JP2007003982A - Electrooptical apparatus and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily find a defective pixel in a small-sized panel of an electrooptical apparatus, such as, for example, a liquid crystal device. <P>SOLUTION: The electrooptical apparatus includes a plurality of scanning lines and a plurality of data lines which are wired in pixel array regions on a substrate, a plurality of pixel sections which are disposed in correspondence to the intersections of the plurality of scanning lines and the plurality of data lines, a plurality of analog buffers which are disposed by one each in correspondence to every data line group defining N (N is a natural number of 2 or higher) data lines of the plurality of the data lines as one group and amplify the potential of inspection signals supplied from the pixel sections via the data lines. Further, the apparatus includes a data line selecting means for electrically connecting one data line to be inspected among the N data lines selectively to the one corresponding analog buffer for every data line group and an analog buffer selecting means for selecting the output from the one analog buffer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technical field of an electro-optical device such as a liquid crystal device and an electronic apparatus including the same.

  Conventionally, display devices such as liquid crystal devices are widely used in devices such as mobile phones and projectors. 2. Description of the Related Art A liquid crystal display device using a TFT (Thin Film Transistor) or the like is configured by adhering a TFT substrate and a counter substrate and sealing liquid crystal between the substrates. In general, an inspection of whether a manufactured liquid crystal device operates normally is performed on a finished product. For example, a predetermined image signal is input to the liquid crystal device as display data, and is projected, displayed, or the like to check whether the data is correctly displayed or whether there is a defective pixel.

  However, the method of inspecting a finished product is not preferable from the viewpoint of manufacturing process management. The reason is that a defective product is found after the substrate manufacturing process, so that the detection of the defective product is delayed.

  For this reason, the time until failure detection for process management is fed back becomes longer. As a result, the yield reduction period becomes longer and the manufacturing cost increases. Also, in the case of a prototype, since the period of time from the evaluation of the prototype to the feedback to the design is prolonged, the development period is prolonged and the development cost is increased. Furthermore, after the product is completed, so-called repair, that is, repair of a defective portion is difficult.

  Therefore, it is desired to find a defect, particularly a defective pixel of a display device, in the manufacturing process of the substrate.

  As one of such inspection methods, for example, Patent Document 1 proposes a pixel inspection method using an analog buffer in a large panel having a liquid crystal element.

JP 2003-114658 A

  However, in the inspection method disclosed in Patent Document 1, one analog buffer for reading out a pixel signal is required for each data line. Therefore, the area required for providing one analog buffer on the substrate is as much as the number of data lines. For this reason, the inspection method disclosed in Patent Document 1 is applicable to a large panel, but is not suitable for inspection of a pixel in a small electro-optical device having a small area on the substrate. There is.

  The present invention has been made in view of the above-described problems, for example, and an electro-optical device capable of easily finding a defective pixel even in a small panel and various electronic apparatuses including such an electro-optical device. It is an issue to provide.

  In order to solve the above-described problem, an electro-optical device according to an aspect of the invention crosses a plurality of scanning lines and a plurality of data lines wired in a pixel array region on a substrate, and the plurality of data lines and the plurality of scanning lines. And a plurality of pixel portions provided corresponding to each of the data lines, and N data lines adjacent to each other (where N is a natural number of 2 or more) among the plurality of data lines. A plurality of analog buffers for amplifying the potential of a test signal supplied from the pixel portion via the data line, and a test among the N data lines for each data line group. A data line selection means for selectively connecting one data line to be electrically connected to a corresponding one of the plurality of analog buffers, and an analog buffer selection for selecting an output from the one analog buffer. And means.

  According to the electro-optical device of the present invention, during the operation, an image signal is supplied to each pixel unit via the data line by, for example, an X-driver circuit. At the same time, a scanning signal is supplied to each pixel unit via the scanning line by the Y-driver circuit. For example, a thin film transistor for pixel switching (hereinafter referred to as “TFT” as appropriate) provided for each pixel portion has a gate connected to a scanning line, and selectively supplies an image signal to a pixel electrode in accordance with the scanning signal. To do. Accordingly, for example, by driving an electro-optical material such as liquid crystal sandwiched between the pixel electrode and the counter electrode in each pixel portion, active matrix driving is possible. At this time, the storage capacitor improves the potential holding characteristic in the pixel portion, and the display can have high contrast.

