JPH096288A - Liquid crystal display - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the power consumption of liquid crystal displays. A liquid crystal driving LSI 10 of this liquid crystal display device branches an output stop signal input to a driver circuit section 12 to provide an AND circuit 13 provided in a preceding stage of a logic circuit section 11.
And a clock signal from the outside is output to the logic circuit section 11 through the AND circuit 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device mounted on information equipment such as a portable computer and a word processor.

[0002]

2. Description of the Related Art Liquid crystal display devices such as a matrix type liquid crystal display device are currently widely used for information equipment such as portable computers and word processors. Due to the recent trend toward low power consumption of information equipment, There is an urgent need for liquid crystal display devices to deal with it.

A conventional matrix type liquid crystal display is composed of a connecting portion for exchanging signals with an external information device, a drive circuit, a liquid crystal panel and the like and is modularized. The drive circuit is formed into an LSI in the module and is usually called a liquid crystal drive LSI.

As shown in FIG. 2, a liquid crystal driving LSI 20
Is a logic circuit section 21 to which logic signals such as a data signal controlled at a predetermined timing through a connection section, a data reading clock signal, and a data latch signal are input, and an output signal from the logic circuit section 21 and an external signal. And an output stop signal, a bias signal, an AC signal, and an analog signal such as a power supply voltage.

This matrix type liquid crystal display is mounted on a battery-driven computer or the like and operates by connecting the connecting portions to each other.

In this case, the data signal,
When a clock signal, a data latch signal, etc. are input to the logic circuit section 21, the logic circuit section 21 controls the output timing of the data signal and outputs it to the driver circuit section 22.

The driver circuit section 22 generates a predetermined liquid crystal drive signal by combining the input of the data signal with the bias signal and the alternating signal, and outputs it to the liquid crystal panel.

A selection signal is applied line-sequentially from the liquid crystal driving LSI 20 to the scanning electrode group of the liquid crystal panel, and the data signal electrode group is turned on in synchronization with the waveform of the selection signal.
The liquid crystal panel is driven by applying the / OFF signal waveform.

By the way, in recent years, in order to reduce unnecessary power consumption of a battery as much as possible, a user does not operate a keyboard for a certain period of time in a battery-driven computer equipped with this type of matrix liquid crystal display. And the control signal (output stop signal) from the computer side to the matrix type liquid crystal display from "H" (high) to "L"
It has a function to switch to (low) and output to make the screen of the liquid crystal panel in a non-operating state.

Since this function is effective for the screen of the liquid crystal panel, the output stop signal is normally input to the driver circuit section 22 to turn on / off the switch provided inside the driver circuit section 22. The liquid crystal drive signal is output / stopped.

However, in this case, the LS for driving the liquid crystal
In the I driver circuit section, the output of the liquid crystal drive signal is simply stopped by the switch, so that the logic circuit section 21 located in the preceding stage operates normally and outputs the data signal. Therefore, although the screen of the liquid crystal panel is in a non-operating state, the logic circuit unit 21 consumes almost the same power as when operating.

[0012]

As described above, in the conventional liquid crystal display device, the output stop signal for stopping the output of the liquid crystal drive signal is input to the driver circuit section of the liquid crystal drive LSI, and the inside of the driver circuit section is inputted. Since the output of the liquid crystal drive signal was only stopped by the switch of, the logic circuit in the preceding stage maintains the operating state, and there is a problem that unnecessary power is consumed even when the screen is in the non-operating state. there were.

The present invention has been made to solve the above problems, and an object thereof is to provide a liquid crystal display device capable of reducing power consumption without changing the internal configuration of the driver circuit portion. There is.

