JP2006139059A - Light modulator and projector using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light modulator capable of effectively utilizing light passing through a pixel or reflected thereby and getting along without using a projection lens of a large diameter, and to provide a projector made to be excellent in utilization efficiency of light and made to be compact by using the light modulator. <P>SOLUTION: By appropriately setting a difference of refractive index between microprism arrays 4, 5 and glass substrates 6, 7, shapes of them and a distance between the microprism arrays 4, 5, incident light ILa passing through a region DI is emitted to the outer part as emission light ELa from a region DI' altogether, thereby, the parallelism is maintained and, resultantly, the desired light modulator can be obtained. Further, by using the same, the projector which is excellent in utilization efficiency of light and is compact can be obtained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light modulation device having a microprism array and a projector using the same.

  A liquid crystal panel in the light modulation device incorporates a thin film transistor for switching liquid crystal in each pixel, and these are hidden by a so-called black matrix. However, since the light is blocked by the black matrix, there is a problem that the light cannot be used effectively.

In order to solve this problem, for example, a method of using a microlens array to collect light passing through pixels and increasing the amount of light is used (see Patent Document 1). Further, at this time, a method has been proposed in which microlens arrays are installed on both sides so as to sandwich a black matrix so that a projection lens having a large diameter is not required (see Patent Document 2). Also known is an aspherical lens shape (see Patent Documents 3, 4, 5, 6, etc.).
JP 2003-185803 A JP-A-6-75212 JP 2003-287603 A Japanese Patent Laid-Open No. 9-43588 JP-A-5-40216 JP 2003-262706 A

  However, the microlens array is affected by the spherical aberration of the lens, and there is a problem that the emitted light from the light modulation device is not completely collimated even if an aspherical lens is used.

  Therefore, the present invention provides a light modulation device that effectively uses light that passes through or is reflected by a pixel and that does not require use of a projection lens having a large diameter. An object of the present invention is to provide a compact projector with high utilization efficiency.

  In order to solve the above problems, an optical modulation device according to the present invention includes a pair of substrates each having an electrode formed thereon, a liquid crystal sandwiched between the pair of substrates, and an electrode formed on each of the pair of substrates. And a plurality of pixels including a liquid crystal sandwiched between a pair of electrodes, and a light shielding portion that shields the periphery of each of the plurality of pixels. Further, the pair of substrates has a prism array including a plurality of prisms, at least one of which is provided corresponding to the plurality of pixels. The prism has a bottom surface parallel to the substrate surface and a side surface constituted by a straight line, and the size of the cross section of the prism parallel to the substrate surface decreases as the distance from the bottom surface increases.

  Even if an aspherical lens or the like is used as the microlens array, it is difficult to form a parallel light beam due to the influence of the residual aberration of the lens, but the prism in the present invention is configured by a bottom surface parallel to the substrate surface and a straight line. Therefore, aberration due to the lens does not occur. Further, light can be effectively used by avoiding the light shielding portion by the prism.

  Here, the light shielding portion includes, for example, a so-called black matrix for hiding a thin film transistor or the like, but is not limited to the black matrix or the like, and as a result, for example, a partition for determining the shape of the pixel for pixel formation. It shows all things that block light.

  As a specific aspect of the present invention, one of the pair of substrates is an incident substrate that forms a light incident surface, and the other is an emission substrate that forms a light emission surface, Both emission substrates each have a prism array. In this case, the light modulation device is a light transmission type in which the light incident side and the reflection side face each other, and can form image light with high saturation.

  Further, as a specific aspect of the present invention, each prism has symmetry with respect to the center of the corresponding pixel, and the parallelism of incident light incident in parallel is maintained in a vertical section including the straight line. In this case, since the parallelism of light is reliably maintained, it is not necessary to use a projection lens having a large diameter when projecting image light formed by the light modulation device. Here, the vertical cross section refers to a cross section of the prism that includes the straight line and is perpendicular to the incident surface of the light modulation device.

  As a specific aspect of the present invention, incident light crosses symmetrically with respect to the center. In this case, the uniformity of the light can be maintained and the light amount can be prevented from being attenuated by the light shielding portion, and as a result, the light amount of the light passing through the pixel can be increased.

  As a specific aspect of the present invention, the prism includes at least part of either a cone shape or a column shape, and the bottom surface is formed according to the shape of a plurality of pixels. In this case, the amount of light can be efficiently secured because the bottom surface corresponds to the shape of the pixel. In addition, by including at least part of either the cone shape or the column shape, it is possible to increase the amount of light that passes through or is reflected by the pixel without causing spherical aberration or the like.

  As a specific aspect of the present invention, the prism includes at least a part of a conical shape. In this case, the light beam formed by the incident light has high symmetry.

