JPH05328167A - Power supply synchronization system for 50hz - Google Patents

Abstract

PURPOSE:To obtain a CCD camera capable of being line-locked even at districts whose commercial power supply frequency is 50Hz. CONSTITUTION:A frequency 50Hz of a commercial peer supply received from a power supply input terminal 12 is subjected to 1/5 frequency division by a frequency divider 13 and a phase comparator 14 compares the phase with a phase of an output of a 1/6 frequency divider 23. A detection voltage in accordance with the phase difference controls an oscillated frequency from a VCO 15, the frequency is converted by a synchronizing signal generator 17 and the result is subjected to 1/6 frequency division by the 1/6 frequency divider 23 through a phase comparator 14 again. Since the phase is not always in matching with a reference frequency 50Hz of a camera, a V phase adjustment switch 22 is adjusted in the manual mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present technology relates to a vertical sync signal generation method for an NTSC CCD camera.

[0002]

2. Description of the Related Art Conventionally, in the case of monitoring or recording an image by switching a plurality of CCD cameras, if the vertical synchronizing signals between the cameras do not match, the image will be disturbed when the cameras are switched. Therefore, the following method has been used to match the vertical synchronization signals between the cameras. The above method is called a line lock method. In this method, the vertical synchronizing signal frequency of the NTSC method is 60 Hz and the frequency of the commercial power source is 60 Hz. The vertical synchronizing signals between the two are combined. However, the line lock method has a drawback that synchronization cannot be achieved in an area where the frequency of the commercial power source is 50 Hz. The reason why the above defects occur will be described below with reference to FIG. 1 is a waveform diagram of a commercial power source having a frequency of 50 Hz, and 4 and 7 are waveforms of vertical synchronization signals of the two CCD cameras. In Fig. B, the line lock of 4 is applied at the time indicated by 2 of 50Hz in Fig. A, and from that time point onward, the vertical synchronizing signal of the camera 4 is generated by the built-in 60Hz transmitter. The vertical synchronizing signal of the camera 7 shown in FIG.
It takes at the time point shown by
The vertical synchronizing signal of the camera 7 shall be generated by the Hz transmitter. At the time point after one cycle of 50 Hz shown in FIG. A, 60 Hz between the camera 4 and the camera 7
The vertical sync signals can be out of phase with each other by the amount indicated by 8. When the cameras are switched to each other, the above-mentioned phase shift has a problem that it causes image disturbance.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems. Even in an area where the frequency of the commercial power source is 50 Hz, the vertical lock signal of the vertical synchronizing signal of the NTSC system can be locked. Another object of the present invention is to provide a synchronizing signal generator and a changeover switcher which can automatically apply vertical synchronizing between cameras by using the vertical synchronizing signal generator.

[0004]

In order to solve the above-mentioned problems, the present invention provides a commercial power source having a frequency of 50 Hz divided by 5 and a camera internal 60 Hz divided by 6.
The mutual phase difference is compared, a clock pulse is generated by a voltage according to the phase difference, and the clock pulse is generated for 60H.
In addition to the V phase adjustment switch by converting to z, the line lock can be applied by switching the switch in the manual mode. When the V phase adjustment switch is used in the auto mode, a plurality of CCs are used.
The vertical synchronization between D cameras can now be automatically adjusted.

[0005]

With the above structure, the NT according to the present invention
In the SC type vertical sync signal CCD camera, the line lock can be applied even in a region where the frequency of the commercial power supply is 50 Hz.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS NTSC in the area where the commercial power source of the CCD camera according to the present invention is 50 Hz based on the following drawings.
An embodiment of how to lock the line of the vertical synchronizing signal by the method will be described in detail. FIG. 1 shows a block of a line lock circuit inside a CCD camera. 12 is a line input of a commercial power supply whose frequency is 50 Hz, and 13 is 5
A frequency divider, 14 is a phase comparator, 15 is a VCO circuit that varies the frequency by a DC voltage according to the phase difference, 16 is a clock frequency generator, 17 is a synchronization signal generator, and 20 is an auto signal generator. And a manual selector switch, 21 is an external terminal in the auto mode, 22 is a V-phase adjusting switch, and 23 is a 6-divider. FIG. 2 is a block in which a plurality of cameras 51 to 53 with built-in V phase adjustment switches and a monitor changeover switcher with an automatic V phase adjustment function are combined when the line lock circuit is operated in the automatic mode. It is a figure.