  In the present invention, in particular, one data line group is provided corresponding to each data line group including N data lines adjacent to each other among a plurality of data lines, and supplied from the pixel portion via the data lines. A plurality of analog buffers for amplifying the potential of the inspection signal are provided. The analog buffer is used to amplify the inspection signal at the time of inspection performed prior to the operation of the electro-optical device. Such inspection is preferably performed before a pair of substrates are bonded to each other by the electro-optical device, for example, when a substrate called an element array substrate, an element substrate, or a TFT array substrate is completed. Is done.

  More specifically, at the time of this inspection, for example, first, an inspection signal is supplied to the storage capacitor of the pixel portion.

  Next, the pixel switching TFT provided for each pixel portion is turned off.

  Next, a refresh signal is supplied to refresh the potentials of the plurality of data lines to 0 V, that is, the potential is 0 V. At this time, since the pixel switching TFT is in an OFF state, the inspection signal supplied to the storage capacitor of the pixel portion is held as it is.

  Next, for each data line group, one of the N data lines to be inspected is selectively transferred to the corresponding one of the plurality of analog buffers by the data line selecting means. Connected to. In other words, the plurality of analog buffers are electrically connected to only one data line to be inspected among the N data lines by the data line selection means. Typically, for each data line group, N data lines are sequentially connected to one corresponding analog buffer as one data line to be inspected in the order in which the data lines are arranged. At this time, all the pixel switching TFTs remain in the OFF state.

  Next, one of the plurality of analog buffers is selected by the analog buffer selection means as an analog buffer for inspecting the pixel portion via one data line to be inspected. Typically, the plurality of analog buffers are sequentially selected in the arrangement order of the plurality of analog buffers or the plurality of data lines. The selected analog buffer is electrically connected to, for example, a pad (PAD) on the substrate or an external circuit connection terminal provided for inspection. Then, one data line to be inspected is electrically connected to an inspection circuit provided outside the substrate via a pad on the substrate, for example, via an inspection probe. At this time, a reference output signal is output to the inspection circuit from one data line to be inspected. The reference output signal is a potential signal obtained by changing the refresh signal supplied in advance to the data line due to the influence of, for example, the wiring capacity of the data line, and usually has a potential slightly different from 0V.

  Next, the potential difference between the potential of the reference output signal thus output and the reference potential is output by, for example, an inspection circuit and stored in, for example, a memory. The reference potential is an arbitrary potential that serves as a reference in the inspection.

  Next, the pixel switching TFT is turned on, and a test output signal is output to the data line in the storage capacitor. The inspection output signal is a signal that is output reflecting the result of discharge of the inspection signal in a storage capacitor or the like. At this time, the inspection output signal is output to the inspection circuit via the analog buffer. The potential difference between the potential of the output inspection output signal and the reference potential is output by the inspection circuit and stored in, for example, a memory. Here, the analog buffer is an amplifier circuit composed of a plurality of inverter circuits, for example, and amplifies the test output signal. The analog buffer may have a structure using an operational amplifier (differential amplifier circuit) or may be a source follower type. Other known circuit configurations may be used freely.

  Next, the quality of the pixel portion is determined by the inspection circuit based on the potential difference between the potential of the reference output signal and the reference potential and the potential difference between the potential of the inspection output signal and the reference potential. For example, if the potential difference between the potential of the reference output signal and the reference potential and the potential difference between the potential of the inspection output signal and the reference potential are the same potential difference, for example, it is determined that a leak has occurred in the storage capacitor of the pixel unit or the pixel switching TFT. Is done. As described above, since the test output signal is amplified by the analog buffer, it can be detected even if the leakage generated in the storage capacitor of the pixel unit or the pixel switching TFT is very small.

  The above inspection is performed for each scanning line and each data line.

  In the present invention, in particular, a plurality of analog buffers are provided in correspondence with each data line group including N data lines adjacent to each other among the plurality of data lines (where N is a natural number of 2 or more). It is provided one by one. At the time of inspection, the plurality of analog buffers are electrically connected to only one data line to be inspected among the N data lines, and one analog buffer of the plurality of analog buffers is connected to the pixel portion. By being selected by the analog buffer selection means as an analog buffer to be inspected, for example, it is electrically connected to a pad on the substrate. One pixel line to be inspected is electrically connected to an inspection circuit provided outside the substrate via a pad on the substrate, so that the pixel portion can be inspected. That is, a plurality of analog buffers are shared by N data lines, and are electrically connected to only one data line to be inspected, and are sequentially selected as analog buffers to be inspected one by one, for example. As a result, the pixel portion can be inspected. Therefore, the number of necessary analog buffers can be reduced as compared with the case where one analog buffer is provided for each data line. Therefore, the area of the region on the substrate necessary for providing the analog buffer can be reduced. That is, for example, when two data lines are made into one group, the area of the region on the substrate necessary for providing the analog buffer is smaller than that in the case where one analog buffer is provided for each data line. 1/2. Therefore, for example, for small liquid crystal device applications up to several inches diagonal, even when the area of the region on the substrate is small, inspection with an analog buffer can be performed, and the electro-optical device can be miniaturized. It becomes. Alternatively, the area of the region on the substrate necessary for providing one analog buffer can be increased without changing the area of the region on the substrate. Therefore, for example, by increasing the area of the gate of the TFT constituting the analog buffer, the amplification capability of each of the plurality of analog buffers can be increased.

