Note: Descriptions are shown in the official language in which they were submitted.
3 "
1~53-59~1I
SPECIYIC~TION
The present invention relates to photoelectric
input apparatus; more particularly, to touch input panels
having a series of crossed light beams, in which the
interruption of a pair of crossed light beams identifies
the position of an object in the plane,
Photoelectric touch input panels have been devel-
oped which use a plurality of crossed light beams, arranged
in sets of parallel beams in a single plane, to identify
the approximate position of an object which breaks both of
two crossing beams. Typically, such touch input panels
are intended to be used in front of a display device such
as a cathode ray tube, and the position of an operator's
finger when it touches a spot on the cathode ray tube is
detected by determining which two crossed beams are simul-
taneously interrupted. At times, the touch input panel
is used witha stylus or other device in place of a finger.
The resolution with which the position of the finger or
stylus can be determined is dependent largely upon the
spacing of the parallel beams in the beam plane and the
width of the finger or stylus. The beams must be spaced
`- apart by a distance which is small enough to insure break-
ing at least one beam by the srnallest size finger or
stylus, and, accordingly, it is frequently the case that
; 25 multiple beams are broken. In previous touch input panels,
the output is produced by an indication of the first beam
which is recognized as being broken, scanning from one
direction toward the other (for example, ~rom the top
down), and this results in determination of a position
., 30 which is not the position corresponding to the center line
'
of the finger or stylus. Accordingly, it is desirable
to provide a way of determinirlg the appro~imate center
point of the finger or stylus if more than one of a
series of parallel beams is broken.
~n previous touch input panels, it is possible
for a relatively small foreign object, such as an insect,
a raindrop or debris, to cause a false indication of an
input by passing through the beam plane. It is, there-
fore, desirable to provide a mechanism for discriminating
against foreign objects which happen to pass through the
beam plane of the device.
In previous touch input panels, a relatively com-
plicated arrangement is required for controlling operation
uf the panel. It is desirable to simplfy, as much as
possible, the logic and electronic circuits required in the
use of the panel to enable the panel to be produced with as
much economy as possible, and to increase the reliability
of the panel.
Previous touch input panels, while useful for
determining the position of an object in a beam plane,
are not capable of sensing any additional data relating to
such input, such as the velocity of approach of the
object toward the touch panel. It is sometimes desirable
to be able to discriminate the velocity of approach of an
object which intersects the beams in the beam plane, in
order to insure with greater certainty that an actuation
of the touch input panel in an intentional actuation by
means of a finger or stylus, rather than an accidental
operation. It is, therefore, also desirable to provide
some means o sensing the veloclty of approach of an
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object which intersects the beams and the beam plane.
Previous touch input panels are adapted to scan
through the entire population of each set of beams on
a sequential basis, and therefore each individual beam
is scanned relatively infre~uently. This establishes a
time interval of uncertainty as to whether a beam is
interrupted or not. It is desirable to reduce this time
interval, and increase the scanning rate for one or more
specific beams which are of greater significance, or which
are more likely than others to be interrupted.
Previous touch panels are not well-adapted to
operation in more than one mode. Typically, they
operate in a point mode, in which points are identified
by decoding the X-Y coordinates of a broken beam pair,
without recognizing additional points which may be legiti-
mate inputs until after a condition is recognized in which
no beam is broken. It is desirable to avoid this limita-
tion and permit multi-mode operation of the touch panel.
Previous touch panels have not been well-adapted
to recognize and detect more than one pair of interrupted
beams at a time, which severely limits the usefulness of
the panel. It is desirable to provide an arrangement in
which a number of interrupted crossed beam pairs are
reco~nized. ~his makes it possible to use touch input
panel control apparatus to perform a variety of tasks
such as sizing, space monitoring, and protection inter-
lock activities.
Previous touch panels have not been able to
discriminate between touch inputs (by ~ finger or stylus)
which move normally to the touch panel. It i5 desirable
to be able to distinguish between normal or skew approaches,
particularly in applications where high resolution of the
touch input is required.
Prevlous touch panels have been required to use
comparators for determining, in each beam plane, whether
a beam detected as being interrupted is different from
the last detected beam. It is desirable to provide an
arrangement which makes the use of such comparators, and
other associated logic, unnecessary.
It is a principal object of the present invention
to provide a touch input panel with means for determining
the approximate center point of an object which intersects
more than one beam of a plurality of parallel spaced beams
in a beam plane.
It is another object of the present invention to
provide improved logic apparatus for decoding the position
of an object which is detected within a beam plane.
Another object of the present invention i5 to
provide means fGr sensing the presence of a finger or
stylus or other elongated object, and distinguishing such
object from an object of shorter dimensions.
A further object of the present invention is to
provide means for determining the velocity of approach
of an object which is detected within the beam plane,
or a change in velocity of the object during its approach.
Another object of the present invention is to
provide means for selectively scanning particular beams
with increased frequency relative to the scanning of
the beams.
A further object of the present invention is to
;~,r?t~(J~3r ~
provide means for scannin~ interrupted beams more fre-
quently than non-interrupted beams.
~nother object of the present inven~ion is to
provide apparatus for enabling the control apparatus of
5 the present invention to function selectively in a point
mode or in a stream mode. 2
A further object of the present invention is to
provide apparatus for enahling the control apparatus of
the present invention to monitor plural pairs of crossed
interrupted beams.
Another object of the present invention is to
provide a plurality of beam planes and apparatus for
counting the number of interrupted beams in each set
of beams defining each beam plane.
A further object of the present invention is to
provide apparatus for sizing objects within a space defined
by a plurality of beam planes.
Another object of the present invention is to
provide apparatus for monitoring activity within a space
defined by a plurality of beam planes.
A further object of the present invention is to
provide apparatus for monitoring specific locations within
a space defined by a plurality of beam planes and for
inhibiting operation of dangerous instrumentalities in
response to detection of an interrupted beam pair at
such location.
A further object of the present invention is to
provide apparatus for detecting the approach of a finger
or stylus toward a touch panel in a normal direction and
discriminating against an anyled approach,
-6- 61253-5961I
A further object of the present invention is to
provide an improved arrangement for Inountiny a pl.urality of
LED's associated with a sinyle beam planc.
According to one aspec-t, the present :invcntion pro-
vides for use in a photoelectric input device, an inteyrated
structure having a plurality of active elernents arranyed in a
row on a common semiconducting surface, means for supporting
said surface in position relative to a space so that said active
elements are each aligned with one of a set of light beams tra-
versing said space, said active elements each being spaced apartby the distances between adjacent light beams of said set and
means mounted on said structure for establishing elec-trical con-
tact between said active devices and apparatus located external
to said structure.
