JP2014202907A - Planar display device and inspection method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a short-circuit of wirings arrayed in a matrix such as the short-circuit among sensor wirings to be easily detected and particularly to simplify a structure of an inspection device in a planar display device and the inspection device of the same.SOLUTION: Each sensor 11 in a wiring group 22 is made conductive to one inspection pad 27 through a switching element 25 provided on its end part, respectively. Further, an odd-numbered sensor wiring 11A only or an even-numbered sensor wiring 11B only can be made conductive to the inspection pad 27 by the first/second switching control wirings 23, 24 for turning on/off these switching elements 25. In order to inspect the short-circuit among adjacent wirings, first of all, the odd-numbered sensor wiring 11A only is made conductive to the inspection pad 27 to be applied with a voltage. Then, the even-numbered sensor wirings 11B only are made conductive to the inspection part 27 to measure a discharge current.

Description

  The present invention relates to a flat display device and an inspection method thereof. In particular, the present invention relates to an active matrix liquid crystal display device having a touch panel function (contact detection function) and an inspection method thereof.

  An active matrix liquid crystal display device, which is the most typical flat display device, includes a liquid crystal display panel including a pair of substrates facing each other and a liquid crystal layer sandwiched between the pair of substrates. The pixel dots are arranged in a matrix. One of the pair of substrates is an array substrate, and a switching element is provided for each pixel dot, and scanning lines arranged along a matrix row in which the pixel dots are arranged and along a matrix column And disposed signal lines. The alignment state of the liquid crystal molecules contained in the liquid crystal layer is controlled by an electric field applied to the liquid crystal layer.

  In particular, a liquid crystal display panel of a horizontal electric field method such as an IPS (In-Plane Switching) method or an FFS (Fringe Field Switching) method generally has a plurality of first electrodes arranged for each pixel dot on an array substrate. (Pixel electrode) and a second electrode (common electrode) opposite to the plurality of first electrodes, and liquid crystal molecules contained in the liquid crystal layer by a lateral electric field generated between the first electrode and the second electrode. Control the orientation state. A horizontal electric field liquid crystal display panel has excellent features such as a wide viewing angle and low power consumption, and is widely applied to display applications such as televisions and mobile phones.

  In particular, in recent years, the market demand for providing a user interface for improving operability on the display surface is increasing, and products having a touch panel function on the display surface of the liquid crystal display panel are spreading to the market. For example, according to Patent Literature 1, contact sensing elements for realizing a touch panel function are integrally formed on a liquid crystal display panel, and the sensor wirings in the row direction and the column direction are arranged in a matrix (lattice). Formed without additional wiring. That is, the common electrode wiring formed by connecting the common electrodes in the row direction of the matrix also serves as the sensor wiring in the row direction, and the signal line also serves as the sensor wiring in the column direction (FIGS. 2-3 and FIG. 8-9). In addition, one frame period includes a “pixel display mode” period and a shorter “detection mode” period (FIG. 10).

  On the other hand, Patent Document 2 describes an array substrate provided with an inspection pad and wiring, and an inspection method thereof. Specifically, it describes that the probe is brought into contact with the inspection pad to charge the pixel electrode, and the inspection is performed by irradiating the pixel electrode with an electron beam and detecting secondary electrons (FIGS. 10 to 11). ing. In addition, there is also described that a plurality of signal lines are connected to one inspection pad via a switching circuit (FIG. 9).

JP2011-137882A JP 2009-069643

  The present invention can easily detect a short circuit between wires arranged in a matrix, such as a short circuit between sensor wires, in the flat display device and the inspection method thereof, and in particular, to simplify the configuration of the inspection device. It is to provide what can be done.

  The flat display device of the present invention includes row-direction wirings and column-direction wirings arranged in a matrix-like row direction and column direction in which pixel dots are arranged in the display region, and is drawn out of the display region. A switching element is provided for each end portion of these wirings, and one wiring group formed by the row-direction wiring or the column-direction wiring is electrically connected to one inspection pad through the switching element for each wiring. Are connected to the one test pad only when the switching element is switched to the conductive state through the first switching control wiring, and the even-numbered wiring in the wiring group is connected to the second wiring. Only when the switching element is switched to the conducting state through the switching control wiring, the one testing pad is conducted.

