JP2006195500A - Illumination optical system and picture projecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination optical system preventing the occurrence of ghost light with simple constitution and a picture projecting device using the same. <P>SOLUTION: The illumination optical system for illuminating the display surface of a reflection type picture display element from an inclined direction to the normal of the display surface uses a rod integrator whose cross-sectional shape perpendicular to an optical axis is rectangular, and is equipped with a means for restricting luminous flux emitted from the emitting surface of the rod integrator so that an illumination area on the reflection type picture display element may be in the area of the window aperture part of the reflection type picture display element. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an illumination optical system for illuminating a reflective image display element and an image projection apparatus using the illumination optical system.

  In recent years, an image projection apparatus using a DMD (digital micromirror device) which is a reflection type image display element has attracted attention. The DMD has a display surface in which a large number of micromirrors are arranged in a matrix, and one micromirror constitutes one pixel of a display image. The inclination of the micromirrors is configured to be individually driven and controlled, and each micromirror can take two inclination states, an ON state and an OFF state. The illumination light is reflected into the projection optical system by the micromirror in the ON state, and the illumination light is reflected out of the projection optical system by the micromirror in the OFF state. Therefore, only the light reflected by the micromirror in the ON state reaches the projection surface (for example, the screen surface) by the projection optical system, and the target image is displayed on the projection surface.

  In an illumination optical system for illuminating the display surface of the DMD used in such an image projection apparatus, it is required to illuminate the display surface of the DMD with as uniform illuminance as possible. However, the light emitted from the light source device often has a non-uniform illuminance distribution. If such light is used as illumination light as it is, the brightness of the projected image will be uneven, which is not preferable. For this reason, such an illumination optical system generally includes a rod integrator for emitting light incident from the incident surface from the exit surface while increasing the uniformity of the in-plane illuminance distribution. The cross-sectional shape perpendicular to the optical axis of such a rod integrator is often a rectangle similar to the shape of the DMD display surface.

  However, such an illumination optical system for illuminating the display surface of the DMD normally irradiates illumination light from a direction inclined with respect to the normal line of the display surface. The shape of the exit surface is not as it is, but a shape extending in one direction according to the incident angle. For this reason, the illumination area is extended to the outside of the display surface of the DMD, which causes a reduction in illumination efficiency.

In order to prevent such a decrease in illumination light rate, an illumination optical system has been proposed in which the cross-sectional shape perpendicular to the optical axis of the rod integrator is not a rectangle but a special quadrilateral (see, for example, Patent Document 1). .)
JP 2001-42434 A

  As described above, in the illumination optical system for illuminating the display surface of the DMD, since the illumination light is normally irradiated from the direction inclined with respect to the normal line of the display surface, the illumination area extends in one direction, The illumination area extends beyond the display surface of the DMD.

  FIG. 11 is a schematic diagram of a DMD in a state of being illuminated by a conventional illumination optical system including a rod integrator having a rectangular cross-sectional shape perpendicular to the optical axis. 11A is a view of the DMD viewed from the front with the incident direction of the illumination light 1 on the right side, and FIG. 11B is a cross-sectional view taken along the line II of FIG. 11A.

  The DMD includes a window opening region 4 covered with window glass outside the display surface 3 on which micromirrors are arranged in a matrix. It was found that when the illumination area 5 by the illumination optical system spreads outside the window opening area 4, the light reflected from the protruding area (ghost source 6) is projected as ghost light. . It is difficult to completely remove such ghost light even if a matte black mask is provided outside the window opening region 4.

  The ghost light generated for such a reason is projected outside the projection screen, so that its presence is rarely recognized in the past, and has not been regarded as a problem. Recently, however, the image quality of projection devices has been improved, and home theater projectors for use in home theater rooms have been developed. In such applications, a very high level of display quality is required, and even if ghost light is projected outside the projection screen, the quality of the projector as a home theater is greatly impaired, which is a major problem. It has become. Furthermore, with the increase in the number of pixels of the DMD, an element having a smaller space between the display surface 3 and the window opening region 4 tends to be employed than before, so that the generation of such ghost light is prevented. Technology was desired.

