JP2004302173A - Driving method and driving gear for light emission display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving method for a light emission display device with which a display mode capable of saving electric power and prolonging the light emission lifetime of light emitting elements can be set. <P>SOLUTION: For example, two scanning lines adjacent to each other as a set are so arranged as to be respectively simultaneously scanned. During the scanning period of the two scanning lines, the same data signal is supplied from a data line. The scanning time of the scanning lines is doubled as compared with that in an ordinary scanning mode and the light emission time is doubled as well. Accordingly, the instantaneous luminance can be lowered by as much as the increased component of the light emission quantity by the simultaneous scanning mode and the driving electric power can be accordingly reduced. Also, the current flowing to the elements is dropped and therefore the light emission lifetime of the elements can be prolonged. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light-emitting display device using, for example, an organic EL (electroluminescence) element as a light-emitting element, and more particularly to a driving method and a driving apparatus capable of setting a display mode capable of saving power and extending the light emission life of the light-emitting element. About.
[0002]
[Prior art]
A display using a display panel in which light-emitting elements are arranged in a matrix has been widely developed. As a light-emitting element used for such a display panel, an organic EL element using an organic material for a light-emitting layer is known. Attention has been paid. This is due to the fact that the use of an organic compound that can be expected to have good light-emitting characteristics in the light-emitting layer of the device has promoted high efficiency and long life that can be put to practical use.
[0003]
As a display panel using such an organic EL element, a passive matrix display device in which the elements are arranged in a matrix has already been partly put into practical use. In this passive matrix EL display device, at each intersection of a plurality of scanning lines and data lines that intersect each other, organic EL elements are formed between the scanning lines and the data lines, and the scanning lines are sequentially scanned. By appropriately supplying a drive current to the data line while setting the potential, a desired image pattern or the like can be lit and displayed.
[0004]
This organic EL element has a luminescent life, and several measures for extending the luminescent life are introduced. A typical example is a structure in which a laminated structure of an EL element is covered with a resin film in order to block moisture (moisture) in the air (for example, Patent Document 1). There have been known ones in which physical measures have been taken, such as those sealed with a container and a desiccant or the like sealed inside (for example, Patent Document 2). In addition, there is a device in which a reverse bias is periodically applied to an EL element to extend the light emission lifetime (for example, Patent Document 3).
[0005]
[Patent Document 1]
JP-A-10-144468 [Patent Document 2]
Japanese Patent Application Laid-Open No. 9-148066 [Patent Document 3]
JP 2001-20377 A
[Problems to be solved by the invention]
By the way, it is known that the longer the driving current at the time of lighting driving, the shorter the light emitting life of the EL element. In this case, the element is particularly damaged by an overcurrent, and its life is extremely shortened. On the other hand, when the EL element is driven to be driven by a relatively small current, the life thereof can be significantly extended.
[0007]
For example, when an EL display panel is used for a display of a mobile phone, almost all of the time is in a standby state. Therefore, it is desired to preferentially reduce the driving current at this time. In addition, the effect of extending the life of the EL element can be expected. In this case, the light emission time of the element can be ensured and the power consumption can be reduced by devising the scan mode of the display panel.
[0008]
The present invention has been made based on the above-described technical viewpoint, and a light emitting display capable of reducing power consumption and extending a light emitting life of a light emitting element by switching a scanning mode of the light emitting element. It is an object of the present invention to provide a method and a device for driving the device.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a driving method of a light emitting display device according to the present invention, as described in claim 1, includes a plurality of scanning lines and data lines crossing each other, and a method of driving the scanning lines and the data lines. A method for driving a passive matrix light emitting display device in which light emitting elements are formed between the scanning lines and the data lines at each intersection, wherein M adjacent scanning lines are simultaneously scanned, and The characteristic feature is that the same data signal is supplied from the data line during the scanning period of the scanning line.
