JP4678231B2 - Uniform optical element, illumination device and image display device - Google Patents

Description

  The present invention relates to a homogenizing optical element, an illuminating device, and an image display device, and more particularly, to a technique of a homogenizing optical element and an illuminating device used in combination with a liquid crystal spatial light modulator.

  As a configuration for improving the illuminance ratio, a fly eye integrator or a rod integrator that makes light from a light source substantially uniform is used in a projector illumination device that is an image display device. Of these, the rod integrator causes light from the light source to be superimposed on the exit surface by propagating the light while reflecting it on the inner surface. By making the light from the light source uniform and entering the spatial light modulation device, it is possible to display an image with reduced brightness unevenness. In addition, as a spatial light modulation device that modulates light from a light source according to an image signal, for example, a liquid crystal type spatial light modulation device is used. A liquid crystal spatial light modulator performs modulation by converting the polarization state of incident light. A bright projection image can be obtained by converting light from the light source into polarized light having a specific vibration direction that can be modulated by the liquid crystal spatial light modulator. For example, Patent Document 1 proposes a technique for combining a configuration for converting light from a light source into polarized light having a specific vibration direction and a rod integrator.

JP 2000-131647 A

  In the technique proposed in Patent Document 1, light from a light source is converted into polarized light having a specific vibration direction using a polarization beam splitter, and then made uniform by a rod integrator. It is conceivable that the light from the light source changes from linearly polarized light to elliptically polarized light, for example, by repeatedly reflecting in the rod integrator. For this reason, even if light from the light source is converted into polarized light in a specific vibration direction by the polarization beam splitter, the polarization state of the light may change in the rod integrator. When the polarization state of the light is changed by the rod integrator, it becomes difficult to use the light from the light source with high efficiency, so that the illumination efficiency and the contrast are lowered. In addition, if the number of reflections by the rod integrator is reduced, the light becomes insufficiently uniform. Thus, the conventional technique has a problem that it is difficult to supply polarized light in a specific vibration direction with high efficiency at a high illuminance ratio. The present invention has been made in view of the above-described problems, and a uniformizing optical element, a lighting device, and the uniformizing optics for supplying polarized light in a specific vibration direction with high illuminance ratio and high efficiency. An object of the present invention is to provide an image display device capable of displaying a bright image with reduced brightness unevenness by using an element or a lighting device.

  In order to solve the above-described problems and achieve the object, according to the present invention, a uniformizing portion that makes the intensity distribution of the light beam substantially uniform, and a first vibration direction provided on one end face of the uniformizing portion. Of the first reflection type polarizing plate that transmits the polarized light of the first vibration direction and reflects the polarized light of the second vibration direction substantially orthogonal to the first vibration direction, and the first reflection type polarizing plate of the uniformizing portion is provided. A second reflective polarizing plate that is provided on the other end surface different from the formed end surface, transmits polarized light in the first vibration direction, and reflects polarized light in the second vibration direction. The homogenizing optical element can be provided.

  For example, when light is incident on the uniformizing optical element from the first reflective polarizing plate side, the first reflective polarizing plate causes the first vibration direction of the light incident on the first reflective polarizing plate. Is transmitted in the direction of the uniformizing section. After that, the polarized light in the first vibration direction out of the light incident on the second reflective polarizing plate is transmitted through the second reflective polarizing plate and then emitted from the uniformizing optical element. Of the light incident on the second reflective polarizing plate, the polarized light in the second vibration direction is reflected by the second reflective polarizing plate. The light reflected by the second reflective polarizing plate propagates in the opposite direction to the inside of the uniformizing portion and enters the first reflective polarizing plate. Of the light incident on the first reflective polarizing plate from the homogenizing unit, the polarized light in the second vibration direction is reflected by the first reflective polarizing plate, and then the second reflected light is reflected again inside the uniformizing unit. Propagated in the direction of the polarizing plate. Of the light traveling in the direction from the first reflective polarizing plate to the second reflective polarizing plate, the polarized light in the first vibration direction is transmitted through the second reflective polarizing plate. Of the light traveling in the direction from the first reflective polarizing plate to the second reflective polarizing plate, the polarized light in the second vibration direction repeats the above circulation. By reusing polarized light in the second vibration direction, polarized light in the first vibration direction can be emitted one after another.

  The homogenizing optical element makes the intensity distribution of the incident light beam substantially uniform by using the homogenizing portion. Further, the homogenizing optical element uses the second reflective polarizing plate, so that even if the polarization state of the light changes while propagating through the homogenizing portion, the polarized light having a specific vibration direction is used. Only polarized light in the first vibration direction can be emitted. For example, when a rod integrator is used for the homogenizer, the higher the frequency of reflection, the more uniform the light, while the degree of change in the polarization state of the light increases. The present invention is configured to emit only polarized light in the first vibration direction, so that the light can be made sufficiently uniform and only polarized light in the first vibration direction can be emitted. Furthermore, by reusing the polarized light in the second vibration direction using the first reflective polarizing plate, the polarized light in the first vibration direction can be efficiently emitted. Thereby, a uniform optical element for supplying polarized light in a specific vibration direction with high efficiency at a high illuminance ratio can be obtained.

  Moreover, according to the preferable aspect of this invention, it is desirable for a uniformization part to provide a rod integrator. The rod integrator superimposes light from the light source on the exit surface by propagating the light while reflecting it on the inner surface. By using the rod integrator, the intensity distribution of the incident light beam can be made substantially uniform. Thereby, the intensity distribution of the incident light beam can be made substantially uniform.

