JP3836830B2 - Active matrix panel inspection apparatus, active matrix panel inspection method, and active matrix OLED panel manufacturing method - Google Patents

Description

  The present invention relates to an inspection apparatus for an active matrix panel used for organic EL, inorganic EL, and the like, and more particularly to an inspection apparatus for inspecting a pixel electrode by contacting a probe.

  Among display panels, an EL panel using organic EL (Electro Luminescence) or inorganic EL has recently attracted much attention. An EL element is a chemical substance that emits light when energized, and different emission colors can be obtained by changing the chemical structure, and research into use for display panels is underway. Among them, organic EL (hereinafter referred to as OLED (Organic Light Emitting Diode)) emits light by applying a direct current to a fluorescent organic compound excited by applying an electric field, and is thin and has a high viewing angle. In view of wide Gamut, etc., it is attracting attention as a next-generation display device. There are a passive type and an active type for driving the OLED, but the active type is suitable in terms of material, life, and crosstalk in order to realize a large screen and a high-definition display. This active type generally employs a TFT (Thin Film Transistor) drive system.

  Here, an active matrix OLED (AMOLED) and an active matrix liquid crystal display (AMLCD) will be compared and described. FIGS. 21A and 21B are diagrams for comparing and explaining pixel circuits of AMOLED and AMLCD. FIG. 21A shows an AMOLED pixel circuit, and FIG. 21B shows an AMLCD pixel circuit. In FIG. 21B, a TFT array pixel circuit is formed by the TFT 310 connected to the data line (Data) and the gate line (Gate). On the other hand, in the AMOLED shown in FIG. 21A, a driving TFT 302, which is an open / drain drive driving transistor, is connected beside a pixel capacitance of a circuit similar to that shown in FIG. An OLED 301 is connected to the driving TFT 302. The AMLCD shown in FIG. 21B can change the gradation only by generating a voltage in the TFT 310. On the other hand, in the AMOLED, when a predetermined voltage is applied to the driving TFT 302, the luminance of the OLED 301 changes according to the value of the flowing current. The threshold voltage Vth (threshold voltage) of the driving TFT 302 may vary even if the process is adjusted. When there is a variation, even when the same voltage is applied, the flowing current changes, resulting in luminance unevenness. Therefore, in the function inspection of the TFT array for the AMOLED panel, it is important to inspect that the characteristics of the driving TFT 302 for driving the OLED 301 are uniform in the whole panel in addition to the wiring cut (open) / short circuit (short) inspection. This inspection is to confirm that the correction circuit of the driving TFT 302 functions and the Vth of the driving TFT 302 on the panel is uniform.

  Here, in order to reduce the manufacturing cost of the current AMOLED panel, it is required to perform a function test with a single TFT array and to pass only non-defective products to the next process such as an OLED formation process. In the manufacture of AMOLED panels, the yield of the current AMOLED TFT array is not sufficiently high, the material of the OLED 301 itself is expensive, the process occupation time of the OLED 301 formation process is long in the manufacturing process, etc. For reasons, it is desirable to measure the Vth of the drive TFT 302 before mounting the OLED 301. However, in the TFT array alone, the OLED which is a component of the pixel circuit is not mounted, and the driving TFT is in an open drain state. That is, in the process before mounting the OLED, the OLED 301 indicated by the broken line in FIG. 21A is not connected and does not constitute a normal circuit. Accordingly, it is basically impossible to pass a current through the driving TFT 302, and the function test of the Vth correction circuit cannot be performed as it is. In order to inspect such a driving TFT 302, a method of applying a voltage from the outside to an electrode in an open state or a method of dropping the potential of the electrode to GND (ground) is necessary.

  As a conventional technique described in the publication, for example, an inspection method has been proposed in which a TFT array is immersed in an electrolyte liquid and an electrical continuity is applied to apply a voltage (see, for example, Patent Document 1). Further, for example, an inspection method is described in which an inspection conductive film is formed on the pixel electrode before patterning the pixel electrode, and the inspection conductive film is removed after the inspection (see, for example, Patent Document 2). .). Furthermore, although there is no relevance in terms of solving technical problems, there is a technique for inspecting the electrical characteristics of the electrodes by bringing a cylindrical rotary probe into contact with the wiring lead-out portion of the display panel while rotating (for example, , See Patent Document 3).

Japanese Unexamined Patent Publication No. 2002-72918 (page 4-5, FIG. 1) JP 2002-108243 A (page 8-9, FIG. 1) JP-A-63-5377 (page 2-3, FIG. 1)

  However, in the technique described in Patent Document 2, the inspection conductive film is formed by being laminated on the TFT array, and is in close contact with the pixel electrode. For this reason, the load on the TFT array in the process of actually forming the test conductive film on the TFT array and the process of removing it is increased, and the surface of the pixel electrode circuit is likely to be damaged. In the technique described in Patent Document 1, it is necessary to immerse the TFT array in an electrolytic solution, which cannot be said to be realistic.

  In addition, a probe device (prober) is used as a device for making electrical contact when inspecting semiconductor parts. This probe device is in contact with an electrode pad for inspection with a needle such as a thin metal needle or conductive rubber. It is a device to let you. As a probe head in a conventional probe device, for example, a contact probe in which an anisotropic conductive resin is integrally formed by molding has been proposed, for example, there is one that achieves electrical conduction only between upper and lower contact protrusions. To do. In semiconductor component inspection, it is only necessary to make contact with several tens to several hundreds of electrodes, so it is ensured by the elasticity of the spring, the elasticity of the rubber, the tension of the metal needle, or the pressure of the surrounding atmosphere. It is possible to make contact. However, in the case of an AMOLED panel, since it is necessary to make contact with over 100,000 electrodes arranged in a matrix, it is difficult to apply a uniform pressure to all the probes. A device that pressurizes each pixel by independently controlling each inspection needle is also conceivable, but it is still very difficult and expensive to manufacture a device that can handle 100,000 or more pixel electrodes. It becomes. The above-mentioned Patent Document 3 only discloses a technique for pressing a probe against a drawn wiring, and does not directly touch electrodes arranged in a matrix. Therefore, it cannot cope with the problem of inspection in the TFT array for OLED before OLED formation, and cannot be used as a solution to this.

