JPH07245728A - Method and device for adjusting video camera - Google Patents

Abstract

PURPOSE:To obtain a proper adjusted value to implement the correction of a black level in a still image video signal in an excellent way even at the start of image pickup device as well as at the beginning of restart of a still picture insertion. CONSTITUTION:In a manufacturing stage of the video camera, a light source 31 is used to pick up an image of a prescribed object and data of a still picture correction digital clamp signal and data of a moving picture correction digital clamp signal given to a signal processing circuit 11 from a camera microcomputer 15 are received by an EVR jig 33. The EVR jig 33 calculates the difference between both the digital clamp data and the difference is stored in an EEPROM or the like of the EVR jig 33 of the camera microcomputer 15 as an adjustment value to set the adjustment value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera adjusting method and apparatus.

[0002]

2. Description of the Related Art In a video camera, a video signal obtained by shooting is recorded on a video tape. Examples of modes for playing back recorded videotapes include moving image playback that is displayed as a moving image on the monitor, still image playback that is displayed as a still image on the monitor, frame-by-frame playback that sequentially displays still images on the monitor in the frame advance state, and a printer. There is print image reproduction that uses still images to print on paper. When performing still image reproduction, frame-by-frame reproduction, or print image reproduction (collectively referred to as “still image reproduction, etc.”), the image sensor (CCD) is set to a high-speed electronic shutter (for example, 1 / 250
It is desirable to reproduce a video signal (hereinafter, referred to as “video signal for still image”) when the high-speed electronic shutter is operated for 2 seconds). Since such a video signal for a still image is obtained by operating a high-speed electronic shutter,
The blurring of the reproduced image is reduced.

When shooting a moving image, the electronic shutter speed of the image pickup device (charge accumulation time of the CCD)
Is set to, for example, 1/100 second. When reproducing a still image, one still image is displayed on one monitor, and one monitor is divided into a plurality (for example, 9 or 16) and different still images are simultaneously displayed on each divided screen as a multi-screen. There are cases.

With the recently developed video camera, once the still image automatic insertion mode is selected, a high-speed electronic shutter (for example, 1/250) for each predetermined field (for example, 20 fields) can be obtained by simply pressing the shooting button and shooting. Seconds)
Some models are designed to operate automatically. When photographing with such a model, the photographer can photograph without recognizing that the high-speed electronic shutter operation is performed.

The detailed structure and operation will be described later in an embodiment of the present invention, but when the still image automatic insertion mode is selected, the shutter speed is shortened to compensate for the shortage of light quantity. , The video signal for still images is electrically amplified. As a result, the levels of the video signal (hereinafter referred to as “video signal for video”) obtained during video shooting (when the shutter speed is set to, for example, 1/100 second) and the video signal for still image are equalized. . By doing so, even if the moving image is reproduced in sequence without distinguishing the moving image signal and the still image signal, the occurrence of flicker on the reproduced screen is suppressed. If the gain of the video signal for still images is not increased, the screen obtained by playing back the video signal for still images becomes darker than the screen obtained by playing back the video signal for moving images. Large flicker occurs in the.

A video camera equipped with a still image automatic insertion mode has an AGC (auto gain control) circuit like a normal video camera, and in a situation in which exposure is insufficient even if the aperture is wide open, The AGC circuit electrically amplifies the video signal for moving images and the video signal for still images to perform exposure compensation. Therefore, in a situation where the subject is dark and underexposed, the gain of the video signal for a still image is increased to match the level of the video signal for a moving image and then the AGC is further performed.
Gain is increased by the circuit.

Further, in the video camera having the still image automatic insertion mode, when the still image automatic insertion mode is selected, the still image insertion signal is also recorded on the track on which the still image video signal is recorded, and the still image reproduction or the like is performed. When this is done, the still image insertion signal is detected to select the track on which the still image video signal is recorded. Then, the still image video signal of the selected track is reproduced to reproduce the still image.

[0008]

By the way, in the video camera provided with the still image automatic insertion mode, as described above,
In a situation where the subject is dark and the video signal is amplified by the AGC circuit, the gain of the video signal for a still image is increased to match the level of the video signal for a moving image, and further increased by the AGC circuit. That is, when the subject is dark, the still image video signal is gained up twice. Therefore, the proportion of noise components in the gained-up still image video signal increases, and the image quality of the still image obtained by reproducing the still image based on the still image video signal deteriorates. Then, it came to consider developing a video camera having a still image automatic insertion mode having the following functions. That is, even if the still image automatic insertion operation is performed, when the brightness of the video signal becomes darker than a predetermined value, the still image automatic insertion operation is stopped, and then the brightness of the video signal becomes brighter than the predetermined value. Automatically restarts the still image automatic insertion operation. By doing so, it is possible to avoid capturing a still image with poor image quality.

Even in this case, since the level fluctuation of the video signal caused by the fluctuation of the brightness of the subject is not completely eliminated, it is necessary to introduce the "digital clamp control" for digitally clamping the black level of the video signal. I arrived.

However, since the digital clamp control is originally a feedback control, the first clamp after the power is turned on, such as when the shooting button of the video camera is pressed to start shooting.
The black level of the second video signal for a still image cannot be optimally controlled, and in this case, how to obtain the necessary control data becomes a problem. The still image video signal and the moving image video signal pass through different circuits because the former is amplified, and a level difference occurs due to the influence of switching required for the former.
In order to remove this level difference, it is necessary to adjust the blanking level by the level adjusting circuit, but the problem is how to set the circuit itself to the optimum operating state. In addition, since the level difference between the color signal of the still image video signal and the color signal of the moving image video signal remains only by adjusting the blanking level, the digital clamp control for the still image color signal is corrected. Need to add
The problem is how to set the coefficient necessary for this correction. When compensating for the lack of light amount due to the high shutter speed by amplifying the video signal for still images, how to set the gain required to match the brightness between the video signal for still images and the video signal for moving images It's a problem. When performing digital clamp control, an analog video signal is converted to a digital signal by an A / D converter.
It is necessary to add an appropriate amount of offset amount to the input signal of the converter by the offset adding circuit so that the signal can be surely converted to a small level. If this offset amount is set while visually observing the waveform with an oscilloscope, it is troublesome and the accuracy is not good. Therefore, how to easily and surely set an appropriate offset amount is a problem. Further, when the above-mentioned adjustment or setting is performed, an error occurs when the brightness of the illumination light fluctuates, so it is necessary to use appropriate illumination light. Further, it is necessary to prepare an adjusting device suitable for the above-mentioned adjustment and setting.

In view of the above situation, it is an object of the present invention to provide a method and apparatus suitable for adjusting or setting a video camera having a still image automatic insertion mode.

[0012]

According to a first aspect of the present invention, when the brightness of a subject becomes brighter than a predetermined value, a high-speed electronic shutter operation of the image pickup device is performed for each predetermined field to output a still image video signal. , In other fields, the image sensor is operated at the normal shutter speed to output the video signal for the moving image, and when the brightness of the subject becomes darker than the predetermined value, the shutter speed of the image sensor is set to the normal shutter speed in all fields. A video camera having a still image automatic insertion mode, which further integrates the signals of the blanking period of the still image video signal to obtain an integrated photometric value for still image correction, and An integration circuit that integrates the signals in the blanking period to obtain an integrated photometric value for moving image correction, and a still image correction lens when a still image video signal is input. The black level of the video signal for still images is corrected and output based on the video signal, and when the video signal for video is input, the black level of the video signal for video is corrected based on the clamp signal for video correction. A signal processing circuit for correction and output, and a clamp signal for still image correction based on the integrated photometric value for still image correction, and a clamp signal for video correction based on the integrated photometric value for video correction. When a still image video signal is input to the signal processing circuit, a clamp signal obtained based on the still image video signal output from the image sensor before the still image video signal is calculated. , A clamp signal that is sent to the signal processing circuit and, when a video signal for a moving image is input to the signal processing circuit, is obtained based on the video signal for a moving image output from the image sensor before the video signal for the moving image. , And a camera microcomputer for sending to the signal processing circuit, further the camera microcomputer, when the video camera is video signal for the first still image from the start of operation is inputted to the signal processing circuit,
A clamp signal obtained by adding a preset adjustment value to the clamp signal obtained based on the video signal for a moving image output from the image pickup device before the video signal for a still image,
In a video camera adapted to be sent to the signal processing circuit, at the stage of manufacturing the video camera, when a predetermined object is photographed and a still image correction clamp signal and a video image signal for still image input are input. Of the moving image correction clamp signal, and the value corresponding to this difference is recorded in advance in the camera microcomputer as the adjustment value.

