JP5850350B2 - Surface display device and electronic device - Google Patents

Description

  The present invention relates to a surface display device and an electronic device, and more particularly, to a surface display device and an electronic device provided with a touch sensor capable of detecting the presence or absence of contact of a finger or a pen and a contact position coordinate on a display surface. .

  The touch sensor is a device that detects the position pointed by using a finger or a pen or the presence / absence of a pointing operation, and is usually a surface display device such as a liquid crystal display device (LCD) or a plasma display device (PDP). Used in combination. An easy-to-use man-machine interface is realized by inputting the output signal of the touch sensor to the computer and controlling the device by the computer or controlling the display content of the surface display device. Currently, touch panels have been put into practical use in game machines, personal digital assistants, ticket vending machines, automatic teller machines (ATMs), car navigation systems, and the like.

  As a touch sensor system, an analog capacitive coupling system, a resistive film system, an infrared system, an ultrasonic system, and an electromagnetic induction system are known. Among these, the analog capacitive coupling method is further classified into a projected capacitive type and a surface capacitive type. A surface capacitive touch sensor is composed of a transparent substrate, a uniform transparent conductive film formed thereon, and a thin insulating film formed thereon. When driving, an alternating voltage is applied from the four corners of the transparent conductive film. When the touch sensor is touched with a finger, a minute current flows through the finger due to the capacitance formed by the surface of the touch surface and the finger. This current flows from each corner to the touched point. The controller obtains the ratio of each current and calculates the coordinates of the touch position. As for the technology related to the surface capacitive type touch sensor, Patent Document 1 discloses a basic device, and Patent Document 2 discloses a known example related thereto. Further, Non-Patent Document 1 discloses the latest technical trend of the analog capacitive coupling method.

  In the past, analog capacitive coupling type touch sensors used a surface capacitive touch sensor formed on a transparent substrate and a surface display device in an overlapping manner. However, in such a configuration, the presence of the touch sensor on the display surface has a problem that the thickness of the device itself increases, costs increase, and display quality is impaired. Thus, techniques for solving these problems are disclosed in Patent Documents 3 and 4.

  Patent Document 3 discloses an apparatus that attaches current detectors to four corners of a common electrode that applies a voltage to liquid crystal, and calculates the position coordinates of the contact portion based on the current flowing in the four corners. In Patent Document 4, a liquid crystal display circuit that supplies a display voltage or current to the transparent counter electrode, a position detection circuit that detects current flowing from a plurality of locations of the transparent counter electrode, and any one of these circuits are provided. An apparatus is disclosed that includes a switching circuit that is in electrical communication with a transparent common electrode. According to both documents, the common electrode or the transparent counter electrode serves as a surface capacitive transparent conductive film, and it is not necessary to separately add a surface capacitive touch sensor to the display device. It is said that problems such as increase in cost, cost, and display quality are impaired.

U.S. Pat. No. 4,293,734 Japanese Examined Patent Publication No. 56-500230 JP 2003-99192 A JP 2003-66417 A Japanese Patent No. 3121592

Supervised by Yuji Mitani, “Technology and Development of Touch Panels”, CM Publishing, December 1, 24, p. 54-64

  However, the display devices disclosed in Patent Documents 3 and 4 have several problems.

  The first problem is that the signal amount related to the indicated position or presence / absence of the pointing operation is small. The inventor of the present application has found through experiments that the signal amount is smaller in the configurations disclosed in Patent Documents 3 and 4 than in the configuration of Non-Patent Document 1. Since there is no clear grounding point (ground) in the human body, it is difficult to calculate the capacitance (impedance) of the finger, and experiments were important. The signal amount index in the configuration of Non-Patent Document 1 and the configurations disclosed in Patent Documents 3 and 4, that is, the experimental result of the impedance value formed by the finger and the touch sensor will be described later.

  A second problem is that a signal (this is referred to as an invalid signal) that is not related to the indicated position or the presence or absence of the indicated operation, that is, noise is large. A signal related to the indicated position or presence / absence of the pointing operation (referred to as an effective signal) is a current flowing through the finger due to the capacitance formed by the surface of the touch surface and the finger as described above. In addition to this effective signal, a current through a capacitor other than the finger flows in the transparent conductive film of the surface capacitive touch sensor. In the case of the configurations of Patent Documents 3 and 4, the transparent conductive film usually has a liquid crystal layer of several microns sandwiched between the pixel array circuits and forms a large capacitance. The inventor of the present application has found that the capacitance is extremely large compared to the capacitance formed by the surface of the touch surface and the finger by actually measuring the capacitance.

  From these first and second problems, it was derived that the signal-to-noise ratio of the signal relating to the position in the display device disclosed in Patent Documents 3 and 4 or the presence or absence of the pointing operation is very low. As a result, new problems have been found such that the position coordinates cannot be detected and the signal processing circuit is expensive.

  The third problem is that the pixel switch cannot be kept off, leak current is generated, and display performance is deteriorated. According to Patent Literature 4, an AC voltage of 2 to 3 volts is applied to the opposing conductive film during the position detection period. At this time, since the pixel electrode has high impedance and is strongly capacitively coupled with the counter electrode, the pixel electrode similarly varies within a range of 2 to 3 volts. Therefore, the gate-source voltage (Vgs) of a thin film transistor (TFT) that is a pixel switch may fluctuate, and the switch may be intermittently turned on. The present inventor has found this problem.

  SUMMARY OF THE INVENTION A first object of the present invention is to provide a touch sensor integrated surface display device suitable for reduction in weight, size and thickness without deteriorating display characteristics.

  The second object of the present invention is to provide the surface display device at a low cost.

  The third object of the present invention is to save resources.

  According to a first aspect of the present invention, there is provided a surface display device including a display device substrate on which an electrode for applying an electrical signal to a display element element that has an electro-optical response is formed, and the surface display device An impedance surface on a surface corresponding to the display area of the display, and a current detection circuit for detecting a current flowing through the impedance surface, and formed by the impedance surface and the indicator detected by the current detection circuit. A function of detecting the presence or absence of the indicator or a position coordinate based on a current corresponding to the electrostatic capacity, and an electrode for supplying an electric signal to the display element element during a period in which the current detection circuit detects the current. Among them, at least one of electrodes for transmitting an electric signal from the outside of the display area to the inside of the display area is set to high impedance.