The present invention has been made to solve the above technical problems, and an object of the present invention is to provide an active matrix for inspecting electrical characteristics while directly contacting electrodes arranged in a matrix. It is to provide a panel inspection apparatus.
Another object is to reduce the influence of contact failure even when the probe is in direct contact with the pixel electrode, and to reduce the adverse effect on the pixel electrode due to the contact of the probe.
Still another object is to enable inspection of even a sheet-like substrate that is curved, for example, by pressing a rotating probe to the pixel electrode.
Still another object is to use a plurality of measurement results for pixel circuits arranged in a matrix and perform a test by a statistical method to obtain a highly accurate measurement result that takes into account the characteristics of each factor. .

  For this purpose, the present invention is an inspection apparatus for an active matrix panel for inspecting the characteristics of the active matrix panel before the OLED is formed, and at least the surface is made of a conductive material and is formed on the active matrix panel. A rotating probe that sequentially contacts the pixel electrode while rotating, a voltage applying means that can apply a voltage necessary for measurement to the TFT array in which the rotating probe contacts the pixel electrode, and the voltage applying Current measuring means for measuring the current flowing through the TFT array to which a voltage is applied by the means, and processing means for statistically processing the measurement results sequentially measured by the current measuring means.

  Here, if this processing means is characterized in that the number of measurements for each TFT array by the current measurement means is recorded, it is preferable in that the cause of the abnormality can be easily determined by statistical processing. Further, this rotating probe is excellent in that it can suppress contact failure due to panel bending or the like if it is formed in a roller shape and has irregularities on the surface. Furthermore, the unevenness of the rotary probe can be characterized by having at least one of a square shape, a spherical shape, and a groove shape. Still further, the rotating body probe may be configured in a roller shape so as to be capable of simultaneously contacting a plurality of lines of pixel electrodes.

  On the other hand, the present invention relates to an active matrix panel inspection method for inspecting an active matrix panel before forming an OLED, in which an active matrix is rotated by rotating a rotating body probe controlled so as to function as a power source or a GND. The step of bringing the rotator probe into contact with the pixel electrode of the pixel to be measured in the panel sequentially, the step of scanning the select line for selecting a line in the active matrix panel, and the data line in synchronization with the scan of the select line And a step of observing a current flowing through the driving TFT of the pixel to be measured to which the measurement voltage is applied.

Here, the step of observing the current is characterized in that a measurement value is obtained a plurality of times for one measurement target pixel.
Also, mapping the number of measurements observed in the step of observing the current, and checking for abnormalities in the pixel circuits that make up the active matrix panel and / or abnormalities in the rotating probe using the mapped measurement results And further comprising the step of:
Further, the method may further include a step of detecting an abnormality of the rotator probe by detecting a periodic state depending on the shape of the rotator probe from the observation of the current in the step of observing the current.

  From another point of view, an active matrix panel inspection method to which the present invention is applied includes a step of sequentially bringing a probe into contact with a pixel electrode of a measurement target pixel in the active matrix panel, and a measurement target with which the probe is in contact For a pixel, a step of obtaining a plurality of measurement results for the current flowing through the measurement target pixel, a step of detecting an abnormality from the obtained measurement results of a plurality of times, a statistical processing of the measurement result, and a detected abnormality Determining whether the pixel is due to a defect in the pixel to be measured or a defect in the probe. Here, this determination step outputs a measurement number map in which the number of measurements is matrixed by lines and columns, and the detected abnormality is a periodic abnormality depending on the probe shape by the measurement number map. Further, it can be characterized that it is determined that the probe is abnormal.

  Meanwhile, an active matrix OLED panel manufacturing method to which the present invention is applied includes an array process for forming an active matrix panel by forming a TFT array on a substrate, and an inspection process for performing a function test on the generated active matrix panel. A cell process for mounting an OLED on an active matrix panel determined to be a non-defective product by this inspection process, and the inspection process rotates a rotating probe made of a conductive material to measure pixels in the active matrix panel. In this case, the functional test is performed by sequentially contacting the rotating body probe with the pixel electrodes and observing the current flowing through the measurement target pixel constituting the active matrix panel. Here, in this inspection step, the measurement result of the measurement target pixel constituting the active matrix panel is recorded for each pixel, and the measurement target pixel is inspected while checking the performance of the rotating probe based on the recorded number of measurements. It can be characterized by doing.

  According to the present invention, it is possible to accurately grasp a defect of a pixel electrode with respect to a TFT array substrate (active matrix panel) arranged in a matrix.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a diagram for explaining a configuration of a test apparatus 10 as an inspection apparatus for an active matrix panel (TFT array substrate) to which the present embodiment is applied. The test apparatus 10 includes a storage device (Data Base) 11, a computer (PC) 12, a measurement control circuit (Control Circuits) 13, a signal generation / signal measurement circuit (Drive / sense circuits) 14, a probe (Data probes) 15, a signal. A generation / signal measurement circuit (Drive / sense circuits) 16, a probe (Gate probes) 17, a roller contact probe (Roller Contact Probe) 18, and a probe control circuit (Probe control Circuits) 19 are provided.

