JPS5948364B2 - lens aperture device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lens aperture device having a manual aperture adjustment mechanism and an automatic aperture adjustment mechanism.

Although the aperture device of the present invention is suitable for television cameras, it is not limited to such applications. Television cameras are equipped with automatic and manual adjustment means for the aperture of the photographic lens, but as a means to automatically adjust the exposure according to the brightness of the subject, a light receiving element is placed inside the lens barrel. , a structure in which the aperture diameter is changed using a signal from the aperture via a galvanometer, etc., and a structure in which the field brightness signal from the image pickup tube in the camera body is fed back to the lens, thereby changing the lens aperture diameter are known. It is being

The latter structure includes one in which a motor is rotated by a feedback signal from the image pickup tube, and the motor drives the aperture blades via an aperture scale ring, and the other is a drive member such as a servometer that drives the aperture blades directly without going through the aperture scale ring. There are devices that move the aperture blades, but in either case, the rotational torque required to drive the aperture blades needs to be extremely small. This is because portable TV cameras are powered by batteries, and it is necessary to minimize power consumption.
This is also due to the need to stop quickly when the aperture reaches the appropriate aperture diameter to prevent overshooting. In consideration of these points, a structure is known in which a knob is provided to rotate the shaft of a servometer for manual aperture adjustment, but in this case, the aperture scales are irregularly spaced, and the aperture scale interval is The disadvantage is that it is very small, inconvenient to operate, and has poor reliability. SUMMARY OF THE INVENTION An object of the present invention is to provide a lens diaphragm device that can form aperture scales at equal intervals for manual aperture adjustment and that can minimize rotational torque for automatic aperture adjustment. do.

That is, in the aperture device of the present invention, for manual aperture adjustment, a cam mechanism is disposed between an aperture scale member and an aperture blade drive member, so that aperture scales can be formed at equal intervals; For automatic aperture adjustment, the aperture blade drive member is directly driven by a drive device such as a servometer that is activated by an electric signal, and a spring that acts on the aperture blade drive member is used when automatic aperture adjustment is activated. It is characterized by removing the biasing force,
For this purpose, the lens diaphragm device according to the present invention includes a cam provided in the lens barrel of a photographic lens and moved by an aperture scale member, a cam driven member moved by the cam, an aperture blade drive member, and the cam driven by the cam. a spring that biases the aperture blade drive member in one direction; an interlocking member that transmits the movement of the cam driven member to the aperture blade drive member to move the aperture blade drive member against the biasing force of the spring; The aperture blade drive member includes a means for separating the spring from the aperture blade drive member to free the aperture blade drive member, and an automatic aperture adjustment device that drives the aperture blade drive member using an electric signal. The automatic diaphragm adjustment device may be configured to drive the diaphragm blade drive member via an interlocking member, and the disconnection means is formed on a cam member provided with a cam, and the disconnection means is formed on a cam member provided with a cam so as to move the cam in the direction in which the cam separates from engagement with the cam driven member. Preferably, the spring is disconnected when the spring is moved. Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
A pin on the aperture blade drive ring 1, which is pivotally mounted at one end and rotatably mounted inside the fixed ring, engages with the slot of the aperture blade 2, and the rotation of the drive ring 1 causes the aperture blade to move. 2 is moved to adjust the aperture.

An interlocking pin 3 extending rearward parallel to the optical axis is fixed at one end of the aperture blade drive ring 1, and a lever 3a is provided at the other end of the interlocking pin 3. A cam ring 5 is rotatably provided behind the ring 1, and a cam surface 5a is formed on a part of the inner circumference of the cam ring 5. The cam driven member that engages with the cam surface 5a is a pin 4, and this pin 4 is fixed to an arc-shaped lever 12 whose one end is pivotally connected to the lens barrel by a pin 12a. The lever 12 has a pusher 12b at its free end, and this pusher 12b engages with the interlocking pin 3. A spring 13 is combined with the lever 12, and the cam follower pin 4 is pressed against the cam surface 5a by the spring 13. A pin 9 extending further rearward is implanted in the aperture blade drive ring 1, and a spring 10 engages with this pin 9 to urge the ring 1 in one direction. The biasing direction of the spring 10 is the direction in which the interlocking pin 3 is pressed against the pusher 12b of the lever 12. A protrusion 5b is provided on the outer periphery of the cam ring 5.
is formed, and this protrusion 5b fits into a recess 14a on the inner circumference of the aperture scale ring 14.

