BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
FIG. 1 is a plan view showing the configuration of a liquid crystal panel according to a first embodiment of the invention.
FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1.
FIG. 3 is a cross-sectional view showing the configuration of a liquid crystal device and a path of incident light according to the first embodiment of the invention.
FIG. 4 is a perspective view showing compensation directions of optical compensation films.
FIG. 5 is a cross-sectional view showing arrangement of liquid crystal molecules in a liquid crystal layer.
FIG. 6 is a cross-sectional view showing the configuration of a liquid crystal device including dust-proof glass and a path of incident light according to a second embodiment of the invention.
FIG. 7 is a cross-sectional view showing the configuration of a liquid crystal device including a micro lens array and a path of incident light according to a third embodiment of the invention.
FIG. 8 is a cross-sectional view showing the configuration of a liquid crystal device including a micro lens array and a path of incident light according to a fourth embodiment of the invention.
FIG. 9 is a cross-sectional view showing the configuration of a liquid crystal device including a micro lens array and a path of incident light according to a fifth embodiment of the invention.
FIG. 10 is a plan view showing the configuration of a projector which is an example of an electronic apparatus including the liquid crystal device.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
Hereinafter, embodiments of the invention will be described with reference to the accompanying drawings. In the following embodiments, a TFT active-matrix-drive-type liquid crystal device in which a drive circuit is built will be described as an example of a liquid crystal device according to the invention.
First Embodiment
First, a liquid crystal panel 100 configuring a liquid crystal device according to a first embodiment of the invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a plan view showing the configuration of the liquid crystal panel 100 according to a first embodiment of the invention, and FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1. In FIGS. 1 and 2, an optical compensation film which will be described in detail later is not shown and only the liquid crystal panel 100 is shown.
In FIGS. 1 and 2, in the liquid crystal device according to the present embodiment, a TFT array substrate 10 and a counter substrate 20 face each other. A liquid crystal layer 50 is filled between the TFT array substrate 10 and the counter substrate 20. The TFT array substrate 10 and the counter substrate 20 are adhered to each other by a seal material 52 provided in a seal region located at the circumference of an image display region 10a.
In FIG. 1, a frame light-shielding film 53 for defining a frame region of the image display region 10a is provided on the counter substrate 20 inside the seal region, in which the seal material 52 is provided, in parallel to the seal region. In a region located outside the seal region, in which the seal region 52 is provided, among peripheral regions, a data line drive circuit 101 and an external circuit connection terminal 102 are provided along one side of the TFT array substrate 10. A sampling circuit 7 is provided so as to be covered with the frame light-shielding film 53 at the inside of the seal region along one side. Scanning line drive circuits 104 are provided so as to be covered with the frame light-shielding film 53 at the inside of the seal region along two sides adjacent to the one side. Further, on the TFT array substrate 10, upper and lower conducting terminals 106 to serve as upper and lower conduction materials 107 between the two substrates are provided at regions opposite to four corners of the counter substrate 20. Through these members, the electrical conduction is made between the TFT array substrate 10 and the counter substrate 20.
On the TFT array substrate 10, pulled wires for electrically connecting the external circuit connection terminal 102, the data line drive circuit 101, the scanning line drive circuits 104, and the upper and lower conduction terminals 106 are formed.
In FIG. 2, a lamination structure having thin-film transistors (TFTs) for pixel switching, which are drive elements, and wiring lines such as scanning lines and data lines is formed on the TFT array substrate 10. In the image display region 10a, pixel electrodes 9a are provided in a matrix on the TFTs for pixel switching and the wiring lines such as the scanning lines and the data lines. An alignment layer (not shown) is formed on the pixel electrodes 9a. The light-shielding film 23 is formed on the surface of the counter substrate 20 opposite the TFT array substrate 10. The light-shielding film 23 is, for example, formed of a light-shielding metal film and is, for example, patterned in a lattice shape in the image display region 10a of the counter substrate 20. On the light-shielding film 23, counter electrodes 21 formed of a transparent material are formed to face the plurality of pixel electrodes 9a in a solid shape. An alignment film is formed on the counter electrodes 21. The liquid crystal layer 50, which is formed of, for example, one kind of nematic liquid crystal or a mixture of plural kinds of nematic liquid crystal, takes a predetermined alignment state between a pair of alignment layers.
