JPH04326873A - Video camera system - Google Patents

Abstract

PURPOSE:To automate the frequency compensation of a video signal by detecting the length of a cable on the basis of a signal to be a standard, and giving the frequency compensation corresponding to this length to the video signal. CONSTITUTION:In a video camera system in which a camera head part and a camera main body 2 are connected by the cable 3, a cable compensation circuit 10 is constituted of a frequency characteristic compensation circuit 11 which has a frequency compensation characteristic for the cables 3 of plural lengths and compensates the frequency characteristic of the video signal and a control circuit 20 to control the frequency characteristic compensation circuit 11 in accordance with the length of the cable 3. In this case, the control circuit 20 detects the length of the cable 3 on the basis of time during which a horizontal synchronizing signal goes and returns along the cable 3. Further, the frequency characteristic compensation circuit 11 compensates the frequency characteristic of the video signal from the camera head part 1 in accordance with the cable length detected by the control circuit 20. Accordingly, the frequency compensation not fitting the actual length of the cable 3 due to the forgetting of operation and the misoperation of a user can be prevented.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a video camera system, and in particular, to a video camera system in which a camera head and a video camera body are connected by a cable, the present invention is for compensating for deterioration in the frequency characteristics of a video signal caused by the cable. .

0002

2. Description of the Related Art As shown in FIG. 3, a video camera system includes a camera head unit 31 that outputs a video signal (hereinafter referred to as a video signal), and a camera controller (hereinafter referred to as a CCU: Camera
The camera body 3 has a power source that supplies power to the camera head section 31 (referred to as a control unit) and the camera head section 31.
2, and a cable 33 that connects the camera head section 31 and the camera body 32.

The camera head section 31 has a so-called CCD image sensor, reads out an imaging signal from the CCD image sensor in synchronization with a horizontal synchronization signal supplied from the camera body 2, and superimposes a horizontal synchronization signal on the imaging signal. It is designed to form and output a video signal. Further, the camera head section 31 is configured such that lens aperture, filter selection, etc. are remotely controlled by control signals sent from the camera body 2.

The CCU of the camera body 32 is configured to perform various signal processing on the video signal supplied via the cable 3, such as cable compensation, contour correction, gamma correction, knee characteristics, and pedestal level. Further, the aperture of the lens of the camera head section 31, selection of filters, etc. are controlled by remote control.

The cable 33 is made of, for example, a 26-core cable, and transmits power and control signals from the camera body 32 to the camera head section 31, and also transmits a video signal obtained by photographing a subject from the camera head section 31. It is designed to be sent to the camera body 32.

That is, in a video camera system that is permanently installed in a studio, for example, a camera head section 31 is placed in the studio, a CCU and the like are placed in a so-called sub-adjustment area, and a cable 3 connects them. Also,
For example, even in a portable video camera system, the camera head section 31 and the camera body 32 can be separated in consideration of mobility, and the cable 3 is used to connect them.

In the conventional video camera system, the cable compensation circuit in the CCU of the camera body 32 has, for example, 2
The unit (step) is 5m, and each length has 25
There are four cable compensators with frequency compensation characteristics corresponding to 50 m, 50 m, 75 m, and 100 m, respectively, and the cable compensator according to the cable length being used can be selected manually. .

[0008]

[Problems to be Solved by the Invention] However, in a video camera system as described above in which the camera head section and the camera body equipped with a CCU, etc. are separated and used by connecting them with a cable, it is difficult for the operator to control the operation. Sometimes they were forgotten or made incorrectly and a cable compensator was selected that did not match the actual length of the cable being used.

Furthermore, in recent years, devices have become smaller (compact), and there are fewer places on the operation panel of the camera body 32 to attach various adjustment switches and the like. That is, it has become difficult to install, for example, a changeover switch for selecting the above-mentioned cable compensator.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a video camera system that can automatically compensate the frequency of a video signal according to the cable length.

[0011]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a video camera system in which a camera head section and a video camera body are connected by a cable.
cable length detection means for detecting the length of the cable based on the time that the reference signal travels back and forth through the cable; and cable compensation means for compensating accordingly.

0012

[Operation] In the video camera system according to the present invention, the length of the cable connecting the camera head and the video camera body is detected, and the frequency characteristics of the video signal from the camera head are automatically adjusted according to the cable length. to be compensated for.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a video camera system according to the present invention will be described below with reference to the drawings.

