JPS62245867A - Solid-state color television camera - Google Patents

Abstract

PURPOSE:To prevent the different timing of a video signal obtained from a color television camera depending on the state at power application by providing the 1st, 2nd and 3rd PLL circuits. CONSTITUTION:A television signal fed externally to an input terminal 1 is fed to a synchronizing separator circuit 2. The 1st PLL circuit consists of a phase shifter 3, a phase shift detector 4, a low pass filter 5, a VCO 6 and a synchronizing signal generator 7, and the 2nd PLL circuit consists of a phase detector 19, a low pass filter 20, a VCO 21, a counter circuit 22 and the phase detector 19. Further, the 3rd PLL circuit consists of the phase shifter 9, a phase detector 10, a low pass filter 11, a VCO 12 and a counter circuit 13. The output signal of the counter circuit 13 is fed to a color encoder circuit 14. The output signal of the VCO 21 is fed to a solid-state image pickup element drive circuit 18, operated with the output signal of one horizontal scanning period of the synchronizing signal generator 7 to obtain the horizontal tansfer pulse of a solid-state image pickup element.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an external synchronization method for synchronizing the scanning of a television camera to an externally supplied reference synchronization signal.

2. Description of the Related Art In the past, image pickup tubes have been used to convert light from an object image into video signals, but in recent years, solid-state image pickup devices have also come into use. The solid-state image sensor is a CCD type image sensor in which both the light receiving part and the signal readout part are charge-coupled devices, or a large number of photodiodes arranged in a lattice pattern.
There is an MO5 type image sensor that has a readout switch at each contact point and obtains a video signal by sequentially switching the readout switch, or an image sensor that has a photodiode as the light receiving part and a COD as the signal readout part. The above-mentioned image sensor in which the light receiving section is a photodiode and the signal reading section is a COD is also generally called a can-type solid-state image sensor. Since the structure and operation of these elements are well known, their explanation will be omitted.

A solid-state color television camera uses three solid-state imaging devices as described above and one three-color separation prism to capture a subject image, and obtains a 2-color television signal through electrical circuit processing. . This uses three conventional image pickup tubes.
The structure is very similar to a tube color television camera.

A color television camera is supplied with a standard color television signal (hereinafter referred to as a television signal) generated by another color video signal generating means (another color television camera, etc.) and changes its scanning timing and color subcarrier. It is necessary to synchronize the two phases of the frequency with the supplied television signal.Furthermore, in a color television camera, the timing of the video signal to be imaged can be arbitrarily changed in relation to the horizontal synchronization signal of the externally supplied standard television signal. things are required.

Further, the phase of the color subcarrier is also required to be arbitrarily changed with respect to the phase of the color subcarrier of the reference television signal.

From the viewpoint of operability of a color television camera, it is desirable that the timing of the video signal to be imaged and the phase of the color subcarrier can be adjusted independently. In other words, it is desirable that the timing of the video signal does not change even if the phase of the color subcarrier is adjusted, and that the phase of the color subcarrier does not change even if the timing of the video signal is adjusted.

In a conventional three-tube color television camera, each of the above adjustments can be made independently. In other words, in order to adjust the timing of the video signal to be imaged, it is sufficient to adjust the timing of the horizontal deflection timing pulse of the color television camera, and in order to adjust the phase of the color subcarrier, it is necessary to adjust the timing of the horizontal deflection timing pulse that is supplied to the encoder of the color television camera. The phase of the color subcarrier may be arbitrarily adjusted. Although the method of external synchronization of a conventional three-tube color television camera is well known, this method will be briefly explained here using FIG. 2.

In FIG. 2, 1 is an input terminal for television signals.

2 is a synchronous separation circuit, 3.9 is a phase shifter, 5.11 is a low-pass filter, 6.12 is a VCO (iF pressure controlled oscillator) 1
7 is a 910 frequency divider circuit, a synchronizing signal generator whose main constituent circuits are gate circuits, 13 is a counter circuit, 8 is a horizontal deflection circuit, and 14 is a color encoder.