  Moreover, according to a preferable aspect of the present invention, it is desirable to include a plurality of rod integrators provided in parallel in a direction substantially orthogonal to the optical axis. The light transmitted through the first reflective polarizing plate propagates while being reflected by each of the plurality of rod integrators provided. When a plurality of rod integrators are used, the frequency of light reflection is increased compared to the case of using a single rod integrator, and the intensity distribution of the luminous flux can be made sufficiently uniform. Thereby, the intensity distribution of the incident light beam can be made more uniform.

  Further, as a preferred aspect of the present invention, it is desirable to provide a rod integrator that substantially uniforms the intensity distribution of light beams from a plurality of rod integrators provided in parallel in a direction substantially orthogonal to the optical axis. With this configuration, the light from the plurality of rod integrators can be made uniform as a whole. Thereby, the intensity distribution of the incident light beam can be made more uniform.

  Furthermore, according to the present invention, the light source unit that supplies light, the polarization conversion unit that converts the light from the light source unit into polarized light in the first vibration direction, and the intensity distribution of the light flux from the polarization conversion unit are substantially uniform. There is provided a lighting device characterized in that the uniformizing optical element is the uniformizing optical element described above. By supplying polarized light in the first vibration direction to the uniform optical element, it is possible to efficiently emit polarized light in the first vibration direction with a high illuminance ratio. Thereby, the illuminating device which can supply the polarized light of a specific vibration direction with high efficiency with high illuminance ratio can be obtained.

  Further, according to the present invention, the light source unit that supplies light, the polarization conversion unit that converts the light from the light source unit into the polarized light in the first vibration direction, and the intensity distribution of the light flux from the polarization conversion unit are substantially reduced. A uniformizing unit for uniforming and an end surface of the homogenizing unit opposite to the side where the polarization converting unit is provided, and transmits polarized light in the first vibration direction out of the light from the uniformizing unit. And a reflective polarizing plate that reflects polarized light in the second vibration direction substantially orthogonal to the first vibration direction, and the polarization conversion unit traveled from the reflective polarizing plate toward the polarization conversion unit. It is possible to provide an illuminating device including a reflecting unit that reflects light to travel toward the uniformizing unit.

  The polarized light in the first vibration direction from the polarization conversion unit passes through the uniformizing unit and then enters the reflective polarizing plate. Of the light incident on the reflective polarizing plate, the polarized light in the first vibration direction is transmitted through the reflective polarizing plate and then emitted from the illumination device. Of the light incident on the reflective polarizing plate, the polarized light in the second vibration direction is reflected by the reflective polarizing plate, and then propagates through the inside of the uniformizing unit in the direction of the polarization converting unit, which is the opposite direction. To do. The reflection unit reflects the light traveling in the direction of the polarization conversion unit in the direction of the uniformization unit. The light traveling from the reflecting portion toward the uniformizing portion propagates again through the uniformizing portion toward the reflective polarizing plate. Of the light traveling in the direction of the reflective polarizing plate, the polarized light in the first vibration direction is transmitted through the reflective polarizing plate. Of the light traveling in the direction from the first reflective polarizing plate to the second reflective polarizing plate, the polarized light in the second vibration direction repeats the above circulation. By reusing polarized light in the second vibration direction, polarized light in the first vibration direction can be emitted one after another.

  The illumination device uses the uniformizing unit to make the intensity distribution of the incident light beam substantially uniform. In addition, the illumination device uses the reflective polarizing plate, so that even if the polarization state of the light changes while propagating through the uniformizing portion, the first polarization light having a specific vibration direction is used. Only polarized light in the vibration direction can be emitted. For example, when a rod integrator is used for the homogenizer, the light can be sufficiently homogenized as the frequency of reflection increases, while the polarization state changes. The present invention is configured to emit only polarized light in the first vibration direction, so that the light can be made sufficiently uniform and only polarized light in the first vibration direction can be emitted. Furthermore, by reusing the polarized light in the second vibration direction using the reflecting portion, the polarized light in the first vibration direction can be efficiently emitted. Thereby, the illuminating device which can supply the polarized light of a specific vibration direction with high illuminance ratio with high efficiency can be obtained.

  Moreover, as a preferable aspect of the present invention, it is desirable that the uniformizing unit includes a rod integrator. By using the rod integrator, the intensity distribution of the incident light beam can be made substantially uniform. Thereby, the intensity distribution of the incident light beam can be made substantially uniform.

  Moreover, as a preferable aspect of the present invention, it is desirable to include a plurality of rod integrators provided in parallel in a direction substantially orthogonal to the optical axis. Light from the polarization conversion unit propagates while being reflected by each of the plurality of rod integrators provided. When a plurality of rod integrators are used, the frequency of light reflection is increased compared to the case of using a single rod integrator, and the intensity distribution of the luminous flux can be made sufficiently uniform. Thereby, the intensity distribution of the incident light beam can be made more uniform.

  Further, as a preferred aspect of the present invention, it is desirable to provide a rod integrator that substantially uniforms the intensity distribution of light beams from a plurality of rod integrators provided in parallel in a direction substantially orthogonal to the optical axis. With this configuration, it becomes possible to further uniformize light from a plurality of rod integrators. Thereby, the intensity distribution of the incident light beam can be made more uniform.

  Moreover, as a preferable aspect of the present invention, it is desirable that the polarization conversion units are arranged in an array. Thereby, it is set as the structure using a some light source part, and bright illumination light can be obtained easily.

