JP2008186022A - Illumination optics - Google Patents

Abstract

To improve the light transfer efficiency of an illumination optical system having an optical integrator and a polarization conversion element.
An illumination optical system 1 has an optical integrator that divides an illumination light beam from a light source 200 using lens arrays 206 and 207 including a plurality of lenses, and a multistage configuration corresponding to the plurality of lenses of the lens array. A polarization beam splitter array having a plurality of polarization beam splitters, and a plurality of first and second polarization lights separated by each polarization beam splitter and whose polarization directions are orthogonal to each other, that rotate the polarization direction of the first polarization light. And a polarization conversion element 208 having a half-wave plate.
[Selection] Figure 3

Description

  The present invention relates to an illumination optical system and a projection display optical system used in a projection type image display apparatus.

  Conventionally, a projector-type display (projection-type image display device) is generally selected by using a liquid crystal display panel or a micromirror array device panel as a light modulation element for switching, and controlling transmission and blocking or deflection of light. By projecting a light pattern onto the screen, an image is displayed on the screen.

  In a projector using a liquid crystal display panel or a micromirror array device panel as a light modulation element, it is important to use light from a light source with high efficiency and to reduce illuminance unevenness on a screen.

  As an improvement means, an optical integrator composed of two two-dimensionally arranged lens arrays is known. The optical integrator divides a light beam from a light source into a plurality of light beams by a first lens array, and superimposes these light beams on a display area of a light modulation element while enlarging these light beams by a second lens array (Patent Literature). 1).

  According to this method, a light beam with small illuminance unevenness after division is superimposed, so that highly uniform irradiation light can be obtained, and the illuminance unevenness on the screen is greatly improved. Further, if each aperture of the first lens array is a rectangle similar to the display area of the light modulation element, the divided luminous flux is emitted to the display area without any problem, so that the efficiency of the irradiation light is improved and the light from the light source is improved. Improve usage efficiency.

  As another improvement means, light from the light source is guided to the kaleidoscope, and the light vector is mixed to make the light intensity distribution uniform at the light emitting end face of the kaleidoscope. Is imaged in a conjugate manner on a micromirror array device using an image forming lens as a light modulation element.

  In the case of using a kaleidoscope, the use of means for converting light from a naturally radiating light source into a linearly polarized state makes the optical system complicated, and thus is not generally implemented.

  Also in this method, highly uniform irradiation light can be obtained, and illuminance unevenness on the screen can be greatly improved.

  However, when a method for equalizing the light intensity distribution using an optical integrator or a kaleidoscope composed of two lens arrays is used, the light beam that illuminates the light modulation element has a large convergence angle. For this reason, when the light modulation panel is a reflective liquid crystal display panel or a micromirror array device, there is a spatial limitation for forming an optical path for guiding illumination light. When the light modulation panel is guided by a TIR (total reflection tilt) prism, There is a limit on the minimum reflection angle. In addition, when the light beam is guided by a polarizing beam splitter, the S-wave reflectivity is limited by the incident angle dependency, and therefore, it is desirable that the illumination light beam to the light modulation element is close to a parallel light beam.

  Further, when the light modulation element is a transmissive liquid crystal display panel and the transmissive liquid crystal display panel modulates light of the three primary colors red, green, and blue, the modulation is performed when the modulated light is synthesized by a dichroic mirror or a dichroic prism. As the light deviates from the parallel light flux, the cut wavelength in the reflection / transmission wavelength region of the dichroic film changes, resulting in color blur and deviation in color reproducibility depending on the position of the projected image.

  Further, when the light modulation element is not limited to a transmission type or a reflection type, but is a twisted nematic liquid crystal (TNLC), the more the incident angle of the illumination light beam to the liquid crystal display panel is inclined from the normal direction of the panel, the more general In the liquid crystal display panel surface, as it is tilted from each side direction, a deviation from 0 or π, which is an ideal optical wavelength phase difference caused by passing through the liquid crystal display panel, is generated. Therefore, the contrast of light modulation is reduced.

  Accordingly, the applicant of the present invention is an illumination optical system that illuminates the illuminated surface with a telecentric illumination light beam (including a slight divergence and convergence component), and is based on the deviation angle of the incident light beam with respect to the normal direction of the illuminated surface. The ratio of the angular width at which the intensity distribution of the changing illumination light on the surface to be illuminated becomes a half value of the peak value in each of the biaxial directions orthogonal to each other on the surface to be illuminated has an aspect ratio of 2: 1 or more. An optical integrator that performs splitting and recombination of the light beam in a first axial direction on a cross section that is substantially orthogonal to the traveling direction of the light beam, and a second that is orthogonal to the first axial direction on the cross section. Proposed is an illumination optical system provided with light intensity conversion means for performing a light intensity distribution conversion operation in the axial direction.

Accordingly, it is possible to realize an illumination optical system that uses light from the light source with high efficiency and obtains an illumination light beam with high illuminance uniformity, and this illumination optical system is used as an illumination unit of the projection display optical system. As a result, a projected image with high contrast can be obtained.
Japanese Patent Laid-Open No. 11-64848

  However, in the illumination optical system, when the divergence of the input light beam from the light source lamp is large, the utilization efficiency of the light from the light source may be reduced.

  Generally, full-color projection display devices that are currently commercialized have the color separation direction of the color separation / resynthesis optical system set in the horizontal direction of the projected image. This is because the horizontally long apparatus is easy to handle as a video-related device. Therefore, in the image content signal, the display image has an image display ratio of horizontal 4 vertical 3 of the NTSC system or an image ratio of horizontal 16 vertical 9 of the MUSE system, so that the long side direction of the light modulation panel is displayed in full color. The color separation and recombination direction necessarily coincides.

  That is, the light beam separation direction of the wavelength band separation film (dichroic mirror or the like) or the polarization beam splitter is the long side direction of the light modulation panel.

  Therefore, in order to prevent deterioration of the light separation accuracy due to the angle deviation of the light incident angle to the wavelength band separation film or the polarizing beam splitter, the light incident angle of the illumination light flux to the light modulation panel is the color separation recombination direction, that is, the light modulation panel. It is necessary to set a small value in the long side direction.

  Therefore, the optical integration direction in the illumination optical system according to the proposal of the applicant is the short side direction of the light modulation panel.

  Here, a disadvantageous problem arises in the light use efficiency from the light source lamp. In other words, since the optical integration direction is the short side direction of the light modulation panel, the multi-stage configuration direction of the polarization conversion element called a PS conversion element mainly composed of a multi-stage polarization beam splitter and a half-wave retardation plate is the light modulation element. Therefore, the arrangement of the light source arranged in the long side direction of the light modulation panel and the multi-stage slit mask arranged in the polarization conversion element is also usually the short side direction of the light modulation panel. Therefore, the amount of light from the light source having divergence blocked by the multi-stage slit mask increases, and the light transfer efficiency of the illumination optical system decreases.

