Automatic focusing mechanism for camera

An automatic focusing camera is operated between daylight and flash modes automatically responsively to ambient light photosensings. The lens is operable between a near-focus setting and a far-focus setting, taking the far-focus setting automatically in the daylight mode. In flash mode the aperture is automatically set to its maximum value, whereas in daylight mode the aperture is automatically set to one of at least two reduced aperture settings. The largest aperture setting in daylight mode is the hyperfocal aperture setting corresponding to the far-focus lens setting. A further reduction in aperture below the hyperfocal value is governed by a filmspeed entry system and ambient light sensings. The changeover threshold between daylight and flash mode is also governed by the filmspeed entry system.

TECHNICAL FIELD 
The technical field of the invention is photographic cameras, and in 
particular cameras which provide an automatic focusing feature. 
BACKGROUND OF THE INVENTION 
A large number of relatively inexpensive still cameras are currently 
manufactured which provide an automatic focusing capability and/or 
automatic exposure control governed by either ambient illumination for 
outdoor photography or by a sensing of the object distance when used in 
flash mode. Ranging sensings used to govern lens focusing, as well as 
exposure during flash mode, are provided by a variety of systems. Ranging 
by ultrasonic pulses produced by the camera, electronic comparison of the 
images in a split-image rangefinder, and the reflected amplitude of an 
infra-red preflash all are well-described in the patent literature. In 
flash mode, exposure control is governed typically by one of the 
aforementioned range sensings, whereas in the ambient illumination mode, 
some form of weighted value of the scene illumination as detected by a 
photosensor is typically used to govern exposure. 
In the case of intermediate and higher-priced cameras, such systems are 
routinely provided. On the other hand, in the case of the low-cost camera, 
the expense of providing such range-sensing systems becomes prohibitive. 
Moreover, such low-cost cameras are not in general purchased by for the 
serious amateur, but rather by people who either use a camera only on rare 
occasions, or who are relatively inexperienced, or both. Even the most 
rudimentary manual exposure and focus adjustments are frequently 
overlooked by such users. 
Thus, there remains a need in the low-priced camera field for a completely 
automatic focus and exposure system which will give adequate results both 
as to focus and exposure in totally inexperienced hands. 
SUMMARY OF THE INVENTION 
According to one of the features of the invention of the parent 
application, a camera having flash capability is provided with an ambient 
illumination sensor and a lens focusable between near and far focus 
settings and is automatically coupled to operate a two-position exposure 
control When the detected ambient light is low, implying a need for flash 
illumination, upon actuation of the shutter release mechanism, associated 
control mechanisms set the shutter aperture to its maximum value, e.g., 
f/4.5, while simultaneously setting the lens focus to a near-zone focusing 
range of 5 to 12 feet. Thus, the reduced depth of field associated with 
large shutter aperture is compensated for by adjusting the lens to a 
focusing range appropriate for short-range flash work. On the other hand, 
in the event that adequate ambient illumination is sensed, as is normally 
the case in outdoor photographic work during bright daylight hours, a 
focus-aperture combination is automatically commanded providing for a 
reduced aperture, e.g., f/8, and a focus setting where the lens is set to 
the hyperfocal distance corresponding to that aperture, such as 12 feet 
for a 55 mm. lens. By this means, during daylight exposures, the camera is 
automatically set for sharp focus from half the hyperfocal distance to 
infinity The need for an expensive range sensing system is thus totally 
eliminated. 
According to a feature of the present invention, a further reduction of the 
aperture below f/8 than that corresponding to the hyperfocal lens setting 
is provided automatically for use with higher speed photographic films. 
This has the effect of further sharpening the photographic image of 
objects positioned close to the boundaries of the depth of field, i.e., 6 
feet and infinity. According to a related feature of the invention, the 
changeover from daylight to flash mode is also governed by filmspeed 
sensings. 
Other advantages and aspects of the invention will become apparent upon 
making reference to the specification, claims, and drawings to follow. 
While it is possible that there may have been prior camera systems which 
used manual settings of a two-position focus system usable selectively in 
manually set flash and normal modes of operation, no cameras having 
automatic settings of these parameters have to the applicant's knowledge 
been heretofore produced.

