JP2004348088A - Organic el display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL display which eliminates a possibility of burnout of a panel. <P>SOLUTION: The organic EL display is equipped with a plurality of pixel EL elements, a driving circuit and a voltage measuring circuit which measures respectively the driving voltages generated in the respective pixel EL elements by the driving currents respectively supplied from the driving circuit. The organic EL display is further equipped with an aging circuit for supplying the aging current for aging a non-deteriorated element to the non-deteriorated element in such a manner that the luminance of each of the plurality of the pixel EL elements is made nearly constant with each other when the pixel EL element having the driving voltage of each pixel EL element measured by the voltage measuring circuit among the plurality of the pixel EL elements in excess of the prescribed threshold is defined as the deteriorate element and the pixel EL element having the driving voltage below the prescribed threshold as the non-deteriorate element. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an organic EL display including a plurality of pixel EL elements arranged in a matrix such that each pixel constitutes a pixel.
[0002]
[Prior art]
As a display capable of high-quality display instead of a liquid crystal display, an organic EL display using an organic EL (electroluminescence) element has attracted attention.
[0003]
The organic EL element is a self-luminous display element, has a wide viewing angle, and is excellent in contrast and visibility. Further, since a backlight is not required, flattening and weight reduction are possible, and there are advantages such as low power consumption.
[0004]
Hereinafter, a conventional organic EL display will be described. A conventional organic EL display includes a plurality of pixel EL elements arranged in a matrix so as to form pixels, a scanning line driving circuit for driving the pixel EL elements along a horizontal direction, and a pixel EL element. And a driving circuit for driving the scanning line driving circuit and the signal line driving circuit according to an image signal.
[0005]
In the organic EL display configured as described above, when an image signal is input to the driving circuit, the driving circuit drives the scanning line driving circuit and the signal line driving circuit according to the input image signal. Then, the scanning line driving circuit and the signal line driving circuit drive the plurality of pixel EL elements so that an image represented by the image signal input to the driving circuit is displayed.
[0006]
[Patent Document 1]
JP-A-8-297304
[Problems to be solved by the invention]
However, in the above-described configuration of the conventional organic EL display, since the lifetime of the pixel EL element is short, there is a problem that if the image of the fixed pattern is continuously displayed for a long time, the panel may be burned.
[0008]
An object of the present invention is to provide an organic EL display in which a panel is not likely to burn.
[0009]
[Means for Solving the Problems]
The organic EL display according to the present invention includes: a plurality of pixel EL elements arranged in a matrix so as to form pixels; and a driving current for displaying an image by the plurality of pixel EL elements. An organic EL display, comprising: a driving circuit that supplies each of the EL elements; and a voltage measurement circuit that measures a driving voltage generated in each of the pixel EL elements by the driving current supplied from the driving circuit. Among the pixel EL elements, the drive voltage of each pixel EL element measured by the voltage measurement circuit is a deteriorated element when the drive voltage of the pixel EL element exceeds a predetermined threshold, and the drive voltage is equal to or less than the predetermined threshold. In the case where the pixel EL element is a non-deteriorating element, the luminance of each of the plurality of pixel EL elements Characterized in that the aging current for aging the non-degraded element so that the constant further comprising an aging circuit for supplying to the non-degraded element.
[0010]
A foldable mobile phone according to the present invention includes the image display unit on which the organic EL display according to the present invention is mounted, the image display unit on which the plurality of pixel EL elements are arranged, and a main unit having a key input unit. The unit is a foldable mobile phone that is configured to be rotatable with respect to the main unit so that the unit can be folded and stored in the main unit, and the aging current is supplied from the aging circuit during the storage. The non-deteriorating element is supplied to the non-deteriorating element, and the non-deteriorating element is aged.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
In the organic EL display according to the present embodiment, there is provided an aging circuit for supplying an aging current for aging the non-deteriorating element to the non-deteriorating element such that the brightness of each of the plurality of pixel EL elements is substantially constant. Have been. Therefore, the non-deteriorating element is aged so that the luminance of each of the plurality of pixel EL elements is substantially constant. Therefore, the luminance of each of the plurality of pixel EL elements can be made substantially constant. As a result, burn-in of the panel of the organic EL display can be prevented.
