JPS58157261A - External synchronizing system - Google Patents

Abstract

PURPOSE:To eliminate the generation of missing of a picture and asynchronism completely, by putting an external driving pulse signal into a video blanking period. CONSTITUTION:A horizontal oscillation circuit 11 of a video section 8 starts the oscillation at the tail ridge of a horizontal driving pulse separated at a frequency separating circuit 10, keeps the oscillation for the horizontal scanning period and the oscillation stop period is the blanking period of an output video signal. In an input waveform of an oscillation section 1, the driving pulse signal is provided in the blanking period, and this is applied to a positive amplitude separation circuit 3 for the elimination of the driving pulse signal, allowing to obtain the video signal without the effect of the driving pulse. When a delay time by a cable 7 is longer, the driving pulse appears prior to the blanking period, but the driving pulse stays within the blanking period, even if the round delay time is within a difference between the blanking period and the width of driving pulse. thus, the missing of picture and the asynchronism are eliminated and the trace of pulse is eliminated completely.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an external synchronization method in which a television camera or the like oscillates its synchronization signal in synchronization with an external drive signal.

Figure 1 is an example of a block diagram of an external synchronization method, and Figure 2 is an example of a block diagram of an external synchronization method.
FIG. 2 shows waveforms and timing charts for the conventional external synchronization method in the block diagram shown in FIG.

In FIG. 1, (1) is an oscillation part of an external drive signal, (2
) is a drive signal generator with mixed horizontal and vertical signals, (3
) is a positive amplitude separation circuit that extracts a signal with a positive polarity above a certain level. (4) is a sync signal generator that generates a sync signal from the input blanking signal. (5) is a video amplifier that amplifies the video signal. (6) is a video amplifier. Signal output terminal, (7) is a coaxial cable where the external synchronization drive signal and video signal are multiplexed and transmitted, (8) is the imaging unit of the television camera, and (9) is for extracting signals of negative polarity from a certain level. Negative amplitude separation circuit, (2
) is a frequency separation circuit that separates the external synchronization drive signal obtained by the negative amplitude separation circuit (9) into horizontal and vertical drive signals;
(b) is a horizontal oscillation circuit that is externally synchronized with the horizontal drive signal from the frequency separation circuit QO; (2) is a vertical oscillation circuit that is externally synchronized with the vertical drive signal from the frequency separation circuit 01;
) is an input terminal for a video signal from an image pickup tube, etc., and α◆ is a video amplifier that amplifies the video signal from the input terminal.

2 to O in FIG. 2 show waveforms and timing charts of the horizontal oscillation period of parts 0 to 0 in FIG.

Next, the operation will be explained. The drive signal generator (2) of the oscillator (1) generates the horizontal drive signal C necessary for television scanning.
In the NTSC system, it is 15.78k) h) e vertical drive signal (
This horizontal and vertical mixed negative polarity driving pulse signal is sent to the imaging section (8) through the coaxial cable (7). The waveform is shown in Figure 2 (■). This negative polarity drive signal is limited in the positive polarity separation circuit (3) of the oscillation section (1) and is not output.

The negative polarity drive pulse signal phase sent to the imaging unit (8) via the coaxial cable (7) is detected by the negative amplitude separation circuit (9),
The frequency separation circuit αq separates the signal into a horizontal drive signal and a vertical drive signal, and the front pulse of each pulse generates a horizontal oscillation circuit Oυ,
Apply external synchronization to the vertical oscillation circuit @ to oscillate. The outputs from the horizontal oscillation circuit α and the vertical oscillation circuit (6) function as scanning, blanking signals, etc., and the imaging section (8) operates. In addition, the video signal of the imaging unit (8) is amplified by the video amplifier α4, sent to the oscillation unit (1) through the coaxial cable (7), detected by the positive amplitude separation circuit (3), and then sent to the video amplifier (
5), and a synchronizing signal from a synchronizing signal generator (4) is added thereto and output. The negative amplitude separation circuit (9) of the imaging section (8) limits the video and signal and does not output it.

Next, FIG. 112 will be explained. First of all, it is well known that a delay time occurs when transmitting a signal using a cable, etc., and in the case of a coaxial cable, the delay time is 1007i.
FJ is approximately 0.5 μs. In Fig. 1, if the coaxial cable (7) is 600 m long, the driving pulse signal of the oscillator (1) is approximately 2.5 μs (Fig. 2 tdl
) be late. The video signal generated by the drive pulse is also delayed by about 2.5 μs (td2 in FIG. 2) at the input to the oscillation unit (1), resulting in a round trip delay time of about 5 μs. Although this delay time does not affect the overlapping period with a long period, it has an adverse effect on the horizontal period with a short period as described below.

In Fig. 2 ■ is the horizontal single-motion pulse signal waveform of the oscillation unit (1), which is negative, and @ is the output end waveform of the imaging unit (8), which is the positive polarity including the negative horizontal drive pulse that caused the delay tdl and the blanking signal. It is a mixture of sexual video signals. ■ is a drive pulse signal separated from waveform O by the negative amplitude separation circuit (9), (p is a horizontal oscillation circuit that oscillates synchronously with the leading edge of the horizontal one-motion pulse separated by the frequency separation circuit Q4) (
The output of (b) serves as a blanking signal for the output video signal 0. O is the input end waveform of the oscillator (1), which is a mixture of the output drive pulse and the input video signal frs.The blanking signal causes a delay td2, and from the leading edge of the drive pulse signal = 2td
l) is occurring.

Since the conventional system is configured as described above, the drive pulse 7 signal always appears within the video signal period due to the delay time caused by the cable, resulting in image dropout, and the pulse also causes synchronization failure. However, it was difficult to put it into practical use.

