JPS63139492A - Acc circuit - Google Patents

Abstract

PURPOSE:To stabilize an operation with simple circuit constitution by adding the amplitude value of a burst signal for one horizontal period, dividing a prescribed reference value by this added value, calculating the average value of the quotient for every one vertical period to have a multiplexer in a multiplication circuit. CONSTITUTION:A burst amplitude value calculating circuit 2 calculates the amplitude value of the burst signal and this calculated value is applied to one input terminal of an addition circuit 9 and a value outputted from this addition circuit 9 is applied to the other input terminal of the circuit 9. A value outputted from an addition circuit 12 is applied to a shifter 13, shifted by one bit and outputted. This operation is repeated for every one vertical period, thereby, the average value for every one vertical period of a quotient is calculated. The average value outputted from the shifter 13 is applied to the multiplication circuit 7, the multiplication circuit 7 multiplies this average value by a chrome signal from an input terminal 1 as themultiplier, an output signal of a prescribed level is taken out to an output terminal 8 and in such a way, an ACC operation is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ACC circuit for digitizing and processing a video signal and used in a color preview receiver.

[Conventional technology] FIG. 2 is a block diagram showing a conventional ACC circuit.

First, the configuration of this ACC circuit will be explained.

In the figure, an input terminal 1 is connected to one input terminal of a multiplication circuit 7, and a burst amplitude value calculation circuit 2. f
fi width maximum value acquisition circuit 3. Error signal generation circuit 4. It is connected to the other input terminal of the multiplication circuit 7 via the accumulator 6 . 5 is an input terminal to which a predetermined reference value is input.

Multiplier circuit 7 is connected to output terminal 8 .

Next, the operation of this ACC circuit will be explained.

A chroma signal including a burst signal digitized with 8 pits is input to an input terminal 1, and this chroma signal is applied to one input terminal of a multiplier circuit 7 and a burst amplitude value calculation circuit 2. The burst amplitude value calculation circuit 2 calculates the amplitude value of the burst signal, and this total W value is given to the maximum amplitude value acquisition circuit 3.

The maximum amplitude value acquisition circuit 3 acquires the maximum amplitude value of the burst signal for each horizontal opening, and this acquired value is given to the error signal generation circuit 4. The error signal generation circuit 4 calculates the difference between the reference value inputted from the input terminal 5 and the above-mentioned input value, and outputs an error signal. This error signal is given to the accumulator 6, and the accumulator 6 accumulates this error signal. The multiplier circuit 7 logically determines its multiplier based on the error signal from the accumulator 6, and multiplies this multiplier by the chroma signal from the input terminal 1, thereby making the level of the output signal equal to the reference value.

[Problems to be solved by the invention] Since the conventional ACC circuit is configured as described above,
What is the circuit configuration? ! ! Furthermore, since the maximum value of the amplitude of the burst signal is captured, the image is often disturbed when the level of the burst signal changes significantly due to pulse noise, etc. This was made to solve the above-mentioned problems, and the purpose is to obtain an ACC circuit with a simple circuit configuration and stable operation.

[Means for Solving the Problems] The ACC circuit according to the present invention inputs a chroma signal including a fully digitized burst signal to an input terminal, and calculates a burst signal of an O chroma signal from the input terminal using an amplitude value calculation means. , the adding means adds the output of the amplitude value calculating means for each horizontal period, the dividing means divides the predetermined reference value by the adding means output for each horizontal period, and the average value calculating means divides the predetermined reference value by the output of the adding means for each horizontal period. The average value of the output for each vertical period is calculated, and the output of the average value calculation means is multiplied by the chroma signal from the input terminal by the multiplication means.

[Operation] In the present invention, the amplitude values of the burst signals are added for each horizontal period, a predetermined reference value is divided by this added value, and the average value of this quotient for each vertical period is calculated. Since the multiplier is set as a multiplier of The operation of the ACC circuit is more stable than the conventional case where the multiplier of the multiplier circuit is determined based on the maximum amplitude value of the burst signal.

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

In the description of this embodiment, the description of parts that overlap with the description of the conventional technology will be omitted as appropriate.

