JP2006100099A - Panel inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to shorten measuring time and carry out defect inspection of an organic EL panel in a state that a driving circuit is assembled at inspection of the organic EL panel. <P>SOLUTION: As for respective pixels of the organic EL panel, by driving the pixels by periodic signals, driving at different voltages within those periods, and by carrying out the defect inspection by comparing obtained currents, the measuring time to measure discharge current is shortened and the inspection is carried out in a short time. A panel inspecting device 1 is provided with a driving pattern output part 4 for the inspection to output the driving pattern for the inspection to the organic EL panel 2, and a measurement processing part 11 to evaluate the organic EL panel based on a current value which flows in the respective pixels of the organic EL panel. The driving pattern for the inspection is made to be the driving pattern to periodically drive the pixels, and the measurement processing part 11 carries out defect judgment of the organic EL panel based on a difference between the current values obtained in applying different voltages. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inspection apparatus for detecting pixel defects in an organic EL panel used for an organic EL display or the like.

  In the organic EL panel, a plurality of scanning lines and signal lines are arranged in a matrix, and pixels are arranged at intersections of the lines. Each pixel includes a switching circuit that performs a switching operation by a scanning line and a signal line, a constant current circuit that supplies a constant current upon application of a predetermined voltage from a power supply line, and an organic EL pixel that is connected to the constant current circuit. The organic EL pixel of the pixel selected by the switch circuit emits light when supplied with a current from a constant current circuit.

  In order to evaluate such an organic EL display, a method is known in which an organic EL panel is driven by an inspection signal and the lighting state of the panel is observed visually or by an imaging device such as a CCD camera. It has been pointed out that there are variations in evaluation results due to differences in individual or even the same person due to changes in evaluation criteria.

For such a problem, an evaluation apparatus that evaluates an organic EL display by measuring a current flowing through a pixel of the organic display has been proposed (for example, Patent Document 1).
Japanese Patent Laid-Open No. 2002-40074

  The evaluation apparatus includes a connection switch circuit that connects a scanning line, a signal line, and a voltage supply line to an organic EL display, and evaluates an organic EL display in a state before incorporating a drive circuit. The difference between the drive current value and the discharge current value is obtained for each pixel, and the defect detection of the organic EL pixel is performed based on the difference between the current values (operation current difference).

  In the above configuration, it is necessary to measure both the drive current value and the discharge current value, and there is a problem that the measurement time becomes long. This measurement time problem becomes more prominent as the number of pixels increases. Further, since the defect detection of the organic EL pixel is performed by comparing the operating current difference with a threshold value, the accuracy of defect detection is reduced depending on the difference between the operating current difference and the threshold value or the noise level. There's a problem.

  In addition, since the evaluation apparatus is an inspection target for the organic EL display before the drive circuit is incorporated, when the defect inspection is performed at a later stage of the manufacturing process of the organic EL panel, the drive circuit is incorporated. There is also a problem that it cannot be applied to an organic EL panel.

  In view of the above, an object of the present invention is to solve the above-described problems and shorten the measurement time in the inspection of an organic EL panel. A second object is to perform a defect inspection of an organic EL panel in which a drive circuit is incorporated.

  In order to solve the above-mentioned object, according to the present invention, for each pixel of an organic EL panel, the pixel is driven with a periodic signal, and is driven with a different voltage within the period, and the obtained current is compared, and defect inspection is performed. By performing this, the measurement time for measuring the discharge current is shortened and the inspection is performed in a short time.

  A panel inspection apparatus according to the present invention includes an inspection drive pattern output unit that outputs an inspection drive pattern to an organic EL panel, and a measurement value processing unit that evaluates the organic EL panel based on a current value flowing through each pixel of the organic EL panel. The test drive pattern is a drive pattern for periodically driving the pixels, and the measurement value processing unit is an organic EL panel based on a difference between current values obtained when different voltages are applied to the pixels within the same cycle. Defect determination is performed.