  Furthermore, according to the present invention, it is possible to provide an image display device characterized by including the illumination device described above and a spatial light modulation device that modulates light from the illumination device in accordance with an image signal. By using the above-described illumination device, it is possible to supply polarized light in a specific vibration direction with high efficiency at a high illuminance ratio. Thereby, an image display apparatus capable of displaying a bright image with reduced brightness unevenness can be obtained.

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

  FIG. 1 shows a top view of a lighting device 100 according to Embodiment 1 of the present invention. The lighting device 100 includes a light emitting diode element (hereinafter referred to as “LED”) 101 which is a solid light source. The LED 101 is a surface-emitting light source unit that mainly supplies light from the surface of the chip. The LED 101 supplies light in the Z-axis direction that is the optical axis AX direction. A polarization conversion element 102 is provided at a position where light from the LED 11 is incident. The polarization conversion element 102 converts light from the LED 101 serving as the light source unit into polarized light in the first vibration direction, for example, p-polarized light. A condensing lens LN is provided in the optical path between the LED 101 and the polarization conversion element 102. The condensing lens LN causes the light from the LED 101 to converge and enter the polarization conversion element 102. Instead of the condensing lens LN, other configurations such as a collimator lens or a reflector may be used.

  The polarization conversion element 102 includes a polarization separation film 111, a reflection film 112, and a λ / 2 phase plate 113. Light incident on the polarization conversion element 102 from the LED 101 is p-polarized light that is polarized light in the first vibration direction and s-polarized light that is polarized light in the second vibration direction that is substantially orthogonal to the first vibration direction. Light having a random polarization state including light. Of the light incident on the polarization separation film 111 of the polarization conversion element 102, p-polarized light is transmitted through the polarization separation film 111 and emitted from the polarization conversion element 102.

  Of the light incident on the polarization separation film 111, the s-polarized light is reflected by the polarization separation film 111 and bent in the optical path, and then travels in the direction of the reflection film 112. The s-polarized light incident on the reflection film 112 travels in the Z-axis direction, which is the emission direction, after the optical path is bent by reflection at the reflection film 112. The λ / 2 phase plate 113 is provided at a position where light reflected by the reflective film 112 enters. The s-polarized light incident on the λ / 2 phase plate 113 is converted into p-polarized light and emitted from the λ / 2 phase plate 113. In this way, the polarization conversion element 102 converts the light from the LED 101 into p-polarized light. In addition, it is desirable to provide an antireflection film for preventing reflection of light from the LED 101 on the incident surface of the polarization conversion element 102. By providing the antireflection film, light from the LED 101 can be efficiently incident on the polarization conversion element 102.

  A uniformizing optical element 103 is provided on the exit side of the polarization conversion element 102. The homogenizing optical element 103 makes the intensity distribution of the light beam from the polarization conversion element 102, which is a polarization conversion unit, substantially uniform. The homogenizing optical element 103 includes a first reflective polarizing plate 121, a rod integrator 122, and a second reflective polarizing plate 125. As shown in the top surface configuration of FIG. 1 and the side surface configuration of FIG. 2, the polarization conversion element 102 and the uniformizing optical element 103 are coupled to each other so as to form one rectangular parallelepiped shape.

  FIG. 3 shows a perspective configuration of the homogenizing optical element 103. The first reflective polarizing plate 121 and the second reflective polarizing plate 125 transmit p-polarized light that is polarized light in the first vibration direction, and a second vibration direction that is substantially orthogonal to the first vibration direction. The s-polarized light that is the polarized light is reflected. The first reflective polarizing plate 121 is provided on the surface on the polarization conversion element 102 side, which is one end surface of the rod integrator 122. The second reflective polarizing plate 125 is provided on the surface on the irradiated surface I side, which is the other end surface of the rod integrator 122 different from the end surface on which the first reflective polarizing plate 121 is provided.

  As the first reflective polarizing plate 121 and the second reflective polarizing plate 125, wires in which wires made of metal, for example, aluminum, are provided in a grid pattern on a substrate made of an optically transparent glass member. A grid polarizer can be used. The wire grid polarizer transmits polarized light whose vibration direction is substantially perpendicular to the wire and reflects polarized light whose vibration direction is substantially parallel to the wire. By providing a wire grid polarizer so that the wire is substantially perpendicular to the vibration direction of polarized light in a specific vibration direction, only polarized light in a specific vibration direction can be transmitted. The rod integrator 122 is a uniformizing unit that makes the intensity distribution of the light flux from the first reflective polarizing plate 121 substantially uniform. The rod integrator 122 has a rectangular parallelepiped transparent member. The rod integrator 122 superimposes the light on the exit surface by propagating the light while reflecting it at the interface between the transparent member and the air.

  Returning to FIG. 1, a transparent member layer 114 is formed in a portion other than the portion where the λ / 2 phase plate 113 is provided in the portion where the polarization conversion element 102 and the uniformizing optical element 103 are in contact. The transparent member layer 114 is configured by filling a refractive index matching liquid such as index matching oil. By providing the transparent member layer 114, a reflection loss caused by air entering between the polarization conversion element 102 and the uniformizing optical element 103 is reduced, and the light from the polarization conversion element 102 is efficiently uniformized optical element 103. It can be made to enter.

