JPS63126387A - Color signal processing circuit - Google Patents

Abstract

PURPOSE:To maintain a normal frequency control operation and a phase control operation by switching the output of a color signal circuit and supplying a selected burst gate pulse to a frequency and phase control circuit. CONSTITUTION:When the burst gate pulse 2a outputted from a burst gate pulse output circuit 2 is inputted to a color signal discriminating circuit 4 to discriminate a specified color signal, the movable contact 3a of a switching circuit 3 is charged to a fixed contact A side by the discriminating output of the color signal discrminating circuit 4. Therefore, the pulse is inputted to the frequency and phase control circuit 5 from the burst gate pulse output circuit 2 to maintain a noise resistance. According to the deviation of a timing between a luminance signal and a color signal, when the color signal discriminating circuit 4 discrminates it to be not the specified color signal, the movable contact 3a is charged to a fixed contact B side, a pulse from a burst gate pulse output circuit of wide pulse duration is supplied to the circuit 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color signal processing device for a video recording and reproducing device. The present invention relates to a color signal processing device that operates a control circuit and a phase control circuit.

[Conventional technology]

Conventional color signal processing devices of this type narrow the pulse width of the burst gate pulse for extracting burst signals in order to ensure noise resistance. However, there was a high possibility that the burst signal and the burst gate pulse position did not match. Therefore, for example, as shown in Japanese Utility Model Publication No. 59-7819, a pulse counter is used to count a fixed number of burst pulses. Furthermore, a burst signal processing circuit has been proposed which extracts only an intermediate portion of a burst signal having accurate phase information.

[Problem that the invention seeks to solve]

However, in the past, no consideration was given to the extraction process of the burst signal itself.As a result, due to mismatch between the burst signal and the burst gate pulse, normal frequency control operation and phase control operation are not performed. The present invention was made to eliminate the above-mentioned problems, and its purpose is to provide normal frequency control operation even if the timings of the luminance signal and color signal are misaligned.

An object of the present invention is to provide a color signal processing device that can maintain phase control operation.

[Means for solving problems]

In order to achieve the above object, the present invention extracts a burst signal included in a color signal in a video signal using burst gate pulses from a plurality of burst gate pulse output circuits, and determines whether the color signal is a specified color signal. a color signal discrimination circuit that discriminates whether or not the color signal is present; and one of the plurality of burst gate pulse output circuits is selected based on the discrimination output of the color signal discrimination circuit, and the burst gate pulse outputted from the circuit is controlled in both frequency and phase. It is characterized in that it is equipped with a switching circuit that supplies power to the circuit.

[Effect]

The color signal processing device of the present invention switches the switching circuit using the output of the color signal discrimination circuit, and supplies the burst gate pulse from the burst gate pulse output circuit selected by the switching circuit to the frequency 9 phase dual control circuit. Thus, normal frequency control operation and phase control operation are maintained even if the timings of the luminance signal and color signal are shifted.

〔Example〕

The present invention will be described in detail below with reference to the drawings. ・Figure 1 shows that a burst gate pulse with a narrow pulse width is normally used, and a burst gate pulse with a wide pulse width is used only when the burst signal position is shifted. FIG. 2 is a block diagram showing a first embodiment of the present invention in which switching to gate pulses is performed.

In FIG. 1, the output side of the first burst gate pulse output circuit 10 is connected to a fixed contact B of the switching circuit 3. The output side of the second burst gate pulse output circuit 2 is connected to the fixed contact A of the switching circuit 3 and the color signal discrimination circuit 4.
connected to the input side of the

A color signal input terminal 6 and a reference signal input terminal 7 serving as a reference for the frequency, phase, and dual control circuit 2 discrimination circuit are connected to the other input side of the color signal discrimination circuit 4. The output side of the switching circuit 3 is connected to the switching circuit 3. The output side of the switching circuit 3 is connected to the input side of the frequency 1 phase dual control circuit 50, and the other input side of the frequency 9 phase dual control circuit is connected to the above input terminal. 6.7 is connected.

FIG. 2 is a signal waveform diagram illustrating the operation of the above embodiment.

The first burst gate pulse output circuit 1 is shown in FIG.
The second burst gate pulse output circuit 2 outputs a burst gate pulse having a pulse width W1 shown in FIG.
) outputs a burst gate pulse with a pulse width W2 shown in FIG. Here, wl>w2.

Now, the burst gate pulse 2a outputted from the second burst gate pulse output circuit 2 is input to the color signal discrimination circuit 4, which performs a color signal discrimination operation, and discriminates it as the prescribed color signal 8 shown in FIG. 2 (&). When this occurs, the movable contact 3a of the switching circuit 3 is closed to the fixed contact A side by the discrimination output of the color signal discrimination circuit 40, and at other times, the movable contact 6a is closed to the fixed contact B side.

For this reason, the frequency 9 phase dual control circuit 5 has a
The burst gate pulse 2a from the second burst gate pulse output circuit 2 having a narrow pulse width shown in ) is inputted, and unnecessary parts before and after the burst signal are not extracted, so that the noise resistance of the frequency 9 phase control operation is ensured.

