JPH0760244B2 - Mirror and light shield position detection mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to position detection for detecting the operating positions of a mirror and a light shielding plate that are moved between a finder observation position and a photographing position in conjunction with a motor. It relates to the device.

[Conventional technology]

As is well known, a single-lens reflex camera is provided with a movable reflex mirror (hereinafter, simply referred to as a mirror) that reflects a photographing light beam toward a focusing screen during finder observation. The mirror is moved to a shooting position retracted from the shooting optical path by performing shutter release, and then the shutter is opened and closed to perform exposure.

By the way, in some large format single-lens reflex cameras using 120 film, a lens shutter is used as a shutter. With such a camera,
Since the shutter is open during finder observation, a light-shielding plate is placed between the mirror and the film surface to block the shooting optical path so that the film is not exposed by part of the shooting light flux. Has been done. Then, when shutter release is performed, first, after the shutter is closed, the mirror and the light shielding plate are sequentially moved to the photographing position and retracted from the photographing optical path, and then the shutter is opened and closed to perform exposure. . After the exposure is completed, the shading plate and the mirror are returned to the original finder observation position in this order, and the shutter is opened to restore the finder observation mode.

In such a type of camera, it has been proposed to use a motor to drive the mirror and the light shield. When the motor directly drives the mirror and the light shielding plate, the spring for driving the mirror and the light shielding plate becomes unnecessary as in the conventional device, and the mechanism for charging the spring can be omitted. A drive mechanism for a mirror and a light-shielding plate, which has a simple structure and has less shock during operation, can be obtained.

[Problems to be solved by the invention]

As described above, when the mirror and the light shield plate are driven by the motor, it is necessary to accurately control the stop of the motor in relation to the moving positions of the mirror and the light shield plate. Under these circumstances, for example, when detecting the position of the mirror, conventionally, the mirror itself is detected by a position sensor such as a photo sensor. Therefore, two position sensors are required to detect that the mirror has moved to the photographing position and the finder observation position. In such a method, in order to detect the position of the light shielding plate in accordance with the position detection of the mirror, it is necessary to additionally provide a position sensor for the light shielding plate, and each position sensor is a mirror. Further, it is necessary to accurately position the light shielding plate in correspondence with the stop position. Therefore, not only is the number of position sensors increased, but all of these position sensors must be positioned with high accuracy, which complicates assembly.

The present invention has been made in view of such a conventional technique,
When the signal for controlling the motor for driving the mirror and the light shielding plate is taken out from the position sensor for detecting the position of the mirror and the light shielding plate, the number of the position sensors can be saved. An object of the present invention is to provide a position detecting mechanism for a light shielding plate.

[Means for solving problems]

In order to achieve the above object, the present invention sequentially moves each of the mirror and the light shielding plate in association with a drive plate driven by a motor, and detects the position of the mirror and the light shielding plate by the drive. It is obtained from a signal plate consisting of a fan-shaped reflector having first and second edges which rotate integrally with the plate. That is, since the mirror and the light shielding plate are moved in response to the rotation of the drive plate, the rotation position of the drive plate corresponds to the passage position of the first and second edges of the signal plate. Incidentally, photoelectrically detecting each passage with the first and second photosensors,
The position of the mirror and the light shielding plate can be detected by the combination of the detection signals.

An embodiment of the present invention will be described below with reference to the drawings.

〔Example〕

In FIG. 6 showing the principle structure of a camera using the present invention, a lens unit 2 and a film back 3 are detachably attached to a camera body 1 so as to maintain a light tight state. The lens unit 2 has a built-in shutter 6 that is opened and closed via a shutter drive circuit 5 in addition to a focus-adjustable taking lens 4. When the lens unit 2 is attached to the camera body 1, electrical contacts (not shown) are also connected, and the operation of the shutter drive circuit 5 is controlled by a signal from the camera body 1 side. A film 7 is stored in the film back 3. Even when the film back 3 is mounted on the camera body 1, the film back 3 is electrically connected to the camera body 1, and the film winding motor 8 built in the film back 3 is connected to the camera body 1.
The film 7 is driven by a motor drive circuit by an electric signal output from the side to wind the film 7 frame by frame.

