LIQUID CRYSTAL DEVICE AND ELECTRONIC APPARATUS
20200117031 ยท 2020-04-16
Assignee
Inventors
Cpc classification
G02F1/13439
PHYSICS
G03B33/12
PHYSICS
G02F1/1337
PHYSICS
International classification
Abstract
In a liquid crystal device, a sheet resistance of an ITO film constituting a common electrode is set to be not less than 19/ and not more than 44/ so that the surface roughness of the ITO film is managed. Accordingly, a pre-tilt angle p of a liquid crystal material can be set to 4.30.6, which can suppress the video domain and improve the contrast. Additionally, a specific resistance of the ITO film may be set to be not less than 2740 nm.Math./ and not more than 6740 nm.Math./. In addition, in an X-ray diffraction result of the ITO film, an intensity Ia of a crystal plane orientation and an intensity Ib of a crystal plane orientation is configured to satisfy a following relationship:
0.85(Ia/(Ia+Ib))0.92
Claims
1. A liquid crystal device, comprising: a pixel electrode; a common electrode; a first oriented film covering the pixel electrode; a second oriented film covering the common electrode; and a liquid crystal layer that is disposed between the first oriented film and the second oriented film and that includes a liquid crystal material, wherein at least the common electrode, of the pixel electrode and the common electrode, includes an ITO film with a sheet resistance not less than 19 / and not more than 44 / and a pre-tilt angle that is a tilt angle of the liquid crystal material with respect to a thickness direction of the liquid crystal layer is not less than 3.7 and not more than 4.9.
2. The liquid crystal device according to claim 1, wherein the ITO film has a specific resistance of not less than 2740 nm.Math./ and not more than 6740 nm.Math./, the specific resistance being a product of a sheet resistance and a film thickness.
3. The liquid crystal device according to claim 1, wherein according to an X-ray diffraction result of the ITO film, 0.85(Ia/(Ia+Ib))0.92, where Ia is an intensity of a crystal plane orientation (222) and Ib is an intensity of a crystal plane orientation (440).
4. The liquid crystal device according to claim 1, wherein both of the pixel electrode and the common electrode include the ITO film.
5. The liquid crystal device according to claim 1, wherein the first oriented film and the second oriented film each include a columnar structure including a columnar body tilted obliquely with respect to a thickness direction of the liquid crystal layer.
6. An electronic apparatus, comprising the liquid crystal device according to claim 1.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0009]
[0010]
[0011]
[0012]
[0013]
[0014]
[0015]
[0016]
[0017]
[0018]
[0019]
[0020]
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0021] Exemplary embodiments of the present disclosure will be described below with reference to the drawings. In the drawings referred to in the following description, the scale of each layer and each member is different in order to make each layer and each member have a size that can be recognized in the drawing.
Configuration of Liquid Crystal Device
[0022]
[0023] As illustrated in
[0024] Both the first substrate 10 and the second substrate 20 have a quadrangle shape, and in a substantially central portion of the liquid crystal device 100, a display region 10a is provided as a rectangular region having a longer dimension in the direction from 3 o'clock toward 9 o'clock, and a shorter dimension in the direction from 0 o'clock toward 6 o'clock. In accordance with the above shapes, the sealing material 107 is also formed in a substantially rectangular shape, and a peripheral region 10b in a quadrangular frame-shape is provided between an inner peripheral edge of the sealing material 107 and an outer peripheral edge of the display region 10a.
[0025] The first substrate 10 is made of quartz, glass or the like. In the surface (one surface 10s) of the first substrate 10 at the side of the second substrate 20, in the outside of the display region 10a, a data line driving circuit 101 and a plurality of terminals 102 are formed along one side of the first substrate 10, and a scanning line driving circuit 104 is formed along the other side adjacent to this one side. A flexible wiring substrate 105 is coupled to the terminal 102, and various potentials and various signals are input to the first substrate 10 via the flexible wiring substrate 105.
[0026] At the one surface 10s side of the first substrate 10, in the display region 10a, a plurality of light-transmitting pixel electrodes 9a formed of an Indium Tin Oxide (ITO) film or the like, and transistors (not illustrated) electrically coupled to each of the plurality of pixel electrodes 9a are formed in a matrix shape. A first oriented film 16 is formed at the second substrate 20 side with respect to the pixel electrodes 9a, and the pixel electrodes 9a are covered with the first oriented film 16.
[0027] The second substrate 20 is made of quartz, glass or the like. A light-transmitting common electrode 21 made of an ITO film is formed at a surface (one surface 20s) of the second substrate 20 at the side of the first substrate 10, and a second oriented film 26 is formed with respect to the common electrode 21 at the side of the first substrate 10. Accordingly, the common electrode 21 is covered by the second oriented film 26. The common electrode 21 is formed substantially entirely at the second substrate 20.
