JPH10321367A - Evaluating device and evaluating method of organic el display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL display evaluating device by which manufacturing time can be shortened and a yield can be improved by applying an inspection voltage generated by a voltage generating means of an organic EL display between two scanning electrodes or data electrodes, and judging the quality from a value of an electric current flowing between the voltage generating means and the organic EL display. SOLUTION: Data electrodes 24 and scanning electrodes 23 sandwich an organic layer between them, and are arranged in a plurality so as to cross each other, and form a matrix. When an electric current is flowed by applying a prescribed voltage between optional electrodes of X, Y coordinates imparted by the data electrodes 24 and the scanning electrodes 23, a specific organic layer emits the light, and constitutes a single picture element. An optional picture element is made to selectively emit the light, and an image is constituted. Inspection voltage of a voltage generating means 3 is particularly desirable to be 0.1 to 2.5 V. An electric current detecting means detects an electric current flowing to an organic EL element, and converts it into a signal, and sends it to a judging means 5, and feeds it back by a display, a voice or the like when it is not proper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to home appliances, automobiles, information display panels used for audio and the like, instrument panels for automobiles, displays for displaying moving images and still images, and the like.
The present invention relates to an evaluation method and an evaluation device for an organic EL display which is used for a motorcycle electric component and is configured using an organic compound.

[0002]

2. Description of the Related Art In recent years, organic EL devices have been actively studied,
It is being put to practical use. In this method, a hole transport material such as triphenyldiamine (TPD) is formed into a thin film on a transparent electrode (hole injection electrode) such as tin-doped indium oxide (ITO) by vapor deposition, and then an aluminum quinolinol complex (A
1q3) as a light emitting layer, and a metal electrode such as Mg having a small work function (electron injection electrode)
This element has a basic structure and has a very high luminance of several hundreds to several tens of thousands cd / m ² at a voltage of about 10 V, and thus has attracted attention as a display for home electric appliances, automobiles, motorcycle electric components and the like.

As a display using such an organic EL element, for example, an organic EL display having a configuration as shown in FIG. 4 is known. In the figure, an organic EL display 1 has a scanning (common line) electrode 23 in which an organic layer (light emitting layer or the like) (not shown) usually serves as a negative electrode, and a data (segment line) electrode 24 usually serving as an anode (transparent electrode). And are disposed between the transparent (glass) substrates 21 and 22. When a potential difference is applied between the scanning electrode 23 and the data electrode 24, an electric field is generated in the organic layer, and electrons accelerated by the electric field generate electron-hole pairs, or electrons at the emission center are excited, and the electrons and electrons are excited. It emits light when the hole pair disappears or when returning from the excited state to the steady state.

When such an organic EL display is manufactured, an organic layer is unevenly stacked in a manufacturing process, an organic layer is damaged when a functional thin film such as a negative electrode is stacked, or the organic layer is adversely affected. The electrodes themselves may be mixed with impurities or oxidized, which may cause defects such as so-called luminance unevenness and dot defects and variations in quality. Even after being supplied to the market as a non-defective product, the organic layer, the electrode, or their interface is deteriorated due to aging, and the luminance is reduced.

The organic EL element emits light when current flows from the anode to the cathode in the forward direction, and the current hardly flows in the reverse direction.
Although it has a so-called diode characteristic, in a simple matrix type, this diode characteristic is extremely important. That is, when there is a current (leakage current) in the reverse direction, display quality such as cross-stroke and uneven brightness is deteriorated, and energy consumption that does not contribute to light emission such as unnecessary heat generation of the element occurs. Decrease.

Conventionally, as a method of evaluating or inspecting an organic EL display, in a production line, after assembling peripheral parts such as a driving device to the organic EL display, the parts are actually driven, and luminance unevenness, dot defects, etc. are reduced. Each measurement was performed by a separate measuring device for each line and each measurement item using an image measuring device or the like. For this reason, due to errors in the device and individual differences among workers who use the device, the measurement standards may vary, and the measurement may take time, thereby increasing the measurement accuracy and improving the evaluation efficiency. Was an obstacle. In addition, if the number of measurement items increases, a new device for that is required. On the other hand, when trying to find luminance unevenness or the like with high accuracy, there is also a method of making a determination with human eyes, but this also tends to be affected by the proficiency and physical condition of the person in charge, and the determination results have been uneven.