According to the second aspect of the present invention, when the brightness of the subject becomes brighter than a predetermined value, the image pickup device is operated at a high speed electronic shutter for each predetermined field to output a still image video signal, and another field is output. Then, the image sensor is operated at the normal shutter speed to output the video signal for the moving image, and when the brightness of the subject becomes darker than a predetermined value, the shutter speed of the image sensor is set to the normal shutter speed in all fields. A video camera having an insertion mode, further comprising a level adjusting circuit for adjusting a blanking level of a video signal and an integrated photometric value for still image correction by integrating a signal of a blanking period of a video signal for a still image. And the integration circuit that calculates the integrated photometric value for video correction by integrating the signal in the blanking period of the video signal for video When an image signal is input, a black level correction is performed on this still image video signal based on the clamp signal for still image correction, and it is output, and when a video image signal is input, a clamp signal for video correction is input. Based on this, a signal processing circuit that corrects and outputs a black level for this video signal for video, and a clamp signal for still image correction using a correction coefficient preset based on the integrated photometric value for still image correction. Along with the calculation, the clamp signal for moving image correction is calculated based on the integrated photometric value for moving image correction, and when the still image video signal is input to the signal processing circuit, it is preceded by the still image video signal. A clamp signal obtained based on the still image video signal output from the image sensor is sent to the signal processing circuit, and when the video signal is input to the signal processing circuit, the video signal In a video camera having a camera microcomputer that sends a clamp signal obtained based on a video signal for a moving image output from the image pickup device to the signal processing circuit before, a predetermined object at the manufacturing stage of the video camera. Is taken and the difference between the clamp signal for still image correction when inputting the video signal for still images and the clamp signal for video correction when inputting the video signal for moving images is calculated, and the level is adjusted in advance so that the value becomes zero. The circuit adjusts the blanking level, and the level difference between the color signal of the video signal for still images and the color signal of the video signal for moving images is calculated, and the correction coefficient of the camera microcomputer is set so that the value becomes zero. It is a method of adjusting a video camera, which is characterized in that it is determined and recorded in advance in the same camera microcomputer.

According to the third aspect of the present invention, when the brightness of the subject becomes brighter than a predetermined value, the image pickup device operates the high speed electronic shutter for each predetermined field to output a still image video signal, and normally in other fields. A still image automatic insertion mode that operates the image sensor at the shutter speed and outputs a video signal for a moving image, and when the brightness of the subject becomes darker than a predetermined value, the shutter speed of the image sensor is set to the normal shutter speed in all fields. A video camera further comprising: an amplifier circuit for amplifying a still image video signal with a preset gain, and a still image correction for integrating a blanking period signal of the amplified still image video signal. And an integration circuit that calculates the integrated photometric value for video correction by integrating the blanking period signal of the video signal for video. When a video signal for image is input, black level correction is performed on the video signal for still image based on the clamp signal for still image correction, and the signal is output for video correction when the video signal for video is input. A signal processing circuit that performs black level correction for this video signal for video based on the clamp signal and outputs it, and also calculates a clamp signal for still image correction based on the integrated photometric value for still image correction, and also performs video correction When a clamp signal for moving image correction is calculated based on the integrated photometric value for a still image and a still image video signal is input to the signal processing circuit, it is output from the image sensor before the still image video signal. The clamp signal obtained based on the still image video signal is sent to the signal processing circuit, and when the moving image signal is input to the signal processing circuit, the image pickup device is placed before the moving image signal. In a video camera having a camera microcomputer, which sends a clamp signal obtained based on the video signal for a moving image output from the video camera, to a signal processing circuit, a predetermined subject is photographed at the manufacturing stage of the video camera to obtain a still image. A method of adjusting a video camera, characterized in that a difference between an integrated photometric value for correction and an integrated photometric value for moving image correction is obtained, and a gain of the amplifier circuit is preset so that the value becomes zero.

Further, in the invention of claim 4, when the brightness of the subject becomes brighter than a predetermined value, the image pickup device is operated at a high speed electronic shutter for each predetermined field to output a still image video signal, and another field is output. Then, the image sensor is operated at the normal shutter speed to output the video signal for the moving image, and when the brightness of the subject becomes darker than a predetermined value, the shutter speed of the image sensor is set to the normal shutter speed in all fields. A video camera having an insertion mode, further comprising an A / D converter for converting a still image video signal and a moving image video signal from an analog signal to a digital signal, and an analog video input to this A / D converter. An offset adding circuit that adds a preset offset amount to the signal, and integrates the blanking period signal of the digital video signal for still images. An integration circuit that calculates the integrated photometric value for still image correction, integrates the signals in the blanking period of the video digital video signal to obtain the integrated photometric value for video correction, and the digital video signal for still image are input. When the digital clamp signal for still image correction is used, black level correction is performed on the digital video signal for still image and output, and when the digital video signal for video is input, the digital clamp signal for video correction is output. Based on this, a signal processing circuit that corrects and outputs the black level of the digital video signal for moving images, and calculates the digital clamp signal for still image correction based on the integrated photometric value for still image correction, and also for moving image correction. When a digital clamp signal for moving image correction is calculated based on the integrated photometric value of, and a still image digital video signal is input to the signal processing circuit, A digital clamp signal obtained based on the still image digital video signal output from the image sensor before the still image digital video signal is sent to the signal processing circuit, and the moving image digital image is sent to the signal processing circuit. When a signal is input, it has a camera microcomputer that sends to the signal processing circuit a digital clamp signal obtained based on the moving image digital image signal output from the image pickup device before the moving image digital image signal. In the video camera, at the stage of manufacturing the video camera, a predetermined subject is photographed, and the offset amount of the offset circuit is adjusted so that the still image correction digital clamp signal and the moving image correction digital clamp signal have predetermined values. It is a method of adjusting a video camera, characterized in that it is determined and preset in the same offset adding circuit.

According to a fifth aspect of the present invention, in each of the above video camera adjusting methods, the brightness of the illumination light is limited to a range in which the gain of the auto gain control circuit of the video camera is equal to or less than a predetermined value during shooting in the manufacturing stage. That is, the light source of the illumination light is driven by an AC power source having the same frequency as the frequency of the vertical synchronizing signal of the video camera.

Further, according to the invention of claim 6, when the brightness of the subject becomes brighter than a predetermined value, the image sensor is operated at a high speed electronic shutter for each predetermined field to output a video signal for a still image, and the other field. Then, the image sensor is operated at the normal shutter speed to output the video signal for the moving image, and when the brightness of the subject becomes darker than a predetermined value, the shutter speed of the image sensor is set to the normal shutter speed in all fields. A video camera having an insertion mode, further comprising an amplifier circuit for amplifying a still image video signal with a preset gain, and a moving image video signal and the amplified still image video signal are converted from an analog signal to a digital signal. A / D converter and offset addition for adding a preset offset amount to the analog video signal input to this A / D converter Path, a level adjustment circuit that adjusts the blanking level of the analog video signal input to this offset addition circuit, and the integrated photometry for still image correction by integrating the signal in the blanking period of the digital video signal for still images. An integrating circuit that calculates the value and integrates the signals in the blanking period of the moving image digital video signal to obtain an integrated photometric value for moving image correction, and a still image correction signal when the still image digital image signal is input. Black level correction is performed on this still image digital video signal based on the digital clamp signal and output, and when a video digital video signal is input, this video digital image is based on the video correction digital clamp signal. A signal processing circuit that corrects the black level of the signal and outputs it, and a digital image correction circuit for still image correction based on the integrated photometric value for still image correction. The clamp signal is calculated, the digital clamp signal for moving image correction is calculated based on the integrated photometric value for moving image correction, and when the still image digital video signal is input to the signal processing circuit, the still image digital signal is input. A digital clamp signal obtained based on the still image digital video signal output from the image sensor before the video signal is sent to the signal processing circuit, and the video digital video signal is input to the signal processing circuit. Sometimes, it has a camera microcomputer for sending to the signal processing circuit a digital clamp signal obtained based on the moving picture digital video signal output from the image pickup device before the moving picture digital video signal, and further the camera microcomputer. The microcomputer is
When the first still image video signal is input to the signal processing circuit after the video camera starts operating, it is obtained based on the moving image video signal output from the image sensor before the still image video signal. In a device for adjusting a video camera, which is configured to send a digital clamp signal obtained by adding a preset adjustment value to the digital clamp signal to the signal processing circuit, a still image when a predetermined subject is photographed A means for obtaining a difference between the correction digital clamp signal and the moving image correction digital clamp signal, and recording a value corresponding to the difference in the camera microcomputer as the adjustment value, and for still image correction when a predetermined subject is photographed Find the difference between the digital clamp signal and the digital clamp signal for video correction, and adjust the level adjustment so that the difference becomes zero. And a level difference between the color signal of the still image digital video signal and the color signal of the moving image digital video signal when a predetermined object is photographed, and the value is set to zero. A means for determining the correction coefficient of the camera microcomputer and recording it in the camera microcomputer, and the difference between the integrated photometric value for still image correction and the integrated photometric value for video correction when a predetermined subject is photographed, and the value is zero. Means for setting the gain of the amplification circuit so that the offset amount is determined so that the still image correction digital clamp signal and the moving image correction digital clamp signal when a predetermined subject is photographed have predetermined values. Means for setting in the offset adding circuit and a range in which the brightness is within a range where the gain of the auto gain control circuit of the video camera is below a predetermined value, and An illumination light source which is driven by an AC power source having the same frequency as the frequency of the vertical synchronizing signal is an adjustment device of the video camera, characterized by comprising.