Although not show herein, on the TFT array substrate 10, a test pattern or a test circuit for testing the quality of the liquid crystal device or for testing the liquid crystal device for defects before delivery or during manufacture may be formed in addition to the data line drive circuit 101 and the scanning line drive circuit 104.
Next, the optical compensation film according to the present embodiment will be described with reference to FIGS. 3 to 5. FIG. 3 is a cross-sectional view showing the configuration of a liquid crystal device and a path of incident light. First, the position of the compensation film will be described with reference to FIG. 3. In the following drawings, the detailed members of the liquid crystal panel 100 shown in FIGS. 1 and 2 will be omitted and only related members will be shown.
In the liquid crystal device according to the present embodiment, the liquid crystal panel 100 is a twisted nematic (TN) type liquid crystal panel. Polarization plates 300a and 300b are provided with the liquid crystal panel 100 interposed therebetween. A first optical compensation film 201 is interposed between the light incident side polarization plate 300a and the liquid crystal panel 100 and a second optical compensation plate 202 is interposed between the light emission side polarization plate 300b and the liquid crystal panel 100. The first optical compensation film 201 and the second optical compensation film 202 may be integrally configured with the member such as the counter substrate 20 or the TFT array substrate 10 as shown in FIG. 3 or may be integrally configured with a support body which is separately provided. Alternatively, for example, the first optical compensation film 201 and the second optical compensation film 202 may be respectively configured in a seal shape to be attached to any substrate.
The first optical compensation film 201 and the second optical compensation film 202 may be provided by coating an inorganic material on a desired place using a method such as a deposition method. By this method, it is possible to provide the optical compensation film to a member having a complicated shape. In addition, since the optical compensation film need not be formed in a film shape in advance, it is possible to reduce manufacturing cost. Since the first optical compensation film 201 and the second optical compensation film 202 are formed of the inorganic material, deterioration due to strong light such as ultraviolet rays does not occur. Since strong light is always illuminated onto the optical compensation film during use, it is efficient for improving durability.
FIG. 4 is a perspective view showing compensation directions of the optical compensation films. The first optical compensation film 201 and the second optical compensation film 202 are arranged such that the compensation directions thereof are perpendicular to each other. For such an arrangement, in the deposition method, deposition processes are performed such that deposition directions are perpendicular to each other. In the first optical compensation film 201, light is compensated in an X direction of FIG. 4 and, in the second optical compensation film 202, the light is compensated in a Y direction. This is because the liquid crystal device according to the present embodiment is of the TN type. In the TN type, since light is twisted in the liquid crystal layer 50, it is preferable that polarizations of lights compensated at a light incident side and a light emission side of the liquid crystal layer 50 differ by 90 degrees. If the liquid crystal device is, for example, of a vertical alignment (VA) type or an in-place-switching (IPS) type instead of the TN type, the optical compensation films are appropriately selected and arranged according to the type of the liquid crystal device.
The first optical compensation film 201 provided at the light incident side of the liquid crystal panel 100 is arranged such that the optical compensation direction thereof corresponds to the alignment direction of the counter substrate 20 (see FIG. 3) provided at the light incident side of the liquid crystal panel 100. For example, the compensation direction of the first optical compensation film 201 is set to correspond to the rubbing direction of the counter substrate 20.
In contrast, the second optical compensation film 202 provided at the light emission side of the liquid crystal panel 100 is arranged such that the optical compensation direction thereof corresponds to the alignment direction of the TFT array substrate 10 (see FIG. 3) provided at the light emission side of the liquid crystal panel 100. For example, the compensation direction of the second optical compensation film 202 is set to correspond to the rubbing direction of the TFT array substrate 10.
For example, the optical compensation direction of the first optical compensation film 201 is arranged in the alignment direction of the counter substrate 20 and the optical compensation direction of the second optical compensation film 202 is arranged in the alignment direction of the TFT array substrate 10.