  The storage device 11 of the test apparatus 10 stores information necessary for good / bad determination of individual TFT arrays to be inspected and information necessary for measurement. The computer 12 is configured by, for example, a PC or the like, and executes determination processing based on information stored in the storage device 11 based on input data. The measurement control circuit 13 manages the measurement sequence of the inspection method. The signal generation / signal measurement circuits 14 and 16 are analog circuits that generate AMOLED drive signals and acquire a measurement waveform of the TFT array. An integration circuit to be described later is mounted on the signal generation / signal measurement circuits 14 and 16. The probes 15 and 17 supply the AMOLED drive signal generated by the signal generation / signal measurement circuits 14 and 16 to the TFT array to be measured, and acquire a measurement waveform from the TFT array. The roller contact probe 18 is formed of a conductive material that contacts the pixel electrode on the surface of the TFT array panel to be measured while rotating. Further, the probe control circuit 19 controls the operation of the roller contact probe 18 and the power supply voltage supplied to the roller contact probe 18.

  In the present embodiment, by rotating the roller contact probe 18 in the line direction of the active matrix panel, all the pixel electrodes are reliably brought into contact while controlling the contact pressure of the roller contact probe 18, and all The pixel can be inspected. In addition, since the contact probe is formed into a roller shape, the contact with the pixel electrode is simultaneously only for several lines, and the pressure can be easily made uniform. Further, since the contact / peeling is performed while rotating the roller-shaped contact probe 18, the peeling is easy and the load on the pixel electrode can be minimized.

  In the test apparatus 10, the measurement sequence of the inspection method is managed by the measurement control circuit 13, the AMOLED drive signal is generated by the signal generation / signal measurement circuits 14 and 16, and is supplied to the TFT array through the probes 15 and 17. The roller contact probe 18 is managed by a probe control circuit 19, and the probe control circuit 19 is managed by a measurement control circuit 13, and operates in synchronization with a measurement sequence. The measurement waveform of the TFT array is input to the signal generation / signal measurement circuits 14 and 16 through the probes 15 and 17 or input to the roller contact probe 18 and observed. For this purpose, a circuit for current measurement is mounted on the signal generation / signal measurement circuits 14 and 16 or the probe control circuit 19. The observed signal is converted into digital data by the measurement control circuit 13 and input to the computer 12. In the computer 12, measurement data processing and good / bad determination are performed while referring to information stored in the storage device 11. In addition, display and output of data necessary for determination by a statistical method is performed as necessary.

  FIG. 2 is a diagram showing a configuration example of the roller contact probe 18. The roller contact probe 18 functions as means for making contact with the pixel electrode of the TFT array substrate while preventing damage to the TFT array substrate to be measured. For this purpose, a control mechanism such as a pressure mechanism 21, a position control mechanism 22, and a movement mechanism (not shown) is provided for the roller-like contact probe 18. Using such a control mechanism, the roller contact probe 18 is configured to be able to contact the pixel electrode of the TFT array substrate provided on the support base 25. When a conductive rubber or the like is arranged on the entire surface of the TFT array without adopting the structure shown in FIG. 2, it is necessary to apply a uniform pressure over a wide range. In addition, when the conductive rubber or the like is peeled after the TFT array inspection, a vertical tensile force is applied to the pixel circuit surface, and the pixel circuit surface is likely to be damaged. Therefore, as shown in FIG. 2, a roller-like electrode made of a soft and conductive material such as conductive rubber or conductive organic material on the surface of the AMOLED panel (surface on which the OLED connection electrode is exposed). The contact probe 18 is configured to contact. By making the probe into a roller shape, the contact area can be limited to about a few lines of pixels, and contact pressure control can be easily performed. Therefore, the contact resistance between the roller contact probe 18 and the pixel electrode is made uniform. can do. Further, the pixel circuit can be continuously inspected by moving the roller contact probe 18 on the panel while rotating it.

  The pressurizing mechanism 21 shown in FIG. 2 generates pressure using a pressure generating device 21a such as an elastic force or tension such as a spring, a screw type, or a gas pressure. Further, a sensor 21b for measuring the pressure is added, and feedback is applied to the pressure generator 21a so that the pressure is within the reference range. The position control mechanism 22 is composed of position adjustment in the triaxial direction and angle adjustment in the biaxial direction. The size of the AMOLED pixel is a 1: 3 rectangle, depending on the definition, and the short side is about 50 μm to 100 μm. By sufficiently increasing the radius of curvature of the roller contact probe 18, 10 lines can be contacted at the same time. For example, assuming that 10 lines can be contacted at the same time, an allowable angle range of ± 3 degrees can be secured, and a general angle control device can sufficiently cope with this. A larger radius of curvature of the roller surface is desirable. The moving mechanism is a mechanism that simultaneously rotates and moves the roller-like contact probe 18, the pressurizing mechanism 21, the position control mechanism 22, and the like on the substrate. Generally used moving mechanisms such as a screw-in type, a bearing type, and air levitation can be employed. Further, the movement may be performed on the support base 25 side that supports the TFT array substrate.

Here, the roller surface of the roller-shaped contact probe 18 may be a smooth curved surface, but preferably has an uneven surface. If there is an uneven surface, it is possible to prevent contact failure due to bending of the substrate and to reliably contact the pixel electrode.
FIGS. 3A to 3C and FIGS. 4A to 4C are diagrams showing examples of the roller surface of the roller contact probe 18.
FIGS. 3A to 3C show examples of a single uneven shape, and the shape may be either spherical or conical. As the arrangement method, a lattice arrangement shown in FIG. 3A, a staggered arrangement shown in FIG. 3B, a random arrangement shown in FIG. The average distance (pitch) of the unevenness is desirably smaller than the pitch of the pixel electrodes of the AMOLED, and is preferably in the range of 10 μm to 100 μm from the viewpoint of manufacturing accuracy.
FIGS. 4A to 4C show examples of ridge-like projections. As a method of forming the ridge-like projections on the roller surface, for example, there is a linear arrangement shown in FIG. 4A, a diagonal arrangement shown in FIG. 4B, or a curved arrangement shown in FIG. . 3 (a) to 3 (c) and FIGS. 4 (a) to 4 (c) are similarly developed views, and are formed so as to be wound around the roller surface. The pitch of the ridge is preferably smaller than the pitch of the pixel electrodes of the AMOLED, and is preferably in the range of 10 μm to 100 μm from the viewpoint of manufacturing accuracy.