Further, in order to evaluate or inspect an organic EL display, peripheral components and the like are assembled to near the final stage of the manufacturing process, and the components are evaluated by actually operating and emitting light. If evaluated, the assembled parts and the manufacturing time for them are wasted. Also, since the evaluation method is based on the emitted light,
It is difficult to determine which part of the organic EL display has a defect, and even if the organic EL display is evaluated on a production line, the occurrence of a defective product is prevented only by the evaluation result. It was difficult to give feedback for

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide high evaluation efficiency, objective evaluation, feedback of evaluation results to a manufacturing line, and reduction of evaluation time, ie, manufacturing time, and improvement of yield. It is an object of the present invention to provide an evaluation device and an evaluation method for an organic EL display capable of performing the following.

[0009]

As described above, the organic EL device
The device emits light when current flows from the anode to the cathode in the forward direction, and hardly flows in the reverse direction. In a simple matrix type, this diode characteristic is extremely important, and if there is a current in the reverse direction (leakage current), display quality such as cross stroke and uneven brightness is reduced. That is, as shown in FIG. 3, for example, there is a correlation between the leak current and the light emission luminance. Therefore, a leakage current corresponding to a certain critical luminance is obtained, and if a leakage current higher than that current is determined, it is determined to be defective, thereby easily and objectively detecting luminance unevenness and missing dots. be able to.

In this case, when a voltage that does not emit light is applied between any of the scanning electrodes or any of the data electrodes,
No current flows because one electrode side is in the forward direction and the other electrode side is in the reverse direction. However, if there is a defective portion on the electrode side in the opposite direction, a leak current flows, and it is found that there is a defective portion at the position of the electrode. It is sufficient to know that the defective part is located on the line of the electrode, but when specifying the position further, when the inspection is performed with the scanning electrode, the inspection is performed by changing to the data electrode, and vice versa. For example, the inspection may be performed again using the scanning electrode.

That is, the above object is achieved by the present invention described below. (1) Two or more data electrodes, two or more scan electrodes arranged in a direction intersecting with the data electrodes, and an organic EL layer existing between the two electrodes;
An organic EL layer, an organic EL display forming at least one circuit between the scanning electrodes, voltage generating means for generating a test voltage for the organic EL display, and a test voltage generated by the voltage generating means for the organic EL display. Connecting means for applying between at least two scanning electrodes or data electrodes of the display; current detecting means for detecting a current flowing between the voltage generating means and the organic EL display;
An evaluation device for an organic EL display, comprising: a judging unit for judging the quality of the organic EL display based on the current value detected by the current detecting unit. (2) The apparatus for evaluating an organic EL display according to the above (1), wherein the inspection voltage is lower than a light emission voltage of the organic EL display. (3) The apparatus for evaluating an organic EL display according to (1) or (2), wherein the inspection voltage is 0.1 to 2.5 V. (4) two or more data electrodes, two or more scan electrodes arranged in a direction intersecting the data electrodes, and an organic EL layer existing between the two electrodes;
Applying a test voltage lower than the light emission voltage of the organic EL display between at least two of the data electrodes or scan electrodes of the organic EL display forming at least one circuit between the organic EL layer and the scan electrodes, A method for evaluating an organic EL display, comprising detecting a current flowing between the electrodes based on a voltage, and evaluating the organic EL display from the detected current value.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The evaluation apparatus for an organic EL display of the present invention has two or more data electrodes, two or more scan electrodes arranged in a direction intersecting the data electrodes, and an electrode between the two electrodes. An organic EL display having at least one circuit formed between the data electrode, the organic EL layer, and the scan electrode; and a voltage generating means for generating a test voltage for the organic EL display. Connecting means for applying an inspection voltage generated by the voltage generating means between at least two scan electrodes or data electrodes of the organic EL display;
It has a current detecting means for detecting a current flowing between the L displays, and a judging means for judging pass / fail of the organic EL display based on a current value detected by the current detecting means.