Therefore, by rotating the aperture scale ring 14, the cam ring 5 rotates, and the cam follower pin 4 moves to the cam surface 5a.
The movement is transmitted from the lever 12 via the interlocking pin 3 to the aperture blade drive ring 1 for manual adjustment of the aperture. Lever 3 provided at the end of interlocking pin 3
A slot is formed in a, and a pin installed in the output lever 6 of the servometer T is engaged with this slot.

As shown in FIG.
This circuit 19 is adapted to receive electrical signals sent from the image pickup tube IT behind the lens 16 via the video signal processing circuit 18. 21 is a resistor for video level adjustment.

Therefore, the output lever 6 of the servometer T is rotated by an angle proportional to the electric signal according to the field brightness, and this rotation is transmitted from the interlocking pin 3 to the aperture blade drive ring 1 to rotate the aperture. Perform automatic adjustment. As shown in FIGS. 1 and 2, the switch 8 is connected to the aperture scale ring 14.
The ring 14 has a recess 14b corresponding to the operating arm of the switch 8, and the aperture scale ring 14 is moved from the position shown in FIG. 1 to the auto position shown in FIG. At this time, the operating arm of the switch 8 engages with this recess 14b, the switch 8 is closed, the servometer T is activated, and the diaphragm is automatically adjusted.
A disconnection lever 11 is attached close to the inner circumference of the cam ring 5 so as to be able to swing around a shaft 11c.
1 has a bending pawl 11a at one end for engaging the spring 10.
is formed.

A protrusion 5c is formed on the inner periphery of the cam ring 5, and this protrusion 5c engages with the end 11b of the lever 11 to rotate the lever 11 when the aperture scale ring 14 is moved to the auto position. To this end, the pawl 11a of the lever 11 engages the spring 10 and deflects it out of engagement with the pin 9 on the aperture drive ring 1. Therefore, in the auto position, the aperture blade 1 drive ring 1 is in a state where it can freely rotate, and the load applied to the servometer 7 becomes very small. As explained above, in the present invention, manual adjustment of the lens aperture is performed via the cam mechanism, so the aperture scale can be formed at equal intervals, and automatic adjustment is performed by the aperture blade drive member without using the cam mechanism. Since the spring biasing force applied directly to the aperture blade drive member during automatic adjustment is removed, the torque for rotating the aperture blade drive member can be significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing an embodiment of the lens aperture adjustment device of the present invention in the manual adjustment position, Fig. 2 is an exploded perspective view showing it in the auto position, and Fig. 3 is a system diagram showing the arrangement of the automatic adjustment device. It is. 1... Aperture blade 1 drive ring, 3...
Interlocking pin, 5...Cam ring, 7...
Servometer, 10... Spring, 11...
- Separation lever, 14... Aperture scale ring.

Claims (1)

[Scope of Claims] 1. A cam that is provided on a lens barrel of a photographic lens and is moved by an aperture scale member that has graduations at approximately equal intervals, a cam driven member that is moved by the cam, an aperture blade drive member, and the aperture blades. a spring that biases the drive member in one direction; an interlocking member that transmits the movement of the cam driven member to the aperture blade drive member to move the aperture blade drive member against the biasing force of the spring; and automatic aperture adjustment. A diaphragm device for a lens comprising: a disconnection means that separates the spring from the diaphragm blade drive member during operation to free the diaphragm blade drive member; and an automatic diaphragm adjustment device that drives the diaphragm blade drive member by an electric signal. 2. In the above item 1, the automatic aperture adjustment device is a lens aperture device configured to drive the aperture blade drive member via the interlocking member. 3. In the above item 1 or 2, the separating means is provided on a member having a lever that acts on the spring to separate the spring from the aperture blade drive member and the cam, and the cam is disposed in engagement with the cam driven member. a lens diaphragm device comprising a projection that engages the lever and moves it in the direction of spring separation when the lever is moved away from the spring. 4 In the above item 3, the cam is provided on the inner circumferential surface of a ring member that interlocks with the aperture scale member, and the cam driven member includes an axial pin that contacts the cam and an arcuate swinging member that integrally supports the pin. A lens aperture device consisting of a lever. 5. The lens diaphragm device according to item 4, wherein the projection for operating the spring separation lever is formed on the inner circumferential surface of the ring member. 6. The lens aperture device according to item 4, wherein the interlocking member is a pin extending in the axial direction from the aperture blade drive member, and the swing lever has its free end engaged with the pin.