JP3236155B2 - Aperture device and optical equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm device and an optical apparatus.

[0002]

2. Description of the Related Art As shown in FIG. 7, a conventional diaphragm device for a video lens controls the rotation of a motor 101 whose rotor shaft is rotated by a driving voltage by an arm (not shown).
In general, the control signal is transmitted to the control unit 02 to drive and control the aperture blade 102. The rotation amount (rotation angle) of the rotor shaft of the motor 101 is configured to change linearly with a change in the drive voltage.

[0003]

However, in the above-mentioned conventional example, the motor 101 for driving the aperture blades protrudes largely outside the lens barrel, which is an obstacle to downsizing. .

The amount of rotation (rotation angle) of the rotor shaft is
Since it changes with the change in the drive voltage, there has been a problem in accuracy due to the change in the power supply voltage.

[0005]

According to the present invention, there is provided a diaphragm blade having a resistor provided on an insulating film, a blade support having electrodes capable of switching polarities arranged at predetermined intervals on the insulating support , Position detecting means for detecting a predetermined position of the aperture blade
And the detection information of the predetermined position from the position detection means.
By controlling the switching of the polarity of the electrodes based on the above, it is possible to reduce the size of the aperture device and to enable digital control of the aperture device.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. Japanese Patent Laid-Open No. 13390/1992 discloses an electrostatic film actuator composed of a movable member having a resistor provided on an insulating film and a stator having electrodes capable of switching the polarity arranged on an insulating support.
The principle is described with reference to FIG. 4 and the like, with reference to FIG.

FIGS. 4 (a) to 4 (d) are explanatory diagrams of the operation principle of the above-mentioned electrostatic film actuator.
1 is an insulating support, 2 is a strip electrode, 3 is a stator, 4 is an insulating film, 5 is a resistor, 6 is a mover, and 7 to 9 are electric wires.

First, as shown in FIG. 4A, a positive voltage is applied to the electric wire 7 and a negative voltage is applied to the electric wire 8. As a result, a current flows through the resistor 5 due to the potential difference between the electric charge existing at the electrode connected to the electric wire 7 and the electric charge existing at the electrode connected to the electric wire 8,
A band-like charge is induced at the boundary between the insulating film 4 of the movable element 6 and the resistor 5 to form an equilibrium body.

The above-mentioned band-like charges can be replaced by mirror image charges shown by dotted lines in FIG. Since the polarities of the charges are different from the polarities of the electrodes, respectively, the stator 3 and the mover 6 attract each other in the state of FIG. 4B.

Next, as shown in FIG. 4C, a negative voltage is applied to the electric wire 7, a positive voltage is applied to the electric wire 8, and a negative voltage is applied to the electric wire 9. As a result, the charges in the electrodes move instantaneously, but the mirror image charges induced in the resistor 5 cannot move immediately because of their high resistance. As a result, the stator 3 and the mover 6 repel each other, float only at the moment when the mover 6 moves, and the friction between the stator 3 and the mover 6 decreases. On the other hand, as a result of applying a negative voltage to the electric wire 9, the moving element 6 moves by one electrode pitch due to the force between the electric charge and the band-like electric charge.

FIG. 4 (d) shows the result of a rightward movement of one electrode pitch by the above driving force.

By repeating the above operation, the moving element 6 continuously moves to the right. When moving the wire 9 to the left, a positive voltage may be applied to the electric wire 9 in FIG.

Next, an embodiment of the present invention will be described with reference to FIGS. The aperture device of the present invention is a device in which the moving element of the electrostatic film actuator described above is used as aperture blades, the stator is configured as a blade support, and the aperture device is formed by combining a plurality of aperture blades and the blade support. is there.

FIG. 1 is a cross-sectional view of a video lens.
It holds a front lens group L ₁ in the front inner periphery fixed barrel. Reference numeral 22 denotes a rear fixed cylinder, which is integrated with the fixed cylinder 21 to form a video lens VL. 23 is a first lens movement frame holds the zoom lens group L _2, is movably supported along the optical axis (not shown) of the guide bar.

Reference numeral 24 denotes a first blade support, which supports the first aperture blade 25. Reference numeral 26 denotes a second blade support, which supports the second aperture blade 27. First blade support 24, second blade support 26, first aperture blade 2
5. The diaphragm device D is constituted by the second diaphragm blade 27 and housed inside the fixed cylinder 21.