A mirror box 10 is fixed inside the camera body 1. A mirror 11 and a light shielding plate 12 are rotatably attached to the mirror box 10, and when the finder is observed, the mirror 11 has a photographing optical path 14 as shown.
The photographing optical path 14 is located inside and the photographing optical path 14 is directed to the focusing screen 15, so that the subject screen is imaged on the focusing screen 15. On the other hand, at the time of observing the viewfinder, the light shielding plate 12 is also at the position shown in the figure, and the aperture 16 formed on the back surface of the mirror box 10 is closed. Therefore, when observing the viewfinder, the mirror 11
There is no possibility that the film 7 is exposed by a part of the photographing light flux that wraps around.

In FIG. 1 showing a drive mechanism portion of the mirror 11 and the light shielding plate 12, each of the frame 20 and the light shielding plate 12 to which the mirror 11 is fixed is provided with a shaft 21 provided on the mirror box 10.
Is rotatably attached to the shaft. A drive plate 24 is rotatably attached to one side surface of the mirror box 10 about a rotation shaft 23, and the drive plate 24 is rotatably attached to the inside of the mirror box 10. It is driven by a motor 28 via 25, 26 and 27. A mirror drive pin 32 and a light-shielding plate drive pin 33 are respectively provided on the arms 30 and 31 integrally attached to the drive plate 24 so as to protrude in opposite directions. Further, the drive plate 24 has a fan-shaped signal plate 35 made of a metal plate having a high reflectance, such as aluminum.
Is stuck.

Shafts 36 and 37 are planted on the side surface of the mirror box 10,
A mirror up lever 40 and a cam lever 41 are rotatably attached to one of the shafts 36. As shown in FIG. 4, these levers 40 and 41 are connected by a clamping force by a spring 43 via a rising 40a formed on the mirror up lever 40 and an adjusting plate 42. The adjusting plate 42 is attached to the cam lever 41 by a shaft 44, and is fixed at an arbitrary adjusting position by tightening a screw 46 through the long hole 45. By adjusting the position of the adjusting plate 42, the angle between the mirror up lever 40 and the cam lever 41 can be precisely adjusted.

The cam lever 41 is provided with a cam groove 48 including a circular arc portion 48a centering on the rotary shaft 23 of the drive plate 24 and a curved portion 48b continuous with the circular arc portion 48a. This cam groove 48 has an arm
The mirror drive pin 32 implanted in 30 is engaged. Further, a pin 50 implanted in the frame 20 is engaged with a long hole 49 formed at the tip of the mirror up lever 40.

The other shaft 37 implanted in the mirror box 10 has a spring 51
An interlocking lever 52 biased in a counterclockwise direction is rotatably attached by a shaft. The interlocking lever 52 is formed with a slot 53 whose one end is open, and a pin 54
The arm 55 in which is planted is integrated. This pin 54
Engages with a long hole 58 formed at one end of the light shielding plate up lever 57. The shading plate up lever 57 is pivotally attached to a shaft 59, and an edge 61 against which a pin 60 protruding from the shading plate 12 abuts is formed on the other end side, and a pin 62 is planted. Then, a spring 63 is hooked between the pin 60 and the light-shielding plate up lever 57 so as to go around the pin 62.

