Patent Publication Number: US-2022236630-A1

Title: Light source device, projector and light intensity distribution uniformization method

Description:
TECHNICAL FIELD 
     The present invention relates to a light source device, a projector including the light source device and a light intensity distribution uniformization method for uniformizing the intensity distribution of light irradiated from the light source device to a specific irradiated surface. 
     BACKGROUND OF THE INVENTION 
     In a projector for projecting a color image, a system is known in which white light emitted from a light source is separated into three primary colors of red, green and blue using a dichroic mirror or a color wheel that rotates at a high speed, and a color image is formed by optical modulating according to a video signal for each separated color light. Liquid crystal panels or DMDs (Digital Micromirror Device) are used for image forming devices used for optical modulating. 
     In the above-described projector, conventionally, a configuration in which a high brightness discharge lamp or the like is used as a light source is mainly used. However, in recent years, in order to extend product life and low power consumption of a light source, a projector using a semiconductor device such as a laser diode (hereinafter, referred to as LD) or an LED (Light Emitting Diode) as the light source has been developed. 
     When a semiconductor device is used as a light source, usually because the semiconductor device can only emit a single wavelength light, there is a configuration in which the color light emitted from the light source irradiates to a phosphor as excitation light and the colored lights not directly obtained from the light source are emitted by the phosphor, respectively. For example, when a blue LD that emits laser light having a peak wavelength in a blue wavelength region is used as a light source, red light and green light are emitted by using the phosphors. In some projectors, there is a configuration in which individual phosphors that emit red and right are not used but a phosphor that emits yellow light including red and green components is used. The yellow light, or the red light and the green light emitted by the phosphors are synthesized with the blue light emitted from, for example, the blue LD to convert into white light which is used as illumination light for irradiating the image forming device. 
     In the configuration using the LD in the light source described above, in order to output a higher brightness light from the light source, it is sufficient to increase the light output (optical power) by increasing the number of LDs. In general, the laser light emitted from the LD is a shape extending in an elliptical cone shape, a cross section perpendicular to the optical axis becomes an elliptical shape having a narrow width in the short axis direction. For example, when a plurality of LDs arranged in a lattice pattern is used, a plurality of light source images formed by each laser light is shown in  FIG. 10 . 
     When light from a light source having such a non-uniformity intensity distribution is used, for example, as excitation light for irradiating a phosphor, the luminous efficiency of the phosphor is lowered. Generally, it is known that the luminous efficiency of a phosphor depends on the temperature, and the luminous efficiency decreases when the temperature is high. Therefore, when excitation light having a peak local to the intensity distribution of light is irradiated to the phosphor, the temperature rises at the portion irradiated with the peak light, and light having a low intensity is irradiated at the other portion, so that the luminous efficiency of the phosphor is lowered. 
     Furthermore, when illumination light including light from a light source having a non-uniform intensity distribution is irradiated to the image forming device, it causes color unevenness and luminance unevenness in the projected image. 
     Therefore, in a projector using LD as a light source, it is necessary to convert the light from the light source having a non-uniform intensity distribution into light having a uniform intensity distribution at a specific irradiated surface. 
     As a method of making uniform the light intensity distribution in the irradiated surface, a method of using a diffusion plate, a method of using a rod integrator or a light tunnel, a method of using a microlens array or the like is known. For example, Patent Document 1 describes a configuration in which the intensity distribution of illumination light irradiated from a light source having an LD to an image forming device is made uniform by using a microlens array. 
     RELATED ART DOCUMENTS 
     Patent Documents 
     Patent Document 1: JP 2016-062038 A 
     SUMMARY 
     Problem to be Solved by the Invention 
     The microlens array is a configuration which comprises a plurality of microlenses (hereinafter, referred to as cells) arranged in two directions orthogonal to each other. As shown in  FIG. 11A , on the irradiated surface of the microlens array, if the cells that have sufficiently small with respect to the size of each light source image formed by the laser light are formed, it is possible to increase the uniformity of the light illumination intensity distribution in the irradiated surface as shown in  FIG. 11B . However, when the cells are small, edge sagging occurs at the time of manufacture, and the ratio of the ridge line portions formed between the cells increases with the increase in the number of cells. Since the light passing through such the ridge line portions are not subjected to a lens effect, the light utilization efficiency is lowered in the microlens array having the small cells. That is, there is a limit in the manufacturing in the miniaturization of the cells of the microlens array. 
