KR20030033122A - Apparatus and method for evaluating organic el display - Google Patents

Abstract

PURPOSE: An apparatus for evaluating an organic EL display and a method thereof are provided to obtain high evaluation result with high reliability by making a test driving circuit of the organic EL display with a simple circuit configuration. CONSTITUTION: The organic EL display(10) comprises an organic EL device as a pixel(11), and measures a driving current and a discharge current at every pixel by the above organic EL device, and thus detects a pixel defect by detecting a difference between the driving current and the discharge current. The organic EL display also comprises a constant current circuit to drive the above organic EL device and a switch circuit(29,31) switching a voltage to vary a constant current by the constant current circuit.

Description

Evaluation apparatus and evaluation method of organic EL display {APPARATUS AND METHOD FOR EVALUATING ORGANIC EL DISPLAY}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaluation device and an evaluation method of an organic electroluminescent (EL) display (hereinafter referred to as an "organic EL display") using an organic material as a light emitting material, and in particular, a mobile telephone. The present invention relates to an evaluation device and an evaluation method of an organic EL display used in various display devices such as a display panel for display, a car audio display panel, a moving / still image display panel, and an image display for a digital still camera.

In recent years, organic electroluminescent elements (hereinafter referred to as "organic EL elements") have been actively studied and put into practical use.

Fig. 7 is an enlarged cross-sectional view of the main portion of the organic EL element 1 of the conventional type, wherein the organic EL element 1 is a glass substrate 2, an anode 3, a hole transport layer 4, an electron transporting light emitting layer 5, and a cathode 6; It is provided. The DC power supply 7 supplies a DC current by applying a predetermined voltage between the anode 3 and the cathode 6.

Anode 3 employs a transparent electrode made of indium tin oxide (ITO) or the like, a diamine dielectric (TPAC) is employed for the hole transport layer 4, and an aluminum complex (Alq) is employed for the electron transporting light emitting layer 5, thereby providing carrier transport. By stacking these different materials, the carrier recombination rate is increased. As the cathode 6, magnesium (Mg), aluminum (Ag), or the like is employed.

In the organic EL element 1 having such a configuration, carriers (charges of holes and electrons) injected from the anode 3 and the cathode 6 are trapped in the organic layer of the electron transporting light-emitting layer 5, and the carrier recombination efficiency is dramatically increased. A high luminance of 1000 cd / m ² or more can be obtained with a voltage of 10 volts or less.

Therefore, expectations are rising as displays for mobile phones, car audio, home appliances, and the like.

Fig. 8 is a circuit diagram showing one pixel 11 portion of the organic EL display 10 of the active matrix system, wherein the organic EL display 10 is wired in a matrix manner with a plurality of selection lines VG (scanning lines) and signal lines VD at the intersections thereof. Pixel 11 is connected.

The pixel 11 includes a switch circuit 12, a constant current circuit 13, and an organic EL pixel 14 by the organic EL element 1 described above, and applies a constant current to the organic EL pixel 14 by applying a predetermined voltage almost constant from the voltage supply line VLC. The supply is made to emit light.

As for the pixel 11, there is a Japanese Patent Application Laid-open No. Hei 5-107561 and the like, for example, as shown in FIG. Similarly, as the 13, a second transistor 16 and a capacitor 17, such as a TFT, are employed.

The first transistor 15 switches current to supply a constant current to the organic EL element 14.

The second transistor 16 is switched by the first transistor and connects the first transistor to the organic EL element 14.

The capacitor 17 charges a predetermined electric capacity, and auxiliary current is supplied to the organic EL element 14 in accordance with the predetermined discharge time.

In the pixel 11 having such a configuration, one pixel 11 is selected by the first transistor 15, the result of the selection is transferred to the second transistor 16, and the voltage control for one pixel 11 is transferred to the second transistor 16 and the predetermined. The capacitor 17 is capable of maintaining the capacitance for a predetermined time, and maintains a predetermined voltage almost constant from the voltage supply line VLC to reduce the difference in voltage between each pixel 11.

In order to evaluate the organic EL display 10 having such a configuration, conventionally, a driving circuit (not shown) is attached to the organic EL display 10 to form a shape close to the actual product, and the organic EL display 10 is actually driven to produce a line defect. And dot defects were detected by separate image evaluation devices.