  In order to solve the above problems, the illumination optical system of the present invention is compatible with an optical integrator that divides an illumination light beam from a light source using a lens array including a plurality of lenses, and a plurality of lenses of the lens array. A polarization beam splitter array having a plurality of polarization beam splitters in a multi-stage configuration, and a polarization direction of the first polarization light among the first and second polarization lights separated by each polarization beam splitter and orthogonal to each other. And a polarization conversion element having a plurality of half-wave plates to be rotated.

  As described above, according to the present invention, in the illumination optical system in which the incident angle on the surface to be illuminated in the split direction of the illumination light beam is reduced, by using a DC-driven discharge gas excitation arc tube as a light source, While maintaining the characteristics of the above-mentioned illumination optical system that the polarization separation (combination) characteristics such as the polarization separation (combination) element and spatial light modulation element on which the illumination light beam is incident are improved, the intensity distribution of the light beam toward the polarization conversion element is expanded. It is possible to suppress the amount of light shielded by the mask provided in the polarization conversion element (that is, a drop in the amount of light). Therefore, the light transfer efficiency of the present illumination optical system using the polarization conversion element can be improved.

  Then, by using such an illumination optical system for a projection display optical system or a projection type image display device, it is possible to improve the brightness of the projected image and increase the contrast without increasing the amount of light emitted from the light source. 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 a first embodiment of the present invention. In FIG. 1, reference numeral 200 denotes a DC-driven gas excitation lamp as a light source, and a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, or the like is used. A light source lamp (DC-driven discharge gas excitation arc tube) 200 is combined with a parabolic reflecting mirror 201 to generate a substantially parallel visible light beam.

  The light source lamp 200 is designed so that the discharge gap is as narrow as possible so as to limit the electron excitation region of the gas in order to make the obtained parallel beam as high quality collimated light beam as possible with as little divergence (divergence angle) as possible. Then, a direct current bias is applied between both electrodes, and a high-luminance point light source is generated on the cathode electrode side.

  Of the luminous flux radiated from the lamp unit composed of the light source lamp 200 and the parabolic reflection mirror 201, ultraviolet light outside visible light is cut by the ultraviolet cut filter 202.

  Ultraviolet rays can also excite and degrade optical glass and optical thin films that are used as lens materials in the long term. Especially when liquid crystal elements are used in light modulation panels, liquid crystal polymers and liquid crystals that are organic materials are used. The main purpose is to prevent the polymer liquid crystal alignment film for molecular alignment from being decomposed and altered by ultraviolet rays.

  The visible light beam that has passed through the ultraviolet cut filter 202 is incident on the first cylindrical lens array homogenizer 206. The first cylindrical lens array homogenizer 206 has a plurality of cylindrical lenses having refractive power only in the vertical direction in the figure, and divides the incident light flux into the number of the cylindrical lenses, and individually connects the focal lines. Thereafter, each split light beam is converted into a parallel light beam set to a predetermined width again by the cylindrical condenser lens 209.

  Here, the main plane interval between the first cylindrical lens array homogenizer 206 and the cylindrical condenser lens 209 is set to the sum of the focal length of the first cylindrical lens array homogenizer 206 and the focal length of the cylindrical condenser lens 209. Thereby, the light flux is reconverted into a parallel light flux as described above.

  Further, since the optical axis of the first cylindrical lens array homogenizer 206 is decentered with respect to the optical axis of each array, the cylindrical condenser lens 209 has a first cylindrical lens array homogenizer 206 at the position of the focal line of the cylindrical condenser lens 209. The light beams passed through each array are superimposed. Thereby, an optical integration operation is performed. The position of the focal line of the first cylindrical condenser lens 209 becomes the modulation surface of the light modulation panel 212.

  The light beam that has passed through the first cylindrical lens array homogenizer 206 passes through the second cylindrical lens array homogenizer 207. The position of the focal line of the second cylindrical lens array homogenizer 207 is set to the pupil position of each cylindrical lens of the first cylindrical lens array homogenizer 206. With the tandem lens configuration of the second cylindrical lens array homogenizer 207 and the cylindrical condenser lens 209, the pupil of each cylindrical lens of the first cylindrical lens array homogenizer 206 and the modulation surface of the light modulation panel 212 are optically conjugate. . Therefore, the pupils of the respective cylindrical lenses of the first cylindrical lens array homogenizer 206 are imaged on the modulation surface of the light modulation panel 212 in the vertical direction in the drawing.

  The light beam emitted from the lamp unit composed of the light source lamp 200 and the parabolic reflection mirror 201 is not completely parallel light but has divergence. Therefore, the second cylindrical lens array homogenizer 207 reliably modulates the light beams that have passed through the pupils of the respective cylindrical lenses of the first cylindrical lens array homogenizer 206 in order to correct the spread of the light flux for this divergence. Lead to the surface.

  The light beam that has passed through the second cylindrical lens array homogenizer 207 enters the polarization conversion element 208. The polarization conversion element 208 is similar to what is generally called a PS conversion element used in a liquid crystal projector, and is an array in which light emitted from a lamp unit is superimposed on a polarization beam splitter. It converts only to the polarization component parallel to the direction.

(About the polarization conversion element 208)
FIG. 2 schematically shows the polarization conversion element 208. The polarization conversion element 208 has multiple stages in the vertical direction so that a polarization beam splitter having a polarization separation film 208b inclined by 45 ° with respect to the incident optical axis corresponds to each cylindrical lens of the first and second cylindrical lens array homogenizers 206 and 207. (Multiple) arranged polarizing beam splitter array 208a and half-wave retardation plate (1/2 wavelength plate) provided on the exit surface of the polarizing beam splitter every other stage in the vertical direction among the plurality of polarizing beam splitters 208c and a multistage having a slit-like opening corresponding to the incident surface of the polarizing beam splitter not provided with the half-wave retardation plate 208c, covering the incident surface of the polarizing beam splitter provided with the half-wave retardation plate 208c. And a slit mask (hereinafter simply referred to as a mask) 208d.

  The P-polarized light component whose polarization direction is parallel to the paper surface of FIG. 2 is transmitted through the polarization separation film 208b, and the S-polarized light component whose polarization direction is perpendicular to the paper surface of FIG. 2 is reflected by the polarization separation film 208b. The light is reflected again by the polarization separation film 208b of the polarization beam splitter immediately below. As a result, the optical path of the S-polarized component is shifted downward by the pitch of the polarization beam splitter array 208a.

