JP2005043901A - Liquid crystal device and electronic equipment using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a high image quality liquid crystal device being hardly influenced by electrostatic charges in a liquid crystal device constructed so that an electric field substantially parallel to a substrate surface can be applied. <P>SOLUTION: In the liquid crystal device constructed so that the electric field 113 substantially parallel to the substrate surface can be applied, the liquid crystal device is constructed by forming a conductive film on a color filter forming substrate 104 opposite to a substrate 109 with an electric field controlling means wherein a potential of the conductive film is set to any one of a ground potential, a common electrode potential, a central potential of image signals, a non-selecting potential of scanning signals, a logic potential of an external driving means or a floating state. Thereby the liquid crystal device which is hardly invaded by static electricity and which has high image quality is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an active matrix liquid crystal device in which an active element that switches to each pixel (also referred to as a picture element) is arranged, and the voltage application to the liquid crystal of the pixel is controlled by this active element. The present invention relates to a liquid crystal device of a type in which a lateral electric field (layer direction) is applied.

  The present invention also relates to an electronic apparatus using the liquid crystal device.

  Currently, most liquid crystal devices used in notebook personal computers and liquid crystal televisions are in the TN (Twisted Nematic) mode. However, this TN mode looks different depending on the viewing direction. As a method for improving this viewing angle characteristic, an IPS (In Plane Switching) mode using a lateral electric field is proposed in Japanese Patent Laid-Open Nos. 56-091277 and 06-160878.

  Hereinafter, the operating principle of the IPS mode will be briefly described with reference to the drawings. 4 (a) and 4 (b) are cross-sectional views showing the operation of the liquid crystal in the liquid crystal panel using the IPS mode, FIG. 4 (a) is a cell cross-sectional view when no voltage is applied, and FIG. 4 (b) is a cross-sectional view. It is cell sectional drawing at the time of the voltage application exceeding a liquid crystal and a threshold value. 4 (c) is a plan view of FIG. 4 (a), and FIG. 4 (d) is a plan view of FIG. 4 (b). In FIG. 4, 401 and 409 are a pair of polarizing plates, 402 and 408 are a pair of substrates sandwiching liquid crystal, 403 is a color filter, 404 and 406 are alignment films, and 405 is a liquid crystal molecule schematically shown. Reference numeral 410 denotes a pixel electrode, reference numeral 411 denotes a common electrode serving as a counter electrode of the pixel electrode, reference numeral 412 denotes an image signal line (source line), and reference numeral 407 denotes an insulating layer that separates the pixel electrode 410 and the common electrode 411 from each other. The IPS mode liquid crystal device has a structure in which the pixel electrode and the common electrode for applying an electric field to the liquid crystal are juxtaposed on one substrate as described above. Reference numeral 413 denotes an absorption axis of the lower polarizing plate, and 414 denotes an absorption axis of the upper polarizing plate.

  FIG. 4 is a schematic diagram in which an active element such as a TFT (Thin Film Transistor) is omitted. This schematic diagram is a cross-sectional view of a portion X-X ′ in FIG. 5 and an enlarged view of a portion surrounded by a dotted line. FIG. 5 is a configuration diagram of one pixel. In this configuration diagram, two common electrodes 502 and one pixel electrode 501 exist in the longitudinal direction in one pixel. This is merely a schematic drawing, and several common electrodes 502 and several pixel electrodes 501 may exist in one pixel. In the figure, reference numeral 503 denotes a running signal line (gate line), 504 denotes an image signal line (source line), and 505 denotes a thin film transistor (TFT).

  4A and 4C when no voltage is applied, a color filter 403 is formed on the upper substrate 402 of the pair of substrates 402 and 408, and a linear common electrode 411 is formed on the inner side of the lower substrate 408. The pixel electrode 410 is formed, and the alignment films 404 and 406 for arranging the liquid crystal molecules 405 are formed. Liquid crystal is sandwiched between the pair of substrates 402 and 408, and the liquid crystal molecules 405 are at a predetermined angle (0 to 45 degrees) with the longitudinal direction of the linear electrodes (common electrode 411, pixel electrode 410) when no voltage is applied. And have a uniform orientation. In FIG. 4, this angle is 30 degrees. Further, polarizing plates 401 and 409 are arranged on both sides of the liquid crystal cell. The upper polarizing plate 401 has the absorption axis 414 parallel to the alignment direction of the liquid crystal, and the lower polarizing plate 409 is arranged vertically. This state is a black display state. A material having positive dielectric anisotropy was used as the liquid crystal material.

  Next, when an electric field 415 is applied, as shown in FIGS. 4B and 4D, the liquid crystal molecules 405 attempt to align their long axes in the direction of the electric field 415, so that the liquid crystal molecules 405 correspond to the strength of the applied electric field. Thus, it has an angle with respect to the absorption axis of the polarizing plate. The birefringence of the liquid crystal can be controlled by controlling the orientation angle of the liquid crystal cell in accordance with the strength of the applied electric field. Thereby, the light transmittance which permeate | transmits a pair of polarizing plate can be controlled, and, thereby, a gradation display can be performed.

  However, the pixel electrode 410 and the common electrode 411 for applying an electric field to the liquid crystal are formed only on one substrate, and no electrode is formed on the other substrate. Problems arise. When charged with static electricity, the orientation of the liquid crystal is disturbed and high-quality display cannot be performed. Also, once charged by static electricity, the other substrate does not have an electrode, so this static electricity cannot be removed easily.

  Accordingly, an object of the present invention is to realize a high-quality liquid crystal device that is not easily affected by static electricity and that is not easily charged with static electricity.

