JP3757423B2 - Electroluminescence display device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an electroluminescence display device, and more particularly, an electroluminescence display that includes a plurality of electroluminescence elements that emit light of the same emission color, and detects the breakdown of the electroluminescence elements and automatically switches and drives other electroluminescence elements. Relates to the device.
[0002]
[Prior art]
Conventionally, as an electroluminescence (hereinafter also simply referred to as EL) display, there is an EL element multilayer structure type for the purpose of multicolor display (for example, see JP-A-1-315987). There are more structural types.
[0003]
[Problems to be solved by the invention]
However, when an EL display device with a single layer structure type is used for a speedometer of an automobile that requires high reliability for display, if any EL element that displays a segment or dot is destroyed, the display cannot be performed. Or the display quality deteriorates, and there is a problem that a sufficient function as a speedometer or the like cannot be exhibited.
[0004]
Therefore, the electroluminescence display device according to claim 1 is configured as a speedometer or the like by displaying the EL display with another EL element instead of the EL element having a multilayer structure of EL elements. An object of the present invention is to provide an EL display device capable of exhibiting sufficient functions. In addition, the electroluminescence display device according to claim 1 causes the breakdown to occur by driving the EL element having a multilayer structure first from the last EL element and then driving the front EL element sequentially for each breakdown. It is an object of the present invention to solve the problem that the destruction pattern of the EL element is displayed by the light emission of the rear EL element and to improve the display quality.
[0005]
The electroluminescence display device according to claim 2 is an electroluminescence display device according to claim 1, wherein a plurality of EL elements are configured in the same shape, thereby achieving homogenization of display before and after destruction. To do.
[0006]
According to a third aspect of the present invention, in the electroluminescent display device according to the first or second aspect, a breakdown detection circuit is configured to detect a breakdown by electrically detecting an operation change of the EL element. Thus, an object of the present invention is to easily detect destruction of an EL element with a simple configuration.
[0007]
The electroluminescence display device according to claim 4 is substantially the same as the electroluminescence display device according to any one of claim 1, claim 2, or claim 3, when the light emission luminance of each EL element is viewed from the light extraction side. The purpose is to further homogenize the display before and after destruction.
[0009]
An electroluminescence display device according to claim 5 is the electroluminescence display device according to any one of claims 1, 2, 3, and 4 , while simplifying the circuit configuration of the breakdown detection circuit. The purpose is to accurately detect destruction.
[0010]
[Means for Solving the Problems]
Under the above object, the electroluminescence display device according to claim 1 is characterized in that at least the rearmost electroluminescence element in which the electrode on the light extraction side is constituted by a transparent electrode and the pair of electrodes are both constituted by transparent electrodes, An electroluminescence display comprising at least one or more front electroluminescence elements that emit light of the same emission color as the electroluminescence elements, and a plurality of layers stacked in the front-rear direction, and a drive circuit that drives the electroluminescence elements And a breakdown detection circuit for detecting the breakdown of the electroluminescence element, and when receiving a breakdown detection signal from the breakdown detection circuit, electrically disconnects the broken electroluminescence element from the drive circuit, One of the electroluminescent elements of the A device switching circuit for electrically connecting between the dynamic circuit is constituted by the element switching circuit is first electrically by conduction between the rearmost electroluminescence element and the driving circuit, the When a breakdown detection signal indicating that the last electroluminescence element is broken is received from the breakdown detection circuit, next, electrical conduction is made between the electroluminescence element immediately before the last electroluminescence element and the drive circuit. After that, every time the destruction detection signal is received, the electroluminescence element immediately before the destroyed electroluminescence element is electrically connected to the drive circuit, and finally, the frontmost electroluminescence element And the drive circuit are electrically connected to each other.
[0011]
The electroluminescence display device according to claim 2 is the electroluminescence display device according to claim 1, wherein the plurality of electroluminescence elements are configured in the same shape.
[0012]
In addition, the electroluminescence display device according to claim 3 is the electroluminescence display device according to claim 1 or 2, wherein the breakdown detection circuit has a capacitance or current that changes according to an operation of the electroluminescence element. Based on the above, it is configured to detect the destruction of the electroluminescence element.