A horizontal synchronization signal and a burst signal included in an externally supplied television signal inputted from a television signal input terminal 1 are separated by a synchronization separation circuit 2 . The separated horizontal synchronizing signal is supplied to a phase shifter 3 and phase-shifted at an arbitrary timing. The phase-shifted horizontal synchronization signal is supplied to a phase detector 4. The phase detector output signal is supplied to a low pass filter 5. The low pass filter output signal is provided to the VCOe. The vCO generates a signal whose frequency depends on the magnitude of the supplied voltage. The VCO oscillates a signal with a frequency approximately 910 times the horizontal scanning frequency.

The VCO output signal is supplied to a synchronization signal generator 7 and frequency-divided by 910.

The synchronization signal generator output signal is supplied to the phase detection circuit 4 and also to a trigger terminal (not shown) of the horizontal deflection circuit. The horizontal deflection circuit performs horizontal scanning in response to a trigger signal supplied to a trigger terminal.

Each circuit group from 1 to 7 creates a phase-locked loop (hereinafter referred to as P
(abbreviated as LL) is configured. Therefore, the two horizontal synchronizing signals supplied to the phase detector 4 are stable when their rising phases match, so by arbitrarily adjusting the phase of the horizontal synchronizing signals separated by the synchronizing separation circuit 2, the reference TV The phase of the video signal of the signal and the video signal imaged by the color television camera can be adjusted arbitrarily.

Although not shown, the simplest method is to arbitrarily adjust the phase of the horizontal synchronization signal obtained from the synchronization separation circuit to reset the horizontal scanning pulse generation counter (hereinafter abbreviated as horizontal counter) of the synchronization signal generator of the color television camera. There is a way to do that.

Next, phase adjustment of color subcarriers will be explained.

The burst signal separated by the synchronization separation circuit 2 is supplied to a phase shifter 9 and adjusted to an arbitrary phase. The phase-adjusted burst signal is supplied to a phase detector 1o. The phase detector output signal is supplied to a low pass filter 11. The low pass filter output signal is provided to V6O13. V
The CO generates a signal whose frequency depends on the magnitude of the supplied voltage.

The VCO oscillates a signal with a frequency approximately four times the color subcarrier frequency. The VCO output signal is supplied to the counter circuit 13 and frequency-divided by four. The counter circuit output signal is supplied to the phase detection circuit 1o and also to the color encoder circuit. The color encoder modulates the color signal with the supplied color subcarrier. PLL by each circuit group from 9 to 13
is configured.

Therefore, the two color subcarriers supplied to the phase detector 1Q are stable when their phases match, so by arbitrarily adjusting the phase of the burst signal separated by the synchronization separation circuit 2, the color of the reference television signal can be adjusted. It is possible to synchronize the phase of the subcarrier and the color subcarrier of the color television camera and adjust the phase arbitrarily.

However, when a solid-state image sensor is used as a photoelectric conversion element, in order to arbitrarily adjust the phase of the video signal of the reference television signal and the video signal imaged by the color television camera, it is necessary to use the solid-state image sensor for horizontal transfer. The clock pulse signal must also maintain a synchronous relationship with the horizontal synchronization signal of the television signal. A conventional method for producing a color television camera using a solid-state image sensor will be explained with reference to FIG.

A solid-state image sensor uses photoelectric conversion elements arranged two-dimensionally and reads out the signals from the photoelectric conversion elements to obtain a subject image, so the resolution of a color television camera is determined by the number of photoelectric conversion elements. be done. Therefore, the number of elements in the vertical direction is determined by the number of scanning lines of the color television camera, but the number of elements in the horizontal direction can be determined arbitrarily. Therefore, the number of elements in the horizontal direction is determined by considering the entire system of the color television camera. As a result, the number of elements in the horizontal direction is generally determined so that the horizontal transfer clock signal can be obtained from a signal that is an integral multiple of the color subcarrier.

Therefore, in the following description, it is assumed that the color television camera system is the NTSC system, the number of elements in the horizontal direction is 576, and the horizontal transfer clock is a signal (10.7 MHz) with a frequency three times that of the color subcarrier.

In Figure 3, 1 is a TV signal input terminal, 2 is a sync separation circuit, 3.9 is a phase shifter, 6.11 is a low-pass filter, 16.12 is a VCO (voltage controlled oscillator), and 7 is a sync signal generator. 13, 16, and 17 are counter circuits, 18 is a solid-state image sensor driving circuit, and 14 is a color encoder.