  In order to make the light from the LED 101 incident on the irradiated surface I efficiently, it is desirable that the shape of the second reflective polarizing plate 125 and the shape of the irradiated surface I are substantially the same or substantially similar to each other. . With this configuration, it is possible to efficiently illuminate the entire irradiated surface I with light emitted from the second reflective polarizing plate 125. In this embodiment, since the polarization conversion element 102 and the uniformizing optical element 103 are combined to form one rectangular parallelepiped shape, the surface on the LED 101 side of the polarization conversion element 102, the first reflective polarizing plate 121, Both end surfaces of the rod integrator 122 also have a shape that is substantially the same as or similar to the irradiated surface I.

  The p-polarized light incident on the uniformizing optical element 103 from the first reflective polarizing plate 121 side passes through the first reflective polarizing plate 121 and enters the rod integrator 122. The light that has entered the rod integrator 122 from the first reflective polarizing plate 121 propagates through the rod integrator 122 and then enters the second reflective polarizing plate 125. Of the light incident on the second reflective polarizing plate 125, p-polarized light is transmitted through the second reflective polarizing plate 125 and then supplied to the irradiated surface I.

  Of the light incident on the second reflective polarizing plate 125, the s-polarized light is reflected by the second reflective polarizing plate 125. The s-polarized light reflected by the second reflective polarizing plate 125 propagates through the rod integrator 122 in the negative Z direction, which is the opposite direction, and enters the first reflective polarizing plate 121. Of the light incident on the first reflective polarizing plate 121 from the rod integrator 122, the s-polarized light is reflected by the first reflective polarizing plate 121, and then again inside the rod integrator 122, the second reflective polarizing plate. Propagate in the direction of 125.

  Of the light traveling in the direction from the first reflective polarizing plate 121 to the second reflective polarizing plate 125, p-polarized light is transmitted through the second reflective polarizing plate 125. Of the light traveling from the first reflective polarizing plate 121 toward the second reflective polarizing plate 125, the s-polarized light repeats the above-described circulation. As described above, the illumination device 100 can sequentially emit the p-polarized light that is the polarized light in the first vibration direction by reusing the s-polarized light that is the polarized light in the second vibration direction. .

  The illumination device 100 makes the intensity distribution of the incident light beam substantially uniform by the rod integrator 122 provided in the uniformizing optical element 103. The rod integrator 122 can sufficiently uniform the light as the frequency of reflection increases, while the degree of change in the polarization state of the light increases. By providing the second reflective polarizing plate 125 in the homogenizing optical element 103, even if the p-polarized light changes to elliptically polarized light while propagating through the rod integrator 122, Only p-polarized light can be supplied.

  By using the uniformizing optical element 103, the illumination device 100 can make the light sufficiently uniform and emit only polarized light in a specific vibration direction. Further, the s-polarized light reflected by the second reflective polarizing plate 125 is reused by using the first reflective polarizing plate 121 provided in the homogenizing optical element 103, so that a specific vibration direction is obtained. Can be efficiently emitted. This produces an effect that polarized light in a specific vibration direction can be supplied with high efficiency at a high illuminance ratio.

  FIG. 4 shows a top surface configuration of the illumination device 400 according to the first modification of the present embodiment. The illumination device 400 according to the present modification includes a uniformizing optical element 403 including two rod integrators 422 and 423. One of the two rod integrators 422 is provided at a position where light transmitted through the polarization separation film 111 travels. The other rod integrator 423 is provided at a position where light transmitted through the λ / 2 phase plate 113 travels. The two rod integrators 422 and 423 are provided in parallel in the X-axis direction, which is a direction substantially orthogonal to the optical axis AX. In order to make the light from the LED 101 incident on the irradiated surface I efficiently, the shape of the region where the emission side end surfaces of the two rod integrators 422 and 423 are combined is substantially the same as or substantially similar to the irradiated surface I. It can be a shape.

  The rod integrator 422 propagates the light transmitted through the polarization separation film 111, the transparent member layer 114, and the first reflective polarizing plate 121. The rod integrator 423 propagates the light reflected by the polarization separation film 111 and the reflection film 112 and transmitted through the λ / 2 phase plate 113 and the first reflection type polarizing plate 121. Between the rod integrator 422 and the rod integrator 423, an adhesive member having a refractive index smaller than that of the transparent member constituting the rod integrator 422, 423 is filled. In addition, an air layer may be provided between the rod integrator 422 and the rod integrator 423. With this configuration, light incident on the rod integrator 422 can be totally reflected in the rod integrator 422, and light incident on the rod integrator 423 can be totally reflected in the rod integrator 423. The homogenizing optical element 403 increases the frequency of light reflection and sufficiently equalizes the intensity distribution of the light beam as compared with the above-described homogenizing optical element 103 (see FIG. 1) using a single rod integrator 122. It becomes possible. Thereby, the intensity distribution of the incident light beam can be made more uniform.

  Note that the number of rod integrators that are arranged in parallel in a direction substantially orthogonal to the optical axis AX is not limited to two as long as it is plural. In addition to the X-axis direction, the rod integrator may be arranged in parallel in the Y-axis direction, which is a direction substantially orthogonal to the optical axis AX. Furthermore, the rod integrator may be arranged in an array in two directions, the X-axis direction and the Y-axis direction. Furthermore, the rod integrator arranged in parallel in a direction substantially orthogonal to the optical axis AX is provided at a position where the light transmitted through the polarization separation film 111 travels and a position where the light transmitted through the λ / 2 phase plate 113 travels. It is not limited to the configuration. A plurality of rod integrators arranged regardless of the configuration of the polarization conversion element 102 may be used.