  The S-polarized component emitted from the polarization beam splitter is given a pi phase difference by the half-wave retardation plate 208c, so that the polarization direction is converted by 90 degrees and emitted from the polarization conversion element 208 as P-polarized light. Thus, all the light beams that have passed through the polarization conversion element 208 become P-polarized linearly polarized light with respect to the polarization beam splitter. That is, it is emitted as a polarized wave having an electromagnetic wave vibration vector parallel to the paper surface.

  Here, when the P-polarized light transmitted through the polarization separation film 208b is incident on the half-wave retardation plate 208c, the polarization direction is rotated by 90 °, and the S-polarized light is emitted from the polarization conversion element 208. For this reason, a mask 208d that blocks the incidence of the light beam is provided on the incident surface of the polarizing beam splitter that faces the half-wave retardation plate 208c, and the light beam is incident only from the slit formed between the masks 208d.

  In FIG. 1, the light beam that has passed through the polarization conversion element 208 is incident on the first cylindrical lens 205. The first cylindrical lens 205 has a refractive power only in the horizontal direction in the figure, and forms a beam compressor by pairing with the second cylindrical lens 210 arranged in the traveling direction of the light beam. . Therefore, the light beam incident on the first cylindrical lens 205 is compressed in the horizontal direction in the drawing and is basically guided to the light modulation panel 212 in an afocal state.

  However, in this embodiment, a predetermined amount of pupil distortion aberration is intentionally given to the beam compressor, and the light intensity distribution on the modulation surface of the light modulation panel 212 is controlled to be uniform or arbitrary distribution by this pupil distortion aberration. is doing. The action of pupil distortion aberration by this beam compressor will be described later with reference to FIG.

  The light beam that has passed through the first cylindrical lens 205 is incident on the cylindrical condenser lens 209, and as described above, the cylindrical condenser lens 209 causes the light beam to pass through the modulation surface of the light modulation panel 212 at the focal line position of the cylindrical condenser lens 209 in the drawing. Are superimposed and integrated in the vertical direction.

  The light beam that has passed through the cylindrical condenser lens 209 is incident on the second cylindrical lens 210. As described above, the second cylindrical lens 210 has a refractive power only in the horizontal direction in the figure, and forms a beam compressor paired with the first cylindrical lens 205. As a result, the light beam is compressed in the horizontal direction in the figure and guided to the light modulation panel 212 in an afocal state.

  Further, by the second cylindrical lens 210, the pupil of the first cylindrical lens 205 and the modulation surface of the light modulation panel 212 are substantially in an optical conjugate relationship (because the beam compressor intentionally has an aberration so that it is optical). The conjugate relationship is coarsely accurate). Therefore, the pupil of the first cylindrical lens 205 is imaged on the modulation surface of the light modulation panel 212 in the horizontal direction in the figure.

  Similar to the role of the second cylindrical lens array homogenizer 207, the second cylindrical lens 210 corrects the divergence of the light flux emitted from the lamp unit including the light source lamp 200 and the parabolic reflection mirror 201 by the divergence. It is arranged to reliably guide the light beam that has passed through the pupil of the cylindrical lens 205 to the modulation surface of the light modulation panel 212.

  The light beam that has passed through the cylindrical lens 210 enters the dummy polarizing beam splitter 211. This dummy may be a dichroic prism or a mirror. However, regardless of whether the dummy is a polarizing beam splitter or a dichroic prism, the deflection direction of the light beam is set in the horizontal direction in the figure.

  As described above, the light beam that has passed through the illumination optical system of this embodiment is guided to the light modulation panel 212. The illumination characteristics of this embodiment will be described later.

(About the light source lamp <DC-driven discharge gas excitation arc tube> 200)
Next, the state of the light beam emitted from the lamp unit and incident on the polarization conversion element 208 will be described with reference to FIG.

  FIG. 3A shows a lamp unit including the light source lamp 200 and the parabolic reflection mirror 201, and a mask 208d provided on the polarization conversion element 208, and a second unit disposed between the lamp unit and the mask 208d. A simplified cylindrical lens array homogenizer 206 is shown. The ultraviolet cut filter 202 and the second cylindrical lens array homogenizer are not shown.

  The light source lamp 200 is disposed such that the discharge end of the cathode electrode 200a is positioned at the focal point of the parabolic reflection mirror 201, and the discharge end of the anode electrode 200b is disposed forwardly from the discharge end of the cathode electrode 200a by a predetermined discharge gap. Has been.

  When a DC bias is applied to the light source lamp 200, the gas is excited by electron emission from the electrode 200a side, and a high-luminance light emitting region 200c is generated near the discharge end of the cathode electrode 200a. A low-luminance light emitting region 200d is formed between the electrodes 200a and 200b.

  Light emitted obliquely rearward from the light emitting region 200c is reflected by a portion of the parabolic reflection mirror 201 close to the light source lamp 200, and travels toward the first cylindrical lens array homogenizer 206 while spreading with a divergence angle θa2. The light beam emitted from the first cylindrical lens array homogenizer 206 enters the polarization conversion element 208 through the slit between the masks 208d while being converged.

  Further, light emitted obliquely forward from the light emitting region 200c is reflected by a portion of the parabolic reflection mirror 201 away from the light source lamp 200, and spreads with a divergence angle θa1, via the first cylindrical lens array homogenizer 206. It goes to the polarization conversion element 208.

  A slit opening between the mask 208d of the polarization conversion element 208 is disposed at a position of the focal length f from the first cylindrical lens array homogenizer 206.

  FIG. 4A shows a state of a light beam incident on the polarization conversion element 208 when an AC drive type light source lamp 250 is used in the illumination optical system shown in FIG.

  The light source lamp 250 is disposed so that the focal point of the parabolic reflection mirror 201 is positioned between the discharge end of the electrode 250a and the discharge end of the electrode 250b. When an AC bias is applied to the light source lamp 250, gas is excited between the electrodes 250a and 250b, and two high-luminance light emitting regions 250c1 and 250c2 are generated near the discharge end of the electrode 250a and near the discharge end of the electrode 250b. . A low-luminance light emitting region 250d is formed between the electrodes 250a and 250b.

  Light emitted obliquely backward from the two light emitting regions 250c1 and 250c2 is reflected by a portion of the parabolic reflection mirror 201 close to the light source lamp 250, and travels toward the first cylindrical lens array homogenizer 206 while spreading with a divergence angle θb2. The light beam emitted from the first cylindrical lens array homogenizer 206 enters the polarization conversion element 208 through the slit between the masks 208d while being converged.