DETAILED DESCRIPTION 
The subject matter of the invention is an aperture and focus adjusting 
system for a camera governed solely by ambient light sensings. FIGS. 1 and 
5 show in partially cutaway form the arrangement of the principal elements 
of the system. The system as shown in FIG. 1 is in a dormant cocked 
condition. A lens focusing ring 7 is coupled so as to move a 
picture-taking lens 50 (see FIG. 7) along the optic axis 30 of the system. 
As seen in FIG. 1, counterclockwise rotation of the focusing ring 7 moves 
the focusing range of the lens 50 from a short-focus to a long-focus 
position. This counterclockwise movement of the focusing ring 7 is induced 
by a spring 8 coupled thereto. A focus control solenoid 13 is selectively 
actuated by a photosensor-controlled sensor flash system 42 (FIG. 9) to 
act upon an armature 12 attached to a focus locking lever 9 rotatably 
mounted upon a pivot 10 and urged clockwise by a tensioning spring 11. A 
pawl end 9a generally confronts the outer rim of the focusing ring 7, 
either in a generally retracted position shown in FIG. 1, or alternatively 
to a released condition so that the pawl will lockingly engage a notch 7b 
in the focusing ring to arrest rotation of the focusing ring during 
adjustment of the system. 
A pair of aperture-controlling blades 27,28 overlie each other, each blade 
being pivotally mounted to a common pivot 29. Each blade is provided with 
a cutout slot 27a -28a positioned so that a common entry region is formed 
therebetween, through which a pin 26 mounted on an aperture control slide 
21 passes. The cutout slots 27a,28a are angled with respect to each other 
such that a leftward movement of the pin 26 will cause the blades to swing 
together so as to close down the aperture of the optical system. Thus, 
according to whether the pin 26 is moved to the right or to the left, the 
aperture of the camera can be adjusted between extreme values. 
The aperture control slide 21 is slidably mounted on guide pins 22-22 and 
captively retained by retention bosses 22a-22a (FIG. 6) mounted on a main 
mounting wall 35, permitting general left-right motion of the aperture 
control slide 21 as seen in FIG. 1. The aperture control slide 21 is urged 
to the left by a spring 36. An aperture control solenoid 25 is positioned 
to contactingly engage an armature 24 captively retained in the righthand 
end of the aperture control slide when the system is in a cocked position, 
and is capable of overcoming the tensile force of the spring 36. 
A lens cocking slide 2 is slidably mounted on the front surface of the main 
mounting wall 35 by means of pins 3-3 and captively secured thereto by 
retention bosses 3a-3a. The lens cocking slide 2 is thus also linearly 
slidable between left and right positions thereof as seen in FIG. 1. 
A focus release lever 4, rotatably mounted on a pivot 5, is urged clockwise 
by a restoring spring 6, and is provided with a notch 4a configured to 
lockingly confront an extension tab 2a on the lens cocking slide 2, 
thereby holding this element is its rightmost position. The lens cocking 
slide 2, in turn, engages a pin 23 on the aperture control slide 21 to 
hold the aperture control slide in its rightmost condition with its 
armature 24 contacting the aperture control solenoid 25, against the force 
of its restoring spring 36. This configuration also holds the focusing 
ring 7 in an extreme clockwise position against the force of the focusing 
ring actuating spring 8 by engagement of the extension tab 2a with a boss 
E extending outwardly from the periphery of the focusing ring from a 
shoulder line S. 
Rotating the focus release lever 4 counterclockwise sufficiently to 
disengage from the extension tab 2a will remove the opposing force from 
the focusing ring boss E, allowing the focusing ring 7 to be driven 
counterclockwise by its energizing spring 8. No opposition is encountered 
from the lens cocking slide 2, since this element is not directly spring 
biased. If the aperture control solenoid 25 remains energized during this 
operation, the focusing ring boss E will merely drive the lens cocking 
slide 2 along with it as it rotates. In the event that the aperture 
control solenoid 25 is not energized during this phase, the aperture 
control slide 21 will further be driven in the same direction by 
engagement with pin 23. The principal function of the lens cocking slide 2 
is merely to restore the system to a cocked condition during a 
film-advancing operation. 
