JP2004013115A - Method and device for driving display device using organic light emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a display quality by making it difficult to visually recognize scanning line, without raising a frame frequency for constituting a picture in a passive matrix type organic light emitting element display device. <P>SOLUTION: The selection order of scanning lines in one frame is prescribed to non-sequentially scan scanning electrodes in the passive matrix type organic light emitting element display device. Concretely, every other scanning electrode or every third scanning electrode is scanned or the scanning electrodes are scanned at random. Thus scanning line of high luminance in EL display are hardly visually recognized because scanning lines move more quickly than movement of eyes, so that a display quality is improved. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a driving method and a driving apparatus of a passive matrix type display device using an organic light emitting element that emits light by passing a current through an organic thin film.
[0002]
[Prior art]
In recent years, information has been diversified. Among them, display devices in the information field, including solid-state imaging devices, are being actively developed toward small size, thin shape, high definition, low power consumption, and high speed response. In particular, inventions of high-definition flat panel display devices have been widely made.
[0003]
As a liquid crystal display element or the like suitable for such a display device, an element having excellent characteristics such as viewing angle dependency and high-speed response has been studied and developed since the latter half of 1980. More specifically, an organic electroluminescence (hereinafter, referred to as an organic EL) element having a thin-film stacked structure of organic molecules, which can provide a high luminance of 1000 cd / m ² or more at an applied voltage of 10 V, is disclosed by Tang et al. (Appl. Phys. Lett., 51, 913 (1987)), research on the practical use of organic EL devices has been actively conducted. Further, similar devices using organic polymer materials are also being actively developed.
[0004]
Since an organic EL element can realize a high current density at a low voltage, higher luminous luminance and luminous efficiency can be expected as compared with an inorganic EL element and an LED. More specifically, the organic EL element has the following features of the display element: (1) high brightness and high contrast; (2) low voltage drive and high luminous efficiency; (3) high resolution; (4) high field of view; ▼ It has excellent characteristics such as fast response speed, 6) miniaturization and colorization, 7) lightness and thinness.
[0005]
Then, a plurality of wirings are arranged on the panel in a grid pattern, the horizontal wirings are used as scanning lines, the vertical wirings are used as data lines, and one pixel is formed between each scanning line and the data line. The elements are individually joined, the scanning lines are sequentially selected one by one, and the data corresponding to the selected scanning lines are sequentially applied to the data lines, so that the organic EL elements that are selectively energized are sequentially applied. Since the light is turned on, a simple matrix display can be easily performed, thereby obtaining a flat panel display device capable of performing high-quality image display.
[0006]
[Problems to be solved by the invention]
When an organic EL element having a high response speed is displayed in a simple matrix as described above, a very high-luminance linear light-emitting position (this is called a scanning line) is moved at a high speed. At this time, since the organic EL element has a high response speed, the light emission of each pixel ends immediately after scanning, and the next line emits light.
[0007]
Therefore, in this case, light emission is performed only on one line at a time, and an image is formed by utilizing the light emission using the afterimage effect of the eyes. Therefore, the luminance of the emitting line needs to be very high. The luminance needs to be at least twice as large as the number of scanning lines as compared with the luminance of the lines of a display panel including other display elements having a relatively slow response speed such as an inorganic EL element and an LED. Therefore, if the viewpoint is made to follow the change in the position of the line that emits light, the line of sight will be continuously viewed for more than the scanning time, and will be visually recognized as a bright line that is much brighter than the image. Would.
[0008]
Actually, the human naked eye is not stationary due to its characteristics, but keeps moving the viewpoint. At that time, when the movement of the viewpoint becomes closer to the scanning speed of the panel by accident, the movement of the viewpoint becomes closer to the movement of the scanning line, and it is several times to several tens times as compared with the case of viewing the image normally. Time and scan lines will be captured in the same area of the retina. As a result, an observer (user) visually recognizes as if a very bright line occurred in the screen for a moment (within one frame). This phenomenon is unusually impressive to the observer, and as a result of focusing on the bright lines, the visibility of the entire image is reduced, and furthermore, it is as if the image has defects. This gives the observer a bad impression that a malfunction or failure has occurred.
[0009]
As a means to solve this, it is conceivable to increase the frame frequency constituting the screen, but if this is performed, the frequency of the data signal transmission will be increased, which will increase the manufacturing cost. Since the number of times the organic light emitting element blinks per unit time increases, the power consumption of the panel increases due to charge / discharge, and the time response is limited by the capacity of the organic EL element. There is a drawback in that the longer the light emission, the longer the time until the start of light emission, and as a result, the brightness of the screen decreases.
