JPS63141487A - Automatic chroma saturation control circuit - Google Patents

Abstract

PURPOSE:To reduce power consumption by activating a peak detection bias voltage circuit only for a burst signal period. CONSTITUTION:A bias circuit driving control circuit 9 is added to a peak detection bias voltage circuit 3. A control pulse is inputted from an input terminal 10 to a bias circuit driving control circuit 9 and only when the control pulse exists in the burst signal period at a high level, the peak detection bias circuit 3 is operated. The peak detection circuit 4 detects only the burst signal component among the inputted chrominance signal component and gives the addition of the peak detection reference bias from the peak detection bias voltage circuit 3 to the peak value holding circuit 6. The output of the peak value holding circuit 6 is given to a hand amplifying circuit 2 via a comparison control circuit 7 to control the amplification gain.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an automatic saturation control circuit used in color demodulation circuits of television equipment and the like.

BACKGROUND OF THE INVENTION In recent years, portable televisions such as liquid crystal televisions have been released, and it is expected that their use will further expand in the future. One of the challenges of portable televisions is to keep power consumption low, and in particular, it is important to reduce the power consumption of various ICs used in television equipment. Among these, the automatic saturation control circuit used in the color demodulation circuit is listed as one of the circuits with the highest power consumption.

The conventional automatic saturation control circuit as described above will be described below with reference to the drawings.

FIG. 3 shows a block diagram of a conventional automatic saturation control circuit. In FIG. 3, 2 is a band amplification circuit that amplifies and outputs the input signal, 3 is a peak detection circuit that outputs a peak detection reference voltage, and IASMI pressure circuit 14 is a peak detection circuit 16 that detects the magnitude of the burst signal amplitude. 7 is a peak value holding circuit that holds the peak-detected output signal, and 7 is a comparison control circuit that controls the amplification gain of the band amplification circuit in accordance with the detected peak voltage value. In the figure, the automatic saturation control circuit includes: peak detection bias voltage circuit 3. peak detection circuit 4. Peak value holding circuit6. It consists of a comparison control circuit 7.

The operation of the automatic saturation control circuit configured as above will be described below.

First, in FIG. 3, a chrominance signal is inputted from an input terminal 1, and the chrominance signal amplified by a band amplification circuit 2 is outputted.

The color 3'-- signal output from the band amplifier circuit 2 is sent to the output terminal 8 and the peak detection circuit 4. In the peak detection circuit 4, among the input color signal components, only the burst signal component is separated from the color signal and extracted by a burst signal extraction control signal input from the one-pulse input terminal 5. The extracted signal component is added to the peak detection reference bias voltage, the peak value is detected, and a detected voltage signal is output. The peak detection reference bias voltage is generated by the peak detection bias voltage circuit 3. The peak detection bias voltage circuit 3 is a circuit that outputs a stable bias voltage against various fluctuations such as power supply voltage fluctuations. The detected voltage signal outputted from the peak detection circuit 4 is held in the peak value holding circuit 6 for 1H period of the video signal, and then sent to the comparison control circuit 7.
The detected voltage signal is transmitted to the The detected voltage signal transmitted to the comparison control circuit 7 is compared with a comparison reference voltage within the comparison control circuit γ, and a control signal according to the comparison result is output. The output control signal controls the amplification gain of the band amplification circuit and always outputs a stable signal to the output terminal 14 regardless of input signal amplitude fluctuations.

Problems to be Solved by the Invention However, the above configuration consumes a large amount of power and is therefore not suitable for a low power consumption video processing IC.

In view of the above problems, the present invention provides an automatic saturation control circuit that can significantly reduce power consumption compared to conventional component circuits.

Means for Solving the Problems In order to achieve the above object, the automatic saturation control circuit of the present invention uses a burst drive control circuit in which a drive control circuit is installed in the peak detection bias voltage circuit that consumes the largest amount of power in the control circuit. The bias voltage circuit is configured to be operated by the drive control circuit only during the signal period.

According to the above-described configuration, the present invention operates the drive control circuit with a pulse signal applied to the input terminal of the drive control circuit, operates the peak detection bias voltage circuit during the burst signal period, and stops the operation outside the burst signal period. By doing so, the time average value of the power consumption of the peak detection bar 5...--Fiasumi pressure circuit is reduced.
This also leads to a reduction in the power consumption of the entire automatic saturation control circuit.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to one drawing. FIG. 1 shows a block diagram of an automatic saturation control circuit in one practical example of the present invention. In FIG. 1, 1 is a video color signal input terminal, 2 is a band amplifier circuit 13 is a peak detection bias voltage circuit, 4 is a peak detection circuit, 5 is a pulse input terminal, 6 is a peak value holding circuit, and 7 is a comparison control circuit. 1 or more are the same as the configuration of the conventional example shown in FIG. Reference numeral 9 denotes a bias circuit drive control circuit, which outputs an operation control signal for the peak detection bias voltage circuit in response to a pulse signal input from the one-pulse input terminal 10. In the figure, the automatic saturation control circuit is composed of blocks excluding the band amplification circuit 2.

There is.

The operation of the automatic saturation control circuit configured as above will be described below. Since the basic operation is the same as that of the conventional configuration shown in FIG. 2, the differences from the conventional configuration will be described in detail below. The difference from the conventional method is 1. A bias circuit drive control circuit 9 is added to the peak detection bias voltage circuit 3. When the control pulse shown in FIG. 2 is inputted to the bias circuit drive control circuit 9 from the pulse input terminal 10, the control pulse stops the peak detection bias circuit 3 at low level, and operates at the control pulse at NO level. This control signal is output. The width T of the control noxle is the second
It is necessary to have a width T2 wider than the width T1 of the burst signal extraction node (pulse input to the node input terminal 6) shown in FIG. The period T2 is the time required to start up the peak detection bias voltage circuit 3 and bring it into a stable state. Therefore, the operating period of the peak detection bias voltage circuit 3 is only T (T, +T2), which leads to a reduction in power consumption.

Effects of the Invention As described above, the present invention makes it possible to reduce power consumption by 7·-7 by setting the operation period of the peak detection bias circuit to the burst signal period, and is extremely useful in practice.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an automatic saturation control circuit according to an embodiment of the present invention. FIG. FIG. 2 is a block diagram showing an automatic saturation control circuit. 1...Video color signal input terminal, 2...Band amplifier circuit, 3...Peak detection bias voltage circuit 14.
... Peak detection circuit 16 ... Pulse input terminal, 6 ... Peak value holding circuit 17 ... Comparison control circuit, 8 ... Image color signal output Terminal, 9.
...Bias circuit drive control circuit, 10...Pulse input terminal. Name of agent: Patent attorney Toshio Nakao and 1 other person
2 Figure

Claims (1)

[Claims] An automatic saturation control circuit comprising a drive control circuit for controlling the drive of a peak detection bias voltage circuit, and operating the peak detection bias voltage circuit only during a burst signal period.