JP5923402B2 - Display device - Google Patents

Description

  Embodiments described herein relate generally to a display device.

  Electronic devices such as mobile phones, personal digital assistants, and personal computers equipped with a display device having a touch panel function have been developed as a form of user interface. In an electronic device having such a touch panel function, it has been studied to add a touch panel function by separately attaching a touch panel substrate to a display device such as a liquid crystal display device or an organic EL display device.

  In recent years, thin films are formed of various materials on a transparent insulating substrate such as a glass substrate by CVD (Chemical Vapor Deposition) method, etc., and by repeating operations such as cutting and grinding, scanning lines and signal lines can be used. A technique for manufacturing an image reading apparatus by forming a display element, an optical sensor element, and the like has been studied.

  In addition, as a reading method of the image reading device, a conductive electrode is arranged in place of the optical sensor element, and so-called electrostatic detection is performed to detect information such as a finger on the panel surface by a change in capacitance between the electrode and the finger. A technique for detecting a contact position by a capacitive method has been studied.

JP 2004-93894 A

  In the display device using the electrostatic capacity method, so-called in-cell technology in which a sensor function is incorporated in a display panel such as a liquid crystal has been actively developed. According to the in-cell technology, it is not necessary to attach a separately created touch panel to a liquid crystal or the like, so that it is possible to avoid an increase in thickness and weight of the entire electronic device. Furthermore, since there is no interface between the liquid crystal or the like and the touch panel, light reflection that tends to occur at the interface does not occur, which is excellent in terms of display quality.

  By the way, in the conventional liquid crystal display device with a built-in touch sensor using the in-cell technology, a defect may occur in the liquid crystal display due to the sensor operation. This phenomenon is considered to be because a display function and a sensor function are incorporated close to each other in the display panel, so that a signal for driving the sensor circuit affects the display circuit.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a display device capable of reducing the influence of sensor operation on the display function.

A display device according to one embodiment of the present invention includes a pixel circuit including a pixel including a counter electrode and a display electrode that sandwich a liquid crystal layer arranged in a matrix, and a dielectric disposed between rows of the plurality of pixel circuits. A plurality of sensor circuits for reading the strength of capacitive coupling between the plurality of pixel circuits, a plurality of drive signal lines for driving the sensor circuits extended along the row direction of the plurality of pixel circuits, and electrically connected to a fixed potential is and possess a shield electrode provided to reduce the voltage change of the display electrode through the parasitic capacitance due to the voltage change of the specific driving signal line between a particular drive signal line and the pixel circuit, wherein The plurality of drive signal lines include a precharge gate line, a coupling pulse line, and a read gate line, and the sensor circuit applies a voltage to the detection electrode that forms a capacitance with a dielectric and the detection electrode Do A recharge line, a read line for reading a detection signal from the detection electrode, a precharge transistor having one of a source / drain connected to the precharge line and a gate electrode connected to the precharge gate line, and a source / drain One electrode is connected to the other electrode of the precharge transistor, the gate electrode is connected to the detection electrode, one source / drain electrode is connected to the other electrode of the amplification transistor, and the other electrode is A readout transistor connected to the readout line, a gate electrode connected to the readout gate line, one electrode of the source / drain connected to the other electrode of the amplification transistor, the other electrode connected to the detection electrode, and a gate electrode Transistor connected to the precharge gate line and one of the source and drain electrodes Connected to one electrode of the amplifying transistor, connected to the other electrode coupling pulse line, a gate electrode is provided with a power supply switching transistor connected to the read gate line.

1 is a schematic plan view showing a configuration of a display device according to a first embodiment. The figure which shows the cross section of the display apparatus of 1st Embodiment. The figure which shows the equivalent circuit of the sensor circuit in 1st Embodiment. 4 is a timing chart for explaining an example of a driving method of the display device according to the first embodiment. The figure which shows the structure of the conventional display apparatus typically. The figure which shows typically the structure of the display apparatus of 1st Embodiment. The figure which shows the response | compatibility with the cross-sectional structure of the display apparatus of 1st Embodiment, and a sensor circuit. The figure which shows typically the structure of the display apparatus of 2nd Embodiment. The figure which shows the response | compatibility with the cross-sectional structure of the display apparatus of 2nd Embodiment, and a sensor circuit.