The organic EL display 1 used in the present invention has two or more, ie, a plurality of scanning electrodes 23, and a plurality of data electrodes 24 in a direction crossing the scanning electrodes, as shown in FIGS. And a matrix type display having an organic layer such as a light emitting layer sandwiched between the two electrodes. The data electrode 24 normally functions as an electrode (anode) on the current injection side, and the scan electrode 23 functions as an electrode (cathode) on the normal current discharge side. A plurality of data electrodes 24 and scanning electrodes 23 are provided so as to intersect with each other with an organic layer interposed therebetween to form a matrix. Therefore, a predetermined voltage is applied between any electrodes of the X and Y coordinates given by the data electrode 24 and the scanning electrode 23,
When an electric current is passed, the organic layer sandwiched between the specific data electrode 24 and the scanning electrode 23 emits light, and constitutes one pixel (hereinafter, unless otherwise specified, one pixel in the display is used in this specification). Organic EL is used to constitute the pixel
Element). In this manner, an arbitrary image can be formed on a screen by selectively causing pixels at an arbitrary position to emit light. The method of displaying an image on an organic EL display is based on a conventionally known method of driving a dot matrix type display, and a detailed description thereof will be omitted.

The voltage generating means 3 generates a test voltage necessary for testing the organic EL display 1. The inspection voltage may be equal to or lower than a voltage that does not destroy the organic EL display. However, it is preferable that the evaluation can be performed when no light is emitted, and the safety voltage is higher. The voltage which is lower than the above voltage and which allows a current required for evaluating the organic EL display 1 to flow is preferable. The light emission voltage of the organic EL element varies depending on the organic substance and electrode material used, but is usually about 2.6 V. Accordingly, the inspection voltage is particularly preferably about 0.1 to 2.5 V, more preferably about 0.5 to 2.5 V, and further preferably about 0.8 to 1.5 V. As such a voltage generating means 3, any means capable of stably supplying a desired voltage may be used. For example, a constant voltage circuit using a semiconductor element such as a transistor or an FET,
It can be easily obtained by using a battery, a regulator IC or the like.

The connection means 2 connects the test voltage generated by the voltage generation means 3 to at least two of the organic EL displays.
The voltage is applied between two scan electrodes 23 or data electrodes 24.
That is, as shown in FIG. 1, for example, two arbitrary scanning electrodes 23 (data electrodes 24) of the organic EL element 1 are selected,
Voltage generating means is connected between the two scanning electrodes 23 (data electrodes 24) so that the inspection voltage is applied. The electrodes to be connected are the scanning electrodes 23 and the data electrodes 2.
4, and an arbitrary set of the same type is selected. This set of electrodes may be separated such that electrodes of the same type are present between them, or may be a selection of a plurality of electrodes on one side or both sides. Depending on the contents, they are connected so as to be sequentially energized between all the electrodes within the same type. Such connection means include, for example, contact switches such as switches and rotary switches, transistors and switching elements using semiconductors such as FETs, or integrated ones of these. It also includes a contact that contacts the contact, a probe used when connected by an operator, and the like. Among them, a switching element using a semiconductor can switch an electrode to be connected at high speed on the order of microseconds or less, which is preferable in terms of speeding up inspection.

The current detecting means 4 detects a current flowing between the electrodes of the organic EL display, that is, a current flowing through the organic EL element when the inspection voltage is applied. The detected current is converted into a predetermined signal and sent to the determination means 5. Organic EL
As described above, the element emits light when a current flows from the anode to the cathode in the forward direction, and has a so-called diode characteristic in which the current hardly flows in the reverse direction. For this reason, usually, even if an inspection voltage is applied between two electrodes, the flowing current is zero or a very small value. However, if there is a defective portion that causes a cross stroke or uneven brightness, a current (leakage current) of about several μ to several tens μA flows in the opposite direction depending on the measurement conditions, and is detected by the current detection means. Is done. The current detecting means only needs to be capable of detecting a current of about several μA to several tens μA, and may detect a voltage generated by a resistor or other impedance element in addition to a method of directly detecting a current. In addition, the magnetic field generated by the current is a Hall element,
It may be detected by an MR element or the like.

