JP5151657B2 - Liquid crystal device and electronic device - Google Patents

Description

  The present invention relates to an optical element, a liquid crystal device, an electronic apparatus, a method for manufacturing an optical element, and a method for manufacturing a liquid crystal device.

  As one of optical elements having a polarization separation function, a wire grid polarization element is known. This is an element with a large number of conductor fine wires arranged at a pitch shorter than the wavelength of the light, and reflects the component having a polarization axis parallel to the fine wires in the incident light and is polarized perpendicular to the fine wires. It has the property of transmitting a component having an axis.

  On the other hand, as a means for reflecting and diffusing incident light, for example, an aluminum diffusion plate having smooth irregularities with a height of about 1 μm on the surface is known. If a wire grid polarizing element is formed on the surface of this aluminum diffusion plate, a polarization separation function can be added to the reflection diffusion function (see Patent Document 1).

Japanese translation of PCT publication No. 2002-520777

  However, it is difficult to form such an optical element. The reason is as follows. That is, as shown in FIG. 21, when the resist 34 is applied to the surface of the aluminum diffusion plate 97 formed on the base 96 to form a wire grid polarizing element by photolithography, the aluminum diffusion plate 97 Due to surface irregularities, the thickness becomes non-uniform. For this reason, the exposure and development of the resist 34 are partially insufficient, and there is a problem that a fine wire is formed only on a part of the aluminum diffusion plate 97. Further, in laser interference exposure, the slope indicated by the region B in FIG. 21 becomes a shadow of the laser, so that there is a problem that the exposure of the region B is incomplete and fine wires are not formed.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  [Application Example 1] A diffraction function layer that diffracts at least part of incident light, and a grid having a polarization separation function, which is formed on one surface of the diffraction function layer and includes a plurality of fine wires, The one surface of the diffraction function layer includes a plurality of first regions, and a plurality of second regions whose height from the other surface of the diffraction function layer is different from the first region, An optical element, wherein a step portion is provided at a boundary between the first region and the second region.

  According to such a configuration, a plurality of irregularities formed by the first region and the second region are distributed on one surface of the diffraction function layer. The diffractive functional layer can diffract incident light by the uneven distribution and diffuse it in a direction different from the incident direction. In the incident light, a component having a polarization axis parallel to the fine wire is reflected in the grid, and a component having a polarization axis perpendicular to the fine wire is transmitted. As described above, according to the optical element, incident light can be separated into reflected light and transmitted light having different polarization states, and the emission direction can be diffused.

  Application Example 2 In the optical element described above, the first region and the second region are parallel to each other.

  According to such a configuration, light can be simultaneously incident on the first region and the second region at an equal angle. For this reason, a grid can be easily formed on the diffraction function layer by a laser interference exposure method. Note that a photolithography method other than the laser interference exposure method can also be applied.

  Application Example 3 In the above optical element, the first region is irregularly arranged on the one surface.

  According to such a configuration, the unevenness formed by the first region and the second region has an irregular distribution with no law and statistical deviation on one surface of the diffraction function layer. For this reason, incident light can be diffused in various directions. Therefore, it is possible to widen the diffusion range of incident light by the optical element.

  Application Example 4 In the optical element, the optical element includes a plurality of unit patterns in which the plurality of first regions and the plurality of second regions are arranged in a specific irregular distribution. A featured optical element.

  According to such a configuration, the photomask used for manufacturing the diffraction function layer can also have a structure in which mask patterns corresponding to the unit patterns are repeatedly arranged, and the photomask can be easily created. Thereby, it becomes possible to manufacture an optical element easily.

  Application Example 5 In the optical element described above, the directions of adjacent unit patterns are different from each other.

  According to such a configuration, it is possible to eliminate the unevenness in the diffusion direction caused by the repetition period of the unit pattern.

  Application Example 6 In the optical element described above, outer peripheries of the first region and the second region include a straight line, and the fine wires are arranged with a certain angle with respect to the straight line. An optical element characterized by being made.

  According to such a configuration, the step portion provided at the boundary between the first region and the second region is not parallel to the fine wire. For this reason, the malfunction that the fine wire arrange | positioned in the vicinity of the said level | step difference becomes unstable can be avoided.

  Application Example 7 In the optical element described above, when the wavelength of incident light is λ, the incident angle is θ, and the refractive index of the surrounding medium of the optical element is n, from the other surface of the diffraction function layer The optical element is characterized in that the difference between the height to the first region and the height to the second region is substantially equal to λ / (4n · cos θ).

  According to such a configuration, incident light having the wavelength λ can be diffused widely.

  Application Example 8 In the optical element described above, the diffraction function layer is made of a material different from that of the grid and has a light-transmitting property.

  According to such a structure, the component which permeate | transmitted the grid among incident light can be taken out outside an optical element. That is, a transflective optical element can be obtained.

  Application Example 9 In the optical element, an adhesion layer made of a material different from both the diffraction function layer and the grid is formed between the diffraction function layer and the grid, and the diffraction function layer The adhesion strength between the adhesion layer and the grid, and the adhesion strength between the grid and the adhesion layer are higher than the adhesion strength between the diffraction function layer and the grid.

  According to such a structure, the adhesiveness between a diffraction function layer and a grid can be improved by passing an adhesion layer.

  Application Example 10 A liquid crystal device having a plurality of pixels, the liquid crystal device being disposed between the first substrate and the second substrate that are disposed to face each other, and the first substrate and the second substrate. A liquid crystal, and an optical element disposed on at least a part of each of the pixels of the surface of the first substrate facing the second substrate, wherein the optical element includes at least incident light. A diffraction function layer that diffracts a part of the diffraction function layer; and a grid that is formed on one surface of the diffraction function layer and includes a plurality of fine wires and that has a polarization separation function, and the one surface of the diffraction function layer is A plurality of first regions, and a plurality of second regions different from the first region in height from the other surface of the diffraction function layer, the first region and the second region A liquid crystal device, wherein a step portion is provided at a boundary with the region.

  According to such a configuration, a region where the optical element is formed in the pixel can be used as a reflective display unit, and the remaining region can be used as a transmissive display unit. Light incident on the reflective display portion from the second substrate side is reflected and diffused by the optical element. Thus, since the optical element having both the light reflection function, the polarization separation function, and the light diffusion function is disposed on the inner surface of the substrate, the liquid crystal device can be thinned. Moreover, since the liquid crystal side surface of the optical element has a shape close to a flat surface, there is little adverse effect on the alignment of the liquid crystal, and the display quality can be improved.

