JPH0623822B2 - Control circuit for motor for driving mirror and light shield - Google Patents

Description

The present invention relates to a motor control circuit for sequentially driving a mirror and a light shielding plate.

[Conventional technology]

As is well known, in a single-lens reflex camera, a movable reflex mirror (hereinafter, simply referred to as a mirror) that reflects a photographing light beam toward a focusing screen during finder observation.
Is provided. 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. In such a camera, since the shutter is opened during finder observation, the shooting optical path is blocked between the mirror and the film surface so that the film is not exposed by a part of the shooting light flux. The light-shielding plate is arranged in such a manner. 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. If the motor directly drives the mirror and the light shielding plate, the spring for driving the mirror and the light shielding plate and the mechanism for charging the spring, which are used in the conventional device, can be omitted. The structure can be simplified.

[Problems to be solved by the invention]

As described above, when the mirror and the light shielding plate are driven by the motor, the mirror and the light shielding plate are so arranged that a large load is not applied when the motor is started and that the load applied to the motor is dispersed in time. It is preferable to move and sequentially. However, when the load for moving the mirror and the load for moving the light shielding plate are sequentially applied to the motor, there is a drawback that the load applied to the motor tends to intermittently change at the start of each drive. . That is, when the light-shielding plate is driven after the driving of the mirror is completed, the load applied to the motor is released by the completion of the driving of the mirror, and the light-shielding plate is driven next while the rotation of the motor is increased, Shock and vibration are likely to occur at the time of switching. Moreover, even if it is attempted to drive the mirror or the light shield immediately after the motor starts, the torque is small at the start of the motor, so the actual driving of the mirror and the light shield is likely to be intermittent, which also causes vibration. Has become.

The present invention has been made to solve such a drawback, and when the mirror and the light shielding plate are sequentially driven by the motor, the drive of the motor is controlled so that vibration and shock do not occur when driving them. It is an object of the present invention to provide a control circuit for

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention supplies a drive voltage that is maintained at a constant level while gradually increasing to a motor that sequentially drives a mirror and a light-shielding plate, so that the mirror is first photographed from a finder observation position. Move to position. Then, when the mirror reaches the photographing position, the drive voltage is once cut off to stop the motor, and thereafter the drive voltage for moving the light shielding plate from the light shielding position to the open position is supplied to the motor. In this way, the drive voltage supplied again is controlled so as to be maintained at a constant level while gradually increasing, as in the case of moving the mirror, and this drive voltage is cut off when the light shielding plate reaches the open position. It will be. By controlling the drive voltage supplied to the motor in this way, shock and vibration at the start of driving the mirror and the light shielding plate can be prevented, and the motor is stopped when the mirror reaches the shooting position. This prevents the shading plate from being suddenly driven.

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 the mirror 11 is positioned inside the photographing optical path 14 as shown in the figure when the finder is observed. The target screen is imaged on the focusing screen 15 toward 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, at the time of observing the viewfinder, the film 7 is not exposed by a part of the photographing light flux that has passed around the mirror 11.

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 rotatably attached to a shaft 21 provided in the mirror box 10. Has been done. On one side surface of the mirror box 10, a drive plate 24 is provided with a rotation shaft 23.
The drive plate 2 is attached so as to be rotatable around the
4 is driven by a motor 28 via gears 25, 26, 27 rotatably mounted inside the mirror box 10. 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, a fan-shaped signal plate 35 made of a metal plate having a high reflectance, such as aluminum, is fixed to the drive plate 24.