  The inspection method for a flat panel display device according to the present invention is to first check whether there is a short circuit between adjacent row direction wirings or column direction wirings in the above flat display device. By supplying a potential for turning on the switching element only to one side, the odd-numbered or even-numbered wiring in the one wiring group is made conductive with the one inspection pad, and then a voltage is applied to these wirings. Then, by supplying a potential that makes the switching element conductive only to the other of the first and second switching control wirings, the other wirings in the one wiring group are electrically connected to the one inspection pad. In addition, the discharge current from the other wiring is measured.

  The number of probes of the inspection apparatus can be reduced. Further, as in the case where a pair of probes is used for each wiring group, it is possible to prevent the yield from being deteriorated due to misidentification and the display unevenness due to residual charge due to the failure of one probe.

It is a fragmentary top view which shows typically the principal part of the flat display apparatus which becomes one embodiment of this invention. An inspection apparatus and its probe are also shown schematically. It is a typical lamination | stacking cross-section perspective view about the flat display apparatus of FIG. The thickness is greatly exaggerated, and the FPC is not folded. FIG. 2 is a schematic plan view corresponding to FIG. 1, showing a lighting inspection state in the flat display device of FIG. 1. FIG. 2 is a schematic plan view corresponding to FIG. 1, showing a state of a short circuit inspection between adjacent wirings in the flat display device of FIG. 1. The left and right parts show the stages of voltage application and discharge current measurement, respectively. FIG. 4 is a schematic plan view corresponding to FIG. 3, showing a lighting inspection in a flat display device of a comparative example. FIG. 6 is a schematic plan view corresponding to FIG. 3, illustrating a state of a short circuit inspection between adjacent wirings in the flat display device of FIG. 5. FIG. 6 is a schematic plan view corresponding to FIG. 5 for describing the occurrence of an inspection failure due to a contact failure of one probe in the flat display device of FIG. 5.

  A flat display device and a driving method thereof according to an embodiment of the present invention will be described with reference to FIGS. Here, the flat display device is described as being composed of a liquid crystal display panel, but depending on the case, it may be composed of another matrix display device such as an organic EL display panel.

  As shown in FIG. 2, the flat display device 10 includes a liquid crystal display panel 1 having a touch panel function and a driving IC 19 at the periphery, a control unit 3 including a computer having a processor and a memory, a battery 4, and the like. The surface light source device 5 is provided in a single flat casing (not shown). The controller 3 includes a controller for the liquid crystal display panel 1 in a controller IC or other form.

  In the illustrated example, the liquid crystal display panel 1 is a transmission type or a semi-transmission type, and the polarizing plate 18 is provided on the front side and the back side, but may be a reflection type. The drive IC 19 is usually mounted on a shelf-like connection portion 16A along one or more sides of the liquid crystal display panel 1 together with a flexible printed circuit board (FPC) 19A, which are collected into one or more drive IC chips. . The shelf-like connection portion 16 </ b> A is a portion where the array substrate 16 protrudes from the counter substrate 17.

  In the present embodiment, the liquid crystal display panel 1 is configured in the same manner as described in Patent Document 1 above. In the display area of the liquid crystal display panel 1, pixel dots are arranged in a matrix, and each pixel dot is provided with a TFT element 14 as shown in the enlarged portion in FIG. The electrodes are connected to the signal line 12 and the scanning line 13, respectively. The pixel electrode 15 connected to the drain electrode of the TFT element 14 faces the common electrode (counter electrode) 11C through the liquid crystal layer.

  The common electrode 11C of each pixel dot is connected to each other in the direction of the scanning line 13 to form an electrode line, and this electrode line also serves as the first sensor wiring 11 for contact detection. The signal line 12 also serves as a second sensor wiring for contact detection. Each frame period (16.6 ms in the case of 60 Hz driving) is divided into an image signal writing period and a contact detection period of about 1/3 to 1/4. During the image signal writing period, an image signal potential is written to each pixel electrode 15 from the source driver portion of the driving IC 19 via the signal line 13 and the TFT element 14. Further, during the contact detection period, the contact of the fingertip or the pen tip is detected through the first and second sensor wires 11 and 12. Needless to say, each first sensor wiring 11 is a sensor wiring in the row direction extending in one direction (row direction of the matrix) in which pixel dots are arranged, and each second sensor wiring 12 is arranged in pixel dots. This is a sensor wiring in the column direction extending in the other direction (column direction of the matrix).

