JP4207593B2 - Organic thin film light emitting display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to defect repair of a display using an organic light emitting element, and more particularly to repair of a short-circuited pixel and suppression of bright lines of a display using a passive matrix organic thin film light emitting element.
[0002]
[Prior art]
Organic light-emitting elements are self-luminous elements, and thus have high visibility and can be driven at a low voltage. As an organic light emitting device, a transparent conductive film of an anode on a transparent substrate, a hole transport layer and a light emitting layer made of an organic substance, and an organic layer in which a metal film of a cathode is formed, or an organic layer is a hole A structure composed of three layers of a transport layer, a light emitting layer, and an electron transport layer is known.
[0003]
The light emission mechanism of the organic light emitting device is considered as follows. Electrons injected from the cathode and holes injected from the anode generate excitons with the fluorescent dye molecules in the light-emitting layer, and electroluminescence is emitted in the process of excitons recombining with radiation. The electroluminescence is emitted to the outside through the transparent conductive film as the anode and the transparent substrate.
[0004]
As a display using an organic light emitting element, there is a passive matrix type (simple matrix type) display as shown in FIG. The passive matrix organic light-emitting display includes an anode row made up of a plurality of anodes 3 disposed above the transparent substrate 1, a cathode row made up of a plurality of cathodes 4 intersecting the anode row substantially perpendicularly, and these It is comprised from the organic layer containing the organic light emitting layer supported by. A plurality of pixels 2 are formed in a matrix in the intersection region of the anode column and the cathode column, and a display portion is formed by these pixels.
[0005]
A display device is configured by connecting the external drive circuit and the display unit via a connection unit formed by extending the anode 3 and the cathode 4 from the display unit to the periphery of the substrate.
[0006]
In recent years, research has been conducted on high-definition passive matrix color displays that take advantage of the light-emitting response speed of organic light-emitting elements to realize high-quality displays at low cost for information equipment applications such as full-color display and video display. Expectations are increasing.
[0007]
In an actual passive matrix organic light emitting display, an electrical short circuit may occur between both electrodes in a pixel due to structural defects in the process. In this case, the pixel resistance is almost lost, and a large current (hereinafter referred to as a short-circuit current) determined by the internal impedance of the drive circuit and the wiring resistance flows through the electric path passing through the defective pixel.
[0008]
The short-circuit current not only increases the power consumption, but also alters the thermally weak organic thin film layer, causing an increase in the electrode short-circuit area in the short-circuited pixel. Furthermore, it propagates to neighboring pixels and induces a new electrically shorted pixel.
[0009]
A short-circuited pixel in which an electrical short circuit exists does not light up because an inter-electrode potential necessary for light emission cannot be obtained, resulting in a display defect that appears as a black dot on the display portion. In addition, the short-circuited pixels cause various image quality defects when displaying an image, for example, bright lines are generated in which data lines including the short-circuited pixels continue to be lit in a bright line shape.
[0010]
By the way, the organic layer used in the passive matrix organic light emitting display has a very thin film thickness of about several hundred nm or less, and it is industrially difficult to eliminate short circuit defects such as dust adhesion. Methods have been devised to repair shorted pixels.
[0011]
For example, there is a method of repairing the short circuit part by applying a reverse voltage exceeding the light emission voltage (hereinafter referred to as a repair voltage) to the short circuit pixel and fusing the short circuit part.
[0012]
[Problems to be solved by the invention]
The present invention minimizes the generation of bright lines even when an electrical short circuit occurs, while preventing the generation of bright lines due to an electrical short circuit between both electrodes, and does not significantly reduce display quality. It is an object of the present invention to provide a method capable of performing a repair operation for a short-circuit location.
[0013]
[Means for Solving the Problems]
In the present invention in order to achieve the above object, the intersections of a plurality of cathodes arranged in parallel to substantially perpendicular to the plurality of anodes and plurality of anodes arranged in parallel to the transparent substrate an organic light-emitting layer obtained by forming a plurality of pixels in matrix a pinched organic light-emitting layer, and a data driver connected to the plurality of anodes, a plurality of scan drivers connected to the cathode An organic thin film light emitting display comprising a scan driver to which a scan signal for scanning the plurality of cathodes is supplied , and a control signal corresponding to the scan signal, the scan driver passing through the plurality of cathodes comprises a recovery control means for generating a control signal for causing I line repair and / or emission lines of suppression of the short-circuit pixel in a plurality of pixels, the scan driver, a plurality of cathodes the scanning signal is supplied Scanning means for checking and limiting a short-circuit current flowing through the short-circuited pixels by supplying a constant current to the plurality of cathodes during an image display period of the scanning signal in accordance with the control signal from the recovery control means And a repairing means for repairing the short-circuited pixels by applying a constant positive voltage according to the control signal during an image non-display period of the scanning signal .
