JP2010032800A - Active matrix substrate, liquid crystal display panel and inspection method of active matrix substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active matrix substrate capable of efficiently performing inspections of electric characteristics of wiring and switching element for display or the like formed on the substrate even in the state of the substrate only, even for the active matrix substrate whose pixel composition is made fine. <P>SOLUTION: The active matrix substrate includes, on a display area 8: a plurality of pixel electrodes 5 arrayed in a matrix shape of row direction and column direction; a plurality of scanning lines 2 extended in the row direction of an array of the pixel electrodes 5; a plurality of data lines 3 extended in the column direction of the array of the pixel electrodes 5; and a plurality of switching elements 4 for display, the switching elements applying prescribed potentials to the pixel electrodes 5 based on signals applied by the scanning lines 2 and the data lines 3. With respect to at least one side of the scanning lines 2 and the data lines 3, a plurality of lines are connected with one inspection pad 11, 14 via switching elements 19 for inspection and a photoelectric element 17 which operates according to the irradiation of light and controls the on/off of the switching elements 19 for inspection are disposed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an active matrix substrate, a liquid crystal display panel, and a method for inspecting an active matrix substrate, and in particular, even if a pixel configuration is miniaturized in order to perform a small and high-definition image display, the substrate The present invention relates to an active matrix substrate, a liquid crystal display panel, and an inspection method for an active matrix substrate that can efficiently inspect electrical characteristics of wirings and image display switching elements formed on the substrate.

  An active matrix substrate for displaying an image on a so-called flat panel display such as a liquid crystal display panel is arranged in a display area for displaying an image in a matrix corresponding to a pixel electrode formed in a matrix shape and corresponding to the arrangement of the pixel electrode. A plurality of scanning lines formed in the direction, a plurality of data lines formed in the column direction, and provided corresponding to each pixel electrode, and connected to the scanning lines and the data lines. And a display switching element for applying a predetermined voltage to the pixel electrode based on a signal applied to the pixel electrode.

  When such an active matrix substrate is used for, for example, a liquid crystal display panel, the active matrix substrate is disposed to face a counter substrate on which a counter electrode, a color filter and the like are formed at a predetermined interval, and the periphery is bonded with a sealing material. At the same time, liquid crystal is sealed between the two substrates. Further, a polarizing plate is attached to the outside of both substrates, and on the active matrix substrate, a driving semiconductor element in which a driving circuit for image display is formed, an FPC for connecting to an external circuit substrate, etc. Is connected. Here, a defective active matrix substrate in which a wiring electrode such as a scanning line or a data line formed is disconnected or short-circuited, or a TFT serving as a display switching element generates a leakage current is an active matrix. It is discovered before the assembly process that combines the substrate with the counter substrate, for example, before the scribing process that separates the active glass substrate from the mother glass on which multiple substrates are formed. It is preferable in terms of manufacturing cost reduction that it is not restored to the next step.

  As a method for inspecting whether or not the TFT, which is a display switching element formed in the display region of the active matrix substrate, operates normally, from a test pad formed in a peripheral region outside the display region of the active matrix substrate, A method is proposed in which a write voltage is applied to a TFT and a pixel electrode connected to the TFT via a scanning line and a data line to give a charge, and after a predetermined time has passed, a read voltage is applied to the pixel electrode to measure the charge. (See Patent Document 1). According to this method, by utilizing the capacitor function of the pixel electrode, in the state of the active matrix substrate alone, there is no leakage current in each pixel electrode and the TFT connected thereto, and the pixel to be measured It is possible to accurately inspect in a relatively short time that there is no disconnection or short circuit in the scanning lines and data lines leading to the electrodes and TFTs.

In the peripheral area outside the display area of the active matrix substrate, a plurality of scanning lines and data lines are connected to one inspection pad via an inspection TFT as a switching element, and the inspection TFT gate is connected to the inspection TFT. There has been proposed a configuration in which the inspection pad and the scanning line and the data line are electrically connected by energizing the connected inspection gate wiring (see Patent Document 2). By this method, the number of inspection pads can be reduced as compared with the case where inspection pads are provided for each scanning line or data line, and the area of each inspection pad and the pitch between inspection pads are increased. be able to.
JP-A-3-200121 Japanese Patent Laid-Open No. 2005-241988

  In the above-described conventional active matrix substrate inspection method in which a predetermined charge is given to each pixel electrode in the display area and this is read out after a lapse of a predetermined time, the charge is written to each of a plurality of scanning lines and data lines. Therefore, it is necessary to provide a test pad for each of the scanning lines and the data lines. However, the scanning lines and data lines arranged in the display area with a smaller size and higher resolution have a narrow width and a small pitch. In particular, in a so-called COG (Chip On Glass) type active matrix substrate in which a driving semiconductor element for image display is mounted in the peripheral region, the space for disposing the inspection pads in the peripheral region is narrowed. Both the area and the arrangement pitch must be reduced.

  In order to perform an inspection with such an inspection pad having a small area and pitch, a probe having a thin tip must be used as an inspection probe, and the probe pin itself is expensive and inevitably. Since the strength is reduced, the life of the inspection probe is shortened, resulting in an increase in cost. In addition, the probe pin must be accurately positioned on the test pad, and a predetermined pressing force is required to prevent contact resistance between the test pad and the probe pin. Inspection efficiency also decreases.

  Further, in the method described in Patent Document 2, ON / OFF of the inspection TFT is controlled by using a common inspection gate wiring for each group of scanning lines and data lines. And gate lines cannot be specified individually. In order to individually control the connection between the inspection pad and the scanning line or data line to be measured, the same number of inspection gate wirings as the number of inspection TFTs connected to each scanning line or data line are required. For example, a control circuit capable of individually controlling the inspection TFT as a switching element is required.

