Note: Descriptions are shown in the official language in which they were submitted.
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SPEC:[FICATION
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 ~f an object in the plane.
PhotQelectric 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 ox 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
apa.rt by a distance which is small enough to insure break--
ing at least one beam by the smallest size finger or
stylus, and, accordingly, it is frequently the case that
multiple beams are broken. In previous touch input panels,
the output is produced by an indication of the first beam
which is recognized as ~eing broXen, scanning from one
direction toward the o~her (for example, from the top
down), and this results i.n determination o a position
which is not the position correspondiny to the center line
~g~
of the ~inger or stylus~ Accordingly~ it is desirable
to provide a way of determining the approximate center
point of the finger or skylus if more than one of a
series o parallel beams is broken.
In 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 ~orelgn 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
of khe panel. It is desira~le to simplfy, as much as
possible~ the logic and electronic circuits required in the
u~e of the panel to enable the panel to be produced with as
~uch econ~my as possible, and to incrPase 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 rela~ing to
such input, such as the velocity of approach of the
ob~ect to~ard the touch panel. It is sometime~ desixable
to be able to discriminate the velocity of approach o an
object which lntersects the beams in the beam plane, in
order to insure with gxeater certainty that an actua~ion
of the touch input panel in an inkentional actuation by
means o~ a fing~r or stylus, rather than an accidental
operation. It is, therefore, also desirable ko provide
some mean~ o~ sensing the velocity of approach of an
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~bject 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 infrequently. This establishes a
time interYal of uncertainty as to whether a beam is
interruptsd or not. It is desixable to reduce this ti~e
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
operatio~ in more than one mode. Typically, they
operate in a point mode, in which points are identi~ied
by decoding the X Y coordinates of a broken beam pair,
without recogniz.ing additional points which may be leaiti-
mate inputs until after a condition is recogn.ized in which
no beam is broken. It is desirable to avoid this limita-
tion and permit multi-mode operati.on of the touch panel.
Previous touch panels have not been well-adapted
to recognize and detect more than one pair of interrup~ed
~eams at a time, which severelylimits the usefulness of
the panel~ It is desirable to provide an arrangement in
which a number of interrupted crossed beam pairs are
reco~nized. This ~akes it possible to use touch input
p~nel 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 a finger or stylus)
which mo~e normally to the touch panel. I~ is desirable
to be able to distinguish between normal or skew approaches,
particularly in applications where high resolution of the
touch input is required.
Previous touch panels have been required to use
comparator~ 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 to~ch input panel with means Eor determining
the approximate cen-ter point of an object which intersects
more than one ~eam of a plurality of parallel spaced beams
in a beam plane~
I~ is another objec~ of the present invention to
provide improved logic apparatus for decoding the position
oE an object which is detected within a beam plane.
Anothex object of the present invention is to
provide means for sensing the presence of a inger or
stylus or other elongated object, and distinguishing such
object from an object of shorter dimensions.
A further object oE 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
proyide ~eans for scanning interrupted beams more fre-
quently than non-interrup~ed beams.
Another object oE the present invention is to
provide appar~tus for enabling the control apparatus of
the present invention to function selectively in a point
mode or in a stream mode.
A furtheî o~ject of the present invention is to
provide apparatus for enabling the con~rol apparatus of
the present in~ention 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 planeO
A urther object of the present invention is to
provide appara~us for sizing ohjects within a space defined
by a plurality ~ beam planes.
Another object of the present invention is to
provide apparatus for monitoring activity within a space
~0 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 ~y a plurality of beam planes and for
inhibitinq operation of dangerous ins~rumentalities 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 ~f a finger
or stylus toward a touch panel in a normal direction and
discriminating against an angled approach,
~g~
A further ob~ect of the present invention is to
provide an improved arrangement for mounting a plurality of
LED's associated with a single beam plane.
According to a broad aspect of the present invention,
there is provided in a photoelectric input device having a
plurality of light sources and photosensitive devices defining
a set of light beams, apparatus for energizing said light sour-
ces one at a time, and detecting means for developing a signal
in response to a beam which is interrupted at the time i-ts
light source is energized, the improvement comprising counting
means for counting a number of beams in said se-t which are
interrupted.
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The invention will now be described in greater de~ail with reference
~o the accompanying drawings in which:
Pigure 1 is a perspective view of a portion of a housing of a
touch input panel incorporating an exemplary embodimen~ of the present
invention, illus~rating 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 unctional block diagram of a control system for
the appara~us of Figure l, illustrating the apparatus for detecting and
counting the number of broken beams, ~or detecting the coincidence of beam
interruption in ~he principal and auxiliary planes, anf for determining the
velocity of approach of an object toward the principal beam plane;
Figure 3 is a perspective view of an alternative embodiment 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 phototransistors;
Figure 5 is a functional block diagram of a control system for an
alternative embodiment of the present invention, having t~o X beam planes
spaced on opposite sides of a Y beam p].ane;
Figure 6 is a -functional block diagram of a control system for
a further dmbodiment of the present invention adapted for cowlting the num-
ber of consecutive interrupted
,~_
be~ms ln each beam plane and determining the address of
the center line of the interrupting object;
Fig, 7 is a functional block diagram of another
~mbodiment of the present invention adapted for scanning
back and forth in each beam plane across an interr~pting
object, without scanni.ng beam paths which are remote
from the intexrupting ob j ect;
Fig. 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 Eor enabling the apparatus of the present invention
to be selected for stream mode or point mode operation.
