JP6503799B2 - Lighting device and image display device - Google Patents

Description

  The present invention relates to a lighting device and an image display device having the lighting device.

  2. Description of the Related Art An image display apparatus such as a front projection type projector apparatus that projects an image on a screen installed in front of the apparatus is widely used, for example, for presentation in a company, for school education, or for home use.

  The brightness of the image displayed on the projection surface of the image display device is determined by the power of the light source and the light utilization efficiency of the optical system. Here, the light utilization efficiency is the ratio of the intensity of the reflected light beam to the intensity of the irradiated light beam. In the image display apparatus, in order to improve the light utilization efficiency, it is possible to improve the transmittance and the reflectance of the optical elements constituting the optical system, or to suppress the light quantity loss due to the light in the optical path. Measures can be considered.

  In order to improve the transmittance and the reflectance of the optical element, the transmittance and the reflectance can be reduced to several% or less by applying a non-reflection coating to at least the incident surface or the exit surface of the optical device.

  On the other hand, the light quantity loss due to vignetting is caused by the fact that the projection range of light becomes larger than the effective area of the optical element.

  In an image display apparatus including a light tunnel and a DMD (Digital Micromirror Decive), light loss due to vignetting includes light tunnel coupling loss and DMD loss.

  The light tunnel coupling loss is the loss of light that occurs until the light emitted from the light source enters the light tunnel.

  The DMD loss is a light quantity loss that occurs when the light beam reflected by the optical element of the illumination optical system is projected to the DMD. That is, the DMD loss is such that the light beam projected in the direction of the DMD (hereinafter referred to as "DMD projection light beam") is larger than the effective area of the DMD and distorted relative to the effective area of the DMD. It occurs in Here, the effective area of the DMD refers to an area on the DMD that can reflect the DMD projected light flux.

  Therefore, there is a need for an illumination device that can illuminate the projection surface brightly while suppressing the DMD loss.

  So far, for example, there has been disclosed an image display apparatus having an imaging optical system for imaging light from a light source as an image, and a projection optical system for projecting the imaged image on a screen (for example, , Patent Document 1). Here, Patent Document 1 discloses that an illumination optical system includes a rod integrator, a relay lens, a first illumination mirror, a second illumination mirror, and a condenser lens.

  Further, in Patent Document 1, in order to suppress occurrence of astigmatism and obtain high imaging performance, the reflecting surface of the second illumination mirror has a curvature radius corresponding to the long side direction of the exit end of the rod integrator. It is disclosed to provide a rotationally asymmetric reflective surface larger than the radius of curvature corresponding to the short side direction.

  Further, in the image display device described in Patent Document 2, the first illumination mirror is a cylinder mirror, and the second illumination mirror is a spherical mirror.

  However, Patent Documents 1 and 2 do not disclose the arrangement of mirrors of an anamorphic surface that can suppress the DMD loss and brighten the projection surface by optimizing the shape of the DMD irradiation light flux. The

  Further, in the technology of Patent Document 1, the first illumination mirror and the reflection surface of the second illumination mirror are both anamorphic surfaces, and both have free-form surface shapes configured using high-order expanded aspheric coefficients. It is. Therefore, in the technique of Patent Document 1, there is a problem that it takes time to check whether the shape of the reflective surface is appropriately formed.

  An object of this invention is to provide the illuminating device which can illuminate a to-be-projected surface brightly by simple structure.

The lighting device according to the present invention is
Light source,
A light mixing element for forming a secondary light source by an image of a plurality of the light source by the light beam from the light source,
An illumination optical system for projecting a light beam from the plurality of secondary light sources to the light modulation element,
A lighting device having
The illumination optical system comprises an optical element having an anamorphic surface,
The optical element, as a rotation axis normal from the vertex of said anamorphic surface, Ri position near rotated relative to the optical modulator,
The luminous flux reflected by the light modulation element includes a first luminous flux reflected in the direction in which a projection optical system that projects the reflected luminous flux onto a projection surface is provided.
The rotation angle of the optical element with respect to the light modulation element with the normal axis from the top of the anamorphic surface as the rotation axis of the optical element is the light at the incident end of the first light beam of the projection optical system The light distribution angular distribution of the first light flux in the direction of the rotation axis of the plurality of micro mirrors included in the modulation element is smaller than the light distribution angular distribution of the first light flux in the direction orthogonal to the rotation axis of the micro mirror is there,
It is characterized by

  According to the present invention, the projection surface can be brightly illuminated with a simple configuration.

