JP2005208481A - Electrooptical device, electronic equipment, and flexible wiring substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively reduce noises and ripples of a common electric potential to be supplied to a driving circuit of an electrooptical panel. <P>SOLUTION: The liquid crystal panel 10 has a plurality of two-dimensionally arrayed pixel electrodes 12 and a counter electrode 171 placed opposite to the pixel electrodes 12 across a liquid crystal 182. A power supply circuit 33 to generate a low potential side power supply electric potential Gnd and a common electric potential Vcom to be applied to the counter electrode 171 is mounted on a wiring substrate 30. An FPC 20 has a flexible base material 21 fixed to the liquid crystal panel 10 and the wiring substrate 30, a common wire 231 to supply the common electric potential Vcom to the liquid crystal panel 10 and an earth wire 232 to supply the low potential side power supply electric potential Gnd to the liquid crystal panel 10. A chip condenser 251 interposed between the common wire 231 and the earth wire 232 is mounted on the base material 21. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technique for supplying various potentials such as a power supply potential to an electro-optical panel that displays an image using an electro-optical material such as liquid crystal.

  Various electro-optical devices represented by a liquid crystal device include an electro-optical panel having a plurality of pixels. For example, an active matrix type electro-optical panel in which a transistor is employed as an active element for controlling voltage application to a pixel includes a plurality of pixel electrodes arranged in a matrix, and an electro-optical material applied to these pixel electrodes. And opposed electrodes facing each other. Under this configuration, a potential corresponding to a display image is applied to a plurality of pixel electrodes, and a potential (hereinafter referred to as a “common potential”) is applied to a counter electrode. Various images corresponding to the applied voltage are displayed. As disclosed in Patent Document 1, a power supply circuit for generating various potentials such as a power supply potential and a common potential is a wiring connected to an electro-optical panel via a flexible wiring board (hereinafter referred to as “FPC”). Generally, it is mounted on a substrate.

JP 2002-182604 A (paragraph 0015 and paragraph 0042)

  Incidentally, noise and ripple may occur in the power supply potential and common potential output from the power supply circuit. In particular, since the common potential is a potential applied to the electro-optic material, if noise or ripple occurs in the common potential, a voltage different from the intended voltage is applied to the electro-optic material. There may be a problem that degradation of quality is caused. As a measure for solving this problem, it is conceivable to mount a bypass capacitor (for example, a chip capacitor) connected in parallel to each output wiring from the power supply circuit on the wiring board. However, even if noise and ripple are reduced by the capacitor on the wiring board, the common potential and other power supply potentials are supplied to the electro-optical panel after passing through the inductance component formed by the wiring of the flexible wiring board. There is a limit to removing noise and ripple of the common potential and power supply potential that are actually supplied to the electro-optic panel. The present invention has been made in view of such circumstances, and an object thereof is to effectively reduce noise and ripple of each potential supplied from the wiring board to the electro-optical panel via the FPC. .

  In order to achieve this object, an electro-optical device according to the present invention includes a plurality of pixel electrodes arranged in a planar shape and a counter electrode facing the plurality of pixel electrodes with an electro-optical material interposed therebetween. A wiring board provided with a power supply circuit for generating a power supply potential and a common potential applied to the counter electrode, and a flexible base material fixed to the electro-optical panel and the wiring board. A flexible wiring board having capacitance is provided between a first wiring for supplying a potential to the electro-optical panel and a second wiring for supplying a common potential to the electro-optical panel. The “electro-optical substance” in the present invention is a substance that converts an electrical action such as current and voltage into an optical action such as transmittance and luminance, such as liquid crystal or organic EL (ElectroLuminescent).

  In this configuration, the electrostatic capacitance between the first wiring to which the common potential is applied and the second wiring to which the power supply potential (typically ground potential) is applied is generated between the electro-optical panel and the wiring board. It is provided on a flexible wiring board interposed therebetween. For this reason, noise and ripple of common potential and power supply potential are removed by electrostatic capacitance at a stage after passing through the inductance component formed by wiring of the flexible wiring board in addition to the inductance component formed by wiring of the wiring board, Each potential after the removal is supplied to the electro-optical panel. Therefore, according to the present invention, noise and ripples of the common potential and power supply potential supplied to the electro-optical panel are reduced, and good display quality is realized. Note that the common potential is typically a substantially constant potential, but may be a potential whose level varies every specific time (for example, in synchronization with the polarity inversion of the voltage applied to the pixel electrode).

