JP2007065540A - Electrooptical device and its inspection method, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inspect pixel parts of an electrooptical device such as a liquid crystal device by optionally simulating inspection conditions. <P>SOLUTION: The electrooptical device is equipped with a plurality of pixel parts, a plurality of scanning lines and a plurality of data lines which are wired in a pixel area where the plurality of pixel parts are arrayed, and a scanning line driving circuit including (i) a shift register which outputs transfer signals in sequence and (ii) an output buffer having at lest one buffer circuit to which the sequentially output transfer signals are input and supplying the transfer signals output from the output buffer as scanning signals to the pixel parts through the plurality of scanning lines. Further, a power source provided for a final-stage buffer circuit disposed at the final stage of an output side to the scanning lines among buffer circuits is a power source independent of a power source for the scanning line driving circuit for driving the scanning line driving circuit except the power source for the final-stage buffer circuit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  In this type of electro-optical device, for example, as a liquid crystal device, a plurality of pixel portions connected to a plurality of scanning lines and data lines, a data line driving circuit for driving the data lines, and a scanning line are provided on a substrate. A scanning line driving circuit or the like for driving is built in.

  As one of the inspections of the pixel portion, there is an inspection method in which the pixel portion is inspected by applying a voltage to the pixel portion using a power source for a scanning line driving circuit during or after assembly of the electro-optical device.

  Here, the scanning line driving circuit has a shift register that sequentially outputs a transfer signal as an original signal of a scanning signal for sequential scanning from each stage. In the electro-optical device, the operating voltage of the scanning line driving circuit constructed as an internal circuit may be lowered to reduce power consumption. In that case, the operation voltage of the above-described shift register is also lowered, and the voltage level of the transfer signal is low. Therefore, as disclosed in Patent Document 1 by the applicant of the present application, a buffer circuit for setting the transfer signal of the shift register to a high voltage level and a matrix driving voltage is provided on the output side of the shift register.

JP 2004-139111 A

  However, according to the conventional inspection method described above, the inspection can be performed only within the range of the power source for the scanning line driving circuit. For this reason, there is a technical problem that it is impossible to perform an inspection assuming that power outside the range of the power supply for the scanning line driving circuit is supplied. In addition, for example, in order to perform an inspection under a high temperature environment, there is a technical problem that the electro-optical device must actually be installed and inspected in a high temperature environment.

  The present invention has been made in view of the above-described problems, for example, an electro-optical device that enables inspection of a pixel portion by arbitrarily simulating severe inspection conditions such as in a high-temperature environment, and an inspection method thereof, and It is an object of the present invention to provide various electronic apparatuses including the electro-optical device.

  In order to solve the above problems, an electro-optical device of the present invention includes a plurality of pixel portions, a plurality of scanning lines and a plurality of data lines wired in a pixel region in which the plurality of pixel portions are arranged, and (i A shift register that sequentially outputs transfer signals; and (ii) an output buffer having at least one buffer circuit to which the sequentially output transfer signals are input, and the transfer signals output from the output buffer are scanned signals. As a final line supplied to a final stage buffer circuit located in the final stage on the output side to the scanning line in the buffer circuit. The power supply for the stage buffer circuit is a power supply independent from the power supply for the scanning line driving circuit for driving the scanning line driving circuit except for the power supply for the final stage buffer circuit.

  According to the electro-optical device of the invention, during the operation, an image signal and a scanning signal are supplied to the pixel portion via the data line and the scanning line. These image signals and the like are selectively supplied from a switching element such as a pixel switching transistor to a display electrode such as a pixel electrode in the pixel portion, whereby active matrix driving is performed. That is, image display is performed in a pixel area or a pixel array area (or also referred to as an “image display area”) in which a plurality of pixel portions are arranged in a matrix.