A lock lever 66 is pivotally attached to a shaft 65 protruding from the camera body 1, and is biased counterclockwise by a spring 67. One end 66a of the lock lever 66 faces the rotation locus of the pin 50 implanted in the frame 20, and the other end 66b locks the pin 60 in the illustrated state, so that the light shielding plate 12 is rotated clockwise. It is prohibited to turn to. And the mirror
When 11 is rotated to the position of the chain double-dashed line in FIG. 7, the lock lever 66 is rotated clockwise by the pin 50, whereby the other end 66b of the lock lever 66 releases the lock of the pin 60. Like

On the side surface of the mirror box 10, two reflection type photo sensors 70 and 71 are provided on the same circumference with the axis 23 as the center. As is well known, these photosensors 70 and 71 are composed of a light projecting section and a light receiving section, and the light from the light projecting section is transmitted to the signal plate 35.
When the light receiving section detects the reflected light, a high level signal (hereinafter referred to as H signal) is output. Therefore, the photosensors 70 and 71 change the state of the output signal at the moment when the edges 35a and 35b of the signal plate 35 that rotates together with the drive plate 24 pass. In addition, as the mounting position of the photosensors 70, 71, the edges 35a, 35b
It is not always necessary to use the same circumference as described above as long as the passage can be detected.

Further, a V-shaped stop lever 74 is attached to a shaft 73 protruding from the side surface of the mirror box 10. This stop lever 74 is stopped by a spring 75.
It is biased to crimp against 76. Recesses 74a and 74b for receiving the light-shielding plate drive pin 33 are formed at both ends of the stop lever 74, and guide surfaces 77 and 78 are provided at the front edges of these recesses. Then, when the drive plate 24 is at the initial position, the light shield plate drive pin 33 is fitted and positioned in the recess 74a, and at the turning end of the drive plate 24, the light shield plate drive pin 33 is fitted in the recess 74b and machined. Drive plate 24
Movement is stopped.

In addition to the stop position regulation of the drive plate 24 described above, the mirror 11 is positioned at the finder observation position by the stopper pin 80 that abuts on the frame 20. The stopper pin 80 is planted at one end of a V-shaped lever 82 biased counterclockwise by a spring 81. The other end of the lever 82 is in contact with the tip of an adjusting screw 83 screwed into the mirror box 10.
By adjusting the movement of the adjusting screw 83, the position of the stopper pin 80 can be changed, so that the angle of the mirror 11 can be adjusted in the finder observation state.
That is, the angle adjustment of the mirror 11 at the finder observation position is precisely adjusted by the adjusting screw 83 during assembly, separately from the interlocking system from the motor 28 to the cam lever 41.
The projected screen is set so as to be correctly guided to the focusing screen 15. In addition, by adjusting the fixed position of the adjusting plate 42 after setting the initial position of the mirror 11 in this way, the gap between the cam lever 41 and the mirror up lever 40 is eliminated, and the swing of the cam lever 41 is immediately mirrored. The transmission can be made to the up lever 40.

FIG. 2 shows an example of a circuit configuration for controlling the operation of the camera including the above-mentioned mechanism, and the operation will be described below with reference to FIGS. 3, 4, and 5.

When the release detection circuit 85 detects the pressing operation of the shutter button 18, the CPU 86 starts the process according to the sequence program stored in the ROM 87. The CPU 86 first outputs a drive signal to the shutter drive circuit 5 built in the lens unit 2, and the shutter 6 is closed. When closing of the shutter 6 is detected by the shutter position detection circuit 88 at time t ₁ in FIG. 3, the H signal is output to the normal signal output terminal 86a of the CPU 86. This H signal activates the relay 90, the contact piece 91 is switched from the ground terminal 92 to the terminal 93, and the transistor 94 becomes conductive.

Since the capacitor 95 starts to be charged by the conduction of the transistor 93, the voltage V _a of the line a gradually rises as shown in FIG. On the other hand, at the time of t ₁ , the photo sensor 70 is not facing the signal plate 35 as shown in FIG. 1, so that the signal state is L level. Therefore, the output terminal of the comparator 96 is also at the L level, and the transistor 97 becomes conductive. As a result, the voltage V _b appearing on the line b is proportional to the voltage set by the resistors 98 and 99 for voltage division, and the voltage level proportional to the voltage of V _b1 on which the voltage drop due to the current from the transistor 97 is superimposed. Has become.