     As described above, the light source image of the laser light emitted from the LD is elliptical having a narrow width in the short axis direction. When a microlens array having large cells at a certain level with respect to the size of the light source image is used as shown in  FIG. 12A , the uniformity of the intensity distribution of light caused by the shape of the light source image in the irradiated surface is reduced as shown in  FIG. 12B . This becomes more pronounced as the cells become larger for the size of the light source image on the irradiated surface of the microlens array. 
     Patent Document 1, when the coherent laser light is incident on the microlens array, the interference fringes are formed on the microlens array, points out a problem in which the interference fringes are superimposed on the same position on the image forming device to become an interference fringe pattern, and proposes a configuration for reducing the occurrence of the interference fringe pattern. The art described in Patent Document 1 does not improve the non-uniformity of the light intensity distribution on the irradiated surface caused by the shape of the light source image. 
     The present invention has been made to solve the problems of the background art as described above, it is an object of the present invention to provide a light source device, a projector and a light intensity distribution uniformization method that can improve the non-uniformity of the light intensity distribution in a particular irradiated surface caused by the shape of the light source image. 
     Means for Solving the Problems 
     In order to achieve the above object, the light source device of an exemplary aspect of the present invention is a light source device for generating laser light that is irradiated to a microlens array, comprising a plurality of microlenses arranged in two directions orthogonal to each other, comprising: 
     a plurality of light sources that emits laser light, wherein: 
     the light source image of the light source on the irradiated surface of the microlens array is elliptical; and 
     the long axis direction of the light source image intersects with both the two directions. 
     The projector of an exemplary aspect of the present invention is a projector comprising: 
     the above light source device; 
     an optical modulating unit that forms an image light by optical modulating the light emitted from the light source device according to a video signal; and 
     a projection optical system that projects an image light formed by the optical modulating unit. 
     An exemplary aspect of the light intensity distribution uniformization method of the present invention is a light intensity distribution uniformization method for uniformizing the intensity distribution of light that is irradiated a specific irradiated surface from a light source device that comprises a plurality of microlenses arranged in two directions orthogonal to each other, for generating laser light that is irradiated a microlens array, 
     wherein light source device comprises a plurality of light sources that emits laser light, 
     wherein the light source image of the light source on the irradiated surface of the microlens array is elliptical, the light intensity distribution uniformization method comprising the steps of: 
     arranging the light source so that the long axis direction of the light source image intersects with both the two directions; and 
     irradiating the specific irradiated surface with the light emitted from the microlens array. 
     According to the present invention, it is possible to improve the non-uniformity of the light intensity distribution on a specific irradiated surface caused by the shape of the light source image. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram showing an example of a configuration of a light source device included in a projector. 
         FIG. 2  is a schematic view showing an example of a configuration of an illumination projection optical system shown in  FIG. 1 . 
         FIG. 3A  is a schematic diagram showing an example of the relationship between the light source image and the microlens array of the first exemplary embodiment. 
         FIG. 3B  is a schematic diagram showing an example of the light intensity distribution of the irradiated surface in the relationship between the light source image and the microlens array shown in  FIG. 3A . 
         FIG. 4A  is a schematic diagram showing another relationship example of the light source image and the microlens array of the first exemplary embodiment. 
         FIG. 4B  is a schematic diagram showing an example of the light intensity distribution of the irradiated surface in the relationship between the light source image and the microlens array shown in  FIG. 4A . 
         FIG. 5  is a graph showing an example of the peak intensity of light in the irradiated surface with respect to the rotation angle of the light source image. 
         FIG. 6A  is a schematic diagram showing an example of a definition of the size of the light source image. 
         FIG. 6B  is a schematic diagram showing an example of a definition of the size of the cell included in microlens array. 
         FIG. 7  is a schematic diagram showing another configuration example of a light source device included in the projector. 
         FIG. 8  is a schematic diagram showing an arrangement example of a light source image obtained by the light source device shown in  FIG. 7 . 
         FIG. 9A  is a schematic diagram showing an example of the relationship between the light source image and the microlens array of the third exemplary embodiment. 
         FIG. 9B  is a schematic diagram showing an example of the light intensity distribution of the irradiated surface in the relationship between the light source image and the microlens array shown in  FIG. 9A . 
         FIG. 10  is a schematic diagram showing an example of a light source image formed by a laser light. 
         FIG. 11A  is a schematic diagram showing an example of the relationship between the light source image and the microlens array of the background art. 
         FIG. 11B  is a schematic diagram showing an example of the light intensity distribution of the irradiated surface in the relationship between the light source image and the microlens array shown in  FIG. 11A . 
         FIG. 12A  is a schematic diagram showing another example of the relationship between the light source image and the microlens array of the background art. 