[0010]
Japanese Patent Application Laid-Open No. 2000-148088 discloses that a plurality of pulses are applied to a data line within a scanning line selection period in order to perform gradation display (pixel brightness control) in one scanning line. Although a gray scale display method of expressing a gray scale according to the number of pulses is described, line sequential scanning, that is, a scanning method in which scanning lines are sequentially selected from the top is adopted, so that the movement of the viewpoint and The problem that the scanning line becomes visible when the movement of the scanning line coincides is not solved.
[0011]
As described above, the phenomenon in which attention is paid to the bright line is generated because the scanning line moves in accordance with the moving speed of the viewpoint of the observer. Usually, the scanning line emits light by scanning sequentially from one end of the screen, so that the scanning line moves at the lowest speed. For example, in a panel of 640 × 480 dots (480 scanning lines) with a frame frequency of 60 Hz and a frame frequency of 60 Hz, the moving speed of the scanning lines is only 10 m / s, which is a speed that can be easily followed by human eyes.
[0012]
An object of the present invention is to provide a passive-matrix display device using an organic light-emitting element, in order to solve the above-described problems, without visually increasing the frame frequency of a screen, and by performing high-luminance scanning. An object of the present invention is to improve display quality by making it difficult to visually recognize a line.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention proposes several techniques for preventing the eyes from following the movement of the scanning line without increasing the frame frequency constituting the screen. One of them is to move the scanning line at such a speed that the eyes cannot follow. A technique for that is to scan the scanning lines at several intervals instead of sequentially scanning the scanning lines, and the moving speed of the scanning lines is increased by the intervals, so that the line of sight follows. I want to.
[0014]
The next method is to move the scanning line not at a constant speed but at an accelerated, discrete, or random manner. It is easy to move the line of sight at a constant speed at a certain speed, but it is difficult to rapidly change the moving speed of the line of sight in view of the eyeball movement method. Therefore, by changing the moving speed of the scanning lines, the number of scanning lines imaged at the same position on the retina can be reduced to an extremely small number. Since the brightness perceived by the eyes can be considered to be proportional to the number of scanning lines to be imaged, the possibility of visually recognizing the scanning lines and the visibility of the scanning lines can be reduced by reducing this.
[0015]
Further, in addition to these methods, an effective measure is to combine with appropriately increasing the period (frame frequency) constituting one screen.
[0016]
That is, in order to achieve the above object, the present invention uses an organic light emitting element that emits light by passing a current through an organic thin film as a display element, and includes a plurality of data electrode rows and a plurality of scanning electrode rows. In a driving method of a passive matrix type display device in which images are displayed by cross-arranging and selecting scanning electrodes one after another and simultaneously applying a voltage corresponding to data on the selected scanning line to the data electrodes, the scanning electrodes are non-conductive. The selection is performed sequentially.
[0017]
Here, the non-sequential selection of the scanning electrodes may be characterized in that the scanning electrodes are sequentially selected with an interval of one or two electrodes.
[0018]
The non-sequential selection of the scanning electrodes may be characterized in that the interval between the currently selected scanning electrode and the next selected scanning electrode is three or more.
[0019]
Further, the non-sequential selection of the scanning electrodes may be performed so that the interval between the currently selected scanning electrode and the next selected scanning electrode is not constant.
[0020]
The non-sequential selection of the scanning electrodes may be changed according to the content of an image to be displayed.
[0021]
Further, the non-sequential selection of the scanning electrodes may be characterized by simultaneously selecting a plurality of scanning lines.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0023]
For simplicity of description, an embodiment in which the present invention is applied to an organic EL display panel having a number of pixels (16 × RGB) × 12 dots will be described below as a model.
[0024]
(Hardware configuration of each embodiment)
FIG. 1 shows a configuration of a passive matrix type organic light emitting device display in each embodiment described later of the present invention. This organic light emitting device display includes an organic EL simple matrix panel (hereinafter, referred to as an organic light emitting device panel) 101, a scan driver (scan drive circuit) 103, a data driver (data drive circuit) 105, and a control unit 107. . The scanning driver 103 drives a scanning line of the organic light emitting element panel 101. The data driver 105 drives the data lines of the organic light emitting device panel 101. The control unit 107 controls the scanning driver 103 and the data driver 105 according to a video signal supplied from an external device (not shown). Note that reference numeral 109 denotes an enlarged portion of a part of the organic light emitting element panel 101.
