JP2005250072A - Illuminating optical system and image projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an illuminating optical system capable of effectively suppressing uneven illumination on an illuminated surface which may be generated by the decentering or the like of a light source. <P>SOLUTION: The illuminating optical system comprises first optical elements 3, 4 for dividing a beam from the light source into a plurality of beams in the first direction (Y axis direction) rectangular to the optical axis of the illuminating optical system and a second optical element for converging the plurality of beams in the second direction (Y axis direction) rectangular to the optical axis and the first direction. The illuminating optical system has reflection surfaces 6A, 6B (mirror 6) for reflecting a part of beams from the second optical element 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an illumination optical system that illuminates a surface to be illuminated such as an image forming element with a light beam from a light source, and an image projection apparatus including the illumination optical system.

  In an image projection apparatus that projects a light beam, which has been image-modulated using an image forming element such as a liquid crystal panel, onto a projection surface such as a screen by a projection lens, it is desirable that the projected image has uniform brightness throughout.

  An illumination optical system used in a general image projection apparatus collects a light beam emitted from a light source in all directions by a reflector and emits the light forward, and a plurality of the light beams are emitted by an optical integrator (a so-called fly-eye lens array). Is divided into a plurality of luminous fluxes, and the plurality of luminous fluxes are condensed to illuminate the image forming element which is the illuminated surface in a superimposed manner.

Furthermore, instead of the fly-eye type optical integrator, an optical integrator that is a lens array in which cylindrical lenses are arranged only in a one-dimensional direction is used to suppress the spread of the angular distribution in one cross-sectional direction of the light beam, thereby reducing the color separation and synthesis system. For example, Patent Document 1 proposes an illumination optical system that reduces color unevenness and improves contrast due to incident angle characteristics of thin film components (such as dichroic mirrors and polarizing beam splitters) used in the field.
JP-A-6-75200 (paragraph 0018, FIG. 1 etc.)

  However, in the optical system proposed in Patent Document 1, since the cylindrical lens array as an optical integrator does not illuminate the illuminated surface in a cross-sectional direction without refractive power, the illuminance on the image forming element It is difficult to make the distribution uniform. This is because the direction in which the superimposed illumination is not performed is to compress the light emitted from the light source as it is to illuminate the image forming element.

  For this reason, the optical system proposed in Patent Document 1 has a non-uniform brightness distribution as shown in FIG. In FIG. 18, the horizontal axis indicates the position in the direction (X direction) where the superimposed illumination is not performed on the surface to be illuminated, and the vertical axis indicates the brightness (illuminance).

  Here, if the light source (light emitting point) is at the focal position of the reflector (the intersection of the X axis and the Y axis) as shown in FIG. 4A, the distribution of the illumination light amount when viewed from the A direction in the figure is The distribution is symmetrical about the optical axis position (0 position) as shown in FIG. However, in practice, as shown in FIG. 5A, the light source often deviates (is decentered) from the focal position of the reflector. In this case, the optical axis position as shown in FIG. This results in an asymmetric light amount distribution. This causes a nonuniform brightness distribution as shown in FIG. Further, aberration due to the lens in the illumination optical system, manufacturing error of the light source lamp (the light emitting point position is deviated from a predetermined position with respect to the light source lamp, or the position of the lamp mounting position and the lamp light emitting point is predetermined For example), a change in the light emission position of the lamp over time, a change in the light emission distribution of the lamp over time, and the like.

  Therefore, the present invention provides an illumination optical system that can effectively suppress illuminance unevenness on a surface to be illuminated, which occurs due to eccentricity of a light source, manufacturing errors of a lamp, changes with time, and the like, an image projection apparatus using the same, and the like. The purpose is to provide.

  In order to achieve the above object, an illumination optical system as one aspect of the present invention includes a first optical beam splitting a light beam from a light source into a plurality of light beams in a first direction orthogonal to the optical axis of the illumination optical system. And a second optical element that condenses the plurality of light beams in a second direction orthogonal to the optical axis and the first direction. The illumination optical system has a reflecting surface that reflects a part of the light beam from the second optical element.

