JP4936082B2 - TFT array drive - Google Patents

Description

  The present invention relates to a drive device that drives a TFT array formed on a substrate such as a TFT substrate, and can be applied to a TFT array inspection device that inspects a TFT array.

  The TFT array is used as a switching element for selecting a pixel electrode of a liquid crystal display device, for example. In a substrate including a TFT array, for example, a plurality of gate lines functioning as scanning lines are arranged in parallel, and a plurality of source lines described as signal lines are arranged orthogonal to the gate lines. A TFT (Thin Film Transistor) is disposed in the vicinity of a portion where the lines intersect, and a pixel electrode is connected to the TFT.

  A TFT array forms a panel by arranging in a grid pattern. Usually, in the manufacture of a liquid crystal substrate, a plurality of panels are formed on a single glass substrate, and after being subjected to various processes, the panels are cut into individual panels.

  The manufacturing process of a semiconductor substrate on which a TFT array such as a liquid crystal substrate is formed includes a TFT array inspection process for inspecting the TFT array formed on the panel during the manufacturing process. In this TFT array inspection process, defects in the TFT array Inspection is being conducted. In this TFT array inspection process, the TFT array is inspected by driving the TFT array by applying a drive signal of a signal pattern for defect inspection to the gate line and the source line, and detecting the driving state of the TFT array. .

  In this TFT array inspection, it is known to detect the ITO potential when the TFT array is driven by the intensity of secondary electrons generated by electron beam irradiation.

On the glass substrate, a plurality of panels are formed on a single glass substrate, which is called multi-chamfering. When inspecting this multi-faceted TFT glass substrate, a driving signal is applied to all the panels formed on the TFT glass substrate to simultaneously drive the TFT array of all the panels, and the stage supporting the glass substrate is driven at a constant speed. The TFT array of each panel formed on the glass substrate is inspected in order by continuously scanning the panel with an electron beam while moving in (for example, see Patent Document 1).
JP 2006-170697 A

  In TFT array inspection equipment, a measurement stage is placed in a vacuum chamber, an electron gun that irradiates an electron beam for inspection is placed in the upper part of the vacuum chamber, and an electron beam emitted from the electron gun is placed on the stage. The irradiated substrate is irradiated. Since the irradiation range of the electron beam is extremely small compared to the area of one panel, the electron beam is continuously applied on the substrate by controlling the irradiation direction of the electron beam or moving the stage at a constant speed. Scanning.

  When a plurality of panels are arranged on the substrate, in the TFT array inspection, all the panels arranged on the substrate are driven. When a plurality of panels are arranged in the direction in which the stage moves, the place where the electron beam from one electron gun is irradiated is only one of the panels arranged on the substrate. In the TFT array driving, all the panels arranged on the substrate are driven simultaneously.

  FIG. 5 is a diagram for explaining a conventional panel driving example during scanning, and shows an example in which a TFT array is inspected by panel driving. FIG. 5A shows the state before the measurement, FIG. 5B shows the state in the first half of the measurement, and FIG. 5C shows the state in the second half of the measurement.

  Here, it is assumed that four panels A to D (6A to 6D) are arranged in a 2 × 2 arrangement on one glass substrate 5, and the vacuum chamber 2 includes two electron guns 4A and 4B. Are fixed in a direction (x direction in the drawing) orthogonal to the moving direction of the stage (y direction in the drawing).

  Each of the electron guns 4A and 4B irradiates one panel with an electron beam and controls the irradiation direction of the electron beam to perform scanning in the x direction, and scanning in the y direction is performed according to the moving direction of the stage. Therefore, measurement is performed in two stages according to the movement of the stage, and panel A (6A) and panel C (6C) are scanned in the first half of the measurement, and panel B (6B) and panel D (6D) are scanned in the second half of the measurement. . In each scan, the TFT array is inspected by driving the TFT array of the panel. At this time, in the first half of the measurement, not only panel A (6A) and panel C (6C) to be inspected are driven, but also panel B (6B) and panel D (6D) not to be inspected are driven, In the latter half of the measurement, not only panel B (6B) and panel D (6D) to be inspected are driven, but also panel A (6A) and panel C (6C) that are not inspected are driven.