[First Embodiment]
Hereinafter, a display device and a display device driving method according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic plan view showing the configuration of the display device according to the first embodiment.
The display device 1 according to the present embodiment includes a liquid crystal display panel PNL and a circuit board 60. One end of the flexible substrates FC1 and FC2 is electrically connected to the end of the liquid crystal display panel PNL. A circuit board 60 is electrically connected to the other ends of the flexible boards FC1 and FC2.

  The liquid crystal display panel PNL includes a display unit DYP composed of a plurality of pixels arranged in a matrix, and a scanning line driving circuit YD and a signal line driving circuit XD arranged around the display unit DYP. The circuit board 60 controls the display operation of the display device and also controls a sensor circuit (described later) provided in the liquid crystal display panel PNL. That is, the circuit board 60 outputs the video signal acquired from the external signal source SS to the liquid crystal display panel PNL. The circuit board 60 supplies a signal for operating the sensor circuit and outputs an output signal acquired from the sensor circuit to the control unit 65.

FIG. 2 is a diagram illustrating a cross section of the display device according to the first embodiment.
The display device 1 according to the present embodiment includes a liquid crystal display panel PNL, a lighting unit, a frame 40, a bezel cover 50, a circuit board 60, and a protective glass PGL.

  The illumination unit is disposed on the back side of the liquid crystal display panel PNL. The frame 40 supports the liquid crystal display panel PNL and the illumination unit. The bezel cover 50 is attached to the frame 40 so as to expose the display unit DYP of the liquid crystal display panel PNL. The circuit board 60 is disposed on the back side of the frame 40. The protective glass PGL is fixed on the bezel cover 50 with an adhesive 70.

  The liquid crystal display panel PNL includes an array substrate 10, a counter substrate 20 disposed so as to face the array substrate 10, and a liquid crystal layer LQ sandwiched between the array substrate 10 and the counter substrate 20. The array substrate 10 includes a polarizing plate 10A attached to the main surface opposite to the liquid crystal layer LQ. The counter substrate 20 includes a polarizing plate 20A attached to the main surface opposite to the liquid crystal layer LQ.

The illumination unit includes a light source (not shown), a light guide 32, a prism sheet 34, a diffusion sheet 36, and a reflection sheet 38.
The light guide 32 emits light incident from the light source toward the liquid crystal display panel PNL. The prism sheet 34 and the diffusion sheet 36 are optical sheets disposed between the liquid crystal display panel PNL and the light guide 32. The reflection sheet 38 is disposed so as to face the main surface of the light guide 32 on the side opposite to the liquid crystal display panel PNL. The prism sheet 34 and the diffusion sheet 36 collect and diffuse the light emitted from the light guide 32.

  The protective glass PGL protects the display unit DYP of the liquid crystal display panel PNL from external impacts. The protective glass PGL can be omitted.

  Next, the display device shown in FIG. 1 will be described in detail.

  The liquid crystal display panel PNL has a structure in which a liquid crystal layer LQ is sandwiched between an array substrate 10 and a counter substrate 20 which are a pair of electrode substrates. The transmittance of the liquid crystal display panel PNL is controlled by the liquid crystal driving voltage applied to the liquid crystal layer LQ from the display electrode PE provided on the array substrate 10 and the counter electrode CE provided on the counter substrate 20.

  In the array substrate 10, a plurality of display electrodes PE are arranged in a substantially matrix form on a transparent insulating substrate (not shown). In addition, a plurality of gate lines GL are arranged along the rows of the plurality of display electrodes PE, and a plurality of signal lines SL are arranged along the columns of the plurality of display electrodes PE.

  Each display electrode PE and counter electrode CE are made of a transparent electrode material such as ITO (Indium Tin Oxide), for example, and are each covered with an alignment film AL. The display electrode PE and the counter electrode CE constitute a liquid crystal pixel PX together with a pixel region that is a part of the liquid crystal layer LQ.

  A plurality of pixel switches SWP are arranged in the vicinity of the intersection position of the gate line GL and the signal line SL. Each pixel switch SWP is a thin film transistor (TFT), for example, and has a gate connected to the gate line GL, a source-drain path connected between the signal line SL and the display electrode PE, and a corresponding gate line GL. And the corresponding signal line SL and the corresponding display electrode PE are electrically connected.