[0014]
Here, the limiting means comprises a current source having a source side coupled to the constant positive voltage and a sink side coupled to the plurality of cathodes, and the current source is in the image display period according to the control signal. Controlled by the recovery control means to turn on and off during the image non-display period, the repair means being a transistor coupled in parallel to the current source and coupled to the recovery control means The switch means is turned off during the image display period in response to the control signal, and is turned on during the non-image display period so as to apply the constant positive voltage to the plurality of cathodes. It is preferable to be controlled by the recovery control means .
[0015]
Here, when the switch means is on, all the operations of each terminal of the scan driver are the source operation (power supply operation), and all the operations of each terminal of the data driver are the sink operation (ground potential). Is preferred.
[0016]
Here, when the switch means is on, the constant positive voltage is preferably the same voltage as the image display period or a voltage higher than the image display period.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
(One embodiment)
Figure 2 shows a configuration example of a driving circuit of an embodiment of a passive matrix organic thin film light emitting display according to the present invention.
[0018]
A data drive circuit 6 is connected to each anode (data line) 3, and a scanning drive circuit 5 is connected to each cathode (address line) 4. The output circuit portion of the scanning side drive circuit 5 can supply the power supply voltage (+ V) from the power source directly to each cathode 4 by setting the source side to the constant current circuit 52 and bypassing the constant current circuit 52 by the bypass circuit 51. To do. The bypass circuit 51 is composed of a transistor switch. By switching the on-off timing of the switch arbitrarily by a signal from the timing circuit 7, it is possible to switch the emission line of suppressing operation by repair operation and the short-circuit pixel of the short pixel occurring in passive matrix organic thin film light-emitting display 20.
[0019]
FIG. 3 is a timing chart showing the operation timing of the scanning side drive circuit 5 in this embodiment, and FIG. 4 is a timing chart showing the operation timing of the data side drive circuit 6 in this embodiment.
[0020]
3 and FIG. 4, t ₁ is the image non-display period, t ₂ is the image display period.
[0021]
Image display period t ₂ is operated is constant current circuit 52 by a control signal from the timing circuit 7, the bypass circuit 51 the base of the transistor switch is a high level is open. Each cathode 4 is scanned by the transistors 53 ₁ to 53 _n in accordance with the scanning signals shown in (1) to (n) of FIG. 3, and emits light according to the image data shown in (1) to (n) of FIG. .
[0022]
If there is a short pixels, while the scanning of the scanning image display period t _2, the reverse current to short-circuit the pixel of passive matrix organic thin film light-emitting display 20 from the power supply of the scanning side drive circuit 5 flows, normally therefrom pixels Is emitted in the forward direction to emit light by being energized to the ground of the scanning side drive circuit 5 to become a bright line.
[0023]
However, according to constant current constant current circuit 52 to the image display period t ₂ is operated to the present embodiment configured to provide from each cathode 4, a short-circuit pixel when an electrical short occurs nonradiative The reverse current flowing through the shorted pixel can be limited by a constant current from the constant current circuit 52, and even if there is a shorted pixel, the data line including the shorted pixel becomes a bright line shape. It is possible to suppress the emission of the bright line that is lit up inconspicuously.
[0024]
On the other hand, the image non-display period t ₁ of each frame, the operation of the constant current circuit 52 is stopped by the control signal from the timing circuit 7, the bypass circuit 51 the base of the transistor switch is set to the low level is closed. Therefore, the power supply voltage from the power supply (+ V) can be directly applied to each cathode 4.
[0025]
At this time, the operation of all the terminals of the scanning side drive circuit 5 is the source operation (power supply operation), and the operation of all the terminals of the data side drive circuit 6 is the sink operation (ground potential).
[0026]
Thus, from the power of the scanning side drive circuit 5 without passing through the constant current circuit 52, to be energized to the ground of the data-side driving circuit 6 via the short pixel of passive matrix organic thin film light-emitting display 20, short-circuit pixel In this case, a reverse voltage between the power source of the scanning side drive circuit 5 and the ground is applied, and if the power source of the scanning side drive circuit 5 is set to a voltage value that can restore the short-circuited portion, the repair effect on the short-circuited portion is achieved. Is obtained.