  More specifically, a chip capacitor mounted on the plate surface of the substrate can be employed as a capacitance for smoothing the common potential or the power supply potential. According to this aspect, it is possible to use a chip capacitor having a capacitance value sufficient to eliminate noise and ripple of the common potential or the power supply potential as the smoothing capacitance. In order to more effectively reduce the influence of the inductance component of the wiring provided on the flexible wiring board, in the vicinity of the end connected to the electro-optical panel of the first wiring and the second wiring (that is, It is desirable to reduce noise and ripple of the common potential or power supply potential (just before the power supply potential is output to the electro-optical panel). For example, a smoothing capacitance is provided on the electro-optical panel side as viewed from the center of the base material and the end portion fixed to the wiring board and the end portion fixed to the electro-optical panel.

  In another aspect, a smoothing capacitance is configured using the first wiring and the second wiring as electrodes. According to this configuration, since it is not necessary to mount an electrical component such as a chip capacitor separate from the wiring on the substrate, the number of components can be reduced and the manufacturing process can be simplified. In addition, in order to mount a chip capacitor used as a smoothing capacitance on a substrate, a method such as soldering is used. In this case, it is necessary to form the substrate with a heat-resistant material. is there. On the other hand, when wiring is also used as an electrode for capacitance, the presence or absence of heat resistance of the base material does not matter, so that there is an advantage that a base material made of a cheaper material can be used.

  In an aspect in which the capacitance is formed by the first and second wirings, each of the first wiring and the second wiring has electrode portions that overlap each other when viewed from the direction perpendicular to the plate surface of the substrate. A configuration may be employed. According to this configuration, since the capacitance value of the smoothing capacitance can be increased, the common potential and the power supply potential are compared with a configuration in which the first wiring and the second wiring are simply adjacent to each other on the substrate. Noise can be reduced more effectively. Here, in order to secure a sufficient capacitance value for the smoothing capacitance, the area of the electrode portion (particularly the width of the wiring) needs to be relatively wide. Therefore, the structure which made the 1st wiring and the 2nd wiring wide wiring over the full length can also be employ | adopted. However, in this configuration, the space on the base material occupied by the wiring becomes large. In particular, it is desirable to reduce the space occupied by the first wiring and the second wiring because a large number of wirings are concentrated on the portion of the base material that is joined to the electro-optical panel or the wiring board. Therefore, in a desirable aspect of the present invention, each of the first wiring and the second wiring is formed with an end portion fixed to the wiring board and an end portion fixed to the electro-optical panel of the base material. A wiring portion is provided, and the electrode portion described above is wider than the wiring portion (the width of the wiring portion is narrower than the width of the electrode portion). According to this configuration, the capacitance portion can have a sufficient capacitance value due to the wide electrode portion, while the space of the portion to be joined to the electro-optical panel or the wiring board is reduced by the wiring portion. Is done.

  In addition, an electronic apparatus according to the present invention includes the above-described electro-optical device as a display device. According to the electro-optical device of the present invention, noise and ripple of the common potential and the power supply potential are effectively reduced. Therefore, the electro-optical device is particularly suitable as a display device for an electronic apparatus that requires good display quality. Further, in a high-definition display device having an extremely large number of pixels, slight noise and ripple generated in the common potential and the power supply potential can seriously affect the display quality. According to the electro-optical device according to the present invention, noise and ripples affected by the inductance component of the flexible wiring board are also effectively reduced, and therefore, particularly effective when applied to a high-definition display device. .

  Furthermore, the present invention can be implemented as a flexible wiring board interposed between the electro-optical panel and the wiring board. That is, the flexible wiring board includes a first wiring for supplying a common potential to the electro-optical panel on a plate surface of a flexible base material fixed to the electro-optical panel and the wiring board, and a power source. A second wiring for supplying a potential to the electro-optical panel is formed, and a smoothing capacitance is provided between the first wiring and the second wiring. According to this flexible wiring board, for the same reason as described above for the electro-optical device according to the present invention, the common potential supplied from the power supply circuit of the wiring board and the noise and ripple of the power supply potential are effectively reduced. The electro-optic panel can be supplied.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings shown below, the dimensions and ratios of the constituent elements are different from actual ones for convenience. In the following first to third embodiments, modes in which the present invention is applied to a liquid crystal device using a liquid crystal as an electro-optical material will be exemplified.