The video camera system of this embodiment, as shown in FIG.
The camera body 2 includes a camera body 2 having a power source for supplying power to the camera head unit 1 ) and the camera head unit 1, and a cable 3 connecting the camera head unit 1 and the camera body 2. In this video camera system, a video signal obtained by photographing a subject with the camera head unit 1 is supplied from the camera head unit 1 to the camera body 2 via a cable 3, and is sent to the cable 3 by the CCU of the camera body 2. After the resulting deterioration in frequency characteristics is compensated for, predetermined signal processing is performed and the signal is output via the terminal 4.

The camera head section 1 is, for example, a so-called CC
It has a D image sensor, operates with power supplied from the camera body 2, reads out the imaging signal from the CCD image sensor in synchronization with the horizontal synchronization signal supplied from the camera body 2, and performs horizontal synchronization with the imaging signal. The signals are superimposed to form a video signal, and the lens aperture, filter selection, etc. are remotely controlled by control signals sent from the camera body 2.

The CCU of the camera body 2 includes a cable compensation circuit 10 and a signal processing circuit 3 that performs various signal processing such as contour correction, gamma correction, knee characteristics, and pedestal level.
0. And this CCU is connected to cable 3
After frequency compensation is applied to the video signal supplied via the cable 3 according to the length of the cable 3, signal processing such as contour correction and gamma correction is performed on the video signal, and the signal is output via the terminal 4. Further, the aperture of the lens of the camera head section 1, selection of filters, etc. are controlled by remote control.

The cable compensation circuit 10 has frequency compensation characteristics for cables of a plurality of lengths, and includes a frequency characteristic compensation circuit 11 for compensating the frequency characteristics of a video signal, and a frequency characteristic compensation circuit 11 for compensating the frequency characteristics of a video signal. It is composed of a control circuit 20 that controls according to the following.

The control circuit 20 includes a synchronization signal generation circuit 21 that generates a reference horizontal synchronization signal SYNCREF, and a synchronization signal detection circuit 22 that detects a horizontal synchronization signal SYNCRET from the video signal supplied via the cable 3. and a pulse generation circuit 23 that is reset by the horizontal synchronization signal SYNCRET from the synchronization signal detection circuit 22.
and horizontal synchronization signal SY from the synchronization signal generation circuit 21.
NCREF and a phase detection circuit 24 that detects the phase of the pulse signal from the pulse generation circuit 23, an integration circuit 25 that smoothes the output of the phase detection circuit 24, and a DC amplifier circuit that amplifies the output of the integration circuit 25. 26, a comparator 28 that compares the output of the DC amplifier circuit 26 with the reference voltage from the reference voltage generation circuit 27 with a so-called hysteresis characteristic, and encodes the comparison result of the comparator 28, and generates the encoded control signal. The above frequency characteristic compensation circuit 1
1, and an encoder 29 that supplies data to The control circuit 20 receives the horizontal synchronizing signal SYNCREF from the synchronizing signal generating circuit 21 and the horizontal synchronizing signal SYNCCRE included in the video signal supplied via the cable 3.
The length of the cable 3 is detected based on the phase of T, and the frequency characteristic compensation circuit 11 is controlled so that frequency compensation is performed according to the length of the cable 3.

The cable 3 is made of, for example, a 26-core cable, and sends power from the camera body 2, control signals for controlling the lens aperture, etc., horizontal synchronization signals, etc. to the camera head 1, and also A video signal obtained by photographing is sent from the camera head section 1 to the camera body 2.

Next, the principle of cable compensation in the video camera system configured as above will be explained.

The horizontal synchronizing signal SYNCRET detected by the synchronizing signal detecting circuit 22 is different from the horizontal synchronizing signal SYNCREF from the synchronizing signal generating circuit 21 on the cable 3.
By reciprocating, for example, as shown in FIG. 2, the detection is delayed by a time t1. Specifically, usually 100m
A delay of 1 μs occurs per time.

The pulse generating circuit 23 generates a horizontal synchronizing signal SY.
It outputs a pulse signal that rises (set) earlier than NCREF by, for example, time t2, and is reset at the rise of horizontal synchronizing signal SYNCREF. That is, this pulse generating circuit 23 has a so-called detection window corresponding to the time t2, and the delay time t
1 is reliably detected. Then, the pulse generation circuit 23 supplies a pulse signal having information on the delay time t1 to the phase detection circuit 24.

The phase detection circuit 24 falls, for example, at the fall of the horizontal synchronizing signal SYNCREF from the synchronizing signal generating circuit 21, and falls at the falling of the pulse signal from the pulse generating circuit 23, for a time corresponding to the delay time t1. A pulse signal at a high level (hereinafter referred to as H level) is output to the integrating circuit 25.