  If the number of wirings is increased or a control circuit is formed in order to individually control the inspection TFTs, the circuit configuration on the active matrix substrate becomes complicated, and a predetermined circuit for arranging the inspection circuits and wirings is required. Area is required. Increasing the area of the peripheral area where the inspection circuit and the wiring for inspection are formed reduces the ratio of the area of the display area to the area of the active matrix substrate, which is contrary to the demand for so-called framed frames. Become. In addition, when the inspection TFT as the inspection switching element is electrically switched by energizing the inspection gate wiring, a delay in circuit characteristics and a voltage drop are caused, resulting in a decrease in inspection efficiency and inspection accuracy. There is also a risk of being connected.

  In view of such a problem of the prior art, the present invention provides an active matrix substrate whose pixel configuration is miniaturized by downsizing, high resolution, and the like, such as wirings formed on the substrate and display switching elements. It is an object of the present invention to provide an active matrix substrate, a liquid crystal display panel, and an inspection method for an active matrix substrate that can efficiently inspect electrical characteristics even in a single substrate state.

  In order to achieve the above object, an active matrix substrate of the present invention extends in a row direction of a plurality of pixel electrodes arranged in a matrix in a row direction and a column direction in a display region, and the arrangement of the pixel electrodes. A plurality of scanning lines; a plurality of data lines extending in a column direction of the pixel electrode array; and the pixels connected to the pixel electrodes, respectively, based on signals applied to the scanning lines and the data lines. A plurality of display switching elements for applying a predetermined potential to the electrodes, and at least one of the scanning lines and the data lines is provided in the peripheral region outside the display region via a plurality of inspection switching elements. A photoelectric sensor that is connected to one test pad and that operates by irradiating light to control the on / off of the test switching element to the peripheral region. It characterized in that it has a child.

  The liquid crystal display panel according to the present invention is characterized in that a liquid crystal layer is provided between the active matrix substrate according to the present invention and a counter substrate.

  Furthermore, the inspection method for an active matrix substrate according to the present invention includes a plurality of pixel electrodes arranged in a matrix in a row direction and a column direction in a display region, and a plurality of scanning lines extending in the row direction of the arrangement of the pixel electrodes. A plurality of data lines extending in the column direction of the pixel electrode array, and a plurality of data lines connected to the pixel electrodes, respectively, based on signals applied to the scanning lines and the data lines. A plurality of display switching elements for applying a potential, and a plurality of the scanning lines or the data lines are connected to the inspection pads formed in the peripheral area outside the display area via the inspection switching elements. In the active matrix substrate, the inspection switching element is controlled to be turned on / off by irradiating the photoelectric elements formed in the peripheral region with light. Characterized connected are to be measured the switching the display switching elements sequentially.

  According to the present invention, even if a pixel structure is a miniaturized substrate, it is possible to efficiently inspect electrical characteristics such as wirings formed on the substrate and switching elements for image display with a single substrate. An inspection method for a matrix substrate, a liquid crystal display panel, and an active matrix substrate can be obtained.

  The active matrix substrate according to the present invention includes a plurality of pixel electrodes arranged in a matrix in a row direction and a column direction, a plurality of scanning lines extending in a row direction of the arrangement of the pixel electrodes, and the pixels A plurality of data lines extending in the column direction of the electrode array and a plurality of data lines connected to the pixel electrodes and applying a predetermined potential to the pixel electrodes based on signals applied to the scanning lines and the data lines, respectively. And at least one of the scanning line and the data line is connected to one inspection pad via the inspection switching element in a peripheral region outside the display region. In addition, the peripheral region has a photoelectric element that operates by being irradiated with light, which controls on / off of the inspection switching element.

  According to this configuration, since at least one of the scanning line and the data line is connected to one inspection pad via the inspection switching element, the scanning line or data line to be measured The number of test pads is smaller than the number. Therefore, by increasing the area and pitch of the inspection pad, the probe pin of the inspection probe can be made thicker, and the accuracy of alignment between the inspection pad and the inspection probe is relaxed. In addition, since the ON / OFF control of the switching element for inspection is performed using a photoelectric element that operates when irradiated with light, the circuit configuration including wiring routing can be simplified, and the circuit characteristics are also improved. Effects such as delays and voltage drops can be avoided.

  In the above configuration, it is preferable that an output voltage generated by the photoelectric element when irradiated with light is used as an on-voltage for making the inspection switching element conductive. In this way, it is not necessary to separately provide a power source for supplying the on-voltage, and the circuit configuration can be simplified and the area required for the inspection circuit can be reduced.

  Moreover, it is preferable that the control power supply voltage is applied as an on-voltage to the inspection switching element by causing the photoelectric element to conduct when irradiated with light. By doing in this way, ON / OFF control of the inspection switching element by light irradiation can be performed easily and reliably.

  Furthermore, it is preferable that an element mounting area for mounting a driving semiconductor element for performing display in the display area is provided in the peripheral area, and the photoelectric element is formed in the element mounting area. By doing so, it is possible to eliminate waste in circuit arrangement in the peripheral area which is a non-display area.

  The liquid crystal display panel according to the present invention includes a liquid crystal layer between the active matrix substrate according to the present invention and the counter substrate.

  With this configuration, it is possible to obtain a liquid crystal display panel with high manufacturing efficiency that can detect defects early using an active matrix substrate that can be easily inspected in a substrate state.