Referring now to Fig. 1, there is illustrated in
diagram~atic form a housing 10 which contains ~he control
system ~or operating a touch input panel. The housing 10
has a central opeIling 12, and the housing 10 is adapted
to be placed in relation to a display surace on the front
of a display device 11, 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 ~wo side walls 14 (one of which
is shown in Fig. 1) and upper and lower walls 16, One of
the side walls 14 is equipped with a plurali~y of light
emitting devices such as LED's or the like, and the oppo-
site wall is equipped with a plurality of photosensltive
devices such a.s phototransistors or the like. The photo-
transistors are aligned with the LED's and are adapted to
receive light generated by the LED~s. There ls a lens
i` v
provided or each o the LED~s to collimate the li~ht
and foc~s it principally on one o the phototransistors
on the opposite wall. The path between an LE~ and the
phototransistor on the opposite wall upon which the LED's
light ls focused i9 referred to as a beam. There are a
plurality of ~uch beams which originate at one of the side
walls 14 and terminate a~ the opposite side wall 14, and
these beams are arrang2d in parallel spaced relationship
so that a person or operator who tGuches a panel located
behind the opening 12 will intercept one or more of the
beams. The beams are arranged in a plane which is refer-
red to as a beam plane~
A ~econd set of spaced parallel beams extends
bet~een the upper ~d lower walls 16t with each o such
beams having~a light-generating LED at one end and a
phototransi~tor at the other end. The beams extending
between the slde walls 14 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 bearns. 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 i5 refexred to as ~he Y beam plane. When the X
beam plane colncides wi~h the Y beam plane, the plane is
reerred to as the principal plane~
In the apparatus of Fig, 1, a principal plane is
formed near the rear of the opening 12, with crossing X
beams and Y beams in that plane. An auxiliary X beam
plane is spaced forwardly o the pxincipal plane, near
the front o the opening 12. Its plane i~ referred to as
~J
the auxiliary plane, The location of the principal plane
is identi~ied in Fig, 1 by the apertures in the lower
wall 16 and the rearward line of apertures in the side
wall 14. The forward line of apertures in the side wall
14 define~ the auxiliary plane, The auxiliaxy 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
~reign objectO 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 simu~taneously can be discriminated against on the
basis of their characteristlc ~elocity of approach toward
the principal beam plane r as descri~ed 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 inhiblting the
device fxom recognizing a valid input unless that interval
confcrms to prescribed values.
The X beams in the auxiliary plane are hori~ontal-
ly aligned with the X beams in the principal plane. This
fact is mad~ u~e of in order to require that corresponding
X beam~ 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
~'10--
the front of the display device 11 in such a way that
his finger or stylus extends generally normally to the
panel, as far~as the X beams are concerned. By dis-
criminating against input~ which interrupt non-correspond-
ing X bearns in the principal and auxiliary planes, theapparatus is~able to discriminate against fingers or
styli which approach the panel in an oblique direction
as far a5 the X beams are concerned. Since the only set
of Y 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 normali~y is desired, a second se~ of Y beams can be
provided spaced from the principal plane in order to make
the same coinoidence requiremen~ for the Y beams as has
been described ~bove in connection with the X beamsO
~hen an extra ~ beam plane is pro~ided, it is desirable
to space it ~rom both the principal plane and the auxil~
iary X plane,'~so that three planes are provided. Noting
the time di~ference of beam interruption in each of the
three planes~permits a determina~ion of a change in the
velocity as~finger or stylus approaches the panel. In
other words, the time difference between interception of
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beams ln the ~irst 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 averaye velocities
in two adjacent spaces permi~s an identification of
certain type~ of movement of the operatox's finger or
stylus. Thi~ may be used as a~ additional input from
the touch input panel, and is at times very significant.
For example, if the veloci~y of a finger decreases more
than usual as it approaches the panel, it may indicate
a degree of uncertainty on ~he 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
progra~ for ~he circums~ance. For example, when the
touch input panel is employed with a programmed learning
device, one gubsequent program may be selected when the
response indicated by the ~ouch input i5 correct and
certain, and a different program may be selected when
the touch input is correct, but hesitant.
Referrlng to Fig. 3, an alternative embodiment
o~ the present in~ention is illustrated. In the
embodimeht o~ 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 apparatu~ of Fig. 1.
A clock pulse generator 20 i~ provided which
pxoduces repetitive pulses~ The pulses produced by the
generator 20 advance a counter 24, which funetions as
a scan counter for the X and Y beam~. It is a binary
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c~unte~ ~nd in the illustration of Fig. 4 is a multi-
st~e counter.~;~The output lines 26 from four stages of
the counter 24~are four in number, as identified by the
slash and the numeral 4. A larger ccunter (having si~
O~ more stages, fox example) may be used for larger
panels and when greater resolution is desiredO The lines
26 are connected ~o four input terminals of a latch unit
23, which functions to latch the data presented on
the llnes 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 outpu~ lines 36 connec~ed to individual LED's on
.:
one ~ the ~îdè walls 14, to generate the X beams 35
A g~te pul~e;~referred to as the LED gate is supplied
from a fifth~stage of the counter 24 to the decoding
unit 34 over à`line 38, so that an LED selected by the
decoding unit 34 ls fi~ed only for the duration of the
LED gate pulse on the line 38~ Preferably, this duration
~s a relatively small period within each cycle of the
highest ~requency output signal supplied to the output
lines 26, so that the LED's operate with a low duty cycle
~. .
and hav~ relatively high light output in relation to
the a~era~e power consumed by the LED's. This increases
the ef~iciency and reliability o the LED's. rrhe output
~5 lines 32 ~re connected over lines 40 to a series of output
terminals (not sho~n~ which identify the address of the
LED and the beam being energized at any given time.
rrhese terminals may be connected to a microprocessor or
othex computiny apparatus as an input.