  As a specific aspect of the present invention, a prism is sandwiched between a pair of end portions each having at least a part of a pair of cone portions obtained by dividing a cone shape into two along an axis, and the pair of cone portions. A plurality of pixels having a rectangular shape. In this case, both the end portion and the central portion increase the amount of light that passes through or is reflected by the pixel without causing aberration. In addition, the amount of light can be more efficiently ensured by designing the triangular columnar central portion in accordance with the shape of the rectangular pixel.

  Moreover, as a specific aspect of the present invention, the prism has a trapezoidal shape having a top portion chamfered in parallel to the bottom surface. In this case, the light passing through the top can reach the pixel without being refracted.

  In order to solve the above problems, a projector according to the present invention includes an illumination device that emits illumination light, a color separation optical system that color-separates illumination light for each predetermined wavelength, and any one of the plurality of light modulation devices, A color synthesis optical system that synthesizes image light of each color light formed by a plurality of light modulation devices, and a projection optical system that projects the image light synthesized by the color synthesis optical system. In this case, by using the light modulation device, it is possible to provide a compact projector by eliminating the need to use a projection lens with high light utilization efficiency and a large diameter.

[First Embodiment]
FIG. 1 is a cross-sectional view for explaining the light modulation device according to the first embodiment. The illustrated light modulation device 100 is a light transmission type light modulation device, and includes an incident substrate 1, an emission substrate 2, a display layer 3, microprism arrays 4 and 5, and glass substrates 6 and 7. Among these, the display layer 3 includes a liquid crystal pixel 8 and a black matrix portion 9.

  Both the incident substrate 1 and the emission substrate 2 are formed of a transparent glass plate, are arranged to face each other as a pair of substrates, and sandwich the display layer 3. The display layer 3 is a main part of a function as a so-called liquid crystal panel of an active matrix driving method by TFT (thin film transistor) driving. The display layer 3 includes a plurality of liquid crystal pixels 8 that include liquid crystal molecules and constitute a plurality of pixels, and a black matrix portion 9 that includes a drive circuit including a TFT and a black matrix that conceals these. Transparent electrodes are formed on the opposing surfaces of both substrates 1 and 2, whereby a predetermined voltage is applied to the display layer 3 on a pixel-by-pixel basis, and the liquid crystal molecules in the liquid crystal pixels 8 are controlled to form a display panel. To play a role. Here, the black matrix portion 9 that partitions the liquid crystal pixels 8 serves as a light shielding portion that blocks light around the pixels.

  The microprism arrays 4 and 5 are formed by two-dimensionally arranging conical prism-like prism-like members 4a and 5a (one unit is defined by a dotted line in the figure) corresponding to each liquid crystal pixel 8, and each of which is an incident substrate. 1 and the injection substrate 2.

  The shape of the microprism arrays 4 and 5 will be described with reference to FIG. FIG. 2 is a perspective view in which the conical portions (prisms) of the prism-like members 4a and 5a are taken out by cutting out the microprism arrays 4 and 5 along the AA arrow cross section of FIG. Conversely, the cross section in the BB direction of FIG. 2 corresponds to FIG. Here, the cone CN is a right cone, and the side surface is formed with a straight line as a generating line. In this case, the cross section of the cone CN parallel to the bottom surface BS of the cone CN decreases as the distance from the bottom surface BS increases. The bottom surface BS is arranged in parallel to the substrates 1 and 2 and is designed so that the center of the liquid crystal pixel 8 is on a straight line extending vertically from the vertex S of the cone CN to the bottom surface BS.

  Returning to FIG. 1, the glass substrates 6 and 7 respectively have a light incident surface and an emission surface in the light modulation device 100, and have shapes in which the irregularities of the microprism arrays 4 and 5 are reversed. The microprism arrays 4 and 5 are in close contact with each other.

  The contact portion is formed by, for example, bonding a resin adhesive between the incident substrate 1 and the glass substrate 6 and bonding them together, and forming an adhesive portion made of the resin adhesive as the microprism array 4. The injection substrate 2 and the glass substrate 7 are also formed by the same method as described above.

  Since the material of the microprism arrays 4 and 5 and the material of the glass substrates 6 and 7 have different refractive indexes, a refraction phenomenon occurs at the boundary between them. In the light modulation device 100 of FIG. 1, it is assumed that the refractive index of the microprism arrays 4 and 5 is larger than the refractive index of the glass substrates 6 and 7, and the refractive index is appropriately determined to transmit the light modulation device 100. Control the optical path of light. Here, it is assumed that the microprism array 4 and the microprism array 5 use the same material and have the same shape. The glass substrate 6 and the glass substrate 7 are also made of the same material and have the same shape. That is, in FIG. 1, these are geometrically symmetrical about the display layer 3.

  Hereinafter, formation of modulated light by the light modulation device 100 according to the present embodiment will be described with reference to FIG. 1 by tracing the optical path of each liquid crystal pixel 8. For this purpose, first, the optical path and the elements existing on the optical path are defined as follows.