A horizontal synchronization signal and a burst signal included in an externally supplied television signal inputted from a television signal input terminal 1 are separated by a synchronization separation circuit 2 . The separated horizontal synchronizing signal is supplied to a phase shifter 3 and phase-shifted at an arbitrary timing. The phase-shifted horizontal synchronization signal is supplied to a phase detector 4. The phase detector output signal is supplied to a low pass filter 5. The low pass filter output signal is supplied to VCO 15. The vCO generates a signal whose frequency depends on the magnitude of the supplied voltage. The VCO oscillates a signal with a frequency approximately 2730 times the horizontal scanning frequency. The vGO output signal is supplied to the counter circuit 16 and frequency-divided by 3, and the output signal is supplied to the synchronization signal generator 7 and frequency-divided by 910.

The synchronizing signal generator output signal is supplied to the phase detection circuit 4 and also to the solid-state image sensor driving circuit 18. A signal obtained by frequency-dividing the output signal of the VCO 16 by four by a counter circuit 17 is also supplied to the solid-state image sensor driving circuit, and a horizontal transfer clock signal for the solid-state image sensor is obtained from these signals. PL by each circuit group of 1 to 5, 7, 16°16
L is configured.

Therefore, the two horizontal synchronization signals supplied to the phase detector 4 are stable when their rising phases match, so it is possible to adjust the phase of the horizontal synchronization signals separated by the synchronization separation circuit 2 arbitrarily. The phase of the video signal of the television signal and the video signal imaged by the color television camera can be adjusted arbitrarily. The solid-state image sensor drive circuit 18 includes a counter circuit 17. The output signals of the synchronization signal generators are combined to create horizontal transfer pulses for the solid-state image sensor.

In the NTSC system, the original oscillator output signal (1
4,318181aMHz) is divided by 4, 910, and 238875, respectively. Therefore, the rising phases of the original oscillator output signal and the horizontal synchronizing signal are the same, and the rising phases of the horizontal synchronizing signal and the color subcarrier signal are inverted every horizontal scan.

Problems to be Solved by the Invention By the way, the phase of the horizontal transfer clock signal and the horizontal synchronization signal obtained by the configuration shown in FIG. 3 depends on the state of the counter circuit when the power of the color television camera is turned on. There are several possible phase states.

This is because the horizontal transfer clock is obtained as mentioned above, so even if the horizontal synchronization signal inside the color television camera is synchronized (locked by the PLL circuit) with the externally supplied television signal, the power is turned on. The timing of the video signal obtained by the color television camera differs depending on the state of the camera, and the horizontal scanning timing must be adjusted every time the color television camera is powered on, which is inconvenient.

Furthermore, in order to synchronize the operation of a color television camera with a television signal supplied from the outside with the configuration shown in Figure 3, the oscillation frequency of the original oscillator must be an integral multiple of the color subcarrier. There is a drawback that the number of horizontal elements of a solid-state image sensor that can be used in a camera is limited.

The present invention solves the above-mentioned conventional drawbacks, and prevents the timing of the video signal obtained by the solid-state color television camera from varying depending on the state when the power is turned on. The aim is to remove restrictions on the number of horizontal elements of solid-state image sensors that can be used for

Means for Solving the Problems To solve the above problems, the solid-state color television camera of the present invention separates the horizontal synchronization signal from the reference standard color television signal supplied to the solid-state color television camera; A first PLL circuit obtains a horizontal synchronizing signal for the solid-state color television camera synchronized with the horizontal synchronizing signal, and a second PLL circuit obtains a horizontal scanning frequency synchronized with the second horizontal synchronizing signal. Obtain a horizontal transfer clock signal with an integer multiple of frequency, and use the third PLL circuit to
A color subcarrier synchronized with a burst signal separated from the reference standard color television signal is obtained.

Operation According to the above configuration, the horizontal synchronizing signal is separated from the reference standard color television signal supplied to the solid-state color television camera, and the separated horizontal synchronizing signal is supplied to the first PLL circuit. A signal of an integer multiple of 4 of the color subcarrier synchronized with a horizontal synchronization signal is obtained, and the frequency of the signal of an integer multiple of 4 of the color subcarrier is divided to obtain a horizontal synchronization signal or a signal of one horizontal scanning period. By supplying the signal of one horizontal scanning period thus obtained to the second PLL circuit to obtain a signal for horizontal transfer having an integral multiple of the horizontal scanning frequency synchronized with the signal of one horizontal scanning period, To prevent the timing of the video signal obtained by a color television camera from varying depending on the state when the power is turned on, and to limit the number of horizontal elements of a solid-state image sensor that can be used in a color television camera. Can be canceled.

