JPH03151768A - Synchronizing system for television camera - Google Patents

Abstract

PURPOSE:To take synchronization between television cameras without need of wiring other than power wire between television cameras by applying a pulse signal of a specific period to the power wire generated by a pulse generator and superimposing a pulse voltage onto a power voltage. CONSTITUTION:An output terminal 19 of a pulse generator 11 of a reference signal generator 10 connects to a drawing line 51 to the reference signal generator 10 from a power wire 50 and an output signal of 60Hz from the pulse generator 11 is applied superimposingly onto a power voltage. A pulse detector 21 extracting a pulse signal superimposed on the power voltage is incorporated to a television camera 20, an output signal of the pulse detector 21 is sent to a phase locked loop transmission circuit 42 in a camera circuit 41 and a vertical synchronizing signal of the television camera synchronously with the pulse signal detected by the pulse detector 21 is outputted from the oscillation circuit 42. Thus, each of television cameras 20 using the same power supply applies vertical synchronization of the screen in the same timing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for synchronizing television cameras, and more particularly to a method for synchronizing the vertical synchronization of a plurality of television cameras.

rPrior art] Today, in order to match the synchronization timing between television camera devices, an external synchronization method is adopted in which a reference signal for synchronization is input from the outside to the television camera, and the reference signal for synchronization is output. In many cases, a separate reference signal generator is used to connect the reference signal generator and each television camera with reference signal wiring for inputting the output signal of the reference signal generator to each television camera. In addition, in television camera devices that use AC commercial power, the vertical synchronization of the television camera is synchronized with the power frequency using a method called the line lock method, which allows the synchronization of the screens of the television cameras to be at the same timing. (For example, Utility Model Application Publication No. 83-111.755).

This line lock method does not require wiring for reference signals, uses the AC power supply that drives each television camera, detects the phase of the AC power supply, and detects the frequency of the AC power supply.
z, the vertical synchronization signal in the NTSC television camera is synchronized with the power frequency, thereby synchronizing the screens of a plurality of television cameras using the same power source at the same timing.

By using such an external synchronization method or line lock method, if images are captured using multiple TV cameras that are synchronized with each other, each image captured by each TV camera can be transferred to a switcher, etc. Even when viewing images on a single monitor TV via a switcher, when switching images in the same way as switching TV cameras, the synchronization of the monitor TV will not be out of sync with the synchronization of the new TV camera, and the switcher will This has the advantage that noise does not occur on the screen when switching -.

[Problems to be Solved by the Invention] The external synchronization method requires wiring between the reference signal generator and each television camera, so it is difficult to use when increasing the number of television cameras or when the distances between the television cameras are increased. In some cases, there was a drawback that it required a lot of effort to prepare the wiring.

In addition, televisions in Japan are standardized to the NTSC system, which creates a TV screen at 30 frames per second, and each frame consists of 2 fields, so the vertical synchronization signal has a cycle of 60Hz. It is stipulated in

Therefore, in areas where the commercial power supply frequency is BOB Z, it is extremely easy to use the line lock method, which detects the power frequency and compares the phase of the commercial power supply with the phase of the synchronization signal to control the timing of the vertical synchronization signal. Although it could be adopted, in areas where the commercial power supply frequency is 50 Hz (such as the Kanto region), there was an inconvenience that it was not possible to easily synchronize multiple video cameras.

[Means for Solving the Problems] The present invention uses a pulse generator that outputs pulses at a cycle of 60 Hz, and applies the output of the pulse generator to a power line to generate a commercial power supply having a fundamental frequency as an AC power source. By superimposing a pulse voltage of minute width on the power supply with a period of Hz, and on the other hand, incorporating a pulse detector into the television camera and detecting the pulse signal included in the power supply voltage, the above-mentioned 6.
A pulse voltage with a period of 0 Hz is extracted, and this pulse with a period of 60 Hz is used as a reference signal to synchronize a synchronization signal generator in a television camera.

[Function] The present invention applies a pulse signal of ftOHz period generated by a pulse generator to the power supply line and superimposes the pulse voltage on the power supply voltage, so that all television cameras using the same power supply can be connected via the power supply line. The pulse signal can be sent by

Also, in each TV camera, 60H superimposed on the power supply voltage
Since the synchronization signal generator outputs the vertical synchronization signal etc. based on the pulse signal having a period of 1, it is possible to synchronize the screens of each television camera at the same timing.

[Example] An example of the television camera synchronization method according to the present invention is the first example.
As shown in the figure, the reference signal generator! The output terminal 1s of the pulse generator 11 designated as 110 is connected to the lead-in line 51 from the power supply line 50 to the reference signal generator IO, and the pulse generator! The output signal of 1 is superimposed on the power supply voltage so that it can be sent to the power supply line 50 via the lead-in line 51, and the television camera 20 is equipped with a pulse detector 21 for extracting the pulse signal superimposed on the power supply voltage. The output signal of the pulse detector 21 is sent to the phase-locked loop type oscillation circuit 42 in the camera rigidity 11, and the vertical synchronization signal of the television camera synchronized with the pulse signal detected by the pulse detector 21 is sent from the oscillation circuit 42. This is to make it output.

As shown in FIG. A pulse signal having a period of BOB Z is created by dividing the frequency by , and the pulse width of the pulse signal is, for example, about 1/2,000 second. By adding modulation, the frequency range from several tens of KHz to several hundred KHz is
The output signal of the oscillator 12, which is a sine wave of H2, is reduced to 1/60th.
It is configured to generate a pulsed reference signal that is output for, for example, 1/2000 seconds every second.