  Application Example 11 The liquid crystal device includes an illumination device that irradiates light to the first substrate, which is disposed on the opposite side of the first substrate from the second substrate. A liquid crystal device.

  According to such a configuration, transmissive display can be performed by extracting light from the illumination device from the transmissive display unit of the pixel. Here, the light that has entered the reflective display unit from the lighting device is reflected and diffused by the optical element, and then enters the lighting device again. Part of this light is reflected by the illumination device and enters the transmissive display unit. Thus, the light use efficiency of transmissive display can be improved.

  Application Example 12 Electronic equipment in which the liquid crystal device is mounted on a display portion.

  According to such a configuration, the electronic device can be reduced in size and high-quality display can be performed on the display unit.

  [Application Example 13] A diffraction functional layer that diffracts at least a part of incident light, and a grid including a plurality of fine wires formed on one surface of the diffraction functional layer, There are a plurality of regions having different heights from the other surface of the diffraction function layer on the opposite side of one surface, and stepped portions are provided at each of the boundaries of the plurality of regions having different heights. An optical element.

  [Operation Example 14] In the above optical element having a plurality of regions having different heights, where the wavelength of incident light is λ, the incident angle is θ, and the refractive index of the surrounding medium of the optical element is n, The height of the step portion is substantially equal to (2m + 1) λ / (4n · cos θ); m = 0, 1, 2, 3,.

  According to such a structure, the said level | step-difference part of different height can be arrange | positioned by distribution according to a use, and an application range will spread more.

  A liquid crystal device having a plurality of pixels using the above-described optical elements having a plurality of regions having different heights, wherein the first substrate and the second substrate disposed opposite to each other, the first substrate, A liquid crystal disposed between the second substrate, and the optical element is disposed in at least a part of the plurality of pixel regions between the first substrate and the liquid crystal, The plurality of areas are a red area, a green area and a blue area, and the red area, the green area and the blue area have different heights. Liquid crystal device.

  With such a configuration, it is possible to configure a liquid crystal device that can reflect and diffuse according to the wavelengths of the three primary colors of light.

  Application Example 15 By processing a part of one surface of the diffraction function material layer, the one surface has a plurality of first regions, and the height from the other surface is the first region. Includes a plurality of different second regions, and a step of forming a diffraction function layer provided with a step portion at a boundary between the first region and the second region, and a conductor on the diffraction function layer A method of manufacturing an optical element, comprising: forming a film; and forming a grid having a polarization separation function including a plurality of fine wires by processing a part of the conductor film .

  According to such a manufacturing method, it is possible to manufacture an optical element that can separate incident light into reflected light and transmitted light having different polarization states and can diffuse the emission direction thereof. As a processing method, etching, exposure / development, mold formation, or the like can be used.

  Application Example 16 In the optical element manufacturing method, the step of forming the grid includes a step of laminating an antireflection film and a resist in this order on the conductor film, and laser interference exposure on the resist. And a step of developing the conductive film using the developed resist as a mask, and a step of removing the resist and the antireflection film.

  According to such a manufacturing method, the reflection of the laser beam on the surface of the conductor film at the time of laser interference exposure can be suppressed by the antireflection film. Thereby, a grid can be formed with high shape and dimensional accuracy.

  Application Example 17 A method of manufacturing a liquid crystal device having a plurality of pixels, the step of forming a diffraction function material layer on a first substrate, the step of forming an optical element on at least a part of the pixels, Bonding the second substrate so as to oppose the surface of the first substrate on which the optical element is formed, and the step of forming the optical element includes one of the diffraction function material layers By processing a part of the surface, the one surface includes a plurality of first regions and a plurality of second regions that are different from the first region in height from the other surface. And a step of forming a diffraction function layer in which a step portion is provided at a boundary between the first region and the second region, a step of forming a conductor film on the diffraction function layer, By processing a part, it has a polarization separation function including multiple fine wires. A method of manufacturing a liquid crystal device which comprises the steps, a to form a that grid.

  According to such a manufacturing method, a liquid crystal device having an optical element having both a light reflection function, a polarization separation function, and a light diffusion function on the inner surface of the substrate can be manufactured.

  Application Example 18 In the liquid crystal device manufacturing method, the pixel includes a reflective display portion and a transmissive display portion, and the step of forming the optical element is formed in the transmissive display portion of the pixels. A method for producing a liquid crystal device, comprising the step of removing the conductive film.

  According to such a manufacturing method, a reflective display unit including the optical element and a transmissive display unit having no optical element can be provided in one pixel.

  Hereinafter, embodiments of the optical element will be described with reference to the drawings. In the drawings shown below, the dimensions and ratios of the components are appropriately different from the actual ones in order to make the components large enough to be recognized on the drawings.

(A. Optical element)
FIG. 1A is a perspective view of the optical element 1 according to this embodiment, and FIG. 2A is a cross-sectional view taken along the XZ plane of the optical element 1 in FIG. The optical element 1 includes a base 6 made of glass or the like, a diffraction function layer 4 disposed on the base 6, and a grid 2 disposed on the diffraction function layer 4. FIG. 1 (a) is an enlarged view of a part of the optical element 1, and actually the same structure is continuous over a wider range of the XY plane.

  FIG. 1B is a perspective view showing the shape of the diffraction function layer 4, and is a state in which the grid 2 is removed from FIG. The diffraction function layer 4 is made of a polymer having translucency with respect to incident light, and a large number of irregularities are formed on one surface. The one surface includes a plurality of first regions 4a and a plurality of second regions 4b. Here, the second region 4b is different from the first region 4a in height from the other surface 4c of the diffraction function layer 4 (that is, the surface of the diffraction function layer 4 in contact with the substrate 6). In the present embodiment, the second region 4b is higher than the first region 4a. A step 8 is provided at the boundary between the first region 4a and the second region 4b. The height g (FIG. 2A) of the stepped portion 8 is set to be smaller than the wavelength of the incident light, and can be set to 152 nm, for example. Further, the step portion 8 is substantially perpendicular to the first region 4a and the second region 4b. That is, the cross section of the diffraction function layer 4 has a substantially rectangular shape (rectangular wave shape).