According to a second aspect of the present invention, there is provided a surface display device including a display device substrate on which an electrode for applying an electric signal to a display element element that has an electro-optical response is formed, and the display device substrate Is a pixel formed on a substrate with a plurality of scanning lines and a plurality of signal lines as electrodes for applying an electrical signal to the display element element, and further formed in the vicinity of the intersection of the scanning lines and the signal lines An electrode and a switch element that turns on and off the electrical connection between the pixel electrode and the signal line, and has a display region formed by the arrangement of the pixel electrode, and has an impedance on a surface corresponding to the display region A current detection circuit for detecting a current flowing through the impedance surface, and detecting a capacitance between the impedance surface and the indicator by the current detection circuit, A function of detecting the presence or absence of the indicator or a position coordinate based on the corresponding current, and during the period in which the current detection circuit detects the current, the scanning line and the signal line are connected to a voltage source outside the display area. And high impedance.
According to a third aspect of the present invention, there is provided a surface display device including a display device substrate on which an electrode for applying an electric signal to a display element element that has an electro-optical response is formed, and the display device substrate Is a pixel formed on a substrate with a plurality of scanning lines and a plurality of signal lines as electrodes for applying an electrical signal to the display element element, and further formed in the vicinity of the intersection of the scanning lines and the signal lines An electrode and a switch element that turns on and off the electrical connection between the pixel electrode and the signal line, and has a display region formed by the arrangement of the pixel electrode, and has an impedance on a surface corresponding to the display region A current detection circuit for detecting a current flowing through the impedance surface, and detecting a capacitance between the impedance surface and the indicator by the current detection circuit, A function of detecting the presence or absence of the indicator or a position coordinate based on the corresponding current, and during the period in which the current detection circuit detects the current, the scanning line and the signal line are connected to a voltage source outside the display area. The voltage of the scanning line and the signal line that are high impedance is the same amplitude and phase as the voltage of the impedance plane.

  According to the present invention, during the period in which the current detection circuit detects a current, at least one of the wirings or electrodes arranged from the outside to the inside of the display region among the wirings or electrodes for supplying an electric signal to the display element element is high. By using impedance, the S / N of the position detection signal is dramatically improved. Further, since the S / N of the position detection signal is dramatically improved, the cost of the signal processing circuit can be reduced. Further, the switching element in the display device substrate is kept off, and display characteristics are not deteriorated.

  Further, according to the present invention, since the impedance surface serves as a transparent conductive film of the surface capacitive touch sensor, it is not necessary to separately add a surface capacitive touch sensor to the display device, and the thickness of the device can be reduced. And resources can be saved.

It is the perspective view which showed typically the structure of the display apparatus which concerns on Example 1 of this invention. It is the time chart which showed typically the mode of the voltage of the main electrode of the display apparatus which concerns on Example 1 of this invention. It is the elements on larger scale which showed typically the composition of the pixel circuit part of the display concerning Example 1 of the present invention. It is the schematic diagram which showed the drive condition of the display drive period in the display apparatus which concerns on Example 1 of this invention. 5 is a time chart schematically showing a voltage state of each electrode when the display device according to Example 1 of the present invention is driven under the driving conditions of FIG. 4. It is a schematic diagram for demonstrating the position detection principle of the surface capacitive touch sensor applied to the display apparatus which concerns on Example 1 of this invention, (a) when there is no finger, (b) when there is a finger It is. It is a schematic diagram for demonstrating the position detection principle of the surface capacitive type touch sensor applied to the display apparatus which concerns on a prior art. It is sectional drawing which showed typically the structure of the display apparatus which concerns on a prior art, (a) is a structure of a nonpatent literature 1, (b) is a structure based on patent documents 3 and 4. FIG. It is a circuit diagram for demonstrating the position detection principle of the display apparatus which concerns on Example 1 of this invention. It is the time chart which showed typically the mode of the voltage of each electrode at the time of driving the display apparatus which concerns on a prior art. It is the perspective view which showed typically the structure of the modification 1 of the display apparatus which concerns on Example 1 of this invention. It is the perspective view which showed typically the structure of the modification 2 of the display apparatus which concerns on Example 1 of this invention. It is the perspective view which showed typically the structure of the modification 3 of the display apparatus which concerns on Example 1 of this invention. It is the perspective view which showed typically the structure of the modification 4 of the display apparatus which concerns on Example 1 of this invention. It is the perspective view which showed typically the structure of the modification 5 of the display apparatus which concerns on Example 1 of this invention. It is the perspective view which showed typically the structure of the modification 6 of the display apparatus which concerns on Example 1 of this invention. It is the perspective view which showed typically the structure of the modification 7 of the display apparatus which concerns on Example 1 of this invention. It is a circuit diagram for demonstrating the position detection principle of the display apparatus which concerns on Example 2 of this invention. It is the fragmentary sectional view which showed typically the structure of the display apparatus which concerns on Example 3 of this invention.

  The surface display device according to the present invention includes a switch disposed on the scanning line and the signal line.

  The surface display device of the present invention includes a control circuit that controls switching of the switch, and the control circuit controls the scanning line and the signal line to high impedance during a period in which the current detection circuit detects a current. To do.

  In the surface display device of the present invention, the output of the first drive circuit that drives the scanning line and the second drive circuit that drives the signal line is in a high impedance state during a period in which the current detection circuit detects current. It becomes.

  In the surface display device of the present invention, the display device substrate has one end connected to the switch element and the pixel electrode and the other end of the capacitor and extends to the outside of the display area. A capacitor line; and a switch disposed on the capacitor line, and controlling the switching of the switch disposed on the capacitor line during a period in which the current detection circuit detects a current. Control to high impedance.

  In the surface display device of the present invention, the display device substrate has a capacitor having one end connected to the switch element and the pixel electrode, the other end of the capacitor being connected to the scanning line, and the current detection circuit. During the period in which the current is detected, the scanning line is controlled to have a high impedance by controlling the switching of the switch arranged on the scanning line.

  In the surface display device of the present invention, the impedance surface is formed on a counter substrate facing the display device substrate via the display element element.

  In the surface display device of the present invention, the display element element is any one of a liquid crystal, an electrophoretic body, charged particles, an electrochromic material, an electroluminescent material, a gas, a semiconductor, and a phosphor.

  In the surface display device of the present invention, the display element element is mainly composed of liquid crystal, and the impedance surface is made of a transparent conductive film.

  In the surface display device of the present invention, the current detection circuit applies an AC voltage to the impedance surface and detects a current flowing through the impedance surface by applying the AC voltage.

  In the surface display device of the present invention, there are a plurality of the current detection circuits corresponding to a plurality of locations on the impedance surface, and each of the current detection circuits is a location corresponding to a plurality of locations on the impedance surface. The AC voltage is applied to the current, and the current at the location of the impedance surface corresponding to the AC voltage is detected.

  The surface display device of the present invention includes a position detection circuit that detects a contact coordinate of a contact object on the impedance surface based on an output signal of the current detection circuit.

  In the surface display device of the present invention, a flexible material is used for the base material of the display device substrate and the counter substrate.

  In the surface display device of the present invention, a linearization pattern is formed on the impedance surface.

  In the surface display device of the present invention, the display device substrate includes a counter substrate disposed at a position facing the display device substrate with the display element element interposed therebetween, and the impedance surface is located on the counter substrate side of the display device substrate. It exists on the surface opposite to the surface.

  In the surface display device of the present invention, the display device has a counter substrate disposed at a position facing the display device substrate via the display element element, and the impedance surface is located on the display device substrate side of the counter substrate. It exists on the surface opposite to the surface.

  In the present invention, the surface display device is mounted on an electronic device.

