JP2006154601A - Light source device and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device and the like which can reduce the spread of light flux and supply light with high efficiency. <P>SOLUTION: The light source device has at least two light-emitting sections 101, 102 for supplying light, and a polarization splitter 107 for dividing the lights from the light-emitting sections 101, 102 into a polarized light, oscillating in a 1st direction and a polarized light oscillating in a 2nd direction, by passing the polarized light oscillating in the 1st direction out of the light from the light-emitting sections 101, 102 and reflecting the polarized light oscillating in the 2nd direction that substantially cross the 1st oscillating direction. The light-emitting section 101 has a reflector 103 to reflect the light traveling from the polarizing divider 107 to the light-emitting section 101 into the direction of the polarization splitter 107. The polarization splitter 107 combines the polarized light, oscillating in the 1st direction supplied from the light-emitting section 101 and directly entering the polarization splitter 107 and the polarized light, oscillating in the 1st direction reflected at reflector 103 and entering the polarization aplitter 107 to make them travel in the predetermined direction L. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light source device and an image display device, and more particularly to a technology of a light source device used in combination with a spatial light modulation device.

  In recent years, it has been proposed to use a solid light-emitting element for a light source device of a projector. A light-emitting diode (hereinafter referred to as “LED”), which is a solid-state light-emitting element, is characterized by being ultra-compact, ultra-light, and long-life. Moreover, remarkable progress has been made in the development and improvement of high-power LEDs, and the use of LEDs for lighting applications is expanding. For this reason, it is expected to use an LED as a light source of a projector, particularly a small and bright projector.

  A liquid crystal type spatial light modulation device used in a projector performs modulation by converting the polarization state of incident light. When a liquid crystal spatial light modulator is used, the light from the light source can be used efficiently by converting the light from the light source into polarized light having a specific vibration direction and supplying it. For example, Patent Document 1 and Patent Document 2 propose a technique for converting light into polarized light having a specific vibration direction and supplying the light.

JP 2000-212499 A JP 2003-57445 A

  When the currently developed LED is used for a projector, it is necessary to use a plurality of LEDs in order to obtain a bright image. When a plurality of LEDs are used, the LEDs are arranged in an array according to the techniques of Patent Document 1 and Patent Document 2. When a plurality of LEDs are arranged in an array, the area in which the LEDs are arranged increases as the number of LEDs increases. Further, in a projector, in an optical system including a light source device and a spatial light modulation device, a spatial spread in which a light beam that can be effectively handled exists can be expressed as a product of an area and a solid angle (etendue, Geometric Extent). The product of the area and the solid angle is stored in the optical system. From this, when a plurality of LEDs are arranged in an array, it is considered that the spatial spread of the light beam incident on the spatial light modulator increases as the number of LEDs increases.

  On the other hand, there is a limit to the angle of light that can be effectively modulated by the spatial light modulator. For this reason, it becomes difficult to use light from the light source device effectively as the spatial spread of the light beam incident on the spatial light modulator increases. For this reason, even if it uses the technique currently disclosed by patent document 1 and patent document 2, light may not be utilized efficiently. In particular, if the light from the light emitting unit cannot be used efficiently, a bright image may not be obtained even if a plurality of light emitting units are used, which is a problem. The present invention has been made in view of the above-described problems, and is capable of reducing the spread of a light beam and capable of supplying light with high efficiency, and a bright image can be displayed using the light source device. An object is to provide an image display device.

  In order to solve the above-described problems and achieve the object, according to the present invention, at least two light emitting units that supply light, and the polarized light in the first vibration direction among the light from the light emitting unit are transmitted, By reflecting the polarized light in the second vibration direction substantially orthogonal to the first vibration direction, the light from the light emitting unit is separated into the polarized light in the first vibration direction and the polarized light in the second vibration direction. The light-emitting unit includes a reflection unit that reflects light traveling in the direction of the light-emitting unit from the light-polarizing unit to the direction of the light-polarizing unit, and the light-polarizing unit is supplied from the light-emitting unit. Combining the polarized light in the first vibration direction directly incident on the polarization separation unit and the polarized light in the first vibration direction incident on the polarization separation unit after being reflected by the reflection unit and proceeding in a predetermined direction. A light source device can be provided.