[0028] A lens 24 overlapping the pixel electrode 9a is formed between the common electrode 21 and the second substrate 20. The lens 24 directs light to an open region of the first substrate 10. When the lens 24 is formed, a concave curved surface 201 is formed at the one surface 20s of the second substrate 20 at a position overlapping with each of the plurality of pixel electrodes 9a in a one-to-one manner. Further, a lens layer 28 that fills the interior of each of the plurality of concave curved surfaces 201 is provided at the second substrate 20, and the surface 280 of the lens layer 28 at the opposite side to the second substrate 20 is planar. A light-transmitting layer 29 is formed at the surface 280 of the lens layer 28 opposite to the second substrate 20, and a common electrode 21 is formed at a surface 290 opposite to the second substrate 20 of the light-transmitting layer 29.
[0029] The refractive index of the lens layer 28 is different from that of the second substrate 20. Thus, the concave curved surface 201 constituted the lens surface 240 of the lens 24. In the exemplary embodiment, the lens layer 28 has a greater refractive index than the second substrate 20. Therefore, the lens 24 has a positive power. In the exemplary embodiment, the second substrate 20 is made of a glass substrate or a quartz substrate (refractive index is 1.48 near a wavelength of 550 nm), and the lens layer 28 is composed of silicon oxynitride (refractive index is from 1.58 to 1.68 near a wavelength of 550 nm). The light-transmitting layer 29 is made of silicon oxide (refractive index is 1.48 near a wavelength of 550 nm).
[0030] A light shielding layer 27 having light-shielding properties formed from metal or a metal compound or the like is formed between the lens layer 28 and the light-transmitting layer 29. The light shielding layer 27 is formed, for example, as a partition 27a in a frame-like shape extending along the outer peripheral edge of the display region 10a. Also, the light shielding layer 27 may be formed as a black matrix in a region overlapping in plan view with a region located between pixel electrodes 9a adjacent to each other. In the embodiment, regions overlapping, when viewed in plan view, with the partition 27a in the peripheral region 10b of the first substrate 10 are formed with dummy pixel electrodes 9b formed simultaneously with the pixel electrodes 9a.
[0031] The first oriented film 16 and the second oriented film 26 are inorganic oriented film made of SiO.sub.x(x<2) or the like, and the liquid crystal material with negative dielectric anisotropy used in the liquid crystal layer 80 is substantially vertically oriented. In this way, the liquid crystal device 100 is configured to serve as a VA mode liquid crystal device.
[0032] The first substrate 10 includes an inter-substrate conduction electrode 109 being formed in a region positioning outside the sealing material 107 and overlapping with a corner portion of the second substrate 20 such that electrical conduction is established between the first substrate 10 and the second substrate 20. An inter-substrate conduction material 109a including conductive particles is disposed in the inter-substrate conduction electrode 109. The common electrode 21 of the second substrate 20 is electrically coupled to the first substrate 10 side via the inter-substrate conduction material 109a and the inter-substrate conduction electrode 109. Therefore, a common potential is applied to the common electrode 21 from the first substrate 10 side.
[0033] The liquid crystal device 100 of the embodiment is configured as a transmissive type liquid crystal device. The liquid crystal device 100 thus configured displays an image in such a manner that light incident from one substrate side of the first substrate 10 and the second substrate 20 is modulated while transmitting the other substrate side to be emitted. In the embodiment, the light incident from the second substrate 20 side, as indicated by an arrow L, is modulated by the liquid crystal layer 80 at each pixel while transmitting the first substrate 10 and emitted, thereby displaying an image. The liquid crystal device 100 may be configured as a reflective type liquid crystal device.
Configuration of Liquid Crystal Layer 80 and Other Components
[0034]
[0035] In the exemplary embodiment, the first oriented film 16 and the second oriented film 26 illustrated in
[0036] The orientation Dp of the pre-tilt of the liquid crystal material 85 is the orientation in which the end 852 at the second substrate 20 side is located with respect to the end 851 at the first substrate 10 side of the liquid crystal material 85 in a long axis direction 85a. In the liquid crystal device 100, when a drive voltage is applied between the pixel electrodes 9a and the common electrode 21, the liquid crystal materials 85 incline in the pre-tilt orientation Dp.
