JPH0519136B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a camera having an automatic distance detection function that automatically detects a subject distance and automatically adjusts focus or displays the focus state based on the distance information. It is about improvement.

When taking normal photographs, for example, the first thing to do is to photograph a person.
There is a main subject that you want to focus on, and a sub-subject such as the background, but if you shoot a composition like this with a conventional autofocus camera, only the main subject will be in focus, and the sub-subject will be in focus. In many cases, it is not. However, when a subject, such as a commemorative photograph, has a certain degree of weight in the background, the photographer wants to take the photograph in a state where both the main subject, the person, and the sub-subject, the background, are in focus. However, conventional autofocus cameras have not been able to satisfy this desire.

An object of the present invention is to provide a camera that can bring objects in focus, including those at close range, within other focus ranges and shorten the AF processing time.

In order to achieve this object, the present invention provides a light projecting means for projecting a luminous flux to each of a plurality of distance measurement fields in a screen, and a light projecting means provided corresponding to each distance measurement field,
a light-receiving circuit that receives the reflected light of the luminous flux from the object in the corresponding field of view, and outputs a signal that changes over time in accordance with the object distance in each field of view and shows a peak after a time corresponding to the object distance, and each light-receiving circuit; Judgment means are provided corresponding to the corresponding light receiving circuits and detect changes over time in the output signals of the corresponding light receiving circuits, and each judgment means determines whether or not the output signals have reached a peak. A signal forming circuit that forms a digital value for each corresponding light receiving circuit according to the time interval until it is determined that the output signal has reached its peak, and a digital value that corresponds to the closest subject distance from each digital value is selected. a selection circuit that calculates the selected digital value and a digital value corresponding to the depth of field to obtain a calculated value corresponding to a subject distance that is further away by the depth than the closest subject distance; and a drive circuit that drives the photographing lens.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

1 to 6 show one embodiment of the present invention, and FIGS. 1 to 3 are perspective views showing the structure of an automatic focus control mechanism. Reference numeral 1 denotes a lens barrel that houses a photographic lens (not shown) and is provided so as to be movable between a close end and an infinity end. It is provided with a portion 1a, and a convex portion 1
It moves back and forth while being guided by the insert bar 2 which is fitted into a and a structural member (not shown). Reference numeral 3 denotes a focusing screw screwed into the convex portion 1a of the lens barrel 1. Its tip 3a is in contact with a feeding cam portion of a distance adjustment ring, which will be described later, and by rotating the focusing screw 3, the photographic lens can be adjusted. The range of motion can be adjusted. 4 is the tip 3 of the focusing screw 3
A is a spring that urges the lens barrel 1 in the direction of the arrow so that a and a feeding cam portion of a distance adjustment ring (described later) are always in contact with each other; 5 is an inner diameter portion 5a, a feeding cam portion 5b, a charge locking portion 5c, and a locking Parts 5d, 5e, 5f,
5g and 5h (only 5 are shown in this example, but in reality there are 15 as shown in Fig. 9), and the inner diameter part 5a is fitted with a structural member (not shown). , is rotatably held by its structural members. The lens barrel 1 is attached to the feeding cam portion 5b.
The tip 3a of a focusing screw 3 screwed into the convex portion 1a is in contact with the convex portion 1a, and the lens barrel 1 is retracted or extended as the distance adjustment ring 5 rotates. The charge locking portion 5c is a locking portion 5d to 5 that holds the distance adjustment ring 5 at the charge position by being locked to a claw portion of a stop claw described later.
h are provided at positions corresponding to the amount of retraction of the lens barrel 1, and the lens barrel 1 is retracted when the pawl of a stop pawl, which will be described later, jumps into one of the locking portions 5d to 5h. Stop operation.

