JPH11194382A - Light quantity adjusting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize variable speed driving of a light quantity adjusting member by forming a non-linear cam groove on the light quantity adjusting member and engaging a moving member moving in a direction orthogonal to the moving direction of the light quantity adjusting member in the groove. SOLUTION: The driving pin 10c of a rack gear 10 is inserted and engaged with driving cams 12a and 13a formed on the light quantity adjusting members 12 and 13. When a feed screw 4 is rotated by a stepping motor 1, the gear 10 is guided by the guide hole 11a of a bottom board 11 so that it may move straight. When the gear 10 is guided by the guide hole 11a of the bottom board 11 so that it may move straight, the driving pin 10c of the gear 10 traces the cams 12a and 13a formed on the members 12 and 13 and moves the members 12 and 13 in an opposite direction to each other. Thus, the quantity of luminous flux passing through the aperture part 11f of the bottom board 11 is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light amount adjusting device mounted on an optical apparatus such as a video camera and a still camera.

[0002]

2. Description of the Related Art Conventionally, when this type of light amount control device is mounted on a video camera, for example, it automatically controls the light exposure in response to a photographing condition and brightness that change every moment. The aperture opening diameter is changed by reciprocating driving. As a reciprocating driving device for reciprocatingly driving the light amount adjusting member, a method of driving only by electromagnetic action and a spring action in combination with the electromagnetic action shown in FIG. A proposed method has been proposed.

The reciprocating drive device of the light quantity adjusting device shown in FIG. 15 has a base plate 36 having a diaphragm opening 35 and a magnet net rotor 31 whose output shaft is rotatably supported by bearings of a cap 37 and a gap on the outer periphery. The yoke 32, which is fixed to a ground plate 36, which is provided and provided, and a driving coil 33 and a braking coil 34 disposed between the magnet rotor 31 and the yoke 32 constitute a driving unit.
And a drive lever 38 as a transmission member is fixed to the output shaft of FIG. A pair of light amount adjusting members 39, 4 are provided between the base plate 36 and the case 41 having the aperture 41a.
The pair of light amount adjusting members 39 and 40 are guided in the moving direction by guide holes 39c, 39d, 40c and 40d which engage with guide pins (not shown) provided on the base plate 36. The engagement holes 39a and 40a formed at the ends are provided with the engagement pins 3 at both ends of the drive lever 38.
8a and 38b are engaged with each other to transmit the rotational force from the drive unit. The return spring 42 is incorporated so as to bias the drive lever 38 in the closing direction. The ND filter 43 is fixed to the light amount adjusting member 39 and the light amount adjusting member 3.
It attenuates the amount of light that passes over part or the entirety of the opening formed by 9 and 40.

[0004]

However, in the conventional driving unit, the rotation speed is not constant because the driving circuit is complicated and expensive if the rotation speed is arbitrarily changed from the control circuit. Did not get. Therefore, in the conventional light amount adjusting device, the rotation speed is set and used according to the low speed most necessary for control.

As described in the conventional example, since the two light quantity adjusting members move in opposite directions to change the size of the opening, the light quantity adjusting member moves slightly when the aperture is small and the aperture is small. Even with the amount, the change ratio of the opening area becomes large. For this reason, the moving speed of the light quantity adjusting member is usually the slowest speed required for control when the aperture is small, and the entire area must be driven at this slow speed. In this case, on the open side, it is not possible to quickly follow the change in the amount of light, and the captured image may deviate from the appropriate exposure amount.

[0006]

According to a first aspect of the present invention, there is provided a light amount adjusting device for adjusting a light amount of a passing light beam by moving a light amount adjusting member in opposite directions using a motor as a driving source. A non-linear cam groove is formed in the adjustment member, and the cam groove is driven by the motor so that a moving member that moves in a direction orthogonal to the moving direction of the light amount adjustment member is engaged. Features.

According to a second aspect of the present invention, there is provided a motor, a feed screw rotationally driven by the motor, a rack which is screwed with the feed screw and moves linearly, and a non-linear cam which engages with the rack. A groove is formed, and a light amount adjusting member that adjusts the light amount of the passing light beam by moving in a direction perpendicular to the moving direction of the rack is provided.