  FIG. 5 shows an upper surface configuration of a lighting apparatus 500 according to the second modification of the present embodiment. The illumination device 500 of the present modification includes a rod integrator 524 that makes the intensity distribution of the light beams from the plurality of rod integrators 422 and 423 provided in parallel in a direction substantially orthogonal to the optical axis AX substantially uniform. It is characterized by having an opticalizing element 503. Between the rod integrator 422 and the rod integrator 423, a layer of an adhesive member having a low refractive index and an air layer are formed as in the first modification. Between the rod integrator 422 and the rod integrator 524, and between the rod integrator 423 and the rod integrator 524, an adhesive member having substantially the same refractive index as the transparent members constituting the rod integrators 422 and 423 and the rod integrator 524 is provided. Filled. Thereby, reflection loss caused by air entering between the rod integrators 422 and 423 and the rod integrator 524 can be reduced, and light from the rod integrators 422 and 423 can be efficiently incident on the rod integrator 524. By using the rod integrator 524, the uniformizing optical element 503 can uniformize light from the plurality of rod integrators 422 and 423 as a whole. Thereby, the intensity distribution of the incident light beam can be made more uniform.

  FIG. 6 shows an upper surface configuration of the illumination device 600 according to the third modification of the present embodiment. The illumination device 600 of this modification includes a polarization conversion element array 602 configured by arranging polarization conversion elements 102 that are polarization conversion units in an array. As shown in the top surface configuration of FIG. 6 and the side surface configuration of FIG. 7, the polarization conversion element array 602 has two polarization conversion elements 102 arranged in an array in the X-axis direction and in the Y-axis direction. The polarization conversion element array 602 has a shape in which the surface on the LED 101 side is substantially the same as or substantially similar to the irradiated surface I by arranging the four polarization conversion elements 102 in an array.

  The homogenizing optical element 603 is provided with two rod integrators 422 and 423 for one polarization conversion element 102. The homogenizing optical element 603 has four rod integrators arranged in an array in the X-axis direction and two in the Y-axis direction corresponding to the configuration of the polarization conversion element array 602. Between the rod integrators, a layer of an adhesive member having a low refractive index and an air layer are formed as in the first modification. Thereby, it is set as the structure using several LED101, and bright illumination light can be obtained easily.

  Similar to the description of Modification 1, the plurality of rod integrators may be arranged regardless of the configuration of the polarization conversion element array 602. The illumination device 600 may be configured to combine the polarization conversion element array 602 and a single rod integrator. Further, similarly to the description of the second modification, a rod integrator that makes light beams from a plurality of rod integrators substantially uniform may be used.

  The illumination device 600 is not limited to the configuration in which one LED 101 is used for one polarization conversion element 102, and may be configured to use a plurality of LEDs 101 for one polarization conversion element 102. Thereby, it becomes possible to supply bright light by using more LEDs 101. Not only in this modification but also in each of the illumination devices described above, a plurality of LEDs 101 may be used for one polarization conversion element 102.

  In addition, the rod integrator which is a uniformization part is not restricted to what has a rectangular parallelepiped transparent member. For example, as shown in the perspective configuration of FIG. 8, a rod integrator 822 having a hollow structure may be used. On the inner surface of the rod integrator 822, a reflective surface 823 made of a highly reflective member, for example, a metal member such as aluminum is provided. The light incident on the rod integrator 822 travels inside the rod integrator 822 while being repeatedly reflected on the reflecting surface 823. When the rod integrator 822 having a hollow structure is used, it is desirable to provide an antireflection film instead of the transparent member layer 114 (see FIG. 1). Thereby, the light from the polarization conversion element 102 can be efficiently incident on the rod integrator 822. Furthermore, a rod integrator that combines a transparent member and a reflective surface may be used as the uniformizing portion.

  Further, as the uniformizing portion, a rod integrator 922 having a tapered shape may be used as shown in the perspective configuration of FIG. The rod integrator 922 is made of a transparent member, like the rod integrator of this embodiment. The rod integrator 922 has a tapered shape such that the exit side end surface S2 is larger than the entrance side end surface S1 and gradually increases toward the exit side. When the rod integrator 922 having such a shape is used, the light beam angle can be converted so that the angle with respect to the optical axis becomes small when the light is totally reflected at the interface between the transparent member and the air.

  For example, projectors are limited in the angle range of light that can be modulated by each spatial light modulator and the angle range of light that can be captured by the projection optical system. It can be said that light can be used. Therefore, when the illumination device is used in a projector, it is possible to obtain a bright image with high light utilization efficiency by increasing light with a smaller light beam angle to the rod integrator 922. Further, when the tapered rod integrator 922 is used, for example, the incident-side end surface S1 may have an arbitrary shape matching the polarization conversion element 102, and the emission-side end surface S2 may have a shape substantially similar to the irradiated surface I. Is possible. Thereby, even if it is a case where the polarization conversion element 102 of arbitrary shapes is used, the light from LED101 can be efficiently entered into the to-be-irradiated surface I. FIG.

  FIG. 10 shows a top surface configuration of the illumination apparatus 1000 according to the second embodiment of the present invention. The illuminating device 1000 includes a reflecting portion 1015 in place of the first reflective polarizing plate 121 (see FIG. 1) provided in the illuminating device 100 of the first embodiment. The same parts as those in the lighting apparatus 100 of the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The polarization conversion element 1002 converts the light from the LED 101 into p-polarized light that is polarized light in the first vibration direction by the polarization separation film 111, the reflection film 112, and the λ / 2 phase plate 113.