  A surface display device according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view schematically showing a configuration of a surface display device according to Embodiment 1 of the present invention.

  Referring to FIG. 1, the surface display device 1 is a liquid crystal display device (LCD) and includes a touch sensor that can detect the presence or absence of a finger or a pen and a contact position coordinate on the display surface. Is. The surface display device 1 may be a surface display device such as a plasma display device (PDP) organic EL display device in addition to a liquid crystal display device. The surface display device 1 includes a display device substrate 10, a counter substrate 19, a liquid crystal 2, and a polarizing plate (not shown).

  The display device substrate 10 has electrodes (signal lines (signal electrodes) 4a to 4c, scanning lines (scanning electrodes) 6a to 6c, storage capacitance lines (storage) in FIG. 1) for applying an electrical signal to the liquid crystal 2 in the display region 11. (Capacitance electrodes) 8a to 8c) are formed. A pixel matrix portion is formed in the display area 11 on the surface of the display device substrate 10 on the counter substrate 19 side. The pixel matrix portion includes a plurality of signal lines (4a to 4c in FIG. 1), a plurality of scanning lines (6a to 6c in FIG. 1) intersecting with the signal lines, and storage capacitor lines (between the scanning lines). In FIG. 1, it is composed of 8a to 8c) and pixel circuits arranged corresponding to the respective intersections.

  The pixel circuit includes a pixel switch TFT, a storage capacitor, and a pixel electrode. In the pixel switch TFT (switching element), scanning lines 6a to 6c for controlling on / off of the TFT are connected to the gate electrode, and a signal line for supplying a signal to the pixel electrode to one of the drain electrode and the source electrode. 4a to 4c are connected, and a storage capacitor and a pixel electrode are connected to the other of the drain electrode and the source electrode. The storage capacitors are connected to the corresponding storage capacitor lines 8a to 8c.

  A scanning line driving circuit 14, a signal line driving circuit 15, and a storage capacitor line driving circuit for driving the pixel matrix portion are disposed on the outer peripheral portion of the display region 11 in the display device substrate 10. The scanning line driving circuit 14 is a circuit for driving the scanning lines 6a to 6c. The signal line drive circuit 15 is a circuit for driving the signal lines 4a to 4c. The storage capacitor line drive circuit is a circuit for applying a voltage signal to the storage capacitor lines 8a to 8c, and is connected to the COM terminal.

  The display device substrate 10 is provided with electrodes 29a to 29d in the vicinity of the four corners of the surface on the counter substrate 19 side. The electrodes 29a to 29d are electrically connected to the corresponding electrodes 28a to 28d of the counter substrate 19 through the corresponding conduction means 20a to 20d, and are electrically connected to the corresponding switches 21a to 21d.

  In addition, in the outer peripheral portion of the display region 11, the signals of the scanning lines 6 a to 6 c are provided so that the circuit in the pixel matrix portion and the circuit in the outer peripheral portion of the display region 11 can be electrically set to high impedance. Switches 16a to 16c are provided for the paths, switches 17a to 17c are provided for the signal paths of the signal lines 4a to 4c, and switches 18a to 18c are provided for the signal paths of the storage capacitor lines 8a to 8c, respectively. 18c is provided. The switches 16a to 16c, 17a to 17c, and 18a to 18c are switching-controlled by a control circuit (not shown). Thereby, the scanning lines 6a to 6c and the signal lines 4a to 4c for transmitting an electrical signal from the outside to the inside of the display area 11 can be set to high impedance.

  The display device substrate 10 is produced using, for example, a manufacturing process of a low-temperature polysilicon TFT. Further, the switches (16a to 16c, 17a to 17c, 18a to 18c) can be configured by analog switches using n-type TFTs. Further, the scanning line driving circuit 14 and the signal line driving circuit 15 can be configured using n-type TFTs and p-type TFTs.

  On the other hand, the counter substrate 19 includes a glass substrate 23, a color filter (not shown) formed on the surface on the liquid crystal 2 side, and a transparent conductive film 12 formed on the surface on the liquid crystal 2 side of the color filter. Have The transparent conductive film 12 is a counter electrode made of ITO and constitutes an impedance surface. In the transparent conductive film 12, electrodes 28a to 28d are disposed in the vicinity of the four corners of the display device substrate 10 side. The electrodes 28a to 28d are electrically connected to the corresponding electrodes 29a to 29d of the display device substrate 10 through conduction means 20a to 20d using a conductive material such as silver paste. A polarizing plate (not shown) is disposed on the surface of the glass substrate 23 opposite to the display device substrate 10 side.

  Each of the electrodes 29a to 29d is electrically connected to a single pole double throw type switch 21a to 21d. In the switches 21a to 21d, AC voltage sources 22a to 22d are electrically connected to one contact through current detection circuits 13a to 13d, and the other contact is electrically connected to the storage capacitor line drive circuit via a COM terminal. Connected. The current detection circuits 13a to 13d detect the current flowing through the transparent conductive film 12 (impedance surface) at the electrodes 28a to 28d. A signal relating to the current detected by the current detection circuits 13a to 13d is output to a position detection circuit (not shown). In the position detection circuit, the contact position with the finger 24 on the glass substrate 23 is detected based on the output signals of the current detection circuits 13a to 13d. The AC voltage sources 22a to 22d supply an AC voltage to the transparent conductive film 12 through corresponding current detection circuits 13a to 13d and electrodes 28a to 28d.

  The liquid crystal 2 is a display element element that is disposed between the display device substrate 10 and the counter substrate 19 and has an electro-optical response.

  Next, the operation of the display device according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a time chart schematically showing voltage states of main electrodes of the display device according to the first embodiment of the present invention. Refer to FIG. 1 for the configuration of the display device.

  Here, in FIG. 2, Vc represents the voltage of the transparent conductive film (12 in FIG. 1), and 6a, 6b to 6x represent the voltages of the respective scanning lines in the order of scanning. SW represents the voltage of the control signal that determines the state of the switch 16, the switch 17, the switch 18, and the switch 21. Although FIG. 1 schematically shows an example of three scanning lines, it may be designed arbitrarily, and 6x corresponds to the voltage of the scanning line scanned last.

  The surface display device 1 has two periods, that is, a display drive period and a position detection period, for driving. These two periods are divided in time. The display drive period is a period for writing a voltage for pixel display. The position detection period is a period in which the current detection circuits 13a to 13d detect current in order to detect the position of the finger 24 or the presence or absence of the pointing operation.