[0018]

According to the present invention, the difference between the still image correction clamp signal at the time of inputting the still image video signal and the moving image correction clamp signal at the time of inputting the moving image signal is obtained at the manufacturing stage of the video camera. By recording the value corresponding to this difference as the adjustment value in the camera microcomputer in advance, the black level of the first video signal for still image after the power is turned on can be calculated.
Prior to that, an adjustment value is added to the clamp signal obtained based on the video signal for a moving image output from the image pickup device to form a clamp signal, and the clamp signal is sent to the signal processing circuit, so that appropriate control can be performed. it can.

According to the second aspect of the invention, in the manufacturing stage of the video camera, the difference between the still image correction clamp signal at the time of inputting the still image video signal and the moving image correction clamp signal at the time of inputting the moving image signal is obtained, The blanking level is adjusted in advance by the level adjusting circuit so that the value becomes zero. Further, the level difference between the color signal of the still picture video signal and the color signal of the moving picture video signal is obtained, and the correction coefficient of the camera microcomputer is determined so that the value becomes zero and is recorded in advance in the same camera microcomputer. As a result, it is possible to eliminate the level difference of the luminance signal and the level difference of the color signal caused by the influence of switching.

According to the third aspect of the present invention, the difference between the integrated photometric value for still image correction and the integrated photometric value for moving image correction is calculated at the manufacturing stage of the video camera, and the gain of the amplifier circuit is adjusted so that the difference becomes zero. Is set in advance. As a result, the brightness of the video signal for a still image and the brightness of the video signal for a moving image match without being affected by the shutter speed.

According to a fourth aspect of the present invention, the offset amount of the offset circuit is determined so that the still image correction digital clamp signal and the moving image correction digital clamp signal have predetermined values at the manufacturing stage of the video camera. It is preset in the additional circuit. Thereby, an appropriate offset amount can be set easily and surely without observing the waveform.

According to the invention of claim 5, the brightness of the illumination light is limited to a range in which the gain of the auto-gain control circuit of the video camera is equal to or less than a predetermined value at the time of photographing at the manufacturing stage, and the light source of the illumination light is controlled by the video. It is driven by an AC power supply with the same frequency as the vertical sync signal frequency of the camera. As a result, the adjustment or setting can be performed without being affected by the automatic gain control circuit and without being affected by the flicker of the light source.

According to the sixth aspect of the invention, the above-mentioned various adjustments and settings can be performed by one adjusting device.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An adjusting method and apparatus according to an embodiment of the present invention will be described below in detail with reference to the drawings together with a video camera having a still image automatic insertion mode.

<Overall Configuration and Operation Outline of Video Camera of Embodiment> FIG. 1
FIG. 3 is a block diagram of a video camera having a still image automatic insertion mode according to an embodiment. In this video camera, the optical image formed by the lens 1 and passing through the iris 3 is C
An image is formed on the light receiving surface of the CD 5, and an analog video signal E is output from the CCD 5. The video signal E is amplified by the amplifier circuit 7 as necessary (details will be described later), and converted into a digital signal by the A / D converter 9. The digital video signal E is signal-processed by the digital signal processing circuit 11 to become a video signal V, and the video signal V is recorded on a video tape by the video circuit in the subsequent stage. Integrator circuit 1 for light intensity detection
3 integrates the video signal E for each field.

The camera microcomputer 15 sends a digital clamp signal DC for black level correction to the digital signal processing circuit 11 based on the integration data obtained by the integration circuit 13 (the operation here will be described in detail later). Also, the camera microcomputer 15
Detects the exposure amount on the basis of the integrated data obtained by the integration circuit 13 and sends an iris signal to the iris driver 17 so as to obtain the optimum exposure amount. The iris driver 17 adjusts the opening of the iris 3 according to the iris signal. Iris 3
If the exposure becomes insufficient even if the opening degree of exceeds a predetermined value, the gain of the AGC circuit 7a is increased by a command from the camera microcomputer 15. When the opening of the iris 3 is less than or equal to the predetermined value (that is, when the subject is bright), A
The gain of the GC circuit 7a is 1.

The still image automatic insertion switch 19 is installed on the surface on which the battery pack is mounted, and the battery pack must be removed in order to turn on / off the switch 19. Conversely, when the battery pack is mounted and shooting is performed, the still image automatic insertion switch 19 cannot be turned on / off.

When the automatic still image inserting switch 19 is turned on and the still image automatic inserting operation is not stopped (which will be described later), that is, when the switch 19 is inserted and the camera is in a photographing condition in which no large noise is generated, the camera microcomputer 15 operates. , The still image automatic insertion mode signal SI is sent to the still image automatic insertion control IC 21 at a cycle of 20 fields.

Upon receiving the still image automatic insertion mode signal SI, the still image automatic insertion control IC 21 sets the shutter speed to 1/250 seconds in the 20n + 2 field, and sets the shutter speed of the CCD 5 to 1 / s in other fields.
A shutter speed switching signal SS _S set to 100 seconds is sent to the timing generator 23. Note that n is an integer including 0. The timing generator 23 controls the electronic shutter speed of the CCD 5 according to the shutter speed switching signal SS _S.

Here, the shutter speed is 1/100
The video signal E obtained when the second is
Referred to as _M, the video signal E obtained when the shutter speed 1/250 seconds is referred to as a still picture video signal E _S. Further, in the field in which the moving picture video signal E _M is output from the CCD 5, the still image automatic insertion control IC 21 turns on the mode changeover switch 7b of the amplifier circuit 7 to the terminal M side, and the CCD 5 outputs the still picture video signal E _S. In the output field, the mode changeover switch 7b is turned on to the terminal S side. Therefore, the still image video signal E _S is amplified by the still image amplifier 7c, and the level of the amplified still image video signal E _S is adjusted to the level of the moving image signal E _M.
The gain of the still image amplifier 7c is preset in the camera microcomputer 15, and the gain is amplified as it is. Further, in addition to the AGC circuit 7a, the mode changeover switch 7b and the amplifier 7c, the amplifier circuit 7 includes a level adjusting circuit 7d and a switch 7b.
And the AGC circuit 7a. In addition, the amplifier circuit 7 and A
An offset adding circuit 8 is provided between the / D converter 9 and the / D converter 9. The operation of the level adjusting circuit 7d is set in advance in the same level adjusting circuit 7d, and the level is adjusted accordingly.
The offset amount of the offset adding circuit 8 is set in the camera microcomputer 15 in advance, and the offset is added as it is.

Further, in the field where the video signal V obtained by processing the still image video signal E _S is output from the digital signal processing circuit 11, the still image automatic insertion control IC 21 determines the blanking period of the video camera signal V. The still image insertion signal I is superimposed on.