  A TFT array is constructed, and various electric capacities exist at the site. FIG. 6 shows a configuration example of a TFT array provided in the liquid crystal display device. The TFT array 20 includes an ITO electrode 22 to which a TFT switch 21 is connected. The liquid crystal pixel is configured by sandwiching a liquid crystal layer between a pixel electrode (ITO electrode) 22 and a counter electrode (not shown), and a pixel capacitance is formed between the pixel electrode 22 and the counter electrode. Further, the TFT array 20 has stray capacitance in addition to the above-described pixel capacitance. Examples of the stray capacitance include a gate parasitic capacitance Cg existing on the gate side of the TFT switch 21, a source parasitic capacitance Cd existing on the source side of the TFT switch 21, and an additional capacitance (Cs) added to the pixel electrode 22. is there. One of the additional capacitors (Cs) is connected to the pixel electrode 22, and the other is connected to a common line or a gate line. The stray capacitance described above is an example and is not limited to these.

  In order to drive the TFT array, it is necessary to charge and discharge the capacitance existing in each of these panels. The time required for charging / discharging the capacitance depends on the capacitance and the applied current. As the number of panels increases, the capacitance that requires charging / discharging increases, so the time required for charging / discharging also increases.

  FIG. 7 is a diagram for explaining the charged state of the capacitance of the TFT array. When the current applied to the TFT array is constant, the time required to reach a predetermined voltage depends on the capacitance included in the TFT array, and when the capacitance increases from Ca to Cb due to stray capacitance, the time required for charging is Ta From T to Tb. The time required for discharge is also the same.

  Since the charge / discharge time of the TFT array capacitor affects the response time of the TFT array, it is necessary to reduce the charge / discharge time of the capacitor in order to shorten the response time of the TFT array. In order to shorten the charge / discharge time and shorten the response time of the TFT array, it is necessary to increase the current required for charge / discharge, and it is necessary to apply a large current to the TFT array.

  However, if a large current is passed through the TFT array substrate, the TFT array itself may be damaged, and wiring, connectors, and probe pins leading to the TFT array may be heated and damaged.

  The damage due to heating includes, for example, deterioration of the spring of the probe pin, peeling of the gold plating provided at the contact portion, disconnection of the wiring, and the like. The peeling of the gold plating causes a contact failure and an increase in electric resistance. In particular, since the TFT array is placed in a vacuum chamber and inspected in a vacuum state, heat generated in the vacuum state is not radiated, so that it is more likely to be damaged by heating than in the atmosphere. Therefore, it is necessary to limit the current supplied to the TFT array to avoid damage due to heating.

  This limitation of the supply current causes a problem that the time required for charging and discharging is lengthened, and as a result, the inspection time is lengthened. FIG. 8 is a diagram for explaining the relationship between the supply current and the charge / discharge time.

  FIG. 8A shows a case where the supply current I2 is larger than the limit current I0, and FIG. 8B shows a case where the supply current I1 is limited to be smaller than the limit current I0. Further, FIG. 8C shows a long and short state depending on the supply current during the charging time.

  When a large supply current I2 (FIG. 8 (a)) is applied to the TFT array, the charging time for charging the capacity is shortened to the charging time T2, but the supply current I2 exceeds the limit current I0 and heating is performed. Damage caused by is a problem. On the other hand, when the supply current I1 is limited to be smaller than the limit current I0 (FIG. 8B), a long charging time T1 is required to charge a capacity such as a stray capacitance.

  Therefore, when the current is limited for the purpose of preventing a failure, there arises a problem that the charging / discharging time is prolonged due to an increase in electrostatic capacity accompanying an increase in the number of panels, for example, an increase in the TFT gate parasitic capacitance Cg.

  Therefore, the present invention aims to solve the above problems and reduce the time required for charging and discharging the TFT array, and in particular, reducing the time required for charging and discharging the TFT array even with a current-limited supply current. The purpose is to do.

  An object of the TFT array substrate is to reduce the charge / discharge capacity, which is one of the factors that increase the driving time of the TFT array.

  Another object of the present invention is to shorten the inspection time when inspecting the TFT array substrate.

