JPH05161060A - Iris control circuit - Google Patents

Abstract

PURPOSE:To enable the fine adjustment of a video level with a simple configuration by forming an iris control signal based on a high-order bit signal of a signal fed from an input means and a gain control signal based on a low-order bit signal. CONSTITUTION:A microcomputer 11 generates an iris control signal based on a high-order n-bit signal in (n+k) bits (n=1, 2, 3,..., k=1, 2, 3,...) of signals representing an iris rate of an iris 3 fed from a camera controller 18 and gives the signal to an amplifier circuit 14 and a motor 15. Moreover, the microcomputer generates a gain control signal based on a low-order k-bit and gives it to a variable amplifier 6. Thus, a video level of a camera output is fine- adjusted with a simple configuration and an excellent camera output is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iris control apparatus suitable for application to a color video camera such as a so-called three-plate color video camera.

[0002]

2. Description of the Related Art Conventionally, in various video cameras such as so-called three-plate video cameras, an iris for adjusting light from a lens system and an iris control circuit for controlling the iris are used.

In some of such video cameras, an external device such as a camera controller is provided with an input terminal for controlling the opening and closing of the iris.

That is, the operator operates the camera controller connected to this input terminal to control the opening and closing of the iris, thereby setting the video level of the camera output from this video camera to the intended level. ..

As an example, there is a case where the camera output is supplied to a wave form monitor or the like, and adjustment is performed by the camera controller while watching the camera output waveform.

The knob for controlling the iris of this camera controller is connected to, for example, a rotary encoder.

Therefore, when the operator turns the knob, the rotation amount is detected by the rotary encoder, and the detection output is converted into digital data by the camera controller main circuit of the camera controller, which is supplied from the input terminal to the video camera. Is supplied to.

In the video camera, the digital data from the camera controller is converted into an analog signal by the D / A converter, which is used as the drive signal for the motor for driving the iris, and the iris is opened / closed according to this drive signal. To be controlled.

[0009]

By the way, in the video camera as described above, the quantized bits of the DA converter for converting the digital data from the camera controller into the analog drive signal for driving the motor for driving the iris. When the number is coarse, as shown by p2 in FIG.
The F value (brightness index) for the digital data, which is the control data from the camera controller, is not continuous, so that the output level of the camera is also not continuous.

That is, for example, when the number of quantization bits of the D-A converter is n bits and the control data from the camera controller is n + k, the width of ΔF such as p2 shown by the broken line in FIG. 3 is set. It has the characteristics that it has.

Therefore, also at the video level, the output characteristic has a width of ΔF.

That is, even if the camera controller supplies control data with high accuracy to the video camera, it is not possible to finely control the driving of the iris corresponding to the control data.

Therefore, it is sufficient to increase the number of quantization bits of the DA converter as described above, but in that case, there is a disadvantage that the cost increases.

On the other hand, in the iris (iris blade) drive system, a gear 3b is meshed with an iris ring 3c attached to the iris as shown in FIG.
Is connected to the motor 15 via the shaft 3a, and the driving power of the motor 15 is transmitted to the iris ring 3c via the shaft 3a and the gear 3b.

As shown in FIG. 3, the iris ring 3
Play (backlash) in the meshing part of c and gear 3b
There is Δx, and because of this backlash Δx, when the data indicating the direction of control data from the camera controller (iris opening / closing direction) changes, that is, from the iris opening direction to the closing direction or from the closing direction to the opening direction. In addition, the movement of the iris cannot follow quickly.

Therefore, there is an inconvenience that it is very difficult to make an adjustment when finely adjusting the video level.

The present invention has been made in view of the above points, and it is possible to perform a fine adjustment of the video level of the camera output with a simple structure and at low cost, and due to the mechanical backlash that occurs in the iris servo system. The present invention intends to propose an iris control circuit which can prevent a discontinuous change in the video output level and obtain a good camera output.