It is a schematic block diagram which shows the arrangement | positioning relationship with the to-be-projected surface which shows embodiment of the image display apparatus concerning this invention. It is a schematic block diagram which shows the arrangement | positioning relationship between the said image display apparatus and a to-be-projected surface. It is an optical layout showing an embodiment of the above-mentioned image display device. It is a schematic block diagram which shows the structure from the light source of the said image display apparatus to a light tunnel. It is a perspective view which shows the 2nd illumination mirror of the said image display apparatus. It is a perspective view of DMD of the said image display apparatus. It is a schematic diagram which shows the state of the inclination of the micro mirror which said DMD has. It is an optical layout showing the composition of the projection optical system of the above-mentioned image display device. It is an optical layout showing the composition of the above-mentioned projection lens system. It is a perspective view which shows the structure of the 2nd projection mirror which the said projection optical system has. It is a perspective view which shows the coordinate position of the said 2nd projection mirror. It is a schematic diagram which shows the relationship between the effective area | region of said DMD, and the irradiation area | region of the light beam radiated | emitted from the vertex of the opening of a light tunnel. It is an optical path figure which shows the course of the ray emitted from the point light source arranged at the center of the outgoing end of the above-mentioned light tunnel. It is a graph which shows illumination distribution on the light receiver arrange | positioned to the virtual surface of the incident end of the projection lens system of the light ray emitted from the said point light source. When the rotation angle γ of the second illumination mirror is rotated by 90 degrees from the design median value, it is a graph showing the illuminance distribution on the light receiver disposed on the virtual surface of the entrance of the projection lens of the light beam emitted from the point light source. It is a graph which shows the relationship between the rotation angle from the design median value of said 2nd illumination mirror, and SD / SI. It is a graph which shows the result of having calculated the illumination distribution on said DMD by ray tracing. It is a perspective view which shows the 2nd illumination mirror with which another embodiment of the image display apparatus concerning this invention is equipped. It is a graph which shows the illuminance distribution on the light receiver arrange | positioned to the virtual surface of the incident end of the projection lens system of the projection lens system of the light ray emitted from the point light source with which the said image display apparatus is equipped. 14 is a graph showing an illuminance distribution on a light receiver disposed on a virtual surface of an entrance of a projection lens of a light beam emitted from the point light source in a state where the rotation angle γ of the second illumination mirror is rotated 90 degrees from a design median . It is a graph which shows the result of having calculated the illuminance distribution on DMD with which the said image display apparatus is equipped by ray tracing. It is a figure which matches the incident angle of the light beam which injects into flat glass with the incident position when the said light beam injects into a to-be-projected surface, and matches it. It is a figure which shows the average illumination intensity of the area | region corresponding to the upper half of a projection surface among the illuminance distribution in FIG. 17, and the area | region corresponding to a lower half. It is a figure which shows the average illumination intensity of each area | region divided perpendicularly | vertically and horizontally toward the to-be-projected surface among the illumination intensity distribution in FIG.

  Hereinafter, embodiments of a lighting device according to the present invention and an image display device having the lighting device will be described with reference to the drawings.

● Image display device (1) ●
First, an embodiment of an image display device according to the present invention will be described.

  As shown in FIG. 1, the image display apparatus 100 projects a projection image on the projection surface 101. Moreover, FIG. 2 is a schematic block diagram which shows the arrangement | positioning relationship between the image display apparatus 100 and the to-be-projected surface 101. As shown in FIG. Here, the projection surface 101 is, for example, a screen.

Configuration of Image Display Device 100 As shown in FIG. 3, the image display device 100 includes an illumination device 200, a cover glass 6, a DMD 7, and a projection optical system 8.

  In the following description, the origin O of the absolute coordinate system (xyz system) is the center (central portion) of the DMD 7 and one of the directions (horizontal direction of the DMD 7) in the horizontal surface (surface) of the DMD 7 is the x axis I assume. Further, the horizontal direction (longitudinal direction of the DMD 7) of the DMD 7 orthogonal to the x-axis is taken as z-axis, and the axis perpendicular to the surface of the DMD 7 orthogonal to both x-axis and z-axis is taken as y-axis. Also, the x-axis is parallel to the lateral direction of the DMD 7, and the z-axis is parallel to the longitudinal direction of the DMD 7.

  Furthermore, in the following description, rotation angles around the x-axis, y-axis, and z-axis will be referred to as rotation angles α, β, and γ, respectively. The rotation angle α and the rotation angle β are positive in the counterclockwise direction when viewed from the positive direction of each of the x axis and the y axis. Further, the rotation angle γ is positive clockwise when viewed from the positive direction of the z axis.

Configuration of Lighting Device 200 The lighting device 200 is a device that projects a light flux onto the DMD 7. The illumination device 200 includes a light source 1, a light tunnel 2, an explosion-proof glass 12, a color wheel 13, and an illumination optical system 18.

  As shown in FIG. 3, the light source 1 includes a reflector 401. Inside the reflector 401, a light emitter and a collecting mirror are provided. The light emitter is, for example, a xenon lamp, a mercury lamp, or a metal halide lamp. A lamp cover is provided at the front end of the light source 1.

  The illumination device 200 forms a light source image from the light flux emitted from the light source 1 using a condensing mirror. The optical axis of the light beam emitted from the light source 1 is in the z-axis direction. The light source 1 is disposed so that the light distribution of the light beam emitted from the light source 1 is substantially rotationally symmetric and isotropic with respect to the optical axis (z axis).

  As shown in FIG. 4, an explosion proof glass 12 and a color wheel 13 are disposed between the light source 1 and the light tunnel 2. The explosion-proof glass 12 and the color wheel 13 are disposed such that their incident and exit surfaces are inclined at a predetermined angle (for example, 10 degrees) with respect to the optical axis of the light source 1 (z-axis direction in FIG. 4).

  The color wheel 13 is a known optical filter in which an annular portion is divided into three corresponding to the three primary colors of light (red (R), green (G), and blue (B)). The color wheel 13 may be an optical filter divided into four by adding white (W) to red, green and blue.

  The luminous flux from the light source 1 is time-divided into luminous fluxes of respective colors added with R, G, B, or W because the annular zone crosses the light path of the light when the color wheel 13 is rotationally driven. It is incident on That is, the image display apparatus 100 forms a color image on the projection surface 101 by projecting an image corresponding to the optical filter of each color of the color wheel 13 onto the projection surface 101.