  The TFT array drive device of the present invention reduces the rise time and fall time of the drive waveform due to current limitation by reducing stray capacitance, which is a factor for extending the drive time of the TFT array on the TFT array substrate, and the TFT array. The time required for charging and discharging is reduced.

  The present invention reduces the number of panels driven simultaneously in order to reduce the stray capacitance related to the TFT array of the TFT array substrate. The present invention reduces the number of panels to be driven at the same time, and applies a drive signal only to the panel to be inspected at that time among the plurality of panels included in the TFT array substrate. By not applying the drive signal, the substantial capacity of the TFT array when the TFT array substrate side is viewed from the drive source to which the drive signal is applied is reduced.

  The drive signal can be applied to the inspection target panel by selecting a panel to which the drive signal is applied by the drive panel selection control circuit. Moreover, the panel selection by this drive panel selection control circuit can be performed according to the position of the stage which moves the panel on a TFT array board | substrate to an electron beam irradiation position, and can select the panel which applies a drive signal.

  As a result, when the drive source applies a drive signal to the TFT array, the time required for charging and discharging is shortened because the capacitance of the TFT array is reduced. As a result, the inspection time of the TFT array substrate can be reduced. Compared with the case where all the panels are driven, it can be shortened even in a current-limited state.

  The TFT array driving device of the present invention is a TFT array driving device that drives a panel included in a TFT array substrate, and a TFT driving circuit that generates a driving signal for driving the TFT array and a driving that selects a panel to which the driving signal is applied. A panel selection control circuit.

  The drive panel selection control circuit selects a panel from a plurality of panels included in the TFT array substrate, and applies the drive signal generated by the TFT drive circuit to the selected panel. A drive signal is not applied to all the panels included in the TFT array substrate, but a drive current is applied only to a panel selected from all the panels. The capacity of the panel when the TFT array substrate side is viewed from the TFT drive circuit is determined by the panel connected to the TFT drive circuit in order to apply the drive signal. Therefore, by limiting the panel to which the drive current is applied to a panel that requires the reduction, the capacity of the panel when the TFT array substrate side is viewed from the TFT drive circuit is reduced.

  By reducing the capacity of the panel, the charge time required to charge the capacitor or the discharge time required to discharge the charge charged to the capacitor is shortened, and the rise time and fall time of the drive signal waveform are shortened. Thus, the time required to drive each panel can be shortened.

  The TFT array driving device of the present invention includes a power feeding circuit that applies a driving signal to a panel included in the TFT array substrate. The drive panel selection control circuit of the present invention controls the drive of the panel by sending a drive signal for driving the TFT array and a selection signal for selecting the panel to which the drive signal is applied to the power feeding circuit. When the power supply circuit receives the selection signal and the drive signal from the drive panel selection control circuit, the power supply circuit selects a predetermined panel from all the panels included in the TFT array substrate by the selection signal, and supplies the drive signal to the selected panel. The drive signal is not supplied to the panel that is not selected. On the other hand, the selected panel is driven by the supplied drive signal without being affected by the capacity of the panel not selected.

  Further, the TFT array driving device of the present invention includes an electron beam scanning means for scanning an electron beam on a panel included in the TFT array. The electron beam scanning means can perform a TFT array inspection by scanning an electron beam on a panel included in the TFT array and detecting secondary electrons emitted from the TFT array by the electron beam scanning.

  The drive panel selection circuit of the present invention performs panel selection in synchronization with the electron beam scanning of the electron beam scanning means, and selects a panel scanned by the electron beam scanning means as a panel to which a drive signal is applied. Thereby, the panel to which the drive signal is applied is switched in synchronization with the electron beam scanning. Since electron beam scanning scans an electron beam with respect to the panel to be inspected, driving only the panel to be inspected by switching the panel to which the drive signal is applied in synchronization with the electron beam scanning. A signal can be applied.