[0018]

The iris control device of the present invention is, for example, as shown in FIGS. 1 to 4, an iris 3, driving means 14 and 15 for driving the iris 3, and an iris 3.
Image sensor 4 for converting light incident through the light source into an electric signal
And a variable amplifier circuit 6 for amplifying the output signal of the image pickup device 4, and N + K bits (N = K) indicating the open / close ratio of the iris 3.
, 1, 2, 3, ... And K = 1, 2, 3, ...
And an input means 18 for outputting the digital signal, and an iris control signal is formed on the basis of the signal of the upper N bits of the signal supplied from the input means 18 and is supplied to the driving means 14 and 15 and supplied from the input means 18. The control means 11 forms a gain control signal based on the lower K-bit signal of the generated signal and supplies the gain control signal to the variable amplifier circuit 6.

The iris control device of the present invention is shown in FIG.
As shown in FIG. 4, the iris 3, driving means 14 and 15 for driving the iris 3 via gears, and the iris 3
Image sensor 4 for converting light incident through the light source into an electric signal
A variable amplifier circuit 6 for amplifying the output signal of the image pickup device 4, an input means 18 for outputting a signal indicating the open / close ratio of the iris 3, and a storage means for storing correction data having a value corresponding to the backlash of the gear. 11, the detection means 11 for detecting a change in the sign of the increase rate of the signal indicating the opening / closing rate of the iris 3 output from the input means 18, and the opening / closing rate of the iris 3 based on the detection result of this detection means 11. When a change in the sign of the increase rate of the signal is detected, the iris control signal is formed based on the value obtained by adding the correction data to the signal indicating the opening / closing rate of the iris 3 supplied from the input means 18 to form the iris control signal.
It is designed to be supplied to Nos. 4 and 15.

[0020]

According to the present invention described above, an iris control signal is formed based on the signal of the upper N bits of the signal supplied from the input means 18 and is supplied to the drive means 14 and 15, and
Since the gain control signal is formed on the basis of the signal of the lower K bits of the signal supplied from the input means 18 and is supplied to the variable amplifier circuit 6, the video level of the camera output can be obtained with a simple structure and at low cost. Fine adjustments can be made, which allows good camera output to be obtained.

Further, according to the present invention described above, the input means 1
The detection means 11 detects a change in the sign of the increase rate of the signal indicating the open / close rate of the iris 3 output from the detection means 8, and based on the detection result, a change in the sign of the increase rate of the signal indicating the open / close rate of the iris 3 is detected. When detected, an iris control signal is formed based on a value obtained by adding correction data to the signal indicating the opening / closing ratio of the iris 3 supplied from the input means 18 to form the iris control signal.
Since it is supplied to Nos. 4 and 15, it is possible to prevent a discontinuous change in the video output level due to mechanical backlash that occurs in the iris servo system and obtain a good camera output.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the iris control device of the present invention will be described in detail below with reference to FIG.

In FIG. 1, reference numeral 1 generally indicates a video camera to which the iris control circuit of the present invention is applied. Light from a subject enters the video camera 1 as indicated by a solid arrow, and this incident light is reflected by a lens. Iris 3 by system 2
An image is formed on the incident surface of the CCD (charge coupled device) element 4 via the, and is accumulated as electric charge in the CCD element 4.

The information of the object accumulated as electric charges in the CCD element 4 is read out as a video signal by a reading circuit (not shown).

The video signal from the CCD element 4 is supplied to the gain control circuit 6 through the amplifier circuit 5.

The gain control circuit 6 varies the level of the video signal from the amplifier circuit 5 according to a control signal supplied from the microcomputer 11 described later via the DA converter 12.

The video signal from the gain control circuit 6 is A-
The A-D converter 7 is supplied to the D converter 7.
Then, the digital data is converted into digital data and then supplied to the digital detector 8.

In the three-plate color video camera, the above-mentioned CCD element 4 and amplifier circuit 5 are provided for the incident light of red, green and blue, respectively, and for so-called white balance correction and shading correction. Three gain control circuits 6 are provided for red, green and blue, respectively.

The detector 8 compares the level of the video signal with the level of the reference value from the digital data from the AD converter 7, and supplies the comparison result to the microcomputer 11 as an error signal.