      According to the present invention, even if the light amount distribution of the light beam from the light source is asymmetric, the traveling direction of a part of the light beam can be controlled by the reflecting surface, so that uneven illuminance on the illuminated surface can be effectively suppressed. it can.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows the configuration of an illumination optical system that is Embodiment 1 of the present invention. In this illumination optical system, the optical action differs between the YZ cross section (FIG. 1A) and the XZ cross section (FIG. 1B).

  The Y-axis direction as the first direction represents the vertical direction, the X-axis direction as the second direction represents the left-right direction, and the Z-axis direction represents the optical axis direction. In addition, each lens in the present embodiment is configured by a single lens, but may be configured by a plurality of lenses.

  As shown in FIG. 1A, in the YZ section, the white light emitted from the light source lamp 1 is reflected by the reflector 2 and enters the first integrator 3 that is the first optical element. The first integrator 3 is configured by arranging a plurality of cylindrical lens cells 3a in the Y-axis direction. The first integrator 3 divides the light flux from the light source lamp 1 into a plurality of parts and the vicinity of the second integrator 4 by the plurality of divided light fluxes. A plurality of light source images are formed. The second integrator 4 has a plurality of cylindrical lens cells 4a corresponding to the individual cylindrical lens cells 3a of the first integrator 3, and each cylindrical lens cell 4a transmits the divided light beam that forms each light source image.

  The plurality of split light beams emitted from the second integrator 4 pass through a first light beam compression lens 5 as a second optical element, a condenser lens 7 as a third optical element, and a second light beam compression lens 8. Then, the image forming element 9 is illuminated. The image forming element 9 is constituted by a liquid crystal display panel or the like. The image forming element 9 forms an original image corresponding to image information supplied from an image information supply device IS such as a personal computer, a DVD player, a video player, or a TV tuner.

  Here, the first light beam compression lens 5 and the second light beam compression lens 8 do not have refractive power in the YZ section (Y-axis direction), and can be handled as simple glass blocks. Further, a mirror 6 is provided between the first light flux compression lens 5 and the condenser lens 7, but it does not have a reflecting effect on the YZ cross section.

  Each lens cell 3a of the first integrator 3 is conjugated to the image forming element 9 that is an illuminated surface by the action of each lens cell 4a of the second integrator 4 and the condenser lens 7. For this reason, the plurality of light source images are superimposed on the surface to be illuminated by the condenser lens 7.

  In the XZ cross section shown in FIG. 1B, B1 is a region above the optical axis L (region where the Y axis is positive), and B2 is a region below the optical axis L (region where the Y axis is negative). Show.

  In the region B <b> 1, white light emitted from the light source 1 is reflected by the reflector 2 and travels toward the first light flux compression lens 5 via the first integrator 3 and the second integrator 4. Here, in the XZ section (X-axis direction), the first integrator 3 and the second integrator 4 do not have refractive power and can be handled as a simple glass block.

  Fourthly, the light beam from the integrator 4 illuminates the image forming element 9 via the first light beam compression lens 5, the condenser lens 7 and the second light beam compression lens 8.

  Here, the first light beam compression lens 5, the condenser lens 7, and the second light beam compression lens 8 constitute a substantially afocal system that compresses a parallel light beam at a predetermined pupil magnification. The first light beam compression lens 5 condenses the light beam from the second integrator 4 in the X-axis direction.

  On the other hand, in the region B 2, the white light emitted from the light source 1 is reflected by the reflector 2 and travels toward the first light flux compression lens 5 via the first integrator 3 and the second integrator 4. The light beam that has been focused by the first light beam compression lens 5 is reflected by reflection surfaces provided on the left and right of the mirror 6, and further forms an image via the condenser lens 7 and the second light beam compression lens 8. The element 9 is illuminated.

  Here, the mirror 6 will be described in detail. The mirror 6 is disposed in a region including the focal position of the first light flux compression lens 5 in the region B2. The enlarged view is shown in FIG.