The position detection period uses a vertical blanking period. The vertical blanking period refers to a period during which the scanning lines 6a to 6c are not scanned. In the position detection period, the switches 16a to 16c, the switches 17a to 17c, and the switches 18a to 18c are all turned off as shown in FIG. 1, and the signal lines 4a to 4c, the scanning lines 6a to 6c, and the storage capacitor lines 8a to 8c are High impedance is applied to wiring outside the display region 11 (wiring connected to the scanning line driving circuit 14, the signal line driving circuit 15, and the COM terminal). In the position detection period, the switches 21a to 21d are in a conductive state with respect to the AC voltage sources 22a to 22d including the current detection circuits 13a to 13d. This state is realized by setting the SW signal in FIG. 2 to B, that is, high level. In such a switch state, that is, the switch state shown in FIG. 1, in-phase AC voltages generated by the AC voltage sources 22 a to 22 d are applied to the four corner electrodes 28 a to 28 d of the transparent conductive film 12. . The voltage of the transparent conductive film 12 is indicated by Vc in FIG. Further, since each scanning line 6a to 6c has high impedance and is capacitively coupled to the transparent conductive film 12, the voltage of the scanning lines 6a to 6c varies with the same amplitude as the voltage amplitude of the transparent conductive film 12. . The AC voltage applied from the four corner electrodes 28 a to 28 d is propagated to the entire surface of the transparent conductive film 12, and a current flows through the finger 24 through the capacitor 25 formed by the finger 24. By calculating signals corresponding to the currents i _{1 to} i ₄ detected by the four current detection circuits 13a to 13d, the presence / absence of the finger 24 and the coordinates of the position of the finger 24 are detected. An example of the calculation is Equation 1 and Equation 2.

Here, x is the x coordinate of the contact position, and y is the y coordinate. k ₁ and k ₂ are constants. Further, i ₁ to i ₄ are currents detected by the current detection circuits 13a to 13d shown in the four corners of FIG. 1, i ₁ is 13a, i ₂ is 13b, i ₃ is 13c, i ₄ Corresponds to 13d.

  As described above, the transparent conductive film 12 serves as the transparent conductive film of the surface capacitive touch sensor during the position detection period.

  Next, the state of the pixel circuit when an AC voltage is applied to the transparent conductive film in the position detection period in the display device according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a partially enlarged perspective view schematically showing the configuration of the pixel circuit portion of the display device according to the first embodiment of the present invention.

  Referring to FIG. 3, in the pixel circuit portion, the pixel electrode 26 and the signal electrode 4 are connected via a TFT switch, and the TFT switch is on / off controlled by a control signal of the scanning electrode 6. The signal electrode 4 is connected to the signal line driving circuit 15 via the switch 17, and the scanning electrode 6 is connected to the scanning line driving circuit 14 via the switch 16. The symbols Vc, Vp, Vs, Vg, and Vd shown on each electrode in FIG. 3 represent the voltage of that electrode. Capacitances C1, C2, and C3 represent the capacitance between the pixel electrode 26 and the transparent conductive film 12, the capacitance between the scanning electrode 6 and the transparent conductive film 12, and the capacitance between the signal electrode 4 and the transparent conductive film 12, respectively.

  Next, drive voltage design values in the display drive period in the display apparatus according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 4 is a schematic diagram illustrating drive conditions during the display drive period in the display device according to the first embodiment of the present invention.

  In the driving during the display driving period, a driving method is adopted in which the voltage Vc of the transparent conductive film 12, that is, the counter electrode is made constant, and a maximum voltage of 5V is inverted with respect to this voltage Vc and applied to the liquid crystal. The counter electrode voltage Vc is set to 6V. On the other hand, + 5V 11V is the maximum voltage (Vpix_high) applied to the pixel electrode 26 through the signal electrode 4, and -5V is 1V to the counter electrode voltage Vc. Becomes the minimum voltage (Vpix_low). Considering the leakage current of the TFT switch, the gate voltage (Vg_off) at the time of switching off is set to 0 V so that the maximum gate-source voltage at the time of switching off becomes −1V. Further, the gate voltage (Vg_on) when the switch is turned on is set to 15 V so that a sufficient on-current can be obtained.

  Next, the voltage of each electrode when the display device according to Example 1 of the present invention is driven under the driving conditions of FIG. 4 will be described with reference to the drawings. FIG. 5 is a time chart schematically showing the voltage state of each electrode when the display device according to the first embodiment of the present invention is driven under the driving conditions of FIG.

  Referring to FIG. 5, in the display drive period, a positive pulse is applied to the gate voltage Vg, and 1 V is written to the pixel electrode voltage Vp. Thereafter, the switches 16 and 17 are turned off, and the process proceeds to the position detection period. In the position detection period, an alternating voltage is applied to the transparent conductive film 12 as described above. Here, an AC voltage (Vc in FIG. 5) having an offset voltage of 6 V and an amplitude of 2 V was applied. At this time, the electrodes facing each other across the 4 micron liquid crystal layer, that is, the pixel electrode 26, the scanning electrode 6, and the signal electrode 4 are high impedance, and the transparent conductive film 12 and the capacitors C1, C2, Since the capacitive coupling is performed via C3, the pixel electrode voltage Vp, the scan electrode voltage Vg, and the signal electrode voltage Vd vary with the same amplitude as the amplitude of the transparent conductive film voltage Vc. Therefore, in the example shown in FIG. 5, since the signal electrode voltage Vd is set to high impedance at 6V, it becomes a voltage having an offset voltage of 6V and an amplitude of 2V. Similarly, the scan electrode voltage Vg has an offset voltage of 0V and an amplitude of 2V. For example, the pixel electrode voltage Vp has an offset voltage of 1V and an amplitude of 2V when the minimum value is taken as an example. Since the pixel electrode 26 is connected to the source electrode 27 of the TFT switch, the source electrode voltage Vs of the TFT switch is equal to the pixel electrode voltage Vp. As described above, since the voltages of all the electrodes in the pixel circuit vary in accordance with the amplitude of the voltage Vc of the transparent conductive film 12, the gate-source voltage Vgs of the TFT switch is a voltage that is a voltage at the end of the display period. In this example, -1V is held during the position detection period. That is, in the position detection period, even if an AC voltage is applied to the transparent conductive film 12, the voltage of all the electrodes of the pixel circuit varies with the same amplitude as the voltage of the transparent conductive film 12. The voltage (Vc−Vp) and the gate-source voltage Vgs of the TFT switch do not change. For this reason, driving in the position detection period does not cause deterioration in image quality.

  On the other hand, in the display drive period, each switch is in a state opposite to the state shown in FIG. That is, the switches 16a to 16c, the switches 17a to 17c, and the switches 18a to 18c are all turned on, and the signal lines 4a to 4c, the scanning lines 6a to 6c, and the storage capacitor lines 8a to 8c are wiring outside the display area 11. Low impedance is set for (the wiring connected to the scanning line driving circuit 14, the signal line driving circuit 15, and the COM terminal). Further, the switches 21a to 21d are in a conductive state with respect to the COM terminal side. This state is realized by setting the SW signal in FIG. 2 to A, that is, a low level. In such a state, like the conventional active matrix LCD, the scanning lines 6a to 6c are sequentially scanned, and a voltage for display is written to the pixels through the signal lines 4a to 4c. During the display drive period, the transparent conductive film 12 is supplied with the same voltage as the counter electrode in the conventional LCD from the COM terminal. That is, the transparent conductive film 12 serves as a counter electrode. Thus, a voltage for display is written to the liquid crystal 2 existing between them.

