JP2006337428A - Illuminating optical system, optical engine and projection image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology of improving efficiency in using light and reducing nonuniform illuminance of light, in an illuminating optical system for a projection type image display apparatus having a plurality of light sources. <P>SOLUTION: An illuminating optical system comprises: a plurality of rod lenses corresponding to a plurality of light sources; and a prism array by which light rays made incident on the plurality of rod lenses are aligned to one optical path and emitted. The prism array is integrally formed from: a first means for reflecting about a half of incident light or specific polarization component light and allowing the remaining or other specific polarization component light to pass through the first means; a second means for reflecting light passed through or reflected from the first means; and a prism material disposed in contact with both the first and second means. The transmitted light and reflected light by the first means and the reflected light by the second means are turned into composite light aligned to the one optical path. The composite light is emitted to an image display element from the one prism face of the prism array. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical system of a projection display apparatus, and more particularly to a technique for improving the brightness of an image using a plurality of light sources.

  An optical image formed by irradiating light from a light source onto a video display element (for example, a micromirror array in which micromirrors serving as pixels are arranged in a matrix) using a lens, a mirror, or the like, and modulating the video display element There is known a projection type image display apparatus that displays an image by enlarging and projecting. In such a video display device, in recent years, an illumination optical system including a plurality of light sources may be used to improve luminance. In the illumination optical system using the plurality of light sources, means for synthesizing light from the plurality of light sources is required. As this type of prior art, for example, there is one described in Japanese Patent Application Laid-Open No. 2004-133388 (Patent Document 1). In this publication, two light sources arranged orthogonally are used, the light flux from each light source is made uniform by a corresponding rod lens, and the two light sources are provided by a so-called half mirror having a reflecting surface. A technique for synthesizing light from is described.

JP 2004-133388 A

In the technique described in the above Japanese Patent Application Laid-Open No. 2004-133388, since a beam splitter is used, approximately half of the light emitted from each light source is directly irradiated onto the image display element, and the remaining half of the light is Reflected by the reflecting surface of the beam splitter and returned to the rod lens side, reflected by the mirror of the rod lens and directed again to the beam splitter. The remaining half of the light is repeatedly reflected and then emitted from the beam splitter and applied to the image display element. For this reason, the light utilization efficiency of the remaining half of the light tends to decrease due to light loss due to repeated reflection. Therefore, in the present technology, there is a possibility that sufficient brightness cannot be obtained while using two light sources.
An object of the present invention is to improve light utilization efficiency and obtain a predetermined high-intensity image in a projection-type image display device in view of the above-described state of the prior art.

In the present invention, as an illumination optical system of a projection display apparatus, basically, a plurality of rod lenses corresponding to each of a plurality of light sources, and light incident from each of the plurality of rod lenses are placed on one optical path. And a prism array that emits light in a uniform manner. The prism array reflects about half of light incident from each of the plurality of rod lenses or predetermined polarization component light, and transmits the remaining light or other predetermined polarization component light. The first means, the second means for reflecting the light transmitted through the first means or the light reflected by the first means, and the prism material in contact with both the first and second means are integrated. The transmitted light and the reflected light by the first means and the reflected light by the second means are combined light having a single optical path, and one of the prism arrays is formed. The light is emitted from the prism surface toward the image display element side. For example, a half mirror or a polarization beam splitter is used as the first means, and a total reflection mirror is used as the second means.
Specifically, the present invention is an illumination optical system, an optical engine, and a projection-type image display device that have the above basic requirements.

  The use efficiency of light can be improved under a configuration using a plurality of light sources, and it is possible to provide an illumination optical system, an optical engine, and a projection-type image display device with high luminance and little illuminance unevenness.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, components having a common function are denoted by the same reference numerals in the respective drawings.

1 to 3 are explanatory views of a first embodiment of the present invention. FIG. 1 is a configuration diagram of an illumination optical system for a projection-type image display device as a first embodiment of the present invention, and FIG. 2 is an explanatory diagram of an irradiation area on an image display element by the illumination optical system of FIG. 3 is a diagram showing an example of optical characteristics of the half mirror 5 in the illumination optical system of FIG.
In FIG. 1, the illumination optical system of the present embodiment includes two light sources 1A and 1B arranged so that their optical paths are orthogonal, reflectors 2A and 2B provided corresponding to the respective light sources, and light from each light source. Two rod lenses 3A and 3B for equalizing each other, and a prism array 4 in which the light beams emitted from the rod lenses 3A and 3B are combined light with the same optical path (hereinafter referred to as “synthesize”), and prisms And a condensing lens 7 for condensing the light synthesized by the array 4. The light emitted from the condenser lens 7 is separated (color separated) into red, green, and blue light by a color separation means (not shown), and then irradiated to a video display element 8 such as a micromirror array. The In FIG. 1, “A” in each symbol indicates an element on one light source 1A side, and “B” indicates an element on the other light source 1B side. The light sources 1A and 1B and the reflectors 2A and 2B constitute a light source unit.