6 is a spring that biases the distance adjustment ring 5 in the counterclockwise direction (in the direction of the arrow); 7 is a lens movement monitor signal contact piece that slides on the pulse plate 8 as the distance adjustment ring 5 rotates; The stop pawl is rotatably held by a structural member (not shown) fitted into the hole 9a, and biased clockwise (in the direction of the arrow) by a spring (not shown). Further, the stop pawl 9 is provided with a pawl portion 9b and a convex portion 9c for holding the armature 10. Reference numeral 11 denotes a distance adjustment starting magnet, and when excited, the yoke 11a attracts the armature 10. As a result, the stop pawl 9 rotates counterclockwise against the biasing force of the spring, the engagement between the charge locking portion 5c of the distance adjustment ring 5 and the pawl portion 9b of the stop pawl 9 is released, and distance adjustment begins. As the magnet 11 is demagnetized, the claw portions 9b again jump into the locking portions 5d to 5h. 1
2 has two long grooves 12a, a convex portion 12b, and a gear portion 12.
c, a light emitting element lever equipped with a cam part 12d and a locking part 12e, in which the long groove 12a is fitted with the structural member 13 and the adjusting member 14, and is slidably held with respect to the structural member 13 and the adjusting member 14; has been done. The adjustment member 14 is for adjusting the position of a light emitting element and a light receiving element, which will be described later.It is rotatably attached by a structural member (not shown), and by rotating the adjustment member 14, the projection can be adjusted. The position of the optical element lever 12 is finely adjusted.

Reference numeral 15 denotes a light emitting element lever position signal contact piece, which is fixed to the convex portion 12b of the light emitting element lever 12, and when the light emitting element lever 12 slides (travels), the comb-shaped electrode of the pulse plate 16 and the straight line are connected. slide over the shaped electrode. 17 is a spring that urges the light projecting element lever 12 in the direction of the arrow; 18 and 19 are governor gears;
The shafts 18a and 19a are rotatably held by structural members (not shown), and the gear part 12c of the light projecting element lever 12 and the gear part 18c of the governor gear 18 are engaged with each other, and a known governor is formed by a pallet (not shown). The rotation is transmitted to the mechanism, and the sliding movement of the light projecting element lever 12 is made constant. 20 is the hole 20
a, a locking claw having a claw portion 20b and a convex portion 20c;
It is rotatably held by a structural member (not shown) fitted into the hole 20a, and biased counterclockwise by a spring 21. An armature 22 is fixed to the convex portion 20c, and the yoke 23a attracts the armature 22 by excitation of the distance measurement starting magnet 23. As a result, the locking claw 20 rotates clockwise against the bias of the spring 21, and the engagement between the locking portion 12e of the light projecting element lever 12 and the claw portion 20b of the locking claw 20 is released. Reference numerals 24 and 25 indicate distance measurement completion signal contacts, which are turned on at the position where the light emitting element lever 12 has completed sliding, and are output to a distance measurement completion detection section to be described later.

Reference numeral 26 designates a light emitting element holder, in which a shaft portion 26a is rotatably held by a structural member 27, and is attached clockwise by a spring 28 so that the protrusion 26b and the cam portion 12d of the light emitting element lever 12 are always in contact with each other. Forced. A compression spring 26c serves to bias the shaft portion 26a of the light emitting element holder 26 in the direction of the arrow, thereby preventing the light emitting element holder 26 from wobbling. Reference numeral 29 denotes a light projecting section, which is integrally constructed with the light projecting element holder 26, and is provided with a light projecting element section 30 made up of nine light projecting elements inside. 31 is a connector part, 32 is a light projecting lens provided on the front side in the optical axis direction of the light projecting part 29, 33 is a light receiving lens, and 34 is a light receiving element board, which includes a light receiving element part 35 consisting of nine light receiving elements; Peak detection unit 36 (details will be described later)
is held. 37 is a connector section, 38 is a start position confirmation circuit, a light emitting element control circuit, which will be described later;
This is a board that holds an aperture value determination circuit, a pulse counter section, a closest distance determination circuit, a lens position calculation circuit, a lens extension control circuit, and the like.

FIG. 4 shows a light emitting element section 30 and a light receiving element section 35.
FIG. I ₁ to _{I 9} are light projecting elements arranged in three columns vertically and three columns horizontally. S ₁ to _{S 9} are light receiving elements, which are arranged at positions corresponding to the light projecting elements I ₁ to I ₉ , respectively.