  Here, as in the illumination optical system described in Patent Document 1, the cross-sectional shape perpendicular to the optical axis of the rod integrator is a special quadrilateral, and the shape of the illumination region 5 is brought close to the shape of the display surface 3 to thereby generate ghost light. It is also possible to prevent the occurrence of this.

  However, since it is difficult to manufacture a rod integrator having such a special cross-sectional shape and requires many steps, it is necessary to prepare rod integrators of various shapes according to the specifications of the image projection apparatus. It becomes a factor of big cost increase.

  The present invention has been made in view of the above technical problems, and an object of the present invention is to provide an illumination optical system that prevents the generation of ghost light with a simple configuration and an image projection apparatus using the same. That is.

  In order to solve the above problems, the present invention has the following features.

  1. A rod integrator for increasing the uniformity of the in-plane illuminance distribution and emitting the light incident from the incident surface from the exit surface, and the light beam emitted from the exit surface of the rod integrator as a window opening of the reflective image display element An illumination optical system for illuminating the display surface of the reflective image display element from a direction inclined with respect to the normal line of the display surface. The rod integrator has a rectangular cross-sectional shape perpendicular to the optical axis, and the illumination region of the reflective image display element is within the window opening region of the reflective image display element. An illumination optical system comprising means for limiting a light beam emitted from an emission surface.

  2. 2. The illumination optical system according to claim 1, further comprising: a light shielding member that covers a part of the exit surface in contact with or close to the exit surface of the rod integrator.

  3. The shape of the region of the exit surface of the rod integrator that is not covered by the light shielding member is a shape obtained by removing a region including one of the four corners of the rectangle or two corners that are diagonal from the rectangular region. 3. The illumination optical system according to 2, wherein

  4). 4. The illumination optical system according to claim 2, wherein the light shielding member has a function as a positioning reference in the optical axis direction of the rod integrator.

  5. A rod integrator for increasing the uniformity of the in-plane illuminance distribution and emitting the light incident from the incident surface from the exit surface, and the light beam emitted from the exit surface of the rod integrator as a window opening of the reflective image display element An illumination optical system for illuminating the display surface of the reflective image display element from a direction inclined with respect to the normal line of the display surface. The output of the rod integrator is such that the cross-sectional shape perpendicular to the optical axis of the rod integrator is a rectangle, and the illumination area of the reflective image display element is within the window opening area of the reflective image display element. The shape of the surface is a shape obtained by excluding an area including one of the four corners of the rectangle or two corners forming a diagonal from the rectangular area. An illumination optical system for.

  6). A rod integrator for increasing the uniformity of the in-plane illuminance distribution and emitting the light incident from the incident surface from the exit surface, and the light beam emitted from the exit surface of the rod integrator as a window opening of the reflective image display element An illumination optical system for illuminating the display surface of the reflective image display element from a direction inclined with respect to the normal line of the display surface. The cross-sectional shape perpendicular to the optical axis of the rod integrator is changed from the rectangular area to the rectangular 4 so that the illumination area in the reflective image display element is within the window opening area of the reflective image display element. An illumination optical system having a shape excluding a region including one of two corners or two diagonal corners, and the other corners having a right angle.

  7). A light source device, a reflective image display element that modulates illumination light, an illumination optical system according to any one of 1 to 6 for illuminating a display surface of the reflective image display element, and the reflective type An image projection apparatus comprising: a projection optical system for projecting light modulated by an image display element onto a projection surface.

  According to the present invention, by limiting the light beam emitted from the exit surface of the rod integrator, the illumination area of the reflective image display element can be accommodated in the window opening area of the reflective image display element, and ghost light It is possible to provide an illumination optical system that prevents the occurrence of the above with a simple configuration and an image projection apparatus using the illumination optical system.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 shows an optical configuration diagram of the image projection apparatus according to the first embodiment. This image projection apparatus includes a light source device 10, a color wheel 20, an illumination optical system 30, a prism unit 40, a DMD 50 as a reflective image display element, and a projection optical system 60. The illumination optical system 30 includes a rod integrator 31, a light shielding member 32, and a relay optical system 33.