The invention will now be described in greater detail
wi-th reference to the accompanyiny drawinys in which:
Figure 1 is a perspective view of a portion of a
housiny of a touch input panel incorporating an exemplary embodi-
ment of the present invention, illustrating devices associated
with plural spaced crossed beams in a principal beam plane and
plural spaced beams in an auxiliary beam plane;
Figure 2 is a functional block diayram of a control
system for the apparatus of Figure 1, illustrating the appara-tus
for detecting and counting the number of broken beams, for
detectiny the coincidence of beam interruption in the principal
and auxiliary planes, and for determining the velocity of
approach of an object toward the principal beam plane;
Figure 3 is a perspective view of an alternative em-
bodiment of the present invention, incorporating spaced X and Y
beam planes;
Figures 4a-4c are views of arrangements for mounting
a plurality of LED's or pho-totransistors;
~5(~'9Z~3
- 6a - 1253-5961I
Figure 5 is a functional block diayram of a control
system for an alternative embodiment of the pre.sent invention,
having two X beam planes spaced on opposite sides of a Y
beam plane;
Figure 6 is a functional block diagram of a control
system for a further embodiment of the present invention
adapted for counting the number of consecutive interrupted
(J~3
beams in eAch bearn plane ar,d determining the address o
the center line of the interrupting object;
Fig. 7 is a functional block diayram of another
embodiment o~ the present invention adapted for scanning
back and forth in each beam plane across an interrupting
object, without scanning beam paths which are remote
from the interrupting object;
Fi~. 8 is a perspective view of another embodi-
ment of the present invention adapted for monitoring a
space defined by a plurality of beam planes;
Fig. 9 is a functional block diagram of a logic
circuit used with the apparatus of Fig. 8; and
Fig. 10 is a functional block diagram of a control
circuit for enabling the apparatus of the present invention
to be selected for stream mode or point mode operation.
Referring now to Fig. l, there is illustrated in
diagrammatic form a housing 10 which contains the control
system for operating a touch input panel. The housing 10
has a central opening 12, and the housing 10 is adapted
to be placed in relation to a display surface on the front
of a display device ll, which may be a CRT or other dis-
play device, so that a display is visible in the opening 12.
The opening 12 is bounded by two side walls 14 (one of which
is shown in Fig. l) and upper and lower walls 16. One of
the side walls 14 is equipped with a plurality of light-
emitting devices such as LED's or the like, and the oppo-
site wall is equipped with a plurality of photosensitive
devices such as phototransistors or the like. The photo-
transistors are aligned with the LED's and are adapted to
. 30 receive light generated by the L~DIs. There is a lens
f ~
provided for eah of th~ LED's to collimclte the light
and focus it princip~lly on on~ of ~Jc phototransistors
on the OppOsite wall. The path bet~Jeen an LED and th
phototransistor ~n the opposite wall upon which the LED's
light is focused is referred to as a beam. There are a
plurality of such beams which originate at one of the side
walls 14 and ~erminate at the opposite side wall 1~, and
these beams are arrange,~ in parallel spaced relationship
so that a person or operator who touches a panel located
hehind the opening 12 will intercept one or more of ~he
beams. The beams are arranged in a plane which is refer~
red to as a beam plane.
A second set of spaced parallel beams extends
between the upper ~d lower walls 16, with each of such
beams having a light-generating LED at one end and a
phototransistor at the other end. The beams extending
between the side walls 1~ are referred to herein as the
X beams, and the beams extending between the upper and
lower walls 16 are referred to as the Y beams. The X and
Y beams may be oriented in any direction with respect to
the horizontal and vertical. The plane of the X beams
( is referred to as the X beam plane, and the plane of the
Y beams is referred to as the Y beam plane. When the X
beam plane coincides with the Y beam plane, the plane is
referred to as the principal plane.
In the apparatus of Fig. 1, a principal plane is
formed near the rear of the opening 12, with crossin~ X
beams and Y beams in that plane. An auxiliary X beam
plane is spaced forwardly of the principal plane, near
the front of the opening 12. It~ plane is referred to as
8 -
the auxiliary plane. The location of the principal plane
is identified in Fig. 1 by the apertureS in the 10~,7er
wall 16 and the rear~ard line of apertures in the side
wall 1~. The forward line of apertures in the side ~7all
14 defines the auxiliary plane. The auxiliary plane is
spaced far enough from the principal plane so that a small
foreign object which happens to be present in the opening
12 cannot intercept beams in both the principal plane
and the auxiliary plane. Coincidence of principal and
auxiliary beam interruption can, therefore, be used to
confirm that an interrupted beam is not caused by a small
foreign object. This feature is of particular value when
the invention is used in environments such as aircraft
cockpits, outdoor terminals, etc.
Foreign objects ~such as insects) which are large
enough to break beams in both the principal and auxiliary
planes simultaneously can be discriminated against on the
basis of their characteristic velocity of approach toward
¦ the principal beam plane, as described hereinafter. This
is accomplished by determining the time interval between
a beam interruption in the auxiliary plane and a beam
interruption in the principal plane, and inhibiting the
device from recognizing a valid input unless that interval
conforms to prescribed values.
The X beams in the auxiliary plane are horizontal-
ly aligned with the X beams in the principal plane. This
fact is made use of in order to require that corresponding
X beams in both the principal and auxiliary planes are
interrupted simultaneously in order to recognize a valid
input. This requires an operator to touch the panel at
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I
¦ the front of the display ~evice 11 in ~Uch a way that
his finger or stylus e~tends generally normally to the
panel, as far as the X beams are conce~ned. By dis-
criminating against inputs which interrupt non-corr~spond-
ing X beams in the principal and au~iliary planes, the
apparatus is able to discriminate against fingers or
styli which approach the panel in an oblique direction
as far as the X beams are concerned. Since the only set
of ~ beams is in the principal plane, the finger or stylus
may approach the panel at any angle which simultaneously
intercepts corresponding X beams. If a higher degree
of normality is desired, a second set of Y beams can be
provided spaced from the principal plane in order to make
the same coincidence requirement for the Y beams as has
been described above in connection with the X beams.
When an extra Y beam plane is provided, it is desirable
to space it from both the principal plane and the auxil-
iary X plane, so that three planes are provided. Noting
the time difference of beam interruption in each of the
three planes permits a determination of a change in the
velocity as a finger or stylus approaches the panel. In
other words, the time difference between interception of
beams in the first two beam planes is a function of the
average velocity in that space, and the -time difference
between interruption of the beams in the second and
third beam planes is a function of the average velocity
in that space. The determination of the average velocities
in two adjacent spaces permits an identification of
certain types of movement of the oper~tor's finger or
stylus. This may be usecl as an additional input from
the tou~h input panel, and is at times very significant.
-- I O
For example, if the velocity of a finger decreases more
than usual as it approaches the panel, it may indicate
a degree of uncertainty on the part of the operator as
to what part of the panel is to be touched. Recognition
of this fact may be employed to select an appropriate
program for the circumstance. For eY.ample, when the
touch input panel is employed with a programmed learning
device, one subsequent program may be selected when the
response indicated by the touch input is correct and
certain, and a different program may he selected when
the touch input is correct, but hesitant.
Referring to Fig. 3, an alternative embodiment
of the present invention is illustrated. In the
embodiment of Fig. 3, there is one set of X beams and
one set of Y beams, which have been separated so that
there is no principal plane. The separation of the X
and Y beam planes permits the apparatus to discriminate
against small insects, and to calculate the difference
in time between interruption of the beams in the two
auxiliary planes. It is not capable of requiring that
inputs be made in a direction normal to the panel, as
is the apparatus of Fig. l, but has the advantage of
greater simplicity.