  In the electro-optical device of the present invention, the scanning line driving circuit includes a shift register and an output buffer. The shift register sequentially outputs transfer signals, for example, at a timing at which an image signal should be supplied to the pixel unit, and transfers the transfer signals to the output buffer. The output buffer is configured by electrically connecting, for example, inverters as a buffer circuit in a plurality of stages in series, and gives the drive capability to the voltage of the transfer signal transferred from the shift register. The output buffer may function as a level shifter that shifts the voltage level of the transfer signal. In that case, a level shifter circuit is used instead of an inverter. A transfer signal having a driving capability and a further increased voltage is finally supplied as a scanning signal from the scanning line driving circuit to the pixel portion through the scanning line. The output buffer may have a function as a level shifter, a function as a normal output buffer such as waveform shaping and timing adjustment of a transfer signal, in addition to the function of obtaining such driving capability.

  In the present invention, in particular, the power supply for the final stage buffer circuit supplied to the final stage buffer circuit located at the final stage of the output buffer in the buffer circuit drives the scanning line driving circuit except the power supply for the final stage buffer circuit. This power source is independent from the power source for the scanning line driving circuit. Here, the “independent power supply” according to the present invention refers to a power supply that can set or adjust the power supply potential separately. The power supply for the final stage buffer circuit is a scanning line drive except the power supply for the final stage buffer circuit. It is a separate power source or a different power source from the circuit power source. Therefore, for example, when inspecting or evaluating an electro-optical device, what is a power source for normal driving potential in addition to or instead of a power source for normal driving, that is, a scanning line driving circuit power source? Different potential power sources can also be supplied. In other words, in addition to or instead of the normal driving conditions, the pixel portion can be inspected or evaluated under conditions that are stricter or have a margin than the normal driving conditions. For example, the electrical conditions in the pixel portion under a high temperature environment can be simulated by changing the potential of the power supply for the final stage buffer circuit beyond the operating range of the power supply for the scanning line driving circuit. Such inspection or evaluation of the pixel portion is very convenient in practice when selecting or screening a product in mass production. Alternatively, by changing the potential of the power supply for the final stage buffer circuit, for example, the gate potential of the pixel switching transistor in the pixel portion can be arbitrarily changed, and for pixel switching in a state mounted in the electro-optical device. It becomes possible to measure or evaluate the static characteristics of the transistor. Thus, the measurement or evaluation of the static characteristics of the pixel portion is very convenient in practice, particularly when measuring or evaluating at the time of prototyping.

  As described above, according to the electro-optical device of the present invention, it is possible to arbitrarily change the power supply for the final stage buffer circuit. Therefore, the pixel can be simulated by arbitrarily simulating severe inspection conditions such as in a high temperature environment. The part can be inspected or evaluated.

  In one aspect of the electro-optical device of the present invention, the voltage of the power supply for the final stage buffer circuit is variable when a scanning signal is supplied to the pixel unit in the inspection process of the pixel unit.

  According to this aspect, when the pixel portion is inspected, by changing the voltage of the power supply for the final stage buffer circuit, the pixel portion is inspected or evaluated by arbitrarily simulating severe inspection conditions such as in a high temperature environment. Can do.

  In another aspect of the electro-optical device of the invention, the buffer circuit is formed by electrically connecting a plurality of inverters.

  According to this aspect, the power for the scanning line driving circuit is supplied to the inverters other than the inverter constituting the final stage buffer circuit among the plurality of inverters. Therefore, for example, by simply providing an external circuit connection terminal and power supply wiring for supplying the power for the final stage buffer circuit from an external circuit, for example, the pixel part is inspected by arbitrarily simulating severe inspection conditions such as in a high temperature environment. Or it can be evaluated.

  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 Conduction Electron-Emitter Display), and a display device using these electrophoretic device and electron emission device are realized. Is also possible.

  In order to solve the above problems, an electro-optical device inspection method of the present invention includes a plurality of pixel portions, a plurality of scanning lines and a plurality of data lines wired in a pixel region in which the plurality of pixel portions are arranged. (I) a shift register that sequentially outputs transfer signals; and (ii) an output buffer having at least one buffer circuit to which the sequentially output transfer signals are input, and the transfer signal output from the output buffer. Is supplied to the final stage buffer circuit located in the final stage on the output side to the scanning line in the buffer circuit. The final stage buffer circuit power supply is connected to an electro-optical device which is a power source independent of the scanning line drive circuit power supply for driving the scanning line drive circuit except for the final stage buffer circuit power supply. And changing the voltage of the power supply for the final stage buffer circuit in order and supplying the pixel unit with the inspection condition, and whenever the inspection site is changed in the inspection condition changing step, And an inspection step for inspecting static characteristics.