  In FIG. 1, light incident on the light modulation device 100 that passes through the side surface SF of the cone CN1 in one prism-like member 4b in the microprism array 4 is defined as incident light IL. Of the incident light IL, on the side surface SF, the light passing through the region D1 on the right side of the drawing from the apex S1 of the cone CN1 is defined as the incident light ILa, and the light passing through the region D2 on the left side of the drawing is defined as the incident light ILb. Here, the incident light IL is parallel light at the time of incidence, and is assumed to be perpendicularly incident on the light modulation device 100. Among the liquid crystal pixels 8, a pixel corresponding to the cone CN1 is set as a target pixel 8a. One prism-like member in the microprism array 5 corresponding to the target pixel 8a is a prism-like member 5b, a cone in the prism-like member 5b is a cone CN1 ′, and a vertex is S1 ′. That is, the center of the target pixel 8a comes on a line connecting the vertex S1 and the vertex S1 '. Of the side surface SF ′ of the cone CN1 ′, a region on the left side of the drawing from the vertex S1 ′ is a region D1 ′, and a region on the right side of the drawing is a region D2 ′.

  Of the incident light IL, the incident light ILa is bent to the right in the traveling direction in the region D1. After refraction, the incident light ILa is bent leftward with respect to the traveling direction in the region D1 ′ of the prism-shaped member 5b through the incident substrate 1, the target pixel 8a, and the emission substrate 2 from the prism-shaped member 4b, and becomes the emitted light ELa.

  At this time, if the refractive index difference between the microprism array 4 and the glass substrate 6 and the respective shapes, and the distance between the microprism arrays 4 and 5 are set appropriately, if it goes straight without being refracted. Can transmit the ambient light blocked by the black matrix portion 9 into the target pixel 8a and prevent the central light from protruding outside the target pixel 8a. Furthermore, by designing the outermost light (right end of the drawing) of the incident light IL to reach the vertex S1 ′ of the cone CN1 ′, the region D1 and the region D1 ′ correspond to each other. That is, all the incident light ILa that passes through the region D1 is emitted to the outside as the emitted light ELa from the region D1 ′. On the other hand, similarly, due to symmetry, the incident light ILb passing through the region D2 is emitted to the outside as the emitted light ELb from the region D2 ′. The emitted light ELa and the emitted light ELb are combined to form an emitted light EL, which is emitted from the light modulation device 100 as modulated light.

  In the above, first, since the incident light IL is not shielded by the black matrix portion 9, the amount of light transmitted through the liquid crystal pixel 8 is increased. Further, due to the linearity of the side surface SF that intersects the incident section that is the vertical section and the side surface SF ′ that intersects the exit section that is the vertical section, the incident light ILa and the incident light ILb are kept parallel in the longitudinal section. The emitted light ELa and the emitted light ELb are emitted as they are. Therefore, spherical aberration that occurs when a lens is used does not occur. Furthermore, since the incident light ILa and the incident light ILb intersect symmetrically, the emission positions are switched. However, according to the above design, there is no region where the emission light ELa and the emission light ELb are superimposed and the incident light IL is not emitted. If it is uniform, the uniformity is maintained. Further, for the incident light ILa, ILb and the emitted light ELa, ELb, since the parallelism in the longitudinal section is maintained, the directions and shapes of the light beams of the incident light IL and the emitted light EL are the same. For example, when projecting the obtained modulated light as image light, it is not necessary to use a projection lens having a large diameter.

  FIG. 3 is a diagram for explaining a modification of the microprism arrays 4 and 5 in FIG. FIG. 3 is a perspective view in which the protruding portions (prisms) of the respective prism-like members 4a and 5a are taken out by cutting out the microprism arrays 4 and 5 along the AA arrow section of FIG. 1 as in FIG. Conversely, the cross section in the BB direction of FIG. 3 corresponds to FIG. The protrusion PR is composed of a pair of cone portions CP1 and CP2 obtained by dividing a right cone into two along an axis, and a central portion TP that is a triangular prism sandwiched between the pair of cone portions CP1 and CP2. In this case, the bottom surface CS of the protrusion PR has a track shape including one rectangle and two semicircles. In the cone CN of FIG. 2, the bottom surface BS is a circle, which is suitable when the shape of the corresponding liquid crystal pixel 8 is a square or the like. In contrast, in this modification, the shape of the liquid crystal pixel 8 is a rectangle or the like. Suitable for. In particular, by appropriately adjusting the size of the central portion TP in accordance with the ratio of the sides of the rectangle, it is possible to design a protrusion PR having a bottom surface CS having an optimal shape for each prism-like member 4a, 5a.

