JPH02187737A - Iris controller - Google Patents

Abstract

PURPOSE:To form a stably locking state by controlling the revolution of a motor based on the information of an angle position of a motor for the iris in a rocking state. CONSTITUTION:When the iris is locked, a memory circuit 29 is stopped from memorizing at the same time switching circuits 22 and 24 are turned on, whereby, the inversion terminal of a differential amplifier 23 is supplied with an output detected when the iris is locked, and non-inversion terminal is supplied with a detected output according to the rotary angle of the motor 10. And then, the revolution of the motor 10 is controlled by the differential amplifier 23 so that the detected output which is supplied to its non-terminal is converged to the detected output which is supplied to the inversion terminal. The motor 10 can be thus controlled with a closed loop, and therefore, the motor 10 can rapidly and correctly be returned into the original condition when it is accidently turned by shock, and a stably locked iris can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an iris control device used in various cameras.

(Prior Art) Generally, various cameras such as video cameras have COD
An additional iris control mechanism is installed to limit the amount of imaging light that enters the image sensor (charge-coupled device) or film from the subject, allowing for optimal exposure. ing.

This iris control device d is installed, for example, in front of the above COD! The iris blades arranged between the zoom lens and the master lens, which constitute the optical system for guiding the imaging light to this COD, should be driven. The iris drive mechanism is generally configured to include an iris drive mechanism that opens and closes the iris.The iris drive mechanism can be driven manually or a meter, which is the drive source of the iris drive mechanism, can be driven to rotate. By opening and closing the optical path using the blades, the incidence of the silver image light on the COD is restricted.

Generally, the motor in such an iris control device is one that rotates within a predetermined angle range, and the rotation angle is set and controlled according to the supplied illumination current. At the same time, the iris blades are opened and closed according to the rotation angle.

By the way, in general, when photographing a specific subject such as a person, or when the brightness of the subject changes frequently during photographing, the iris blades in the iris control device as described above are usually Photographing is performed with the iris fixed, that is, with the iris closed.

Here, as a conventional means for performing such an iris lock, a method in which the iris blades are directly locked with a single lock member has generally been used. .

However, while it has the advantage of being able to securely lock the iris (411) when performing one lock using the locking member, it does not require an independent mechanism to lock the iris (411). This has the drawback of hindering the miniaturization and weight reduction of the iris control device, which in turn hinders the miniaturization and eave size of the camera.

Therefore, conventionally, one iris can be electrically operated by controlling the drive power supplied to the iris drive mechanism without installing a locking member as described in 1). There are suggestions for what to do.

For example, when the iris is locked, the voltage level of the drive current supplied to the motor is held by a capacitor or the like, and the iris is -11 [! when locked] It is known that the iris blade is fixed by stopping the iris blade at a rotational position corresponding to the voltage level held by the =1 capacitor.

(Problem to be Solved by the Invention) By the way, in the above-mentioned device that electrically locks the iris, the motor may be inadvertently rotated due to shocks such as camera vibrations after the iris is locked. It may move.

Here, in the conventional iris control device as described above, the rotation angle of the motor is controlled only by the voltage level held in the capacitor -h, regardless of the rotation of the motor. Due to the oven loop control, it is not possible to accurately and quickly restore the rotational angle position of the motor that has rotated carelessly to its original state, making it impossible to obtain a stable l-cock condition. There is.

In addition, the conventional iris 1. In the control device, as the capacitor discharges, there is a risk that the previously held voltage level may change little by little.
Also from this point of view, it is not possible to obtain a stable locked state for a long time.

In addition, when adjusting the iris by manual operation after cocking the iris, for example, by operating a variable resistor, etc., and varying the voltage level held in the capacitor, the iris adjustment can be done in an analog manner. However, such an analysis [according to the standard H method, the standard for adjusting the iris by 1J, which corresponds to the F value of the camera, is the sense that the operation is too large, or sometimes...] It will be different.

(Means for Solving the Problems) The present invention has been made in view of the above-mentioned circumstances, and it is possible to stabilize the lock state and set a standard for iris adjustment after the iris is locked. The purpose of the present invention is to provide an iris control device that can control the iris.

