JPH0413396A - Burst gate pulse changeover device - Google Patents

Abstract

PURPOSE:To make the timing of a burst signal in matching with that of a BGP burst gate pulse and to make recording and reproducing picture quality stable by connecting each output of generated plural BGPs to each of plural input terminals of a changeover circuit comprising analog components directly so as to switch the plural BGPs. CONSTITUTION:Plural generated BGPs 1, 2 are connected directly to each of plural input terminals of a changeover circuit 7 comprising analog components and also connected to each of plural input terminals of a selector 4 in a digital circuit 8 directly, a control signal being an output of the selector 4 selects the changeover circuit 7 thereby connecting either of the plural generated BGPs 1, 2 to a BGP control circuit 6 and switching the BGPs 1, 2. Thus, only the switching control signal from the selector is connected to the BGP changeover circuit via the digital circuit whose delay is caused only by the time delay of the switching control signal from the selector and it is possible to almost make the timing of a burst signal in matching with that of the BGP (in several ns or below).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a system for switching a plurality of burst gate pulses (hereinafter referred to as BGP) created according to a purpose in color signal processing in a VTR.

2. Description of the Related Art Currently, in the color signal processing of a VTR, a method is implemented in which a plurality of BGPs are created depending on the purpose for use in a phase comparator circuit, a color killer circuit, etc., and the BGPs are switched in a timely manner.

FIG. 2 is a circuit diagram of a conventional burst gate pulse switching circuit. Its configuration consists of multiple BGP
I, 2 are once input to the digital circuit section 3, and a selector (hereinafter referred to as selector) 4 consisting of a digital circuit is input.
After being input to the switching circuit 5 which is also made up of a digital circuit, the GP required by the control signal which is the output of the selector 4 is outputted from the switching circuit 5 which is made up of a digital circuit, and is then input to the switching circuit 5 which is also made up of a digital circuit. and a BGP control circuit 6 such as a color killer circuit.

In VTR color signal processing, A is used as a circuit under BGP control.
There are CC (automatic chroma level control) circuits, burst emphasis circuits, burst de-emphasis circuits, phase comparison circuits, color killer circuits, etc., but numerically digital circuits are used as a method for creating burst gates.

Problems to be Solved by the Invention The problem with this method is that the BGP control circuit 6
Examples of such problems include pulse width fluctuations in BGP due to timing differences between GP and burst signals and clock jitter.

To solve this problem, recently burst signals have been used to
By creating P, a gate that is completely synchronized with the burst signal is realized and the above problem is solved, but the problem with this method is that BGP that is created from the burst signal generally uses an amplitude detection method. Therefore, there is a drawback that BGP cannot be created when the amplitude of the burst signal becomes small.

Therefore, when the amplitude of the burst signal is large, the BGP created by the burst signal is used, and the amplitude becomes small and the BG
When P creation becomes impossible, a method is used in which this state is digitally detected (selected) and switched to BGP created by the previous digital circuit. This series of operations involves selecting multiple BGPs in a digital circuit, switching the multiple BGPs within the digital circuit using the selected control signal, and then connecting to each of the aforementioned circuits. When timing passes through a digital circuit (especially when using an IIL circuit), the number of gates (I
There is a problem in that the transit time is added in proportion to IL) and there is a delay with respect to the burst signal.

Means for Solving the Problems The present invention connects the respective BGP outputs of a plurality of created BGPs to a plurality of input terminals of a selector having a digital circuit configuration, and further provides a switching system in which each of the BGP outputs is configured with an analog element. Connect directly to multiple input terminals of the circuit,
The present invention is characterized in that the plurality of BGPs, which are the outputs of the switching circuit, are switched by a control signal obtained by the selector.

Therefore, only the switching control signal from the selector (hereinafter referred to as selector) is connected to the BGP switching circuit via a digital circuit that causes a time delay.

Embodiment FIG. 1 is a circuit diagram showing the burst gate pulse switching method of the present invention. In Figure 1, the created multiple B
The GPI, 2 is directly connected to a plurality of input terminals of a switching circuit 7 made up of analog elements, and also connected to a plurality of input terminals of a selector 4, which is a digital circuit 8. The configuration is such that the switching circuit 7 is operated to switch and one of the plurality of BGPIs 2 is connected to the BGP control circuit 6, and the BGPIs 2 are switched.

Generally, in the case of a digital circuit composed of IIL, the time taken to pass through the circuit is proportional to the number of IIL gates used, and ranges from several tens of nanoseconds to several hundred nanoseconds per gate.

In VTR color signal processing, if the timing of the burst signal of the burst control circuit and the BGP differ by several hundred nanoseconds, this is one of the causes of image quality deterioration, so it is important that the timings match exactly. As in the present invention, a plurality of BGPs are directly connected to a BGP switching circuit, and the output is connected to a BG switching circuit.
By connecting it immediately before the P control circuit or by switching BGP within the BGP control circuit, it is possible to make the timings of the burst signal and BGP almost coincide (within several nanoseconds).

Effects of the Invention The present invention has the advantage that the timing of the burst signal in the BGP control circuit (phase comparator circuit, color killer circuit, etc.) in the VTR color signal processing can almost match the BGP timing, thereby stabilizing recording and playback image quality. It becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a burst gate pulse switching method according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing a conventional burst gate pulse switching method. 1.2...BGP, 3,8...Digital circuit section, 4...Selector, 5,7...
...Switching circuit, 6...BGP control circuit.

Claims (1)

[Claims] inputting each of the plurality of burst gate pulse signals to a plurality of input terminals of a selector having a digital circuit configuration; further inputting each of the burst gate pulses directly to a plurality of input terminals of a switching circuit constituted by analog elements; A burst gate pulse switching device characterized in that the plurality of burst gate pulses, which are outputs of the switching circuit, are switched by a control signal obtained from a selector.