  Furthermore, the inspection method for an active matrix substrate according to the present invention includes a plurality of pixel electrodes arranged in a matrix in a row direction and a column direction in a display region, and a plurality of scanning lines extending in the row direction of the arrangement of the pixel electrodes. A plurality of data lines extending in the column direction of the pixel electrode array, and a plurality of data lines connected to the pixel electrodes, respectively, based on signals applied to the scanning lines and the data lines. A plurality of display switching elements for applying a potential, and a plurality of the scanning lines or the data lines are connected to the inspection pads formed in the peripheral area outside the display area via the inspection switching elements. In the active matrix substrate, the inspection switching element is controlled to be turned on / off by irradiating the photoelectric element formed in the peripheral region with light. Sequentially switching said display switching element to be measured is connected to a de.

  In this way, even on a substrate with a miniaturized pixel configuration, it is possible to efficiently inspect electrical characteristics such as wiring formed on the substrate and switching elements for image display with a single substrate. An inspection method for an active matrix substrate can be realized.

  In this case, the output voltage generated by the photoelectric element when irradiated with light can be used as an on-voltage for conducting the inspection switching element, and when the light is irradiated, When the photoelectric element becomes conductive, a control power supply voltage can be applied as an ON voltage to the inspection switching element.

  Further, it is preferable that the photoelectric element is irradiated with light through an optical fiber. By using the optical fiber, it is possible to accurately irradiate light at a predetermined place on the active matrix substrate, and it is possible to reliably perform ON / OFF control of the inspection switching element.

  At this time, it is preferable that the tip of the optical fiber on the photoelectric element side has a convex curved shape. A lens effect is produced by making the tip end a convex curved surface, and the light emitted from the optical fiber can be collected, so that the irradiation light can be accurately applied to a predetermined photoelectric element.

  Hereinafter, preferred embodiments of an inspection method for an active matrix substrate, a liquid crystal display panel, and an active matrix substrate of the present invention will be described with reference to the drawings. In the following description, an example will be described in which an active matrix substrate according to the present invention includes both a display switching element and an inspection switching element formed of thin film transistors (TFTs). However, this does not limit the configuration of the present invention, and other switching element structures such as a metal insulator metal (MIM) structure can be used as the switching element in addition to the TFT. In addition, in all the drawings used in the following description, the ratio of dimensions of each component is appropriately changed for easy understanding of the drawings.

  FIG. 1 is a plan view showing a schematic configuration of an active matrix substrate according to an embodiment of the present invention. As shown in FIG. 1, the active matrix substrate 1 according to the present embodiment has a display in which a plurality of pixel electrodes 5 to which a voltage for image display is applied are arranged in a matrix in a row direction and a column direction. Region 8 is formed.

  In the display region 8, a number of scanning lines 2 (also referred to as “gate lines”) corresponding to the number of rows formed by the pixel electrodes 5 are arranged extending in the row direction of the pixel electrodes 5. A number of data lines 3 (also referred to as “source lines”) corresponding to the number of columns formed by the pixel electrodes 5 are arranged extending in the column direction of the pixel electrodes 5. The plurality of scanning lines 2 and the plurality of data lines 3 are arranged orthogonally to each other.

  Display TFTs 4 as display switching elements are arranged at respective intersections of the respective scanning lines 2 and data lines 3, and the display TFTs 4 are connected to the corresponding pixel electrodes 5 and correspond to each other. The scanning line 2 and the data line 3 are connected.

  In the active matrix substrate 1, the scanning lines 2 are sequentially selected and scanned, and the potentials of the corresponding pixel electrodes 5 are applied from the data lines 3, and based on the signals applied to the scanning lines 2 and the data lines 3 in this way. Thus, image display is performed when the pixel electrode 5 has a predetermined potential. For example, in the case of a liquid crystal display panel, a potential difference between a potential of a counter electrode normally provided on a counter substrate disposed opposite to the active matrix substrate and a potential applied to the pixel electrode 5 on the active matrix substrate 1. By changing the orientation of the liquid crystal molecules sandwiched between these electrodes, the amount of light transmitted through the liquid crystal layer is changed. For this reason, an area where the pixel electrode 5 and the display TFT 4 as a display switching element are disposed surrounded by the scanning lines and the data lines forms one pixel 7 in the display image.

  In addition, including the case where the active matrix substrate 1 is used for a liquid crystal display panel, in order to stably operate the display TFT 4 as a display switching element and to stabilize the potential of the pixel electrode 5, each pixel 7, an additional capacitor 6 connected to the pixel electrode 5 is formed.

  As shown in FIG. 1, the scanning line 2 and the data line 3 are drawn to the peripheral area 15 outside the display area 8. The scanning line 2 drawn out to the peripheral region 15 is connected to the control pad 11 of the scanning line 2 through the scanning line 9 for the scanning line 2 through the scanning circuit 9 formed in the peripheral region 15. Further, the data line 3 drawn to the peripheral area 15 passes through the inspection switching section 12 formed in the peripheral area 15 and passes through the inspection wiring 13 for the data line 3 to the inspection pad 14 of the data line 3. It is connected.

  The inspection switching unit 12 for the data line 3 connects a plurality of, for example, about 8 to 16, data lines 3 to the corresponding inspection pad 14 via a switching circuit capable of switching control. . For example, in the case of a VGA monitor for a mobile phone having a diagonal screen size of about 5 to 10 cm, 480 pixels are used for color display in the horizontal (horizontal) direction of the screen, that is, the row direction of the pixels 7 forming the display area. When counted by each RGB sub-pixel, 1440 fine pixels 7 are aligned, and the number of data lines 3 corresponding to the pixels 7 is provided. For this reason, although the arrangement pitch of the data lines 3 is very narrow as about 50 μm, the data lines 3 are bundled by the switching circuit of the inspection switching unit 12 every 8 to 16 lines as in this embodiment, and the data lines 3 By connecting the test pads 14 in an aggregated manner to the number of test pads 14 that is 1/8 to 1/16 of the number, about 0.5 mm can be secured as the arrangement pitch of the test pads 14, so that the test is brought into contact with the test pads 14 A sufficient probe pin thickness can be secured.