Reference numeral 28 denotes an afocal lens frame, which holds the afocal lens unit L ₃ on the inner periphery thereof and is fixed between the fixed cylinder 21 and the rear fixed cylinder 22. 29 is a second lens movement frame, it holds a relay lens group L _4, first
Are supported movably in the optical axis direction by the guide bar 30 and the second guide bar 31. Reference numeral 32 denotes a rack member, which is supported so as to move integrally with the second lens moving frame 29 in the direction along the optical axis, and is configured so that the output shaft of the stepping motor 34 is sandwiched by the force of a spring 33. 37
Is an image sensor.

Next, a schematic configuration of a main part of a video camera having the above-described aperture device D will be described with reference to a block diagram of FIG.

The image pickup light from the subject incident from the video lens VL forms an image on the image pickup surface of the image pickup element 51 after the light amount is adjusted by the diaphragm device D. The subject image formed on the image sensor 51 is photoelectrically converted here and output to the camera signal processing circuit 52 as an image signal. In the camera signal processing circuit 52, processing such as γ (gamma) conversion is performed.
The color signal C and the luminance signal Yγ are extracted as a video signal. This video signal is output to the outside by the camera unit in the form of a composite video signal or the like via an NTSC type camera encoder 53.

The luminance signal Y output from the camera signal processing circuit 52 is input to a detection circuit 54 for generating a control signal for controlling the diaphragm device D to obtain an appropriate exposure according to the luminance state of the screen. The camera microcomputer 5
5 is taken in. The luminance signal is compared with a reference value (appropriate exposure value) by a comparator 56 in a camera microcomputer 55, and a signal (digital) corresponding to a difference from the appropriate exposure value is sent to a driver 57.

The driver 57 applies a voltage to each of the blade supports 24 and 26 of the aperture device D according to the input signal to drive each of the aperture blades 25 and 27. Also, the camera microcomputer 55 detects how far the aperture is away from the reset position from the information of the photo interrupters 35 and 36 by counting the number of rectangular wave pulses of the output signal.

FIG. 2 is a detailed view of the diaphragm device D as viewed from the optical axis direction. A first blade support 24 is provided in front of the diagram so that the first diaphragm blade 25 can be moved up and down in the figure. ing. The first aperture blade 25 is provided with a protruding portion 25a, and is configured so that the position can be detected by the photo interrupter 35 at a predetermined position. A second blade support 26 is located behind the first blade support 24 and the first aperture blade 25 in the figure, and is configured to move the second aperture blade 27 in the vertical direction in the figure. . Second diaphragm blade 27
Is provided with a protruding portion 27a, so that the photo interrupter 36 can detect the position at a predetermined position. A range (opening area) A surrounded by the first diaphragm blade 25 and the second diaphragm blade 27 is a range effective as a diaphragm diameter.

FIG. 3 is a longitudinal sectional view of a central portion of FIG.
The inside of the blade support 24 is provided with a strip electrode 24a and an electric wire 24.
b, 24c and 24d are arranged. The first diaphragm blade 25 includes an insulating film 25b and a resistor 25c. Inside the second blade support 26, a strip electrode 26 is provided.
a, electric wires 26b, 26c, 26d are arranged. The second diaphragm blade 27 includes an insulating film 27 b and a resistor 27.
c.

The first blade support 24 and the second blade support 26 are made of a light transmissive material, and the electrodes 24a and 26a are made of transparent electrodes.
The electrodes can also be arranged.

In the diaphragm device D configured as described above, the amount of photographing light incident on the image sensor 37 is detected, and the electric wires 24b and 24 of the first blade support 24 are detected in accordance with the amount of photographing light.
The first diaphragm blade 25 is moved by applying three-phase voltages to c and 24d in the same manner as the operation of the electrostatic film actuator described with reference to FIG. At the same time, the second diaphragm blade 27 is moved by applying a three-phase voltage to the electric wires 26b, 26c, 26d of the second blade support 26. The first diaphragm blade 25 and the second diaphragm blade 27 have protrusions 25a and 27a, respectively, and the positions can be detected at predetermined positions by the photo interrupters 35 and 36, so that synchronization can be achieved. By changing the size of the opening area A, it operates as a diaphragm device.