  As described above, according to the electro-optical device of the present invention, a defective pixel can be easily found even in an electro-optical device having a small liquid crystal panel or the like. In addition, since the quality of the pixel portion can be determined at a relatively early stage in various manufacturing processes, the yield of electro-optical devices such as liquid crystal devices can be increased, and the manufacturing cost can be reduced.

  In one aspect of the electro-optical device of the present invention, the data line selection unit is provided in a region between the pixel array region and the analog buffer on the substrate surface on the substrate, and is in the middle of the plurality of data lines. A plurality of first changeover switches electrically connected to each other, and a first changeover means for turning on and off the first changeover switch.

  According to this aspect, for example, when inspecting the quality of the pixel portion, the first changeover switch is switched to the on state, thereby conducting between one data line to be inspected and one analog buffer corresponding thereto. Is possible. Each of the plurality of first changeover switches is turned on and off by the first changeover means. By turning on the first changeover switch corresponding to one data line to be inspected by the first switching means, conduction between one data line to be inspected and one analog buffer corresponding thereto is conducted. it can.

  In another aspect of the electro-optical device of the present invention, an analog buffer selection unit is provided for each analog buffer, and electrically connects the analog buffer and an inspection circuit for inspecting the quality of the pixel unit. A plurality of second changeover switches, and second changeover means for turning on and off the second changeover switch.

  According to this aspect, for example, when inspecting the quality of the pixel portion, the analog buffer and the inspection circuit can be made conductive by switching the second changeover switch to the ON state. At this time, each of the plurality of second change-over switches is turned on and off sequentially from the end, for example, by a second change-over means including a shift register, for example. One data line and inspection circuit to be inspected by turning on a second changeover switch corresponding to one analog buffer electrically connected to, for example, one data line to be inspected by the second switching means It is possible to conduct between them.

  In order to solve the above problems, an electronic apparatus according to the present invention includes the above-described electro-optical device according to the present invention (including various aspects thereof).

  Since the electronic apparatus of the present invention includes the above-described electro-optical device of the present invention, a projection display device, a television, a mobile phone, an electronic notebook, a word processor, a view capable of performing high-quality image display. Various electronic devices such as a finder type or a monitor direct-view type video tape recorder, a workstation, a videophone, a POS terminal, and a touch panel can be realized. In addition, as an electronic apparatus of the present invention, for example, an electrophoretic device such as electronic paper, an electron emission device (Field Emission Display and a Conduction Electron-Emitter Display), an electrophoretic device, and a device using the electron emission device, DLP (Digital Light Processing) and the like can also be realized. In addition, since such an electronic apparatus includes the above-described electro-optical device, the yield is improved.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, a driving circuit built-in type TFT active matrix driving type liquid crystal device, which is an example of the electro-optical device of the present invention, is taken as an example.

(First embodiment)
First, the overall configuration of the liquid crystal device according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a plan view showing the overall configuration of the liquid crystal device according to this embodiment, and FIG. 2 is a cross-sectional view taken along the line HH ′ of FIG.

  1 and 2, in the liquid crystal device according to the present embodiment, a TFT array substrate 10 and a counter substrate 20 are arranged to face each other. A liquid crystal layer 50 is sealed between the TFT array substrate 10 and the counter substrate 20, and the TFT array substrate 10 and the counter substrate 20 are included in an image display region 10a as an example of the “pixel array region” according to the present invention. They are bonded to each other by a sealing material 52 provided in a surrounding sealing region.