  On the active matrix substrate 1, circuit elements such as drive wirings and drive logic circuits used when the active matrix substrate 1 is operated as a liquid crystal display panel after the active matrix substrate 1 is completed are mounted. Circuit terminals, and electrode terminal portions for connecting the active matrix substrate 1 and an external circuit substrate are formed, but not all are shown in FIG. Further, the size and position of the display area 8 on the active matrix substrate 1 are not accurately shown.

  Next, a detailed description of the inspection switching unit 12 of the data line 3 shown in FIG. 1 will be given with reference to FIG. In the present embodiment, since the scanning circuit 9 that scans the scanning line 2 is automatically scanned by a logic circuit, the scanning line 2 is provided with the inspection switching unit 12 provided for the data line 3. It is not configured. However, for example, when the scanning circuit 9 of the scanning line 2 does not have an automatic scanning function, the inspection switching unit 12 shown below for the data line 3 is similarly provided for the inspection of the scanning line 2. It doesn't matter.

  As shown in FIG. 2, in the inspection switching unit 12 for the data line 3, the plurality of data lines 3 drawn from the display area 8 shown as the hatched portion at the left end in the figure are inspection switching elements. The data lines 3 are connected and bundled through the TFTs 19, and are connected to the inspection pads 14 for one data line 3 through the inspection wirings 13 for one data line 3. In FIG. 2, only four of 19-1, 19-2, 19-3, and 19-4 are shown as the inspection TFT 19 in order to avoid the complexity of the drawing. In the inspection switching unit 12 shown in the present embodiment, since 8 to 16 data lines 3 are connected to one inspection pad 14, the number of inspection TFTs 19 is also 8 to 16. The number of the data lines 3 bundled on one inspection pad 14 via the inspection switching element is appropriately determined according to the wiring pitch of the data lines 3 corresponding to the pitch of the pixels and the total number.

  Since the inspection switching element used in the inspection switching circuit 12 can be formed in the same process as the display switching element, the inspection TFT 19 having the same configuration as the display TFT 4 as the display switching element is used. There are many. However, the switching element for inspection in the present invention is not limited to this, and any other switching element can be used as long as it can be switched between connection / disconnection by irradiating light to the photoelectric element. be able to.

  A photoelectric element 17 for controlling on / off of the inspection TFT 19 is arranged in the photoelectric element forming section 16 of the inspection switching section 12 for the data line 3. As shown in FIG. 2, photoelectric elements 17-1 to 17-4 are provided corresponding to the respective inspection TFTs 19-1 to 19-4, and output terminals of the photoelectric elements 17-1 to 17-4 are provided. Are connected to the gates of the respective inspection TFTs 19-1 to 19-4 through the control wiring 18. In the inspection switching unit 12, on / off of the inspection TFT 19 of each of a plurality of (for example, 16) data lines 3 connected to one inspection pad 14 is switched by individually controlling the photoelectric element 17. Thus, the same number (for example, 16) of photoelectric elements 17 as the number of inspection TFTs 19 (for example, 16) connected to one inspection pad 14 are provided. In FIG. 2, only four photoelectric elements 17 are illustrated as in the inspection TFT 19.

  In this manner, in the inspection switching unit 12, a group of a plurality of data lines 3 is bundled into one inspection pad 14 via the inspection TFT 19, so that in this embodiment, active The number of test pads 14 of the data lines 3 arranged on the matrix substrate 1 is, for example, the number of quotients obtained by dividing the total number of data lines 3 by the number of photoelectric elements 17 provided in the test switching unit 12. Efficiency is good. In the description of FIG. 2, the example in which the inspection TFTs 19 bundled on one inspection pad 14 are configured to correspond to the data lines 3 arranged continuously is shown. However, the wiring method is devised. Thus, the configuration may be such that several inspection TFTs 19 having a positional relationship of several jumps are bundled on one inspection pad 14.

  Note that as the photoelectric element 17, it is preferable to use a photodiode, a solar cell, or the like as a semiconductor element that can be formed in the same semiconductor process as a TFT that is a switching element for display or inspection. However, the photoelectric element 17 of the present invention is not limited to the photoelectric element as these semiconductor elements.

  The control power supply 20 is a power supply for applying a predetermined voltage to the gate of the control TFT 19 when each photoelectric element 17 is irradiated with light 22 from the light irradiation port. The control power source 20 does not need to be provided with a voltage source as a circuit element, and a predetermined control voltage may be applied at the time of inspection. For this reason, the control power source 20 is formed as a voltage application pad, and a predetermined voltage is applied by contacting a voltage application probe at the time of inspection, or applied for necessity other than the control voltage at the time of inspection. For example, a method of applying a voltage using a connection wiring formed on the active matrix substrate 1 can be applied.

  A COG pad 21 for mounting an IC as a driving semiconductor element is formed between the display area 8 and the inspection TFT 19 of each data line 3. As will be described later, from the viewpoint of reducing the area of the peripheral region 15 on the active matrix substrate 1 as much as possible and covering the inspection switching unit 12 with a semiconductor element mounted thereon, the inspection switching unit 12 can be covered. Is preferably formed in an element mounting region which is a region where a driving semiconductor is mounted. In this case, as shown in FIG. 2, the inspection TFT 19 is disposed in an extended portion on the opposite side of the display area 8 with respect to the COG pad 21 of the data line 3.

  Next, a specific method for controlling on / off of the inspection TFT 19 using the photoelectric element 17 will be described with reference to FIGS.