Referring now to Fig. 2, there is shown a
functional block diagram illustrating a control system
which may be used with the apparatus of Fig. l.
A clock pulse generator 20 is provided which
produces repetitive pulses. The pulses produced by the
generator 20 advance a counter 2~, which functions as
. 30 a s~an counter for the X and Y beams, It is a binary
-- 11 --
counter and in the illust~atiun of Fig. ~ i5 a multi-
sta~e counter, The output lines ~6 frorn ~our stayes o~
the counter 24 are four in number, as identified by the
slash and the numeral 4. A larger counter (having si~
or more stages, for example) may be used for larger
panels and when greater resolution is desired. The lines
26 are connected to four input terminals of a latch unit
28, which functions to latch the data presented on
the lines 26 when a latch signal appears on a line 30.
The latch outputs of the latch unit 28 are presented on
a group of four lines 32 to a decode unit 34, which has
sixteen output lines 36 connected to indi~idual LED's on
one o~ the side walls 14, to generate the X beams 35.
A gate pulse referred to as the LED gate is supplied
from a fifth stage of the counter 24 to the decoding
unit 34 over a line 38, so that an LED selected by the
decoding unit 34 is fired only for the duration of the
LED gate pulse on the line 38. Preferably, this duration
is a relatively small period within each cycle of the
highest frequency output signal supplied to the output
lines 26, so that the LED's operate with a low duty cycle
and have relatively high light output in relation to
the aYerage power consumed by the LED's. This increases
the efficiency and reliability of the LED's. The output
lines 32 are connected over lines 40 to a series of output
terminals (not shown) which identify the address of the
LED and the beam being energized at any given time.
These terminals may be connected to a microprocessor or
other computing apparatus as an input.
Two of the four lines 32 are al50 5upplied to a
set of group selcct gates 33 for sclccting onc or another of several groups
of phototransistors 35 (four in the embodiment of Eigure Z)- ~f all of the
phototransistors in the selected group, only one receivcs light from the
LED ~hich is energized at that time, so that tl~e composite signal from a
selected group of phototransistors reveals that the beam originated ~.lith
the LED currently being energized is not interrupted. This signal appears
on a line 42, which leads to the input of a threshold detector apparatus 44.
A suitable threshold detector apparatus is described and claimed in the
Carroll et al United States Patent No. 4,243,879 for Dynamic Level Shifter,
issued ~lay 12, 1981. When a signal is received on the line 42 ~Jhich indi-
cates that a beam has not been interrupted, the threshold device 44 pro-
duces a signal on a line 46. The line 46 is connected to the D input of
the D flip-flop 48. The clock input of the D flip-flop is connected to
the LED gate line 38, so that the flip-flop 48 is set at the trailing edge
of the LED gate pulse on the line 38 if a non-interrupted beam signal has
been received on the line 42. This sets the flip-flop 48 so that its Q
output is lo~.
-In its reset condition, the Q output of the flip-flop 48 is high
and this is conveyed to the line 30 which causes the latching operation
of the latch unit 28. This causes the output lines 32 of the latch unit 28
to manifest the address of the last LED which was ener~ized subsequent to
receipt of a non-interrupted beam signal on the line 42.
When a beam is interrupted, there is no signal
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.
J~J~
produced on the li,ne ~6, and the flip~fl~p ~ is reset
at the end of the LED gate pulse. It rernains reset as
long as that beam remains in~errupted. This causes the
latch unit 28 to remain latched at the address of the
LED associated with the interrupted beam, and this
address is made availa~le to ex~ernal devices over the
line 40. The line 60 is also connected by way of the
line 62 to an external device, to indicate that an X
beam interruption has been recognized.
Since the latch unit 28 remains latched to the
address of the LED associated with the interrupted beam,
this LED,is pulsed repetitively at the LED gate pulse
time by one of the lines 36 until a non-interrupted beam
si~nal is received on the line 42. Scanning then resumes
until the next interrupted beam is found. The counter 24
runs continuously during this time. The output on the
lines 40 continuously indicates the address of the LED
associated with the interrupted beam, and the signal on
the line 62 indicates that it is an interrupted beam.
The same apparatus is repeated for the Y beams,
using the same counter 2~. A separate latch unit 66
i5 provided for the Y beams. A separate threshold
detector 68 is employed for the phototransistors associated
with the Y beams, and a separate output flip-flop 70 is
also provided ~or the Y beams. Output lines 72 from the
latch unit 66 identify the address of an LED associated
with an interrupted Y beam, and a signal from the flip
~lop 70 on a line 74 indicates that the address is one of
an interrupted beam, When both of the lines 62 and 74
axe high, it si~nifies that X and Y beams have both been
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~ f~d ~
broken, and the coordinates of the t~"o interrupted bearns
are available on the lines ~0 and 72. The LED for the
interrupted Y beam is repetitively pulsed, at the rate
of the clock generator ~0, as described above in connec-
tion with the X beam, and this continues until the beamis recognized as non-interrupted.
The continuous pulsing of the interrupted beams
provides a different pulsing rate for interrupted beams
than for non-interrupted beams. Until a non-interrupted
beam is recognized, each beam is pulsed once for every
sixteen cycles of the clock pulse generator 20 (assuming
a touch input panel having sixteen X beams and si~teen Y
beams). When a beam is interrupted, however, the inter-
rupted beam is pulsed once during each cycle of the clock
pulse generator 20, sixteen times higher than formerly.
This provides a markedly increased ability of the
apparatus to detect when a touch input has been terminated.
This allows a touch input panel of the present invention
to be used much more rapidly than conventional touch
input panels, which cannot recognize the termination of
a touch input until after as many as sixteen cycles of
the clock pulse generator. The speed of operation
achieved by the apparatus of the present invention makes
it possible for an operator to make multiple inputs in
~5 a point mode by rapidly withdrawing and then repositioning
his finger on the panel, and allows rapid finger motion in
a stream mode, in which a succession of output coordinates
is generated without lifing the finger or stylus from
the panel, Because the movement of the finger away
from the interrupted beam i5 recogniæed almost instantly,
it is not necessary for the operator to withdraw his
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i
~ 3~q3~ ~
I
i
finger and wait for si~een cloc~. pUlS~ cycles to go b~
before making another finger input.
As thus far described, t~e apparatus of ~ig. 2
may be employed with the apparatus of Fig. 3, in which
there is only one set of X beams and one set of Y beams.
In the apparatus of Fig. 1, a second set of X beams is
required for the auxiliary plane, and the apparatus
associated with the second set of X beams will now be
described.
The LED's of the auxiliary plane are connected in
common with corresponding X LED's in the principal plane,
directly from the X decode unit 34. The outputs of
the phototransistors of the auxiliary plane are treated
separately.
Driving the LED~s of the principal and auxiliary
X planes ~rom the same decode unit 34 effectuates a
savings of structure, and permits a construction in which
only a small additional amount of structure is required
for the auxiliary X plane.