Returning to FIG. 3, an operation according to the path of the incident light will be described. First, the incident light is incident to the light incident side polarization plate 300a. That is, the incident light is linearly polarized light. The incident light passing through the polarization plate 300a is compensated by the first optical compensation film 201 such that a phase difference is adjusted. The light passing through the first optical compensation film 201 passes through the counter substrate 20 and is incident to the liquid crystal layer 50. At this time, there are liquid crystal molecules which do not completely align as required even when a voltage is applied to the vicinity of the interface of the liquid crystal layer. Hereinafter, the arrangement of the liquid crystal molecules will be described in detail.
FIG. 5 is a cross-sectional view showing the arrangement of the liquid crystal molecules in the liquid crystal layer. The liquid crystal molecules 501 in the liquid crystal layer 50 are twisted by 90 degrees when the voltage is not applied. When the voltage is applied, the liquid crystal molecules 501 are aligned along an electric field and thus are arranged in a vertical direction (501d and 501e). However, the liquid crystal molecules 501, 501b, 501c, 501f, 501g and 501h in the vicinity of the interface of the liquid crystal layer 50 are not completely arranged in the vertical direction and the long axes of the molecules gradually align toward a central region of the liquid crystal layer 50. Even in intermediate tone display, a plurality of liquid crystal molecules which are not completely arranged in the vertical direction are present. When the linearly polarized light is incident to the liquid crystal liquid 50 in such a state, a phase difference of light occurs and elliptically-polarized light is emitted. That is, if compensation is not performed in this state, contrast may deteriorate.
The light passing through the liquid crystal layer 50 passes through the TFT array substrate 10, is emitted from the liquid crystal panel 100, and is incident to the second optical compensation film 202, as shown in FIG. 3. In the second optical compensation film 202, a phase difference which occurs in the liquid crystal layer 50 is compensated.
The compensated light is incident to the light emission side polarization plate 300b and only light, which is twisted by 90 degrees through the liquid crystal layer 50, passes through the polarization plate 300b.
As described above, since the phase difference of the incident light is compensated by the first optical compensation film 201 and the second optical compensation film 202 to obtain the linearly polarized light, it is possible to efficiently prevent deterioration in the contrast of an image displayed on the liquid crystal device or to enlarge a viewing angle.
Second Embodiment
Next, a liquid crystal device according to a second embodiment will be described with reference to FIG. 6. The second embodiment is similar to the first embodiment except for dust-proof glass 150 and the configuration of the optical compensation film. Accordingly, in the second embodiment, the dust-proof glass 150 and the optical compensation film will be described and the other configurations will be omitted. FIG. 6 is a cross-sectional view showing the configuration of a liquid crystal device including the dust-proof glass and a path of incident light.
In the configuration shown in FIG. 6, first dust-proof glass 150a is interposed between the light incident side polarization plate 300a and the liquid crystal panel 100 and second dust-proof glass 150b is interposed between the light emission side polarization plate 300b and the liquid crystal panel 100. First optical compensation films 201a and 201b are provided on both surface of the first dust-proof glass 150a and second optical compensation films 202a and 202b are provided on both surfaces of the second dust-proof glass 150b. At this time, the first optical compensation film 201 or the second optical compensation film 202 may be provided on one surface of the dust-proof glass 150, instead of on the both surfaces of the dust-proof glass 150.
By providing the dust-proof glass 150, it is possible to prevent dust from flowing into the liquid crystal panel 100 to cause a failure. When the first optical compensation film 201 and the second optical compensation film 202 are arranged on the surfaces of the dust-proof glasses 150, a member or a fixing member for arranging the optical compensation films may not be newly used. Accordingly, it is possible to prevent deterioration of contrast or to enlarge a viewing angle by optically compensating for the incident light, while achieving space saving and cost reduction.
Third Embodiment
Next, a liquid crystal device according to a third embodiment will be described with reference to FIG. 7. The third embodiment is similar to the first embodiment except for a micro lens array 400 and the configuration of the optical compensation film. Accordingly, in the third embodiment, the micro lens array 400 and the optical compensation film will be described and the other configurations will be omitted. FIG. 7 is a cross-sectional view showing the configuration of a liquid crystal device including the micro lens array and a path of incident light.
In the liquid crystal device according to the present embodiment, a micro lens array 400 is interposed between the light incident side polarization plate 300a and the liquid crystal panel 100 and a first optical compensation film 201 is interposed between the light emission side polarization plate 300b and the liquid crystal panel 100.
