JP5369554B2 - Liquid crystal device and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To change a pretilt angle of liquid crystal molecules in response to, for example, a use of a liquid crystal device or a user's request. <P>SOLUTION: When contrast of an image is enhanced, that is, when a liquid crystal device (1) is used in a high contrast specification, an initial application voltage (Va) is set so that major axes of liquid crystal molecules (50b) cross an alignment layer (16) at an angle of nearly perpendicular (that is, a pretilt angle (&theta;) is about 98&deg; near 90&deg;) in a state where the initial application voltage (Va) is applied to liquid crystal molecules (50b). When importance is given to response of liquid crystal molecules (50b) to a driving voltage, an initial application voltage (Vb) is set so that major axes of liquid crystal molecules (50b) and the alignment layer (16) are approximately parallel with each other (that is, the pretilt angle (&theta;) is 1 to 2&deg; near 0&deg;) in a state where the initial application voltage (Vb) is applied to liquid crystal molecules (50b). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a technical field of an electronic device such as a liquid crystal device and a projector including such a liquid crystal device as a light valve.

  In this type of liquid crystal device, a technique for improving the display quality of an image by setting a pretilt angle of liquid crystal molecules to a predetermined angle by an alignment film such as a vertical alignment polyimide film has been proposed (for example, patents). Reference 1).

Japanese Patent Application Laid-Open No. 6-27377

  In this type of liquid crystal device, when a moving image is displayed, the responsiveness of the liquid crystal molecules to the driving voltage is required as compared with the case where a still image is displayed. More specifically, it is required that the alignment state of the liquid crystal molecules can be immediately changed with respect to the driving voltage applied to the liquid crystal molecules. Further, in this type of liquid crystal device, it is more preferable that the contrast of the displayed image is higher from the viewpoint of improving the display quality of the image.

  The responsiveness of the liquid crystal molecules to the driving voltage and the contrast of the displayed image are usually in a trade-off relationship, and the responsiveness is enhanced when importance is attached to increasing the responsiveness of the liquid crystal molecules to the driving voltage. In the case where the alignment film is formed as described above and importance is attached to increasing the contrast of the image, the alignment film is formed so as to increase the contrast, and the pretilt angle of the liquid crystal molecules is set to a predetermined angle. More specifically, for example, when the alignment mode of the liquid crystal molecules is a vertical alignment mode, the major axis of the liquid crystal molecules and the alignment film are parallel to each other in a state where the driving voltage is not applied to the liquid crystal molecules. Thus, a predetermined rubbing process is performed on the alignment film. On the other hand, when the alignment mode of the liquid crystal molecules is the vertical alignment mode, when increasing the contrast of the image, the major axis of the liquid crystal molecules is nearly perpendicular to the alignment film in a state where the driving voltage is not applied to the liquid crystal molecules. The alignment film is subjected to a predetermined rubbing process so as to intersect at an angle. Therefore, when manufacturing a liquid crystal device, an orientation film is used depending on whether the display quality when displaying a still image is important or the display quality when displaying a moving image is important. For example, it is difficult to increase the production efficiency of the liquid crystal device by reducing the number of models of the liquid crystal device.

  In addition, a user who views an image displayed on the liquid crystal device may want to change the image display mode according to content provided to the user via the image. More specifically, for example, when importance is attached to the display quality of a moving image such as in a sports broadcast, the user wants to view an image in which display defects such as image blur are reduced rather than image contrast. .

  Accordingly, the present invention has been made in view of the above-described problems and the like. For example, a liquid crystal device capable of changing the pretilt angle of liquid crystal molecules in accordance with the use of the liquid crystal device and the user's request, and such a liquid crystal device. It is an object to provide an electronic device such as a projector including the above.

A liquid crystal device according to one embodiment of the present invention includes a liquid crystal element including liquid crystal molecules, a display portion capable of displaying an image in accordance with a voltage applied to the liquid crystal element, and the voltage applied to the liquid crystal element And driving the display unit so as to increase the contrast of the image, the drive circuit applies a first initial voltage to the liquid crystal element so as to increase the responsiveness of the liquid crystal element. When the display unit is operated, the driving circuit applies a second initial voltage to the liquid crystal element.
The liquid crystal device according to the first invention of the present invention has a liquid crystal element including liquid crystal molecules, and possible display unit displaying an image in accordance with a voltage applied to the liquid crystal element, response of the image In the first mode in which importance is attached to the liquid crystal element, a drive circuit that increases the initial applied voltage applied to the liquid crystal element is provided compared to the second mode in which importance is attached to the contrast of the image.