  In FIG. 1, a light-shielding frame light-shielding film 53 that defines the frame area of the image display region 10a is provided on the counter substrate 20 side in parallel with the inside of the seal region where the sealing material 52 is disposed. An X-driver circuit 101 and an external circuit connection terminal 102 are provided along one side of the TFT array substrate 10 in a region located outside the seal region where the seal material 52 is disposed in the peripheral region. The sampling circuit 110 is provided so as to be covered with the frame light shielding film 53 on the inner side of the seal region along the one side. The Y-driver circuit 104 is provided so as to be covered with the frame light-shielding film 53 inside the seal region along two sides adjacent to the one side. On the TFT array substrate 10, vertical conduction terminals 106 for connecting the two substrates with the vertical conduction material 107 are arranged in regions facing the four corner portions of the counter substrate 20. Thus, electrical conduction can be established between the TFT array substrate 10 and the counter substrate 20.

  On the TFT array substrate 10, a lead wiring 90 is formed for electrically connecting the external circuit connection terminal 102 to the X-driver circuit 101, the Y-driver circuit 104, the vertical conduction terminal 106, and the like. .

  In FIG. 2, on the TFT array substrate 10, a laminated structure in which wiring such as a pixel switching TFT (Thin Film Transistor) as a driving element, a scanning line, and a data line is formed. In the image display area 10a, a pixel electrode 9a is provided in an upper layer of wiring such as a pixel switching TFT, a scanning line, and a data line. An alignment film is formed on the pixel electrode 9a. On the other hand, on the counter substrate 20, in addition to the counter electrode 21, a lattice-shaped or striped light-shielding film 23 and an alignment film are formed on the uppermost layer portion. The liquid crystal layer 50 is made of, for example, a liquid crystal in which one or several types of nematic liquid crystals are mixed, and takes a predetermined alignment state between the pair of alignment films.

  As shown in FIGS. 1 and 2, in this embodiment, in particular, the inspection switch driving shift register 220 is provided on the opposite side of the X-driver circuit 101 across the image display region 10a on the TFT array substrate 10. A test enable switch (not shown), a test enable circuit, wiring, etc., which will be described in detail below, are provided.

  Next, the circuit configuration of the liquid crystal device according to the present embodiment will be described with reference to FIGS. FIG. 3 is a circuit diagram showing the electrical configuration of the liquid crystal device according to this embodiment. FIG. 4 is a circuit diagram showing an electrical configuration of the pixel portion. FIG. 5 is a circuit diagram showing an electrical configuration of the analog buffer. FIG. 6 is a circuit diagram showing an electrical configuration of the test enable circuit. FIG. 7 is a circuit diagram showing an electrical configuration of the pull-down circuit. 3 shows a circuit diagram in which the top and bottom are reversed with respect to the plan view shown in FIG.

  3, the liquid crystal device according to the present embodiment includes a plurality of scanning lines Gj (j = 1, 2,... N) and a plurality of data lines Si (i = 1, 2,...) On the TFT array substrate 10. , M), a Y-driver circuit 104, an X-driver circuit 101, a sampling circuit 110, and a plurality of pixel units 70 are provided.

  The plurality of scanning lines Gj and the plurality of data lines Si are wired so as to intersect the image display region 10a.

  The Y-driver circuit 104 sequentially supplies a switching signal for each scanning line when the pixel unit 70 is inspected. Here, the switching signal is a signal different from an image display scanning signal supplied to the pixel unit 70 when displaying an image, and the pixel unit 70 outputs an inspection output signal described later from the pixel unit 70. This is a signal for switching on the TFT included in 70.

  The X-driver circuit 101 supplies a sampling signal to the sampling switch 111 that constitutes the sampling circuit 110, and switches the sampling switch 111 to an on state. Here, the “sampling signal” refers to the sampling circuit 110 from the X-driver circuit 101 in order to supply a refresh signal, an inspection signal, etc., which will be described later, to the data line Si through the image signal line 112 when inspecting. Is a signal supplied to.

  The sampling circuit 110 includes a plurality of sampling switches 111, and the sampling switch 111 is switched on / off according to the sampling signal supplied from the X-driver circuit 101.

  As shown in FIG. 4, the pixel unit 70 includes a TFT 71, a pixel electrode 9 a, and a storage capacitor 73.

  The TFT 71 has a source electrically connected to the data line Si and a gate electrically connected to the scanning line Gj. The TFT 71 is switched on and off by a switching signal supplied from the Y-driver circuit 104. The pixel unit 70 outputs an inspection output signal to the data line Si. The pixel electrode 9 a sandwiches the liquid crystal between the pixel electrode 9 a and the counter electrode 21 provided on the counter substrate 20. The storage capacitor 73 temporarily holds an image signal supplied to the pixel unit 70 when image display is performed, and enables active matrix driving of the plurality of pixel units 70.

