JPH0712975Y2 - Program shutter with lens drive mechanism - Google Patents

Description

[Detailed description of the device] [Industrial applications]

The present invention relates to an improvement of a program shutter in which a shutter motor and a photographing lens system are driven by using a step motor as a drive source, and particularly, a program with a lens driving mechanism which improves closing response and can be adapted even at high speed exposure seconds. Regarding the shutter.

[Prior art]

First, FIG. 7 shows a conventionally known program shutter with a lens driving mechanism using a step motor as a driving source. In the drawing, 50 is a blade drive ring, 51 is a lens drive ring, and both rings 50 and 51 are concentrically supported rotatably around an aperture 52. The blade drive ring 50 is formed with a gear surface 50 a, and the gear surface 50 a meshes with the gear 53. Gear 5 coaxial with gear 53
Reference numeral 4 meshes with an axle wheel 55 of a step motor (not shown), and the blade drive ring 50 rotates left and right by the rotation of the step motor. The blade drive ring 50 has a cam surface 50b.
The boss 56a of the interlocking cam 56 urged clockwise by a spring (not shown) is in contact with the boss 56a. Therefore, when the blade drive ring 50 is rotated clockwise from the illustrated state,
The interlocking cam 56 includes the shaft 56 while the boss 56a contacts the cam surface 50b.
Rotating counterclockwise about b, the counterclockwise rotation of the interlocking cam 56 operates the shutter blades in the opening direction, and the clockwise rotation of the interlocking cam 56 operates the shutter blades in the closing direction. Are associated with each other. Further, the lens drive ring 51 is biased clockwise by the spring 57, but the pin 51a implanted in the lens drive ring 51 contacts the step 50c at the end of the cam surface 50b to restrict the clockwise rotation. Has been done. Therefore, when the blade drive ring 50 rotates clockwise, the lens drive ring 51 rotates clockwise while the pin 51a abuts against the step 50c, and the rotation of the lens drive ring 51 causes, for example, a helicoid or other focus adjustment mechanism. Operate. A gear 58 is formed on the gear surface 51b formed on the lens drive ring 51.
Are engaged with each other, and a ratchet 59 is provided coaxially with the gear 58. Further, 60 is an iron piece lever for engaging the ratchet 59, and the iron piece lever 60 is urged clockwise by a spring 61, but in the initial state, it is a magnet.
It is adsorbed by 62 and is restricted from rotating clockwise. When the blade drive ring 50 rotates clockwise, the lens drive ring 51 rotates clockwise, and the control circuit (not shown) demagnetizes the magnet 62 by a signal generated during focusing. Is rotated clockwise by a spring 561 to engage the ratchet 59, the lens drive ring 51 is stopped by the engagement of the ratchet 59, and the taking lens (not shown) is positioned. Even after the lens drive ring 51 is stopped, the blade drive ring 50 continues to rotate, and its cam surface 50b rotates the interlocking cam 56 counterclockwise to start the opening operation of the shutter blade (not shown). Then, after the desired exposure time elapses, the motor axle
When 55 is reversed, the blade drive ring 50 rotates counterclockwise, the interlocking cam 56 rotates clockwise while the boss 56a contacts the cam surface 50b, and closes the shutter blade (not shown) to complete the exposure operation. . Then, from the time when the step 50c of the blade drive ring 50 contacts the pin 51a, the lens drive ring 51 also rotates counterclockwise and the lens mechanism also returns to the initial position.

[Problems to be solved by the device]

Now, when the step motor is used as the drive source as described above,
Since the shutter blades are opened by the forward rotation of the step motor and the shutter blades are closed by the reverse movement of the step motor, the closing response is poor and it is difficult to deal with high-speed exposure seconds. There was a problem. Moreover, since the opening operation and the closing operation are both pulse-controlled, it is necessary to accurately control the reversal of the pulse phase at the time of the transition from the opening operation to the closing operation in order to improve the exposure accuracy. There was also the problem of becoming.