  FIG. 1 schematically shows a part of the shelf-like connecting portion 16 </ b> A of the liquid crystal display panel 1 together with the inspection device 28 and its probe 29. A strip-shaped connection pad 22 for connecting to the terminal of the chip of the driving IC 19 is formed at the end of the first sensor wiring 11 that also serves as the common electrode wiring. Each first sensor wiring 11 extends further outward (on the edge of the substrate) than the connection pad 22 and is electrically connected to the inspection wiring 26 via the switching element 25. One inspection wiring 26 is provided in one wiring group 22 formed by the first sensor wiring 11, and one inspection pad 27 is provided at an end of the inspection wiring 26.

  In the first wiring group 22, the odd-numbered first sensor wiring 11 </ b> A from the right end is turned on / off by the switching element 25 being turned on / off by the voltage applied to the first switching control wiring 23. The pad 27 becomes conductive or non-conductive. Further, the even numbered first sensor wiring 11B from the right end is turned on / off by the switching element 25 being turned on / off by the voltage applied to the second switching control wiring 24, and is electrically connected to the inspection wiring 26 and the inspection pad 27. It becomes conduction. In a specific example, these switching elements 25 are n-type TFT elements formed simultaneously with the TFT elements 14 of the respective pixel dots.

  Each wiring group 22 may be composed of the entire first sensor wiring 21 or the entire second sensor wiring 12, or may be composed of a part thereof. For example, the first sensor wiring 11 can be divided into two wiring groups 22, and the inspection wiring 26 and the inspection pad 27 can be provided for each of the wiring groups 22.

  FIG. 3 shows a lighting inspection state of the liquid crystal display panel. In order to apply a voltage to the liquid crystal layer at each pixel dot, a high level voltage that turns on the switching element 25 is applied to both the first and second switching control wirings 23 and 24. A common potential is supplied to the first sensor wiring 11 also serving as a common electrode. At the same time, the pixel electrode potential is similarly supplied to the second sensor wiring 12 serving also as a signal line, and writing is performed.

  FIG. 4 schematically shows how a short circuit inspection is performed between adjacent sensor wires. In the first stage shown in the left half of FIG. 4, a predetermined voltage is applied from the inspection device 28 to the inspection pad 27, and only the first switching control wiring 23 of the two switching control wirings is set to a high level potential. As a result, the odd-numbered first sensor wirings 11 </ b> A in the wiring group 22 are conducted to the inspection pad 27. In this way, a charge is applied by applying a voltage to the odd-numbered first sensor wiring 11A. Next, in the second stage shown in the right half of FIG. 4, only the first switching control wiring 24 is set to the high level potential, and thereby the even-numbered second sensor wiring 11 </ b> B in the wiring group 22 is conducted to the test pad 27. Let Then, the discharge current from the even-numbered second sensor wiring 11 </ b> B is observed by the ammeter mechanism or galvanometer mechanism of the inspection device 28. That is, it is observed that a discharge current corresponding to the amount of charge accumulated in the even-numbered second sensor wirings 11 </ b> B flows into the inspection device 28 through the inspection pad 27.

  If adjacent sensor wires are short-circuited, the even-numbered sensor wires 11B are also charged through the short-circuit during the period in which the odd-numbered sensor wires 11A are charged. The amount of discharge current is larger than when there is no short circuit. In this way, by observing the discharge current, it is possible to detect the presence or absence of a short circuit between adjacent sensor wires 11.

  According to this embodiment, since the power feeding system from the inspection probe to each sensor wiring in one wiring group 22 can be integrated into one point, there is no difference in principle in power feeding to each sensor wiring 11, The occurrence of display unevenness due to the contact state of the probe can be effectively prevented. Furthermore, the maintenance frequency of the inspection probe can be suppressed, and the inspection cost can be reduced. Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage.

  In addition, the flat display device according to the above embodiment has been described with an example of detecting the presence or absence of short-circuit between wirings arranged in parallel in one row, but the arrangement of sensor wirings is in an arrangement arranged in parallel to one row. The present invention is not limited to wiring that is orthogonal to the vertical and horizontal directions, and the same effects as those of the flat display device according to the above-described embodiment can be obtained.

  Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine the component covering different embodiment suitably.

  Below, the flat display apparatus of a comparative example is demonstrated using FIGS. As shown in FIGS. 5 to 7, two test pads 27 </ b> A and 27 </ b> B are provided corresponding to one wiring group 22. The odd-numbered sensor wiring 11A counted from the right end of the wiring group 22 can be electrically connected to one inspection pad 27A through the switching element 25 and one inspection wiring 26A provided at the end of each wiring. The even-numbered sensor wiring 11B can be electrically connected to the other inspection pad 27A through the switching element 25 provided at the end of each wiring and the other inspection wiring 26B. As shown in FIG. 7, only one switching control wiring is provided. For this reason, the switching element 25 connected to each wiring in the wiring group 22 can be switched only between the conductive state and the non-conductive state at the same time.