The digital data from the detector 8 is supplied to a digital process circuit 9, and after various signal processing is performed in the digital process circuit 9, it is supplied to, for example, a television monitor or the like via an output terminal 10, and its pipe is supplied. It is displayed as an image on the surface.

The microcomputer 11 is supplied with the error signal from the detector 11 and the control data from the external device via the external input terminal 17.

In this example, as shown in this figure,
The camera controller 18 is used as an external device.

The camera controller 18 comprises, for example, a camera controller main circuit 20 and a rotary encoder 19.

Although not shown, the rotary encoder 19 is connected to a rotary switch, detects the amount of rotation when the operator operates the rotary switch, and supplies a signal corresponding to this to the camera controller main circuit 20. ..

The camera controller main body circuit 20 converts the signal from the rotary encoder 19 into n + k-bit digital data of a predetermined format, and the n + k-bit digital data is input to the input terminal 1 of the video camera 1.
It is supplied to the microcomputer 11 via 7.

Now, the microcomputer 11 uses the k + k bits of the control data of n + k bits from the camera controller 18.
The bit data is added to the gain control voltage data DAT _gc stored in the RAM (not shown) of the microcomputer 11.

In parallel with this, every time the control data of n + k bits is supplied from the camera controller 18, it is detected whether the control data is the opening direction or the closing direction of the iris 3, and the detection result is obtained. Accordingly, the correction by ΔV is performed to correct the delay in the response of the iris drive due to the backlash Δx (see FIG. 5) as shown in FIG.

As shown in FIG. 4, y values indicated by dashed lines y1 and y2 do not change the F value due to backlash, that is, when the iris 3 is driven from the opening direction to the closing direction and from the closing direction to the opening direction, this Δx amount is required. Iris 3 doesn't respond,
In other words, since it does not move, it takes time until the amount of light incident on the CCD element 4 changes.

Therefore, by correcting the gain control data supplied to the gain control circuit 6, the delay of the video level change due to the backlash is corrected in advance.

Then, for example, k-bit gain control data is obtained based on the error signal from the detector 8 and the data obtained by such addition or ΔV correction, and this gain control data is supplied to the DA converter 12.

Thus, this gain control data is DA
The converter 12 converts the analog gain control signal.

Then, this gain control signal is sent to the gain control circuit 6
The gain control circuit 6 controls the level of the video signal from the amplifier circuit 5 according to the gain control signal.

As a result, it is possible to interpolate the width ΔF that causes discontinuity of the output of the DA converter having a coarse number of bits shown as p2 in FIG. 3, and therefore p1 in FIG. 3 at the camera output. It is possible to make the video level change in small steps closer to the continuous output shown by.

On the other hand, the microcomputer 11 supplies n-bit control data corresponding to the lower order of the n + k-bit control data from the camera controller 11 to the DA converter 21.

This n-bit control data is converted into an analog signal by the DA converter 21, and then the subtraction circuit 1
3 is supplied.

The subtraction circuit 13 subtracts the detection signal from the position detection potentiometer 16 from the signal obtained by analog-converting the n-bit control data from the DA converter 21, and the subtraction result drives the motor 15. The signal is supplied to the motor 15 via the amplifier circuit 14.

Thus, the iris 3 is driven in the opening or closing direction by the amount corresponding to the drive signal level.

Next, the correction process for the backlash Δx in the microcomputer 11 will be described in detail with reference to FIG.

First, at step 100, ΔV _{gc is set} to "0". Then, the process proceeds to step 110.

In step 110, the camera controller 1
The control data IDAT _n from 8 is accepted. Then, the process proceeds to step 120.

In step 120, IDAT _{n is set} to IDA.
_Let T _n-1 . Then, the process proceeds to step 130.

In step 130, the camera controller 1
The control data IDAT _n from 8 is accepted. Then, the process proceeds to step 140.

At step 140, IDAT _n to IDA
Subtract T _n-1 to obtain Δ. Then, the process proceeds to step 150.

In step 150, it is judged whether or not the result Δ of the subtraction performed in step 140 is negative, and "YES".
If so, the process proceeds to step 160, and if "NO", the process proceeds to step 200.