[0014]

In order to achieve the above object, a liquid crystal display device according to claim 1 is a liquid crystal driving signal based on a control signal, an alternating signal and a bias signal inputted from the outside of the device. And a liquid crystal drive system that outputs and stops the liquid crystal drive signal according to a change in the control signal, a clock signal and a control signal input from outside the device, and a change in the control signal. Clock signal control means for outputting the clock signal according to the above, a clock signal output from the clock signal control means, and a data signal input from the outside of the apparatus based on a latch signal input from the outside of the apparatus And a logic system for controlling the timing and outputting to the liquid crystal drive system. The liquid crystal display device according to claim 2, further comprising a liquid crystal driving LSI for driving a liquid crystal panel based on a plurality of signals input from outside the device, wherein the liquid crystal driving LSI includes a data signal. A driver circuit that generates a liquid crystal drive signal based on an output stop signal, an AC signal, and a bias voltage that are input from outside the device, and outputs or stops the liquid crystal drive signal according to a change in the output stop signal. Section, an AND circuit that receives the clock signal and the output stop signal that are input from the outside, and outputs the clock signal according to a change in the output stop signal, and a clock signal that is input from the AND circuit ,
A logic circuit unit for timing-controlling a data signal input from the outside of the device based on a latch signal input from the outside of the device and outputting the data signal to the driver circuit unit.

[0015]

According to the first aspect of the present invention, the clock signal control means for outputting the clock signal input from the outside of the device to the logic system according to the change of the control signal input to the liquid crystal drive system is provided in the preceding stage of the logic system. Due to the provision, when the control signal changes, the output of the liquid crystal drive signal is stopped by the liquid crystal drive system and the output of the clock signal to the logic system is stopped.

Therefore, the screen of the liquid crystal panel becomes inoperative, and the operation of the logic system also becomes inactive.
Power is not consumed in each part.

According to the second aspect of the invention, an AND circuit for outputting a clock signal input from the outside of the device to the logic circuit section in response to a change in the output stop signal input to the driver circuit section is provided in the liquid crystal driving LSI. By providing,
When the output stop signal changes, the driver circuit section stops the output of the liquid crystal drive signal and also stops the output of the clock signal to the logic circuit section.

Therefore, the screen of the liquid crystal panel becomes non-operational, and the operation of the logic circuit section also becomes inactive, so that power is not consumed in each part.

As described above, the power consumption can be reduced without changing the internal structure of the driver circuit portion.

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram showing the structure of a matrix type liquid crystal display device according to an embodiment of the liquid crystal display device of the present invention.

This matrix type liquid crystal display device transmits and receives signals through a connecting portion connected to an external information device, for example, a main body portion such as a portable computer and a word processor. It has a liquid crystal driving LSI 10 to be driven.

As shown in FIG. 1, this liquid crystal driving LSI
Reference numeral 10 denotes a logic circuit section 11 to which logic signals such as data signals and data latch signals controlled at a predetermined timing are input through the connection section, an output signal from the logic circuit section 11 and an output stop signal from the outside. (Control signal), bias signal, AC signal, analog signal such as power supply voltage, and the like
AND which is provided in the preceding stage of the logic circuit unit 11 and receives a clock signal for reading data from the outside and the output stop signal through the connection unit, takes the logical product of the signals and outputs the logical product to the logic circuit unit 11. And a circuit 13. A switch (not shown) is provided in the driver circuit section 12 to stop the output of the liquid crystal drive signal to the liquid crystal panel when the input output stop signal is switched from the logic level “H” (high) to “L” (low). ) Is provided.

Next, the operation of this liquid crystal display will be described.

In the case of this liquid crystal display, during normal operation, a control signal (output stop signal) "H" (high) and a clock signal are input to the AND circuit 13 from the main body portion of a portable computer or the like through the connection portion, As a result of taking the logical product of each other, the clock signal is output to the logic circuit unit 11.
A data signal, a data latch signal and the like are also input to the logic circuit section 11 through the connection section.

Then, in the logic circuit section 21, the driver circuit section 1 is controlled by controlling the timing of outputting the data signal based on the frequency of the clock signal and the latch signal.
Output to 2.

The driver circuit section 12 generates a predetermined liquid crystal drive signal by combining the input of the data signal with the output stop signal "H", the bias signal and the alternating signal, and outputs it to the liquid crystal panel.

A selection signal is line-sequentially applied from the liquid crystal driving LSI 10 to the scanning electrode group of the liquid crystal panel, and the data signal electrode group is turned on in synchronization with the waveform of the selection signal.
The liquid crystal panel is driven by applying the / OFF signal waveform.

On the other hand, in a portable computer or the like, if the user does not operate the keyboard for a certain period of time, a control signal (output stop signal) from the computer side to the liquid crystal display device is changed from "H" (high) to "L". Switch to (low) and output.