  The polarized light in the first vibration direction that has entered the polarization separation unit from the light emitting unit passes through the polarization separation unit. The polarized light in the second vibration direction that has entered the polarization separation unit from the light emitting unit is reflected by the polarization separation unit. The polarized light in the second vibration direction reflected by the polarization separation unit travels again toward the polarization separation unit by being reflected by the reflection unit. At this time, the polarized light in the second vibration direction is converted into polarized light in the first vibration direction using, for example, a phase plate. In this way, polarized light in the second vibration direction from the light emitting unit can be converted into polarized light in the first vibration direction and supplied. The light source device converts the polarized light in the second vibration direction from the light emitting unit into polarized light in the first vibration direction by transmission and reflection in the polarization separation film and polarization conversion, and travels in a predetermined direction. be able to. For this reason, the light source device can efficiently supply light from the light emitting unit. The polarized light in the first vibration direction directly incident on the polarization separation unit from the light emitting unit and the polarized light in the first vibration direction incident on the polarization separation unit after being reflected by the reflection unit are combined in the polarization separation unit, Proceed in the direction of a predetermined illumination target. The light source device can reduce the spread of the light beam emitted from the light source device by combining the light from each light emitting unit with the polarization separating unit, even when using a plurality of light emitting units. Accordingly, it is possible to obtain a light source device that can reduce the spread of the light flux and can supply light with high efficiency.

  Moreover, according to a preferable aspect of the present invention, it is desirable to have a phase plate provided at least at one place between the light emitting unit and the polarization separation unit and on the emission side of the polarization separation unit. For example, when a λ / 4 phase plate is used as the phase plate, linearly polarized light incident on the phase plate is converted into circularly polarized light. The light converted into circularly polarized light by the phase plate is reflected by, for example, the reflection portion and then incident on the phase plate again, whereby the vibration direction is converted. By passing the light twice through the λ / 4 phase plate, the vibration direction of the light can be rotated by 90 degrees. By passing the λ / 4 phase plate twice, polarized light in the first vibration direction and polarized light in the second vibration direction can be converted into each other. Thereby, it is possible to reuse light in a vibration direction other than the specific vibration direction, and light from the light emitting unit can be efficiently advanced in a predetermined direction.

  According to a preferred aspect of the present invention, it is desirable to have an optical element that is provided between the light emitting unit and the polarization separating unit and guides light from the light emitting unit to the polarization separating unit. Thereby, the light from a light emission part can be efficiently guide | induced to a polarization separation part.

  Moreover, as a preferable aspect of the present invention, it is desirable that the optical element is a rod integrator that makes light from the light emitting portion substantially uniform. By using the rod integrator, it is possible to efficiently guide the light from the light emitting unit to the polarization separating unit and to make the light uniform. Thereby, the light from the light emitting part can be efficiently and uniformized and guided to the polarization separating part.

  As a preferred embodiment of the present invention, it is desirable that the optical element is a collimator lens that makes light from the light emitting portion substantially parallel. By using the collimator lens, the light from the light emitting unit can be efficiently guided to the polarization separation unit. Further, by using the collimator lens, the light traveling in the direction from the polarization separating unit to the light emitting unit travels in substantially the same optical path as traveling in the direction from the light emitting unit to the polarization separating unit. The light traveling in the direction from the polarized light separating unit to the light emitting unit efficiently enters the light emitting unit by traveling in substantially the same optical path as traveling from the light emitting unit to the polarized light separating unit. Since the light incident on the light emitting unit is reflected by the reflecting unit and travels again toward the polarization separating unit, the light can be efficiently reused by using a collimator lens. Thereby, the light from a light emission part can be utilized efficiently.

  Moreover, as a preferable aspect of the present invention, it is desirable that the optical element is a condensing lens that condenses light from the light emitting section. By using the condensing lens, light from the light emitting unit can be efficiently guided to the polarization separation unit. In addition, when the light from the light emitting unit is converged using the condensing lens, it is not necessary to illuminate the polarization separation unit telecentrically. For this reason, the freedom degree of a structure of a light source device can be made high. Thereby, the light from a light emission part can be efficiently guide | induced to a polarization separation part by the structure of a high freedom degree.