When the automatic still image inserting switch 19 is not turned on, or when the automatic still image inserting operation is stopped (described later) even if this switch 19 is turned on, the still image automatic inserting mode is set from the camera microcomputer 15. The signal SI is not output. Therefore, at this time, the still image automatic insertion control IC 21 causes the shutter speed switching signal SS _M to set the shutter speed in all fields to 1/100 second.
And the shutter speed of the CCD 5 is fixed at 1/100 second. Furthermore, by the still image automatic insertion control IC21,
The mode changeover switch 7b remains turned on to the terminal M side, and the still image insertion signal I is not output. As a result, the still image automatic insertion operation is not performed.

<Outline of Configuration and Operation for Black Level Correction>
Here, the outline of the operation of correcting the black level of the video signal E (E _M , E _S ) by the integrating circuit 13, the camera microcomputer 15, and the digital signal processing circuit 11 will be described.

In order to capture a beautiful color image with a color video camera, the black level of the video signal E must always be properly fixed at a prescribed level. However, CCD
The output of 5 includes a dark current that fluctuates depending on the ambient temperature, and the black level of the video signal E fluctuates due to the fluctuation of the dark current. When the video signal E passes through an AC-coupling amplifier circuit (AGC circuit 7a or the like), the DC component is lost, and the black level fluctuates depending on the contents of the screen. In order to eliminate the black level fluctuation due to such a cause, the black level is corrected by the digital clamp control. That is, since the blanking period of the video signal is a period during which no light is incident on the camera, the level during this period is corrected by considering it as a reference level indicating perfect black.

Specifically, the option built in the integrating circuit 13 is
Tickal black detection circuit (not shown) has 1 feel
Signal in the blanking period of the video signal E for each
Is integrated to obtain an integrated photometric value IB for black level correction and output.
Force Camera microcomputer 15 inputs every field
Optimal black level correction is performed based on the integrated photometric value IB
Digital clamp signal DC for each field
Output to the digital signal processing circuit 11. Digital signal processing
The logic circuit 11 sets the level of the digital clamp signal DC to black.
Video signal E is clamped so that the level becomes black level
Make a correction. In addition, video signal E for video_MProduct obtained by accumulating
IB the photometric value_M, Video signal E for still images _SObtained by accumulating
IB_SIndicate.

<Signal State During Still Image Automatic Insertion Operation> Next, the signal state during the still image automatic insertion operation will be described with reference to FIG. This operation is performed when the shooting button (REC button) is pressed in a mode in which the still image automatic insertion switch 19 is turned on and the still image automatic insertion operation is not stopped (described later).

In this operation, the still image automatic insertion mode signal SI is sent from the camera microcomputer 15 to the still image automatic insertion control IC 21 in the 1st, 21st, ... 20n + 1 fields (FIG. 2 (b)). reference). Upon receiving the still image automatic insertion mode signal SI, the still image automatic insertion control IC 21 sends a shutter speed switching signal SS _S to the timing generator 23 at a timing delayed by one field from the reception of the signal SI. Therefore, the second and second
2, ... In the 20n + 2 field, the shutter speed is set to 1/250 seconds in the timing generator 23, and in the other fields, the shutter speed is set to 1/100 seconds (see FIG. 2 (c)). .

The CCD 5 operates electronically at a shutter speed set in the timing generator 23 at a timing delayed by one field. Therefore C
The actual shutter speed of CD5 is 3rd, 23rd, ...
It becomes 1/250 seconds in the 20n + 3th field and becomes 1/100 seconds in the other fields (see FIG. 2D). Therefore, the still image video signal E _S is output in the 3rd, 23rd, ..., 20n + 3 fields, and the moving image video signal E _M is output in the other fields.

The integrator circuit 13 displays the video over one field.
Signal E (E_M, E_S) Is integrated and the product for black level correction
Photometric value IB_M, IB_SAnd AE (auto exposure
Integrated photometric value I_M, I_S(See below). Yo
Video signal E_SFrom the field where is output
Delay, that is, the 4th, 24th, ... 20n + 4th frame
Field metered value IB_S, I_SGot other feel
Metering value IB_M, I _MIs obtained (FIGS. 2 (e) and (f)
reference).

Next, how to obtain the integrated photometric values I _M and I _S will be described. As shown in FIG. 3, the image pickup surface of the CCD 5 is divided into _three blocks B ₁ , B ₂ and B ₃ , and each block B ₁ ,
The value obtained by integrating the video signals obtained from B ₂ and B ₃ is b ₁ ,
Let b ₂ and b ₃ .

The integrated photometric value I _M for AE is the video signal E for moving images.
_If the values obtained by integrating _M are b ₁ , b ₂ , and b ₃ , they can be calculated by the following equation (1). I _M = k ₁ · b ₁ + k ₂ · b ₂ + k ₃ · b ₃ (1) where k ₁ , k ₂ and k ₃ are constants

The integrated photometric value I _S for AE is calculated by the following equation (2), where b ₁ , b ₂ and b ₃ are values obtained by integrating the video signal E _S for still images. I _S = k ₁ · b ₁ + k ₂ · b ₂ + k ₃ · b ₃ (2)

<Exposure control method> During automatic still image insertion operation
The control of the iris 3 and the operation of the AGC circuit 7a are as follows.
Do it like this. That is, the 5th, 25th, ... 20n + 5th frame
In fields other than fields, you can get it in the previous field.
Integrated AE metering value I_MHowever, the target measurement
The opening of the iris 3 and AGC so that it becomes equal to the light value.
The gain of the circuit 7a is adjusted. 5th, 25th, ... 2nd
In the 0n + 5 field, the 2nd previous field, the
3, 23, ... Product for AE obtained in the 20n + 3 field
Photometric value I _MIs equal to the preset target metering value.
The iris 3 opening and the AGC circuit 7a
Adjust the gain. In other words, for exposure control, integrated metering
Value I _SIs not used.

When the still image automatic insertion operation is not performed,
The AE control in all fields is performed so that the AE integrated photometric value I _M obtained in the immediately preceding field becomes equal to the target photometric value.

<Control for Canceling Still Image Automatic Insertion Operation> Next, an operation for canceling the still image automatic insertion operation during the still image automatic insertion operation and shooting will be described. This operation is performed mainly by the camera microcomputer 15, and is basically performed in the following states. That is, the brightness of the subject is insufficient and the AG
The gain of the C circuit 7a increases and the amplifier 7c and the AG
When the noise component in the still image video signal E _S becomes large because the gain is increased by the C circuit 7a. When the subject becomes brighter after the still image automatic insertion operation is stopped due to insufficient brightness, the still image automatic insertion operation is restarted.

The process of stopping the still image automatic insertion operation will be described in detail with reference to FIG. It is assumed that the still image automatic insertion switch 19 is still turned on.

First, the operation shown in FIG. 4 will be described. Shooting (R
When the EC button is pressed, the camera unit shown in FIG. 1 is activated (starts up), and a certain time (for example, 0.6
Before the elapse of seconds, the camera microcomputer 15 does not output the still image automatic insertion mode signal SI. Fixed time (eg 0.6
After the elapse of seconds), the exposure is stabilized and the signal SI is started to be output (steps 1, 2, 3).

When the signal SI is output (step 4), it is determined whether or not it is the 20th field (where n is an integer including 0), that is, whether or not it is the field immediately before the field to which the signal SI is output. (Step 5), if it is the 20th field, the process proceeds to step 6, and if it is not the 20n field, the process proceeds to step 8.

In step 6, the brightness value L of the subject is compared with a preset brightness value α (α is the brightness at which the gain of the AGC circuit 7a begins to increase). Although the AGC control value that determines the gain of the AGC circuit 7a is used as the brightness value L of the subject, the aperture value of the iris 3 or the exposure value E _v can also be used. The exposure value E _v is
Calculated from the aperture value, AGC control value, shutter speed and over / under exposure value. When the brightness value L of the subject is smaller than the set brightness value α, the output of the signal SI is stopped and the still image automatic insertion operation is stopped (step 7). When the brightness value L is larger than the brightness value α in step 6, the process proceeds to step 8.

In step 8, the brightness value L of the subject is compared with the preset brightness value β. Brightness value β
Is larger than the brightness value α. When the brightness value L of the subject is larger than the brightness value β, the signal SI is output (step 9). Therefore, even if the output of the signal SI is once stopped and the still image automatic insertion operation is stopped, if the subject becomes brighter thereafter, the signal SI is output and the still image automatic insertion operation is restarted. Note that the automatic still image insertion operation may be restarted immediately after L> β, or L> β.
It may be performed from a field delayed by a predetermined field from that field. When the brightness value L of the subject is smaller than the set brightness value β in step 8, the process proceeds to step 4.