  According to the first aspect of the present invention, the drive pattern output unit periodically outputs a test drive pattern output unit to the organic EL panel, and the organic EL panel based on the current value flowing through each pixel of the organic EL panel. And a measurement value processing unit that evaluates the test drive pattern as a drive pattern for periodically driving the pixel by turning on / off, and the measurement value processing unit has a current value when the pixel is on and a current value when the pixel is off. The defect determination of the organic EL panel is performed based on the difference from the current value. The drive pattern can be formed by turning on / off the video signal.

  According to the first aspect, data used for pixel defect determination can be acquired by an on / off operation performed within one cycle in the drive pattern.

  In addition, according to the first aspect, since the video signal supplied to the drive circuit can be used as the inspection drive pattern, the defect inspection of the organic EL panel in which the drive circuit is incorporated can be easily performed.

  According to the second aspect of the present invention, the driving pattern output unit periodically outputs a driving pattern for inspection to the organic EL panel, and the organic EL panel based on the current value flowing through each pixel of the organic EL panel. In the configuration including the measurement value processing unit that evaluates, the test drive pattern is a drive pattern that periodically drives the pixel, and the measurement value processing unit performs waveform comparison between the waveform of the measurement current of the pixel and a reference waveform obtained in advance. Defect determination of the organic EL panel is performed. The driving pattern can be an arbitrary waveform such as a triangular wave, a sawtooth wave, a sine wave, or a rectangular wave.

  According to the second aspect, data used for pixel defect determination can be acquired by an operation based on a signal within one cycle in the drive pattern.

  Further, according to the second aspect, since an easily formed signal such as a triangular wave, a sawtooth wave, a sine wave, or a rectangular wave can be used as an inspection drive pattern, the organic EL panel in a state in which a drive circuit is incorporated The defect inspection can be easily performed.

  According to the panel inspection apparatus of the present invention, the measurement time can be shortened in the inspection of the organic EL panel. In addition, it is possible to perform a defect inspection of the organic EL panel in which the drive circuit is incorporated.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  First, a schematic configuration of the organic EL panel inspection apparatus of the present invention will be described with reference to FIG.

  In FIG. 1, the organic EL panel 2 includes, for example, data line (signal lines) and scan signal line (scan lines) control / signal lines arranged in a grid pattern in the vertical and horizontal directions, and the lines cross each other. An organic EL element connected to the organic EL electrode is arranged, and the organic EL electrode is connected to a voltage supply line via a switch circuit to perform a light emitting operation by supplying a driving current to the organic EL element. The switch circuit is controlled by the control circuit that receives the data line and the scan signal.

  In FIG. 1, the data line of the organic EL panel 2 is connected to the horizontal drive circuit 5, the scan signal line is connected to the vertical drive circuit 7, and the normal drive operation is performed based on the drive signal from the drive circuit 3.

  The panel inspection apparatus 1 according to the present invention includes an inspection drive pattern output unit 4 that outputs an inspection drive pattern to the organic EL panel 2 and a measurement obtained by measuring a current value flowing through each pixel of the organic EL panel 2. And a measured value processing unit 11 that evaluates the organic EL panel based on the current value.

  In FIG. 1, the current value flowing through each pixel is measured by the measurement unit 8 and the obtained measurement current value is sent to the measurement value processing unit 11. However, the measurement value processing unit 11 and the measurement unit 8 are common. You may comprise by the circuit of.

  Further, FIG. 1 shows a configuration example in which the inspection control unit 10 controls the drive circuit 3, the inspection drive pattern output unit 4, the measurement unit 8, and the measurement value processing unit 11.

  In the panel inspection apparatus 1 having the above-described configuration, the inspection drive pattern output unit 4 applies a different voltage within the same period to each pixel by outputting an inspection drive pattern for periodically driving each pixel. The current flowing in the organic EL element by this voltage application is measured, and the measurement value processing unit 11 determines the defect of the organic EL panel based on the difference between the current values obtained when different voltages are applied within the same period.

  The inspection drive pattern can be a drive pattern for periodically driving each pixel by on / off, or a periodic signal such as a triangular wave or a sine wave.