That is, IDA which is the newer control data
It is possible to determine whether the iris 3 is open or closed by determining the plus or minus of Δ, which is the result of subtraction of the next data IDAT _n−1 from T _n .

At step 160, the plus flag is cleared. Then, the process proceeds to step 170.

In step 170, it is determined whether or not the minus flag is set. If "YES", the process proceeds to step 180, and if "NO", step 210.
Move to.

That is, the subtraction result obtained in step 140.
Set the minus flag if the result is negative
However, the control data ID one step before the present
AT _nThe minus flag has already been set when
In that case, in that case, one step before the present
The moving direction of iris 3 and the current moving direction of iris 3
Since it is the same, explanation is given in step 190.
As is clear, backlash Δx (see Fig. 5) occurs.
Therefore, the correction corresponding to the backlash Δx, etc.
There is no need to do so, so it remains as it is.

In step 180, the minus flag is set. Then, the process proceeds to step 190.

At step 190, ΔV is subtracted from the control data DAT _gc for controlling the gain control circuit 6, and this result is output. Then, the process proceeds to step 210.

That is, this ΔV becomes the voltage data corresponding to the backlash Δx described in FIG. 5, and this amount is subtracted from the control data DAT _gc first by one step before the current control data IDAT _n. The result obtained by subtracting the control data IDAT _n-1 is negative, that is, the iris 3 should be driven in the closing direction from the position of the iris 3 one step before.

This means that at the video level, the video level at the current control data IDAT _n should be lower than the video level at the control data IDAT _{n-1 which} is one step before the current control data IDAT _n . Shows.

That is, the motor 15 drives the iris 3 in the closing direction to reduce the amount of light incident on the CCD element 4. However, this is the only amount of backlash Δx described in FIG. The response of the video level drop is poor.

Therefore, even if the response of the iris 3 is poor, it is electrically unresponsive by reducing the gain control data DAT _gc supplied to the gain control circuit 6 by an amount corresponding to Δx in advance. Is being corrected.

At step 200, it is judged whether Δ is "0", and if "YES", the routine proceeds to step 210,
If “NO”, the process proceeds to step 220.

At step 210, IDAT _{n is set} to IDAT
_n-1 . Then, the process proceeds to step 130 again.

At step 220, it is judged whether Δ is positive, and if "YES", the routine proceeds to step 230,
If “NO”, the process moves to step 100 again. still,
In the case of “NO”, for example, an error message or the like may be displayed on a dedicated display unit or the like, and then the process may return to step 100.

At step 230, the minus flag is cleared. Then, the process proceeds to step 240.

In step 240, it is determined whether or not the plus flag is set. If "YES", the process proceeds to step 210, and if "NO", the process proceeds to step 250.

At step 250, the plus flag is set. Then, the process proceeds to step 260.

That is, if the subtraction result obtained in step 140 is positive, the plus flag is set, but the control data IDAT one step before the present is set.
_{Since the} plus flag may have already been set at the time of _n-1 , in that case, the moving direction of the iris 3 one step before the present and the moving direction of the present iris 3 are the same, so step As will be described later with reference to 260, backlash Δx (see FIG. 5) does not occur, and therefore correction or the like corresponding to backlash Δx is not performed, so that it remains as it is.

[0072] adding ΔV to step 260 in DAT _gc, and outputs the resulting DAT _gc. Then, the process proceeds to step 210.

That is, this ΔV becomes the voltage data corresponding to the backlash Δx described in FIG. 5, and this amount is added to the control data DAT _gc first by one step before the current control data IDAT _n. The result obtained by subtracting the control data IDAT _n-1 is positive, that is, it indicates that the iris 3 should be driven in the opening direction rather than the position of the iris 3 one step before.

This means that, at the video level, the video level at the current control data IDAT _n should be higher than the video level at the control data IDAT _n-1 one step before the current control data IDAT _n . Shows.

That is, the iris 3 is driven in the opening direction by the motor 15 to increase the amount of light incident on the CCD element 4, but this is the only amount corresponding to the backlash Δx explained in FIG. Responsiveness of increasing video level is poor.