In the present invention, a liquid crystal is sandwiched between a pair of substrates, and a scanning signal line and an image signal line arranged in a matrix on one of the substrates, and arranged according to the intersection of the scanning signal line and the image signal line Active element, a pixel electrode connected to the active element, and a common electrode are arranged so that an electric field substantially parallel to the substrate surface can be applied to the liquid crystal between the pixel electrode and the common electrode. In the liquid crystal device, an electrode for driving the liquid crystal is not formed on the opposite surface side of the other substrate facing the one substrate, and a metal light shielding film is formed on the opposite surface side of the other substrate. The metal light-shielding film has the same potential as the common electrode, the center potential of the image signal supplied to the image signal line, and the non-scan signal applied to the scan signal line. Selection potential, the liquid crystal Wherein the one of a constant potential of the logic potential of the driving means for driving the location is applied.
The present invention is characterized in that the metal light-shielding film is electrically connected to the common electrode at a peripheral portion of a pixel area where the liquid crystal is driven.

  According to the above configuration, the other substrate is not charged by external static electricity or the like, and high-quality display is possible. If there is no metal light-shielding film having a constant potential on the other substrate, the substrate is charged with static electricity, and a large potential difference of tens of thousands V or more between the pixel electrode and the common electrode on the one substrate. The liquid crystal responds to this potential difference. Therefore, in order to obtain a high-quality display, it is important to provide a metal light-shielding film having a constant potential on the other substrate that does not have an electrode for driving the liquid crystal. An alloy of chromium (Cr) or nickel (Ni) copper (Cu) is suitable for the metal light shielding film.

  Further, according to the present invention, liquid crystal is sandwiched between a pair of substrates, and scanning signal lines and image signal lines arranged in a matrix on one of the substrates, and according to the intersection of the scanning signal lines and the image signal lines. The active element, the pixel electrode connected to the active element, and the common electrode are arranged, and an electric field substantially parallel to the substrate surface can be applied to the liquid crystal between the pixel electrode and the common electrode. In the liquid crystal device, an electrode for driving the liquid crystal is not formed on the opposite surface side of the other substrate facing the one substrate, and the same electrode as the common electrode is formed on the other substrate. A constant potential of any one of a potential, a center potential of an image signal supplied to the image signal line, a non-selection potential of a scanning signal applied to the scanning signal line, and a logic potential of driving means for driving the liquid crystal device is applied. Conductive film Made is characterized in that is.

  According to the above configuration, the other substrate is not charged by external static electricity or the like, and high-quality display is possible. If there is no conductive film having a constant potential on the other substrate, the substrate is charged with static electricity, and a large potential difference of tens of thousands V or more is generated between the pixel electrode and the common electrode on the one substrate. This causes the liquid crystal to respond to this potential difference. Therefore, in order to obtain a high-quality display, it is important to provide a conductive film having a constant potential on the other substrate that does not have an electrode for driving the liquid crystal. Since the conductive film is formed in a portion other than the display portion, it is not necessary to be transparent, and various metal materials can be used.

  Note that the pixel area is a region 303 indicated by a dotted line in the liquid crystal cell as shown in FIG. 3 and is a portion where characters, pictures, and the like can be actually displayed. The peripheral area of the pixel area is an area 304 that cannot be displayed around the pixel area.

  Further, the present invention is characterized in that the constant potential is any one of a potential of a common electrode, a center potential of an image signal amplitude, a non-selection potential of a scanning signal, and a logic potential of an external driving unit.

  According to the above configuration, it is not necessary to create a new potential, and a potential that already exists in the liquid crystal device can be used. This realizes a high-quality liquid crystal device that is resistant to static electricity without increasing costs.

  Note that the common electrode potential, the center potential of the image signal amplitude, and the non-selection potential of the scanning signal are potentials 606, 605, and 607 in FIG. 6 of a driving waveform diagram of a liquid crystal panel using TFT elements. The drive waveform of FIG. 6 is simply simplified using the equivalent circuit of the TFT element of FIG. Reference numerals 602 and 603 denote signals of the scanning signal line 703 and the image signal line 704, which are applied to the gate and source of the TFT element 705, respectively. An NTSC image signal is composed of two interlaced fields, and the first field 610 and the second field 611 are combined into one frame 612 to form one picture. In the selection period 608, when a selection pulse is applied to the scanning signal line 703 and the TFT element 705 is turned on, the potential 604 of the pixel electrode 701 becomes substantially equal to the potential 603 of the image signal line 704. In the non-selection period 609, the TFT element 705 is turned off and the signal written in the liquid crystal capacitor 706 is held. In this way, all the scanning signal lines 703 are sequentially selected one by one, and the data of all the pixels are rewritten once per field.

Further, the invention is characterized in that a backlight light source is disposed on the pair of substrates.
Further, the invention is characterized in that any one of the above liquid crystal devices is used as a display device for various electronic devices.

  Hereinafter, the present invention will be described with reference to the drawings.

(Example 1)
FIG. 1 is a diagram showing a main part of the configuration of a liquid crystal device according to the present invention. (A) is a top view of the color filter formation board | substrate 104, (b) is sectional drawing of a liquid crystal device. First, the configuration will be described. It has a structure in which two 1.1 mm thick transparent glass substrates 104 and 109 are overlapped, and a liquid crystal layer 106 is sandwiched between them. On the upper glass substrate 104, a chromium (Cr) light-shielding film 101, a red green blue (RGB) color filter 102, and an alignment film 105 are sequentially formed on the inner side, and a polarizing plate 103 is disposed on the outer side. In the lower glass substrate 109, a common electrode 111, an insulating layer 108, a pixel electrode 112, and an alignment film 107 are formed on the inner side, and a polarizing plate 110 is disposed on the outer side.

  Each pixel has a scanning signal line (gate line) 503 and an image signal line (source line) 504 arranged in a matrix as shown in FIG. 5, which is a plan view of the lower glass substrate. Near the intersection, a thin film transistor (TFT element) 505 having a gate electrode connected to the scanning signal line 503, a source electrode connected to the image signal line 504, and a drain electrode connected to the pixel electrode 501 (112) is formed.