         FIG. 12B  is a schematic diagram showing an example of the light intensity distribution of the irradiated surface in the relationship between the light source image and the microlens array shown in  FIG. 12A . 
     
    
    
     EXEMPLARY EMBODIMENT 
     Next, the present invention will be described with reference to the accompanying drawings. 
     First Exemplary Embodiment 
       FIG. 1  is a schematic diagram showing an example of a configuration of a light source device included in a projector,  FIG. 2  is a schematic diagram showing an example of a configuration of an illumination projection optical system shown in  FIG. 1 . 
       FIGS. 1 and 2  illustrate an example of an optical system included in a projector, and the number of lenses, mirrors and the like is not limited to the number shown in  FIGS. 1 and 2 , may be increased or decreased as necessary.  FIG. 1  shows a configuration example of irradiating a laser light emitted from the LD to a ring-shaped phosphor fixed on the phosphor wheel rotating at a high speed as excitation light. The phosphor is not limited to a configuration in which it is fixed on the phosphor wheel, and may be fixed to a predetermined portion that does not have a rotation mechanism or a movement mechanism. 
     The light source device shown in  FIG. 1  includes a plurality of LDs  11 , a plurality of collimator lenses  1   a,  lenses  1   b,    1   c,    1   d  and  1   e,  two sets of microlens arrays  12  and  13 , phosphor wheel  14 , dichroic mirror  15 , and a color synthesis system  16 . Although four light sources (LD  11 ) are shown in  FIG. 1 , any number of LDs  11  may be used as long as the number is one or more. The plurality of light sources includes a case where the laser light emitted from the LD is divided into a plurality of light sources. 
     The laser lights emitted from a plurality of LDs  11  are converted into parallel luminous flux, respectively by the collimator lens  1   a,  the converted lights are condensed by lens  1   b  and  1   c,  and are incident on microlens array  12  and  13 . Light emitted from microlens array  13  is condensed by the lens  1   d  and is incident on dichroic mirror  15 . 
     Microlens array  12  which is the incident side divides the light flux of the incident light, microlens array  13  which is the emitting side forms an image each divided light flux on the irradiated surface, microlens arrays  12  and  13  thereby convert the intensity distribution the incident light into uniform light at a predetermined irradiated surface. 
     Microlens arrays  12  and  13  are configured to include a plurality of cells arranged in two directions orthogonal to each other. Each of the plurality of cells has a square shape or a rectangular shape, and is arranged in a lattice pattern or a staggered shape, for example. The lens included in each cell is a plano-convex lens or a biconvex lens, the lens shape may be square, rectangular or circular. If each cell is formed by a plano-convex lens, the convex surface may be the incident surface side of the light or may be the emitting surface side of the light. When providing the convex surface to the incident surface side and the emitting surface side of the light, respectively, two microlens arrays  12  and  13  may be integrally formed. The shape of microlens arrays  12  and  13  may match the shape of the irradiated surface and may be square, rectangular or circular. The size of microlens arrays  12  and  13  may be the size to be incident all the light source image formed by a laser light emitted from a plurality of LDs  11 . 
     Dichroic mirror  15 , for example, has a characteristic of passing through a wavelength light longer than a predetermined wavelength, and reflecting a wavelength light shorter than the predetermined wavelength. In the specification, it is assumed that dichroic mirror  15  reflects the laser light (excitation light) emitted from LD  11  and passes through the light emitted by the phosphor on phosphor wheel  14 . Light (excitation light) which is incident on dichroic mirror  15  is reflected in the direction of phosphor wheel  14 , is condensed by lens  1   e,  and is irradiated to the phosphor on phosphor wheel  14 . 
     Phosphor wheel  14  emits light (e.g., yellow light) having wavelengths different from those of the excitation light (e.g., blue light) from the excitation light (e.g., blue light) emitted from LD  11 . Phosphor wheel  14 , by rotating at a high speed by a motor (not shown), reduces the temperature rise of the phosphor by moving the irradiated position of the excitation light, and efficiently cools the phosphor. The light emitted by the phosphor passes through the lens  1   e,  and is incident on dichroic mirror  15 , and passes through dichroic mirror  15 . 