  In addition, the defect determination of the organic EL panel by the measurement value processing unit is performed based on the difference between the current value when the pixel is on and the current value when the pixel is off according to the on / off drive pattern, as well as a triangular wave or a sine wave. It can be performed based on a difference in current value due to different voltage driving in one period flowing through the pixel by a driving pattern having a periodicity such as. Further, in the case of using a driving pattern having a periodicity such as a triangular wave or a sine wave, it is possible to determine the defect of the organic EL panel by comparing the waveform of the measurement current of the pixel with a waveform obtained in advance.

  A first operation example of the panel inspection apparatus of the present invention will be described with reference to the flowchart of FIG. 2, the signal diagram of FIG. 3, and the state diagrams of FIGS. Note that the first operation example shows an example using an inspection drive pattern in which each pixel is periodically driven on / off.

  The inspection drive pattern is generated by turning on / off the video signal (step S1).

  A pixel to be inspected is selected from a plurality of pixels included in the organic EL panel, and is driven by an inspection driving pattern. The pixel is selected by selecting a data line and a scan signal line for supplying a control signal, and the pixel is driven by supplying an inspection drive pattern to the selected pixel via the data line (step S2).

  The inspection drive pattern includes a period in which the video signal is turned on and a period in which the video signal is turned off during one cycle. FIG. 3C shows an example of a driving pattern for inspection. During the period of the shift register signal shown in FIG. 3B or the clock signal shown in FIG. Is included.

  The current flowing through the pixel is measured by applying this test drive pattern, and the measured current value when the video signal is turned on is (A), and the measured current value when the video signal is turned off is (B). . In FIG. 3 (d), in the period marked with a, the measured current value at the time of turning on shows a predetermined value and the measured current value at the time of turning off shows 0, and in the period marked with the sign b, when turned on and off. The measured current value of 1 indicates a predetermined value, and in the period indicated by the symbol c, the measured current value at the time of ON and OFF indicates 0, and in the period indicated by the symbol d, the measured current value at the time of ON indicates a predetermined value. The measured current value at the off time is smaller than that at the on time.

  The measured current values (A) and (B) are obtained by sampling the measured current at a predetermined sampling period (the points in FIG. 3 (d) indicate sampling points), and the obtained sampling values are obtained for each period of each period. For example, it calculates | requires by calculating an average value (step S3).

  Next, the difference between the obtained measured current values (A) and (B) is calculated and obtained. Here, the periods within one cycle are denoted by A and B, and the measured current values measured during the periods are denoted by () such as (A) to (B).

  This difference (A)-(B) in the measured current value corresponds to the current flowing through the pixel. FIG. 3E schematically shows the difference (A)-(B) in the measured current value. For example, the value of (A) is calculated as the measured current value difference (A) − (B) in the period with the symbol a, and the measured current value difference (A) − ( 0 is calculated as B), and in the period marked with the symbol d, a value smaller than (A) is calculated as the measured current value difference (A)-(B).

  The difference (A)-(B) between the measured current values (A) and (B) indicates a different value depending on whether the pixel is normal or defective. Therefore, pixel defect determination is performed in the following process using the measured current value difference (A)-(B) as an index (step S4).

  When the value of the measured current value difference (A)-(B) calculated in step S4 is 0 (step S5), the signal state within the period is the state of the period b or the period c in FIG. One of the states. Whether it is in the state of the period b or the state of the period c is classified by whether or not the value (A) of the period A is zero.

  If (A)-(B) = 0 and (A) ≠ 0 (step S6), this corresponds to the state of the period b in FIG. Is shown.

  FIG. 5 shows a state diagram for explaining the white defect. In a state where the pixel is short-circuited and a current always flows, regardless of the data state of the data signal and the scan signal, the changeover switch unit in both the on state shown in FIG. 5A and the off state shown in FIG. 2d is always on. Therefore, the currents (A) and (B) always indicate predetermined values that are not 0, and the measured current value difference (A)-(B) is 0 (step S7).

  In step S6, when (A)-(B) = 0 and (A) = 0, black corresponds to the state of the period c in FIG. Indicates a defect.

  FIG. 6 shows a state diagram for explaining the black defect. In the state where the pixel does not always flow due to disconnection or the like, the change-over switch in either the on state shown in FIG. 6 (a) or the off state shown in FIG. 6 (b) regardless of the signal state of the data signal and the scan signal. Part 2d is always off. Therefore, the currents (A) and (B) always show a value of 0, and the measured current value difference (A)-(B) becomes 0 (step S8).