The judging means 5 judges whether or not the detected current value is in an appropriate range, and if not, notifies the presence of a defective portion by using a display means, a voice transmitting means, or the like.
In this case, the evaluation level may be determined to simply deviate from the normal value, or the detected current value may be divided into several stages to determine and notify a defective state corresponding to each current value. In this way, it is possible to determine where in the manufacturing stage a defect has occurred, and it is also possible to provide feedback such as taking measures to prevent a defect from occurring in the manufacturing stage. The determination means 5 can be composed of a combination of a comparator, a flip-flop, a gate circuit, and the like if it is only for determining the level of the detected current level with respect to a certain threshold level. A processor may be used for separate determination and analysis of the obtained data. In that case, the current detecting means 4
May be provided, or A / D conversion may be performed. The processor may be a dedicated processor or may be used as a processor for controlling the display.

In the case where the judgment is made in a plurality of stages,
For example, it is possible to determine a leak between data lines, a leak between a data line and a scan line, a leak between scan lines, a defect in an organic layer itself, or a state immediately before a failure occurs due to deterioration of an organic layer. is there. These determinations are based on data indicating the correlation between the line in which the defect has occurred, the content of the defect, and the leakage current value, or the occurrence of a certain defect (probable).
It is possible to determine the relationship between the line and other lines by analyzing the data and processing the data obtained by the current detecting means at high speed using a processor based on these data.

The display means may be, for example, an LED display, a liquid crystal display, a plasma display, an organic EL display, or a CRT, or may be a single light bulb, an LED, or the like if only a defect is to be notified. As a voice transmission means, a combination of a voice synthesis IC, a melody IC, a music processor, etc. and a speaker,
A piezoelectric buzzer or the like can be used. These may be appropriately selected depending on the production line to be used, the necessary judgment contents, and the like.

Although the evaluation apparatus has mainly been described above in the manufacturing stage, the apparatus of the present invention can be applied during or after driving the organic EL display. In other words, if a defect has occurred on the display due to aging, this is detected, and the presence of such a defect, the defect is displayed on the display itself, or an alarm sound is generated. It is also possible to inform the person.

At this time, for example, a power supply for driving the organic EL display and a power supply for generating a test voltage are prepared, and before and after driving or at rest, the power supply for driving the element is switched to a power supply for the test voltage, and the switching element is used. It is also possible to operate the connecting means at high speed and inspect the organic EL element in the display at high speed. Such inspections before and after using the display enable early detection of defective parts,
High reliability can be obtained even when used for meters, such as automobiles, trains, and airplanes, which have a particularly important meaning in the display contents.

Next, the organic layer of the organic EL display used in the present invention will be described.

As shown in FIG. 4, the organic EL display used in the present invention has a hole injection electrode (anode) 24, a hole injection / transport layer, a light emission and electron injection / transport layer, The injection electrode (cathode) 23 has a configuration in which a protective layer is laminated, if necessary, and the organic layer is interposed between the injection electrode 23 and the other substrate 21.

The organic EL display of the present invention is not limited to the above-mentioned configuration examples, but may be of various configurations. For example, a light-emitting layer is provided alone, and electron injection and transport are performed between the light-emitting layer and the electron injection electrode. A structure in which layers are interposed can also be used. If necessary, the hole injecting / transporting layer and the light emitting layer may be mixed.

The electron injection electrode is formed by sputtering or vacuum evaporation, and the organic layer such as the light emitting layer is formed by vacuum evaporation or the like.
The hole injection electrode can be formed by vapor deposition, sputtering, or the like.Each of these films is patterned by a method such as etching after mask vapor deposition or film formation as necessary, thereby forming a desired light emitting pattern. Obtainable. After forming the electrode, a protective film using an inorganic material such as SiO _X or an organic material such as Teflon may be formed. The protective film may be transparent or opaque,
The thickness of the protective film is about 50 to 1200 nm. The protective film may be formed by a sputtering method, an evaporation method, or the like.