  The left and right surfaces of the mirror 6 are both reflecting surfaces 6A and 6B, and the reflecting surfaces 6A and 6B are arranged so as to sandwich the optical axis L. Each reflecting surface extends in the X-axis direction (the direction orthogonal to the lens cell arrangement direction of the first and second integrators 3 and 4) as the second direction orthogonal to the optical axis L and Y-axis directions. Has line n. Note that there may be a case where another mirror that reflects all the light beams is disposed between the first light beam compression lens 5 and the mirror 6 and the optical axis L is bent. It is assumed that the X, Y, and Z axis directions with respect to the optical axis L do not change at each of the above positions, and the direction of the normal line n does not change on a two-dimensional cross section including the normal line n.

  In the present embodiment, both reflection surfaces 6A and 6B of the mirror 6 are planes parallel to the optical axis L. Further, the mirror 6 has reflecting surfaces 6A and 6B formed on both sides of a thin transparent plate, and the light beam traveling on the optical axis L is transmitted through the transparent plate and enters the condenser lens 7.

  The operation of the mirror 6 will be described with reference to FIGS. FIG. 3A conceptually shows the behavior of the light beam when the periphery of the focal position of the first light beam compression lens 5 is viewed from the first light beam compression lens 5 side. Here, of the left and right regions sandwiching the optical axis L, the right region is defined as a first region I, and the left region is defined as a second region II. The upper region (corresponding to the region B1 in FIG. 1B) of the upper and lower regions sandwiching the optical axis L is defined as a third region III, and the lower region (corresponding to the region B2 in FIG. 1B). To be the fourth region IV.

  A light flux R3 traveling from the first light flux compression lens 5 through the region (3) which is the first region I and also the third region III, and the region (4 which is the second region II and also the third region III) The light beam R4 that travels through () is condensed near the focal position of the first light beam compression lens 5 and travels to the region on the opposite side in the left-right direction. That is, the region in which the light beam R3 travels and the region in which the light beam R4 travels are reversed in the left-right direction. These light beams R3 and R4 are incident on the condenser lens 7 shown in FIG.

  On the other hand, the light flux R1 that travels from the first light flux compression lens 5 to the region (1) that is the first region I and is also the fourth region IV, and the second region II and the fourth region IV. The light beam R <b> 2 traveling through a certain region (2) is condensed near the focal position of the first light beam compression lens 5. However, the light beam R1 is reflected by the reflecting surface 6A to the original region (1) side, and the light beam R2 is reflected by the reflecting surface 6B to the original region (2) side. For this reason, the region where the light beam R1 travels and the region where the light beam R2 travels are not reversed in the left-right direction. These light beams R 1 and R 2 are incident on the condenser lens 7.

  FIG. 3B conceptually shows a light beam that reaches the image forming element 9 due to a part of the light beam (light beams R1, R2) from the first light beam compression lens 5 being reflected by the mirror 6. FIG. Note that the first region I and the second region II in FIG. 3B are a right region and a left region across the optical axis L on the image forming element 9.

  The light fluxes R3 and R4 that have not been reflected by the mirror 6 reach the second region II and the first region I in the image forming element 9, respectively, because their traveling regions are inverted as described above. At this time, because of the action of the condenser lens 7, the light beams R3 and R4 are superimposed in the Y-axis direction.

  On the other hand, the light fluxes R1 and R2 reflected by the mirror 6 reach the first region I and the second region II in the image forming element 9, respectively, because their traveling regions are not reversed as described above.

  That is, the light beam R1 and the light beam R4 are incident on the first region I of the image forming element 9, and the light beam R2 and the light beam R3 are incident on the second region I. At this time, because of the action of the condenser lens 7, the light beams R1 and R2 are superimposed in the Y-axis direction.

  The operation of the illumination optical system configured as described above will be described in more detail.

  4A and 4B show the light emission distribution (light quantity distribution) of the lamp 1 when the light source lamp 1 is disposed at the focal position of the reflector 2. FIG. 4A shows a light emission distribution when the light source lamp 1 is viewed from the direction of arrow A in FIG. 4B, the horizontal axis indicates the position in the X-axis direction (0 is the optical axis position) in FIG. 4A, and the vertical axis indicates the amount of light.