Therefore, there is a problem that an error occurs between the evaluation apparatuses and the evaluation criteria, resulting in a decrease in detection accuracy.

In addition, there is a method of evaluating the driving or emitting state of the organic EL display 10 by the human eye, but there is a problem in that the evaluation result varies depending on the skill of the evaluator and the condition of the day.

In addition, when it is determined that the defective product is found to be defective, the organic EL display 10 is destroyed at the same time as the drive circuit component attached thereto, resulting in a wasteful waste. Work time for evaluation is also a waste.

As for the organic EL device, there are JP-A-5-107561, JP-A-9-260061, JP-A-10-321367, and the like.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides an evaluation apparatus and an evaluation method for an organic EL display which can obtain a highly reliable evaluation result by making a driving circuit for inspecting an organic EL display with a simple circuit configuration. It is a task.

Another object of the present invention is to provide an evaluation apparatus and an evaluation method for an organic EL display, which has high detection accuracy and can evaluate the organic EL display itself before coupling the driving circuit for the product to the organic EL display.

Another object of the present invention is to provide an evaluation apparatus and an evaluation method for an organic EL display, in which a circuit configuration is simple and the pixel defects of the organic EL display element can be detected by efficiently detecting a minute current flowing through the organic EL element. do.

In addition, the present invention provides an evaluation apparatus and an evaluation method of an organic EL display which can efficiently detect a small current by preventing the driving current supplied to the organic EL element for inspection from overlapping between a plurality of organic EL elements. It is a subject to offer.

Moreover, an object of this invention is to provide the evaluation apparatus and evaluation method of an organic electroluminescent display which can suppress the fall of the product yield by the process of the defective product by the evaluation result.

1 is a schematic circuit diagram of an evaluation apparatus 20 of an organic EL (hereinafter, referred to as an 'organic EL') display according to a first embodiment of the present invention.

2 is a timing chart for evaluating the organic EL display 10 by driving the evaluation apparatus 20 of the organic EL display according to the first embodiment.

3 is a graph showing pixel current values for each organic EL pixel 14 according to the first embodiment.

Fig. 4 shows each organic EL in the case of the inspection procedure for inspecting the next organic EL pixel 14 without waiting for the time t2 and the discharge time t3 to fall after the supply of the driving current (after the driving time t1) according to the first embodiment. A graph showing pixel current values for the pixel 14.

5 is a schematic diagram of a conventional organic EL display 40 of a simple matrix type.

6 is a schematic circuit diagram of the evaluation apparatus 50 of the organic EL display 40 according to the second embodiment of the present invention.

Fig. 7 is an enlarged cross-sectional view of the main portion of the organic EL element 1 in the conventional type.

Fig. 8 is a circuit diagram showing one pixel 11 portion of the organic EL display 10 in the conventional active matrix system.

FIG. 9 is a circuit diagram showing one pixel 11 portion of the organic EL display 10 in the active matrix method shown in FIG. 8 in more detail.

* Description of symbols on the main parts of the drawings *

1: organic EL device (Fig. 7)

2: glass substrate

3: positive electrode (ITO)

4: hole transport layer

5: electron transporting light emitting layer

6: cathode

7: DC power

10: organic EL display of the active matrix system (Figs. 8 and 9)

11: Pixels of the organic EL display 10

12: switch circuit

13: constant current circuit

14 organic EL pixel (organic EL element)

15: first transistor (TFT)

16: second transistor (TFT)

17 capacitor

20: Apparatus for Evaluating Organic EL Display 10 (Active Matrix System) (First Embodiment, Fig. 1)

21: central control circuit

22: control bus

23: inspection voltage generating circuit

24: current detection circuit

25: current amplifier circuit

26: A / D conversion circuit

27: defect determination circuit

28: control signal generating circuit

29: signal line connection switch circuit (connection switch circuit)

30: selection line connection switch circuit (connection switch circuit)

31: voltage supply line connection switch circuit (connection switch circuit)

40: organic EL display of simple matrix method (Fig. 5)

41: current source

42: signal line selection circuit (data line selection circuit)