According to a third aspect of the present invention, a motor, a moving member driven by the motor, and a cam groove engaged with the moving member are formed, and the moving member moves in a direction perpendicular to the moving direction of the moving member. And a light amount adjusting member for adjusting the light amount of the passing light beam by performing the setting, such that the cam displacement of the cam groove is increased as the light amount adjusting member moves from the small aperture state to the open state. I do.

According to a fourth aspect of the present invention, a motor, a feed screw rotationally driven by the motor, a rack which is screwed with the feed screw and moves linearly, and a cam groove which engages with the rack are provided. And a light amount adjusting member that adjusts the light amount of the passing light beam by moving in a direction orthogonal to the moving direction of the rack, and the cam is moved as the light amount adjusting member moves from the small aperture state to the open state. The cam displacement of the groove is set to be large.

According to a fifth aspect of the present invention, in addition to the third or fourth aspect, the cam displacement of the cam groove is set to become zero as the light amount adjusting member approaches an open state. It is characterized by that.

According to a sixth aspect of the present invention, a motor, a moving member driven by the motor, and a cam groove engaged with the moving member are formed, and the moving member moves in a direction orthogonal to the moving direction of the moving member. And a light amount adjusting member that adjusts the light amount of the passing light beam, and the cam displacement of the cam groove is
It is characterized in that it is set to zero as it approaches the end of the cam groove.

According to a seventh aspect of the present invention, there is provided a motor, a feed screw rotatably driven by the motor, a rack which is screwed with the feed screw and moves linearly, and a cam groove which engages with the rack. And a light amount adjusting member that adjusts the light amount of the passing light beam by moving in a direction perpendicular to the moving direction of the rack, and the cam displacement of the cam groove becomes zero as approaching the end. It is characterized by being set.

[0013] The invention described in claim 8 is the second invention,
In addition to the invention described in 4 or 7, the feed screw is arranged parallel to an output shaft of the motor.

According to a ninth aspect of the present invention, in addition to any one of the first to eighth aspects, the motor is a stepping motor.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 8 are views showing a light amount adjusting device according to a first embodiment of the present invention.

FIG. 1 is an exploded perspective view of the light amount adjusting device.

In FIG. 1, reference numeral 1 denotes a stepping motor as a driving source, which is positioned and fixed to a base plate 11 by a cover 8 so that the direction of an output shaft 1a is orthogonal to the optical axis.

Reference numeral 2 denotes a pinion gear which is press-fitted into the output shaft of the stepping motor 1, and a gear 3 which is press-fitted into the feed screw 4.
And are engaged. 4 feed screw is cover 8 and bearing 9
, And is rotatably supported by a shaft, and rotates integrally with the gear 3. 6 is the cover 8 by the screw 5
, And one end of the feed screw 4 is pressed against the bearing 9 to suppress thrust play.

The rack gear 10 engages with a guide hole 11a provided in a direction substantially parallel to the tangent of the circle perpendicular to the optical axis of the base plate 11, and the tooth 10a is engaged with the gear 4 of the feed screw 4.
a.

Therefore, the rotation of the feed screw 4 causes the ground plate 11 to rotate.
And can be moved along the guide hole 11a. The photointerrupter 7 has a detection gap 7 as shown in FIG.
The light shielding portion 10b of the rack gear 10 is fixed to the cover a by the cover 8 such that the light shielding portion 10b enters the a.

When the light-shielding part 10b enters the middle part of the detection gap 7a, the light reaching the light-receiving part from the light-emitting part of the photo-interrupter 7 is blocked by the light-shielding part 10b. At this time, the output signal of the photo interrupter 7 changes from L level to H level. In a state where the light shielding unit 10b does not shield the photo interrupter 7, the output signal of the photo interrupter 7 is at the L level.

Therefore, by detecting a change in the output signal of the photo interrupter 7, the position of the rack gear 10 (ie, the position of the light amount adjusting member) can be detected.

The rack gear 10 is provided with a guide hole 11
a, and a drive pin 10c protruding from the back side of the base plate 11 is engaged with drive cams 12a, 13a formed on the light amount adjusting members 12, 13, respectively.