  According to the inspection method of the electro-optical device of the present invention, first, in the inspection condition changing step, the final buffer circuit power source that simulates severe inspection conditions such as in a high temperature environment in the pixel portion of the above-described electro-optical device of the present invention. Supply. More specifically, for example, the gate potential of the pixel switching transistor in the pixel portion is set to be lower than the power supply potential during normal driving, that is, the potential of the power supply for the scanning line driving circuit. At this time, since the power supply for the final stage buffer circuit is a power supply independent of the power supply for the scanning line drive circuit excluding the power supply for the final stage buffer circuit, it can be easily set to a potential lower than that of the power supply for the scanning line drive circuit. Can be set to Therefore, in the inspection step, for example, the electrical static characteristics of the pixel switching transistor can be inspected under severe inspection conditions such as a high temperature environment in the pixel portion. By alternately and repeatedly performing the inspection condition changing step and the inspection step described above, for example, the inspection condition can be arbitrarily simulated to inspect or evaluate the pixel portion. Such an inspection method is very convenient in practice when evaluating the pixel portion at the time of prototyping and selecting or screening a product at the time of mass production.

  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>
The liquid crystal device according to the first embodiment will be described with reference to FIGS.

  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 configuration of the liquid crystal device according to this embodiment. 2 is a cross-sectional view taken along 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 surrounded by an image display region 10a as an example of the “pixel region” according to the present invention. Are adhered to each other by a sealing material 52 made of, for example, a photo-curing resin, provided in a sealing region located in the area.

  In FIG. 1, a light-shielding frame light-shielding film 53 that defines the periphery of the image display region 10 a is provided on the counter substrate 20 side in parallel with the inside of the seal region 52 a where the sealing material 52 is disposed. A data line driving 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 sealing region in which the sealing material 52 is disposed in the peripheral region. The sampling circuit 7 is provided so as to be covered with the frame light-shielding film 53 in the frame area inside the seal area along one side. Further, in order to connect the two scanning line driving circuits 104 provided on both sides of the image display area 10 a in this way, a plurality of the pixel lines are covered along the remaining side of the TFT array substrate 10 and covered with the frame light shielding film 53. Wiring 105 is provided. Further, the scanning line driving circuit 104 is provided in a frame region inside the seal region 52 a along two sides adjacent to this one side so as to be covered with the frame light shielding film 53. 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 data line driving circuit 101, the scanning line driving circuit 104, the vertical conduction terminal 106, and the like. .

  In FIG. 2, on the TFT array substrate 10, a laminated structure in which wirings such as pixel switching TFTs (Thin Film Transistors) serving as drive elements, scanning lines, and data lines are 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. On the other hand, a light shielding film 23 is formed on the surface of the counter substrate 20 facing the TFT array substrate 10. A counter electrode 21 made of a transparent material such as ITO is formed on the light shielding film 23 so as to face the plurality of pixel electrodes 9a. Further, 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.

  Although not shown here, in addition to the data line driving circuit 101 and the scanning line driving circuit 104, the TFT array substrate 10 is used for inspecting the quality, defects, etc. of the liquid crystal device during manufacturing or at the time of shipment. An inspection circuit, an inspection pattern, or the like may be formed.

  Next, the main configuration of the liquid crystal device will be described with reference to FIGS. FIG. 3 is a block diagram showing the configuration of the main part of the liquid crystal device according to this embodiment. FIG. 4 is a block diagram showing an electrical configuration of the pixel portion.

  3, the liquid crystal device according to the present embodiment includes a scanning line driving circuit 104, a data line driving circuit 101, a sampling circuit 7 and the like in a peripheral region located around the image display region 10a on the TFT array substrate 10. The drive circuit is formed.