Shafts 36 and 37 are planted on the side surface of the mirror box 10, and a mirror up lever 40 and a cam lever 41 are rotatably attached to one of the shafts 36. As shown in FIG. 4, each of these levers 40 and 41 has a rising edge 4 formed on the mirror up lever 40.
0a and the adjusting plate 42 are connected by the clamping force of the spring 43. The adjusting plate 42 is axially attached to the cam lever 41 by a shaft 44, and passes through a long hole 45 to screw 46.
It is fixed in any adjustment position by tightening. 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 has an arc portion 48a centered on the rotation shaft 23 of the drive plate 24 and a curved portion 4 continuous with the arc portion 48a.
A cam groove 48 including 8b is formed. In the cam groove 48, the mirror drive pin 32 planted in the arm 30 is provided.
Are engaged. Further, a pin 50 planted 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 planted in the mirror box 10 has an interlocking lever 52 biased counterclockwise by a spring 51.
Is rotatably attached to the shaft. The interlocking lever 52 is formed with a slot 53 whose one end side is open, and an arm 55 in which a pin 54 is planted is integrated. The pin 54 is engaged with a long hole 58 formed at one end of the light shielding plate up lever 57. The light shield plate up lever 57 is pivotally attached to a shaft 59, and an edge 61 with which a pin 60 protruding from the light shield plate 12 abuts is formed on the other end side, and a pin 62 is planted. Then, the spring 63 rotates the pin 6 so as to go around the pin 62.
It is hung between 0 and the light shielding plate up lever 57.

The lock lever 6 is attached to the shaft 65 protruding from the camera body 1.
6 is pivotally attached and is urged counterclockwise by a spring 67. One end 66a of the lock lever 66 is connected to the frame 2
The pin 50, which is planted at 0, faces the turning locus, and the other end 66b locks the pin 60 in the illustrated state to prohibit the light shield plate 12 from turning clockwise. There is. When the mirror 11 is rotated to the position indicated by the chain double-dashed line in FIG. 7, the lock lever 66 is moved by the pin 50.
Rotates in the clockwise direction, so that the other end 66b of the lock lever 66 releases the lock of the pin 60.

On the side surface of the mirror box 10, two reflective photosensors 70 and 71 are provided on the same circumference with the axis 23 as the center. As is well known, these photo sensors 7
Reference numerals 0 and 71 include a light projecting portion and a light receiving portion. Light from the light projecting portion is reflected by the signal plate 35, and when this reflected light is detected by the light receiving portion, a high level signal (hereinafter referred to as H signal).
Is output. Therefore, the photosensors 70 and 71 are connected to the edge 3 of the signal plate 35 that rotates together with the drive plate 24.
The state of the output signal is changed at the moment when 5a and 35b pass. The photosensors 70 and 71 are not necessarily mounted on the same circumference as described above as long as they can detect the passage of the edges 35a and 35b.

Furthermore, a shaft 73 protruding from the side surface of the mirror box 10
A V-shaped stop lever 74 is mounted on the shaft. The stop lever 74 is biased by a spring 75 so as to be pressed against the stopper 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.
When the drive plate 24 is at the initial position, the recess 7
The light-shielding plate drive pin 33 is fitted and positioned in 4a, and at the rotation end of the drive plate 24, the light-shielding plate drive pin 33 is fitted in the recess 74b to mechanically stop the movement of the drive plate 24.

In addition to the stop position regulation of the drive plate 24 described above, the mirror 1
1 is positioned at the finder observation position by a stopper hin 80 which is brought into contact with 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. The position of the stopper pin 80 can be changed by adjusting the movement of the adjusting screw 83, 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 at the time of assembly, separately from the interlocking system from the motor 28 to the cam lever 41, so that the subject screen is correctly guided to the focusing screen 15. Will be set. Incidentally, 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. It can be transmitted 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.

The shutter button 18 is pressed to release the release detection circuit 85.
When it is detected at, the CPU 86 starts processing according to the sequence program stored in the ROM 87. The CPU 86 first outputs a drive signal to the shutter drive circuit 5 incorporated in the lens unit 2, whereby 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 rotation signal output end 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.