  The arrangement of the first region 4a and the second region 4b is random (irregular), and the shape thereof is a square or a shape obtained by irregularly connecting the squares vertically and horizontally. Here, the minimum dimension (that is, the length of one side of the square) δ (FIG. 2A) of the first region 4a and the second region 4b is longer than the wavelength λ of the incident light and is used for visible light. In this case, it can be set to 2 μm, for example. The first region 4a and the second region 4b are planes parallel to each other.

  A grid 2 is actually formed on one surface of the diffraction function layer 4 (that is, on the first region 4a and the second region 4b) as shown in FIG. The grid 2 is composed of a number of fine aluminum wires parallel to each other. This fine wire is arranged in parallel with one of the straight lines on the outer periphery of the first region 4a and the second region 4b. The arrangement pitch d of the fine wires (FIG. 2A) is shorter than the wavelength λ of the incident light, and can be set to 140 nm, for example. In FIG. 1A, for convenience of explanation, the number of fine wires is smaller than the actual number.

FIG. 2B is an enlarged cross-sectional view of a part of FIG. As shown in this figure, the grid 2 is sealed by a sealing layer 3 made of SiO ₂ or SiN, and the space surrounded by the diffraction function layer 4, the grid 2 and the sealing layer 3 is in a vacuum state. It has become.

An adhesion layer made of a material different from both the diffraction function layer 4 and the grid 2 may be formed between the diffraction function layer 4 and the grid 2. At this time, the adhesion strength between the diffraction function layer 4 and the adhesion layer and the adhesion strength between the grid 2 and the adhesion layer are preferably higher than the adhesion strength between the diffraction function layer 4 and the grid 2. With such a configuration, the adhesion between the diffraction function layer 4 and the grid 2 can be improved through the adhesion layer. As the material of the adhesion layer, for example, a dielectric thin film such as SiO ₂ can be used.

  FIG. 3 is a schematic diagram for explaining the function of the optical element 1. Among these, FIG. 3A is a diagram showing the function of the diffraction function layer 4, and FIG. 3B is a diagram showing the function of the grid 2.

  As shown in FIG. 3B, in the incident light 80 on the grid 2, the component p having a polarization axis parallel to the fine wire is reflected by the grid 2, and the component s having a polarization axis perpendicular to the fine wire is the grid. 2 is transmitted. That is, the optical element 1 having the grid 2 has a polarization separation function, and can separate the incident light 80 into reflected light 80r and transmitted light 80t having different polarization states.

  In the optical element 1 shown in FIG. 3A, the black region corresponds to the first region 4a, and the white region corresponds to the second region 4b. A plurality of irregularities formed by the first region 4a and the second region 4b are distributed on one surface of the diffraction function layer 4 (FIG. 1B). The diffraction function layer 4 can diffract the incident light 80 by this uneven distribution and diffuse it in a direction different from the incident direction as shown in FIG. More specifically, according to the action of the diffractive function layer 4, both the reflected light 80 r reflected by the grid 2 and the transmitted light 80 t transmitted through the grid 2 can be diffused.

  FIG. 4A is a graph showing the diffusion characteristics of the optical element 1. The measurement conditions for this diffusion characteristic are shown in FIG. That is, while projecting light from the light projecting unit 94 at an angle of 25 degrees from the normal of the optical element 1, light is received while changing the angle θ of the light receiving unit 95 from 0 degrees to 60 degrees, and the angle θ and the reflectance are reflected. Is a plot of the relationship. It can be seen that the diffused light in the diffraction function layer 4 is diffused widely even at angles other than regular reflection. The spread of reflected light (range of viewing zone angle) φ is determined from the minimum dimension δ of the first region 4a and the second region 4b included in the diffraction function layer 4, and φ2 = λ / δ between the two. There is a relationship. For example, when the wavelength λ of incident light is 550 nm and δ = 2 μm, φ = 32 degrees, and a practically sufficient viewing zone can be obtained when applied to a reflective display device. Further, by devising the arrangement of the first region 4a and the second region 4b in the diffraction function layer 4 or the planar shape thereof, the diffusion characteristics (the width of the viewing zone, the viewing angle) according to the purpose of use and the use environment. The shape of the area can be controlled.

  More specifically, the height g of the stepped portion 8 is preferably a height that satisfies g = λ / (4n · cos θ). Here, n is the refractive index of the surrounding medium of the optical element 1, and θ is the incident angle of light. By setting the step portion 8 in this way, the diffusion range of the reflected light 80r and the transmitted light 80t can be expanded. Further, according to this equation, the height g of the stepped portion 8 of the diffraction function layer 4 can be reduced by using a material having a high refractive index as the surrounding medium of the grid 2. As the height g of the stepped portion 8 is smaller, the manufacturing process (including the photolithography method) of the grid 2 becomes easier, so that the grid 2 can be manufactured more easily. As the surrounding medium laminated on the grid 2, for example, SiN (n≈1.5) is preferable.

  When the optical element 1 is applied to a specific display device, the first region 4a and the second region 4b of the diffraction function layer 4 may be arranged completely randomly over the entire range. You can also do the following: That is, a unit pattern in which a plurality of first regions 4a and a plurality of second regions 4b are arranged in a specific random distribution is created, and a plurality of the unit patterns are repeatedly arranged. Here, the size of the unit pattern is arbitrary, but for example, it can be a square having a side of 400 μm. According to such a configuration, the photomask used for manufacturing the diffraction function layer 4 can also have a structure in which a mask pattern corresponding to the unit pattern is repeatedly arranged, and the photomask can be easily created. Thereby, it becomes possible to manufacture an optical element easily.

  Further, as shown in FIG. 5, the unit patterns 1u adjacent to each other may be arranged so that the directions thereof are different from each other. In FIG. 5, an arrow in the unit pattern 1u indicates the direction of the unit pattern 1u. According to such an arrangement, the periodicity of the diffractive functional layer 4 can be kept low. As a result, the deviation in the diffusion direction caused by the repetition period of the unit pattern 1u can be eliminated, and coloring due to diffraction causes a practical problem. It can be relaxed to a lesser extent.