  According to the first embodiment, the circuit inside the pixel matrix is set to a high impedance with respect to the external circuit during the position detection period. Therefore, when an AC voltage is applied to the transparent conductive film 12, the transparent conductive film 12 sees it. The parasitic capacitance is extremely small. As a result, the S / N ratio of the signals output from the current detection circuits 13a to 13d is improved by two digits compared to the conventional case.

  The above effect will be described below, including a comparison with the prior art, while detailing S (signal) and N (noise) of the S / N ratio.

  First, the principle of position detection of a surface capacitive touch sensor applied to the display device according to Embodiment 1 of the present invention will be described with reference to the drawings. 6A and 6B are schematic views for explaining the position detection principle of the surface capacitive touch sensor applied to the display device according to the first embodiment of the present invention, where FIG. This is when there is a finger. In order to simplify the description, the principle of position detection in the one-dimensional direction will be described.

Referring to FIG. 6A, there is shown a configuration in which current detection circuits 13a and 13b and AC voltage sources 22a and 22b are connected to both ends of a uniform resistor 40, respectively. When alternating voltages having the same phase are applied from both ends of the resistor 40, no current flows through the resistor 40, so both i ₁ and i ₂ are zero.

When the finger 24 is on the resistor 40 as shown in FIG. 6B, the finger 24 can be shown by a model grounded via the impedance Z. Therefore, i ₁ and i ₂ can be expressed by the following equations, respectively.

Here, R ₁ and R ₂ indicate respective resistance values from the position of the finger 24 to the end of the resistor 40. From this, the position x (0 ≦ x ≦ 1) is obtained by the following equation.

Although Equation 5 does not include impedance Z, currents i ₁ and i ₂ include Z, which is a signal for position detection. The inventors confirmed Z in this example by experiments. That is, the structure of Example 1 is a structure in which a polarizing plate (not shown), a glass substrate (23 in FIG. 1), and a transparent conductive film (12 in FIG. 1) are laminated, and a finger is placed on the polarizing plate side. Z when (24 in FIG. 1) was placed was obtained by experiment. Since Z is an impedance formed between the glass substrate and the polarizing plate, it can be treated as a capacitor C. When the thickness of the glass substrate was 0.7 mm and the thickness of the polarizing plate was 0.2 mm, the value of C was 6.7 pF. That is, S (effective signal component) of the S / N ratio of the signals output from the current detection circuits 13a and 13b is a current flowing through this C.

  For reference, in the case of the configuration described in Non-Patent Document 1, the value of C was 30 pF. As described in the problem of the prior art, a small signal means that when the configuration described in Non-Patent Document 1 is compared with Patent Document 3 and Patent Document 4, the capacity is reduced in this way, and the effective signal is reduced accordingly. Means that.

  Next, the noise component will be described. When the conventional technique is implemented based on the position detection principle shown in FIG. 6, a parasitic capacitance Cp is connected to the resistor 40 in addition to the impedance Z by the finger 24 as shown in FIG. 7. The outputs of the current detection circuits 13a and 13b are obtained by superimposing the current via the parasitic capacitance Cp, and the current via the parasitic capacitance Cp does not include information on the position of the finger 24. That is, the current through the parasitic capacitance Cp becomes a noise component. This inventor calculated | required the value of this parasitic capacitance Cp by experiment.

  In the case of the configuration described in Non-Patent Document 1 shown in FIG. 8A, the parasitic capacitance Cp is formed by the transparent conductive film 103 and the shield layer 101 formed on the glass substrate 102. At a suitable size, the value was 29 pF. On the other hand, in the case of the configuration based on Patent Documents 3 and 4 shown in FIG. 8B, the parasitic capacitance Cp is formed by the transparent conductive film 204 disposed with the liquid crystal 203 interposed therebetween and the electrodes constituting the pixel matrix circuit 202. The size was 15000 pF. As described in the problem of the prior art, when the noise is large, comparing the configuration described in Non-Patent Document 1 and Patent Documents 3 and 4, Patent Documents 3 and 4 have an overwhelmingly large parasitic dose in this way. This means that noise increases.

  From the above results, the S / N ratios when Patent Documents 3 and 4 are implemented are as follows.

S / N = (current value flowing through capacitance by finger) / (current value flowing through parasitic capacitance Cp)
= (6.7 pF) / (15000 pF)
≒ 4 × 10 ^-4

  That is, the output signal of the current detection circuit contains almost no component relating to position detection, and it has been impossible to detect the position from the signal having the S / N, or the cost is very high. A signal processing circuit was required. Alternatively, since the S / N is low, there is a problem that it takes a long time to detect position coordinates for calculating a signal over a plurality of cycles.

  On the other hand, in the display device according to Embodiment 1 of the present invention, each switch is in the state shown in FIG. 1 during the position detection period. That is, the switches 16a to 16c, the switches 17a to 17c, and the switches 18a to 18c are all turned off, and the signal lines 4a to 4c, the scanning lines 6a to 6c, and the storage capacitor lines 8a to 8c are wired outside the display area 11 ( The scanning line driving circuit 14, the signal line driving circuit 15, and the wiring connected to the COM terminal) are set to high impedance. A circuit diagram based on this principle is shown in FIG. The parasitic capacitance Cp in FIG. 9 is the same as the parasitic capacitance Cp in FIG. 7, but one end of Cp is not directly connected to a fixed potential (alternating current ground), but in series with a fixed potential across the capacitor Cs. (AC ground). This Cs is the total value of the capacitance values when the switch group surrounding the pixel matrix portion in FIG. 1 is off. In Example 1, an LCD having a diagonal size of 2.1 inches and a pixel configuration of 176 × RGB × 240 was prototyped, and the value of Cs was 100 pF. As a result, the parasitic capacitance of the resistance element is a series connection of Cp and Cs, and its value is 100 pF. Therefore, S / N in Example 1 is as follows.

S / N = (6.7 pF) / (100 pF)
= 6.7 × 10 ⁻²

  That is, Example 1 confirmed the remarkable effect that the S / N ratio was improved by two digits compared to the cases of Patent Documents 3 and 4 (see FIG. 8B). As a result, the coordinates of the position can be detected, and a very expensive signal processing circuit is not required. In addition, the time until position detection is shortened.

  In the description with reference to FIG. 5, in the case of the configuration of the first embodiment, it is described that the gate switch-source voltage Vgs of the TFT switch is maintained at −1V, which is the voltage at the end of the display period, even during the position detection period. did. The condition of −1V is when the voltage written to the pixel is the lowest, that is, when Vpix_low (1V) shown in FIG.