Thus, in the 20nth field, S
Whether or not to output the I signal is determined. When it is determined to output, the SI signal is output in the 20n + 1 field, and when it is determined not to output, the output of the SI signal in the 20n + 1 field is stopped.

When the still picture automatic insertion mode signal SI is stopped and the still picture automatic insertion operation is stopped, only the moving picture image signal E _M is output. However, the still picture is included in the moving picture image signal E _M of the 20n + 3 field. The insertion signal I is superimposed. Therefore, when reproducing a still image or the like, the moving image video signal E _M of the 20n + 3 field on which the still image insertion signal I is superimposed is reproduced, and the still image is reproduced based on this signal E _M.

<Signal State during Black Level Correction Operation> When the still image automatic insertion operation is being performed, the timing at which the integrated photometric values IBM _M and IB _S for black level correction are loaded into the camera microcomputer 10 and the camera microcomputer 10 2 (f) (g) shows the timing of outputting the digital clamp signal DC from
Will be described with reference to. Incidentally shows a digital clamp signal obtained based on the integrated photometric value IB _M DC _M, a digital clamp signal obtained based on the integrated photometric value IB _S as DC _S.

As shown in FIGS. 2G and 2H, the camera microcomputer 15 outputs the digital clamp signal DC _S in the 23rd field. This signal DC _S is the integrated photometric value IB input in the 4th field. It is calculated based on _S. Generally speaking, the digital clamp signal DC _S obtained by calculation based on the integrated photometric value IB _S input in the 20n + 4th field is output in the 20th (n + 1) + 3th field. Of the digital clamp signals DC _S , the digital clamp signal DC _S0 that is first output after the power is turned on.
(The third field in FIG. 2) is calculated by the method described later.

The digital clamp signal DC _M output in the fifth (generally 20n + 5) field is the third
(Typically 20n + 3) is obtained by calculating based on the integrated photometric value IB _M entered in the field.

The digital clamp signal DC _M output in the other fields (fields other than the 20 (n + 1) +3, 20n + 5th field) is calculated based on the integrated photometric value IB _M input in the immediately preceding field.

<Description of Black Level Correction Operation of Still Image Video Signal> Here, the control for correcting the black level of the still image video signal E _S will be described.
Each state will be described.

<First Example of Black Level Correction Operation of Still Image Video Signal> FIG.
Shows the operation of the first example. In this example, the state where the brightness of the subject becomes brighter or darker is repeated (see FIG. 5).
(F)), the automatic still image inserting operation is activated or stopped (FIG. 5 (b)), and the AGC circuit 7a is turned on (gain becomes greater than 1) or turned off (gain becomes 1). (Fig. 5 (e)). The brightness of ON / OFF switching of the AGC circuit 7a is different from the brightness of switching operation / stop of the automatic still image inserting operation.

As shown in FIG. 5 (f), the brightness of the subject is changing, and the AGC circuit 7a is turned on after the photographing button is pressed at time t ₀ and the video camera is turned on.
Then, at time t ₁ , the still image automatic insertion operation is activated, and at time t ₂
The AGC circuit 7a is turned off at, and the AGC circuit 7a is turned off at time t _3.
a is turned on, the still image automatic insertion operation is stopped at time t ₄ , and the still image automatic insertion operation is restarted at time t ₅ .

The operation shown in FIG. 5 will be described in order. The power is turned on at time t ₀ and the AGC circuit 7a is turned on.
To do. After the power is turned on, the first digital clamp signal DC _S0 for a still image is output from the camera microcomputer 15. The value of this digital clamp signal DC _{S0 is the same as} the value of the digital clamp signal DC _M for the moving image output in the previous field.
It is a value obtained by adding the adjustment value set in the camera microcomputer 15 in advance. The adjustment value is set according to the characteristics of the video camera at the time of shipping the video camera, and one fixed adjustment value is set for one video camera. By the time this digital clamp signal DC _S0 is output, the integrated photometric value IB _S for a still image has not been obtained, but the digital clamp signal DC that has a good value has been obtained by the above-mentioned device. It is possible to output _S0, and it is possible to excellently perform black level correction of the still image video signal E _S that is first output after the power is turned on.
This operation is one of the points of the present invention.

When the still image automatic insertion mode signal SI ₁ is output from the camera microcomputer 15, the still image video signal E _S is output from the CCD 5 and the integrated photometric value IB _S1 obtained by integrating the video signal E _S by the integration circuit 13. Is obtained (eg in the third field). Then, the camera microcomputer 15 calculates the digital clamp signal DC _S1 based on the integrated photometric value IB _S1 , and this digital clamp signal DC _S1 is output with a delay of a predetermined field (specifically, for example, in the 23rd field). If the AGC circuit 7a is turned on when the integrated photometric value IB _S1 is obtained, the camera microcomputer 15 only outputs the digital clamp signal DC _S1 and does not store it.

When the still image automatic insertion mode signal SI ₂ is output, the still image video signal E _S is integrated to obtain an integrated photometric value IB _S2 , the digital clamp signal DC _S2 is calculated, and a predetermined field delay occurs. Digital clamp signal DC
_S2 is output. The camera microcomputer 15 uses the integrated photometric value I
Since the AGC circuit 7a is off when B _S2 is obtained, the digital clamp signal DC _S2 is output and stored.

When the still image automatic insertion mode signal SI ₃ is output, the still image video signal E _S is integrated to obtain an integrated photometric value IB _S3 , the digital clamp signal DC _S3 is calculated, and a predetermined field delay occurs. Digital clamp signal DC
_S3 is output. The camera microcomputer 15 uses the integrated photometric value I
Since the AGC circuit 7a is off when B _S3 is obtained, the digital clamp signal DC _S3 is output and stored. Then, the previously stored digital clamp signal DC _S2 is erased.

When the still image automatic insertion mode signal SI ₄ is output, the still image video signal E _S is integrated to obtain an integrated photometric value IB _S4 , and the digital clamp signal DC _S4 can be calculated. At the timing delayed by the predetermined field, the still image automatic insertion operation is stopped, so the digital clamp signal DC _S4 is not output. Camera microcomputer 1
In No. 5, since the AGC circuit 7a is turned on when the integrated photometric value IB _S4 is obtained, the digital clamp signal DC _S4 is not stored but the digital clamp signal DC stored in the previous memory is stored.
Hold _S3 . When the AGC circuit 7a is ON, the value of the integrated photometric value IB _S varies greatly depending on the value of the AGC gain. Therefore, the digital clamp signal DC _S obtained when the AGC circuit 7a is ON is not stored.

When the still image automatic insertion operation is restarted, the camera microcomputer 15 outputs the digital clamp signal DC _S3 stored in the memory. Although the integrated photometric value IB _S cannot be obtained when the still image automatic insertion operation is restarted, the black level correction of the still image video signal E _S that is first output after the restart is performed by the above-mentioned device. It can be done well.

When the still image automatic insertion mode signal SI ₅ is output, the still image video signal E _S is integrated to obtain the integrated photometric value IB _S5 , the digital clamp signal DC _S5 is calculated, and a predetermined field delay occurs. Digital clamp signal DC
_S5 is output. The camera microcomputer 15 uses the integrated photometric value I
Since the AGC circuit 7a is turned on when B _S5 is obtained, the digital clamp signal DC _S5 is not stored and the digital clamp signal DC _S3 is held.

After all, in the example shown in FIG. 5, (A) immediately after the power is turned on, a signal obtained by adding an adjustment value to the digital clamp signal DC _M for the moving image is output as the digital clamp signal DC _S0 , and (B) AGC. Digital clamp signal DC obtained from integrated photometric value IB _S integrated when circuit 7a is OFF
_{When S} is stored and the signal DC _S stored before is erased, and (C) the still image automatic insertion operation is resumed after being temporarily stopped, the digital clamp signal DC _S stored last is output. To do.

Because of this, in the example of FIG.
A product for still images, such as immediately after turning on or when the automatic still image insertion operation is restarted.
Photometric value IB_SEven if you can't get the
Issue E _SIt is possible to satisfactorily correct the black level. Note that
FIG. 6 shows the operation shown in FIG. 5 as a flowchart.
Of.