A separate threshold detecting circuit 80 is
provided for the auxiliary X phototransistors, and a
flip-flop 82 is set by the trailing edge of the LED gate
pulse when the detector ~0 produces a signal indicating
that a beam is broken in the auxiliary X plane. An
AN~-gate ~4 is connected to the outputs of the flip-flops
48, 70 and 82, so that when they are all set, as when a
finger or stylus has interrupted corresponding X beams
and at least one '~ beam, an output is produced indicating
that a normal input ls read~.
The X decode unit 3~ operates to energize the
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iz5~gz3
LED~s for both the principal and auxiliary X planes,
so that corresponding beams in both planes are energized
simultaneously. Since the X latch was last set following
detection of an interrupted beam in the principal plane,
only the interrupted beam in the principal plane and
the corresponding beam in the auxiliary plane can be
pulsed. When both of those beams are broken, the flip-
flops ~8 and 82 are both set, indicating that a finger
has approached the panel normally as far as the X beams
are concerned.
When a finger approaches the panel in a direction
which does not intercept the same X beam in the principal
and auxiliary planes, only the flip-flop 48 can be reset.
The outputs of this and the flip-flop 82 are connected
to two inputs of an exclusive ~R-gate 86, the output of
which is connected to an input of an AND-gate 88. The
second input of the AND-gate 88 is connected to the output
of the flip-flop 70,which is set when a Y beam is broken.
When the AND-gate 88 is operated, a signal appears on an
output line 90, signifying that a skew input is present.
A skew input is one which breaks a Y beam, but does not
break both of the X beams. This output line can be
employed to trigger a message on the screen of the dis-
play device 11, indicating to the operator that he must
place his finger or stylus more normal to the surface of
the panel.
A counter 92 is provided for measuring the time
difference between the arrival of a finger or stylus
in the auxiliary and principal planes. It receives
timing pulses through an AND-gate 94 from a timing
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~ s~
clock pulse source ~6, provl~ing that a flip-flop 98 is
set. The flip-flop 98 is set by a sign~l on the line 100
from a monostable multi-vibrator 102. The rnultivibrator
102 ~urnishes a signal in the line 100 for a short period
after the flip-flop 82 is set, indicating that an objec~
has arrived at the auxiliary plane. When the object
arrives at the principal plane, the flip-flop 70 is set,
and a short duration signal is produced by a second
monostable multivibrator 104 on a line 106 to reset the
flip-flop 98. Accordingly, the counter 92 counts pulses
from the source 96 only for the period between interruption
of the beam in the auxiliary plane up until interruption
of the beam in the principal plane. The output of the
counter is connected to a comparator 105 which compares
the content of the counter with value stored in storage
device 107. If the content of the counter is less than
the value stored in the storage device 107, an output
line 108 is energized, otherwise, an output line 110 is
energized. The output line 110 activates a comparator
; 20 112, which compares the output of the counter 92 to the
value stored in a second storage device 114. If the
( content of the counter is larger than the value stored
~ in the storage device 114, a line 116 is energized and
¦ otherwise, a line 118 is energized. Accordingly, the
outputs on lines 108, 116 and 118 indicate respectively
that the time between interruption of the auxiliary and
principal planes is less than Tl, is between Tl and
T2, and is greater than T2. The line 116 is connected
to one input of an AND-gate 120, the other input of
~hich is connected to the output of the AND-gate 84.
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The output of the AND-~ate 1~0 indicates a norrnal input
within the speed range specified by the time values Tl and
T2. This output can be used to control selection of a
program which can inform the operator, through the dis-
play panel, that the input is not recognized because thespeed of movement of the finger or stylus was too fast
or too slow. Alternatively, the several outputs on
lines 108, 116 and 118 can select programs of operations
which are suitable to inputs which are made rapidly, or
slowly. In self~teaching devices, this may be especially
significant, because instruction programs may be chosen
in response to whether an input is delivered slowly and
hesitantly, or rapidly, with certainty. The gate 120
can be connected through an OR-gate to the lines 108 and
118 instead of to the line 116, to discriminate against
a range of velocities corresponding to the time Tl and
T2,
The velocity discrimination available by the
signals on the lines 108, 116 and 118 is usable to dis-
tinguish between valid inpuks through the use of a
stylus or finyer, or through the accidental presence of
another relatively large object, such as a moth, which
is large enough to brea~ beams in both the principal
and auxiliary planes.
Fig. 5 is a functional block diagram of an
alternative arrangement of the present invention having
two separated X beam planes. This gives three distinct
planes, with two X beam planes and one Y beam plane. In
the apparatus illustrate~ in ~icJ. 5, the Y bearn plane is
interposed between the two X beam planes which are
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referred to as Xl and X2.
The counter 24 is connected to the latch unit 28
¦ in the same manner as described in connectiOn with Fiy, 2,
for the Xl plane. A separate latch unit 200 is provided
for the X2 plane, and it is connected through a multi-
plexer unit 226 to a decode unit 202, which provides six-
teen output lines for separately energizing the sixteen
LED's of the X2 plane. Since separate latch units 28
and 200 are provided for ~he two X pl~nes, the~ are
capable of latching the address of two separate inter-
rupted beams in the Xl and X2 planes, when they are inter-
cepted by an object which is not moving normally to the
panel. In this way, the interruption of the beam in
either the Xl or X2 planes does not prevent the recogni-
tion of the interruption of a non-corresponding beam in
the other plane.
Three threshold detection devices TD and three
output flip-flops are provided 48, 70 and 82, just as in
the apparatus of Fig. 2.
The output of the flip-flop 82 is connected
through a monostable multivibrator 102 to set the flip-
flop 98 and the output of the flip-flop 70 is connected
through a monostable multivibrator 104 to reset the
flip-flop 98. It causes the counter 92 to be counted
up to a value corresponding to the time difference be-
tween beam interruptions in the X2 plane and the Y plane.
The monostable multivibrator 104 is also con-
nected to set a flip-flop 204, which is reset by a multi-
vibrator 206 ener~ized ~ th2 flip-flop 48. While the
fli,p-flop 204 remains set, an AND-gate 208 i5 activated
20 -
3L~ 23
to pass pulses from the timiny clocik source 96 to a
counter 210. Accordingly, the counter 210 is counted
up to a value corresponding to the time difference be
tween interruption of beams in the Y plane and the Xl
plane. The content of the two counters 92 and 210 is
conveyed to a subtraction unit 212, the output of which
is connected to a comparator 214 which compares the
result of the subtraction with the value stored in a
storage device 216. An output line 218 identifies the
sign of the difference, which indicates ~"hether the
velocity is increasing or decreasing as an object
approaches the panel, and two additional output lines
220 and 222 indicate whether the time difference is
greater or less than the time difference stored in the
storage device 216.
If it is desired to produce outputs responsive
to the relative change in velocities as a finger or
stylus approaches the panel, a dividing unit can be
substituted for the subtraction unit 212, whereupon the
result is not the difference betweenthe times, but the
relative length of the times. This result can be
( compared with a standard value stored in the storage
unit 216, whereupon the signals on the output lines 220
and 222 indicate whether the change in velocity is
above or below a specified value. The signal on the line
218 would be produced in response to a comparison with
unityin a comparator (not shown) and would signify a
condition of increasing or decreasing velocity.