  The light tunnel 2 is a light mixing element configured such that the reflecting surfaces of four plate-like mirrors face inward to form a square tube. In addition to the light tunnel 2, a well-known rod integrator, a light pipe or the like may be used as the light mixing element.

  The light tunnel 2 has a rectangular opening at the entrance end 21 and the exit end 22. The light tunnel 2 is disposed such that the incident end 21 is located near the focal position of light behind the color wheel 13. The luminous flux from the light source 1 is efficiently incident on the light tunnel 2 by adjusting the focal position of the light to be disposed near the incident end 21.

  In the light tunnel 2, a plurality of images of light sources are formed at the exit end of the light tunnel 2 by repeating reflection of incident light by four mirrors arranged on the inner surface, and the exit end of the light tunnel 2 is a secondary light source Form Therefore, light having a rectangular cross-sectional area with uniformed illuminance distribution is emitted from the emission end 22 of the light tunnel 2. Since the light distribution of the light emitted from the light tunnel 2 is substantially symmetrical with respect to the optical axis (z-axis), the isotropy of the emitted light is maintained.

  The emitting end 22 and the surface of the DMD 7 on which the micro mirror group is provided are disposed at substantially conjugate positions.

  At the exit end 22 of the light tunnel 2, a light tunnel arrangement adjusting means is provided. The light emitting end 22 is tilted in the longitudinal direction or the latitudinal direction (the direction of the arrow 105 or the arrow 106 in FIG. 3) of the rectangular opening by the light tunnel arrangement adjusting means. Therefore, the light tunnel arrangement adjusting means can adjust the direction of light projected from the light tunnel 2 to the DMD 7.

  An illumination optical system 18 is disposed on the path of the light emitted from the light tunnel 2.

Configuration of Illumination Optical System 18 The illumination optical system 18 is an optical system that projects luminous fluxes from a plurality of secondary light sources formed by the light tunnel 2 onto the DMD 7.

  The illumination optical system 18 includes a lens 3, a first illumination mirror 4, and a second illumination mirror 5. In the illumination optical system 18, the lens 3, the first illumination mirror 4 and the second illumination mirror 5 are arranged in this order in the traveling direction of the light flux from the light tunnel 2 to the DMD 7.

  The lens 3 is on a substantially straight path of the light emitted from the light tunnel 2. The lens 3 is composed of a single condenser lens having an aspheric surface on the exit surface. Here, the aspheric surface of the exit surface of the lens 3 is represented by the aspheric surface defined by Equation 1, the radius of curvature of Table 1 described later, and the aspheric surface coefficient.

(Equation 1)

  The lens 3 may be configured of a plurality of lenses.

  Here, z ′ in Equation 1 is expressed by a local coordinate system x ′, y ′, z ′ with the surface vertex of each lens as the origin. That is, in Equation 1, z 'is the amount of sag of the lens surface.

  The first illumination mirror 4 is on a substantially straight path of the light flux emitted from the light tunnel 2. The first illumination mirror 4 is a plane mirror. The first illumination mirror 4 is installed in a posture inclined with respect to both the x-axis direction and the z-axis direction so as to project the light emitted from the lens 3 to the second illumination mirror 5.

  The second illumination mirror 5 projects the light reflected by the first illumination mirror 4 toward the DMD 7 disposed below. The second illumination mirror 5 is installed in a posture inclined with respect to both the x-axis direction and the z-axis direction.

  The first illumination mirror 4 and the second illumination mirror 5 are disposed in front of the light modulation element in the light path of the light flux, so that it is simple unlike the image display apparatus in which the lens is disposed in front of the light modulation element. An illumination optical system can be realized.

  As shown in FIG. 5, the reflective surface of the second illumination mirror 5 is an anamorphic surface. The reflection surface of the second illumination mirror 5 is a toroidal surface. A toroidal surface is a simpler shape than a surface shape using higher order expanded aspheric coefficients. Therefore, the time required for the inspection time of the surface shape of the second illumination mirror 5 can be shortened, and the manufacturing cost of parts can be reduced.

  The toroidal surface of the second illumination mirror 5 is an aspheric surface defined by Equation 2 below, where O ′ is the origin of the local coordinate system (x′y′z ′ system). This aspheric surface is a concave surface formed by rotating an arc having a radius of curvature Ry = 79.1 mm around an axis parallel to the y'-axis around an axis parallel to the x'-axis with a radius of curvature Rx = 68.7 mm. It is a toroidal surface.

(Formula 2)

  As described above, the light beam emitted from the light source 1 is shaped by the illumination optical system 18 so that the cross-sectional shape of the light is shaped, and is projected on the surface of the DMD 7 on which the minute mirror group described later is provided.

  By arranging the illumination optical system 18 as described above, the uniform luminous flux emitted from the emission end 22 of the light tunnel 2 is uniformly projected to the DMD 7.

  Further, as described above, the light flux from the lens 3 is reflected three-dimensionally several times before reaching the projection optical system 8 through the first illumination mirror 4, the second illumination mirror 5 and the DMD 7.

  The first illumination mirror 4 and the second illumination mirror 5 are centered on the optical axis of the projection lens system 81 so that the light flux is not interfered by each optical member between the lens 3 and the projection optical system 8. It is disposed to be inclined with respect to the x-axis direction and the y-axis direction.

  Table 1 shows component specifications of the illumination optical system 18 from the light source 1 to the DMD 7.