<A: First Embodiment>
FIG. 1 is a plan view showing the configuration of the liquid crystal device according to the first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II in FIG. As shown in these drawings, the liquid crystal device 100 includes a liquid crystal panel 10, an FPC 20, and a wiring board (printed board) 30. Among these, the liquid crystal panel 10 is a device for displaying various images by a plurality of pixels arranged in a matrix, and is sandwiched between the element substrate 11 and the counter substrate 17 bonded together via the sealing material 181 and the two substrates. A liquid crystal 182. On the surface of the counter substrate 17 facing the liquid crystal 182, as shown in FIG. 2, a counter electrode 171 is provided over substantially the entire surface.

  On the other hand, on the plate surface of the element substrate 11 facing the liquid crystal 182, as shown in FIG. 1, a plurality of scanning lines 131 extending in the X direction and connected to the scanning line driving circuit 141, and Y A plurality of data lines 133 extending in the direction and connected to the data line driving circuit 143, and the scanning lines 131 and the pixel electrodes 12 connected to the data lines 133 via thin film transistors (not shown) are provided. . One pixel includes a pixel electrode 12, a counter electrode 171 facing the pixel electrode 12, and a liquid crystal 182 sandwiched between the two electrodes. The scanning line driving circuit 141 and the data line driving circuit 143 formed on the element substrate 11 are circuits that drive pixels by supplying driving signals (scanning signals and data signals) to the pixel electrodes 12.

  A large number of wirings 15 are formed on a portion 11 a of the element substrate 11 that protrudes from the peripheral edge of the counter substrate 17 (hereinafter referred to as “extended portion”). These wirings 15 are patterned so that one end reaches the peripheral edge 11 b of the element substrate 11. The other ends of these wirings 15 are connected to input terminals of the scanning line driving circuit 141 and the data line driving circuit 143. Further, the above-described counter electrode 171 is electrically connected to the wiring 15 through a conductive material (not shown) provided in at least one of the four corners of the counter substrate 17.

  On the other hand, the wiring board 30 is a rigid board on which various electronic circuits for driving the liquid crystal panel 10 are mounted. As shown in FIGS. 1 and 2, a power supply circuit 33 is mounted on the wiring board 30. The power supply circuit 33 includes a counter electrode in addition to the high power supply potential Vcc and the low power supply potential (ground potential) Gnd used by the scanning line drive circuit 141 and the data line drive circuit 143 of the liquid crystal panel 10 to generate drive signals. 17 is a circuit for generating a common potential Vcom applied to the circuit 17. A large number of wirings 31 are formed on the plate surface of the wiring board 30. These wirings 31 are used to transmit signals output from various electronic circuits including the power supply circuit 33, and are patterned from each electronic circuit to the connection portion 35 in FIG. For example, the wiring 311 illustrated in FIG. 1 is formed so as to extend from the terminal from which the common potential Vcom is output in the power supply circuit 33 to the connection portion 35, and the wiring 312 is output from the lower power supply potential Gnd in the power supply circuit 33. It is formed so as to extend from the terminal to the connecting portion 35.

  The liquid crystal panel 10 and the wiring board 30 are connected via the FPC 20. The FPC 20 includes a film-like base material 21 having flexibility. On the substrate surface of the base material 21 that faces the liquid crystal panel 10 and the wiring substrate 30 (the back-side plate surface in FIG. 1), the wiring substrate extends from an end 21 a fixed to the liquid crystal panel 10 of the base material 21. A large number of wirings 23 are formed so as to reach the end 21 b fixed to 30. These wirings 23 are for electrically connecting the wiring board 30 and the liquid crystal panel 10. More specifically, in the state where the end portion 21 a of the base material 21 is fixed to the overhanging portion 11 a of the element substrate 11 via an anisotropic conductive film (not shown), each wiring 23 is connected to the periphery of the element substrate 11. It is electrically connected to the wiring 15 formed in 11b. On the other hand, in a state where the end portion 21 b of the base material 21 is fixed to the connection portion 35 of the wiring substrate 30 via an anisotropic conductive film (not shown), each wiring 23 is electrically connected to the wiring 31 reaching the connection portion 35. Connected. Among these wirings 23, the wiring 231 shown in FIG. 1 (hereinafter sometimes referred to as “common wiring 231” in some cases) is electrically connected to the wiring 311 reaching the connection portion 35 of the wiring substrate 30 and is common. The potential Vcom is supplied to the liquid crystal panel 10. On the other hand, the wiring 232 (hereinafter sometimes referred to as “ground line 232” in particular) is electrically connected to the wiring 312 of the wiring board 30 and supplies the lower power supply potential Gnd to the liquid crystal panel 10.