[0025]
FIG. 2 shows a configuration of an organic light emitting device panel constituting the organic light emitting device display of FIG. The organic light-emitting element panel 101 has, for example, 12 scanning lines 201 and 16 data lines 301 arranged in a lattice pattern, and one pixel is formed between each scanning line 201 and the data line 301. The organic EL elements to be connected are individually joined (see 109 in FIG. 1), and the scanning lines 201 are selected in a specific order described later according to the present invention, and data corresponding to the selected scanning line is transmitted to the data line. , The organic EL elements that are selectively energized are sequentially turned on.
[0026]
That is, the control unit 107 in FIG. 1 selects the twelve scan electrodes in FIG. 2 in a specific order described below according to the present invention, and the data electrode displays data corresponding to the selected scan electrode. The comparative example and the first to fourth embodiments described below are all implemented by changing the order in which the scanning electrodes are selected. The scanning of one frame is completed by scanning all the scanning electrodes, and the display shifts to the display of the next frame.
[0027]
(Comparative example)
As a comparative example of the present invention, FIG. 3 shows a case where scanning electrodes are sequentially scanned. FIG. 3 shows the potential of each scanning line in one frame. Since FIG. 3 is an example, the display is finished by scanning only one frame. However, normally, since an image is formed by successively displaying frames one after another, the display may be continuously performed. Of course. Here, the potential of each scanning line is represented by two potentials, a high potential (high level) and a low potential (low level), and is drawn vertically in the figure for convenience of drawing. Further, when the potential becomes low, it indicates that the scanning line at that location is selected. Pixels (pixels) connected to the scanning lines emit light according to the potentials applied to the data lines. Pixels leading to unselected (ie, higher potential) scan lines do not emit light.
[0028]
In the comparative example shown in FIG. 3, a line-sequential scanning, that is, a conventional scanning method in which the scanning lines are sequentially selected from the top is adopted. Therefore, the order of selecting the scanning lines is 1, 2, 3, 4, 5, and 5.・ 6 ・ 7 ・ 8 ・ 9 ・ 10 ・ 11 ・ 12 (number) Therefore, the moving distance of the scanning line per unit time is 1.1.1.1.1.1.1.1. In this case, since the adjacent scanning electrodes are selected and displayed one after another, the visibility of the bright line is most likely to occur as described in detail in the conventional example.
[0029]
(1st Embodiment)
First, a case where the scanning electrodes are scanned one by one is shown in FIG. 4 as a first embodiment of the present invention. FIG. 4 shows the potential of each scanning line in one frame. Although FIG. 4 is an example, the display is finished by scanning only one frame. However, since an image is usually formed by displaying frames one after another, display may be performed continuously. Of course.
[0030]
As shown in FIG. 4, the order of selecting the scanning lines in this embodiment is 1, 3, 5, 7, 9, 11, 2, 4, 6, 8, 10, 12 (number). Therefore, the moving distance of the scanning line per unit time is 2.2.2.2.2-2-9-2.2.2.2.2.2. In this case, the distance that the selected scanning line travels per unit time is twice as long as that of the above-described comparative example, and it has been confirmed by an experiment that the bright line becomes harder to recognize as compared with the panel of the comparative example. Was done.
[0031]
(Second embodiment)
Next, FIG. 5 shows a second embodiment of the present invention in which scanning is performed by scanning two scanning electrodes. FIG. 5 shows the potential of each scanning line in one frame. Although FIG. 5 is an example, the display is finished by scanning only one frame. However, since an image is usually formed by displaying frames one after another, display may be performed continuously. Of course.
[0032]
As shown in FIG. 5, the order of selecting the scanning lines in this embodiment is 1, 4, 7, 10, 2, 5, 8, 11, 3, 6, 9, 12 (number). Therefore, the moving distance of the scanning line per unit time is 3.3.3-3.-8.3.3.3.3.-8.3.33.3. In this case, the distance that the selected scanning line travels per unit time is three times as large as that of the above-described comparative example. confirmed.
[0033]
(Third embodiment)
Next, a case where scanning electrodes are scanned in a specific order (or random order) is shown in FIG. 6 as a third embodiment of the present invention. Although FIG. 6 is an example, the display is finished by scanning only one frame. However, normally, since an image is formed by successively displaying frames one after another, the display may be continuously performed. Of course.