  In FIG. 4A as well, a slit opening between the mask 208d of the polarization conversion element 208 is arranged at the position of the focal length f from the first cylindrical lens array homogenizer 206.

  In addition, the light emitted obliquely forward from the two light emitting regions 250c1 and 250c2 is reflected by a portion of the parabolic reflection mirror 201 away from the light source lamp 250, and spreads with a divergence angle θb1, while the first cylindrical lens array homogenizer. It goes to the polarization conversion element 208 via 206.

Here, in FIGS. 3A and 4A,
θa1 <θb1
θa2 <θb2
There is a relationship.

  FIG. 4B shows a light beam traveling toward the slit between the masks 208d when the light source lamp 250 which is an AC drive type gas excitation lamp is used. Since the light source lamp 250 forms two high-luminance light emitting portions, the intensity distribution of the luminous flux is the highest around the slit as shown in the figure. However, since the divergence angles θb1 and θb2 of the light flux are relatively large, the range of the light flux directed to the slit by the mask 208d is large. For this reason, the light amount drop due to the provision of the mask 208d becomes large.

  On the other hand, FIG. 3B shows a light beam traveling toward the slit between the masks 208d in the case of the present embodiment using the light source lamp 200 which is a direct current drive type discharge gas excitation arc tube. Since the light source lamp 200 forms one high-luminance light-emitting portion, the intensity distribution of the luminous flux is the highest at the approximate center of the slit and lower toward the periphery as shown in the figure. That is, the spread of the light intensity distribution of the luminous flux is suppressed as compared with FIG.

  Moreover, since the divergence angles θa1 and θa2 of the light beams are smaller than the divergence angles θb1 and θb2 in the case shown in FIG. 4A using the AC drive type light source lamp 250, the mask 208d out of the light beams toward the slit. The range given by is small.

  In other words, when the range of light flux produced by the mask 208d is small and the light intensity within that range is low, the drop in the amount of light due to the provision of the mask 208d is used when using an AC drive type discharge gas excitation arc tube. It can be suppressed to a very small amount compared to.

  In this way, by using a DC-driven discharge gas excitation arc tube as a light source, the light quantity drop at the point of incidence on the polarization conversion element 208 can be reduced compared to the case where an AC drive discharge gas excitation arc tube is used. In addition, the light transfer efficiency of the illumination optical system using the polarization conversion element 208 can be improved. That is, the light from the light source lamp 200 can be used with high efficiency.

(About optical integrator)
Next, an optical integrator used in the illumination optical system will be described with reference to FIG.

  In each of the optics arranged in FIG. 5, the first cylindrical lens array homogenizer 306 corresponds to the first cylindrical lens array homogenizer 206 in FIG. The second cylindrical lens array homogenizer 307 corresponds to the second cylindrical lens array homogenizer 207 in FIG.

  Furthermore, the cylindrical condenser lens 309 corresponds to the cylindrical condenser lens 209 of FIG.

  The first and second cylindrical lens array homogenizers 306 and 307 and the cylindrical condenser lens 309 constitute an optical integrator.

  The light modulation panel 312 in FIG. 5 corresponds to the light modulation panel 212 in FIG.

  The light beam indicated by the arrow in FIG. 5 guided to the first cylindrical lens array homogenizer 306 and substantially collimated in the optical integration direction is divided in the vertical direction in the figure by the pupil of each cylindrical lens, and is condensed on each focal line. To do. The position of the focal line of the first cylindrical lens array homogenizer 306 is near the pupil position of the second cylindrical lens array homogenizer 307, and the incident light beam indicated by the arrow is an ideal light beam that is completely collimated light. The luminous flux is arranged so that it hardly receives refractive power by the second cylindrical lens array homogenizer 307.

  Each light beam that has passed through the second cylindrical lens array homogenizer 307 is guided to a cylindrical condenser lens 309. Since the optical axis of each light beam is shifted from the optical axis of the cylindrical condenser lens 309, the optical axis of each light beam divided by the pupil of each cylindrical lens of the first cylindrical lens array homogenizer 306 is the focal line of the cylindrical condenser lens 309. It will gather at the position of.

  The main plane distance between the first cylindrical lens array homogenizer 306 and the cylindrical condenser lens 309 is set to the sum of the focal length of the first cylindrical lens array homogenizer 306 and the focal length of the cylindrical condenser lens 309. Each light beam divided by the pupil of each cylindrical lens of the one cylindrical lens array homogenizer 306 passes through the cylindrical condenser lens 309, and becomes parallel light with respect to the cross-sectional direction in the figure.

  The width of the parallel light is set so as to be enlarged by the ratio of the focal length of the cylindrical condenser lens 309 to the focal length of the first cylindrical lens array homogenizer 306.

  On the other hand, the light modulation surface of the light modulation panel 312 is disposed at the focal line position of the cylindrical condenser lens 309. As a result, an optical integration operation is performed on the modulation surface of the light modulation panel 312, and the light beam incident on the illumination optical system is converted into a substantially uniform light intensity distribution regardless of the light intensity distribution at the time of incidence. The modulation surface 312 is irradiated.

  Next, the function of the second cylindrical lens array homogenizer 307 will be described. The incident light beam indicated by the arrow in FIG. 5 is not completely collimated. In particular, in the present embodiment using the gas excitation light source lamp 200 instead of the laser, the excitation light emission region has a finite region of the order of 0.1 mm even if it is small. Therefore, a collimator lens or a parabolic reflection mirror is used. Even if is used, it is impossible to obtain a complete collimated beam, and the incident light beam always includes divergence (divergence angle).

  A second cylindrical lens array homogenizer 307 is provided in order to correct the outline blur of the illumination area of the light modulation panel 312 due to the divergence error.

  Referring to FIG. 5, since the light beam divided by the pupils of the respective cylindrical lenses of the first cylindrical lens array homogenizer 306 has a divergence component from the entire area of the pupils, the first cylindrical lens array homogenizer 306 has the divergence component. The pupil image of each cylindrical lens is projected and formed on the modulation surface of the light modulation panel 312 by the re-synthesis system of the second cylindrical lens array homogenizer 307 and the cylindrical condenser lens 309.

  The position of the focal line on the light incident side of each cylindrical lens of the second cylindrical lens array homogenizer 307 is set to the pupil position of each cylindrical lens of the first cylindrical lens array homogenizer 306. The divergence component of the light beam divided by the pupils of the respective cylindrical lenses of the first cylindrical lens array homogenizer 306 is indicated by fine dotted lines in FIG. The light flux that has passed through the second cylindrical lens array homogenizer 307 is converted into parallel light in the cross-sectional direction in the figure, and is further condensed by the cylindrical condenser lens 309 onto the focal plane of the cylindrical condenser lens 309.

