JPS60216389A - Driver for thin film el display unit - 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 Technical Field The present invention relates to a drive device for a thin film EL display device.

<Prior Art> Thin film EL display devices are AC driven capacitive flat matrix display panels and require high voltage driving.

Conventionally, for such thin film EL display devices, for example, as explained in detail in the special feature "Practical Technology of Thin Film Electroluminescent (EL) Character Display" in the April 2, 1979 issue of Aperture Electronics, The drive device is configured by combining a high voltage N-ch MOS driver having only a pull-down function and a diode having a pull-up function.

However, in this drive device, the phase of the write pulse changes sequentially along the scan electrode with respect to the refresh pulse. (2) A DC voltage is generated depending on the pre-charging voltage depending on the selection or non-selection of the data side electrode. (2) The amplitudes of the refresh pulse and write pulse are asymmetric. These (d,
In an AC-driven thin film EL display device, the slope of the voltage-luminance characteristics became gradual over the course of 5 hours, causing undesirable phenomena in terms of long-term reliability such as deterioration of display quality.

<Object of the Invention> The present invention skillfully combines an N-ch MOs driver having only a pull-down function and a P-ch MOs driver having a pull-up function as a drive circuit for scanning side electrodes, and This realizes so-called field inversion drive in which the polarity is reversed for each sequential drive (sequential drive), and provides a drive device with high long-term reliability in display quality etc. for AC drive type, capacitive thin film EL display devices. It is.

<Example> An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing an example of the configuration of a drive circuit according to the present invention.

Reference numeral 10 indicates a thin film EL display device, and in this figure, only the electrodes are shown, with the X direction electrode being the data side electrode and the Y direction electrode being the scanning side electrode.

20.30 is a scanning side N-ch high voltage MOS I corresponding to the odd number line and even number line of the Y direction electrode, respectively.
In C, 21.31 is a logic circuit such as a shift register in each IC. 40.50 is surface scanning side P-ch high voltage MO
5 IC, 41.51 is a logic circuit such as a shift register in each IC.

60 is a data side N-ch high voltage MO5IC, 61 is an I
This is a logic circuit such as a shift register in C.

70t/i data side diode array, which provides isolation of data side drive lines and reverse bias protection of switching elements.

These are an 80r/'i preliminary charge drive circuit, a 90% pull-up charge drive circuit, and a 100t/'i write/refresh drive circuit. In addition, 110 is a scanning side N-ch high voltage MO8IC
The source potential switching circuits 20 and 30 normally maintain the ground potential. 120 is a data side refresh drive circuit.

Figure 2 shows the on/off timing of each circuit section and each element.
FIG. 3 shows applied voltage waveforms with picture elements A and B in FIG. 1 as representative examples.

Hereinafter, the operation of the present drive device will be explained with reference to FIGS. 2 and 3. Note that here, Y including picture element A is line-sequentially driven.
It is assumed that the second scanning side electrode is selected. In addition, as will be described later, the polarity of the voltage applied to the picture elements is inverted for each field, and the first field is
The second field will be referred to as a P-ch field.

N-ch field In the N-ch field, scanning side N-ch high breakdown voltage M
The source potential switching circuit 110 of the OS ICs 20 and 30 always maintains the ground potential.

N-ch h1st stage Tl-Preliminary charging period □Scanning side N-
All MOS in ch high voltage MO8 IC20, 30)
Run raster N T 1- N T i is turned on. At the same time, the pre-charging drive circuit 80 (voltage %VM=30V
), the entire panel is charged via the data side diode array 70. At this time, data side N - c
h All MO3 in high voltage MO51C60) Run raster N
tl~Ntj and scanning side P-ch high breakdown voltage MO8/IC4
Total MO8) run raster P Tl −P T within 0,50
All i are kept off.

N-ch second side, scanning side N-ch high voltage MOS IC20
.

All MO8 in 30) Run raster N T 1 - N T
i is turned off, and the data side N-ch (MOS) run raster (Nt
2) is turned off, and the MOS run rasters Ntl-Ntj connected to the other data-side drive electrodes are turned on. At the same time, the scanning side P-ch high withstand voltage MO5
All MOS transistors PT1 to P in IC40.50
Turn on Ti. Non-selected electrodes on the data side (xjz
) is the data side N-ch high breakdown voltage MO5 in the on state.
MOS in IC60) run raster Ntl to Ntj (Nt
2) and scanning side P-ch high voltage MOS IC4
The ground loop is formed by all the MOS transistors PT1 to PTi in the memory cells 0 and 50 and the diode 101 in the write/refresh drive circuit 100 for discharging.