  Table 2 shows the position coordinates of each of the optical components constituting the illumination optical system 18. The arrangement of each optical component shown in Table 2 is based on the position where the direction and origin of the three axes of the local coordinate system (x'y'z 'system) of each optical component coincide with the absolute coordinate system (xyz system) It is determined by moving and rotating each optical component based on the values in Table 2. That is, in the arrangement of each optical component, first, the local coordinate system of each optical component is displaced in the xyz direction in Table 2, and then the rotation about the x 'axis (α rotation) and the rotation about the y' axis (.Beta. Rotation) and rotation about the z 'axis (.gamma. Rotation).

  The cover glass is disposed on the surface of the DMD 7 on which the micro mirror is provided in order to protect the DMD 7.

Configuration of DMD 7 As shown in FIG. 6, the DMD 7 is disposed substantially along a horizontal surface. The DMD 7 is provided with micromirror groups 7-1 to 7-k arranged in a two-dimensional manner. The DMD 7 corresponds to a light modulation element.

  As for the number of micro mirror groups 7-1 to 7-k, the number M of micro mirrors in the longitudinal direction is 1280, and the number N of micro mirrors in the lateral direction is 800. That is, the DMD 7 is provided with a total of k = M × N = 1024000 micro mirror groups 7-1 to 7-k. Here, the aspect ratio of the DMD 7 is 1280: 800 = 16: 10.

  The inclinations of the minute mirror groups 7-1 to 7-k change independently of one another. By changing the inclination of the minute mirror group 7-1 to 7-k, it is possible to change the reflection angle of the light flux. Here, the deflection angles of the micro mirror groups 7-1 to 7-k are approximately ± 12 degrees.

  Each of the micro mirror groups 7-1 to 7-k has an on state and an off state depending on the reflection angle of the light beam. Here, the on state is a state in which the reflected light of the micro mirror is projected to the subsequent projection optical system 8. The off state is a state in which the reflected light of the micro mirror is deviated without being projected onto the subsequent projection optical system 8.

  FIG. 7 shows an arbitrary one of the micro mirror groups 7-1 to 7-k (hereinafter referred to as "micro mirror 7-j"). The micro mirror 7-j rotates around an axis parallel to the x = z straight line on the xz plane, that is, the x 'axis.

  When the micro mirror 7-j is at an inclination angle of +12 degrees with respect to the xz plane (on state), the light flux (first light flux) reflected by the micro mirror 7-j has a first direction (direction of the projection optical system 8) Head for Also, when the micro mirror 7-j is at -12 degrees (off state) with respect to the xz plane, the light flux (second light flux) reflected by the micro mirror 7-j deviates from the projection optical system 8 in the second direction. Head towards the direction).

  That is, the light flux reflected by the DMD 7 includes the first light flux reflected in the direction in which the projection optical system 8 that projects the reflected light flux onto the projection surface 101 is provided.

  The light from the second illumination mirror 5 to the DMD 7 is projected in the direction crossing the rotation axis of the micro mirror 7-j, that is, in the direction from the space on the −x, + z, + y side to the origin.

  The minute mirrors 7-m to 7-n (m and n are integers of 1 or more and k or less) in the on state direct the light flux reflected by the second illumination mirror 5 to the projection optical system 8 reflect. Then, the reflected light from the micro mirrors 7-m to 7-n in the on state is projected by the projection optical system 8 onto the projection surface 101 installed parallel to the plane including the y axis and the z axis. . Here, the image size projected onto the projection surface 101 is 80 inches at maximum.

Configuration of Projection Optical System 8 The projection optical system 8 is an optical system that projects the light flux from the DMD 7 onto the projection surface 101.

  As shown in FIG. 8, the projection optical system 8 has a lens barrel 10, a projection lens system 81, a first projection mirror 84, a second projection mirror 85, and a flat glass plate 9 in the form of a plate. Become. The light beam reflected from the DMD 7 toward the projection optical system 8 is projected from the projection optical system 8 onto the projection surface 101. The central ray 201 reflected at the center of the DMD 7 and directed to the projection surface 101 through the projection optical system 8 is incident on the flat glass 9 at an incident angle. The angle of incidence is greater than 0 degrees. The lens barrel 10 holds a projection lens system 81.

  FIG. 9 is an optical layout diagram showing the configuration of the projection lens system 81 of the projection optical system 8. The projection lens system 81 includes a projection lens 811, a projection lens 812, a projection lens 813, a projection lens 814, a projection lens 815, a projection lens 816, a projection lens 817, a projection lens 818, a projection lens 819, a projection lens 820, and a projection lens 821. It consists of 11 lenses. The incident end of the projection lens system 81 is a projection lens 811. Further, the emission end of the projection lens system 81 is a projection lens 821.

  The optical axis of the projection lens system 81 is directed in the y-axis direction. Further, the projection surface 101 is disposed in parallel to the optical axis of the projection lens system 81. The first projection mirror 84 and the second projection mirror 85 are arranged to project the light flux transmitted through the projection lens system 81 toward the projection surface 101.

  Table 3 shows the specifications of the projection lens system 81.

  In Table 3, the radius of curvature of the surface corresponding to the surface number is R, the distance between adjacent surfaces is d, the refractive index to the D line of each lens is nd, and the Abbe number of each lens is vd. The projection lens 811, the projection lens 820, and the projection lens 821 are lenses with both aspheric surfaces.