The integrating circuit 25 smoothes the pulse signal from the phase detection circuit 24 to obtain an average value of this signal, and supplies the average value to the comparator 28 via the DC amplifier circuit 26. That is, when the cable 3 is long, the H level period of the pulse signal from the phase detection circuit 24 is long, and the DC output level of the integrating circuit 25 is high.

The comparator 28 compares the DC output level of the DC amplifier circuit 26 with the threshold value TH from the reference voltage generation circuit 27.
The DC voltages are compared, and the comparison result is supplied to the encoder 29. Specifically, the reference voltage generation circuit 27 generates the cables 3 having respective lengths of 12.5 m, 37.5 m, 62 m, .
Threshold values TH1 and T corresponding to 5m and 87.5m, respectively
H2, TH3, TH4 are supplied to the comparator 28, and the comparator 28 supplies these threshold values TH1 to TH
4 and the DC output level of the DC amplifier circuit 26, and it is determined that the length of the cable 3 currently used is, for example, 12
．． 5m or less, 12.5m to 37.5m, 37.5m to 6
It is detected whether the distance corresponds to 2.5 m, 62.5 m to 87.5 m, or 87.5 m or more. Further, at this time, the comparator 28 has a hysteresis characteristic, so that the detection result does not become uncertain when the length of the cable 3 is exactly equivalent to the threshold values TH1 to TH4.

The encoder 29 controls the frequency characteristic compensation circuit 11 based on the comparison result from the comparator 28. Specifically, the frequency characteristic compensation circuit 11 is configured such that, for example, 0
Cable compensator 1 having frequency compensation characteristics for cables with lengths of m, 25 m, 50 m, 75 m, and 100 m
1a, 11b, 11c, 11d, and 11e, and the encoder 29 adjusts these cable compensators 11a to 11e based on the detected cable length, for example, if each length of the cable 3 is 12.5 m or less, 12 .5m~37.5m,
37.5m~62.5m, 62.5m~87.5m, 8
Cable compensators 11a and 11b for 7.5m or more
, 11c, 11d, and 11e. The frequency characteristic compensation circuit 11 performs frequency compensation on the video signal supplied via the cable 3 by using a cable compensator selected according to the length of the cable, for example, to further amplify highly attenuated high frequency components. .

This frequency compensated video signal is supplied to a signal processing circuit 30. The signal processing circuit 30 performs signal processing such as contour compensation and gamma correction on this video signal and outputs it via the terminal 4.

As described above, in the video camera system in which the camera head section 1 and the camera body 2 are connected by the cable 3, the length of the cable 3 is detected based on the time t1 for the horizontal synchronization signal SYNC to travel back and forth through the cable 3. However, by applying frequency compensation to the video signal according to the cable length, the frequency compensation of the video signal can be automatically performed according to the cable length. Therefore, it is possible to prevent the operator from forgetting an operation or performing an erroneous operation, thereby preventing frequency compensation from being performed that does not match the length of the cable actually used. Further, there is no need to provide a changeover switch for selecting a cable compensator in a conventional video camera system, and the device can be made more compact.

It should be noted that the present invention is not limited to the above-described embodiment; for example, the horizontal synchronizing signal SYNCRET sent from the camera head section 1 to the camera body 2 may be sent on a line separate from the line for sending the video signal. You may also do so. Also,
For example, as a signal to detect the length of a cable,
It is not limited to horizontal synchronization signals.

[0030]

Effects of the Invention As is clear from the above description, in the present invention, in a video camera system in which a camera head and a video camera body are connected by a cable, a reference signal, such as a horizontal synchronization signal, is sent back and forth along the cable. By detecting the cable length based on time and applying frequency compensation to the video signal according to the length, it is possible to automatically perform frequency compensation of the video signal according to the cable length. Therefore, it is possible to prevent the operator from forgetting an operation or performing an erroneous operation, thereby preventing frequency compensation from being performed that does not match the length of the cable actually used. Further, there is no need to provide a changeover switch for selecting a cable compensator in a conventional video camera system, and the device can be made more compact.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing main parts of the configuration of a video camera system to which the present invention is applied.

FIG. 2 is a time chart for explaining the principle of cable compensation.

FIG. 3 is a block diagram showing the configuration of a conventional video camera system.

[Explanation of symbols]

1...Camera head part 2...Camera body 3...Cable 10...Cable compensation circuit 11...Frequency characteristic compensation circuit 20...control circuit

Claims (1)

[Claims] Claim 1: A video camera system in which a camera head and a video camera body are connected by a cable,
cable length detection means for detecting the length of the cable based on the time that the reference signal travels back and forth through the cable; and cable compensation means for compensating accordingly.