JPS61286879A - Large integrated circuit for crt display - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is a method for generating video signals for displaying numbers, characters, figures, etc. on a CRT screen, and for displaying these character outputs extremely clearly. 0 Related to large-scale integrated circuits for CRT displays Conventional technology Large-scale integrated circuits for CRT displays are cathode ray tubes (CRTs).
Generates a video signal to display characters on top. In order to operate the internal logic circuit for generating this video signal, a reference pulse signal (this pulse signal is hereinafter referred to as a "reference pulse signal") is required.

Conventionally, this reference pulse signal has been generated by directly oscillating it in a pulse oscillation circuit inside a large-scale integrated circuit for CRT display.

Problems to be Solved by the Invention In such a conventional reference pulse signal generation method, CR
When a large-scale integrated circuit for T display is installed in a television receiver, the reference pulse signal or its harmonic components become high frequency noise and interfere with the signals of the electronic circuits in the television receiver.

Furthermore, as the oscillation frequency becomes higher, the oscillation circuit tends to operate more unstable and consume more current.

The present invention has been made in view of this point, and an object of the present invention is to effectively reduce high frequency noise generated from a reference pulse signal and current consumption.

Means for Solving the Problems In order to solve the above problems, the present invention makes the period of the pulse signal oscillated by the oscillator inside the large-scale integrated circuit for CRT display twice the period of the reference pulse signal, and the internal By changing the period to a month, high frequency noise generated from the reference pulse signal and current consumption are reduced.

Function The present invention doubles the period of the pulse signal oscillated by the oscillator inside the large-scale integrated circuit for ficRT display by the above-mentioned means, thereby effectively eliminating harmonic components that affect the TV87 receiver. At the same time, current consumption can also be reduced.

Embodiment FIG. 1 is a block diagram showing an embodiment of reference pulse signal generation according to the present invention. In Figure 1, 1 is a pulse signal oscillation circuit with a period twice that of the reference pulse signal, 2 is a pulse period control circuit that makes the period of the pulse signal monthly, 3 is a video signal generation circuit, and 4 is a video signal output terminal. It is.

The period of the pulse signal generated by the pulse signal generation circuit 1 is converted into a reference pulse signal by a pulse period control circuit 2 which converts the period of the pulse signal into a percentage. The video signal generation circuit 3 generates a video signal using the reference pulse signal and outputs it from the video signal output terminal 4.

Here, a specific example of the pulse period control circuit 2 that changes the period of the pulse signal shown in FIG. 1 to H will be explained with reference to FIGS. 2 and 3.

In FIG. 2, 5 is an input signal application terminal, 6 is a buffer circuit with a propagation delay dt, and 9 is an exclusive OR (9 exclusive OR circuit).The input signal application terminal 5 is connected to A in FIG. When the shown pulse signal is applied, the pulse signal applied to the input signal application terminal 6 is applied to the exclusive OR circuit from one input terminal 7 of the exclusive OR circuit without propagation delay. Exclusive O
Due to the propagation delay of the buffer circuit 6, a pulse signal delayed by a time Δ as shown in FIG. 3B is applied from the other input terminal 8 of the R circuit.

At this time, the exclusive OR appearing at output terminal 1o
The output pulse signal of the circuit 9 is as shown in FIG. 3C, and the period of this pulse signal is H of the period of the pulse signal applied to the input signal application terminal 5. The third diagram shows a standard reference pulse signal obtained by a conventional pulse signal oscillation circuit, and the pulse signal in FIG. 3C has the same period as this standard reference pulse signal.

Effects of the Invention According to the present invention, the period of the oscillation pulse signal generated in the oscillation circuit inside the large-scale integrated circuit for CRT display is equal to the period of the reference pulse signal for operating the internal logic circuit for generating the video signal. Since the frequency is twice that of the oscillation circuit, it is possible to effectively reduce harmonic components generated from the oscillation circuit, and to significantly reduce high frequency noise that affects television receivers. Furthermore, according to this integrated circuit, the current consumption can be reduced depending on the reduction in the oscillation frequency of the oscillation circuit.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram of the main part of the pulse signal control means of the invention, and FIG. 3 is an operation waveform diagram of the main part. 1...Pulse signal oscillation circuit, 2...Pulse cycle control circuit that changes the cycle of the pulse signal as a percentage, 3...
...Video signal generation circuit, 4...Video signal output terminal, 5...Input signal application terminal, 6...
...Buffer circuit, 7...Exclusive O
Input terminal of R circuit (exclusive OR), 8...Input terminal of exclusive OR circuit (exclusive OR),
9: Exclusive OR circuit (exclusive OR), 10: Output terminal of two-person exclusive OR circuit (exclusive OR). Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3

Claims (1)

[Claims] A configuration in which a reference pulse signal for operating a display signal control logic circuit is generated by an oscillation means for generating a pulse signal with a period twice that of the reference pulse signal, and a logic means for halving the period of the pulse signal. A large-scale integrated circuit for CRT display.