In the liquid crystal panel 100, the micro lens array 400 is provided on a light incident side region of the liquid crystal layer 50, for improvement of substantial aperture efficiency, that is, improvement of light use efficiency, improvement of brightness, or improvement of color purity. In the micro lens array 400, since the incident light is condensed by the micro lenses, the light is bent. Since the bent light is vertically incident to the liquid crystal layer 50, a phase is apt to be shifted when the light is incident to the liquid crystal layer 50. Accordingly, a phase difference is compensated by providing the first optical compensation film 201 such that the light becomes the linearly polarized light. Accordingly, since the compensated light can be incident to the light emission side polarization plate 300b, it is possible to prevent deterioration of contrast and to enlarge a viewing angle.
In addition, the micro lens array 400 may be built into the liquid crystal panel 100.
Fourth Embodiment
Next, a liquid crystal device according to a fourth embodiment will be described with reference to FIG. 8. The fourth embodiment includes a second optical compensation film 202 provided at a light emission side of a first optical compensation film 201, in addition to the configuration of the third embodiment. Accordingly, in the fourth embodiment, the first optical compensation film 201 and the second optical compensation film 202 will be described and the other configurations will be omitted. FIG. 8 is a cross-sectional view showing the configuration of a liquid crystal device including the micro lens array and a path of incident light.
The optical compensation direction of one of the first optical compensation film 201 and the second optical compensation film 202 corresponds to the alignment direction of the TFT array substrate 10 provided at the light emission side of the liquid crystal layer 50. The optical compensation direction of the other of the first optical compensation film 201 and the second optical compensation film 202 corresponds to the alignment direction of the counter substrate 20 provided at the light incident side of the liquid crystal panel 100.
In more detail, the first optical compensation film 201 corresponds to the TFT array substrate 10 and the second optical compensation film 202 corresponds to the counter substrate 20. By this correspondence, it is possible to improve contrast.
In the liquid crystal device according to the present embodiment, the second optical compensation film 202 is provided in addition to the first optical compensation film 201. The second optical compensation film 202 may be integrally configured with the first optical compensation film 201 as shown in FIG. 8 or may be configured a support body which is separately provided.
Since the first optical compensation film 201 and the second optical compensation film 202 are provided at the light emission side of the liquid crystal panel 100, it is possible to perform two-step compensation with respect to the light passing through the liquid crystal layer 50. Accordingly, the light which is incident to the light emission side polarization plate 300b becomes more perfect linearly polarized light, compared with the case of providing one optical compensation film. Accordingly, it is possible to reduce light leakage in the light emission side polarization plate 300b. Therefore, it is possible to prevent deterioration of contrast and to enlarge a viewing angle.
One of the first optical compensation film 201 and the second optical compensation film 202 may be formed of, for example, a film for enlarging a viewing angle. This is an optical compensation device manufactured by coating a polymer alignment layer on a tri-acetyl cellulose (TAC) film, performing a rubbing process, and coating, aligning and fixing discotic liquid crystal. Since this optical compensation device has an effective characteristic regardless of an arrangement angle in a range of 80 degrees to 100 degrees, the decreasing rate of contrast due to deviation in the arrangement angle is decreased. Since this optical compensation device is a molded product, attachment is performed for arrangement of the device. Cost reduction or work time reduction in a manufacturing process can be achieved.
Accordingly, optical compensation with respective characteristics can be achieved using one optical compensation film formed of the inorganic material and one optical compensation device. For example, when the optical compensation film formed of the inorganic material is arranged at a side which is apt to be affected by ultraviolet rays in structure and the optical compensation device is arranged at the opposite side thereof, it is possible to reduce cost while improving durability. In consideration of the positions or the roles of the optical compensation film formed of the inorganic material and the optical compensation device, the optical compensation film and the optical compensation device are appropriately combined to obtain a plurality of advantages.