Next, a circuit example used for current measurement will be described.
FIGS. 5A to 5D are diagrams showing circuit examples that can be used for current measurement. For example, the circuit is mounted on the signal generation / signal measurement circuits 14 and 16 or the probe control circuit 19. 5A is a charge integration circuit that performs measurement by connecting to the GND wiring, FIG. 5B is a charge integration circuit that performs measurement by connecting to the power supply wiring, and FIG. 5C is connected to the GND wiring. FIG. 5D shows a current measurement circuit for performing measurement by connecting to the power supply wiring.
The integrating circuit shown in FIGS. 5A and 5B includes an operational amplifier 31, a capacitor Ci, and a reset switch SWreset. The operation of the integration circuit is also detailed in US Pat. No. 5,179,345. The current measurement circuit shown in FIGS. 5C and 5D is provided with a small resistance R for current monitoring in addition to the operational amplifier 31. Outputs from the integration circuits and current measurement circuits shown in FIGS. 5A to 5D are converted into digital data by an A / D conversion circuit provided in the measurement control circuit 13 shown in FIG. .

Next, an actual inspection method will be described.
6A to 6D are diagrams illustrating pixel circuit examples to be inspected. FIG. 6A shows a 2-TFT configuration voltage programming circuit by Brody, which is currently the mainstream configuration. FIG. 6B shows a 4-TFT configuration voltage programming circuit with a Vth correction function by Dawson. FIG. 6C shows a 4 TFT configuration current programming circuit with a Vth correction function by Dawson, and FIG. 6D shows a current mirror type 4 TFT configuration current programming circuit. Each pixel circuit can have both n-channel and p-channel configurations as types of drive TFTs. In the various pixel circuits shown in FIGS. 6A to 6D, driving TFTs indicated by T2 (n) or T2 (p) are used, and pixel electrodes are connected.

  This pixel electrode is connected to the drain or source of the driving TFT. When an OLED is formed, an anode or a cathode is disposed opposite to the pixel electrode, and the driving TFT can pass a current through the OLED. By bringing the roller-shaped contact probe 18 into contact with the pixel electrode, the roller-shaped contact probe 18 can be used in place of the electrode opposed to the OLED. In the case of FIG. 6A, the roller contact probe 18 is electrically controlled so as to serve as a power source. In the case of FIGS. 6B to 6D, the roller contact probe 18 is electrically controlled so as to function as GND.

With reference to the pixel circuit shown in FIG. 6A as an example, the electrical characteristic inspection of the driving TFT in this embodiment will be described.
FIG. 7 is a diagram showing a state where the pixel electrode is contacted by the roller contact probe 18 and the power (Vdd) is supplied. The select line (Select) is driven for the line in contact with the roller contact probe 18, and the pixel selection TFT (T1) is turned on. In this state, by applying a video voltage to the data line (Data), the gate-source voltage (Vgs) of the driving TFT (T2) is set. Since the power (Vdd) is supplied to the drain electrode of the driving TFT (T2) by the pixel selection TFT (T1), the drain-source voltage (Vds) of the driving TFT (T2) is determined. At this time, if a circuit (for example, an integration circuit or a current measurement circuit shown in FIGS. 5A to 5D) that can measure a current is connected to the roller contact probe 18 or the GND wiring on the TFT array, the driving is possible. The drain-source current (Id) of the TFT (T2) can be measured.

  FIG. 8 is a diagram showing a Vgs-Id curve (characteristic curve) obtained by measuring a drain-source current (Id) for a plurality of gate-source voltages (Vgs). The same measurement is possible with the pixel circuits shown in FIGS. 6B to 6D in which the horizontal axis represents the gate-source voltage (Vgs) and the vertical axis represents the drain-source current (Id). FIG. 8 also shows the measurement result of the pixel circuit with the Vth correction function.

FIG. 9 is a diagram showing a specific curve with the square root of Id on the vertical axis with respect to the Vgs-Id curve obtained as shown in FIG. By taking the square root of the drain-source current (Id), a curve as shown in FIG. 9 is obtained, and Vth and β of the driving TFT can be easily obtained. That is, the gate-source voltage (Vgs) at which the linear portion of the characteristic crosses Id = 0 is Vth, and the slope of the linear portion of the characteristic is (0.5) ^1/2 . In the inspection, by obtaining Vth and β for the driving TFT of each pixel, it becomes possible to determine the variation in electrical characteristics and the good / bad determination of the driving TFT.

FIG. 10 is a flowchart showing a flow of inspection to which the present embodiment is applied.
First, at the time of inspection, the roller contact probe 18 to which a circuit for current measurement is connected is disposed near the measurement start line of the panel to be measured (step 101). Thereafter, the roller contact probe 18 moves (step 102). The moving speed of the roller contact probe 18 is set smaller than the scanning speed of the select line. At this time, a start pulse is input to the select line driver circuit, and the select line is scanned (step 103). This start pulse is input at intervals exceeding the number of lines that the roller contact probe 18 contacts simultaneously. In addition, a measurement voltage is applied to the data line in synchronization with this select line scan (step 104).