Furthermore, it is preferable to form a sealing layer on the device in order to prevent oxidation of the organic layers and electrodes of the device. The sealing layer is made of an adhesive resin layer such as a commercially available low-moisture-absorbing light-curing adhesive, an epoxy-based adhesive, a silicone-based adhesive, and a cross-linked ethylene-vinyl acetate copolymer adhesive sheet to prevent moisture from entering. Is used to adhere and seal a sealing plate such as a glass plate. Besides a glass plate, a metal plate, a plastic plate or the like can be used.

The light emitting layer has a function of injecting holes (holes) and electrons, a function of transporting them, and a function of generating excitons by recombination of holes and electrons. It is preferable to use a relatively electronically neutral compound for the light emitting layer.

The hole injecting and transporting layer has a function of facilitating the injection of holes from the positive electrode, a function of stably transporting holes, and a function of preventing electrons. The electron injecting and transporting layer has a function of transporting electrons from the negative electrode. It has the function of facilitating injection, the function of transporting electrons stably, and the function of blocking holes. These layers increase and confine holes and electrons injected into the light-emitting layer, and optimize the recombination region. To improve luminous efficiency.

The thickness of the light emitting layer, the thickness of the hole injecting and transporting layer, and the thickness of the electron injecting and transporting layer are not particularly limited, and vary depending on the forming method.
The thickness is preferably from 0 to 300 nm.

The thickness of the hole injecting and transporting layer and the thickness of the electron injecting and transporting layer depend on the design of the recombination and light emitting region, but may be about the same as the thickness of the light emitting layer or about 1/10 to 10 times. When the injection layer and the transport layer for holes or electrons are separated from each other, the injection layer is preferably 1 nm or more, and the transport layer is preferably 20 nm or more. At this time, the upper limit of the thickness of the injection layer and the transport layer is usually about 500 nm for the injection layer and 5 for the transport layer.
It is about 00 nm. Such a film thickness is the same when two injection / transport layers are provided.

The light emitting layer contains a fluorescent substance which is a compound having a light emitting function. Examples of such a fluorescent substance include compounds disclosed in JP-A-63-264892, for example, at least one selected from compounds such as quinacridone, rubrene, and styryl dyes. A quinoline derivative such as a metal complex dye having 8-quinolinol or a derivative thereof as a ligand, such as tris (8-quinolinolato) aluminum;
Tetraphenylbutadiene, anthracene, perylene,
Coronene, 12-phthaloperinone derivatives, and the like. Further, a phenylanthracene derivative disclosed in Japanese Patent Application No. 6-110569 and a tetraarylethene derivative disclosed in Japanese Patent Application No. 6-114456 can be used.

Further, it is preferable to use in combination with a host substance capable of emitting light by itself, and it is preferable to use it as a dopant. In such a case, the content of the compound in the light emitting layer is 0.01 to 10% by weight, and more preferably 0.1 to 10% by weight.
It is preferably 1 to 5% by weight. When used in combination with a host substance, the emission wavelength characteristics of the host substance can be changed, light emission shifted to a longer wavelength becomes possible, and the luminous efficiency and stability of the device are improved.

As a substrate material, a transparent or translucent material such as glass, quartz, resin, etc. is used. Further, the emission color may be controlled by using a color filter film, a color conversion film containing a fluorescent substance, or a dielectric reflection film on the substrate.

As the color filter film, a color filter used in a liquid crystal display or the like may be used.
The characteristics of the color filter may be adjusted in accordance with the light emitted from the organic EL to optimize the extraction efficiency and the color purity.

If a color filter capable of cutting off short-wavelength external light that is absorbed by the EL element material or the fluorescence conversion layer is used, the light resistance of the element and the display contrast are improved.

An optical thin film such as a dielectric multilayer film may be used in place of the color filter.

The color conversion film absorbs EL light and emits light from the phosphor in the color conversion film to convert the color of the emitted light.
It is formed from a fluorescent material and a light absorbing material.

The organic EL display is a direct current drive type,
Used as AC drive or pulse drive. The applied voltage for driving is usually 2 (especially around 2.5) to 2
It is about 0V.