  According to the liquid crystal device of the present invention, the display unit is composed of, for example, a plurality of pixel units provided in a matrix on the substrate, and light emitted from the light source is modulated by liquid crystal molecules in each pixel unit. Is done. Such a voltage applied to the liquid crystal molecules is set according to an image signal supplied to each pixel unit constituting the display unit during operation of the liquid crystal device. The display unit may display an image in a display area including a plurality of pixel units, or may display an image on the screen by projecting display light emitted from the display unit onto the screen. .

In the liquid crystal device according to another aspect of the present invention, a pretilt angle of the liquid crystal molecules when the first initial voltage is applied is larger than a pretilt angle of the liquid crystal molecules when the second initial voltage is applied. It is characterized by that.
Liquid crystal device according to the second aspect of the present invention has a liquid crystal element including liquid crystal molecules, and possible display unit displaying an image in accordance with a voltage applied to the liquid crystal element, response of the image In the first mode in which importance is attached to the image, a driving circuit for applying an initial applied voltage is provided so that the pretilt angle of the liquid crystal molecules is larger than in the second mode in which the image contrast is emphasized.

  According to the liquid crystal device according to the present invention, the display unit may display an image on a display region including a plurality of pixel units or emit light from the display unit, similarly to the liquid crystal device according to the first aspect described above. An image may be displayed on the screen by projecting the displayed light onto the screen.

  As in the above-described aspect of the liquid crystal device according to the first aspect of the invention, the user specifies which of the moving image and the still image is to be emphasized when the liquid crystal device is used. The specifying unit specifies the initial applied voltage so that a moving image or a still image is displayed with display quality specified by the user.

  Therefore, according to the liquid crystal device of the present invention, when the liquid crystal device is used, the specific configuration of the liquid crystal device, more specifically, for example, the liquid crystal molecules specified by the conditions of the rubbing treatment of the alignment film Without being limited to the pretilt angle, the pretilt angle of the liquid crystal molecules can be set so that an image can be displayed with display quality requested by the user. Therefore, according to the liquid crystal device according to the present invention, it is possible to realize either reduction of blur of an image that may occur when a moving image is displayed, or improvement of contrast of an image when a still image is displayed. The pretilt angle of the liquid crystal molecules can be set.

  In the liquid crystal device according to each of the first and second inventions of the present invention, the specifying unit may set the initial applied voltage for each of a plurality of pixel units constituting the display unit.

  According to this aspect, the brightness or contrast of the image displayed by the liquid crystal device can be made uniform in the image.

  In order to solve the above problems, an electronic device according to the present invention includes the above-described liquid crystal device of the present invention.

  According to the electronic apparatus according to the present invention, since the liquid crystal device according to the present invention is included, a projection display device such as a projector, a mobile phone, an electronic notebook, a word processor, a view, and the like capable of high-quality display. Various electronic devices such as a finder type or a monitor direct-view type video tape recorder, a workstation, a videophone, a POS terminal, and a touch panel can be realized. In addition, as an electronic apparatus according to the present invention, for example, an electrophoretic device such as electronic paper can be realized.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

  Hereinafter, embodiments of a liquid crystal device and an electronic apparatus according to the present invention will be described with reference to the drawings.

<1: Liquid crystal device>
<1-1: Electrical Configuration of Liquid Crystal Device>
With reference to FIG. 1, an electrical configuration of a liquid crystal device 1 which is an embodiment of the liquid crystal device according to the first invention of the present invention will be described. FIG. 1 is a block diagram showing an electrical configuration of the liquid crystal device 1.

  The liquid crystal device 1 includes a display unit 200, a drive circuit unit 210, and a specific circuit unit 220 which is an example of the “specification unit” of the present invention, and various signals supplied from the external circuit unit 230 to the drive circuit unit 210. Accordingly, an image can be displayed on the display unit 200.

  The display unit 200 includes a plurality of pixel units provided in a matrix on a substrate. For example, the display unit 200 is mounted on the electronic device as a part of the electronic device such as a projector, and a light source such as a backlight. The light emitted from the light is modulated by liquid crystal molecules in each pixel portion. Such a voltage applied to the liquid crystal molecules, that is, a driving voltage for driving the liquid crystal molecules, depends on an image signal supplied to each pixel unit constituting the display unit 200 during the operation of the liquid crystal device 1. Is set. The liquid crystal device 1 may be used as a direct-view display that displays an image in the display area of the display unit 200 including a plurality of pixel units, or projects display light emitted from the display unit 200 onto a screen. Thus, it may be used as a light valve of a projector capable of displaying an image on the screen.