  After the roller contact probe 18 comes into contact with the measurement start line, current measurement is performed until the measurement for all the pixel circuits is completed. That is, for example, the measurement control circuit 13 which is an inspection apparatus performs measurement current observation using a circuit for measurement current as shown in FIGS. 5A to 5D (step 105). For example, the measurement control circuit 13 which is an inspection device stores the measurement current value of each pixel circuit, counts the number of times the current measurement is performed in each pixel circuit, and maps the number of measurements (described later) (see below). Step 106). Then, the current measurement state of a plurality of times is grasped for each pixel circuit from the created measurement frequency map (step 107). The measurement control circuit 13 determines whether or not a plurality of current measurements have been completed for all pixel circuits (step 108). If all of them are not completed, the process returns to step 102, and the operation of inputting the start pulse to the select line driver circuit is repeated while moving the roller contact probe 18. If the measurement of all lines is completed in step 108, the measurement ends. In the above inspection flow, since the select line driver circuit (signal generation / signal measurement circuits 14 and 16) is generally constituted by a shift register, there is no problem even if a plurality of start pulse inputs are performed. Even when a plurality of select lines on the panel (TFT array substrate) are driven, the fact that current flows only in the pixel circuit in contact with the roller contact probe 18 is utilized.

Next, detection of contact failure will be described.
FIG. 11 is a view showing a state in which the roller contact probe 18 is correctly in contact with the pixel electrode. In the case where a large number of pixel electrodes are simultaneously contacted by the roller contact probe 18, as shown in FIG. 11, it is ideal that all the pixel electrodes in the inspection target line can be contacted. In the example shown in FIG. 11, the roller contact probe 18 is arranged in parallel to the line in which the pixel electrodes are arranged, and the contact surface of the roller contact probe 18 is not damaged. Here, in order to simplify the description, the columns are 0 to 29, and the lines are 0 to 5.

  FIGS. 12A to 12G are views for explaining the flow of the roller contact probe 18 and the flow of inspection in the case shown in FIG. In each of the drawings (a) to (g), the diagram on the left side shows the contact area of the roller contact probe 18. Here, lines (0 to 5) are shown in the vertical direction, and columns (0 to 14) are shown in the horizontal direction. The center figure shows a state in which the panel and the roller contact probe 18 are viewed from the side. The chart on the right side shows an example of the measurement frequency map generated by the measurement control circuit 13, for example, the horizontal direction of the chart indicates the column number, and the vertical direction indicates the line number. This number-of-measurements map shows the number of times current measurement has been performed in each pixel circuit. 12A to 12G show a case where the roller contact probe 18 can contact two lines at the same time.

  FIG. 12A shows a state in which the measured current on line 0 is observed and the measured current is not observed on line 1. This state means that the roller contact probe 18 is arranged on the measurement start line. While moving the roller contact probe 18, a start pulse is input to the select line driver circuit. As shown in FIG. 12B, the second measurement of line 0 and the first measurement of line 1 are completed. Further, the operation of inputting the start pulse to the select line driver circuit is repeated while moving the roller contact probe 18. 12C, the second measurement of line 1 and the first measurement of line 2 are completed. In FIG. 12D, the second measurement of line 2 and the first measurement of line 3 are performed. In the completed state, in FIG. 12 (e), the second measurement of line 3 and the first measurement of line 4 are completed, in FIG. 12 (f), the second measurement of line 4 and 1 of line 5 are completed. The state where the second measurement is completed is shown. And as shown in FIG.12 (g), the measurement of all the lines is completed by completing the 2nd measurement of the line 5. FIG. When the measurement of all the lines is completed, if there is a pixel whose measurement value is not a preferable value, it can be determined that the pixel is abnormal.

  The tables (maps) shown in the right diagrams of FIGS. 12A to 12G are displayed on, for example, a display (not shown) provided in the computer 12 of the test apparatus 10 shown in FIG. Is done. In addition, if there is an abnormality when displayed, it is possible for the person in charge of the inspection to easily determine if only the abnormal part is highlighted.

  FIG. 13 is a diagram showing an example in which a damaged portion 18a is present at a part of the contact surface of the roller contact probe 18, and the damaged portion 18a is not correctly in contact with the pixel electrode. In FIG. 13, as in FIG. 11 and the like, the horizontal axis indicates the column, the vertical axis indicates the line, and the roller contact probe 18 is moved on the second line. In the example shown in FIG. 13, the columns 5 and 6 in the line 2 are not correctly in contact. When the contact is not made correctly, current does not flow through the driving TFT when the pixel circuit is inspected, so that the inspection device regards the pixel circuit as defective. Even in this case, the present embodiment is characterized in that the inspection apparatus can detect that a contact failure has occurred.

  FIGS. 14A to 14G are views for explaining the flow of the roller contact probe 18 and the flow of inspection in the case shown in FIG. The arrangement of each figure is the same as in FIG. 12, and a description thereof will be omitted. When the processing proceeds according to the above-described inspection flow, the broken portion 18a of the roller-shaped contact probe 18 as shown in FIG. 13 causes the column 1 and the column in the line 0 (0th row) in the example shown in FIG. 2 cannot contact correctly. For this reason, as shown in FIG. 14A, the column 1 of the line 0 (0th column) and the column 2 of the line 0 cannot be measured correctly. Even when the roller contact probe 18 moves to the position shown in FIG. 14B and the number of times of measurement is stored twice in the line 0, the column 1 of the line 0 and the column 2 of the line 0 are “0”. It remains. Similarly, as shown in FIGS. 14 (e) and 14 (f), the damaged portion 18a causes a portion in which the column 1 of the line 4 and the line 4 column 2 cannot be measured correctly. As described above, when there is a damaged portion in the roller-shaped contact probe 18, it is possible to detect a periodic defective portion corresponding to the roller diameter on the measurement number map. That is, as shown in FIG. 14G, when a defective portion is detected at a position that is a period of the outer peripheral length of the roller in the rotation direction of the roller contact probe 18, the roller contact probe 18 has an abnormality. And can be distinguished from measurement failures due to failure of the pixel circuit. It should be noted that this abnormality detection is easy for the examiner to judge by looking at the table displayed on the display or the like. For example, the computer 12 shown in FIG. It is also possible to configure so that the cause of the error is displayed and output.

