Note: Descriptions are shown in the official language in which they were submitted.
aD o~
In recent years a number of auto focus systems particularly for
use with cameras have been devised. The majority of such auto focus systems
fall into one of two main types: first the passive type systems wherein two
images of a scene being viewed are compared with the amoun~ of displacement
from a coincidence or superimposed position being indicative of the range to
the subject and second, the active type systems wherein a proje~tion of either
sound or light is directed from the camera to the subject and the reflected
energy received back is analyzed to determine the distance to the subject.
The present invention relates to an active type system which, in the past,
have encountered several difficulties.
Active units, using sound as the projection beam, suffer the problems
of reflections off of objects which are not the main subject of the picture
and the inabil:ity to focus through a transparent medium such as a window.
Active systems using light or infrared energy heretofore have usually re-
quired moveable projections and/or moveable detectors or have needed multiple
projectors to establish a focus position. In some systems, a fixed projector
and fixed detectors have been employed but these systems require specially
shaped or masked detectors and/or use rather complex electronics to determine
the position o:~ the reflected light. Furthermore, prior art systems have
produced primar:ily analog output signals which are difficult to process and
use for positioning a camera lens. While steps have been taken to overcome
most of the problems encountered with prior art systems and accurate in-focus
pictures may be obtained in a majority of the cases with either type system,
a truly simple system having a digital output, having no moving parts other
~ ~g
~3~ ~7
than the camera taking lens, having simple electronics, and having a lo~"
manufacturing cost has yet to be devised.
SUh~ARY OF TIIE INVENTION
The present invention is an active system utilizing modulated light
or infrared energy and employing a unique detector which works in con~ination
with a lens that, in the preferred embodiment, produces a distorted image of
the reflected energy to provide a digital output signal indicative of the
range to the subject in one of a plurality of zones. In the present invention,
a unique and low cost taking lens positioning apparatus is utilized which
operates from the digital output without the use of servo motors or other
high energy consuming and costly components. More particularly, in the
present invention, a modulated source of infrared energy is directed from the
camera to the subject and the modulated reflected energy received from the
subject is passed through a cylindrical lens or other type of distorting lens
so as to create an image of the reflected energy which is a narrow strip or
line. This line of reflected energy falls upon a novel detector array which
is built to have a plurality of separate detector elements in a predetermined
pattern thereon. The position of the reflected line of energy on the detector
is indicative of the distance to the subject and through the unique placement
of the detector elements on the detector array this position is ascertained
in a digital fashion with sufficient accuracy to provide a proper in-focus
signal for subjects ranging from very near to infinity. A spring biased
taking lens is positioned by a plurality of solenoid actuated shims which stop
the lens motion at the proper focus zone.
In accordance with the present invention, there is provided an
apparatus for positioning the taking lens means of a camera comprising:
3~ 7
housing means carrying the lens means and movable along a first path; a
first member positioned a predetermined space from the housing means in
the first path, the housing means moving in the first path, contacting the
first member and being restrained from further movement in a first position
after the housing means has contacted the first member; and spacing means
operable to move into and out of the predetermined space and operable when
in the predetermined space to cause the housing means in i~cs movement in
the path to contact .the spacing means, said housing means and said spacing
means thereafter moving together in the first path, contacting the first
member and being restrained from further movement with the housing means in
a position other than the first position after the housing means together
with the spacing means has contacted the first member.
BRIEF DESCRIPTION OF TIIE DRAWINGS
FIGURE I shows a cross-sectional and partly schematic diagram of
the camera and auto focus circuitry of the present invention;
r:IGURE 2 shows one embodiment of the detector array with the place-
nent of individual detectors thereon;
FIGURE 3 i~ a table showing the zones, the distances involved in
each zone, the system outputs at the various zone positions, the lens exten-
sion used for each zone and the nominal position of an in-focus subject in
each zone;
FIGURE 4 shows an embodiment of the detector array for a four zone
system; and
FIGURE 5 shows an alternate embodiment of an eight zone system det-
ector array.
DETAILED DESCRIPTION ~)F TIIE PREFERRED EJIBODII~IENT
In FIGURE 1, the lens structure of a camera is show~ by reference
numeral 10 comprising a taking lens 12 fastened in a lens mounting 14 which
is biased downwardly by a spring 16. A latch 18 is shown in an indented por-
tion 20 of the lens mounting 14 and is shown held in tllis position by a bias
member 22 urging the latch member 18 to the left in FIGURE 1. A release but-
ton 26 is shown in FIGURE 1 normally biased to the left by a spring mernber
28 and having a first extension 30 and a second extension 34. Upon activ-
ation of the release button 26, extension 34 first operates to close the
switch contacts of an auto focus power switch 32 thereby providing power to
the system to be described. Further motion of release button 26 causes
extension 30 to bear against the latch member 18 causing it to move to the
right and out of the detent portion 20 and thereby releasing the lens mounting
14 and lens 12 to move downwardly.
When lens mounting 14 and lens 12 move downwardly, an abutment 36
of lens mounting 14 will come in contact with one of a plurality of shims
identified by reference numerals 40, 42 and 44 depending upon the output of
the auto focus system and will then strike a moveable member 46 which will
itself move downwardly a small amount indicated by space 48 before coming
to rest against a fixed member 50. As moveable member 46 moves do~mwardly,
an extension shown by arrow 52 will operate a switch S4 which causes the
shutter release mechanism, not shown, to operate. For purposes to be ex-
plained in greater detail hereinafter, shim members 40, 42 and 44 are of
different widths and are positioned between the abutment 36 and the moveable
member 46 in accordance with the ac-tuation of a plurality of solenoids 60,
62 and 64 which are caused to operate by the output of the auto focus system.