FIGS. 5a and 5b are diagrams showing the viewfinder field of view. 39 is a viewfinder field of view, P ₁ to _{P 9} are distance measurement points set at predetermined positions within the shooting screen, and the light emitting element I ₁ is used for the subject at each distance measurement point P ₁ to _{P 9} .
_-I9 respectively, and the reflected light is received by the light-receiving elements _S1 - _S9 , respectively. The number of distance measurement points is not limited to nine, and N distance measurement points P ₁ to _{P o} may be set as shown in FIG. 5b. In that case, the number of light projecting elements and light receiving elements is also set to N.

FIG. 6 is a block diagram showing the electric circuit of the automatic focus control mechanism. A release button 101 outputs a high-level signal when the photographer presses the release button 101 (release operation). 1
Reference numeral 02 denotes a start position confirmation circuit for checking whether or not the distance measurement can be started, and outputs a high level signal to the AND gate 103 if the distance measurement can be started. Reference numeral 104 denotes a release mechanism equipped with a known release operation holding mechanism, etc., which starts its operation when a high level signal is input from the AND gate 103. Reference numeral 105 denotes a light emitting element control circuit, in which the light emitting elements _I1 to _{I9 of the light emitting element section 30 sequentially emit light in synchronization with the pulses output from the light emitting element control circuit 105, and the light emitting elements I9} sequentially emit light. Elements S ₁ to _{S 9}
receives light. This light emitting operation is performed by the light emitting element lever 12.
However, since one round of the light emitting operation of the light emitting elements I ₁ to _{I 9} is performed at a much higher speed than the sliding movement of the light emitting element lever 12, the light emitting elements I ₁ to I The position of the light emitting element lever 12 when the light emitting element ₉ makes one round is almost the same. Photodetector S ₁
~ _S9 , the amount of received light is exchanged into a current value and output to the peak detection section 36. The peak detection section 36 is composed of nine peak detectors _K1 to _K9 ,
The peak detectors K ₁ to _{K 9} have light emitting elements I ₁ to _{I 9} respectively.
_The current values output from the light receiving elements S _{1 to} S ₉ corresponding to
The signals are input sequentially in synchronization with the signals output to the Each of the peak detectors K ₁ to K ₉ detects the peak value of the amount of light received by the corresponding light receiving elements S ₁ to _{S 9} due to repeated light emission from the light emitting elements I ₁ to I ₉ . The structure is such that a high-level signal is output until a peak value is detected, and the output is inverted to a low-level signal at the same time as the peak value is detected. Reference numeral 106 indicates that the light emitting element lever position signal contact piece 15 slides on the pulse plate 16 as the light emitting element lever 12 slides, thereby generating pulses as signals pointing to distance addresses No. 1 to 15 (details will be described later). The output pulse generator 107 is an AND gate section composed of nine AND gates A ₁ to _{A 9} , and each of the AND gates A ₁ to A ₉ is connected to a peak detector K ₁ to _{K 9} of the peak detection section 36 . The gate is opened until the output of is inverted to low level. 1
08 is a pulse counter section composed of nine pulse counters _M1 to _M9 , each of which receives the output from _the AND gate section ₁₀₇ ,
In other words, each of the peak detectors _K1 to _K9 has the role of counting the number of pulses from the pulse generator 106 until each peak value is detected (until it is reversed from high level to low level), and simultaneously storing the number. I have it.