  As described above, the optical element 1 having the grid 2 and the diffraction function layer 4 can separate the incident light 80 into the reflected light 80r and the transmitted light 80t having different polarization states by the grid 2, and the reflection. The light 80r and the transmitted light 80t can be diffused by the diffraction function layer 4. That is, according to this embodiment, the optical element 1 having both the polarization separation function and the light diffusion function can be obtained.

(B. Manufacturing method of optical element)
Then, the manufacturing method of the optical element 1 is demonstrated using FIGS. 6-8. FIG. 6 is a flowchart of the manufacturing method of the optical element 1, and FIGS. 7 and 8 are cross-sectional views in the manufacturing process of the optical element 1. Hereinafter, it demonstrates along the flowchart of FIG.

  In step S <b> 1, the diffraction function layer 4 is formed on the substrate 6. In this step, first, a diffraction function material layer 4L made of a polymer is laminated on a base 6 made of glass having a thickness of 0.7 mm by using a spin coat method or the like (FIG. 7A). Subsequently, a region corresponding to the first region 4a in the diffraction function material layer 4L is selectively exposed using a photomask, and then removed by wet development, so that one surface of the diffraction function material layer 4L is formed. The distribution of the first region 4a and the second region 4b is formed. In the present embodiment, the difference in height between the first region 4a and the second region 4b, that is, the depth of the etched portion of the diffraction function material layer 4L is 152 nm. Further, the etching is performed so that the first region 4a and the second region 4b are parallel to each other. Thus, the diffraction function layer 4 is formed on the substrate 6 (FIG. 7B).

  Next, in step S2, an aluminum film 2L as a conductor film having a thickness of 120 nm is formed on the diffraction function layer 4 by sputtering or the like.

Next, in step S3, an antireflection film 32 is formed on the aluminum film 2L by vacuum deposition or sputtering. The antireflection film 32, for example, SiC or _{SiO x N y: H (x} , y composition ratios) are suitable. Alternatively, ITO (Indium Tin Oxide) may be used. Whether or not it has an antireflection effect depends greatly on the complex refractive index of the material. For example, the real part value of the complex refractive index is 1.4 or more, and the imaginary part value of the complex refractive index is -0.1 or more. -1.5 or less is desirable. FIG. 9 shows the relationship between the thickness of the antireflection film 32 and the intensity of reflected light at the interface between the resist 34 and the antireflection film 32 when the resist 34 (FIG. 7C) is stacked on the antireflection film 32. (A) is the case where SiC is used as the antireflection film 32, and (b) is the case where SiO _x N _y : H is used as the antireflection film 32. Note that the optimum film thickness of the antireflection film 32 varies depending on the film forming conditions even if the same material is used.

  Next, in step S4, a resist 34 having a substantially flat plane is formed on the antireflection film 32 by spin coating or the like (FIG. 7C).

Next, in step S5, the resist 34 is subjected to laser interference exposure to selectively expose a region corresponding to the fine wire formation position of the grid 2, that is, a fine linear region having a pitch of 140 nm. Then, a latent image of the fine wire is formed (FIG. 8A). As a light source used for laser interference exposure, a continuous wave DUV (Deep Ultra Violet) laser having a wavelength of 266 nm can be used, and the incident angle θ _L can be set to 72 degrees, for example. At this time, since the antireflection film 32 is formed in the lower layer of the resist 34, it is possible to prevent a problem that the laser beam is reflected by the aluminum film 2L and the exposure is incomplete. Here, since the first region 4a and the second region 4b of the diffraction function layer 4 are parallel to each other, the laser light can be simultaneously incident on these regions at an equal angle. Therefore, even on the diffractive functional layer 4 having irregularities, it is possible to uniformly irradiate laser light with substantially equal power density, and in the subsequent steps, the pattern and grid of the resist 34 with high shape and dimensional accuracy. 2 can be formed. In addition, the resist 34 has a slight film thickness variation due to the unevenness of the diffraction function layer 4, but the depth of the unevenness, that is, the height g of the stepped portion 8 is as extremely small as about 100 nm to 200 nm. There is almost no problem with the pattern shape due to the film thickness variation. For this reason, a latent image similar to the case where a resist is formed on a flat surface can be formed.

  Next, in step S6, the resist 34 subjected to laser interference exposure is developed. As a result, a fine linear resist 34 pattern having a pitch of 140 nm is obtained (FIG. 8B).

  Next, in step S7, the aluminum film 2L is etched. More specifically, the antireflection film 32 and the aluminum film 2L are patterned by performing dry etching using the pattern of the resist 34 as a mask. In the subsequent step S8, the resist 34 and the antireflection film 32 are removed. As a result, the grid 2 made of fine wires arranged at a pitch of 140 nm is formed on the diffraction function layer 4 (FIG. 8C).

If SiO ₂ (thickness 30 nm) is formed between the aluminum film 2L and the antireflection film 32, the etching selectivity with respect to the aluminum film 2L is improved as compared with the case of the resist 34. The pattern can be made shallower. Thereby, a more stable pattern of the resist 34 can be formed.

Next, in step S <b> 9, the sealing layer 3 is formed on the grid 2. This step is performed, for example, by forming a layer made of SiO ₂ or SiN on the grid 2 in a vacuum environment by a CVD (Chemical Vapor Deposition) method, a vacuum deposition method, or the like. As a result, the space surrounded by the diffraction function layer 4, the grid 2, and the sealing layer 3 can be sealed in a vacuum state (FIG. 2B).

  Through the above steps, the optical element 1 having the diffraction function layer 4 and the grid 2 can be manufactured. According to this manufacturing method, since the irregularities on the surface of the diffraction function layer 4 are rectangular, the grid 2 can be more reliably formed on the surface of the diffraction function layer 4. In the present embodiment, the aluminum film 2L is used as the conductor film, but other metal materials such as silver and nickel can also be used. Moreover, although the polymer was used as the raw material of the diffraction function layer 4, the grid 2 can also be formed with the said manufacturing method on the diffraction function layer 4 formed, for example on the quartz glass substrate by the photolithographic method. Here, as a photolithography method, for example, a step of applying a resist on the diffraction functional material layer 4L, a step of developing after exposing the resist through a photomask, and a step of developing the diffraction functional material layer 4L using the remaining resist as a mask. Can be performed by a step of etching and a step of removing the resist.