  FIG. 3 is a diagram showing a first specific example for applying a predetermined gate voltage to the gate of the inspection TFT 19 using the photoelectric element 17. In the first specific example shown in FIG. 3, as the photoelectric element 17, an element such as a solar cell that generates a voltage with a constant electromotive force when irradiated with light is used.

FIG. 3A is a block diagram showing a circuit configuration in the inspection switching unit 12 when a device (for example, a solar cell) having a photovoltaic function is used as the photoelectric element 17. As shown in FIG. 3A, the output terminal of the photoelectric element 17 is connected to the gate of the inspection TFT 19 provided between the COG pad 21 of the data line 3 and the inspection pad 14 of the data line 3. When the photoelectric element 17 is irradiated with the light 22 from the light irradiation port, the total potential of the electromotive force generated by the photoelectric element 17 and the potential E ₀ of the control power source 20 is applied to the gate of the inspection TFT 19. The

  Between the gate of the inspection TFT 19 and the ground potential, there is provided a charge removal circuit 23 for removing charges applied to each pixel electrode 5 in the display region 8 for inspection.

  FIG. 3B shows an image when the electromotive forces in the photoelectric element 17 are combined. As shown in FIG. 3A, in the first specific example shown in FIG. 3, the on-voltage of the gate of the inspection TFT 19 is obtained by the electromotive force of the photoelectric element 17. For this reason, the electromotive force of the photoelectric element 17 needs to have a value equal to or greater than a voltage difference between the ON voltage and the OFF voltage of the inspection TFT 19. When an electromotive force greater than the difference between the on-voltage and the off-voltage of the inspection TFT 19 cannot be obtained by photoelectric conversion at one PN junction of the photoelectric element 17, a plurality of electromotive forces as shown in FIG. By forming the PN junction in the photoelectric element 17, the electromotive force of the photoelectric element 17 can be made a certain level or more. FIG. 3B shows an example of using three in series when the electromotive force at one PN junction is Es.

FIG. 3C shows the on-voltage characteristics of the inspection TFT 19. As shown in FIG. 3C, when the potential E ₀ of the control power supply 20 is applied to the gate of the inspection TFT 19, the inspection TFT 19 is turned off. When the photoelectric element 17 is irradiated with light, in addition to the potential E ₀ of the control power supply 20, the electromotive force nEs corresponding to the number n of electromotive forces Es by the PN junction of the photoelectric element 17 is Applied to the gate. This combined potential “E ₀ + nEs” is higher than the ON voltage of the inspection TFT 19.

  FIG. 4 shows a second method for applying a predetermined gate voltage to the gate of the inspection TFT 19 using the photoelectric element 17 as a specific method for controlling on / off of the inspection TFT 19 using the photoelectric element 17. It is a figure which shows a specific example.

  In the second specific example shown in FIG. 4, the photoelectric element 17 is a circuit element having an optical switching function, and its conduction state and non-conduction state change when irradiated with light. Then, by irradiating light and making the photoelectric element 17 conductive, potentials from a plurality of control power supplies 20 that supply different voltages are applied to the gate of the inspection TFT 19, thereby turning on / off the inspection TFT 19. Be controlled.

FIG. 4A shows a circuit configuration diagram when a bipolar optical switching circuit is used as the photoelectric element 17 as a second specific example. As shown in FIG. 4 (a), the gate of the test TFT19 includes a first control voltage 20a via the first resistor R _0, and the second control voltage 20b via a second resistor R ₁ It is connected. In this case, the photoelectric elements 17a and 17b are photodiodes arranged so as to perform a bipolar operation. When the light 22 is irradiated, the photodiode 17b connected in parallel with _R0 is non-conductive. _{In a} state where the photodiode 17a connected in parallel with ₁ is turned on and the light 22 is not irradiated, the photodiode 17a is turned on and the photodiode 17b is turned off. In this manner, when the values of R ₀ and R ₁ are sufficiently high, when the photoelectric element 17 is irradiated with the light 22, the gate potential of the inspection TFT 19 becomes E ₁ , and the photoelectric element When the light 22 is not irradiated to the gate 17, the gate potential of the inspection TFT 19 is E ₀ .

As shown in the on-voltage characteristics of the inspection TFT in FIG. 4C, the inspection TFT 19 is turned on when the gate potential is E ₁ , and the inspection TFT 19 is turned off when the gate potential is E _0. Thus, the on / off state of the inspection TFT 19 can be controlled by irradiating the photoelectric element 17 with light.

FIG. 4B shows a circuit configuration when the photodiode as the photoelectric element 17 is used so as to form a monotype circuit configuration instead of the bipolar type as shown in FIG. 4A. A photodiode as a photoelectric device 17, when used to form a circuit arrangement of a mono-type, because that would only photodiode 17a is connected in parallel with the second resistor R _1, the photodiode 17a When the light 22 is irradiated, both ends of the second resistor R ₁ become conductive, which is equivalent to R ₁ = 0Ω. In this case, since the on-voltage E ₁ is applied to the gate of the inspection TFT 19, the inspection TFT 19 becomes conductive.

On the other hand, when the light 17 is not irradiated on the photodiode 17a, the voltage applied to the gate of the inspection TFT 19 is from the on-voltage E ₁ to R ₁ / (R ₁ + R ₀ ) * E _0. Will be reduced. Accordingly, by setting the gate potential of the inspection TFT 19 at this time, [E ₁ − (R ₁ / (R ₁ + R ₀ ) * E ₀ )] to be lower than the threshold voltage of the inspection TFT 19, When the element 17 is not irradiated with the light 22, the inspection TFT 19 can be turned off.