  On the other hand, in the case of Patent Documents 3 and 4, Vgs varies. Referring to FIG. 10, in the position detection period, the pixel electrode has high impedance and is capacitively coupled to the transparent conductive film through the capacitor. Therefore, the pixel electrode voltage Vp is equal to the voltage Vc of the transparent conductive film. It fluctuates with the same amplitude as the amplitude. Therefore, when an alternating current with an amplitude of 2V is applied to the voltage Vc of the transparent conductive film, the pixel electrode voltage Vp also varies with an amplitude of 2V accordingly. On the other hand, the scanning line voltage Vg is fixed to 0 V, which is a voltage for turning off the pixel switch. As a result, the gate-source voltage Vgs of the TFT switch fluctuates with a voltage amplitude of 2V, with -1V being the offset voltage. For this reason, the switch TFT cannot continue to be kept off, resulting in image quality degradation.

  On the other hand, in the case of Example 1, as described above, the Vgs of the transistor does not vary. For this reason, it is possible to obtain a special effect that driving in the position detection period does not cause deterioration in image quality.

  In the first embodiment, n-type TFTs are used as the switches 16a to 16c, 17a to 17c, and 18a to 18c that make the inside and the outside of the display region 11 electrically high impedance. Or a transfer gate combining n-type and p-type. In addition, although the driving circuit is formed by an n-type TFT and a p-type TFT, it may be formed by either one, that is, only a p-type TFT or only an n-type TFT. Since these various types of switches can be selected, when implementing the present invention, it is possible to provide switches without increasing the manufacturing cost. More specifically, as described in the first embodiment, when the signal line driving circuit and the scanning line driving circuit are configured using n-type and p-type polysilicon TFTs, an n-type switch and a p-type switch are used. The switch can be provided without increasing the number of manufacturing steps, regardless of which switch is selected from the combination of the n-type and p-type transfer gates. When an n-type or p-type switch is selected, the circuit area is reduced compared to the transfer gate, and the control is simplified. Furthermore, there is an effect of suppressing the parasitic capacitance when the switch is turned off, and as a result, an effect of suppressing the deterioration of the signal-to-noise ratio regarding the position or presence / absence of the indicated operation can be obtained. In particular, in the case of an n-type switch, since the on-resistance is lower than that of the p-type, the size of the switch can be further reduced, and the parasitic capacitance can be reduced. On the other hand, a transfer gate is desirable from the viewpoint of suppressing the drive voltage. In a display device, when the circuit excluding the switch that electrically connects the inside and outside of the display area is composed of either an n-type or a p-type transistor, either one of the transistors is used accordingly. By using the switch to form the switch, the switch can be provided without increasing the number of manufacturing steps.

  The switches 16a to 16c, 17a to 17c, and 18a to 18c are provided outside the scanning line driving circuit 14 and outside the signal line driving circuit 15. However, these switches may be included inside the driving circuit. Good. When included in the scanning line driving circuit 14, for example, it can be realized by a circuit configuration capable of ternary output (high level, low level, high impedance). In this case, for example, a clocked inverter circuit can be applied. Further, by controlling the transistors in the output stage of the driver circuit to have a high impedance, the circuit area can be suppressed by adopting a configuration in which the transistor in the output stage also serves as a switch.

  In the first embodiment, the transparent conductive film 12 is also present at a position opposite to the position where the scanning line driving circuit 14 and the signal line driving circuit 15 are provided. From the viewpoint of reducing the parasitic capacitance of the transparent conductive film. It is desirable to minimize the area of the transparent conductive film 12, and therefore, the transparent conductive film 12 at a position opposite to the position where the drive circuits 14 and 15 are disposed may be removed.

  In the first embodiment, the transparent conductive film 12 is also present at a position opposite to the position where the scanning line driving circuit 14 and the signal line driving circuit 15 are disposed. In this case, from the viewpoint of reducing the parasitic capacitance of the transparent conductive film 12, the power supply lines of the drive circuits 14 and 15 may be set to high impedance during the position detection period. In this case, since the transparent conductive film exists, a capacitance is formed between the power supply line or the electrodes constituting the circuit and the transparent conductive film, and the potential relationship between the nodes in the circuit is maintained by this function. Therefore, even in the case of a dynamic circuit or a register circuit, the stored contents are not destroyed during the high impedance, and the continuous operation can be resumed by changing to the low impedance after setting the high impedance.

  In the first embodiment, the display device substrate 10 is formed by a low-temperature polysilicon TFT process, but may be formed by an amorphous silicon TFT process. Furthermore, other TFT processes such as a microcrystal silicon TFT process, an oxide TFT process, an organic TFT process, a process of forming a TFT after transferring a silicon thin film onto a support substrate, and the like may be used. At this time, as means for making the inside and the outside of the display region 11 electrically high impedance, the function is integrated in a bulk silicon driver LSI, or an amorphous silicon switch is formed on the display device substrate 10. And realized. Further, it can be realized by mounting the switch array LSI created by the low-temperature polysilicon TFT process on the display device substrate 10 or connecting it outside the display device substrate. Further, the display device substrate 10 may be formed over a single crystal silicon substrate (bulk silicon) or may be formed using an SOI substrate. Alternatively, the display device substrate 10 may be formed by forming a circuit using a polysilicon TFT process, an amorphous silicon TFT process, a bulk silicon process, an SOI process, or the like and then transferring the circuit to another substrate.

  Further, a so-called linearization pattern may be formed on the transparent conductive film 12. In this regard, with reference to FIG. 11, the linearization pattern 80 is provided in order to make the electric field curve formed on the surface of the transparent conductive film 12 uniform. In this embodiment, since the linearization pattern is formed on the transparent conductive film 12 which is a conductive film for position detection, the linearity between the position and the current signal is improved in position detection.

  Moreover, in Example 1, although the transparent conductive film 12 is provided in the surface at the side of the liquid crystal 2 of the glass substrate 23, you may provide the transparent conductive film 12 in the surface on the opposite side. Even in this case, the effect of reducing the parasitic capacitance of the transparent conductive film 12 can be obtained by applying the present invention. The transparent conductive film 12 may be formed by forming a film on the glass substrate 23 by sputtering or vapor deposition, or may be formed by attaching a sheet. Further, it is also possible to use a polarizing plate having conductivity and use it as a position detecting conductive film of a surface capacitive touch sensor. In particular, when using an in-plane switching (IPS) liquid crystal mode, these methods are suitable.

  In Example 1, although the base material of the glass substrate 23 and the display apparatus substrate 10 is made of glass, a flexible material may be used. In this case, since a transparent conductive film for position detection is integrally formed on the counter substrate, mechanical distortion is hardly generated with respect to bending, and the position detection performance is not deteriorated by bending.

  In the first embodiment, one switch 18a to 18c is provided for each storage capacitor line 8a to 8c, but the switches 18a to 18c of the storage capacitor lines 8a to 8c are not necessarily required. This is because the voltage applied to the storage capacitor lines 8a to 8c and the voltage applied to the transparent conductive film 12 serving as the counter electrode may be the same voltage. In this case, since the same signal as the AC signal applied to the counter electrode during the position detection period is applied to the storage capacitor line, it cannot be seen as a parasitic capacitance when viewed from the counter electrode. Therefore, in such a case, the switches 18a to 18c are not necessary.