(C. Liquid crystal device)
Next, an example in which the optical element 1 is applied to a liquid crystal device will be described. 10A and 10B show a transflective liquid crystal device 10, in which FIG. 10A is a perspective view and FIG. 10B is a cross-sectional view taken along line AA in FIG. The liquid crystal device 10 includes an element substrate 21 and a counter substrate 11 which are bonded to each other with a frame-shaped sealant 41 therebetween. A liquid crystal 40 is sealed in a space surrounded by the element substrate 21, the counter substrate 11, and the sealant 41. The element substrate 21 is larger than the counter substrate 11 and is bonded in a state where a part of the element substrate 21 protrudes from the counter substrate 11. A driver IC 42 for driving the liquid crystal 40 is mounted on the protruding portion. The liquid crystal device 10 performs display in the display area 43 in which the liquid crystal 40 is sealed.

  FIG. 11 is an enlarged plan view of the display area 43. As shown in this figure, the liquid crystal device 10 has a large number of rectangular pixels 44R, 44G, and 44B corresponding to red, green, and blue (hereinafter, simply referred to as pixels 44 when colors are not distinguished). Yes. The pixels 44 are arranged in a matrix, and all the colors of the pixels 44 arranged in a certain column are the same. In other words, the pixels 44 are arranged so that corresponding colors are arranged in a stripe pattern. A set of three adjacent pixels 44R, 44G, and 44B arranged in the row direction is the minimum unit (pixel) for display. The liquid crystal device 10 can display various colors by adjusting the luminance balance of the pixels 44R, 44G, and 44B in each pixel.

  Each pixel 44 has a transmissive display portion 44t and a reflective display portion 44r. A light shielding layer (black mask) 14 is disposed between adjacent pixels 44. The light shielding layer 14 serves to improve the display contrast by blocking light leaking from between the pixels 44.

  Next, a detailed configuration of the pixel 44 will be described with reference to FIG. FIG. 12 is a schematic cross-sectional view showing a state when the liquid crystal device 10 is cut along the column direction at a certain pixel 44.

  The element substrate 21 is configured with a glass substrate 22 as a first substrate as a base, and the counter substrate 11 is configured with a glass substrate 12 as a second substrate as a base. A TFT (Thin Film Transistor) element 23 is formed on the surface of the glass substrate 22 facing the glass substrate 12. More specifically, a gate electrode 23g, a gate insulating film 24, and a semiconductor layer 23a are stacked in this order on the glass substrate 22, and a source electrode 23s is provided in the source region of the semiconductor layer 23a, and a drain region is provided in the drain region. Is formed with the drain electrode 23d partially overlapping. The source electrode 23s is connected to a data line (not shown). The TFT layer 23 is configured by the semiconductor layer 23a, the source electrode 23s, the drain electrode 23d, the gate electrode 23g, and the like.

On the TFT element 23, an interlayer insulating film 26 made of SiO ₂ or SiN is formed. The interlayer insulating film 26 may be further multilayered as necessary. On the interlayer insulating film 26, the diffraction function layer 4 made of a polymer is laminated. The diffraction function layer 4 has irregularities formed on the surface only in the reflective display portion 44r, and a grid 2 made of fine aluminum wires is further formed on the irregularities. That is, on the interlayer insulating film 26, the optical element 1 including the diffraction function layer 4 and the grid 2 is formed only in the reflective display portion 44r.

  On the optical element 1 in the reflective display portion 44r and the diffraction function layer 4 in the transmissive display portion 44t, a pixel electrode 25 made of light-transmitting ITO is formed. The pixel electrode 25 is electrically connected to the drain electrode 23 d of the TFT element 23 through a contact hole provided through the grid 2, the diffraction function layer 4, and the interlayer insulating film 26. Since the refractive index of ITO is around 2, according to the above formula g = λ / (4n · cos θ), the height g of the stepped portion 8 of the diffraction function layer 4 is compared with the case where the surrounding medium is air. Can be made smaller. An alignment film (not shown) is formed on the pixel electrode 25. The element substrate 21 is composed of components from the glass substrate 22 to the alignment film.

  On the other hand, the color filter 13 is formed on the surface of the glass substrate 12 that is the base of the counter substrate 11 that faces the element substrate 21. The color filter 13 can change the transmitted light to a predetermined color (for example, red, green, or blue) by absorbing light having a specific wavelength in the incident light. A light shielding layer 14 made of black resin having a light shielding property is formed in a region between adjacent pixels 44. On the color filter 13, an overcoat 15 made of a resin having translucency is formed.

  On the overcoat 15, a common electrode 16 made of ITO is formed. An alignment film (not shown) is formed on the common electrode 16. The counter substrate 11 is configured by components from the glass substrate 12 to the alignment film.

  A TN mode liquid crystal 40 is disposed between the element substrate 21 and the counter substrate 11. The liquid crystal 40 changes the alignment direction according to the magnitude of the drive voltage applied between the pixel electrode 25 and the common electrode 16, and changes the polarization state of the transmitted light according to the alignment direction. Further, polarizing plates 47 and 46 are attached to the outside of the element substrate 21 and the counter substrate 11, respectively. FIG. 13 is a diagram illustrating the directions of the optical axes of the polarizing plates 47 and 46 and the optical element 1. In FIG. 13, the arrows attached to the polarizing plates 47 and 46 indicate the transmission axis, and the arrow attached to the optical element 1 indicates the extending direction of the fine wires of the grid 2. As described above, the polarizing plates 47 and 46 are arranged so that the transmission axes are orthogonal to each other, and the transmission axis of the polarizing plate 47 is arranged so as to be parallel to the extending direction of the fine wire of the optical element 1. Yes. A backlight 45 as an illumination device is disposed at a position facing the polarizing plate 47. The liquid crystal device 10 is a device that performs display using the polarization selection function of the polarizing plates 47 and 46 and the polarization conversion function of the liquid crystal 40.