Considering next the basic sequence of operations of the various systems 
shown during a picture-taking operation, pressure applied to a shutter 
button (not shown) acts on a release slide 14, slidably mounted on pins 
15-15, to move downward. The immediate effect of initial downward movement 
is to cause switch contacts 19-20 to be urged into contact by a camming 
surface 44 on the release slide 14. This causes immediate actuation of the 
focus activation switch 46 (FIG. 9), representing switch contacts 19-20, 
to a closed condition to actuate one of the two solenoids 13,25 to an "ON" 
condition, according to sensings of a ambient illumination sensor 48. 
Further depression of the slide release 14 causes a cutout 50 to engage 
one end of the focus release lever 4, causing a counterclockwise rotation 
thereof, thereby causing the notch 4a in the end of the focus release 
lever to move out of its confronting position with respect to extension 
tab 2a of the lens cocking slide 2. As will subsequently be discussed in 
detail, the focus and aperture systems then proceed to go through 
independent adjustment. 
The release slide 14 has a cutout 14a therein through which an extension 
16a of a shutter release member 16, urged upward by an energizing spring 
17, extends. The cutout 14a is configured sufficiently long that with the 
release slide 14 in its uppermost position, a substantial distance is 
provided between the upper edge of the cutout 14a and the confronting edge 
of the extension 16a of the shutter release member. A shutter energizing 
slide 18 is captively held in the cocked position by the shutter release 
member 16, and is urged to the left by a slide energizing spring (not 
shown). A final terminal downward movement of the shutter release member 
16 after system adjustments are complete will cause release of the shutter 
energizing slide, whereupon it snaps to the left so as to actuate the 
shutter (not shown) through an exposure cycle. Release of downward 
pressure to the release slide 14 causes the slide to move upward under the 
influence of an associated biasing spring (not shown) so as to allow the 
switch contacts 19,20 to spring apart to allow reversion of the solenoids 
13,25 to a dormant non-energized condition. This state of affairs is best 
shown in FIG. 4. 
The particular form of shutter release and recocking system energized by 
the shutter energizing slide 18 may take a great variety of forms, such as 
that disclosed in the applicant's U.S. Pat. No. 4,595,261 issued June 17, 
1986. This application discloses, among other things, the use of an 
eccentric pin driven by the film-advancing system to drive a shutter 
energizing slide 18 of the form shown in FIG. 1 to a cocked position 
during film advance. Restoration of the system to a cocked condition from 
the de-energized configuration shown in FIG. 4 to that shown in FIG. 1 is 
carried out by a similar eccentric-pin system, which may in fact be 
coupled to or be integral with the eccentric pin system restoring the 
shutter energizing slide 18 to a cocked condition. 
Thus, with particular reference to FIGS. 1, 4 and 6, an eccentric pin 1a 
mounted on a cocking rotor 1 is brought to bear against a cocking 
extension 2b on the lens cocking slide 2, so that an initial half rotation 
from the de-energized condition shown in FIG. 6 moves the lens cocking 
slide to its extreme rightmost position. Recalling that the focus release 
lever 4 is biased clockwise during rewind, during this half rotation of 
the cocking rotor 1 the extension boss E on the focusing ring 7 is first 
engaged by the extension tab 2a on the lens cocking slide to rotate the 
focusing ring 7 counterclockwise. Since the solenoids 13,25 are 
de-energized during rewind, the aperture control slide 21 will be in its 
leftward position as shown in FIG. 3, as a result of which the lens 
cocking slide 2 will be driven to engage pin 23 on the aperture control 
slide to move the aperture control slide into contact with the aperture 
control solenoid 25. During the terminal phases of this process, the notch 
4a of the focus release lever 4 again drops into a latching engagement 
with the extension tab 2a of the lens cocking slide 2 to latch the entire 
system in the dormant cocked condition shown in FIG. 1. 