  The Cr light-shielding film 101 in FIG. 1 is formed so as to shield the TFT element and image signal line / scanning signal line regions formed on the lower substrate.

  In FIG. 1, the common electrode 111 (502) and the pixel electrode 112 (501) are arranged in different layers with an insulating layer 108 interposed in one pixel. Reference numeral 113 in FIG. 1 indicates the direction of the electric field. A nematic liquid crystal having a refractive index anisotropy Δn = 0.070 and a positive dielectric anisotropy was used as the liquid crystal material 106 with a gap between the substrates of 4.5 μm. The distance between the linear common electrode 111 and the pixel electrode 112 was 10 μm, and the line width of both electrodes was 5 μm. The rubbing alignment treatment was performed so that the molecular major axis direction of the liquid crystal molecules had an angle of 30 degrees with the longitudinal direction of the linear electrodes (common electrode 111, pixel electrode 112). The polarizing plate 103 of the upper glass substrate 104 has an absorption axis parallel to the alignment direction of the liquid crystal, and the polarizing plate 110 of the lower glass substrate 109 is arranged vertically. This state is a black display state, and the angle at which the liquid crystal molecules are aligned changes according to the voltage applied from the external driving means, thereby changing the birefringence of the liquid crystal, so that gradation display is possible. . Note that a backlight light source is disposed on the lower substrate 109 side. The alignment method of the liquid crystal molecules and the setting of the absorption axis of the polarizing plate are the same as those described above with reference to FIG.

  Further, the Cr light-shielding film 101 in FIG. 1 is formed so as to shield the TFT element and image signal line / scanning signal line regions formed on the lower substrate.

  Next, a driving method of the active matrix liquid crystal device described above will be described with reference to FIGS. FIG. 7 is an equivalent circuit diagram of one pixel of the liquid crystal device, and FIG. 6 shows driving waveforms. In FIG. 7, reference numeral 703 denotes a scanning signal line corresponding to 503 in FIG. 5, reference numeral 704 denotes an image signal line corresponding to 504 in FIG. 5, and reference numeral 705 denotes a TFT element corresponding to 505 in FIG. The gate electrode of the TFT element 705 is connected to the scanning signal line 503, the source electrode is connected to the image signal line 704, and the drain electrode is connected to the pixel electrode 701 corresponding to 501 in FIG. 5 (112 in FIG. 1). Reference numeral 706 denotes a liquid crystal capacitor, and reference numeral 702 denotes a common electrode 502 corresponding to 502 in FIG. 5 (111 in FIG. 1). FIG. 6 shows driving in one pixel in time series, 607 is a scanning signal applied to the scanning signal line, 608 is a selection period in which the TFT element is turned on, and 609 is a liquid crystal in which the TFT element is turned off. This is a non-selection period in which the voltage applied to is held. In the selection period 608, the image signal 603 supplied to the image signal line is supplied to the pixel electrode through the TFT element. 612 indicates one frame period, 610 indicates a first field, and 611 indicates a second field. The voltage polarity of the image signal 603 is inverted between the first field and the second field with reference to the amplitude center potential 605 of the image signal. Reference numeral 604 denotes a potential of the pixel electrode, and a potential difference from the potential 606 of the common electrode is a voltage applied to the liquid crystal. In the selection period 608, the image signal 606 is applied to the pixel electrode through the TFT element, and the potential of the pixel electrode becomes the potential of the image signal 606. However, in the selection period 608, the charge accumulated in the capacitance parasitic between the drain electrode and the gate electrode of the TFT element flows into the pixel electrode side in the non-selection period 609, and the potential of the pixel electrode drops by ΔV. Therefore, the common electrode potential 606 is previously lowered by ΔV from the amplitude center potential 605 of the image signal. Thus, the polarity of the potential of the pixel electrode is substantially symmetrically reversed for each field with reference to the common electrode potential. Note that not only the liquid crystal capacitor 706 but also a storage capacitor can be provided in the pixel in parallel therewith. In this case, the storage capacitor is formed by overlapping the pixel electrode 501 and the common electrode 502 through the insulating film in the peripheral portion of the pixel in FIG.

  In the liquid crystal device having such a configuration, in this embodiment, as shown in FIG. 8, the Cr light-shielding film 807 (101 in FIG. 1) of the upper glass substrate 801 (104 in FIG. 1) is replaced with the lower glass substrate 802. A short circuit is made through a silver paste 805 at the peripheral portion 804 of the pixel area 803 of the liquid crystal cell so as to have the same potential as the common electrode 808 (111 in FIG. 1) formed on (109 in FIG. 1). FIG. 8A is a plan view of the liquid crystal panel, and FIG. 8B is an enlarged cross-sectional view in which the upper and lower substrates are short-circuited with silver paste. In FIG. 8, the Cr light shielding film shields between the TFT element and the pixel in the pixel area 803, but the pixel area 804 and the seal portion 806 are formed so as to surround the pixel area in the peripheral area 804 of the pixel area. It can be a parting out of the area.

  The Cr light-shielding film 807 (101) drawn outside the seal portion of the peripheral portion 804 is a seal portion (a seal for bonding a pair of substrates) of the liquid crystal panel with the silver paste 805, and is disposed so as to surround the pixel area 803. ) It is electrically short-circuited with the common electrode 808 (111) drawn from the pixel area at the four points outside 806. The reason why the light shielding film and the common electrode are connected at a plurality of locations is to make the voltage distribution of the light shielding film uniform in the entire pixel area.

  In FIG. 8B, the terminal portion drawn from the common electrode 808 mounts a liquid crystal driver or connects a circuit board and a liquid crystal panel via an anisotropic conductive film (ACF) 809. It is electrically connected to an electrode wiring 811 that is formed on the flexible substrate 810 and supplies a common electrode potential.

  Even when the liquid crystal device was subjected to an electrostatic withstand voltage test with static electricity of about 1 kV, good display could be performed without being charged at all. In addition, disorder of the liquid crystal alignment was not observed.