Diodes 101 and 102 are reversely connected to the lines a and b, respectively, and these are connected to each other and then operational amplifiers are connected.
Connected to 104. As a result, the voltage corresponding to the lower one of the voltages V _a and V _b appears at the output terminal of the operational amplifier 104. As a result, the forward drive voltage V _c appearing at the point c gradually increases in proportion to the voltage V _a on the line a until the time t ₂ where V _a <V _b , as shown in FIG. After that, it becomes a constant level proportional to the voltage V _b1 of the line b.

When the motor 28 is normally driven by the normal rotation drive voltage V _c having such a waveform, the motor 28 slowly rises at the time of its startup, and accordingly, the drive plate 24 also rotates while being gradually accelerated. . When the drive plate 24 is rotated, the light shield plate drive pin 33, which is fitted in the recess 74a of the stop lever 74 and positioned at the initial position, causes the stop lever 74 to move to the spring 75.
Guide surface 77 while swinging counterclockwise against the urging force of
After getting over the vehicle and escaping, the drive plate 24 rotates in the counterclockwise direction from the initial position shown in FIG. When the signal plate 35 is at the initial position shown in FIG. 1, the photo sensor 71 outputs the H signal. However, the normal rotation of the drive plate 24 is started as described above, and the signal plate 35 rotates. At that moment, the photo sensor 71 also outputs an L level signal.

The drive plate 24 rotates in the forward direction, and it is integrated with this to drive the mirror
As the 32 rotates, the mirror drive pin 32 is moved to the initial position shown by the chain double-dashed line in FIG. 4, that is, the arc portion 48 of the cam groove 48.
From the midpoint between a and the curved portion 48b, the cam lever 41 is swung counterclockwise while moving in the cam groove 48 to the right. Since the left side of the curved portion 48b is connected to the arc portion 48b while being asymptotic to each other, in the initial stage of the rotation of the drive plate 24, the cam lever is rotated relative to the rotation of the mirror drive pin 32.
41 swings slowly. As a result, the rise at the time of starting the motor 28 is controlled mechanically as well as being moderated by the electrical control, and the electrical and mechanical power at the time of starting the drive plate 24 is increased. Most shocks will be resolved.

By swinging the cam lever 41 in this way, the mirror up lever 40 is pushed up via the rising 40a and the adjusting plate 42, and is also swung counterclockwise. Further, the frame 20 holding the mirror 11 rotates toward the raised position via the elongated hole 49 of the mirror up lever 40 and the pin 50. In the process in which the drive plate 24 is normally rotated in this manner, the mirror drive pin 32 reaches the right end of the cam groove 48 and then moves toward the left side. Then, when the mirror drive pin 32 has returned to the right end side of the arc portion 48a of the cam groove 48, each of the cam lever 41 and the mirror up lever 41 reaches the position shown in FIG.
11 is raised from the photographing optical path 14 to a photographing position which is completely retracted. Along with this, the lock lever 66 is rotated clockwise by the pin 50 to unlock the pin 60,
The light shielding plate 12 becomes rotatable.

At the moment t ₃ when the mirror 11 rises to the position shown in FIG. 4,
The edge 35a of the signal plate 35 is detected by the photo sensor 70, and the photo sensor 70 outputs an H signal as a timing signal for completion of mirror up. The output signals of the photosensors 70 and 71 are also input to the CPU 86, and when this timing signal is input to the CPU 86 at time t ₃ , the normal rotation signal output from the normal rotation signal output end 86 a of the CPU 86 is Δt. Time, eg 15ms
L level only during ec.

When the forward rotation signal is interrupted in this way, the relay 90
When turned off, the contact piece 91 is switched to the ground terminal 92. Then, the drive of the motor 28 is suddenly stopped, and the rotation of the drive plate 24 is also interrupted. On the other hand, when the H signal is output from the photo sensor 70,
The output terminal of the comparator 96 becomes H level, and the transistor 97 becomes non-conductive. Therefore, the voltage V _{b of} line _b
Drops to a value proportional to the voltage V _b2 (<V _b1 ) set by resistors 98,99.