  Here, the display principle of the liquid crystal device 10 will be described with reference to FIGS. 12 and 13. First, in the case of reflective display, external light (incident light 80) incident on the reflective display unit 44r from the counter substrate 11 side passes through the color filter 13 and the liquid crystal 40 and enters the optical element 1. Here, when the liquid crystal 40 is in the OFF state, the linearly polarized light transmitted through the polarizing plate 46 is converted into linearly polarized light orthogonal to the liquid crystal 40 by the optical rotation. Since the converted linearly polarized light is parallel to the extending direction of the fine wire, it is reflected by the optical element 1, converted again to the original linearly polarized light by the liquid crystal 40, and transmitted through the polarizing plate 46. That is, when the liquid crystal 40 is in the OFF state, a bright display is performed. At this time, since the reflected light is diffused by the diffraction function of the diffraction function layer 4, a high-quality reflection display can be performed in a wide range of viewing angles. On the other hand, when the liquid crystal 40 is in the ON state, the linearly polarized light that has passed through the polarizing plate 46 passes through the liquid crystal 40 without undergoing polarization conversion and enters the optical element 1. Since this linearly polarized light is perpendicular to the extending direction of the fine wire, it passes through the optical element 1 and is absorbed by the polarizing plate 47. That is, when the liquid crystal 40 is in the ON state, light is not reflected on the viewer side and dark display is performed.

  Next, at the time of transmissive display, incident light 81 incident on the transmissive display unit 44 t from the backlight 45 passes through the element substrate 21 and enters the liquid crystal 40. Note that the grid 2 is not formed in the transmissive display portion 44t. That is, the optical element 1 in FIG. 13 does not exist in the transmissive display unit 44t. Here, when the liquid crystal 40 is in the OFF state, the linearly polarized light transmitted through the polarizing plate 47 is converted into linearly polarized light orthogonal to the polarized light by the optical rotation of the liquid crystal 40 and is transmitted through the polarizing plate 46 to the observer. Visible. That is, when the liquid crystal 40 is in the OFF state, a bright display is performed. On the other hand, when the liquid crystal 40 is in the ON state, the linearly polarized light transmitted through the polarizing plate 47 is transmitted by the liquid crystal 40 without undergoing polarization conversion and is absorbed by the polarizing plate 46. That is, when the liquid crystal 40 is in the ON state, light is not transmitted to the viewer side and dark display is performed.

  Incidentally, the incident light 81 from the backlight 45 enters not only the transmissive display portion 44t but also the reflective display portion 44r. In the incident light 81, a component having a polarization axis parallel to the fine wire is reflected and diffused by the optical element 1. This light is reflected upward by the reflecting plate included in the backlight 45 and enters the element substrate 21 again. At this time, due to the diffusion by the optical element 1, a part of the light enters the transmissive display portion 44t and contributes to the transmissive display. Thus, the utilization efficiency of the backlight 45 can be improved by arrange | positioning the optical element 1 in the reflective display part 44r. Thereby, the light quantity of the backlight 45 can be saved, and power consumption can be reduced by extension.

  When the optical element 1 is applied to the liquid crystal device 10 capable of color display, as shown in FIG. 14, the unevenness depth of the diffraction function layer 4 is changed according to the display color of the pixels 44R, 44G, and 44B. May be. It is preferable that the depth of the unevenness of the diffraction function layer 4, that is, the height g of the stepped portion 8 satisfy the formula g = λ / (4n · cos θ) as described above. Here, θ is an angle formed between the observer's line of sight and the normal line of the display surface of the liquid crystal device 10, and for example, when the angle is set to about 25 degrees, the display is easily visually recognized. In the above formula, by setting the wavelength λ to the center wavelength of red, green, and blue light, for example, 650 nm, 550 nm, and 450 nm, the preferable value of height g is g (R) = 179 nm in the pixel 44R. For 44G, g (G) = 152 nm, and for the pixel 44B, g (B) = 124 nm. The optical element 1 having such a configuration has the diffraction function layer 4 suitable for the wavelength of incident light in each pixel 44, and can diffuse light more efficiently.

  Since the liquid crystal device 10 having the above-described configuration includes the optical element 1 on the inner surface of the opposing substrate, the liquid crystal device 10 can be thinned and has high quality display without parallax due to the thickness of the substrate. It can be performed. Further, the depth of the unevenness of the diffraction function layer 4 included in the optical element 1, that is, the height g of the stepped portion 8 is as extremely small as about 100 nm to 200 nm, and the surface of these unevenness (that is, the first region 4a and Since the second region 4b) is parallel to the glass substrate 22, the influence on the alignment state of the liquid crystal 40 can be suppressed. Thereby, display quality can be further improved.

(D. Manufacturing method of liquid crystal device)
Next, a method for manufacturing the liquid crystal device 10 will be described with reference to FIGS. FIG. 15 is a flowchart showing a method for manufacturing the liquid crystal device 10. FIG. 16 is a flowchart showing details of the manufacturing process of the optical element 1, and FIG. 17 is a cross-sectional view in the manufacturing process of the optical element 1. In FIG. 15, steps P <b> 11 to P <b> 13 are steps for manufacturing the element substrate 21, and steps P <b> 21 and P <b> 22 are steps for manufacturing the counter substrate 11. Process P31 to process P33 are processes for manufacturing the liquid crystal device 10 by combining the element substrate 21 and the counter substrate 11. Process P11 to process P13, process P21, and process P22 are performed independently.

  First, in step P11, a circuit element layer including the TFT element 23, various wirings, the interlayer insulating film 26, and the like is formed on the glass substrate 22. Next, in Step P12, the optical element 1 is formed on the reflective display portion 44r on the interlayer insulating film 26. This process P12 further includes processes S1 to S9 shown in FIG. Hereinafter, step P12 will be described in detail with reference to FIG.

  Steps S1 to S5 are the same as the manufacturing method of the optical element 1 described in FIG. That is, after the diffraction function layer 4 is formed in step S1, the aluminum film 2L, the antireflection film 32, and the resist 34 are sequentially formed in steps S2 to S4. Thereafter, in step S5, laser interference exposure is performed to form a latent image of a fine wire pattern (FIG. 17A).

  Next, in step S51, only the resist 34 arranged in the transmissive display portion 44t is selectively exposed (FIG. 17B). For example, exposure is performed with only the reflective display portion 44r hidden by a mask. When performing exposure using a mask, an imaging projection exposure method is desirable. This is because in the case of the proximity exposure method, a region where a pattern is not formed may occur due to diffraction of light at the edge of the mask opening.

  Thereafter, the resist 34 is developed in step S6. At this time, all of the resist 34 disposed in the transmissive display portion 44t is removed, and a fine linear resist 34 pattern with a pitch of 140 nm remains in the reflective display portion 44r (FIG. 17C).