  Referring back to FIG. 3, particularly in the present embodiment, on the TFT array substrate 10, the analog buffer 230, test enable switches 241 and 242 as examples of the “first changeover switch” of the present invention, and the “first switcher” of the present invention. The test enable circuit 210 as an example, the pull-down circuit 35, the inspection switch 250 as an example of the “second changeover switch” of the present invention, and the shift register for driving the inspection switch as an example of the “second changeover means” of the present invention. 220 and PAD (pad or electrode pad) 60 are further provided.

  1 and 2, the PAD 60 may be configured as one of the external circuit connection terminals 102. Alternatively, the PAD 60 may be used as a dedicated pad in the inspection switch driving shift register 220 on the TFT array substrate 10. It may be provided at an adjacent position or the like.

  One analog buffer 230 is provided corresponding to each data line group Grk (k = 1, 2,..., M / 2) composed of two adjacent data lines among a plurality of data lines Si. It has been. The analog buffer 230 is used, for example, to amplify an inspection signal at the time of inspection performed prior to the operation of the liquid crystal device.

  As shown in FIG. 5, the analog buffer 230 includes inverter circuits 231, 232 and 233. The inverter circuits 231, 232 and 233 are cascaded. The analog buffer input terminal 238 is electrically connected to the gates of the TFT 231a and the TFT 231b. The analog buffer output terminal 239 is electrically connected to the drains of the TFTs 233a and 233b. The analog buffer may have a structure using an operational amplifier (differential amplifier circuit) or may be a source follower type. Other known circuit configurations may be used freely.

  In FIG. 3 again, the test enable switches 241 and 242 are provided in a region nearer to the analog buffer 230 when viewed from the pixel unit 70 on the substrate surface on the TFT array substrate. The test enable switches 241 and 242 are provided corresponding to each of the two data lines constituting the data line group Grk, and are turned on according to a test enable signal supplied from a test enable circuit 210 described later. Can be switched. By switching the test enable switches 241 and 242 to the ON state, for each data line group Grk, one data line Si to be inspected, which will be described later, and one analog buffer 230 corresponding thereto are brought into conduction.

  The test enable circuit 210 is electrically connected to the gates of the test enable switches 241 and 242 via test enable wirings T1 and T2, respectively, and outputs a test enable signal.

  As shown in FIG. 6, the test enable circuit 210 includes TFTs 211, 212 and 213, an inverter 215, and an external connection terminal 219.

  The drain of the TFT 213 is electrically connected to the drains of the TFTs 211 and 212. The TFT 213 is used to turn on the TFTs 211 and 212 when inspecting, and to turn off the TFTs 211 and 212 when not inspecting.

  The drains of the TFTs 211 and 212 are electrically connected to the test enable wirings T1 and T2, respectively. The sources are electrically connected to the external connection terminals 219, respectively, and are electrically connected to the external power supply circuit at the time of inspection.

  The inverter 215 is provided in the middle of the external connection terminal 219 and the source of the TFT 212. For this reason, inverted potentials are supplied to the sources of the TFTs 211 and 212. That is, at the time of inspection, power is supplied to only one of the test enable wirings T1 and T2, and only one of the above-described test enable switches 241 and 242 is turned on. Therefore, the test enable signal is supplied to only one of the test enable wirings T1 and T2.

  In FIG. 3 again, the pull-down circuit 35 stabilizes the potentials of the test enable lines T1 and T2 so that the test enable signals supplied to the test enable switches 241 and 242 via the test enable lines T1 and T2 do not fluctuate. .

  As shown in FIG. 7, the pull-down circuit 35 includes a TFT 135 having a gate electrically connected to the power supply VDD, a grounded source, and a drain electrically connected to the test enable wiring T1 or T2. Thus, fluctuations in the potentials of the test enable lines T1 and T2 when the test enable signal is supplied are reduced.

In FIG. 3 again, a test switch 250 is provided for each analog buffer 230, and the analog buffer 230 and a test PAD 60 described later are driven by a test switch driven from a test switch drive shift register 220 described later. Electrical connection is made according to the signal.
At the time of inspection, the inspection can be performed by electrically connecting the analog buffer 230 and the inspection circuit 300 for inspecting the quality of the pixel unit 70 via the PAD 60.