  In this embodiment, elliptical reflectors are used as the reflector 2A and the reflector 2B, and the light sources 1A and 1B are arranged near the first focal points of the reflector 2A and the reflector 2B, respectively, and the rod lens 3A is arranged near the second focal points. The incident side end surface (hereinafter referred to as “incident surface”) S3Ai and the incident side end surface (hereinafter referred to as “incident surface”) S3Bi of the rod lens 3B are disposed. Thereby, the light emitted from each of the light sources 1A and 1B can be efficiently incident on the incident surface S3Ai of the rod lens 3A and the incident surface S3Bi of the rod lens 3B. A parabolic reflector is used for the reflector 2A and the reflector 2B, and light is condensed on the respective incident surfaces of the rod lens 3A and the rod lens 3B by a spherical or aspherical condensing lens (not shown). Also good.

  The rod lenses 3A and 3B include those made of a rod-like transparent glass material, and those in which four surfaces are surrounded by a total reflection mirror and the center is hollow, and the light from the light source has a substantially uniform intensity distribution. It has a structure that makes it light. The light beam incident on the rod lens 3A from the light source 1A passes through the side surface of the rod lens 3A while being totally reflected, and is emitted at various angles on the exit side end surface (hereinafter referred to as “exit surface”) S3Ao of the rod lens 3A. Are combined, and the light intensity distribution becomes substantially uniform. The light emitted from the rod lens 3 </ b> A enters the prism array 4. Similarly, the light beam incident on the rod lens 3B from the light source 1B passes through the side surface of the rod lens 3B while being totally reflected, and there are various types of light on the exit side end surface (hereinafter referred to as “exit surface”) S3Bo of the rod lens 3B. Angled light is combined, and the light intensity distribution becomes substantially uniform. The light emitted from the rod lens 3B enters the prism array 4.

  The prism array 4 includes a half mirror 5 as a first means for reflecting or transmitting about half of the light incident from the side of the plurality of rod lenses 3A and 3B and transmitting or reflecting the rest, and the half mirror 5 The total reflection mirror 6 as a second means for reflecting the light transmitted through the mirror 5 or the light reflected by the half mirror 5 and the half mirror 5 and the prism material 40 in contact with the total reflection mirror 6 are integrated. It is formed in a single rigid body state. The light transmitted through the half mirror 5, the light reflected by the half mirror 5, the light transmitted through the half mirror 5 and then reflected by the total reflection mirror 6, and after reflected by the half mirror 5, the total mirror The light reflected by the reflection mirror 6 is emitted from one prism plane of the prism array 4 (or the prism material 40) as combined light having a single optical path (combined). In the prism array 4, the half mirror 5 and the total reflection mirror 6 are substantially parallel to each other, and are inclined by approximately 45 ° with respect to the optical axis 100A of the light source 1A and the optical axis 100B of the light source 1B.

In the first embodiment, the prism array 4 includes a half mirror 5 and a total reflection mirror 6 inside the half mirror 5 and the total reflection mirror 6 both from the rod lens 3A side and the rod lens 3B side. Arranged in order. The light incident on the prism array 4 from the rod lens 3A is incident on the half mirror 5, about 1/2 of which is reflected by the half mirror 5, and the rest is transmitted. The light reflected by the half mirror 5 is emitted from the emission surface S5 of the prism array 4. On the other hand, the light transmitted through the half mirror 5 is reflected by the total reflection mirror 6 and then exits from the exit surface S 6 of the prism array 4. The exit surfaces S5 and S6 are both formed in one prism plane of the prism array 4 (or the prism material 40). The light that has entered the prism array 4 from the rod lens 3 </ b> B enters the half mirror 5, approximately ½ passes through the half mirror 5, and the rest is reflected by the half mirror 5. The light transmitted through the half mirror 5 is emitted from the emission surface S5 of the prism array 4. On the other hand, the remaining half of the light reflected by the half mirror 5 is further reflected by the total reflection mirror 6 and then exits from the exit surface S 6 of the prism array 4. As described above, the light incident on the prism array 4 from the rod lens 3 </ b> A and the light incident on the prism array 4 from the rod lens 3 </ b> B are combined as a combined light having a single optical path (combined). The light is emitted from one plane of the prism material (or the prism material 40), that is, the prism surface having the emission surfaces S5 and S6.
In the configuration of the first embodiment, the rod lenses 3A and 3B are bonded to the opposing surface of the prism array 4, respectively. By adopting the adhesive structure, light loss at the exit surfaces of the rod lenses 3A and 3B and the incident surface of the prism array 4 can be suppressed, and the light utilization efficiency can be further enhanced, which is advantageous for high luminance.

  The condensing lens 7 is arranged so that the optical axis 700 is the boundary position Q between the half mirror 5 and the total reflection mirror 6 of the prism array 4. As a result, the light emitted from the emission surface S5 of the prism array 4 is condensed by the condenser lens 7 and then separated into red, green, and blue color light, and is approximately half on the surface of the video display element 8 ( For example, the light emitted from the emission surface S6 of the prism array 4 is also collected by the condenser lens 7 and then separated into red, green, and blue color lights. Each color light is applied to about half of the surface on the image display element 8 (for example, the lower half of the figure). That is, the emission surfaces S5 and S6 of the prism array 4 are mapped onto the image display element 8 by the light emitted from the emission surfaces S5 and S6 of the prism array 4.

FIG. 2 is an explanatory diagram of an irradiation area on the image display element 8.
In FIG. 2, the lower half area on the surface of the image display element 8 is irradiated with the condensed light 9a reflected by the total reflection mirror 6 and emitted from the exit surface S6, and the upper half area on the surface of the image display element 8 is The light transmitted through the half mirror 5 (light from the light source 1B side) and the light reflected by the half mirror 5 (light from the light source 1A side), that is, exits from the exit surface S5 without passing through the optical path of the total reflection mirror 6. The condensed light 9b is irradiated. The intensity of the condensed light 9a and the intensity of the condensed light 9b depend on the light transmission performance and reflection performance of the half mirror 5, respectively.