As described above, the control power supply 20 does not necessarily require a voltage source as a circuit element to be provided in the switching control unit. Therefore, as in the case of the second embodiment shown in FIG. 4, even when two control potentials E ₀ and E ₁ are used, pads for supplying the respective voltages are formed and supplied. A predetermined potential other than that applied as a control potential during the inspection of the active matrix substrate can be supplied by the circuit wiring.

  Next, an example of the inspection method for the active matrix substrate of the present invention will be described.

  The inspection method of the active matrix substrate according to the present invention includes a switching element for inspection formed on a wiring to be measured such as a data line or a scanning line by irradiating light to a photoelectric element formed in a peripheral region outside the display region. The display switching elements formed in the respective pixels in the display region connected to the inspection pad are sequentially switched by controlling on / off of the display.

  For this reason, the scanning line and data for operating the pixel to be inspected without using the inspection pad for each wiring and using the common inspection pad bundled through the switching element for inspection for each wiring. A line can be selected, and a display switching element formed in a pixel to which the selected scan line and data line are connected can be operated. As a result, whether or not a display switching element and a pixel electrode formed in a predetermined pixel, a scanning line and a data line leading to the predetermined pixel are not disconnected or short-circuited, or other defects that cause defective electrical characteristics have occurred. It can be judged through an inspection pad.

  More specifically, as an inspection method, for example, a write voltage is applied to the switching element 4 for display, the pixel electrode 5 connected thereto, and the additional capacitor 6 via the scanning line 2 and the data line 3 to store charges. A case will be described in which a method of measuring a charge by applying a read voltage to a pixel electrode after a predetermined time has elapsed will be described.

  When this method is used, measurement is applied to the control pad 11 of the scanning line 2 and the inspection pad 14 of the data line 3 so that a predetermined potential is applied to the display switching element 4 of the pixel 7 to be measured at a predetermined timing. The scanning circuit 9 is operated so that the predetermined scanning line 2 operates by bringing the probe into contact, and at the same time, the voltage to be applied to the data line 3 is applied, and at the same time, the inspection switching unit 12 shown in FIG. 1 and FIG. Among the photoelectric elements 17 formed in the photoelectric element forming section 16, the photoelectric element 17 that controls the connection between the data line 3 connected to the display switching element 4 of the pixel 7 to be measured and the inspection pad 14. Irradiate light.

  In this way, by irradiating the predetermined photoelectric element 17 with light, the inspection voltage applied to the inspection pad 14 is applied to the data line 3 connected to the pixel 7 to be measured, and the measurement target The measurement voltage is applied to the pixel electrode 5 and the additional capacitor 6 via the display switching element 4 of the pixel 7. In this way, application of a predetermined voltage is performed in a state where the connection between the control pad 11 and the inspection pad 14 and the display switching element 4, the pixel electrode 5, and the additional capacitor 6 of the pixel 7 to be measured is secured. The charge remaining after a lapse of a certain time can be measured. Therefore, the inspection of the display switching element 4, the pixel electrode 5, the additional capacitor 6, and the scanning line 2 and the data line 3 connected to the measurement target pixel 7 of the measurement target pixel 7 is performed. The number of pixels 7 corresponding to the number can be performed simultaneously.

  When the inspection of a group of pixels 7 to be measured, which are simultaneously inspected first, is finished, light irradiation to the photoelectric element 17 that has been irradiated with light is stopped and subsequently formed in the photoelectric element forming portion 16. By irradiating the other photoelectric element 17 thus irradiated with light, the connection between the other data line 3 connected to the next pixel 7 to be measured and the inspection pad 14 is secured, and the same measurement is performed for this pixel 7 as well. By repeating the procedure, the electrical characteristics can be inspected. By repeating this operation, that is, by sequentially switching the photoelectric elements 17 that irradiate light in the photoelectric element forming unit 16, the pixels 7 to be measured can be sequentially switched. Inspection about the pixel 7 can be performed.

  As described above, for example, 8 to 16 data lines 3 are bundled and connected to one inspection pad 14 via the inspection switching element 19. Further, one active matrix substrate 1 is provided in a form in which, for example, about 30 test pads 14 of the data lines 3 are aggregated. For this reason, using an inspection probe on which 30 inspection probe pins are formed, this is simultaneously pressed against the inspection pads 14 of all the data lines 3 of one active matrix substrate 1, and in this state, By sequentially irradiating light to the photoelectric elements 17 for switching the data lines 3 connected to the respective inspection pads 14, the connection between the inspection pads 14 and the data lines 3 is switched by the inspection switching elements 19, and all The data line 3 can be inspected.

  According to the above-described method of applying a predetermined voltage to the display switching element 4 and the pixel electrode 5 formed in the pixel 7 and the additional capacitor 6 and measuring the charge stored after a predetermined time has elapsed, Etc., the active matrix substrate 1 can be inspected before it is bonded. For this reason, it is possible to inspect the mother glass on which a plurality of active matrix substrates 1 are formed as a pattern before the scribing process, and to detect and correct defective substrates at an early stage, thereby improving yield and manufacturing cost. This is favorable in terms of reducing

  In the active matrix substrate inspection method of the present invention, on / off switching of the inspection switching element formed on the data line side or on both sides of the scanning line and the data line is controlled by light irradiation to the photoelectric element. To do. Therefore, the quality determination of the circuit wiring and circuit elements on the active matrix substrate is not limited to the above-described method, and is not limited to the inspection method using the active matrix substrate alone. For this reason, for example, when the active matrix substrate is used for a liquid crystal display panel, the active matrix of the present invention is also used in the inspection method for measuring the capacitance with the counter electrode formed on the counter substrate after the counter substrate is bonded. A substrate inspection method can be applied.