3~
Solenoid 60 is shown connected by means of a rnember 66 to shim 40 which is
the largest in width, solenoid 62 is shown connected by a member 68 to shim
42 which is of the middle thickness of the three shims and solenoid 64 is
shown connected by a member 70 to shim 44 which is the smallest of the shims.
As can be seen, if none of the solenoids 60, 62, or 64 is actuated, then lens
mounting 14 will move all the way downwardly until abutment 36 moves member
46 into contact with fixed member 50. If solenoid 64 is actuated, ~he
smallest shim 44 will be placed in between ahutment 36 and moveable member
46 so that the lens mounting 14 will not move as far as it did with none of
the solenoids actuated. In similar fashion, if solenoid 62 is actuated,
the middle sized shim will be placed between abutment 36 and moveable mem-
ber 46 and again the lens mounting 14 will not move downwardly as far as it
did with solenoid 64 actuated. It can be seen that by energizing or not
energizing one or more of the three solenoids, various combinations of shims
may be placed between the abutment 36 and the moveable member 46 and various
amounts of downward motion of lens mounting 14 and lens 12 may be provided.
With the use of three solenoids and three shims, eight different positions of
the lens mounting 14 and lens 12 may be obtained. After the shutter release
switch 5~ has operated and ~he picture has been taken, the film advance mech-
~0 anism, noE shown, will be used to move the lens mounting 14 and lens 12 backto its original position and latch member 18 will again be moved into the
indent 20 so as to hold the lens mounting 14 in the position shown in readi-
ness for the next picture to be taken.
Also shown in FIGURE 1 is a light source 80 identi~ied as LED r~OD
which, in the preferred embodiment, produces a modulated beam of infrared
energy along the path shown by axis 82 *hrough a lens 84. The modulated LED
80 may transmit energy in a relatively narrow band preferably in the infrared
region at about 0.94 microns. A :filter may also be placed along ai~i s 82 to
further assure a narrow band of frequency. Lens 84 may act to focus or col-
limate the infrared energy dires:ted along axis 82 although accurate col-
limation is not imperative. The infrared energy travels along axis 82 until
it strikes a subject whose picture is to be taken. rhe modulated infrared
energy that is reflected back from the subject -travels along a path shown by
axis 86 at the left hand side of FIGURE 1 and passes through a lens 88 and
a distorting lens 90 to thereafter strike a detector array 92. ~ filter may
10 also be employed along axis 86 to reduce the amount of ambient energy and
restrict the frequency that strikes detector array 92 to the narrow band
projected by the LED modulator 80. The distorting lens 90 may be a cylindrical
lens mounted as a separate element or may be incorporated as part of lens 88.
Other kinds of lenses which may be made to create a relatively narrow image
Oll detector array 92 may also be employed and, for example, lens 88 may be
made similar to the astigmatic lenses which are common in the art.
The reflected energy along axis 86 will produce on the detector
array 92 a relativeiy thin narrow line ima~e into and out of the plane of
UI~ 1 and the position of this line will vary with the range to the sub-
20 ject. With the subject at a far distance, axis 86 will be substantially
parallel with axis 82 and ~he lens image will strike detector 92 at the right
end thereof labeled "oo" in ~IGUR~ 1. If the subject were very close at, for
example, one meter, the line image would strike detector 92 at the left end
thereof labelled "I~l" in FIGURE 1. Positions of the line image between one
meter and infinity will fall on detector 92 at corresponding positions between
the ends thereof. Detector array 92 is composed of a plurality of detectors
-- 6 --
~3~3V~
split into two equal areas and arran~ed on the surface of the detector in a
pattern which will enable determination of the position of the re~lected
energy striking the surface thereof. FIGUI~ 2 shol~s one e-mbodimerlt of the
surface of detector array 92 in which detectors of various si~es are placed
in three rows thereon. The detectors are preferably photo diodes which
generate a signal when energy is imaged on this surface although other types
of detectors such as photo conducting or even charge coupled devices could be
employed. The detectors have been shown as rectangles and in practice this
will be their preferred approximate shape although other shape detectors may
also be employed. For convenience, adjacent detectors have been shown either
dotted or blank for purposes of showing which detectors will operate to
produce a digital "0" or a digital "1" by the circuitry to be described. The
frst row, identified by the letter "Al', has a small detector 100 at the left
hand side thereof and shown by a dotted area. The width of detector 100 is
one eighth of the width of the array and the height of the detector 100 may
~e chosen for convenience. In FIGURE 2, detector 100 is shown to be approx-
imately square but the height may be chosen so as to have a more rectangular
shape. Adjacent detector 100 is a detector 102 which is twice the width of
detector 100 and is sllown blank in FIG~RE 2. A third detector, 10~, is
2() mounted next to the detector 102 and is of the same width as detector 102 but
is shown as a dotted area. A :Eourth detector, 106 is shown adjacent detector
104 and is of the same wid~h as detectors 102 and 104 but again is shown as
a blank area. Finally, row "A" contains a fifth detector, 108, at the right
hand side which is of the same width as detector 100 and is also shown as a
dotted area. The second row, identified by the letter "B", has a first
detector 110 at the left hand side that is four times the width of detector
3;~
lO0 and is shown to be blank in FIGURE 2. Row "B" also contains a second
detector 112 adjacent detector llO, at the right hand side of the array,
which is of the same width as detector 110 and is shown as a dotted area.