In order to achieve this objective, the present invention performs automatic iris control by driving an iris adjustment motor according to the brightness of the subject, and also performs iris lock by locking the aperture diameter of the iris blades. An iris control device, comprising a corner position detection means for detecting the rotational angular position of the motor, and a memory means for storing the detection output of the angular position detection means immediately before the iris lock, and the iris control device is provided with In this case, the level difference between the detection output of the angular position detection means (1) and the detection output immediately before the iris lock stored in the memory means is detected, and the detection output of the angular position detection means is stored in the memory means (G). C
To lock the iris feathers! li! an iris control device with the same characteristics as above, and an A/D converter in the iris control device as described above, which digitalizes the detection output of the angular position detection means; and an A/D converter that digitalizes the memory value of the memory means. An object of the present invention is to provide an iris control device characterized by having a variable means for changing the iris.

(Embodiment) Hereinafter, a preferred embodiment of the iris control device according to the present invention will be explained in detail with reference to FIGS. 1 to 3.

This embodiment applies the present invention to a video camera, and FIG. 1 is a block diagram showing an electrical 4T configuration of an iris control circuit constituting an iris control device according to this embodiment.
FIG. 2 is a side sectional view of the iris drive mechanism that also constitutes the iris control device.

This iris lit! As shown in FIG. 2, the lm device is incorporated into the optical system of a video camera, which consists of a focusing lens 1, a variable magnification lens 2, a correction lens 3, and a pair of imaging lenses 4 and 5. , the imaging light from the subject is incident on the CCD 6 via the optical system.

A plurality of (for example, five) iris blades 7 constituting the iris control device are disposed between the pair of imaging lenses 4.5, and these iris blades 7 are operated to open and close. The amount of imaging light directed to the CCD 6 is adjusted by.

The iris blades 7 are supported by an iris drive mechanism shown in FIG. 2 to open and close.

That is, each of the iris blades 7 is arranged between a pair of mounting plates 8.9 facing each other at a predetermined interval, and these iris blades 7 are connected to a drive plate 11 which is rotatably driven by a motor 10, which will be described later. It is designed to open and close in conjunction with the

Incidentally, such opening/closing operation of the iris blade 7 uses a general cam mechanism, and this cam mechanism is described in detail in, for example, Japanese Patent Publication No. 60-70426.

The motor 10 is configured to include a magnet 12 provided on the rotor side and a driving coil 13 placed on the stator side. The magnet 12 is rotated within a predetermined angular range D.

A disc-shaped link member 15 is attached to the drive shaft 14 of the motor 10 (=J't-J), and the link member 15 engages with the drive plate 11 at an eccentric position to rotate the motor 10. pin 1 that transmits the rotational force of to this drive plate 11
6 is provided. .

Furthermore, a torsion spring 17 is fitted into the drive shaft 14, and this torsion spring 17 is connected to the link part @
The iris blade 7 is always urged in the closed direction via the drive unit 15 and the drive unit 11.

Further, on the stator side of this motor 10, a Hall element 18 facing the magnets 1 to 12 is arranged,
The output of this Hall element 18 changes depending on the rotation angle of the magnet 12.

As a result, in this embodiment, this Hall element 18
In order to detect the output of the motor 10,
- The rotation angle on the evening side, that is, the aperture diameter of the iris blade 70 can be detected.

・On the other hand, the iris blades 7, which are like two series, can be operated by an iris control circuit as shown in FIG. Opening/closing is controlled by controlling the rotation 91 of 10 (-).

In this iris control circuit, the video signal supplied from the C (low) 6 to the signal processing circuit 20 is extracted from the video signal by the signal processing circuit 20, and this brightness signal is used for the iris in the auto iris state. It is supplied to the input terminal 21 as a signal used for υ control.

The supplied luminance signal is then passed through one terminal and the movable terminal of the first switch circuit 22 to the differential amplifier 23.
is supplied to the non-inverting terminal of

Further, an N quasi-signal is supplied to the inverting terminal of the differential amplifier 23 through one terminal and a movable terminal of the second switch circuit 24, and this 1J quasi-signal is set to a predetermined value by adjusting the variable resistor 25. It is now preset to .

Thereby, the differential amplifier 23 uses a differential output corresponding to the difference between the luminance signal and the reference signal supplied to each terminal as a control current to drive the motor 10 through the drive circuit 39.
When the subject becomes bright, the iris blades 7 are closed, and when the subject becomes dark, the iris blades 7 are opened.