At the time point of t ₄ after the time of Δt has passed, the CPU86
The normal rotation signal comes to appear again at the normal rotation signal output terminal 86a. As a result, the relay 90 is turned on and the contact piece 91 is connected to the terminal 92, so that the motor 28 causes the forward drive voltage appearing at the point c.
The forward rotation is performed again by V _c . As described above, the forward drive voltage V _c gradually increases in proportion to the voltage V _{a of the} line a, and after the time t ₅ when V _a ≧ V _b , the voltage V _{b2 of the} line b ₂ It becomes a constant level proportional to.

The normal rotation of the motor 28 is restarted by such a normal rotation drive voltage V _c , and when the drive plate 24 gradually rotates in the counterclockwise direction, the mirror drive pin 32 disengages from the bent portion 48b of the cam groove 48. , The cam lever 4 because it is moved along the arc portion 48a.
Each of 1 and the mirror up lever 40 remains in that position, and the mirror 11 is held in the up position.

On the other hand, when the rotation of the drive plate 24 is restarted, the light blocking plate drive pin 33 enters the slot 53 of the interlocking lever 52 and rotates it in the clockwise direction against the spring 51.
Therefore, the light-shielding plate up lever 57 rotates counterclockwise about the shaft 59 via the pin 54 and the elongated hole 58. When the shading plate up lever 57 is rotated counterclockwise in this way, the pin 60 is pushed by the edge 61 of the shading plate up lever 57 and the shading plate 12 is rotated around the rotation shaft 21. , The aperture 16 opened in the mirror box 10 is released.

Even when the light shielding plate 12 is rotated in this way,
Since the motor 28 is driven while gradually increasing its speed at the rising portion thereof, no shock is generated even at the instant when the light shielding plate drive pin 33 and the interlocking lever 52 are engaged with each other in the initial stage of the drive. Further, since the load for rotating the light shielding plate 12 is smaller than the load for rotating the mirror 11, the maximum voltage level of the forward drive voltage V _c after t ₄ is that of the mirror 11. Voltage level when rotating V _b1
It is set to a value proportional to the lower voltage level V _b2 . Therefore, the shock when the motor 28 is stopped can be suppressed to be lower than the time point t ₃ . That is, since the exposure is started immediately after the light blocking plate 12 is stopped, it is advantageous to reduce the shock when the light blocking plate 12 is stopped in this way as much as possible.

The motor 28 is driven by the forward drive voltage V _c that is proportional to V _b2 ,
When the rotation of the drive plate 24 is continuously connected, the shading plate 12 is moved to the photographing position completely retracted from the photographing optical path 14 and the aperture 16 is opened, as shown by the two-dot chain line in FIG. It becomes a state. At the same time, as shown in FIG. 5, the edge 35a of the signal plate 35 is detected by the photo sensor 71,
An H signal is output from the photo sensor 71 as a timing signal for completion of light-shielding plate up. This timing signal is CPU8
At time t ₆ when the signal is input to 6, the normal signal is not supplied from the normal signal output end 86a, the relay 90 is turned off and the contact piece 91
Is switched to the ground terminal 92 and the motor 28 stops.

When the drive plate 24 is stopped, the position of the drive plate 24 is regulated by the stop lever 74 at the end position of the rotation so that the drive plate 24 is not excessively rotated by the inertia of the motor 28 or the like. To be done. That is, when the light-shielding plate drive pin 33 rotates toward its terminal position,
The light-shielding plate drive pin 33 abuts on the guide surface 78, and while slidingly contacting the guide surface 78, the stop lever 74 is pushed counterclockwise and then recessed.
Fit in 74b. As a result, the light shielding plate drive pin 33 is braked, and the light shielding plate drive pin 33 is recessed by the recess 74b.
It can reduce the impact when stopped.