[0012]
In this embodiment, it is preferable that the voltage measuring circuit is constituted by a low-temperature polysilicon TFT.
[0013]
The organic EL display, when mounted on an electronic device having a chargeable internal power supply, supplies the aging current from the aging circuit to the non-deteriorating element at the time of charging the internal power supply or immediately after charging is completed, Preferably, the non-deteriorating element is aged.
[0014]
In the foldable mobile phone according to the present embodiment, the aging current is supplied from the aging circuit to the non-deteriorating element, and the non-deteriorating element is aged, while the image display unit is folded and stored in the main body. Therefore, the non-deteriorating element is aged so that the luminance of each of the plurality of pixel EL elements is substantially constant. Therefore, the luminance of each of the plurality of pixel EL elements can be made substantially constant. As a result, burn-in of the panel of the organic EL display can be prevented.
[0015]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 is a block diagram showing a configuration of the organic EL display according to the embodiment. The organic EL display 100 includes a plurality of pixel EL elements 4 arranged in a matrix so that each pixel constitutes a pixel.
[0017]
The organic EL display 100 includes a scanning line driving circuit 22 for driving the pixel EL elements 4 along the horizontal direction, a signal line driving circuit 21 for driving the pixel EL elements 4 along the vertical direction, and an image. It is provided for driving the scanning line driving circuit 22 and the signal line driving circuit 21 so as to supply a driving current for displaying an image by the plurality of pixel EL elements in accordance with a signal to the plurality of pixel EL elements 4, respectively. Drive circuit 3 is provided.
[0018]
The organic EL display 100 includes the voltage measurement circuit 2. The voltage measuring circuit 2 is configured by a low-temperature polysilicon TFT, and measures a driving voltage generated in each pixel EL element 4 by a driving current supplied to each pixel EL element 4.
[0019]
The organic EL display 100 is provided with an aging circuit 1. The aging circuit 1 uses the pixel EL element 4 whose driving voltage measured by the voltage measuring circuit 2 exceeds a predetermined threshold value among the plurality of pixel EL elements 4 as a degraded element. Is the predetermined threshold value or less, and the aging current for aging the non-deteriorating element such that the luminance of each of the plurality of pixel EL elements 4 is substantially constant when the pixel EL element 4 is the non-deteriorating element. Is supplied to the non-degraded element.
[0020]
FIG. 2 is a graph showing a temporal change in luminance and voltage of the pixel EL element 4 provided in the organic EL display 100 according to the embodiment. When the driving current is supplied to the pixel EL element 4, the voltage generated in the pixel EL element 4 to which the driving current is supplied increases linearly with the passage of time, and the luminance of the pixel EL element 4 to which the driving current is supplied. Degrades linearly over time.
[0021]
The operation of the organic EL display 100 according to the embodiment configured as described above will be described.
[0022]
When an image signal is input to the driving circuit 3, the driving circuit 3 supplies a driving current for displaying an image corresponding to the input image signal to each of the pixel EL elements 4. 22 and the signal line drive circuit 21 are driven. Then, a drive current is supplied to each pixel EL element 4.
[0023]
Next, the voltage measuring circuit 2 measures a drive voltage generated in each pixel EL element 4 by a drive current supplied to each pixel EL element 4. Thereafter, the aging circuit 1 regards the pixel EL element 4 in which the drive voltage of each pixel EL element 4 measured by the voltage measurement circuit 2 exceeds a predetermined threshold among the plurality of pixel EL elements 4 as a deteriorated element, In a case where the pixel EL element 4 whose driving voltage is equal to or lower than a predetermined threshold value is a non-deteriorating element, the aging of the non-deteriorating element is performed so that the luminance of each of the plurality of pixel EL elements 4 becomes substantially constant. An aging current is supplied to the non-degraded element.
[0024]
FIG. 3 is a graph showing the relationship between the voltage and the current of the pixel EL element 4 provided in the organic EL display 100 according to the embodiment. The vertical axis indicates the current supplied to the pixel EL element 4, and the horizontal axis indicates the voltage generated in the pixel EL element 4. Line 11 shows the relationship between voltage and current in the non-degraded element, and line 12 shows the relationship between voltage and current in the degraded element.