Two of the four lines 32 are also supplied to a
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set of group select gates 33 for selecting one or another of several groups
of phototransistors 35 tfour in the embodiment of Figure 2~. Of all of the
phototransistors in ~he selected group, only one receives light from the
LED which is energized a.t that time, so that the composite signal from a
selected group of phototransistors reveals that the beam originated wi-th
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 ShifterJ
issued May 12, 1981. When a signal is received on the line 42 which indi
cates that a beam has not been interruptedl 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 a~ the tra.iling edge
of th0 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 low.
ln its reset condi~ion, 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 ou~put lines 32 of the latch unit 28
to manifest the address~of the last LED which was energized subsequent ~o
receipt of a non interrupted beam signal on the line 42.
When a beam is interrupted, there is no signal
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~ lw~
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pr~duced ~n the line 46, and the flip-flop 48 is reset
~t the end of th~ ~ED g~te pulse, I~ remains reset as
long as that beam remains interrupted~ This causes the
latch unit ~ to remain latched at the address of the
LED associated wi~h the interrupted beam, a~d this
address is made available to external 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,
his LED is pulsed repeti~ively at the ~ED gate pulse
ti~e by one o~ the lin~s 36 until a non-in~errupted beam
si~nal is rece~Lved on the line 42. Scanning then resumes
until the next~interrupted beam is found. The counter 24
~ ,
runs continuously during this tlme, The output on the
lines 40 continuously indicates the address of the LED
associated with the interrupted beam, and ~he signal on
the line 62 indicates that it is an interrupted beam.
~ ~he same apparatus is repeated for the Y beams,
using the same counter 24. A separake latch unit 66
is provided ~or the Y beams~ A separate threshold
detecto~ 68 is~e~ployed for the phototransistors associated
with the Y bea~s, and a separate output flip-flop 70 is
~l~o pxovided-~or the Y beams. Output lines 72 from the
latch unit 66 identify the addres~ of an LED associated
with an interxupted Y beam, and a signal from ~he flip
~lop 70 on a line 74 indicates tha~ the address i5 one of
an inte~rupted beam, When both of the lines 62 and 74
are high, lt ~i~nifies that X and Y bea~s have both been
`J ``. - ~
broken, and ~he coordinates of the two interrupted beams
are available on the lines 40 and 72. The LED for ~he
interrupted Y beam is repetitively pulsed, at the rate
of the clock ~enerator 20, as described above in connec~
tion with the X beam, and this continues until the beam
is recognized~a~ non-interrup~ed.
The continuous pulsing of the interrup~ed beams
provldes a di~ferent pulsin~ rate for interrupted beams
, ,
than ~r non-interrupted beams. Until a non-interrupted
beam i~ recognlzed, each be~m is pulsed once for every
sixteen cycle~;of the clock pul~e generator 20 (assuming
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a touch input;panel having sixteen X beams and sixteen Y
beams). ~hen~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 p~ovide~a markedly increased ability of the
appaxatus to d~tect when a touch input has been tPrminated.
This allcw`a ~ ~ ouch input panel of the present invention
to be u~ed~ ~ `~ore rapidly than conventional touch
2n input panels,~hich cannot recogni~e the termination of
touch inpu~until after as many as sixteen cycles of
the clock;pul ~;gener~tor. The speed of operation
~chieved by~t~ apparatus of the present invention makes
it possible ~r~ an operator to make multiple inputs in
a poi~t 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 ~enerated without lifing the finger or stylus frorn
the p~nely Because the n~o~lement of the finger away
frQm the int~rrupted beam is recogni~ed almost instantly,
it ls not nece~ary for the operator to withdraw his
~16;
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finger and wait ~or sixt.een çlock pulse cycles to go by
before making another finger input,
As thus far described, the apparatus of Fig. 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.
~n the apparatus of Fig. 1, a second set of X beams i~
required for the auxiliary plane, and the apparatus
assoclated with the second set of X beams will now be
described.
The LED~'s of the auxiliary plane are connected in
com~on with corresponding X LED's in the principal plane,
directly ~rom the X decode unlt 34. The outputs of
the phototransistors of the auxiliary plane are treated
separately~
Driving.the LEDIs of the principal and auxiliary
X plane~ ~r~m~the same decode unit 34 efPectuates a
saVings o~ ~trùcture, and permits a construction in which
only a small~:~;additisnal amount of structure is required
for the auxiliaxy X plane,
A separate threshold detecting circuit 80 is
provided for the auxiliary X phototransistors, and a
~lip-flop 82 is set by the trailing edge of the LED gate
pulse when the;detector 80 produces a signal indicating
that a beam is broken in the auxiliaxy X plane. An
AND-~ts 84 i~ connected to the outpu~s of the flip-flops
48, 70 and 8~, so that when they are all ~et, as when a
finyer or stxlu~ has interrupted corresponding X beams
and ~t lea~ one ~ beam, an output is produced indicating
th~t ~ nor~al ~nput i~ readyO
The X decode unit 34 operates to energize the
LED ' s for both the principal and auxiliary X planes,
so that cQ~responding beAms in both planes are energized
simultane~uslyO Since the X latch was last set following
detection of an interxupted beam in the principal plane,
~nly the interrupted beam in the principal plane and
the corresponding beam in the auxiliary plane can be
pulsed~ When both of those ~eams are broken, the flip-
~lops 48 and 82 are both set, indicating that a finger
h~s a~proached the panel normally as far as the X beams
are concerned~
When a finger approaches the panel in a direction
which does n~t intercept the same X beam in the principal
and auxiliary planes, only the flip~flop 48 can be reset.