The holding plate 14 is connected to the base plate 11 to hold the light amount adjusting members 12 and 13. This allows
The light amount adjusting members 12 and 13 are movable between the main plate 11 and the holding plate 14.

FIG. 2 is a view of the light amount adjusting device shown in FIG. 1 as viewed from the upper side, that is, the side on which the stepping motor 1 is mounted. , The photo interrupter 7 and the like are omitted.

FIG. 3 is a view of the light amount adjusting device shown in FIG. 1 viewed from the lower surface side, that is, the side on which the holding plate 14 is attached. FIG. 3 shows the relationship between the main plate 11, the light amount adjusting members 12, 13 and the rack gear 10. FIG. 4 is a view showing a state in which a holding plate is removed.

The light amount adjusting members 12 and 13 are formed with guide slits 12b and 12c and 13b and 13c, respectively. The guide slits 12b and 13b are
The guide slits 12c and 13c are engaged with the guide pins 11b provided on the base plate 11. Therefore, the light amount adjusting member 1
2 and 13 are movably held in the direction in which the guide slit is formed.

A drive pin 10c of the rack gear 10 is inserted into and engaged with the drive cams 12a and 13a formed on the light amount adjustment members 12 and 13, respectively.

The rack gear 10 includes a stepping motor 1
When the feed screw 4 is driven to rotate, the guide screw 11 is guided by the guide hole 11a of the base plate 11 and moves straight. When the rack gear 10 moves linearly while being guided by the guide holes 11a of the main plate 11, the drive pins 10c of the rack gear 10 are driven by the drive cams 12a, 1 formed on the light amount adjusting members 12, 13.
3a is traced, and the light amount adjusting members 12 and 13 are moved in opposite directions. Therefore, it is possible to adjust the light amount of the light beam passing through the opening 11f of the base plate 11.

FIGS. 5 to 7 show how the rack gear 10 moves along the guide holes 11a of the main plate 11, thereby moving the light amount adjusting members 12 and 13 to change the size of the aperture opening 15. FIG. .

FIG. 5 shows a state in which the aperture 15 is closed. The output signal of the photointerrupter 7 changes from L level to H level in the vicinity of this.

FIG. 6 shows a state in which the rack gear 10 has moved from the state shown in FIG.

FIG. 7 shows that the rack gear 10 further moves from the state shown in FIG.
Opened more than 1f, that is, a fully opened state.

FIG. 8 shows a driving pin 10c of the rack gear 10.
FIG. 6 is a diagram showing a state in which the cam 12a of the light amount adjusting member 12 is traced. The cam displacement (cam lift) of the cam 12a of the light amount adjusting member 12 will be described with reference to FIG.

In FIG. 8, θ 1 is the light amount adjusting member 12.
In the state where the opening 11f of the base plate 11 is closed (fully closed state), the moving direction of the rack gear 10 and the light amount adjusting member 12
Of the cam 12a. θ2, θ3
As the light amount adjusting member 12 moves in the opening direction, the moving direction of the rack gear 10 and the cam 12 of the light amount adjusting member 12
This shows a state in which the angle made with a gradually increases. By forming the cam 12a of the light amount adjusting member 12 in this manner, the rate of change of the aperture opening with respect to the moving amount of the rack gear 10 is optimized. That is, the cam displacement (cam lift) is set so that the change amount of the aperture opening becomes smaller with respect to the unit movement amount of the rack gear 10 on the small aperture side,
On the open side, the cam displacement (cam lift) is set so that the amount of change in the aperture opening becomes larger with respect to the unit movement amount of the rack gear 10.

However, at the end of the cam 12a of the light amount adjusting member 12, the moving direction of the rack gear 10 and the light amount adjusting member 1
The angle between the second cam 12a and the cam 12a is set to 0 °, and the angle between the moving direction of the rack gear 10 and the cam 12a of the light amount adjusting member 12 is gradually reduced from near the end of the cam 12a. You have set.

As described above, since the cam displacement (cam lift) converges to 0 from the vicinity of the end, the light amount adjusting member 12 can be stably stopped at the moving end.