Preferably, the rotation angle of this shutter 10 is the same as that of the 12-hole element 1.
The detection output of this Hall element 18 is amplified to a predetermined level by an amplifier 26 and supplied to an A/D (analog-digital) converter 27 that constitutes a control system that maintains the iris lock state. be done.

This digitized detection output is supplied to a delay circuit 28 and a memory circuit 29, respectively, and the detection outputs supplied to each circuit 28 and 29 are sequentially output in synchronization with 1γ.

The memory circuit 29 memorizes the supplied detection output and immediately outputs it, and the delay circuit 28 delays the detection output Wffi for a time corresponding to the memory operation of the memory circuit 29, thereby delaying each circuit. The outputs of 28 and 29 are synchronized.

The detection output is output from each of these circuits 28 and 29, and the detection output is output from the D/A (digital-to-analog) converter 3.
0.31 and converted into analog signals, and the detection output outputted from the Mannobu circuit 28 is supplied to the other terminal of the first switch circuit 22, and the memory circuit 29 described in -
The detection output output from the second switch circuit 24
is supplied to the other terminal of .

Here, switching of these switch circuits 22 and 24 is performed by suppressing the lock switch 32, and by pressing the lock switch 32 on this day, the iris control circuit is set from the auto iris state to the iris lock state. The movable contacts of each of the switch circuits 22, 24 are switched from one terminal to the other terminal.

Therefore, after the iris is locked, each detection output supplied to each of the switch circuits 22 and 24 is supplied to the non-inverting terminal and the inverting terminal of the differential amplifier 23, respectively. ing.

Further, by suppressing the lock switch 32, the memory operation of the memory circuit 29 is stopped. 1. Therefore, the detection output supplied to the inverting terminal of the differential amplifier 23 is generated immediately before the switch 32 is pressed.
In other words, it is the detection output immediately before the iris is locked, and the differential amplifier 23 outputs the detection output immediately before the iris goes into the 0-lock state, and the output that is supplied via the delay circuit 28 after the iris is turned on. A differential output is supplied to the motor 10 according to the difference between the detected output and the detected output.

Further, the metering circuit 29 has a j7 circuit whose operation is controlled by an up switch 33 and a down switch 34.
It is variably controlled by a knob down counter 35, and by operating each of the switches 33 and 34, the F value in the iris lock state can be variably set.

In this embodiment, the detection output is digitized and stored in memory, and the digital values are digitally varied by the switches 33 and 34.
In addition to being able to correctly recognize the variable F value, there is no perceptual variation that occurs with manual operation, and the iris control device can be accurately set to the desired F value. can.

Further, in this embodiment, the voltage level of the reference signal in the O1 to Iris states can be variably controlled by the sensitivity setting circuit 38 whose operation is controlled by the up switch 36 and the down switch 37. Sensitivity can be adjusted from +n to - by operating each switch 36 and 37.
can be varied over n.

That is, by pressing each of the switches 36 and 37, a correction voltage that changes as shown by the solid line and the dashed line in FIG. 3 is applied to the reference signal, thereby causing the iris blade 7 to It is possible to variably set the sensitivity by opening and closing the reference aperture diameter.

Here, in the iris drive mechanism as shown in FIG. 2 described above, the iris blade 7 is opened and closed by mechanical means, and a torsion spring 17 is provided that always biases the iris blade 7 in the closing direction. Therefore, a mechanistic hysteresis exists.

Therefore, as shown in FIG. 3, the sensitivity setting circuit 38
When changing the sensitivity by
If the change curve of the correction voltage when the voltage is varied is the same curve as shown by the solid line in the figure, even though the same correction voltage is applied, the change from ``n'' to ``-n'' is the same. The reference aperture diameter when changing from -n to 4-n is different.

Therefore, in the iris control device according to this embodiment,
The change curve of the sleeve voltage changing from t') to -r) is shown by the dotted chain line in Figure 3, and the correction data corrects the mechanical hysteresis. This curve is set to be different from the correction voltage change curve shown by the solid line in the figure when the sensitivity is varied from +n to -n.

In addition, J, each switch above even if the sensitivity is the same 3
The above mechanical hysteresis is compensated for by varying the level of the correction voltage depending on whether the sensitivity is changed by 637, that is, whether the sensitivity is increased or decreased. The opening diameter can be set as the opening diameter.