[0037] The liquid crystal panel 100p is disposed between a pair of polarizing elements disposed in crossed Nichols manner to cause the pre-tilt orientation Dp to form an angle of 45 with respect to a transmission axis or an absorption axis of the pair of polarizing elements. In the exemplary embodiment, for example, as illustrated in
[0038] As illustrated in
[0039] The liquid crystal materials 85 are pre-tilted by an orientation restriction force of the first oriented film 16. At that time, the pre-tilt angle p may not be identical to the angle c of the columnar bodies 16a. However, the pre-tilt angle p is controlled by the angle c of the columnar bodies 16a. Therefore, the pre-tilt angle p is controlled by the angle d of the deposition. In the embodiment, the first oriented film 16 is formed by setting the angle d to 45.
[0040] The second oriented film 26 has a configuration identical to the configuration of the first oriented film 16. Therefore, like numbers in parentheses reference like components in
Range of Pre-tilt Angle p
[0041]
[0042] In
[0043] According to the results illustrated in
[0044] In order to achieve such a configuration, it is necessary to appropriately form the first oriented film 16 and the second oriented film 26, and to do that, it is necessary to appropriately manage the surface roughness and the like of the ITO film constituting the pixel electrodes 9a and the common electrode 21. In particular, it is necessary to control the surface roughness or the like of the ITO film constituting the common electrode 21. In the embodiment, it is difficult to manage the surface roughness of the ITO film directly, and therefore, as described below, the sheet resistance of the ITO film or the like and the ratio of the intensity of the crystal plane orientation obtained by X-ray diffraction of the ITO film may be managed, which controls the pre-tilt angle p.
[0045] Such management is performed on the ITO film constituting at least the common electrode 21 of the pixel electrodes 9a and the common electrode 21. However, it may be performed on both the ITO film that constitutes the pixel electrodes 9a and the ITO film that constitutes the common electrode 21.
Sheet Resistance of ITO Film
[0046]
[0047] As illustrated in
y=0.0458x+2.8634 [0048] x: Sheet resistance (/) [0049] y: Pre-tilt angle p ()
[0050] In the embodiment, based on the above approximation formula, the sheet resistance of the ITO film is set to be not less than 19 / and not more than 44 /, so that a pre-tilt angle p of 4.30.6 is achieved. Note that, the lower limit of the sheet resistance of the ITO film is set to 19 / by rounding up the decimal part of the value obtained from the approximation formula, and the upper limit of the sheet resistance of the ITO film is set to 44 / by rounding down the decimal part of the value obtained from the approximation formula.
[0051] As illustrated in
y=0.0003x+2.878 [0052] x: Specific resistance (nm.Math./) [0053] y: Pre-tilt angle p ()
[0054] In the embodiment, the specific resistance of the ITO film is set to be not less than 2740 nm.Math./ and not more than 6740 nm.Math./, so that the pre-tilt angle p of 4.30.6 is more reliably achieved.
X-ray Diffraction Results of ITO Film
[0055]
[0056] As illustrated in
[0057] Furthermore, when film formation conditions such as pressure during film formation are changed and the formed films are used as the second oriented film 26, a relationship between the intensities of crystal plane orientations (622), (440), (400), (211), (222) and the pre-tilt angle p is as illustrated in
[0058] For example, when the relationship between the intensity Ia of the crystal plane orientation (222) and the pre-tilt angle p is approximated to a linear function, the resulting approximation formula is as follows, and the square of the correlation coefficient R is 0.9983.
y=0.2112x+0.0732 [0059] x: Pre-tilt angle p () [0060] y: Intensity Ia of the crystal plane orientation (222)
[0061] When the relationship between the intensity Ib of the crystal plane orientation (440) and the pre-tilt angle p is approximated to a linear function, the resulting approximation formula is as follows, and the square of the correlation coefficient R is 0.9558.
y=0.1308x+0.5567 [0062] x: Pre-tilt angle p () [0063] y: Intensity Ib of the crystal plane orientation (440)
[0064] Additionally, the relationship between the value of Ia/(Ia+Ib), the value of Ib/Ia+Ib), and the pre-tilt angle p are as illustrated in
[0065] For example, when the relationship between the Ia/(Ia+Ib) value and the pre-tilt angle p is approximated to a linear function, the resulting approximation formula is as follows, and the square of the correlation coefficient R is 0.9706.
y=0.144x+0.2894 [0066] x: Pre-tilt angle p () [0067] y: Ia/(Ia+Ib)
[0068] In addition, when the relationship between the Ib/(Ia+Ib) value and the pre-tilt angle p is approximated to a linear function, the resulting approximation formula is as follows, and the square of the correlation coefficient R is 0.9706.
y=0.144x+0.71 [0069] x: Pre-tilt angle p () [0070] y: Ib/(Ia+Ib)
[0071] In the embodiment, the relationship between the value of Ia/(Ia+Ib) and the pre-tilt angle p is approximated to a cubic function, and the range of Ia/(Ia+Ib) is set based on this approximation formula. More specifically, as illustrated in
y=0.025x.sup.3+0.3793x.sup.2+1.9303x2.3676 [0072] x: Pre-tilt angle p () [0073] y: Ia/(Ia+Ib)
[0074] According to the result illustrated in
0.85(Ia/(Ia+Ib))0.92
[0075] Note that, the lower limit of Ia/(Ia+Ib) is set to 0.85 by rounding up the third decimal place of the value obtained from the approximation formula, and the upper limit of Ia/(Ia+Ib) is set to 0.92 by rounding down the third decimal place of the value obtained from the approximation formula.