  As shown in FIG. 3, the scanning line driving circuit 104 receives various control signals such as a Y clock signal CLY (and an inverted Y clock signal CLY ′) and a Y start pulse signal from an external circuit via the external circuit connection terminal 102. Is supplied. As will be described later, the scanning line driving circuit 104 sequentially generates and outputs the scanning signals G1,..., Gm in this order or in the reverse order of the order based on these signals. The scanning line driving circuit 104 has a higher potential VDDY for scanning line driving circuit for driving the scanning line driving circuit 104 via the external circuit connection terminal 102 and a potential higher than that of the high potential power source for scanning line driving. The low potential power supply VSSY for the low scanning line driving circuit, the high potential power supply VDDT for the final stage buffer circuit, which will be described later, and the low potential power supply VSSY for the final stage buffer circuit having a lower potential than the high potential power supply VDDT for the final stage buffer circuit are supplied. Is done.

  In FIG. 3, an X clock signal (and an inverted X clock signal) and an X start pulse are supplied to the data line driving circuit 101 from the external circuit via the external circuit connection terminal 102. When the X start pulse is input, the data line driving circuit 101 sequentially generates and outputs sampling signals S1,..., Sn at a timing based on the X clock signal (and the inverted X clock signal X). Further, the data line driving circuit 101 includes a data line driving circuit high potential power supply VDDX for driving the data line driving circuit 101 via the external circuit connection terminal 102 and the data line driving circuit high potential power supply VDDX. A low potential power supply VSSX for the data line driving circuit having a low potential is supplied.

  The sampling circuit 7 includes a plurality of sampling switches 7 s formed of P-channel or N-channel single-channel TFTs or complementary TFTs.

  In FIG. 3, the liquid crystal device according to the present embodiment is further provided with a plurality of pixel portions 70 arranged in a matrix in the image display region 10a occupying the center of the TFT array substrate.

  As shown in FIG. 4, the pixel unit 70 includes a pixel switching TFT 71, a liquid crystal element 72, and a storage capacitor 73.

  The pixel switching TFT 71 has a source electrically connected to the data line 6a and a gate electrically connected to the scanning line 11a. The pixel switching TFT 71 is switched on and off by a scanning signal supplied from the scanning line driving circuit 104.

  The liquid crystal element 72 includes a pixel electrode 9 a, a counter electrode 21, and a liquid crystal sandwiched between the pixel electrode 9 a and the counter electrode 21. In the liquid crystal element 72, an image signal of a predetermined level written in the liquid crystal via the data line 6a and the pixel electrode 9a is held with the counter electrode 21 for a certain period. The liquid crystal modulates light and enables gradation display by changing the orientation and order of the molecular assembly depending on the applied voltage level. In the normally white mode, the transmittance for incident light is reduced according to the voltage applied in units of each pixel, and in the normally black mode, the light is incident according to the voltage applied in units of each pixel. The light transmittance is increased, and light having a contrast corresponding to the image signal is emitted from the electro-optical device as a whole.

  The storage capacitor 73 is added in parallel with the liquid crystal capacitor formed between the pixel electrode 9a and the counter electrode in order to prevent the held image signal from leaking.

  Since the pixel portions 70 as described above are arranged in a matrix in the image display region 10a, active matrix driving is possible.

  As shown in FIG. 3 again, the image signals are supplied for each group to the set of six data lines 6a corresponding to each of the image signals VID1 to VID6 that are serially and parallelly developed in six phases. It is configured as follows. Note that the number of phase development of the image signal (that is, the number of series of image signals that are serial-parallel-developed) is not limited to six phases, and may be, for example, a plurality of phases such as nine phases, twelve phases, and twenty-four phases. The developed image signal may be supplied to a set of data lines 6a in which the number corresponding to the number of development is set as one set. Alternatively, the data lines 6a may be supplied line-sequentially without being serial-parallel developed.

  Next, the scanning line driving circuit of the liquid crystal device according to the present embodiment will be described in detail with reference to FIGS. FIG. 5 is a circuit diagram showing an electrical configuration of the scanning line driving circuit. FIG. 6 is a circuit diagram showing a specific configuration of the output buffer.

  In FIG. 5, the scanning line driving circuit 104 includes a shift register 240 and an output buffer 230.

  The shift register 240 includes a plurality of inverters 241 and a NAND circuit 242. Based on the Y clock signal CLY and the inverted Y clock signal CLY ′, the shift register 240 receives a transfer signal at a timing at which an image signal should be supplied to the pixel unit 70. The data are sequentially output and transferred to the output buffer 230.