     In the first exemplary embodiment, since white light is emitted from the light source device, color light which is insufficient for the synthesis of white light and which is different from the color light emitted by the phosphor is generated by color synthesis system  16 . For example, when yellow light is emitted by a phosphor, blue light may be emitted by color synthesis system  16 . In this case, color synthesis system  16  may be configured to include a blue LD, a diffusion plate for diffusing the laser light emitted from the blue LD, a lens or the like for irradiating dichroic mirror  15  by condensing the light emitted from the diffusion plate. If it is provided with a configuration for making uniform the intensity distribution of light emitted from the light source device to the illumination projection optical system  17  to be described later, the diffusion plate may not be used. The color light used for the synthesis of the white light may be the same color light as the laser light emitted from LD  11 , and the laser light emitted from LD  11  may be used for the synthesis of the white light. 
     Light emitted from color synthesis system  16  is reflected by dichroic mirror  15  and is synthesized with light that is passed through dichroic mirror  15  and that is emitted by the phosphor, and the synthesize light is output from the light source device. 
     Light (white light) emitted from the light source device is optical modulated for each of the three primary colors of red, green and blue light according to the video signal, and is incident on the illumination projection optical system  17  that projects the image lights formed by the optical modulation. 
     As shown in  FIG. 2 , the illumination projection optical system  17  includes illumination optical system  2 , optical modulating unit  3 , and projection optical system  4 .  FIG. 2  shows a configuration example of an illumination projection optical system  17  using a liquid crystal panel as an image forming device included in optical modulating unit  3 . The present invention is also applicable to a configuration in which the DMD is used as an image forming device. 
     Illumination optical system  2  includes integrator  2   a,  polarizing beam splitter  2   b,  lens  2   c,  first dichroic mirror  2   d,  second dichroic mirror  2   e,  first relay lens  2   f,  first mirror  2   g,  second relay lens  2   h,  third relay lens  2   i,  second mirror  2   j,  fourth relay lens  2   k  and third mirror  2   m.    
     Integrator  2   a  converts the light emitted from the light source device into light having a uniform intensity distribution in the irradiated surface (liquid panel surface). For example, a pair of two fly-eye lenses may be used as integrator  2   a.  The fly-eye lens has a configuration in which a plurality of microlenses (cells) are arranged in two directions orthogonal to each other, and is similar to microlens arrays  12  and  13 . 
     Polarizing beam splitter  2   b  uniforms polarization of light emitted from integrator  2   a  and outputs the light. Light output from polarizing beam splitter  2   a  is incident on first dichroic mirror  2   d  by lens  2   c.    
     First dichroic mirror  2   d,  for example, passes through green light and blue light and reflects red light. Red light reflected by first dichroic mirror  2   d  is incident on first mirror  2   g  by first relay lens  2   f,  and is incident on optical modulating unit  3  by reflecting first mirror  2   g.  Green light and blue light passed through first dichroic mirror  2   d  are incident on second dichroic mirror  2   e  by second relay lens  2   h.    
     Second dichroic mirror  2   e,  for example, passes through blue light and reflects green light. Green light reflected by second dichroic mirror  2   e  is incident on optical modulating unit  3 . Blue light passed through second dichroic mirror  2   e  is incident on second mirror  2   j  by third relay lens  2   i.    
     Second mirror  2   j  reflects the blue light which is incident, the reflected blue light is incident on third mirror  2   m  by fourth relay lens  2   k.  Third mirror  2   m  is incident on optical modulating unit  3  by reflecting the blue light which is incident. 
     Optical modulating unit  3  includes liquid crystal panel  3   a  which is an image forming device, polarizing plate  3   b  and cross prism  3   c.    
     Each color light separated by illumination optical system  2  is incident through polarizing plate  3   b  to liquid crystal panel  3   a  prepared for each R (red)/G (green)/B (blue), respectively and is optical modulated based on the video signal. Each color light (image light) formed by being optical modulated is synthesized by cross prism  3   c,  and is projected as an image on a screen or the like (not shown) through projection optical system  4  having projection lens  4   a.    
     In such a configuration, the present invention uniforms intensity distribution of light on a specific irradiated surface by arranging the light source and the microlens array so that the long axis direction of the light source image formed by the laser light on the irradiated surface of the microlens array intersects with the direction in which the cells are aligned. 
     For example, a coordinate system is set which includes: a first axis parallel to a principal ray of laser light incident on the microlens array; a second axis, in the direction in which the laser light emitted from the microlens array or the fluorescence emitted from the phosphor is reflected, in a direction orthogonal to the first axis; and a third axis orthogonal to the first axis and the second axis, respectively. In the example shown in  FIG. 3A , for example, the first axis is the Z axis, the second axis is the X axis, and the third axis is the Y axis. Then, in the first exemplary embodiment, the microlens array are arranged so that the two directions in which the cells are aligned are parallel to the direction of the second axis and the direction of the third axis. 