The shape of the cam 13a of the light amount adjusting member 13 is set so that the cam displacement (cam lift) is small on the small aperture side and large on the open side, similarly to the shape of the cam 12a. It is set as follows.
At the end of the cam 13a, the angle between the moving direction of the rack gear 10 and the cam 12a of the light amount adjusting member 12 is zero.
Is set so that the cam displacement (cam lift) converges to 0 from near the open end of the cam 12a.

The guide slits 12b and 12c formed in the light amount adjusting member 12 and the guide slits 13b and 13c formed in the light amount adjusting member 13
The rack gear 10 is formed only on the side where the rack gear 10 is located when the rack gears 2 and 13 are opened. This is because the light amount adjusting members 12, 1
The third cams 12a and 13a are related to the fact that the cam displacement (cam lift) increases as the light amount adjusting members 12 and 13 approach the opening. That is, as the cam displacement (cam lift) increases, the movement of the light amount adjusting members 12 and 13 becomes unstable, which affects the straightness of the light amount adjusting members 12 and 13.

Therefore, the guide slit 12 is located on the side where the cam displacement (cam lift) of the cams 12a and 13a is large.
By providing b, 12c and the guide slits 13b, 13c, the rectilinearity of the light amount adjusting members 12, 13 is prevented from being deteriorated.

In the conventional light amount adjusting device, guide slits are provided on both sides of the aperture opening. In the present embodiment, stable operation can be realized only by providing the guide slit only on one side of the aperture opening, and the width can be reduced. The size can be reduced in the direction.

In the above configuration, the stepping motor 1
When a drive pulse is applied to the motor, the output shaft 1a of the stepping motor 1 rotates together with the pinion gear 2.

The gear 3 meshing with the pinion gear 2 is decelerated at the ratio of the number of teeth, and rotates the feed screw 4. When the feed screw 4 rotates, the rack gear 10 meshing with the threaded portion of the feed screw 4 becomes a guide hole 11a of the base plate 11.
The vehicle is guided to move straight.

The guide hole 11 provided in the base plate 11 as described above
By guiding the moving direction of the rack gear 10 by a, a dedicated guide member is not required.

FIGS. 9 to 14 show a light amount adjusting device according to a second embodiment of the present invention.

Only the points different from the first embodiment will be described, and the same parts as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

The difference from the first embodiment is the position of the guide slits formed in the light amount adjusting members 12 and 13. In the light amount adjusting device of the second embodiment, the light amount adjusting members 12 and 13 have guide slits 12d and 12d, respectively.
12e and 13d, 13e are formed. The guide slits 12b and 13b engage with guide pins 11d provided on the base plate 11, and the guide slits 12e and 13e
Are engaged with guide pins 11e provided on the base plate 11. Therefore, the light amount adjusting members 12 and 13 are movably held in the direction in which the guide slit is formed.

The guide slits 12d and 12e formed in the light amount adjusting member 12 and the guide slits 13d and 13e formed in the light amount adjusting member 13
The racks 2 and 13 are formed only on the side where the rack gear 10 is located when the opening 11f of the main plate 11 is closed (fully closed state).

This is because the cam 1 of the light amount adjusting members 12 and 13
2a and 13a relate to the requirement that more stable and accurate operation is required as the light amount adjusting members 12 and 13 approach the small aperture.

That is, even if the cam lift as described above is moderated, the light amount adjusting members 12 and
There is a risk that the light quantity will greatly change even if a slight shift occurs in the light emitting element 13. Therefore, the light amount adjusting members 12, 1
In order to prevent the movement of 3 from becoming unstable on the small aperture side, a guide slit is formed only on the side where the rack gear 10 is located when the light amount adjusting members 12 and 13 are fully closed.

In the second embodiment, with such a configuration, the movement of the light amount adjusting members 12 and 13 does not become unstable particularly on the small aperture side where accuracy is required, and
Compared with the conventional light amount adjusting device, the size of the light amount adjusting device can be further reduced in the width direction.

In the above-described configuration, an embodiment using a stepping motor as a driving source has been described, but the present invention is not limited to this. Other driving sources such as a DC motor and an ultrasonic motor may be used as long as the actuator can be electrically controlled to stop and rotate.