43: selection line selection circuit (scan line selection circuit)

50: evaluation device 50 of organic EL display 40 (simple matrix system) (second embodiment, Fig. 6)

51: inspection current generating circuit

52: forward drop voltage detection circuit

VD: Signal Line

VG: Selection Line

VLC: voltage supply line

t1: driving time (first predetermined time)

t2: fall time

t3: discharge time (second predetermined time)

S1: first sampling

S2: second sampling

That is, the present invention prepares a signal line and a selection line (additional voltage supply line in the case of the active matrix system) that can supply the driving current to each pixel (organic EL element) of the organic EL display, and supplies the driving current to the pixel. The next pixel is driven (inspected) for the discharge time, and the difference between the drive current value and the discharge current value of the organic EL pixel in one pixel is measured. Focusing on being able to determine that a pixel by an organic EL element is normal, the first invention is an evaluation device of an organic EL display having an organic EL element as a pixel, and the pixel by the organic EL element. Each drive current value and discharge current value are measured, and the difference between the current values is checked. It is a device for evaluating an organic EL display characterized by detecting pixel defects.

The organic EL display includes a constant current circuit such as a TFT for driving the organic EL element, and a TFT such as a TFT for switching a voltage in order to vary the constant current by the constant current circuit. A switch circuit can be provided.

The organic EL display may include a constant current circuit for driving the organic EL element, a signal line and a selection line for selecting the organic EL element.

A signal line and a selection line for selecting the organic EL element are provided, and the driving current value and the discharge current value can be measured by switching any one of the signal line or the selection line for each pixel of the organic EL element.

A signal line and a selection line for selecting the organic EL element are provided, the driving current is supplied to the organic EL element by switching any one of the signal line or the selection line for each pixel of the organic EL element, and the organic EL element is provided. The charge accumulated in the battery can be released.

A capacitor for supplying a constant current to the organic EL element may be provided, a driving voltage may be supplied for each pixel of the organic EL element, and the charge accumulated in the capacitor may be released.

A first transistor for switching to supply a constant current to the organic EL element, and a second transistor switched by the first transistor and connected to the organic EL element, the first transistor for each pixel of the organic EL element. By switching one transistor, a driving current is supplied to the organic EL element over a first predetermined time, and the second transistor is in a non-conductive state over a second predetermined time following the first predetermined time. You can do

A signal line and a selection line for selecting the organic EL element, and a voltage supply line for supplying a voltage to the organic EL element, and the signal line or selection line for each pixel of the organic EL element with this voltage supply line turned on. Any one of them can be switched to measure the drive current and the discharge current flowing through the organic EL element.

A signal line and a selection line for selecting the organic EL element are provided, and either one of the signal lines or the selection line is switched for each pixel of the organic EL element, and the current supplied to the organic EL element is controlled to control the organic EL element. The driving current and the discharge current flowing in the EL element can be measured.

The second invention is an evaluation device for an organic EL display comprising an organic EL element as a pixel, a signal line and a selection line for selecting the organic EL element, and a voltage supply line for supplying a voltage to the organic EL element. A test voltage generation circuit for generating a test voltage on signal lines, selection lines, and voltage supply lines, a control signal generation circuit for generating control signals for sequentially applying the test voltage to the signal lines, selection lines, and voltage supply lines at regular intervals; A connection switch circuit for connecting this control signal to said organic EL element via said signal line, selection line and voltage supply line, a current detecting circuit for detecting a drive current and a discharge current flowing through said organic EL element, and a detected current value Determination of the quality of the organic EL device An evaluation unit of the organic EL display comprising the identification circuit.

A third invention is an evaluation device for an organic EL display having an organic EL element as a pixel and a signal line and a selection line for selecting the organic EL element, wherein an inspection current is generated to generate an inspection current in the signal line and the selection line. A circuit, a control signal generating circuit for generating a control signal for sequentially applying the inspection current to the signal line and the selection line at a predetermined cycle, and for connecting the control signal to the organic EL element through the signal line and the selection line. An organic EL comprising a connection switch circuit, a current detection circuit for detecting a drive current and a discharge current flowing through the organic EL element, and a defect determination circuit for determining the quality of the organic EL element from the detected current value. The evaluation device of the display.