In the iris control device as described above, in the case of the O1 to iris states, the luminance signal and the reference signal are supplied to each terminal of the differential amplifier 23 from the first and second switch circuits 22 and 24, respectively. , this differential amplifier 23 supplies the differential output of these signals to the recorder 10 as a control signal, and variably controls the aperture diameter of the iris blade 7 according to the brightness of the subject.

As a result, the luminance signal level during the video image obtained by dancing can be kept constant.

Furthermore, in this auto-iris state, the sensitivity of this iris control device can be variably set by pressing each of the switches 36 and 37 as appropriate.

On the other hand, when the iris lock state is established, the first and second switch circuits 2224 are switched and the metering operation of the memory circuit 29 is stopped. The detection output when the iris is locked is supplied to the inversion terminal, and the detection output corresponding to the rotation angle of the motor 10 is supplied to the non-inversion terminal.

Then, the differential amplifier 23 rotationally controls the motor 10 so that the detection output supplied to its actual rotation terminal converges to the detection output supplied to its inversion terminal.

Therefore, even if the motor 10 is inadvertently rotated due to an 11i strike or the like after the iris is locked, the rotation angle of the motor 10 can be returned to the rotation angle when the iris was turned [1].

Here, in this embodiment, after the above-mentioned iris lock time rotation, the motor 10 can be controlled in a closed loop based on the information on the rotation angle position of the motor 10 according to V. Theta 10 can be quickly and accurately returned to its original state by inadvertently rotating with y/), and a stable locked state can be obtained.

In addition, in this embodiment, the detection output is digitized and stored in memory, and the digital values are varied in stages by the switches 33 and 34.
It is possible to correctly recognize the variably set F value, and also to accurately set the desired F value.

Here, according to this embodiment, since it is possible to set the f-number accurately in this way, the information on the F value can also be used as information for varying the shutter speed.

The iris control device according to the present invention includes the A/D converter 27, the delay circuit 28, the metric circuit 29, the D/Δ converter 30. 31 and up/down counter 35 may be built into a single-chip IC (integrated circuit). In such a case, these circuits can be locked only when the iris is locked by operating the lock switch 32. Power saving can be achieved by driving the motor.

In addition, in the first embodiment, the memory circuit 29 was particularly used as the memory means, but the number of circuit components can be reduced by configuring the memory function of the D/A converter 31 to be utilized. be able to.

(Effects of the Invention) As is clear from the above description, according to the present invention, the rotation of the iris motor is controlled based on information about the angular position of the iris motor when the iris is in the closed state. S Toni,
Closed loop control of the motor can be realized even when the iris I is turned on.

As a result, even if the C1 -1- motor were to be rotated unnecessarily due to an object, etc., it would be possible to quickly and accurately return to the state before rotation, and the iris lock. In addition, there is no problem such as the change in the rack state over time due to the capacitor's tli voltage, as in the conventional case.

Furthermore, according to the present invention, the detection output of the angular position detection means is converted into f-digits and stored in memory, and this memory value is digitally varied as necessary, thereby establishing a standard standard for iris adjustment. This makes it possible to more accurately set Fl in the iris lock state.

[Brief explanation of the drawing]

FIG. 1 shows the electrical configuration of the iris control circuit constituting the iris control device according to the present invention.
The figure is a side cross-sectional view of the iris drive mechanism constituting the iris control device, and FIG. 3 is a graph showing the correction voltage when setting the sensitivity. 7...Iris blade, 10...Motor, 18...
Hall element (angular position detection means), 23... differential amplifier, 27... A/D converter, 29... memory circuit (
35... up/down counter. 2. Patent applicant: Kakimoto, representative of Victor Japan Co., Ltd.
Kunio Figure 2

Claims (2)

[Claims] (1) An iris control device that performs automatic iris control by driving an iris adjustment motor according to the brightness of the subject, and also performs iris lock by locking the aperture diameter of the iris blades, which angular position detection means for detecting the angular position, and memory means for storing the detection output of the angular position detection means immediately before the iris lock, and when the iris is locked, the detection output of the angular position detection means and the above A level difference between the detection output immediately before the iris lock stored in the memory means is detected, and the motor is operated so that the detection output of the angular position detection means converges to the detection output immediately before the iris lock stored in the memory means. An iris control device characterized by controlling drive and locking iris blades. (2) The iris according to claim 1, further comprising: an A/D converter for digitizing the detection output of the angular position detection means; and variable means for digitally varying the memory value of the memory means. Control device.