Example An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a configuration diagram of an external synchronization circuit of a solid-state color television camera, a horizontal transfer clock pulse generation circuit of a solid-state image sensor, and a color subcarrier generation circuit according to the present invention.

In FIG. 1, 1 is a television signal input terminal, 2 is a synchronous separation circuit, 3 and 9 are phase shifters, and 5 and 11.

20 is a low-pass filter, 6, 12.21 is a VCO (voltage controlled oscillator), and 13.22 is a counter circuit.

7 is a synchronizing signal generator, 18 is a solid-state image sensor driving circuit, 1
4 is a color encoder, and 4, 10.19 is a phase detection circuit.

A signal supplied from the outside to a television signal input terminal 1 is supplied to a synchronization separation circuit 2. The output signal of the synchronous separation circuit 2 is supplied to a phase shifter 3, and the phase shifter output signal is supplied to a phase detector 4. The phase detector output signal is passed through a low-pass filter 6
and the low-pass filter output signal is vcols
supplied to

The VCO output signal is supplied to a synchronizing signal generator 7, and its output signal is supplied to a phase detection circuit 4 and a solid-state image sensor driving circuit 18. A PLL circuit is configured by the circuit groups 1 to 7 above.

The output signal of the synchronization signal generator 7 is supplied to the phase detector 19, and the phase detector output signal is supplied to the low-pass filter 2o (
The low-pass filter output signal is supplied to the VCO 21. The VCO output signal is supplied to a counter circuit 22, and its output signal is supplied to a phase detector 19. VC
The output signal of O21 is supplied to the solid-state image sensor drive circuit 18. A PLL circuit is constituted by this group of 19 to 220 circuits.

Furthermore, the output signal of the synchronous separation circuit 2 is supplied to a phase shifter 9, the phase shifter output signal is supplied to a phase detector 10, the phase detector output signal is supplied to a low-pass filter 11, and the low-pass filter output signal is , are supplied to the VCO 12. v
The CO output signal is supplied to a counter circuit 13, and its output signal is supplied to a phase detection circuit 10 and a color encoder circuit 14. These circuit groups 9 to 13 constitute a PLL circuit.

Next, the operation of the embodiment according to the present invention will be explained.

A horizontal synchronization signal and a burst signal contained in an externally supplied television signal inputted from a television signal input terminal 1 are separated by a synchronization separation circuit 2 . The separated horizontal synchronization signal is supplied to a phase shifter 3, and is phase-shifted at an arbitrary timing relative to the horizontal synchronization signal of the television signal, which is a reference signal. The phase-shifted horizontal synchronization signal is supplied to a phase detector 4. Although not shown here, when the output signal of the phase shifter 3 is supplied to the phase detector 4, the vertical synchronization signal and equivalent pulse contained in the one-separated synchronization signal are removed by a simple method such as a one-shot multivibrator. (This is to operate the PLL circuit stably.) Furthermore, the obtained phase detector output signal is supplied to a low-pass filter 5 to remove unnecessary high-frequency components.

The low pass filter output signal is provided to the VCOes. A VCO exhibits a change in frequency depending on the magnitude of the supplied voltage. Its oscillation frequency is approximately 9 times the horizontal scanning frequency.
This is 10 times the frequency. The vC0 output signal is a synchronization signal generator 7 whose main constituent circuits are a counter circuit and a gate circuit.
The synchronizing signal generator output signal, which is supplied to and frequency-divided by 910, is supplied to the phase detection circuits 4 and 19 as well as to the solid-state image sensor driving circuit 18. Therefore, the phase detector 4
Two signals (phase shifter 3 and synchronization signal generator 7) supplied to
Since the output signal (output signal of The phase of the horizontal synchronization signal of the color television camera can be set arbitrarily.