In particular, for a simple matrix type organic EL display, a forward drop voltage detection circuit for measuring forward drop voltage of the organic EL element is provided, and the defect determination circuit includes the detected current value and the forward direction. It can be determined whether the organic EL element is from the drop voltage value.

And a current amplifier circuit for amplifying the current detected by the current detection circuit, and an A / D conversion circuit for converting the amplified current into a digital signal.

In particular, in the setting of the inspection voltage in the inspection voltage generating circuit, the generation of the control signal in the control signal generating circuit, and the setting of the current amplification in the current amplifier circuit for an organic EL display of an active matrix type, This can be arbitrarily set by the bus data from the central control circuit.

In particular, in the simple matrix type organic EL display, in the setting of the inspection current in the inspection current generating circuit, the generation of the control signal in the control signal generating circuit, and the setting of the current amplification degree in the current amplifier circuit. The bus data from the central control circuit can be set arbitrarily.

A fourth invention is an evaluation apparatus for an organic EL display comprising a signal line and a selection line arranged in a matrix, and an organic EL element as a pixel connected to the signal line and the selection line at each intersection of the signal line and the selection line, respectively. And by switching one of the signal line and the selection line for each pixel of the organic EL element, driving the organic EL element, measuring a drive current value and a discharge current value of the organic EL element, and detecting a difference in the current value. It is an evaluation apparatus of an organic EL display characterized by detecting the.

The fifth invention is an evaluation device for an organic EL display comprising a signal line and a selection line arranged in a matrix, and an organic EL element as a pixel connected to the signal line and the selection line at each intersection of the signal line and the selection line, respectively. The organic EL element is driven by switching any one of the signal line and the selection line for each pixel of the organic EL element, and first sampling the driving current value within the driving time of the organic EL element. And a second sampling of the discharge current value after the end of the discharge time, which measures the drive current value and the discharge current value, and detects the pixel defect by detecting the difference in the current value.

A sixth invention is an evaluation method of an organic EL display having an organic EL element as a pixel, wherein a pixel defect is detected by measuring a drive current value and a discharge current value for each pixel by the organic EL element and detecting a difference in the current value. It is an evaluation method of the organic electroluminescent display characterized by the above-mentioned.

In the evaluation apparatus and evaluation method of the organic EL display according to the present invention, after the driving current is supplied to each pixel (organic EL element) of the organic EL display, the next pixel is driven or inspected for a period of time during which the organic EL element is discharged. In particular, since the difference between the drive current value and the discharge current value of the organic EL element is measured, the driving current can be supplied and discharged for each pixel (organic EL element), and each organic EL element is individually provided. Can be checked

If this difference in current value is within a predetermined level, it can be determined that the organic EL element constituting one pixel is normal.

In particular, according to the first invention, since the difference between the drive current value and the discharge current value is detected for each pixel by the organic EL element, the same pixel can be detected for the next pixel (organic EL element) after the discharge ends. Since the drive current value by the previous detection does not remain in the next pixel, evaluation for each pixel can be performed reliably sequentially.

In particular, according to the second invention, the active voltage organic EL display is provided with an inspection voltage generation circuit, a control signal generation circuit, an organic EL display connection switch circuit, a current detection circuit, and a defect determination circuit. Unlike the conventional evaluation apparatus in which the driving circuit is attached to the organic EL display to form a form close to the actual product and then inspected, the evaluation operation can be performed in the form of the organic EL display.

In particular, according to the third aspect of the invention, for a simple matrix type organic EL display that does not have a constant current circuit in a pixel of the organic EL element, a signal line is used instead of the inspection voltage generation circuit in the evaluation apparatus of the active matrix type organic EL display. And an inspection current generating circuit for generating an inspection current at the selection line, so that the same evaluation work as in the second invention can be performed.

In particular, according to the fourth aspect of the present invention, one of the signal lines and the selection lines is switched for each organic EL element connected at each intersection of the signal lines and the selection lines arranged in a matrix so as to detect a difference between the driving current value and the discharge current value. Therefore, each pixel can be quickly evaluated by the signal line or the selection process of the selection line.