[Second Embodiment]
FIG. 4 is a cross-sectional view for explaining the light modulation device according to the second embodiment. In the light modulation device 200 of the present embodiment, the components other than the shape of the microprism arrays 204 and 205 and the shape of the glass substrates 206 and 207 deformed accordingly are the same as those of the light modulation device 100 of FIG. So I will omit the explanation. In the prism-like members 204a and 205a forming the microprism arrays 204 and 205 in this embodiment, the protrusion PP corresponding to the cone CN or the like of the prism-like members 4a and 5a in FIG. It is a trapezoid in which the top portion SS is formed by chamfering in parallel to the bottom surface BS. As in the case of the light modulation device 100, the microprism array 204 and the microprism array 205 have the same shape and the same material and have symmetry.

  Hereinafter, the formation of modulated light by the light modulation device 200 in the present embodiment will be described with reference to FIG. 4 by following the optical path of each liquid crystal pixel 8. As in the case of FIG. 1, first, the optical path and the elements existing on the optical path are defined as follows.

  In FIG. 4, incident light that enters the light modulation device 200 and that passes through the surface PF of the protrusion PP1 of one prism-like member 204b in the microprism array 204 is referred to as incident light IL. The surface PF includes the above-described top portion SS1, the right side surface RS that is the side region on the right side of the drawing from the top portion SS1, and the left side surface LS that is the side region on the left side of the drawing from the top portion SS1. Of the incident light IL, the light passing through the right side RS is defined as the incident light ILa, the light passing through the left side LS as the incident light ILb, and the light passing through the top SS1 as ILc. Here, the incident light IL is parallel light at the time of incidence, and is perpendicularly incident on the light modulation device 200. Among the liquid crystal pixels 8, a pixel corresponding to the protrusion PP1 is set as a target pixel 8a. One prism-like member in the microprism array 205 corresponding to the target pixel 8a is a prism-like member 205b, a protrusion on the prism-like member 205b is a protrusion PP1 ′, and a top is SS1 ′. The surface PF ′ of the protrusion PP1 ′ includes a top portion SS1 ′, a right side surface RS ′ that is a side surface region on the right side of the drawing from the top portion SS1 ′, and a left side surface LS ′ that is a side surface region on the left side of the drawing from the top portion SS1 ′. .

  Of the incident light IL, the incident light ILa is bent to the right with respect to the traveling direction on the right side surface RS. After the refraction, the incident light ILa is bent leftward with respect to the traveling direction in the region LS ′ of the prism-shaped member 205b from the prism-shaped member 204b through the incident substrate 1, the target pixel 8a, and the emission substrate 2, and becomes the emitted light ELa.

  At this time, if the refractive index difference between the microprism array 204 and the glass substrate 206, the respective shapes, and the distance between the microprism arrays 204 and 205 are set appropriately, if it goes straight without refraction. Can transmit the ambient light blocked by the black matrix portion 9 into the target pixel 8a and prevent the central light from protruding outside the target pixel 8a. By designing the outermost light (right end of the drawing) of the incident light ILa to reach the intersection of the top portion SS1 ′ and the left side surface LS ′, the right side surface RS and the left side surface LS ′ correspond to each other. That is, all the incident light ILa that passes through the right side surface RS is emitted to the outside as the emitted light ELa from the left side surface LS ′. On the other hand, similarly, due to symmetry, the incident light ILb passing through the left side LS is emitted to the outside as the emission light ELb from the right side RS ′.

  Since the incident light ILc is perpendicularly incident on the top portion SS1, it travels straight without being bent, and reaches the top portion SS1 ′ of the prism-like member 205b from the prism-like member 204b through the incident substrate 1, the target pixel 8a, and the emission substrate 2. The top portion SS1 ′ is also emitted to the outside as the emitted light ELc without being bent.

  As is clear from the above description, the emission light ELa, the emission light ELb, and the emission light ELc are combined to form the emission light EL, which is emitted from the light modulation device 200 as modulated light.

  Also in this embodiment, the amount of light transmitted through the liquid crystal pixel 8 is increased without the incident light IL being blocked by the black matrix portion 9. Further, the incident light ILa, the incident light ILb, and the incident light ILc are emitted as the emitted light ELa, the emitted light ELb, and the emitted light ELc, respectively, while maintaining parallelism in the longitudinal section. Therefore, spherical aberration that occurs when a lens is used does not occur. Furthermore, since the incident light ILa and the incident light ILb cross symmetrically, the emission positions are switched. However, the above design does not include a region where the emission light ELa, the emission light ELb, and the emission light ELc are superimposed and emitted. If the light IL is uniform, the uniformity is maintained. Further, the incident light ILa, the incident light ILb, and the incident light ILc, and the exit light ELa, the exit light ELb, and the exit light ELc are maintained in parallel in the longitudinal section, so that the directions of the incident light IL and the light beam are maintained. For example, when projecting the obtained modulated light as image light, it is not necessary to use a projection lens having a large diameter.

