JPS636596A - Driving of matrix display panel - 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] [Summary] A method for driving a matrix display panel, in which the rise time of a write pulse that causes a selected display cell to emit light is sequentially shortened in the scanning order, and the deviation in luminance of light emission over the entire surface of the panel is reduced. It is possible to make it smaller.

[Industrial application field]

The present invention relates to matrix display panels, particularly thin film electroluminescent panels (hereinafter referred to as 1&thin 11Q E L
This relates to a method of driving a panel (referred to as a panel).

Thin-film EL panels are expected to be used in the displays of office terminals and desktop general-purpose calculators.
In order to manufacture terminals and the like at low cost, display panels are required to be lower in price, and there is a need for a highly reliable display device and a method for driving a matrix display panel with good display quality.

[Conventional technology]

FIG. 5 is a block diagram showing a conventional method for driving a thin film EL panel, and FIG. 6 shows a conventional driving waveform diagram.

In FIG. 5, the thin film EL panel 1 has a plurality of data electrodes D1 to Dm and scanning electrodes S1 to Sn arranged in a grid pattern, and an electro-optical body (not shown) is interposed at the intersection of the picture electrodes. display cells are formed. This thin film E
A drive circuit that drives the L panel 1 includes data electrodes D1 to D.
a data signal generation circuit 2 that supplies data pulses to a;
It consists of a scan electrode drive circuit 3 that supplies scan pulses to the scan types is1 to Sn.

The data signal generation circuit 2 includes a push-pull driver 4-, which is a field-effect transistor (FET) that supplies positive and negative voltages of the number of channels corresponding to the data electrode D1''Dm.
1 to 4-m, and a DC power supply 5 for push-pull drivers 4-1 to 4-m.

Further, the scan electrode drive circuit 3 includes push-pull drivers for each of the scan electrodes 51 to Sn. -1 to 7-n are connected, and the first reference voltage generation circuit 8 and the first scan pulse generation circuit 10 are connected to the FET source side wiring 15 of the push-pull drivers 7-1 to 7-n. Further, a second reference voltage generation circuit 9 and a second scan pulse generation circuit 11 are connected to the FET drain side wiring 16.

The first and second reference voltage generation circuits 8.9 are connected to a negative power supply 8-1°9-1 of negative polarity and the same voltage (-165V),
A positive power supply 8-2 with positive polarity and the same voltage (+165V),
9-2, the negative power source 8-1.9-1 and the positive power source 8-2.
9-2 and switches 8-3 and 9-3, respectively.

The first and second scan pulse generation circuits 10.11 are powered by power supplies for obtaining predetermined scan pulse voltages, for example, the first scan pulse generation circuit 10 is powered by a power supply 10-10 which outputs -190cm.
A power supply 10-2 for 1 and +190 V and a switch 10-3 for switching between the two power supplies are provided, and the second scanning pulse generation circuit 11 is provided with a power supply 11-1 for outputting -165V and a power supply 11-1 for outputting +215V.
Power supply 11-2 for v and switch 11 for switching between both power supplies
-3 is provided.

In addition, the FETs of push-pull drivers 7-1 to 7-n
A Zener diode 12 is connected between the source side wiring 15 and the drain side wiring 16 to protect the driver.

Next, the light emitting operation of the display cell will be explained with reference to FIG. In the first frame, the switches 8-3 and 9-3 of the first and second reference voltage generation circuits 8.9 are connected to the -165V power supplies 8-1 and 9-1, respectively, and the power supplies 8-
1 and 9-1 is applied to the source side wiring 15 and drain side wiring 16 of the push-pull drivers 7-1 to 7-n, and the voltage of -165V outputted from the push-pull drivers 7-1 to 7-n is applied to The reference voltage Vp is applied to each scan electrode S1.S2.
...Apply to Sn.

In this fully selected state, the first and second scan pulse generation circuits 10
．． 11 switches 10-3 and 11-3 are 190v
10-1 and a 165V power supply 11-1. The voltages of -19Ov and -165V from the power supply 10-1 and the power supply 11-1 are applied to the push-pull driver 7-1~? −
It is output to the source side wiring 15 and the drain side wiring 16 of n, respectively.

Push-pull drivers 7-1 to 7-n have both input voltages (
-190V, -165V) (7) Difference, -25V (
FIG. 6 (bl~(VY shown in C1) is taken out and a scanning pulse VY of -25V is applied to the display cell selected by the scanning position control signal inputted from the outside at the reference voltage Vp(-
165V) and sequentially connect each scan electrode Sl, S2.
・Apply to Sn.

- On the other hand, the data signal generation circuit 2 generates a 25V data pulse Vs shown in FIG. It is output to the selected electrode on the data electrode side in synchronization with the scanning pulse vY.

6(Q) to (gl) are cell drive waveforms applied as a composite voltage between the data electrode Di (i is a positive integer) and each scan electrode (Sl-Sn). is a scanning pulse vY and a data pulse Vs on the reference voltage Vp.
The write pulses el and fl are formed by superimposing the pulses el and fl.

gl is sequentially applied, thereby causing the selected display cell to emit light. However, the write pulses el and fLgl are for all selections in which all cells emit light, and the peak value is +215V. In the case of a half-selected state in which the display cells sequentially emit light, the peak value is 190V.

After the writing drive of the first frame is completed, the drive of the next second frame is performed using the power supply 8-2.9-2.10-2.11.
-2, a write pulse of opposite polarity to that of the first frame is created in the same manner as above, and the selected display cell is caused to emit light.