In this embodiment, the rack gear 10b
Although the photointerrupter 7 is used as the detecting element, the same applies to a magnetic detecting element such as a Hall element or an MR element or a mechanical detecting means such as a brush or a switch.

Further, the object to be detected need not be limited to the rack gear 10, and the positions of the light amount adjusting members 12, 13 may be detected.

[0055]

According to the first aspect of the present invention, there is provided a light amount adjusting device for adjusting a light amount of a passing light beam by moving a light amount adjusting member in an opposite direction using a motor as a driving source. A non-linear cam groove is formed, and the cam groove is driven by the motor so that a moving member that moves in a direction perpendicular to the moving direction of the light amount adjusting member engages, thereby forming a light amount adjusting member. Can be driven at a variable speed, and the driving speed of the light amount adjusting member can be appropriately set according to the shape of the cam groove.

According to a second aspect of the present invention, there is provided a motor, a feed screw rotationally driven by the motor, a rack which is screwed with the feed screw and moves linearly, and a non-linear cam which engages with the rack. A groove is formed, and by having a light amount adjusting member that adjusts the light amount of the passing light beam by moving in a direction perpendicular to the moving direction of the rack, it becomes possible to drive the light amount adjusting member at a variable speed. The drive speed of the light amount adjusting member can be appropriately set according to the shape of the cam groove.

According to a third aspect of the present invention, a motor, a moving member driven by the motor, and a cam groove engaged with the moving member are formed, and the moving member moves in a direction perpendicular to the moving direction of the moving member. A light amount adjusting member that adjusts the light amount of the passing light beam by performing a setting so that the cam displacement of the cam groove increases as the light amount adjusting member moves from the small aperture state to the open state. As the adjusting member moves from the small-aperture state to the open state, the moving speed of the light-amount adjusting member can be set so as to be faster. The light amount can be adjusted.

According to a fourth aspect of the present invention, a motor, a feed screw rotationally driven by the motor, a rack which is screwed with the feed screw and linearly moves, and a cam groove which engages with the rack are provided. And a light amount adjusting member that adjusts the light amount of the passing light beam by moving in a direction orthogonal to the moving direction of the rack, and the cam is moved as the light amount adjusting member moves from the small aperture state to the open state. By setting the cam displacement of the groove to be large, the moving speed of the light amount adjusting member can be set to increase as the light amount adjusting member moves from the small aperture state to the open state. High-precision light quantity adjustment is possible on the aperture side, and high-speed light quantity adjustment is possible on the open side.

According to a fifth aspect of the present invention, in addition to the third or fourth aspect, the cam displacement of the cam groove is set to be zero as the light amount adjusting member approaches an open state. Thus, when the light amount adjusting member is opened, the light amount adjusting member can be stably stopped.

According to a sixth aspect of the present invention, a motor, a moving member driven by the motor, and a cam groove engaged with the moving member are formed, and the moving member moves in a direction orthogonal to the moving direction of the moving member. And a light amount adjusting member that adjusts the light amount of the passing light beam, and the cam displacement of the cam groove is
By setting the value to 0 as the position approaches the end of the cam groove, the light amount adjusting member can be stopped stably.

According to a seventh aspect of the present invention, a motor, a feed screw rotated by the motor, a rack which is screwed with the feed screw and moves linearly, and a cam groove which engages with the rack are provided. And a light amount adjusting member that adjusts the light amount of the passing light beam by moving in a direction perpendicular to the moving direction of the rack, and the cam displacement of the cam groove becomes zero as approaching the end. By being set, the light amount adjusting member can be stopped stably.

[0062] The invention described in claim 8 is based on claim 2,
In addition to the invention described in 4 or 7, the feed screw is arranged in parallel with the output shaft of the motor, so that a sufficient movement stroke of the rack can be secured without increasing the size of the device.

According to a ninth aspect of the present invention, in addition to the first aspect of the present invention, the motor is a stepping motor, so that digital control of the light amount adjusting device becomes possible.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view illustrating a light amount adjusting device according to a first embodiment of the present invention.

FIG. 2 is a diagram of the light amount adjusting device shown in FIG. 1 as viewed from above.