  As shown in FIG. 1, the common wiring 231 and the ground line 232 are adjacent to each other on the base material 21. A chip capacitor 251 is interposed between the common wiring 231 and the ground line 232. Here, FIG. 3 is an equivalent circuit diagram showing an electrical relationship between the common wiring 231 and the ground line 232 and the chip capacitor 251. As shown in FIGS. 1 and 3, the chip capacitor 251 is mounted on the substrate 21 so that one end thereof is connected to the common wiring 231 and the other end is connected to the ground line 232. Accordingly, the chip capacitor 251 is connected in parallel with the power supply circuit 33 via the common wiring 231 and the ground line 232 and functions as a smoothing capacitor (bypass capacitor). The chip capacitor 251 is mounted in the vicinity of the end 21 a bonded to the liquid crystal panel 10 in the base material 21. A straight line Lc in FIG. 1 is a straight line passing through a central portion of the end 21a bonded to the liquid crystal panel 10 and the end 21b bonded to the wiring board 30 in the base material 21 (that is, the end 21a and the end 21b Straight line at an approximately equal distance from The chip capacitor 251 is disposed on the liquid crystal panel 10 side when viewed from the straight line Lc.

  Thus, in this embodiment, since the chip capacitor 251 that functions as a smoothing capacitor is mounted on the FPC 20, the common potential Vcom and the lower power supply potential Gnd output from the power supply circuit 33 are shown in FIG. As described above, noise and ripple are removed at a stage after passing through the inductance component L2 of the wiring 23 provided in the FPC 20 in addition to the inductance component L1 of the wiring 31 provided in the wiring board 30. Therefore, according to the present invention, noise and ripple of the common potential Vcom applied to the counter electrode 17 can be effectively reduced as compared with the configuration in which the smoothing capacitor is provided on the wiring board 30. Moreover, according to the present embodiment, since the chip capacitor 251 is provided in the vicinity of the end 21 a fixed to the liquid crystal panel 10 in the base material 21, in the vicinity of the end 21 b fixed to the wiring board 30. Compared with the configuration in which the chip capacitor 251 is provided, the influence of the inductance component L2 of the wiring 23 of the FPC 20 can be reduced.

<B: Second Embodiment>
In the above embodiment, the configuration using the chip capacitor 251 as the smoothing capacitor is exemplified. On the other hand, in the present embodiment, the common wiring 231 and the ground line 232 are also used as electrodes of the smoothing capacitor. FIG. 4 is a plan view showing the configuration of the FPC 20 according to the present embodiment, and FIG. 5 is a cross-sectional view taken along line VV in FIG. 4, the plate surface of the base material 21 that faces the element substrate 11 and the wiring substrate 30 of the liquid crystal panel 10 is shown on the front side (that is, the front and back of the FPC 20 are reversed from those in FIG. 1). . In addition, among the components of the liquid crystal device 100 according to the present embodiment, those that operate in the same manner as in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

  As shown in FIGS. 4 and 5, each of the common wiring 231 to which the common potential Vcom is applied and the ground line 232 to which the lower power supply potential Gnd is applied are the end 21a and the end 21b of the base material 21. Wiring portions 28a and 28b positioned in the vicinity of each of the wiring portions 28a and 28b, and electrode portions 29 formed wider than the wiring portions 28a and 28b. The wiring portions 28a and 28b and the electrode portion 29 in each of the common wiring 231 and the ground line 232 are integrally formed in a common process by patterning a single conductive film.

  As shown in FIG. 4, when viewed from the direction perpendicular to the plate surface of the base material 21, the electrode portion 29 of the common wiring 231 and the electrode portion 29 of the ground line 232 overlap each other. On the other hand, the wiring portions 28 a and 28 b of the common wiring 231 and the wiring portions 28 a and 28 b of the ground wire 232 are formed at different positions on the substrate 21 so as to be separated from each other. More specifically, as shown in FIG. 4, the electrode portion 29 of the common wiring 231 is formed so as to protrude from the wiring portions 28 a and 28 b of the common wiring 231 toward the grounding wire 232, while the grounding wire 232. The electrode portion 29 is formed so as to protrude from the wiring portions 28 a and 28 b of the ground line 232 toward the common wiring 231, and these protruding portions overlap each other. As shown in FIGS. 4 and 5, the electrode portion 29 of the common wiring 231 and the electrode portion 29 of the ground line 232 are electrically insulated by an insulating layer 261 interposed therebetween. More specifically, as shown in FIG. 5, an insulating layer 261 is formed so as to cover the electrode portion 29 of the common wiring 231 formed on the plate surface of the base material 21, and on the surface of the insulating layer 261. An electrode portion 29 of the ground line 232 is formed. The insulating layer 261 is a film body made of an insulating material having a high dielectric constant. Therefore, the capacitor 252 is constituted by the electrode portion 29 of the common wiring 231 and the electrode portion 29 of the ground line 232 which are opposed to each other with the insulating layer 261 interposed therebetween. On the other hand, the electrode portion 29 of the ground wire 232 is covered with a coating layer 262 (not shown in FIG. 4). The covering layer 262 is a film body for protecting the ground wire 232 and is formed of, for example, a resin material.