  That is, the pupil image of each array of the first cylindrical lens array homogenizer 306 is superimposed on the modulation surface of the light modulation panel 312 in an optically integrated state to form an image. As a result, the modulation surface of the light modulation panel 312 is illuminated with a light intensity distribution with sharp edges in the cross-sectional direction of FIG.

(Optics for light intensity distribution conversion)
Next, optics for converting a light intensity distribution incorporated in the illumination optical system of the above embodiment will be described with reference to FIG.

  In each optics in FIG. 6, the first cylindrical lens 405 corresponds to the first cylindrical lens 205 in FIG. 1, and the second cylindrical lens 410 corresponds to the second cylindrical lens 210 in FIG. The light modulation panel 412 corresponds to the light modulation panel 212 of FIG.

  The substantially collimated light beam indicated by the arrow in FIG. 6 is incident on the first cylindrical lens 405. The first cylindrical lens 405 and the second cylindrical lens 410 disposed next form an afocal convex-convex pair of beam compressors, and the beam compression magnification is such that the width of the incident light beam is the light modulation panel 412. It is set to almost match the effective width of.

  The main plane distance between the first cylindrical lens 405 and the second cylindrical lens 410 is set to the sum of the focal length of the first cylindrical lens 405 and the focal length of the second cylindrical lens 405. For this reason, in the cross section of FIG. 6, a light beam incident as substantially parallel light is emitted as substantially parallel light having an angular magnification corresponding to the reciprocal of the compression magnification, and is applied to the light modulation panel 412.

  On the other hand, the second cylindrical lens 410 also has another function. The incident light beam indicated by the arrow in FIG. 6 is not completely collimated. In particular, in this embodiment using a gas excitation light source lamp 200 instead of a laser, the excitation light emission region has a finite region of the order of 0.1 mm even if it is small. Therefore, a collimating lens or a parabolic reflection mirror is used. Even if it is used, it is impossible to obtain a complete collimated beam, and the incident light beam always includes divergence (divergence angle).

  The second cylindrical lens 410 has a function of correcting the outline blur of the illumination area of the light modulation panel 412 due to the divergence error.

  The first cylindrical lens 405 allows the light beam having the divergence component to pass through from the entire area of the pupil, so that the pupil image of the first cylindrical lens 405 is applied to the modulation surface of the light modulation panel 412 by the second cylindrical lens 410. Projection is formed.

  The position of the imaging conjugate line on the light incident side of the second cylindrical lens 410 is the pupil position of the first cylindrical lens 405, and the position of the imaging conjugate line on the light exit side of the second cylindrical lens 410 is the modulation of the light modulation panel 412. Is set on the surface. The divergence component of the pupil light beam of the first cylindrical lens 405 is indicated by a fine dotted line in FIG. 6, and each light beam divided by the pupil of the first cylindrical lens 405 passes through the second cylindrical lens 410 so that a cross section in the figure. The light is condensed on the modulation surface of the light modulation panel 412 in the direction. That is, the pupil image of the second cylindrical lens 410 is transferred and formed on the modulation surface of the light modulation panel 412.

  Further, the beam compressor composed of the first cylindrical lens 405 and the second cylindrical lens 410 is an afocal optical system, and the pupil transfer aberration by the beam compressor is also referred to as spherical aberration at afocal. Distortion aberration is intentionally added. The curvatures of the cylindrical surfaces of the first cylindrical lens 405 and the second cylindrical lens 410 are small, and are designed so that aberrations are given as they deviate from the optical axis. As shown by a rough dotted line in FIG. 6, the light beam in the vicinity of the optical axis passes through the second cylindrical lens 410 and is then converted into a slightly divergent light beam in the cross section of FIG.

  On the other hand, the light beam outside the pupil away from the optical axis passes through the second cylindrical lens 410 and is converted into a slightly convergent light beam in the cross section of FIG. In this way, since the change in divergence and convergence is applied smoothly and continuously, the light density at the center portion becomes light and the light density at the end portion becomes high on the modulation surface of the light modulation panel 412 in the cross section of FIG. Thus, the light intensity distribution for illuminating the modulation surface of the light modulation panel 412 is obtained by multiplying the light intensity distribution of the incident light beam indicated by the arrow from the lamp unit composed of the gas excitation light source and the parabolic reflection mirror by the light density distribution described above. Distribution.

  Here, it will be described with reference to FIGS. 7 and 8 what light intensity distribution the light modulation panel is illuminated by the combination of the light intensity conversion optics and the optical integrator described with reference to FIG.

  7 and 8 show a process for forming a light intensity distribution on the light modulation panel by the illumination optical system of this embodiment. FIGS. 7A and 8A show cross-sectional profiles of light beams emitted from the lamp unit including the light source lamp 200 and the parabolic reflection mirror 201. In FIG. Is high. Further, in FIG. 8A, a solid line graph indicates light in a cross section in the horizontal (X) direction at the center (0 mm) in the vertical (Y) direction (the short side direction of the rectangular light modulation panel) in FIG. The intensity distribution and the dotted line graph respectively show the light intensity distribution in the cross section in the longitudinal (Y) direction at the center (0 mm) in the horizontal (X) direction (long side direction of the light modulation panel) in FIG. .

  The light intensity distribution of the light beam shown in FIGS. 7A and 8A is divided and integrated by an optical integrator for each region divided by a horizontal line in FIG. 7A, and is shown in FIG. The light density distribution on the modulation surface of the light modulation panel due to the pupil distortion aberration of the beam compressor described above is multiplied in the direction of the light intensity conversion optics to modulate the light modulation panel shown in FIGS. 7 (c) and 8 (c). A light intensity distribution on the surface can be obtained.

  As can be seen from FIGS. 7C and 8C, the light intensity distribution of the illumination light beam incident on the modulation surface of the light modulation panel has a high intensity and a substantially flat (uniform) distribution.

  However, as a matter of course, the light beam density distribution on the modulation surface of the light modulation panel can be changed according to the purpose by designing the pupil distortion aberration of the beam compressor to a predetermined value. Therefore, the light intensity distribution of the illumination light beam incident on the modulation surface of the light modulation panel can intentionally have a predetermined distribution in the direction in which the light intensity conversion optics acts.

  Next, characteristics obtained by the illumination optical system described above will be described with reference to FIGS.

  FIG. 10 shows a light beam incident angle distribution on an illuminated surface such as a modulation surface of a light modulation panel of an illumination light beam optically integrated by a pair of conventional two-dimensional fly-eye lens arrays. In FIG. 10A, the outer periphery is in the direction of the azimuth angle of 360 degrees, and the radiation axis indicates the elevation angle with respect to the normal line (vertical incident axis) of the illuminated surface. In this figure, the outer periphery is shown with an elevation angle of 20 degrees. FIGS. 10B and 10C show the light intensity distributions at the BB and CC sections in FIG. 10A, respectively.