[Means for solving problems]

The present invention has been made in view of these problems,
An object of the present invention is to provide a program shutter with a lens drive mechanism, which has a step motor as a drive source and which has excellent closing responsiveness and in which the transition from the opening operation to the closing operation is performed only by timing control. The above object of the present invention can be achieved by the following means. The program shutter with a lens driving mechanism of the present invention includes: a blade driving ring which is rotationally driven by a step motor and is associated with opening and closing of shutter blades by its rotational movement;
A lens drive ring connected to the focus adjusting mechanism; a ratchet wheel connected to the lens drive ring; and a ratchet click driven by a magnet to engage with the ratchet wheel: the lens drive ring is in focus As a prerequisite technique for a program shutter with a lens drive mechanism that engages the ratchet click with the ratchet wheel at the timing when the position is reached: a cam member for driving the shutter blade is constantly urged in the closing direction. A cam member that is swingably supported on the blade drive ring, and when opened, the relative position to the blade drive ring is fixed by the magnet, and the cam member is biased in the closing direction. Cam interlocking lever with a cam surface that drives in the opening direction against The a: have been made so as to actuate the shutter blade in the closing direction by releasing the fixing of the cam interlock lever by the magnet.

[Action]

In the present invention, the relative position of the cam interlocking lever with respect to the blade drive ring is fixed by the magnet during the opening operation, and when the blade drive ring is rotated by the step motor, the shutter blade is biased by the cam surface formed on the cam interlocking lever. The cam member for driving is driven to drive the shutter blades in the opening direction. Then, when the fixing of the cam interlocking lever by the magnet is released at the desired exposure time, the cam member closes the shutter blade by the urging force in the closing direction. As described above, in the present invention, the closing responsiveness is determined by the biasing force of the cam member, and the rotation speed of the step motor does not contribute to the closing responsiveness, so the closing responsiveness is improved and it becomes easier to cope with high-speed exposure seconds. Further, the control of the inflection point from the opening operation to the closing operation is only required to control the operation timing of the magnet, and the reversal of the step motor is merely the operation for returning the initial position of the shutter mechanism. It becomes good with the simple one that only reverses.