The outputs o~ this and ~he flip-flop 82 are ccnnected
to two inputs~E an exclusive OR-gate 86, the output of
which is connected ~o an input of an AND-gate 88. The
second input of the ~ND-gate 88 is connected to the output
of the flip-flop 70,which ls set when a Y beam is broken.
~hen the ~ND~te 88 is operated, a signal appears on an
output line 90, signifying that a skew input is present.
A skew input~i~ one which breaks a Y beam, but does not
break both o~the X beams. This output line can be
employed to trigger a message on the Screen of ~he dis-
pl~y device 11~ indic~ting ~o the operator that he must
pl~ce his fin~er or stylus more normal to the surface ofthe panel.
A counter 92 is provided for measuring the time
difference between the arrival cf a finger or stylus
in the auxiliary and principal planes. It receives
ti~iny pulse~ through an AND-gate 94 from a timing
18-
clock pulse source 96, providing that a flip-flop 98 is
set. The flip~lop 98 is set by a slgnal on the line 100
from a monostable multi-vibrator 102. The multivibrator
102 furnishes a signal in the line 100 for a short period
S after the flip~flop 82 is set, indicating that an object
has arrived at the auxiliary plane. When the object
~rri~es at the pxincipal plane, the flip-flop 70 is set,
and a short duration signal i5 produced by a second
monostahle multivibrator 104 on a line 106 to reset the
~lip~lop 93. Accordingly, the counter 92 counts pulses
~rom 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 o~ the
counter is connected to a comparator 105 which compares
the content o the counter with value stored in storage
device 107~ If the content o ~he 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
112, which compaxes the output of the counter 92 to the
value stored in a second stcrage 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
other~ise~ a line 118 is energi~ed~ Accordingly, the
~5 QUtputs on lines 108, 116 and 118 indicate respec ively
that the time betwe n int~xruption of the auxiliary and
principal planes is less than Tl, is between Tl and
T2, and is greater than T2. ~rhe line 116 is connected
to ~ne input ~f 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 ~ND~gate 120 indicates a nor~al inPut
within the speed range speci~ied by the time values T1 ar,d
T2. Th~s 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 mo~ement of the finger or stylus was too fast
or too slow. Al~ernatively, 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 progra~s may be chosen
in response to whe~hex an input is delivered slowly and
hesi.tantly~ ~r rapidly, with certainty. The gate 120
can be connected thxough an O~-gate to the lines 108 and
118 instead of~to the line 116, to discriminate against
a ran~e of ~elscities corresponding to the time Tl and
T2,
The velocity discrlmination available by the
sign~ls on the lines 108, 116 and 118 is usable to dis-
~inguish hetween valid inputs through the use of a
stylus or finger, or through the accidental presence of
another relati~ely large object, such as a moth, which
is large enou~h to bxeak beams in both the principal
~nd auxiliary planes.
Flg, 5 i~ a functional block diagram of an
alternative ar~angement of the present invention having
two separated X beam planes~ This gives ~hxee distinct
pl~ne~, with two X beam planes and one Y beam plane. In
the apparatus illustrated in Fig. 5, the Y beam plane is
interposed between the two X beam planes which are
~20~
~ ,i
~6~
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 Fig. 2,
for the Xl plane. A separate latch unit 200 ls provided
for the X2 plane, and it is corlnected 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 the two X planes, they are
10 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
eithex the Xl or X2 planes does not prevent the recogni-
15 tion of the interruption of a non-corresponding beam in
the other pla~e.
Three-~threshold detection devices TD and three
output ~lip-flops are provided 48, 70 and 82, just as in
the apparatus of Fig. 2.
The output o~ the flip--flop 82 is connected
thxough a monos~able multivibrator 102 to set the flip-
fl~p 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
25 up to a value corresponding to the time difference be-
tw~en bea~ 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-
~ibrator 206 energized by the flip~flop 48. While the
30 flip flop 204 remains set, an AND gate 208 is activated
-21-
to pass pulses from the timing clock souxce 96 to a
counter 2107 Accordingly, the counter 210 is counted
up to a value corresponding to the time difference be-
tween interrup~ion of beams in the Y plane and the Xl
plane. The content of the two counters g2 and 210 is
conveyed to a 3ubtraction unit 212, the output of which
is connected to a comparator 214 which compares the
result o the subtraction with the value stored in a
storage device 216. An output line 218 identifies the
sign of the difference, which indicates whether the
velocity ls increasing or decreasing as an object
approaches the panel, and two additional output lines
220 and ~22 indicate whether the time difference is
greater or less than the time difference stored in the
storage device 2160
If it is desired to produce outputs responsive
to the relative change in velocities as a flnger or
stylus approaches the panel, a dividing unit can be
substituted for the subtraction unit 212, whereupon the
result is not~khe dii~erence between the times, but the
relative leng~h of the times. This result can be
co~pared with a standard value stored in the storage
unit 215,~ whereupon the signals on the output lines 220
and 222 indica~e whether the change in velocity is
above or below a specified value. ~he signal on the line
218 would be produced in response to a comparison ~ith
unity in a comparator (not shown) and would signify a
condition of increasing or decreasing velocity.