  In the TFT array driving apparatus of the present invention, the electron beam scanning unit has a substrate stage that supports the TFT array substrate and moves the supported TFT array substrate in a predetermined direction. By moving the substrate stage, the panel irradiated with the electron beam on the TFT array substrate is switched. The selection circuit performs panel selection in synchronization with the movement command for driving the substrate stage, thereby switching the panel to which the drive signal is applied according to the position of the substrate stage and driving only the panel irradiated with the electron beam. A signal is applied so that a drive signal is not applied to a panel not irradiated with an electron beam. As a result, the drive signal is applied only to the panel to be inspected at that time among the plurality of panels included in the TFT array substrate, and the drive signal is not applied to the panel not to be inspected. The substantial capacitance of the TFT array when the TFT array substrate side is viewed from the drive source to which the drive signal is applied is reduced.

  According to the present invention, the time required for charging and discharging the TFT array can be shortened. In particular, the time required for charging and discharging the TFT array can be shortened even with a current-limited supply current.

  Further, in the TFT array substrate, it is possible to reduce the charge / discharge capacity, which is one of the factors that increase the driving time of the TFT array.

  According to the present invention, the inspection time can be shortened when inspecting the TFT array substrate.

It is the schematic of the TFT array drive device of this invention. It is a figure for demonstrating the panel drive example of this invention at the time of a scan. It is a figure which shows the example of a relationship between each instruction | command and drive signal in a TFT array drive device. It is a figure which shows typically the drive waveform by a conventional structure, and the drive waveform by the structure of this invention. It is a figure for demonstrating the example of the conventional panel drive at the time of a scan. It is a figure which shows the structural example of the TFT array with which a liquid crystal display device is provided. It is a figure for demonstrating the charge state of the capacity | capacitance of a TFT array. It is a figure for demonstrating the relationship between supply current and charging / discharging time.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... TFT array drive device, 2 ... Vacuum chamber, 3 ... Substrate stage, 4, 4A, 4B ... Electron gun, 5 ... TFT glass substrate, 6, 6A-6D ... Panel, 7 ... Feed relay circuit, 10 ... Control part 11 ... TFT drive circuit, 12 ... Drive panel selection control circuit, 13 ... Stage drive circuit, 14 ... Electron gun control unit, 15 ... Electron gun control circuit, 16 ... Electron beam, 20 ... TFT array, 21 ... TFT switch, 22: ITO electrode.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram of a TFT array driving device of the present invention.

  The TFT array drive device 1 shown in FIG. 1 shows an example applied to a TFT array inspection device. Here, it arrange | positions on the board | substrate stage 3 provided in the vacuum chamber 2, a drive current is applied to several panel A-panel D (6A-6D) in which this TFT glass substrate 5 is formed, and by this drive current An example in which a TFT array inspection is performed on a panel in a driving state is shown.

  In addition, although the example of four panels of panel A-panel D (6A-6D) is shown here as a panel in which TFT glass substrate 5 is formed, this panel number is an example shown from description. The number of panels is not limited.

  The TFT array driving apparatus 1 includes a substrate stage 3 built in the vacuum chamber 2 and an electron gun 4 provided on the upper portion of the vacuum chamber 3, and a stage for driving the substrate stage 3 as a circuit configuration for driving the TFT array. A drive circuit 13, a TFT drive circuit 11 and a drive panel selection control circuit 12 for driving a TFT array of a panel of the TFT glass substrate 5 placed on the substrate stage 3, an electron gun control unit 14 for controlling and driving the electron gun 4A, and an electron A gun control circuit 15 and a control unit 10 that controls the entire TFT array driving device 1 are provided. Note that the control unit 10 and the electron gun control unit 14 perform control by software processing by a memory means such as a ROM for storing a CPU and software describing an algorithm for driving the CPU, or a RAM for signal processing. be able to.

  The substrate stage 3 includes a power supply relay circuit 7 that supports the TFT glass substrate 5 and supplies a drive current to a panel selected from the panels formed on the TFT glass substrate 5. The substrate stage 3 moves the TFT glass substrate 5 placed on the stage in a predetermined direction based on the drive signal from the stage drive circuit 13. The movement of the TFT glass substrate 5 can be set to a constant speed in accordance with, for example, the scanning speed of the electron beam that scans the panel. Here, the stage drive circuit 13 for supplying a drive signal to the substrate stage 3 is driven in response to a movement command from the control unit 10, and the electron gun control unit 14 controls the electron beam irradiation direction and controls the electron beam to the panel. Scan above.