[0025]
When the aging circuit 1 ages a non-deteriorating element having the characteristic indicated by the line 11, the non-deteriorating element having the characteristic indicated by the line 11 changes to a degraded element having the characteristic indicated by the line 12 as a result of aging. . Therefore, all the pixel EL elements 4 are non-deteriorating elements having the characteristics indicated by the line 11. Therefore, the brightness of each of the plurality of pixel EL elements 4 becomes substantially constant. As a result, burn-in of the panel can be eliminated.
[0026]
When the organic EL display 100 is mounted on an electronic device having a chargeable internal power supply, the aging circuit 1 supplies an aging current from the aging circuit 1 to the non-deteriorating element when the internal power supply is charged or immediately after the charging is completed. Aging is preferred.
[0027]
As described above, according to the present embodiment, the aging circuit 1 that supplies the aging current for aging the non-deteriorating element to the non-deteriorating element so that the luminance of each of the plurality of pixel EL elements 4 becomes substantially constant to each other. Is provided. For this reason, the non-deteriorating elements are aged so that the luminance of each of the plurality of pixel EL elements 4 becomes substantially constant. Therefore, the luminance of each of the plurality of pixel EL elements 4 can be made substantially constant. As a result, burn-in of the panel of the organic EL display can be prevented.
[0028]
FIG. 4 is a graph showing the appearance of the foldable mobile phone 150 according to the embodiment. The foldable mobile phone 150 includes the image display unit 6 on which the organic EL display 100 is mounted and in which a plurality of pixel EL elements are arranged, and a main unit 7 having a key input unit 8.
[0029]
The image display unit 6 is configured to be rotatable with respect to the main body 6 so that the image display unit 6 can be folded and stored in the main body 7. When the image display unit 6 is folded and stored in the main unit 7, an aging current is supplied from the aging circuit to the non-deteriorating element, and the non-deteriorating element is aged.
[0030]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an organic EL display in which a panel is not likely to burn.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of an organic EL display according to an embodiment. FIG. 2 is a graph illustrating temporal changes in luminance and voltage of a pixel EL element provided in the organic EL display according to the embodiment. FIG. 3 is a graph showing a relationship between a voltage and a current of a pixel EL element provided in the organic EL display according to the embodiment. FIG. 4 is a graph showing an appearance of the foldable mobile phone according to the embodiment. Description】
DESCRIPTION OF SYMBOLS 1 Aging circuit 2 Voltage measurement circuit 3 Drive circuit 4 Pixel EL element 6 Image display part 7 Main body 8 Key input part 100 Organic EL display 150 Cellular phone

Claims (4)

A plurality of pixel EL elements arranged in a matrix such that each constitutes a pixel;
A drive circuit for supplying a drive current for displaying an image by the plurality of pixel EL elements to each of the plurality of pixel EL elements;
A voltage measuring circuit for measuring a driving voltage generated in each pixel EL element by the driving current supplied from the driving circuit, respectively,
Among the plurality of pixel EL elements, the pixel EL element whose drive voltage measured by the voltage measurement circuit exceeds a predetermined threshold value is a deteriorated element, and the drive voltage is the predetermined threshold value. In the case where the pixel EL element having a threshold value or less is a non-deteriorating element,
The organic EL device further comprising an aging circuit that supplies an aging current for aging the non-deteriorating element to the non-deteriorating element so that the luminance of each of the plurality of pixel EL elements becomes substantially constant. display. 2. The organic EL display according to claim 1, wherein the voltage measurement circuit is configured by a low-temperature polysilicon TFT. The organic EL display, when mounted on an electronic device having a chargeable internal power supply, supplies the aging current from the aging circuit to the non-deteriorating element at the time of charging the internal power supply or immediately after charging is completed, The organic EL display according to claim 1, wherein the non-deteriorating element is aged. An image display unit, comprising the organic EL display according to claim 1, wherein the plurality of pixel EL elements are arranged, and a main unit having a key input unit, wherein the image display unit is folded on the main unit. A foldable mobile phone configured to be rotatable with respect to the main body portion so that the mobile phone can be stored in the mobile phone,
A foldable mobile phone, wherein the aging circuit supplies the aging current from the aging circuit to the non-deteriorating element during the storage, and ages the non-deteriorating element.

Images