The Various outputs available from the apparatus
of Fig. 5 can be used in the same manner as described in
w ~
connection with the apparatus of ~ 2, namely, to con-
trol selection of programs, in response to the observed
c~ndition~. ~n the apparatus of both Fig. 2 and Fig. 5,
it is apparent that the counting, the subtraction or
division~ and the compariso~ can take place by suitable
programmin~ o~ a microprocesslng unit or other computer,
in which the storage devices 107, 114, 216, etc. are
contained in the computer's memory unitO
In any arrangement in which multiple X beams are
e~ployed~ it is preferable to place the LED's for one X
beam plane and the phototransistors for the other X beam
plane on a sin~le side 14 of the opening 12. The other
LED's and phototransistors would then 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 LEDIs of on~ beam plane and the phototransis-
tors of the ~ther, When multiple Y beam planes are pro-
vided, a corre~ponding arrangement is also desirable for
the same reason.
In Fi5, S, 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 th~
interruption of non-correspondin$ beams, the output of the
gate 224 doe~ not necessarily indicate a normal input,
but does indicate that an input is readyl and that it is
lon~ erlough to intexcep'~ all three beam planes. The
presence of a normal input can be identified, however,
b~ me~ns of apparatus which will now be described.
The multiplexer 226 has two sets of inputs
-23-
connected respective~l~ to the outputs Df the Xl latch 28
and the X2 latch 200. Its output lines 228 are connected
to the X2 decode unit 202, A con~rol line 230 is con-
nected to the ~ultiplexer unit 226 ~or selecting the
output of the Xl latch 28 or the X2 latch 200 to be decoded
by the unit 202, Normally, the multiplexer 226 selects the
output ~f the X2 latch, and when it does, the flip-:Elops
48 and 82 can be set by the breaXing of non--corresponding
bea~s, When the condition cf the multiplexer 226 is
chan~ed, howeyer, 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 axe pulsed simultaneously, and
then the ~lip~1Ops 48 and 82 can be set only when
corresponding beams are simultaneousl~ interrupted. An
AND-gate 232`has two of its three inputs connected to the
outputs ~f the flip-flops 48 and 82 and its third input
to the multiplexer control line 230, Thus, when the
multiplexer ~26 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 contr~l lines 230 high, this can occur
only when corxesponding X bea~s are broken, so that t.he
output Signi~ies that the input finger or stylus is normal
to the touch panel
Re~erence will now be made to Fig. 6, in which an
embodiment is illustxated whi~h provides a means for
countin~ the number of broken beams, and determining the
center point o~ the object which is interrupting the
be~ms, A clock pulse ~enerator 20 is connected to a
counter 24, and the counter 24 is connected to X and
decode units 34 and 67, just as described above in
-2~-
relation to Fig 2. The coun~er 24 p~oduces an o-ltput
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 X beams, it being
understood that this structure is duplicated for the Y
beam~.
The threshold detector 44 is con~ected 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, and it is provided with a pulse on
lS 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 ~lip~flop 48 is also connected
to a gate 308 which receives LED gate pulses at its
other input. The output of the gate 308 is connected
to the input of a counte~ 312 which is reset by a pulse
on a line 311 at the end of each scan cycle. Accvrdingly,
~he counter is xeset to ~ero during ~he ea~ly portion of
the scan cycle, and begins to count the LED clock pulses
~ollowing resettlng of the flip-flop ~8, and is incre-
mented to a c~ntent of unity on the second interrupted
-25-
beam. The counter 24 continues to be incremented by the
clock pulse genera~or 20, so tha~ the decoder 34 con~
tinues to enexgize successive beams, after khe first
intexrupted beam is detected. For each additional beam
which is intercepted, th~ ga~e 308 produces an output
which is counted by the counter 312. When the first
following uninterrupted beam is recognized, the flip-
flop 48 is set, and an input is applied from the line 60
through an inverter 314 to the control input of a latch
unit 316, whereby the content of the ~ounter 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-fl~p 302.
Since the 1ip-flop 302 is set following detection of
the first interrupted beam, both inputs to the gate 318
are hi~h or the first time when the last of the series
of interrupted beams has been detected. Its output on
a line 320 si~nifies 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 t~e l~tch 316 and shift it rightwardly one
position, which results in the binary quantity being
di~ided ~y 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
o 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 ~tored in the
counter 312. It thus ldentifies the midpoint of the
-26-
sequence of interrup~ed bearns 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 bea~ plane, even when the beams are broken
by a fi.nger 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
~o the center point of the interrupting object. This 5ig-
nal may ~e produced by anding the line 320 with the
cor~esponding output line ~or the Y beams.