The conduction of transistor 93, because capacitor 95 begins to charge, the voltage V _a of the line a as shown in FIG. 3, so that gradually rises. On the other hand, t ₁
At the point of time, as shown in FIG.
5, the signal state is L level. Therefore, the output terminal of the comparator 96 is also L
It is at the level, and the transistor 97 is in the conductive state. As a result, the voltage V _b appearing on the line b is a voltage that is set by the resistors 98 and 99 for voltage division, and a voltage drop due to the current from the transistor 97 is superimposed on the voltage V _b.
The voltage level is proportional to the voltage of _b1 .

Diodes 101 and 1 are respectively provided on the lines a and b.
02 is connected in the reverse direction, and these are connected to each other and then connected to the operational amplifier 104. Thus, the output terminal of the operational amplifier 104, the voltage V _a, of the V _b,
The voltage corresponding to the lower one appears. As a result, the normal drive voltage V _c appearing at the point _c is, as shown in FIG. 3, the line a until the time t ₂ where V _a <V _b.
Gradually it increases in proportion to the voltage V _a at, thereafter becomes a constant level proportional to the voltage V _b1 of the line b.

The motor 28 is driven by the forward drive voltage V _c having such a waveform.
When the motor is driven in the normal direction, the motor 28 gradually rises at the time of its startup, and accordingly, the drive plate 24 also rotates while gradually increasing the speed. When the drive plate 24 rotates, 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 resist the urging force of the spring 75 in the counterclockwise direction. While oscillating, the driving plate 24 escapes by passing over the guide surface 77, and rotates in the counterclockwise direction from the initial position in FIG. When the signal plate 35 is at the initial position shown in FIG. 1, the photo sensor 71 outputs the H signal,
As described above, the normal rotation of the drive plate 24 is started, and the signal plate 35
At the moment when is rotated, the photo sensor 71 also outputs an L level signal.

When the drive plate 24 rotates in the forward direction and the mirror drive pin 32 rotates together with the drive plate 24, 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 of the cam groove 48. From the midpoint between the portion 48a 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 gradually approaching it, in the initial stage of the rotation of the drive plate 24, the swing of the cam lever 41 is gentle with respect to the rotation of the mirror drive pin 32. become. As a result, the start-up when the motor 28 is started is moderately controlled by electrical control, and is mechanically controlled in the same manner.
Most of the electric and mechanical shocks at the time of starting of No. 4 are eliminated.

When the cam lever 41 is swung in this manner, the mirror up lever 40 is pushed up via the rising 40a and the adjusting plate 42, and is swung counterclockwise as well. 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. Thus drive plate 2
In the process in which 4 is rotated in the forward direction, the mirror drive pin 32 reaches the right end of the cam groove 48 and then moves to the left. 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. 1
It is lifted from 4 to the shooting position where it was completely retracted. At the same time, the lock lever 66 is rotated clockwise by the pin 50 to release the lock with respect to the pin 60, and the light shielding plate 12 becomes rotatable.

The moment t ₃ when the mirror 11 rises to the position shown in FIG.
In addition, the edge 35a of the signal plate 35 is detected by the photo sensor 70, and the photo sensor 70 outputs the H signal as a timing signal for completion of mirror up. Photo sensor 70,
The output signal of 71 is 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 86a of the CPU 86 is at the L level only for a time of Δt, for example, 15 msec.

When the forward rotation signal is interrupted in this way, the relay 90
Is turned off, and the contact piece 91 is switched to the ground terminal 92. Then, the drive of the motor 28 is suddenly stopped and the drive plate 24
The rotation of 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 the line b is lowered to a value proportional to the set voltage V _b2 (<V _b1) by a resistor 98, 99.

At the time point of t ₄ after the time of Δt has passed, CP
The normal rotation signal again appears at the normal rotation signal output end 86a of U86. 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 is again rotated in the normal direction by the normal rotation drive voltage V _c appearing at the point _c . As described above, the forward drive voltage V _c gradually increases in proportion to the voltage V _{a of the} line a, and V _a ≧ V
After the time point t ₅ when it becomes _b, it becomes a constant level proportional to the voltage V _b2 on the line b.