  According to this configuration, the capacitor 252 configured by the common wiring 231 and the ground line 232 functions as a smoothing capacitor connected in parallel with the power supply circuit 33, and thus a circuit similar to that in FIG. 3 is configured. Therefore, also according to the present embodiment, noise and ripple of the power supply potential supplied to the scanning line driving circuit 141 and the data line driving circuit 143 are effectively reduced as compared with the case where the smoothing capacitor is provided on the wiring board 30. can do.

  In the present embodiment, the configuration in which the insulating layer 261 provided separately from the base material 21 is interposed between the common wire 231 and the ground wire 232 is illustrated. However, the electrode portion 29 of the common wire 231 A configuration in which the electrode portion 29 of the grounding wire 232 is opposed to the grounding wire 232 via the substrate 21 can also be adopted. That is, as shown in FIGS. 6 and 7, the electrode portion 29 of the common wiring 231 is formed on one plate surface 21 c of the base 21 and the electrode portion 29 of the ground wire 232 is formed on the other plate surface of the base 21. The structure which forms in 21d and makes it mutually oppose can also be employ | adopted. However, in order to connect both the common wiring 231 and the ground line 232 to the wiring 31 of the wiring board 30 and the wiring 15 of the liquid crystal panel 10, the common wiring 231 is provided in the vicinity of the end 21a and the end 21b of the base 21. And the ground line 232 need to be present on the bonding surface (the surface facing the element substrate 11 or the wiring substrate 30). Therefore, in the configuration shown in FIGS. 6 and 7, the wiring portions 28a and 28b of the common wiring 231 are formed on the plate surface 21d, and the electrodes formed on the wiring portions 28a and 28b and the plate surface 21c. The portion 29 is electrically connected through a through hole 21 e provided in the base material 21. With this configuration, the same effects as those of the above embodiments can be obtained. In addition, according to the configuration shown in FIGS. 6 and 7, the film body (insulating layer 261 shown in FIG. 5) inserted as a dielectric between the common wiring 231 and the ground line 232 is attached to the base material 21. Therefore, the manufacturing process can be simplified as compared with the second embodiment.

<C: Third Embodiment>
In particular, in a liquid crystal device using liquid crystal as an electro-optical material, there may be a case where charges remain in each pixel electrode 12 and the counter electrode 171 even after the image display is completed. Such residual charges (hereinafter referred to as “residual charges”) cause various problems. For example, the direct current voltage resulting from the residual charge continues to be applied to the liquid crystal 182 even after the power supply to the liquid crystal panel 10 is stopped, so that the orientation direction of the liquid crystal 182 changes in a direction different from the intended direction, thereby displaying Degradation is caused. Also, even if the image display is once stopped and then the image display is started again, if the charges still remain in the pixel electrodes 12 and the counter electrode 171, they are actually applied to the liquid crystal 182 during the image display. Since the voltage to be displayed differs from the voltage corresponding to the original display image by the amount of the residual charge, the image resulting from the residual charge with respect to the display image (that is, the image that was displayed immediately before the power was turned off last time) Image) is superimposed like an afterimage. Against this background, various techniques have been proposed for solving problems caused by residual charges. For example, Japanese Patent Laid-Open No. 2001-147416 discloses a configuration in which residual charges are removed by setting the pixel electrode and the counter electrode to the same potential when the image display is finished.

  This type of configuration can also be employed in the first and second embodiments described above. More specifically, the lower power supply to all the pixel electrodes 12 is triggered by the input of a signal instructing the end of image display (typically a signal instructing power off) from the host device. It is possible to adopt a configuration in which the potential Gnd is applied and the common potential Vcom applied to the counter electrode 17 is lowered to the lower power supply potential Gnd. According to this configuration, the charge accumulated in each pixel electrode 12 and the counter electrode 171 is removed along with the end of the image display, so that the period during which the image display is stopped (for example, the power is turned off). The situation in which a DC voltage is applied to the liquid crystal 182 in the period) is avoided.