  Moreover, as a preferable aspect of the present invention, it is desirable to have a mirror that reflects light traveling in a direction different from the predetermined direction from the polarization separation unit in the direction of the polarization separation unit. By using the mirror, the light traveling in a direction different from the predetermined illumination direction can be returned to the direction of the polarization separation unit. As a result, it is possible to reuse the light that has traveled in a different direction from the illumination direction, and to efficiently use the light from the light emitting unit.

  Moreover, as a preferable aspect of the present invention, the first light emitting unit includes at least a first light emitting unit and a second light emitting unit, and the first light emitting unit is a first vibration direction incident on the polarization separating unit from the first light emitting unit. First polarized light after the polarized light of the second oscillation direction that has passed through the polarized light separating portion and travels in a predetermined direction and is incident on the polarized light separating portion from the second light emitting portion is reflected by the polarized light separating portion. The second light emitting unit is provided with a second light after the polarized light having the second oscillation direction incident on the polarization separating unit from the first light emitting unit is reflected by the polarization separating unit. It is desirable to be provided at a position that advances in the direction of the light emitting portion.

  Of the light from the first light emitting unit, the polarized light in the first vibration direction travels in a predetermined illumination direction after passing through the polarization separating unit. Of the light from the first light emitting unit, the polarized light in the second vibration direction travels in the direction of the second light emitting unit after being reflected by the polarization separating unit. Of the light from the second light emitting unit, the polarized light in the first vibration direction passes through the polarization separation unit and then returns to the polarization separation unit by being reflected by, for example, a mirror. The polarized light in the first vibration direction that has returned to the polarization separation unit passes through the polarization separation unit and travels toward the second light emitting unit.

  Of the light from the second light emitting unit, the polarized light in the second vibration direction travels in the direction of the first light emitting unit after being reflected by the polarization separating unit. Thus, the light traveling from the polarization separation unit toward the first and second light emitting units is reflected by the reflection unit and then travels again toward the polarization separation unit. The polarized light in the first vibration direction that has traveled in the direction of the polarization separator passes through the polarization separator. The polarized light in the second vibration direction is converted into polarized light in the first vibration direction by passing through the phase plate, for example, and then transmitted through the polarization separation unit. In this manner, the polarized light in the first vibration direction is advanced in the illumination direction by transmission and reflection in the polarization separation unit and polarization conversion. Thereby, the polarized light in the first vibration direction can be synthesized and traveled in a predetermined direction.

  Moreover, as a preferable aspect of the present invention, the light emitting device further includes a third light emitting unit, and the third light emitting unit separates polarized light in the first vibration direction incident on the polarization separating unit from the third light emitting unit. It is desirable to be provided at a position where the light travels in the direction of the second light emitting part after passing through the part. The polarized light in the first vibration direction from the third light emitting unit travels in the direction of the second light emitting unit after passing through the polarization separating unit. The light traveling in the direction of the second light emitting unit is reflected by the reflecting unit and travels in the direction of the polarization separating unit. The polarized light in the second vibration direction from the third light emitting unit can be converted into polarized light in the first vibration direction using, for example, a reflective polarizing plate or a λ / 4 phase plate. The light from the third light emitting unit is converted into polarized light in the first vibration direction by repeating transmission and reflection in the polarization separation unit and vibration direction conversion, and proceeds in a predetermined illumination direction. Thereby, the light from the third light emitting unit can be advanced in a predetermined direction, and brighter illumination light can be supplied.

  Further, as a preferable aspect of the present invention, the polarized light of the first vibration direction is transmitted between the third light emitting unit and the polarization separation unit and at least one of the emission side of the polarization separation unit, It is desirable to have a reflective polarizing plate that reflects polarized light in the second vibration direction. By using a reflective polarizing plate, only polarized light in the first vibration direction can be extracted. The polarized light in the second vibration direction reflected by the reflective polarizing plate can be reused by converting it into polarized light in the first vibration direction using, for example, a phase plate. Thereby, the polarized light in the first vibration direction can be supplied with high efficiency.