FIG. 3 shows an example of optical characteristics of the half mirror 5 in the illumination optical system of FIG.
As shown in FIG. 3, by making the transmittance 601 and the reflectance 602 of the half mirror 5 have substantially the same performance, the light amounts of the condensed light 9a and the condensed light 9b can be made substantially the same, and the light source 1A Even when the brightness of the light source 1B is different, the illuminance unevenness on the video display element 8 can be reduced.
At this time, the shape of the irradiation region of the light condensed on the video display element 8 is substantially similar to the emission surface of the prism array 4. From this point as well, the light utilization efficiency is improved.
Further, the reflectors 2A and 2B and the rod lenses 3A and 3B have the second focal lengths of the reflectors 2A and 2B so that the light having the substantially maximum angle is reflected at least twice in the rod lenses 3A and 3B. When the length (length in the optical axis direction) and thickness (distance in the direction perpendicular to the optical axis) of the rod lenses 3A and 3B are determined, the irradiation area on the image display element 8 is also determined from this point. It is possible to reduce unevenness in illuminance.

  According to the first embodiment, when the light emitted from each of the light sources 1A and 1B is combined by the prism array 4, the light emitted from the rod lenses 3A and 3B is reflected by the half mirror 5 and the total reflection. Since it passes through the mirror 6 only once, the optical loss in each can be suppressed. For this reason, the utilization efficiency of light can be increased and high luminance can be achieved. In addition, it is possible to reduce illuminance unevenness. Furthermore, color unevenness can be reduced.

  FIG. 4 is a block diagram of an illumination optical system for a projection display apparatus as a second embodiment of the present invention. In the second embodiment, the light incident from the rod lenses 3A and 3B is synthesized and emitted by the polarization beam splitter 5 ′ and the total reflection mirror 6 in the prism array 4 ′. The prism array 4 ′ includes a polarizing beam splitter 5 ′ serving as a first unit that reflects the S-polarized component and transmits the P-polarized component of the light incident from the plurality of rod lenses 3A and 3B, and the polarizing beam splitter. A total reflection mirror 6 as a second means for reflecting the P-polarized component light transmitted through 5 'or the S-polarized component light reflected by the polarization beam splitter 5', the polarization beam splitter 5 'and the total reflection mirror 6 and the prism material 40 in contact with 6. P-polarized component light transmitted through the polarizing beam splitter 5 ′, S-polarized component light reflected by the polarizing beam splitter 5 ′, and P-polarized light transmitted through the polarizing beam splitter 5 ′ and reflected by the total reflection mirror 6 The component light and the S-polarized component light reflected by the total reflection mirror 6 after being reflected by the polarization beam splitter 5 ′ are combined (combined) into a single optical path as a combined light and are combined into the prism array 4 ′. The light is emitted from one prism surface.

In the prism array 4 ′, the polarization beam splitter 5 ′ and the total reflection mirror 6 are arranged substantially parallel to each other, and are inclined by about 45 ° with respect to the optical axis 100A of the light source 1A and the optical axis 100B of the light source 1B. . In addition, the prism array 4 ′ includes a polarizing beam splitter 5 ′ and a total reflection mirror 6 in the order of the polarizing beam splitter 5 ′ and the total reflection mirror 6 from both the rod lens 3 A side and the rod lens 3 B side. Are arranged in The light 201A incident on the prism array 4 ′ from the rod lens 3A enters the polarization beam splitter 5 ′, and the S polarization component 201AS is reflected by the polarization beam splitter 5 ′ and the P polarization component 201AP is transmitted. The S-polarized component light 201AS reflected by the polarization beam splitter 5 ′ exits from the exit surface S5 of the prism array 4 ′. On the other hand, the P-polarized component light 201AP transmitted through the polarization beam splitter 5 ′ is reflected by the total reflection mirror 6 and then emitted from the emission surface S6 of the prism array 4 ′. Both exit surfaces S5 and S6 are formed in one prism plane of the prism array 4 ′. The light 201B incident on the prism array 4 ′ from the rod lens 3B is incident on the polarization beam splitter 5 ′, the P-polarized component 201BP is transmitted through the polarized beam splitter 5 ′, and the S-polarized component 201BS is reflected. The P-polarized component light 201BP transmitted through the polarizing beam splitter 5 ′ is emitted from the emission surface S5 of the prism array 4 ′. On the other hand, the S-polarized component light 201BS reflected by the polarization beam splitter 5 ′ is further reflected by the total reflection mirror 6 and then emitted from the emission surface S6 of the prism array 4 ′. As described above, the light 201A incident on the prism array 4 ′ from the rod lens 3A and the light 201B incident on the prism array 4 ′ from the rod lens 3B are combined light having a single optical path (combined). The light is emitted from one prism plane of the prism array 4 ′, that is, a plane having the emission surfaces S5 and S6.
Also in the configuration of the second embodiment, the rod lenses 3A and 3B are bonded to the opposing surface of the prism array 4, respectively. By adopting the adhesive structure, light loss at the exit surfaces of the rod lenses 3A and 3B and the incident surface of the prism array 4 ′ can be suppressed, and the light utilization efficiency can be further enhanced, which is advantageous for high brightness.