  On the other hand, FIG. 9 shows a light incident angle distribution of an illumination light beam obtained by the illumination optical system of the present embodiment on a surface to be illuminated such as a modulation surface of a light modulation panel. In FIG. 9A, the outer periphery is the azimuth angle of 360 degrees, and the radiation axis indicates the light beam incident angle distribution on the illuminated surface. In this figure, the outer periphery is shown with an elevation angle of 20 degrees. FIGS. 9B and 9C show the light intensity distributions along the BB and CC sections in FIG. 9A, respectively.

  As can be seen from a comparison between FIG. 9A and FIG. 10A, the light beam applied to the illuminated surface has a substantially uniform light intensity distribution on the illuminated surface. There is a big difference in incident angle characteristics.

  That is, as shown in FIG. 10A, an illumination light beam that has been optically integrated by a pair of two-dimensional fly-eye lens arrays has a light beam distribution that is biaxially symmetric with respect to the surface to be illuminated.

  On the other hand, in the case of the present embodiment, as shown in FIG. 9A, the vertical elevation of the optical integration direction (BB direction) in the figure has the same elevation angle, but the action of the light intensity conversion optics. In the direction (C-C direction), since there is no superimposing operation of the light beam by the optical integration, the divergence angle of the light beam emitted from the lamp unit depends on the angular magnification by the compression magnification of the beam compressor. It will have an elevation angle. Therefore, the light incident angle on the surface to be illuminated can be kept very small in the direction in which the light intensity conversion optics acts.

  Specifically, with respect to the intensity distribution on the illuminated surface of the illumination light that changes depending on the deviation angle of the incident light with respect to the normal direction of the illuminated surface, two axes (BB axis and C−) that are orthogonal to each other on the illuminated surface. The ratio α: β of the angular width that is a half value (1 / 2P) of the peak value P in each of the (C axis) directions has an aspect ratio of 2: 1 or more.

  More specifically, the angle width that is the half value of the peak value on the BB axis is twice or more the angle width that is the half value of the peak value on the CC axis. Further, the maximum value of the angular width that is a half value of the peak value in the BB axis direction may be twice or more the maximum value of the angular width that is the half value of the peak value in the CC axis direction.

  Hereinafter, the influence (advantage) of the performance of the projection type image display apparatus using the illumination optical system due to such characteristics will be described.

  FIG. 11 shows the entire optical system of the projection type image display apparatus according to the second embodiment of the present invention.

  In this figure, 1 schematically shows the illumination optical system described in the first embodiment. In addition, the figure on the left side in the illumination optical system 1 is the figure which looked at the illumination optical system 1 shown on the right side from the arrow D direction.

  2R, 2G, and 2B are red, green, and blue reflective liquid crystal modulation panels (hereinafter referred to as liquid crystal modulation panels), respectively. An optical modulation panel driver 3 converts an external video input signal from an image information supply device such as a personal computer, a television, a video, a DVD player (not shown) into a drive signal for driving the liquid crystal modulation panels 2R, 2G, and 2B. Convert. The liquid crystal modulation panels 2R, 2G, and 2B form an original image corresponding to the input drive signal with liquid crystals, and reflect and modulate the illumination light beam incident on the liquid crystal modulation panels 2R, 2G, and 2B.

  Illumination light as linearly polarized light polarized in the direction perpendicular to the paper surface of the drawing from the illumination optical system 1 reflects the magenta color light component, and the magenta color light component is first reflected by the magenta separation dichroic mirror 30 that transmits the green color light component. The

  The reflected magenta color light component is incident on a blue cross color polarizer 34 that gives a phase difference of π to the polarization of blue light. As a result, a blue light component that is linearly polarized light polarized in a direction parallel to the paper surface of the figure and a red light component that is linearly polarized light polarized in a direction perpendicular to the paper surface are generated.

  The blue light component and the red light component are incident on the polarization beam splitter 33, and the blue light component which is P-polarized light is transmitted through the polarization separation film and guided to the blue liquid crystal modulation panel 2B. Further, the red light component which is S-polarized light is reflected by the polarization separation film and guided to the red liquid crystal modulation panel 2R.

  On the other hand, the green light component transmitted through the magenta separation dichroic mirror 30 passes through the dummy glass 36 for correcting the optical path length and enters the polarization beam splitter 31.

  The green light component that is S-polarized light incident on the polarization beam splitter 31 is reflected by the polarization separation film of the polarization beam splitter 31 and guided to the green liquid crystal modulation panel 2G.

  Thus, the liquid crystal modulation panels 2R, 2G, 2B are illuminated with the corresponding color light components.

  Each color illumination light incident on each liquid crystal modulation panel 2R, 2G, 2B (linearly polarized light polarized in a direction perpendicular to the paper surface of the figure) depends on the modulation state of the pixels arranged on each liquid crystal modulation panel 2R, 2G, 2B. Thus, a phase difference of polarization is given.

  Of the modulated light emitted from each of the liquid crystal modulation panels 2R, 2G, and 2B, the polarization component in the same direction as the illumination light follows the optical path in the reverse order to the illumination optical path and returns to the lamp unit side in the polarization direction of the illumination light. On the other hand, the component having the orthogonal polarization direction reaches the projection lens 4 as follows.

  That is, the modulated light from the red liquid crystal modulation panel 2R becomes P-polarized light whose polarization direction is parallel to the drawing sheet, and passes through the polarization separation film of the polarization beam splitter 33. Next, the light passes through a red cross color polarizer 35 that gives a phase difference of π to red polarized light, and is converted into a red light component as linearly polarized light that is polarized in a direction perpendicular to the drawing sheet.

  The red light component that has become S-polarized light enters the polarization beam splitter 32, is reflected by the polarization separation film, and travels toward the projection lens 4.

  Further, the modulated light by the blue liquid crystal modulation panel 2B becomes S-polarized light whose polarization direction is perpendicular to the paper surface of the drawing, and is reflected by the polarization separation film of the polarization beam splitter 33, and the red cross color polarizer 35 is converted into this polarizer 35. The light is transmitted without being affected by the light beam and enters the polarization beam splitter 32.

  The blue light component that is S-polarized light is reflected by the polarization separation film of the polarization beam splitter 32 and travels toward the projection lens 4.