[Third Embodiment]
FIG. 5 is a cross-sectional view for explaining the light modulation device according to the third embodiment. In the embodiments so far, the refractive index of each microprism array and the glass substrate is assumed to be larger than the refractive index of the glass substrate in the present embodiment. Conversely, the case where the refractive index of the glass substrate is larger than the refractive index of the microprism array will be described. In FIG. 5, in the light modulation device 300 of the present embodiment, each component other than the shape of each of the microprism arrays 304 and 305 and the shape of the glass substrates 306 and 307 that are deformed accordingly is the first and second components. Since it is the same as that of the light modulation apparatuses 100 and 200 of embodiment, description is omitted. In the present embodiment, the glass substrates 306 and 307 have a shape corresponding to the cone CN and the like in FIGS. That is, when the glass substrates 306 and 307 are cut along the AA arrow cross section of FIG. 5, a perspective view as shown in FIG. 2 is obtained. In addition to this, for example, the portions where the glass substrates 306 and 307 are cut out may have the trapezoidal shape described in FIG. In particular, FIG. 5 shows a case where the glass substrates 306 and 307 are cut into right cones as shown in FIG. 2, and the prismatic members 304a and 305a forming the microprism arrays 304 and 305 are respectively right cones. The concave part PQ which is the shape of a mortar corresponding to is included. Similar to the embodiment in FIG. 1, the microprism arrays 304 and 305 are formed on the incident substrate 1 and the emission substrate 2 by arranging the prism-like members 304 a and 305 a two-dimensionally corresponding to the respective liquid crystal pixels 8. The bottom point Q of the recess PQ corresponds to the center of each pixel of the liquid crystal pixel 8 in the same manner as the vertex S of FIG. Note that the microprism array 304 and the microprism array 305 have the same shape and are made of the same material.

  Hereinafter, the formation of modulated light by the light modulation device 300 according to the present embodiment will be described with reference to FIG. 5 by tracing the optical path of each liquid crystal pixel 8. As in the case of FIGS. 1 and 4, first, the optical path and elements existing on the optical path are defined as follows.

  In FIG. 5, incident light that enters the light modulation device 300 and that passes through the side surface QF of the concave portion PQ1 in one prism-shaped member 304b in the microprism array 304 is defined as incident light IL. Of the incident light IL, in the side surface QF, the light passing through the region DD1 on the right side of the drawing from the bottom point Q1 of the recess PQ1 is set as the incident light ILa, and the light passing through the region DD2 on the left side of the drawing as the incident light ILb. Here, the incident light IL is parallel light at the time of incidence, and is perpendicularly incident on the light modulation device 300. Among the liquid crystal pixels 8, a pixel corresponding to the recess PQ1 is set as a target pixel 8a. One prism-like member in the microprism array 305 corresponding to the target pixel 8a is a prism-like member 305b, a concave portion in the prism-like member 305b is a concave portion PQ1 ', and a bottom point is Q1'. That is, the center of the pixel of interest 8a comes on a line connecting the bottom point Q1 and the bottom point Q1 '. Of the side surface QF ′ of the recess PQ1 ′, a region on the left side of the drawing from the bottom point Q1 ′ is a region DD1 ′, and a region on the right side of the drawing is a region DD2 ′.

  Of the incident light IL, the incident light ILa is bent to the right in the traveling direction in the region DD1. After refraction, the incident light ILa is bent leftward with respect to the traveling direction in the region DD1 ′ of the prism-shaped member 305b through the incident substrate 1, the target pixel 8a, and the emission substrate 2 from the prism-shaped member 304b, and becomes the emitted light ELa.

  At this time, if the refractive index difference between the microprism array 304 and the glass substrate 306, their respective shapes, and the distance between the microprism arrays 304 and 305 are set appropriately, if it goes straight without being refracted. Can transmit the ambient light blocked by the black matrix portion 9 into the target pixel 8a and prevent the center light from protruding outside the target pixel 8a. In the present embodiment, the region DD1 and the region DD1 ′ correspond to each other by designing the outermost light (right end in the drawing) of the incident light IL to reach the bottom point Q1 ′ of the recess PQ1 ′. That is, all the incident light ILa that passes through the region DD1 is emitted to the outside as the emitted light ELa from the region DD1 ′. On the other hand, similarly, due to symmetry, the incident light ILb passing through the region DD2 is emitted to the outside as the emitted light ELb from the region DD2 ′. The emitted light ELa and the emitted light ELb are combined to form an emitted light EL, which is emitted from the light modulation device 300 as modulated light. As described above, the same effect as that of the light modulation device 100 can be obtained.

  In all of the above, the structures of the light modulation devices 100, 200, and 300 in the first to third embodiments are geometrically and optically symmetric. However, the structure is not limited to this, and as a result, an optical path difference occurs. As long as the parallelism of the light can be maintained, the microprism arrays 4, 5, 204, 205, 304, and 305 may have different shapes and materials. Further, the material of the glass substrates 6, 7, 206, 207, 306, 307 is not limited to glass, and may be, for example, plastic or the like according to the required refractive index.

  Further, the outer shape of the cone CN in FIG. 2 as a prism can be changed as appropriate. For example, if the shape is a cone shape, the shape of the bottom surface of the prism may be, for example, a polygon or an ellipse other than a circle.