The third row, identified by the letter "C", has a first detector 114 on
the lef~ hand side which is of the same width as detectors 102, 104 and 106,
and is shown as a dotted area. Row "C" contains a second de~ector 11~ adja-
cent detector 114 which is of the same width as detectors 110 and 112 and
is shown in blank area. Finally, row C contains a third detector 118 adja-
cent detector 116, at the right hand side of the array, which is of the same
width as detectors 102, 104, 106 and 114 and is shown as a dotted area.
Along the bottom portion of FIGVRE 2, eight divisions or zones, which
detector g2 with its array thereon can detect, are shown and these are iden-
tified by the numbers 1 through 8. The distorted image of the modulated
infrared energy is shown in FIGURE 2 as an elongated spot or a thin line
image 120 lying in zone 3 of the detector array and crossing detectors 106,
112 and 116. Although relatively thin, the width of image 120 is normally
much larger than the boundary area between adjacent detectors. The direction
o~ rnovernent o~ spot 120, as the object moves, is right and left in FIGURE 2
and is transverse to its direction of elongation. The spot has been shown
elongated in order to impinge on all three rows of detectors simultaneously
using reasonably large detectors. If very thin rows of detectors were used,
the spot could be undistorted and still fall on all three rows simultaneously.
As mentioned above, the position of the image 120 along the array is indicative
of the range to the subject from which the energy is being reflected. For example,
a subject located quite far from the system would cause the line image 120 to be
in zone 1 crossing detectors 108, 112 and 118. As the subject moves closer to
the camera, the angle which axis 86 assumes causes the line i,mage 120 to
move to the left in FIGURE 1 to a grea~er and greater extent dependi,ng on the
distance to the subject. As a result, the energy shown by the line image
120 in FIGURE 2, will move from the right or infinity position through zones
1, 2, 3, 4, 5, 6, 7 until finally it arrives at zone 8 at which time the line
image 120 would strike detectors 100, 110 and 114.
In FIGURE 2, the dotted area detectors 100, 104 and 108 of ro~J A
are connected together to a line not shown in FIGURE 2 identified in FIGURF.
1 as a line 130 and the signal thereon is given the designation "a". The
blank areas 102 and 106 of row A in FIGURE 2 are connected together by a line
132 in FIGURE 1 and the signal thereon is given the designation "a"'. The
dotted detector 112 of row B in ~IGURE 2 is connected to a line 134 of FIGURE
1 and the signal thereon is given the designation "b". The blank detector
110 of row B in FIGURE 2 is connected to a line 136 in FIGURE 1 and the sig-
nal thereon is given the designation "b"'. The two dotted detectors 114 and
118 of row C in FIGURE 2 are connected together to a line 138 of I~IGURE 1 and
the signal thereon :is designated "c". Finally, the blank detector 116 of
row C in ~IGURE 2 is connected to a line 1~0 of FIGURE 1 and the signal
thereon is designated "c"'~ Whenever the line image 120 in FIGURE 2 strikes
the surface of a detector, that detector will produce a signal which will be
carried by one of the lines 130-1~0 to a signal processing circuit shown in
FIGURE 1 as the dashed box 150 and will produce either a digital "0" signal
or a digital "1" signal depending on whether a dotted or blank detector
received the image. It will be seen from FIGURE 2 that if the line of
anergy 120 is in ~one 1, then there will be an output from detectors 108,
112 and 118 and signals will be produced on lines 130, 134 and 138 which,
with the convention chosen will produce a "0", "0", "0" output from the
circuit to be described hereinafter. With the line image 120 positioned as
shown in FIGURE 2, detectors 106, 112 and 116 wil] produce outputs and these
signals will appear on lines 132, 134 and 140 respectively whic~" with the
convention used, will produce a "1", "0'~, "1" output. It will be apparent
that as the line image 120 moves to the left in FIGURE 2, it will strike
different detectors in differen-t zones and that the combination of signals
for each zone is unique.
The position of the line image 120 on the detector array in FIGURE
2, is not only a function of the range to the subject but also of the detector
lens focal length and the base distance between the two lenses 84 and 88 of
FIGURE 1. The displacement, d, of the line image 120 from the infinity pos-
ition may be given by the equation d = fB/R where f is the detector lens 88
focal length, B is the base distance between lenses 84 and 88 and R is the
range to the subject. If it is assunled that f is equal to 20 millimeters,
B is equal to 50 millimeters and R is equal to 1JOOO millimeters at the clo-
sest rangeJ the distance d becomes one millimeter. With this combination of
valuesJ the total length of the detector array then is one millimeter from
the infinity edge to the one meter edge. The width of each zone may ba
calculated from the e~ ression z = fB/Rl - fB/R2 where z is the zone widthJ
Rl the near range chosen for the zone and R2 the far range chosen for the zone.
Normally the zones are chosen to be of equal width so that lens 12 in FIGURE 1
will move substantially equal arnounts in changing focus from one range zone to
another. ThusJ with an array one millimeter wideJ each znne will be substant-
ially one eighth millimeter and the wid'ch of each detector in FIGURE 2 is one
eighth millimeter or slightly less due to the width of the border area between
adjacent detectors.