  In the configuration of the liquid crystal device as in Example 1 above, since the Cr that is the metal light-shielding film has a constant potential (common electrode potential), the color filter forming substrate is not charged by external static electricity or the like, High-quality display is possible. If there is no metal light shielding film with a constant potential on the color filter forming substrate, a large potential difference is generated between the pixel electrode and the common electrode on the upper substrate and the lower substrate due to static electricity, and the liquid crystal responds to this potential difference. End up. Therefore, in order to obtain a high-quality display, it is important to provide a metal light-shielding film having a constant potential on a color filter forming substrate that does not have an electrode for driving liquid crystal. In addition, since the common electrode potential used as the potential of the metal light-shielding film in this embodiment is a potential that already exists in the liquid crystal device, it does not need to be newly created. Therefore, it is possible to realize an electrostatic countermeasure for the liquid crystal device at a low cost.

(Example 2)
As shown in FIG. 9, in the configuration of the liquid crystal device similar to that in Example 1, the Cr light shielding film 903 (101 in FIG. 1) of the upper glass substrate was grounded. The configuration at this time will be described with reference to FIG. FIG. 9A is a plan view of the liquid crystal panel, and FIG. 9B is an enlarged cross-sectional view in which the upper and lower substrates are short-circuited with silver paste. The Cr light shielding film 903 inside the upper substrate 901 (104 in FIG. 1) is connected to the dummy electrode 904 inside the lower substrate 902 (109 in FIG. 1) via the silver paste 905 outside the seal portion 906. As shown in FIG. 9B, the dummy electrode 904 is mounted on a flexible substrate 909 on which a liquid crystal driver is mounted or a circuit board and a liquid crystal panel are connected via an anisotropic conductive film (ACF) 907. And is electrically connected to an electrode wiring 908 that supplies a ground potential. It was connected to the ground potential wiring on the circuit board for driving the liquid crystal. Even when the liquid crystal device was subjected to an electrostatic withstand voltage test with static electricity of about 1 kV, good display could be performed without being charged at all. In addition, disorder of the liquid crystal alignment was not observed.

  In the configuration of the liquid crystal device as in Example 2 above, since the metal light-shielding film Cr is at a constant potential (ground potential), the color filter forming substrate is prevented from being charged by external static electricity or the like. Display with high image quality is possible. When the potential of the Cr light shielding film is set to the ground potential, a slight potential difference is generated between the Cr light shielding film, the pixel electrode, and the common electrode. However, since a color filter layer, an alignment film, and the like are present on the Cr light-shielding film, a voltage drop occurs in this portion, and the potential difference actually applied to the liquid crystal becomes extremely small and can be ignored. Further, if there is no Cr light shielding film having a constant potential, when the color filter forming substrate is charged by static electricity, a potential difference of several tens of thousands of volts is applied to the liquid crystal, and the display device does not function. Therefore, in order to obtain a high-quality display, it is important to provide a metal light-shielding film having a constant potential (ground potential) on a color filter forming substrate that does not have an electrode for driving liquid crystal. Since the ground potential is already present in the liquid crystal device, it is not necessary to create a new one, and a high-quality liquid crystal device that is low-cost and resistant to static electricity can be realized.

(Example 3)
In the configuration of the liquid crystal device similar to that of Example 1, the Cr light-shielding film on the upper glass substrate was connected to the center potential (605 in FIG. 6) in the amplitude of the image signal. The connection method at this time is as shown in FIG. 9 and is realized by connecting the dummy electrode 904 to the potential wiring of the central potential of the image signal amplitude wired to the flexible substrate 909 mounted on the liquid crystal panel. Even when the liquid crystal device was subjected to an electrostatic withstand voltage test with static electricity of about 1 kV, good display could be performed without being charged at all. In addition, disorder of the liquid crystal alignment was not observed.

  In the configuration of the liquid crystal device as in the third embodiment, since the Cr serving as the metal light-shielding film has a constant potential (the center potential of the amplitude of the image signal), the color for the same reason as in the first and second embodiments. The filter-formed substrate is not charged by external static electricity or the like, and high-quality display is possible. Further, since the center potential of the image signal is already present in the liquid crystal device, it is not necessary to newly create it.

(Example 4)
In the configuration of the liquid crystal device similar to that of the first embodiment, the non-selection potential (the potential in the non-selection period 609 of the scanning signal 607 in FIG. 6) is applied to the scanning signal line (503 in FIG. 5) with the Cr light-shielding film of the upper glass substrate ) Connected. The connection method at this time is as shown in FIG. 9 and is realized by connecting the dummy electrode 904 to the potential wiring of the non-selection potential of the scanning signal line in the flexible substrate 909 mounted on the liquid crystal panel. Even when the liquid crystal device was subjected to an electrostatic withstand voltage test with static electricity of about 1 kV, good display could be performed without being charged at all. In addition, disorder of the liquid crystal alignment was not observed.

  In the configuration of the liquid crystal device as in the fourth embodiment, Cr as the metal light-shielding film has a constant potential (non-selection potential of the scanning signal). Therefore, for the same reason as in the first and second embodiments, color The filter-formed substrate is not charged by external static electricity or the like, and high-quality display is possible. Further, since the non-selection potential of the scanning signal is already present in the liquid crystal device, there is no need to newly create it.

(Example 5)
In the same configuration of the liquid crystal device as in Example 1, the Cr light-shielding film of the upper glass substrate was connected to the logic potential of the liquid crystal driving circuit. The connection method at this time was realized as shown in FIG. 9 by connecting the dummy electrode to the logic potential wiring in the flexible substrate 909 mounted on the liquid crystal panel. Even when the liquid crystal device was subjected to an electrostatic withstand voltage test with static electricity of about 1 kV, good display could be performed without being charged at all. In addition, disorder of the liquid crystal alignment was not observed.