  The output buffer 230 is electrically connected in series with inverters 231, 232 and 233 as examples of the “buffer circuit” according to the present invention. Here, the inverter 233 is an example of the “final stage buffer circuit” according to the present invention. An input terminal of the output buffer 230 is electrically connected to an output terminal of the shift register 240, and a transfer signal from the shift register 240 is input to the input terminal of the output buffer 230. The output buffer 230 gives drive capability to the transfer signal transferred from the shift register 240. The transfer signal that has obtained the driving ability (in other words, the current supply ability) is finally supplied from the scanning line driving circuit 104 to the pixel unit 70 through the scanning line 11a as a scanning signal.

  As described above, the output buffer 230 includes a plurality of inverters 231, 232, and 233, and has a function of outputting the transfer signal as a scanning signal after increasing the driving capability, shaping the waveform, and adjusting the timing. In addition, by limiting the pulse width of each scanning signal, it is also possible to provide a waveform limiting circuit or an enable circuit in the scanning line driving circuit 104 that creates a gap between scanning signals output in succession. is there. Further, an output control circuit that changes the output order of the scanning signals so as to perform scanning for each area obtained by dividing the image display area 10a into a plurality of areas, that is, to perform scanning by the area scanning method, is provided with the shift register 240. You may provide between the output buffer 230 or between the output buffer 230 and the scanning line 11a.

  As shown in detail in FIG. 6, the inverter 231 includes a TFT 231a and a TFT 231b. Similarly, the inverter 232 includes TFTs 232a and 232b, and the inverter 233 includes TFTs 233a and 233b. The input terminal of the output buffer 230 is electrically connected to the gates of the TFT 231a and the TFT 231b. The output terminal of the output buffer 230 is electrically connected to the drains of the TFTs 233a and 233b.

  The inverters 231 and 232 are driven by the scan drive circuit high potential power supply VDDX and the low potential power supply VSSX. On the other hand, the inverter 233 is driven by the final stage buffer circuit high potential power supply VDDT and the low potential power supply VSST. Here, during normal driving of the liquid crystal device, the high-potential power supply VDDT for the final stage buffer circuit is set to the same potential as the high-potential power supply VDDX for the scanning drive circuit. Similarly, the low-potential power supply VSST for the final stage buffer circuit is set to the same potential as the high-potential power supply VSSX for the scan drive circuit. Therefore, the voltage of the transfer signal transitions between the potential of the high-potential power supply VDDX for the scan drive circuit and the potential of the low-potential power supply VSSX for the scan drive circuit, and the drive capability is gradually increased, so that the scan signals G1,. Output as Gm.

  Next, a power supply for the final stage buffer circuit and an inspection method using the same will be described with reference to FIGS. FIG. 7 is an explanatory diagram for explaining the inspection method of the liquid crystal device according to the present embodiment liquid. FIG. 8 is a graph showing an example of the electrical static characteristics of the pixel switching element of the liquid crystal device according to the present embodiment.