  The light source device 10 includes a light source lamp 11, a reflector 12, and a condenser lens 13. As the light source lamp 11, a light source lamp generally used in an image projection apparatus, such as an ultra-high pressure mercury lamp or a metal halide lamp that emits white light, can be appropriately selected and used. The reflector 12 is a reflecting mirror having a paraboloid. Since the light source lamp 11 is disposed at the focal position of the paraboloid, the light beam emitted from the light source lamp 11 is reflected by the reflector 12 and then emitted as parallel light. The parallel light emitted from the reflector 12 is condensed near the incident surface of the rod integrator 31 by the condenser lens 13.

  The light source device 10 is not limited to the above-described configuration as long as the light emitted from the light source lamp 11 can be efficiently condensed near the incident surface of the rod integrator 31. For example, it is possible to adopt a configuration in which a reflecting mirror having an elliptical surface is used as the reflector, and the focused light emitted from the reflector is condensed near the incident surface of the rod integrator 31.

  The color wheel 20 is disposed on the incident surface side of the rod integrator 31, and the light emitted from the light source device 10 passes through the color wheel 20 before entering the rod integrator 31.

  FIG. 2 is a front view of the color wheel 20 as viewed from the light source device 10 side. The color wheel 20 includes three transmissive color filters 21R, 21G, and 21B, and rotates about a rotation shaft 22. The color filter 21R transmits only light in the red wavelength region, 21G transmits only light in the green wavelength region, and 21B transmits only light in the blue wavelength region. Since the color of the illumination light is sequentially switched by rotating the color wheel 20, the image information corresponding to each color is sequentially switched and displayed on the DMD, whereby the projection image can be colored. . The color filter is not limited to the combination of three colors of red, green, and blue, and other combinations capable of displaying a color image such as a combination of three colors of cyan, magenta, and yellow may be used.

  The color wheel 20 can be omitted when a monochrome image is projected or when an image projection apparatus having a DMD and an illumination optical system is provided for each color.

  The light that has passed through the color wheel 20 enters the rod integrator 31. The rod integrator 31 is a rod-shaped translucent member having a rectangular cross section perpendicular to the optical axis. By arranging the incident surface of the rod integrator 31 in the vicinity of the condensing point of the emitted light from the light source device 10, the efficiency of incidence on the rod integrator 31 can be increased. The light incident on the rod integrator 31 travels while repeating total reflection on its side surface. As a result, the uniformity of the in-plane illuminance distribution on the exit surface of the rod integrator 31 is improved.

  All four side surfaces of the rod integrator 31 are mirror-polished. As the material, translucent glass, plastic, or the like can be used as appropriate. However, since the temperature may rise due to strong illumination light, it is preferable to use a material having high heat resistance, such as glass. Although the cross-sectional shape of the rod integrator 31 is rectangular, it is preferable that the rod integrator 31 has a rectangular shape similar to the display surface 53 of the DMD 50 from the viewpoint of improving the illumination light rate. It can be square. Further, in order to prevent chipping and the like, small chamfering processing may be performed on four ridge lines parallel to the optical axis.

  Further, the rod integrator 31 can be formed by bonding four flat glass substrates coated with a reflection coating, with the surfaces coated with the reflection coating facing each other, instead of a rod-shaped member. Also in this case, the light that has entered the rod integrator 31 travels while being repeatedly reflected on the reflection-coated wall surface, and as a result, the uniformity of the in-plane illuminance distribution on the exit surface of the rod integrator 31 is enhanced.

  In the hollow rod integrator 31 formed by sticking the glass substrates in this way, the cross-sectional shape perpendicular to the optical axis refers to the cross-sectional shape of the reflection-coated wall surface. As in the case of the rod-shaped member, the cross-sectional shape perpendicular to the optical axis is a rectangle, but a rectangle similar to the display surface 53 of the DMD 50 is preferable.

  A light shielding member 32, a relay optical system 33, a prism unit 40, and a DMD 50 are disposed on the exit surface side of the rod integrator 31, and light emitted from the rod integrator 31 illuminates the DMD 50 through the relay optical system 33.

  The light shielding member 32 is for limiting the light beam emitted from the exit surface of the rod integrator 31 so that the illumination area in the DMD 50 is within the window opening area. The light shielding member 32 will be described in detail later.