When the normal rotation of the motor 28 is restarted by such a normal rotation drive voltage V _c and the drive plate 24 gradually rotates counterclockwise, the mirror drive pin 32 causes the bent portion 4 of the cam groove 48 to move.
8b and is moved along the arc portion 48a, the cam lever 41 and the mirror up lever 40 remain in their respective positions, 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 shield 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 1 is moved.
Since 2 rotates about the rotating shaft 21, the aperture 16 formed in the mirror box 10 is released.

Even when the light shield plate 12 is rotated in this manner, the motor 28 is driven while gradually increasing the speed at the rising portion thereof, so that the light shield plate drive pin 33 and the interlocking lever 52 are engaged at the initial stage of the drive. There is no shock at the moment you do it. 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. It is set to a value proportional to a voltage level V _b2 than the voltage level V _b1 when rotating. Therefore, the shock when the motor 28 is stopped can be suppressed to be lower than that at 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 as much as possible.

When the motor 28 is driven by the forward drive voltage V _c proportional to V _b2 and the drive plate 24 continues to rotate, the light shield plate 12
6 is moved to the photographing position completely retracted from the photographing optical path 14 as shown by the two-dot chain line in FIG.
Is open. At the same time, as shown in FIG.
Is detected by the photo sensor 71, and the H signal is output from the photo sensor 71 as a timing signal for completion of the light shielding plate up. At time t ₆ when this timing signal is input to the CPU 86, the normal rotation signal is not supplied from the normal rotation signal output end 86a, the relay 90 is turned off, the contact piece 91 is switched to the ground terminal 92, and the motor 28 is turned on. Will stop.

When the drive plate 24 is stopped, the drive plate 24 is positioned by the stop lever 74 at the end position of the rotation so that the drive plate 24 is not excessively rotated due to the ellipticity of the motor 28. Regulated. That is,
When the shading plate drive pin 33 rotates toward its end position, the shading 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 impact when the light shielding plate drive pin 33 is stopped in the recess 74b can be alleviated.

The H level signal from the photo sensor 71 is supplied to the light shielding plate 12
Is also used as a movement completion signal of the CPU, 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, and the reverse rotation signal output end 86b of the CPU 86 goes high.
Become a level. 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 the reverse direction by the reverse drive voltage V _d appearing at the point _d . Incidentally reverse drive voltage V _d appearing at point d, the output voltage, i.e. the voltage V _e appearing on line e of the operational amplifier 117 appears in proportion to any greater voltage between the voltage V _f appearing on line f. The voltage V _e appearing on the line e is the voltage dividing resistor 1
While being fixed to the constant voltage _e0 determined by 18, 119, the voltage V _f appearing on the line f gradually decreases due to the charging of the capacitor 118. That is, when the transistor 120 is turned on by the reverse drive signal, the transistor 121 is cut off, so that the voltage, which has been maintained at a constant level by the resistor 122, gradually drops due to the charging of the capacitor 118. 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} point _d is gradually increased 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 being decelerated 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 light shielding plate up lever 57 also rotates counterclockwise about the shaft 59,
The shading plate 12 descends from the position shown in FIG. 5 to the position shown in FIG. 4, and closes the aperture 16. When the shading plate 12 closes the aperture 16, the fourth
As shown in the drawing, the pin 62 implanted in the light-shielding plate up lever 57 presses the middle portion of the spring 63 so as to bend it. As a result, the light shielding plate 12 is elastically held at the position where the aperture 16 is closed by the biasing force of the spring 63.

