JP3724216B2 - Reflective light modulation element and projection display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reflection-type light modulation element and a projection display device that projects and displays a display image formed using the reflection light modulation element on a screen.
[0002]
[Prior art]
A single-plate projection display device (a so-called projector) configured by using one light modulation element capable of color display has a simple optical configuration, and thus can be reduced in size, weight, and cost. It is easy to realize.
[0003]
As a light modulation element used in the single-plate projection display apparatus, a color light separation type reflection light modulation element which does not use a color filter as disclosed in Japanese Patent Application Laid-Open No. 8-240868 has attracted attention. FIGS. 9A and 9B show an example of an optical configuration of a projection display device configured using this type of color light separation type reflection type light modulation element (hereinafter simply referred to as a reflection type light modulation element). A brief description will be given.
[0004]
The reflective light modulation element 700 includes a transparent first electrode 130 provided on the light incident side, and three types of reflective pixel electrodes 701R corresponding to three types of color light (red light, green light, and blue light). A pixel unit 702 composed of 701G and 701B is used as a basic repeating unit, and a second electrode 140 is formed by arranging the pixel units 702 in a planar shape, and a light modulation layer (liquid crystal layer) sandwiched between the electrodes. 150, and a condensing unit 110 and a deflecting unit 120 for introducing three kinds of color lights into each corresponding reflective pixel electrode portion in the pixel unit.
[0005]
The illumination light emitted from the light source unit 410 is first separated into three types of color light (red light, green light, and blue light) having different traveling directions by a dichroic mirror (color light separation means) 420, and then a polarization beam splitter (polarized light). One type of polarized light (for example, S-polarized light) is generated by the separation unit 440 and is incident on the first lens array (condensing unit) 110. Here, the first microlenses 111 constituting the first lens array correspond to the arrangement of the pixel units, that is, one first microlens 111 has three types of reflective pixel electrodes 701R and 701G in the pixel unit. , 701B, and the illumination light incident on the first microlens 111 reaches the second lens array 120 while being condensed at spatially different positions for each color light. Therefore, when the illumination light passes through the first microlens 111, color light corresponding to the three types of reflective pixel electrodes and spatially separated is formed. After that, the traveling direction of these colored lights is bent by the second minute lens 121 constituting the second lens array (deflecting means) 120 according to the incident position on the second minute lens 121, and the main light of each colored light. The light enters the liquid crystal layer 150 that is a light modulation layer in a state where the direction of the light beam is substantially perpendicular to the reflection surfaces of the reflective pixel electrodes 701R, 701G, and 701B. The incident illumination light undergoes modulation (changes the polarization state) while reciprocating through the liquid crystal layer 150, and at the same time, is reflected by the reflecting surface and traces substantially the same path as that at the time of incidence to the polarization beam splitter 440 again. Incident light (hereinafter, such light is referred to as return light). The polarization beam splitter 440 transmits only specific polarized light (for example, P-polarized light) out of the modulated color lights and guides it to the projection lens. The projection lens 470 projects and displays the color image formed on the reflective light modulation element on a screen (not shown).
[0006]
In such a reflection-type light modulation element, illumination light composed of three kinds of color lights whose incident directions to the light modulation element are separated in advance are incident on the corresponding pixels of the light modulation element while being spatially separated. Because it modulates colored light, it can form a color image without significant light loss compared to a light modulation element configured using a conventional color filter, and the light modulation element is a reflection type. Since the pixel (reflecting surface) that modulates light and the circuit element that applies a predetermined voltage to the pixel portion can be three-dimensionally arranged in the thickness direction of the light modulating element, the pixels are arranged on a plane. There is a feature that it is possible to realize a high density of the battery relatively easily. Accordingly, a bright and high-definition color image can be realized relatively easily with this type of reflective light modulation element.
[0007]
[Problems to be solved by the invention]
However, the reflection type light modulation element as described above has the disadvantage that the color expression is inferior and the range of colors that can be expressed becomes narrow. This point will be described with reference to FIG. Since the behavior of blue light and red light is basically the same, FIG. 10 will be described with attention paid to blue light and green light.
[0008]
The illumination light emitted from the light source unit 410 is divergent light or focused light having a certain angular distribution, and is not so-called perfect parallel light. Therefore, each color light condensed by the first and second lens arrays forms a condensed image 760 having a certain finite size, and the size of the condensed image 760 is the size of the illumination light emitted from the light source unit. The larger the parallelism is, the larger it becomes. In addition, since it is necessary to dispose at least the first electrode 130 and the light modulation layer 150 between the second lens array 120 and the second electrode 140, the reflective pixel electrode that is the second electrode 140. 701R, 701G, and 701B are arranged at locations away from the second lens array 120.
[0009]
Accordingly, since each color light collected by the first lens array 110 enters the second lens array 120 in a state where the light beam diameter is not sufficiently narrowed, red, green, Each color light of blue cannot be completely introduced only to the corresponding pixel, and as shown by the oblique line in FIG. 10, a part of the blue light that should originally reach the reflective pixel electrode 701B for blue light A phenomenon occurs in which 770 enters the adjacent red pixel electrode 711R for red light. The blue light incident on the red-light reflective pixel electrode 711R is unnecessary light for the red-light reflective pixel electrode 711R, and as a result, color mixing and color bleeding occur between adjacent pixels. In the entire reflection type light modulation element, the color expression is lowered and the range of colors that can be expressed is narrowed. On the other hand, since the reflective pixel electrode 701G for green light is disposed at the substantially central portion of the pixel unit 702, the green light incident substantially perpendicularly to the reflective light modulation element forms a condensed image with a small size. It is easy and there is very little mixing of the unnecessary light to the adjacent pixel which arises with the above-mentioned blue light (or red light).
[0010]
In view of the above points, an object of the present invention is to realize a reflective light modulation element that is excellent in color expression and can express a wide range of colors by reducing unnecessary light incident on adjacent pixels. Accordingly, it is an object of the present invention to realize a projection display device capable of projecting and displaying a bright and high-quality color image by using such a reflective light modulation element.