  The relay optical system 33 is for guiding the light beam emitted from the emission surface of the rod integrator 31 to the display surface of the DMD 50. In the present embodiment, the display surface of the DMD 50 is uniformly illuminated by functioning together with the prism unit 40 and projecting the image of the exit surface of the rod integrator 31 onto the display surface of the DMD 50.

  FIG. 3 shows a configuration diagram of the prism unit 40. The prism unit 40 is for effectively separating illumination light to the DMD 50 and projection light reflected by the DMD 50, and includes a total reflection prism 41 and a transmission prism 42. The total reflection prism 41 has a first incident surface 43, a critical surface 44, and a first output surface 45, and the transmission prism 42 has a second incident surface 46 and a second output surface 47. The critical surface 44 of the total reflection prism 41 and the second incident surface 46 of the transmission prism 42 are disposed to face each other with an air layer 48 interposed therebetween. A plano-convex lens 49 that is a component of the relay optical system 33 is bonded to the first incident surface 43 of the total reflection prism 41.

  The illumination light from the relay optical system 33 enters the total reflection prism 41 from the first incident surface 43 via the plano-convex lens 49. The incident illumination light satisfies the total reflection condition and reaches the critical surface 44, where it is totally reflected, and then exits from the first exit surface 45 to illuminate the DMD 50.

  At this time, the illumination light is incident from a direction inclined with respect to the normal line of the display surface of the DMD 50. The inclination angle with respect to the normal line of the display surface is usually about 20 ° to 60 °.

  A large number of micromirrors are arranged in a matrix on the display surface of the DMD 50, and each micromirror is deflected by a predetermined angle (for example, 12 °) about the deflection axis, and takes two tilt states, an ON state and an OFF state. . The direction of the deflection axis of each micromirror is a direction of 45 ° with respect to the long side of the rectangle constituting the display surface of the DMD 50. The light reflected by the micromirror in the ON state (projection light 71) travels in the substantially normal direction of the display surface, enters the total reflection prism 41 from the first emission surface 45, and reaches the critical surface 44 again. However, since the projection light 71 does not satisfy the total reflection condition on the critical surface 44, it passes through the critical surface 44 and enters the transmission prism 42 from the second incident surface 46 through the air layer 48. The projection light 71 is further emitted from the second emission surface 47, enters the projection optical system 60, and is projected onto the screen surface. On the other hand, the light 72 reflected by the micromirror in the OFF state is not incident on the projection optical system 60 even after exiting the prism unit 40 because the reflection direction is deflected with respect to the projection light. Thus, only the projection light 71, which is the light reflected by the micromirror in the ON state, is projected onto the screen surface by the projection optical system 60, and the target image is displayed.

  In the present invention, the prism unit 40 is not necessarily an essential element, and the illumination light emitted from the rod integrator 31 may directly illuminate the DMD 50 via the relay optical system 33. In such a configuration, the inclination angle of the illumination light with respect to the normal of the display surface is further larger than in the configuration including the prism unit 40, and the extension of the illumination area is also increased.

  In addition, here, an image projection apparatus using a DMD in which the direction of the deflection axis of each micromirror is 45 ° with respect to the long side of the rectangle constituting the display surface has been described. The present invention is not limited, and the present invention can also be applied to DMDs having deflection axes in other directions.

  Furthermore, in the present invention, the reflective image display element is not limited to DMD, and other elements having the same function, such as a reflective liquid crystal display element, can also be used.

  Next, the light shielding member 32 in the present embodiment will be described in detail. The light shielding member 32 is for restricting the light beam emitted from the exit surface of the rod integrator 31 so that the illumination region in the DMD 50 is within the window opening region. It arrange | positions and covers the one part area | region of this output surface.