FIG. 1 is a block diagram of an ACC circuit according to an embodiment of the present invention.

The configuration of this embodiment differs from the configuration of the ACC circuit shown in FIG. 2 in the following points. That is, the burst amplitude value calculation circuit 2 is connected to one input terminal of the adder circuit 9, and the output terminal of 9 is connected to the other input terminal. Addition circuit 9
The output terminal of is connected to one input terminal of an adder circuit 12 via a divider circuit 10, and the adder circuit 12 is connected to the other input terminal of a multiplier circuit 7 via a shifter 13. Further, the output terminal of the shifter 13 is connected to the other input terminal of the adder circuit 12. 11 is an input terminal to which a predetermined reference value is input.

Next, the operation of this ACC circuit will be explained.

A chroma signal containing an 8-bit digitized burst signal is input to an input terminal 1, and this chroma signal is applied to one input terminal of a multiplier circuit 7 and also to a burst amplitude value calculation circuit 2. The burst amplitude value calculation circuit 2 calculates the amplitude value of the burst signal, and this calculated value is given to one input terminal of the adder circuit 9, and the value output from the adder circuit 9 is given to the other input terminal of the adder circuit 9. Given.

As a result, the adder circuit 9 increases the amplitude value of the burst signal by 1.
It is added for each horizontal period, and this added value is sent to divider circuit 1.
given to o. The division circuit 10 divides the predetermined reference value input from the input terminal 11 by this added value, and the quotient is given to one input terminal of the addition circuit 12. The same value as the value given to one input terminal is input to the other input terminal of the adder circuit 12 only at the beginning, and thereafter the value output from the shifter 13 is input. The value output from the adder circuit 12 is given to the shifter 13, and 1 is added to the LSB side.
Output after bit shifting. By repeating this operation for each vertical period, the average value of the above quotient for each vertical period is calculated. This average value output from the shifter 13 is given to the multiplication circuit 7, which multiplies the chroma signal from the input terminal 1 by using this average value as a multiplier, so that an output signal of a predetermined level is output to the output terminal 8. taken out,
The ACC operation is performed in this manner.

As described above, in this embodiment, the amplitude values of the burst signals are added for each horizontal period, a predetermined reference value is divided by this added value, and the average value of this quotient for each vertical period is calculated. This is used as the multiplier of the multiplier circuit, which simplifies the circuit configuration compared to the conventional method in which the multiplier of the multiplier circuit is determined from the error signal using logic. Also, the level of the resulting burst signal is significantly reduced by pulse noise, etc. Even when the amplitude changes, the operation of the ACC circuit is more stable than in the conventional case where the multiplier of the multiplier circuit is determined based on the maximum amplitude value of the burst signal.

[Effects of the Invention] As described above, according to the present invention, the amplitude value calculation means calculates the amplitude value of the burst signal of the chroma signal, and the addition means adds the outputs of the amplitude value calculation means every horizontal period,
The division means divides the predetermined reference value by the output of the addition means for each horizontal period, and the average value calculation means divides the output of the division means by 1.
The average value for each vertical period is calculated, and the output of the average value calculation means is multiplied by the O signal using the multiplication means.
An ACC circuit with a simple circuit configuration and stable operation can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an ACC circuit according to an embodiment of the present invention. FIG. 2 is a block diagram showing a conventional ACC circuit. In the figure, 1, 5, 11 are input terminals, 2 is a burst amplitude value calculation circuit, 3 is a maximum amplitude value acquisition circuit, 4 is an error signal generation circuit, 6 is an accumulator, 7 is a multiplication circuit, and 8 is an output terminal , 9 and 12 are adder circuits, 1o is a division circuit, and 13 is a shifter. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] An input terminal into which a chroma signal including a digitized burst signal is input; amplitude value calculation means for calculating the amplitude value of the burst signal of the chroma signal from the input terminal; addition means for adding the output of the value calculation means every horizontal period; division means for dividing a predetermined reference value by the output of the addition means for every horizontal period; and an average value of the output of the division means for every vertical period. An ACC circuit comprising: an average value calculation means for calculating; and a multiplication means for multiplying the output of the average value calculation means by the chroma signal from the input terminal.