  The driving circuit 210 is a data line driving circuit that supplies an image signal to each of a plurality of pixel units constituting the display unit 200, and a scanning line that supplies the display unit 200 with a scanning signal for switching on / off of each pixel unit. It is a circuit part comprised including various circuits, such as a drive circuit. The operation of the specific circuit unit 220 will be described in detail together with the pretilt angle of the liquid crystal molecules.

<1-2: Specific Configuration of Liquid Crystal Device>
Next, a specific configuration of the liquid crystal device 1 according to the present embodiment will be described with reference to FIGS. 2 and 3. 2 is a plan view of the liquid crystal device 1 when the TFT array substrate 10 is viewed from the side of the counter substrate 20 together with each component formed thereon, and FIG. 3 is a cross-sectional view taken along the line III-III ′ of FIG. is there. The liquid crystal device 1 according to this embodiment is a liquid crystal device that is driven by a TFT active matrix system with a built-in driving circuit.

  2 and 3, in the liquid crystal device 1, the TFT array substrate 10 and the counter substrate 20 are arranged to face each other. A liquid crystal layer 50 is sealed between the TFT array substrate 10 and the counter substrate 20, and the TFT array substrate 10 and the counter substrate 20 are provided in a seal region located around the image display region 10a composed of a plurality of pixels. They are bonded to each other by the sealing material 52 formed.

  The sealing material 52 is made of, for example, an ultraviolet curable resin, a thermosetting resin, or the like for bonding the two substrates, and is applied on the TFT array substrate 10 in the manufacturing process and then cured by ultraviolet irradiation, heating, or the like. It is. In the sealing material 52, a gap material such as glass fiber or glass beads for dispersing the distance (inter-substrate gap) between the TFT array substrate 10 and the counter substrate 20 to a predetermined value is dispersed.

  The liquid crystal device 1 includes a data line driving circuit 101 and a scanning line driving circuit 104. These circuit units constitute a drive circuit unit 210, and the specific circuit unit 220 is formed on the TFT array substrate 10 together with these circuit units (see FIG. 1). In the peripheral region, the data line driving circuit 101 and the external circuit connection terminal 102 are provided along one side of the TFT array substrate 10 in a region located outside the sealing region where the sealing material 52 is disposed. The scanning line driving circuit 104 is provided along two sides adjacent to the one side. The scan line driver circuit 104 is electrically connected to each other by a plurality of wirings 105.

  Vertical conductive members 106 functioning as vertical conductive terminals between the TFT array substrate 10 and the counter substrate 20 are disposed at the four corners of the counter substrate 20. On the other hand, the TFT array substrate 10 is provided with vertical conduction terminals in a region facing these corner portions. Thus, electrical conduction can be established between the TFT array substrate 10 and the counter substrate 20.

  In FIG. 3, on the TFT array substrate 10, an alignment film 16 (see FIG. 5) is formed on the pixel electrode 9a after the pixel switching TFT, the scanning line, the data line, and the like are formed. ing. On the other hand, on the counter substrate 20, a counter electrode 21 and an alignment film 22 (see FIG. 5) are formed on the surface thereof. The liquid crystal layer 50 is made of, for example, a liquid crystal in which one or several types of nematic liquid crystals are mixed, and takes a predetermined alignment state between the pair of alignment films.

  During the operation, the liquid crystal device 1 modulates the incident light incident on the liquid crystal layer 50 from the TFT array substrate 20 side, which is the lower side in the figure, according to the alignment state of the liquid crystal layer 50, and Light is transmitted to the counter substrate 20 side.

  Next, the circuit configuration of the display unit 200 of the liquid crystal device 1 will be described with reference to FIG. FIG. 4 is a circuit diagram illustrating a circuit configuration of the display unit 200 of the liquid crystal device 1 according to the present embodiment.

  In FIG. 4, each of a plurality of pixel portions 72 formed in a matrix constituting the image display area 10a of the liquid crystal device 1, that is, the display portion 200 for displaying an image, includes a pixel electrode 9a, a TFT 30, and a liquid crystal element 50a. I have. The TFT 30 is electrically connected to the pixel electrode 9a, performs switching control of the pixel electrode 9a during operation of the liquid crystal device 1, and drives the liquid crystal element 50a according to the control. The data line 6a to which the image signal is supplied is electrically connected to the source of the TFT 30. The image signals S1, S2,..., Sn to be written to the data lines 6a may be supplied line-sequentially in this order, or may be supplied for each group to a plurality of adjacent data lines 6a. May be.