  In the second embodiment, the light emitted from the prism array 4 ′ is collected by a condenser lens (not shown). The light (polarized component light) emitted from the emission surface S5 of the prism array 4 ′ is collected by the condenser lens, and then separated into red, green, and blue color lights, and the surface of the image display element (not shown). The light (polarized component light) emitted from the upper half of the element surface and emitted from the exit surface S6 of the prism array 4 ′ is condensed by the condenser lens, and then is colored in red, green, and blue. Each color light is irradiated to about half of the element surface on the surface on the image display element. That is, for example, the lower half region on the surface of the video display element is irradiated with the polarized component light (201AP, 201BS) reflected from the total reflection mirror 6 and emitted from the emission surface S6, and the upper half region on the surface of the video display element, for example. The regions pass through the polarization beam splitter 5 ′, travel straight and exit from the exit surface S5, and the polarization component light (light 201BP from the light source 1B side) and the polarization component reflected by the polarization beam splitter 5 ′ and exit from the exit surface S5. Light (light 201AS from the light source 1A side) is irradiated.

When an incoherent light source such as a high-pressure mercury lamp, a xenon lamp, or an LED is used as the light source, for example, the S-polarized component and the P-polarized component are approximately the same as the polarized light component, and the polarization beam splitter 5 ′ The amount of light transmitted through and the amount of light reflected are substantially the same. For this reason, the amount of light in the upper half area and the lower half area on the surface of the image display element can be made substantially the same. As a result, even when the brightness of the light source 1A and the light source 1B is different, the image display Irradiance unevenness on the element can be reduced. In addition, since the shape of the irradiation region of the light condensed on the image display element is substantially similar to the exit surface of the prism array 4 ′, the use of light is also used from this point as in the case of the first embodiment. Increases efficiency.
Further, the reflectors 2A and 2B and the rod lenses 3A and 3B have the second focal lengths of the reflectors 2A and 2B so that the light having the substantially maximum angle is reflected at least twice in the rod lenses 3A and 3B. When the length (length in the optical axis direction) and the thickness (distance in the direction perpendicular to the optical axis) of the rod lenses 3A and 3B are determined, also from this point in the irradiation area on the video display element. Irradiance unevenness can be reduced.
In the configuration of FIG. 4, the polarizing beam splitter 5 ′ transmits the P-polarized component and reflects the S-polarized component. Conversely, the polarizing beam splitter 5 ′ transmits the S-polarized component and transmits the P-polarized component. The component may be reflected.

  Also in the second embodiment, when the light emitted from each of the light sources 1A and 1B is combined by the prism array 4 ′, the light emitted from the rod lenses 3A and 3B is converted into the polarization beam splitter 5 ′ and Since it passes through the total reflection mirror 6 only once, each optical loss can be suppressed. For this reason, the utilization efficiency of light can be increased and high luminance can be achieved. In addition, it is possible to reduce illuminance unevenness. Furthermore, color unevenness can be reduced.

5 and 6 are explanatory views of a third embodiment of the present invention. FIG. 5 is a block diagram of an illumination optical system for a projection display apparatus as a third embodiment, and FIG. 6 is a block diagram of a rod lens used in the illumination optical system of FIG. In the third embodiment, a rod lens having a polarization conversion function is used. Except for the rod lens, the configuration of the illumination optical system of the first embodiment is the same.
In FIG. 5, 301A and 301B are rod lenses each having a polarization conversion function. As shown in FIG. 6, the rod lens includes a total reflection mirror 302 and a quarter-wave retardation plate 303 on the incident surface S301i side, and a reflective polarizing plate 304 on the output surface S301o side. The total reflection mirror 302 has an optical circular opening 302b, and a total reflection mirror 302a is provided at the periphery of the opening 302b. Since the quarter-wave retardation plate 303 is affected by heat generated from the light source, it is desirable to use a material having excellent heat resistance such as quartz. It is desirable that the reflective polarizing plate 304 has a lattice structure (for example, a wire grid structure) made of aluminum or the like.

  5 and 6, light emitted from the light source 1 (light sources 1A and 1B) is incident on the rod lens 301 (rod lenses 301A and 301B) via the reflector 2 (reflectors 2A and 2B). The light collected by the reflector 2 enters the opening 302b of the total reflection mirror 302 and travels toward the exit surface while being reflected by the side surface of the rod lens 301. When light reaches the reflective polarizing plate 304 on the exit surface side of the rod lens 301, only one of the linearly polarized light components is transmitted through the reflective polarizing plate 304, and the other component is reflected. The reflected light travels through the rod lens 301 toward the light source, passes through the quarter-wave retardation plate 303, is reflected by the total reflection mirror 302a, and then passes through the quarter-wave retardation plate 303 again. And toward the exit surface side. At this time, since the light passes through the quarter-wave retardation plate 303 twice, when it reaches the reflective polarizing plate 304 again, it has a polarization direction that passes through the reflective polarizing plate 304. The light is emitted from the rod lens 301. That is, the light polarized and converted by the rod lens 301 (rod lenses 301A and 301B) is emitted from the rod lens 301 (rod lenses 301A and 301B) to the prism array 4 side.