  When irradiating light to the photoelectric element 17 formed in the photoelectric element forming part 16 of the inspection switching parts 9 and 12, it is preferable to use an optical fiber. This is because by using an optical fiber, light from the light source can be efficiently and accurately transmitted to the photoelectric element 17 to be irradiated. Further, as shown in FIG. 2, when the photoelectric elements 17 are formed side by side in the photoelectric element forming portion 16, the same number of optical fibers as the formed photoelectric elements 17 are bundled, and the light By aligning the arrangement of the optical elements 17 of the optical fiber and the photoelectric element 17 of the photoelectric element forming unit so as to have the same shape, the optical fiber bundle is aligned like a measurement probe. Prepare to irradiate light accurately. Then, the light source sequentially turned to the input end of the optical fiber is turned on, and the optical fiber is irradiated with light, whereby the photoelectric element 17 can be irradiated with light sequentially.

  When adjacent photoelectric elements 17 are arranged close to each other, it is important to irradiate only the desired photoelectric element 17 with the irradiation light from the optical fiber accurately. For this reason, for example, the lens effect can be obtained by making the end of the optical fiber facing the light source element 17 an appropriate convex curved surface shape, and the irradiation light from the optical fiber can be condensed in a narrow range. preferable. In addition, as described above, when a plurality of optical fibers are bundled and arranged to be opposed to the plurality of photoelectric elements 17 at once, the periphery of the optical fiber is surrounded in a cylindrical shape, and the tip of the cylindrical portion is the photoelectric element. By being able to be pressed against the active matrix substrate 1 around 17, it is possible to prevent malfunction caused by irradiation light from the optical fiber to the photoelectric elements 17 other than the desired photoelectric element 17. it can.

  Note that it is preferable to use a light source such as a semiconductor laser as a light source for the light applied to the photoelectric element 17. This is because the laser light can be accurately irradiated by a desired photoelectric element because the diffusion of the irradiation light is small. Of course, the combination of the laser beam and the optical fiber can further suppress the diffusion of the irradiation light.

  Moreover, there is no restriction | limiting in particular about the wavelength of irradiated light, What is necessary is just to select suitably, considering the realization as a light source and the characteristic of the photoelectric element of the light irradiation side. For example, the sensitivity as a photodiode is higher for red light on the long wavelength side than for blue light on the short wavelength side, but if considering the high electromotive force when used as a solar cell, that is, the photoelectric conversion rate, it is short. Blue light with a wavelength is preferred over red light. Alternatively, the photoelectric elements incorporated in the active matrix substrate 1 are arranged by arbitrarily mixing a device that reacts better on the long wavelength side and a device that reacts better on the short wavelength side as a photosensitive device, and switches the wavelength of the light to be irradiated. Thus, the operation of the inspection control circuit may be controlled. Therefore, the color of the irradiated light is examined according to a specific method for controlling on / off of the inspection TFT by light irradiation to the photoelectric element as described with reference to FIGS.

  Next, an example of a specific arrangement configuration on the active matrix substrate of the present invention will be described with reference to FIGS. 5 and 6 are merely examples of specific arrangement, and do not limit the arrangement on the active matrix substrate of the present invention.

  FIG. 5 is a schematic diagram showing an arrangement configuration on a so-called COG (Chip On Glass) type active matrix substrate in which a driving semiconductor element as a driving circuit is mounted on the active matrix substrate 1.

  As shown in FIG. 5, an element mounting area 32 on which a driving semiconductor element is mounted is disposed at one substrate end portion of the peripheral region 15 of the active matrix substrate 1, that is, the upper portion in FIG. . Between this element mounting area 32 and the display area 8, a COG pad 21 for connecting each terminal of the driving semiconductor element to each data line 3 is formed. An electrode terminal portion 33 for connection to an external circuit substrate (not shown) is formed at the end of the active matrix substrate further outside the element mounting region 32. At the time of actual driving, the image signal input from the electrode terminal portion 33 is transmitted to the COG pad 21 via a driving semiconductor element (not shown) and written to the pixel 7. The display area 8 is disposed at a substantially central portion of the active matrix substrate 1 excluding the element mounting area 32. A scanning circuit 9 in which circuit elements for sequentially driving the scanning lines 2 are arranged is controlled by a signal input from a control pad 11 of the scanning lines 2. In addition, after the active matrix substrate 1 is completed as a liquid crystal display panel, an inspection power supply pad 34 for performing a lighting inspection in a stage before mounting a driving semiconductor is provided next to the electrode terminal portion 33 for connection. It is drawn out and formed.

  In such a COG type active matrix substrate 1, as shown in FIG. 5, the number of the data lines 3 is increased by forming the inspection switching unit 12 for the data line 3 and the inspection pad 14 in the element mounting region 32. The number of pads of the inspection pad 14 is reduced. For this reason, compared to the COG pads 21 formed in the same number as the number of the data lines 3, in response to the decrease in the number of the inspection pads 14, the number of pins of the probe used for the inspection is reduced, and the terminal Inspection probes with a wide pitch can be used, and it is possible to use a probe needle with better bending strength and wear resistance.

  In addition, after the driving semiconductor element is mounted on the active matrix substrate 1, the photoelectric element 17 formed in the inspection switching unit 12 is covered with the driving semiconductor element and silicon resin for fixing the driving semiconductor element. Thus, it is possible to effectively avoid a situation in which unwanted light enters the photoelectric element 17 and malfunctions.

