JPH07271327A - Driving circuit for el display device - Google Patents

Abstract

PURPOSE:To perform a high luminance display without using buffer memories. CONSTITUTION:A thin film EL panel (EL element) 1 is made to be a dual insulation construction and has a memory effect due to a polarization effect. A driving circuit consists of an upper screen scanning electrode driving circuit 2, a lower screen scanning electrode driving circuit 3, an upper screen data electrode driving circuit 4 and a lower screen data electrode driving circuit 5. The upper screen scanning electrode driving circuit 2 and the lower screen scanning electrode driving circuit 3 impress sequentially a writing voltage (-Vth) from the highest scanning electrode 71 on an upper screen 1a to the lowest scanning electrode 7n on a lower screen 1b and also impress a refresh voltage (+VR) to scanning electrodes 7n/2+1 to 7n on the lower screen 1b during the period when the write voltage (-Vth) is impressed on scanning electrode 71 to 7n/2 on the upper screen 1a, conversely to this, impress the refresh voltage (+VR) to scanning electrodes 71 to 7n/2 on the upper screen 1a during the period when the write voltage (-Vth) is impressed on scanning electrodes 7n/2+1 to 7n on the lower screen 1b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit for an EL (electroluminescence) display device, and more particularly to a drive circuit for an EL display device in which a screen is vertically divided and which has a polarization effect.

[0002]

2. Description of the Related Art Conventionally, a drive circuit has been known in which a screen is divided into upper and lower parts and upper and lower parts are simultaneously line-sequentially scanned in order to perform high-luminance display in an EL display device (for example, for example, JP-A-59-116791,
(See Japanese Patent Application Laid-Open No. 1-319092).

[0003]

However, in the case of a drive circuit which scans the upper and lower screens line-sequentially, a data signal for one screen is temporarily stored in a buffer memory such as a video RAM and the upper and lower screens are line-sequentially. At the time of scanning, it is necessary to read out the data signals for the upper and lower screens from the buffer memory and to scan the upper and lower screens line-sequentially (for example, Japanese Patent Laid-Open No. Hei 2).
-222090).

Therefore, in the conventional driving circuit for scanning the upper and lower screens simultaneously in a line-sequential manner, a buffer memory is indispensable, and a buffer memory having a large capacity is required as the number of pixels and the number of gradations increase. Therefore, there is a problem that the circuit scale becomes large.

Therefore, in the drive circuit of the EL display device according to the first aspect, attention is paid to the fact that the EL element having the double insulation structure has a memory effect due to the polarization effect, and high-luminance display is performed without using a buffer memory. The purpose is to let.

The drive circuit for an EL display device according to a second aspect of the present invention is an EL display device that adopts a method of applying a refresh voltage to scan electrodes in a line-sequential scanning manner, with a high-luminance display without using a buffer memory. The purpose is to do.

The drive circuit for an EL display device according to a third aspect of the present invention is an EL display device that employs a system in which a refresh voltage is simultaneously applied to scan electrodes for each divided screen.
The purpose is to perform high-intensity display without using a buffer memory.

[0008]

For the above-mentioned purpose, the method according to claim 1
In the drive circuit of the EL display device according to the above, the screen is divided in the vertical direction, and in the drive circuit of the EL display device having a polarization effect, writing is performed in order from the uppermost scan electrode of the upper screen to the lowermost scan electrode of the lower screen. While applying a built-in voltage, a refresh voltage is applied to the scan electrodes of the lower screen during a period in which a write voltage is applied to the scan electrodes of the upper screen,
On the contrary, it is characterized in that the refresh voltage is applied to the scan electrodes of the upper screen while the write voltage is applied to the scan electrodes of the lower screen.

According to a second aspect of the present invention, there is provided a drive circuit for an EL display device according to the first aspect, wherein the refresh voltage is synchronized with application of a write voltage to scan electrodes on the upper screen. Then, the voltage is applied to the scan electrodes of the lower screen corresponding to the same order as the scan electrodes of the upper screen, and in synchronization with the application of the write voltage to the scan electrodes of the lower screen. It is characterized in that the voltage is applied to the scan electrodes of the upper screen corresponding to the same rank as the scan electrodes.

According to a third aspect of the present invention, there is provided a drive circuit of an EL display device according to the first aspect, wherein the refresh voltage is applied to each of the upper screen and the lower screen at the same time. Is characterized by.