In particular, according to the fifth invention, the first sampling of the drive current value is performed within the driving time of the organic EL element, and the second sampling of the discharge current value is performed after the end of the discharge time following the driving time. An appropriate current value for the evaluation can be measured for the EL element.

In particular, according to the sixth invention, since the next pixel (organic EL element) is detected for each pixel after the end of discharge in the same way as in the first invention, the drive current value by the previous detection does not remain in the next pixel. It is possible to reliably evaluate each pixel sequentially.

(Example)

Next, the evaluation apparatus 20 of the organic EL display according to the first embodiment of the present invention will be described with reference to Figs. However, the same parts as those in Figs. 7 to 9 are denoted by the same reference numerals and detailed description thereof will be omitted.

Fig. 1 is a schematic circuit diagram of the evaluation apparatus 20 of the organic EL display 10. The evaluation apparatus 20 of the organic EL display 10 determines or evaluates the quality of each pixel 11 of the organic EL display 10, its wiring, and the like. Control circuit 21 (CPU), control bus 22, test voltage generator circuit 23, current detection circuit 24, current amplifier circuit 25, A / D conversion circuit 26, fault determination circuit 27, control signal generator circuit 28 and signal line connection switch circuit 29 (Connection switch circuit), selection line connection switch circuit 30 (connection switch circuit) and voltage supply line connection switch circuit 31 (connection switch circuit).

The central control circuit 21 controls the whole via the control bus 22.

The test voltage generating circuit 23 generates a test voltage for testing the organic EL display 10, and is connected to the signal line connecting switch circuit 29, the selection line connecting switch circuit 30, and the current detecting circuit 24.

The inspection voltage may be less than or equal to a voltage which does not destroy the organic EL display 10. However, preferably, a voltage lower than the light emitting voltage may allow a current required for evaluation of the organic EL display 10 to flow. The light emission voltage of the organic EL pixel 14 of the organic EL display 10 is usually about 2 to 4 volts depending on the organic material and electrode material to be used. Therefore, the inspection voltage may be generated up to about 4 volts.

As the test voltage generating circuit 23, any desired voltage can be generated. For example, the test voltage can be easily generated by using a constant voltage circuit, a regulator circuit, or the like.

The signal line connection switch circuit 29 is for connecting the signal line VD in the organic EL display 10 to the respective pixels 11 in sequence, and the control signal for the switching is supplied from the control signal generation circuit 28.

The selection line connection switch circuit 30 is for connecting the selection line VG in the organic EL display 10 to the respective pixels 11 in sequence, and the control signal for switching is supplied from the control signal generation circuit 28.

The voltage supply line connection switch circuit 31 is for connecting the voltage supply line VLC in the organic EL display 10 to each pixel 11 in sequence, and the control signal for the switching is supplied from the control signal generation circuit 28.

Therefore, the inspection voltage generation circuit 23 supplies the inspection voltage through the signal line connection switch circuit 29 and the selection line connection switch circuit 30, and also through the current detection circuit 24 and the voltage supply line connection switch circuit 31, and the signal lines VD, the selection line VG and the voltage. It can supply each supply line VLC.

The current detection circuit 24 is for detecting the drive current and the discharge current flowing through one pixel 11 (organic EL pixel 14 to organic EL element 1). The current detection circuit 24 is connected to the voltage supply line connection switch circuit 31 and the detected current value is supplied to the current amplifier circuit 25. Output

The current amplifier circuit 25 amplifies the detected current.

The A / D conversion circuit 26 converts the amplified current into a digital signal.

The defect judging circuit 27 determines whether each pixel 11 to the organic EL pixel 14 (organic EL element 1) in the organic EL display 10 is determined based on the detected current value (details will be described later based on FIG. 4).

The control signal generation circuit 28 supplies control signals to the A / D conversion circuit 26, the signal line connection switch circuit 29, the selection line connection switch circuit 30, and the voltage supply line connection switch circuit 31.

FIG. 2 is a timing chart for evaluating the organic EL display 10 by driving the evaluation apparatus 20 of the organic EL display 10, and is shown for the first pixel and the second pixel.