[Problem that the invention seeks to solve]

The write pulse applied to the display cell selected by the conventional driving method described above is applied to the scan electrodes SL, S2, . . . , Sn in this order, as shown in FIG. In this way, when the scan timing is sequentially shifted and the application timing of the write pulse changes from the rise of the reference voltage Vp, the polarized charge E generated during the previous write
q leaks and the polarized charge decreases. Therefore, this leaked charge Δεq increases sequentially to ΔEql, ΔEq2, . . . ΔEq3, depending on the application timing of the write pulse. Therefore, the effective electric field EB changes when the display cell is selected and the write pulse is applied, and the effective electric field EBI at the timing of FIG. 7(a) becomes high (, FIG. 7(b),
(C) Timing effective electric field ε82. It gradually decreases in the direction of EB3.

For this reason, there is a problem in that the brightness sequentially decreases in the scanning order, causing deviations in brightness on the surface of the thin film EL panel.

In view of the above-mentioned conventional situation, an object of the present invention is to provide a method for driving a matrix display panel that corrects the change in the effective electric field inside the panel that occurs after the application of a write pulse and provides uniform brightness on the surface of the thin film EL panel. It is said that

[Means for solving problems]

FIG. 1 is a diagram showing the principle of the driving method of the present invention.
Since the amount of light emitted from the panel is proportional to the change in the energy of the supplied write pulse, the rise time of the write pulse is changed according to the scanning order so that it becomes faster. In other words, a write pulse with a short rise time is applied to gradually increase the change in energy.

[Function] Generally, when the rise time of a write pulse in a thin film EL element is shortened, the luminance characteristic with respect to the write pulse becomes as shown in FIG. That is, a display cell whose scan order is early with respect to the write pulse A has a brightness of 81, and a display cell whose scan order is late with respect to the write pulse A has a brightness of B2.

When a write pulse with a short rise time is applied to the display cell whose scanning order is slow, the brightness B2 approaches the brightness B1. This is because by applying a rapidly changing write pulse, the energy of the charges moving inside increases, increasing the brightness.

〔Example〕

FIG. 3 is a block diagram of an embodiment of the present invention, in which the same parts as in the prior art are denoted by the same reference numerals, and the explanation thereof will be omitted. Resistors R1 to Rn are connected to the output terminals of the push-pull drivers 7-1 to 7-n on the scanning electrodes 31 to Sn side, and the scanning electrodes 51 to Sn are driven through the resistors. Therefore, the write pulse that drives the scan electrode 51xSn has a rise time of a time constant due to this resistance and the capacitance of the scan electrode corresponding to the resistance, so this resistance value is successively decreased in the order of scanning. to shorten the rise time. In this example, the resistance Rn is the smallest, the resistance value increases successively in the direction of the resistor R1, the rise time of the write pulse that drives the scan electrode S1 is the longest, and the rise time becomes shorter in the direction of the scan electrode Sn. Become.

The drive waveform of the write pulse according to the present invention is as shown in FIG. FIGS. 4(a) to 4(C) are the same as the conventional waveforms. As shown in FIG. 4 fd), (e), and (f), all selection write pulses e1. f1. gl rise time T1. T2...Tn
becomes smaller sequentially.

In the above explanation, the rise of the write pulse is adjusted using a resistor, but it goes without saying that there is no problem in adjusting the write pulse using other rise adjustment methods.

〔Effect of the invention〕

As described above, according to the present invention, the display brightness can be uniformly adjusted regardless of the position of the selected display cell, which is extremely effective in making the brightness of the matrix display panel uniform and improving the display quality.

[Brief explanation of drawings]

FIG. 1 is a principle diagram of the driving method of the present invention, FIG. 2 is a luminance-voltage characteristic diagram for explaining the present invention in detail, FIG. 3 is a block diagram of an embodiment of the present invention, and FIG. A driving waveform diagram of the present invention, FIG. 5 is a block diagram showing a conventional driving method, and FIG. 6 is a conventional driving waveform diagram. In the figure, 1 is a thin 11QEL panel, S1 to Sn are scanning electrodes, D1 to Dn are data bridges, and R1''Rn is a resistor. , 1.Also -4, lacquer invention, brown fruit bag, 'Fftshstr brightness - electrocline, oxbow, 2nd figure, 4th figure, total 1z moving cliff shape, 6th figure.

Claims (1)

[Scope of Claims] A plurality of display cells are formed by interposing an electro-optic body at each intersection of a plurality of scan electrodes (S1 to Sn) and data electrodes (D1 to Dm) arranged in a grid, The scanning electrode (S1~
Sn) and the data electrodes (D1 to Dm) have means (8, 9) for alternately applying reference voltages (Vp) of positive polarity and negative polarity, and the voltage applied to the scanning electrodes (S1 to Sn) A scanning pulse pressure (Vy) is sequentially applied superimposed on the reference voltage (Vp), and a data pulse (Vs) is applied to selected electrodes of the data electrodes (D1 to Dm) in synchronization with the scanning pulse. In the method for driving a matrix display panel, the write pulse (e1, f1, g1) for the fully selected state is applied to the selected display cell determined between the electrodes to cause the selected display cell to emit light. A method for driving a matrix display panel, characterized in that pulses (e1, r1, g1) are applied by sequentially shortening the pulse rise time according to the scanning order.