  Furthermore, according to the present invention, it is possible to provide an image display device having the above light source device and a spatial light modulation device that modulates light from the light source device in accordance with an image signal. By providing the light source device described above, it is possible to supply light with high efficiency to the spatial light modulation device that is the illumination target. Thereby, an image display device capable of displaying a bright image with high light utilization efficiency can be obtained.

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

  FIG. 1 shows a schematic configuration of a light source device 100 according to Embodiment 1 of the present invention. The light source device 100 includes an LED 101 that is a first light emitting unit and an LED 102 that is a second light emitting unit. The LEDs 101 and 102 are surface-emitting light sources that mainly emit light from the surface of the chip. The LEDs 101 and 102 supply light in the direction of the polarization beam splitter 108. The polarization beam splitter 108 is a rectangular parallelepiped structure formed by bonding two prisms. A polarizing film 107 is formed between the two prisms of the polarizing beam splitter 108.

  The polarizing film 107 transmits the polarized light in the first vibration direction out of the light from the LEDs 101 and 102, and reflects the polarized light in the second vibration direction, thereby allowing the light from the LEDs 101 and 102 to pass through the first vibration. A polarization separation unit that separates the polarized light in the direction into the polarized light in the second vibration direction. The polarized light in the first vibration direction is, for example, p-polarized light. The polarized light in the second vibration direction is polarized light in the vibration direction substantially orthogonal to the first vibration direction, and is, for example, s-polarized light.

  Between the LED 101 and the polarizing beam splitter 108 and between the LED 102 and the polarizing beam splitter 108, λ / 4 phase plates 105 and 106, which are phase plates, are provided, respectively. The LED 101 and the λ / 4 phase plate 105 are disposed corresponding to the surface of the polarizing beam splitter 108 opposite to the exit surface. The LED 102 and the λ / 4 phase plate 106 are disposed so as to correspond to the surface adjacent to the exit surface of the polarization beam splitter 108.

  A mirror 109 is provided on the side of the polarizing beam splitter 108 opposite to the side on which the LED 102 is provided. The mirror 109 reflects the light transmitted through the polarizing film 107 and traveling in a direction different from the predetermined illumination direction L from the polarizing film 107 in the direction of the polarizing beam splitter 108. Moreover, LED101,102 has the reflection parts 103 and 104, respectively. The reflection parts 103 and 104 are metal electrodes formed of a highly reflective metal member. The reflection unit 103 reflects light traveling from the polarizing film 107 toward the LED 101 toward the polarizing film 107. The reflection unit 104 reflects light traveling from the polarizing film 107 toward the LED 102 toward the polarizing film 107.

  The LED 101 is disposed around the optical axis AX along the illumination direction L. The LED 102 and the mirror 109 are disposed around an axis BX that is substantially perpendicular to the optical axis AX. The polarizing beam splitter 108 is disposed so that the polarizing film 107 is inclined by approximately 45 degrees with respect to both the optical axis AX and the axis BX. Further, the polarization beam splitter 108 is provided so that the optical axis AX and the axis BX intersect at the approximate center of the polarizing film 107.

  The LED 101 and the LED 102 supply light including p-polarized light and s-polarized light. The light from the LED 101 passes through the λ / 4 phase plate 105 and then enters the polarization beam splitter 108. Of the light that has passed through the λ / 4 phase plate 105 and entered the polarization beam splitter 108, p-polarized light passes through the polarizing film 107 and then travels in a predetermined illumination direction L indicated by an arrow. On the other hand, the s-polarized light out of the light transmitted through the λ / 4 phase plate 105 and incident on the polarization beam splitter 108 is reflected by the polarizing film 107 and then travels toward the LED 102.

  The s-polarized light traveling in the direction of the LED 102 passes through the λ / 4 phase plate 106 and then enters the LED 102. At this time, the s-polarized light is converted into circularly polarized light by passing through the λ / 4 phase plate 106. The circularly polarized light that has entered the LED 102 is reflected by the reflector 104 and then enters the λ / 4 phase plate 106 again. The λ / 4 phase plate 106 converts circularly polarized light into p-polarized light and makes it incident on the polarization beam splitter 108. Thus, by allowing light to pass through the λ / 4 phase plate 106 twice, the vibration direction of the light can be rotated by 90 degrees.