Next, the operation of applying the line lock according to the present invention will be described with reference to FIG. 1. The commercial power supply of 50 Hz taken in from 12 is divided by 5 into 13, and then the phase is changed at 14. Be compared. The detected voltage according to the phase difference controls the oscillation frequency of the VCO of 15, and the oscillation frequency is converted into the master clock by the clock frequency generator of 16. The master clock is frequency-converted by a synchronization signal generator 17 and then V phase adjustment switch 22
Through, it is divided by 6 by 23 dividers 6 and then again phase-compared by 14 phase comparators, thus the above loop is repeated until the respective phases match. If the results of the phase comparisons match, then the output of the 17 sync signal generator is locked by the 50 Hz of the line, and the frequency of the output of the sync signal generator is 6
Although it is 0 Hz, the phase does not always match 50 Hz of other cameras, so in manual mode,
The V phase adjustment switch 22 is adjusted to match the phase of another camera as a reference while looking at the screen. The V phase adjustment switch 22 is not a volume switch but a switch that can be switched in 6 steps, as shown in FIG. According to the timing diagram, the phase shift between the line 50 Hz and the sync signal 60 Hz is
The maximum is 6 types, and the 7th type overlaps with the starting point again. In the case of the auto mode shown in FIG. 2, first, the reference synchronizing signal of the camera 51 is phase-matched with the line 50 Hz in the manual mode, and then superimposed on the video signal to automatically adjust the vertical synchronizing signal phase. Sent to a monitor changeover switcher with a function, superimpose 60 Hz inside the camera 52 on the side where one phase is to be matched with a video signal, and send it to the monitor changeover switcher with a vertical synchronizing signal phase automatic adjustment function, A phase comparison is performed at 56 inside the switcher, and a control pulse corresponding to the phase difference is sent at 55 to the vertical synchronization signal phase adjustment switch inside the camera 52 to automatically adjust the phase. When the phase adjustment of the camera 52 is completed in this way, the contact point of the switch 54 is connected to the camera 53 side and the phase of the camera 53 is adjusted next.

[0008]

As described above, C according to the present invention
According to the line lock system of the CD camera, the line lock can be applied even in an area where the frequency of the commercial power supply is 50 Hz, so that the line lock can be performed by the power supply synchronization system common throughout the world.

[Brief description of drawings]

FIG. 1 is a block diagram of a line lock circuit inside a CCD camera according to the present invention.

FIG. 2 is a configuration diagram of a monitor changeover switcher with a V-phase automatic adjustment function and a camera according to the present invention.

FIG. 3 is an explanatory diagram of the timing when the phase shifts when line lock is applied at 50 Hz.

[Explanation of symbols]

 11 Block of line lock circuit inside CCD camera 12 Commercial power input 13 5 Frequency divider 14 Phase comparator 15 VCO circuit 17 Sync signal generator 22 V Phase adjustment switch 23 6 Frequency divider

Claims (1)

[Claims] 1. A CCD camera having a line lock function for adjusting vertical synchronization between a plurality of CCD cameras, and a CCD camera having the line lock function, which is incorporated in a commercial power supply in a region of a frequency of 50 Hz. Also,
In the manual mode, when the vertical sync signal generator for 50 Hz with a vertical sync signal phase adjustment switch (hereinafter referred to as a V phase adjustment switch) that operates the line lock function and the V phase adjustment switch are in the automatic mode The 50Hz power supply synchronization method that is configured by a monitor changeover switcher with a V phase automatic adjustment function that can automatically adjust the vertical synchronization between a plurality of CCD cameras.