[0013]
An electroluminescence display device according to a fourth aspect is the electroluminescence display device according to any one of the first, second, and third aspects, wherein the light emission luminance of each of the plurality of electroluminescence elements is light extraction. It is characterized by being configured to be substantially the same when viewed from the side.
[0015]
An electroluminescence display device according to claim 5 is the electroluminescence display device according to any one of claims 1, 2, 3, or 4 , wherein the destructive detection circuit is the electroluminescence element. By having a Sawyer-Tower circuit in which a capacitor is inserted between the output terminal electrically connected to at least one of the upper and lower electrodes and the ground, and detecting a change in the charge of the capacitor by a comparator, It is configured to detect the breakdown of the electroluminescence element.
[0016]
[Effects of the invention]
According to the electroluminescence display device according to claim 1, since the EL display has an EL element multilayer structure, even if one EL element is destroyed, it is displayed by another EL element instead. It will be able to demonstrate sufficient functions. According to the electroluminescent display device of the first aspect, the multi-layer EL element is first driven from the last EL element, and then the forward EL element is sequentially driven each time it is destroyed, thereby It is possible to eliminate a problem that the generated EL element destruction pattern is visually recognized by light emission from the rear EL element, and to improve display quality.
[0017]
Further, according to the electroluminescence display device according to claim 2, in the electroluminescence display device according to claim 1, since the plurality of EL elements are configured in the same shape, the display of each EL element becomes uniform, and before and after the breakdown. The display can be homogenized.
[0018]
Further, according to the electroluminescence display device according to claim 3, in the electroluminescence display device according to claim 1 or 2, the breakdown detection circuit is provided to detect the breakdown by electrically detecting the operation change of the EL element. Since it comprised, destruction of an EL element can be easily detected with a simple structure.
[0019]
According to the electroluminescence display device according to claim 4, in the electroluminescence display device according to claim 1, claim 2, or claim 3, the light emission luminance of each EL element is substantially viewed from the light extraction side. Since they are the same, the luminance of the light emission is made uniform in addition to the homogenization of the display by making the EL elements have the same shape, and the display before and after the destruction can be made more uniform.
[0021]
According to the electroluminescence display device of the fifth aspect , the circuit configuration of the destruction detection circuit is simple, and the destruction detection can be performed accurately.
[0022]
【Example】
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 shows a configuration of an electroluminescence display device according to an embodiment.
[0024]
The electroluminescence display device of this embodiment is composed of an EL display 1 having a multilayer structure (in the case of illustration, a two-layer structure), a known drive circuit 2, a breakdown detection circuit 3, and an element switching circuit 4.
[0025]
The EL display 1 includes an insulating substrate (for example, a glass substrate) 11, a rearmost thin film EL element 12 formed on the upper surface (front surface) of the insulating substrate 11, a transparent insulating substrate 13 (for example, a glass substrate), The front thin film EL element (in the illustrated case, the front thin film EL element) 14 formed on the upper surface (rear surface) of the transparent insulating substrate 13 and disposed opposite to the rearmost thin film EL element 12 is insulated. A sealing frame 15 made of resin disposed in close contact between the outer peripheral portion of the front surface of the conductive substrate 11 and the outer peripheral portion of the rear surface of the transparent insulating substrate 13, and a spacer previously mixed in the sealing frame 15 (For example, glass beads) 16 and a transparent insulating oil (for example, silicon oil) 17 enclosed by the sealing frame 15 in a room formed by the sealing frame 15.
[0026]
In the last thin film EL element 12, at least the light extraction side electrode is formed of a transparent electrode. On the other hand, in the foremost thin-film EL element 14, the pair of electrodes are both formed of transparent electrodes. As will be described later, the last thin film EL element 12 and the front thin film EL element 14 are selectively driven by the element switching circuit 4 and do not emit light simultaneously. The last thin film EL element 12 and the front thin film EL element 14 are formed using the same light emitting layer material, and are configured to have the same emission color. The last thin film EL element 12 and the front thin film EL element 14 are formed in the same shape. In addition, the thin film EL elements 12 and 14 are adjusted, for example, in the thickness of each light emitting layer so that the light emission luminance when viewed from the light extraction side is substantially the same, or the thickness of each light emitting layer is the same. In this case, the voltage applied to the thin film EL elements 12 and 14 by the drive circuit 2 is adjusted.