Further, the array substrate 10 is provided with a sensor circuit 12, and a coupling pulse line CPL, a precharge gate line PGL, and a read gate line RGL for driving the sensor circuit 12 are provided for a plurality of display electrodes PE. Arranged along the line.
In the present embodiment, the signal line SL is also used as a precharge line PRL for supplying a signal for driving the sensor circuit 12 and a read line ROL.

  The scanning line driving circuit YD supplies a gate voltage for turning on the pixel switch SWP (conducting the source-drain path) to the plurality of gate lines GL to sequentially drive the gate lines GL. Further, the scanning line driving circuit YD drives the sensor circuit 12 by driving the plurality of coupling pulse lines CPL, the plurality of precharge gate lines PG, and the plurality of read gate lines RGL at a predetermined timing.

  The signal line driving circuit XD supplies a video signal from the signal line SL to the display electrode PE via the pixel switch SWP in which the source-drain path is conducted.

  The common voltage Vcom is supplied to the counter electrode CE. If necessary, the polarity of the common voltage Vcom supplied to the counter electrode CE is inverted, and the polarity of the voltage applied to the liquid crystal layer LQ is inverted so as to correspond to the polarity inversion method of the display device 1.

  The circuit board 60 includes an output circuit unit OCT, an input circuit unit ICT, a D / A conversion unit DAC, an A / D conversion unit ADC, an interface unit I / F, and a timing controller TCON.

  The timing controller TCON controls the operation of each unit mounted on the circuit board 60, and the operations of the scanning line driving circuit YD, the signal line driving circuit XD, the counter electrode driving circuit, and the sensor circuit 12.

  The digital video signal captured from the external signal source SS through the interface unit I / F is converted into an analog signal by the D / A conversion unit DAC and output to the signal line SL by the input circuit unit ICT at a predetermined timing. .

  An output signal from the sensor circuit 12 is supplied to the A / D conversion unit ADC at a predetermined timing by the output circuit unit OCT, converted into a digital signal, and supplied to the interface unit I / F. The interface unit I / F outputs the received digital signal to the control unit 65. The control unit 65 performs coordinate calculation based on the received digital signal, and detects the coordinate position where the fingertip, the pen tip, etc. are in contact.

FIG. 3 is a diagram illustrating an equivalent circuit of the sensor circuit 12 according to the first embodiment.
The sensor circuit 12 includes a detection electrode 7, a precharge line PRL, a read line ROL, a precharge gate line PGL, a coupling pulse line CPL, a read gate line RGL, a coupling capacitor Css, a precharge TFT 6, an amplification TFT 9, a read TFT 12, A compensation TFT 13 and a power supply switching TFT 14 are provided. Further, outside the sensor circuit 12, the precharge line selection TFT 15 is connected to the precharge line PRL, and the read line selection TFT 16 is connected to the read line ROL.

  The detection electrode 7 detects a change in the detection capacitance due to the presence or absence of a contact body (dielectric material). The precharge line PRL supplies a precharge voltage to the detection electrode 7. The read line ROL takes out the voltage of the detection electrode 7. The precharge gate line PGL, the coupling pulse line CPL, and the readout gate line RGL supply signals for driving the operation of the sensor circuit 12.

  The precharge TFT 6 is a switch for writing and holding a precharge voltage to the detection electrode 7. The coupling capacitance Css causes a voltage difference due to a change in the detection capacitance at the detection electrode 7. The amplification TFT 9 is a switch for amplifying the voltage generated in the detection electrode 7. The read TFT 12 is a switch for outputting and holding the amplified voltage to the read line ROL. The compensation TFT 13 is a switch that interrupts the path for supplying the precharge voltage to the detection electrode 7. The power supply switching TFT 14 is a switch that interrupts a path for supplying a signal from the coupling pulse line CPL to the amplification TFT 9.

  The precharge line PRL and the read line ROL use a common line with the signal line SL. Since one sensor circuit 12 is arranged for the plurality of pixels PX, a part of the signal line SL is shared.

  The precharge TFT 6 is, for example, a p-type thin film transistor, and has a gate electrode electrically connected to the precharge gate line PGL (or integrally formed) and a source electrode electrically connected to the precharge line PRL (or The drain electrode is electrically connected to the detection electrode 7 (or configured integrally).