FIG. 3 is a diagram of the light amount adjusting device illustrated in FIG. 1 as viewed from a lower surface side.

FIG. 4 is a sectional view of the light amount adjusting device shown in FIG. 1;

FIG. 5 is a view for explaining changes in the aperture of the light amount adjusting device shown in FIG. 1;

FIG. 6 is a view for explaining a change in an aperture of the light amount adjusting device shown in FIG. 1;

FIG. 7 is a diagram illustrating a change in the aperture of the light amount adjusting device shown in FIG. 1;

FIG. 8 is a view for explaining cam displacement (cam lift) of a cam 12a of the light amount adjusting member 12.

FIG. 9 is an exploded perspective view illustrating a light amount adjusting device according to a second embodiment of the present invention.

10 is a view of the light amount adjusting device shown in FIG. 9 as viewed from above.

11 is a view of the light amount adjusting device shown in FIG. 9 as viewed from the lower surface side.

FIG. 12 is a diagram illustrating a change in the aperture of the light amount adjusting device illustrated in FIG. 9;

FIG. 13 is a view for explaining changes in the aperture of the light amount adjusting device shown in FIG. 9;

FIG. 14 is a view for explaining changes in the aperture of the light amount adjusting device shown in FIG. 9;

FIG. 15 is an exploded perspective view of a light amount adjusting device showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stepping motor 2 Pinion gear 3 Gear 4 Feed screw 7 Photointerrupter 7a Detection gap 10 Rack gear 10a Light shielding part 10c Drive pin 11 Ground plate 12 Light amount adjusting member 12a Drive cam 13 Light amount adjusting member 13a Drive cam 14 Press plate

Claims (9)

[Claims] 1. A light amount adjusting device for adjusting a light amount of a passing light beam by moving a light amount adjusting member in opposite directions using a motor as a driving source, wherein a non-linear cam groove is formed in the light amount adjusting member. The cam groove is driven by the motor,
A light amount adjusting device, wherein a moving member that moves in a direction orthogonal to a moving direction of the light amount adjusting member is engaged. 2. A motor, a feed screw that is rotationally driven by the motor, a rack that is screwed with the feed screw and moves linearly, and a non-linear cam groove that engages with the rack is formed. A light amount adjusting member for adjusting the light amount of the passing light beam by moving in a direction perpendicular to the moving direction of the light amount. 3. A motor, a moving member driven by the motor, and a cam groove engaged with the moving member are formed, and are moved in a direction perpendicular to a moving direction of the moving member to thereby make a light amount of a passing light flux. And a light amount adjusting member for adjusting the light amount adjusting member such that the cam displacement of the cam groove increases as the light amount adjusting member moves from the small aperture state to the open state. 4. A motor, a feed screw rotationally driven by the motor, a rack that is screwed with the feed screw and linearly moves, and a cam groove that engages with the rack is formed, and the rack moves. A light amount adjusting member that adjusts the light amount of the passing light beam by moving in a direction perpendicular to the direction, and the cam displacement of the cam groove increases as the light amount adjusting member moves from the small aperture state to the open state. The light amount adjusting device is set as follows. 5. The light amount adjusting device according to claim 3, wherein the cam displacement of the cam groove is set to zero as the light amount adjusting member approaches an open state. 6. A motor, a moving member driven by the motor, and a cam groove engaged with the moving member are formed, and are moved in a direction orthogonal to a moving direction of the moving member to thereby make a light amount of a passing light flux. Wherein the cam displacement of the cam groove is set to zero as it approaches the end of the cam groove. 7. A motor, a feed screw rotationally driven by the motor, a rack which is screwed with the feed screw and linearly moves, and a cam groove which engages with the rack is formed, and the rack moves. A light amount adjusting member that adjusts the amount of light passing therethrough by moving in a direction perpendicular to the direction, wherein the cam displacement of the cam groove is set to 0 as approaching the end. Light quantity control device. 8. The light amount adjusting device according to claim 2, wherein the feed screw is arranged in parallel with an output shaft of the motor. 9. The light amount adjusting device according to claim 1, wherein the motor is a stepping motor.