Reference numeral 109 denotes a distance measurement completion detection unit that detects that the distance measurement operation has been completed when the light emitting element lever 12 has completed sliding and the distance measurement completion signal contacts 24 and 25 have been turned on. In this way, a ranging completion signal is output. 110 is the distance measurement completion detection unit 10
This is the closest determination circuit that operates when the distance measurement completion signal is input from 9, and determines and outputs the smallest distance address among distance addresses No. 1 to 15 stored in pulse counters M ₁ to _{M 9} . . Reference numeral 111 denotes an exposure light receiving element, which starts blur metering when the release mechanism 104 is started, converts the amount of light from the subject into an electrical signal, and outputs the electrical signal. 112 is an aperture value determining circuit which converts the signal input from the exposure light receiving element 111 into an aperture value F.
and outputs it to the A/D conversion circuit 113.
The A/D conversion circuit 113 converts the aperture value F into digital signal aperture value information (details will be described later) and outputs the digital signal. 114 is the distance address number output from the closest determination circuit 110 and the A/D conversion circuit 1
A lens position calculation circuit adds the digitalized aperture value information from 13 and outputs the result. 115 is a pulse generator, and as the distance adjustment ring 5 rotates, a lens movement amount monitoring signal contact piece is generated on the pulse plate 8 as the distance adjustment ring 5 rotates. 7 slides, a number of pulses corresponding to the lens movement amount are output as a lens movement amount monitor signal.

Reference numeral 116 denotes a lens extension control circuit, which receives pulse signals from the pulse generator 115 and the lens position calculation circuit 1.
At the same time, the distance adjustment start magnet 11 starts to be energized, and when the number of pulse signals from the pulse generator 115 matches the output signal from the lens position calculation circuit 114, The power supply to the magnet 11 for starting distance adjustment is turned off. 117 is an inverter that outputs a low level signal when a high level signal is input from the release button 101, and outputs a high level signal when a low level signal is input; 118;
is a memory cancel circuit which is activated by a high-level signal input from the inverter 117, and after a certain time delay outputs a high-level signal to the reset terminals of the pulse counters _M1 to _M9 to reset the pulse counters M1 to _M9 . It serves to reset ₉ . 11
9 is a comparator that compares the lens position designation signal from the lens position calculation circuit 114 with the number of pulse signals from the pulse generator 115; 120 is a comparator 119;
This is a display circuit that displays front defocus, in-focus, or rear defocus based on a signal input from the camera.

Next, its operation will be explained. When the photographer composes the subject as shown in FIG. 5 and presses the release button 101, the power switch is turned on and a high level signal is output to the start position confirmation circuit 102, AND gate 103, and inverter 117. be done. The start position confirmation circuit 102 checks whether the light emitting element lever 12 is at the charge position shown in FIG. A high level signal is output to the AND gate 103. With ANDGATE 103, release button 1
Since a high level signal is input from 01 and the start position confirmation circuit 102, a high level signal is output, and the operation of the release mechanism 104 is started.
Further, the high level signal input to the inverter 117 is inverted to low level, and the memory cancel circuit 118 inverts the high level signal outputted to the reset terminal of each pulse counter _M1 to _M9 to low level. The count preparation operations of pulse counters _M1 to _M9 are completed.

By operating the release mechanism 104, the magnet 23 for starting distance measurement and the light receiving element 111 for exposure are activated.
and the light projecting element control circuit 105 each start operating. The distance measurement starting magnet 23 is excited,
The locking claw 20 rotates clockwise against the biasing force of the spring 21, and the locking between the claw portion 20b and the locking portion 12e of the light emitting element lever 12 is released, and the light emitting element lever 12 is released.
begins to slide at a constant speed from the position shown in FIG. 1 to the position shown in FIG. 2 by the force of the spring 17. As a result, the light projector 29 starts scanning in the distance direction from close range to infinity. On the other hand, in the light emitting element control circuit 105, the light emitting elements _I1 to _I9 are synchronously blinked and the light receiving elements S1 to _{S1 are} controlled by the peak detectors _K1 to K9.
Start synchronization detection in _S9 (state shown in FIG. 2).
As a result, the ranging points P ₁ to P are scanned. The scanning speed of the ranging points P ₁ to _{P 9} , that is, the flashing transition speed of the light projecting elements I ₁ to I ₉ is determined to be faster than the scanning speed in the distance direction due to the angle change of the light projecting unit 29. . In this embodiment, in order to simplify the explanation, the light emitting elements I ₁ to I ₉ are used as shown in FIG.
and a combination of nine light-receiving elements S ₁ to S ₉ , and a finer field of view 39 detected by the light-receiving elements S ₁ to _{S 9}
As shown in Figure 5a, there are nine distance measuring points _P1 to _P9 , but the number may be fewer than this, or N distance measuring points as shown in Figure 5b.
It may be P ₁ to P _o . Further, the arrangement may be, for example, concentric circles. Furthermore, the light emitting order of the light emitting elements I ₁ to _{I 9} is arranged so that adjacent elements on the subject plane are less likely to interfere with each other, so that the order of the light emitting elements I ₁ to I 9 is not from the light emitting element I 1 to the light emitting element I ₉ , but that adjacent elements are Although it is preferable to use an order in which no light is emitted, in this embodiment, for convenience, the synchronous flashing is performed sequentially starting with the light projecting element I ₁ , and when the light projecting element I ₉ is reached, the next flashing is the light projecting element I ₁ , and so on. I do.