In the inspection of the organic EL pixel 14 of the organic EL display 10 pixel 11, the organic EL pixel 14 selected in the inspection needs to be sufficiently discharged at the end of the inspection of each pixel 11. That is, in the inspection of the organic EL pixel 14, the on / off timing of each signal line VD, the selection line VG, and the voltage supply line VLC by the control signal generation circuit 28 is important.

Specifically, referring to Figs. 1 and 2, at the start of the inspection, the selection line VG of the organic EL pixel 14 of the predetermined pixel 11 (first pixel) is passed from the inspection voltage generation circuit 23 to the selection line connection switch circuit 30. When the voltage is supplied to turn on the first transistor 15 (Fig. 9) and the voltage VD1 is supplied to the signal line VD through the signal line connection switch circuit 29, the voltage for driving the second transistor 16 is supplied to V1. The second transistor 16 is turned on. The capacitor 17 is charged with the rise of the voltage V1.

In this state, the voltage supply line VLC is turned on to cause the voltage V2 to the organic EL pixel 14 to rise. That is, the inspection voltage is supplied to the organic EL pixel 14 to perform the first sampling S1 within this driving time t1 (the first predetermined time) to measure the driving current of the organic EL pixel 14.

After the measurement of the drive current, the signal line VD is turned off to completely discharge (discharge) the capacitor 17 and the organic EL pixel 14 after the fall time t2 has elapsed, and stabilizes this discharge state to completely turn off the second transistor 16. In addition, the discharge current is measured by performing the second sampling S2 within the discharge time t3 (second predetermined time).

The difference between the drive current (drive current data) and this discharge current (discharge current data) is obtained, and the organic EL pixel 14 (the Defect regarding one pixel) is detected.

Specifically, it is as follows. 3 is a graph showing pixel current values for each organic EL pixel 14, and the evaluation reference value of the pixel current values is set to a value within a predetermined level range.

For this predetermined level range or threshold value, the average operating current difference of the normal organic EL pixel 14 is obtained in advance, and it is determined that the organic EL pixel 14 in which the current value deviating from this range is detected is a defective pixel. For example, when the upper limit of the range is exceeded, the first transistor 15, the second transistor 16, or the wiring portion is considered to be defective. In the example shown in the drawing, the n + 3th organic EL pixel 14 has excessively strong emission intensity and is white. It is determined that the defect is on the side.

If the pixel current value is less than the lower limit of the range, the current itself is difficult to flow, so it is considered to be a line defect or a dot defect. For example, the n + 6th organic EL pixel 14 has a weak emission intensity and is determined to be a defect on the black side.

Thus, in the inspection of the next second pixel (organic EL pixel 14), since the influence of the driving state or the inspection state of the first pixel can be left at all, normal and reliable pixel inspection can be continued sequentially. have.

Thus, by assembling and commercializing the accessory parts such as the driving circuit only in the organic EL display 10 evaluated as normal, the product yield in the manufacturing and evaluation process can be improved.

FIG. 4 is a graph similar to FIG. 3 in the case where the next organic EL pixel 14 is inspected without providing the fall time t2 and the discharge time t3 after the supply of the drive current (after the drive time t1) as described above. Since the superimposition of the driving currents for each pixel occurs sequentially, the pixel current value gradually increases, and only the defect on the white side becomes a defect. Evaluation is virtually difficult or impossible.

The evaluation apparatus and evaluation method of the organic EL display according to the present invention are not limited to the organic EL display 10 of the active matrix system, but each organic EL pixel 14 includes a switch circuit 12 and a voltage supply line VLC (Figs. 8 and 9). It is also applicable to the organic EL display 40 of the simple matrix method which is not performed.

5 is a schematic diagram of the organic EL display 40 of a simple matrix type. The organic EL display 40 supplies a current to the organic EL pixel 14 (organic EL element 1) from a current source 41 capable of supplying a constant current, and to the organic EL pixel 14. The light can be emitted by selectively supplying a drive current by the signal line selection circuit 42 (data line selection circuit) and the selection line selection circuit 43 (scan line selection circuit).