  Table 4 shows the aspheric coefficients of the projection lens 811, the projection lens 820 and the projection lens 821. The aspheric surface shape of the aspheric lens of the projection lens 811, the projection lens 820 and the projection lens 821 is represented by the aspheric surface equation using the local coordinate system defined by the equation 1 described above and the aspheric surface coefficients shown in Table 4 Be done.

  The projection optical system 8 can also be applied to a configuration in which the optical axis of the projection lens system 81 is substantially perpendicular to the projection surface 101.

  As shown in FIG. 2 and the like, the first projection mirror 84 reflects the light flux from the projection lens system 81 toward the second projection mirror 85.

  FIG. 10 is a perspective view showing a second projection mirror 85 of the projection optical system 8. The second projection mirror 85 has a free-form surface formed on the reflection surface. The free curved surface formed on the reflection surface of the second projection mirror 85 corrects the distortion of the image projected on the projection surface 101 in the vertical and horizontal directions.

  In the free-form surface, the curvature in the X direction according to the position in the X direction is not constant at any position in the Y direction, and the curvature in the Y direction according to the position in the Y direction is constant at any position in the X direction Not an anamorphic surface.

  In FIG. 11, at the position of Y = 0, the lens surface position (X, Y) = (0, 0), the lens surface position (X, Y) = (− X1, 0), the lens surface position (X, Y) The curvature in the X direction is different with = (+ X1, 0). Also, at the position of X = 0, the curvature in the Y direction is different between the lens surface position (X, Y) = (0, 0) and the lens surface position (X, Y) = (0, -Y2).

  The curvatures of the X direction and the Y direction are different at the lens surface position (X, Y) = (0, 0). The curvatures of the X direction and the Y direction are different also at the lens surface position (X, Y) = (0, -Y2).

  Table 5 is a table which shows the aspherical coefficient which shows the shape of the reflective surface of the 2nd projection mirror 85. FIG. When the origin of the local coordinate system (x'y'z 'system) is O' as shown in FIG. It is formed into an aspheric surface represented using a spherical coefficient.

(Equation 3)

  Table 6 shows the specifications of optical components other than the projection lens system 81 and the second projection mirror 85 that constitute the projection optical system 8. The diaphragm 1, the diaphragm 2 and the diaphragm 3 in Table 6 are omitted in the figure.

  Table 7 shows arrangement coordinates of optical components of the projection optical system 8 when the screen size to be projected onto the projection surface 101 is 43 inches.

  As shown in the table, the image display apparatus 100 is configured to project the projection light obliquely upward toward the projection surface 101.

  The flat glass 9 is disposed behind the second projection mirror 85 in the light path. In the present embodiment, the flat glass 9 is disposed close to the upper ends of the first projection mirror 84 and the second projection mirror 85 and in parallel to a plane including the x axis and the z axis. The flat glass 9 is fitted into the upper end opening of the housing in which the image display device 100 is incorporated. With this configuration, the inside of the image display apparatus can be dustproofed.

Positional relationship between the DMD 7 and the second illumination mirror 5 FIG. 12 shows the effective area of the DMD 7 and the irradiation area of the light beam projected onto the DMD 7 by the second illumination mirror 5 after being projected from the top of the opening of the light tunnel 2. It is a schematic diagram which shows a relationship.

  Here, the light condensing point in the virtual plane parallel to the xz plane of the light flux projected from the vertex (each point of the four corners) of the opening of the light emitting end 22 of the light tunnel 2 is arranged respectively It is assumed that a condensing point P1, a point P2, a point P3 and a point P4. In other words, the positions of the condensing points P1 to P4 are the barycentric coordinate positions of the light beams projected from the four corners of the opening of the light emitting end 22 of the light tunnel 2 in the virtual plane on the same plane as the reflection surface of the DMD 7. It is.

  As shown in FIG. 12, the shape formed when the condensing points P1 to P4 are virtually connected by a line is a distorted rectangular shape.

  Generally, in an illumination optical system in which optical elements such as lenses and mirrors are disposed eccentrically in a three-dimensional space, the imaging shape on the DMD corresponds to the opening shape even if the light tunnel opening shape is rectangular. It becomes a distorted rectangular shape deformed from a complete rectangle.

  Among the DMD losses, it is not a good idea to make the DMD projected light flux smaller in order to secure an adjustment margin between the DMD projected light flux and the position of the DMD 7. Therefore, in order to suppress the DMD loss and improve the light utilization efficiency in the DMD, it is effective to eliminate distortion of the DMD projection light flux and to make the DMD projection light flux as similar as possible to the effective area of the DMD 7. Therefore, in the image display device 100, a toroidal surface is adopted as the reflection surface of the second illumination mirror 5.

  The rotation angle γ of the second illumination mirror 5 with respect to the DMD 7 is based on the light distribution angle distribution in the direction orthogonal to the rotation axis z ′ in the light distribution angle distribution in the rotation axis z ′ direction of the micro mirror groups 7-1 to 7-k. Is set to a smaller position. Here, the rotation axis of the rotation angle γ of the second illumination mirror 5 is a normal from the surface vertex of the second illumination mirror 5. Further, the rotation angle γ of the DMD 7 is 0 degree.

Next, the illuminance distribution on the light receiver will be described using simulation results. A light receiver 701 shown in FIG. 13 is a virtual element on simulation for analyzing the reflected light to the projection optical system 8.

  The simulation in FIGS. 13 to 16 was performed using LightTools (registered trademark) manufactured by ORA Corporation. The light source used for the simulation is a Philips high pressure mercury lamp UHP 240-190W 0.8 E20.9 FusionStar.