  In the prism array 4, the half mirror 5 as a first means for reflecting or transmitting about half of incident light and transmitting or reflecting the remaining light, and the light transmitted through the half mirror 5 or the half mirror The incident light is transmitted and reflected by the total reflection mirror 6 as the second means for reflecting the light reflected by the light 5, the light transmitted through the half mirror 5, and the light reflected by the half mirror 5. The light that has been transmitted through the half mirror 5 and then reflected by the total reflection mirror 6 and the light that has been reflected by the half mirror 5 and then reflected by the total reflection mirror 6 are aligned in one optical path ( The combined light is emitted from one prism surface of the prism array 4 as combined light. The emitted light is condensed by the condensing lens 7, color-separated, and irradiated onto the image display element.

Also in the configuration of the third embodiment, as in the case of the first embodiment, when the light emitted from each of the light sources 1A and 1B is combined by the prism array 4, it is emitted from the rod lenses 3A and 3B. Since the transmitted light passes through the half mirror 5 and the total reflection mirror 6 only once, the light loss in each can be suppressed. For this reason, the utilization efficiency of light can be increased and high luminance can be achieved. In addition, it is possible to reduce illuminance unevenness. In particular, since the polarization direction of the light emitted from the rod lens can be made substantially linearly polarized without increasing the outer dimensions of the illumination optical system, for example, when a liquid crystal panel is used as an image display element, illumination optics It is easy to reduce the size of the system and the entire apparatus. Furthermore, color unevenness can be reduced.
In the configuration of the third embodiment, the prism array 4 includes the half mirror 5 and the total reflection mirror 6. However, as in the prism array 4 ′ in the second embodiment (FIG. 4), A configuration including a polarizing beam splitter and a total reflection mirror may be used.

7 and 8 are explanatory views of a fourth embodiment of the present invention. FIG. 7 is a configuration diagram of an illumination optical system for a projection-type image display device as a fourth embodiment, and FIG. 8 is an explanatory diagram of an irradiation area on an image display element by the illumination optical system of FIG. In the fourth embodiment, a condenser lens (first condenser lens) is provided between the rod lens and the prism array. Other configurations are the same as those in the first embodiment.
In FIG. 7, 401A and 401B are condensing lenses (first condensing lenses) disposed between the rod lenses 3A and 3B and the prism array 4, respectively. The condensing lenses 401A and 401B are arranged so that the exit surfaces S3o (exit surfaces S3Ao and S3Bo) of the rod lenses 3A and 3B are in the vicinity of their focal positions. The light emitted from the light source 1 (light sources 1A and 1B) is reflected by the reflector 2 (reflectors 2A and 2B), is incident on the rod lens 3 (rod lenses 3A and 3B), and the light intensity distribution is made uniform. The light exits from the exit surface S3o (exit surfaces S3Ao, S3Bo) of the lens 3 (rod lenses 3A, 3B). The light emitted from the exit surface S3o (exit surfaces S3Ao, S3Bo) of the rod lens 3 (rod lenses 3A, 3B) is substantially the same as the light ray angle distribution when condensed by the reflector 2 (reflectors 2A, 2B). However, the light emitted from the exit surface S3o (exit surfaces S3Ao, S3Bo) of the rod lens 3 (rod lenses 3A, 3B) is the first condenser lens 401 (first condenser lenses 401A, 401B). ) To be substantially parallel light. The light that has been made substantially parallel light by the first condenser lens 401 (first condenser lenses 401 </ b> A and 401 </ b> B) enters the prism array 4. In the prism array 4, the half mirror 5 as a first means for reflecting or transmitting about half of incident light and transmitting or reflecting the remaining light, and the light transmitted through the half mirror 5 or the half mirror The incident light is transmitted and reflected by the total reflection mirror 6 as the second means for reflecting the light reflected by the light 5, the light transmitted through the half mirror 5, and the light reflected by the half mirror 5. The light that has been transmitted through the half mirror 5 and then reflected by the total reflection mirror 6 and the light that has been reflected by the half mirror 5 and then reflected by the total reflection mirror 6 are aligned in one optical path ( The combined light is emitted from one prism surface of the prism array 4 as combined light. The emitted light is condensed by the second condenser lens 7, is color-separated, and is irradiated onto the video display element 8.

  In the fourth embodiment, the shape of the exit surface S3o (exit surfaces S3Ao, S3Bo) of the rod lens 3 (rod lenses 3A, 3B) is the same as the first condenser lens 401 (first condenser lenses 401A, 401B). ) And the second condenser lens 7. That is, the exit surface S3o (exit surfaces S3Ao, S3Bo) of the rod lens 3 (rod lenses 3A, 3B) and the irradiated surface on the image display element 8 are in a conjugate relationship. For this reason, the shape of the exit surface S3Ao of the rod lens 3A and the shape of the exit surface S3Bo of the rod lens 3B are superimposed on the image display element 8 by the second condenser lens 7 via the condenser lenses 401A and 401B, respectively. Will be.