Fig. 6 is a schematic circuit diagram of the evaluation device 50 of the organic EL display 40 (simple matrix method) according to the second embodiment of the present invention, wherein the evaluation device 50 of the organic EL display 40 is the evaluation device 20 of the organic EL display 10 (Fig. The voltage supply line connection switch circuit 31 in 1) is omitted, and an inspection current generation circuit 51 is provided in place of the inspection voltage generation circuit 23 (FIG. 1). The inspection current generation circuit 51 and the current amplification circuit 25 are provided. The forward drop voltage detecting circuit 52 is connected between the organic EL display 40 and the organic EL pixel 14 (organic EL element 1) in the organic EL display 40 can be inspected.

The inspection current generating circuit 51 sequentially generates the inspection current in the signal line VD and the selection line VG. That is, the organic EL pixel 14 (organic EL element 1) of the organic EL display 40 (Fig. 5) of the simple matrix type is a constant current circuit as in the organic EL display 10 (Figs. 1, 8 and 9) of the active matrix type. Since no 13 is provided, the inspection current must be supplied directly from the inspection current generation circuit 51 to the organic EL pixel 14 for the evaluation of the organic EL pixel 14.

The forward drop voltage detecting circuit 52 detects the forward drop voltage when the organic EL pixel 14 (organic EL element 1) normally operates, as shown by a virtual line in FIG. That is, the organic EL pixel 14 in the organic EL display 40 of the simple matrix system flows in the same way when the organic EL element 1 is normal or short-circuited. However, in the normal case, the forward drop voltage is generated and a short circuit occurs. In this case, since the forward drop voltage does not occur, the pixel defect is detected by detecting the forward drop voltage together with the detection current.

Since the evaluation procedure by the evaluation apparatus 50 of such a structure is the same as that of the evaluation apparatus 20 based on FIG. 1 thru | or FIG. 4, the detailed description is abbreviate | omitted. By switching the signal line VD by the signal line selection circuit 42 or the selection line VG by the selection line selection circuit 43 for each organic EL pixel 14, the difference between the drive current value and the discharge current value is measured, and the defect determination circuit 27 performs a current detection circuit. The quality of the organic EL element 1 is determined from the current value detected by 24 and the forward drop voltage value detected by the forward drop voltage detection circuit 52.

As described above, according to the present invention, since the difference between the driving current and the discharge current of the organic EL pixel or the organic EL element in the organic EL display is detected and the quality of the organic EL display is determined based on this, the organic EL pixel is determined. All of them can also be appropriately evaluated sequentially.

Claims (18)

