JPH0319578A - Video signal processing unit - Google Patents

Abstract

PURPOSE:To guarantee the missing of a horizontal synchronizing signal and also to reduce noise component caused in a synchronizing separator circuit in a weak electric field by providing a horizontal synchronizing signal guarantee circuit and a noise elimination circuit. CONSTITUTION:The unit consists of a horizontal synchronizing signal guarantee circuit 3, a noise elimination circuit 4, a clock generating circuit 5, a horizontal synchronizing signal separator circuit 1 and a video signal digital processing circuit 2. A leading edge detection circuit 6 in the horizontal synchronizing signal guarantee circuit 3 detects the edge of an inputted horizontal synchronizing signal and resets a horizontal synchronizing signal generating circuit 7 with the pulse to generate a horizontal synchronizing signal for each horizontal scanning period. An AND gate 8 of the noise elimination circuit 4 compares the phase of the horizontal synchronizing signal from the horizontal synchronizing signal separator circuit 1 and the phase of the horizontal synchronizing signal from the horizontal synchronizing signal generating circuit 7 and a edge leading detection circuit 9 detects the leading edges of the following signals with the trailing edge of the horizontal synchronizing signal as the time axis. Thus, a dropout caused at the reproduction of a video tape recorder due to the missing of the horizontal synchronizing signal or the fluctuation of period is eliminated and the horizontal synchronizing signal in compliance with the broadcast standards is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a video signal processing device that guarantees or corrects a horizontal synchronizing signal that is missing or has a variable period, and also corrects skew distortion caused by dropouts using a digital processing circuit. It is something.

2. Description of the Related Art In recent years, digital signal processing circuits have come into widespread use for processing video signals.

A conventional video signal processing device will be described below. Third
The figure is a block diagram of a conventional video signal processing device, in which 1 part is a horizontal synchronizing signal separation circuit and 2 parts is a video signal digital processing circuit.

The operation of the video signal processing device configured as described above will be explained below.

The video signal digital processing circuit 2 is directly inputted from the horizontal synchronization signal separation circuit 1 .

Problems to be Solved by the Invention However, in the above-mentioned conventional structure, since the horizontal synchronizing signal separation circuit 1 directly inputs the video signal to the digital processing circuit 2, the horizontal synchronizing signal may be lost due to weak electric fields, etc., or noise may occur. There is a problem in that the video signal digital processing circuit 2 malfunctions when the horizontal synchronizing signal is applied to the horizontal synchronizing signal.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and aims to provide a video signal processing device that can guarantee the absence of a horizontal synchronizing signal and remove noise components.

Means for Solving the Problems To achieve this object, the video signal processing device of the present invention includes a horizontal synchronization signal guarantee circuit that counts one horizontal scanning period and generates a horizontal synchronization signal, and a trailing edge of the horizontal synchronization signal. It consists of a circuit that blocks input signals for a certain period of time.

Effect: With this configuration, it is possible to guarantee the omission of the horizontal synchronizing signal and to remove noise components occurring at the trailing edge of the horizontal synchronizing signal.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of a video signal processing device according to an embodiment of the present invention. Also shown in Fig. 1, 3 is a horizontal synchronization signal guarantee circuit, 4 is a noise removal circuit, 6 is a chronograph generation circuit, 1 is a horizontal synchronization signal separation circuit, and 2 is a video signal digital processing circuit. This is the same configuration as the example.

The operation of the video signal processing apparatus of this embodiment configured as described above will be described below.

First, the horizontal synchronization signal input to the horizontal synchronization signal separation circuit 1 is input to the horizontal synchronization signal guarantee circuit 3 and the noise removal circuit 4. In the horizontal synchronization signal guarantee circuit 3, the edge of the input horizontal synchronization signal is detected by the rising edge detection circuit 6, and the horizontal synchronization signal generation circuit 7 is reset with this pulse to generate a horizontal synchronization signal every horizontal scanning period.

Furthermore, the horizontal synchronization signal output from the horizontal synchronization signal guarantee circuit 3 is input to the noise removal circuit 4.

In the noise removal circuit 4, the phase of the horizontal synchronization signal from the horizontal synchronization signal separation circuit 1 and the horizontal synchronization signal from the horizontal synchronization signal generation circuit 7 is compared by an AND gate 8, so that the trailing edge of the horizontal synchronization signal is located later on the time axis. The rising edge of the coming signal is detected by the rising edge detection circuit 9. Based on this bus μ as a reference, the horizontal synchronizing signal is set to Hi (h
and the AND gate 8 and the noise removal pulse generator 1
0 is input to the video signal digital processing circuit 2 through the OR gate 11. In the noise removal circuit 4,
If the cycle of the input horizontal synchronization signal is longer or shorter than the broadcast standard value, the horizontal synchronization signal from the horizontal synchronization signal guarantee circuit 3 is used, and if the cycle is input at the broadcast standard value, , a method using an input horizontal synchronization signal is adopted. First, countermeasures are taken against skew distortion caused by dropouts that occur during playback of a video table recorder (hereinafter referred to as VTR). Figure 2 shows a horizontal synchronization signal that is input to the video digital processing circuit 2 when the horizontal synchronization signal is missing (2) or when a dropout occurs (referred to as the output horizontal synchronization signal in Figure 2). The state is illustrated. Figure 2 (a) shows when the horizontal synchronizing signal is input normally, and Figure 2 (b) shows when the horizontal synchronizing signal is missing.
Figure (0) illustrates a case where a dropout occurs in the horizontal synchronization signal, and each corrected signal is the output horizontal synchronization signal.

As described above, according to this embodiment, by providing the horizontal synchronization signal guarantee circuit and the noise removal circuit, it is possible to eliminate the loss of the horizontal synchronization signal and the periodic fluctuation history of the video table recorder (VTR).
), it is possible to eliminate dropouts that occur during playback and generate a horizontal synchronization signal that complies with broadcasting standards.

Effects of the Invention By providing a horizontal synchronization signal guarantee circuit and a noise removal circuit, the present invention can guarantee horizontal synchronization signal loss and reduce noise that occurs in the synchronization separation circuit during a weak electric field. It is possible to realize an excellent video signal processing device that can obtain the effect of eliminating skew that appears on a television screen due to dropouts that occur during playback.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a block diagram of a video signal processing device in an embodiment of the invention, Fig. 2 is a timing diagram showing the state when correcting a horizontal synchronization signal, and Fig. 3 is a conventional 1 is a block diagram of a video signal processing device of FIG. 1...Horizontal synchronization signal a circuit, 2...
Video signal digital processing circuit, 3...Horizontal synchronization signal guarantee circuit, 4...Noise removal circuit, 5...
... Clock generation circuit, 6 ... Rising edge detection circuit, 7 ... Horizontal synchronization signal generation circuit, 8
...AND gate, 9 ...rising edge detection circuit, 10 ...noise removal pulse generation circuit, 11 ...OR gate.

Claims (1)

[Claims] A video signal processing device that includes a circuit that counts one horizontal scanning period and generates a horizontal synchronizing signal, and a circuit that removes noise components that occur during a certain period from the leading edge or trailing edge of the horizontal synchronizing signal.