     Hereinafter, the direction in which the cells are arranged may be referred to as a “direction of boundary line of a cell”. In the following, the present specification will be described in an example in which the LD and the microlens array are arranged so that the long axis direction of the light source image and the boundary lines or the diagonal lines of the cells are intersected. The LD and the microlens array may be arranged so that the short axis direction of the light source image and the boundary lines or the diagonal lines of the cells are intersected. 
     As shown in  FIG. 1 , when the intensity distribution of the excitation light irradiated to the phosphor is uniformed, microlens arrays  12  and  13  are arranged so that the boundary lines of the plurality of cells are along the X-axis shown in  FIG. 3A . Then, each of LD  11  is placed so that the direction of the boundary lines of the cells of microlens array  12  and  13  and the long axis direction of the light source image are intersected. 
     On the other hand, as shown in  FIG. 2 , when the intensity distribution of the illumination light irradiated to the liquid crystal panel  3   a  (image forming device) is uniformed, a microlens array (integrator  2   a ) is arranged so that the boundary lines of the plurality of cells are along the X-axis shown in  FIG. 3A  to arrange. Then, each LD which is included in color synthesis system  16  is arranged so that the direction of the boundary lines of the cells of the microlens array (integrator  2   a ) and the long axis direction of the light source image are intersected. 
     As shown in  FIG. 12A , when the direction of the boundaries of the cells and the long and short axis directions of the light source images which are incident on the microlens array are parallel, the light from the light source is relatively uniformly which is incident on each cell. In that case, since the light having the same intensity distribution from each cell is output, in the irradiated surface (imaging surface), caused by the elliptical light source image, the light having the non-uniformity intensity distribution emitted from each cell is superimposed. Consequently, bias occurs in the intensity distribution of light in the irradiated surface as shown in  FIG. 12B . 
     On the other hand, as shown in  FIG. 3A , when the direction of the boundary lines of the cells, and the long axis direction and the short axis direction of the light source image are intersected, the light from the light source is never uniformly incident on a plurality of adjacent cells. In such cases, since light having different intensity distributions is emitted from the respective cells, the light intensity distributions on the irradiated surface become uniform as shown in  FIG. 3B  by superimposing the light intensity distributions on the irradiated surface. 
     As shown in  FIG. 4A , even if the long axis direction and the short axis direction of the light source image incident on the diagonal direction and the microlens array of each cell are parallel, the light source light is uniformly incident on each cell. As a result, the uniformity of the light intensity distribution on the irradiated surface decreases as shown in  FIG. 4B . Therefore, it is desirable that each LD is arranged so that the long axis direction of the light source image intersects with not only the direction of the boundary lines of the cells, also with respect to the direction of the diagonal lines of the cells. 
     As shown in  FIG. 4A , in a plane consisting of X-axis and Y-axis which are parallel to the boundary lines of the cells and which are orthogonal lines to each other, it is assumed that the length of the X-axis direction of each cell is a and the length of the Y-axis direction is b. The peak intensity of light in the irradiated surface with respect to the rotation angle of the light source image (the angle in the long axis direction with respect to the X-axis) θ will be shown in  FIG. 5 . It is assumed that a plurality of cells included in the microlens array is arranged in a lattice pattern. 
     As shown in  FIG. 5 , when the rotational angle θ of the light source image is 0 degrees, 90 degrees and tan −1 (b/a), light having local peaks in the intensity distributions is irradiated to the irradiated surface. The rotation angle θ of the light source image is 0 degrees and 90 degrees, when the direction of the long axis direction and the boundary lines of the cells of the light source image are parallel. The rotational angle θ in which the light source image is tan −1 (b/a) is a case when the long axis direction of the light source image and the direction of the diagonal lines of the cells are parallel. 
     Therefore, in order to make the intensity distribution of the light on the irradiated surface makes uniform, the rotational angle θ of the light source image is not set to 0 degrees, 90 degrees, tan −1 (b/a), and angles around them. 
     Specifically, it is desirable that the angle at which the long axis direction of the light source image for each LD and the direction of the boundary lines of the cells are intersected is 5 degrees or more. Similarly, it is desirable that the angle at which the long axis direction of the light source image for each LD and the direction of the diagonal lines of the cells are intersected is 5 degrees or more. 