  In FIG. 8, the condensed light 10A is the condensed light emitted from the emission surface S3Ao of the rod lens 3A, and the condensed light 10B is the collected light emitted from the emission surface S3Bo of the rod lens 3B. Since each condensed light emitted from the emission surface S3o (emission surface S3Ao, S3Bo) of each rod lens 3 (rod lens 3A, 3B) is imaged in a state of being superimposed on the video display element 8, the light source 1A and Even when the brightness of the light source 1B is different and the transmittance and the reflectance of the half mirror 5 are different, the illuminance unevenness on the image display element 8 can be suppressed. The half mirror 5 has a possibility that the transmittance and the reflectance change depending on the incident angle of light, which may cause unevenness in illuminance, but according to the fourth embodiment, as described above, Since the condensing lens 401 (the first condensing lenses 401A and 401B) can make the incident light to the prism array 4 substantially parallel light, the angle dependency of the half mirror 5 is compensated to reduce illuminance unevenness. In addition, the prism array 4 can be miniaturized. Color unevenness can also be reduced.

  In the fourth embodiment, the shape of the irradiation area of the light irradiated to the image display element is substantially similar to the shape of the exit surface of the rod lens 3 (rod lenses 3A and 3B). From the viewpoint of improving efficiency, the shape of the exit surface of the rod lens 3 (rod lenses 3A, 3B) is substantially similar to the planar shape of the video display element 8. Further, the spatial distance between the first condenser lens 401 (first condenser lenses 401A and 401B) and the rod lens 3 (rod lenses 3A and 3B) (first condenser lens 401 (first condenser lens 401A). , 401B) is approximately inversely proportional to the size of the condensed light collected on the image display element 8, and thus the spatial distance and the first condenser lens 401 (first The curvatures of the condenser lenses 401A and 401B) are set in accordance with the size of the video display element 8.

Also in the configuration of the fourth embodiment, as in the case of the first embodiment, when the light emitted from each of the light sources 1A and 1B is combined by the prism array 4, it is emitted from the rod lenses 3A and 3B. Since the transmitted light passes through the half mirror 5 and the total reflection mirror 6 only once, the light loss in each can be suppressed. For this reason, the utilization efficiency of light can be increased and high luminance can be achieved. Further, as described above, it is possible to reduce illuminance unevenness and downsize the prism array 4, the illumination optical system, and the entire apparatus. Furthermore, color unevenness can be reduced.
In the configuration of the fourth embodiment, the prism array 4 includes the half mirror 5 and the total reflection mirror 6. However, as in the prism array 4 'in the second embodiment (FIG. 4). In addition, a configuration including a polarization beam splitter and a total reflection mirror may be used. When a polarizing beam splitter is used, it is particularly easy to reduce illuminance unevenness due to the incident angle of light.

FIG. 9 is a block diagram of an illumination optical system for a projection display apparatus as a fifth embodiment of the present invention. In the fifth embodiment, a lens array for collimating outgoing light from the prism array side is disposed on the rear stage side of the prism array. Other configurations are the same as those in the first embodiment.
In FIG. 9, reference numeral 501 denotes a lens array that is arranged between the exit surface of the prism array 4 and the condenser lens 7, and collimates the light emitted from the prism array 4, and 501 a is a prism array in the lens array 501. A lens cell 501 b corresponding to the emission surface S 5 of 4 is a lens cell corresponding to the emission surface S 6 of the prism array 4 in the lens array 501. The lens array 501 is divided and arranged on both sides with the optical axis 700 of the condenser lens 7 as a boundary. The lens cells 501a and 501b of the lens array 501 are configured such that the exit surfaces S5 and S6 of the prism array 4 are in the vicinity of their focal positions. The light emitted from the exit surface S5 of the prism array 4 is incident on the lens cell 501a of the lens array 501 and converted into parallel light, and then enters the condenser lens 7 and exits from the exit surface S6 of the prism array 4. Enters the lens cell 501 b to be parallel light, and then enters the condenser lens 7. The light emitted from the lens cell 501a and the light emitted from the lens cell 501b are collected by a condenser lens, separated into color light, and superimposed on the image display element 8. That is, the exit surfaces S5 and S6 of the prism array 4 are superimposed on the image display element 8 as shown in FIG. Other parts are the same as those in the first embodiment. Since the emission surfaces S5 and S6 of the prism array 4 are superimposed on the image display element 8, the brightness of the light source 1A and the light source 1B is different, and the transmittance and reflectance of the half mirror 5 as the first means. Even if they are different, it is possible to suppress the illuminance unevenness on the image display element.

  In the fifth embodiment as well, the shape of the light irradiation area irradiated to the image display element is substantially similar to the shape of the exit surface of the rod lens 3 (rod lenses 3A and 3B). From the viewpoint of increasing the utilization efficiency, the shape of the exit surface of the rod lens 3 (rod lenses 3A, 3B) is made to be substantially similar to the planar shape of the video display element 8. Further, since the spatial distance between the lens array 501 and the prism array 4 (substantially equal to the focal length of the lens array 501) is inversely proportional to the size of the condensed light focused on the video display element, the spatial distance The curvature of the lens array 501 (lens cells 501a and 501b) is set in accordance with the size of the video display element.

Also in the configuration of the fifth embodiment, as in the case of the first embodiment, when the light emitted from each of the plurality of light sources 1A and 1B is combined by the prism array 4, the rod lenses 3A and 3B. Since the light emitted from each passes through the half mirror 5 and the total reflection mirror 6 only once, the light loss in each can be suppressed. For this reason, the utilization efficiency of light can be increased and high luminance can be achieved. In addition, it is possible to reduce illuminance unevenness and color unevenness and to downsize the prism array 4, the illumination optical system, and the entire apparatus.
Also in the configuration of the fifth embodiment, the prism array 4 reflects or transmits about 1/2 of the incident light, and the half mirror 5 as a first means for transmitting or reflecting the rest, Although it is configured to include the total reflection mirror 6 as the second means for reflecting the light transmitted through the half mirror 5 or the light reflected by the half mirror 5, the second embodiment (FIG. As in the prism array 4 ′ in 4), a configuration may be adopted in which a polarization beam splitter is provided as the first means, and a total reflection mirror is provided as the second means. When a polarizing beam splitter is used as the second means, it is particularly easy to reduce illuminance unevenness due to the incident angle of light.