The various outputs available from the apparatus
. 30 o~ Fig. 5 can be used in the same manner as described in
- 21 -
~ 3~ ~
connection with the apparatu5 of Fig. 2, narnely, to con-
trol selectlon of pro~ramS, in r~spon5e to the observed
conditions. In the apparatus o~ bot~l Fig. 2 and Fig. 5,
it is apparent that the counting, th~ subtraction or
division, and the comparison can take place by suitable
programming of a microprocesSing unit or other computer,
in which the storage devices 107, 11~, 2!6, etc. are
contained in the computer's mernory unit.
In any arrangement in which multiple X beams are
employed, it is preferable to place the LED's ~or one X
beam plane and the phototransistors ~or the other X beam
plane on a single side 14 of the opening 12. The other
LED's and phototransistors would ther, be placed in corres-
ponding positions on the other side 14 of the opening
12. In this way, there is less likelihood of interference
between the LED's of one beam plane and the phototransis-
tors of the other. When multiple Y beam planes are pro-
vided, a corresponding arrangement is also desirable for
the same reason.
In Fig. 5, and AND-gate 224 has its three inputs
connected to the outputs of the flip-flops 48, 82 and 70,
and produces an output when all three flip-flops are set.
Since the flip-flops 48 and 82 may be set due to the
interruption of non-corresponding beams, the output of the
gate 224 does not necessarily indicate a normal input,
but does indicate that an input is ready, and that it is
long enough to intercept all three beam planes. The
presence of a normal input can be identified, however,
b~ means of apparatus which will now be described.
The multiplexer 226 has two se-ts of inputs
- 22 -
i
connected respectlvely to the outputs ~f the %1 latch 22
and the X2 latch 200. Its output lines 228 are connected
to the X2 decode unit 202~ A control line 230 is con-
nected to the multiplexer unit 226 for selecting the
output of the Xl latch 28 or the X2 latch 200 to be decoded
by the unit 202, Normally, the multlplexer 226 selects the
output of the X2 latch, and when it does, the flip-flops
48 and 82 can be set by the breaking of non-corresponding
heams. When the condition of the multiplexer 226 is
changed, however, to select the output of the Xl latch
28 for use in the X2 decode unit 202, corresponding beams
in the Xl and X2 planes are pulsed simultaneously, and
then the flip-flops 48 and 82 can be set only when
corresponding beams are simultaneously interrupted. An
AND-gate 232 has two of its three inputs connected to the
outputs of the flip-flops 48 and 82 and its third input
to the multiplexer control line 230. Thus, when the
multiplexer 226 is caused to select the output of the
Xl latch 28, the gate 232 is enabled and produces an
output when both the flip-flops 48 and 82 are set. With
the multiplexer control lines 230 high, this can occur
! only when corresponding X beams are broken, so that the
output signifies that the input finger or stylus is normal
to the touch panel.
Reference will now be made to Fig. 6, in which an
embodiment is illustrated which provides a means for
counting the number of broken beams, and determining the
center point of the object which is interrupting the
beams. A clock pulse generator 20 is connected to a
counter 24, and the counter 24 is connected to X and Y
decode units 34 and 67, just as described above in
- 23 -
1~5~'~3,.3
relation to Fig 2. The ccjunt~r 24 procluces an output
on a line 311 at the end of each scan cycle. Since
the apparatus provided for the Y beams is identical to
that provided for the X beams, it will suffice to describe
only the apparatuS associated with the ~ beams, it being
understood that this structure is duplicated for the Y
beams.
The threshold detector 44 is connected to the
flip-flop 48. The flip-flop 48 is reset when a beam is
interrupted as has been described above. Its output on
the line 60 is connected to the set input of an RS flip-
flop 302, which is set as the first interrupted beam is
detected during each scan. A line 304 is connected to
its reset input, ~nd it is provided with a pulse on
the line 311 at the end of each scan cycle for resetting
it preparatory to a subsequent cycle of operation. The
output of the flip-flop 302 is connected to the latch
input of the latch 306, so that the output of the
counter 24 is latched to identify the first interrupted
be~m, when the first interrupted beam signal is received
At the input of the flip-flop 48.
The output of the flip-flop 48 is also connected
to a ~ate 308 which receives LED gate pulses at its
other input. The output of the gate 308 is connected
to the input of a counter 312 which is reset by a pulse
on a line 311 at the end of each scan cycle. Accordingly
the counter is reset to zero during the early portion of
the scan cycle, and begins to count the LED clock pulses
following resetting of the flip-flop 48, ancl is incre-
mented to a content o~ unity on the second interrupted
- 2~l -
beam. The counter 24 continues to be incremented by the
clock pulse generator 20, so that the decoder 34 con
tinl~es to energize successive beams, after the first
interrupted beam is detected. For each additional beam
which is intercepted, the gate 308 produces an output
which is counted by the counter 312. ~1hen the ~irst
following unin~errupted beam is recognized, the flip-
flop 48 is set, and an input is applied fro~ the line 60
through an inverter 314 to the control input of a latch
unit 316, whereby the content of the counter 312 is
latched. The output of the inverter 314 is connected to
one input of an AND-gate 318, the other input of which
is connected from the Q output of the flip-flop 302.
Since the flip-flop 302 is set following detection of
the first interrupted beam, both inputs to the gate 318
are high for the first time when the last of the series
of interrupted beams has been detected. Its output on
a line 320 signifies the end of a series of interrupted
beams. The line 320 is connected to the control input
of a shift unit 322 which is adapted to receive the data
stored in the latch 316 and shift it ri~htwardly one
position, which results in the binary ~uantity being
di~ided by two. It is then output on lines 324 which
are connected to one input of an adder unit 326. The
other input of the adder unit is connected to the output
of the latch unit 306 by lines 328. The output of the
adder appears on the lines 330, and represents the identi-
fication of the first interrupted beam (stored in the
latch 306) increased by half the number stored in the
counter 31~. It thus identifies the midpoint of the
. . . _
25 -
sequence of interrupted beams which have been broken.
It is possible by this means to attain very high resolu-
tion with the touch input panel by closely spacing the
beams in the beam plane, even when the beams are broken
by a finger which is large in width compared to the
inter-beam spacing.
The outputs which are available from the apparatus
of Fig. 6 are the identification of the center line of
the finger or stylus (on the lines 330), an indication
that the interrupted beam series has ended ~on the
line 320), and an indication that the X beam has been
broken (on the line 60). These signals may be used as
interrupt and data signals for a microprocessor, to
enable the microprocessor to receive and process the
information. Since a duplicate structure is provided for
the Y axis, it is convenient to provide an AND-gate
similar to the AND-gate 84 of Fig. 2 to indicate that an
input is ready when both the X and Y operations have been
completed, such input identifying the X-Y coordinates of
the center point of the interrupting object. This sig-
nal may be produced by anding the line 320 with the
`~ corresponding output line for the Y beams.