  However, in the configuration of each of the embodiments having the smoothing capacitor having one end connected to the counter electrode 171, electric charge is instantaneously accumulated in the smoothing capacitor when the image display is stopped, and as a result, the common potential Vcom. May not reach the lower power supply potential Gnd. That is, the applied voltage to the counter electrode 171 is instantaneously changed at the timing when the common potential Vcom is started to be lowered when the image display is stopped, and the electric charge caused by the fluctuation (noise) is accumulated in the smoothing capacitor. In particular, since the capacitance of the smoothing capacitor is generally significantly larger (for example, about 30 μF (microfarad)) than the capacitance of other elements in the liquid crystal panel 10, it is applied to the counter electrode 171. A considerable amount of charge is accumulated in the smoothing capacitor due to the noise of the voltage. When charges are accumulated in the smoothing capacitor in this way, the common potential Vcom does not drop to the lower power supply potential Gnd, and therefore, a DC voltage is continuously applied to the liquid crystal 182 even after image display is stopped.

  In the present embodiment, a configuration for preventing such inconvenience and avoiding application of a DC voltage to the liquid crystal 182 is applied to the first or second embodiment. FIG. 8 is an equivalent circuit diagram showing the electrical configuration of the liquid crystal device 10 according to the present embodiment, paying particular attention to the electrical relationship between the common wiring 231 and the ground line 232. In addition, about the part which carries out the effect | action similar to said each embodiment among each part shown in the figure, a common code | symbol is attached | subjected and the detailed description is abbreviate | omitted suitably. Hereinafter, the chip capacitor 251 in the first embodiment and the capacitor 252 in the second embodiment are collectively referred to as “smoothing capacitor 25”.

  As shown in the figure, the present embodiment is common to the above embodiments in that the smoothing capacitor 25 inserted in the common wiring 231 and the ground line 232 is arranged in the FPC 20. The wiring 231 and the ground line 232 are different from the above embodiments in that they are electrically connected via a resistor (hereinafter referred to as “discharge resistor”) 27. More specifically, the discharge resistor 27 has one end connected to the common wiring 231 and the other end connected to the ground line 232. The discharging resistor 27 is based on a resistance as an electrical component mounted on the FPC 20 and connected to the common wiring 231 and the ground line 232 or a conductive material having a higher resistivity than the common wiring 231 or the ground line 232. A wiring formed on the material 21 can be adopted. Here, the configuration in which the discharge resistor 27 is provided on the FPC 20 is illustrated, but the location where the discharge resistor 27 is disposed is arbitrary. For example, a configuration in which a resistor whose one end is connected to the wiring 311 and the other end is connected to the wiring 312 is arranged on the wiring substrate 30 as the discharging resistor 27 can be adopted. Alternatively, a configuration in which a resistor electrically connected to the other end and electrically connected to the wiring 232 (or the wiring 15 connected to the wiring 232) is disposed on the liquid crystal panel 10 as the discharge resistor 27 may be employed. That is, it does not matter whether each end of the discharge resistor 27 is directly connected to the counter electrode 171 or indirectly connected to the counter electrode 171 via another wiring (for example, the wiring 15, 23, or 31). The configuration in which the counter electrode 171 and the ground line 232 are electrically connected via the discharge resistor 27 (that is, the discharge resistor 27 is inserted in the electrical path from the counter electrode 171 to the ground line 232) Configuration) is sufficient.

  According to this configuration, even if charges are accumulated in the smoothing capacitor 25 at the moment when the common potential Vcom starts to decrease, the charges are discharged to the ground line 232 via the discharge resistor 27. That is, the electric charge accumulated in the smoothing capacitor 25 due to the noise of the common potential Vcom is discharged by the discharging resistor 27. Therefore, since the common potential Vcom can be lowered until it substantially coincides with the lower power supply potential Gnd of the ground line 232, a DC voltage is applied to the liquid crystal 182 due to the electric charge accumulated in the smoothing capacitor 25. Is prevented in advance.