[0010]
According to a fourth aspect of the present invention, there is provided a driving device for a light emitting display device according to the present invention, wherein the plurality of scanning lines and the data lines cross each other, and the plurality of scanning lines and the data lines intersect each other. What is claimed is: 1. A driving device for a passive matrix light emitting display device, wherein light emitting elements are respectively formed between said scanning lines and said data lines at respective intersections of lines, wherein driving is performed in accordance with pixel information via said data lines. A drive circuit that supplies a data signal to the light-emitting element; and a scan circuit that sets a scan line to be scanned to a scan reference potential. The scan circuit simultaneously scans M adjacent scan lines with a scan reference potential. And the drive circuit applies the same drive data signal to the data lines during a period in which the M scanning lines are simultaneously set to the scanning reference potential. Characterized in that configured to feed.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an organic EL display device employing a driving method according to the present invention will be described based on an embodiment shown in the drawings. FIG. 1 shows an example of a passive matrix display panel and a driving device thereof. There are two methods of driving the organic EL element in this passive matrix driving method, namely, a cathode line scanning / anode line driving and an anode line scanning / a cathode line driving. The example shown in FIG. Fig. 3 shows a form of a line drive.
[0012]
That is, the anode lines A1 to An as n data lines are arranged in the vertical direction, and the cathode lines K1 to Km as m scanning lines are arranged in the horizontal direction. ), Organic EL elements E11 to Enm indicated by diode symbol marks are formed to constitute the display panel 1.
[0013]
Each of the EL elements E11 to Enm constituting the pixel has one end (the anode in the equivalent diode of the EL element) corresponding to each intersection point between the anode lines A1 to An extending along the vertical direction and the cathode lines K1 to Km extending along the horizontal direction. The terminal (terminal) is connected to the anode line, and the other end (cathode terminal in the equivalent diode of the EL element) is connected to the cathode line. Further, each of the anode lines A1 to An is connected to the anode line drive circuit 2, and each of the cathode lines K1 to Km is connected to and driven by the cathode line scanning circuit 3.
[0014]
The anode line drive circuit 2 includes constant current sources I1 to In that operate using a supply power VH and drive switches SX1 to SXn. The drive switches SX1 to SXn are connected to the constant current sources I1 to In. By connecting to the side, the currents from the constant current sources I1 to In act to be supplied to the individual EL elements E11 to Enm arranged corresponding to the cathode lines. The drive switches SX1 to SXn are configured to be connected to the ground side as a reference potential point when the current from the constant current sources I1 to In is not supplied to the individual EL elements.
[0015]
The cathode line scanning circuit 3 is provided with scanning switches SY1 to SYm corresponding to the respective cathode lines K1 to Km, and the corresponding cathode line is selected from the reverse bias voltage source VM or the ground potential as a scanning reference potential point. Acts to connect to one or the other. Thus, the respective EL elements are selected by connecting the constant current sources I1 to In to the desired anode lines A1 to An while sequentially setting each cathode line to the scanning reference potential point (ground potential) at a predetermined cycle. It can be made to emit light. The anode line drive circuit 2 and the cathode line scanning circuit 3 display an image corresponding to the video data on the display panel 1 in accordance with the video data supplied from the light emission control circuit 4 and supplied to the light emission control circuit 4. Acts to let.
[0016]
In this embodiment, in addition to the sequential scanning in which the scanning lines are selected and scanned one by one as described above, that is, in addition to the normal scanning mode, as described later in detail, adjacent M lines (in practice, A mode for simultaneously scanning the scanning lines of M = 2) is set. This mode is referred to herein as a simultaneous scanning mode.
[0017]
Therefore, when the simultaneous scanning mode of M = 2 is set, the cathode line scanning circuit 3 receives a command from the light emission control circuit 4 and sets two adjacent cathode lines as a set and simultaneously sets the scanning reference potential point. To the ground potential. In this case, the frame frequency is set to be the same as that in the normal display mode. Therefore, when the simultaneous scanning mode of M = 2 is set, the scanning time of the pair of cathode rays is doubled as compared with the normal scanning mode. In other words, the emission time of the EL element scanned and lit at this time is also doubled.
[0018]
At this time, the scanning switches SY1 to SYm are sequentially switched so that the reverse bias voltage from the reverse bias voltage source VM is applied to the other cathode lines not to be scanned. Thereby, a reverse bias voltage is applied to the EL element via the scanning line. Note that the state shown in FIG. 1 shows a state where the first and second cathode lines K1 and K2 are simultaneously scanned, and a reverse bias voltage is applied to the other cathode lines.