  The amplification TFT 9 is, for example, a p-type thin film transistor, and the gate electrode is electrically connected (or integrally formed) with the detection electrode 7 and the source electrode is electrically connected (or integrated) with the drain electrode of the power supply switching TFT 14. The drain electrode is electrically connected to the source electrode of the readout TFT 12 (or configured integrally).

  The readout TFT 12 is, for example, a p-type thin film transistor, and the gate electrode is electrically connected (or integrally formed) with the readout gate line RGL, and the source electrode is electrically connected (or integrated) with the drain electrode of the amplification TFT 9. The drain electrode is electrically connected to the readout line ROL (or configured integrally).

  The compensation TFT 13 is, for example, a p-type thin film transistor, and the gate electrode is electrically connected to the precharge gate line PGL (or integrally formed), and the source electrode is electrically connected to the drain electrode of the amplification TFT 9 (or The drain electrode is electrically connected to the detection electrode 7 (or configured integrally).

  The power supply switching TFT 14 is, for example, a p-type thin film transistor, and has a gate electrode electrically connected to the read gate line RGL (or integrally formed) and a source electrode electrically connected to the coupling pulse line CPL (or The drain electrode is electrically connected to (or integrated with) the source electrode of the amplification TFT.

  The precharge line selection TFT 15 is a p-type thin film transistor, for example, and has a gate electrode electrically connected to the precharge selection line PSEL (or integrally formed) and a source electrode electrically connected to the voltage source PPS. The drain electrode is electrically connected to the precharge line PRL (or configured integrally).

  The read line selection TFT 16 is a p-type thin film transistor, for example, and has a gate electrode electrically connected (or integrally formed) with the read selection line RSEL and a source electrode electrically connected with the voltage source PPS (or The drain electrode is electrically connected to the readout line ROL (or configured integrally).

  FIG. 4 is a timing chart for explaining an example of a driving method of the display device 1 according to the first embodiment.

  From the voltage source PPS, an initialization voltage is first supplied, and then a precharge voltage is supplied. Here, the initialization voltage is a voltage lower than the precharge voltage.

  In a state where the initialization voltage is supplied from the voltage source PPS, the precharge gate signal PG which is a drive signal is output to the precharge gate line PGL. A read gate signal RG that is a drive signal is output to the read gate line RGL. A precharge line selection signal PSE which is a drive signal is output to the precharge selection line PSEL. A read line selection signal RSE that is a drive signal is output to the read selection line RSEL.

[Operation at timing T1]
The precharge line selection TFT 15 and the readout line selection TFT 16 are turned on at the timing when the precharge line selection signal PSE and the readout line selection signal RSE are on level (low level), respectively, and the voltage source PPS is applied to the precharge line PRL and readout line ROL, respectively. More initialization voltage is applied.

  The readout TFT 12 and the power supply switching TFT 14 connected to the readout gate line RGL are turned on at the timing when the readout gate signal RG is on level (low level). Further, the compensation TFT 13 and the precharge TFT 6 connected to the precharge gate line PGL are turned on at the timing when the precharge gate signal PG is on level (low level).

  As a result, the initialization voltage applied to the read line ROL is applied to the detection electrode 7 via the read TFT 12 and the compensation TFT 13. Here, the initialization voltage is a voltage whose level is lower than the normal precharge voltage. Therefore, the potential of the detection electrode 7 is also lowered, and the amplification TFT 9 is turned on. As a result, the initialization voltage applied to the precharge line PRL is applied to the detection electrode 7 via the precharge TFT 6 and the amplification TFT 9.

  When the power supply switching TFT 14 is turned on, both the initialization voltage and the high voltage of the coupling pulse signal CP are input on the drain electrode side of the power supply switching TFT 14 (the drain electrode of the precharge TFT 6). For this reason, although the voltage of the detection electrode 7 becomes higher than the initialization voltage, the amplification TFT 9 can be turned on by selecting the characteristics of the amplification TFT 9.

  Thus, the initialization voltage is applied in order to reliably turn on the amplification TFT 9 by sufficiently lowering the potential of the detection electrode 7. The reason why the initialization voltage is applied via the read line ROL is that the read line ROL and the precharge line PRL are used together to reduce the resistance of the wiring and to reliably set the potential of the detection electrode 7 low. is there.