This pulsed reference signal is input to the primary side of the output transformer 1B via the switching transistor circuit 15, and the pulsed reference signal is outputted from the pulse oscillator 12 via the output transformer 1B and the coupling capacitor 17. This output signal is superimposed on the power supply voltage of the reference signal generator 10 to the lead-in line 51 and, ultimately, to the power supply line 50.
A pulsed reference signal with a period of 0Hz is sent (JI3
1iIJB).

Moreover, the pulse detector 21 incorporated into the television camera 20 is
It is constructed using a low frequency trap circuit 23 using a coil and a capacitor, an amplifier 25 and a waveform shaper 27. In this embodiment, the low frequency trap circuit 23 is constructed by short-circuiting the secondary side of an input capacitor 33 with a diode 35. , power line 50
Connect the low frequency trap circuit 23 from the signal input line 55 to the power supply line 53 leading to the television camera 20,
A coupling capacitor 31 is inserted into the primary side of the input capacitor 33 connected to the signal input line 55 to serve as a bypass filter, so that the low frequency of 50Hz or BOB Z, which is the fundamental frequency of the power supply voltage, is absorbed by the trap circuit 23. cut off,
Only the pulsed reference signal indicated by AK in Fig. 3 is sent to the amplifier 25.
Make it output to .

A coupling capacitor 37 is also inserted on the output terminal side of the low frequency trap circuit 23 to output a pulsed reference signal to the amplifier 25. After the pulsed reference signal is amplified by the amplifier 25, the waveform shaper 27 outputs the pulsed reference signal. The waveform of the eOHZ pulse signal is adjusted, and as shown in C in Figure 3, a specific frequency within tens of KHz to hundreds of KHz is repeated a predetermined number of times, such as several thousand times, as the pulsed reference signal. is handled as one pulse, and the pulse signal from the waveform shaper 27 is outputted as one pulse signal with minute width every 1/60th of a second, and this pulse signal with a period of 60 Hz is sent to the pulse detector 2! output from.

In this way, the pulse detector 21 treats a repetition of a specific frequency many times, such as several thousand times, as one pulse, so it clearly distinguishes the pulsed reference signal from other high-frequency noise contained in the power supply voltage. 60 after removing other high frequency noise etc.
It is possible to easily output only the pulse signal as the 8Z reference signal.

Then, the 60Hz output from this pulse detector 21
Inputting a pulse signal having a period of The oscillation circuit 42 includes a phase detector 43, a loop filter 44, a voltage controlled oscillator 45, and a synchronization signal generator 4e.
The phase detector 43 compares the phases of the reference signal from the pulse detector 21 and the vertical synchronization signal from the synchronization signal generator 4B, outputs a signal based on the phase difference, and sends this signal to a loop that is a low-pass filter. The filter 44 generates a voltage signal, and the voltage control oscillator 45 generates approximately 1
A high frequency signal based on 4.3 MHz is output, and based on the high frequency signal, the synchronization signal of the television camera 20, which is a vertical synchronization signal and a horizontal synchronization signal, is output from the synchronization signal generator 4B to the camera rigidity 11. Returning the synchronization signal to the phase detector 43 is the same as in the conventional case.

In this embodiment, the pulse generator 11 is used as the reference signal generator 10, and the pulse generator 11 outputs 6
A pulse signal having a period of 0H2 is superimposed on the power supply voltage,
In addition, in the television camera 20 that uses the same power supply, the pulse signal is extracted from the power supply voltage and used as a reference signal.
Each television camera 20 uses the same power supply because the vertical synchronization signal etc. are created based on a reference signal having a period of 0Hz.
can perform vertical synchronization of the screen at the same timing.

Note that the voltage of the pulse signal output by the pulse generator 11 is
Keep the pulse signal as small as possible so as not to affect other electronic devices that use the same power supply, and repeat the pulse signal not as a single rectangular wave, but as a sine wave with a specific high frequency several thousand to hundreds of times! If it is made equivalent to a pulse, each television camera 2o can easily extract only the pulse signal, distinguishing it from other noises included in the power supply voltage.

[Effects of the Invention] Since the synchronization method according to the present invention allows the reference signal to flow through the power supply line, no wiring other than the power supply line is required between the TV cameras, and all the cables using the same power supply circuit can The synchronization of TV cameras is controlled by the same reference signal, making it possible to match the synchronization of each TV camera, and easily synchronize between TV cameras.Even in areas where the power frequency is 50Hz, it is extremely easy to synchronize between each TV camera. It is something that can be synchronized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 is a block diagram showing a circuit example of the present invention. FIG. 3 is a diagram showing an example of a reference pulse signal. 10=Reference signal generator, 11=Pulse generator! 20=TV camera, 21 = Pulse detection 41=Power Mela circuit. 48 = synchronous signal generator, 42; Oscillation times 50 = power supply

Claims (2)

[Claims] (1) A pulse generator that outputs a minute width pulse signal with a period of 60 Hz is used, and the output signal of the pulse generator is applied to the power supply line to superimpose the pulse voltage on the power supply voltage, and each television camera Incorporating a pulse detector that detects the pulse superimposed on the power supply voltage, and synchronizing a television camera synchronization signal generator incorporated in the television camera based on the pulse signal detected by the pulse detector. A synchronization method for television cameras featuring: (2) The device described in item 1, characterized in that a high frequency sine wave is generated every 1/60th of a second in a minute time width, so that multiple vibrations are equivalent to one pulse with a minute width. synchronization method for television cameras.