【Example】

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. First, FIGS. 1, 2, and 3 are plan views showing an embodiment of the present invention. FIG. 1 shows the initial state, FIG. 2 shows the shutter fully opened, and FIG. 3 shows the shutter closed. Each time is shown. In FIGS. 2 and 3, some of the elements shown in FIG. 1 are omitted in order to avoid complication of the drawings. In the drawing, the blade drive ring 1 rotatably supported along the circumference of the aperture 2 has a gear surface 1a, and the rotation of the step motor shaft wheel 3 is supported coaxially with the gears 4 and 4. It is transmitted to the gear surface 1a via the gear 5.
In this embodiment, it is assumed that the shutter blade (not shown) is opened by the clockwise rotation of the blade drive ring 1. Next, 6 is a lens driving ring connected to a helicoid or other focus adjusting mechanism. The lens driving ring 6 is biased clockwise by a spring 26, but the step 6a
Is brought into contact with the locking member 1b planted in the blade drive ring 1 to restrict the rotation. The lens drive ring 6 has a gear surface 6b, and the gear surface 6b
A ratchet wheel 8 is axially supported coaxially with a gear 7 that meshes with. Next, 9 is a ratchet click which is swingably supported by a shaft 10, and a claw portion 9a formed at one end of the ratchet click 9 is a shelf portion of the ratchet wheel 8 in an initial state.
8a, and the radius of the shelf 8a is larger than the radius of the ratchet 8b. An engaging protrusion 9b is formed at the other end of the ratchet click 9, and the engaging protrusion 9b is inserted into an engaging groove 12a formed at one end of the movable iron piece 12, and the movable iron piece 12 is an iron piece lever 13 It is pinched so that it can be moved. As shown in the perspective view of FIG. 4, the iron piece lever 13 is swingably supported by a shaft 14 and has hook-shaped holding portions 13a above and below the end portion in the longitudinal direction. Movable iron piece 12 on part 13a
Is inserted movably in the direction of arrow A. Then, the engaging projection 9b of the ratchet click 9 is inserted into the engaging groove 12a formed in the movable iron piece 12, and the ratchet click 9 is biased clockwise by the spring 11. Further, a boss 13c for fixing the relative position of the cam interlocking lever 15 to the blade drive ring 1 is formed at the tip of the arm 13b extending from the movable iron piece 13. As shown in FIGS. 1 to 3, an arc-shaped cam interlocking lever 15 is swingably supported by a shaft 16 on the blade drive ring 1, and a cam that is substantially concentric and arcuately raised on its surface. Face 15a
And a cam surface 15b that is inclined and raised.
When the tip of the cam interlocking lever 15 reaches the position of the boss 13c as the blade drive ring 1 rotates clockwise, the cam surface 15a engages with the boss 13c and the cam interlocking lever 15 rotates counterclockwise. Is restricted, and the relative position of the cam interlocking lever 15 to the blade drive ring 1 is fixed. Further, 17 is a blade drive cam, and the blade drive cam 17 is rotatably supported by a shaft 18 fixed to the camera body,
The spring 19 urges it clockwise, but the locking mechanism (not shown) restricts the clockwise rotation in the state shown in FIGS. 1 and 3. This blade drive cam 17
A boss 17a is planted on the surface of the cam, and when the cam surface 15b at the rear end of the cam interlocking lever 15 reaches the position of the boss 17a as the blade drive ring 1 rotates clockwise, the cam surface 15b springs. Rotate the blade drive cam 17 counterclockwise against 19. The blade drive cam 17 is connected to a shutter blade (not shown), the shutter blade opens when the blade drive cam 17 rotates counterclockwise, and the shutter blade closes when the blade drive cam 17 rotates clockwise. It is done like this. 20 is a magnet for driving the iron piece lever 13, and 21 is an iron core of the magnet 20. The control operation required in the above-mentioned shutter mechanism is the forward / reverse rotation of the step motor connected to the axle 3 and the magnet.
There is only 20 on / off control, and such control is executed by a simple control system as shown in FIG. In FIG. 5, 20 is the above-mentioned magnet, 22 is a release switch that generates a release signal RS in conjunction with a shutter button (not shown), and 23 is a focus detection signal AF when the taking lens reaches the focus position. The well-known focus detection unit, which generates 24, has a built-in light receiving element and an optical integrator, and at the timing when the integrated light receiving amount after receiving the AE start signal AES indicating the start point of the exposure integrating operation reaches a predetermined value. A well-known exposure control unit for generating an AE end signal AEE indicating an exposure end point, 25 is a step motor connected to the above-mentioned axle 3, and 26 is a control device having a microcomputer for controlling the above elements. Incidentally, the control device
Details of the control operation of 26 will be described later. Next, the operation of this embodiment will be described with reference to the above items and the flowchart of FIG. First, in the initial state, the mechanism of the present invention is in the state shown in FIG. In this state, when the release switch 22 generates a release signal RS in conjunction with the shutter button being turned on, the control device 26 excites the magnet 20 and causes the step motor 25 to rotate normally. The rotation direction of the step motor 25 is determined by the phase of the A-phase pulse φa and the B-phase pulse φb, and the rotation speed of the step motor 25 is determined by the pulse period of both pulses. First, as the magnet 20 is excited, the movable iron piece 12 is magnetically attached to the iron core 21 together with the iron piece lever 13. Further, since the engagement projection 9b of the ratchet click 