[Fourth Embodiment]
FIG. 6 is a diagram for explaining the projector according to the fourth embodiment. The projector 500 in this embodiment includes an illumination device 410, a color separation optical system 430, a light modulation device 400, a cross dichroic prism 470 that is a color synthesis optical system, and a projection lens 490 that is a projection optical system. Note that the light modulation device 400 in this embodiment uses a plurality of the light modulation devices 100, 200, and 300 shown in the first to third embodiments, and further includes a polarizer and the like to be described later. It is out.

  The illumination device 410 generates the light source light WL, and the illumination light SL, which is uniform polarized light, is formed from the light source light WL.

  The color separation optical system 430 includes dichroic mirrors 31, 32, mirrors 33, 34, 35, relay lenses 36, 37, and field lenses 38, 39, 40. Here, the dichroic mirrors 31 and 32 selectively separate or transmit the illumination light SL formed by the illumination device 410 to separate colors for each predetermined wavelength band, thereby forming colored light of each color. In particular, the dichroic mirror 31 has a characteristic of transmitting the components in the wavelength region including the red light RL while reflecting the other regions. Thereby, the red light RL is separated from the illumination light SL. The dichroic mirror 32 has a characteristic of reflecting the components in the wavelength region including the blue light BL while transmitting the other regions. Thereby, the blue light BL is separated from the remaining components of the illumination light SL, and the rest becomes the green light GL. The mirrors 33, 34, and 35 change the optical path of each color light in a predetermined direction by reflection. The relay lenses 36 and 37 correct the beam shape necessary for the optical path difference between the color lights, that is, the difference in the optical path length from the illumination device 410 to the liquid crystal light valves 51r, 51b, and 51g. The field lenses 38, 39, and 40 adjust the incident angle of each color light obtained by color separation of the illumination light to a polarizer that will be described later.

  The light modulation device 400 includes liquid crystal light valves 51r, 51b, and 51g, and each of the liquid crystal light valves 51r, 51b, and 51g includes a polarizer 52r, 52b, and 52g, and a liquid crystal panel 53r, 53b, and 53g, respectively. Photons 54r, 54b, and 54g. The polarizers 52r, 52b, and 52g are respectively positioned on the incident side of the liquid crystal panel on the optical path, and are used to increase the degree of polarization by limiting the polarization direction of the incident light to the liquid crystal panels 53r, 53b, and 53g to a narrower range. It is a polarizing plate. Each of the liquid crystal panels 53r, 53b, and 53g forms modulated light by adjusting each incident color light with respect to a polarization state in units of pixels in accordance with a drive signal or image signal input as an electrical signal. The analyzers 54r, 54b, and 54g are polarizing plates for selecting a polarization component in a specific direction from the modulated light emitted from the liquid crystal panels 53r, 53b, and 53g.

  Here, the liquid crystal panels 53g, 53r, and 53b are formed by any of the light modulation devices 100, 200, and 300 disclosed in the first to third embodiments. By appropriately setting the refractive index difference between each micro-prism array and the glass substrate, the respective shapes, and the distance between the micro-prism arrays according to the wavelength band of each color light incident on the liquid crystal panels 53g, 53r, 53b. The desired light modulation device 400 disclosed in the first to third embodiments can be formed.

  The cross dichroic prism 470 is a color combining optical system for combining image light obtained according to the modulated light emitted from the liquid crystal panels 53r, 53b, and 53g to form combined light.

  The projection lens 490 is a projection optical system for projecting the formed combined light as projection light onto a screen (not shown) or the like.

  Hereinafter, the function of the main image forming unit will be described with reference to FIG. First, in the color separation optical system 430, the wavelength band including the red light RL as a main component is first color-separated from the illumination light SL formed in the illumination device 410 by the first dichroic mirror 31. Next, the remaining components of the illumination light SL are color-separated by the second dichroic mirror 32 into a wavelength band including the blue light BL as a main component and a wavelength band including the green light GL as a main component. The illumination light SL is separated into red light RL, green light GL, and blue light BL for each wavelength band by the function of each dichroic mirror described above. The red light RL is reflected by the mirror 33, and the incident angle is adjusted by the field lens 38. The red light RL is guided to the liquid crystal light valve 51r of the light modulator 400 and irradiates the liquid crystal light valve 51r. Similarly, the blue light BL is extracted by reflection at the dichroic mirror 32, and then the incident angle is adjusted by the field lens 39, guided to the liquid crystal light valve 51b of the light modulation device 400, and irradiated to the liquid crystal light valve 51b. The green light GL is extracted by transmission through the dichroic mirror 32, and then reflected by the mirrors 34 and 35. Further, the incident angle is adjusted by the field lens 40 and guided to the liquid crystal light valve 51g of the light modulator 400, The liquid crystal light valve 51g is irradiated. In the color separation optical system 430, the optical path of the green light GL is physically longer than the optical paths of other lights. Therefore, it is necessary to correct the beam shape, and relay lenses 36, 37, etc. are provided in the optical path of the green light GL for such correction.