After that, the pull-up charging drive circuit 90 (voltage %VM-30V
) is turned on, and all scanning side electrodes are raised to a potential of 30V. At this time, scanning side N-ch high breakdown voltage MO3 I
All MO3 in C20.30) Run raster NT1 to NTi
Leave it in the off state. As a result, considering the scanning side electrode (Y) as the center, the selected data side electrode (X2) is +
30V, and the unselected data side electrode (Xj key 2) is in a -30V state.

Since the scanning side electrode selected in the line sequential drive is Y2, only the MOS transistor T2 connected to Y2 in the scanning side N-ch high voltage MO8 IC 30 is switched to the ON state. , rare even line side P-ch high voltage MO
All MOS transistors PT, -PTi in 3IC50 are turned off.

At this time, all MO3) run raster FTI~P in the P-ch high voltage MOS 1c40 on the opposing odd line side
Ti-1 is in the on state. And at the same time.

Write/refresh drive circuit 100 (here, voltage V
By turning on the voltage W=190V, all odd-numbered scan side electrodes are raised to 190V via all MO5) run rasters PTl to PTi in the odd-numbered line side P-ah high breakdown voltage MO5 IC40.

As a result, due to the nature of capacitive coupling, the data-side selection drive electrode is pulled up to VW+%VM=220V, and the data-side non-selection electrode is pulled up to VW-%VM=160V.

If the selected scanning electrode fYl is on the odd line side,
Scanning side N-ch high voltage MO3 1 MO in IC20
S) P-ch high voltage MO facing the run raster
All MO8 in SIC5Q) Run raster PT2~PTi
is turned on and all even-numbered scan electrodes are raised to 190V.

As described above, the same driving as from the first stage to the third stage, which was explained using the scanning side electrode Y2 as an example, is performed sequentially from the scanning side electrodes Y1 to Yi, and the refresh is performed during the blanking period when the first P-ch field starts. Drive.

N-ch refresh drive period (RF) - Scanning side N-ch high breakdown voltage MO3 1c20.30 is turned off, data side N-ch high breakdown voltage MO3 IC60 and scanning side P
-ch high voltage MO8 Turn on all MO3) run rasters in IC40, 50, lower the data side drive electrode to ground potential, and scan side write/refresh drive circuit 1
00 is turned on and the scanning side drive electrode is set to VW (=1
90V) and apply a refresh pulse (1) with the opposite polarity to the write waveform of the N-ch field.

Next, the scanning side P-ch high breakdown voltage MO51c40°50 and the data side N-ch high breakdown voltage MOS IC60 are turned off, and all MO5) run rasters NTl to NTi in the scanning side N-ch high breakdown voltage MO8IC20, 30 are turned on. state, pulls the scanning side drive electrode to ground potential, turns on the data side refresh drive circuit 120, and connects the data side drive electrode to VW via the data side diode array 70.
(/=190 VII, refresh pulse +11) and refresh pulse (2) with opposite polarity and equal applied voltage is applied.

At this time, the refresh pulse [11(2) causes E
Due to the polarization effect of the L panel, only the picture elements that emit light when a write pulse is applied emit light.

Although two refresh pulses are added here, only the refresh pulse (1) having the opposite polarity to the field write waveform may be used. By this refresh pulse (1) or (1) and [2], only the picture elements that emit light when the write pulse is applied cause re-emission due to the polarization effect of the EL panel. After this refreshing drive, P-c
Let's move on to driving the h field.

P-ch field P-ch first stage T1'2 Pre-charging period - This pre-charging period is carried out in exactly the same way as the N-ch field first stage.

P-ch 2nd batch Next, scanning side N-ch high voltage MOS IC20.