It will be apparent that in the apparatus of
Fig. 6, it is necessary to continue scanning the X beams
after the first interrupted beam is detected, in order
to count ~he total number of interrupted beams. In the
apparatus of Fig. 6, the counting continues for a full
cycle, so that the increased pulsing speed of beams
detected as having been interrupted, described in con-
nection with Fig. 2, is not a ~eature of Fig. 6. The
- 26
i
fJ3
apparatus of ~ig. ~ can ~e rnodified, ho~,7ever, to enable
the direction of scanniny to reverse when the total
number of lnterrupted beams have been scanned, to impro~e
the speed of operation of the apparatus. Such a modifi-
cation is shown in Fig. 7.
~ n the apparatus sf Fig. 7, the clock pulsegenerator 20 is connected to t~o separate counters 352
and 354 for the X and Y beams. sOth counters are up-do~,m
counters, and the direction of counting is separately
controlled by a control line in each case. The control
line for the X counter 352 is the line 353.
The clock pulse generator 20 counts the counter
352 upwardly, via a frequency divider 355, which produces
the LED gate pulses. The content of the counter is decoded
by the X decoder 34 to energize the LED's for the X beams.
The output of the phototransistors is connected to the X
threshold detector 44, and operates the flip-flop 48. This
much of the operation is similar to that which has been
already described above. The Q output of the flip-flop 48
is connected to the toggle input of a flip-flop 358.
This sets the flip-flop 358 and causes the latch unit 306
to be latched to hold the ~ddress o the interrupted
beam.
A gate 360 is connected to the Q output of the
flip-flop 48 and to the LED gate pulses for causing the
counter 312 to count the number of interrupted beams.
It receives a third input from the Q output of a flip-flop
361, The function of the flip-flop 361 is to control the
dixection of counting o the counter 352. This output
is hi~h when the counter is coun~ing upwardly in its
_ - 27 -
U~23
normal direction, so that the counter 312 i5 enabled to
count the interrupted heams which are encount~ed after
the first interrupted beam, while the counter is counting
in its normal upward direction.
The Q output of the flip-flop 48 is connected to
the toggle input of the flip-flop 361. The Q output of
the flip-flop 48 goes high when the first non-interrupted
beam is encountered following a series of interrupted
beams, and this causes the flip-flop 361 to be reset.
The resetting of the flip-f.lop 361 disables
the counter 312 and causes the counter 352 to begin to
count downwardly, and therefore again scans the inter-
rupted beams in the reverse direction. When the first
interrupted beam is reached, the flip-flop 48 is reset,
and its Q output goes high. This output sets the flip-
flop 358 to terminate the output ready signal. When all
of the interrupted beams have been scanned, eventually,
a non-interrupted beam will be reached, and at that
time, the flip-flop 48 is set and its Q output goes high.
This sets the flip-flop 361, to resume upward counting
of the counter 352. The flip-flops 48, 358 and 361 are
resotred to their initial condition at the beginning of
the scan. The Q output of the flip-flop 358 operates
to ~eset the counter 312 over a line 313, preparatory to
makin~ a new count of the number of interrupted beams on
the next successive scan. The output of the counter 312
is connected to the latch 316, which is operated by
inverter 364, which receives its input from the Q output
of the flip-flop 361. Accordingly, the latch 316 is
operated after the full set of interrupted beams has
been scanned and the ~lip-flop 361 is reset in order to
_ .
- 28 -
cause the counter 352 to count downwardl~. ~n ~lD-gate
366 has its inpu-ts connected to the output of the inver-
ter 364 and the ~ output of the flip-flop 35~ to identi~y
that a count is ready. The content of the latch is
preferably shifted by means of a shifter as shown in
Fig. 6 and added to the data stored in the latch 305,
in the manner described in connection ~7ith Fig. 6 to
identify the center line of the operating finger or stylus.
I'he flip-flops 358 and 3~1 are reset and set, respectively,
by the pulse on the line 311 whenever the end of scan is
reached, to insure that their operation rernains synchron-
ized.
The apparatus of Fig. 7 operates faster than that
of Fig. 6, because it scans only the interrupted beams
backwardly and forwardly and provides an output of the
center line of the interrupting object during each
upward scan. Although, in the apparatus of Fig. 7, the
data which might be acquired during downward scans is
ignored, it will be appreciated that the apparatus
can be modified to make use of this data as well. Such
a modification would involve latching in the latch unit
306 the highest address of an interrupting beam (at the
end of the upward scan or beginning o~ the downward scan),
resetting the counter 312 at the beginning of the down-
ward scan, counting the number of interrupted beams dur-
ing the do~nward scan, shifting the data stored in the
counter at the end of the downward scan and subtracting
it from the data in the latch 306 to arrive at the
identification of the center line of the interrupted beam.
. 30 It is apparent that other latches ~not shown) may be
provided for holding da~a 50 that valid outputs are
- 29 -
available to an output device without any particular
need for synchronization with the operation of the
upward and downward scanning apparatus.
It will be appreciated that, in the arranyement
S of Fig. 7, similar structure is provided for the Y beams,
and an AND-gate can ~e provided to and the data ready
outputs of the X and Y circuits to identify when the ~
and Y coordinates of the center point of the interrupting
. object are available for read-out to an e~ternal device.
Referring now to Fig. 4a, a perspective diagram
is illustrated of a plurality of active elements which
may be either $ED's or phototransistors, which are
fabricated in the form of a single integrated structure,
on a strip 378. Several or all of the elements may be
fabricated as integrated circuits formed in a single
semiconducting surface. A plurality of individually
light-emitting areas 380 are provided in spaced relation-
ship along the length of the device, and a plurality of
pins 382 protrude from the bottom of the apparatus in
order to enable easy mounting and replacement of the
structure. The fabrication of plural LED's on a single
( structure makes it possible to control the accuracy of
the spacing of the LED at the time of the manufacture of
the LED units themselves, and substantially decrease the
assembly operations required in construction of a touch
panel apparatus.
Above the strip 378, a second strip 384 is
positioned. It is formed of transparent plastic material,
and it has a plurality of positive lenses 385 integrally
~olded thereinto, spaced apart by distances which
- 30 -
i
~Z~U~3
correspon~ to thc spacin~ of the L~D's 380. The lenses
385 comprise convex surfaces on the upper surface of the
strip 384, while the lower surface of the strip 384 is
planar. The thickness of the strip is such that when it
is laid directly on the strip 378, the lenses 385 are
positioned relative to the LED's to allow for maximum
focusing of the light emitted therefrom. The use of
the lenses 385 in association with the LED effects a
sufficient collimation so that the light from any one
LED is principally focused on a single phototransistor.
This makes it possible to select groups of spaced photo-
transistors since only one of each selected group is
illuminated by the LED which happens to be energized at
any one time. This avoids the necessity of energizing
the LED's and phototransistors in single layers.