[0011]
[Means for Solving the Problems]
(Explanation of the principle to solve the problem)
First, an optical relationship between an image projected and displayed on a screen and an image formed on the reflective light modulation element in a projection display device using the reflective light modulation element will be described. Here, a reflection type light modulation element using a lens array is assumed as the light collecting means and the deflecting means.
[0012]
Illumination light composed of three types of color light of red, green, and blue in which the directions of chief rays are separated in advance is converted into color light that is spatially separated by the first microlenses of the first lens array that is a condensing means. After the conversion, the light is reflected by each reflective pixel electrode corresponding to the three kinds of color light, becomes return light (reflected light), returns to the first microlens at the same position where the illumination light is incident, It is synthesized into one projection light and guided onto the screen. Here, the image projected and displayed on the screen through the projection lens is not an image of the reflective pixel electrode corresponding to the three types of color light, but the three types of return light (reflected light) are again combined into one. This is nothing but the image (the image formed by the distribution of color and brightness) of the first microlens (and its vicinity) of the first lens array. From this, it can be said that the size and shape of the reflective pixel electrodes on which the respective color lights are incident are not necessarily set to be the same among the three types of pixel electrodes. That is, even if the dimensional shape of each pixel electrode is different among the three types of pixel electrodes, the difference in dimensional shape itself does not directly affect the projected image. It can be said that the mixing of unnecessary color light and the resulting non-uniformity in the balance of the quantity of return light between the color lights directly affects the projected image.
[0013]
Therefore, each color light condensed by the first lens array and bent in the direction of the principal ray by the second lens array is incident only on the corresponding reflective pixel electrode, and is reflected there and reflected by the first lens array. The size and shape of the reflective pixel electrode and its arrangement are set according to the condensing state and condensing position of each color light so that the amount of return light returning to the microlens is equal between the three types of reflective pixel electrodes. If a reflection type light modulation element optimized in the way is configured, a bright projected image with excellent color expression can be realized.
[0014]
(Means for solving the problems and their actions and effects)
In order to solve the above-described problems, a first reflective light modulation element according to the present invention includes a transparent first electrode provided on a light incident side and a first electrode provided opposite to the first electrode. A plurality of reflective pixel electrodes for different colors of color light are used as a pixel unit, and the pixel unit is provided between the first electrode and the second electrode arranged in a matrix in a predetermined order. A light modulating layer disposed on the first electrode side, and a condensing unit that condenses each of the incident lights of the plurality of color lights having different incident directions and guides them to the corresponding reflective pixel electrode, A substantially normal direction of the reflective pixel electrode, which is disposed between the condensing means and the first pixel electrode, and corresponds to the emission direction of the principal rays of each of the plurality of color lights incident from the condensing means The plurality of colors having incident directions separated in advance. In the reflection type light modulation element using the light as illumination light, the dimension shape of at least one reflection type pixel electrode of the plurality of reflection type pixel electrodes constituting the pixel unit is different from the dimension shape of the other reflection type pixel electrode. It is characterized by being different.
[0015]
According to the configuration of the first reflective light modulation element, the light is reflected according to the size (light beam diameter) of the condensed image of each color light collected by the condensing means and the condensing position thereof. Since the size of the reflective pixel electrode to be set can be set, each color light can be efficiently guided only to the corresponding specific reflective pixel electrode. Therefore, unnecessary light incident on the adjacent reflective pixel electrode can be reduced. As a result, a bright display image with excellent color expression can be realized. As the light condensing means and the deflecting means, a lens array, a diffraction element, a hologram element, or the like configured by arranging micro lenses in an array can be used.
[0016]
The second reflective light modulation element according to the present invention is for a transparent first electrode provided on a light incident side and a plurality of different color lights provided opposite to the first electrode. A plurality of reflective pixel electrodes as a pixel unit, a second electrode in which the pixel units are arranged in a matrix in a predetermined order, and a light modulation layer provided between the first and second electrodes, A condensing unit that is disposed on the first electrode side and condenses each of the incident light beams of the plurality of colors having different incident directions, and guides the incident light to the corresponding reflective pixel electrode; the condensing unit; A deflecting unit disposed between the pixel electrode and directing an emission direction of each principal ray of the plurality of color lights incident from the light collecting unit in a substantially normal direction of the corresponding reflective pixel electrode; The color light of the plurality of colors having incident directions separated in advance is used as illumination light In the reflective light modulation element, the three reflective pixel electrodes constituting the pixel unit are arranged in the vicinity of a substantially central part of the pixel unit, and the reflective pixel electrode is arranged in the vicinity of a boundary part with the adjacent pixel unit. It is characterized by not having a configuration.
[0017]
Assuming that the condensing means of the reflective light modulation element is configured by a lens array configured by arranging a plurality of microlenses in a matrix, the light incident on the vicinity of the boundary between adjacent pixel units is assumed. A part of the light is reflected by the reflective pixel electrode and then enters another microlens that is different from the microlens that has passed at the time of incidence. In particular, in the vicinity of the boundary between the pixel units, the reflective pixel electrode for red light and the reflective pixel electrode for blue light are arranged adjacent to each other so as to sandwich the boundary between the pixel units. When unnecessary color light is incident on the adjacent reflective pixel electrode in the arrangement state of the type pixel electrode, the wavelength of the color light is significantly different, which greatly affects the color expression. Even in such an arrangement state of the reflection type pixel electrode, if the configuration of the second reflection type light modulation element is employed, the reflection type pixel electrode is not arranged near the boundary between the pixel units. The light incident on this area is not effectively reflected, and the light returning to the lens array (condensing means) is extremely reduced. As a result, unnecessary light incident on the adjacent reflective pixel electrode can be reduced, and a bright display image with excellent color expression can be realized. The configuration of the reflective pixel electrode is also effective when a diffraction element or a hologram element is used as the light collecting means.