  The polarization conversion element 1002 further includes a reflection unit 1015. The reflection unit 1015 reflects the light traveling from the reflective polarizing plate 125 in the direction of the polarization conversion element 1002 to travel in the direction of the rod integrator 122. The reflecting portion 1015 can be made of a highly reflective member, for example, a metal member such as aluminum. As shown in the upper surface configuration of FIG. 10 and the side surface configuration of FIG. 11, the reflection unit 1015 is provided on all surfaces of the polarization conversion element 1002 other than the incident surface and the exit surface. On the exit side of the polarization conversion element 1002, a rod integrator 122 that is a uniformizing unit is provided. The reflective polarizing plate 121 is provided on the end surface of the rod integrator 122 that is a uniformizing portion, on the side opposite to the side on which the polarization conversion element 1002 is provided.

  As shown in FIG. 10, the polarization conversion element 1002 converts light from the LED 101 into p-polarized light that is polarized light in the first vibration direction. The light that has entered the rod integrator 122 from the polarization conversion element 1002 propagates through the rod integrator 122 and then enters the reflective polarizing plate 125. Of the light incident on the reflective polarizing plate 125, p-polarized light passes through the reflective polarizing plate 125 and is then supplied to the irradiated surface I.

  Of the light incident on the reflective polarizing plate 125, the s-polarized light is reflected by the reflective polarizing plate 125. The s-polarized light reflected by the reflective polarizing plate 125 propagates through the rod integrator 122 in the negative Z direction, which is the opposite direction, and enters the polarization conversion element 1002. The light L that has entered the polarization conversion element 1002 from the rod integrator 122 travels in the direction of the reflection unit 1015 after being reflected by the polarization separation film 111, for example.

  The light traveling in the direction of the rod integrator 122 after repeating the reflection at the reflecting portion 1015, the polarization separating film 111, and the reflecting film 112 in the polarization conversion element 1002 again passes through the inside of the rod integrator 122 as the second reflective polarizing plate. Propagate in the direction of 125. In order to reduce the loss of light incident on the polarization conversion element 1002 from the rod integrator 122 as much as possible, it is desirable to provide the reflecting portions 1015 on all surfaces of the polarization conversion element 1002 other than the entrance surface and the exit surface.

  Of the light traveling from the polarization conversion element 1002 toward the reflective polarizing plate 125, p-polarized light is transmitted through the reflective polarizing plate 125. Of the light traveling from the polarization conversion element 1002 toward the reflective polarizing plate 125, the s-polarized light repeats the above-described circulation. As described above, the illumination device 1000 can sequentially emit p-polarized light that is polarized light in the first vibration direction by reusing the s-polarized light that is polarized light in the second vibration direction. . Note that light traveling in the direction of the LED 101 from the reflective polarizing plate 125 may travel in the direction of the polarization conversion element 1002 by reflection at the reflective electrode of the LED 101. With this configuration, the light traveling in the direction of the LED 101 can be reused.

  The illumination device 1000 makes the intensity distribution of the incident light beam substantially uniform by the rod integrator 122. The rod integrator 122 can sufficiently uniform the light as the frequency of reflection increases, while the degree of change in the polarization state of the light increases. By providing the reflective polarizing plate 125, only the p-polarized light can be supplied to the irradiated surface I even when the p-polarized light changes to elliptically polarized light while propagating through the rod integrator 122. it can.

  The illumination device 1000 can sufficiently emit light and emit only polarized light in a specific vibration direction by using the rod integrator 122 and the reflective polarizing plate 125. Furthermore, the s-polarized light reflected by the reflective polarizing plate 125 can be reused by using the reflection unit 1015, whereby polarized light having a specific vibration direction can be efficiently emitted. This produces an effect that polarized light in a specific vibration direction can be supplied with high efficiency at a high illuminance ratio.

  As the polarization conversion unit, as shown in FIG. 12, a polarization conversion element 1202 provided with an aperture reflection mirror 1215 on the incident surface may be used. The aperture reflecting mirror 1215 is a reflecting mirror in which a circular opening 1216 is provided at the center as shown in the plan configuration of FIG. The aperture reflection mirror 1215 is provided toward the inside of the polarization conversion element 1202. For example, when an image of the LED 101 is formed on the incident surface of the polarization conversion element 1202, the opening 1216 is formed according to the shape of the image of the LED 101. An antireflection film for preventing reflection of light from the LED 101 is provided in the opening 1216 portion of the incident surface of the polarization conversion element 1202.

  Light from the LED 101 enters the polarization conversion element 1202 through the opening 1216. Further, the aperture reflection mirror 1215 reflects the light reflected by the reflective polarizing plate 125 and proceeds toward the LED 101, thereby traveling toward the rod integrator 122. By providing the aperture reflection mirror 1215, loss of light traveling from the reflective polarizing plate 125 in the direction of the polarization conversion element 1202 can be reduced, and the light reflected by the reflective polarizing plate 125 can be reused more efficiently. it can.