  FIG. 15 shows a case where the TFT array substrate, which is the object to be measured, is arranged obliquely with respect to the roller contact probe 18. In the example shown in FIG. 15, the columns 27 to 29 in the line 2 cannot contact the roller contact probe 18 due to the installation angle deviation between the roller contact probe 18 and the TFT array substrate. Further, the columns 19 to 26 in the line 2 may not be in contact with each other.

  FIGS. 16A to 16G are views for explaining the flow of the movement and inspection of the roller contact probe 18 in the case shown in FIG. The arrangement of each figure is the same as in FIG. 12, and a description thereof will be omitted. When the processing proceeds according to the above-described inspection flow, for example, in FIG. 16 (a), only the columns 10 to 14 of the line 0 are correctly in contact with each other due to the installation angle shift, and the output is output only to that portion in the measurement frequency map. You can observe the appearance. In FIG. 16B, two measurements can be observed in the columns 9 to 14 of the line 0, and one measurement can be observed in the columns 0 to 8 of the line 0 and the columns 9 to 14 of the line 1. In FIG. 16 (c), two measurements can be observed for all the pixels on line 0 and on columns 9 to 14 on line 1, and once on columns 0 to 8 on line 1 and columns 9 to 14 on line 2 The measurement is observable. Similarly, in FIG. 16D, two measurements can be observed in all the pixels in lines 0 and 1, and in columns 9-14 in line 2, and in columns 0-8 in line 2, columns 9-9 in line 3. 14 measurements can be observed once. In FIGS. 16 (e) to 16 (g), the lines are similarly shifted and observed. Finally, when the roller contact probe 18 and the TFT array substrate are in the state as shown in FIG. 16 (h), the measurement number map stores that all measurements were performed twice. ing. In other words, even if there is a deviation in the installation angle between the roller contact probe 18 and the TFT array substrate, if the roller contact probe 18 has a length that can cover the entire diagonal direction of the TFT array substrate, the measurement will be hindered. I can understand that there is no. Thus, according to the present embodiment, precise control for adjusting the installation angle is not necessary.

Next, an example of a TFT array substrate to be measured and a driving waveform for inspecting each pixel will be described.
FIG. 17 is a diagram in which pixel circuits having a basic 2-TFT configuration are arranged. The roller contact probe 18 is in contact with the pixel electrode 41 where an OLED is to be formed in a later process, and acts as a power source. In the example shown in FIG. 17, the current measurement is performed by the roller contact probe 18. In FIG. 17, three select lines 42 of Select1 to Select3 and three data lines 43 of Data1 to Data3 are shown. Here, the case where the roller contact probe 18 moves from the line 1 (Line 1) to the line 3 (Line 3) direction will be described.

  FIG. 18 is a diagram showing drive waveforms for inspecting each pixel with respect to the arrangement of FIG. “RCP Position” in the figure indicates the position (line) of the pixel electrode 41 in contact with the roller contact probe 18. With the roller contact probe 18 mounted on the TFT array substrate shown in FIG. 17, the roller contact probe 18 moves in the direction from line 1 to line 3 while rotating in synchronization with line scanning. The roller contact probe 18 moves at a speed that is one third of the scanning speed of the select line 42. In the sequence 00 to 12, only the line 1 is in contact. Sequences 13 to 24 show a state in which line 1 and line 2 are in contact with each other. Further, the sequences 25 to 36 show a state in which the line 2 and the line 3 are in contact with each other. When the roller contact probe 18 is positioned on the line 1, the first measurement is performed on the columns 1, 2, and 3 of the line 1 by activating Data 1 to Data 3 of the data line 43 in the sequence 01 to 03. In sequence 13 to 15, the second measurement of the columns 1, 2, and 3 in line 1 is performed. When the roller contact probe 18 is positioned on the line 2, the first measurement of the columns 1, 2, 3 of the line 2 is performed in sequences 17 to 19, and the columns 1, 2 of the line 2 are detected in sequences 29 to 31. , 3 is measured for the second time. Thereafter, the pixel circuits in each line are similarly inspected. As described above, measurement can be performed twice for each column as shown in FIG.

  In FIG. 19, as another embodiment, two roller-like contact probes 18 are provided, and together with the two roller-like contact probes 18, an opposing roller 51 that sandwiches a TFT array substrate that is a substrate to be inspected is provided. Yes. A cleaning roller 52 for cleaning the rollers is connected between the two roller contact probes 18 and the two opposing rollers 51. Further, a panel cleaning roller 53 for cleaning the panel surface is provided on the upstream side in the transport direction of the TFT array substrate. In the example shown in FIG. 19, the TFT array substrate is rotated and moved by the two panel cleaning rollers 53, the roller-shaped contact probe 18 and the opposing roller 51. In the above-described embodiment, the TFT array substrate and the roller contact probe 18 are relatively moved. As a method of the movement, in addition to the form in which the roller contact probe 18 moves on the TFT array substrate, There is a form in which the TFT array substrate moves. In FIG. 19, the state in which the TFT array substrate moves is indicated by arrows. In the example shown in FIG. 19, the TFT array substrate is supported and pressed simultaneously. As shown in FIG. 19, by installing a plurality of roller-like contact probes 18 at the same time, it becomes possible to inspect in parallel.