Fifth Embodiment
Next, a liquid crystal device according to a fifth embodiment will be described with reference to FIG. 9. The fifth embodiment is different from the fourth embodiment in the dust-proof glass 150 and the configuration of the optical compensation film. Accordingly, in the fifth embodiment, the dust-proof glass 150 and the optical compensation film will be described and the other configurations will be omitted. FIG. 9 is a cross-sectional view showing the configuration of a liquid crystal device including the micro lens array and a path of incident light.
In the liquid crystal device according to the present embodiment, dust-proof glass 150a is interposed between the light incident side polarization plate 300a and the micro lens array 400 and dust-proof glass 150b is interposed between the liquid crystal panel 100 and the light emission side polarization plate 300b. The first optical compensation film 201 is provided on the surface of the dust-proof glass 150b at the side of the liquid crystal panel and the second optical compensation film 202 is provided on the surface of the dust-proof glass 150b at the side of the polarization plate 300b. The optical compensation direction of the first optical compensation film 201 corresponds to the alignment direction of the counter substrate 20 provided at the light incident side of the liquid crystal layer 50 and the optical compensation direction of the second optical compensation film 202 corresponds to the alignment direction of the TFT array substrate 10 provided at the light emission side of the liquid crystal panel 100. The first and second optical compensation films may be integrally configured with the dust-proof glass 150 as shown in FIG. 9 or may be integrally configured with a support body which is separately provided.
As shown in FIG. 9, since the two optical compensation films, that is, the first optical compensation film 201 and the second optical compensation film 202, are provided at the light emission side of the liquid crystal panel 100, it is possible to perform two-step compensation with respect to the light passing through the liquid crystal layer 50. Accordingly, the light which is incident to the light emission side polarization plate 300b becomes more perfect linearly polarized light, compared with the case of providing one optical compensation film. Accordingly, it is possible to reduce light leakage in the light emission side polarization plate 300b. Therefore, it is possible to prevent deterioration of contrast and to enlarge a viewing angle.
Electronic Apparatus
Next, a projector using the above-described liquid crystal device as a light valve will be described. FIG. 10 is a plan view showing the configuration of the projector.
As shown in FIG. 10, a lamp unit 1102 formed of a white light source such as a halogen lamp is provided in the projector 110. The projection light emitted from the lamp unit 1102 is divided into three primary colors of RGB by four mirrors 1106 and two dichroic mirror 1108 provided in a light guide 1104 to be incident to liquid panels 1110R, 1110B and 1110G as light valves corresponding to the primary colors.
The liquid crystal panels 1110R, 1110B and 1110G have the same configuration of the above-described liquid crystal device and are driven by the primary color signals of R, G and B supplied from an image signal processing circuit. The light modulated by the liquid crystal panels is incident to the dichroic prism 1112 in three directions. In the dichroic prism 1112, light of R and B are refracted at 90 degrees and light of G goes straight. Therefore, an image of each color is synthesized, whereby a color image is projected onto a screen or the like through a projector lens 1114.
Here, when attention is focused on a display image by each of the light valves 1110R, 1110B, and 1110G, the display image by the light valve 1110G is needed to be mirror-inversed with respect to the display images by the light valves 1110R and 1110B.
Further, since light corresponding to each of the primary colors is incident to each of the light valves 1110R, 1110B, and 1110G by the dichroic mirrors 1108, there is no need to provide a color filter.
Further, in addition to the electronic apparatus described with reference to FIG. 10, a liquid crystal television, a view finder type or monitor-direct-view type video tape recorder, a car navigation device, a pager, an electronic organizer, an electronic calculator, a word processor, a workstation, a video telephone, a POS terminal, a device comprising a touch panel or the like can be exemplified. Further, it is needless to say that the liquid crystal device of the invention can be applied to the various electronic apparatus described above.
The invention is applicable to a liquid crystal on silicon(LCOS) in which a device is formed on a silicon substrate, in addition to the liquid crystal devices according to the above-described embodiments.
The invention is not limited to the above-described embodiment, and it is to be understood that changes and modifications may be made without departing from the spirit or scope of the invention as defined by the appended claims. The liquid crystal device and the electronic apparatus including the liquid crystal device according to the changes and modifications are also included in the scope of the invention.
The entire disclosure of Japanese Patent Application No. 2006-253822, filed Sep. 20, 2006 is expressly incorporated by reference herein.
Patent Application
20080068546