- 10 -
~3~ ~7
~anufacture of detectors with such small dimensions is not a difficult problem
with today's solid state manufacturing techni(~ues. Of course other ~/alues may
be used for desired near range, the base distance and the focal length and
the length of the array increased but those chosen above are fairly rep-
resentative for use on a standard hand held camera. FIGURE 2 may be composed
of different numbers of rows and different numbers of detectors per row in
order to vary the number of zones in accordance with the accuracy desired.
For example, if four zone accuracy was all that was necessary, then, as
shown in FIGURE 4 two rows of detectors could be employed and the first row
could contain a dotted small detector followed by a blank detector of twice
the width as the small detector and followed by a dotted detector of the same
width as the small detector while the second row could contain a pair of
detectors each twice as wide as the small detec~or, one of which was dotted
and one of which was blank. The arrangement of detectors in FIGURE 2 is
estahlished in the preferred embodiment so that as line image 120 moves from
one zone to another, the outp~t of only one detector at a time changes.
This produces an output of a type referred to as "gray code". Obviously, the
three rows AJ B and C may be placed in different order and other arrangements
of detectors could be established and still produce a gray coded arrangement.
Por example as is shown from right to left in FIGllRE 5, row A might have a
small dotted detector, a blank detector adjacent the small detector but four
times as wide and a dotted detector adjacent the blank detector and three
times as wide as the small detector while row B might have four detectors
alternating dotted and blank with each being twice as wide as the small
detector while row C might have a dotted detector three times as wide as the
small detector followed by a blank detector four times as wide as the small
~3~
detector and followed by a dotted detector the same width as the small
detector. Other arrangements will occur to those skilled in the art. Of
course, the detectors might also be arranged to produce a binary output but
with a binary code, more than one output can change at the same time. The
gray code of FIGURE 2 has the advantage of preventing a significant error
if the width of the line 120 were sufficient to expose two different detect-
ors in the same row. Thus, for example, if the line 120 were moved slightly
to the left in FIGURE 2 and covered bo*h detectors 104 and 106, then with
the convention used herein, either a "1", "O", "1" or a "O", "O", "1" output
might result from the circuitry to be described. Accordingly, the system
would respond so as tc focus the camera either in zone 3 or in zone 4. In
either case, it would be quite close to the desired focus position. On the
other hand, if more than one detector changed for each of the zones, then the
overlapping of two detectors in two or more rows could result and the system
might focus with a signi:Eicant error.
For exan~ple, in going from a binary 5 to a binary 6, the outputs
would change from "1", "O", "1" to "1", "1", "O" in which case an overlapping
of the line image might produce a "1", "O", "1", a "1", "1", "O", a "1", "1",
"1" or a "1", "O", "O", the latter two of which represent a binary 7 and
binary 4 respectively and the system would not focus in either the zone
represented by the binary S or the binary 6. In some applications, this
might be acceptable but in thc present invention, the gray coded array is
preferred. Accordingly, in designing the detector array, it is best to avoid
ha~ing two junctures or boundary areas between detectors in difEerent rows
positioned so that the line image can fall on both of them and, of course,
each of the zones must be unique having a different arrangement of dotted and
~3~ ~ ~
blank detectors therein.
'Jtilizing the equation d = fB/R and the chosen vari~bles for focal
length, base, range, and assuming zones of e~ual width, the distances for
subject range in each of the zones may be calculated. FIGURE 3 shows a chart
i.n which the eight zones are identified at the top of the columns and
directly below each zone is the distance in meters to the subjects located in
the far por~lon of that zone and the near portion of that zone. For example,
in zone 1, the subject may be from infinity to 8 meters, in zone 2, the sub-
ject may be between 8 meters and 4 meters, in zone 3, the subject may be
between 4 meters and 2.66 meters, in zone 4, the subject may be between 2.66
meters and 2.0 meters, in zone 5, the subject may be between 2.0 meters and
1.6 meters, in zone 6, ~he subject may be between l.6 meters and 1.33 meters,
in zone 7, the subject may be between 1.33 meters and 1.14 meters and in zone
8, the subject may be between 1.14 and 1.0 meters. In FIGURE 3, the outputs
of the detectors in rows A, B and C are shown for each of the zones and, as
will be further described below, it has been assumed that the dotted area
detectors of FIGURE 2 produce a "0" signal at the output of the signal pro-
cessing circuit 150 while the blank detectors produce a "1" signal when the
llne lmage 120 strikes thereon. As can be seen in FIGURE 3, the outpu-ts of
the three rows when the energy line is in the first zone will be A = 0,
B = 0 and C - 0. When the line image 120 is in zone 2 the output will be
A = 1, B = 0 and C = 0. In zone 3 the outputs will be A = 1, B = 0 and C = 1.