     That is, the rotation angle θ of the long axis direction of the light source image with respect to the X-axis is desirable as follows: 
       5 degrees≤θ≤tan −1 ( b/a )−5 degrees, or
 
       tan −1 ( b/a )+5 degrees≤θθ85 degrees.   [Equation 1]
 
     For example, if each cell is square, the rotation angle θ in the long axis direction of the light source image with respect to the X-axis may be set in a range of 5 to 40 degrees or 50 to 85 degrees. When setting the rotation angle of the short axis direction of the light source image with respect to the X-axis, since the short axis direction of the light source image is a direction orthogonal to the long axis direction, it may be used an angle obtained by adding 90 degrees to the rotation angle θ of the long axis direction. 
     If the cell is sufficiently large with respect to the size of the light source image on the irradiated surface of the microlens array, the probability that the light source image is incident across a plurality of adjacent cells to the microlens array is reduced. In that case, the light flux of the light source image to be incident on the microlens array is difficult to be divided by a plurality of cells, even if the long axis direction of the light source image and the direction of the boundary lines or the direction of the diagonal lines of the cells are intersected, there is a possibility that the uniform light intensity distribution in the irradiated surface cannot be obtained. Therefore, the size of the cells of the microlens array, it is desirable that the light source image on the irradiated surface of the microlens array is sized so as to be incident across a plurality of cells. 
     For example, as shown in  FIG. 6A , consider an example in which it is assumed that the width of the short axis direction of the light source image incident on the microlens array is c, and in which, as shown in  FIG. 6B , the length of the cell parallel to the short axis direction of the light source image is L. 
     If L≤0.5c, since the cell with respect to the size of the light source image can be said to be sufficiently small, the direction of the boundary lines or the direction of the diagonal lines of the cells and the long axis direction of the light source image are not intersected, the intensity distribution of the light in the irradiated surface becomes relatively uniform. Therefore, in the case of L≤0.5c, it may not necessary that the direction of the boundary lines or the direction of the diagonal lines of the cells and the long axis direction of the light source image are intersected. Of course, even L≤0.5c, the direction of the boundary lines or the direction of the diagonal lines of the cells and the long axis direction of the light source image may be intersected. However, as described above, in the microlens array having small cells, since the edge sag easily occurs at the time of manufacturing, it is desirable that the length of L is 0.5c or more. 
     On the other hand, in the case of L≤3.0c, since the cell can be said to be sufficiently large with respect to the size of the light source image, even if the direction of the boundary lines or the direction of the diagonal lines of the cells and the long axis direction of the light source image are intersected, there is a possibility that the intensity distribution of light in the irradiated surface is not uniform. 
     Therefore, the optical system including the LD and the microlens array to which the first exemplary embodiment is applied may be designed such that L≤3.0c, and in particular, it is desirable to design such that 0.5c&lt;L≤3.0c. 
     In the above description, an example of a configuration in which a plurality of LDs is used as light sources has been described, but the number of LDs may be one. If a plurality of LDs is used as a light source, since the light source image is incident divided in various patterns for each cell of the microlens array, the effect of the present invention is more easily obtained. 
     According to the first exemplary embodiment, each LD and the microlens array is arranged so that the direction of the boundary lines or the direction of the diagonal lines of the cells and the long axis direction of the light source image are intersected. Thus, lights having different intensity distributions are emitted from each cell, and the lights are superimposed on the irradiated surface, so that the intensity distribution of the light on the irradiated surface becomes uniform. 
     Therefore, the non-uniformity of the light intensity distribution caused by the shape of the light source image in a particular irradiated surface can be improved. 
     Second Exemplary Embodiment 
       FIG. 7  is a schematic diagram showing another configuration example of a light source device included in a projector,  FIG. 8  is a schematic diagram showing an arrangement example of the light source image obtained by the light source device shown in  FIG. 7 .  FIG. 7  shows only a simplified main configuration of the light source device of the second exemplary embodiment, it may be provided an optical component such as a lens or a mirror if necessary. 
     The light source device of the second exemplary embodiment is a configuration example in which laser lights emitted from two synthetic light source units are synthesized to obtain brighter projection light, and the synthesized light is used as excitation light for irradiating the phosphor with the synthesized light.  FIG. 7  shows an example in which light emitted by two synthetic light source units is synthesized, but light emitted by three or more synthetic light source units may be synthesized. 
     The light source device of the second exemplary embodiment shown in  FIG. 7  includes two synthetic light source units  21  and  22 , synthetic mirror  23 , microlens arrays  24  and  25 , dichroic mirror  26 , phosphor  27  and color synthesis system  28 . 
     Synthetic light source units  21  and  22  are configured to each comprise a plurality of light sources, for example, a plurality of LDs is arranged in a lattice pattern. 