<Second Example of Black Level Correction Operation of Still Image Video Signal> FIG.
Shows the operation of the second example. Dark brightness of the object in this example, AGC circuit 7a after power-on not even once to OFF, whereas, still image automatic insertion operation is stopped between the time t _4, t _5. The description of the operation of the part that performs the same operation as in the first example (FIG. 5) is simplified.

The first digital clamp signal DC _S0 is obtained by adding an adjustment value to the moving picture digital clamp signal DC _M. Although the digital clamp signals DC _S1 , DC _S2 , and DC _S3 are output, they are not stored because the AGC circuit 7a remains ON.

When the automatic still image inserting operation is stopped and then restarted, no digital clamp signal is stored in the camera microcomputer 15. Therefore, in such a case, the digital clamp signal DC _S00 is obtained by adding the adjustment value preset in the camera microcomputer 15 to the moving image digital clamp signal DC _M obtained in the immediately preceding field in the same manner as immediately after the power is turned on. To output this. By doing so, it is possible to favorably correct the black level of the still image video signal E _S even immediately after reactivating the automatic still image inserting operation.

<Third Example of Black Level Correction of Still Image Video Signal> FIG. 8 shows the operation of the third example. In this example, the camera microcomputer 15
Regardless of whether the AGC circuit 7a is ON or OFF, the digital clamp signal DC _S finally obtained is stored and the previously stored signal DC _S is erased. It should be noted that description of portions that perform the same operations as in the first example will be omitted.

The camera microcomputer 15 calculates the digital clamp signal DC _S4 from the integrated photometric value IB _S4 and stores it, but since the still image automatic insertion operation is stopped between times t _{4 and} t ₅ , the digital clamp signal DC _S4 is stopped. _Does not output DC _S4 . Then, when the automatic still image inserting operation is restarted, the digital clamp signal DC _S4 is read out from the memory and output, and the black level of the still image video signal E _S is corrected even immediately after the still image inserting operation is restarted. You can

In the third example, control can be performed without considering the operation of the AGC circuit 7a, so the control operation is simplified. The digital clamp signal DC _S4 is AG
There is a possibility that the value is changed by the gain value under the influence of the C gain, but it is stored at the end rather than outputting a digital clamp signal of a random value when the still image insertion operation is restarted. Digital clamp signal DC _S4
It is possible to perform stable black level correction by using.

<Fourth Example of Black Level Correction of Still Image Video Signal> FIG. 9 shows the operation of the fourth example. In this example, the camera microcomputer 15
Regardless of whether the AGC circuit 7a is ON or OFF, the two digital clamp signals DC obtained at the end and one before the last
Remember _S. It should be noted that description of portions that perform the same operations as in the first example will be omitted.

The camera microcomputer 15 stores two digital clamp signals DC _S3 and DC _S4 after time t ₄ . When the automatic still image inserting operation is restarted, the digital clamp signal DC _S3 is read out from the memory and output, and the black level of the still image video signal E _S is corrected even immediately after the still image inserting operation is restarted. You can Normally, the effect of AGC gain is more on the signal DC _S3 than on the signal DC _S4.
Is smaller, it is possible to perform better black level correction by using the signal DC _S3 .

<Embodiment of Video Camera Adjustment Method and Device> Next, an embodiment of a video camera adjustment method and device will be described with reference to FIGS. 1 and 10 to 14.

As shown in FIG. 1, the light source 31 and the EV are used for adjustment and setting at the manufacturing stage of the video camera described above.
A video camera adjustment device having an R jig 33 and a monitor 35 is used.

The light source 31 uses a tungsten lamp or the like, and as its power source 31a, an AC power source having the same frequency as the vertical synchronizing signal frequency of the video camera of 59.94 Hz is used. By matching the frequency of the AC power supply 31a with the frequency of the vertical synchronizing signal in this way, even if flicker occurs in the brightness of the illumination light from the light source 31, the flicker will be synchronized with the vertical synchronizing signal, and substantially. Equal to no flicker. On the other hand, it is conceivable to use a DC power supply as the power supply, but it is not always easy to obtain a DC power supply with no fluctuations in ripples and the like, so it is preferable to use the AC power supply 31a described above. Further, the brightness of the illumination light from the light source 31 is limited to a range in which the AGC circuit 7a is OFF, for example, a gain of 1. As a result, while making adjustments and settings, A
Since the gain of the GC circuit 7a becomes constant, it is possible to remove the adjustment or setting deviation caused by the gain variation.
The EVR jig 33 is an electronic variable setting unit provided in each of the still image amplifier 7c, the level adjusting circuit 7d, the offset adding circuit 8 and the camera microcomputer 15, so-called E.
A jig for setting a predetermined value for VR, which is connected to the corresponding circuits 7c, 7d, 8, 15. The usage will be described later. The monitor 35 displays the data of the digital clamp signal,
It is for monitoring color signals and integrated photometric values,
It is connected to the signal processing circuit 11 and the camera microcomputer 15. The usage will be described later.

Next, individual adjustments or settings at the manufacturing stage will be described with reference to FIGS.

<Setting of Adjustment Value for Camera Microcomputer>
In order to set the adjustment value for the camera microcomputer 15, a predetermined subject is photographed by using the light source 31 at the manufacturing stage of the video camera, and as shown in FIG. The image correction digital clamp signal data DC _S and the moving image correction digital clamp signal data DC _M are loaded into the EVR jig 33. EVR jig 33 calculates the difference D _def = DC _S -DC _M of both digital clamp data, the difference D
EEPROM of camera microcomputer 15 with _def as an adjustment value
The adjustment value is set by recording in the etc. When using a video camera after manufacturing, as shown in FIG.
When the first digital video signal for a still image after the image or a still image automatic insertion resume power-on is input to the signal processing circuit 11, the adjustment value D _{de f} camera microcomputer 15 set in EEPROM, the first th in addition to the digital clamp data DC _M based on video image signal output from the CCD5 before the digital video signal for a still image, a black level correction digital to said first th still picture digital video signal to which It is given to the digital signal processing circuit 11 as clamp data DC _S. Thereby, an appropriate digital clamp is performed.

<Adjustment of Blanking Level and Correction Coefficient for Color Signal> To set the operation for the level adjusting circuit 7d, a predetermined object is photographed by using the light source 31 in the manufacturing stage of the video camera, and FIG. As shown in, the data of both digital clamp signals for still image correction and moving image correction given from the camera microcomputer 15 to the digital signal processing circuit 11 are fetched into the monitor 35, and the difference between both monitored digital clamp data 35a is obtained. . And
While monitoring, the EVR jig 33 controls the blanking level of the level adjusting circuit 7d so that the difference becomes zero, and the operation is set. As a result, even if a level difference occurs between the video signals for a still image and the video for a moving image due to the influence of the switching of the mode changeover switch 7b, the levels of the luminance signals will be the same. But,
If left as it is, a level difference remains between the color signals. Therefore, the correction coefficient is set in the camera microcomputer 15 so as to eliminate the level difference between the color signals. Therefore, as shown in FIG. 12, the still image in the video signal V output from the digital signal processing circuit 11 is stopped. The image color signal and the moving image color signal are taken into the monitor 35, and the level difference between the two color signals 35b is obtained.
Then, while monitoring, the correction coefficient of the clamp data calculation for the still image color signal of the camera microcomputer 15 is determined by the EVR jig 33 so that this level difference becomes zero.
The correction coefficient is set by recording in the EEPROM or the like of the camera microcomputer 15. As a result, camera microcomputer 1
Reference numeral 5 adds, subtracts, or multiplies the correction coefficient set in the digital clamp data to be originally output to the signal processing circuit 11 only for the still image color signal to obtain the output value of the digital clamp data.

<Gain Setting of Still Image Amplifier> To set the gain of the still image amplifier 7c, a predetermined object is photographed by using the light source 31 at the manufacturing stage of the video camera, and the gain shown in FIG.
As shown in FIG. 3, the integration circuit 13 to the camera microcomputer 15
The difference between the integrated photometric value for still image correction and the integrated photometric value for moving image correction given to the
Take in 5. Then, while monitoring, the EVR jig 33 controls the gain of the still image amplifier 7c so that the difference between the integrated photometric values becomes zero. The data at that time is the same amplifier 7
The gain is set by recording it in the EEPROM or the like of the camera microcomputer 15 as the control value of the gain adjusting EVR of c. As a result, the screen brightness is the same between the still image video signal and the moving image signal.