[0011]

In the drive circuit of the EL display device according to the first aspect of the present invention, although the screen is divided in the vertical direction, the line-sequential scanning in which the write voltage is applied to the scan electrodes is performed in the upper and lower screens simultaneously. This is not the conventional method of line-sequential scanning, and is the same as line-sequential scanning for a normal screen in which the screen is not vertically divided. Therefore, it is not necessary to store the data signal, and the buffer memory becomes unnecessary. In addition, when a refresh voltage is applied, polarization is generated in a pixel that emits light when a write voltage is applied immediately before, and the polarization effect allows light to be emitted again. Therefore, high-luminance display can be performed as in the conventional drive circuit of the EL display device in which the screen is divided in the vertical direction.

Further, according to the driving circuit of the EL display device of the second aspect, in the EL display device which adopts a method of applying the refresh voltage to the scan electrodes in a line-sequential scanning manner, a high brightness is obtained without using a buffer memory. The display can be performed.

Further, according to the drive circuit of the EL display device of the third aspect, in the EL display device which adopts the method of simultaneously applying the refresh voltage to the scan electrodes for each divided screen, a high brightness is obtained without using a buffer memory. The display can be performed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration of an EL display device incorporating a drive circuit according to an embodiment, FIG. 2 is a detailed configuration of the drive circuit, and FIG. 3 is a timing chart for explaining the operation thereof. Shown respectively.

In FIG. 1, a thin film EL panel (EL element) 1 of an EL display device has a double insulating structure and has a memory effect due to a polarization effect. The thin film EL panel 1 is divided into upper and lower parts, and the upper screen 1a
And a lower screen 1b. This thin film EL panel 1
The drive circuit for driving the upper screen scan electrode drive circuit 2, the lower screen scan electrode drive circuit 3, and the upper screen data electrode drive circuit 4 are
And a lower screen data electrode drive circuit 5. The upper screen scan electrode drive circuit 2, the lower screen scan electrode drive circuit 3, the upper screen data electrode drive circuit 4, and the lower screen data electrode drive circuit 5 are connected to a timing control circuit 6, and these drive circuits 2
The output timings of 5 to 5 are determined by the control signal output by the timing control circuit 6 which receives the horizontal synchronizing signal and the vertical synchronizing signal. In addition, the upper screen data electrode drive circuit 4
The upper screen display data and the lower screen display data are input to the lower screen data electrode driving circuit 5, respectively.

The upper screen scan electrode drive circuit 2 is shown in FIG.
As described above, the shift register 2a and the plurality of driver ICs 2b
Composed of and. The shift register 2a has n / 2 bits
It is composed of a shift register and has n / 2
Scanning electrode 7₁ ~ 7_{n / 2} The uppermost scanning electrode (of the first row
Scanning electrode) 7₁ To the lowest scan electrode (n / 2th row)
Scanning electrode) 7_{n / 2} Drive that can sequentially drive up to one by one
The contents are stored, and the timing control circuit 6
Shift operation is performed at the timing based on the control signal of
It is configured to output the stored contents to each driver IC 2b.
ing. The driver IC 2b is connected to each scan electrode 7₁ ~ 7_{n / 2} 
And n / 2 bit shift register
Depending on the stored contents of the corresponding bit of the star 2a.
Write voltage (-V_th), Positive refresh voltage (+
V_R ) Or ground voltage to scan electrode 7 ₁ ~ 7_{n / 2} Apply to
Is configured. Here, the write voltage (-V_th) And reflation
Voltage (+ V_R ) Are output alternately.

As shown in FIG. 2, the lower screen scan electrode drive circuit 3 is composed of a shift register 3a and a plurality of driver ICs 3b, like the upper screen scan electrode drive circuit 2.
The shift register 3a is composed of an n / 2-bit shift register, and has n / 2 scan electrodes 7 _{n / 2 + 1} to _{n of} the lower screen 1b.
7 _n can be sequentially driven one by _one from the highest scan electrode (scan electrode of the (n / 2 + 1) th row) 7 _{n / 2 + 1} to the lowest scan electrode (scan electrode of the nth row) 7 _n. The drive contents to be stored are stored, and the shift operation is performed at a timing based on the control signal from the timing control circuit 6 to output the stored contents to each driver IC 3b. The driver IC 3b is provided in a one-to-one correspondence with each of the scan electrodes 7 _{n / 2 + 1 to} 7 _n, and writes in the negative polarity according to the stored content of the corresponding bit of the n / 2 bit shift register 3a. Voltage (-V _th ), positive refresh voltage (+ V
_R ) or ground voltage is applied to the scan electrodes. Here, writing voltage (-V _th) and a refresh voltage (+ V _R) is output alternately.