  The inspection switch driving shift register 220 sequentially outputs inspection switch driving signals to the inspection switch 250 at the time of inspection.

  The PAD 60 is provided to connect to the external inspection circuit 300 at the time of inspection, and is electrically connected to the inspection switch 250 as described above.

  Next, with reference to FIG. 3 and FIG. 4, a procedure for inspecting the pixel portion of the liquid crystal device according to the present embodiment will be described. The inspection of the pixel portion is preferably performed before the TFT array substrate 10 and the counter substrate 20 are bonded to each other in the liquid crystal device.

  3 and 4, at the time of this inspection, for example, first, an inspection signal is supplied to the storage capacitor 73 of the pixel unit 70.

  Next, the pixel switching TFT 71 provided for each pixel unit 70 is turned off.

  Next, a refresh signal is supplied to refresh the potential of the plurality of data lines Si to 0V, that is, the potential is 0V. At this time, since the pixel switching TFT 71 is in the OFF state, the inspection signal supplied to the storage capacitor 73 of the pixel unit 70 is held as it is.

  Next, for each data line group Grk, the test enable switch 241 or 242 is turned on / off according to the test enable signal supplied from the test enable circuit 210, so that the plurality of analog buffers 230 have two data lines. Of these, only one data line Si to be inspected is electrically connected. In the present embodiment, for each data line group Grk, two data lines are sequentially connected to one analog buffer 230 corresponding to one data line Si to be inspected in the order of arrangement of the data lines Si. At this time, all the pixel switching TFTs 71 remain in the OFF state.

  Next, one of the plurality of analog buffers 230 is supplied from the inspection switch driving shift register 220 as the analog buffer 230 for inspecting the pixel unit 70 through one data line Si to be inspected. When the inspection switch 250 is turned on / off according to the inspection switch drive signal, the PAD 60 is electrically connected. In the present embodiment, the plurality of analog buffers 230 are electrically connected to the PAD 60 sequentially in the arrangement order of the plurality of analog buffers 230 or the plurality of data lines Si. At this time, as a selection procedure of the analog buffer 230 by the inspection switch driving shift register 220, (i) the odd-numbered test enable switch 241 is turned on by the output T1 of the TE circuit, and the inspection switch driving shift register 220 The odd-numbered data lines Si are sequentially selected, and then the even-numbered test enable switches 242 are turned on by the output T2 of the TE circuit, and the even-numbered data lines Si are sequentially switched by the inspection switch driving shift register 220. (Ii) The test enable switches 241 and 242 are sequentially turned on for one data line set Gr, and then the shift operation by the test switch driving shift register 220 is performed. For sequential inspection switch drive for set Gr A step of performing a shift operation by the shift register 220 can be applied two methods of. Then, one data line Si to be inspected is electrically connected to the inspection circuit 300 provided outside the TFT array substrate 10 via the PAD 60 on the TFT array substrate 10. At this time, a reference output signal is output to the inspection circuit 300 from one data line Si to be inspected. The reference output signal is a potential signal obtained by changing the refresh signal supplied in advance to the data line Si due to the influence of the wiring capacity of the data line Si, for example, and usually has a potential slightly different from 0V.

  Next, the potential difference ΔVro ′ (that is, Vro−V0) between the reference output signal potential Vro and the reference potential V0 output in this way is output by the inspection circuit 300 and stored in the memory 310. The reference potential V0 is an arbitrary potential that serves as a reference in the inspection.

  Next, the pixel switching TFT 71 is turned on, and an inspection output signal is output to the storage capacitor 73 to the data line Si. The inspection output signal is a signal that is output reflecting the result of discharge of the inspection signal in the storage capacitor 73 or the like. At this time, the inspection output signal is output to the inspection circuit 300 via the analog buffer 230. A potential difference ΔVinso ′ (that is, Vinso−V0) between the potential Vinso of the output inspection output signal and the reference potential V0 is output by the inspection circuit 300 and stored in the memory 310. Here, the analog buffer 230 is an amplifier circuit composed of a plurality of inverter circuits 231, 232, and 233 as described above with reference to FIG. 5, and amplifies the test output signal. The analog buffer 230 may have a structure using an operational amplifier (differential amplifier circuit) or may be a source follower type. Other known circuit configurations may be used freely.