In zone 4 the outputs will be A = 0, B -- 0 and C = 1. In zone 5 the outputs
will be A = 0, B = 1 and C = l. In zone G the outputs will be A = 1, B = 1
and C = 1. In zone 7 the outputs will be A = 1, B = 1 and C = 0. In zone 8
the outputs will be A = 0, B = 1 and C = 0. The outputs A, B and C are
shown in FIGURE 1 as output lines 160, 162 and 164 emerging from the si~nal
processing circuit 150 and entering a converter circuit 166. Ihe purpose
of converter circuit 166 is to charlge the gray coded sign~ls A, B and C to
binary coded signals SJ M and L so as to more easily operate the solenoids
60, 62 and 64, as will be further explained hereinafter. The converted sig-
nals S, M and L produced by conver'cer 166 are shown on output lines
170, 172 and 174 of FIGURE 1 connected to the solenoids 64, 62 and 60 respec-
tively. The "S" signal on line 170 ccntrols the solenoid 64 operating the
small shim ~4, the "M" signal on line 172 controls the solenoid 62 operating
the medium sized shim 42 and the "L" signal on line 174 controls the sole-
noid 60 operating the large shim 40.
The converted signals S, M and L are shown in FIGURE 3 just below
the output signals A, B and C it is seen that in zone 1, the converted
signals are S = 0, L = 0 and M = 0. In zone 2, S = 1, L = 0 and M = 0. In
zone 3, S = 0, L = 0 and M = 1. In zone 4, S = l, L = 0 and M = 1. In zone
5, S = 0, L = 1 and M = 0. In zone 6, S = 1, L = 1 and M = 0. In zone 7,
S ~ OJ L = 1 and M = 1. In zone ~, S = 1, L = 1 and M = 1. As can be seen,
the outputs S, L and M are in binary form and, as such, are most advantageous
in performing the operations of properly energizing solenoids 60, 62 and 64
oE FIGURE 1.
For each zone detected, the lens 12 will be positioned at a pre-
determined location with respect to the infinity position. The positioning
of a 25 millimeter focal length ]ens for each of the zones is shown in the
fourth row in FIGVRE 3 and it is seen that in zone 1 the lens extension is
.0~ millimeters from the infinity position. This will produce an exactly
focussed subject at 15.6 meters as is indicated in the last row of FIGURE 3.
- 14 -
In zone 2) the lens extension will be .12 millimeters from the infinity pos-
ition and this will produce an exactly focussed subject located at 5.23 meters.
In zone 3, the lens extension will be .20 millimeters which will produce the
exact focus for subjects located at 3.14 meters. In zone 4, the lens exten-
sion will be .28 millimeters which will produce an exactly focussed subject
at 2.25 meters. In zone 5, the lens extension will be .36 millimeters which
will produce an exactly focussed subject at 1.76 meters. In zone 6 the lens
extension will be .44 millimeters which will produce an exactly focussed
subject at 1.44 meters. In zone 7 the lens extension will be .52 milli-
meters which will produce an exactly focussed subject at 1.23 meters. Inzone 8, the lens extension will be .60 millimeters which will produce an
exactly focussed subject at 1.06 meters. It is seen that ~or the values
chosen) the lens moves .08 millimeters for each zone change. Of course, with
the depth of field of the taking lens, satisfactory focus will be obtained for
subjects located throughout the zone and usually beyond. It is thus seen
that utilizing the eight zones created by the arrangement of detectors in
PIGURE 2, subjects located in any of the eight zones between one meter and
inflnity can be satisfactorily focussed by use of the present invention.
Referring again to FIGURE 1, as mentioned in connection with the
explanation of the detector array of FIGURE 2, the signals from the various
rows o~` detectors and identified as a, a', b, b', c and c' are presented on
lines 130-140 to the signal processing circuit l50. More specifically, the
a signal appearing on line 130 is presented through a junction point 200 to
an inverting amplifier 202 which has an output on a line 204. If energy is
being received by either detector 100, 104 or 108 of FIGURE 2, then an "a"
signal will appear on line 130 and by virtue of the inverting properties of
a~plifier 202, the phase of this signal will be reversed 180 degrees so chat
the signal appearing on line 204 will be 180 degrees out of phasc with the
signal being emitted from the LED modulator 80. If no energy is being re-
ceived by either detector 100, 104 or 108 of FIGURE 2, then there will be no
signal on line 130 and no output from amplifier 202 on line 204. In sirnilar
fa.shion, if either detectors 102 or 106 are receiving ener~y in FIGURE 2,
then an "a"' will appear on line 132 which signal is presented to a non-
inverting amplifier 206 having an output on line 208. The output on line
208 will be a signal in phase with the signal bei.ng emitted from LED mod-
ulator 80. On the other hand, if no energy is being received by eitherde~ector 102 or 106 in FIGURE 2, then there will be no signal on line 132
and there will be no in phase output signal on line 208. If energy is being
received by detector 112 in FIGURE 2, then a "b" signal will appear on line
134 which is presented through a junction point 210 to an inverting amplifier
212 having an output on line al4. Thus, if energy is being received by
detector 112, then a "b" signal will appear on line 134 and by virtue of the
inverter 212, a 180 degrees out-of-phase signal will appear on line 214. On
the othe~ hand, if no energy is being received by detector 112, then there will
be no signal on lines 134 or 214. If detector 110 is receiving energy in
~0 r~IGUI~ 2, then a "b"' signal will appear on line 136 which signal is presented
to a noninverting amplifier 216 having an output on line 218. If detector
110 of FIGURE 2 is receiving energy, then an in-phase signal will appear on
line 136 and a sirnilar in-phase signal will appear on line 218. On the other
hand, if detector llO is not receiving energy, then no signal will appear on
line 136 or on line 218. Similarly, if either detectors 114 or 118 of FIGURE
2 are receiving energy, then a "c" signal will appear on line 138 which signal
- 16 -
is presented through a junction point 220 to an invertillg amplifier 222 having
an output on line 224. Thus, if energy is bei.ng received by either detectors
114 or 118 of FIGURE 2, an in-phase signal will appear on line 138 and a 180
degree out-of-phase signal will appear on line 224. On the other hand, i~
no energy is being received by either detectors 1].4 or 118, then there will
be no signal on line 138 and on line 224. Finally, if energy is being rec-
eived by detector 116 of FIGURE 2, a "c"' signal will appear on line 140 of
FIGURE 1 which signal is presented to a noninverting amplifier 226 having an
output on line 228. If a signal appears on line 140 indicative of the fact
that energy is falling on detector 116 of FIGURE 2, an i.n-phase signal will
appear on line 228. On the o~her hand, if no signal is being received by
detector 116 of FIGURE 2, then no signal will appear on line 140 and on line
228 of FIGURE 1.