[0018]
Here, the arrangement configuration of the reflection type pixel electrode employed in the first reflection type light modulation element according to the present invention and the reflection type pixel electrode employed in the second reflection type light modulation element according to the present invention. These arrangement configurations may be used in combination. That is, in the second reflective light modulation element according to the present invention, the pixel unit includes three reflective pixel electrodes, and at least one of the three reflective pixel electrodes has a dimensional shape. This is characterized in that the size and shape of other reflective pixel electrodes are different.
[0019]
By adopting such a configuration, unnecessary light incident on the adjacent reflective pixel electrode can be further reduced, so that a bright display image with excellent color expression can be realized.
[0020]
Furthermore, in the direction orthogonal to the direction in which the color lights are separated, the same type of reflective pixel electrodes corresponding to the same color light are arranged in a line, so that between the reflective pixel electrodes arranged in this direction, Since most of the light incident on the adjacent reflective pixel electrodes is the same color light, even if such light is incident on the adjacent reflective pixel electrodes, the influence on the color expression is small. Accordingly, in the second reflective light modulation element according to the present invention, the reflective pixel electrode is arranged in the vicinity of the boundary between adjacent pixel units in the direction in which the reflective pixel electrodes in the pixel unit are arranged. In addition, in the direction orthogonal to the direction in which the reflection type pixel electrodes in the pixel unit are arranged, it is desirable that the reflection type pixel electrode is also arranged near the boundary between adjacent pixel units. . By adopting such a configuration, the reflective pixel electrodes having the largest possible size can be arranged in the direction orthogonal to the direction in which the reflective pixel electrodes in the pixel unit are arranged. The amount of light can be increased, and a bright display image can be realized. Of course, it is possible to effectively suppress the phenomenon in which unnecessary light that greatly affects the color expression is incident on the adjacent reflective pixel electrode, so that the color expression is hardly deteriorated.
[0021]
In the first and second reflective light modulation elements, the reflective pixel electrode located in the center of the plurality of reflective pixel electrodes constituting the pixel unit is reflected in the pixel unit. It is possible to adopt a configuration in which the dimension in the direction in which the type pixel electrodes are arranged is set smaller than that of the other reflection type pixel electrodes. Since the color light incident on the reflective pixel electrode disposed in the center of the pixel unit is light whose traveling direction is hardly bent by the deflecting means, generally, it is easy to form a condensed image with a small size. . On the other hand, since the color light incident on the reflection type pixel electrodes arranged on both sides of the pixel unit is light whose traveling direction is bent by the deflecting means, it is not easy to form a condensed image with a small size. Therefore, by adopting the above configuration, it is possible to increase the size of the reflective pixel electrodes arranged on both sides of the pixel unit, so that unnecessary light that greatly affects the color expression is incident on the adjacent reflective pixel electrodes. While suppressing this phenomenon, the amount of reflected color light can be increased, and a bright display image with excellent color expression can be realized. When a reflective pixel electrode for green light is arranged at a substantially central portion of the pixel unit and reflective pixel electrodes for red light and blue light are arranged on both sides thereof, a condensed image formed by the condensing means. If the size of the reflective pixel electrode for red light is set to the largest and the size of the reflective pixel electrode for green light is set to the smallest, considering that the size of It is more effective for improvement.
[0022]
A first projection display device according to the present invention includes the reflective light modulation element, a light source unit that emits substantially parallel light, and light from the light source unit into a plurality of color lights having different wavelength ranges. And separating each of the three color lights from the color light separation means into two kinds of polarized lights having different polarization states, and separating the one polarization state. A polarization separation unit that causes the light beams of the plurality of colors to enter the reflective light modulation element, and a projection unit that projects the light modulated by the reflective light modulation element onto a screen. .
[0023]
Alternatively, a second projection display device according to the present invention includes a light source unit that emits a substantially parallel light beam, and a polarization separation unit that separates light from the light source unit into two types of polarized light having different polarization states, Colored light separating means for separating one of the polarized lights from the polarized light separating means into color lights of different colors having different wavelength ranges and separating the traveling directions of the respective colored lights, and the reflective light And projection means for projecting the light beam modulated by the modulation element onto a screen.
[0024]
Since the first and second projection display apparatuses according to the present invention are configured using the reflection type light modulation element, a bright and high-quality color image excellent in color expression is projected and displayed. can do. Here, according to the configuration adopted in the first projection display device, since only the polarization separation means is mainly disposed between the reflection type light modulation element and the projection means, the reflection type light modulation element. Can be set relatively short, and as a result, a bright projected image can be displayed. On the other hand, according to the configuration employed in the second projection display device, since the light having a relatively small divergence angle can be incident on the polarization separation means, the polarization separation performance of the polarization separation means depends on the incident angle. As a result, a projected image with a high contrast ratio can be displayed. If the color light separating means arranged between the reflection type light modulation element and the projection means is composed of a glass prism having a high refractive index, the distance between the reflection type light modulation element and the projection means can be set shorter. Therefore, it is possible to realize a projection display device that can display a brighter projected image with high light utilization efficiency.
[0025]
Further, in the first and second projection display devices, a light separation unit having both functions of the color light separation unit and the polarization separation unit is used instead of the color light separation unit and the polarization separation unit. Can do. Even in such a case, since the distance between the reflective light modulation element and the projection means can be set shorter, it is possible to realize a projection display device that can display a brighter projection image with high light utilization efficiency.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, unless otherwise specified, three directions orthogonal to each other are defined as an X direction, a Y direction, and a Z direction.
[0027]
(First embodiment)
FIG. 1A is a partial cross-sectional view schematically showing a configuration of a color light separation type reflection type light modulation element used in the first embodiment of the present invention, and FIG. FIG. 6 is an arrangement diagram schematically showing a planar arrangement state of reflection type pixel electrodes formed in a light modulation element.