It will be apparent that in the apparatus of
Fig. 6 t it i5 necessary to continue scanning the X beams
after the first interrupted beam is detected, in order
to count the total number of interrupted beams. In the
apparatus of Fig. 6, the counting continues ~or a full
cycle, so that the increased pulslng speed of beams
detected a~ having been interrupted, described in con
nection with Fig. 2, is not a ~eature of Fig. 6. The
-~7-
apparatus o~ Fig. 6 can be modified, however, to enable
the direction of sca~ning ~ reverse when the t~tal
number of .interrupted beams have been ~canned, to improve
the speed of operation of the apparatus. Such a modifi-
cation is shown in Fig. 7.
ln the apparatus of Fig. 7, the clock pulsegenerator 20 is connected to two separate counters 352
and 354 ~or the X and Y beams. Both counters are up down
counters, and the direction of coun~ing is separately
controlled by a control line in each case. The control
line for the X counter 352 is th~ line 353.
Th~ clock pulse generator 20 counts the counter
352 up~ardly, via a frequency divider 355, which produces
the LED g~te pulses7 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
rnuch of the operation is similar to that which has been
already desc~ibed above. ~he Q output of the flip-flop 48
is connected to the toggle input o~ a flip-flop 358.
This sets the ~lip-flop 358 and causes the latch unit 306
t~ be latched to hold the address o the interrupted
beam,
A ~ate 360 is connected to the Q output of the
flip-flop 48 and ~o the LED ga~e pulses fox causing the
counter 312 to count the n~nber of interrupted bearns.
It recPives a third input from the Q output of a flip-flop
361, The function of the 1ip-flop 361 ls to control the
dixectio~ of counting of the counter 352. This ou~put
is high wh~n the counter is counting upwardly in its
-28
normal direction, so that the counter 312 is enabled t~
count the interrupted beams which are encountered after
the first in~errupted beam, while the counter is counting
in its nor~al upward direct.ton
The Q output of the flip-:Elop 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-flop 361 disables
the counter 31~ and causes the counter 352 to begin to
count downwardly, and therefore again scans the inter-
rupted beams in the reverse direction. When th~ first
inte~rupted beam is reached, the flip-flop 48 is reset,
and its Q output goes highO This output sets the flip-
flop 358 to terminate the output ready signal. When all
of the interrupted beams have been scanned, e~entually,
a non-interrupted bea~ will be reach~d, and at that
time, the flip-~lop 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 reset the counter 312 o~er a line 313, preparatory to
makin~ a new count ~ the number of interrupted beams on
the next successive scan. The output of the counter 31
is conn~cted to the latch 316, which is operated by
inverter 364~ Which receives its input from the Q output
vf the flip-flop 361~ Accordingly, th~ latch 316 is
operated after the full set of in~erruPted beams ha.s
been scanned and the flip~flop 361 is reset in order to
-29-
cause the counter 352 to count downwardly. An AND-gate
366 has its inputs connected to the output of the inver-
ter 364 and the Q output of the flip~lop 358 to identify
that a count is ready. The content of the latch is
pre~erably shif~ed by means of a shifter as shown in
Fig. 6 and added to the data stored in the latch 306,
in the manner described in connection with Fig. 6 to
identif~ the center line of the operating finger or stylus.
The flip-flops 358 and 361 are reset and set, respectively,
by the pulse on the line 311 whenever the end of scan i5
reached, to insure that their operation remains 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 pxovides 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 ~odification would involve latching in the latch unit
306 the hiyhest address of an interrupting beam (at the
end of the upwaxd scan or beginning of 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 arri~e at the
identification of the center line of ~he interrupted beam.
It is apparent that other latches (not shown) may be
provided for holding data so that valid outputs are
~30-
'.~ 1 `
available to an output de~ice without any particula~need for synchronization with the opera~ion sf the
upward and downward scanning apparatus.
It will ~e appreciated that, in the arrangement
of Fig. 7, similar structure is provided for the Y beams,
and an ~N~-gate can be pro~ided 'co and ~he data ready
outputs of the X and Y circuits to identify when the X
and Y coordinates of the center point of the interrupting
object are availa~le for read-out to an external 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 fo.rm of a single in~egrated structure,
on a strip 378, Several or all of the elements may be
fahricated as integrated circuits formed in a single
semiconducting surface. A plurality of indi~7idually
light-emittinq areas 380 are provided in spaced relation-
ship along the length ~f the device, and a plurality of
pins 382 protrude from the bottom of the appara~us in
order to enable easy mounting and replacement of the
structure~ The ~abrication of plural LED's on a single
structure makes it possible to control the accuracy of
the spacin~ of the LED at the time of the manufacture of
the LED uni~s themselves, and substantially decrease the
assembly spexations req~ired in construction of a to~ch
panel appa~atu~.