Next, the control operation of the aperture device D will be described with reference to the flowchart of FIG.

First, the diaphragm blade is driven in a reset direction (aperture open) (step 601). Next, it is confirmed whether the reset position has been reached (step 602). If it is the reset position, the driving is stopped (step 603), and the counter is reset (step 604). Then
The camera microcomputer 55 compares whether the current luminance signal (the amount of light input to the image sensor) and the reference value (appropriate exposure value) are the same (step 605), and if they are the same, stops driving (step 610). .

On the other hand. When the luminance signal and the reference value are not the same, a value obtained by subtracting the reference value from the luminance signal is set to S (60).
6) It is determined whether the value of S is greater than 0 (60).
7) If the value is larger than 0, the counter is counted up by the value of S, and the aperture blade is driven in the closing direction by the number of pulses corresponding to the value of S. When the number of pulses corresponding to the value of S exceeds the drive limit of the aperture blade, the aperture blade is driven to the drive limit and the input time of the image sensor is lengthened (60).
8).

On the other hand, when the value of S is smaller than 0, the counter is down-counted by the value of S, and the aperture blade is driven in the open direction by the number of pulses corresponding to the value of S. Also,
If the number of pulses corresponding to the value of S exceeds the drive limit of the diaphragm blade, the diaphragm blade is driven to the drive limit and the input time of the image sensor is shortened (609).

In the above description of the operation, the reset position is set to the open position (fully open position of the aperture). Therefore, when the power of the video camera is turned off, the closed state (fully closed position of the aperture) is protected to protect the CCD. ) Is desirable. When the reset position is set to the close position, after performing the reset operation in the above operation, after driving to the initial position such as the half-open state of the aperture, the current luminance signal is acquired, and the reference value is acquired. It is necessary to make a comparison with

[0030]

As described above, the diaphragm device is constituted by the diaphragm blade provided with the resistor on the insulating film and the blade support in which the electrodes whose polarity can be switched are arranged on the insulating support at predetermined intervals. This makes it possible to reduce the size of the stop device, particularly in the optical axis direction, and by using this stop device, it is possible to reduce the size of optical equipment.

Further, since the drive control of the aperture device can be digitally controlled, a control circuit can be simply constructed and the precision of the aperture device can be improved.

Further, since the diaphragm blades of the diaphragm device are driven by the repulsion of electric charges, the durability of the device can be improved without being affected by friction.

In addition, since at least a portion of the blade support is formed of a light-transmitting member, electrodes can be arranged in the opening region, so that the aperture diameter can be increased without lowering the driving performance.

[Brief description of the drawings]

FIG. 1 is a sectional view of a video lens barrel having an aperture device embodying the present invention.

FIG. 2 is a diagram of the diaphragm device of the present invention as viewed from the optical axis direction.

FIG. 3 is a sectional view of a diaphragm device according to the present invention.

FIG. 4 is a diagram illustrating the operation principle of the electrostatic film actuator.

FIG. 5 is a block diagram of a video camera having an aperture device embodying the present invention.

FIG. 6 is a flowchart illustrating a control operation of a diaphragm device according to the present invention.

FIG. 7 is a cross-sectional view of a video lens barrel equipped with a conventional motorized aperture device.

[Explanation of symbols]

 24 first blade support 25 first aperture blade 26 second blade support 27 second aperture blade 35, 36 photo interrupter

Claims (4)

(57) [Claims] And 1. A throttle blade having a resistor on the insulating film, and the blade support possible electrode switched polarity insulating support arranged at a predetermined interval, for detecting a predetermined position of the diaphragm blades Position detection means
Based on the detection information of the predetermined position from the position detection means.
A switching device for controlling the switching of the polarity of the electrode . 2. The apparatus according to claim 1, wherein at least a part of the blade support is formed of a light transmissive member.
The squeezing device as described. 3. The method according to claim 2, wherein the position detecting unit is configured to move the diaphragm blade.
Characterized in that it is a photo interrupter that detects motion.
The diaphragm device according to claim 1. 4. An optical apparatus having the aperture device according to claim 1.