[Operation at timing T2]
The read gate signal RG and the read line selection signal RSE are turned off. As a result, the supply of the initialization voltage via the read line ROL is stopped. Further, the power switching TFT 14 is also turned off. Accordingly, the supply of the initialization voltage via the precharge line PRL continues.

  In this state, since the compensation TFT 13 is turned on, the gate and drain of the amplification TFT 9 are electrically connected. Therefore, the voltage of the gate electrode is a voltage reflecting the variation in the threshold voltage of the amplification TFT 9.

[Operation at timing T3]
The potential of the coupling pulse signal CP supplied to the coupling pulse line CPL is set low. The coupling pulse signal CP is applied to one end of the coupling capacitor Css, and as a result, the potential of the detection electrode 7 is lowered. Therefore, the fluctuation of the potential of the detection electrode 7 due to the presence or absence of a contact body described later can be increased.

[Operation at timing T4]
The voltage supplied from the voltage source PPS is changed to the precharge voltage. The precharge voltage is applied to the detection electrode 7 through the precharge line PRL, the precharge TFT 6, the amplification TFT 9, and the compensation TFT 13. As a result, the potential of the detection electrode 7 rises more than when the initialization voltage is applied. As described above, the voltage of the gate electrode of the amplification TFT 9 is a voltage reflecting the variation in the threshold voltage of the amplification TFT 9.

[Operation at timing T5]
The precharge gate signal PG and the precharge line selection signal PSE are turned off (high level). As a result, the detection electrode 7 is in a floating state, and the potential of the detection electrode 7 through the detection capacitor Cf varies depending on the presence or absence of the contact body (finger 10).

[Operation at timing T6]
The potential of the coupling pulse signal CP supplied to the coupling pulse line CPL is set high. The coupling pulse signal CP is applied to one end of the coupling capacitor Css, and as a result, the potential of the detection electrode 7 is raised. As shown by the detection electrode voltage in FIG. 4, a voltage difference can be generated between the detection electrode potential (without a finger) and the detection electrode potential (with a finger).

[Operation at timing T7]
The power supply switching gate signal PW supplied to the read gate line RGL is set to the on level (low level). The power supply switching TFT 14 is turned on, and the coupling pulse signal CP supplied to the coupling pulse line CPL is input to the source electrode of the amplification TFT 9 through the power supply switching TFT 14. As described above, the operating point (amplification degree) of the amplification TFT 9 varies depending on the voltage of the detection electrode 7. Accordingly, an amplified voltage indicating the presence or absence of the contact body (finger 10) is output from the drain electrode of the amplification TFT 9.

  At timing T7, the read gate signal RG is turned on (low level). As a result, the detection signal from the amplification TFT 9 is output to the readout line ROL via the readout TFT 12. The voltage waveform output to the read line ROL indicates this voltage fluctuation, and a voltage difference is generated between the output voltage (with a finger) and the output voltage (without a finger).

  Therefore, by detecting the output voltage difference between the output voltage (with finger) and the output voltage (without finger) at the time when the output period has elapsed since the read gate line PGL is turned on (for example, at timing T8), the fingertip or pen It is possible to detect the position where the tip or the like is in contact.

  The driving method described above has the following effects.

  In the present embodiment, the drain electrode of the amplification TFT 9 is connected to the detection electrode 7 via the compensation TFT 13 during the precharge period. With this configuration, an offset can be applied by the threshold voltage of the amplification TFT 9 when writing the precharge voltage, so that the optimum operating point of the amplification TFT 9 can be prevented from being affected by variations in threshold voltage. As a result, high reading performance can be realized.

  In the conventional image reading apparatus driving method, the precharge voltage is applied immediately after the sensor operation period starts. On the other hand, in this driving method, the initialization voltage is applied to the detection electrode 7 via the readout line ROL before the precharge voltage is applied to the detection electrode 7 via the precharge TFT 6. Different. By driving in this way, the voltage of the detection electrode 7 can be set as low as possible before applying the precharge voltage, so that the precharge voltage can be more easily applied.

  Further, before applying the precharge voltage to the detection electrode 7 via the precharge TFT 6, an initialization voltage is applied to the detection electrode 7 via the readout line ROL, and at the same time, the precharge line PRL is initialized. By applying the voltage, it becomes possible to more easily apply the precharge voltage.

  Next, the cause of the occurrence of defects in the liquid crystal display due to the sensor operation will be described.