Finally, the manufacturing process of the OLED panel will be described.
FIG. 20 is a diagram for explaining a manufacturing process of the OLED panel to which the present embodiment is applied. The manufacturing method of the OLED panel to which this embodiment is applied includes an array process 1 for generating an active matrix panel in which a TFT array, which is an OLED drive circuit, is formed, and a function test is performed on the generated active matrix panel alone. An inspection process 2 is included. In this inspection process 2, an inspection is performed by the above-described inspection apparatus and inspection method to confirm that the open / short of the wiring is below a predetermined condition and that the TFT characteristics are uniform throughout the panel. The active matrix panel that is determined to be a defective product in this inspection process 2 is eliminated without shifting to the next process. For an active matrix panel that is determined to be a non-defective product, a cell process 3 for forming an OLED on the TFT array is followed by a final inspection process 4. By this final inspection process 4, finally, a non-defective product and a defective product are sorted. In the present embodiment, by providing the inspection process 2 before the cell process 3, it is possible to eliminate an active matrix panel having a large variation in driving TFT before mounting the OLED. Examples of the inspection target include various AMOLED panels in addition to an active matrix (AM) panel used for a display screen such as a PHS or a mobile phone.

  As described above in detail, according to the present embodiment, a TFT array that is not mounted with an OLED can be efficiently inspected while minimizing a load caused by contact and applying a uniform pressure. Is possible. Since the current can flow directly from the roller contact probe 18, the characteristic inspection (threshold voltage Vth, characteristic parameter β, pixel capacitance value, or leak inspection) regarding the driving TFT in the pixel circuit can be reliably performed. By performing such a characteristic inspection for all the pixels of the panel, it is possible to obtain variations within the panel, and it is possible to determine whether the panel is good or defective using this result. Thereby, the outflow amount of the defective active matrix panel to the next process can be greatly reduced, and the panel manufacturing cost can be reduced. Also, at the panel development stage, the development period can be shortened by using this test apparatus for fault diagnosis.

  Furthermore, according to the present embodiment, since the measurement is performed while creating the measurement frequency map, the contact position of the roller contact probe 18 can be detected through the measurement. Thereby, the position control device of the roller contact probe 18 can be simplified, and the pixel position where the contact failure has occurred can be detected. Also, by taking statistical data by using this measurement number map, if an undesirable result is obtained as a measurement result, whether the cause is in the pixel electrode itself or whether the probe is affected. It becomes possible to recognize. When the probe is affected, it is easy to perform a normal inspection by cleaning, repairing, or replacing the probe. Furthermore, when conducting measurement with conductive rubber disposed on the entire pixel area, only one select line 42 must be driven at all times. This is because when a plurality of select lines 42 are simultaneously driven, currents from a plurality of pixels are measured. According to the present embodiment, only a few lines are simultaneously contacted by the roller-shaped contact probe 18, and only one select line is required to be driven in this region. Therefore, since it is not necessary to wait for the time when the shift register of the select line driver circuit is washed out, the measurement time can be shortened.

  In this embodiment, the cylindrical roller-shaped contact probe 18 is used as the rotating probe, but a probe made of another rotating member such as a sphere can be used. When a rotating body probe made of a sphere is used, for example, even a film-like display device that is curved is preferable in that it can be easily measured by contacting the pixel electrode.

  As an application example of the present invention, an active matrix panel inspection apparatus for mounting an EL element, an inspection method, and application to a display panel on which the EL element is mounted can be considered.

It is a figure for demonstrating the structure of the test apparatus as an inspection apparatus of the active matrix panel (TFT array substrate) to which this Embodiment is applied. It is the figure which showed the structural example of the roller-shaped contact probe. (a)-(c) is the figure which showed the example of the roller surface of a roller-shaped contact probe. (a)-(c) is the figure which showed the example of the roller surface of a roller-shaped contact probe. (a)-(d) is the figure which showed the example of a circuit which can be used for an electric current measurement. (a)-(d) is the figure which showed the pixel circuit example used as test object. It is the figure which showed the state which contacted the pixel electrode with the roller-shaped contact probe and the power supply (Vdd) was supplied. It is the figure which showed the Vgs-Id curve (characteristic curve) calculated | required by measuring the drain-source current (Id) about several gate-source voltage (Vgs). It is the figure which showed the specific curve by taking the square root of Id on the vertical axis | shaft with respect to the Vgs-Id curve calculated | required like FIG. It is the flowchart which showed the flow of the test | inspection to which this Embodiment is applied. It is the figure which showed the state in which the roller-shaped contact probe has contacted the pixel electrode correctly. (a)-(c) is a figure for demonstrating the flow of a roller-shaped contact probe in the case shown in FIG. 11, and the flow of a test | inspection. (d)-(f) is a figure for demonstrating the flow of a roller-shaped contact probe in the case shown in FIG. 11, and the flow of a test | inspection. (g) is a figure for demonstrating the flow of a movement and test | inspection of a roller-shaped contact probe in the case shown in FIG. It is the figure which showed the example which has a damaged part in a part of contact surface of a roller-shaped contact probe, and has not correctly contacted the pixel electrode in the damaged part. (a)-(c) is a figure for demonstrating the flow of a roller-shaped contact probe in the case as shown in FIG. 13, and the flow of a test | inspection. (d)-(f) is a figure for demonstrating the flow of a roller-shaped contact probe in the case as shown in FIG. 13, and the flow of a test | inspection. (g) is a figure for demonstrating the flow of a roller-shaped contact probe in the case as shown in FIG. 13, and the flow of a test | inspection. This shows a case where the TFT array substrate, which is the object to be measured, is arranged obliquely with respect to the roller-shaped contact probe. (a)-(c) is a figure for demonstrating the flow of a roller-shaped contact probe in the case shown in FIG. 15, and the flow of a test | inspection. (d)-(f) is a figure for demonstrating the flow of a roller-shaped contact probe in the case shown in FIG. 15, and the flow of a test | inspection. (g), (h) is a figure for demonstrating the flow of a roller-shaped contact probe in the case shown in FIG. 15, and the flow of a test | inspection. It is the figure which arranged the pixel circuit of a basic 2TFT structure. It is the figure which showed the drive waveform for test | inspecting each pixel with respect to the arrangement | sequence of FIG. It is the figure which showed an example of other embodiment. It is a figure for demonstrating the manufacturing process of the OLED panel to which this Embodiment is applied. (a), (b) is a figure for comparing and explaining the pixel circuit of AMOLED and AMLCD.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Array process, 2 ... Inspection process, 3 ... Cell process, 4 ... Final inspection process, 10 ... Test apparatus, 11 ... Memory | storage device (Data Base), 12 ... Computer (PC), 13 ... Measurement control circuit (Control Circuits) ), 14 ... Signal generation / signal measurement circuit (Drive / sense circuits), 15 ... Probe (Data probes), 16 ... Signal generation / signal measurement circuit (Drive / sense circuits), 17 ... Probe (Gate probes), 18 ... Roller contact probes, 19 ... Probe control circuits, 21 ... Pressure mechanism, 22 ... Position control mechanism, 25 ... Support base