  Further, in the first embodiment, one switch 18a to 18c is provided for each storage capacitor line. However, these switches are removed and a node on the upstream side of the storage capacitor line 8a to 8c on the signal source side, for example, A small number of switches may be provided at the node given the COM symbol described on the display device substrate 10 of FIG.

  In Example 1, the transparent conductive film 12 made of ITO was used as the impedance surface, and the resistor 40 was assumed as the impedance of the equivalent circuit. However, according to the frequency of the alternating current applied to the impedance surface, the resistance, An arithmetic expression for detecting the relationship between the current value and the coordinates of the touch position or the presence / absence of the touch may be derived by solving the equivalent circuit in consideration of the impedance including the capacitance and the inductor.

  In the first embodiment, the resistor 40 formed in a planar shape is used as the impedance surface. However, an inductor formed in a planar shape or a capacitor formed in a planar shape may be used as the impedance surface.

  Further, in Example 1, it is assumed that the liquid crystal 2 serving as a display element element is disposed between the display device substrate 10 and the counter substrate 19, and that the viewer of the display device exists on the counter substrate 19 side. Although the configuration is such that the finger 24 on the side is detected, the configuration may be based on the assumption that an observer of the display device is present on the display device substrate 10 side. FIG. 12 shows the configuration. In this case, in order to detect a finger (not shown) on the display device substrate 10 side, a transparent conductive film 81 is formed on the surface of the display device substrate 10 on the observer side, and this is used as a conductive film for position detection. To do. Even in such a configuration, as described above, the parasitic capacitance of the conductive film for position detection could be remarkably reduced by setting the signal line and the scanning line to high impedance during the position detection period. . This effect is becoming more pronounced especially with the recent thinning of the display device substrate 10. Further, as shown in FIG. 13, a configuration in which a means for setting the signal line or the scanning line to high impedance is removed may be employed. Further, as shown in FIG. 14, a transparent conductive film 81 may be provided on the counter substrate 19 side to detect the finger 24 on the counter substrate 19 side. Further, as shown in FIG. 15, a configuration in which a means for setting the signal line or the scanning line to high impedance is removed may be employed. In FIGS. 12 to 15, the method of turning on and off the pixels by applying an electric field in the vertical direction of the liquid crystal 2, that is, the direction perpendicular to the plate surface of the display device substrate 10 is described as an example. In the case of using a liquid crystal mode in which a pixel is turned on / off by applying an electric field in a direction horizontal to the display device substrate, the configuration shown in FIG. As shown in FIG. 16, the transparent conductive film is not formed on the surface of the counter substrate 19 on the display device substrate 10 side, and the transparent conductive film 81 for position detection is formed on the surface opposite to the surface on the display device substrate 10 side. . Further, as shown in FIG. 17, a configuration in which a means for setting the signal line or the scanning line to high impedance is removed may be employed. The transparent conductive film 81 is used for position detection and can prevent the counter substrate 19 from being charged, so that it has the effect of eliminating image quality deterioration due to charging.

  A display apparatus according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 18 is a circuit diagram for explaining the position detection principle of the display device according to the second embodiment of the invention.

In the first embodiment, the AC voltage is directly applied to the resistor (40 in FIG. 9). However, in the second embodiment, the indicator 30 (for example, an electronic pen) is connected to the AC voltage source 22, and the impedance Z is Current detection circuits 13a and 13b detect currents i ₁ and i ₂ flowing therethrough. Also in this case, the inside and the outside of the display area (corresponding to 11 in FIG. 1) are set to high impedance during the position detection period.

According to the second embodiment, the parasitic capacitance of the resistor 40 is drastically reduced by setting the inside and outside of the display area to high impedance. As a result, the current flowing in and out through the parasitic capacitance is remarkably reduced, the currents i ₁ and i ₂ flowing in and out of the current detection circuits 13a and 13b are increased, and the signal amount is increased. As a result, the S / N of the position detection signal is dramatically improved, and a touch sensor integrated display device can be realized.

  A display apparatus according to Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 19 is a partial cross-sectional view schematically showing the configuration of the display device according to Example 3 of the present invention.

  The display device according to Example 3 is an electrophoretic display device (EPD) using a microcapsule electrophoretic element, and is a monochrome EPD active matrix display. The display device includes a counter substrate 19, an EPD film 50, and a display device substrate 10.

  In the counter substrate 19, for example, the counter electrode 12 made of a transparent conductive film is formed on the inner surface side of a transparent plastic substrate 23 such as polyethylene terephthalate. The counter substrate 19 may use a glass substrate instead of the plastic substrate 23.

  The EPD film 50 is a film-like electrophoretic display device and includes a microcapsule 51 and a binder 55. The microcapsule 51 is laid inside the EPD film 50 and has a size of about 40 μm. Inside the microcapsule 51, a solvent 52 made of isopropyl alcohol (IPA) or the like is sealed, and white particles 53, which are titanium oxide-based white pigments, each having a nano-level size in the solvent 52, Black particles 54, which are carbon black pigments, are dispersed and floated. The white particles 53 have a minus (−) charging polarity, and the black particles 54 have a plus (+) charging polarity. The binder 55 is made of a polymer filled for bonding between the microcapsules 51.

  The display device substrate 10 has a configuration in which a thin film transistor (TFT 70) is formed on a glass substrate 71. The TFT 70 is an inverted staggered type in which the gate G is disposed closer to the glass substrate 71 than the source S and drain D. In the TFT 70, a gate G is formed on a glass substrate 71, an insulating film 72 serving as a gate insulating film is formed on the gate G, a channel material 73 is formed on the insulating film 72, and a source is formed on both outer sides of the channel material 73. S, the drain D is formed, the insulating film 74 is formed on the insulating film 72 including the channel material 73, the source S, and the drain D, the pixel electrode 60 is formed on the insulating film 74, and the pixel electrode 60 is the source S. And vias are connected.

  In FIG. 19, the gate G of each TFT 70 is electrically connected to a corresponding scanning line (not shown), and the drain D of each TFT 70 is electrically connected to a corresponding signal line (not shown). ing. By applying a voltage to the gate G, the + voltage applied to the drain D is supplied to the corresponding pixel electrode 60 through the channel material 73 and the source S. When a positive voltage is supplied to the pixel electrode 60, the white particles 53 in the corresponding microcapsule 51 are attracted toward the pixel electrode 60, and the black particles 54 in the microcapsule 51 are attracted relatively to the counter electrode 12. . On the other hand, when a negative voltage is supplied to the pixel electrode 60, the black particles 54 in the corresponding microcapsule 51 are attracted to the pixel electrode 60 side, and the white particles 53 in the microcapsule 51 are relative to the counter electrode 12. Gravitate. As described above, in the display device shown in FIG. 19, a monochrome image can be displayed on the counter electrode 12 side depending on whether a positive voltage or a negative voltage is applied to the pixel electrode 60.