Abo~e the strip 378, a second strip 384 is
positiDned. It is formed of transparent plastic material,
~nd it has a plurality of positive lenses 385 integrally
m~lded thereinto, spaced apart by distances which
-31-
` ~J ~_
~ ~3 ~
correspond to the sp~cing o~ the LED~ 380~ The lenses
385 comprise ~onvex surfaces on the upper surface of the
strip 3841 while the lower surface of the stxip 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' 5 to allow for maximum
focusing of the light em.itted 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 i5
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 illustra~ion 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
it is surrounded in three separate planes by three
rectangular~ hollow housings 402, 404 and 406. The
housin~s support liyht sources and photosensitive devices
on opposite s1des, to form crossed beam planes, in the
same manner which has been described above in connecti.on
with touch input panels. In the embodimen~ of Fig. 8,
h~wever, no touchable panel per se is employed. The
apparatus is used to monitor activity within the space
408. The space 408 may, for examp:Le~ comprise an an:imal
cage, in which case the apparatus of Fig. 8 is adapted
to monitor the acti~ity of an animal in the cage. The
-32-
v '~
beams which are broken in the X and Y directi~ns in all
three planes can be observed to represent the profile of
the animal within the space, distinguish between lying,
sitting and standing attitudes of the animal, determine
the horizontal position of the animal in the cage, and,
in general r monitor its activity. The speed of movement
of the ~nim~l in either the X or Y direction can be
determined by noting the time difference between 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 diference between inter-
ruption of successi~e 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 t~ 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 ~et 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 ~o monitor the ac-tivi~y of a child in a
playpen or a crib. Although the space illustrated in
Fig~ 8 i~ square, the space 408 need not be square, if
~he beams in the cross beam planes are not equally spaced,
or if more beams are provided in one set of cross beams
than in ~he o~her. ~n arrangement with an unequal number
of beams in the beam plane is easily accommodated by
-33-
~ - /
~36~
the apparatus of the present invention, by use ~ the
set inputs 581 58' and 58" (Fig 2) which enable the
intercepted beam de~ecting flip-flops to be set externally,
to ignore non-meaningful inputs which may be produced by
the vaxious threshold detectorsO
~he apparatus of Flg. ~ ~ay also be used to monitor
activity within a larger space, such as a room, where it
may be desira~le to maintain a record of movement of
people, animals, or objects The apparatus of Fig. 8 can
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 ~ool, such as a punch press, or other
metal forming or metal cutting machine, the space 408
lS defines the space around the machine in which an operator
can stand during operation of ~he equipment. The apparatus
of Figt 8 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 operatox
moves into a dangerous position. The housings 402, 404
and 406 are positioned in such a way that the dangerous
positions of the machine are scanned, and it is apparent
th~t they need not necessarily be s~acked in parallel
arrangement as shown in Fig. 8, if an angled relationship
afords a better filling of danyerous areas with crossed
beams. The presence of an operator's hand within a
dangero~ls area is recognized by the coordinates of the
beams which are in~errupted, and apparatus is provided
~or disablin~ the machinery when the interrupted beams axe
recognized in these locations.
-3~-
The appar~tus of Fi~. 8 may also be ernployed to
grade or size objects which pass within the space 408.
This can be acco~plished by counting ~he 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 ~unction of the volume of an object which is entirely
within the space scanned by the three planes of the appar-
atus of Fig~ 3. Additional planes may be provided 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 ~ectional area of
the ~bject may be determined in any of the three planes r
by calculating the product of the total number of X
beams and Y beams which are broken, and integrating the
cross sectional area by répetitivR 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 appli~ation.
~ The logic circuit associated with the structure
of Fig, 8 is illustrated in Fig. 9. The clock pulse
generator 20 is employed for producing pulses which count
up a counter 412 Via a divider 355. The output of ~he
counter is 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 li~ht sources. Since ~he apparatus provided for
the Y beam~ is identical to that for ~he X beams, a
description of the apparatus provided for the X beams
will ~u~ice for both,
-35-
~,
The housing 402 ls shown in Fig. 9 in cross
section~ and it is seen that an LED 418 is contained
within the hollow housing aligned with an ape~ture ~hich
has a colli~ating lens ~20 superposed over it. ~ligned
with the LED 418 and the lens 420 is an aperture 422 in
the opposite side ~all of the housing 402, and a photo-
transistor 424 is posi~ioned behind the aperture 422.
The housing 404 and 406 for the other two planes
ha~e a similar structure, but the central plane 404 has
the position of its LED and phototransistor interchanged,
to minimize interfe~ence between the LED's of one plane
and the phototransistors ~f another. .Corresponding LED' 5
of all three planes are connected together so that no
~dditional lines from the X decode unit 416 are required
for any numbe~ of planes which may be provided.
Each of the three planes has its individual
inter~upted bea,m. recogniticn flip~flop 434, 436 and 438,
connected to its threshold detector, so tha~ interruption
o~ three correspondin~ beams in the three planes is
independently reco~nized.
When~a~beam in the X3 plane is interrupted, the
clQck input to the ~lip~flop 434 resets the flip-flop,
and its Q QUtpUt goes high, giVing a hi~h leve.1. signal
on the output 440, indicat.ing that ~he X3 beam has been
interrupted. ~he line 440 i5 connected to the latch
input o~ a l~tch unit 442 which has its data inputs
connectecl to the output of the counter 412. Accordingly,
the add~ess of the LED associated with the lnterrupted
be~m in the X3 plane is latched in the latch unit 442 and
is available ~s an output on lines 444. A gate 446 h~s
-36-
~.J v
~6~
its inputs conne~ted to the Q output o~ the flip-flop
434 and its clock input~ The gate g46 produces pulses
which are counted in a counter 450. The counter 450 is
reset by a reset pulse on a line 311 at the end of each
scan cycle, and is counted Up from zero to count the
total number of successive beams in the X3 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 X2 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
15 operation~ For example, if the cross sectional area, as
seen in the three X beam planes, is ~o be calculated, the
outputs of the three oounters, which are available on
lines 45~, 453 and 460, may be added. If the apparatus
is designed to determine whether an object is in a certain
defined space (such a~ 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 range~ indicated by (a) the outputs 444, 454
and 456 indicating the addresses of the first inter.-cupted
beam in each plane, and (b) the outputs indicating the
total number of sequential interrupted beams in the
three planes, It is ~pparent that a microprocessor or
other processing device can readily make this determination
and i~sue an output signal which can halt operation of
the machine when a danyerous condition is recognized.