  Next, in the light modulation device 400, the color lights RL, BL, and GL of the respective colors irradiated to the respective liquid crystal light valves 51r, 51b, and 51g are firstly polarizers 52r and 52b in the respective liquid crystal light valves 51r, 51b, and 51g. , 52g, the polarization direction of the incident light to the liquid crystal panels 53r, 53b, 53g is limited to a narrower range, and the degree of polarization is increased. Of each color light having an increased degree of polarization, the red light RL, the blue light BL, and the green light GL are incident on the liquid crystal panels 53r, 53b, and 53g, respectively. In each color light RL, BL, GL modulated by the liquid crystal panels 53r, 53b, 53g, a polarization component in a specific direction is further selected by the analyzers 54r, 54b, 54g. As described above, the image light of each color light RL, BL, GL is formed by each liquid crystal light valve 51r, 51b, 51g.

  The image lights formed by the light modulation device 400 are combined with each other by the cross dichroic prism 470. The composite light thus formed is projected onto the screen or the like as projection light from the projection lens 490, and a color composite image having a desired enlargement ratio is displayed on the screen.

  By using any of the light modulation devices disclosed in the first to third embodiments in the light modulation device 400, the projector 500 in the present embodiment has good light utilization efficiency and does not use a projection lens having a large diameter. By compacting, it becomes compact.

[Fifth Embodiment]
FIG. 7 is a cross-sectional view for explaining the light modulation device according to the fifth embodiment. The light modulation devices in the first to third embodiments are all light transmission type light modulation devices, and the projector of the fourth embodiment using the light modulation device is also of a transmission type. On the other hand, the illustrated light modulation device 600 in the present embodiment is a light reflection type, and can be used for a reflection type projector.

  The light modulation device 600 includes an incident emission substrate 601, a reflective substrate 602, a display layer 603, a microprism array 604, and a glass substrate 606. In addition, about the point which does not demonstrate in detail about a component, it shall be equivalent to the thing of the same name in 1st Embodiment etc.

  Both the incident emission substrate 601 and the reflective substrate 602 are made of glass, are arranged to face each other as a pair of substrates, and sandwich the display layer 603. The display layer 603 is a main part of a function as a so-called liquid crystal panel, similar to the display layer 3 in the first embodiment. The display layer 603 includes a liquid crystal pixel 608 that includes liquid crystal molecules and forms a plurality of pixels, and a light-blocking portion 609 that partitions the liquid crystal pixels 608. Electrodes are formed on opposing surfaces of the substrates 601 and 602. A transparent electrode is applied to the incident / exit substrate 601 side, while a reflective electrode is applied to the reflective substrate 602 side. As a result, a predetermined voltage is applied to the display layer 603, and the liquid crystal molecules in the liquid crystal pixel 608 are controlled. At this time, since the light is reflected by the reflective electrode on the reflective substrate 602 side, it serves as a light reflective panel. Here, the light shielding portion 609 that partitions each liquid crystal pixel 608 is a portion that blocks light around the pixel.

  Similar to the prism-like member 4a of the first embodiment, the microprism array 604 is formed by two-dimensionally arranging prism-like members 604a including right cones corresponding to the respective liquid crystal pixels 608. Is formed.

  The glass substrate 606 forms a light incident / exit surface in the light modulation device 600 and has a shape in which the irregularities of the microprism array 604 are inverted, and is in close contact with the microprism array 604. The formation process is the same as in the first embodiment.

  Hereinafter, the formation of modulated light by the light modulation device 600 in this embodiment will be described by following the optical path of each liquid crystal pixel 608. For this purpose, first, the optical path and the elements existing on the optical path are defined as follows.

  In FIG. 7, incident light that enters the light modulation device 600 and passes through the side surface SF of the cone CN2 in one prism-like member 604b in the microprism array 604 is referred to as incident light IL. Of the incident light IL, on the side surface SF, the light passing through the region E1 on the right side of the drawing from the vertex S2 of the cone CN2 is incident light ILa (solid line in the drawing), and the light passing through the region E2 on the left side of the drawing is incident light ILb (see FIG. Middle broken line). Here, the incident light IL is parallel light at the time of incidence, and is assumed to be perpendicularly incident on the light modulation device 600. Among the liquid crystal pixels 608, a pixel corresponding to the cone CN2 is set as a target pixel 608a.

  Of the incident light IL, the incident light ILa is bent to the right in the traveling direction in the region E1. After the refraction, the incident light ILa is transmitted from the prism-like member 604b through the incident emission substrate 601 through the pixel of interest 8a, reflected by the reflection substrate 602, bent to the right in the traveling direction in the region E2, and emitted light ELa. Become.