[0028]
As shown in FIG. 1A, the reflective light modulation element 100 is mainly composed of a first lens array 110 as a condensing unit and a second lens array 120 as a deflecting unit in order from the light incident side. A transparent electrode 130 as a first electrode and a plurality of reflective pixel electrodes 140 as second electrodes, and a light modulation layer is provided between the transparent electrode 130 and the reflective pixel electrode 140. A certain liquid crystal layer 150 is formed. The first lens array 110 is formed by a plurality of first microlenses 111, and the second lens array 120 is formed by a plurality of second microlenses 121, respectively, and there are three types for red light, green light, and blue light. Each of the first microlens 111 and the second microlens 121 corresponds to one pixel unit 149 including the reflective pixel electrodes 140R, 140G, and 140B. The first lens array 110 has a function of condensing each of the red light 160R, the green light 160G, and the blue light 160B incident on the first lens array at different angles, and the second lens array 120 includes: It has a function (deflection action) for changing the direction of the principal ray of the light beam passing through the second lens array. In this example, the pixel unit 149 has the red and blue reflective pixel electrodes 140R and 140B disposed at both ends, but the present invention is not limited to this.
[0029]
The light beams of red light 160R, green light 160G, and blue light 160B incident on the reflective light modulation element 100 at different angles are respectively collected by the first microlenses 111 constituting the first lens array 110, and reflected light modulation. The light is incident on different positions on the second microlens 121 constituting the second lens array 120 according to the difference in the incident angle to the element. Here, since the red light 160R and the blue light 160B are colored light incident with a certain angle (θR> 0, θB> 0, θG = 0) with respect to the normal of the incident surface of the reflective light modulation element, Due to the deflection action of the second lens array 120, the direction of each principal ray is bent so as to substantially coincide with the direction of the normal line of the liquid crystal layer 150, and the red light 160R and the blue light 160B are incident on the liquid crystal layer 150 substantially perpendicularly. Then, the light is reflected by the corresponding red-light and blue-light reflective pixel electrodes 140R and 140B, respectively. On the other hand, the green light 160G incident substantially perpendicularly to the reflective light modulation element is substantially perpendicularly incident on the liquid crystal layer 150 without receiving the deflecting action of the second microlens 121, and is a reflective pixel electrode for green light. Reflected at 140G. The color light incident on the liquid crystal layer 150 is modulated in accordance with an external image signal (not shown) while reciprocating through the liquid crystal layer. The colored light reflected by the reflective pixel electrode passes through the optical path substantially the same as the incident optical path, that is, the traveling direction of the red light 160R and the blue light 160B is bent again by the second minute lens 121, On the other hand, the green light 160 </ b> G is emitted from the reflective light modulation element 100 with the second micro lens 121 being hardly bent in the traveling direction.
[0030]
Next, a planar arrangement state of the reflective pixel electrode 140 will be described with reference to FIG. As shown in FIG. 1B, the reflective pixel electrode 140 of this example is not exactly the same in size and shape among the three types of reflective pixel electrodes, depending on the condensing state of the three types of colored light. The reflective pixel electrodes have different dimensions. That is, the dimensions of the reflective pixel electrode in the direction in which the incident direction of the color light is separated (X direction) are smaller in the order of red light, blue light, and green light (DR>DB> DG), while the incident color light The dimensions (DY) of the reflective pixel electrodes in the direction in which the directions are not separated (Y direction) are set to be the same.
[0031]
If the size and shape of the three types of reflective pixel electrodes are set in this way, and each color light is incident on the substantially central portion of the corresponding reflective pixel electrode, the condensed state of the color light is taken into consideration. Since the dimensions of the reflective pixel electrode and the location in the pixel unit are set, it is possible to reduce the color light incident on the adjacent reflective pixel electrode as unnecessary light. In addition, it is possible to suppress a phenomenon in which return light (light reflected by the reflective pixel electrode) is incident on another second microlens different from the second microlens that has passed at the time of incidence.
[0032]
Also, red light and blue light that pass through the periphery of the second microlens are more susceptible to the influence of the second microlens than green light that passes through the center of the second microlens. For example, when the molding accuracy of the second microlens is poor, colored light is condensed at a position shifted from the corresponding reflective pixel electrode, or the size of the condensed image is increased, but such a phenomenon has occurred. Even in this case, in the reflective light modulation element 100 of this example, since three types of reflective pixel electrodes are set as described above, it is possible to reduce the color light incident as unnecessary light on the adjacent reflective pixel electrodes. Can do.
[0033]
Further, since the substance forming the lens generally has a wavelength dependency on its refractive index and the like, the size of the condensed image changes according to the wavelength of the colored light, and the light that is bent by the second microlens. The angle also changes depending on the wavelength of light. In particular, in consideration of the light diffraction phenomenon in the first and second microlenses, the size of the condensed image formed by the red light having a long wavelength is the concentration formed by the blue light and the green light having a shorter wavelength than the red light. Since it becomes larger than the size of the light image, it can be said that the color light that has the highest ratio of being incident as unnecessary light on the adjacent reflective pixel electrode is red light having a longer wavelength. However, in the reflective light modulation element 100 of this example, the three reflective pixel electrodes in the Y direction are the largest in the reflective pixel electrode for red light and the smallest in the reflective pixel electrode for green light. Therefore, it is possible to effectively reduce the color light incident as unnecessary light on the adjacent reflective pixel electrode.
[0034]
Accordingly, each color light incident on the reflection type light modulation element 100 is incident only on the corresponding reflection type pixel electrode, is reflected there, and is emitted from the reflection type light modulation element through the same optical path as the incident light. Therefore, it is possible to prevent color mixing, color bleeding, optical crosstalk between adjacent pixel units, and the like. As a result, it is possible to realize a reflective light modulation element that is excellent in color expression and can express a wide range of colors.