     Synthetic mirror  23  has a property of passing through light incident on one surface and of reflecting light incident on the other surface. Lights emitted from synthetic light source units  21  and  22  are respectively incident on synthetic mirror  23 , and is synthesized by synthetic mirror  23 , the synthesized light is incident on microlens arrays  24  and  25 . 
     As described above, microlens arrays  24  and  25  convert the light incident into a uniform light intensity distribution to incident on dichroic mirror  26 . 
     Dichroic mirror  26  has a characteristic of reflecting the light emitted from synthetic light source units  21  and  22  (excitation light) and of passing through light emitted by phosphor  27 . Light incident on dichroic mirror  26  is reflected and is irradiated onto phosphor  27 . 
     Phosphor  27  is configured to be fixed to a predetermined portion having no rotation mechanism or movement mechanism, and emits light (e.g., yellow light) having a wavelength different from that of the excitation light from the excitation light (e.g., blue light) emitted from synthetic light source units  21  and  22 . The light emitted by phosphor  27  is incident on dichroic mirror  26  and passes through dichroic mirror  26 . 
     In the second exemplary embodiment, since white light is emitted from the light source device similarly to the first exemplary embodiment, color light different from the color light emitted by phosphor  27 , which is insufficient for the synthesis of white light, is generated by color synthesis system  28 . For example, when yellow light is emitted by phosphor  27 , color synthesis system  28  may emit blue light. Color synthesis system  28  may have the same configuration as that of the first exemplary embodiment. 
     The output light of color synthetic system  28  is reflected by dichroic mirror  26 , is incident on illumination projection optical system  29  to synthesize with the light, which is passed through dichroic mirror  26 , emitted by phosphor  27 . 
     In such a configuration, in the second exemplary embodiment, as described above, the laser light s emitted from two synthetic light source units  21  and  22  are synthesized by synthesizing mirror  23 . At this time, the respective light source images after synthesis formed by a plurality of laser lights can also be arranged in a lattice pattern as shown in  FIG. 3A , but is arranged in a staggered manner as shown in  FIG. 8 . 
     When a plurality of light source images is arranged in a staggered manner, in addition to the short axis direction of each light source image shown by X and the long axis direction of each light source image shown by Y in  FIG. 8 , each light source image is also arranged periodically to the first and the second directions, which are different from the long axis direction and the short axis direction, in which a plurality of light source images shown by S 1  and S 2  are linearly arranged. 
     Therefore, when a plurality of light source images is arranged in a staggered manner, each LD and microrange array is arranged so that the direction of the boundary lines of the cells intersects with the short axis direction of each light source image, the long axis direction of each light source image, and the first and second directions, respectively. Also, each LD and microrange array are arranged so that the direction of the diagonal lines of the cells intersects with the short axis direction of each light source image, the long axis direction of each light source image, and the first and second directions, respectively. 
     At this time, it is desirable that the angle at which the direction of the boundary lines of the cells intersects with the short axis direction of each light source image, the long axis direction of each light source image, and the first and second directions is 5 degrees or more, similarly to the first exemplary embodiment. Also, it is desirable that the angle at which the direction of the diagonal lines of the cells intersects with the short axis direction of each light source image, the long axis direction of each light source image, and the first and second directions is 5 degrees or more, similarly to the first exemplary embodiment. 
     When the light emitted by the three or more synthetic light source units are synthesized, each LD and microrange array is arranged so that the direction of the boundary lines or the direction of the diagonal lines of the cells intersects with the short axis direction of each light source image, the long axis direction of each light source image, as well as the directions in which a plurality of light source images of the others are linearly arranged. 
     According to the second exemplary embodiment, when the light source images are arranged in a staggered manner on the irradiated surface of the microlens array, each LD and microrange array are arranged so that the direction of the boundary lines or the direction of the diagonal lines of the cells intersects with the short axis direction of each light source image, the long axis direction of each light source image, as well as the directions in which a plurality of light source images of others are linearly arranged. In this case, similarly to the first exemplary embodiment, light having a uniform intensity distribution is irradiated onto a predetermined irradiated surface. Therefore, the non-uniformity of the light intensity distribution caused by the shape of the light source image in a particular irradiated surface can be improved. 
     Third Exemplary Embodiment 
       FIG. 9A  is a schematic diagram showing an example of a relationship between the light source image and the microlens array of the third exemplary embodiment,  FIG. 9B  is a schematic diagram showing an example of light intensity distribution of the irradiated surface in a relationship example between the light source image and the microlens array shown in  FIG. 9A . 
     As mentioned above, the first and second exemplary embodiments shown the examples in which the microlens array are arranged so that two directions of the cells which are aligned are parallel to the direction of the second axis and the direction of the third axis, and in which each LD is arranged so that the direction of the boundary lines and the diagonal lines of the cells and the long axis direction of the light source image are intersected. 