  Subsequently, in step S7, the aluminum film 2L is etched. More specifically, the antireflection film 32 and the aluminum film 2L are patterned by performing dry etching using the pattern of the resist 34 as a mask. In the subsequent step S8, the resist 34 and the antireflection film 32 are removed. Through these steps, the grid 2 made of fine wires arranged at a pitch of 140 nm can be formed only on the reflective display portion 44r on the diffraction function layer 4 (FIG. 17D).

  Next, in process S9, the sealing layer 3 is formed on the grid 2, and the manufacturing process (process P12) of the optical element 1 is complete | finished. In the above, the order of step S5 and step S51 may be interchanged. That is, first, the entire transmissive display portion 44t may be exposed, and then laser interference exposure may be performed to form a latent image of a fine wire.

  Returning to FIG. 15, in step P13, the pixel electrode 25 is formed on the optical element 1 in the reflective display portion 44r and on the diffraction function layer 4 in the transmissive display portion 44t. In addition, although application of an alignment film and a rubbing process are performed following process P13, illustration was abbreviate | omitted. The element substrate 21 is completed through the process P11 to the process P13.

  On the other hand, in step P21, the color filter 13, the light shielding layer 14, and the overcoat 15 are formed on the glass substrate 12. This step is performed using a spin coating method, a photolithography method, or the like.

  Next, in step P22, the common electrode 16 is formed by being laminated on the overcoat 15. In addition, although application of an alignment film and a rubbing process are performed following process P22, illustration was abbreviate | omitted. The counter substrate 11 is completed through the processes P21 and P22.

  In step P31, the element substrate 21 and the counter substrate 11 are bonded together. The bonding is performed by applying a sealing agent 41 (FIG. 10) to the element substrate 21 or the counter substrate 11, performing alignment (positioning), and then contacting and pressing the element substrate 21 and the counter substrate 11.

  In Step P32, the liquid crystal 40 is injected between the element substrate 21 and the counter substrate 11 from the opening (injection port) of the sealant 41, and the injection port is sealed.

  In step P33, polarizing plates 47 and 46 are attached to the outside of the element substrate 21 and the counter substrate 11, respectively. Thereafter, the backlight 45 is appropriately attached, and the liquid crystal device 10 is completed.

  The above is a manufacturing method in which the liquid crystal 40 is injected after bonding, but instead, the liquid crystal 40 is dropped onto the element substrate 21 or the counter substrate 11 before bonding, and then both substrates are bonded together. It can also be manufactured.

(E. Electronic equipment)
The liquid crystal device 10 described above can be used by being mounted on, for example, a mobile phone 100 as an electronic apparatus as shown in FIG. The mobile phone 100 has a display unit 110 and operation buttons 120. The display unit 110 can perform high-quality display of various information including information input by the operation buttons 120 and incoming call information by the liquid crystal device 10 incorporated therein.

  The liquid crystal device 10 can be used in various electronic devices such as a mobile computer, a digital camera, a digital video camera, an in-vehicle device, and an audio device in addition to the mobile phone 100 described above.

(Modification 1)
In the said embodiment, the shape of the 1st area | region 4a and the 2nd area | region 4b of the diffraction function layer 4 shall be a square or the shape which connected the square, and the fine wire contained in the grid 2 is 1 side of the said square. However, various other configurations can be used. FIG. 18 shows the relationship between the minimum unit shape (hereinafter referred to as “unit shape”) of the first region 4 a and the second region 4 b of the diffraction function layer 4 and the extending direction of the fine wires included in the grid 2. It is a figure which shows the example of.

  In the configuration of FIG. 18A, the unit shape is a square, and the angle between the side of the square and the extending direction of the fine wires of the grid 2 is 45 degrees. According to such a configuration, the linear boundary of the unit shape and the fine wire are not parallel. Therefore, a fine wire is not formed along the step portion 8 of the diffraction function layer 4. For this reason, the malfunction that the fine wire arrange | positioned in the vicinity of the level | step-difference part 8 becomes unstable can be avoided.

  In FIGS. 18B and 18C, the unit shapes are circular and elliptical, respectively. In such a configuration, the fine wires of the grid 2 are arranged with a certain angle with respect to the boundary of the unit shape, so that the fine wires can be stably formed as in FIG. Can do.

  If the unit shape is circular, an isotropic reflected light intensity distribution can be realized. On the other hand, if the unit shape is provided with anisotropy, for example, a rectangle or an ellipse, the shape of the reflected light intensity distribution can be provided with anisotropy. In that case, the spread of the distribution is large in the direction where the width of the unit shape is narrow, and the spread of the distribution is narrowed in the direction where the width of the unit shape is wide.

(Modification 2)
The liquid crystal device 10 of the above embodiment is a transflective liquid crystal device including the optical element 1 in a part of the pixel 44. However, the present invention is not limited to this. For example, the optical element 1 is disposed on the entire pixel 44. A reflective liquid crystal device may be provided.

(Modification 3)
In the above embodiment, the pixels 44 of the liquid crystal device 10 have red, green, and blue pixels 44R, 44G, and 44B arranged in a stripe pattern, but instead of this, the pixel 44 has a delta arrangement as shown in FIG. May be. In this arrangement, the pixels 44R, 44G, and 44B are arranged so that the pixels 44R, 44G, and 44B are always included one by one, regardless of how the three pixels 44 that are adjacent in a triangular shape are selected. Yes. Even with the liquid crystal device 10 having such a configuration, high-quality display using the optical element 1 can be performed.

(Modification 4)
In the above embodiment, an example in which the optical element 1 is applied to the liquid crystal device 10 is shown. However, the liquid crystal device 10 is one of many application examples of the optical element 1. In addition, for example, the present invention can be applied to a liquid crystal projector that requires a polarizing element having excellent light resistance.

(Modification 5)
The liquid crystal device 10 of the above embodiment is of a normally white mode that performs bright display when the liquid crystal 40 is in an OFF state, but by appropriately changing the optical axes of the polarizing plates 46 and 47 and the optical element 1, A normally black mode device that performs dark display when the liquid crystal 40 is in an OFF state may be used.