  Next, FIG. 6 shows a case where the test pad 14, the test power supply pad 34, and the test switching circuit 12 of the data line 3 are installed at positions on the substrate opposite to the driving semiconductor element mounting region 32. An example is shown. In this case, in addition to the application to a COG type display device in which a driving semiconductor is mounted and displayed, a digital signal input type active matrix substrate 1 that displays an image by directly applying a digital signal to the active matrix substrate 1. Application to inspection in In addition, by arranging the example shown in FIG. 6, the inspection wiring of the data line 3 and the circuit configuration for inspection can be a wiring system not directly related to the actual drive display of the active matrix substrate 1, During the process of separating the active matrix substrate 1 from the mother glass, the inspection pad 14, the inspection power supply pad 34, and the inspection switching circuit 12 may be separated.

  The embodiments of the active matrix substrate of the present invention have been described above by exemplifying the case where the active matrix substrate is used for a liquid crystal display panel.

  In this description, the control method at the time of voltage application at the time of inspection shows a configuration in which the scanning line side is controlled by a logic circuit, and the data line side is provided with an inspection switching unit to inspect a plurality of data lines. A configuration is shown in which a single inspection pad is connected via a switching element, and this is switched and controlled by a photoelectric element. However, the active matrix substrate of the present invention is not limited to this, and has a configuration in which an inspection switching unit is provided only on the scanning line side, or a configuration in which an inspection switching unit is provided on both the scanning line and the data line. Is also possible.

  Further, the use of the active matrix substrate of the present invention is not limited to a liquid crystal display panel, but a flat plate such as an organic or inorganic EL display, a plasma display, a cold cathode display, a field emission display using a planar electrolysis cathode, etc. It can be widely used as means for efficiently inspecting the display display substrate.

  According to the present invention, even in an active matrix substrate with a miniaturized pixel structure, it is possible to efficiently inspect electrical characteristics such as wirings and display switching elements formed on the substrate even in a single substrate state. The present invention can be used industrially as an active matrix substrate and an inspection method thereof, and particularly as a liquid crystal display panel using the active matrix substrate.

It is a top view which shows schematic structure of the active matrix substrate as embodiment of this invention. It is a schematic block diagram which shows the structure of the test | inspection switch part for data lines in the active matrix substrate as embodiment of this invention. It is a figure which shows the 1st specific example which controls on / off of TFT for a test | inspection using a photoelectric element. (A) shows an example of a circuit configuration, (b) shows a configuration example for improving the electromotive force of a photoelectric element, and (c) shows an on-voltage characteristic of an inspection TFT. It is a figure which shows the 2nd specific example which controls on / off of TFT for a test | inspection using a photoelectric element. (A) is a first example of the circuit configuration, (b) is a first example of the circuit configuration, and (c) is an on-voltage characteristic of the inspection TFT. It is a figure which shows the example of arrangement | positioning on the active matrix substrate of this invention. It is a figure which shows the other example of arrangement | positioning on the active matrix substrate of this invention.

Explanation of symbols

1 active matrix substrate 2 scanning line 3 data line 4 switching element for display (display TFT)
5 pixel electrode 7 pixel 8 display area 11, 14 inspection pad 17 photoelectric element 19 inspection switching element (inspection TFT)

Claims (10)

A plurality of pixel electrodes arranged in a matrix in the row direction and the column direction in the display area,
A plurality of scanning lines extending in a row direction of the pixel electrode array;
A plurality of data lines extending in a column direction of the pixel electrode array;
A plurality of display switching elements that are respectively connected to the pixel electrodes and that apply predetermined potentials to the pixel electrodes based on signals applied to the scanning lines and the data lines;
At least one of the scanning line and the data line is connected to one inspection pad via a switching element for inspection in a peripheral area outside the display area,
An active matrix substrate having a photoelectric element which operates by being irradiated with light, which controls on / off of the inspection switching element, in the peripheral region.   The active matrix substrate according to claim 1, wherein an output voltage generated by the photoelectric element when irradiated with light is used as an ON voltage for conducting the inspection switching element.   2. The active matrix substrate according to claim 1, wherein when the light is irradiated, the photoelectric element is turned on to apply a control power supply voltage as an ON voltage to the inspection switching element.   4. The device according to claim 1, further comprising an element mounting area in which a driving semiconductor element for performing display in the display area is mounted in the peripheral area, and the photoelectric element is formed in the element mounting area. The active matrix substrate according to item.   A liquid crystal display panel comprising a liquid crystal layer between the active matrix substrate according to claim 1 and a counter substrate. A plurality of pixel electrodes arranged in a matrix in the row direction and the column direction in the display area,
A plurality of scanning lines extending in a row direction of the pixel electrode array;
A plurality of data lines extending in a column direction of the pixel electrode array;
A plurality of display switching elements that are respectively connected to the pixel electrodes and that apply predetermined potentials to the pixel electrodes based on signals applied to the scanning lines and the data lines;
In the inspection method of the active matrix substrate, wherein a plurality of the scanning lines or the data lines are connected to the inspection pads formed in the peripheral area outside the display area via the inspection switching elements.
The photoelectric switching element formed in the peripheral region is irradiated with light to control on / off of the inspection switching element, and the display switching element to be measured connected to the inspection pad is sequentially switched. An active matrix substrate inspection method.   The method for inspecting an active matrix substrate according to claim 6, wherein an output voltage generated by the photoelectric element when irradiated with light is used as an on-voltage for conducting the inspection switching element.   The method for inspecting an active matrix substrate according to claim 6, wherein when the light is irradiated, the photoelectric element is turned on to apply a control power supply voltage as an ON voltage to the inspection switching element.   The method for inspecting an active matrix substrate according to claim 6, wherein the photoelectric element is irradiated with light through an optical fiber.   The method for inspecting an active matrix substrate according to claim 9, wherein a tip portion of the optical fiber on the photoelectric element side has a convex curved shape.

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