     The third exemplary embodiment, for example, is an example in which a light source is arranged so that the long axis direction of the light source image is along the X-axis, and in which the microlens array is arranged so that the direction of the boundary lines and diagonal lines of the cells and the long axis direction of the light source image are intersected. 
     In the third exemplary embodiment, similarly to the first exemplary embodiment, a coordinate system is set which includes X-axis (first axis) and Y-axis (second axis) orthogonal to each other, and Z-axis (third axis) orthogonal to the X-axis and the Y-axis, respectively (see  FIG. 9A ). Then, in the third exemplary embodiment, the microlens array is arranged so that the two directions in which the cells are aligned and the directions of the second axis and the third axis are intersected. 
     For example, as shown in  FIG. 1 , when the intensity distribution of the excitation light irradiated to the phosphor is uniform, each LD  11  is arranged so that the long axis direction of the light source image on the irradiated surface of the microlens array is along the X-axis shown in  FIG. 9A . Then, the microlens arrays  12  and  13  are arranged so that the long axis direction of the light source image of each LD  11  and the direction of the boundary lines of the cells are intersected. Also, the microlens arrays  12  and  13  are arranged so that the long axis direction of the light source image of each LD  11  and the direction of the diagonal lines of the cells are intersected. 
     As shown in  FIG. 2 , when the intensity distribution of the illumination light irradiated on liquid crystal panel  3   a  (image forming device) is uniform, a plurality of LDs included in color synthesis system  16  is arranged so that the long axis direction of the light source image on the irradiated surface of the microlens array is along the X-axis shown in  FIG. 9A . Then, the microlens array is arranged so that the long axis direction of the light source images of the plurality of LDs included in color synthesis system  16  intersects with the direction of the boundary lines of the cells of the microlens array used as the integrator  2   a.  Also, the microlens array is arranged so that the long axis direction of the light source images of the plurality of LDs included in color synthesis system  16  intersects with the diagonal direction of the cells of the microlens array used as the integrator  2   a.    
     At this time, in order to make uniform the intensity distribution of light in the irradiated surface, similarly to the first exemplary embodiment, it is desirable that the angle at which the direction of the long axis of the light source image and the direction of boundary lines of the cells are intersected is 5 degrees or more. Also, it is desirable that the angle at which the direction of the long axis of the light source image and the direction of diagonal lines of the cells are intersected is 5 degrees or more. 
     Furthermore, when a plurality of light source images is arranged in a staggered manner, similarly to the second exemplary embodiment, each LD and the micro-range array are arranged so that the direction of the boundary lines of the cells intersects with the short axis direction of each light source image, the long axis direction of each light source image, as well as a direction in which a plurality of light source images of others are linearly arranged, respectively. Also, each LD and the micro-range array are arranged so that the direction of the diagonal lines of the cells intersects with the short axis direction of each light source image, the long axis direction of each light source image, as well as the directions in which a plurality of light source images of others are linearly arranged, respectively. 
     At this time, it is desirable that the angle at which the direction of the boundary lines of the cells intersects with the short axis direction of each light source image, the long axis direction of each light source image, as well as a direction in which a plurality of light source images of others is linearly arranged, as in the first exemplary embodiment, is 5 degrees or more. Also, it is desirable that the angle at which the direction of the diagonal lines of the cells intersects with the short axis direction of each light source image, the long axis direction of each light source image, as well as the directions in which a plurality of light source images of others is linearly arranged is 5 degrees or more. 
     Thus, even if the microlens array is arranged so that the direction of the boundary lines or the direction of the diagonal lines of the cells intersects with the long axis direction of each light source image, the short axis direction of each light source image, as well as a direction in which a plurality of light source images of others is linearly arranged, similarly to the first and second exemplary embodiments, light having a uniform intensity distribution is irradiated onto a predetermined irradiated surface (see  FIG. 9B ). The configuration of the other light source devices and the relationship between the microlens array and the LD are the same as those in the first and second exemplary embodiments, and therefore, the description thereof is omitted. 
     According to the third exemplary embodiment, similarly to the first and second exemplary embodiments, the non-uniformity of the light intensity distribution caused by the shape of the light source image in a particular irradiated surface can be improved. 
     Although the present invention has been described above with reference to the exemplary embodiments, the present invention is not limited to the above-described exemplary embodiments. Various modifications that can be understood by those skilled in the art within the scope of the present invention are possible in the configuration and details of the present invention.