FIG. 10 is a configuration example diagram of a projection type image display apparatus using the illumination optical system of FIG.
In FIG. 10, reference numeral 801 denotes an illumination optical system configured as shown in FIG. 9, 701 denotes a condenser lens that collimates the focused light from the illumination optical system 801, 702 denotes a TIR prism (Total Internal Reflection Prism), and 703 denotes an image display. An element, 704 is a projection lens unit, 802 is a rectifying power supply circuit that supplies power to the light source, and 804 is a drive circuit that drives the video display element 703. The TIR prism is two prismatic prisms, and a narrow gap may be provided between the two triangular prisms, or an adhesive having a sufficiently low refractive index with respect to the prism. The two triangular prisms may be bonded to each other. A rectified power supply circuit 802 is connected to a plurality of light sources 1 (light sources 1A and 1B) in the illumination optical system 801. When a voltage is applied from the rectified power supply circuit 802, the light source 1 (light sources 1A and 1B) emits light. Then, the emitted light is emitted. The light source 1 (light sources 1A and 1B) is cooled by a cooling device (not shown) arranged in the vicinity of the light source.

In the illumination optical system 801, light emitted from the plurality of light sources 1 (light sources 1A and 1B) is combined by the prism array 4 as described with reference to FIG. The light emitted from the prism array 4 is collimated by the lens array 501 and then condensed by the condenser lens 7. The light emitted from the condenser lens 7 is converted into substantially parallel light by the condenser lens 701 and then enters the TIR prism 702. When the angle formed between the direction of the light incident on the TIR prism 702 and the reflection surface of the TIR prism 702 is larger than the total reflection angle, the incident light is reflected by the reflection surface of the TIR prism 702 and formed. When the angle is small, incident light passes through the reflecting surface. In this configuration example, the angle formed by the light emitted from the condenser lens 701 and the reflection surface of the TIR prism 702 is larger than the total reflection angle, so that the light is reflected by the reflection surface.
For example, in the video display element 703 configured by a micromirror array or the like, an optical image is formed by performing angle modulation on the irradiated light in accordance with the video signal from the drive circuit 804, and the optical image light is Reflected toward the TIR prism 702. At this time, since the angle formed by the light reflected by the image display element 703 and the reflection surface of the TIR prism 702 is smaller than the total reflection angle, the optical image light passes through the reflection surface of the TIR prism 702. The light is transmitted and incident on the projection lens unit 704. The projection lens unit 704 enlarges and projects it onto a screen (not shown) to display an image.
In the configuration of FIG. 10, the illumination optical system 801, the condenser lens 701, the TIR prism 702, the image display element 703, and the projection lens unit 704 constitute an optical engine. A projection type image display apparatus is configured including the optical engine, the rectifying power supply circuit 802 and the drive circuit 804.

According to the projection-type image display device, since the illumination optical system with high light use efficiency and little illuminance unevenness is used, it is possible to display a bright high-quality image display while saving power.
In the projection type image display device of FIG. 10, the illumination optical system having the configuration of FIG. 9 is used and the TIR prism 702 is used as the color synthesizing means. However, the present invention is not limited to this, and illumination optics is used. As the system, the configuration shown in FIG. 1, the configuration shown in FIG. 4, the configuration shown in FIG. 5, the configuration shown in FIG. 7, and the configuration shown in FIG. Of these, a polarizing beam splitter is used instead of the half mirror, a polarizing beam splitter is used instead of the half mirror in the configuration shown in FIG. 7, and a polarizing beam is used instead of the half mirror in the configuration shown in FIG. For example, a cross dichroic prism may be used as the color synthesizing means.

It is a block diagram of the illumination optical system for projection type video display apparatuses of a 1st Example. It is explanatory drawing of the irradiation area | region on the image display element by the illumination optical system of FIG. It is an optical characteristic example figure of the half mirror in the illumination optical system of FIG. It is a block diagram of the illumination optical system of a 2nd Example. It is a block diagram of the illumination optical system of a 3rd Example. It is a block diagram of the rod lens used for the illumination optical system of FIG. It is a block diagram of the illumination optical system of a 4th Example. It is explanatory drawing of the irradiation area | region on the image display element by the illumination optical system of FIG. It is a block diagram of the illumination optical system of a 5th Example. It is a structural example figure of a projection type video display apparatus.

Explanation of symbols

1, 1A, 1B ... light source,
2, 2A, 2B ... reflectors,
3, 3A, 3B, 301A, 301B ... rod lens,
4, 4 '... Prism array,
5 ... Half mirror,
5 '... Polarizing beam splitter,
6, 302 ... Total reflection mirror,
7, 401A, 401B ... Condensing lens,
8, 703 ... video display element,
40 ... Prism material,
302a ... Total reflection mirror part,
302b ... opening,
303 ... 1/4 wavelength phase difference plate,
304: reflective polarizing plate,
501 ... Lens array,
701: condenser lens,
702 ... TIR prism,
704 ... Projection lens unit,
801: Illumination optical system,
802 ... a rectifying power supply circuit,
804 ... Drive circuit.