  As shown in FIG. 5 corresponding to FIG. 3, when performing a lighting test, each first sensor wiring 11 that also serves as a common electrode wiring is electrically connected to the test pad 27 </ b> A or 27 </ b> B. That is, the switching element 25 at the end of each wiring is made conductive by the switching control wiring. At the same time, the common electrode potential is supplied from the probes 29A and 29B to both of the two test pads 27A and 27B. Further, at the same time, the second sensor wiring 12 that also serves as a signal line is similarly written by supplying a pixel potential.

  As shown in FIG. 6 corresponding to FIG. 4, when inspecting a short circuit between adjacent sensor wires 11, the probes 29A and 29B are also brought into contact with the inspection pads 27A and 27B, respectively. Then, different voltages are supplied to the test pads 27A and 27B, respectively, and the current flowing between the odd-numbered sensor wiring 11A and the test pads 27A and 27B is measured with each switching element 25 in a conductive state.

  Next, a problem that may occur in the flat display device and the inspection method of the comparative example will be described with reference to FIG. First, in the comparative example, there are a plurality of power supply systems from the inspection device to each sensor wiring through the probe and the inspection pad, and these are independent. Therefore, when the contact state of the individual probes 29A and 29B becomes unstable due to wear or bend 29C, the sensor wiring 11A connected to the test pad 27A with good contact and the sensor wiring connected to the test pad 27B with poor contact 11B and the power supply state is different. In this way, it is visually recognized as block-like display unevenness along the sensor wiring 11, and it is determined that the display is defective and the yield is deteriorated.

  Further, the difference in the power supply state also affects the charge discharge when the power supply of the liquid crystal display panel is turned off, so that only the specific sensor wiring 11 is charged, which also causes display unevenness. . Therefore, the frequency of maintenance such as probe replacement of the inspection apparatus increases, which can be a high cost factor.

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display panel; 10 ... Flat panel display device;
11: first sensor wiring also serving as a common electrode; 11A: odd-numbered first sensor wiring;
11B: Even-numbered first sensor wiring; 11C: Common electrode for each pixel dot;
12 ... Second sensor wiring also serving as signal line; 13 ... Scanning line;
14 ... Pixel dot TFT element; 15 ... Pixel electrode; 16 ... Array substrate;
16A ... Shelve connection region of array substrate; 17 ... Counter substrate;
18 ... Polarizing plate; 19 ... Drive IC; 19A ... FPC;
21 ... Connection pad; 22 ... Connection pad group; 23 ... First switching control wiring;
24 ... second switching control wiring; 25 ... switching control TFT element; 26 ... inspection common wiring;
27 ... Inspection pad; 28 ... Inspection device; 29 ... Probe;
DESCRIPTION OF SYMBOLS 3 ... Control part; 4 ... Battery; 5 ... Surface light source device

Claims (3)

  Provided with row-direction wiring and column-direction wiring arranged in a matrix-like row direction and column direction, in which pixel dots are arranged in the display area, and switching is performed for each end of these wirings drawn out of the display area An element is provided, and one wiring group formed by row-direction wiring or column-direction wiring is electrically connected to one inspection pad through a switching element for each wiring, and an odd-numbered wiring in the wiring group is Only when the switching element is switched to the conducting state through the first switching control wiring, the switching pad is conducted to the one inspection pad, and the even-numbered wiring in the wiring group is conducted to the switching element through the second switching control wiring. A flat display device which is electrically connected to the one inspection pad only when switched to a state.   2. The display device according to claim 1, wherein a function of sensing contact of a fingertip or a pen tip is provided in the display area, and the row direction wiring and the column direction wiring are sensor wirings for contact sensing. Flat display device. A method for inspecting whether there is a short circuit between adjacent row direction wirings or column direction wirings in the flat display device according to claim 1,
First, an odd-numbered or even-numbered wiring in the one wiring group is supplied to only one of the first and second switching control wirings by supplying a potential for making the switching element conductive. And then applying a voltage to these wires,
Next, by supplying a potential that makes the switching element conductive to only the other of the first and second switching control wirings, the other wirings in the one wiring group are electrically connected to the one inspection pad. A method for inspecting a flat display device, comprising measuring a discharge current from the other wiring.

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