  When the value (A)-(B) calculated in step S4 is not 0 (step S5), the signal state in the cycle is either the state of cycle a or the state of cycle d in FIG. is there. Whether it is in the state of the period a or the state of the period d is classified by whether or not the value (B) of the period B is zero.

  In step S5, if (A)-(B) ≠ 0 and (B) ≠ 0 (step S9), this corresponds to the state of the period d in FIG. Is shown.

  FIG. 7 shows a state diagram for explaining a leak defect state. When there is a leak defect in the pixel, the pixel is selected according to the signal state of the data signal and the scan signal, and when the driving is instructed by the data signal, the changeover switch unit 2d is turned on and FIG. The on state shown in FIG. On the other hand, when the driving is not instructed by the data signal, the changeover switch portion 2d is turned off, but the leakage state shown in FIG.

  Therefore, the current value (A) indicates a predetermined value other than 0, the current value (B) also indicates a value smaller than 0 (A), and the measured current value difference (A) − (B) is greater than (A). Becomes a small value (step S9).

  In step S5, when (A)-(B) ≠ 0 and (B) = 0 (step S9), this corresponds to the state of period a in FIG. Indicates the pixel state.

  FIG. 4 shows a state diagram for explaining the normal state. When the pixel is in a normal state, the pixel is selected according to the signal state of the data signal and the scan signal, and when the driving is instructed by the data signal, the changeover switch unit 2d is turned on and shown in FIG. When the drive state is not commanded by the data signal, the changeover switch portion 2d is turned off and the turn-off state shown in FIG.

  Therefore, the current value (A) indicates a predetermined value that is not 0, the current value (B) indicates 0, and the measured current value difference (A)-(B) becomes (A) (step S11).

  The panel inspection of the organic EL panel can be performed by performing the above steps S2 to S10 for all the pixels of the organic EL panel. FIG. 3F shows the pixel determination result (step S12).

  A second operation example of the panel inspection apparatus of the present invention will be described with reference to the flowchart of FIG. 8 and the signal diagram of FIG. In the second operation example, an inspection drive pattern having periodicity such as a triangular wave, a sawtooth wave, a sine wave, or a rectangular wave is used for each pixel.

  The defect determination of the organic EL panel can be performed based on a difference between current values due to different voltage driving within one period flowing through the pixel, or by comparing the waveform of the measured current of the pixel with a waveform obtained in advance. .

  The inspection drive pattern is generated by a signal having periodicity such as a triangular wave, a sawtooth wave, a sine wave, or a rectangular wave (step S21).

  A pixel to be inspected is selected from a plurality of pixels included in the organic EL panel, and is driven by an inspection driving pattern. The pixel is selected by selecting a data line and a scan signal line for supplying a control signal, and driving the pixel by supplying an inspection drive pattern to the selected pixel via the data line (step S22).

  The inspection drive pattern is repeated in units of one cycle. FIG. 9C shows an example of the sine wave of the test drive pattern, which is repeated with one cycle of the shift register signal shown in FIG. 9B or the clock signal of FIG. 9A.

  The current flowing through the pixel by applying the test drive pattern is measured. For example, the measured current value in the first half period of the one-cycle signal is (A), and the measured current value in the second half period is (B). Here, the first half period and the second half period of the periodic signal are divided into periods. However, the present invention is not limited to this, and the period may be arbitrarily divided as long as the voltage application state is different.

  In FIG. 9 (d), the period indicated by the symbol a indicates a measured current value having a waveform similar to the applied inspection drive pattern, and the period indicated by the symbol b indicates that regardless of the applied inspection drive pattern. The measured current value in the cycle shows a predetermined value, and in the cycle marked with the symbol c, the measured current value in the cycle shows 0 regardless of the applied driving pattern for inspection, and in the cycle marked with the symbol d The measured current value having a waveform different from that of the inspection driving pattern is shown.