~37-
The apparatlls of Fig. 9 is also adaptable to
control by an ex~rnal computer, in which case the scan-
ning means may be energized in any sequence defined by
the computer~s program. ~hen this mode of operation is
desired, the computer contFols 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 independent~y of the clock pulses produced
by the generator 20 and the divider 355. When the line
466 goes highr 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 ~64~ so tha~
any desired beams ean be chosen by providing the appro-
priate data on the lines 464. In this way, special
progra~s may be executed ~ scan only areas of interest,
such as d~ngerous positions around ~he 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 appaxatus. Such a program has been
described in connection with Fig. 7 r It is apparent
that an MPU or other computer c2n be axranged ~o carry
out, through software, the operation~ which are perform.ed
by the hardware described in connection with Fig 7.
As described in the foregoing embodiments, the
apparatus of the present invention i8 adapted to produce
a stream o~ outputs corresponding to the beams which are
interrupted at any gi~en time. Under some circumstances,
it is desirable to cause the apparatus to operate in a
poin~ ~ode~ in which an ou~put is produced identifying
-38-
v
the X-Y coordinates of only the first pair of crossed
beams which are intercepted, No other data is output
until a condition is first recognized in which no beams
are interceptedO This mode of opera~ion is sometimes
S desirable, in connection with a touch panel, when it is
desired for the operator to execute operations in which
only point~ are per~i~sible inputs.
An arrangement is illustrated in Fig. 10 in
which the poin~ 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--~lops 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 interrupted X and Y
beams. The output of the flip-flop 48 is connected to
the set input o~ a flip-flop 506 which functions to
produce a signal which operates the X latch unit 28,
making the address o~ 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 output o~ which is connected to operate the Y latch
66 a,nd make the address of the in~errupted ~ beam avail~
able on the lines 72~ Once the flip-flops 506 and 510
have been se~, they cannot be reset until a signal is
available on the line 514. Thls signal is developed by
a NOR-gate 516 connected to the outputs of the flip~
flops 48 and 70, and resets the 1ip-flops through OR-gates
525 and 526. A pulse appears on the line 514 only when
both o the flip-flops 48 and 70 have been set in response
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`` J
to recognition of a non-interrup'ced beam, Therefore~ the
finger or stylus must be withdrawn so that no beam is
interrupted before the la~ches 28 and 66 can indicate a
suhsequent address.
W~len a stream mode is desired, a mode selec~or
input 518 is brought low. This is connected to inputs
of two NOR-gates 520 and 522, the output 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 S20 and 522 are connected to the Q out-
puts of the flip-flops 43 and 70. Accordingly, when the
line 518 is low, the flip-~lop 506 i~ reset immediately
following recognition of a non-interrupted beam by the
flip-flop 48~ When this occurs, the output of the flip-
lS flop 48 ~oes Iow, and the garce 520 produces a pulse which
passes through the gate 525 to rese~ the flip-flop 506.
~ccordingly, the X latch 28 may be latched as soon as
the next interrupted beam is recognized. The same oper-
ation occurs or th~ Y latch.
The circuit of Fig. 10 makes it possi~le 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's and the
other row i5 made up of phototransistors, to form halE
of the active elemen'cs needed for two spaced beam plhnes.
In Fig, 4c~ two ~heets oE transparQnt plastic material
384a and 384b are provided, separated by a spacer sheet
~'10--
384c. The sheet 384c is formed of any convenient ma-teri~l 9 and positions
the sheets 384a and 384b far enough apar~ so that the collimation effect
of the lenses is enhanced as much as possible. The spacing of the lenses
above the strip 378 is determined by the thickness of the sheet 384b.
The operation of the apparatus described herein is improved mar-
kedly by the use of variable threshold devices which adapt to ambien~ light
conditions in enabling the detection of interrupted and non-interrupted
beams. Such devices are described and claimed in above-mentioned ~nited
States Patent No. 4~243,879. The use of the variable threshold devices
makes the interlocking and spacemonitoring operations of the present
inYention possible. With previous apparatus, the high and variable light
levels encountered during such operations would effecti.vely prevent collec-
tion of meaningful data.
While the presen~ invention has been described above in relation
to ;ts discrimination against small objec~s, where operation of a touch
input panel by finger or stylus is desired, it will be apparent that large
objects can also be discriminated against. For example~ if more than a
given nuinber of consecutive beams in any beam plane are interrupted, the
inter~ipting object may be recogni~ed as not a finger or stylus, and the
input rejected.
The control logic described above has been described in most
cases for posit;ve logic, i.e., a
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positive-going pulse i5 required to execute the indicated
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 where
required. Where clocked logical units are employed (such
as synchronous countexs 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 a~ a CRT is used as the display device of a
touch input panel, the sets of beams are preferably
curved to conoxm to the curved CRT surface. Moreover r
the light beams referred to herein need not necessarily be
beams of visible light, but mav be anv form of radiant
energy, whether visible or invisible. For example, the
energy may be invisible infrared energy.
In the oregoing, the present invention has been
described suc~ as to enable others skilled in the art
to make and use the same ~ithout departing from the
essential features of novelty involved. It will be
app~rent that vaxious modifications and additions may be
~ade without departing from the essential features of
novelty, which are intended to be defined and secured
by the appended claims,
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