[0035]
In addition, since the phenomenon in which another color light unnecessary for the adjacent reflective pixel electrode is incident occurs more significantly as the parallelism of the light incident on the reflective light modulation element decreases, the reflective light modulation element of this example Can be said to be particularly effective when a light source that emits illumination light with poor parallelism is assumed.
[0036]
(Modification of the first embodiment)
In the first embodiment, the dimensions of the pixel electrodes of the reflective pixel electrodes 140R and 140B for red light and blue light are set to be different from each other. Since the difference in the size of the condensed light image of blue and blue light is slight, as shown in FIG. 2, the reflective pixel electrodes 141R and 141B for red light and blue light are set to have the same size and shape between them. You may do it. That is, among the three types of reflective pixel electrodes corresponding to the three types of color light, the size of the reflective pixel electrodes is only that of the reflective pixel electrode 141G for green light arranged in the middle of the pixel unit. The pixel unit is set to be smaller than the reflective pixel electrodes for other color lights arranged at both ends of the pixel unit (DR = DB> DG). By adopting such a configuration, it is possible to realize a reflection type light modulation element that is excellent in color expression as in the case of the first embodiment and can express a wide range of colors, and design and manufacture of the reflection type light modulation element. The feature is that it can be performed more easily.
[0037]
(Second embodiment)
Next, another embodiment will be described. FIG. 3A is a partial cross-sectional view schematically showing the configuration of a color light separation type reflection type light modulation element used in the second embodiment of the present invention, and FIG. FIG. 6 is an arrangement diagram schematically showing a planar arrangement state of reflection type pixel electrodes formed in a light modulation element. The reflection type light modulation element 200 has three types of reflection types for red light, green light and blue light when compared with the reflection type light modulation element 100 described with reference to FIGS. The dimension shape and arrangement method of the pixel electrode inside the pixel unit are different, and the other configurations are the same. Therefore, the same number is attached | subjected to the part which has the same function as the reflection type light modulation element 100 of 1st Example, and description is abbreviate | omitted about the overlapping part and its function.
[0038]
As shown in FIGS. 3A and 3B, in the reflective light modulation element 200, three types of reflective pixel electrodes 142R, 142G, and 142B for red light, green light, and blue light are connected to a pixel unit 149. The reflective pixel electrode is not disposed near the boundary 170 between the adjacent pixel units. The three types of reflective pixel electrodes 142R, 142G, 142B are all set to have the same size and shape.
[0039]
By disposing the three types of reflective pixel electrodes in this way, unnecessary light that enters the reflective pixel electrode of the adjacent pixel unit beyond the boundary between adjacent pixel units, or second light that is different from that at the time of incidence. Since unnecessary return light that returns to the first microlens through the microlens can be reduced, it is possible to realize a reflective light modulation element that is excellent in color expression and can express a wide range of colors.
[0040]
Here, since the light incident on the region where the reflective pixel electrode is not disposed, that is, near the boundary 170 between the adjacent pixel units is not subjected to the modulation action, the reflective light modulation is performed without changing the polarization state. The light is emitted from the element 200. Therefore, if the reflection type light modulation element is used in the normally black display mode, the light incident on the area where the reflection type pixel electrode is not arranged returns directly to the light source unit (not shown) side. Therefore, the display state is not adversely affected.
[0041]
(Modification of the second embodiment)
As in the case of the reflection type light modulation element 100 shown in the first embodiment, the light condensing property of each color light incident on three types of reflection type pixel electrodes for red light, green light and blue light is considered. In addition, the size of the three types of reflective pixel electrodes may be changed in the X direction. For example, as shown in FIG. 4, in consideration of the fact that the condensing characteristic of green light is superior to other red light and blue light, the dimension (DG) in the X direction of the reflective pixel electrode 143G for green light If the size (DR, DB) in the X direction of the other red- and blue-light reflective pixel electrodes 143R and 143B is increased, the incident light enters the adjacent reflective pixel electrode. Since unnecessary light can be further reduced, it is possible to realize a reflection type light modulation element that is further excellent in color expression and can express a wide range of colors. Of course, as in the first embodiment, the dimensions in the Y direction of the three types of reflective pixel electrodes may be set such that the pixel electrode for red light is the largest and the pixel electrode for green light is the smallest. It is obvious.
[0042]
(Third embodiment)
In the reflective light modulation element 200 shown in the second embodiment, three types of reflective pixel electrodes for red light, green light, and blue light are arranged near the center of the pixel unit, and the X direction and In both directions of the Y direction, the reflective pixel electrode is not disposed near the boundary between adjacent pixel units, but the direction (Y direction) orthogonal to the direction in which the incident direction of the colored light is separated (X direction) In this case, the possibility that unnecessary light is incident on adjacent pixels is relatively small, and therefore, the possibility that the color expression is affected is also relatively small. Another embodiment in consideration of this point will be described. FIG. 5A is a partial cross-sectional view schematically showing the configuration of a color light separation type reflection type light modulation element used in the third embodiment of the present invention, and FIG. FIG. 6 is an arrangement diagram schematically showing a planar arrangement state of reflection type pixel electrodes formed in a light modulation element. The reflection type light modulation element 300 has three types of reflection types for red light, green light, and blue light when compared with the reflection type light modulation element 200 described with reference to FIGS. The dimension shape and arrangement method of the pixel electrode in the pixel unit are different, and the other configurations are the same. Therefore, the same number is attached | subjected to the part which has the same function as the reflective optical modulation element 200 of 2nd Example, and description is abbreviate | omitted about the overlapping part and its function.
[0043]
As shown in FIGS. 5A and 5B, in the reflection type light modulation element 300, in the vicinity of the boundary portion 171 along the direction (X direction) in which the incident direction of the colored light is separated, the boundary line 173 is displayed. The reflective pixel electrodes 144R, 144G, and 144B are disposed so as to be substantially in contact with each other, and the reflective pixel electrode is not disposed in the vicinity of the boundary portion 172 along the Y direction. Therefore, the reflective pixel electrodes are arranged with almost no gap between the pixel units adjacent in the Y direction.