[0027]
The breakdown detection circuit 3 is, for example, between the output terminal electrically connected to the upper electrode of each thin film EL element 12 or 14 in the drive circuit 2 or the output terminal electrically connected to the lower electrode and the ground. , Having a Sawyer-Tower circuit with a sense capacitor inserted, and configured to detect the breakdown of each thin film EL element 12, 14 by detecting a sudden change in the charge of the sense capacitor by a comparator (comparator). ing.
[0028]
That is, the destruction detection circuit 3 is configured as shown in FIG. In FIG. 2, 41 is a capacitor as a sense capacitor, 42 is an amplifier, 43 is a comparator, 44 is an EL power source, and 45 is a signal output unit to the element switching circuit.
[0029]
As another example of the breakdown detection circuit 3, a terminal voltage between an output terminal electrically connected to the upper electrode of each EL element 12, 14 and an output terminal electrically connected to the lower electrode is used. It is also possible to detect a change in the electric charge of the capacitor and detect the breakdown of each of the EL elements 12 and 14. Further, as another example of the breakdown detection circuit 3, the breakdown may be detected by detecting a change in the current flowing through the thin film EL elements 12 and 14 or the like. As the breakdown detection circuit 3, the circuit shown in FIG. 2 has a simple circuit configuration, and the breakdown detection is accurate.
[0030]
The element switching circuit 4 electrically connects or disconnects between the drive circuit 2 and the thin film EL elements 12 and 14 and is constituted by an analog switch or the like that performs a switch operation in response to a breakdown detection signal from the breakdown detection circuit 3. Has been. That is, the element switching circuit 4 includes a transistor 46 and a relay 47 as shown in FIG. Specifically, the element switching circuit 4 first electrically connects the last thin film EL element 12 and the drive circuit 2, and indicates that the last thin film EL element 12 is destroyed from the destruction detection circuit 3. When the destruction detection signal is received, the front thin film EL element 14 and the drive circuit 2 are electrically connected. In the case of an EL display having three or more thin-film EL elements, the element switching circuit 4 first electrically connects the last thin-film EL element 12 and the drive circuit 2 to form a breakdown detection circuit. 3 receives a breakdown detection signal indicating that the last thin film EL element 12 has been broken, and then electrically connects the front thin film EL element immediately before the last thin film EL element 12 and the drive circuit 2. After that, every time the destruction detection signal is received, the thin film EL element immediately before the destroyed thin film EL element is electrically connected to the drive circuit 2, and finally, the foremost thin film EL element 14. And the drive circuit 2 are electrically connected.
[0031]
Next, the operation of the EL display device having the above configuration will be described.
[0032]
First, the element switching circuit 4 electrically connects the drive circuit 2 and the rearmost thin film EL element 12 while electrically disconnecting the drive circuit 2 and the frontmost thin film EL element 14. Yes. Therefore, the EL display 1 performs a predetermined display when the last thin film EL element 12 is driven by the drive circuit 2. At this time, the foremost thin film EL element 14 transmits the display by the last thin film EL element 12.
[0033]
When the last thin film EL element 12 is driven and the last thin film EL element 12 is destroyed, the destruction detection circuit 3 detects the destruction and outputs a destruction detection signal to the element switching circuit 4. Upon receiving this breakdown detection signal, the element switching circuit 4 electrically disconnects the drive circuit 2 and the last thin film EL element 12 and electrically connects the drive circuit 2 and the front thin film EL element 14. Conduct. Therefore, the EL display 1 now performs a predetermined display when the foremost thin film EL element 14 is driven by the drive circuit 2. At this time, the foremost thin-film EL element 14 performs display with the same emission color as that of the rearmost thin-film EL element 12 and substantially the same emission luminance. Further, the destruction pattern generated by the destruction of the last thin film EL element 12 is not visually recognized because the last thin film EL element 12 is located behind the foremost thin film EL element 14.