An evaluation device for an organic EL display including an organic EL element as a pixel, The driving current value and the discharge current value are measured for each pixel by the organic EL element, Detecting pixel defects by detecting differences in the current values Evaluation apparatus for organic EL display, characterized in that. The method of claim 1, The organic EL display, A constant current circuit for driving the organic EL element and a switch circuit for switching a voltage in order to vary the constant current by the constant current circuit. Evaluation apparatus for organic EL display, characterized in that. The method of claim 1, The organic EL display includes a constant current circuit for driving the organic EL element; A signal line and a selection line for selecting the organic EL element Evaluation apparatus of the organic electroluminescent display characterized by including. The method of claim 1, A signal line and a selection line for selecting the organic EL element, The driving current value and the discharge current value are measured by switching any one of the signal line and the selection line for each pixel of the organic EL element. Evaluation apparatus for organic EL display, characterized in that. The method of claim 1, A signal line and a selection line for selecting the organic EL element, Any one of these signal lines or selection lines is switched for each pixel by the organic EL element, Supplying a driving current to the organic EL element, To discharge charges accumulated in the organic EL device Evaluation apparatus for organic EL display, characterized in that. The method of claim 1, A capacitor for supplying a constant current to the organic EL element, A driving voltage is supplied to each pixel by the organic EL element, Releases the charge accumulated in the capacitor Evaluation apparatus for organic EL display, characterized in that. A first transistor for switching to supply a constant current to the organic EL element, A second transistor switched by the first transistor and connected to the organic EL element; By switching the first transistor for each pixel by the organic EL element, A drive current is supplied to the organic EL element over a first predetermined time, and the second transistor is brought into a non-conductive state over a second predetermined time following the first predetermined time. Evaluation apparatus for organic EL display, characterized in that. The method of claim 1, A signal line and a selection line for selecting the organic EL element, A voltage supply line for supplying a voltage to the organic EL element Equipped, In the state where the voltage supply line is turned on, any one of the signal line or the selection line is switched for each pixel by the organic EL element, Measuring the drive current and the discharge current flowing through the organic EL device Evaluation apparatus for organic EL display, characterized in that. The method of claim 1, A signal line and a selection line for selecting the organic EL element, Any one of these signal lines or selection lines is switched for each pixel of the organic EL element, and By controlling the current supplied to the organic EL device to measure the drive current and the discharge current flowing through the organic EL device Evaluation apparatus for organic EL display, characterized in that. An organic EL element that is a pixel, A signal line and a selection line for selecting this organic EL element, Voltage supply line for supplying voltage to this organic EL element As an evaluation device for an organic EL display to be provided, An inspection voltage generating circuit for generating an inspection voltage on the signal line, the selection line, and the voltage supply line; A control signal generation circuit for generating a control signal for sequentially applying the inspection voltage to the signal line, the selection line, and the voltage supply line at regular intervals; A connection switch circuit for connecting this control signal to said organic EL element via said signal line, selection line and voltage supply line; A current detection circuit for detecting a drive current and a discharge current flowing through the organic EL element; A defect determination circuit for determining the quality of the organic EL element from the detected current value Evaluation apparatus of the organic electroluminescent display characterized by including. An organic EL element that is a pixel, Signal line and selection line for selecting this organic EL element As an evaluation device for an organic EL display to be provided, An inspection current generating circuit for generating an inspection current in the signal line and the selection line; A control signal generation circuit for generating a control signal for sequentially applying the inspection current to the signal line and the selection line at regular intervals; A connection switch circuit for connecting the control signal to the organic EL element via the signal line and the selection line; A current detection circuit for detecting a drive current and a discharge current flowing through the organic EL element; A defect determination circuit for determining whether the organic EL element is Evaluation apparatus of the organic electroluminescent display characterized by including. The method of claim 11, A forward drop voltage detecting circuit for measuring forward drop voltage of the organic EL element is provided; The defect judging circuit determines whether the organic EL element is good or not from the detected current value and the forward drop voltage value. Evaluation apparatus for organic EL display, characterized in that. The method according to claim 10 or 11, wherein A current amplifier circuit for amplifying the current detected by the current detection circuit; A / D conversion circuit for converting this amplified current into digital signal Evaluation apparatus of the organic electroluminescent display characterized by including. The method of claim 13, Setting the inspection voltage in the inspection voltage generating circuit; Generation of the control signal in the control signal generation circuit and In setting the current amplification degree in the current amplifying circuit, This can be set arbitrarily by bus data from the central control circuit. Evaluation apparatus for organic EL display, characterized in that. The method of claim 13, Setting of the inspection current in the inspection current generating circuit, Generation of the control signal in the control signal generation circuit, and In setting the current amplification degree in the current amplifying circuit, This can be set arbitrarily by bus data from the central control circuit. Evaluation apparatus for organic EL display, characterized in that. Signal and selection lines arranged in a matrix, At each intersection of the signal line and the selection line, an organic EL element that is a pixel connected to the signal line and the selection line, respectively, As an evaluation device for an organic EL display to be provided, For each pixel of the organic EL element, any one of the signal line and the selection line is switched to drive the organic EL element, and the drive current value and the discharge current value of the organic EL element are measured. Detecting pixel defects by detecting differences in their current values Evaluation apparatus for organic EL display, characterized in that. Signal and selection lines arranged in a matrix, At each intersection of the signal line and the selection line, an organic EL element that is a pixel connected to the signal line and the selection line, respectively, As an evaluation device for an organic EL display to be provided, The organic EL element is driven by switching any one of the signal line and the selection line for each pixel of the organic EL element. First sampling of the drive current value within the drive time of the organic EL element, By the second sampling of the discharge current value after the end of the discharge time following this drive time, The pixel defect is detected by measuring the drive current value and the discharge current value and detecting the difference between the current values. Evaluation apparatus for organic EL display, characterized in that. As an evaluation method of an organic EL display having an organic EL element as a pixel, The driving current value and the discharge current value are measured for each pixel by the organic EL element, Detecting pixel defects by detecting differences in their current values Evaluation method of the organic EL display, characterized in that.