During the sliding process of the light projecting element lever 12, the light projecting elements _I1 to _I9 emit the light emitting signal 121 as shown in FIG. Sequentially irradiate distance measurement points P ₁ to P ₉ , and light-receiving element S ₁
~ _S9 converts the received light amount into a current value of 122 and outputs it to the peak detectors _K1 ~ _K9 . peak detector K ₁
~ _K9 is a light reception signal 123 (indicated by diagonal lines in FIG. 7) that represents the current value while the paired light emitting element is emitting light among the current values 122 output from the light receiving elements _S1 to _S9 . As shown in FIG. 8, a high level signal is output to the AND gate section 107 until the peak value is detected, and at the same time as the peak value is detected, the output is inverted to a low level signal.
On the other hand, the pulse generator 106
With the slide of step 2, a pulse pointing to the distance address number is output. That is, the first pulse is the distance address
No. 1, the second pulse sends distance address No. 2,
The 15th pulse points to distance address No. 15, respectively. Distance addresses No. 11 to No. 15 are respectively assigned to predetermined distances from 0.8 m to infinity ∞, as shown in FIG. The AND gates A ₁ -A ₉ allow the pulses from the pulse generator 106 to be input to the pulse counters M ₁ -M ₉ while the outputs of the respective peak detectors K ₁ -K ₉ are at a high level. This allows pulse counter M ₁
~ _M9 counts the pulses until the light reception signal 123 reaches its peak, and stores the counted value. This count value corresponds to the distance address number representing the subject distance at each distance measurement point _P1 to _P9 . For example, in the example in Figure 9, the distance measurement point
The count value of pulse counters M ₁ to M ₃ corresponding to P ₁ to _{P 3} is 10, the count value of pulse counter M ₄ corresponding to ranging point P ₄ is 4, ..., the pulse corresponding to ranging point P ₉ The count value of counter _M9 becomes 9.

Next, when the sliding of the light emitting element lever 12 is completed (distance measurement operation is completed), the distance measurement completion signal contact piece 24 and the distance measurement completion signal contact piece 25 are turned on at the same time by pressing the light emitting element lever 12. The distance measurement completion detection unit 109 detects that the distance measurement operation is completed, and outputs a distance measurement completion signal to the closest distance determination circuit 110. When the distance measurement completion signal is input, the closest determination circuit 110 determines the minimum value among the count values stored in the pulse counters _M1 to _M9 . For example, according to the example of FIG. counter _M4 ,
Select count value 4 of M ₆ and use lens position calculation circuit 11
Output to 4.