  FIG. 4C shows the illuminance distribution on the image forming element 9 in the case of FIGS. 4A and 4B. The horizontal axis indicates the position in the X-axis direction on the image forming element 9, and the vertical axis indicates the illuminance. In FIG. 4C, the fine dotted line and the coarse dotted line are illuminance distributions by the light beam that has passed through the opening above the first light beam compression lens 5 (corresponding to the third region III in FIG. 3A). And the illuminance distribution by the light beam that has passed through the opening below the first light beam compression lens 5 (corresponding to the fourth region IV in the figure) is shown. However, in the drawing, a fine dotted line and a coarse dotted line are shown as being shifted up and down for easy understanding, but actually they overlap (that is, have the same illuminance distribution).

  As can be seen from FIG. 4C, when the light source lamp 1 is arranged at the focal position of the reflector 2, it enters the image forming element 9 from each of the upper opening and the lower opening of the first light flux compression lens 5. The illuminance distribution by the luminous flux is almost the same. Further, the first light beam compression lens may be aspherical. In addition, regarding at least one of the first and second integrators, as described in FIG. 15, some cylindrical lenses (one in FIG. 15, but a plurality of cylindrical lenses A to E) are arranged in the arrangement direction of the cylindrical lenses A to E. Preferably, it is one or more, and the refractive power may be given to the number of cylindrical lenses of the integrator minus 1 or less.

  Further, the first and second integrators use ordinary integrators (cylindrical lens arrays having cylindrical lenses A ′ to E ′) as shown in FIG. 16, and preferably between the light source and the first light flux compression lens (preferably the light source). 17 to the second integrator), by arranging a prism for refracting the light beam as shown in FIG. 17, the illuminance distribution of the light beam incident on the image forming element 9 is made substantially uniform (substantially bilaterally symmetric). can do. In this case, in FIG. 17, the first light beam splitting means (first integrator) is obtained by arbitrarily combining (i) to (xi) in the cross-sectional view in the YZ plane and accuses in the cross-sectional view in the XZ plane. And a prism.

  These act so as to make the light intensity more uniform on the image forming element (particularly with respect to a direction perpendicular to both the arrangement direction of the cylindrical lenses on the image forming element and the optical axis direction). The final illuminance distribution (shown by a solid line) on the final image forming element 9 resulting from the synthesis is also substantially uniform.

  On the other hand, FIGS. 5A and 5B show the light emission distribution (light quantity distribution) of the lamp 1 when the light source lamp 1 is shifted by 0.2 mm in the X-axis direction from the focal position of the reflector 2. FIG. 5A shows a light emission distribution when the light source lamp 1 is viewed from the direction of arrow A in FIG. 5B, the horizontal axis indicates the position in the X-axis direction (0 is the optical axis position) in FIG. 5A, and the vertical axis indicates the amount of light.

  FIG. 5C shows the illuminance distribution on the image forming element 9 in the case of FIGS. The horizontal axis indicates the position in the X-axis direction on the image forming element 9, and the vertical axis indicates the illuminance. In FIG. 5C, the fine dotted line and the coarse dotted line are the illuminance distributions by the light beam that has passed through the opening above the first light beam compression lens 5 (corresponding to the third region III in FIG. 3A). And the illuminance distribution by the light beam that has passed through the opening below the first light beam compression lens 5 (corresponding to the fourth region IV in the figure) is shown. However, in the drawing, a fine dotted line and a coarse dotted line are shown as being shifted up and down for easy understanding, but actually they overlap (that is, have the same illuminance distribution).

  As can be seen from FIG. 5C, when the light source lamp 1 is deviated from the focal position of the reflector 2, the light beam incident on the image forming element 9 from each of the upper opening and the lower opening of the first light beam compression lens 5. Since the illuminance distribution by is asymmetrical in the left-right direction and the biased side is the same, the final illuminance distribution (shown by a solid line) on the image forming element 9 resulting from their synthesis is also asymmetrical in the left-right direction.