(Modification 6)
The mode of the liquid crystal 40 included in the liquid crystal device 10 of the above embodiment is not limited to the TN mode, but is IPS (In Plain Switching), FFS (Fringe Field Switching), VA (Vertical Alignment), STN (Super Twisted Nematic). ) And the like can be employed. Among these modes, IPS, FFS, and VA, which can obtain a wide viewing angle, are preferable when using the diffusion characteristics of the optical element 1. If the liquid crystal 40 is set to a mode in which a wide viewing angle can be obtained, an image viewed at a viewing angle inclined from the front can be displayed with high brightness and high quality.

(A) is a perspective view of the optical element which concerns on this embodiment, (b) is a perspective view which shows the shape of a diffraction function layer. (A) is sectional drawing along XZ plane of the optical element of Fig.1 (a), (b) is sectional drawing to which a part of (a) was expanded. The schematic diagram for demonstrating the function of an optical element. (A) is a graph which shows the diffusion characteristic of an optical element, (b) is a figure which shows the measurement conditions. The figure which shows the example of arrangement | positioning of the unit pattern in an optical element. The flowchart of the manufacturing method of an optical element. (A) to (c) are cross-sectional views in the manufacturing process of the optical element. (A) to (c) are cross-sectional views in the manufacturing process of the optical element. (A), (b) is a graph which shows the relationship between the thickness of an antireflection film at the time of laminating | stacking a resist on an antireflection film, and the reflected light intensity in the interface of a resist and an antireflection film. 2A and 2B show a transflective liquid crystal device, in which FIG. 1A is a perspective view and FIG. 2B is a cross-sectional view taken along line AA in FIG. The enlarged plan view of a display area. FIG. 3 is a schematic cross-sectional view illustrating a state when a liquid crystal device is cut along a column direction in a certain pixel. The figure which shows the direction of the optical axis of a polarizing plate and an optical element. Sectional drawing which shows the optical element which changed the unevenness | corrugation depth of the diffraction function layer according to the display color. 6 is a flowchart showing a method for manufacturing a liquid crystal device. The flowchart which shows the detail of the manufacturing process of an optical element. (A) to (c) are cross-sectional views in the manufacturing process of the optical element. The figure which shows the example of the relationship between the shape of the minimum unit of the 1st area | region of a diffraction function layer, and a 2nd area | region, and the extending direction of the fine wire contained in a grid. The figure which shows arrangement | positioning of the pixel of the liquid crystal device in a modification. The perspective view of the mobile telephone as an electronic device. Sectional drawing which shows the manufacturing process of the conventional optical element.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical element, 1u ... Unit pattern, 2 ... Grid, 2L ... Aluminum film, 3 ... Sealing layer, 4 ... Diffraction functional layer, 4L ... Diffraction functional material layer, 4a ... 1st area | region, 4b ... 2nd Area 6, substrate 8, stepped portion 10 liquid crystal device 11 counter substrate 12 glass substrate as second substrate 13 color filter 14 light shielding layer 15 overcoat 16 common Electrode, 21 ... Element substrate, 22 ... Glass substrate as first substrate, 23 ... TFT element, 24 ... Gate insulating film, 25 ... Pixel electrode, 26 ... Interlayer insulating film, 32 ... Antireflection film, 34 ... Resist, DESCRIPTION OF SYMBOLS 40 ... Liquid crystal, 41 ... Sealing agent, 43 ... Display area, 44, 44R, 44G, 44B ... Pixel, 44r ... Reflection display part, 44t ... Transmission display part, 45 ... Backlight as an illuminating device, 46, 47 ... Polarization Plate, 100 ... with electronic equipment Mobile phone of Te.

Claims (12)

A first substrate and a second substrate disposed opposite to each other;
A liquid crystal disposed between the first substrate and the second substrate;
A liquid crystal device comprising a plurality of pixels having a transmissive display portion and a reflective display portion,
In between the first substrate the liquid crystal includes a diffraction function layer, a plurality of fine wires disposed on one surface of the diffraction function layer, and
The one surface is composed of a plurality of regions,
In one pixel of the plurality of pixels, a height of the first region of the plurality of regions from the other surface of the diffraction function layer on the opposite side of the one surface is the plurality of regions. Unlike the height of the second region from the other surface,
The reflective display unit is provided with the first region, the second region, and the plurality of fine wires,
The transmissive display unit is not provided with the first region, the second region, and the plurality of fine wires,
Before SL liquid crystal device characterized by stepped portion at a boundary between the first region and the front Stories second region is provided. The liquid crystal device according to claim 1, wherein the pre-SL is the first realm and the previous SL second realm and the mutually parallel planes. 3. The liquid crystal device according to claim 1, wherein each of the plurality of first regions is irregularly arranged on the one surface. 3. The liquid crystal device according to claim 1 , wherein the one surface has a plurality of unit patterns in which each of the plurality of first regions is arranged in an irregular distribution. The liquid crystal device according to claim 4, wherein the directions of the adjacent unit patterns are different from each other. Before SL periphery and before Symbol outer periphery of the second realm of the first region includes a straight line,
The fine wire, the liquid crystal device according to any one of claims 1 to 5, characterized in that it is arranged with a certain angle with respect to the straight line. When the wavelength of the incident light is λ, the incident angle is θ, and the refractive index of the surrounding medium of the optical element is n,
The height of the step portion, lambda / liquid crystal device according to any one of claims 1 to 6, characterized in that approximately equal to (4n · cosθ). The diffraction function layer, together with a different material from the fine wires, the liquid crystal device according to any one of claims 1 to 7, characterized in that a light-transmitting. Wherein between the diffraction function layer and the fine wire, one and are adhesion layer formed of different materials also show the diffraction function layer and the fine wire,
The adhesion strength between the diffraction function layer and the adhesion layer and the adhesion strength between the fine wire and the adhesion layer are higher than the adhesion strength between the diffraction function layer and the fine wire. The liquid crystal device according to claim 8. The plurality of pixels include a pixel corresponding to the first color and a pixel corresponding to the second color;
The height of the stepped portion in the pixel corresponding to the first color is different from the height of the stepped portion in the pixel corresponding to the second color . The liquid crystal device according to one item . 11. The lighting device according to claim 1, further comprising: an illumination device that irradiates light to the first substrate, the light source being disposed on the opposite side of the first substrate from the second substrate . The liquid crystal device according to one item . An electronic apparatus comprising the liquid crystal device according to any one of claims 1 to 11 mounted on a display portion.

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