Considering next in detail the operation of the focusing and aperture 
control subsystems of the camera during the picture-taking operation, it 
will be recalled that one of the two solenoids 13,25 is selectively 
energized according to an ambient light photosensor. Details of the 
control circuit shown in FIG. 9 for accomplishing this will be discussed 
subsequently. For the moment it is sufficient to say that during the 
picture-taking operation, if the ambient light is weak, indicating that 
the camera is to be used in flash mode ("near" mode), the aperture control 
solenoid 25 will be energized throughout the picture-taking process. The 
focus control solenoid 13 will remain de-energized. Thus, with reference 
to FIG. 2, it will be seen that upon release of the engagement between the 
notch 4a of the focus release lever 4 and the extension tab 2a of the lens 
cocking slide 2, the lens focusing ring 7 is immediately urged 
counterclockwise. Since the focus control solenoid 13 is de-energized, the 
pawl 9a on the end of the focus locking lever 9 is spring-urged against 
the rim of the focusing ring 7, and drops into the focusing ring locking 
notch 7b to arrest the rotation of the focusing ring before substantial 
rotation has occurred. As will subsequently be shown, this rotation is 
insufficient to move the lens 50 from its short-range focusing position, 
as a result of which the lens remains focused at an optimum distance of 
approximately 7 feet. 
It will be noted in FIG. 2 that the freely movable lens clocking slide 2 
has been impulsively urged to the extreme leftmost limit of its travel by 
the impulse delivered thereto by the boss E on the focusing ring 7 during 
initial rotation of the focusing ring. Further, it will be noted that by 
retaining the aperture control solenoid 25 in an energized condition 
throughout this process, the aperture control slide 21 remains retained in 
its rightmost position against the force of its associated spring 36, 
holding pin 26 similarly in the rightmost position thereof, as a result of 
which the aperture blades 27,28 remain in the wide-aperture condition. The 
camera has thus been properly conditioned for "near" (flash) mode 
operation with the lens set to a short focusing distance and the aperture 
held at its maximum value. Taking a nominal value of f/4.5 for a 55 mm. 
lens, this yields a properly focused field extending from 5 feet to 12 
feet. These values are appropriate for the normal working range of 
inexpensive flash cameras. 
If, on the other hand, a bright ambient sensing is detected by the 
photosensor 48, with the camera still in the cocked state shown in FIG. 1, 
the focus control solenoid 13 will be energized, whereas the aperture 
control solenoid 25 will remain de-energized. This will cause the camera 
to be set to a "far" mode. The state of affairs in this case immediately 
after disengagement of the focus release lever notch 4a from the extension 
tab 2a of the lens cocking slide 2 is shown in FIG. 3. With respect to the 
movement of the lens focusing ring 7, the focus locking lever 9 is 
maintained in a retracted position, as a result of which the lens focusing 
ring 7 rotates counterclockwise by a substantial amount. The rotation is 
terminated by the engagement of the extension boss E of the focusing ring 
7 against the extension tab 2a of the lens cocking slide 2 when the lens 
cocking slide is driven to its extreme leftmost position to be arrested by 
engagement with its associated guide pins 3,3. As will subsequently be 
shown, this rotation is sufficient to move the lens to a long-focus 
(non-flash) position, preferably yielding a hyperfocal distance of 12 
feet, thereby providing sharp focus from 6 feet to infinity. 
With respect to the aperture control system, it will be noted that with the 
aperture control solenoid 25 de-energized, the aperture control slide 21 
is free to move to the left, the lens cocking slide 2 having completely 
outrun pin 23 on the aperture control slide, with the result that the 
aperture control slide moves to the left. This has the effect of driving 
the aperture blade control pin 26 to the left along the cutout slots 
27a,28a in the aperture blades 27,28, thereby swinging the blades together 
to a reduced aperture position. This reduced aperture position is chosen 
in conjunction with the focal length and focus position of the lens 50 
with the lens focusing ring 7 rotated as shown in FIG. 3 to provide for 
the previously mentioned optimum hyperfocal distance of 12 feet. This is 
achieved by configuring the aperture control blades 27,28 so that in the 
reduced aperture configuration shown in FIG. 3 a focal ratio of 
approximately f/8 is established in the system. 