  However, when the mirror 6 is arranged as in this embodiment, an illuminance distribution on the image forming element 9 as shown in FIG. 6 is obtained. Note that the horizontal and vertical axes in FIG. 6 are the same as those in FIGS. 4C and 5C, and the fine dotted lines indicate the upper part of the first light flux compression lens 5 (the third region in FIG. 3A). Illumination distribution due to the light beams R3 and R4 that have passed through the aperture III), and a rough dotted line represents the illuminance distribution due to the light flux R that has passed through each of the apertures in the lower part of the light beam compression lens 5 (fourth region IV in the figure) Yes.

  That is, the illuminance distribution by the light beams R3 and R4 that have passed through the upper opening of the first light beam compression lens 5 is the same as the illuminance distribution indicated by the fine dotted lines in FIG. The illuminance distribution by the light beams R1 and R2 that have passed through the lower opening of the light beam is opposite to the illuminance distribution by the light beams R3 and R4 with the optical axis position 0 as the center. Accordingly, the illuminance distribution by the total luminous fluxes R1 to R4, which is a combination of these, is substantially uniform (symmetrical) as shown by the solid line in FIG. This is equivalent to the case where the light source lamp 1 is at the focal position of the reflector 2 (FIGS. 4A to 4C).

  This illuminance distribution uniforming action can be obtained regardless of the position of the light source lamp 1 with respect to the focal position of the reflector 2. For this reason, even if the light emission distribution from the lamp 1 changes due to individual differences or temporal changes of the light source lamp 1, a uniform illuminance distribution is maintained on the image display element 9.

  In Example 1, although the case where the mirror 6 which has a reflective surface was arrange | positioned was demonstrated, you may provide a reflective surface in members other than a mirror.

  FIGS. 7A and 7B show an illumination optical system that is Embodiment 2 of the present invention. 7A and 7B are the same as the cross-sections and regions B1 and B2 in FIGS. 1A and 1B of the first embodiment. The same reference numerals as those in the first embodiment are given to the same components as those in the first embodiment, and the description is omitted.

  In this embodiment, an optical element 10 shown in detail in FIGS. 8A to 8C is arranged in place of the mirror 6 of the first embodiment.

  As for the optical element 10, the upper part (part arrange | positioned in area | region B1) is comprised by the transparent body 10E which functions as a mere glass block, and the lower part (part arrange | positioned in area | region B2) is as shown to FIG. 8 (B). The light beams R1 and R2 (same as the light beams R1 and R2 shown in FIG. 3A) are totally constituted by a pair of transparent bodies 10C and 10D provided with internal reflection surfaces 10A and 10B. The transparent bodies 10C and 10D (internal reflection surfaces 10A and 10B) are arranged with the optical axis L in between, and reflect a part of the light beam incident on the entire optical element 10.

  Further, a gap G is provided between the transparent bodies 10C and 10D. For this reason, the light beam traveling on the optical axis L passes through the gap G and enters the condenser lens 7.

  As shown in FIG. 8C, the optical element 10 can be made by adhering the transparent bodies 10C and 10D to the lower surface of the upper transparent body 10E with the cap G interposed therebetween. However, the manufacturing method is not limited to this.

  As shown in FIG. 8C, the surface H facing the optical path of the optical element 10 is a polished surface, and an antireflection film is formed there.

  Also in this embodiment, by providing the internal reflection surfaces 10A and 10B, the illuminance distribution on the image forming element 9 can be made substantially uniform on the same principle as in the first embodiment.

  Further, as a member having a reflective surface other than the mirror 6, a half mirror 11 may be used as shown in FIGS. 9 (A) and 9 (B). FIGS. 9A and 9B show an illumination optical system that is Embodiment 3 of the present invention. The cross sections in FIGS. 9A and 9B are the same as those in FIGS. 1A and 1B of the first embodiment, and constituent elements common to the first embodiment are the same as those in the first embodiment. The same reference numerals as in FIG.