Turn off all MO8) run rasters NT1 to NTi in 30, and turn off the data side N-ch high voltage MO8 IC60.
In contrast to the case of the N-ch field, a run raster (MOS) connected to the selected data side drive electrode is
For example, only Ni2) is left in the on state, and the MOS) run raster Ntl to Nt connected to the other data side drive electrodes.
j (excluding Ni2) to the off state. At the same time, all the Mos transistors PT1 to PTi in the scanning side P-ch high breakdown voltage MO8 IC40.50 are turned on. The charge on the data side selection electrode is the data side N in the on state.
-ch high breakdown voltage MO5 IC60 MOS) run raster Nt2 and scanning side P-ch high breakdown voltage MO8IC40.

All MO5 in 50) are discharged by forming a ground loop by the run rasters PT1 to PTi and the diode 101 in the write drive circuit 100.

Then, the pull-up charging drive circuit 90 is turned on, and all the scanning side electrodes (Y) are pulled up to a potential of %VM=30V. At this time, scanning side N-ch high withstand voltage MO
All MO8 in SIC20.30) Run raster NT1~
Leave NTi in the off state. As a result, the scanning side electrode (Y
), the selected data side electrode (X2)
t/1-aov, the non-selected electrode (Xj 2) becomes +30V.

Assuming that the scanning side electrode selected by the third P-ch is Y2, the scanning side P
- ch MO connected to Y2 in high voltage IC50
S) Leave only the run raster PT2 in the on state and switch the others to the off state. Also, the scanning side N on the even-numbered line side
-ch High voltage MO8IC.

All MO5) in IC20 keep the run raster NT2 to NTi in the off state, and the scanning side N-ch high breakdown voltage MO8 on the opposite odd line side All MO8 in IC20) Run raster NTl-
Switch to NTi-1'i on state. And write/
The refresh drive circuit 100 (sum of electric power EEVW=190V and 3A V M =30V (7)) is turned on, and a voltage of 220V is supplied to the scanning side electrode Y2 via the run raster PT2 (MOS in the on state).

On the other hand, at this time, the source potential switching circuit 110 is 3AvM=
The voltage is switched to 30V, and the source potential in the N-ch high voltage MO5 IC20 on the odd line side is set to 30V.
Lower the scanning side electrode on the odd number side to +30V. As a result, the data side drive electrode
2 is lowered to -220V, and the unselected electrode X
j&+2 is pulled down to -160V.

If the selected scanning side electrode is an odd numbered line.

All MO5) run rasters NT2 to NTi in the scanning side N-ch high withstand voltage MO5 IC30 are turned on, which is opposite to one MO'S) run raster connected to the selected scan electrode in the scanning side P-ch high withstand voltage MOS IC40. state.

The scanning side electrode Y
Drive sequentially until 1 = Y i.

P-ch refresh drive period (RF') - Finally P
-ch Performs refresh drive for the h field.

Scanning side high voltage P-ch MOS IC40,50 and data side N-ch high voltage MO5IC20,30
5) Turn on the run rasters NT1 to NTi, pull down the scanning side drive electrode to ground potential, turn on the data side refresh drive circuit 120, and set the data side drive electrode to vw (-190) via the data side diode array 70.
V), and a refresh pulse C1f having a polarity opposite to that of the write waveform of the P-Ch field is applied.

Next, all MO5 in the scanning side N-ch high voltage MOS IC60 and the scanning side P-ch high voltage MOS IC40, 50
) The run raster is turned on, the data side drive electrode is pulled down to the ground potential, the scan side write/refresh drive circuit 100 is turned on and the scan side drive electrode is pulled down to VW (-1
90V) and apply a refresh pulse (refresh pulse 2) with the opposite polarity and equal applied voltage.

At this time, as in the case of the N-ch field, it is obvious that at least the refresh pulse (1)' is effective.

By alternately driving the N-ch field and the P-ch field as described above, as shown in the waveform diagram of FIG.
Field and P-ch field, light emission is performed at least twice by a write voltage VW+%VM (=220V) sufficient for light emission with reversed polarity and a refresh voltage VM (=190V) applied in each field knob blanking period. I do. In the tree embodiment, the refresh pulse is applied twice for each field, closing the alternating current cycle with the refresh pulses, but the N-ch field and the P-ch field are completely symmetrical as a whole. It is clear that two fields can close the alternating current cycle required for thin film EL displays. Note that VW-%VM (-160V) and refresh voltage VM (=190V) are applied to non-selected picture elements, but since the write voltage is below the light emission threshold, the polarization effect causes the refresh voltage to be applied. , it does not emit light.