[0044]
By adopting such a configuration, the size of the reflective pixel electrode can be increased, so that the amount of reflected light in the reflective pixel electrode is increased and the light utilization efficiency is high while minimizing the effect on color expression. A reflective light modulation element can be realized.
[0045]
Also in this example, as described in the first embodiment, the condensing property of each color light incident on the three types of reflective pixel electrodes for red light, green light, and blue light is considered. In addition, the size of the three types of reflective pixel electrodes may be changed in the X direction.
[0046]
(Fourth embodiment)
Next, a projection display device configured using the reflection type light modulation element will be described. The projection display apparatus 400, whose outline of the optical configuration is shown in FIG. 6, mainly includes a light source unit 410 that emits a substantially parallel illumination light beam, a color light separation element 420, a polarization separation element 440, and the reflection described in the first embodiment. Type light modulation element 100 and a projection lens 470 that projects and displays a display image formed on the reflection type light modulation element 100 on a screen (not shown), and further includes a color light separation element 420 and a polarization separation element. Between the polarization separation element 440 and the projection lens 470, and between the polarization separation element 440 and the reflective light modulation element 100. A quarter wavelength plate 450 is disposed between them.
[0047]
The color light separation element 420 is composed of three dichroic mirrors, a blue light reflecting dichroic mirror 421, a green light reflecting dichroic mirror 422, and a red light reflecting dichroic mirror 423, and the reflecting surfaces are arranged in a non-parallel state. Accordingly, the substantially parallel illumination light beam emitted from the light source unit 410 is reflected by the three dichroic mirrors 421, 422, and 423 to be separated into blue light, green light, and red light having slightly different traveling directions. After passing through the side polarizing plate 430, it becomes almost one type of polarized light beam (S-polarized light beam in this example) and then enters the polarization separation element 440. In the case where an optical device capable of emitting one type of polarized light beam is used as the light source unit 410, or when the polarization separation performance of the polarization separation element 440 described later is excellent, the incident side polarization plate 430 may be omitted. good.
[0048]
The polarization separation element 440 has a function of spatially separating incident light into two types of polarized light beams according to the difference in polarization state, and sandwiches the polarization separation film 442 between the inclined surfaces of the two right-angle prisms 441. A polarizing beam splitter formed in this way can be used. Each color light (S-polarized light beam) separated into blue light, green light, and red light whose traveling directions are slightly different by the color light separation element 420 is reflected by the polarization separation film 442 of the polarization separation element 440, and is a quarter wavelength plate. After 450, the light enters the reflective light modulation element 100 with slightly different angles. As described in the first embodiment, the reflective light modulator 100 modulates light according to an image signal (not shown) from the outside and emits a reflected light beam including the image signal. That is, the S-polarized light beam incident on the reflective light modulation element 100 is subjected to rotation of the polarization plane for each reflective pixel electrode in accordance with an external image signal, and the modulated light beam is in a P-polarized state and modulated The light flux that has not been subjected to is emitted from the reflective light modulation element 100 in the S-polarized state.
[0049]
The emitted light beam from the reflection type light modulation element 100 is incident on the polarization separation element 440 again through the quarter wavelength plate 450. Here, the color light that has been modulated by the reflective light modulation element 100 and has been in the P-polarized state passes through the polarization separation film 442 of the polarization separation element 440 as it is, but remains unpolarized and remains in the S-polarization state. The color light is reflected by the polarization separation film 442 and returns to the color light separation element 420. The light beam that has passed through the polarization separation film 442 of the polarization separation element 440 is guided to the screen (not shown) by the projection lens 470 through the output side polarizing plate 460, and the first lens array 110 of the reflective light modulation element 100. The image formed on the screen is displayed as a projected image. The quarter-wave plate 450 is used to supplement the modulation performance of the reflective light modulation element 100, and the output side polarizing plate 460 is used to supplement the polarization separation performance of the polarization separation element 440. As in the case of the incident-side polarizing plate 430, this may be omitted when the modulation performance of the reflective light modulation device 100 or the polarization separation performance of the polarization separation device 440 is excellent.
[0050]
Since the reflection type light modulation element 100 described in the first embodiment is used in the projection display apparatus 400 configured in this way, color crosstalk and color blur between adjacent display pixels are used. In addition, it is possible to obtain a projected image with little color mixing and excellent color expression, and to express a wide range of colors. Furthermore, since only the polarization separation element 440 is mainly disposed between the reflection type light modulation element 100 and the projection lens 470, the distance between the reflection type light modulation element and the projection lens can be set relatively short, As a result, a bright projected image can be displayed. It is obvious that a high-performance projection display device can be realized in the same manner when the other reflection type light modulation elements described above are used instead of the reflection type light modulation element 100.
[0051]
(5th Example)
The above reflection type light modulation element can be applied to another projection type display apparatus in which the arrangement positions of the color light separation element 420 and the polarization separation element 440 are changed with respect to the projection type display apparatus 400 described in the fourth embodiment. Can be used. The optical configuration of the projection display apparatus 500 having such a configuration will be described with reference to FIG. Note that parts having the same functions as those of the projection display apparatus 400 of the fourth embodiment are denoted by the same reference numerals, and descriptions of the overlapping parts and their functions are omitted.
[0052]
As shown in FIG. 7, in the projection display apparatus 500, the substantially parallel illumination light beam emitted from the light source unit 410 passes through the incident-side polarizing plate 430 and travels in the polarization separation film 442 of the polarization separation element 440 in a traveling direction of about 90. The light is changed into an S-polarized light beam and enters the color light separation element 420. The illumination light beam (S-polarized light beam) incident on the color light separation element 420 is reflected by three dichroic mirrors 421, 422, and 423 arranged in non-parallel to each other, and thus the blue light whose traveling direction is slightly different. The light is separated into green light and red light, and enters the reflective light modulation element 100 through the quarter-wave plate 450. The reflective light modulation element 100 generates a reflected light beam including an image signal (not shown) from the outside, and the light beam is again emitted from the quarter-wave plate 450, the color light separation element 420, the polarization separation element 440, and the emission light. An image formed on the first lens array 110 of the reflective light modulation element 100 is displayed as a projection image through a side polarizing plate 460 and a projection lens 470 and guided onto a screen (not shown).