The H level signal from the photo sensor 71 is also used as a movement completion signal of the light shielding plate 12, and the CPU 86 outputs an operation signal to the shutter drive circuit 5. As a result, the shutter 6 opens and closes at a predetermined shutter speed to perform exposure. When the shutter 6 ends the opening / closing operation at time t ₇ , the shutter position detection circuit 88 outputs a shutter operation completion signal,
The reverse signal output terminal 86b of the CPU 86 goes high. As a result, the relay 112 is driven, and the contact piece 114 is switched from the ground terminal 115 to the terminal 116. Then, the motor 28 is _rotated in reverse by the reverse drive voltage V _d appearing at the point _d .
By the way, the reverse drive voltage V _d appearing at point _d is
The output voltage of 7 appears in proportion to the larger one of the voltage V _e appearing on the line e and the voltage V _f appearing on the line f, whichever is larger. The voltage V _e appearing on the line e is fixed to a constant voltage V _e0 determined by the resistors 118 and 119 for voltage division, while the voltage V _f appearing on the line _f is a capacitor 118.
The charge gradually decreases. That is,
When the transistor 120 is turned on by the reverse drive signal, the transistor 121 is cut off.
The voltage maintained at a constant level by 22 gradually decreases due to the charging of the capacitor 118. And
Since the operational amplifier 125 outputs a voltage proportional to the higher one of these voltages V _e and V _f , the reverse drive voltage V _{d at the} point _d gradually decreases as shown in FIG. Then, the voltage becomes a constant level after time t ₉ when V _e ≧ V _f .

When the motor 28 is driven by such a reverse rotation drive voltage V _d , the motor 28 continues to be driven while decelerating after being started. Then, when the drive plate 24 is rotated clockwise by this, the interlocking lever 52 is rotated counterclockwise around the shaft 37 via the light shield plate drive pin 33 and the slot 53. As a result, the shading plate up lever 57 also rotates counterclockwise about the shaft 59, so that the shading plate 12 descends from the position shown in FIG. 5 to the position shown in FIG. To close. When the shading plate 12 closes the aperture 16, as shown in FIG. 4, the pin 62 implanted in the shading plate up lever 57 presses the middle portion of the spring 63 so as to bend it. As a result, the light shield 12 is a spring.
The biasing force of 63 causes the aperture 16 to be elastically held in the closed position.

In addition, until the light shielding plate 12 is completely lowered in this way,
Since the mirror drive pin 32 moves in the area on the left side of the cam groove 48, that is, in the arc portion 48a, the cam lever 41 and the mirror up lever 40 are still held at the positions shown in FIG. And the shading plate 12 is completely apertured.
At the time t ₈ when the drive plate 24 is reversed to the position where the 16 is closed, the edge 35a of the signal plate 35 passes the photo sensor 70,
The H signal is output from the photo sensor 70. This signal can be used, for example, as a signal for confirming that the light shielding plate 12 has completely descended.

As the drive plate 24 continues to rotate in the reverse direction while being decelerated, the mirror drive pin 32 comes out of the arc portion 48a of the cam groove 48 and moves in the cam groove 48 to the right. The lever 40 and is rotated clockwise about the shaft 36. Then, the frame 20 rotates counterclockwise through the long hole 49 and the pin 50, and the frame 20
Comes into contact with the stopper pin 80 and is stopped, and the mirror 11 is returned to the finder observation position. In this way, at time t ₁₀ when the mirror 11 is returned to the finder observation position, the edge 35b of the signal plate 35 is detected by the photo sensor 71, and the photo sensor 71
Outputs an H signal as a timing signal for completion of mirror down.

When the timing signal is input to the CPU 86, the reverse rotation signal becomes L level at time t ₁₀ . This makes relay 11
Since 2 is turned off and the contact piece 114 is switched to the ground terminal 115, the motor 28 is stopped and the rotation of the drive plate 24 is stopped.
In this way, when the motor 28 and the drive plate 24 are stopped, the reverse drive voltage V _c supplied to the motor 28 gradually decreases to a low level voltage, so that the shock at the time of stopping them is greatly reduced. become.