Details of the mechanism whereby rotation of the focus control ring 7 moves 
the lens 50 between the two focusing positions thereof are best shown in 
FIGS. 5, 6, 7 and 8. A lens cell assembly 54 securely retains the 
objective lens 50 therein, the lens cell assembly having a cylindrical 
outer surface 62 configured to slidingly pass within an aperture 60 in a 
front wall 33 of the camera. A main mounting wall 35 is provided with a 
cylindrical passage 56 coaxially disposed with respect to the front wall 
aperture 60. The lens cell assembly 54 is fixedly secured to the focusing 
ring 70. A wave spring 32 disposed between the front surface 62 of the 
focusing ring and the rear surface 64 of the front wall serves to urge the 
lens cell assembly 54 away from the front wall. Four forwardly extending 
slanting ramps 31 are fixed to extend forwardly of the main mounting wall 
35. The inward action of the wave spring 32 serves to force the rear 
surface 7b of the focusing ring against these ramps. The location of these 
ramps 31-31 is shown in dotted outline in FIGS. 1-4 also. With the 
focusing ring 7 in a cocked position (FIG. 1) or slightly rotated as shown 
in (FIG. 2--near mode) the ramps 31-31 urge the lens cell assembly to its 
forwardmost position with respect to the film plane FP. 
To allow for distant focusing (far mode), four ramp-shaped recesses 7a-7a 
are provided in the rear surface 7b of the focusing ring 7. Upon full 
counterclockwise rotation of the focusing ring 7 as shown in FIG. 3, these 
recesses 7a are rotated to confront their associated ramp elements 31, 
with the result that the wave spring 32 forces the focusing ring to its 
rearmost position as shown in FIG. 6. This establishes the lens in the 
distant-focus condition. Ramp surfaces 68-68 at the ends of the recesses 
7a-7a allow the focusing ring 7 to be urged forward once again when the 
focusing ring is rotated clockwise during the cocking operation. 
One form of representative control circuit for carrying out the 
aforementioned synchronization of the solenoids 13,25 during exposure is 
shown in FIG. 9. A sensor flash system 42 responsively coupled to a 
photosensor 48 is powered from a source of direct voltage supplied to 
lines 76,78 via terminals 80,82 respectively. The sensor flash system may 
take a variety of forms that will be apparent to those knowledgable in the 
art, and as configured for the present system responds to a high ambient 
illumination sensing by the photosensor 48 to put an output control line 
82 into a "low" state. A flash lamp 72 is energized by a flash exciter 70. 
Internal logic circuitry (not shown, but of conventional design) internal 
to the flash exciter 70 will disable the exciter from triggering the flash 
lamp 72 whenever control line 74 is low, i.e., under high illumination 
conditions. 
If, on the other hand, the photosensor reads a low ambient signal, the 
enable/disable line 74 is in a "high" state, causing the flash exciter 70 
to energize the flash lamp 72 upon closure of a shutter synchronization 
switch 75 (not shown in other drawings) appropriately coupled to trigger 
the flash lamp when the camera shutter is fully open. The state of the 
output control line 82 of the sensor flash system 42 is passed through a 
resistor R1 to apply a bias to the base of transistor Q1, having the coil 
of the focusing solenoid 13 connected between the collector thereof and 
negative power line 78. The emitter of transistor Q1 is connected directly 
to the positive power line 76. A second transistor Q2 similarly has its 
emitter connected to the positive power line 76, and has its collector 
connected to the negative power line 78 through the aperture control 
colenoid 25. The base of transistor Q2 is biased through a resistor R2 
connected to the collector of transistor Q1. 
Considering the actions of transistors Q1 and Q2 in terms of the base bias 
signal applied to transistor Q1 through resistor R1 via control line 82, 
it is clear that when the base of transistor Q1 is low (high 
illumination/far mode), transistor Q1 will be turned on, thereby 
energizing the focusing solenoid 13. Since the base-emitter junction of 
transistor Q2 is connected across the collector-emitter leads of 
transistor Q1, it follows that transistor Q2 must under such circumstances 
be turned off, as a result of which the aperture solenoid 25 is also 
turned off. Conversely, by raising the signal level on line 82 
sufficiently, transistor Q1 is turned off and transistor Q2 is turned on. 
Thus, according to the output signal level on line 82, selective actuation 
of the two solenoids 13,25 is achieved simply by the magnitude of the 
ambient light level sensings of the photosensor 48. System power is 
supplied to the transistors Q1,Q2 through a power switch 46, here taken to 
comprise the blade elements 19,20 shown in FIGS. 1-4. 
In the daylight (far) mode provision may be made for aperture settings less 
than the previously described hyperfocal setting. This may be done, for 
example, by restricting the leftward travel of pin 26 (FIGS. 1-4) at one 
or more intermediate positions. FIGS. 10 and 11 show an electrically 
controlled solenoid latch system providing two far mode aperture settings. 