  Conductive means 20 (for example, silver paste) for electrically connecting the electrode 61 of the display device substrate 10 and the counter electrode 12 is provided between the counter substrate 19 and the display device substrate 10 at the corner of the display device. Yes. A single-pole double-throw switch 21 is connected to the electrode 61 of the display device substrate 10. A current detection circuit 13 and an AC voltage source 22 are connected in series to one contact of the switch 21, and a counter electrode is connected to the other contact. A COM terminal to which the drive circuit is connected is connected. In FIG. 19, the switch 21 is connected to one end of the switch, but actually, it is connected to four corners as in FIG.

  In the third embodiment, similarly to FIG. 1, the signal line driving circuit for driving the signal lines and the scanning line driving circuit for driving the scanning lines are provided outside the display region. A switch is provided on the signal path of the line and the scanning line driving circuit and on the signal path of the signal line and the signal line driving circuit, and these wirings for transmitting an electric signal from the outside to the inside of the display area are high. It is comprised so that it may become an impedance.

  Further, the display device according to the third embodiment also detects the display driving period for writing a voltage for display to the pixel and the position coordinates of the finger or the presence / absence of the pointing operation, as in the first embodiment. In addition, the current detection circuit has two periods including a position detection period in which current is detected. These two periods are divided in time.

  According to the third embodiment, the EPD has a characteristic of holding the display for a long time after the voltage for display is written, so that the ratio of the position detection period can be increased as compared with the case of the LCD. Become. In addition, a display device having flexibility and a touch sensor function can be realized by thinning the display device substrate 10 or transferring the pixel circuit to the flexible substrate.

  In the first to third embodiments, the liquid crystal display device and the electrophoretic display device have been described. However, other methods such as charged particles, electrochromic material, electroluminescent material (EL material), gas, semiconductor, fluorescence Of course, it can be applied to a display device using the body.

  Examples of use of the present invention include game machines, portable information terminals, ticket vending machines, automatic teller machines (ATMs), car navigation systems, TV / game machines to be installed in passenger seats of airplanes and buses, factory automation (FA) equipment, printers And display devices used for facsimiles.

DESCRIPTION OF SYMBOLS 1 Display apparatus 2 Liquid crystal 4 Signal electrode 4a, 4b, 4c Signal line 6 Scan electrode 6a, 6b, 6c Scan line 8a, 8b, 8c Storage capacity line 10 Display apparatus substrate 11 Display area 12 Transparent conductive film (counter electrode)
13, 13a, 13b, 13c, 13d Current detection circuit 14 Scan line drive circuit 15 Signal line drive circuit 16, 16a, 16b, 16c Switch 17, 17a, 17b, 17c Switch 18, 18a, 18b, 18c Switch 19 Counter substrate 20 , 20a, 20b, 20c, 20d Conducting means 21, 21a, 21b, 21c, 21d Switch 22, 22a, 22b, 22c, 22d AC voltage source 23 Glass substrate (plastic substrate)
24 finger 25 capacity 26 pixel electrode 27 source electrode 28a, 28b, 28c, 28d electrode 29a, 29b, 29c, 29d electrode 30 indicator 40 resistor 50 EPD film 51 microcapsule 52 solvent 53 white particle 54 black particle 55 binder 60 pixel Electrode 61 Electrode 70 TFT
71 Glass substrate 72, 74 Insulating film 73 Channel material 80 Linearization pattern 81 Transparent conductive film 101 Shield layer 102 Glass substrate 103 Transparent conductive film 104 Overcoat layer 201 Lower substrate 202 Pixel matrix circuit 203 Liquid crystal 204 Transparent conductive film 205 Upper side Substrate 206 Polarizing plate

Claims (14)

A surface display device including a display device substrate on which an electrode for applying an electric signal to a display element element having an electro-optical response is formed,
In the display device substrate, a plurality of scanning lines and a plurality of signal lines are formed on the substrate as electrodes for applying an electric signal to the display element element, and further, in the vicinity of an intersection of the scanning lines and the signal lines. A formed pixel electrode, and a switch element for turning on and off the electrical connection between the pixel electrode and the signal line,
A display area formed by the arrangement of the pixel electrodes;
Having an impedance surface on the surface corresponding to the display area;
Furthermore, it has a current detection circuit for detecting the current flowing through the impedance surface,
The capacitance between the impedance surface and the indicator is detected by the current detection circuit,
Having a function of detecting the presence or absence of the indicator or position coordinates based on the current corresponding to the capacitance;
Period in which the current detecting circuit detects current, Ri high impedance der the scanning lines and the signal lines to a voltage source that outside the display area,
A surface display device, wherein the voltage of the scanning line and the signal line having high impedance has the same amplitude and the same phase as the voltage of the impedance surface .   2. The surface display device according to claim 1, further comprising a switch disposed on the scanning line and the signal line. A control circuit for controlling the switching of the switch;
3. The surface display device according to claim 2, wherein the control circuit controls the scanning lines and the signal lines to high impedance during a period in which the current detection circuit detects a current.   The output of the first drive circuit that drives the scanning line and the second drive circuit that drives the signal line is in a high impedance state during a period in which the current detection circuit detects a current. 1. A surface display device according to 1. The display device substrate provides an electric signal to a capacitor connected at one end to the switch element and the pixel electrode, and the display element element connected to the other end of the capacitor and extending to the outside of the display region. A capacitor line as an electrode for the electrode, and a switch disposed on the capacitor line,
4. The surface display according to claim 3, wherein the capacitance line is controlled to have a high impedance by controlling switching of the switch arranged on the capacitance line during a period in which the current detection circuit detects a current. apparatus. The display device substrate has a capacitor having one end connected to the switch element and the pixel electrode, and the other end of the capacitor is connected to the scanning line,
4. The surface display device according to claim 3, wherein the scanning line is controlled to have a high impedance by controlling switching of a switch disposed on the scanning line during a period in which the current detection circuit detects a current. .   The surface display device according to claim 1, wherein the impedance surface is formed on a counter substrate facing the display device substrate through the display element element.   8. The display element according to claim 1, wherein the display element element is any one of a liquid crystal, an electrophoretic material, a charged particle, an electrochromic material, an electroluminescent material, a gas, a semiconductor, and a phosphor. A surface display device according to claim 1. The display element element is mainly composed of liquid crystal,
The surface display device according to claim 1, wherein the impedance surface is made of a transparent conductive film.   The current detection circuit applies an AC voltage to the impedance surface and detects a current flowing through the impedance surface by applying the AC voltage. Surface display device. There are a plurality of the current detection circuits corresponding to a plurality of locations on the impedance surface,
11. Each of the current detection circuits applies the AC voltage from locations corresponding to a plurality of locations on the impedance surface, and detects current on the impedance surface at locations corresponding thereto. The surface display device described.   The surface display device according to claim 1, further comprising a position detection circuit that detects contact coordinates of a contact object on the impedance surface based on an output signal of the current detection circuit.   The surface display device according to claim 7, wherein a flexible material is used for a base material of the display device substrate and the counter substrate.   An electronic device comprising the surface display device according to claim 1.

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