The signals appearing on lines 204 and 208 of FIGURe 1 are presented
through resistors 230 and 232 to a junction point 234 connected to an ampli~ier
236 having an output on a line 238. Resistors 230 and 232 act to sum the
signals that may appear on lines 204 and 208. Normally, the line image 120
of FIGURE 2 will only fall on a single detector in each row, but it may happen
tha.t the width of the line image 120 will cause energy to be received on two
2U adjacent detectors when the line image is close to the boarder between two
adjacent detectors. In the event "a" and "a"' signals may appear simultan-
eously on lines 130 and 132, an out-of-phase signal on line 204 will occur at
the same time an in-phase signal appears on line 208. However, in all but
the rarest of cases, more energy will fall on one detector than the other so
that the magnitude of the signal on line 204 will be larger than that on line
208 or vice versa. Depending upon ~hich of the signals is largest, an in-phase
or 180 degree out-of-phase signal will appear at junction point 234 and on
the outpu-t line 238 of amplifier 236. In similar fashion, the output signals
on lines 214 and 218 of FIGURE 1 are presented through resistors 240 and 242
to a junction point 244 which is connected to an amplifier 246 having an out-
put on line 248. As with the previously described summing circuit, under
normal conditions there will not simultaneously be a signal on both lines 214
and 218 b~t when the line image is proximate the junction between detectors
110 and 112 in FIGURE 2, energy may fall on both detectors thus producing
"b" and "b "' signals at the same time on lines 134 and 136 in FIGURE 1. Because
one of ihese signals will almost always be at least slightly larger than the
other, the summing resistors 240 and 242 will cause the predominate signal,
either in-phase or out-of-phase, to appear at junction point 244 and on the
output line 248 of amplifier 246. Finally, the signals appearing on lines
224 and 228 of FIGURE 1 are presented through resistors 250 and 252 to a
j~nction point 254 which is connected to the input of an amplifier 256 having
an output on a line 258. In a manner similar to that explained above, there
wilJ normally be only one signal either on line 224 or on line 228 but when
~he image line 120 o:E FIGURE 2 is near a junction point, there may simultan-
cously be "c" and "c~" signals on lines 138 and 140 of FIGURE 1. In either
case, any in-phase signal appearing on line 228 will be compared with any
180 degree out-of-phase signal appearing on line 224 so that the resultant
signal appearing at junction point 254 and on line 258 will be either in-phase
or out-of-phase indicative of which of the detectors is receiving all or more
of the energy in row C of FIGURE 2. Obviously, the gain of the noninverting
amplifiers 206, 216 and 226J ahould be the same as the gain of the inverters
202, 212 and 222 and if the gain of the inverters 2n2, 212 and 222 is one, then
~3~ ~
the noninverting amplifiers 206, 216 and 226 may be eliminated
The signals appearing on lines 238, 248 and 258 in FIGURE 1, indic-
ative of the detectors which are energized in each of the rows A, B and C of
FI~URE 2 are presented to phase detectors 260, 262 and 264 respectively. The
phase detectors also receive in-phase signals from an oscillator 268 via lines
270, 272 and 274. Phase detectors 260, 262 and 264 compare the phase appearing
on lines 238, 248 and 258 respectively with the in-phase signal from oscillator
268 so as to produce output signals on lines 280, 282 and 284 respectively
indicative of this phase comparison. The phase detectors operate to produce
a digital "1" signal whenever the inputs thereto are of the same phase, and
operate to produce a digital "0" when~ver the inputs ~hereto are of the
opposite phase. More specifically, if an in-phase signal appears on line 238
indicative of the fact that a signal "a"' on line 132 is of predominant mag-
nitude, phase detector 260 will have two in-phase inputs on lines 238 and 274
and the output on line 280 will be a "1" whereas if the signal on line 238
is 180 degrees out-of-phase from the signal on line 274 from oscillator 268
:ind:icative of the fact that an "a" signal on lin~ 130 is of predominant mag-
nitude, the output on line 280 will be a "0". In similar fashion7 if the
signal on line 248 is in-phase with the signal on line 272 from oscillator
268 indicative of the fact that a "b"' signal on line 136 is of predominant
magnitude, then a "1" output will appear on line 282 but if the signal on
line 248 is 180 degrees out-of-phase with the signal on line 272 from
oscillator 268 indicative of the fact that a "b" signal on line 134 is of
predominant magnitude, then a "0" signal will appear on line 282. Finally,
iE the signal on line 258 is in-phase with the signal on line 270 from
osc:illator 268 indicative of the fact that a "c"' signal on line 140 is of
- 19 -
predominant magnitude, then a "1" signal will appear on line 284 but if the
signal on line 258 is 180 deg-rees out-of-phase with the si~nal on line 270 froM
oscillator 268, indicative of the fact -that a "c" signal on line 138 is of
predominant magnitude, then a "0" signal will appear on line 2~4. The signals
on lines 280, 282 and 284 are identified as the outputs A, B and C from the
signal processi.ng circuit 150 in FIGURE 1 and these signals will be either
"1" or "0" signa]s depending on the position of line image 120 in FIGURE 2.