[0034]
As shown in FIG. 6, the order in which the scanning lines are selected in the present embodiment is set to 1, 2, 4, 7, 11, 5, 10, 9, 6, 3, 12.8 (number). Therefore, in this case, the distances that the selected scanning lines move per unit time are 1, 2, 3, 4, -6, -5, -1, -3, -3, 6, and -4.
[0035]
In the present embodiment, it was also confirmed by an experiment that the bright line was hard to be visually recognized as compared with the panel of the comparative example because the movement of the selected position of the scanning line was large and not constant.
[0036]
(Other embodiments)
As described above, the embodiments of the present invention have been described in detail. However, the present invention is not limited to the case of the above-described embodiments. For example, in the non-sequential selection of the scanning electrode, the non-sequential contents are displayed. The present invention includes changing the scanning line according to the image content or selecting a plurality of scanning lines simultaneously and non-sequentially.
[0037]
【The invention's effect】
As described above, according to the present invention, in the organic light emitting element passive matrix display panel, the selection order of the scanning lines is performed in a non-sequential manner, so that it is difficult to visually recognize the high-luminance scanning lines. This has the effect that the display quality can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a passive matrix type organic light emitting device display in each embodiment described later of the present invention.
FIG. 2 is a schematic diagram showing a configuration of an organic light emitting device panel constituting the organic light emitting device display of FIG.
FIG. 3 is a timing chart showing a case where scanning electrodes are sequentially scanned as a comparative example of the present invention.
FIG. 4 is a timing chart showing, as a first embodiment of the present invention, a case where the scanning electrodes are scanned one by one.
FIG. 5 is a timing chart showing, as a second embodiment of the present invention, a case where scanning is performed by scanning two scanning electrodes.
FIG. 6 is a timing chart showing a case where scanning electrodes are scanned in a specific order (or a random order) as a third embodiment of the present invention.
[Explanation of symbols]
101 Organic EL simple matrix panel (organic light emitting device panel)
103 scan driver (scan drive circuit)
105 Data driver (data drive circuit)
107 Control unit 109 Enlarged part 201 Scan line 301 Data line

Claims (12)

An organic light-emitting element that emits light by passing a current through an organic thin film is used as a display element, and a plurality of data electrode rows and a plurality of scanning electrode rows are arranged so as to intersect with each other. In a driving method of a passive matrix display device for displaying an image by applying a voltage corresponding to data on a selected scanning line to an electrode,
A method of driving a display device, wherein the scanning electrodes are selected in a non-sequential manner. 2. The method according to claim 1, wherein the non-sequential selection of the scan electrodes is performed by sequentially selecting the scan electrodes with an interval of one or two electrodes. 3. The method according to claim 1, wherein in the non-sequential selection of the scan electrodes, an interval between a currently selected scan electrode and a next selected scan electrode is three or more. 2. The driving device according to claim 1, wherein the non-sequential selection of the scan electrodes is performed such that an interval between a currently selected scan electrode and a next selected scan electrode is not constant. 3. Method. The method according to claim 1, wherein the non-sequential selection of the scan electrode changes according to image content to be displayed. 6. The method according to claim 1, wherein the non-sequential selection of the scan electrodes selects a plurality of scan lines simultaneously. An organic light-emitting element that emits light by passing a current through an organic thin film is used as a display element, and a plurality of data electrode rows and a plurality of scanning electrode rows are arranged so as to intersect with each other. In a driving device of a passive matrix type display device for displaying an image by applying a voltage corresponding to data on a selected scanning line to an electrode,
A driving device for a display device, comprising a control unit for selecting the scanning electrodes in a non-sequential manner. 8. The display device driving device according to claim 7, wherein the control unit sequentially selects the scan electrodes at intervals of one or two electrodes in the non-sequential selection of the scan electrodes. 8. The display device according to claim 7, wherein in the non-sequential selection of the scanning electrodes by the control means, the interval between the currently selected scanning electrode and the next selected scanning electrode is three or more. Drive. 8. The non-sequential selection of the scan electrodes, wherein the control unit selects the scan electrodes so that an interval between a currently selected scan electrode and a next selected scan electrode is not constant. Display device driving device. 8. The driving device for a display device according to claim 7, wherein the non-sequential selection of the scanning electrodes by the control unit changes according to the content of an image to be displayed. 12. The display device driving device according to claim 7, wherein the control unit selects a plurality of scanning lines simultaneously in the non-sequential selection of the scanning electrodes.

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