Thus, with particular reference to FIG. 10, a solenoid 100 having an arm 
assembly 94 rotatable about a pivot 97 is spring-loaded (by means not 
shown) to urge the pole piece 96 mounted thereon away from the solenoid. 
The solenoid 100 may be selectively actuated by a photosensing-related 
control signal from the control circuit 42 of FIG. 9. The arm assembly 94 
is configured with a hook extension 95 at the end thereof, this extension 
having an engaging face 102 provided thereon. An extension portion 90 of 
the aperture control slide 21 is similarly configured with a hook-shaped 
extension 90 having an engaging face 92. 
FIG. 10 shows the system with the solenoid deenergized and the confronting 
faces 92,102 offset from each other to allow maximum leftward travel of 
the aperture control slide 21. FIG. 11 shows the effect of energizing the 
solenoid 100 prior to movement of the aperture control slide 21. Here the 
engaging faces 92,102 are in a confronting relationship, and the movement 
of the aperture control slide 21 is prematurely terminated. 
The aperture-controlling blades 27,28 are configured so that with the 
aperture slide in this intermediate position, the blades provide the 
proper setting, e.g., f/8, corresponding to a hyperfocal distance of 12 
feet as previously described. The solenoid 100 is therefore to be 
energized when either the filmspeed or the ambient light is relatively 
low, requiring an aperture of f/8. During high ambient light conditions, 
or alternatively for cases of substantially higher filmspeed ratings, the 
solenoid 100 is held deenergized throughout the aperture-adjusting 
process, and the aperture control slide 21 moves fully to the left as 
shown in FIG. 10. In this condition the configuration of the shutter 
blades 27,28 is configured such that the effective aperture is 
substantially smaller, i.e., higher f-stop value, than that corresponding 
to the hyperfocal distance. This will have the effect of not only 
correcting the exposure, but also of sharpening up the extreme ends of the 
hyperfocal range by reducing the diameter of the circle of confusion for 
objects at infinity and 6 feet. This will contribute to overall picture 
clarity for objects not placed exactly at the optimal focal distance of 12 
feet. 
Filmspeed information may be entered into the control circuitry of the 
sensor flash system 42 (FIG. 9) by variety of forms well known in the art 
to control the slide control solenoid 100. The filmspeed entry system 102 
may take the simple form of a user-operated switch S operable between two 
states corresponding to two substantially different filmspeed values. 
Alternatively, such sensings may readily be derived from the 
filmspeed-indicating areas currently being manufactured on the outer 
surface of 35 mm. film cassettes. In the simplest case, the switch S may 
be inserted directly in series with the solenoid 100. This will not, 
however, allow filmspeed to control the changeover between flash and 
ambient modes. Thus, the changeover between ambient illumination mode and 
flash mode may be controlled according to ambient illumination and 
filmspeed, as may the selection of the desired value of aperture stop when 
in the far-focus mode. It will be equally evident that a number of such 
intermediate stop positions may be provided by straightforward extension 
of the principles set forth hereinabove. 
Thus, there has been described a system of automatic focus and aperture 
control, based solely upon ambient illumination sensings, which provides 
automatically for near focusing and maximum aperture so as to provide 
adequate depth of field within the relatively restricted object distance 
ranges characteristic of flash photography when the ambient illumination 
is low, and which further provides for an automatic reversion under high 
ambient illumination to place the lens-aperture combination at the 
hyperfocal distance, i.e., that distance placing the far edge of the field 
depth at infinity. The necessity for relatively expensive range-sensing 
systems is eliminated, and by inexpensive means a low-cost camera is 
provided which is well-suited to the needs of the occasional photographer. 
While the invention has been described with reference to a preferred 
embodiment, it will be understood by those skilled in the art that various 
changes may be made and equivalents may be substituted for elements 
thereof without departing from the broader aspects of the invention. Also, 
it is intended that broad claims not specifying details of a particular 
embodiment disclosed herein as the best mode contemplated for carrying out 
the invention should not be limited to such details. Furthermore, while, 
generally, specific claimed details of the invention constitute important 
specific aspects of the invention in appropriate instances even the 
specific claims involved should be construed in light of the doctrine of 
equivalents.