[0053]
In general, since the polarization separation performance of the polarization separation element 440 has a large angle dependency with respect to incident light, the light beam incident on the polarization separation element 440 is required to have high parallelism. On the other hand, in the projection display apparatus 500 configured as described above, the illumination light beam from the light source unit 410 and the reflected light beam from the color light separation element 420 are incident on the polarization separation element 440 in a substantially parallel state. Therefore, an excellent polarization separation performance can be exhibited, and as a result, a bright and high contrast projected image can be obtained. Of course, as in the case of the fourth embodiment, since the reflective light modulation device 100 of the present invention is used, there is little color crosstalk, color bleeding, and color mixing between adjacent display pixels, Projected images with excellent color expression can be realized.
[0054]
(Modification of the fourth and fifth embodiments)
The above reflection type light modulation element is also used for the projection display apparatus using the light separation means 480 having both functions of the color light separation element 420 and the polarization separation element 440 used in the fourth and fifth embodiments. I can do it. The optical configuration of the projection display apparatus 600 having such a configuration will be described with reference to FIG. Note that parts having the same functions as those of the projection display apparatus 400 of the fourth embodiment are denoted by the same reference numerals, and descriptions of the overlapping parts and their functions are omitted.
[0055]
As shown in FIG. 8, in the projection display apparatus 600, the substantially parallel illumination light beam emitted from the light source unit 410 enters the light separation element 480 through the incident side polarizing plate 430, and the polarization separation function and the color light separation function. Are reflected by the three polarization dichroic mirrors 481, 482, 483, and the traveling directions are slightly different, and each of them is separated into blue light, green light and red light in the S polarization state. The light enters the reflective light modulation element 100 through the four-wavelength plate 450. The reflective light modulation element 100 generates a reflected light beam including an image signal (not shown) from the outside, and the light beam is again emitted from the quarter wavelength plate 450, the light separation element 480, the output side polarizing plate 460, and the like. An image guided to a screen (not shown) through the projection lens 470 and formed on the first lens array 110 of the reflective light modulation element 100 is displayed as a projection image.
[0056]
In the projection display device 600 configured as described above, since the distance between the reflective light modulation element 100 and the projection lens 470 can be shortened, the light use efficiency in the optical system can be increased, and as a result, the brightness is further enhanced. A projected image can be obtained. Of course, as in the case of the fourth and fifth embodiments, since the reflective light modulation device 100 of the present invention is used, color crosstalk, color blur, and color mixing between adjacent display pixels are used. Therefore, it is possible to realize a projected image with less color expression.
[0057]
In each embodiment, the combination of red, green, and blue has been described as an example. However, the present invention is not limited to this, and any combination may be used as long as color display is performed by combining multiple meals of colored light. It can also be applied to combinations of colored lights.
[0058]
【The invention's effect】
As described above, according to the present invention, in the color light separation type reflection type light modulation element, the color light incident on the reflection type light modulation element is taken into consideration and the respective color lights are supported. Since the size and shape of the three types of reflective pixel electrodes and the manner in which they are arranged are set, each color light can be efficiently introduced only into the corresponding specific reflective pixel electrode. Therefore, unnecessary light incident on the adjacent reflective pixel electrode can be reduced, and as a result, a bright image with excellent color expression can be displayed. Further, by using such a reflection type light modulation element, it is possible to realize a projection display device that displays a projected image that is bright and excellent in color expression.
[Brief description of the drawings]
FIG. 1A is a partial cross-sectional view schematically showing a configuration of a reflective light modulation device according to a first embodiment of the present invention, and FIG. 1B shows a planar arrangement state of reflective pixel electrodes. It is the arrangement figure shown typically.
FIG. 2 is an arrangement diagram schematically showing a planar arrangement state of the reflection type pixel electrode in a reflection type light modulation element according to a modification of the first embodiment of the present invention.
FIG. 3A is a partial cross-sectional view schematically showing a configuration of a reflective light modulation element according to a second embodiment of the present invention, and FIG. 3B shows a planar arrangement state of reflective pixel electrodes. It is the arrangement figure shown typically.
FIG. 4 is an arrangement diagram schematically showing a planar arrangement state of reflection type pixel electrodes in a reflection type light modulation element according to a modification of the second embodiment of the present invention.
5A is a partial cross-sectional view schematically showing a configuration of a reflective light modulation element according to a third embodiment of the present invention, and FIG. 5B shows a planar arrangement state of reflective pixel electrodes. It is the arrangement figure shown typically.
FIG. 6 is a plan view schematically showing an optical configuration of a projection display apparatus according to a fourth embodiment of the present invention.
FIG. 7 is a plan view schematically showing an optical configuration of a projection display apparatus according to a fifth embodiment of the present invention.
FIG. 8 is a plan view schematically showing an optical configuration of a projection display apparatus according to a sixth embodiment of the present invention.
9A is a plan view schematically showing an optical configuration of a projection display device configured using a conventional reflection type light modulation element, and FIG. 9B is a configuration of a conventional reflection type light modulation element. It is the fragmentary sectional view which showed typically.
FIG. 10 is a diagram for explaining an optical problem that occurs in a conventional reflective light modulation element.