As shown in FIG. 2, the upper screen data electrode driving circuit 4 includes a shift register 4a and a plurality of driver ICs 4
b. The shift register 4a is composed of an m-bit shift register, and has m data electrodes (data electrodes from the first column to the m-th column) 8 of the upper screen 1a.
_The upper screen display data for ₁ to 8 _m is stored, and the shift operation is performed at the timing based on the control signal from the timing control circuit 6 to store the stored contents in each driver I.
It is configured to output to C4b. Driver IC4
b is provided in a one-to-one correspondence with each of the data electrodes 8 ₁ to 8 _m, and the modulation voltage (+ V _M ) or the ground voltage is applied to the data electrode depending on the stored content of the corresponding bit of the m-bit shift register 4 a. Is configured to apply to.

As shown in FIG. 2, the lower screen data electrode drive circuit 5 is composed of a shift register 5a and a plurality of driver ICs 5b, like the upper screen data electrode drive circuit 4. Shift register 5a is composed of m-bit shift register, and the lower screen display data for (scanning electrodes from the first column to the m column) 9 ₁ to 9 _m m pieces of data electrodes of the lower screen 1b stored data The shift operation is performed at the timing based on the control signal from the timing control circuit 6 and the stored contents are output to each driver IC 5b. The driver IC 5b is provided in a one-to-one correspondence with each of the data electrodes 9 _{1 to} 9 _m, and according to the stored content of the corresponding bit of the m-bit shift register 5a,
A modulation voltage (+ V _M ) or ground voltage is configured to be applied to the data electrodes.

Next, an example of the driving method by the driving circuit will be described with reference to FIG.

In the present embodiment, one frame is composed of an upper screen field and a lower screen field following the upper screen field.

In the upper screen field, the upper screen scan electrode driving circuit 2 starts from the first electrode on the upper screen scan side (the uppermost scan electrode of the upper screen) 7 ₁ to the n / 2nd electrode on the upper screen scan side ( The write voltage (-V _th ) is sequentially applied up to 7 _{n / 2} of the lowermost scan electrode of the upper screen, and in synchronization with the application of the write voltage, the lower screen scan electrode drive circuit 3 is used. , Lower screen scan side 1st (uppermost scan electrode of lower screen)
From 7 n _{/ 2 + 1,} until the (lowest scan electrodes of the lower screen) 7 _n lower screen scanning side n / 2-th electrode, so on are sequentially applying the refresh voltage (+ V _R), also on the screen field Then, in synchronization with the writing voltage application, the modulation voltage (+
V _M ) or the ground voltage is the i-th (i = 1, 2,
, M) is applied to the electrode 8 _i . Here, upper screen 1
In a, a voltage (+ V _M + V _th ) exceeding the light emission threshold voltage is applied to the light emitting layer of the pixel portion where the data electrode to which the modulation voltage (+ V _M ) is applied and the scanning electrode at this time intersect. , The pixel emits light, and in the light emitting layer of the pixel portion where the data electrode to which the ground voltage is applied intersects the scan electrode at this time, a voltage (+ V
_th ) is applied, the pixel does not emit light. on the other hand,
In the lower screen 1b, immediately before the pixels which emit light under the screen field, since it has a memory effect due to the polarization effect, even if a refresh voltage (+ V _R) is applied emits light, whereas, under the previous screen field Pixels that did not emit light in, because they do not have a memory effect due to polarization effect,
Refresh voltage (+ V _R) does not emit light be applied.

