JPS59116792A - liquid crystal display device - 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] The present invention relates to a liquid crystal display system.

As is well known, when a DC voltage is applied to a liquid crystal display device, its lifespan is extremely reduced. Therefore, when driving the liquid crystal, AC driving is performed using a multi-value pulse signal.

In addition, liquid crystal display devices generally have negative temperature characteristics, so in order to eliminate erroneous display within the operating temperature range,
It is necessary to use a drive voltage that is compensated for the temperature characteristics of the liquid crystal display device.

In a conventional liquid crystal drive circuit, a temperature compensation circuit is provided in the multi-value voltage generation circuit (power supply voltage of the drive circuit). This temperature? 'ili compensation requires a complicated temperature compensation circuit for each voltage, and it is extremely difficult to form its temperature characteristics. In particular, when a temperature compensation circuit is provided in a semiconductor integrated circuit, it is affected by variations in elements and the like, which causes a deterioration in product yield.

The inventor of the present application focused on the fact that when dynamically driving a liquid crystal display device, selection/non-selection is performed depending on the effective voltage, and considered performing temperature compensation by controlling the pulse duty of the liquid crystal drive waveform. .

An object of the present invention is to provide a liquid crystal display method that can perform temperature compensation with a simple circuit configuration.

Another object of the present invention is to provide a liquid crystal display system suitable for semiconductor integrated circuit devices.

Further objects of the invention will become apparent from the following description and drawings.

Hereinafter, this invention will be explained in detail together with examples.

113th! ! J shows a diagram of an embodiment of the present invention.

What is indicated by symbol II is a liquid crystal panel, and although not particularly limited, a dot matrix is formed by scanning electrodes and signal electrodes.

The row driver 7 drives the scanning electrodes. The row driver 7 regularly supplies four-value voltages to the scanning electrodes according to timing signals from the timing control circuit 6.

A column driver 9 drives the signal electrodes.

This column driver 9 supplies a four-value impulse to the signal electrode in synchronization with a timing signal passed through a gate circuit 10 and in accordance with a display signal from a latch circuit 1/88. This launch circuit 8 takes in display data in synchronization with the clock from the timing control circuit 6. Thereby, the acquisition of display data and the drive timing of the signal electrodes are synchronized.

Oscillation circuit 1 forms a reference frequency signal. Although not particularly limited, a known crystal oscillation circuit using a crystal resonator is used. This 8-frequency output is frequency-divided by the frequency divider circuit 2 to form a basic clock necessary for the operation of the timing control circuit 6.

Further, this frequency dividing circuit 2 forms a plurality of pulse width signals for temperature compensation, which will be described later.

Temperature sensor 3 detects ambient temperature. Although not particularly limited, this temperature sensor is constituted by a temperature sensing element such as a thermistor.

The output signal of this temperature sensor 3 is converted into a digital signal by an A/D converter 4.

The plurality of pulse width signals formed by the frequency dividing circuit 2 are input to the multiplexer 5, and one of them is selectively input to the gate I circuit 10 according to the converted digital signal. This gate circuit 10 logically processes the pulse width signal and the timing signal from the timing control circuit 86 to control the output pulse width of the column driver 8:
shoot

Next, the temperature compensation operation of this embodiment will be explained according to the timing diagram of FIG.

The waveform shown by the solid line in FIG. 2(a') is the voltage waveform E11 applied to both electrodes of the dot which is in the selected state at the lowest operating temperature. The waveform shown by the solid line in FIG. 2B is the waveform applied to both electrodes of the dot which is in the non-selected state at the lowest operating temperature. In other words, the group circuit 10 transmits the evening and timing signals from the timing control circuit 6 as they are to the column driver 9 using the digital signal recorded at the lowest operating temperature. At this time, the effective value of the voltage applied to the liquid crystal panel II becomes maximum.

Next, as the temperature rises, the multiplexer 5 outputs a pulse signal having a pulse width corresponding to the temperature, for example as shown in FIG. The gate circuit 10 limits the timing to the column driver 9 using this pulse signal, as shown in FIG.

(b) The pulse width of the selection/non-selection voltage waveform is limited to a small value as shown by the broken line in -. Thereby, the effective voltage in the selected and non-selected states can be reduced. That is, it is possible to give a negative temperature coefficient to the liquid crystal driving voltage J.

Therefore, the negative temperature coefficient of the liquid crystal panel and the above-mentioned pulse width limit, in other words, the pulse duration of the liquid crystal drive voltage.
By matching the negative temperature coefficient of the effective voltage obtained by -T control, the temperature? You can earn 1 t.

In this embodiment, digital signal processing makes it possible to accurately compensate for the temperature of a liquid crystal panel having a different temperature coefficient. Furthermore, since the temperature compensation circuit can be constructed from a digital circuit, it can be suitable for semiconductor integrated circuits. And that temperature? The li IX operation has the advantage of not being affected by variations in device characteristics.

The invention is not limited to the above embodiments.

The liquid crystal may be composed of a common electrode and segment electrodes. Further, the Guinaminck driving force type can be modified in various ways. The method of controlling the pulse duty of the drive voltage applied to both sides of the liquid crystal at 4:1 can be modified in many ways.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is an operation waveform diagram for explaining its temperature compensation operation. 1. Oscillation circuit, 2. Frequency divider circuit, 3. Temperature sensor, 4. A/D converter to 5. Multiplexer, 6.
Timing control circuit, 7... row driver, 8... launch circuit, 9... column driver, 10... gate circuit,
11...Liquid crystal panel Figure 1 Figure 2

Claims (1)

[Claims] 1. An output that forms a pulse width signal that matches the temperature characteristics of the liquid crystal display device based on the output signal from the temperature sensor, and uses this pulse width signal to dynamically drive the liquid crystal display device. A liquid crystal display system characterized by controlling the effective voltage in accordance with the above-mentioned temperature characteristics by controlling the pulse duty of the waveform. 2. The output signal from the temperature sensor is converted into a digital value by an A/D converter, and synchronized with this basic clock using this digital value and a basic clock that dynamically drives the liquid crystal display device (2 pulse width Claim 1 is characterized in that it forms a signal train.
Liquid crystal display method described in section.