[0034]
As described above, according to the EL display device according to the present embodiment, the EL display 1 has a thin film EL element multilayer structure, and even if one thin film EL element 12 is destroyed, another thin film EL element 14 is used instead. Since it is made to display, it becomes possible to exhibit a sufficient function as a speedometer or the like.
[0035]
In addition, according to the EL display device according to the present embodiment, since the plurality of thin film EL elements 12 and 14 are configured in the same shape, the display of each thin film EL element 12 and 14 becomes uniform, and the display before and after the breakdown is homogenized. It becomes possible to plan.
[0036]
Further, according to the EL display device according to the present embodiment, since the breakdown detection circuit 3 is configured to detect the breakdown by electrically detecting the operation change of the thin film EL element 12, the breakdown of the thin film EL element 12 can be easily configured. It can be easily detected.
[0037]
Further, according to the EL display device according to the present embodiment, the light emission luminances of the thin film EL elements 12 and 14 are made substantially the same when viewed from the light extraction side. Homogenization of the light emission luminance is added to the homogenization of the display by the same shape, so that the display before and after the destruction can be made more uniform.
[0038]
Further, according to the EL display device according to the present embodiment, since the last thin film EL element 12 was first driven, the destruction pattern generated by the destruction of the last thin film EL element 12 is visually recognized by the light emission of the front thin film EL element 14. The display quality can be improved.
[0039]
Further, in the EL display device according to the present embodiment, when a plurality of EL elements that display segments or dots are configured on the same insulating substrate, a drive circuit, a breakdown detection circuit, and an element switching for each EL element. A circuit may be installed. In that case, it is only necessary to electrically connect only the EL element immediately before the segment or dot where the breakdown has occurred to the drive circuit.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an EL display device according to an embodiment. FIG. 2 is an electrical connection diagram illustrating an example of a breakdown detection circuit. FIG. 3 is an electrical connection diagram illustrating an example of an element switching circuit.
1 EL display 12 Last part thin film EL element (last part EL element)
14 Frontmost thin-film EL element (front EL element)
2 Drive circuit 3 Destruction detection circuit 4 Element switching circuit

Claims (5)

At least one or more of the last electroluminescent element in which the electrode on the light extraction side is formed of a transparent electrode and at least one of the pair of electrodes are formed of a transparent electrode and emits light in the same emission color as the last electroluminescent element. An electroluminescence display configured by stacking a plurality of front electroluminescence elements in the front-rear direction; and
A drive circuit for driving the electroluminescence element;
A destructive detection circuit for detecting destructiveness of the electroluminescence element;
When a breakdown detection signal is received from the breakdown detection circuit, the broken electroluminescence element is electrically disconnected from the drive circuit, and one of the other electroluminescence elements is electrically connected to the drive circuit. An element switching circuit that conducts to
Consisting of
The element switching circuit is
First, when the last electroluminescence element and the drive circuit are electrically connected to each other, and a breakdown detection signal indicating that the last electroluminescence element is broken is received from the breakdown detection circuit, The electroluminescence element immediately before the last electroluminescence element is electrically connected to the drive circuit, and each time the breakdown detection signal is received, the electroluminescence element immediately before the destroyed electroluminescence element An electroluminescence display device configured to electrically connect between the driving circuit and, finally, to electrically connect between the electroluminescent element in the forefront and the driving circuit. . The electroluminescence display device according to claim 1, wherein the plurality of electroluminescence elements are configured in the same shape. The said destruction detection circuit is comprised so that destruction of an electroluminescent element may be detected based on the electrostatic capacitance or electric current which changes according to operation | movement of the said electroluminescent element. The Claim 1 or Claim 2 characterized by the above-mentioned. The electroluminescence display device described. The light emission luminance of each of the plurality of electroluminescence elements is configured to be substantially the same when viewed from the light extraction side. The claim 1, claim 2, or claim 3 Electroluminescence display device. The destruction detection circuit is
A Sawyer-Tower circuit having a capacitor inserted between an output terminal electrically connected to at least one of the upper and lower electrodes of the electroluminescence element and a ground, and a change in the charge of the capacitor by a comparator. by detecting, claim 1, characterized in that configured to detect breakdown of the electroluminescent device, an electroluminescent display device according to claim 2, claim 3 or claim 4.

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