  The scanning line 3a is electrically connected to the gate of the TFT 30, and the liquid crystal device 1 sequentially applies the scanning signals G1, G2,..., Gm to the scanning line 3a in a pulse sequence in this order at a predetermined timing. It is comprised so that it may apply. The pixel electrode 9a is electrically connected to the drain of the TFT 30, and the image signal S1, S2,... Supplied from the data line 6a is turned on by turning on the TFT 30 as a switching element for a certain period. Sn is written at a predetermined timing. Image signals S1, S2,..., Sn written to the liquid crystal via the pixel electrode 9a are held for a certain period with the counter electrode 21 formed on the counter substrate 20.

  The liquid crystal constituting the liquid crystal layer 50 modulates light and enables gradation display by changing the orientation and order of the molecular assembly depending on the applied voltage level. In the normally white mode, the transmittance for incident light decreases according to the voltage applied in units of each pixel unit, and in the normally black mode, in accordance with the voltage applied in units of each pixel unit. As a result, the transmittance for incident light is increased, and light having a contrast corresponding to an image signal is emitted from the liquid crystal device 1 as a whole.

  The storage capacitor 70 is electrically connected in parallel with the liquid crystal element 50a formed between the pixel electrode 9a and the counter electrode 21 in order to prevent the image signal from leaking. A fixed potential is supplied to one of the pair of capacitor electrodes included in the storage capacitor 70 via the fixed potential line 300.

  Next, the pretilt angle of the liquid crystal molecules during the operation of the liquid crystal device 1 according to the present embodiment will be described with reference to FIGS. 1 and 5. FIG. 5 is a schematic diagram schematically showing the pretilt angle of the liquid crystal molecules in the liquid crystal device according to the present embodiment, and FIG. 5A shows the pretilt angle θ in the high contrast specification. b) shows the pretilt angle θ in the high-speed response specification.

  As shown in FIG. 1 and FIGS. 5A and 5B, the specific circuit unit 220 determines the initial applied voltages Va and Vb to be applied to the liquid crystal molecules 50 b based on the use of the liquid crystal device 1, respectively. And the potential of the pixel electrode 9a is set so that each of the initial applied voltages Va and Vb is applied to the liquid crystal molecules 50b. Here, each of the initial applied voltages Va and Vb is different from the driving voltage applied to the liquid crystal molecules 50b in order to drive the liquid crystal molecules 50b according to the image signal, and sets the pretilt angle θ of the liquid crystal molecules 50b. Therefore, the voltage applied to the liquid crystal molecules 50b is specified according to the application specified based on whether the display quality of the moving image displayed by the liquid crystal device 1 is important or the display quality of the still image is important. Is done.

  More specifically, for example, when the liquid crystal device 1 displays an image in the VA mode (vertical alignment mode), for example, as shown in FIG. When the apparatus 1 is used in a high contrast specification, the initial applied voltage Va is an angle in which the major axis of the liquid crystal molecules 50b is close to perpendicular to the alignment film 16 in a state where the initial applied voltage Va is applied to the liquid crystal molecules 50b. (That is, the pretilt angle θ is about 98 ° close to 90 °). On the other hand, as shown in FIG. 5B, when emphasizing increasing the responsiveness of the liquid crystal molecules 50b to the driving voltage, the initial applied voltage Vb is the liquid crystal in a state where the initial applied voltage Vb is applied to the liquid crystal molecules 50b. The major axis of the molecule 50b and the alignment film 16 are set so as to be nearly parallel to each other (that is, the pretilt angle θ is 1 ° to 2 ° close to 0 °).

  Therefore, according to the liquid crystal device 1, the alignment film 16 and the liquid crystal device 1 depending on the use of the liquid crystal device 1, such as whether the display quality when displaying a still image is important or the display quality when displaying a moving image is important. Since the manufacturing process conditions such as the rubbing process 22 are not specified, the number of types of liquid crystal devices can be reduced at the time of manufacturing the liquid crystal device, and the production efficiency of the liquid crystal device can be increased.

  In addition, in the liquid crystal device 1, the specifying circuit unit 220 can specify the initial applied voltages Va and Vb based on the display quality requested by the user viewing the image for the image displayed on the display unit 200. .

  More specifically, when the user uses the liquid crystal device 1, the user specifies which of the moving image and the still image is to be emphasized. The user specifies whether to place importance on reducing blurring of an image that occurs when a moving image is displayed or whether to emphasize the contrast of an image when a still image is displayed. The fact is input to the liquid crystal device 1 via the interface function. The specifying circuit unit 220 specifies the initial applied voltages Va and Vb so that a moving image or a still image is displayed with display quality specified by the user.