  By the way, from the viewpoint of efficiently discharging the charge accumulated in the smoothing capacitor 25, it is desirable that the resistance value of the discharge resistor 27 is lower. In particular, as the capacitance of the smoothing capacitor 25 increases, the amount of charge accumulated therein increases. Therefore, in order to sufficiently discharge this charge, it is necessary to use a discharge resistor 27 having a low resistance value. However, if the resistance value of the discharge resistor 27 is too low, current flows from the counter electrode 171 to the ground line 232 via the discharge resistor 27 over the entire period during which the liquid crystal panel 10 displays an image. Continuing may increase power consumption. According to an experiment by the present inventor, if the resistance value of the discharging resistor 27 is about 100 kΩ (kiloohm), the charge of the smoothing capacitor 25 can be effectively discharged without seriously affecting the power consumption. I came to know. Therefore, the resistance value of the discharge resistor 27 is desirably 100 kΩ or more.

<D: Modification>
Various modifications can be added to the above embodiment. Specific modifications are as follows.

(1) In the second embodiment, the configuration in which the wide electrode portions 29 are provided on the common wiring 231 and the ground line 232 and overlap each other is illustrated. According to this configuration, the capacitance of the smoothing capacitor can be increased as compared with a configuration in which the common wiring 231 and the ground line 232 are simply adjacent on the base material 21. However, if sufficient capacitance can be obtained to remove noise and ripples of the common potential Vcom (or the higher power supply potential Vcc and the lower power supply potential Gnd), the common wiring 231 and the ground line 232 have electrode portions. It is not always necessary to employ a configuration provided with 29 or a configuration in which they are overlapped with each other.

(2) In the above embodiment, the description has been made with a particular focus on the smoothing capacitor 25 provided in the FPC 20, but in addition to this, a configuration in which a smoothing capacitor (bypass capacitor) is provided on the wiring board 30 is also employed. obtain. According to this configuration, noise and ripples of the common potential Vcom and the power supply potential (higher power supply potential Vcc and lower power supply potential Gnd) are further reduced.

(3) In the above-described embodiment, the configuration in which the power supply potential and the common potential Vcom are generated by one power supply circuit 33 is illustrated. However, the circuit that generates the power supply potential and the circuit that generates the common potential Vcom are separate circuits. Also, the configuration described above can be adopted. In other words, the “power supply circuit” in the present invention may be a single circuit or a plurality of circuits in appearance. In the above-described embodiment, the configuration in which the common potential Vcom is a substantially constant potential is illustrated. However, the common potential Vcom may be a potential whose level varies with time. For example, in the configuration in which the potential applied to the pixel electrode 12 is inverted with respect to the reference potential every predetermined time (for example, a horizontal scanning period or a vertical scanning period) according to the gradation of the display image, this polarity A configuration in which the level of the common potential Vcom is changed in synchronization with the inversion can also be adopted.

(4) In the above embodiment, a liquid crystal device using liquid crystal as an electro-optical material has been illustrated, but the present invention can also be applied to an electro-optical device using other electro-optical material. For example, a display device using an organic light emitting diode (OLED) element such as an organic EL (ElectroLuminescent) or a light emitting polymer as an electrooptic material, a plasma display panel using a high pressure gas such as helium or neon as an electrooptic material, or a phosphor The present invention can be applied to various electro-optical devices such as a field emission display using as an electro-optical material.

<E: Electronic equipment>
Next, an electronic apparatus having the electro-optical device according to the invention will be described.

  FIG. 9 is a plan view showing a configuration of a projector using the electro-optical device according to the present invention (here, the liquid crystal device 100 according to the above embodiment) as a light valve. As shown in the figure, the projector 2100 has a lamp unit 2102 made of a white light source such as a halogen lamp. The projection light emitted from the lamp unit 2102 is separated into light having wavelengths corresponding to the three primary colors of red (R), green (G), and blue (B) by three mirrors 2104 and two dichroic mirrors 2108. , Are guided to the light valves 100R, 100G and 100B corresponding to the respective colors. Since light corresponding to blue has a longer optical path than light corresponding to other colors, light is guided to the light valve 100B via the relay lens system 2121 in order to prevent loss thereof. The relay lens system 2121 includes an entrance lens 2122, a relay lens 2123, and an exit lens 2124.

  Here, the light valves 100R, 100G, and 100B have the same configuration as that of the liquid crystal device 100 according to the above-described embodiment, and the light valves 100R, 100G, and 100B respectively have image signals corresponding to the red, green, and blue colors supplied from the image signal processing circuit 2. Is driven. The light modulated by these light valves 100R, 100G, and 100B enters the dichroic prism 2112 from different directions. In the dichroic prism 2112, red and blue light is refracted by 90 degrees, while green light goes straight. Under this configuration, a color image obtained by combining the images of the respective colors is projected onto the screen 2120 by the projection lens 2114.