[0019]
The reverse bias voltage VM charges the parasitic capacitance of the driven EL element connected at the intersection with the cathode line selected for scanning, and also connects the driven anode line to the cathode line not selected for scanning. The EL element connected to the intersection acts to prevent crosstalk light emission due to leakage current. Generally, the voltage value of the reverse bias voltage VM is set to a value close to the forward voltage Vf of the EL element driven to emit light.
[0020]
On the other hand, in the anode line drive circuit 2, the above-described light emission control circuit causes any of the EL elements connected to the anode line to emit light at what timing and for how long based on the pixel information indicated by the image data. A drive control signal for controlling the operation is supplied. The anode line drive circuit 2 connects some of the drive switches SX1 to SXn to the aforementioned constant current sources I1 to In according to the drive control signal, and responds to the pixel data through the anode lines A1 to An. It acts to supply a drive current to the EL element.
[0021]
In this embodiment, as will be described later in detail, it is configured such that the same drive data can be supplied to adjacent N (in practice, N = 2) anode lines. I have. This is desirably performed in combination with the simultaneous scanning mode described above.
[0022]
FIG. 2 shows a specific example in which the same drive data is supplied to two adjacent anode lines as described above. The circuit configuration shown in FIG. 2 is arranged in anode line drive circuit 2 shown in FIG. In FIG. 2, A, C, E,... And B, D, F,... Constitute shift registers, and the shift registers indicated by A, C, E,. ., And the shift registers indicated by B, D, F,... Are herein referred to as even-numbered line shift registers.
[0023]
The operation clocks CK1 and CK2 are supplied to the odd-line and even-line shift registers via clock signal lines. Further, the serial data S1 is supplied to the odd-line shift registers, and the serial data S2 is supplied to the even-line shift registers. Then, the output of each register is supplied to the latch circuit 6, and is latched by a latch signal supplied at a predetermined timing.
[0024]
The latch output from the latch circuit 6 is supplied to each anode line shown in FIG. In this case, the drive switches SX1 to SXn shown in FIG. 1 are connected to the constant current sources I1 to In according to the latch output.
[0025]
FIG. 3 shows a relationship between a clock signal and latch data used in the configuration shown in FIG. That is, (a) shows a normal display mode, that is, a mode in which different drive data is supplied to each anode line, and (b) is shown as zoom display here, and two adjacent lines are displayed. A mode in which the same drive data is supplied to the anode line is shown.
[0026]
In the normal display mode shown as (a), the clock signals supplied to the odd-numbered lines and the even-numbered lines are in a state where the phases are inverted. Each of the registers functions to shift data at the rising edge of the clock signal. Therefore, in the normal display mode shown as (a), data is alternately shifted in the order of the odd-line shift register and the even-line shift register. By this. Different drive data is supplied to each of the anode lines A1 to An.
[0027]
In the zoom display mode shown as (b), the shift registers of the odd-numbered lines and the even-numbered lines simultaneously shift the data. As a result, the same data is output from the registers of the adjacent odd-numbered and even-numbered lines, and as a result, the same drive data is provided to each of the anode lines A1 to An for each of the adjacent odd-numbered and even-numbered anode lines.
[0028]
FIG. 4 schematically shows an image reproduction state on the display screen when the simultaneous scanning mode (M = 2) for simultaneously scanning M adjacent scanning lines is set as described above. (A) shows the state of the normal scanning mode, and (b) shows the display form of the simultaneous scanning mode when M = 2. FIG. 4C shows a two-dimensional data arrangement state at this time. In short, an image is displayed with the same data arranged in the scanning direction (Y direction). Therefore, the image is displayed in a state of being enlarged twice in the vertical direction (Y direction).
[0029]
According to this, the scanning time of the pair of cathode rays is doubled as compared with the normal scanning mode. In other words, the emission time of the EL element scanned and lit at this time is also doubled. Here, the light emission amount of the light emitting element is obtained by integrating the light emission luminance with time, and it can be said that if the light emission time is doubled, the light emission amount is also doubled. Accordingly, the instantaneous luminance can be reduced by the amount of light emission in the simultaneous scanning mode, and the driving power can be reduced accordingly. Further, the current flowing through the element can be reduced, so that the light emission life of the element can be extended.