[Explanation of symbols]
100, 200, 300, 700... Reflection type light modulation element
110... First lens array (light collecting means)
111 ... 1st micro lens
120 ... second lens array (deflection means)
121 ... 2nd minute lens
130 ... Transparent electrode (first electrode)
140... Reflective pixel electrode (second electrode)
140B, 141B, 142B, 143B, 144B ... Reflective pixel electrodes for blue light
140G, 141G, 142G, 143G, 144G ... reflective pixel electrodes for green light
140R, 141R, 142R, 143R, 144R ... reflective pixel electrodes for red light
149 ... Pixel unit
150 ... Liquid crystal layer (light modulation layer)
160B ・ ・ Blue light
160G ・ ・ Green light
160R ... Red light
170 ... Boundary part
171 ... Boundary portion along the X direction
172 ... Boundary portion along the Y direction
173 ... Boundary line
400, 500, 600, 800... Projection display device
410 ... Light source unit
420 ... Color light separating element
421 ... Blue light reflecting dichroic mirror
422 ... Green light reflecting dichroic mirror
423 ... Red light reflecting dichroic mirror
430: Incident side polarizing plate
440: Polarized light separating element
441 ... Right angle prism
442 ... Polarized light separation film
450 ... 1/4 wavelength plate
460: Emission side polarizing plate
470 ... Projection lens
480 ... Light separation element
481 ... Blue light reflecting dichroic mirror
482 ... Green light reflecting dichroic mirror
483: Red light reflecting dichroic mirror
701B .. Reflective pixel electrode for blue light
701G ・ ・ Reflective pixel electrode for green light
701R .. Reflective pixel electrode for red light
702 ... Pixel unit
711R .. Adjacent red pixel electrode for red light
760 ... Condensed image
770: Part of blue light

Claims (8)

A transparent first electrode provided on the light incident side;
A plurality of reflective pixel electrodes for a plurality of different color lights provided facing the first electrode as a pixel unit, and a second electrode in which the pixel units are arranged in a matrix in a predetermined order;
A light modulation layer provided between the first and second electrodes;
A condensing unit that is disposed on the first electrode side and condenses each of the incident light beams of the plurality of colors having different incident directions, and guides the incident light to the corresponding reflective pixel electrode; the condensing unit; A deflecting unit disposed between the pixel electrode and directing an emission direction of each principal ray of the plurality of color lights incident from the light collecting unit in a substantially normal direction of the corresponding reflective pixel electrode; Have
In the reflective light modulation element using the color lights of the plurality of colors, the incident directions of which are separated in advance, as illumination light,
Of the plurality of reflective pixel electrodes constituting the pixel unit, the dimensional shape of at least one reflective pixel electrode is different from the dimensional shape of other reflective pixel electrodes,
Of the plurality of reflective pixel electrodes constituting the pixel unit, the size of the reflective pixel electrode located in the center in the direction in which the reflective pixel electrodes in the pixel unit are arranged is larger than that of the other reflective pixel electrodes. Is also small,
The reflection type light modulation element, wherein the reflection type pixel electrode is planar. A transparent first electrode provided on the light incident side;
A plurality of reflective pixel electrodes for a plurality of different color lights provided facing the first electrode as a pixel unit, and a second electrode in which the pixel units are arranged in a matrix in a predetermined order;
A light modulation layer provided between the first and second electrodes;
A condensing unit arranged on the first electrode side, condensing each of the incident lights of the plurality of colors of light having different incident directions, and guiding them to the corresponding reflective pixel electrode;
A substantially normal line of the reflective pixel electrode, which is disposed between the light condensing means and the first pixel electrode, and corresponds to the emission direction of each principal ray of the plurality of color lights incident from the light condensing means. Deflection means for directing in a direction,
In the reflective light modulation element using the color lights of the plurality of colors, the incident directions of which are separated in advance, as illumination light,
The three reflective pixel electrodes constituting the pixel unit are arranged in the vicinity of a substantially central part of the pixel unit, and the reflective pixel electrode is not arranged in the vicinity of a boundary part between adjacent pixel units,
In the direction in which the reflective pixel electrodes in the pixel unit are arranged, the reflective pixel electrodes are not arranged near the boundary between adjacent pixel units, and the reflective pixel electrodes in the pixel unit are arranged. In the direction orthogonal to the reflection type light modulation element, the reflection type pixel electrode is also arranged in the vicinity of a boundary portion between adjacent pixel units. In claim 2,
The pixel unit includes three reflective pixel electrodes, and among the three reflective pixel electrodes, at least one reflective pixel electrode has a dimensional shape different from that of other reflective pixel electrodes. Reflective light modulation element. In claim 2 or claim 3,
Of the plurality of reflective pixel electrodes constituting the pixel unit, the size of the reflective pixel electrode located in the center in the direction in which the reflective pixel electrodes in the pixel unit are arranged is larger than that of the other reflective pixel electrodes. Is a reflection type light modulation element characterized by being small.   5. The reflection type light modulation element according to claim 1, wherein dimensions in a direction in which the reflection type pixel electrodes in the pixel unit are arranged are small in order of red light, blue light, and green light. The reflection type light modulation element according to claim 1 or 2,
A light source that emits substantially parallel light;
Color light separating means for separating the light from the light source part into a plurality of color lights having different wavelength ranges and separating the traveling direction of each color light;
Polarized light that further separates each of the three color lights from the color light separating means into two types of polarized light having different polarization states, and makes the light beams of the plurality of colors having the one polarization state incident on the reflective light modulation element Separating means;
A projection display device comprising: projection means for projecting the light modulated by the reflective light modulation element onto a screen. The reflection type light modulation element according to claim 1 or 2,
A light source that emits a substantially parallel light beam;
Polarization separation means for separating light from the light source unit into two types of polarized light having different polarization states;
Colored light separating means for separating one of the polarized lights from the polarized light separating means into color lights of different colors having different wavelength ranges and separating the traveling directions of the colored lights,
A projection display device, comprising: a projection unit that projects a light beam modulated by the reflective light modulation element onto a screen. In claim 6 or claim 7,
A projection display device, wherein a light separation means having both functions of the color light separation means and the polarization separation means is used in place of the color light separation means and the polarization separation means.

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