  The measured current values (A) and (B) can be obtained by sampling the measured current at a predetermined sampling period (points in FIG. 9 (d) indicate sampling points) (step S23).

  Next, it calculates | requires and calculates the difference of the corresponding sampling value of the calculated | required measured electric current value (A) and (B). Here, the periods within one cycle are denoted by A and B, and the measured current values measured during the periods are denoted by () such as (A) to (B).

  FIG. 9E schematically shows the difference (A)-(B) in the measured current value. For example, in the period with the symbol a, a value that decreases within the cycle is calculated as the measured current value difference (A) − (B), and in the period with the symbols b and c, the measured current value difference (A) -A value of 0 is calculated as (B), and a value that decreases within the period is calculated as the measured current value difference (A)-(B) in the period with the symbol d. In the cycle of the symbol d, a gradient smaller than the gradient of the cycle of the symbol a indicates a gradient.

  The difference (A)-(B) between the measured current values (A) and (B) indicates a different value depending on whether the pixel is normal or defective. Therefore, pixel defect determination is performed in the following steps using the measured current value difference (A)-(B) as an index (step S24).

  When the value of the measured current value difference (A)-(B) calculated in step S24 is 0 (step S25), the signal state within the period is the state of period b or period c in FIG. One of the states. Whether it is in the state of the period b or the state of the period c is classified by whether or not the value (A) of the period A is zero.

  When (A)-(B) = 0 and (A) ≠ 0 (step S26), this corresponds to the state of the period b in FIG. 9D, and a white defect in which current always flows through the pixel. (Step S27).

  In step S26, when (A)-(B) = 0 and (A) = 0, black corresponds to the state of period c in FIG. 9D, and no current always flows through the pixel. A defect is indicated (step S28).

  When the value (A)-(B) calculated in step S24 is not 0 (step S25), the signal state in the cycle is either the state of cycle a or the state of cycle d in FIG. is there. Whether it is in the state of the period a or the period d, for example, is classified by the gradient of the measured current value difference (A)-(B), and the waveform of the measured current value is compared with the reference waveform. The pixel leakage defect determination (step S30) or normality determination (step S31) is performed.

  The panel inspection of the organic EL panel can be performed by performing the above steps S22 to S31 for all the pixels of the organic EL panel. FIG. 9F shows the pixel determination result (step S32).

  Hereinafter, a configuration example of the pattern inspection apparatus of the present invention will be described with reference to FIGS. 10 and 11, the organic EL panel 2 has a configuration including RGB pixels.

  The configuration examples in FIGS. 10 and 11 are both configuration examples in which a data line is selected using a shift register, and a test drive pattern is generated using a video signal, and a cycle corresponding to each pixel in the test drive pattern. Give sex. In the configuration in which the inspection drive pattern has periodicity, in FIG. 10, the cycle of the inspection drive pattern is set by a clock signal, and in FIG. 11, the cycle of the inspection drive pattern is set by a shift register signal.

  Each pixel of the organic EL panel includes an organic EL element 2a, an organic EL electrode 2b, and TFTs 2c and 2d. The TFT 2d constitutes a changeover switch means, the output power line 23 is connected to the source, the organic EL electrode 2b is connected to the drain, and the voltage applied from the output power line 23 passes through the organic EL electrode 2b. A drive current is supplied to the organic EL element 2a.

  The current flowing through the organic EL electrode 2b is controlled by the voltage applied to the gate of the TFT 2d. The TFT 2d is controlled by the TFT 2c. The scan signal line 22 from the vertical drive circuit 7 is connected to the gate of the TFT 2c, and the data line 21 from the horizontal drive circuit 5 is connected to the cathode of the TFT 2c. The selection is performed, and the drive current is controlled by the drive signal of the data line 21. In the horizontal drive circuit 5 having the shift register 6 shown in the figure, the pixels are sequentially driven by the shift register signal.

  In addition to the organic EL element cathode / voltage line 24, the organic EL element 2a is connected to a measuring unit 8 for measuring a current flowing through the pixel. The measuring unit 8 measures the current flowing through the organic EL element 2 a and sends the measured current value to the measured current value processing unit 11. The measured current value processing unit 11 determines a defect in the organic EL panel based on the measured current value.