On the other hand, the exposure light receiving element 111 is connected to the release mechanism 1.
04 starts photometry, converts the brightness of the subject into a current value, and aperture value determination circuit 112.
Output to. The aperture value determination circuit 112 determines the current value,
For example, the aperture value is converted to F2.8, F4, etc., and outputted to the A/D conversion circuit 113. A/D conversion circuit 113
For example, the aperture value is F2.8 from the aperture value determination circuit 112.
If the aperture value is input, the aperture value information is 1, if the aperture value F4 is input, the aperture value information is 2, ..., if the aperture value F32 is input, the aperture value information is 8, etc., and so on. Arithmetic circuit 114
Output to. Note that here, the viewfinder field of view 39
Considering that all distance measurement points P ₁ to _{P 9} are to be in focus, it is desirable that the aperture value determined by blur metering be as small as possible. Therefore, the shutter used in the camera of this embodiment is preferably one that can set the shutter speed so that the aperture is as small as possible within a range that does not cause blurring due to shooting, etc., for a given EV value of the subject. The lens position calculation circuit 114 adds the distance address number from the closest determination circuit 110 and the aperture value information from the A/D conversion circuit 113, and uses this calculation value as a lens position designation signal to be sent to the lens extension control circuit 116 and Output to comparator 119. For example, as shown in Figure 9, if the nearest distance address number is 4, the aperture value information is 1 (F2.8).
If so, calculate 4+1=5 and the aperture value information is 3.
(F5.6), calculate 4+3=7, and if the aperture value information is 7 (F22), calculate 4+7=11. The calculated value specifies a lens position that focuses on a distance corresponding to the value. For example, a calculated value of 5 specifies a lens position that focuses on a distance of 1.6 m that corresponds to distance address No. 5. The lens feeding control circuit 116 receives the signal from the lens position calculation circuit 114 and simultaneously starts the distance adjustment start magnet 1.
1, the distance adjustment start magnet 11 is energized, and as a result, the stop claw 9 rotates counterclockwise against the biasing force of a spring (not shown), and the charge engagement of the distance adjustment ring 5 is activated. The lock between the stop portion 5c and the claw portion 9b of the stop claw 9 is released. Therefore, the distance adjustment ring 5 begins to rotate counterclockwise according to the biasing force of the spring 6. As the distance adjustment ring 5 rotates, the lens movement amount monitor signal contact piece 7 slides on the pulse plate 8, and the amount of movement is transmitted to the lens advance control circuit 1 in the form of a pulse number from the pulse generator 115.
16. At the same time, the lens movement amount is inputted from the pulse generator 115 to the comparator 119 in the form of the number of pulses, and the comparator 119 compares the calculated value from the lens position calculation circuit 114 with the number of pulses. , it is displayed that front defocus or rear defocus is present.

Further, the lens extension control circuit 116 compares the information from the lens position calculation circuit 114 and the information from the pulse generator 115, and when they match, the power supply to the distance adjustment start magnet 11 is turned off. That is, when the number of pulses from the pulse generator 115 reaches the same value as the information from the lens position calculation circuit 114 (for example, if 4+1=5, the number of pulses is counted 5), the distance adjustment start magnet is activated. The excitation of 11 is released. As a result of this operation, the stop pawl 9 rotates clockwise according to the biasing force of a spring (not shown), and jumps into the locking portion 5e of the distance adjustment ring 5, as shown in FIG. 3, for example.
The retracting operation of the lens barrel 1 is completed, and the photographic lens is stopped with the nearest object positioned between the focus distance and the near point of the depth of field. As a result, the display circuit 120 displays that the focus is achieved.

At the same time, a known exposure operation is activated, and when a series of photographic operations is completed, the film is wound up by a motor or manually, advancing one frame of film, and charging each member necessary for photographing to return to the state shown in Figure 1. Return.

Here, we will compare the method of this embodiment for determining the retracted position of the lens barrel 1 with the conventional example.
This will be explained with reference to the figures. In this embodiment, the aperture value information from the A/D conversion circuit 113 is set to the aperture value F2.8, which is the open aperture, as aperture value information 1, and the aperture value information increases to 2, 3, etc. every time the aperture is stopped down one stop. The minimum value among the counted values stored in the pulse counters M ₁ to _{M 9} is determined and outputted by the nearest distance determination circuit 110 and then outputted to the lens position calculation circuit 114 . The respective numerical values are added and output as a lens position setting signal. If the depth of field of the photographic lens is t, the diameter of the permissible circle of confusion is δ, and the aperture value is F, then t=2δu ^{2 2} F/ ⁴ −u ² δ
² Since there is a relationship of F ² , by using the fact that the depth of field t increases by narrowing down the aperture value F,
The idea is to increase the increased depth of field to a point further away than the closest subject (main subject).