  In the configuration of the liquid crystal device as in the fifth embodiment, since the Cr serving as the metal light-shielding film has a constant potential (logic potential), the color filter forming substrate is formed for the same reason as in the first and second embodiments. It is not charged by static electricity from the outside, and high-quality display is possible. Further, since the logic potential is already present in the liquid crystal device, it is not necessary to create a new one.

  In the above examples, the Cr metal film is used as the light shielding film, but it has been confirmed that the same effect can be obtained by using a metal film of Ta, Al, Au or the like other than Cr.

(Example 6)
FIG. 2A is a diagram showing a main part of the structure of the liquid crystal device according to the present invention.
First, the configuration will be described. It has a structure in which two 1.1 mm thick transparent glass substrates 203 and 210 are superposed, and a liquid crystal layer 207 is sandwiched between them. On the upper glass substrate 203, a red line blue (RGB) color filter 204, a resin light shielding film 205, and an alignment film 206 are sequentially formed on the inner side, and an ITO transparent conductive film 202 and a polarizing plate 201 are disposed on the outer side. . In the lower glass substrate 210, a common electrode 213, an insulating layer 209, a pixel electrode 212, and an alignment film 208 are formed on the inner side, and a polarizing plate 211 is disposed on the outer side.

  Each pixel has a scanning signal line (gate line) 503 and an image signal line (source line) 504 arranged in a matrix as shown in FIG. 5, which is a plan view of the lower glass substrate. Near the intersection, a thin film transistor (TFT element) 505 having a gate electrode connected to the scanning signal line 503, a source electrode connected to the image signal line 504, and a drain electrode connected to the pixel electrode 501 (212) is formed. The driving method is the same as in the first embodiment.

  In FIG. 2, the common electrode 213 and the pixel electrode 212 are arranged in different layers with an insulating layer 209 interposed in one pixel. In FIG. 2A, 214 indicates the direction of the electric field. In this embodiment, the gap, the distance between the electrodes, and the rubbing direction are slightly changed from those in the first embodiment. In other words, a nematic liquid crystal having a refractive index anisotropy Δn = 0.070 and a positive dielectric anisotropy was used as the liquid crystal material 207 with a gap between the substrates of 4.0 μm. The distance between the linear common electrode 213 and the pixel electrode 212 was 15 μm, and the line width of both electrodes was 5 μm. The rubbing alignment treatment was performed so that the liquid crystal molecules had an angle of 45 degrees with the longitudinal direction of the linear electrodes (common electrode 213, pixel electrode 212) when no voltage was applied. The polarizing plate 201 of the upper glass substrate 203 has an absorption axis parallel to the alignment direction of the liquid crystal, and the polarizing plate 211 of the lower glass substrate 210 is arranged vertically. This state is a black display state, and gradation display is possible by changing the orientation angle of the liquid crystal molecules in accordance with the applied voltage from the external driving means. Further, a backlight light source is disposed on the lower substrate 210 side.

  In FIG. 2A, the light shielding film 205 is disposed so as to shield the TFT element and image signal line / scanning signal line regions formed on the lower substrate.

  In the present embodiment, the potential of the ITO transparent conductive film 202 of the upper glass substrate 203 is connected to the ground potential on the liquid crystal driving circuit substrate by electric wiring from a region other than the pixel area.

  3 is a plan view of the liquid crystal panel, in which 302 is a lower substrate (210 in FIG. 2A), 301 is an upper substrate (203 in FIG. 2A), 303 is a pixel area, Reference numeral 304 denotes a peripheral portion thereof. In this embodiment, the transparent conductive film 202 is formed in the pixel area 303 and the peripheral portion 304 outside the upper substrate.

  As a method of connecting the ground potential to the transparent conductive film, a metal outer frame (not shown) or the like in which the transparent conductive film is exposed at the edge of the peripheral portion and a constant potential (ground potential) is applied. It is conceivable that a constant potential (ground potential) is applied to the transparent conductive film by bringing the transparent conductive film into contact with each other or through a connection member. If a constant potential (ground potential) is applied to the outer frame, the outer frame case itself also has the shielding function of the liquid crystal device, so that electrostatic protection is further ensured. However, the method of connecting the transparent conductive film to the ground potential is not limited to the above example, and various methods may be employed.

  Even when the liquid crystal device was subjected to an electrostatic withstand voltage test with static electricity of about 1 kV, good display could be performed without being charged at all.

  With the configuration of the liquid crystal device as in the sixth embodiment, the color filter forming substrate is not charged by external static electricity or the like, and high-quality display is possible. Further, since the ground potential is a potential that has conventionally existed in the liquid crystal device, it is not necessary to newly create it.

In this embodiment, the potential of the ITO transparent conductive film is set to the ground potential. However, as in Embodiments 2 to 5, the common electrode potential, the center potential of the image signal amplitude, the non-selection potential of the scanning signal, the logic of the external drive means A constant potential such as a potential may be used. Moreover, although ITO was used for the transparent conductive film, a transparent conductive film such as SnO ₂ may be used. The transparent conductive film need not be formed on the entire surface, and may be formed partially.

(Example 7)
In the liquid crystal device as shown in Example 6, a Cr metal film was formed on the peripheral portion 304 excluding the pixel area 303 instead of the ITO transparent conductive film on the upper substrate. The potential of the Cr metal film on the upper glass substrate was the ground potential. The Cr metal film in the peripheral portion 304 can also function as a parting plate that shields the periphery of the pixel area 303. Various potential connection methods are conceivable as in the sixth embodiment. Even when the liquid crystal device was subjected to an electrostatic withstand voltage test with static electricity of about 1 kV, good display could be performed without being charged at all. In addition, disorder of the liquid crystal alignment was not observed.

  With the configuration of the liquid crystal device as in the seventh embodiment, the color filter forming substrate is not easily charged by external static electricity or the like, and high-quality display is possible. Further, since the ground potential is already present in the liquid crystal device, it is not necessary to newly create it.