  As shown in FIG. 11, since the illumination light 1 is incident from a direction inclined with respect to the normal line of the display surface, the illumination area 5 by the illumination optical system that does not include the light shielding member 32 has one of two diagonal lines. It becomes an elongated rectangle. The illumination area 5 is a projection of the image of the exit surface of the rod integrator 31. Of the four corners of the illumination area 5, the optical path length from the position on the exit surface of the corresponding rod integrator 31 is the shortest. The illumination area 5 extends in the direction of the diagonal line that forms the corner and the longest corner. Ghost light is generated when one or both of the ends of the diagonal line thus extended spread outside the window opening region 4. That is, the ghost source 6 is the region including the shortest angle of the optical path length from the position on the exit surface of the corresponding rod integrator 31 among the four corners of the illumination region 5, or the shortest and longest corners. This is a region including two corners. Generation of ghost light can be prevented by blocking the luminous flux that should reach the ghost source 6 by the light shielding member 32 and placing the illumination area 5 in the window opening area 4.

  The light shielding member 32 may be any shape and size that can illuminate the entire surface of the display surface 3 and can block the light beam that should reach the ghost source 6. Since the illumination region 5 is a quadrangle in which one of the two diagonal lines extends, the shape of the region of the emission surface 34 of the rod integrator 31 that is not covered by the light shielding member 32 changes from the rectangular region to the rectangular shape 4. It is preferable to arrange the light shielding member 32 so as to have a shape excluding a region including one of the two corners or two corners forming a diagonal.

  FIG. 4 is a schematic view of the light shielding member 32 as viewed from the opposite side of the light source device 10. The wavy line in the figure indicates the exit surface 34 of the rod integrator 31. Each of the light shielding members 32a to 32e is formed by providing predetermined openings 39a to 39e on a circular flat plate.

  The light shielding member 32 a shields only the region including one corner of the four corners of the rectangle on the emission surface 34 of the rod integrator 31. That is, a region including the corner having the shortest optical path length with respect to the illumination position corresponding to each corner in the DMD 50 among the four corners of the exit surface 34 of the rod integrator 31 is defined as a light shielding region 35a.

  The relationship between the display surface 53 of the DMD 50, the window opening area 54, and the illumination area 55 at this time is shown in FIG. FIG. 5A is a diagram of the DMD 50 viewed from the front with the incident direction of the illumination light 51 on the right side, and FIG. 5B is a cross-sectional view taken along the line II in FIG. The luminous flux that should reach the ghost source 56 is blocked, and the illumination area 55 is accommodated in the window opening area 54, thereby preventing the generation of ghost light.

  The same effect can be obtained by using a light shielding member 32b in which a part of the light shielding region 35b is formed by a curve instead of the light shielding member 32a. Further, like the light shielding members 32c and 32d, two light shielding regions are provided, and the shape of the region of the exit surface 34 of the rod integrator 31 that is not covered by the light shielding member is changed from the rectangular region to the four corners of the rectangle. Of these, a shape excluding a region including two diagonal corners can be used. Like the light shielding member 32e, the opening 39e may be formed to be slightly smaller than the exit surface 34 of the rod integrator 31 over the entire circumference. However, it is preferable that the area of the light shielding region 35 is small from the viewpoint of the illumination light rate.

  The outer shape of the light shielding member 32 is not limited to a circular shape, and may be various shapes. In addition to the configuration in which the opening having a predetermined shape is provided, for example, as illustrated in FIG. 6, a configuration in which a rectangular light shielding member 32 f is fixed to a predetermined position on the emission surface 34 of the rod integrator 31 may be employed. . The material of the light shielding member 32 is not particularly limited as long as it is a non-translucent material, but a material having high heat resistance is preferable because the temperature may increase due to strong illumination light. For example, various metal plates and ceramic plates can be appropriately selected and used. In addition, even if there is reflected light from the light shielding member 32, it does not affect the projected light, so there is no need to reduce the reflection such as matte black dyeing.

  As described above, according to this embodiment, while using an inexpensive and versatile cross-section with a rectangular rod integrator, a part of the exit surface of the rod integrator is arranged so that the illumination area is within the window opening area of the DMD. By providing the light shielding member that covers the region, it is possible to provide an illumination optical system that prevents the generation of ghost light with a simple configuration and an image projection apparatus using the illumination optical system.