  FIG. 14 shows an upper surface configuration of a lighting apparatus 1400 according to the first modification of the present embodiment. The illumination device 1400 of this modification includes two rod integrators 422 and 423, similar to the illumination device 400 (see FIG. 4). Between the rod integrator 422 and the rod integrator 423, a layer of an adhesive member having a low refractive index and an air layer are formed in the same manner as the lighting device 400 described above. The illuminating device 1400 can increase the frequency at which light is reflected and sufficiently uniform the intensity distribution of the light beam, compared to the illuminating device 1000 (see FIG. 10) using the single rod integrator 122. Become. Thereby, similarly to said illuminating device 400, the intensity distribution of the incident light beam can be made more uniform. Also in this embodiment, a plurality of rod integrators arranged regardless of the configuration of the polarization conversion element 1002 may be used.

  FIG. 15 shows an upper surface configuration of a lighting apparatus 1500 according to the second modification of the present embodiment. The illumination device 1500 of the present modification includes a rod integrator 524 that substantially uniforms the intensity distribution of the light beams from the plurality of rod integrators 422 and 423, similar to the illumination device 500 (see FIG. 5). To do. Between the rod integrators 422 and 423 and the rod integrator 524, similarly to the lighting device 500 described above, an adhesive member having substantially the same refractive index as the transparent members constituting the rod integrators 422 and 423 and the rod integrator 524 is filled. Has been. Thereby, similarly to said illuminating device 500, the intensity distribution of the incident light beam can be made more uniform.

  FIG. 16 shows a top configuration of a lighting device 1600 according to the third modification of the present embodiment. The illumination device 1600 according to the present modification includes a polarization conversion element array 1612 configured by arranging polarization conversion elements as polarization conversion units in an array like the illumination device 600 (see FIG. 6). Features. Between the rod integrators, a layer of an adhesive member having a low refractive index and an air layer are formed in the same manner as the illumination device 600 described above. Thereby, it is set as the structure using several LED101, and bright illumination light can be obtained easily. The illumination device 1600 may use a configuration in which the polarization conversion element array 1612 and a single rod integrator are combined, or a rod integrator that makes light beams from a plurality of rod integrators substantially uniform. Each illumination device of this embodiment may use a plurality of LEDs 101 for one polarization conversion element 1002.

  FIG. 17 shows a schematic configuration of a projector 1700 that is an image display apparatus according to Embodiment 3 of the present invention. The projector 1700 is a so-called front type projector that projects light according to an image signal onto a screen and observes a projected image from the same side as the projector 1700 with respect to the screen. The projector 1700 includes an R light illumination device 100R that supplies red light (hereinafter referred to as “R light”), a G light illumination device 100G that supplies green light (hereinafter referred to as “G light”), and the like. And a B light illumination device 100B that supplies blue light (hereinafter referred to as “B light”). Each of the lighting devices 100R, 100G, and 100B has the same configuration as the lighting device 100 of the first embodiment. In the present embodiment, the description overlapping that of the first embodiment is omitted.

  The R light illumination device 100R includes an R light LED 101R. The R light LED 101R supplies R light. The R light illumination device 100R converts the R light from the R light LED 101R into polarized light having a specific vibration direction, for example, p-polarized light, and supplies the light to the liquid crystal type spatial light modulation device 170R to be illuminated. The liquid crystal spatial light modulator 170R is a transmissive liquid crystal display device that modulates R light according to an image signal. The p-polarized light incident on the liquid crystal spatial light modulator 170R is converted into s-polarized light by modulation. The R light converted into s-polarized light by the liquid crystal type spatial light modulator 170R enters the cross dichroic prism 172.

  The G light illumination device 100G includes a G light LED 101G. The G light LED 101G supplies G light. The G light illumination device 100G converts the G light from the G light LED 101G into polarized light having a specific vibration direction, for example, p-polarized light, and supplies the converted light to the liquid crystal type spatial light modulation device 170G that is an illumination target. The liquid crystal spatial light modulator 170G is a transmissive liquid crystal display device that modulates G light according to an image signal. The p-polarized light incident on the liquid crystal spatial light modulator 170G is converted into s-polarized light by modulation. The G light converted into s-polarized light by the liquid crystal type spatial light modulation device 170G enters the cross dichroic prism 172 from a surface different from the surface on which the R light is incident.

  The B light illumination device 100B includes a B light LED 101B. The LED 101B for B light supplies B light. The B light illumination device 100B converts the B light from the B light LED 101B into polarized light having a specific vibration direction, for example, p-polarized light, and supplies the converted light to the liquid crystal type spatial light modulation device 170B to be illuminated. The liquid crystal spatial light modulator 170B is a transmissive liquid crystal display device that modulates B light according to an image signal. The p-polarized light incident on the liquid crystal type spatial light modulator 170B is converted into s-polarized light by modulation. The B light converted into s-polarized light by the liquid crystal type spatial light modulator 170B enters the cross dichroic prism 172 from a surface different from the surface on which the R light is incident and the surface on which the G light is incident.

  The cross dichroic prism 172 which is a color synthesis optical system has two dichroic films 172a and 172b. The dichroic films 172a and 172b are arranged orthogonal to the X shape. The dichroic film 172a reflects R light and transmits G light. The dichroic film 172b reflects B light and transmits G light. In this manner, the cross dichroic prism 172 combines the R light, G light, and B light modulated by the liquid crystal type spatial light modulators 170R, 170G, and 170B, respectively. The projection optical system 174 projects the light combined by the cross dichroic prism 172 onto the screen 176.

  The dichroic films 172a and 172b are generally excellent in the reflection characteristics of s-polarized light. Therefore, it is desirable that the R light and B light to be reflected by the dichroic films 172a and 172b are incident on the cross dichroic prism 172 as s-polarized light. Further, it is desirable that the G light to be transmitted through the dichroic films 172a and 172b becomes p-polarized light and enters the cross dichroic prism 172. In order to make the G light converted into the s-polarized light enter the cross dichroic prism 172, for example, a λ / 2 phase plate may be provided between the liquid crystal spatial light modulator 170G and the cross dichroic prism 172.