Claims (14)

An active matrix panel inspection device for inspecting the characteristics of an active matrix panel before forming OLED (Organic Light Emitting Diode),
A rotating body probe having at least a surface made of a conductive material and sequentially contacting a pixel electrode formed on the active matrix panel while rotating;
Voltage applying means capable of applying a voltage required for measurement to the TFT array in which the rotating probe is in contact with the pixel electrode;
An inspection apparatus for an active matrix panel, comprising: current measuring means for measuring current flowing through the TFT array to which a voltage is applied by the voltage applying means.   2. The inspection apparatus for an active matrix panel according to claim 1, further comprising processing means for statistically processing measurement results sequentially measured by the current measuring means.   3. The inspection apparatus for an active matrix panel according to claim 2, wherein the processing means records the number of measurements for each TFT array by the current measuring means.   2. The inspection apparatus for an active matrix panel according to claim 1, wherein the rotating body probe is formed in a roller shape and has an uneven surface.   5. The inspection apparatus for an active matrix panel according to claim 4, wherein the unevenness of the rotary probe has at least one of a square shape, a spherical shape, and a groove shape.   2. The inspection apparatus for an active matrix panel according to claim 1, wherein the rotating body probe is formed in a roller shape and is configured to be able to contact a plurality of lines of pixel electrodes at the same time. An active matrix panel inspection method for inspecting an active matrix panel before forming OLED (Organic Light Emitting Diode),
Rotating a rotating probe controlled to act as a power source or GND electrically, and sequentially contacting the rotating probe to a pixel electrode of a measurement target pixel in the active matrix panel;
Scanning select lines for selecting lines in the active matrix panel;
Applying a measurement voltage to the data line in synchronization with the scan of the select line;
Observing a current flowing through a driving TFT (Thin Film Transistor) of the measurement target pixel to which the measurement voltage is applied, and an inspection method for an active matrix panel.   8. The method of inspecting an active matrix panel according to claim 7, wherein the step of observing the current obtains a plurality of measurement values for one measurement target pixel. Mapping the number of measurements observed by observing the current;
The method for inspecting an active matrix panel according to claim 8, further comprising the step of confirming an abnormality of a pixel circuit constituting the active matrix panel and / or an abnormality of the rotating body probe using the mapped measurement result.   The active state according to claim 7, further comprising a step of detecting an abnormality of the rotating body probe by detecting a periodic state depending on a shape of the rotating body probe from observation of the current in the step of observing the current. Matrix panel inspection method. An active matrix panel inspection method for inspecting an active matrix panel before forming OLED (Organic Light Emitting Diode),
Sequentially bringing a rotating probe into contact with a pixel electrode of a measurement target pixel in the active matrix panel;
Obtaining the measurement results for a plurality of times with respect to the current flowing through the measurement target pixel, with respect to the measurement target pixel in contact with the rotating body probe;
Detecting an abnormality from the plurality of measurement results obtained;
An active matrix panel inspection method comprising: statistically processing measurement results and determining whether a detected abnormality is due to a defect in the pixel to be measured or a defect in the rotating probe. The determining step outputs a measurement frequency map in which the measurement frequency is matrixed by lines and columns, and the detected abnormality is a periodic abnormality depending on the shape of the rotating probe by the measurement frequency map. In this case, it is determined that the rotating probe is abnormal. An array process for forming an active matrix panel by forming a TFT (Thin Film Transistor) array on a substrate;
An inspection process for performing a functional inspection of the generated active matrix panel;
A cell process for mounting an OLED (Organic Light Emitting Diode) on an active matrix panel determined to be a non-defective product by the inspection process,
In the inspection step, a rotating body probe made of a conductive material is rotated so that the rotating body probe is sequentially brought into contact with a pixel electrode of a pixel to be measured in the active matrix panel, and the measuring object constituting the active matrix panel A method of manufacturing an active matrix OLED panel, wherein a function test is performed by observing a current flowing through a pixel. The inspection step records the measurement result of the measurement target pixel constituting the active matrix panel for each pixel, and confirms the performance of the rotating body probe based on the recorded measurement result . The method of manufacturing an active matrix OLED panel according to claim 13, wherein an inspection is performed.

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