  Further, the modulated light from the green liquid crystal modulation panel 2G becomes P-polarized light whose polarization direction is parallel to the paper surface of the drawing, passes through the polarization separation film of the polarization beam splitter 31, and passes through the dummy glass 37 for correcting the optical path length. The light passes through and enters the polarization beam splitter 32. The green light component that is P-polarized light passes through the polarization separation film of the polarization beam splitter 32 and travels toward the projection lens 4.

  The liquid crystal modulation panels 2R, 2G, and 2B are adjusted or mechanically or electrically compensated so that predetermined pixels of each panel overlap on the light diffusion screen 5 with relatively high accuracy.

  Each color light component synthesized by the polarization beam splitter 32 is captured by the entrance pupil of the projection lens 4. The modulation surface of each liquid crystal modulation panel 2G and the diffusion surface of the light diffusion screen 5 are optically conjugate with each other by the projection lens 4. For this reason, the respective color light components synthesized by the polarization beam splitter 32 are transferred to the light diffusion screen 5, whereby an image corresponding to the video signal is projected and displayed on the light diffusion screen 5.

  Here, when the dichroic film of the dichroic mirror 30 used in the optical path for illuminating the liquid crystal modulation panels 2R, 2G, and 2B increases in deviation from 45 degrees with respect to the dichroic film of the incident angle of the light beam. The separation wavelength shifts to the short wavelength side at the obtuse angle side and to the long wavelength side at the acute angle side.

  For this reason, when a conventional optical integrator based on a pair of two-dimensional fly-eye lens arrays is used in the illumination optical system, a light beam having an incident angle distribution as shown in FIG. 10A is incident on the dichroic film. However, as the angle shifts from 45 degrees with respect to the dichroic film, light beams having different wavelength bands are mixed.

  Here, if the lamp unit as the light source has a gentle radiant energy wavelength distribution characteristic such as black body radiation, the angle incident on the dichroic film is symmetric with respect to 45 degrees, so the average cut The wavelength does not change. However, as in this embodiment, in the lamp unit of electron excitation radiation using gas excitation light emission, the radiant energy wavelength distribution has a wavelength spectrum distribution mainly composed of emission lines, so the average cut wavelength changes at the center of gravity. It will be. Therefore, the color separation by the dichroic film becomes inappropriate, and the color reproducibility of the projected image becomes unnatural.

  The polarization beam splitters 31, 32, and 33 used in the optical path for illuminating the liquid crystal modulation panels 2R, 2G, and 2B and the color synthesis optical path are general MacNeille polarization beam splitters and have a Brewster angle. As the deviation amount from 45 degrees with respect to the polarization separation surface of the light incident angle increases, the separation accuracy of S polarization and P polarization suddenly increases. to degrade.

  Actually, the separation accuracy between the S-polarized light and the P-polarized light can be maintained at about 50 to 1 because the deviation from 45 degrees is about ± 3 degrees. Therefore, when a conventional optical integrator using a pair of two-dimensional fly-eye lens arrays is used, a light beam having an incident angle distribution as shown in FIG. 10A is incident on the polarization beam splitters 31 and 32, and liquid crystal modulation is performed. Since the light is incident on the polarization beam splitters 31, 32, 33 after being subjected to reflection polarization modulation in the panels 2R, 2G, 2B, the amount of deviation from 45 degrees with respect to the polarization separation surface of the light incident angle is ± 3 degrees or more. In this case, the light beam is reflected at a certain ratio and transmitted at a certain ratio.

  Accordingly, the illumination light incident on each of the liquid crystal modulation panels 2R, 2G, and 2B made of a reflective liquid crystal display element has a polarization phase difference according to the modulation state of the pixels arranged on the liquid crystal modulation panels 2R, 2G, and 2B. Even if each liquid crystal modulation panel 2R, 2G, 2B modulates light that is given but does not change the phase difference in order to display black in each color, it is 45 with respect to the polarization separation surface of the polarization beam splitters 31-33. In a light beam tilted by 3 degrees or more from the angle, it is transmitted at a certain ratio of S-polarized light and reflected at a certain ratio of P-polarized light, and is transferred to the light diffusion screen 5 through the projection lens 4 so that black is gray. As a result, the illuminance contrast deteriorates.

  In addition, regarding the polarization modulation characteristics of the liquid crystal modulation panels 2R, 2G, and 2B, when twisted nematic liquid crystal is used as the liquid crystal modulation panel, the azimuth angle of the reflective liquid crystal modulation panel is incident from an angle of 45 degrees. Since the polarization phase difference modulation panels 2R, 2G, and 2B are fundamentally characterized by being unable to modulate with high accuracy, the conventional two-dimensional fly-eye lens that performs illumination from a substantially axially symmetric azimuth angle When an optical integrator using a pair of arrays is used, the polarization modulation of the liquid crystal becomes insufficient, and as in the case of the incident angle dependent characteristics of the polarizing beam splitters 31 to 33, black is displayed in gray and the illuminance contrast is deteriorated. To do.

  For these problems, the illumination optical system 1 described in the first embodiment can be used to obtain a light beam having an incident angle distribution as shown in FIG. In incidence, the deviation from 45 degrees with respect to the dichroic film at the angle of incidence of light falls within about ± 3 to 4 degrees, which occurs when a conventional optical integrator using a pair of two-dimensional fly-eye lens arrays is used. In the color separation by the dichroic film, inappropriate color synthesis is performed by changing the average cut wavelength at the center of gravity, and it is almost eliminated that the color reproducibility of the projected image becomes unnatural.

  In addition, when the light beam is incident on the polarization beam splitters 31 to 33, the deviation amount from 45 degrees with respect to the polarization separation surface of the light incident angle is within ± 3 to 4 degrees. The deterioration of the illuminance contrast due to the polarization wave separation error that does not depend on the modulation state of the pixels arranged in the liquid crystal modulation panel, which occurs when using the optical integrator of the pair, is almost eliminated.

  In addition, regarding the problem of polarization phase difference modulation that depends on the incident angle of the reflective liquid crystal modulation panel, the illumination light flux component from the azimuth angle at which the polarization modulation of the liquid crystal is insufficient is almost eliminated, so that the illuminance contrast deteriorates. Mostly eliminated.

  Further, in the projection type image display apparatus of the present embodiment, an advantage relating to the projection lens 4 also occurs. That is, FIG. 9A shows a direction in which the projection field angle of the projection lens 4 increases by setting the polarization separation direction in the long side direction of the liquid crystal modulation panel or setting the wavelength separation direction. Since it is possible to set a direction in which the illumination angle distribution in the lateral direction is narrow, the width of the light beam passing in the direction in which aperture erosion called vignetting of the projection lens 4 occurs is narrowed. In other words, it has the effect of reducing the flux fluctuation caused by the pupil aperture of the projection lens 4, prevents a decrease in the amount of light at the edge of the image area projected onto the light diffusion screen 5, and produces a projection image with a uniform light intensity distribution. Obtainable.