Next, a method of obtaining a horizontal transfer pulse whose phase is matched (locked) to the rising edge of the horizontal scanning start timing (eg, horizontal drive signal, ID) pulse of the synchronization signal generator 7 will be explained.

The output signal of the synchronization signal generator 7 is supplied to a phase detection circuit 19, and the phase detector output signal is supplied to a low-pass filter 20 to remove unnecessary high-frequency components. The low-pass filter output signal is supplied to the VCO 21. VCQ exhibits a change in frequency depending on the magnitude of the supplied voltage. The oscillation frequency is approximately 680 times the horizontal scanning frequency. V
The output signal of CO21 is supplied to the counter circuit 22 for 6s.
The output signal of the counter circuit 22 is frequency-divided and supplied to the phase detector 19.

Since a t-envy PLL circuit is configured in each of the circuits 19 to 22, the two signals supplied to the phase detector 19 (the output signals of the synchronization signal generator 7 and the counter circuit 22) have the same rising phase. The output signal of the synchronizing signal generator (phase detector 19
The input signal of the VCO 21) and the output signal of the VCO 21 always have the same phase. Therefore, the output signal of vC021 is supplied to the solid-state image pickup device drive circuit 18, and is operated on the output signal of one horizontal scanning period of the synchronization signal generator 7 to obtain the horizontal transfer pulse of the solid-state image pickup device.

Here, the reason why the frequency division ratio of the counter circuit is 680 is because the horizontal transfer clock frequency is 10.7 MH.
This is a value when z is used, and the number of effective elements in the horizontal direction of the solid-state image sensor (which performs photoelectric conversion) is approximately 670 elements. The frequency division ratio can be arbitrarily set depending on the number of elements in the horizontal direction of the solid-state image sensor.

Since the phase adjustment of the color subcarrier is the same as in the conventional example, detailed explanation will be omitted.

Effects of the Invention As described above, according to the present invention, the phenomenon in which the timing of the video signal obtained by a color television camera differs depending on the state when the power is turned on does not fundamentally occur. There is no need to adjust the horizontal scanning timing. Furthermore, it is possible to remove the restriction on the number of horizontal elements of a solid-state image sensor that can be used in a color television camera.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a synchronization circuit of a solid-state color television camera according to an embodiment of the present invention, and FIGS. 2 and 3 are block diagrams of a synchronization circuit of a conventional solid-state color television camera. 1...TV signal input terminal, 2...
Synchronous separation circuit, 3, 9... Phase shifter, 5, 11.
20...Low pass filter, 6,12.21.
...VCO (voltage controlled oscillator), 13.22...
...Counter circuit. 7...Synchronization signal generator 118...Solid-state image sensor drive circuit, 14...Color encoder, 4,10°19...Phase detection circuit.

Claims (2)

[Claims] (1) A solid-state image pickup device that has photoelectric conversion elements arranged two-dimensionally and a scanning section that scans in the horizontal and vertical directions, and the transfer lock frequency of the horizontal scanning is an integral multiple of the horizontal scanning frequency. separating a horizontal synchronization signal from a reference standard color television signal supplied to the solid-state color television camera used, and supplying the separated horizontal synchronization signal to a first PLL circuit to synchronize with the horizontal synchronization signal. A solid-state collar characterized in that a signal of one horizontal scanning period is obtained, the signal of the one horizontal scanning period is supplied to a second PLL circuit, and a signal for a transfer clock synchronized with the signal of the one horizontal scanning period is obtained. television camera. (2) Use a solid-state image sensor that has two-dimensionally arranged photoelectric conversion elements and a scanning section that scans in the horizontal and vertical directions, and the transfer clock frequency for the horizontal scanning is an integral multiple of the horizontal scanning frequency. separating a horizontal synchronization signal from a reference standard color television signal supplied to a solid-state color television camera, and supplying said separated horizontal synchronization signal to a first PLL circuit, which is synchronized with said horizontal synchronization signal; Obtain a signal with a horizontal scanning period, supply the signal with the one horizontal scanning period to a second PLL circuit, obtain a signal for a transfer clock synchronized with the signal with the one horizontal scanning period, and set the reference standard color television. separating a burst signal from the signal and supplying the separated burst signal to a third PLL circuit;
A solid-state color television camera characterized in that a color subcarrier synchronized with the burst signal is obtained.