FIG. 4 is a luminance-voltage characteristic diagram showing a comparison between the case where only a write pulse is applied and the case where both a write pulse and a refresh pulse are applied as in the present invention in field inversion driving.

As shown in the figure, it can be seen that with the device of the present invention, an image with even higher brightness can be obtained by adding a refresh pulse.

<Effects of the Invention> As described above, the present invention not only improves the symmetry of the phase and peak value of the write pulse, but also improves the symmetry at the DC level by using the precharging voltage and reduces the power consumption associated with precharging. It is possible to provide a useful drive device that can achieve high brightness while maintaining a high level of long-term reliability in display quality for AC-driven, capacitive thin-film EL display devices.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is an on/off timing diagram of each part to explain the operation of Fig. 1, and Fig. 3 shows the applied voltage waveform and light emission intensity of the picture element. The waveform diagram and FIG. 4 are luminance-voltage characteristic diagrams. 10... Thin film EL display device, 20.30... Scanning side N-ch high breakdown voltage MOS Ic, 40.50... Scanning side P-ch high breakdown voltage MO8I C, 60... Data side N- ch high voltage MO5IC, 70... diode array, 80... preliminary charge drive circuit, 9o... bow 1 raising charge drive circuit, 100... write/refresh drive circuit, 110... source potential switching circuit, 120...
Data side refresh drive circuit.・4, P patent attorney Aihiko Fukushi (and 2 others) Procedural amendment /P January 1985 To the Commissioner of the Patent Office (Japan Patent Office) 2. Name of the invention Driving of thin film EL display device Device 3, Relationship with the case of the person making the amendment Patent applicant 4, Agent Address: 545 U 545 Nagaike +11T22-2, Abekei-ku, Osaka City
No. 2 Sharp Co., Ltd. 6, Detailed explanation of the invention column 7 of the specification subject to amendment, contents of the amendment + 1) "Rare even number lie" on page 9, line 6 of the specification was changed to "
Also an even number rai,” I corrected myself. (2) "Write pulse" on page 11, line 15 of the specification will be corrected to "write pulse." (3) On page 15, line 17 of the specification, [Scanning side N-ch high withstand voltage MO3J is corrected to ``Data side N-ch high withstand voltage MO3J.''('2)

Claims (1)

[Claims] 1. In a driving device for a thin film E'L display device in which EL layers are interposed between scanning side electrodes and data side electrodes arranged in directions crossing each other, precharging, discharging/ Charging and writing 3
Perform stage drive. The N- electrodes are connected to the odd-numbered and even-numbered scanning side electrodes, and the other ends are commonly connected to the source potential switching circuit.
ch high voltage MOS driver, and a P-ch high voltage MOS driver whose other end is commonly connected to the pull-up charging drive circuit and the write/refresh drive circuit. Connected to the data side electrode. It includes an N-cb high voltage MOS driver whose other end is commonly connected to a pre-charge drive circuit and a data-side refresh drive circuit via a diode array. In the write drive period, the source potential switching circuit sets the source potential of the N-ch high voltage MOS driver on the scanning side to the grounded V or the raised charging potential to scan one screen (one field). 8) Run raster of one MOS of the odd-numbered or even-numbered scan-side N-ch high-voltage MOS driver and the opposing P-ch high-voltage MO of the other 8) all MOs of the driver.
3) Run raster and one MOS of the selected scan side P-ch high voltage MOS driver) Run raster and all MO5 of the other opposing N-ch high voltage MOS driver
) and the run raster are turned on alternately, and a write pulse with the polarity reversed is applied every field. During the blanking period after driving the final scanning electrode,
All MOs of the N-ch high voltage MOS driver on the data side and the P-ch high voltage MOS driver on the scanning side 8) Run raster is on, or the N-ch high voltage MOS driver on the data side is turned on.
All MO8) run raster of the S driver is turned off, and all MOS transistors of the N-ch high voltage MOS driver on the scanning side are turned off.
1. A driving device for a thin-film EL display device, characterized in that at least one refresh pulse having a polarity opposite to that of the write pulse is applied within one field while a refresh pulse is turned on.