<Setting of Offset Amount> In order to set the offset amount in the offset adding circuit 8, a predetermined object is photographed by using the light source 31 at the manufacturing stage of the video camera, and the setting shown in FIG.
As shown in FIG. 4, the output value of the digital clamp data is fetched from the camera microcomputer 15 to the EVR jig 33, the offset amount of the offset adding circuit 8 is controlled so that this becomes a predetermined value, and the offset data at this time is offset by the same offset value. The offset amount is set by recording in the EEPROM or the like of the camera microcomputer 15 as the control value of the offset adjusting EVR of the additional circuit 8. In this case, the offset amount offsets the analog video signal in order to surely convert the analog video signal input to the A / D converter 9 to the minimum value. Therefore, when offsetting, an offset amount corresponding to the offset amount given by the offset adding circuit 8 appears as a numerical value in the digital clamp data. Therefore, if the digital clamp data corresponding to the offset amount required for A / D conversion is defined in advance, when the digital clamp data output from the camera microcomputer 15 reaches a predetermined value, the appropriate offset amount will be an analog image. Will be given to the signal. Further, in this case, since the setting is performed using digital data, the accuracy is improved and the operation is simpler than the conventional waveform viewing by an oscilloscope.

[0085]

According to the first aspect of the present invention, in the manufacturing stage of the video camera, the difference between the clamp signal for still image correction at the time of inputting the video signal for a still image and the clamp signal for moving image correction at the time of inputting the video signal for a moving image is calculated. The black level of the first video signal for a still image after the power is turned on is output from the image pickup device earlier than that by obtaining the obtained value and recording it in the camera microcomputer in advance as a value corresponding to this difference. An adjustment value is added to the clamp signal obtained based on the generated moving image signal to form a clamp signal, which is sent to the signal processing circuit, so that it can be controlled appropriately. According to the second aspect of the present invention, at the manufacturing stage of the video camera, the difference between the still image correction clamp signal at the time of inputting the still image video signal and the moving image correction clamp signal at the time of inputting the moving image video signal is obtained, and the difference is obtained. The blanking level is adjusted in advance by the level adjusting circuit so as to be zero. Furthermore, the level difference between the color signal of the video signal for still images and the color signal of the video signal for moving images is obtained, and the correction coefficient of the camera microcomputer is determined so that the value becomes zero and recorded in advance in the camera microcomputer. As a result, it is possible to eliminate the level difference of the luminance signal and the level difference of the color signal caused by the influence of switching. According to the third aspect of the present invention, the difference between the integrated photometric value for still image correction and the integrated photometric value for moving image correction is calculated at the manufacturing stage of the video camera, and the gain of the amplifier circuit is preset so that the value becomes zero. . As a result, the brightness of the video signal for a still image and the brightness of the video signal for a moving image match without being affected by the shutter speed. According to the invention of claim 4, at the manufacturing stage of the video camera, the offset amount of the offset circuit is determined so that the still image correction digital clamp signal and the moving image correction digital clamp signal have predetermined values, and the offset amount is previously set in the offset addition circuit. Set. Thereby, an appropriate offset amount can be set easily and surely without observing the waveform. According to the invention of claim 5, the brightness of the illumination light is limited to a range where the gain of the auto gain control circuit of the video camera is equal to or less than a predetermined value at the time of photographing at the manufacturing stage, and the light source of the illumination light is set to the vertical direction of the video camera. It is driven by an AC power supply with the same frequency as the frequency of the synchronization signal. As a result, the adjustment or setting can be performed without being affected by the automatic gain control circuit and without being affected by the flicker of the light source.
In the invention of claim 6, the above-mentioned various adjustments and settings can be performed by one adjusting device.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a time chart showing signal states.

FIG. 3 is an explanatory diagram showing a divided state of a block for obtaining an integrated photometric value.

FIG. 4 is a flowchart showing an operation of stopping the automatic still image inserting operation.

FIG. 5 is a time chart showing a first example of the operation of the digital clamp.

FIG. 6 is a flowchart showing the operation of the first example.

FIG. 7 is a time chart showing a second example of the operation of the digital clamp.

FIG. 8 is a time chart showing a third example of the operation of the digital clamp.

FIG. 9 is a time chart showing a fourth example of the operation of the digital clamp.

FIG. 10 is an explanatory diagram of adjustment value setting.

FIG. 11 is an explanatory diagram of a digital clamp using adjustment values.

FIG. 12 is an explanatory diagram of adjustment for level difference removal.

FIG. 13 is an explanatory diagram of gain setting.

FIG. 14 is an explanatory diagram of offset amount setting.

[Explanation of symbols]

1 lens 3 iris 5 CCD 7 amplification circuit 7a AGC circuit 7b mode selector switch 7c still image amplifier 7d level adjustment circuit 8 offset addition circuit 9 A / D converter 11 digital signal processing circuit 13 integration circuit 15 camera microcomputer 17 iris driver 19 Still image automatic insertion switch 21 Still image automatic insertion control IC 23 Timing generator 31 Light source 31a AC power supply 33 EVR jig 35 Monitor SI Still image automatic insertion mode signal SS _S , SS _M Shutter speed switching signal I Still image insertion signal DC digital clamp Signal IB Integrated photometric value for black level correction

Claims (6)