  By using each color light illumination device 100R, 100G, 100B, polarized light in a specific vibration direction can be supplied with high efficiency at a high illuminance ratio. Thereby, a bright image with reduced brightness unevenness can be displayed. In the above embodiment, the LED is used as the light source unit, but the present invention is not limited to this. Instead of the LED, another solid light source such as an EL element or a semiconductor laser may be used. The light source unit is not limited to a solid light source, and a lamp such as an ultrahigh pressure mercury lamp may be used. The spatial light modulation device used for the projector 1700 is not limited to a transmissive liquid crystal display device, and a reflective liquid crystal display device may be used. Furthermore, the image display device provided with the illumination device is not limited to the projector, and may be a display that directly views light modulated by the spatial light modulation device, for example.

  As described above, the uniformizing optical element and the illumination device according to the present invention are useful when used in a projector that is an image display device, and are particularly suitable for a projector that modulates polarized light in a specific vibration direction.

The figure which shows the upper surface structure of the illuminating device which concerns on Example 1 of this invention. The figure which shows the side surface structure of an illuminating device. The figure which shows the isometric view structure of a uniform optical element. FIG. 6 is a diagram illustrating a top surface configuration of a lighting device according to a first modification of the first embodiment. The figure which shows the upper surface structure of the illuminating device which concerns on the modification 2 of Example 1. FIG. FIG. 6 is a diagram illustrating a top surface configuration of a lighting device according to a third modification of the first embodiment. The figure which shows the side surface structure of an illuminating device. The figure explaining the structure of the rod integrator which has a hollow structure. The figure explaining the structure of the rod integrator which has a taper shape. The figure which shows the upper surface structure of the illuminating device which concerns on Example 2 of this invention. The figure which shows the side surface structure of an illuminating device. The figure explaining the structure of the polarization conversion element provided with the aperture reflection mirror. The figure which shows the structure of the entrance plane of the polarization conversion element provided with the aperture reflection mirror. The figure which shows the upper surface structure of the illuminating device which concerns on the modification 1 of Example 2. FIG. The figure which shows the upper surface structure of the illuminating device which concerns on the modification 2 of Example 2. FIG. FIG. 6 is a diagram illustrating a top surface configuration of a lighting device according to a third modification of the second embodiment. FIG. 6 is a diagram illustrating a schematic configuration of a projector according to a third embodiment of the invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Illumination device, 101 LED, 102 Polarization conversion element, 103 Uniformization optical element, 111 Polarization separation film, 112 Reflection film, 113 λ / 2 phase plate, 114 Transparent member layer, 121 Reflective polarizing plate, 122 Rod integrator, 125 Reflective polarizing plate, AX optical axis, I irradiated surface, LN condenser lens, 400 illumination device, 403 homogenizing optical element, 422, 423 rod integrator, 500 illumination device, 503 homogenizing optical element, 524 rod integrator, 600 Illumination device, 602 polarization conversion element array, 603 homogenization optical element, 822 rod integrator, 823 reflection surface, 922 rod integrator, S1 incident type end surface, S2 emission side end surface, 1000 illumination device, 1002 polarization conversion element, 1015 reflection unit, 1202 polarization change Element, 1215 Aperture reflection mirror, 1216 aperture, 1400 illumination device, 1500 illumination device, 1600 illumination device, 1612 polarization conversion element array, 1700 projector, 100R R light illumination device, 100G G light illumination device, 100B for B light Illumination device, LED for 101R R light, LED for 101G G light, LED for 101B B light, 170R, 170G, 170B Liquid crystal type spatial light modulator, 172 Cross dichroic prism, 172a, 172b Dichroic film, 174 Projection optical system, 176 screen

Claims (7)

A homogenizing portion that makes the intensity distribution of the light beam substantially uniform;
A first reflection type that is provided on one end face of the uniformizing section and transmits polarized light in the first vibration direction and reflects polarized light in the second vibration direction substantially orthogonal to the first vibration direction. A polarizing plate;
Provided on the other end face of the homogenizing unit different from the end face on which the first reflective polarizing plate is provided, transmits polarized light in the first vibration direction, and transmits in the second vibration direction. And a second reflective polarizing plate that reflects polarized light.   The homogenizing optical element according to claim 1, wherein the homogenizing unit includes a rod integrator.   The uniformizing optical element according to claim 2, comprising a plurality of the rod integrators provided in parallel in a direction substantially orthogonal to the optical axis.   The homogenization according to claim 3, further comprising a rod integrator that substantially uniformly distributes the intensity distribution of light beams from the plurality of rod integrators provided in parallel in a direction substantially orthogonal to the optical axis. Optical element. A light source unit for supplying light;
A polarization conversion unit that converts light from the light source unit into polarized light in a first vibration direction;
A homogenizing optical element that makes the intensity distribution of the light beam from the polarization converter substantially uniform,
The said uniformizing optical element is a uniforming optical element as described in any one of Claims 1-4, The illuminating device characterized by the above-mentioned. The illumination device according to claim 5, wherein the polarization conversion units are arranged in an array. A lighting device according to claim 5 ;
An image display device comprising: a spatial light modulation device that modulates light from the illumination device according to an image signal.

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