Then, in the liquid crystal drive LSI 10, the switch inside the driver circuit section 12 is turned off, the output of the liquid crystal drive signal to the liquid crystal panel is stopped, and the screen of the liquid crystal panel is rendered inoperative.

Since the output stop signal is input to the AND circuit 13, when this signal is switched from "H" (high) to "L" (low), the AND circuit 13 outputs the clock signal. Be stopped.

Since the logic circuit section 11 basically operates in synchronization with the clock signal, the operation of the entire logic circuit section 11 stops when the clock signal is no longer input. As a result, in the liquid crystal drive LSI 10, the output of the liquid crystal drive signal from the driver circuit unit 12 is stopped, the operation of the logic circuit unit 11 is stopped, and almost no power is consumed.

As described above, according to the liquid crystal display of this embodiment, the output stop signal inputted to the driver circuit section 12 is branched and inputted to the AND circuit 13 provided in the preceding stage of the logic circuit section 11, and Since the clock signal from the outside is output to the logic circuit section 11 through the AND circuit 13, when the output stop signal from the portable computer changes from "H" to "L", the driver circuit section 12 drives the liquid crystal. Signal output and logic circuit unit 11
The operation of and can be stopped.

This makes it possible to reduce power consumption when the user is not using the driver circuit section 12 without changing the internal configuration of the driver circuit section 12 itself.

In the above embodiment, the logic circuit unit 1
An AND circuit 13 is provided as a clock signal control means in the preceding stage of 1.
However, the present invention is not limited to this. As the clock signal control means, for example, in terms of hardware, a simple changeover switch or a relay may be used. Other logic circuits such as a NAND circuit may be used depending on the logic level of the output stop signal.

[0036]

As described above, according to the first aspect of the invention, when the control signal input to the liquid crystal drive system changes, the clock signal control means provided in the preceding stage of the logic system supplies the clock to the logic system. Since the output of the signal is stopped, the output of the liquid crystal drive signal is stopped by the liquid crystal drive system, the screen of the liquid crystal panel becomes inoperative, the operation of the logic system is stopped, and the power is not consumed in each part.

According to the second aspect of the present invention, when the output stop signal input to the driver circuit section changes, the clock signal from the AND circuit is no longer output to the logic circuit section. Therefore, the driver circuit section drives the liquid crystal. The output of the signal is stopped, the screen of the liquid crystal panel becomes non-operational, the operation of the logic circuit section is stopped, and power is not consumed in each part.

As described above, the power consumption can be reduced without changing the internal structure of the driver circuit portion.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a liquid crystal driving LSI of a matrix type liquid crystal display according to an embodiment of the present invention.

FIG. 2 is an L for driving a liquid crystal of a conventional matrix type liquid crystal display.
It is a figure which shows the structure of SI.

[Explanation of symbols]

10 ... Liquid crystal driving LSI, 11 ... Logic circuit, 12 ...
Driver circuit section, 13 ... AND circuit.

Claims (2)

[Claims] 1. A liquid crystal that generates a liquid crystal driving signal based on a control signal, an alternating signal, and a bias signal input from the outside of the device, and outputs and stops the liquid crystal driving signal according to a change in the control signal. A drive system, a clock signal control unit that receives a clock signal and a control signal that are input from outside the device, and that outputs the clock signal in accordance with a change in the control signal, and an output from the clock signal control unit. And a logic system for timing-controlling a data signal input from the outside of the device based on a clock signal and a latch signal input from the outside of the device and outputting the data signal to the liquid crystal drive system. Liquid crystal display device. 2. A liquid crystal display device having a liquid crystal driving LSI for driving a liquid crystal panel based on a plurality of signals inputted from the outside of the device, wherein the liquid crystal driving LSI is inputted with a data signal and the outside of the device. A driver circuit unit that generates a liquid crystal driving signal based on the output stop signal, the alternating signal and the bias voltage, and outputs or stops the liquid crystal driving signal according to the change of the output stop signal; An AND circuit that receives the input clock signal and the output stop signal and that outputs the clock signal in response to a change in the output stop signal; a clock signal that is input from the AND circuit; A logic circuit unit for timing-controlling a data signal input from the outside of the device based on the latched signal and outputting the data signal to the driver circuit unit. A liquid crystal display device characterized by including the.