  In the first embodiment, the mirror 6 is disposed only in the lower region B2. However, in this embodiment, the half mirror 11 that reflects a part of the incident light beam and transmits the remaining light beam is provided over both the upper and lower regions.

  When the half mirror 11 is used in this way, the illuminance distribution on the image forming element 9 can be made uniform as long as the transmitted light amount: reflected light amount = 1: 1 in the half mirror 11. However, in an actual half mirror, as shown in FIG. 10, the light beam b having a small incident angle has a higher transmission rate than the light beam a having a large incident angle (in the figure, affixed before a and b). 0.5, 0.8, and 0.2 indicate transmission and reflection ratios of the light beams a and b), and the ratio of transmission and reflection differs depending on the incident light. Therefore, the effect of uniforming the illuminance distribution tends to be low.

  However, since it is certain that the illuminance distribution of the light beam reflected by the half mirror 11 and the illuminance distribution of the light beam transmitted through the half mirror 11 are opposite to each other, the half mirror 11 is provided as shown in FIG. In this case, the illuminance unevenness on the image forming element 9 can be reduced as compared with the case where the half mirror 11 is not provided.

  Furthermore, an optical member 12 shown in FIGS. 12A and 12B may be used as a member having a reflective surface other than the mirror 6. 12 (A) and 12 (B) show an illumination optical system that is Embodiment 4 of the present invention. Each cross section in FIGS. 12A and 12B is the same as each cross section in FIGS. 1A and 1B of the first embodiment, and the same components as in the first embodiment are the same as in the first embodiment. The same reference numerals as in FIG.

  In the first embodiment, the mirror 6 is disposed only in the lower region B2, but in this embodiment, the reflective surface 12A that reflects the light beam and the transmission region 12B that transmits the light beam are alternately arranged in a vertical direction on a thin transparent body. The optical element 12 is provided over both the upper and lower regions.

  The reflection surface 12A is provided in the incident region of the light beam having a large influence on the illuminance unevenness on the image forming element 9, and the rest is defined as the transmission region 12B.

  A reflection surface such as a mirror absorbs light, though slightly, and there is a possibility that the brightness on the image forming element 9 is reduced accordingly. For this reason, in this embodiment, the reflection surface 12A is provided only in the incident region of the light beam having a large influence on the illuminance unevenness, and the others are used as the transmission region, thereby reducing the amount of absorbed light and reducing the brightness. It is relaxed.

  Even in the case of this embodiment, the effect of uniformizing the illuminance distribution is lower than in the first and second embodiments, but it is effective for alleviating the illuminance unevenness as in the third embodiment.

  In addition, the reflective element of this invention is not restricted to the reflective element shown to said each Example, What is necessary is just to have a reflective surface where a normal line extends in an X-axis direction.

  In each of the above-described embodiments, the case where the reflecting surface is a flat surface has been described. However, the reflecting surface has a curvature (that is, power) so that a part of the power required in the illumination optical system is shared by the reflecting surface. It may be. That is, the reflecting surface only needs to have a shape in which a normal line at at least one point extends in the X-axis direction.

  FIG. 14 shows the configuration of a display optical system used in a projector (image projection apparatus) that is Embodiment 5 of the present invention. The display optical system includes the illumination optical system described in the first to fourth embodiments (1 to 8: the illumination optical system of the first embodiment is shown as a representative example in the figure), the image forming element 9, and the image. The projection lens 13 is configured to project the light beam modulated by the forming element 9 onto a projection surface such as a screen.

  In this embodiment, only one image forming element 9 is shown. However, the light beam from the illumination optical system is color-separated between the illumination optical system and the plurality of image forming elements 9, and each image forming element is displayed. In this case, an optical system that synthesizes modulated light beams from the image forming elements may be arranged to constitute a display optical system capable of projecting a color image.

  Such a display optical system is mounted on the projector, and the image information supply apparatus IS shown in FIG. 1A is connected to the projector, whereby an image display system is configured.