On the other hand, if the position of the burst signal and the burst gate pulse 2a output from the second burst gate pulse output circuit 2 do not match due to the timing difference K between the luminance signal and the color signal, the color signal discrimination circuit 4 The movable contact 5a of the switching circuit 3 determines whether the signal is a specified color signal 8 or a color signal 9 shown in FIG. 2(b).
into the fixed contact B side.

For this reason, the frequency 1 phase dual control circuit 5 has
A burst gate pulse 1a from the first burst gate pulse output circuit 1 having a wide pulse width shown in ) is inputted to prevent misgate of the burst signal 10 and maintain normal control operation.

In this embodiment, the switching circuit 6 is preferably connected to the fixed contact A under normal conditions.

FIG. 5 is a block diagram showing a second embodiment of the present invention, in which a burst gate pulse is selected by the output of a color signal discrimination circuit that operates based on a burst signal extracted from burst gate pulses having different pulse generation times. ◇ In FIG. 5, the output sides of the plurality of burst gate pulse output circuits 11 to 15 having different pulse generation times are fixed contacts A to C of the switching circuit 14 and the color signal discrimination circuit 1.
5 to 170 input side, and to the other input side of this color signal discrimination circuit, an input terminal 6 for a color signal and an input terminal 7 for a reference signal that serves as a reference for the frequency 1 phase dual control circuit 1 discrimination circuit are connected. has been done.

Each output side of the color signal discrimination circuits 15 to 17 is connected to a comparator circuit 18, and the output of the comparator circuit 18 switches the switching circuit 14. The output side of this switching circuit 14 is connected to the input side of the frequency 9 phase dual control circuit 5, and the input terminal 6.7 is connected to the other input side of the frequency 1 phase dual control circuit 5.

FIG. 4 is a signal waveform diagram explaining the operation of the second J embodiment.@The burst gate pulses 11a to +3a output from each of the burst gate pulse output circuits 11 to 15 have pulse widths as shown in FIG. is a signal whose phase is constant and whose phase differs by a certain amount.

In the normal state, the color signal discrimination circuit 15 discriminates the color signal as the specified color signal 19 shown in FIG. The burst gate pulse 12a output from the burst gate pulse output circuit 12 is supplied to the two-phase dual control circuit 4, and the normal frequency 1
A phase control operation is performed.

On the other hand, if the position of the burst signal and the burst gate pulse 12a7jX of the burst gate pulse output circuit l 2 do not match due to timing deviation of the luminance signal, the other fixed contacts of the switching circuit 14 are switched by the output of the comparison circuit 18. selected.

That is, when the burst signal 22 is shifted forward from its normal position as shown in FIG. 4(1), the movable contact 14& of the switching circuit 14 is connected to the fixed contact A. As a result, the color signal 2 shown in Fig. 4 (1))
0, the burst gate pulse lta output from the burst gate pulse output circuit 11 is supplied to the frequency 1 phase dual control circuit 4.

On the other hand, when the burst signal 22 is shifted backward from the normal position as shown in FIG. 5(c), the movable contact 14a of the switching circuit 14 is connected to the fixed contact C.

Therefore, for the color signal 21 shown in FIG. 4(C), the burst gate pulse 13a output from the burst gate pulse output circuit 13 is supplied to the frequency 1 phase dual control circuit 4.

As described above, according to the present embodiment, it is possible to prevent misgate of the burst signal 22 and maintain normal control operation. [Effects of the Invention] As is clear from the above description, according to the present invention, color signal discrimination is possible. The output of the circuit switches the switching circuit, selects a plurality of burst gate pulse output circuits, and changes the frequency of the burst gate pulse output from the selected burst gate pulse output circuit.

Since the signal is supplied to both phase control circuits, it is possible to maintain a normal frequency control operation and one-phase control operation even if the timings of the luminance signal and the color signal are shifted.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a color signal processing device according to a first embodiment of the present invention, FIG. 2 is a signal waveform diagram explaining the operation of the first embodiment, and FIG. 3 is a color signal processing device according to a second embodiment of the present invention. FIG. 4, a block diagram of the signal processing device, is a signal waveform diagram illustrating the operation of the second embodiment. 1.2.11-13... Burst gate pulse, 4°15-17... Color signal discrimination circuit, 5.14...
Switching circuit, 5... Frequency 9 phase dual control circuit, 8, 9
゜19-21...Color signal, 10.22...Burst signal, la, 2a, lla~+3a...Burst gate pulse.

Claims (1)

[Scope of Claims] 1. A plurality of burst gate pulse output circuits; a burst signal included in a color signal in a video signal is extracted by the burst gate pulse output from the burst gate pulse output circuit, and the color signal is defined; a color signal discrimination circuit that discriminates whether or not the color signal is a color signal; a switching circuit that selects the plurality of burst gate pulse output circuits based on the discrimination output of the color signal discrimination circuit; A color signal processing device comprising a frequency and phase control circuit that inputs a burst gate pulse from a gate pulse output circuit. 2. The color signal processing device according to claim 1, which uses a plurality of burst gate pulse output circuits that output burst gate pulses having different pulse widths. 3. The color signal processing device according to claim 1, which uses a plurality of burst gate pulse output circuits that output burst gate pulses having different phases.