  Next, based on the potential difference ΔVro ′ between the reference output signal potential Vro and the reference potential V0, and the potential difference ΔVinso ′ between the inspection output signal potential Vinso and the reference potential V0, the inspection circuit determines the quality of the pixel portion. For example, if the potential difference ΔVro ′ between the potential of the reference output signal and the reference potential and the potential difference ΔVinso ′ between the potential of the test output signal and the reference potential are the same potential difference (that is, ΔVro ′ = ΔVinso ′), for example, the storage capacitor 73 of the pixel unit 70. Alternatively, it is determined that a leak occurs in the pixel switching TFT 71. Here, in this embodiment, since the inspection output signal is amplified by the analog buffer 230 as described above, it is assumed that, for example, a leak generated in the storage capacitor 73 of the pixel unit 70 or the TFT 71 for pixel switching is very small. Can also be detected.

  The above inspection is performed for each scanning line Gj and each data line Si.

  In FIG. 3, in the present embodiment, in particular, the plurality of analog buffers 230 are provided one by one for each data line Grk group in which two adjacent data lines among a plurality of data lines Si are taken as one group. It has been. At the time of inspection, the plurality of analog buffers 230 are electrically connected to only one data line Si to be inspected among the two data lines, and one of the plurality of analog buffers 230 has one analog buffer 230. The analog buffer 230 for inspecting the pixel unit 70 is electrically connected to the PAD 60. One data line Si to be inspected is electrically connected to an inspection circuit 300 provided outside the TFT array substrate 10 via the PAD 60, whereby the pixel portion 70 can be inspected. . That is, the plurality of analog buffers 230 are respectively shared by the two data lines Si, and are electrically connected to only one data line Si to be inspected, and one analog buffer 230 for performing inspection. By sequentially selecting, the pixel portion 70 can be inspected. Therefore, the number of necessary analog buffers 230 can be reduced as compared with the case where one analog buffer 230 is provided for each data line Si. Therefore, the area of the region on the TFT array substrate 10 necessary for providing the analog buffer 230 can be small. That is, in this embodiment, the area of the region on the TFT substrate necessary for providing the analog buffer 230 is ½ compared to the case where one analog buffer 230 is provided for each data line. Therefore, even when the area of the region on the TFT array substrate is small, the inspection by the analog buffer 230 can be performed, and the liquid crystal device can be downsized. Alternatively, the area of the region on the TFT array substrate 10 necessary for providing one analog buffer 230 can be increased without changing the area of the region on the TFT array substrate 10. For example, even in the case of a small liquid crystal device having a diagonal size of 10 inches or less and a diagonal number of inches or less, it is possible to secure a region where the analog buffer 230 is provided while preventing an increase in the size of the substrate. Therefore, for example, by increasing the area of the gate of the TFT constituting the analog buffer 230, the amplification capability of each of the plurality of analog buffers 230 can be increased. The analog buffer 230 may be provided for each data line group Grk having three or four or more adjacent data lines as one group. By doing so, compared to the case where one analog buffer 230 is provided for each data line Si, the area of the region on the TFT substrate 10 necessary for providing the analog buffer 230 is 1/3 or 1/4. The following is enough.

  In addition, if the area for forming the analog buffer can be increased, variation in ion implantation into the semiconductor layer can be reduced when forming the transistor constituting the analog buffer 230, so that a transistor with no variation in performance is formed. can do.

  As described above, according to the liquid crystal device of the present embodiment, a defective pixel can be easily found even in a liquid crystal device having a small liquid crystal panel. In addition, since the quality of the pixel unit 70 can be determined at a relatively early stage in various manufacturing processes, the yield of the liquid crystal device can be increased, and the manufacturing cost can be reduced.

(Electronics)
Next, the case where the liquid crystal device which is the above-described electro-optical device is applied to various electronic devices will be described.

  First, a projector using this liquid crystal device as a light valve will be described. FIG. 8 is a plan view showing a configuration example of the projector. As shown in FIG. 8, a projector 1100 includes a lamp unit 1102 made of a white light source such as a halogen lamp. The projection light emitted from the lamp unit 1102 is separated into three primary colors of RGB by four mirrors 1106 and two dichroic mirrors 1108 arranged in the light guide 1104, and serves as a light valve corresponding to each primary color. The light enters the liquid crystal panels 1110R, 1110B, and 1110G.

  The configurations of the liquid crystal panels 1110R, 1110B, and 1110G are the same as those of the liquid crystal device described above, and are driven by R, G, and B primary color signals supplied from the image signal processing circuit. The light modulated by these liquid crystal panels enters the dichroic prism 1112 from three directions. In this dichroic prism 1112, R and B light is refracted at 90 degrees, while G light travels straight. Accordingly, as a result of the synthesis of the images of the respective colors, a color image is projected onto the screen or the like via the projection lens 1114.