  FIG. 5 is a diagram schematically showing the structure of a conventional display device. FIG. 5A is a plan view of the display device viewed from the array substrate 10 side, and FIG. 5B is a cross-sectional view taken along the arrow AB.

  In FIG. 5A, the horizontal direction represents the direction in which the signal line SL extends, and the vertical direction represents the direction in which the gate line GL extends. The detection electrode 7 is provided between the display electrode PE of a certain row and the display electrode PE of the adjacent row. A coupling pulse electrode (line) CPL is arranged in the vertical direction. A counter electrode CE (not shown) is provided on the back surface of the display electrode PE. A light shielding body BM (Black Matrix) is disposed between the display electrodes PE to shield the sensor circuit 12 such as the detection electrode 7 and the coupling pulse electrode CPL.

  Here, the coupling pulse line CPL described in the description of the sensor circuit 12 is actually an electrode having a predetermined width as shown in FIG. Accordingly, in the following description, the same reference numerals are given and appropriately described as a coupling pulse electrode CPL or a coupling pulse line CPL. The same applies to the other signal lines.

  In FIG. 5 (2), the color filter CF is clearly shown and the parasitic capacitance existing between the respective electrodes is described.

  As described above, the voltage of the detection electrode 7 is changed by the coupling capacitance Css by changing the voltage of the coupling pulse line CPL during a period when there is no liquid crystal display driving (blanking period). That is, the finger capacitance Cf between the detection electrode 7 and the finger changes depending on the presence or absence of the finger, so that the voltage of the detection electrode 7 changes.

  On the other hand, a parasitic capacitance Cpc exists between the coupling pulse electrode CPL and the display electrode 7. Therefore, when the voltage of the coupling pulse electrode CPL changes, the voltage of the display electrode PE changes accordingly. This is the cause of display failure.

  FIG. 6 is a diagram schematically illustrating the structure of the display device according to the first embodiment. FIG. 6A is a plan view of the display device viewed from the array substrate 10 side, and FIG. 6B is a cross-sectional view taken along the arrow AB.

  As shown in FIG. 6, the first embodiment is different from the conventional display device in that the shield electrode SHE is provided between the display electrode PE and the coupling pulse electrode CPL. Here, although the width of the coupling pulse electrode CPL is displayed narrower than the conventional one, FIG. 6 is a schematic diagram, and the width of the coupling pulse electrode CPL is the same as the conventional one.

  FIG. 7 is a diagram illustrating a correspondence between the cross-sectional structure of the display device according to the first embodiment and the sensor circuit 12. The shield electrode SHE is connected to a fixed potential (for example, the common voltage Vcom).

  By providing the shield electrode SHE, a parasitic capacitance Csc is generated between the shield electrode SHE and the coupling pulse electrode CPL, and a parasitic capacitance Csp is generated between the shield electrode SHE and the display electrode PE. Also, by providing the shield electrode SHE, the parasitic capacitance Cpc between the coupling pulse electrode CPL and the display electrode PE is reduced to a value close to zero. Therefore, the voltage change of the display electrode PE accompanying the voltage change of the coupling pulse electrode 7 can be reduced. Further, since the shield electrode SHE has a fixed potential, the potential of the display electrode PE is stabilized.

  Therefore, it is possible to reduce (prevent) occurrence of liquid crystal display defects due to sensor operation.

[Second Embodiment]
FIG. 8 is a diagram schematically illustrating the structure of the display device according to the second embodiment. FIG. 8A is a plan view of the display device viewed from the array substrate 10 side, and FIG. 8B is a cross-sectional view taken along the arrow AB. The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 8, the second embodiment is different from the first embodiment in that the size of the counter electrode CE is different. In addition, although the width of the coupling pulse electrode CPL is displayed narrower than the conventional one, FIG. 6 is a schematic diagram, and the width of the coupling pulse electrode CPL is the same as the conventional one.

Here, if the shortest distance between the end of the display electrode PE and the end of the counter electrode CE is d, and the shortest distance between the end of the coupling pulse electrode CPL and the end of the counter electrode CE is e, the formula (1 ) Is established.
d ≧ 3 × e (1)
The relationship of this formula (1) is as follows: the shortest distance c between the display electrode PE and the counter electrode CE in the cross-sectional view, the shortest distance a between the display electrode PE and the counter electrode CE in the plan view, and the coupling pulse electrode CPL in the plan view. Using the shortest distance b from the counter electrode CE, it is expressed by the formula (2).
a ² ≧ 9 × b ² + 8 × c ² Formula (2)
FIG. 9 is a diagram illustrating the correspondence between the cross-sectional structure of the display device according to the second embodiment and the sensor circuit 12.