Further, when the drive plate 24 is stopped at this position, the stop lever 74 acts to position the stop position of the drive plate 24. That is, when the shading plate drive pin 33 moves to the initial position shown in FIG.
Is in contact with the front edge of the guide surface 77 that is inclined with respect to the locus, and while swinging the stop lever 74 in the counterclockwise direction against the spring 75, gets over this and fits into the recess 74a. Regulated. At this time, the front edge of the guide surface 77 acts as a buffer surface for the light-shielding plate drive pin 33 and absorbs impact, so that vibrations that tend to occur when the drive plate 24 is stopped are suppressed.

When the timing signal obtained at time t ₁₀ is input to the CPU 86, the CPU 86 outputs an operation signal to the shutter drive circuit 5. Then, after the opening / closing operation for exposure, the shutter 6 in the closed state is brought to the open state again.
At this time, since the light shielding plate 12 has already closed the aperture 16, even if the shutter 6 is opened, the film back 3
The side is light tight. Furthermore, the lock lever is driven by the clockwise rotation of the mirror up lever 40.
66 rotates counterclockwise, and its one end 66b locks the light shielding plate 12 in the closed position via the pin 60.

When the mirror 11 and the light shielding plate 12 are restored to their initial positions in this way, the CPU 86 outputs an operation signal to the motor drive circuit 126 incorporated in the film back 3. As a result, the film feeding motor 8 is driven, and the exposed film 7 is transported via the well-known film winding mechanism 127. When the winding detection circuit 128 identifies that the transfer amount has reached just one frame, the motor 8 stops, one shooting sequence ends, and the viewfinder observation mode is restored.

Incidentally, have been described driving of the motor 28 in the in the usual imaging sequence, t ₁ ~t mirror-up processing of up to _6, and the mirror-down processing up t ₇ ~t _10, the row as a subroutine within the imaging sequence It can be executed by an interrupt command to the CPU86. That is, the mirror up and mirror down operations can also be performed by operating the separately provided mirror up button and mirror down button. For example, when the mirror is raised by an interrupt command, the processing is executed only when it is confirmed by the signal states of the photosensors 70, 71 that the mirror 11 is in the down position.

Instead of detecting the positions of the mirror 11 and the light shielding plate itself as in the above-described embodiment, the rotation position of the drive plate 24 commonly used for operating these is monitored, It becomes possible to reliably detect the three timing signals of the mirror up, the light shielding plate up, and the mirror down required for the drive control of 28 by only the two photosensors 70 and 71. Of course, the signal plate 35 is made of a light-shielding disc, and a reflection signal portion is provided in a part thereof so that it can be detected by the photosensors 70 and 71, or a slit is formed in the light-shielding disc. Such as through holes,
This may be detected by a transmissive photo sensor.

When implementing the present invention, as a position sensor for detecting the position of the signal plate 35, instead of the photosensor as described above, another sensor that can detect the approach of the signal plate 35, such as a proximity switch, or the like, If contact with the signal board 35 is allowed, a micro switch, a sliding contact, or the like can be used. Further, the mounting positions of these position sensors are independent of the mirror 11 and the light shielding plate 12,
Since it can be appropriately selected by changing the shape of the signal plate 35, particularly the shapes of the edges 35a and 35b, it is also advantageous in expanding the degree of freedom in design.