  In the second embodiment, the image display system is configured using a reflective screen. However, the screen may be a reflective type or a transmissive type. In particular, if a device having a predetermined diffusivity is used, it functions as a projection type image display device that directly recognizes an image by looking directly at the screen 5.

  The configuration of the projection display optical system described in the second embodiment is merely an example, and the illumination optical system of the present invention can be applied to projection display optical systems other than the second embodiment.

  Further, in each of the above embodiments, as an optical integrator, illumination is performed in the first axial direction (vertical direction) on a cross section substantially orthogonal to the traveling direction of the illumination light beam that is incident as a substantially parallel light beam from the light source using the lens array. Although the first cylindrical lens array homogenizer 206 and the second cylindrical lens array homogenizer 207 for splitting and recombining the light beams are used, a DC drive type discharge gas excitation arc tube (light source lamp) 200 is used as a light source. The present invention, as an optical integrator, divides the illumination light beam with respect to the first and second axial directions (vertical and horizontal directions) on the cross section substantially perpendicular to the traveling direction of the illumination light beam that is incident as a substantially parallel light beam from the light source, and Using a two-dimensional lens array for recombination and direct current drive as the light source In the configuration using a discharge gas excitation light-emitting tube (light source lamp) 200 can be applied.

  Furthermore, each Example described above is also an example when each invention shown below is implemented. The following inventions are also implemented by adding various changes and improvements to the above embodiments.

[Invention 1] a light source;
An optical integrator that divides and recombines the illumination light beam in a first axial direction in a two-dimensional cross section orthogonal to the traveling direction of the illumination light beam that is incident as a substantially parallel light beam from the light source using a lens array;
A polarizing beam splitter array having a plurality of polarizing beam splitters having a multi-stage configuration corresponding to a predetermined lens region of the lens array, and first and second polarized lights separated by the polarizing beam splitters and having mutually orthogonal polarization directions Among the plurality of half-wave plates that rotate the polarization direction of the first polarized light by approximately 90 °, and the polarized light that blocks the incidence of the second polarized light on the half-wave phase plates. A polarization conversion element having a mask covering a plurality of regions of the incident surface of the beam splitter array,
An illumination optical system characterized in that a direct current drive type discharge gas excitation light emitting tube is used as the light source.

  [Invention 2] The illumination optical system according to Invention 1, wherein the light beam passing through the opening of the mask has a higher intensity distribution at a substantially center in the opening than in the periphery.

[Invention 3] A substantially rectangular surface to be illuminated is illuminated,
The illumination optical system according to claim 1, wherein the first axial direction is a short side direction of the illuminated surface.

[Invention 4] The optical integrator,
The light intensity converting means for converting the light intensity distribution in a second axis direction orthogonal to the first axis direction on the cross section. The illumination optical system described.

[Invention 5] Illuminate the surface to be illuminated with a substantially telecentric illumination beam,
The angle at which the intensity distribution on the illuminated surface of the illumination light, which varies depending on the deviation angle of the incident light beam with respect to the normal direction of the illuminated surface, is a half value of the peak value in each of two mutually perpendicular directions on the illuminated surface The illumination optical system according to any one of inventions 1 to 4, wherein the width ratio has an aspect ratio of 2: 1 or more.

  Thereby, in addition to the effect of the invention 1, it is possible to realize an illumination optical system that uses light from the light source with high efficiency and obtains an illumination light beam with high uniformity of illuminance. By using this illumination optical system as a projection display optical system, a bright and high-contrast projection image can be obtained.

[Invention 6] The illumination optical system according to any one of Inventions 1 to 5,
A spatial light modulation element that modulates a light beam emitted from the illumination optical system by a two-dimensionally arranged pixel group;
A projection display optical system comprising: a projection lens that projects a light beam modulated by the spatial light modulation element onto a projection surface.

  [Invention 7] A projection-type image display device comprising the projection display optical system according to Invention 6.

  [Invention 8] The projection image display device according to Invention 7, and a screen that forms the projection surface, and a projected image by diffuse reflection light or diffuse transmission light having a predetermined directivity on the screen. An image display system characterized by causing the image to be observed.

1 is a schematic configuration diagram of an illumination optical system that is a first embodiment of the present invention. FIG. The schematic block diagram of the polarization conversion element contained in the said illumination optical system. Schematic which showed the mode of the light beam which goes to the polarization conversion element from the direct current drive type discharge gas excitation light emission tube of the said illumination optical system. Schematic which showed the mode of the light beam which goes to a polarization conversion element from an alternating current drive type discharge gas excitation light-emitting tube in an illumination optical system. Schematic explaining the function of the optical integrator incorporated in the said illumination optical system. Schematic explaining the function of the light intensity conversion optics incorporated in the said illumination optical system. The figure explaining the process which produces | generates substantially uniform light intensity distribution by the said illumination optical system. The figure explaining the process which produces | generates substantially uniform light intensity distribution by the said illumination optical system. The figure which shows light irradiation angle distribution to the light modulation panel by the said illumination optical system. The figure which shows the light irradiation angle distribution to the light modulation panel by the illumination optical system using the conventional two-dimensional optical integrator. Schematic which shows the structure of the projection type image display apparatus which is 2nd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Illumination optical system 2,2R, 2G, 2B Liquid crystal modulation panel 3 Light modulation panel driver 4 Projection lens 5 Light diffusion screen 30 Dichroic mirror 31-33 Polarization beam splitter 34 Blue cross color polarizer 35 Red cross color polarizer 36, 37 Dummy glass 200 Light source lamp (DC-driven discharge gas excitation arc tube)
201 Parabolic reflection mirror 202 UV cut filter 205, 305, 405 First cylindrical lens 206, 306 First cylindrical lens array homogenizer 207, 307 Second cylindrical lens array homogenizer 208 Polarization conversion element 209, 309 Cylindrical condenser lens 210, 310, 410 Second cylindrical lens 212, 312, 412 Light modulation panel 250 Light source lamp (AC drive type discharge gas excitation arc tube)

Claims (1)

An optical integrator that divides an illumination light beam from a light source using a lens array including a plurality of lenses;
A polarizing beam splitter array having a plurality of polarizing beam splitters having a multi-stage configuration corresponding to the plurality of lenses of the lens array, and first and second polarized lights separated by the polarizing beam splitters and having mutually orthogonal polarization directions A polarization conversion element having a plurality of half-wave plates for rotating the polarization direction of the first polarized light,
An illumination optical system comprising:

Images