  3 and 7, in the present embodiment, in particular, the high potential power supply for the final stage buffer circuit supplied to the inverter 233 located in the final stage of the output buffer 230 among the inverters 231, 232, and 233 constituting the output buffer 230. The VDDT and the low potential power supply VSST are power supplies independent of the high potential power supply VDDY and the low potential power supply VSSY for the scanning line driving circuit. That is, as shown in FIG. 3, the high-potential power supply VDDT and the low-potential power supply VSST for the final stage buffer circuit are connected via the external circuit connection terminal 102 different from the high-potential power supply VDDX and the low-potential power supply VSSX for the scanning line driving circuit. It is a separate power supply or a different power supply. Therefore, the high potential power supply VDDT and the low potential power supply VSST for the final stage buffer circuit can set or adjust the power supply potential separately from the high potential power supply VDDY and the low potential power supply VSSY for the scanning line driving circuit. Therefore, as shown in FIG. 7, when the liquid crystal device is inspected or evaluated, the pixel unit 70 is supplied with a power supply having a normal driving potential, that is, the scanning line driving circuit high potential power supply VDDX and the low potential power supply VSSX. Alternatively, a power source having a potential different from that of the potential during normal driving can be supplied. That is, in addition to or instead of the normal driving condition, the pixel unit 70 can be inspected or evaluated under conditions that have a stricter condition or margin than the normal driving condition. For example, the electrical conditions in the pixel unit 70 in a high temperature environment include the potential of the high potential power supply VDDT and the low potential power supply VSST for the final stage buffer circuit, and the operating range of the high potential power supply VDDX and the low potential power supply VSSX for the scanning line driving circuit. It can be simulated by changing beyond. Such inspection or evaluation of the pixel unit 70 is very convenient in practice when selecting or screening a product in mass production. Alternatively, by changing the potentials of the high-potential power supply VDDT and the low-potential power supply VSST for the final stage buffer circuit, for example, the gate potential of the pixel switching TFT 71 in the pixel portion 70 can be arbitrarily changed, and is mounted on the liquid crystal device. It is possible to measure or evaluate the static characteristics of the pixel switching TFT 71 in this state. Thus, the measurement or evaluation of the static characteristics of the pixel unit 70 is very convenient in practice, particularly when measuring or evaluating at the time of prototyping.

  Here, the above-described inspection or evaluation of the liquid crystal device will be described in more detail.

  In FIG. 7, in the inspection or evaluation of the liquid crystal device described above, first, the final buffer circuit potential power supply VDDT that simulates severe inspection conditions such as in a high temperature environment and the low potential are applied to the pixel unit 70 of the liquid crystal device of this embodiment. The power supply VSST is supplied. For example, the final buffer circuit high potential power supply VDDT is set so that the gate potential of the pixel switching TFT 71 in the pixel portion 70 is lower than the power supply potential during normal driving, that is, the potential of the scanning line drive circuit potential power supply VDDY. Set. At this time, since the high-potential power supply VDDT for the final stage buffer circuit is a power supply independent of the potential power supply VDDY for the scanning line driving circuit, it can be easily set to a potential lower than the potential power supply VDDY for the scanning line driving circuit. Can be set to If the potential power supply VDDY for the scanning line driving circuit is used as the potential power supply for the final stage buffer circuit and the potential is lowered, the shift register in the scanning line driving circuit will not operate normally, and the pixel switching TFT The voltage cannot be applied to the gate. The gate voltage Vg of the pixel switching TFT 71 can be arbitrarily set by making the final stage buffer circuit high potential power supply VDDT a power supply independent of the scanning line drive circuit potential power supply VDDY. At this time, the source potential Vs of the pixel switching TFT 71 can be set to a constant potential, for example, 2 V, by supplying power from the data line driving circuit 101 via the data line 6a. On the other hand, the drain potential of the pixel switching TFT 71 can be set to a constant potential, for example, 20 V, by electrically connecting a mechanical needle or a probe to the pixel electrode 9a constituting the liquid crystal element 72 and supplying an external power supply. .

  Next, an electrical static characteristic of the pixel switching TFT 71 in the pixel unit 70, for example, a drain current Id is measured. The drain current Id of the pixel switching TFT 71 is measured by measuring the drain current Id while changing the final stage buffer circuit high-potential power supply VDDT so that the gate voltage Vg is between 2V and 20V, for example, as described above. The characteristic of Id can be measured. That is, as shown in FIG. 8, a characteristic curve L1 indicating the relationship between the gate voltage Vg of the pixel switching TFT 71 and the drain current Id can be obtained. Therefore, the electrical static characteristics of the pixel unit 70 can be evaluated.

  When the pixel unit 70 is in a high temperature state, the image signal held in the liquid crystal element 72 may leak through the pixel switching TFT 71. In order to simulate such a state, if the power supply for the final stage buffer circuit cannot be arbitrarily set, it is necessary to actually set the pixel unit 70 to a high temperature state. However, according to the present embodiment, for example, the leakage of the image signal in the pixel unit 70 can be simulated by reducing the gate voltage Vg and weakening or shallowing the image signal written to the liquid crystal element 72.