〔The invention's effect〕

As described above, according to the present invention, when the positions of the mirror and the light shielding plate are detected, the driving plate used as a common driving source for these mirrors is changed from the fan-shaped reflecting plate having the first and second edges. The signal plate is fixed, the passage of the first edge and the second edge thereof is monitored by the first and second photosensors, and the rotational position of the driving plate, that is, the mirror and the light shielding plate is determined by the combination of the photoelectric signals from these photosensors. The drive control signal of the motor corresponding to the position of is obtained.
Therefore, it is not necessary to individually detect the position of each of the mirror and the light shielding plate, and the number of position sensors that require highly accurate positioning can be reduced. Further, as for the photosensor and the mounting position, it is possible to avoid a place where it is difficult to take a space such as a movement path of a mirror or a light shielding plate, and to select an appropriate place which can be easily assembled according to the shape of the signal plate.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a mirror and a light shielding plate driving mechanism using the present invention. FIG. 2 is a circuit diagram showing an example of a control circuit used in the present invention. FIG. 3 is a time chart diagram for explaining the operation of the control circuit shown in FIG. 4 and 5 are explanatory views showing the operating state of the mechanism shown in FIG. FIG. 6 is a schematic diagram showing the principle structure of a camera using the present invention. 1 …… Camera body, 2 …… Lens unit 3 …… Film back 6 …… Shutter, 10 …… Mirror box 11 …… Mirror, 12 …… Shading plate 15 …… Focus plate, 16 …… Aperture 24 …… Drive Plate, 28 ... Motor 32 ... Mirror drive pin 33 ... Shading plate drive pin 35 ... Signal plate 40 ... Mirror up lever 41 ... Cam lever, 48 ... Cam groove 52 ... Interlocking lever 57 ... Shading plate Up lever 66 …… Lock lever 70,71 …… Photo sensor 74 …… Stop lever 86 …… CPU.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masayoshi Hirai, 1-324 Uetakecho, Omiya City, Saitama Prefecture, Fuji Photo Optical Co., Ltd. (72) Shiro Hashimoto, 1-324 Uetakecho, Omiya City, Saitama Prefecture Fuji Photo Inside the light machine Co., Ltd. (72) Inventor Michihiro Shiina 1-324, Uetakecho, Omiya City, Saitama Prefecture Fuji Photo Optical Co., Ltd. (72) Inventor Shigenori Goto 1-324, Uetakecho, Omiya City, Saitama Prefecture Fuji Photo Light Machine Co., Ltd. (72) Inventor Hisashi Hamada 2-26-30 Nishiazabu, Minato-ku, Tokyo Fuji Photo Film Co., Ltd. (56) Reference JP-A-57-186743 (JP, A) JP-A-60-29729 (JP, A) JP-A-60-208740 (JP, A)

Claims (1)

[Claims] 1. A mirror movable between a finder observation position and a photographing position, and a light shielding plate movable behind the mirror between a closed position for fully closing the aperture and an open position for fully opening the aperture. In the camera, the drive plate that is rotated in the normal and reverse directions by the motor, and the mirror is moved from the viewfinder observation position to the shooting position in conjunction with the normal rotation of the drive plate, and then the light shield plate is moved from the closed position to the open position. Then, the light blocking plate is moved from the open position to the closed position in conjunction with the reverse rotation of the motor, and then the interlocking mechanism for moving the mirror from the photographing position to the finder observation position and the drive plate fixed to the drive plate and rotated integrally with the drive plate. The signal plate, which is made up of a fan-shaped reflector that moves and has a first and a second edge, is provided so as to face the rotation range of the signal plate. A first photo sensor of the reflection type that outputs a first timing signal for photoelectrically detecting the passage of the first edge of the signal plate and temporarily stopping the driving of the motor when the first photo signal is moved to In order to stop the driving of the motor in the forward direction by photoelectrically detecting the passage of the second edge of the signal plate when the light-shielding plate moves to the open position by the normal rotation of the drive plate after it is obtained. A second photo sensor of a reflection type for outputting a second timing signal of the signal plate, the first plate of the signal plate when the drive plate is rotated in the reverse direction.
A position detecting mechanism for the mirror and the light shielding plate, wherein a third timing signal for stopping the reverse rotation of the motor is obtained by photoelectrically detecting the passage of the edge of the second photosensor.