  In the panel inspection apparatus 1 shown in the figure, pixel defect inspection is performed by supplying an inspection drive pattern to a data line.

  The inspection drive pattern output unit 4 generates an inspection drive pattern using the video signal.

  The inspection drive pattern output unit 4 in FIG. 10 generates an inspection drive pattern by turning on / off the video signal in synchronization with the cycle of the clock signal. On the other hand, the test drive pattern output unit 4 in FIG. 11 generates a test drive pattern by turning on / off the video signal in synchronization with the cycle of the shift register output.

  An inspection driving pattern composed of a video signal that is on / off controlled is supplied to a predetermined pixel through a TFT controlled by a shift register output.

  In addition to the organic EL panel of the present invention, it can be applied to inspection of liquid crystal panels.

It is a figure for demonstrating schematic structure of the organic electroluminescent panel inspection apparatus of this invention. It is a flowchart for demonstrating the 1st operation example of the panel inspection apparatus of this invention. It is a signal diagram for demonstrating the 1st operation example of the panel test | inspection apparatus of this invention. It is a state figure in the normal state for demonstrating the 1st operation example of the panel inspection apparatus of this invention. It is a state figure in the white defect state for demonstrating the 1st operation example of the panel inspection apparatus of this invention. It is a state figure in the black defect state for demonstrating the 1st operation example of the panel inspection apparatus of this invention. It is a state figure in the leak defect state for demonstrating the 1st operation example of the panel inspection apparatus of this invention. It is a flowchart for demonstrating the 2nd operation example of the panel inspection apparatus of this invention. It is a signal diagram for demonstrating the 2nd operation example of the panel inspection apparatus of this invention. It is the schematic for demonstrating the structural example of the pattern inspection apparatus of this invention. It is the schematic for demonstrating the structural example of the pattern inspection apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Panel inspection apparatus, 2 ... Organic EL panel, 2a ... Organic EL element, 2b ... Organic EL electrode, 2c, 2d ... TFT, 3 ... Drive circuit, 4 ... Test drive pattern output part, 5 ... Horizontal drive circuit, DESCRIPTION OF SYMBOLS 6 ... Shift register, 7 ... Vertical drive circuit, 8 ... Measurement part, 10 ... Inspection control part, 11 ... Measurement value signal part, 21 ... Data line, 22 ... Scan signal line, 23 ... Output power line, 24 ... Organic EL element cathode and voltage line.

Claims (5)

An inspection drive pattern output unit for outputting an inspection drive pattern to the organic EL panel;
A measurement value processing unit that evaluates the organic EL panel based on a current value flowing through each pixel of the organic EL panel;
The inspection drive pattern is a drive pattern for periodically driving the pixels,
The said measured value process part performs the defect determination of an organic electroluminescent panel based on the difference between the electric current values obtained when the said pixel applies the different voltage within the same period, The panel inspection apparatus characterized by the above-mentioned. An inspection drive pattern output unit for outputting an inspection drive pattern to the organic EL panel;
A measurement value processing unit that evaluates the organic EL panel based on a current value flowing through each pixel of the organic EL panel;
The test drive pattern is a drive pattern for periodically driving the pixels by on / off,
The panel inspection apparatus, wherein the measurement value processing unit determines a defect of the organic EL panel based on a difference between a current value when the pixel is on and a current value when the pixel is off.   The panel inspection apparatus according to claim 2, wherein the inspection drive pattern is formed by turning on / off a video signal. An inspection drive pattern output unit for outputting an inspection drive pattern to the organic EL panel;
A measurement value processing unit that evaluates the organic EL panel based on a current value flowing through each pixel of the organic EL panel;
The inspection drive pattern is a drive pattern for periodically driving the pixels,
The panel inspection apparatus, wherein the measurement value processing unit determines a defect of the organic EL panel by comparing a waveform of a measurement current of the pixel with a reference waveform obtained in advance.   The panel inspection apparatus according to claim 1, wherein the inspection drive pattern is an arbitrary waveform including a triangular wave, a sawtooth wave, a sine wave, and a rectangular wave.

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