In the lower screen field, the lower screen scan electrode driving circuit 3 starts from the first electrode on the lower screen scan side (the uppermost scan electrode of the lower screen) 7 _{n / 2 + 1} to the lower screen scan side n / 2.
The write voltage (-V _th ) is sequentially applied to the 7th electrode (the lowest scan electrode of the lower screen) 7 _n , and the upper screen scan electrode drive circuit is synchronized with the application of the write voltage. 2, the first on the upper screen scan side (the uppermost scan electrode on the upper screen)
7 _1, until (lowest scan electrodes of the upper screen) 7 n _{/ 2} on the screen scanning side n / 2-th electrode, so on are sequentially applying the refresh voltage (+ V _R), also in the lower screen field, In synchronization with the application of the write voltage, the lower screen data electrode drive circuit 5 causes the modulation voltage (+
V _M ) or the ground voltage is the i-th (i = 1, 2,
, M) is applied to the electrode 9 _i . Here, lower screen 1
In b, since a voltage (+ V _M + V _th ) exceeding the light emission threshold voltage is applied to the light emitting layer of the pixel portion where the data electrode to which the modulation voltage (+ V _M ) is applied and the scan electrode at this time intersect with each other. , The pixel emits light, and in the light emitting layer of the pixel portion where the data electrode to which the ground voltage is applied intersects the scan electrode at this time, a voltage (+ V
_th ) is applied, the pixel does not emit light. on the other hand,
In the upper screen 1a, the pixels emitted in the screen field on immediately before, because it has a memory effect due to the polarization effect, and emitting a refresh voltage (+ V _R) is applied, whereas, on the previous screen field Pixels that did not emit light in, because they do not have a memory effect due to polarization effect,
Refresh voltage (+ V _R) does not emit light be applied.

As described above, according to the drive circuit of this embodiment, although the screen 1 is divided in the vertical direction, the write voltage (-V _th ) is applied to the scan electrodes 7 _{1 to} 7 _n . The line-sequential scanning is not the conventional method of line-sequentially scanning the upper and lower screens 1a and 1b at the same time, and is the same as the line-sequential scanning for a normal screen in which the screen 1 is not vertically divided. This eliminates the need to store data signals,
The buffer memory becomes unnecessary, and the circuit scale can be reduced. Furthermore, the refresh voltage (+ V _R) applied, and the polarization occurs in the pixel emitted by the write voltage application just before, it is possible to re-emit light by the polarization effect. Therefore, similarly to the conventional drive circuit of the EL display device in which the screen 1 is divided in the vertical direction, scanning can be performed at a frequency twice the normal scanning frequency, so that high-luminance display can be performed.

[0026] The present invention is scanned above such refreshing voltage (+ V _R) line-sequentially scanned electrodes 7 ₁ to 7
is not limited to the EL display device taking method to be applied to _n, other, the refresh voltage (+ V _R)
Scan electrodes 7 _{1 to} 7 _{n / 2} , 7 for each of divided screens 1a and 1b
_It can be easily applied to an EL display device that adopts a method of simultaneously applying to _{n / 2 + 1 to} 7 _n , and has the same effect.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an EL display device to which a drive circuit according to an embodiment is applied.

FIG. 2 is a configuration diagram of the drive circuit.

FIG. 3 is a timing chart for explaining the operation of the drive circuit.

[Explanation of symbols]

1a on the screen 1b bottom of the screen 2 on the screen scanning electrode drive circuit 3 under the screen scanning electrode driving circuit 4 on the screen data electrode driving circuit 5 lower screen data electrode driving circuit 7 ₁ scan electrodes 7 uppermost of the upper screen ₁ to 7-n _{/ 2} on the screen of the scanning electrode 7 n _{/ 2 + 1} to 7-lowest scanning electrodes 7 _n the bottom of the screen of the _n bottom of the screen of the scanning electrodes -V _th writing voltage + V _R refresh voltage

Claims (3)

[Claims] 1. A drive circuit of an EL display device in which a screen is divided in the vertical direction and has a polarization effect, a write voltage is sequentially applied from the uppermost scan electrode of the upper screen to the lowermost scan electrode of the lower screen. As the write voltage is applied to the scan electrodes of the upper screen, a refresh voltage is applied to the scan electrodes of the lower screen, and conversely, a write voltage is applied to the scan electrodes of the lower screen. A drive circuit for an EL display device, characterized in that a refresh voltage is applied to the scan electrodes of the upper screen during a period in which a voltage is applied. 2. The refresh voltage is applied to the scan electrodes of the lower screen corresponding to the same order as the scan electrodes of the upper screen in synchronization with the application of the write voltage to the scan electrodes of the upper screen. , And is applied to the scan electrodes of the upper screen corresponding to the same rank as the scan electrodes of the lower screen in synchronization with the application of the write voltage to the scan electrodes of the lower screen. Item 2. A drive circuit for an EL display device according to item 1. 3. The drive circuit for an EL display device according to claim 1, wherein the refresh voltage is applied simultaneously to each of the upper screen and each of the lower screens.