Claims (10)

An illumination optical system of a projection type video display device that irradiates a video display element with light from a light source side to form an optical image according to a video signal, and displays an image by expanding and projecting,
A light source unit comprising a plurality of light sources;
A plurality of rod lenses arranged corresponding to each of the plurality of light sources of the light source unit, each of which uniformizes and emits incident light from the light source side;
Of the light incident from the plurality of rod lens sides, the first means reflects about 1/2 light or light of a predetermined polarization component and transmits the remaining light or light of another predetermined polarization component And a second means for reflecting the light transmitted through the first means or the light reflected by the first means, and a prism material in contact with the two means are integrally formed, and the first means A prism array for emitting transmitted light, reflected light from the means, and reflected light from the second means from one prism surface;
A condensing lens that condenses the emitted light from the prism array side;
The emitted light from each of the plurality of light sources passes through the corresponding rod lenses, and then is synthesized on one optical path by the prism array, and the synthesized light is condensed by the condenser lens. An illumination optical system for a projection-type image display apparatus, wherein the image-display element side emits light. An illumination optical system of a projection type video display device that irradiates a video display element with light from a light source side to form an optical image according to a video signal, and displays an image by expanding and projecting,
A light source unit comprising a plurality of light sources;
A plurality of rod lenses arranged corresponding to each of the plurality of light sources of the light source unit, each of which uniformizes and emits incident light from the light source side;
Of the light incident from the plurality of rod lens sides, the first means reflects about 1/2 light or light of a predetermined polarization component and transmits the remaining light or light of another predetermined polarization component And a second means for reflecting the light transmitted through the first means or the light reflected by the first means, and a prism material in contact with the two means are integrally formed, and the first means A prism array for emitting transmitted light, reflected light from the means, and reflected light from the second means from one prism surface;
A first condensing lens that is disposed between each of the plurality of rod lenses and the prism array, and condenses the emitted light of each of the plurality of rod lenses and enters the prism array;
A second condensing lens that condenses the light emitted from the prism array side;
The emitted light from each of the plurality of light sources passes through the corresponding rod lens, and then is collected by the first condenser lens, and is synthesized on one optical path by the prism array, An illumination optical system for a projection-type image display apparatus, wherein the combined light is condensed by the second condenser lens and emitted to the image display element side. An illumination optical system of a projection type video display device that irradiates a video display element with light from a light source side to form an optical image according to a video signal, and displays an image by expanding and projecting,
A light source unit comprising a plurality of light sources;
A plurality of rod lenses arranged corresponding to each of the plurality of light sources of the light source unit, each of which uniformizes and emits incident light from the light source side;
Of the light incident from the plurality of rod lens sides, the first means reflects about 1/2 light or light of a predetermined polarization component and transmits the remaining light or light of another predetermined polarization component And a second means for reflecting the light transmitted through the first means or the light reflected by the first means, and a prism material in contact with the two means are integrally formed, and the first means A prism array for emitting transmitted light, reflected light from the means, and reflected light from the second means from one prism surface;
A lens array consisting of an assembly of a plurality of lenses, which collimates the light emitted from the prism array side;
The emitted light from each of the plurality of light sources passes through the corresponding rod lenses, and is synthesized on one optical path by the prism array, and the synthesized light is collimated by the lens array, An illumination optical system for a projection-type image display apparatus, characterized in that the light is emitted toward the image display element side.   4. The illumination optical system for a projection display apparatus according to claim 1, wherein said prism array is a half mirror for said first means and a total reflection mirror for said second means.   4. The illumination optical system for a projection display apparatus according to claim 1, wherein said prism array is a polarizing beam splitter, and said second means is a total reflection mirror.   Each of the plurality of rod lenses includes a total reflection mirror having a circular opening and a ¼ wavelength phase difference plate on an end side where light enters, and a reflection type on an end side where light exits. The illumination optical system of the projection type video display apparatus according to claim 1, 2 or 3, wherein the polarizing plate is provided with a polarizing plate.   4. The illumination optical system of a projection display apparatus according to claim 1, wherein the prism array has a configuration in which the first means and the second means are arranged substantially parallel to each other.   In the plurality of rod lenses, the light from the first rod lens side is incident on the prism array from one plane side of the first means, and the light from the second rod lens side is the first lens. 4. An illumination optical system for a projection display apparatus according to claim 1, 2, or 3, wherein the light is incident from the other plane side of the means.   The illumination optical system according to any one of claims 1 to 8, color separation means for separating light irradiated with light emitted from the illumination optical system into red, green, and blue color lights, and the separation A projection-type image display apparatus comprising: an image display element that irradiates colored light and modulates the color light according to an image signal to form an optical image; and a projection unit that enlarges and projects the optical image light. Optical engine.   The illumination optical system according to any one of claims 1 to 8, color separation means for separating light irradiated with light emitted from the illumination optical system into red, green, and blue color lights, and the separation Image display element that irradiates the color light and modulates the color light according to the video signal to form an optical image, projection means for enlarging and projecting the optical image light, and a power supply circuit for driving a plurality of light sources of the illumination optical system And a drive circuit for driving the video display element based on a video signal.

Images