  FIG. 13 is a ray diagram of a light flux 700 emitted from a point light source disposed at the opening center (x, y, z) = (-8.818, 19.025, -30. 897) of the exit of the light tunnel 2. Illustration of optical elements other than the light tunnel 2 and the DMD 7 is omitted in FIG. The light receiver 701 in FIG. 13 is disposed on a virtual plane of the incident plane position (x, y, z) = (5.630, 42.080, 0) of the projection lens 811.

  As shown in FIG. 13, the light receiving surface of the light receiver 701 is disposed perpendicularly to the chief ray of the light beam 700. The local coordinate system x'z 'has (x, y, z) = (5.630, 42.080, 0) as the origin, the x' axis is the direction of the x = z straight line, and the z 'axis is orthogonal to the x' axis It is in the direction.

  FIG. 14 is a graph showing an illuminance distribution on a light receiver 701 disposed on a virtual plane of the incident end of the projection lens system 81 of a light beam emitted from a point light source disposed at the opening center of the emission end 22 of the light tunnel 2 is there. Here, the vertical axis of the graph of FIG. 14 is the normalized illuminance normalized with the maximum illuminance on the light receiving surface of the light receiver 701 as one. The rotation angle γ of the second illumination mirror 5 is a designed median (γ = −81.310 degrees). The illuminance distribution indicates that the illuminance distribution is wider as the absolute value at which the graph intersects with the straight line with zero normalized illuminance is larger.

  As shown in FIG. 14, the illuminance distribution in the z'-axis direction is wider than the illuminance distribution in the x'-axis direction. That is, the light distribution angular distribution in the x 'axis direction is smaller than the light distribution angular distribution in the z' axis direction.

  The luminous flux emitted from the reflector 401 of the light source 1 is approximately symmetrical and isotropic with respect to the optical axis (z axis). Therefore, in the light fluxes reflected by the plurality of micro mirrors constituting the DMD 7 in the first direction, the light distribution angular distribution in the x 'axis direction of the reflected light flux is smaller than the light distribution angular distribution in the z' axis direction It is set.

  FIG. 15 shows a state where the rotation angle γ of the second illumination mirror 5 is rotated ± 90 degrees from the design median value (γ = −81.310 degrees) (γ = 8.640 degrees or γ = −171.310 degrees) In the same manner as in FIG. 13, the normalized illuminance distribution on the light receiver 701 is calculated.

  In the state of FIG. 15, unlike in FIG. 14, the illuminance distribution in the x ′ axis direction is wider than the illuminance distribution in the z ′ axis direction. That is, the light distribution angle distribution of the illumination optical system in the z 'axis direction is larger than the light distribution angle distribution in the x' axis direction.

  That is, by adjusting the rotation angle γ of the second illumination mirror 5, the light distribution angular distribution in the x 'axis direction of the light flux reflected in the first direction by the plurality of micro mirrors constituting the DMD 7 is in the z' axis direction It can be set to be smaller than the light distribution angle distribution.

The relationship between the polygon on the virtual plane and the effective area 17 of the DMD 7 The relationship between the effective area of the DMD 7 and the polygon さ れ る formed by connecting the points P1, P2, P3 and P4 on the virtual plane Will be explained.

  An area of a polygon さ れ る formed by connecting the points P1, P2, P3 and P4 is represented by SI. Further, the area of a polygon obtained by similarly reducing or expanding the effective area 17 so that at least one vertex of the effective area 17 of the DMD 7 is inscribed in the polygon in the polygon 上 の on the virtual surface is defined as SD.

  FIG. 16 is a graph showing the relationship between the rotation angle γ from the design median of the second illumination mirror 5 and SD / SI. FIG. 16 changes the rotation angle γ of the second illumination mirror 5 shown in Table 2 from −90 degrees to +90 degrees with reference to the design median (γ = −81.310 degrees) (Δγ = 0 degrees). The relationship between the amount of rotation Δγ and the SD / SI is shown.

  In the graph in the figure, the radii of curvature Rx and Ry of the reflection surface of the second illumination mirror 5 are respectively spherical surfaces with R = Rx = Ry, and R = Rx, R = Ry, R = (Rx + Ry) / 2. The graph shows the case of. The graph shows that by making the reflection surface of the second illumination mirror 5 a toroidal surface, it is possible to find a rotation angle γ at which SD / SI is maximized. SD / SI is maximized at Δγ = 0, and the light utilization efficiency of the DMD 7 is also maximized.

  Therefore, by setting the rotation angle γ of the second illumination mirror 5 as described above, it is possible to make the DMD projection light flux approach the shape of the effective area 17. That is, the light utilization efficiency of the DMD 7 can be improved.

  FIG. 17 is a graph showing the results of calculation of the illuminance distribution on the DMD 7 by ray tracing. In FIG. 17, the area surrounded by the black line is the effective area 17 of the DMD. In addition, the illuminance distribution is displayed by normalizing the maximum illuminance in the area as 1, that is, 100%.

  The average value of 9 points of ANSI (American National Standards Institute) of the effective area 17 (the illuminance at the center of each area when the effective area 17 is divided into 9 equal size in vertical and horizontal directions) is 89.3%. That is, the illuminance distribution of the effective area 17 indicates that the distribution is uniform.