9 is engaged with the engagement groove 12a of the movable iron piece 12, the ratchet click 9 is also fixed in the state shown in FIG. On the other hand, the forward rotation of the step motor 25 causes the axle wheel 3 to rotate clockwise by one pitch, and the gears 4 and 5 rotate counterclockwise. Then, the rotation of the gear 5 is transmitted to the gear surface 1a, and the blade drive ring 1 rotates clockwise by one pitch. However, even if the blade drive ring 1 starts rotating in the clockwise direction in this way, the blade drive cam 17 does not spring until the cam surface 15b of the cam interlocking lever 15 reaches the position of the boss 17a of the blade drive cam 17. Since the state of FIG. 1 is maintained by the tension of 19, the shutter blade (not shown) is in the closed state. Since the locking member 1b that locks the lens driving ring 6 is planted on the blade driving ring 1, the lens driving ring 6 has a step 6a as the blade driving ring 1 rotates. While being in contact with 1b, the spring 26 rotates clockwise by the tension of the spring 26. Then, the focus adjustment mechanism (not shown) is driven by the rotation of the lens drive ring 6, the focus detection unit 23 generates a focus detection signal AF at the point where the photographing lens has moved to the focus position, and the control device 26 sets the focus. When the focus detection signal AF is received, the magnet 20 is demagnetized. On the other hand, by rotating the lens drive ring 6 clockwise,
The gear 7 meshing with the gear surface 6b rotates counterclockwise, and the ratchet wheel 8 coaxial with the gear 7 also rotates counterclockwise. Then, since the movable iron piece 12 is released from the iron core 21 of the magnet 20 at the timing when the magnet 20 is demagnetized, the ratchet click 9 is rotated clockwise by the spring 11, and the claw portion 9a thereof is either the ratchet portion 8b. The ratchet wheel 8 stops rotating by engaging with the claw of the ratchet wheel. Therefore, the rotation of the lens drive ring 6 is stopped at that time, and the taking lens (not shown) is positioned at that position. When the positioning of the photographing lens is completed in this way, the cam surface 15b of the cam interlocking lever 15 has not reached the position of the boss 17a of the blade drive cam 17, and the blade drive cam 17 is in the state shown in FIG. Therefore, the shutter blade (not shown) is not opened. Now, the step motor 25 is continuing the normal rotation operation further, and eventually the tip of the cam interlocking lever 15 reaches the position of the boss 13c. Then, immediately before the tip of the cam interlocking lever 15c reaches the position of the boss 13c, the control device 26 causes the magnet 20 to move.
The movable iron piece 12 is magnetically attached to the iron core 21. Therefore,
The cam interlocking lever 15 continues to rotate while its cam surface 15a abuts on the inside of the boss 13c (the side facing the center of the aperture 2), and the cam interlocking lever 15 bosses a counterclockwise rotational movement. The relative position with respect to the blade drive ring 1 is fixed by being regulated by 13c. Movable iron piece at this time
Although 12 is also magnetically attached to the iron core 21, since the ratchet click 9 is urged clockwise by the spring, the ratchet wheel 8 is kept locked. When the cam surface 15b of the cam interlocking lever 15 reaches the position of the boss 17a as the stepping motor 20 continues to rotate in the forward direction, the blade drive cam 17 contacts the spring 19 while the boss 17a contacts the cam surface 17. Counterclockwise,
The shutter blade is operated in the opening direction. When the shutter blade reaches the AE start position (the position at which the exposure control unit 24 is activated) immediately before it becomes a pinhole, the control device 26 adds the AE start signal AES to the exposure control unit 24 and integrates the field light. Start operation. After the exposure control unit 24 starts to operate, when the integrated value of the field light reaches a predetermined value, the exposure control unit 24 generates the AE end signal AEE, and the control device 26 receives the AE end signal AEE, and the magnet 20
Degauss. Further, in the case of low brightness, the aperture 2 is fully opened before the AE end signal AEE is generated, and a long exposure longer than that causes camera shake.
When a predetermined time has elapsed after the AE start signal AES was generated, the magnet 20 is demagnetized regardless of the presence or absence of the AE end signal AEE. FIG. 2 shows a state in which the blade drive ring 1 is rotated to the fully open position of the aperture 2, and the cam surface 15b rotates the blade drive cam 17 to the left limit position. When the magnet 20 is demagnetized as described above in the state of FIG. 2, the iron piece lever 13 is released from the magnetic attachment by the iron core 21, and the fixing of the cam interlocking lever 15 by the boss 13c is also released. Therefore, in the blade drive cam 17, the boss 17a has the cam interlocking lever 1
While rotating 5 counterclockwise, it is instantaneously rotated clockwise by the spring 19, and the clockwise rotation of the blade drive cam 17 causes the shutter blade (not shown) to operate in the closing direction. Incidentally, FIG. 3 shows a state in which the closing operation of the shutter blades is completed in this way. After the shutter closing delay time has passed since the magnet 20 was turned off, the control device 26 reverses the step motor 25 by exchanging the phases of the A-phase pulse φa and the B-phase pulse φb. When the step motor 25 rotates in the reverse direction, the ratchet click 9 has already been released from the magnet iron core 21 at this point, so the blade drive ring 1 also rotates counterclockwise while the locking member 1b rotates the lens drive ring 6 counterclockwise. It rotates around and returns to the initial position shown in FIG.