  Here, paying attention to the display images by the liquid crystal panels 1110R, 1110B, and 1110G, the display image by the liquid crystal panel 1110G needs to be horizontally reversed with respect to the display images by the liquid crystal panels 1110R, 1110B.

  Note that since light corresponding to the primary colors R, G, and B is incident on the liquid crystal panels 1110R, 1110B, and 1110G by the dichroic mirror 1108, it is not necessary to provide a color filter.

  Next, an example in which the liquid crystal device is applied to a mobile personal computer will be described. FIG. 9 is a perspective view showing the configuration of this personal computer. In FIG. 9, the computer 1200 includes a main body 1204 having a keyboard 1202 and a liquid crystal display unit 1206. The liquid crystal display unit 1206 is configured by adding a backlight to the back surface of the liquid crystal device 1005 described above.

  Further, an example in which the liquid crystal device is applied to a mobile phone will be described. FIG. 10 is a perspective view showing the configuration of this mobile phone. In FIG. 10, a cellular phone 1300 includes a reflective liquid crystal device 1005 together with a plurality of operation buttons 1302. In the reflective liquid crystal device 1005, a front light is provided on the front surface thereof as necessary.

  In addition to the electronic devices described with reference to FIGS. 8 to 10, a liquid crystal television, a viewfinder type, a monitor direct-view type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, a word processor, a work Examples include a station, a videophone, a POS terminal, a device equipped with a touch panel, and the like. Needless to say, the present invention can be applied to these various electronic devices.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit or concept of the invention that can be read from the claims and the entire specification. An electronic apparatus including the electro-optical device is also included in the technical scope of the present invention.

It is a top view which shows the whole structure of a liquid crystal device. It is sectional drawing of HH 'of FIG. It is a circuit diagram which shows the electrical constitution of a liquid crystal device. It is a circuit diagram which shows the electrical structure of a pixel part. It is a circuit diagram which shows the electrical structure of an analog buffer. It is a circuit diagram which shows the electrical structure of a test enable circuit. It is a circuit diagram which shows the electric constitution of a pull-down circuit. It is a top view which shows the structure of the projector which is an example of the electronic device to which the electro-optical apparatus is applied. 1 is a perspective view showing a configuration of a personal computer as an example of an electronic apparatus to which an electro-optical device is applied. It is a perspective view which shows the structure of the mobile telephone which is an example of the electronic device to which the electro-optical apparatus is applied.

Explanation of symbols

  9a ... Pixel electrode, 10 ... TFT array substrate, 10a ... Image display area, 20 ... Counter substrate, 21 ... Counter electrode, 60 ... Memory, 70 ... Pixel part, 101 ... X-driver circuit, 102 ... External circuit connection terminal, 104 ... Y-driver circuit, 210 ... test enable circuit, 220 ... shift switch for inspection switch drive, 230 ... analog buffer, 241,242 ... test enable switch, 250 ... inspection switch, 300 ... inspection circuit, 310 ... memory, Gj ... Scanning line, Grk ... Data line group, Si ... Data line

Claims (4)

A plurality of scanning lines and a plurality of data lines wired in a pixel array region on the substrate;
A plurality of pixel portions provided corresponding to intersections of the plurality of data lines and the plurality of scanning lines;
One of the plurality of data lines is provided corresponding to each data line group including N data lines adjacent to each other (where N is a natural number of 2 or more). A plurality of analog buffers for amplifying the potential of the inspection signal supplied via the data line;
Data line selection means for selectively connecting one data line to be inspected among the N data lines for each data line group and electrically connecting to one corresponding analog buffer among the plurality of analog buffers. When,
An electro-optical device comprising: analog buffer selection means for selecting an output from the one analog buffer. Data line selection means
A plurality of first changeover switches provided in a region between the pixel array region and the analog buffer on the substrate surface on the substrate, and electrically connected respectively in the middle of the plurality of data lines;
The electro-optical device according to claim 1, further comprising: a first switching unit that switches on and off of the first switch. Analog buffer selection means
A plurality of second changeover switches that are provided for each analog buffer and electrically connect the analog buffer and an inspection circuit for inspecting the quality of the pixel unit;
The electro-optical device according to claim 1, further comprising: a second switching unit that switches on and off the second switch. An electronic apparatus comprising the electro-optical device according to any one of claims 1 to 3.

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