  In addition to the projector shown in FIG. 9, the electronic apparatus in which the electro-optical device according to the present invention can be used includes a portable personal computer, a liquid crystal television, a viewfinder type (or monitor direct view type) video recorder. , Car navigation devices, pagers, electronic notebooks, calculators, word processors, workstations, videophones, POS terminals, devices equipped with touch panels, and the like.

It is a top view which shows the structure of the liquid crystal device which concerns on 1st Embodiment of this invention. It is sectional drawing seen from the II-II line | wire in FIG. 4 is an equivalent circuit diagram illustrating a relationship between a common wiring and a power supply line and a smoothing capacitor in the liquid crystal device. FIG. It is a top view which expands and shows FPC among the liquid crystal devices which concern on 2nd Embodiment of this invention. It is sectional drawing seen from the VV line in FIG. It is sectional drawing which shows the structure of FPC among the liquid crystal devices which concern on a modification. It is sectional drawing seen from the VII-VII line in FIG. It is an equivalent circuit diagram which shows the relationship between a common wiring and a power supply line among the liquid crystal devices which concern on 3rd Embodiment of this invention. It is sectional drawing which shows the structure of the projector which is an example of the electronic device which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Liquid crystal device, 10 ... Liquid crystal panel, 11 ... Element board | substrate, 12 ... Pixel electrode, 141 ... Scanning line drive circuit, 143 ... Data line drive circuit, 15, 23, 31 ... Wiring, 17 ...... Counter substrate, 20 ... FPC (flexible wiring board), 21 ... base material, 21a ... end part on the liquid crystal panel side, 21b ... end part on the wiring board side, 231 ... common wiring (first wiring) Wiring), 232... Ground line (second wiring), 28a, 28b... Wiring portion, 29... Electrode portion, 261 .. Insulating layer, 25 .. Smoothing capacitor (electrostatic capacity), 251. Chip capacitor, 252... Capacitor, 27... Discharge resistor, 30... Wiring board, 311 .. wiring to which common potential is applied, 312... Wiring to which lower power supply potential is applied, 33. .

Claims (9)

An electro-optic panel comprising a plurality of pixel electrodes arranged in a planar shape and a counter electrode facing the plurality of pixel electrodes with an electro-optic material interposed therebetween;
A wiring board provided with a power supply circuit for generating a power supply potential and a common potential applied to the counter electrode;
A flexible base material fixed to the electro-optical panel and the wiring board, and a first wiring for supplying the power supply potential to the electro-optical panel and the common potential to the electro-optical panel An electro-optical device comprising: a flexible wiring board having a capacitance between the second wiring for supplying to the first wiring. The electro-optical device according to claim 1, wherein the capacitance is a chip capacitor mounted on a plate surface of the base material. The capacitance is provided on the electro-optical panel side when viewed from a central portion of an end portion fixed to the wiring board and an end portion fixed to the electro-optical panel in the base material. The electro-optical device according to 1. The electro-optical device according to claim 1, wherein the capacitance is a capacitance having the first wiring and the second wiring as electrodes. 5. The electro-optic according to claim 4, wherein each of the first wiring and the second wiring includes electrode portions that overlap with each other when viewed from a direction perpendicular to a plate surface of the base material to configure the capacitance. apparatus. Each of the first wiring and the second wiring has a wiring portion formed at an end portion fixed to the wiring substrate and an end portion fixed to the electro-optical panel of the base material. The electro-optical device according to claim 5, wherein the electrode portion is wider than the wiring portion. The electro-optical device according to claim 1, further comprising: a resistor having one end electrically connected to the counter electrode and the other end electrically connected to the second wiring.   An electronic apparatus comprising the electro-optical device according to claim 1 as a display device. An electro-optical panel having a counter electrode opposed to a plurality of pixel electrodes arranged at intersections of a plurality of scanning lines and a plurality of data lines with an electro-optical material interposed therebetween, and a power source potential and a common applied to the counter electrode In a flexible wiring board interposed between a wiring board provided with a power supply circuit for generating a potential,
A flexible base material fixed to the electro-optical panel and the wiring board;
A first wiring for supplying the common potential to the electro-optical panel;
A second wiring for supplying the power supply potential to the electro-optical panel;
A flexible wiring board comprising: a capacitance provided between the first wiring and the second wiring.

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