  At this time, the refractive index difference between the microprism array 604 and the glass substrate 606, the respective shapes, and the distance between the microprism array 604 and the display layer 603 were set appropriately, so that the sample proceeded straight without being refracted. In this case, ambient light that is blocked by the light shielding portion 609 can be transmitted into the target pixel 608a, and the central light can be prevented from protruding outside the target pixel 608a. Further, when the outermost light (right end of the drawing) of the incident light ILa is emitted from the region E2 as the emitted light ELa, the region E1 and the region E2 correspond to each other by reaching the vertex S2 of the cone CN2. . That is, all the incident light ILa incident from the region E1 is emitted to the outside as the emitted light ELa from the region E2. On the contrary, due to symmetry, the incident light ILb passing through the region E2 is emitted to the outside as the emitted light ELb from the region E1. The emitted light ELa and the emitted light ELb are combined to form an emitted light EL, which is emitted from the light modulation device 600 as modulated light. As described above, it is possible to obtain a light reflection type light modulation device having the same effect as each light modulation device in the first embodiment.

  In FIG. 7, each prism may have the trapezoidal shape described in FIG. 4. FIG. 7 is an explanation of the refractive index of the microprism array and the glass substrate, in which the refractive index of the microprism array is larger than the refractive index of the glass substrate, but is the same as FIG. 5 in the third embodiment. Thus, it is possible to consider the case where the refractive index of the glass substrate is larger than the refractive index of the microprism array.

It is sectional drawing for demonstrating the light modulation apparatus which concerns on 1st Embodiment. It is a perspective view for demonstrating the shape of the microprism array which concerns on 1st Embodiment. It is a perspective view for demonstrating the modification of the shape of the microprism array which concerns on 1st Embodiment. It is sectional drawing for demonstrating the light modulation apparatus which concerns on 2nd Embodiment. It is sectional drawing for demonstrating the light modulation apparatus which concerns on 3rd Embodiment. It is a top view for demonstrating the projector which concerns on 4th Embodiment. It is sectional drawing for demonstrating the light modulation apparatus which concerns on 5th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100, 200, 300, 400, 600 ... Light modulation apparatus, 1 ... Incident substrate, 2 ... Ejection substrate, 3 ... Display layer, 4, 5 ... Micro prism array, 6, 7 ... Glass substrate, 8 ... Liquid crystal pixel, 9 ... Black matrix part 9, 4a, 4b, 5a, 5b ... Prism-shaped member, CN, CN1, CN1 '... Cone, BS ... Bottom, S, S1, S1' ... Vertex, 8a ... Pixel of interest, IL, ILa, ILb ... Incident light, EL, ELa, ELb ... Reflected light

Claims (9)

A pair of substrates each having an electrode formed thereon;
A liquid crystal sandwiched between the pair of substrates;
A plurality of pixels configured to include the electrodes respectively formed on the pair of substrates and the liquid crystal sandwiched between the pair of electrodes;
A light shielding portion that shields the periphery of each of the plurality of pixels;
A light modulation device comprising:
The pair of substrates includes a prism array including a plurality of prisms, at least one of which is provided corresponding to the plurality of pixels.
The prism has a bottom surface parallel to the substrate surface and a side surface constituted by a straight line, and a size of a cross section of the prism parallel to the substrate surface decreases as the distance from the bottom surface increases. Light modulation device.   One of the pair of substrates is an incident substrate that forms an incident surface of light, and the other is an emitting substrate that forms an exit surface of light, and both the incident substrate and the emitting substrate are the prisms. The light modulation device according to claim 1, further comprising an array.   2. The prism according to claim 1, wherein each of the prisms has symmetry with respect to a center of the corresponding pixel, and maintains parallelism of incident light incident in parallel within a vertical section including the straight line. Item 3. The light modulation device according to any one of Items 2 to 3.   4. The light modulation device according to claim 3, wherein the incident light intersects symmetrically with respect to the center.   5. The prism according to claim 1, wherein the prism includes at least a part of either a cone shape or a column shape, and the bottom surface is formed according to a shape of the plurality of pixels. The light modulation device according to one item.   The light modulation device according to claim 1, wherein the prism includes at least a part of a conical shape.   The prism includes a pair of end portions each having at least a part of a pair of cone portions obtained by dividing a cone shape into two along an axis, and a triangular columnar central portion sandwiched between the pair of cone portions, The projector according to claim 6, wherein the pixel is a rectangle.   8. The light modulation device according to claim 5, wherein the prism has a trapezoidal shape having a crest chamfered in parallel to the bottom surface. 9. An illumination device that emits illumination light;
A color separation optical system that separates the illumination light for each predetermined wavelength; and
A plurality of light modulation devices according to any one of claims 1 to 8,
A color synthesizing optical system that synthesizes the image light of each of the color lights formed by the plurality of light modulation devices;
A projection optical system for projecting image light synthesized by the color synthesis optical system;
A projector comprising:

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