  Therefore, according to the liquid crystal device 1, when the liquid crystal device 1 is used, the specific configuration of the liquid crystal device 1, more specifically, for example, the liquid crystal specified by the rubbing process conditions of the alignment films 16 and 22. The pretilt angle θ of the liquid crystal molecules 50b can be set so that an image can be displayed with the display quality requested by the user without being limited to the pretilt angle θ of the molecules 50b.

  In addition, the specific circuit unit 220 can also set the initial applied voltages Va and Vb for each of the plurality of pixel units 72 constituting the display unit 220, and the luminance of the image displayed by the liquid crystal device 1 or It is possible to make the contrast uniform in the image.

  Further, the liquid crystal device 1 is not limited to the case where each of the initial applied voltages Va and Vb is set according to the use of the liquid crystal device 1. In other words, the liquid crystal device 1 may have only a function of specifying the initial applied voltages Va and Vb based on the display quality requested by the user viewing the image for the image displayed on the display unit 200. . Thus, the liquid crystal device having only the function of specifying the initial applied voltages Va and Vb only for the user's request is an example of the liquid crystal device according to the second invention of the present invention.

<2: Electronic equipment>
Next, an example of an electronic apparatus using the liquid crystal device described above will be described with reference to FIG. The electronic apparatus according to the present embodiment is a projector that uses the above-described liquid crystal device as a light valve. FIG. 6 is a plan view showing a configuration example of the projector according to the present embodiment.

  As shown in FIG. 6, a lamp unit 1102 including a white light source such as a halogen lamp is provided inside the projector 1100. The projection light emitted from the lamp unit 1102 is separated into three primary colors of RGB by four mirrors 1106 and two dichroic mirrors 1108 arranged in the light guide 1104, and serves as a light valve corresponding to each primary color. The light enters the liquid crystal panels 1110R, 1110B, and 1110G.

  The configurations of the liquid crystal panels 1110R, 1110B, and 1110G are the same as those of the liquid crystal device described above, and are driven by R, G, and B primary color signals supplied from an image signal processing circuit that is an example of an external circuit. Light emitted from the optical system including the liquid crystal panel and the phase difference plate enters the dichroic prism 1112 from three directions. In this dichroic prism 1112, R and B light is refracted at 90 degrees, while G light travels straight. Accordingly, as a result of the synthesis of the images of the respective colors, a color image is projected onto the screen or the like via the projection lens 1114.

  Here, paying attention to the display images by the liquid crystal panels 1110R, 1110B, and 1110G, the display image by the liquid crystal panel 1110G needs to be horizontally reversed with respect to the display images by the liquid crystal panels 1110R, 1110B.

  Since light corresponding to the primary colors R, G, and B is incident on the liquid crystal panels 1110R, 1110B, and 1110G by the dichroic mirror 1108, it is not necessary to provide a color filter.

  Since such a projector includes the above-described liquid crystal device as a light valve, the image quality of a projected image projected on a projection surface such as a screen is improved, and a high-quality image can be displayed.

1 is a block diagram showing an electrical configuration of a liquid crystal device which is an embodiment of a liquid crystal device according to a first invention of the present invention. It is a top view of the liquid crystal device which is one Embodiment of the liquid crystal device which concerns on 1st invention of this invention. FIG. 3 is a cross-sectional view taken along the line III-III ′ of FIG. 2. 4 is a circuit diagram showing a circuit configuration of a display unit that is a part of a liquid crystal device that is an embodiment of the liquid crystal device according to the first aspect of the present invention. It is the schematic diagram which showed typically the pretilt angle of the liquid crystal molecule in the liquid crystal device which is one Embodiment of the liquid crystal device which concerns on 1st invention of this invention. 1 is a plan view illustrating a configuration of a projector that is an example of an electronic apparatus according to the invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal device, 10 ... TFT array substrate, 20 ... Counter substrate, 200 ... Display part, 220 ... Specific circuit part, Va, Vb ... Initial applied voltage

Claims (3)

A display unit having a liquid crystal element including liquid crystal molecules, and capable of displaying an image according to a voltage applied to the liquid crystal element;
A drive circuit for applying the voltage to the liquid crystal element ;
With
When operating the display unit to increase the contrast of the image, the driving circuit applies a first initial voltage to the liquid crystal element,
In the liquid crystal device, the drive circuit applies a second initial voltage to the liquid crystal element when the display unit is operated so as to improve the responsiveness of the liquid crystal element . The liquid crystal according to claim 1, wherein a pretilt angle of the liquid crystal molecules when the first initial voltage is applied is larger than a pretilt angle of the liquid crystal molecules when the second initial voltage is applied. apparatus.   An electronic apparatus comprising the liquid crystal device according to claim 1.

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