Fig. 8 is a diagrammatic illustration of a further
embodiment of the present invention in which the touch
panel mechanism is employed to monitor a space. A
space 408 is indicated diagrammatically in Fig. 8, and
¦ 20 it is surrounded in three separate planes by three
rectangular, hollow housings 402, 404 and 406. The
i housings support light sources and photosensitive devices
on opposite sides, to form crossed beam planes, in the
same manner which has been described above in connection
with touch input panels. In the embodiment of Fig. 8,
however, no touchable panel per se is employed. The
apparatus is used to monitor activity within the space
408. The space 408 may, for example, comprise an animal
cage, in whicll case the apparatus of Fig. ~ is adapted
to monitor the activity of an animal in the cage. The
-31
i
~ 3~
beams which are br~.e~ in t~le ~ ~n~ Y ~irectlons in all
three planes can b~ observed to repr~sent the prGfile of
the animal within the space, distinguish bet~een lying,
sitting and standing attitudes of the 2nimal, determine
the horizontal position of the animal in the cage, and,
in general, monitor its activity. The speed of movement
of the animal in either the X or Y ~irection can be
determined by noting the time difference bet~een break-
ing of successive beams in the beam planes. This is
effectively accomplished by scanning back and forth
across the animal, with the apparatus of Fig. 7 or as
modified to allow meaningful data to be generated scanning
in both directions. The time difference between inter-
ruption of successive beams in a beam plane is determined
by employing counters as in Figs. 2 and 4, but triggering
the counters on and off when successive beams become
non-interrupted. The content of the counter is then
inversely proportional to the velocity component trans-
verse to the beam direction in the beam plane. When
the direction of motion of the animal is not parallel
to either set of beams, the speed of movement of the
animal in any direction may be calculated by vector
addition of the X and Y velocities.
In another application, the apparatus of Fig. 8
may be employed to monitor the activity of a child in a
playpen or a crib. Although the space illustrated in
Fig. 8 is square, the space ~08 need not be square, if
the beams in the cross beam planes are not equally spaced,
or if more beams are provided in one set of cross beams
than in the other. An arrangemen~ wi~h an unequal number
. of beams in the beam plane is easily accommodated by
-- 32 --
the apparatus o~ the pre5ent inverltion, by use of the
set inputs 5~, 58' and 58" ~ig. 2) ~hich enable the
intercepted beam detecting flip-~lops tG be set eY.ternally,
to ignore non-meaningful inputs which may be produced by
the various threshold detectors.
The apparatus of Fig. 8 may also be used to monitor
activity within a larger space, such as a room, where it
may be desirable to maintain a record of movement of
people, animals, or objects The apparatus of Fig. 8 can
! 10 also be employed to monitor movements within dangerous
environments, in such a way as to prevent accidental
injury. For example, when it is desired to monitor activi-
ty around a machine tool, such as a punch press, or other
metal forming or metal cutting machine, the space 408
defines the space around the machine in which an operator
can stand during operation of the equipment. The apparatus
of Fig. ~ senses the position of the operator in relation
to the machine, and may be used to inhibit operation of
the machine when the operator or any part of the operator
moves into a dangerous position. The housings 402, ~04
and 406 are positioned in such a wa~ that the dangerous
positions of the machine are scanned, and it is apparent
that they need not necessarily be stacked in parallel
arrangement as shown in Fig. 3, if an angled relationship
affords a better filling of dangerous areas with crossed
beams. The presence of an operator's hand within a
dangerous area is recognized by the coordinates of the
beams which are interrupted, and apparatus is provided
for disabling the machinery when the interrupted beams are
recognized in these loca~ions.
- 33
The apparatus of Fig. 8 may also be ernployed to
grade or size objects which pass ~ithin the space 408.
This can be accomplished by counting the total number of
X beams broken by any one object, counting the total
number of Y beams broken by any one object and multi-
plying these numbers together to get a result which is
the function of the volume of an object ~hich is entirely
within the space scanned by the three planes of the appar-
atus of Fig. ~. Additional planes may be provi~ed for
greater resolution, if desired, For longer objects,
the objects may be sized by moving through the space 408
with a uniform velocity. The cross sectional area of
the ob~ect may be determined in any of the three planes,
by calculating the product of the total number of X
beams and Y beams which are broken, and integrating the
cross sectional area by repetitive addition while the
object is moving through the space 408. It is apparent
that only a single plane of crossed beams is required
for this application.
The logic circuit associated with the structure
of Fig. 8 i5 illustrated in ~ig. ~. The clock pulse
generator 20 is employed for producin~ pulses which count
: up a counter 412 via a divider 355. The output of the
counter i5 connected to a Y decode unit 414 and to an X
decode unit 416, for decoding the content of the
counter 412 and energizing one of a plurality of LED's
of other light sources. Since the apparatus provided for
the Y beams is identical to that for the X beams, a
description of the apparatus provided for the X beams
will suffice ior both.
- 34 -
~f~
The hol~sin~ 402 is sho~n in ~iq. 9 in cross
section, and it is seen that an LED 418 is contained
within the hollow housing aligned ~ith an aperture which
has a collimating lens 420 superposed over it. Aligned
with the LED 418 and the lens 420 is an aperture 422 in
the opposite side wall of the housing 402, and a photo-
transistor 424 is positioned behind the aperture 422.
The housing 404 and 406 for the other two planes
have a similar structure, but the central plane 4 04 has
the position of its LED and phototransistor interchanged,
to minimize interference between the LED'S of one plane
and the phototransistors of another. Corresponding LED's
of all three planes are connected together so that no
additional lines from the X decode unit 416 are required
for any number of planes which may be provided.
Each of the three planes has its individual
interrupted beam recognition flip-flop 434, 436 and 438,
connected to its threshold detector, so that interruption
of three corresponding beams in the three planes is
independently recoynized.
When a beam in the X3 plane is interrupted, the
clock input to the flip-flop 434 resets the flip-flop,
~nd its Q output yoes high, giving a high level signal
on the output 440, indicating that the X3 beam has been
interrupted. The line 440 is connected to the latch
input of a latch unit 442 which has its data inputs
connected to the output of the counter 412. Accordingly,
the address of the LED associated with the interrupted
beam in the X3 plane is la~ched in the la-tch unit ~42 and
is available a5 an output on lines 44~. A gate 4~6 has
- 35 -
i
its inputs connected to the Q output of the flip-flop
434 and its clock input. The gate 446 produces pulses
which are counted in a counter 450. The counter 45~ is
reset by a reset pulse on a line 311 at the end of each
scan cycle, and i5 counted up from zero to count the
total number of successive beams in the ~3 plane which
are interrupted. This output is available on lines 452.
Similar apparatus is provided for the output flip-flops
436 and 438 of the X~ and Xl planes, and the address of
the first interrupted beam in these planes is available
on lines 454 and 456, with the total number of sequential
broken beams being available on lines 458 and 460. These
various outputs are available to a CPU or other controlling
device, which is adapted to select a specific program of
operations. For example, if the cross sectional area, as
seen in the three X beam planes, is to be calculated, the
outputs of the three oounters, which are available on
lines 452, 458 and 460, may be added. If the apparatus
is designed to determine whether an object is in a certain
defined space (such as an operator's hand in a dangerous
area around a machine tool), an inspection can be made
of whether the X coordinate of the dangerous location is
within the ranges indicated by (a) the outputs 444, 954
and 456 indicating the addresses of the first interrupted
beam in each plane, and (b) the outputs indicating the
total number of sequential interrupted beams in the
three planes. It is apparent that a microprocessor or
other processing device can readily make this determination
and issue an output signal which can halt operation of
the machine when a dangerous condition is recognized.