【effect】

As described above, in the present invention, when the blade is opened, the relative position of the cam interlocking lever with respect to the blade drive ring is fixed by the magnet drive, so that the shutter blade is rotated by the rotation of the blade drive ring by the step motor. Will operate in the opening direction, so that the opening characteristics of the shutter blades are determined depending on the step motor. On the contrary, during the closing operation of the blade, the fixing of the cam interlocking lever is released, and the blade operates in the closing direction by the spring drive, so that the closing response of the blade is determined depending on the spring. Thus, in the present invention, since the blades are driven by the step motor during opening, the opening characteristics can be ideally controlled, and at the time of closing, the connection with the step motor is cut off and the return by the spring is performed. It has excellent responsiveness and can sufficiently cope with high-speed exposure seconds. Further, the control of the inflection point from the opening operation to the closing operation is only required to control the operation timing of the magnet, and the reversal of the step motor is merely the operation for returning the initial position of the shutter mechanism. All you have to do is simply flip it. Further, in the present invention, since the magnet for positioning the photographing lens mechanism can be used as the magnet for fixing the cam interlocking lever, it is possible to effectively use the magnet that requires a large storage volume in the mounted parts. There is no fear that the mounting space will increase.

[Brief description of drawings]

1 is a plan view showing an initial state of a program shutter according to an embodiment of the present invention, FIG. 2 is a plan view showing a fully opened state of the program shutter shown in FIG. 1, and FIG. 3 is shown in FIG. Plan view showing the closed state of the program shutter, FIG.
FIG. 7 is a perspective view showing the iron piece lever, the movable iron piece and the ratchet click portion in the shutter mechanism, FIG. 5 is a block diagram of the control system of the present invention, FIG. 6 is a control flowchart of the present invention, and FIG. 7 is The top view of the conventional program shutter with a lens drive mechanism which made the drive source the step motor. 1 ... Blade drive ring, 1a ... Gear surface 1b ... Locking member, 2 ... Aperture 3 ... Motor shaft wheel, 4.5 ... Gear 6 ... Lens drive ring, 6b ... Gear surface 8 ... ... Ratchet wheel 9 ... Ratchet click 9b ... Engagement protrusion, 12 ... Movable iron piece 13 ... Iron piece lever, 13c ... Boss 15 ... Cam interlocking lever, 15a and 15b ... Cam surface 17 ... Blade drive ring , 17a …… Boss

Claims (1)

[Scope of utility model registration request] 1. A blade drive ring that is rotationally driven by a step motor and is associated with the shutter blade so that the shutter blade opens and closes due to the rotational movement, and the blade drive ring rotates following the blade drive ring and is connected to a focus adjustment mechanism. A lens drive ring, a ratchet wheel connected to the lens drive ring, and a ratchet click that is driven by a magnet and engages with the ratchet wheel. The lens drive ring is moved at a timing when the lens drive ring reaches a focus position. In a program shutter with a lens drive mechanism in which a ratchet click is engaged with the ratchet wheel, a cam member for driving the shutter blade, which is always biased in a closing direction, and the blade driving ring. It is supported so that it can swing freely, and at the time of opening it A relative position with respect to the ring is fixed by the magnet, and a cam interlocking lever formed with a cam surface for driving the cam member in the opening direction against the biasing force in the closing direction; A program shutter with a lens drive mechanism, wherein the shutter blade is operated in a closing direction by releasing the fixing of the cam interlocking lever.