The mirror drive pin 32 moves in the region on the left side of the cam groove 48, that is, in the arc portion 48a until the light shield plate 12 is completely lowered in this manner, so that the cam lever 41 and the mirror up lever 40 move to the first position. It remains held in the position shown in FIG. Then, the drive plate 24 is moved to a position where the light shielding plate 12 completely closes the aperture 16.
At the time point t ₈ when the signal is reversed, the edge 35a of the signal plate 35
Passes through the photo sensor 70, and H
The signal will be output. 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. Lever 40
And are rotated clockwise about shaft 36. Then, the frame 20 rotates counterclockwise via the elongated hole 49 and the pin 50, the frame 20 contacts the stopper pin 80 and is stopped, and the mirror 11 is returned to the finder observation position. At time t ₁₀ when the mirror 11 is returned to the finder observation position in this manner, the edge 35b of the signal plate 35 is detected by the photosensor 71, and the photosensor 71 outputs the H signal as a timing signal for mirror down completion.

When the timing signal is input to the CPU 86, the reverse rotation signal becomes L level at time t ₁₀ . As a result, the relay 112 is turned off and the contact piece 114 is connected to the ground terminal 115.
Motor 28 is stopped and 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 these is greatly alleviated. become.

Further, even 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. 1, the shading plate drive pin 33 is guided by the guide surface 7 that is inclined with respect to its locus.
7, the stop lever 74 is swung counterclockwise against the spring 75 while passing over it to be fitted into the recess 74a, and the position thereof is regulated. At this time, the guide surface 77
Since the front edge of the above acts as a cushioning surface for the light-shielding plate drive pin 33 and absorbs the shock, the vibration that tends to occur when the drive plate 24 is stopped is 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. And after opening and closing for exposure,
The shutter 6 in the closed state is brought back into the open state. 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 side is in a light-tight state. Further, as the mirror up lever 40 rotates clockwise, the lock lever 66 rotates counterclockwise, and one end 66b of the lock lever 66 locks the light shielding plate 12 at the closed position via the pin 60. become.

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.

Although the driving of the motor 28 in the normal photographing sequence has been described, the mirror-up processing from t _{1 to} t ₆ and the mirror-down processing from t _{7 to} t ₁₀ are
It is designed to be executed as a sub-routine in the photographing sequence, and can also be executed by an interrupt command to the CPU 86. That is, mirror up,
Each mirror down operation can also be performed by operating a separately provided mirror up button or mirror down button. For example, when the mirror is raised by the interrupt command, the processing is executed only when it is confirmed by the signal states of the photosensors 70 and 71 that the mirror 11 is in the down position.

As described above, when the drive of the mirror 11 or the light shielding plate 12 is started while gradually increasing the forward drive voltage V _c , the mirror 11 and the light shielding plate are not affected by the unstable rising characteristic of the motor 28. 12 starts to move smoothly, and almost no vibration or shock occurs. Moreover, when the movement of the mirror 11 is completed, the driving of the motor 28 is temporarily stopped, so that the movement of the light shielding plate subsequent thereto is not shockedly started.

〔The invention's effect〕

As described above, according to the present invention, when the mirror and the light shielding plate are sequentially driven by the motor, the motor is temporarily stopped between the driving of the mirror and the light shielding plate, and the respective driving is started. The driving voltage that gradually increases is supplied to the motor. As a result, the load applied to the motor does not fluctuate intermittently when switching between driving the mirror and driving the light shielding plate. Moreover,
Even when the motor starts up when driving the mirror and the light shield, the motor gradually receives a load, and at this time, vibration does not occur, and the mirror and the light shield operate smoothly. Become so.

[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 using 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-55-98726 (JP, A) JP 62-183441 (JP, A)

Claims (1)

[Claims] 1. A camera in which a mirror at a finder observation position and a light shielding plate at a light shielding position are sequentially moved to a photographing position and an open position in association with the forward rotation of the motor. The drive voltage supplied to the camera is gradually increased and then maintained at a constant level to move the mirror from the finder observation position to the shooting position, and when the mirror reaches the shooting position, the drive voltage is turned off for a predetermined time. After that, the drive voltage that is gradually increased again and maintained at a constant level is supplied to the motor to move the light shielding plate from the light shielding position to the open position, and when the light shielding plate reaches the open position, the drive voltage is increased. A control circuit for a motor for driving a mirror and a light-shielding plate, characterized in that the above is cut off.