  By setting the distance between the counter electrode CE and the coupling pulse electrode CPL short, a parasitic capacitance Cso is generated between the counter electrode CE and the coupling pulse electrode CPL. Further, since the counter electrode CE functions in the same manner as the shield electrode SHE, the parasitic relationship between the coupling pulse electrode CPL and the display electrode PE is satisfied by satisfying the relationship of the above-described formulas (1) and (2). The capacity Cpc is reduced to about 10% as compared with the conventional configuration. Therefore, the voltage change of the display electrode PE accompanying the voltage change of the coupling pulse electrode 7 can be reduced. Furthermore, since the shield electrode SHE has a fixed potential, the potential does not change even when the voltage of the coupling pulse electrode 7 changes, and the potential of the display electrode PE is stabilized.

  Therefore, it is possible to reduce (prevent) occurrence of liquid crystal display defects due to sensor operation. Further, since the shield electrode SHE is not used as compared with the first embodiment, the display aperture ratio can be increased.

  The sensor circuit is not limited to the configuration of the above-described embodiment. Any structure can be used as long as it can read the strength and weakness of capacitive coupling with the dielectric.

[Variations of this embodiment]
The above-described embodiment can be configured as various variations.

(1) In the above-described embodiment, each TFT is configured using a p-type thin film transistor, but may be configured using an n-type thin film transistor.

(2) In the above-described embodiment, the touch panel having an active sensor circuit has been described. However, the active sensor circuit is not limited to the above-described configuration. The present invention can also be applied to a touch panel having a passive sensor circuit.

(3) The display device 1 according to the embodiment may be a liquid crystal display device that employs a display mode such as a TN (Twisted Nematic) mode, an IPS mode, or an OCB (Optically Compensated Bend) mode.

(4) The display device according to the above embodiment can be applied to a color display type and a monochrome display type display device.

(5) The coupling pulse may not be supplied from the gate line GL. For example, a wiring parallel to the signal line SL may be added to form a coupling pulse line.

(6) The timing controller TCON is not limited to being provided on the circuit board 60, and may be provided externally or on the TFT substrate.

(7) The amplification TFT 9 is not limited to the embodiment, and may be configured using an amplifier.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  PNL ... liquid crystal display panel, DYP ... display unit, YD ... scanning line drive circuit, XD ... signal line drive circuit, PGL ... protective glass, GL ... gate line, SL ... signal line, PX ... liquid crystal pixel, CPL ... coupling pulse Line, PGL ... Precharge gate line, RG ... Gate line, PRL ... Precharge line, ROL ... Read line, TCON ... Timing controller, RGL ... Gate line, PSEL ... Precharge selection line, PPS ... Voltage source, RSEL ... Selection Line, PGL ... Gate line, 6 ... Precharge TFT, 7 ... Detection electrode, Css ... Coupling capacitance, 9 ... Amplification TFT, 12 ... Sensor circuit, 13 ... Compensation TFT, 14 ... Power supply switching TFT, 15 ... Precharge line Selection TFT, 16... Read line selection TFT.

Claims (9)