Capacitors 290, 292 and 294 are connected between the outputs of phase det-
ectors 260, 262 and 264 and signal ground respectively so as to smooth the A,
B and C signals and reduce noise and also any ripple that is usually inherent
in phase detectors.
Oscillator 268 has an output on a line 296 that is presented through
capacitors 298, 300 and 302 respectively to lines 130, 134 and 138. The
purpose of these connections is to produce a slight in-phase signal on lines
130, ].34 and 138 respectively so that in the absence of any signal at all
from the detectors of FIGURE 2, as would occur when the range to the remote
object was quite large, there will be out-of-phase signals on lines 204, 214
and 224 and thus on lines 238, 248 ancl 258 so that the output signals A, B
and C will b~.all "0's" and the apparatus will operate to focus at infinity
or the hyperfocal distance as will be further explained hereinafter. It should
also be noticed that since the bias provided by capacitors 298, 300 and 302
.is slightly larger than any noise expected to be encountered but smaller
than the signals from the detectors, the dotted detectors of FIGURE 2 could
be eliminated entirely if desired, since when the line image 120 falls upon
an empty space rather than a dotted detector, the bias produced by capacitors
298, 300 and 302 provides a signal to inverters 202, 212 and 222 with the
- 20 -
3~ ~7
same result as if the line image had impinged upon a dotted detector. In prac-
tice, however, since the production of the detectors is quite easy, it is pre-
ferred to have both the blank and the dotted detectors in the array because
it is better to have a well defined signal than the small bias signal when
the energy implnges on a dotted detector. If the bias were increased to give
a larger signal, then with the remote objects, the energy impinging on a
detector might decrease below the bias level and signals from the blank
detectors would be overpowered by the bias signal resulting in a false indi-
cat on~
Oscillator 268 has a final output on a line 304 which is presented
to the LED modulator 80 for purposes of modulating the IR beam eminating from
lens 84 and establishing the in-phase signal.
The "A" signal from signal processing circuit 150 appearing on line
160 is presented to converter circuit 166 by a line 310 connected to one
input of an exclusive OR gate 312 which has an output on a line 314 identified
as the "S" output. The "B" output from signal processing circuit.l50
appearing on li.ne 162 is presented to converter circuit 166 through a junction
point 320 to a line 322 which is identi~ied as -the "L" output. The "C" out-
put Erom signal processing circuit 150 appearing on line 164 is presented to
converter circuit 166 by a line 326 to one input of an exclusive OR gate 328
having an output on line 330. The output on line 330 is presented through a
junction point 334 to a line 336 identified as the "M" output. Junction point
320 is connected by a line 340 to the other input of exclusive OR gate 328
and junction point 334 is connected by a line 344 to the other input of exc-
lusive OR gate 312. The outputs S, L and M on lines 314, 322 and 336 are
connected to conductors 170, 174 and 172 leading to solenoids 64, 60 and 62
respectively. The signals S, L and M cause the positioning of small shim 44
large shim 44 and medium shim 42 respectively between abutment 36 and
moveable member 46 for purposes of properly positioning lens 12. The outputs
S, L and M are also connected by lines 350, 352 and 354 respectively to a
zone decoder box 356 which may be of the binary to octal decoder t-ype shown
in FIGURE 4-12 of Section 4-8 on page 109 of "Computer Logic Design" by M.
Morris Mano published by Prentice-Hall, Inc., Englewood Cliffs, New Jersey.
Such a device receives three binary coded signals and operates to provide
eight output signals which are shown in FIGURE l connected to eight indicating
devices identified by reference numerals 360-367. Zone decoder 356 will
analyzc the signals on lines 350, 352 and 354 indicative of the S, L and M
signals and will produce indications on indicators 360 through 367 indic-
ative of which of the zones 1 through 8 of FIGURE 2 the line image 120
impinges upon. This will provide a visu~l indication to the photographer of
what zone the camera is focussing on.
If the signals A, B and C are all O, then the exclusive OR gates
312 and 328 of converter 166 will operate to produce "O" signals on all three
lines 314, 322 and 336 and thus none of the solenoids 60, 62 and 64 will be
activated. ~his occurs when the energy line 120 of FIGURE 2 is in the in-
finity position or zone l of FIGURE 2. As a result, when the latch member
118 releases the lens mounting 14, abutment 36 will move down until it
contacts moveable member 46 and both lens mounting 14 and moveable member
46 will move a distance equal to the spacing ~8 before coming to rest. The
length of member 46 is chosen to provide the lens extension necessary for
the zone 1 which is .04 millimeters and is the hyperfocal position. Thus
when the lens 12 comes to rest and shutter release switch 5~ is actuated, the
- 22 -
3~'7
lens will be in the proper position for subjects located between 8 meters and
in:Einity rom the camera. Of course, member 46 could be firmly mounted aga-
inst the fixed member 50 but then alternate arrangements would have to be used
to actuate switch 54.