As described above, according to the liquid crystal device according to the present embodiment, the final stage buffer circuit high potential power supply VDDT and the low potential power supply VSST can be arbitrarily changed. The pixel unit 70 can be inspected or evaluated by arbitrarily simulating the conditions.
<Electronic equipment>
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. 9 is a plan view showing a configuration example of the projector. As shown in FIG. 9, a projector 1100 includes a lamp unit 1102 made up 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. 10 is a perspective view showing the configuration of this personal computer. In FIG. 10, the computer 1200 includes a main body 1204 provided with 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. 11 is a perspective view showing the configuration of this mobile phone. In FIG. 11, a mobile 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. 9 to 11, 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. The inspection method and the electronic apparatus provided with the electro-optical device are also included in the technical scope of the present invention.

It is a top view which shows the whole structure of the liquid crystal device which concerns on 1st Embodiment. It is sectional drawing of HH 'of FIG. It is a block diagram which shows the structure of the principal part of the liquid crystal device which concerns on 1st Embodiment. FIG. 3 is a circuit diagram illustrating an electrical configuration of a pixel unit of the liquid crystal device according to the first embodiment. FIG. 2 is a circuit diagram illustrating an electrical configuration of a scanning line driving circuit of the liquid crystal device according to the first embodiment. FIG. 3 is a circuit diagram illustrating a specific configuration of an output buffer of the liquid crystal device according to the first embodiment. It is explanatory drawing for demonstrating the test | inspection method of the liquid crystal device which concerns on 1st Embodiment. It is a graph which shows an example of the electrical static characteristic of the pixel switching element of the liquid crystal device which concerns on 1st Embodiment. 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

  6a ... data line, 10 ... TFT array substrate, 10a ... image display area, 11a ... scanning line, 20 ... counter substrate, 21 ... counter electrode, 50 ... liquid crystal layer, 52 ... sealing material, 53 ... frame light shielding film, 70 ... Pixel unit 101... Data line driving circuit 102 102 External circuit connection terminal 104 Scanning line driving circuit 230 Output buffer 231, 232 Buffer circuit 233 Final stage buffer circuit 240 Shift register G1 ..Gm: Scanning signal, VDDT, VSST: Power supply for final stage buffer circuit, VDDY, VSSY: Power supply for scanning line drive circuit

Claims (5)

A plurality of pixel portions;
A plurality of scanning lines and a plurality of data lines wired in a pixel region in which the plurality of pixel portions are arranged;
(I) a shift register that sequentially outputs transfer signals; and (ii) an output buffer that includes at least one buffer circuit to which the sequentially output transfer signals are input, the transfer signal output from the output buffer being A scanning line driving circuit that supplies the pixel unit as a scanning signal via the plurality of scanning lines, and
The power supply for the final stage buffer circuit supplied to the final stage buffer circuit located at the final stage on the output side to the scanning line in the buffer circuit drives the scanning line driving circuit except the power supply for the final stage buffer circuit. An electro-optical device, characterized in that the power source is independent from a power source for a scanning line driving circuit.   2. The electro-optical device according to claim 1, wherein the voltage of the power supply for the final stage buffer circuit is variable when a scanning signal is supplied to the pixel unit in the inspection process of the pixel unit.   The electro-optical device according to claim 1, wherein the buffer circuit is formed by electrically connecting a plurality of inverters.   An electronic apparatus comprising the electro-optical device according to any one of claims 1 to 3. A plurality of pixel portions, a plurality of scanning lines and a plurality of data lines wired in a pixel region in which the plurality of pixel portions are arranged, (i) a shift register that sequentially outputs transfer signals, and (ii) the sequential And an output buffer having at least one buffer circuit to which the output transfer signal is input, and scanning the transfer signal output from the output buffer as a scan signal to the pixel unit via the plurality of scan lines A power supply for the final stage buffer circuit supplied to the final stage buffer circuit located in the final stage on the output side to the scanning line, excluding the final stage buffer circuit power supply. For an electro-optical device that is a power source independent of a power source for a scanning line driving circuit for driving the scanning line driving circuit,
A test condition changing step of sequentially changing the voltage of the power supply for the final stage buffer circuit and supplying the voltage to the pixel unit;
An inspection step of inspecting an electrical static characteristic of the pixel portion every time the inspection condition is changed in the inspection condition changing step.

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