In other words, as shown in FIG. 10a, in the conventional example, when the distance signal to the subject is output from the distance measuring section,
The retraction of the photographic lens was stopped in accordance with the output subject distance. That is, if a focus signal was output when the subject distance was 1.35 m, the retraction of the photographic lens would also have stopped at a position corresponding to 1.35 m. However, in this embodiment, if distance address No. 4 is output from the closest distance determination circuit 110 as shown in FIG. 5 plus information 1 (for aperture value F2.8), that is, distance address No. 5 (1.6m)
Specify the retraction position of the lens barrel 2 so that it matches the position.

To explain in more detail, if you shoot a composition with an aperture value of F5.6 and the closest subject is located at a distance of 1.35 m, according to conventional methods, the range that appears in focus on the film surface is at a distance of 0.6 m. ~4.8
It is m. Therefore, the background, which is the sub-subject, can only be in focus up to 4.8m, and the background located further away will be blurred, but in this example, the subject distance can be in focus from 0.78m to 17m. Become. Furthermore, it can be seen that the amount of blur of an image at infinity is considerably smaller than that of the conventional model.

Next, the operations described so far will be briefly explained using the flowchart shown in FIG. First, the photographer decides on the composition of the subject and presses the first stroke of the release button 101 (step 201).
Power is supplied to each circuit, and the camera becomes ready for shooting (step 202). When the camera is pushed in to the second stroke position (step 203), the magnet 23 for starting distance measurement is turned on by known means (step 202).
204). When the ranging start magnet 23 is turned on, the light emitting element lever 12 starts sliding (step 205), and at the same time, a synchronous blinking command for the light emitting element section 30 is issued, and the light emitting elements I ₁ to I ₉ starts synchronous blinking (step 206), and the light receiving element of the light receiving element section 35
The light is received by S ₁ to _{S 9} (step 207). next,
Of the current values output from the light-receiving elements _S1 - _S9 , only the portion that is synchronized with the light emission of the light-emitting elements _I1 - _I9 is converted into a synchronizing signal as a light-receiving signal (step 208). The peak value of the light reception signal, which is an analog value, is detected by a known means (step 209), and at the same time, the light emitting element lever 12 is slid to output the position signal in the form of pulses (step 209). 210),
It is determined at what distance the peak value described above was obtained.

On the other hand, by operating an exposure control mechanism (not shown), blur metering is started (step 211), light is received by the exposure light receiving element 111, and an aperture value is determined (step 212). The aperture value is A/D converted (step 213), and added to the number of pulses until the aforementioned peak value is detected as shown in FIG. 9 (step 214), resulting in a final lens position designation signal (step 215). ) is stored in the lens extension control circuit 116.

When the object distance measurement operation is completed using the light emitting element lever 12, the distance measurement completion signal contacts 24 and 25 are turned on (step 216), the distance measurement start magnet 23 is turned off (step 217), and distance adjustment is started. The starting magnet 11 is turned on (step 218). When the distance adjustment starting magnet 11 is excited, the lens barrel 1 begins to retract (step 219), and in conjunction with the retracting operation, a lens movement monitor signal is output (step 220). Lens feeding control circuit 11
A lens position designation signal is stored in 6, which is compared with the lens movement amount monitor signal described above (step 221), and when they match, the distance adjustment start magnet 11 is turned off (step 222). When the distance adjustment start magnet 11 is demagnetized, the rotation of the distance adjustment ring 5 is stopped by the stop claw 9, and the retracting operation of the lens barrel 1 is stopped (step 223). At the same time, the distance adjustment start magnet 11 is turned off to start an exposure operation by a known means (step 224), and the series of photographing operations ends.

According to this embodiment, by measuring the distance from the distance measuring points P ₁ to _{P 9} , it is possible to perform focusing that takes into account not only the main subject but also the secondary subject in a single distance measuring operation. Further, by eliminating the distance measurement marks and the like that were conventionally provided in the viewfinder field of view 39, the troublesomeness of the viewfinder field of view and the time required for the photographer to make decisions are eliminated, resulting in a camera that is resistant to shutter startup.