Relationship Between Incident Angle to Flat Glass 9 and Illuminance of Projected Surface 101 FIG. 22 corresponds the incident angle of the light beam incident on the flat glass 9 to the incident position when the light beam is incident on the projected surface 101 FIG. The incident angle at which the central ray 201 is incident on the flat glass 9 is 26.2 °. The incident angles at which the light rays incident on the upper right end and the upper left end as viewed from the incident direction on the projection surface 101 enter the flat glass 9 is 36.5 °, and the light rays incident on the lower right end and the lower left end of the projection surface 101 are planar The incident angle to the glass 9 is 80.2 °. In other words, when the projection surface 101 is divided into the first area 1011 of the upper half and the second area 1012 of the lower half, the incident angle at which the light beam incident on the first area 1011 is incident on the flat glass 9 is the second The luminous flux incident on the area 1012 is smaller than the incident angle on the flat glass 9. Generally, depending on the position on the projection surface 101, the angle of incidence on the flat glass 9 is as wide as less than 20 ° to about 80 °.

  The light beam incident angle to the flat glass 9 becomes larger as it approaches the lower left and right corners from the center of the projection surface 101, and the light incident angle to the flat glass 9 toward the lower left and right corners becomes 80 ° or more. Generally, the transmittance decreases as the incident / exit angle to the optical element increases, so that the transmission loss of the light traveling to the lower half is larger than the light traveling to the region of the upper half of the projection surface 101. In the lower left and right corners of the projection surface 101, the transmission loss by the flat glass 9 tends to reduce the illuminance.

  However, when the second illumination mirror 5 sets the average illuminance on the reflective surface of the DMD 7 of the luminous flux incident on the first region 1011 to L1, and the average illuminance on the reflective surface of the DMD 7 on the luminous flux incident on the second region 1012, L2. It is disposed at a position where L1 <L2. The average illuminance indicates the average in the area of the illuminance distribution in FIG.

  As shown in FIG. 23, the average illuminance L1 of the first area 1011 (effective area on the −x side in FIG. 17) is 86.2%. The average illuminance L2 of the second area 1012 (effective area on the + x side in FIG. 17) is 91.4%. By setting the rotation angle γ of the second illumination mirror 5 as described above, the relationship of L1 <L2 can be established. That is, by adjusting the rotation angle γ of the second illumination mirror 5, it is possible to suppress an increase in the transmission loss of the light beam in the second region 1012 caused by the flat glass 9 being disposed downstream of the projection optical system 8. .

  FIG. 24 is a view showing the average illuminance of each of the regions divided vertically and horizontally toward the projection surface 101 in the illuminance distribution in FIG. The average illuminance LA of the upper left region A1013 is 85.5%, and the average illuminance LB of the upper right region B1014 is 87.1%. The average illuminance LC of the lower left region C1015 is 91.5%, and the average illuminance LD of the lower right region D1016 is 91.6%. The difference between LC and LD is approximately equal. That is, by adjusting the rotation angle γ of the second illumination mirror 5, it is possible to suppress an increase in the transmission loss of the light beam in the area C 1012 caused by the flat glass 9 being disposed downstream of the projection optical system 8. In other words, it is possible to obtain uniform illuminance distribution balanced on the left and right.

  According to the embodiment described above, the light use efficiency in the DMD 7 can be adjusted by adjusting the rotation angle γ of the second illumination mirror 5. That is, the projection surface can be illuminated brightly and uniformly by a simple configuration.

● Image display device (2) ●
Next, another embodiment of the image display device according to the present invention will be described focusing on differences from the above-described embodiment. The present embodiment differs from the embodiments described above in that the reflection surface of the second illumination mirror is an aspheric surface represented by a polynomial that is rotationally asymmetric with respect to the normal from the surface vertex.

  As shown in FIG. 18, the reflection surface of the second illumination mirror 205 is a polynomial aspheric surface rotationally asymmetric with respect to the normal from the surface vertex. This surface has the aspheric surface equation defined by Equation 3 and the curvature radius R and the aspheric surface coefficient described in Table 8 when the local coordinate system (x ', y', z 'system) origin is O'. It is an aspheric surface expressed using. Table 9 shows component specifications of the illumination optical system 18 from the light source 1 to the DMD 7. Table 10 shows the position coordinates of each optical component that constitutes the illumination optical system 18.

  As shown in FIG. 19, the illuminance distribution in the z'-axis direction on the light receiver disposed on the virtual plane at the incident end of the projection lens system is wider than the illuminance distribution in the x'-axis direction. That is, the light distribution angular distribution in the x 'axis direction is smaller than the light distribution angular distribution in the z' axis direction.

  As shown in FIG. 20, in the state where the rotation angle γ of the second illumination mirror 205 is rotated by 90 degrees from the designed median value, the illuminance distribution in the x ′ axis direction is wider than the illuminance distribution in the z ′ axis direction. That is, the light distribution angular distribution in the z 'axis direction is smaller than the light distribution angular distribution in the x' axis direction. The light distribution angular distribution in the x'-axis direction of the light fluxes reflected by the plurality of micro mirrors constituting the DMD 7 in the first direction is set to be smaller than the light distribution angular distribution in the z'-axis direction.

  FIG. 21 is a schematic view showing a result of calculation of illuminance distribution on the DMD 7 by ray tracing. The area surrounded by the black line is the effective area 17 of the DMD. In addition, the illuminance distribution is displayed by normalizing the maximum illuminance in the area as 1, that is, 100%. Also in the present embodiment, the DMD projection light flux can be made close to the shape of the effective area 17. That is, the light utilization efficiency of the DMD 7 can be improved.

