JPH0392891A - Controller of liquid crystal display device - Google Patents

Abstract

PURPOSE:To prevent liquid crystal from breaking by selecting a 1st AC signal which is initialized with a reset signal and a 2nd AC signal which is irrelevant to the reset signal according to the input state of the reset signal. CONSTITUTION:This control circuit is provided with a 1st AC signal generating circuit 1 which is initialized with the reset signal and generates the 1st AC signal by the input of a synchronizing signal and a 2nd AC signal generating circuit 2 which generates the 2nd AC signal by the input of a reference clock signal. Further, the circuit is provided with a selecting circuit 3 which outputs the 1st AC signal when the reset signal is false and outputs the 2nd AC signal when the reset signal is true. Consequently, a signal for AC generation is sent to the liquid crystal artificially while the reset signal in the true state is inputted to prevent the liquid crystal from breaking.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a control circuit for a liquid crystal display device, in which a pseudo alternating current signal is sent to the liquid crystal while a device reset signal is being input, and the liquid crystal is This relates to a control circuit to prevent it from being destroyed.

2. Description of the Related Art A control circuit for a conventional liquid crystal display device will be described with reference to FIG.

Referring to FIG. 3, numeral 1 denotes an alternating current signal generating circuit which supplies an alternating current signal to the liquid crystal of a liquid crystal display device, and when the reset signal input to the input terminal 12 is false, the synchronizing signal is input to the input terminal 11. When input, an AC signal is output from the output terminal 13, and when the synchronization signal is input while the reset signal is true, the AC signal generation circuit 1 is initialized, and an AC signal is output from the output terminal 13. It is configured to output a DC signal that is not converted to AC.

Problems to be Solved by the Invention However, in the control circuit of such a conventional liquid crystal display device, as shown in FIG. If the voltage continues to be input in the true state, the alternating current signal will not be generated, and the liquid crystal will not be converted to alternating current, but a direct current voltage will continue to be applied, and there is a risk that the liquid crystal will be destroyed.

The present invention has been made in view of this point, and is a liquid crystal display device that sends a pseudo alternating current signal to the liquid crystal while the real signal is being input, thereby preventing the liquid crystal from being destroyed. The purpose is to provide a control circuit.

Means for Solving the Problems In order to achieve the above object, the present invention provides a first alternating current signal generating circuit that is initialized by a reset signal and generates a first alternating current signal upon input of a synchronizing signal; Reseno 1-
a second alternating current signal generation circuit that is not initialized by the signal and generates a second alternating current signal upon input of the reference clock signal, the first alternating signal and the second alternating signal; and a selection circuit that outputs the first alternating current signal when the reset signal is false and outputs the second alternating current signal when the reset signal is true. This is a control circuit for a liquid crystal display device.

Effect of the Invention With the above-described structure, the present invention can prevent the liquid crystal from being destroyed by sending a pseudo alternating current signal to the liquid crystal while the reset signal is being input in the true state.

Embodiment FIG. 1 is a block diagram showing a control circuit of a liquid crystal display device according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes the AC signal generation circuit, which has an input terminal 11 for inputting an external synchronization signal, an input terminal 12 for inputting a reset signal, and generates an AC signal for the liquid crystal. It has an output terminal 13. Reference numeral 2 denotes a pseudo alternating current signal generation circuit, which has an input terminal 21 for inputting an external clock signal, and an output terminal 22 for outputting a pseudo alternating current signal for the liquid crystal.

Reference numeral 3 denotes a selection circuit, which is connected to the input terminal 31 for inputting the reset signal and the output terminal 13, is connected to the input terminal 32 for inputting the main AC conversion signal, and is connected to the output terminal 22, and is connected to the input terminal 32 for inputting the main AC conversion signal, and is connected to the output terminal 22 for pseudo AC conversion. It has an input terminal 33 for inputting a signal, and an output terminal 34 for outputting an AC signal for the liquid crystal.

Regarding the control circuit of the tree embodiment constructed as described above,
The operation will be explained below. FIG. 2 is a timing chart of the control circuit in the same embodiment. As shown in FIG. 2, when the reset signal at the input terminal 31 is true, the input terminal 3
The pseudo alternating current signal input to 3 is outputted from the output terminal 34 to the liquid crystal display device as an alternating current signal for liquid crystal, thereby preventing a direct current voltage from being applied to the liquid crystal. When the reset signal is false, the main alternating current signal input to the input terminal 32 is outputted from the output terminal 34 to the liquid crystal display device as an alternating current signal for the liquid crystal, and the original alternating current is applied to the liquid crystal. .

Effects of the Invention As described above, according to the present invention, the first alternating current signal generating circuit is initialized by a reset signal, the second alternating current signal generating circuit is not involved in the reset signal, and the first alternating current converting signal generating circuit is initialized by a reset signal. By providing a selection circuit and a backbone for selecting the alternating current signal and the second alternating current signal according to the input state of the reset signal,
To prevent destruction of a liquid crystal due to continued application of DC voltage to the liquid crystal even if a reset signal continues to be input in the true state due to a cause such as an object hitting the reset button of a machine AG and the button being pressed continuously. I can do it.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a control circuit of a liquid crystal display device according to an embodiment of the present invention, FIG. 2 is a timing chart of the control circuit in the same embodiment, and FIG. 3 is a control circuit of a conventional liquid crystal display device. FIG. 4 is a timing chart of a conventional control circuit. 1...This alternating current signal generation circuit, 2...
Pseudo AC signal generation circuit, 3...Selection circuit.

Claims (1)

[Claims] a first alternating current signal generation circuit that is initialized by a reset signal and generates a first alternating current signal upon input of a synchronization signal; a second alternating current converting signal generation circuit that generates an alternating current signal, and when the reset signal is false due to the input of the first alternating current signal, the second alternating current signal, and the reset signal, the 1. A control circuit for a liquid crystal display device, comprising a selection circuit that outputs a first alternating current signal and outputs the second alternating current signal when the reset signal is true.