(Embodiment 2)
Next, an image projection apparatus according to a second embodiment of the present invention will be described. The optical configuration of the present embodiment is the same as the optical configuration of the first embodiment shown in FIG. The difference from the first embodiment is in the holding method of the rod integrator 31 and the light shielding member 32. FIG. 7 shows a holding state of the rod integrator 31 and the light shielding member 32 in the present embodiment.

  Generally, when assembling such an image projector, it is required to accurately position the rod integrator 31. In the present embodiment, the rod integrator 31 is disposed on an L-shaped holding member 36. The holding member 36 is provided with projections 37x and 37y for pressing the side surface of the rod integrator 31 for positioning. By pressing the side surface of the rod integrator 31 against the convex portions 37x and 37y, positioning in two directions perpendicular to the optical axis can be performed.

  A light shielding member 32g is fixed to the end of the holding member. The light shielding member 32g can be used as a positioning reference in the optical axis direction of the rod integrator 31 by pressing and fixing the emission surface of the rod integrator 31 to the light shielding region 35g of the light shielding member 32g. Normally, there is a possibility that the illumination light on the display surface of the DMD may be blocked when the exit surface of the rod integrator 31 is blocked. However, by giving the light blocking member 32 according to the present invention a function as a positioning reference in the optical axis direction, Positioning of the rod integrator 31 in the optical axis direction can be performed easily and accurately while preventing light generation with a simple configuration. When a rod-shaped member is used as the rod integrator 31, it has been difficult to provide a positioning reference in the direction of the optical axis in the related art, which is particularly effective.

(Embodiment 3)
Next, an image projection apparatus according to a third embodiment of the present invention will be described. FIG. 8 shows an optical configuration diagram of the present embodiment. The difference from the first embodiment shown in FIG. 1 is that the rod integrator is different and that the light shielding member is not provided, and the other configurations are the same.

  FIG. 9 shows a view of the rod integrator 31b in the present embodiment as viewed from the exit surface side. The rod integrator 31b is a rod-shaped translucent member having a rectangular cross-section perpendicular to the optical axis, and all four side surfaces are mirror-polished. The light that has entered the rod integrator 31b travels while repeating total reflection on its side surface, so that the uniformity of the in-plane illuminance distribution is enhanced and is emitted in the direction indicated by the arrow from the emission surface 34b.

  The shape of the exit surface 34b of the rod integrator 31b is a shape obtained by removing a region including one corner of the four corners of the rectangle from the rectangular region. Generation | occurrence | production of a ghost light can be prevented by making the output surface 34b of the rod integrator 31b into this shape, and making the illumination area | region in DMD50 fit in a window opening part area | region.

  Such a rod integrator 31b can be easily manufactured by, for example, once manufacturing a rod-shaped member having a rectangular cross section and then removing one of the corners of the emission surface 34b. The removal portion 38b may have a planar shape as shown in FIG. 9 or a curved shape. Further, only one of the corners of the emission surface 34b may be removed, or two corners that are opposite to each other may be removed.

(Embodiment 4)
Next, an image projection apparatus according to a fourth embodiment of the present invention will be described. The optical configuration of this embodiment is the same as the optical configuration of the third embodiment shown in FIG. The difference from the third embodiment is that the rod integrator is different.

  FIG. 10 shows a view of the rod integrator 31c in the present embodiment as viewed from the exit surface side. The light incident on the rod integrator 31c repeats total reflection on its side surface and is emitted from the emission surface 34c in the direction indicated by the arrow. The cross-sectional shape perpendicular to the optical axis of the rod integrator 31c is a shape obtained by removing a region including one corner from the four corners of the rectangle so that the illumination region in the DMD 50 is within the window opening region. And the angle of the other three angles is a right angle. Generation of ghost light can be prevented by using such a rod integrator 31c.

  Such a rod integrator 31c can be easily manufactured by, for example, once manufacturing a rod-shaped member having a rectangular cross section and then chamfering one of the ridge lines parallel to the optical axis. The removal portion 38c by chamfering may have a planar shape as shown in FIG. 10 or a curved shape. Further, the chamfering process may be performed on only one of the ridge lines parallel to the optical axis, or the chamfering process may be performed on two diagonal ridge lines. Further, from the viewpoint of preventing the light passing through the rod integrator 31c from being attenuated by the removing unit 38c, the removing unit 38c is preferably mirror-finished.