[0027]
Incidentally, the emission line, while the scanning of the scan in the image display period t _2, current from a power source of the scanning side drive circuit 5 to the ground the street scanning side driving circuit 5 normal pixels via the short pixel It is for being bright line is not generated in the image non-display period t _1.
[0028]
(Modification)
FIG. 5 is an example of a timing chart showing another operation timing of the scanning side drive circuit 5.
In this modification, the power supply of the scanning side drive circuit 5 is set to a higher voltage (= v ₂ ) than normal (= v ₁ ) in the image non-display period t ₁ for each frame, thereby restoring the short-circuited portion. Is made even higher.
[0029]
【The invention's effect】
According to the present invention, in contrast to the generation of bright lines due to an electrical short between the anode and the cathode during the image display period, the generation of bright lines can be minimized even when an electrical short occurs, and the display quality can be significantly reduced. It is possible to avoid it. In addition, during the image non-display period, a repairing operation for a short-circuited portion that is the cause of the bright line is performed, and a fundamental countermeasure for the bright line is possible.
[Brief description of the drawings]
1 is a plan view showing a passive matrix organic thin-film light emitting display electrode structure capable of applying the present invention.
2 is a block diagram showing a configuration example of a driving circuit of an embodiment of a passive matrix organic thin film light emitting display according to the present invention.
FIG. 3 is a timing chart showing operation timing of the scanning side drive circuit in the embodiment of FIG. 2;
4 is a timing chart showing the operation timing of the data side driving circuit in the embodiment of FIG. 2;
5 is a timing chart showing the operation timing of the scanning side drive circuit according to a modification of the passive matrix organic thin film light emitting display according to the present invention.
[Explanation of symbols]
1 Transparent substrate 2 Pixel 3 Anode (data line)
4 Cathode (address line)
5 the scanning side drive circuit 6 data side drive circuit 7 a timing circuit 20 passive matrix organic thin film light-emitting display 51 constant current circuit 52 bypass circuit 53 ₁ to 53 _n transistor

Claims (4)

An organic light-emitting layer which is sandwiched at intersections of a plurality of cathodes arranged in parallel to substantially perpendicular to the plurality of anodes and plurality of anodes arranged in parallel to the transparent substrate in a matrix An organic light emitting layer formed with a plurality of pixels;
A data driver connected to the plurality of anodes ;
An organic thin-film light emitting display comprising: a scanning driver connected to the plurality of cathodes, and a scanning driver supplied with a scanning signal for scanning the plurality of cathodes ;
Recovery control for generating a control signal for causing I line repair and / or emission lines of suppression of the short-circuit pixel in the scanning signal of the plurality of pixels through the plurality of cathodes and a control signal by the scanning driver in accordance with the With means,
The scan driver
Scanning means for scanning the plurality of cathodes to which the scanning signal is supplied;
Limiting means for limiting a short-circuit current flowing through the short-circuited pixels by supplying a constant current to the plurality of cathodes during an image display period of the scanning signal according to the control signal from the recovery control means; ,
Repairing means for repairing the short-circuited pixels by applying a constant positive voltage according to the control signal during an image non-display period of the scanning signal;
The organic thin film light-emitting display, characterized in that it comprises a. The organic thin film light emitting display according to claim 1.
The limiting means includes a current source having a source side coupled to the constant positive voltage and a sink side coupled to the plurality of cathodes, and the current source is turned on in the image display period in accordance with the control signal. , Controlled by the recovery control means to turn off during the image non-display period,
The restoration means includes a switch means having a control terminal coupled to the recovery control means, the transistor being connected in parallel to the current source, and the switch means is configured to display the image display period according to the control signal. The organic thin-film light emitting display is controlled by the recovery control means so as to apply the constant positive voltage to the plurality of cathodes by turning on the non-image display period. . The organic thin film light emitting display according to claim 2,
When the switch means is on, all the operations of each terminal of the scan driver are a source operation (power supply operation), and all the operations of each terminal of the data driver are a sink operation (ground potential). Organic thin film light emitting display. The organic thin film light emitting display according to claim 2 or 3,
An organic thin film light emitting display characterized in that, when the switch means is on, the constant positive voltage is set to the same voltage as the image display period or higher than the image display period.

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