This invention was made in order to eliminate the drawbacks of the conventional system as described above.
) rises at the trailing edge or leading edge of the external drive pulse, oscillates with a long pulse width, and operates so that the oscillation stop period becomes the blanking period, so that the external drive pulse signal is within the blanking period. It is an object of the present invention to provide a device that eliminates the influence of external drive pulses by eliminating them from the output video signal through positive polarity separation.

Embodiments of the present invention will be described below with reference to the drawings.

The block diagram is as shown in FIG. 1 as in the conventional method, but FIG. 8 shows waveforms and timing charts according to the method of the present invention.

e is the output end waveform of the imaging unit (8) according to the method of the present invention;
e is the output waveform of the horizontal oscillation circuit (b) that oscillates synchronously with the trailing edge of the horizontal drive pulse separated by the frequency separation circuit (L), which serves as a blanking signal for the output video signal; O is the oscillation unit (1) The input end waveform is a mixture of the output drive pulse signal and the input video signal, and the drive pulse is removed from the waveform O by the positive amplitude separation circuit (3), and the synchronization signal is generated after amplification by the video amplifier (5). The video output from the device (4) with the synchronization signal added is in the form of a signal waveform.

The timing is shown in conjunction with Figure 2 ■■.

Horizontal drive pulse signal waveform ■ of the oscillating unit (1) and the imaging unit (
The drive pulse signal waveform (■) separated by the negative amplitude separation circuit (9) in 8) is the same as the conventional method, but the horizontal oscillation operation according to the present invention is performed at the trailing edge of the drive pulse, as shown in Figure 8e. An oscillation waveform is obtained in which the oscillation starts, the horizontal scanning period oscillates, and the oscillation stop period becomes the blanking period.As a result, the input waveform of the oscillator (1) becomes the drive pulse signal as shown in Figure 8e. When the blanking period begins, the positive amplitude separation circuit (3) removes the drive pulse signal, thereby obtaining a video signal that is completely free from the influence of the drive pulse.

As the delay time due to the cable increases, the drive pulse appears before the blanking period, but as can be seen in the figure, the round trip delay time is the same as one blanking period and the drive pulse width (T
), it will not deviate from the blanking period. If the blanking period is 10.5 μs and the drive pulse width (I) is 2 μs, a round trip delay time of 8.5 μs is allowed, and in the case of a coaxial cable. It can be extended up to about 860m, and there is no problem in practical use.

Incidentally, in the example of the above method, the case where the drive pulse rises at the trailing edge has been explained, but when the same operation occurs when the drive pulse rises at the leading edge, the delay time depending on the cable number ζ is the drive pulse Ill! (1
), it can be easily inferred that the drive pulse signal will fit within the blanking period and the same effect will be obtained.

In addition, in the example of the above method, the case where the video signal and the drive pulse signal are multiplexed using a coaxial cable was explained, but even when the drive pulse signal is sent using a separate cable, there is a risk that traces of the drive pulse may be mixed in the oscillator. The external synchronization method of the present invention is effective as a countermeasure against this problem.As described above, according to the present invention, since the external drive pulse is contained within the video blanking period, there is no possibility of missing images or synchronization failures. It is possible to use an external synchronization method that eliminates all traces of the pulse plate and completely eliminates the traces of the pulse plate, thereby causing no deterioration in image quality.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an example of an external synchronization method that multiplexes and transmits a video signal and a drive pulse signal for external synchronization, FIG. 182 is a diagram showing waveforms and timing charts of the conventional external synchronization method, and FIG. It is a figure which shows the waveform of an external synchronization method, and a timing chart. (1)......Oscillation section, (2)......
・：Normal signal generator, (3)・・・・・・Positive amplitude separation circuit, (4)・・・・・・Synchronization (Wi signal generator, (5)・・・...Video amplifier, (6)...
......Video output terminal, (7)...
・Coaxial cable, (8)... Imaging section, (
9)・・・・・・Negative amplitude separation circuit, aq・・・・
・Four frequency separation circuit, 0M...Horizontal oscillation circuit, (2)...Song vertical oscillation circuit, 0...Song video input terminal, 04... ...Video amplifier. In addition, (i!ri・j ai>#*V@
* 'jJI, shows the waveform and timing of part (ω(4)■(1)) in Figure 1. Agent Makoto Kuzuno - Figure 2 Procedural Amendment (request) Mr. Commissioner of the Japan Patent Office 1, Indication of the case Request paste No. 57-48585 2
, Title of the invention External synchronization method 3, Relationship with the case of the person making the amendment Patent applicant address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Corporation representative piece + I
+Jinhachibe 4, Agent address: 2-2-3-6 Marunouchi, Chiyoda-ku, Tokyo, Subject of amendment (1) Brief description of drawings in the specification (2) Drawing 7, Contents of amendment (1) ) of the specification, page 8, digit 1 to page 16, “2nd digit”
The figure is a conventional... figure. " is corrected to "FIG. 2 is a diagram showing waveforms and timing charts of the conventional external synchronization method and the present invention." (2) Figures 2 and 8 of the drawings shall be referred to as Figure 2 as shown in Attachment G-. 8. List of attached documents (1) Revised drawings (Figure 2) 1 or more copies of Figure 2

Claims (1)

[Claims] In a device that transmits a video signal and an external synchronizing drive pulse signal, a circuit that synchronizes oscillation with an external drive pulse, and starts oscillating at the trailing edge or leading edge of an external single-motion pulse, and the oscillation stop period becomes a blanking period. An external synchronization method characterized in that oscillation is performed so that an external synchronization drive pulse signal falls within the blanking period.