- 36 -
The apparatus o~ Fiy. ~ is also adaptable to
control by an external computer, in which ca e the scan-
ning means may be energized in any sequence defined by
the computer's pro~ram. When this mode of operation is
desired, the computer controls the voltage levels on
lines 464 and 466. The lines 464 are data lines, for
setting the counter 412 in response to a control signal
on the line 466. When the line 466 is high, the counter
412 operates independently of the clock pulses produced
by the generator 20 and the divider 355. When the line
466 goes high, the counter 412 loads the data from the
lines 464. This causes the counter 412 to be set to the
data provided by the computer on the lines 464, so that
any desired beams can be chosen by providing the appro-
priate data on the lines 464. In this way, special
programs may be executed to scan only areas of interest,
such as dàngerous positions around the machine tool, or
other programs may be executed in which only the area
occupied by a body or object is scanned, to reduce the
response time of the apparatus. Such a program has been
described in connection with Fig. 7. It is apparent
( that an MPU or other computer can be arranged to carry
out, through software, the operations which are performed
by the hardware described in connection with Fig. 7.
As described in the foregoing embodiments, the
apparatus of the present invention is adapted to produce
a stream of outputs corresponding to the beams which are
interrupted at any given time. Under some circumstances,
it is desirable to cause the appLlratus to opcra-te in a
point mode, in which an output is produced iclentifying
- 37 -
the X-Y coordinates o~ only ~he first pair of crossed
beams which are intercepted No other data is output
until a condition is first recogniz~d in which no beams
are intercepted. This mode of operation is sometimes
desirable, in connection with a touch panel, when it is
desired for the operator to execute operations in which
only points are permissible inputs.
An arrangement is illustrated in Fig. 10 in
which the point mode or the stream mode may be selected.
The threshold detectors for the X and Y planes are con-
nected to the X and Y flip-flops 48 and 70 in the manner
described above. The Q outputs of both flip-flops are
connected to inputs of a gate 502 to generate an output
ready signal on a line 504 when both flip-flops have been
reset indicating the presence of i.nterrupted X and Y
beams. The output of the flip-flop 48 is connected to
the set input of a flip-flop 506 which functions to
produce a signal which operates the X latch unit 28
making the address of the interrupted X beam available
on the output 40. Similarly, the output of the flip-
flop 70 is connected to the set input of a flip-flop 510,
the Q oùtput of which is connected to operate the Y latch
66 and make the address of the interrupted Y beam avail-
able on the lines 72. Once the flip-flops 506 and 510
have been set, they cannot be reset until a signal is
available on the line 514. This signal is developed by
a NOR-gate 516 connected to the outputs of the flip-
flops 48 and 70, and resets the flip-flops through OR-gates
525 and 526. A pulse appears on the line 514 only when
.30 both of the ~lip-flops 48 and 70 have been set in response
- 38 -
to recognition of a norl lnterrupted beam. Therefore, the
finger or st~lus must ~e withdrawn so that no beam is
interrupted before the latches 28 and 66 can indicate a
subsequent address.
When a stream mode is desired, a mode selector
input 518 is brought low. This is connected to inputs
of two NOR-gates 520 and 522, the outputs of which are
connected through the OR-gates 525 and 526 to the reset
inputs of the flip-flops 506 and 510. The other inputs
of the NOR-gates 520 and 522 are connected to the Q out-
puts of the flip-flops 48 and 70. ~ccordingl~, when the
line 518 is low, the flip-flop 506 is reset immediately
following recognition of a non-interrupted beam by the
flip-flop 48. When this occurs, the output of the flip-
flop 48 goes low, and the gate 520 produces a pulse which
passes through the gate 525 to reset the flip-flop 506.
Accordingly, the X latch 28 may be latched as soon as
the next interrupted beam is recognized. The same oper-
ation occurs for the Y latch.
The circuit of Fig. 10 makes it possible easily
to select a point mode of operation or a stream mode, so
( that either may be used, as desired.
Figs 4b and 4c show alternative arrangements for
the integrated construction of active elements. In
Fig. 4b, two rows 552 and 554 of active elements are
fabricated on the same supporting surface 556, in spaced
apart relationship. One row is made up of LED'~ and the
other row is made up of phototransistors, to form half
of the active elements needed for two spaced beam planes.
In Fig. ~c, two sheet~ of transparent plastic material
384a and 384b are provided, separated by a spacer sheet
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~5~.'3'~3
. .,
; 384c. Tlle shect 38~c is forrncd of any convcnicnt m.l~crial, arld positions
the sheets 384a and 384b far enoug~) apart so tilat t~c collirrlation cffcct
of the lenses is enhanced as much as possiblc. Thc spacing of the lcrlses
above the strip 378 is determined by the thickncss of thc shcct 38~b.
The operation of the apparatus describcd hcrcin is improvcd mar
~edly by the use of variable threshold de~/iccs ~hich adapt to ambient light
conditions in enabling the detection of intcrrupted and non-intcrrupted
beams. Such devices are described and claimcd in above-mcntioncd United
States Patent ~o. 4,243,879. The usc of the variablc threshold dcvices
! 10 makes the interlocking and spacemonitoring operations of thc prescnt
invention possible. I~ith previous apparatus, the high and variable light
levels encountered during such operations would effectively prevent collec-
¦ tion of meaningful data.
¦ l~hile the present invention has been describcd above in relation
j to its discrimination against small objects, where operation of a touch
¦ input panel by finger or stylus is desircd, it will be apparcnt that large
objects can also be discriminated against. For example, if more than a
given number of consecutive beams in any beam plane are interrupted, the
interrupting object may be recognized as not a finger or stylus, and the
input rejected.
The control logic described abovc has been dcscribcd in most
cases for positive logic, i.e., a
- 40
2S~ 3
positive-going pulse is required ~o execute the irldicated
function. It is apparent to those skilled in the art
that pulses of opposite polarity may be obtained at
substantially the same times by the use of inverters ~here
required. Where clocked logical units are employed (such
as synchronous counters instead of ripple counters) a
suitable source of clock pulses may be provided as well as
understood in the art. All of the logic units illustrated
and described are conventional commercially available
units.
It will be appreciated by those skilled in the
art that although the present invention is described in
terms of beam planes, the various sets of beams are not
necessarily aligned in a plane. In fact, when a curved
surface such as a CRT is used as the display device of a
touch input panel, the sets of beams are preferably
curved to conform to the curved CRT surface. Moreover,
the light beams referred to herein need not necessarily be
beams of visible light, but may be any form of radiant
energy, whether visible or invisible. For example, the
energy may be invisible infrared energy.
In the foregoing, the present invention has been
described such as to enable others skilled in the art
to make and use the same without departing from the
essential features of novelty involved. It will be
apparent that various modifications and additions may be
made without departing from the essential features of
novelty, which are intended to be defined and secured
by the appended claims.
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