[Claims] 1. When the brightness of a subject becomes brighter than a predetermined value, the high-speed electronic shutter operation of the image sensor is performed for each predetermined field to output a still image signal, and in other fields, the image sensor is operated at a normal shutter speed. To output a video signal for a moving image, and when the brightness of the subject becomes darker than a predetermined value, a video camera with a still image automatic insertion mode that sets the shutter speed of the image sensor to the normal shutter speed in all fields. In addition, the signal in the blanking period of the still image video signal is integrated to obtain an integrated photometric value for still image correction, and the signal in the blanking period of the video image signal is integrated to correct the moving image. The integrated circuit that determines the integrated photometric value for the still image and the still image video signal based on the clamp signal for still image correction when the still image video signal is input. A signal processing circuit that corrects and outputs a black level to the video signal based on the clamp signal for video correction when the video signal for the video is input. The clamp signal for still image correction is calculated based on the integrated photometric value for still image correction, and the clamp signal for video correction is calculated based on the integrated photometric value for video correction, and the still image is displayed in the signal processing circuit. When a video signal for input is input, a clamp signal obtained based on the video signal for a still image output from the image sensor before the video signal for a still image is sent to the signal processing circuit to perform the signal processing. A camera that, when a video signal for a moving image is input to the circuit, sends to the signal processing circuit a clamp signal obtained based on the video signal for a moving image output from the image pickup device before the video signal for the moving image. The camera microcomputer further includes: when the first still image video signal is input to the signal processing circuit after the video camera starts operating, the image pickup device is provided before the still image video signal. In a video camera configured to send a clamp signal obtained by adding a preset adjustment value to a clamp signal obtained based on a video signal for a moving image output from the video camera, a manufacturing step of the video camera. Then, a predetermined object is photographed and the difference between the still image correction clamp signal at the time of inputting the still image video signal and the moving image correction clamp signal at the time of inputting the video image signal for the moving image is obtained, and the value corresponding to this difference is calculated as A method of adjusting a video camera, wherein the adjustment value is recorded in the camera microcomputer in advance. 2. When the brightness of a subject becomes brighter than a predetermined value, the image pickup device operates the high-speed electronic shutter for each predetermined field to output a video signal for a still image, and in other fields, the image pickup device has a normal shutter speed. To output a video signal for a moving image, and when the brightness of the subject becomes darker than a predetermined value, a video camera with a still image automatic insertion mode that sets the shutter speed of the image sensor to the normal shutter speed in all fields. In addition, a level adjusting circuit that adjusts the blanking level of the video signal and the signal of the blanking period of the still image video signal are integrated to obtain the integrated photometric value for still image correction, and The integration circuit that integrates the signals in the blanking period of the signals to obtain the integrated photometric value for video correction, and that the video signal for still images is input In this case, the black level correction is performed on the still image video signal based on the still image correction clamp signal, and when the video signal is input, the black level correction is performed based on the video correction clamp signal. A signal processing circuit that corrects and outputs the black level of the video signal for the moving image, and calculates the clamp signal for still image correction using the preset correction coefficient based on the integrated photometric value for still image correction. When a clamp signal for moving image correction is calculated based on the integrated photometric value for moving image correction and a still image video signal is input to the signal processing circuit, the image pickup device outputs the still image video signal before the still image video signal. A clamp signal obtained based on the output still image video signal is sent to the signal processing circuit, and when the moving image video signal is input to the signal processing circuit,
A video camera having a camera microcomputer that sends a clamp signal obtained based on the video signal for a moving image output from the image pickup device before the video signal for a moving image to the signal processing circuit, the manufacturing step of the video camera Then, take a picture of a predetermined subject, find the difference between the clamp signal for still image correction when inputting the video signal for still image and the clamp signal for video correction when inputting the video signal for moving image, and set it to zero. In advance, the blanking level is adjusted by the level adjustment circuit, and further, the level difference between the color signal of the still image video signal and the color signal of the moving image video signal is obtained, and the camera is adjusted so that the value becomes zero. A method of adjusting a video camera, characterized in that a correction coefficient of a microcomputer is determined and recorded in advance in the same camera microcomputer. 3. When the brightness of a subject becomes brighter than a predetermined value, the image sensor is operated at high speed electronic shutter for each predetermined field to output a still image video signal, and in other fields, the image sensor is operated at a normal shutter speed. To output a video signal for a moving image, and when the brightness of the subject becomes darker than a predetermined value, a video camera with a still image automatic insertion mode that sets the shutter speed of the image sensor to the normal shutter speed in all fields. In addition, the amplifier circuit that amplifies the still image video signal with a preset gain integrates the blanking period signal of the amplified still image video signal to obtain the integrated photometric value for still image correction. In addition to the above, the integration circuit that calculates the integrated photometric value for video correction by integrating the signals in the blanking period of the video signal for video and the video signal for still image When the video signal is input, the black signal is corrected and output based on the clamp signal for still image correction, and when the video signal for video is input, it is output based on the clamp signal for video correction. A signal processing circuit that performs black level correction for this video signal and outputs it, and calculates a clamp signal for still image correction based on the integrated photometric value for still image correction, and also integrated photometric value for video correction. When a clamp signal for moving image correction is calculated based on, and a still image video signal is input to the signal processing circuit, the still image video output from the image sensor before the still image video signal is input. The clamp signal obtained based on the signal is sent to the signal processing circuit, and when the moving image signal is input to the signal processing circuit, the motion signal output from the image pickup device before the moving image signal is input. In a video camera having a camera microcomputer for sending a clamp signal obtained based on a video signal for use to the signal processing circuit, a predetermined subject is photographed at the manufacturing stage of the video camera, and an integrated photometric value for still image correction is obtained. And the integrated photometric value for moving image correction are obtained, and the gain of the amplifier circuit is preset so that the value becomes zero. 4. When the brightness of a subject becomes brighter than a predetermined value, the high-speed electronic shutter operation of the image sensor is performed for each predetermined field to output a still image video signal, and in other fields, the image sensor is operated at a normal shutter speed. To output a video signal for a moving image, and when the brightness of the subject becomes darker than a predetermined value, a video camera with a still image automatic insertion mode that sets the shutter speed of the image sensor to the normal shutter speed in all fields. In addition, an A / D converter that converts still image video signals and moving image video signals from analog signals to digital signals, and an offset amount preset in the analog video signals input to this A / D converter The offset addition circuit that adds the signal and the signal in the blanking period of the digital video signal for still images are integrated to perform integrated measurement for still image correction. An integrator circuit that calculates the light value and integrates the signals in the blanking period of the moving image digital video signal to obtain an integrated photometric value for moving image correction, and a still image correction signal when a still image digital image signal is input. The digital video signal for this still image is black level corrected based on the digital clamp signal of and output, and when the digital video signal for video is input, the digital clamp signal for video correction is used to output this digital video signal. A signal processing circuit that corrects the black level of the video signal and outputs it, and a digital clamp signal for still image correction is calculated based on the integrated photometric value for still image correction. When a digital clamp signal for moving image correction is calculated and the still image digital video signal is input to the signal processing circuit, A digital clamp signal obtained based on the still image digital video signal output from the image sensor before the image signal is sent to the signal processing circuit, and the moving image digital video signal is input to the signal processing circuit. Sometimes, in a video camera having a camera microcomputer that sends a digital clamp signal obtained based on the moving image digital image signal output from the image pickup device before the moving image digital image signal to the signal processing circuit, At the manufacturing stage of the video camera, a predetermined object is photographed, and the offset amount of the offset circuit is determined so that the still image correction digital clamp signal and the moving image correction digital clamp signal have predetermined values, and the same offset is added. A method for adjusting a video camera, characterized by being preset in a circuit. 5. The method of adjusting a video camera according to claim 1, wherein the brightness of the illumination light is limited to a range in which the gain of the auto gain control circuit of the video camera is equal to or less than a predetermined value at the time of shooting at the manufacturing stage. A method of adjusting a video camera, characterized in that the light source of the illumination light is driven by an AC power supply having the same frequency as the frequency of the vertical synchronizing signal of the video camera. 6. When the brightness of a subject becomes brighter than a predetermined value, the high-speed electronic shutter operation of the image sensor is performed for each predetermined field to output a still image video signal, and in other fields, the image sensor is operated at a normal shutter speed. To output a video signal for a moving image, and when the brightness of the subject becomes darker than a predetermined value, a video camera with a still image automatic insertion mode that sets the shutter speed of the image sensor to the normal shutter speed in all fields. In addition, an amplifier circuit that amplifies the still image video signal with a preset gain, and an A / D converter that converts the moving image video signal and the amplified still image video signal from an analog signal to a digital signal. An offset adding circuit for adding a preset offset amount to the analog video signal input to the A / D converter, and the offset adding circuit. A level adjustment circuit that adjusts the blanking level of the analog video signal input to the additional circuit, and a signal for the blanking period of the digital video signal for still images are integrated to obtain an integrated photometric value for still image correction. Based on the integration circuit that calculates the integrated photometric value for video correction by integrating the signals in the blanking period of the video digital video signal, and the digital clamp signal for still image correction when the digital video signal for still image is input. The black level of the digital video signal for still image is corrected and output, and when the digital video signal for video is input, the black level is corrected for the digital video signal for video based on the digital clamp signal for video correction. Signal processing circuit for correction and output, and digital clamp signal for still image correction is calculated based on the integrated photometric value for still image correction At the same time, the digital clamp signal for moving image correction is calculated based on the integrated photometric value for moving image correction, and when the still image digital image signal is input to the signal processing circuit, the digital image signal for the still image is more than the still image digital image signal. The digital clamp signal obtained based on the still image digital video signal previously output from the image pickup device is sent to the signal processing circuit, and when the video digital video signal is input to the signal processing circuit, A digital clamp signal obtained based on the moving image digital video signal output from the image pickup device before the digital video signal for use in the camera, and a camera microcomputer for sending to the signal processing circuit. When the first still image video signal is input to the signal processing circuit after the camera starts operating, Adjust the video camera that is configured to send a digital clamp signal obtained by adding a preset adjustment value to the digital clamp signal obtained based on the moving image signal output from the image sensor to the signal processing circuit. In the device for determining the difference between the digital clamp signal for still image correction and the digital clamp signal for moving image correction when a predetermined subject is photographed, a value corresponding to this difference is recorded in the camera microcomputer as the adjustment value. Means for calculating the difference between the digital clamp signal for still image correction and the digital clamp signal for moving image correction when a predetermined subject is photographed, and means for setting the operation of the level adjustment circuit so that the difference becomes zero. And the color signals of the digital video signal for a still image and the digital video signal for a moving image when a predetermined subject is shot. Means for determining the correction coefficient of the camera microcomputer so that the value becomes zero, and recording it in the camera microcomputer; and integrated photometric value for still image correction and moving image when a predetermined subject is photographed. A means for setting the gain of the amplifier circuit so that the difference is obtained from the correction integrated photometric value and the value becomes zero, and a digital clamp signal for moving image correction and a digital clamp signal for moving image correction when a predetermined subject is photographed. Means for determining the offset amount so that the clamp signal has a predetermined value and setting the offset amount in the offset adding circuit; and a range in which the brightness of the auto gain control circuit of the video camera is equal to or less than a predetermined value, and An illumination light source that is driven by an AC power supply having the same frequency as the frequency of the vertical synchronization signal of the video camera, and the adjustment of the video camera. Location.