[0039]

EXAMPLES Next, the present invention will be described more specifically with reference to examples.

FIG. 2 is a circuit diagram showing a more specific embodiment of the organic EL display evaluation apparatus of the present invention. In the figure, an evaluation device for an organic EL display according to the present invention comprises a voltage generating means 3, a current detecting means 4, a determining means 5
And the voltage generating means 3 is a power supply Vcc1 for generating a test voltage. Although the connecting means is omitted in this example, as shown in FIG. 1, a selecting means may be used such that the organic EL display is connected to the nodes N1 and N2.

The current detecting means 4 detects a leak current or the like flowing by the inspection voltage and converts it into a voltage, and resistors R2, R3 and R4 for amplifying a minute voltage generated by the resistor R1 to a voltage of a predetermined level. And an amplifier composed of an operational amplifier IC1. Note that the amplifier is not limited to such a configuration, and may have various configurations for amplifying a minute voltage.

The judging means 5 receives the signal sent from the voltage detecting means, compares the signal with the reference level ref, and when the input signal is smaller than the reference level ref, changes the H level.
Operational amplifier IC2 that outputs L level when large
(Comparator), a resistor R5 for obtaining a power supply voltage reference level ref, a Zener diode ZD, and a resistor R6 for pulling up the output of the operational amplifier IC to the positive power supply side Vcc2.
And In this way, a leak current or the like is generated in the organic EL display, and when a current of a certain level or more flows, the L level indicating that there is a defect is output from the determination means. Note that the output of the operational amplifier IC2 is sent to an alarm device, a warning light control device, a display controller, another control device, or the like as necessary, and an appropriate process is performed depending on the usage mode.

In the example shown, the judging means 5 determines whether the detected current is higher or lower than a predetermined reference level ref.
Although only the value determination is performed, the present invention is not limited to such a configuration. For example, the output of the operational amplifier IC1 may be A / D converted and the value may be read by a processor. The contents of the judgment are the same as those described above.

[0044]

As described above, according to the present invention, the evaluation efficiency is high, objective evaluation is possible, the evaluation result can be fed back to the production line, and the production time can be reduced and the yield can be improved. An evaluation device and an evaluation method for an organic EL display can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of an evaluation device for an organic EL display of the present invention.

FIG. 2 is a circuit diagram of an evaluation device for an organic EL display, which is one embodiment of the present invention.

FIG. 3 is a graph showing a relationship between a leak current and a relative luminance.

FIG. 4 is an external perspective view showing a configuration of an organic EL display.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Organic EL display 2 Connecting means 3 Voltage generating means 4 Current detecting means 5 Judging means 21 Substrate 22 Substrate 23 Scanning electrode 24 Data electrode

Claims (4)

[Claims] A plurality of data electrodes; a plurality of scan electrodes arranged in a direction intersecting the data electrodes;
An organic EL display having an organic EL layer existing between both electrodes, forming an at least one circuit between the data electrode, the organic EL layer, and the scanning electrode; and generating a test voltage for the organic EL display. A voltage generating means for generating the inspection voltage generated by the voltage generating means.
Connecting means for applying between at least two scanning electrodes or data electrodes of the L display; current detecting means for detecting a current flowing between the voltage generating means and the organic EL display; and a current value detected by the current detecting means. An evaluation device for an organic EL display, comprising: a determination unit for determining whether the organic EL display is good or bad. 2. The organic EL display evaluation apparatus according to claim 1, wherein the inspection voltage is lower than an emission voltage of the organic EL display. 3. The evaluation device for an organic EL display according to claim 1, wherein the inspection voltage is 0.1 to 2.5 V. 4. Two or more data electrodes, two or more scan electrodes arranged in a direction crossing the data electrodes,
At least two of the data electrodes or the scan electrodes of an organic EL display having an organic EL layer present between both electrodes, wherein at least one circuit is formed between the data electrodes, the organic EL layer, and the scan electrodes A method for evaluating an organic EL display, comprising: applying a test voltage lower than the light emission voltage of the organic EL display during the test, detecting a current flowing between the electrodes based on the test voltage, and evaluating the organic EL display based on the detected current value.