Therefore, even if the responsiveness of the iris 3 is poor, the responsiveness of the iris 3 can be electrically reduced by previously adding the gain control data DAT _gc supplied to the gain control circuit 6 by the amount corresponding to Δx. It corrects the badness.

As described above, in this example, the gain control voltage data stored in the RAM of the microcomputer 11 is added to the upper k bits of the n + k bits of control data from the camera controller 18, and D-A The converter 12 converts it into an analog signal and supplies it to the gain control circuit 6 as a gain control signal, while the lower n bits of data are converted into an analog signal by the DA converter 21, and the analog signal from the position detection potentiometer 16 is used. Since the signal obtained by subtracting the detection signal is supplied as the drive signal to the motor 15, the drive of the iris 3 in the opening or closing direction can be adjusted more finely.

Further, in order to correct the delay due to the backlash, the correction by ΔV corresponding to the backlash Δx is performed, and the higher k bits of the control data are corrected by this ΔV, and then the analog-to-digital converter 12 is used. Since the signal is supplied and this analog signal is supplied to the gain control circuit 6 as the gain control signal, the delay of the response of the iris 3 due to the backlash is corrected, and the adjustment can be performed quickly and satisfactorily even during the fine adjustment. It can be carried out.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0080]

According to the present invention described above, an iris control signal is formed based on the signal of the upper N bits of the signal supplied from the input means and is supplied to the drive means, and at the same time the signal supplied from the input means is changed. Since the gain control signal is formed based on the lower K-bit signal and is supplied to the variable amplifier circuit, the video output level of the camera output can be finely adjusted with a simple configuration and at low cost. , There is a benefit that you can get a good camera output.

Further, according to the present invention described above, the change of the sign of the increase rate of the signal indicating the open / close rate of the iris output from the input means is detected by the detecting means, and the open / close rate of the iris is calculated based on the detection result. When a change in the sign of the increase rate of the indicated signal is detected, an iris control signal is formed based on a value obtained by adding correction data to the signal indicating the opening / closing rate of the iris supplied from the input means, and the iris control signal is supplied to the driving means. Since it was done, it prevents the discontinuous change of the video output level due to the mechanical backlash that occurs in the iris servo system,
There is a benefit of getting good camera output.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example in which an iris control circuit of the present invention is applied to a video camera.

FIG. 2 is a flow chart for explaining an iris control circuit of the present invention.

FIG. 3 is a graph provided respectively for explaining an iris control circuit of the present invention and a conventional iris control circuit.

FIG. 4 is a graph showing a backlash curve used for explaining a conventional iris control circuit.

FIG. 5 is a schematic diagram of an iris drive system.

[Explanation of symbols]

 3 Iris 4 CCD element 6 Gain control circuit 11 Microcomputer 12 D-A converter 14 Amplification circuit 15 Motor 18 Camera controller

Claims (2)

[Claims] 1. An iris, a driving means for driving the iris, an image pickup device for converting light incident through the iris into an electric signal, a variable amplifier circuit for amplifying an output signal of the image pickup device, and an iris. N + K bits (N = 1, 2,
, ... and K = 1, 2, 3, ...), and an iris control signal based on the upper N-bit signal of the signal supplied from the input means. And forming a gain control signal on the basis of the signal of the lower K bits of the signal supplied from the input means and supplying the gain control signal to the variable amplifier circuit. Iris control device. 2. An iris, a driving means for driving the iris via a gear, an image sensor for converting light incident through the iris into an electric signal, and a variable amplifier for amplifying an output signal of the image sensor. A circuit, input means for outputting a signal indicating the opening / closing rate of the iris, storage means for storing correction data of a value corresponding to the backlash of the gear, and the opening / closing rate of the iris output from the input means are shown. Detecting means for detecting a change in the sign of the increase rate of the signal; and when a change in the sign of the increase rate of the signal indicating the opening / closing rate of the iris is detected based on the detection result of the detecting means, from the input means. An iris control signal is formed based on a value obtained by adding the correction data to the supplied signal indicating the opening / closing ratio of the iris and is supplied to the driving means. Squirrel control device.