(A), (B) is a block diagram of the illumination optical system which is Example 1 of this invention. FIG. 3 is an enlarged view of a mirror provided in the first embodiment. FIG. 3 is a conceptual diagram illustrating the behavior of a light beam in the first embodiment. (A), (B) is a figure which shows light quantity distribution in case a light source exists in the focus position of a reflector, (C) is a figure which shows illuminance distribution on an image forming element. (A), (B) is a figure which shows light quantity distribution in case a light source has shifted | deviated from the focus position of a reflector, (C) is a figure which shows illuminance distribution on an image forming element. FIG. 3 is a diagram illustrating the effect of a mirror in Example 1, and illustrating an illuminance distribution on an image forming element. (A), (B) is a block diagram of the illumination optical system which is Example 2 of this invention. (A)-(C) are the enlarged views of the optical element provided in Example 2. FIG. (A), (B) is a block diagram of the illumination optical system which is Example 3 of this invention. FIG. 6 is an enlarged view of a half mirror provided in Example 3. FIG. 10 is a diagram illustrating the effect of a half mirror in Example 3, and illustrating an illuminance distribution on an image forming element. (A), (B) is a block diagram of the illumination optical system which is Example 4 of this invention. FIG. 6 is an enlarged view of an optical element provided in Example 4. (A), (B) is a block diagram of the display optical system which is Example 5 of this invention. FIG. 3 is a perspective view showing an example of a cylindrical array in the first embodiment. FIG. 3 is a perspective view showing an example of a cylindrical array in the first embodiment. FIG. 3 is a diagram illustrating a configuration example of a prism in the first embodiment. The figure which shows the illumination intensity distribution on the image forming element by the conventional illumination optical system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source lamp 2 Reflector 3 1st integrator 4 2nd integrator 5 1st light beam compression lens 6 Mirror 7 Condenser mirror 8 2nd light beam compression lens 9 Image forming element 10, 12 Optical element 11 Half mirror 13 Projection lens

Claims (14)

An illumination optical system that illuminates a surface to be illuminated with a light beam from a light source,
A first optical element that divides a light beam from the light source into a plurality of light beams in a first direction orthogonal to the optical axis of the illumination optical system;
A second optical element for condensing the plurality of light beams in a second direction orthogonal to the optical axis and the first direction;
An illumination optical system comprising: a reflecting surface that reflects a part of the light beam from the second optical element.   The illumination optical system according to claim 1, further comprising a third optical element that superimposes the plurality of light beams from the second optical element on the illuminated surface. When two regions sandwiching the optical axis in the second direction are the first and second regions,
The reflection surface reflects a first light beam incident from the first region out of the partial light beams to the first region side, and reflects a second light beam incident from the second region to the first region. The illumination optical system according to claim 1, wherein the illumination optical system reflects the light toward the region 2 side.   The illumination optical system according to any one of claims 1 to 3, wherein the reflecting surface has a shape in which a normal line at at least one point extends in the two directions.   The illumination optical system according to claim 4, wherein the reflection surface is a plane whose normal extends in the direction of the two.   The illumination optical system according to claim 1, wherein at least two surfaces sandwiching the optical axis are provided as the reflection surfaces. When two regions sandwiching the optical axis in the first direction are the third and fourth regions,
The illumination optical system according to claim 1, wherein the reflection surface is disposed in one of the third and fourth regions. When two regions sandwiching the optical axis in the first direction are the third and fourth regions,
The illumination optical system according to claim 1, wherein the reflecting surface is disposed in both the third and fourth regions.   The illumination optical system according to claim 1, wherein the reflecting surface is formed on a mirror member.   The illumination optical system according to any one of claims 1 to 8, wherein the reflecting surface is formed on a part of a transparent body that transmits a light beam.   The illumination optical system according to claim 1, wherein the reflecting surface is formed on a half mirror member. A light source;
The illumination optical system according to any one of claims 1 to 11,
An image forming element illuminated by a light beam from the illumination optical system;
A display optical system comprising: a projection optical system that projects a light beam from the image forming element.   An image projection apparatus comprising the display optical system according to claim 12. An image projection device according to claim 13,
An image display system comprising: an image information supply device that supplies image information for forming an original image on the image forming element to the image projection device.

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