  The power feeding relay circuit 7 receives a selection signal and a drive signal from the drive panel selection control circuit 12. As the selection signal, a panel is selected from all the panels 6A to 6D formed on the TFT glass substrate 5, and a drive signal is supplied to the selected panel.

  Here, as for the selection signal, the driving panel selection control circuit 12 receives a selection command from the control unit 10 and selects a panel to which the driving signal is applied in synchronization with the movement of the substrate stage 3 by the stage driving circuit 13.

  As for the drive signal, first, the TFT drive circuit (panel driver) 11 receives a drive command from the control unit 10 to form a drive waveform. Subsequently, the drive panel selection control circuit 12 receives the TFT drive circuit (panel driver) 11. It is generated by receiving a drive waveform from.

  Further, the control unit 10 sends an electron beam scanning command to the electron gun control unit 14 to drive the electron gun control circuit 15. The electron gun control circuit 15 controls the electron gun 4 based on the control of the electron gun control unit 14 and controls the electron beam to be irradiated.

  Here, the control unit 10 controls the movement of the substrate stage 3 in the electron beam scanning on the panel, the selection command for selecting the panel to which the drive signal is applied, and the electron beam for controlling the electron beam irradiation from the electron gun. Control is performed so that each command output of the scan command is synchronized.

  According to a command synchronized by the control unit 10, stage driving by the stage driving circuit 13, selection of a driving panel by the driving panel selection control circuit 12, application of a driving signal to the selection panel, and electron beam irradiation by the electron gun control unit 14 Control is synchronized, the target panel is moved to the electron beam irradiation position of the electron gun by the stage drive circuit 13, and the target panel is irradiated with the electron beam from the electron gun by the electron gun control unit 14 to select the drive panel A drive signal is applied to the target panel by the control circuit 12.

  As a result, the drive signal is applied only to the target panel, and the drive signal is not applied to the non-target panel, so that the capacitance on the TFT array side as viewed from the power supply relay circuit 7 as the drive source on the TFT array substrate is reduced. Can be reduced.

  FIG. 2 is a diagram for explaining an example of panel driving according to the present invention during scanning, and shows an example in which a TFT array is inspected by panel driving. 2A shows a state before the measurement, FIG. 2B shows a state in the first half of the measurement, and FIG. 2C shows a state in the second half of the measurement.

  Here, similarly to the configuration example of FIG. 5 described above, it is assumed that four panels A to D (6A to 6D) are arranged in a 2 × 2 array on one glass substrate 5, In the vacuum chamber 2, it is assumed that two electron guns 4A and 4B are fixed in a direction (x direction in the figure) perpendicular to the moving direction of the stage (y direction in the figure).

  Similarly to the operation example of FIG. 5 described above, each of the electron guns 4A and 4B irradiates one panel with an electron beam and controls the irradiation direction of the electron beam to perform scanning in the x direction. Scanning in the y direction is performed according to the moving direction of the stage. Therefore, measurement is performed in two stages according to the movement of the stage, and panel A (6A) and panel C (6C) are scanned in the first half of the measurement, and panel B (6B) and panel D (6D) are scanned in the second half of the measurement. . In each scan, the TFT array is inspected by driving the TFT array of the panel.

  At this time, in the TFT array driving device of the present invention, the electron beam irradiation by the electron guns 4A and 4B and the application of the drive signal to the panel are performed in synchronization, and the drive signal is not applied to the panel not irradiated with the electron beam. In the first half of the measurement (FIG. 2B), the drive signal is applied only to the panel A (6A) and the panel C (6C) to be inspected, and to the panel B (6B) and the panel D (6D) not to be inspected. The drive signal is not applied. In FIG. 2B, “ON” is described for the panels 6A and 6C that are driven by the application of the drive signal, and “OFF” is described for the panels 6B and 6D that are not driven because the drive signal is not applied.

  In the latter half of the measurement (FIG. 2 (c)), the drive signal is applied only to the panel B (6B) and the panel D (6D) to be inspected, and the panel A (6A) and the panel C (6C) to which the inspection is not performed. No drive signal is applied to. In FIG. 2C, “ON” is described for the panels 6B and 6D driven by application of the drive signal, and “OFF” is described for the panels 6A and 6C that are not driven because the drive signal is not applied.