Optical configuration diagram of image projection apparatus in first and second embodiments Front view of the color wheel 20 Configuration diagram of prism unit 40 Schematic diagram of the light shielding member 32 Schematic diagram of the DMD in a state illuminated by the illumination optical system in the first embodiment Schematic diagram of another light shielding member 32 The figure which shows the holding | maintenance state of the rod integrator 31 and the light-shielding member 32 in 2nd Embodiment. Optical configuration diagram of image projection apparatus in third and fourth embodiments Schematic diagram of the rod integrator 31b in the third embodiment Schematic diagram of the rod integrator 31c in the fourth embodiment Schematic diagram of DMD illuminated by a conventional illumination optical system

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,51 Illumination light 3,53 DMD display surface 4,54 DMD window opening area 5,55 Illumination area 6,56 Ghost source 10 Light source device 11 Light source lamp 12 Reflector 13 Condenser lens 20 Color wheel 30 Illumination optical system 31 Rod integrator 32 Light shielding member 33 Relay optical system 34 Light exit surface of rod integrator 35 Light shielding area by light shielding member 38 Rod integrator removal part 39 Light shielding member opening 40 Prism unit 41 Total reflection prism 42 Transmission prism 50 DMD
60 Projection optics

Claims (7)

A rod integrator for increasing the uniformity of the in-plane illuminance distribution and emitting the light incident from the incident surface from the exit surface;
A relay optical system for guiding the light beam emitted from the exit surface of the rod integrator to a display surface located inside the window opening region of the reflective image display element;
In an illumination optical system for illuminating the display surface of the reflective image display element from a direction inclined with respect to the normal line of the display surface,
The cross-sectional shape perpendicular to the optical axis of the rod integrator is a rectangle,
And a means for limiting a light beam emitted from the exit surface of the rod integrator so that an illumination area in the reflective image display element is within the window opening region of the reflective image display element. Lighting optical system. The illumination optical system according to claim 1, further comprising: a light shielding member that covers a part of the exit surface in contact with or close to the exit surface of the rod integrator. . The shape of the region of the exit surface of the rod integrator that is not covered by the light shielding member is a shape obtained by removing a region including one of the four corners of the rectangle or two corners that are diagonal from the rectangular region. The illumination optical system according to claim 2, wherein: The illumination optical system according to claim 2, wherein the light shielding member has a function as a positioning reference in the optical axis direction of the rod integrator. A rod integrator for increasing the uniformity of the in-plane illuminance distribution and emitting the light incident from the incident surface from the exit surface;
A relay optical system for guiding the light beam emitted from the exit surface of the rod integrator to a display surface located inside the window opening region of the reflective image display element;
In an illumination optical system for illuminating the display surface of the reflective image display element from a direction inclined with respect to the normal line of the display surface,
The cross-sectional shape perpendicular to the optical axis of the rod integrator is a rectangle,
The shape of the exit surface of the rod integrator is changed from the rectangular area to the four corners of the rectangle so that the illumination area in the reflective image display element is within the window opening area of the reflective image display element. An illumination optical system characterized by having a shape excluding an area including one or two diagonal corners. A rod integrator for increasing the uniformity of the in-plane illuminance distribution and emitting the light incident from the incident surface from the exit surface;
A relay optical system for guiding the light beam emitted from the exit surface of the rod integrator to a display surface located inside the window opening region of the reflective image display element;
In an illumination optical system for illuminating the display surface of the reflective image display element from a direction inclined with respect to the normal line of the display surface,
The cross-sectional shape perpendicular to the optical axis of the rod integrator is changed from the rectangular area to the four rectangular areas so that the illumination area in the reflective image display element is within the window opening area of the reflective image display element. An illumination optical system having a shape excluding a region including one of the corners or two diagonal corners, and the other corners having a right angle. A light source device;
A reflective image display element for modulating illumination light;
The illumination optical system according to any one of claims 1 to 6, for illuminating a display surface of the reflective image display element;
A projection optical system for projecting modulated light from the reflective image display element onto a projection surface;
An image projection apparatus comprising:

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