  In this embodiment, the potential of the Cr metal film is set to the ground potential. However, the influence of static electricity can also be a constant potential such as the common electrode potential, the center potential of the image signal, the non-selection potential of the scanning signal, and the logic potential of the external driving means. Good display can be performed without receiving.

  In this embodiment, the Cr metal film is formed in a region other than the pixel area on the outer surface of the liquid crystal panel substrate. However, similarly to the first embodiment, the Cr metal film is formed on the peripheral portion on the inner surface of the liquid crystal panel substrate. The same effect was confirmed even when formed in this region (however, in this embodiment, light shielding between the TFT elements and the pixels in the pixel area is performed by the resin light shielding film).

  In addition, it was confirmed that a metal film such as Ta, Al, or Au other than Cr has the same effect.

(Example 8)
The present embodiment is a configuration obtained by changing the configuration of FIG. 2A described in the sixth embodiment. In this embodiment, a gap between the substrates is set to 4.0 μm, and a nematic liquid crystal having a refractive index anisotropy Δn = 0.070 and a positive dielectric anisotropy is used as the liquid crystal material 207. The distance between the linear common electrode 213 and the pixel electrode 212 was 15 μm, and the line width of both electrodes was 10 μm. The rubbing alignment treatment was performed so that the liquid crystal molecules had an angle of 45 degrees with the longitudinal direction of the linear electrodes (common electrode 213, pixel electrode 212) when no voltage was applied. The polarizing plate 201 of the upper glass substrate 203 has an absorption axis parallel to the alignment direction of the liquid crystal, and the polarizing plate 211 of the lower glass substrate 210 is arranged vertically. This state is a black display state, and gradation display is possible by changing the orientation angle of the liquid crystal molecules in accordance with the applied voltage from the external driving means. A pack light source is disposed on the lower substrate 210 side.

  In the present embodiment, the potential of the ITO transparent conductive film 202 of the upper glass substrate 203 is in a floating state and is not electrically connected at all. Even when the liquid crystal device was subjected to an electrostatic withstand voltage test with static electricity of about 1 kV, good display could be performed without being charged at all.

  With the configuration of the liquid crystal device as in Example 8, the color filter forming substrate is difficult to be charged by external static electricity or the like, and high-quality display is possible. Further, since the potential of the transparent conductive film is in a floating state, it is not necessary to make an electrical connection, and it is possible to take measures against static electricity at low cost.

Example 9
FIG. 2B is a diagram showing a main part of the structure of the liquid crystal device according to the present invention.
First, the configuration will be described. Two transparent glass substrates 216 and 224 having a thickness of 1.1 mm are stacked, and a liquid crystal layer 221 is sandwiched therebetween. A red green blue (RGB) color filter 218, a resin light-shielding film 217, an ITO transparent conductive film 219, and an alignment film 220 are sequentially formed on the upper glass substrate 216, and a polarizing plate 215 is disposed on the outer side. In the lower glass substrate 224, a common electrode 227, an insulating layer 223, a pixel electrode 228, and an alignment film 222 are formed on the inner side, and a polarizing plate 225 is disposed on the outer side.

  Each pixel has a scanning signal line (gate line) 503 and an image signal line (source line) 504 arranged in a matrix as shown in FIG. 5, which is a plan view of the lower glass substrate. Near the intersection, a thin film transistor (TFT element) 505 having a gate electrode connected to the scanning signal line 503, a source electrode connected to the image signal line 504, and a drain electrode connected to the pixel electrode 501 (228) is formed. The driving method is the same as in the first embodiment.

  In one pixel, the common electrode 227 and the pixel electrode 228 are arranged in different layers with the insulating layer 223 interposed therebetween. 2B in FIG. 2B indicates the direction of the electric field. In this example, the gap, refractive index anisotropy, interelectrode distance, and rubbing direction between Example 1 and the substrate are slightly changed. That is, a nematic liquid crystal having a refractive index anisotropy Δn = 0.085 and a positive dielectric anisotropy was used as the liquid crystal material 221 with a gap between the substrates of 4.0 μm. The distance between the linear common electrode 227 and the pixel electrode 228 was 12 μm, and the line width of both electrodes was 5 μm. The rubbing alignment treatment was performed so that the liquid crystal molecules had an angle of 40 degrees with the longitudinal direction of the linear electrodes (common electrode 227, pixel electrode 228) when no voltage was applied. The polarizing plate 215 of the upper glass substrate 216 has an absorption axis parallel to the alignment direction of the liquid crystal, and the polarizing plate 225 of the lower glass substrate 224 is disposed vertically. This state is a black display state, and gradation display is possible by changing the orientation angle of the liquid crystal molecules in accordance with the applied voltage from the external driving means. A backlight light source is disposed on the lower substrate 224 side.

  In FIG. 2A, the light shielding film 205 is disposed so as to shield the TFT element and image signal line / scanning signal line regions formed on the lower substrate.

  In the present embodiment, the potential of the ITO transparent conductive film 219 of the upper glass substrate 216 is in a floating state and is not electrically connected at all. Even when the liquid crystal device was subjected to an electrostatic withstand voltage test with static electricity of about 1 kV, good display could be performed without being charged at all. In addition, disorder of the liquid crystal alignment was not observed.

  With the configuration of the liquid crystal device as in the ninth embodiment, the color filter forming substrate is not easily charged by external static electricity or the like, and high-quality display is possible. Further, since the potential of the transparent conductive film is in a floating state, it is not necessary to make an electrical connection, and it is possible to take measures against static electricity at low cost. Normally, when a transparent conductive film is formed on the surface in contact with the liquid crystal layer, that is, inside the liquid crystal cell, an electric field is generated between the pixel electrode and the common electrode and the image quality is deteriorated. However, the potential of the conductive film is in a floating state. , Image quality degradation can be suppressed as much as possible.