In zone 2 when the output A is a "1", the output B is a "O" and
the output C is a "1", the e~clusive OR gates 312 and 328 will operate so
that the output S is a "1", the output L is a "O" and the output M is a "O".
Under these circumstances, a signal will appear on line 170 but not on lines
172 and '7~i and sole~oid 64 alone will be actuated so as to insert shim 44
between ~ ent 36 and moveable member 46. ~him 44 is chosen to have a
width Oc .o~, millimeters and accordingly, when latch member 18 releases lens
mounting 1~1~ abutment 36 will move until it contacts shim 44 and together they
will move until they contact moveable member 46 and an additional amount of
movement will be allowed due to the spacing 48. As a result, the lens mounting
will come to rest at a position which is the sum of .04 millimeters representing
the hyperfocal position and the .08 millimeter width of shim 44. The lens
housing will there~ore stop in a position which is .12 millimeters from the
in:~inity position which, as seen in FIGURE 3, is the zone 2 lens extension
pos:ition and subjects between 8 meters and 4 meters frsm the camera will
be properly focussed, In zone 3, the outputs A, B and C are 1, 0 and 1 res-
pectively and the exclusive OR circuits 312 and 328 operate to produce the
signals S = O, L = O and M = 1. As a result, solenoid 62 will be actuated
and shim 42 will be moved in between abutment 36 and moveable member 46. Shim
42 is chosen to have a width of .16 millimeters and accordingly, when latch
member 18 releases lens mounting 14, abutment 36 will move down until it
contacts shim 42 and they together will move until they contact moveable
member 46 and all three will move the distance provide~ by space 4~ at whic~l
time the shutter release mechanism 54 is actuated. In this position, the lens
mounting is located the sum of .04 millimeters+.16 millimeters = .2 milli-
meters which is the proper setting for zone 3 and subjects bet~een 4 meters
and 2.66 meters will be properly focussed. In zone 4, the outputs A, B and
C are "0", "0" and "1" respectively and the exclusive OR gates 312 and 338
operate to produce the signals S = 1, L-= 0 and M = 1 for zone 4. As a
result, s~lenoid 6~ and 62 will be actuated and the small and medium shims
44 and 42 respective]y will both be inserted between the abutment 36 and the
moveable member 46. As a result, when the lens mounting comes to rest, its
position will be the sum of .04 millimeters, shim 44's width and shim 42's
width which totals .28 millimeters and is the correct position for zone 4 so
that subjects between 2.66 meters and 2 meters will be properly focussed. In
zone 5, the A, B and C outputs are "0", "1" and "1" and the converted outputs
S, L and M become "0", "1" and "0" respectively. Under these circumstances,
solenoid 60 is actuated and large shim 40 is inserted between abutment 36 and
moveable member 46. Shim 40 has a width of .32 millimeters and as a result,
the lens mounting 14 will come to a rest position represen~ing the sum of the
width of shim 40 and .04 millime-ters, the total of which is .36 millimeters.
Th:Ls is the oorrect position for zone 5 and subjects between 2 meters and 1.6
meters will be properly focussed. In zone 6, the A, B and C signals each
become "l~s" and the converted signals S, L and M become "1", "1~' and "0"
respectively. Under these circumstances solenoids 60 and 64 will be actuated
inserting shims 40 and 44 between abutment 36 and moveable member 46. The
lens mounting 14 will therefore come to a rest position which is .44 milli-
meters from the infinity position and subjects between 1.6 meters and 1.33
- 24 -
meters will be in focus. In zone 7, the outputs A, B and C are "1", "1" and
''O''respectively and the outputs of the conversion circuit 166 become S - 0,
L = 1 and M = 1. Under these circumstances, solenoids 60 an~ 62 will be
actuated and shims 40 and 42 will be inserted between abutment 36 and move-
able member 46. The lens mounting will therefore come to a rest position at
.52 millimeters from the infinity position and subjects between 1.33 meters
and 1.14 meters will be in focus. Finally, in zone 8 the outputs A, B and
C are 0, 1, 0 respectively and the converted outputs S, L and M become 1, 1
and 1 respectively. Under these circumstances, all of the solenoids 60, 62
and 64 will be actuated and all of the shims 40, 42 and 44 will be inserted
between abutment 36 and moveable member 46. Thus, when the lens mounting
14 comes to rest, it will be in a position representative of the sums of
the thicknesses of the shims plus .04 millimeters. This sum is .60 milli-
meters, the oorrect distance for the lens extension in zone 8 and subjects
between 1.14 meters and l meter will be properly focussed.
It is thus seen that I have provided an active auto :Focus system
employlng a novel detector which can determine in which of 8 zones a light
image is present with each of the zones representing a different range from
the camera to the subject. It is seen that my system is not complex and
may be easily and inexpensively produced. It is also seen that I have pro-
vided a novel, accurate and inexpensive arrangement for moving the lens to
the correct focus posi.tion without the use of electrical motors. Many obvious
alterations will occur to those skilled in the art and I do not wish to be
limited by the specific disclosures used in connection with the preferred
embodiment. I intend only to be limited by the following claims.
- 25 -