[0030]
When the simultaneous scanning mode is executed, a vertically long unnatural image is obtained as schematically shown in FIG. 4B. In order to correct this, it is desirable to use the above-described zoom display mode together. FIG. 5 illustrates a state in which the simultaneous scanning mode (M = 2) and the zoom display mode (N = 2) are used together. Assuming that the image shown in (a) is a normal image, when the simultaneous scanning mode and the zoom display mode are used together, the display image becomes twice as long in the vertical and horizontal directions.
[0031]
According to this, a vertically long image using only the simultaneous scanning mode can be corrected. FIG. 5C shows a two-dimensional data arrangement state at this time. In short, the same data is arranged in the scanning direction (Y direction) and the direction orthogonal to the scanning direction (X direction).
[0032]
It is desirable that the simultaneous scanning mode and the zoom display mode described above are configured to be automatically set, for example, when the mobile phone is on standby. In particular, when the simultaneous scanning mode is set, a moderate light emission amount can be ensured even if the control in which the drive current of the EL element is slightly reduced is executed. Therefore, power saving and extension of the life of the light emitting element can be effectively achieved.
[0033]
When the simultaneous scanning mode is executed, although the resolution of the image is reduced, executing the same in the above-described standby state of the telephone has almost no effect. If necessary, the display may be easily returned to the normal display normal state.
[Brief description of the drawings]
FIG. 1 is a connection diagram showing an embodiment for realizing a driving method according to the present invention.
FIG. 2 is a block diagram showing a configuration example for realizing a zoom display mode.
FIG. 3 is a timing chart for explaining the operation of the configuration shown in FIG. 2;
FIG. 4 is a schematic diagram illustrating a case where a simultaneous scanning mode is executed.
FIG. 5 is a schematic diagram illustrating a case where a zoom display mode is used in combination with the simultaneous scanning mode.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 light emitting display panel 2 anode line drive circuit 3 cathode line scanning circuit 4 light emission control circuit 6 shift registers A1 to An anode line (data line)
K1 to Km Cathode ray (scanning line)
E11-Enm Organic EL device (light emitting device)
I1 to In Constant current sources SX1 to SXn Drive switches SY1 to SYm Scan switches VH Supply power supply VM Reverse bias voltage source

Claims (6)

Driving a passive matrix light emitting display device in which a plurality of scanning lines and data lines intersecting with each other, and at each intersection of the scanning lines and the data lines, light emitting elements are formed between the scanning lines and the data lines, respectively. The method,
A driving method of a light-emitting display device, wherein adjacent M scanning lines are simultaneously scanned, and the same data signal is supplied from the data lines during the scanning period of the M scanning lines. 2. The method according to claim 1, wherein the same data signal is supplied from adjacent N data lines during a period in which adjacent M scanning lines are simultaneously scanned. 3. The method according to claim 2, wherein the values of M and N are switched, and in any combination of M and N, one frame period is the same. Driving a passive matrix light emitting display device in which a plurality of scanning lines and data lines intersecting with each other, and at each intersection of the scanning lines and the data lines, light emitting elements are formed between the scanning lines and the data lines, respectively. A device,
A drive circuit that supplies a drive data signal corresponding to pixel information to the light-emitting element via each of the data lines; and a scan circuit that sets a scan line to be scanned to a scan reference potential. And the drive circuit sets the same drive data signal to the data line during a period in which the M scanning lines are simultaneously set to the scanning reference potential while the M scanning lines are simultaneously set to the scanning reference potential. A driving device for a light-emitting display device, characterized in that the driving device is supplied to the light-emitting display device. The drive circuit is configured to supply the same drive data signal to adjacent N data lines in a state where the scanning circuit sets M adjacent scan lines at the same time to a scanning reference potential. The driving device of a light emitting display device according to claim 4, wherein The driving device for a light-emitting display device according to claim 4, wherein the light-emitting element is an organic EL element using an organic compound for a light-emitting layer.

Images