  In this embodiment, the ITO transparent conductive film is provided between the color filter layer and the alignment film on the upper substrate, but may be provided between the substrate and the color filter layer.

(Example 10)
In the present embodiment, the resin light-shielding films 205 and 217 in FIG. 2 in the eighth and ninth embodiments are changed to a metal light-shielding film such as Cr. At this time, the metal light-shielding film not only functions as a light-shielding film between the TFT element and the pixel, but is also connected to a constant potential at the periphery of the pixel area as shown in FIG. .

  Further, a floating ITO transparent conductive film as shown in Example 8 and Example 9 is formed on the outer surface or inner surface of the upper substrate as shown in FIG. Combine with ITO transparent conductive film.

  In this case, since the floating ITO transparent conductive film that absorbs static electricity and the metal light shielding film that shields the liquid crystal from static electricity exist, durability against static electricity is further increased.

  However, when a metal light-shielding film and a transparent conductive film are laminated on the inner side surface of the upper substrate, it is necessary to insulate both with a color filter or an insulating film.

  In this embodiment, the ITO transparent conductive film is provided between the color filter layer and the alignment film on the upper substrate, but may be provided between the substrate and the color filter layer.

(Example 11)
In the liquid crystal device as shown in Example 8 and Example 9, instead of the ITO transparent conductive film, a Cr metal film is formed on the outer side surface or the inner side surface of the upper glass substrate in the peripheral portion 304 of the pixel area 303 shown in FIG. Formed. The potential of the Cr metal film on the upper glass substrate was in a floating state.

  Even when the liquid crystal device was subjected to an electrostatic withstand voltage test with static electricity of about 1 kV, good display could be performed without being charged at all. In addition, disorder of the liquid crystal alignment was not observed.

  With the configuration of the liquid crystal device as in Example 11 above, the color filter forming substrate is not easily charged by external static electricity or the like, and high-quality display is possible. Further, since the Cr metal film is in a floating state, it is not necessary to make an electrical connection, and it is possible to take measures against static electricity at low cost. In addition, the light shielding film can have a function of parting out the pixel area.

  As described above, according to the present invention, it is possible to realize a high-quality liquid crystal device that is not easily affected by static electricity.

(Example 12)
In this embodiment, the upper polarizing plates 103, 201, and 215 are made conductive in the configuration shown in FIG. 1B, FIG. 2A, or FIG. Such a polarizing plate can be easily manufactured by mixing conductive particles in the film material of the polarizing plate, or by attaching a transparent conductive layer to the polarizing film and integrating them.

  The conductive polarizing plate is in a following state, or the conductive polarizing plate or the conductive layer of the polarizing plate is exposed. On the other hand, a constant potential (common electrode potential) is obtained in the same manner as in Example 6. , Any one of a ground potential, a non-selection potential of a scanning signal, and a logic potential of external drive manual throwing may be applied. When applying a constant potential, a connection method similar to that of the sixth embodiment can be employed.

  Even when the liquid crystal device was subjected to an electrostatic withstand voltage test with static electricity of about 1 kV, good display could be performed without being charged at all. In addition, disorder of the liquid crystal alignment was not observed.

  With the configuration of the liquid crystal device as in the above embodiments, the color filter forming substrate is not easily charged by external static electricity or the like, and high-quality display is possible.

  In addition, if the lower polarizing plate is also used as a conductive polarizing plate and the liquid crystal panel is sandwiched between the conductive polarizing plates from above and below, a better display against static electricity can be performed.

  Furthermore, this embodiment may be employed in a liquid crystal panel in combination with any of the other embodiments 1-11. By doing so, further countermeasures against static electricity can be taken.

(Example 13)
Examples of electronic devices configured using the liquid crystal devices of Examples 1 to 12 will be described below.

  An electronic apparatus using the liquid crystal device includes a display information output source 1000, a display information processing circuit 1002, a display driving circuit 1004, a display panel 1006 such as a liquid crystal panel, a clock generation circuit 1008, and a power supply circuit 1010 shown in FIG. Is done. The display information output source 1000 is configured to include a memory such as a ROM and a RAM, a tuning circuit that tunes and outputs a television signal, and outputs display information such as a video signal based on the clock from the clock generation circuit 1008. To do. The display information processing circuit 1002 processes display information based on the clock from the clock generation circuit 1008 and outputs it. The display information processing circuit 1002 can include, for example, an amplification / polarity inversion circuit, a phase expansion circuit, a rotation circuit, a gamma correction circuit, or a clamp circuit. The display driving circuit 1004 includes a scanning side driving circuit and a data side driving circuit, and drives the liquid crystal panel 1006 to display. The power supply circuit 1010 supplies power to each of the circuits described above.

  As an electronic apparatus having such a configuration, a personal computer (PC) and engineering workstation (EWS) corresponding to multimedia shown in FIG. 11, a pager shown in FIG. 12, a mobile phone, a word processor, a television, a viewfinder type Or, a monitor direct-view video tape recorder, an electronic notebook, an electronic desk calculator, a car navigation device, a POS terminal, a device equipped with a touch panel, and the like can be given.

  A personal computer 1200 shown in FIG. 11 includes a main body 1204 provided with a keyboard 1202 and a liquid crystal display screen 1206.

  A pager 1300 shown in FIG. 12 includes a glass substrate 1304, a light guide 1306 having a backlight 1306a, a circuit board 1308, first and second shield plates 1310 and 1312, and two elastic conductors in a metal frame 1302. 1314 and 1316, and a film carrier tape (flexible substrate) 1318. Two elastic conductors 1314 and 1316 and a film carrier tape 1318 connect the glass substrate 1304 and the circuit substrate 1308.

  Here, the substrate 1304 is obtained by enclosing a liquid crystal between two transparent glass substrates 1304a and 1304b, and thereby at least a liquid crystal panel device is configured. A driving circuit 1004 shown in FIG. 10 or a display information processing circuit 1002 can be formed on one transparent substrate. A circuit that is not mounted on the substrate 1304 is an external circuit of the substrate, and can be mounted on the circuit substrate 1308 in the case of FIG.