A pixel circuit having a pixel composed of a counter electrode and a display electrode sandwiching a liquid crystal layer arranged in a matrix;
A plurality of sensor circuits arranged between rows of the plurality of pixel circuits to read the strength of capacitive coupling with a dielectric;
A plurality of drive signal lines for driving the sensor circuit extended along the row direction of the plurality of pixel circuits;
A shield that is electrically connected to a fixed potential and is provided between a specific drive signal line and the pixel circuit to reduce a voltage change of the display electrode via a parasitic capacitance due to a voltage change of the specific drive signal line. have a and the electrode,
The plurality of drive signal lines include a precharge gate line, a coupling pulse line, and a read gate line,
The sensor circuit is
A sensing electrode that forms a capacitance with the dielectric;
A precharge line for applying a voltage to the detection electrode;
A readout line for reading a detection signal from the detection electrode;
A precharge transistor in which one of the source and drain electrodes is connected to the precharge line and the gate electrode is connected to the precharge gate line;
An amplification transistor in which one electrode of the source / drain is connected to the other electrode of the precharge transistor, and a gate electrode is connected to the detection electrode;
A read transistor in which one electrode of the source / drain is connected to the other electrode of the amplification transistor, the other electrode is connected to the read line, and a gate electrode is connected to the read gate line;
A compensation transistor in which one electrode of the source / drain is connected to the other electrode of the amplification transistor, the other electrode is connected to the detection electrode, and a gate electrode is connected to the precharge gate line;
A display device comprising: a power source switching transistor in which one electrode of a source / drain is connected to one electrode of an amplification transistor, the other electrode is connected to a coupling pulse line, and a gate electrode is connected to a readout gate line. A control unit for controlling each transistor of the sensor circuit;
The control unit performs control so as to have a precharge period for applying a voltage to the detection electrode and a read period for reading the voltage generated in the detection electrode due to the presence or absence of contact with the dielectric via the read line. The display device according to claim 1 . The controller is
In the precharge period,
Control is performed so that an initialization voltage lower than a precharge voltage is applied to the detection electrode via the precharge line and the readout line, and then a precharge voltage is applied to the detection electrode via the precharge line. The display device according to claim 2 . The controller is
In the precharge period,
The display device according to claim 3 , wherein the compensation transistor is controlled so that the other electrode of the amplification transistor and the detection electrode are electrically connected. The controller is
In the readout period,
The electrical connection between the source / drain electrodes of the precharge transistor and the compensation transistor is cut off, and the electrical connection between the source / drain electrodes of the power supply switching transistor and the read transistor is controlled to be conducted. The display device according to claim 4 . A pixel circuit having a pixel composed of a counter electrode and a display electrode sandwiching a liquid crystal layer arranged in a matrix;
A plurality of sensor circuits arranged between rows of the plurality of pixel circuits to read the strength of capacitive coupling with a dielectric;
A plurality of drive signal lines for driving the sensor circuit extended along the row direction of the plurality of pixel circuits;
A fixed potential are electrically connected, it possesses a shield electrode to reduce the voltage change of the display electrode through the parasitic capacitance due to the voltage change of a particular drive signal line,
The size of the counter electrode is longer than the display electrode in the column direction,
The shortest distance a in the column direction between the display electrode and the counter electrode in the plan view of the display device, the shortest distance b in the column direction between the counter electrode and the specific drive signal line in the plan view of the display device, and A display device having the following relationship between the shortest distance c between the counter electrode and the display electrode.
a ² ≧ 9 × b ² + 8 × c ² The plurality of drive signal lines include a precharge gate line, a coupling pulse line, and a read gate line,
The sensor circuit is
A sensing electrode that forms a capacitance with the dielectric;
A precharge line for applying a voltage to the detection electrode;
A readout line for reading a detection signal from the detection electrode;
A precharge transistor in which one of the source and drain electrodes is connected to the precharge line and the gate electrode is connected to the precharge gate line;
An amplification transistor in which one electrode of the source / drain is connected to the other electrode of the precharge transistor, and a gate electrode is connected to the detection electrode;
A read transistor in which one electrode of the source / drain is connected to the other electrode of the amplification transistor, the other electrode is connected to the read line, and a gate electrode is connected to the read gate line;
A compensation transistor in which one electrode of the source / drain is connected to the other electrode of the amplification transistor, the other electrode is connected to the detection electrode, and a gate electrode is connected to the precharge gate line;
And connected to one electrode of the one electrode is the amplification transistor of a source-drain, it claims the other electrode is connected to the coupling pulse line, a gate electrode is provided with a power supply switching transistor connected to the read gate line 6 The display device described in 1. A control unit for controlling each transistor of the sensor circuit;
The control unit performs control so as to have a precharge period for applying a voltage to the detection electrode and a read period for reading the voltage generated in the detection electrode due to the presence or absence of contact with the dielectric via the read line. The display device according to claim 7 . The controller is
In the precharge period,
Control is performed so that an initialization voltage lower than a precharge voltage is applied to the detection electrode via the precharge line and the readout line, and then a precharge voltage is applied to the detection electrode via the precharge line. The display device according to claim 8 .

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