Main Effects of Embodiment
[0076] As described above, in the embodiment, the pre-tilt angle p of 4.30.6 is achieved by managing the sheet resistance of the ITO film used in the second oriented film 26, or the like, and the ratio of the intensity of the crystal plane orientation obtained by X-ray diffraction of the ITO film. Thus, even when the surface roughness of the ITO film is not measured, it is possible to achieve a liquid crystal device 100 that is superior in terms of the video domain and the contrast.
[0077] More specifically, since the common electrode 21 includes ITO film having a sheet resistance of not less than 19/ and not more than 44 /, the pre-tilt angle p can be 4.30.6.
[0078] In addition, since the specific resistance, which is the product of the sheet resistance and the film thickness of the ITO film used in the common electrode 21 is set to not less than 2740 nm.Math./ and not more than 6740 nm.Math./, ITO film can be appropriately managed even when the film thickness of the ITO film is changed, so that the pre-tilt angle p can be set to 4.30.6.
[0079] Furthermore, in the X-ray diffraction results of the ITO film used in the common electrode 21, since the intensity Ia of the crystal plane orientation (222) and the intensity Ib of the crystal plane orientation (440) satisfy the relationship below, the pre-tilt angle p can be more appropriately controlled, so that the pre-tilt angle p can be set to 4.30.6.
0.85(Ia/(Ia+Ib))0.92
Other Exemplary Embodiments
[0080] Although the above exemplary embodiments have been described when the liquid crystal device 100 is in the normally black mode, the present disclosure may be applied when the liquid crystal device 100 is in the normally white mode.
[0081] In the exemplary embodiment described above, the ITO film that constitutes the pixel electrode 9a is described with reference to the management of the ITO constituting the common electrode 21, The management described in the above exemplary embodiments may be performed on both of the ITO constituting the pixel electrode 9a and the ITO constituting the common electrode 21.
Installation Example to the Electronic Apparatus
[0082] A projection-type display device (liquid crystal projector) will be described as an example of the electronic apparatus using the liquid crystal device 100 according to the above-described exemplary embodiments.
[0083] The projection-type display device 2100 is provided with a lamp unit 2102 (light source unit) including a white light source, such as a halogen lamp. Projection light emitted from the lamp unit 2102 is split into three primary colors of red (R), green (G), and blue (B) by three mirrors 2106 and two dichroic mirrors 2108 installed inside. The split projection light is guided to light valves 100R, 100G, and 100B corresponding to each of the primary colors, respectively and is modulated. Note that, since the light of the B color has a long optical path as compared to the other light of the R color and the G color, the light of the B color is guided via a relay lens system 2121 including an incidence lens 2122, a relay lens 2123, and an emission lens 2124 to prevent a loss due to the long optical path of the light of the B color. The light valves 100R, 100G, and 100B each include an incident-side polarization separation element 111 overlapping, on an incident side, with the liquid crystal device 100, and an emission side polarization separation element 112 overlapping, on an emission side, with the liquid crystal device 100.
[0084] The light modulated by each of the light valves 100R, 100G, and 100B is incident on a dichroic prism 2112 from three directions. Then, at the dichroic prism 2112, the light of the R color and the light of the B color are reflected at 90 degrees, and the light of the G color is transmitted. Accordingly, an image of the primary colors are synthesized, and subsequently a color image is projected on a screen 2120 by a projection lens group 2114 (projection optical system).
Other Projection-Type Display Device
[0085] A projection-type display device may be configured to use, as a light source unit, an LED light source configured to emit light in various colors, or the like to supply light in various colors emitted from the LED light source to different light valves respectively.
Other Electronic Apparatuses
[0086] The electronic apparatus including the liquid crystal device 100 to which the present disclosure is applied is not limited to the projection-type display device 2100 of the above-described exemplary embodiment. Examples of the electronic apparatus may include a projection-type Head Up Display (HUD), a direct-view type Head-Mounted Display (HMD), a personal computer, a digital still camera, and a liquid crystal television.