Furthermore, a plurality of light emitting elements I ₁ to I ₉ and light receiving elements S ₁
~ Compared to measuring the same range using a large projected image of a single element, placing _S9 not only improves the resolution of distance measurement, but also enables distance measurement of even small objects, resulting in highly accurate photographs. Photography is now possible.

In this embodiment, information from the center of the viewfinder's field of view and from the periphery was processed with the same weight, but it is also possible to give weight to this information, in other words, to perform something similar to center-weighted photometry in photometry. .

The present invention is also applicable to a camera in which only distance measurement is performed automatically, and distance adjustment is performed manually while viewing the focus state display. In this case, a predetermined range between the focal length of the photographic lens and the near point of the depth of field is displayed as the in-focus area. It can also be applied to cameras that take pictures with the subject placed within the distance measurement mark at the center of the screen. Furthermore, the present invention is not limited to a camera that performs distance measurement in a single distance measurement operation, but can also be applied to a camera with a prefocus mechanism that performs distance measurement operations once for a plurality of subjects.

As explained above, according to the present invention, multi-point
During AF, the lens moves from the position where it focuses on the subject at the closest point to the position where it focuses on subjects further away by the amount of depth, so it is possible to focus on other subjects within the focusing range, including the closest point. It can be brought into focus. Also, multi-point
Since AF processing is performed in parallel, AF processing time can be reduced.

[Brief explanation of the drawing]

1 to 3 are perspective views showing the structure of an automatic focus control mechanism of a camera according to an embodiment of the present invention, FIG. 4 is a layout diagram of a light emitting element and a light receiving element, and FIGS. 6 is a block diagram showing the electric circuit, FIG. 7 is a diagram showing the operation of the light emitting element and light receiving element, FIG. 8 is a diagram showing the light reception signal, and FIG. 9 is a diagram showing the distance measurement points. 10A is a diagram showing the calculation method, FIG. 10A is a diagram showing the depth of field in a conventional camera, FIG. The figure is a flowchart showing the same operation. 1... Lens barrel, 3... Focusing screw, 5...
Distance adjustment ring, 7... Lens movement amount monitor signal contact piece, 8... Pulse plate, 9... Stop claw, 11
...Magnet for starting distance adjustment, 12... Light emitting element lever, 15... Light emitting element lever position signal contact piece, 20... Locking claw, 23... Magnet for starting distance measurement, 24, 25... Measurement Distance completion signal contact, 30...
... Light emitting element section, 35 ... Light receiving element section, 36 ... Peak detection section, 101 ... Release button, 104
...Release mechanism, 105...Light emitter control circuit, 106...Pulse generator, 108...Pulse counter section, 109...Distance measurement completion detection section, 110
...Closest distance determination circuit, 112...Aperture value determination circuit, 113...A/D conversion circuit, 114...Lens position calculation circuit, 115...Pulse generator, 11
6...Lens extension control circuit, _I1 to _I9 ...Light emitter element, _S1 to _S9 ...Light receiving element, _K1 to _K9 ...Peak detector, _A1 to _A9 ...And gate, _M1 to _M9 ...
Pulse counter, _P1 to _P9 , P _o ... Distance measurement point.

Claims (1)

[Claims] 1. A light projecting means for projecting a luminous flux to each of a plurality of distance measurement fields of view within a screen, and a light projecting means provided corresponding to each distance measurement field of view, each receiving light reflected by the luminous flux from a subject in the corresponding field of view, A light receiving circuit that outputs a signal that changes over time in accordance with the subject distance in each field of view and peaks after a time corresponding to the subject distance; Determination means for detecting changes over time and determining whether the output signal has reached its peak, and the time interval until each determination means determines that the output signal of the corresponding light receiving circuit has reached its peak. a signal forming circuit that forms a digital value for each corresponding light-receiving circuit; a selection circuit that selects a digital value corresponding to the closest subject distance from among each digital value; The camera is characterized by comprising a calculation circuit that calculates a digital value to obtain a calculation value corresponding to a subject distance that is further away by depth than the closest object distance, and a drive circuit that drives a photographing lens based on the calculation value. camera.