  FIG. 3 is a diagram showing an example of the relationship between each command and drive signal in the TFT array drive device. 3A to 3C show an electron beam scanning command (FIG. 3A), a movement command (FIG. 3B), and a drive command (FIG. 3C) output by the control unit 10. 3D to 3G show selection signals (FIGS. 3D and 3F) and drive waveforms (FIGS. 3E and 3G) output from the drive panel selection control circuit 12. FIG. Show.

  Here, the electron beam scanning command, the movement command, and the drive command are output in synchronization, and the selection signal (FIG. 3 (d)) and the drive waveform (FIG. 3 (e)) is output, and a selection signal (FIG. 3 (f)) and a drive waveform (FIG. 3 (g)) are output to the panels B and D in the second half period.

  Note that FIG. 3 shows a signal state having a period overlapping the selection signal and the drive waveform at the time of switching between the first half period and the second half period, but it may be a signal state having no overlapping period.

  FIG. 4 schematically shows a driving waveform according to the conventional configuration and a driving waveform according to the configuration of the present invention. In FIG. 4, the solid line shows the drive waveform when only the panel selected by the configuration of the present invention is driven, and the broken line shows the drive waveform when all the panels are driven by the conventional configuration.

  Here, assuming that the time required to drive each array by a drive signal and execute a predetermined operation is the effective drive time Tact, this effective drive time Tact is a case where all the panels are driven and only the selected panel is driven. It is the same in any case. On the other hand, the necessary drive time Tall required from the application of the drive waveform to the end thereof is charged by the liquid crystal capacity, additional capacity and parasitic capacity connected to the array in addition to the effective drive time Tact. It becomes longer by the rise time and fall time for discharging.

  The time width of the rise time and the fall time depends on the capacitance of the array to which the drive signal is applied. As shown by the solid line, the configuration in which the drive signal is applied only to the panel selected according to the present invention reduces the capacitance connected to the array and shortens the rise time and fall time.

  The shortened time in FIG. 4 indicates that the required drive time Tall2 according to the present invention can be made shorter than the required drive time Tall1 when driving all the panels as in the prior art.

  In the above example, the TFT array driving device of the present invention is applied to a TFT array inspection device. However, the present invention is not limited to the inspection device and can be similarly applied to any circuit configuration for driving a TFT array. .

  The present invention can be applied not only to a TFT array inspection process in a liquid crystal manufacturing apparatus but also to a defect inspection of a TFT array provided in an organic EL or various semiconductor substrates.

Claims (4)

In the TFT array driving device for driving the panel provided in the TFT array substrate,
A TFT drive circuit for generating a drive signal for driving the TFT array;
A drive panel selection control circuit for selecting a panel to which the drive signal is applied;
The TFT array driving device, wherein the driving panel selection control circuit applies a driving signal generated by the TFT driving circuit to a selected panel. A power supply circuit for applying a drive signal to a panel included in the TFT array substrate;
The drive panel selection control circuit sends a drive signal for driving the TFT array and a selection signal for selecting a panel to which the drive signal is applied to the power supply circuit,
The TFT array driving device according to claim 1, wherein the power feeding circuit feeds a driving signal to a panel selected by the selection signal. An electron beam scanning means for scanning an electron beam on a panel included in the TFT array;
The drive panel selection control circuit performs panel selection in synchronization with the electron beam scanning of the electron beam scanning unit, selects a panel to be scanned by the electron beam scanning unit as a panel to which a drive signal is applied, and performs electron beam scanning. The TFT array driving device according to claim 1, wherein a panel to which a driving signal is applied is switched in synchronization with the driving signal. The electron beam scanning means has a substrate stage that supports the TFT array substrate and moves the TFT array substrate in a predetermined direction,
4. The TFT according to claim 3, wherein the selection circuit performs panel selection in synchronization with a movement command for driving the substrate stage, and switches a panel to which a drive signal is applied in accordance with the position of the substrate stage. Array drive device.

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