  FIG. 12 shows the structure of the pager, and therefore a circuit board 1308 is required in addition to the glass substrate 1304. In the case where a liquid crystal display device is used as a component for electronic equipment, the display is made on a transparent substrate. When a drive circuit or the like is mounted, the minimum unit of the liquid crystal display device is a substrate 1304. Or what fixed the board | substrate 1304 to the metal frame 1302 as a housing | casing can also be used as a liquid crystal device which is one component for electronic devices. Further, in the case of the backlight type, a liquid crystal display device can be configured by incorporating a substrate 1304 and a light guide 1306 provided with a backlight 1306a in a metal frame 1302. Instead, as shown in FIG. 13, an IC chip 1324 is mounted on a polyimide tape (flexible substrate) 1322 in which a metal conductive film is formed on one of two transparent substrates 1304a and 1304b constituting the substrate 1304. A TCP (Tape Carrier Package) 1320 can be connected and used as a liquid crystal device that is a component for electronic equipment.

  In addition, this invention is not limited to the said Example, A various deformation | transformation implementation is possible within the range of the summary of this invention.

  In relation to Embodiments 1 to 12, the liquid crystal device is supplied with various constant potentials from the power supply circuit 1010 of FIG. 10, and the constant potential applied to the light shielding film and the transparent conductive film in the embodiment is as follows. , From the power supply circuit or from the driving circuit 1004. Further, as described in the embodiment, the light shielding film is connected to the common electrode or the dummy electrode, but the common electrode or the dummy electrode is fixed by the tape 1318 of FIG. 12 or the tape 1322 of FIG. Connected to potential wiring.

  When applying a constant potential to the transparent conductive film or metal film formed on the outer surface of the upper glass substrate, the power circuit shown in FIG. 10 is added to the frame 1302 shown in FIG. A constant potential may be applied from 1010, and the constant potential may be supplied to the transparent conductive film or metal film of the upper substrate 1304a through this.

In the above examples, the Cr metal film was used, but it was confirmed that the same effect was obtained with a metal film of an alloy of Cr and Ni or Cu in addition to Ta, Al, and Au other than Cr. In the above embodiments, ITO is used for the transparent conductive film, but a transparent conductive film such as SnO ₂ may be used. Furthermore, the transparent conductive film does not need to be formed on the entire surface, and may be formed partially.

  As described above, since the liquid crystal device according to the present invention is an active matrix type liquid crystal device having a wide viewing angle, it can be used as a display device for personal computers, workstations, etc., and as a monitor for multimedia terminal devices, televisions, etc. Can do. In particular, it is suitable for protecting a liquid crystal device from static electricity in an environment where static electricity is likely to be generated, for example, in an office environment where there are many electronic devices.

It is a block diagram of the liquid crystal device of this invention. It is a cross-sectional block diagram of the liquid crystal device of this invention. It is a top view of the liquid crystal cell of this invention. It is explanatory drawing of IPS mode. It is a block diagram of 1 pixel in the liquid crystal device of this invention. It is a figure which shows the drive waveform of a TFT type liquid crystal device. It is an equivalent circuit diagram of one pixel in the liquid crystal device of the present invention. It is the top view and enlarged sectional view of the liquid crystal cell which short-circuited the electrode of the inner surface of an upper and lower board | substrate with the silver paste in this invention. It is sectional drawing of the liquid crystal cell which short-circuited the electrode of the inner surface of an upper and lower board | substrate with the silver paste in this invention. It is a drive circuit diagram of the liquid crystal device of the present invention. It is a figure which shows the example of the personal computer using the liquid crystal device of this invention. It is a figure which shows the structural example of the pager using the liquid crystal device of this invention. It is a figure which shows the example of mounting structure of the liquid crystal device of this invention.

Claims (5)

A liquid crystal is sandwiched between a pair of substrates, and on one of the substrates, scanning signal lines and image signal lines arranged in a matrix, and active elements arranged in accordance with intersections of the scanning signal lines and the image signal lines In the liquid crystal device, the pixel electrode and the common electrode connected to the active element are arranged, and an electric field substantially parallel to the substrate surface can be applied to the liquid crystal between the pixel electrode and the common electrode.
An electrode for driving the liquid crystal is not formed on the opposite surface side of the other substrate facing the one substrate, and a color filter having a metal light-shielding film on the opposite surface side of the other substrate The metal light-shielding film has the same potential as the common electrode, the center potential of the image signal supplied to the image signal line, the non-selection potential of the scanning signal applied to the scanning signal line, A liquid crystal device, wherein a constant potential of any one of logic potentials of driving means for driving the liquid crystal device is applied.   The liquid crystal device according to claim 1, wherein the metal light shielding film is electrically connected to the common electrode at a peripheral portion of a pixel area where the liquid crystal is driven. A liquid crystal is sandwiched between a pair of substrates, and on one of the substrates, scanning signal lines and image signal lines arranged in a matrix, and active elements arranged in accordance with intersections of the scanning signal lines and the image signal lines In the liquid crystal device, the pixel electrode and the common electrode connected to the active element are arranged, and an electric field substantially parallel to the substrate surface can be applied to the liquid crystal between the pixel electrode and the common electrode.
An electrode for driving the liquid crystal is not formed on the opposite surface side of the other substrate facing the one substrate, and the other substrate has the same potential as the common electrode and the image signal line. A conductive film is formed to which a constant potential of any one of the center potential of the image signal supplied to the scanning signal, the non-selection potential of the scanning signal applied to the scanning signal line, and the logic potential of the driving means for driving the liquid crystal device is applied. A liquid crystal device characterized by being made.   4. The liquid crystal device according to claim 1, wherein a backlight light source is disposed on the one substrate side. 5. An electronic apparatus using the liquid crystal device according to claim 1.

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