  The average value of the ANSI 9 points of the effective area 17 (the illuminance at the center of each area when the effective area 17 is equally divided into 9 in vertical and horizontal directions) is 89.7%. That is, the illuminance distribution of the effective area 17 indicates that the distribution is uniform.

  According to the second embodiment of the present invention described above, the reflection surface of the second illumination mirror 205 is made axisymmetric polynomial aspheric, and the DMD projection light flux can be obtained by providing the characteristic as shown in FIG. The size and shape can be made close to the effective area 17 of the DMD 7. That is, the DMD loss is suppressed, and the projection surface can be brightly illuminated with a simple configuration.

  In addition, although the reflective surface of the 2nd illumination mirror shown in 2nd Embodiment was an aspheric surface represented by a polynomial of the axis asymmetrical represented by Numerical formula 3, the reflective surface shape is limited to this Instead, it may be an anamorphic surface such as a curved toroidal surface having a polynomial aspheric coefficient, for example.

  The embodiment described above is a projection type image display apparatus. However, the image display device according to the present invention is also applicable to a projector for displaying a video signal from a video reproduction device such as a personal computer, a television, a DVD player and the like.

1 light source 2 light tunnel 3 lens 4 first illumination mirror 5 second illumination mirror 7 DMD
Reference Signs List 8 projection optical system 18 illumination optical system 81 projection lens system 84 first projection mirror 85 second projection mirror 100 image display device 101 projection surface 200 illumination device

JP, 2004-184626, A Japanese Patent Application Publication No. 2002-268010

Claims (11)

Light source,
A light mixing element that forms a secondary light source by an image of a plurality of the light sources by a light flux from the light source;
An illumination optical system for projecting a light flux from the plurality of secondary light sources onto a light modulation element;
A lighting device having
The illumination optical system comprises an optical element having an anamorphic surface,
The optical element, as a rotation axis normal from the vertex of said anamorphic surface, Ri position near rotated relative to the optical modulator,
The luminous flux reflected by the light modulation element includes a first luminous flux reflected in the direction in which a projection optical system that projects the reflected luminous flux onto a projection surface is provided.
The rotation angle of the optical element with respect to the light modulation element with the normal axis from the top of the anamorphic surface as the rotation axis of the optical element is the light at the incident end of the first light beam of the projection optical system The light distribution angular distribution of the first light flux in the direction of the rotation axis of the plurality of micro mirrors included in the modulation element is smaller than the light distribution angular distribution of the first light flux in the direction orthogonal to the rotation axis of the micro mirror is there,
A lighting device characterized by Wherein the optical element is a mirror, according to claim 1 Symbol mounting lighting device. The lighting device according to claim 1 , wherein the anamorphic surface is a toroidal surface . The rotation angle of the optical element with respect to the light modulation element with the normal axis from the top of the anamorphic surface as the rotation axis of the optical element is effective for the light modulation element with respect to the light beam irradiated to the light modulation element. light beam reflected from the region is set to an angle of maximum illumination device according to any one of claims 1 to 3. The anamorphic surface is asymmetrical with respect to the normal line from the surface vertex, Ru aspheric der represented by a polynomial, the lighting device according to any one of claims 1 to 4. An area of a polygon formed by connecting a light condensing point on an imaginary plane on the same plane as the reflection surface of the light modulation element of the light flux projected from the vertex of the light mixing element is represented by SI.
When an area of a polygon in which the effective area is similarly reduced or expanded so that at least one vertex of the effective area of the light modulation element is inscribed in the polygon in the polygon is SD,
The angle of rotation, that is set to an angle SD / SI is maximized, the lighting device according to any one of claims 1 to 5. The illumination optical system includes a lens system and a flat mirror,
In the optical path of the light beam directed to the optical modulator from the light mixing element, said lens system, and the plane mirror, said optical elements are arranged in this order, according to any one of claims 1 to 6 Lighting device. The illumination device according to claim 7 , wherein the lens system is configured of one lens . A lighting device,
A light modulation element in which light from the lighting device is reflected in the direction of the projection optical system;
A projection optical system that projects a light flux from the light modulation element onto a projection surface;
An image display device having
The lighting device is a lighting device according to any one of claims 1 to 8,
An image display apparatus characterized by The projection optical system includes a projection lens system and a flat glass in this order in the optical path of the light flux from the light modulation element toward the projection surface,
The flat glass is disposed obliquely to a light beam passing through the projection lens system toward the projection surface,
When the projection surface is divided into a first area and a second area, the incident angle at which the light beam incident on the first area is incident on the flat glass is the light beam incident on the second area to the flat glass Less than the incident angle,
When an average illuminance on a reflective surface of the light modulation element of the light flux incident on the first region is L1, and an average illuminance on a reflective surface of the light modulation element of the light flux incident on the second region is L2, the anamol The image display according to claim 9, wherein the rotational angle of the optical element with respect to the light modulation element with respect to the light modulation element with the normal line from the surface apex of the Fick plane as the rotational axis of the optical element is L1 <L2. apparatus. When the second area is divided into a third area and a fourth area, the average illuminance of the light flux incident on the third area on the reflection surface of the light modulation element is L3, and the luminous flux of the light flux incident on the fourth area When the average illuminance on the reflection surface of the light modulation element is L4, the rotation angle of the optical element with respect to the light modulation element is L3 with the normal line from the top of the anamorphic surface as the rotation axis of the optical element. The image display device according to claim 10, wherein the image display device is disposed at a position where the difference between L and L4 is equal .