  The p-polarized light that has entered the polarization beam splitter 108 passes through the polarizing film 107 and enters the mirror 109. The p-polarized light incident on the mirror 109 is reflected by the mirror 109, enters the polarization beam splitter 108, and passes through the polarizing film 107. The p-polarized light that has passed through the polarizing film 107 travels again toward the LED 102. The p-polarized light traveling in the direction of the LED 102 is converted into s-polarized light by passing through the λ / 4 phase plate 106 twice before being reflected by the reflection unit 104 and entering the polarization beam splitter 108.

  The s-polarized light incident on the polarization beam splitter 108 is reflected by the polarizing film 107 and then travels toward the LED 101. The s-polarized light traveling in the direction of the LED 101 is converted into p-polarized light by passing through the λ / 4 phase plate 106 twice before being reflected by the reflecting portion 103 and entering the polarization beam splitter 108. The p-polarized light incident on the polarizing beam splitter 108 travels in the illumination direction L after passing through the polarizing film 107. The s-polarized light from the LED 101 passes from the light source device 100 through three reflections by the reflection units 103 and 104, two reflections by the polarizing film 107, one reflection by the mirror 109, and three transmissions by the polarizing film 107. Exit.

  The light from the LED 102 passes through the λ / 4 phase plate 106 and then enters the polarization beam splitter 108. Of the light that has passed through the λ / 4 phase plate 106 and entered the polarization beam splitter 108, p-polarized light passes through the polarizing film 107 and then enters the mirror 109. The p-polarized light incident on the mirror 109 behaves in the same manner as when the s-polarized light supplied from the LED 101 is converted to p-polarized light and then incident on the mirror 109. The p-polarized light from the LED 102 is reflected from the light source device 100 through two reflections at the reflection units 103 and 104, one reflection at the polarizing film 107, one reflection at the mirror 109, and three transmissions through the polarizing film 107. Exit.

  Of the light that has passed through the λ / 4 phase plate 106 and entered the polarization beam splitter 108, s-polarized light travels in the direction of the LED 101 after being reflected by the polarizing film 107. The s-polarized light traveling in the direction of the LED 101 behaves in the same manner as when the p-polarized light supplied from the LED 102 is converted into s-polarized light and then enters the LED 101. The s-polarized light from the LED 102 is emitted from the light source device 100 through one reflection at the reflection unit 103, one reflection at the polarizing film 107, and one transmission through the polarizing film 107. The polarizing film 107 synthesizes the p-polarized light supplied from the LED 101 and directly incident on the polarizing film 107 and the p-polarized light reflected by the reflecting unit 103 and then incident on the polarizing film 107 and travels in the illumination direction L.

  It is assumed that the reflectance at the reflecting portions 103 and 104, the reflectance at the polarizing film 107, and the reflectance at the mirror 109 are 60%, 90%, and 85%, respectively, and the transmittance of the polarizing film 107 is 90%. Assuming that the intensity of illumination light when the p-polarized light from one LED is taken out for illumination is 0.5, the total power of illumination light emitted from the light source device 100 of this embodiment is about 0.847. It is. The utilization efficiency of the emitted light from the LEDs 101 and 102 is approximately 42% per LED. When the light source device that takes out and illuminates p-polarized light from one LED is used as a reference, the light source device 100 of the present embodiment can supply illumination light having an intensity of about 1.69 times.

  The light source device 100 converts the polarized light in the second vibration direction from the LEDs 101 and 102 into the polarized light in the first vibration direction by transmission and reflection in the polarizing film 107 and polarization conversion, and the illumination direction L Can proceed to. For this reason, the light source device 100 can efficiently supply the light from the LEDs 101 and 102. The light source device 100 synthesizes the light from the LEDs 101 and 102 with the polarizing film 107, thereby causing the light from the LEDs 101 and 102 to travel to substantially the same illumination region. For this reason, even when two LEDs 101 and 102 are used, the spread of the light beam emitted from the light source device 100 can be reduced. As a result, it is possible to reduce the spread of the luminous flux and to supply light with high efficiency. For example, when the light source device 100 is used for a projector, since the spread of the light beam incident on the spatial light modulation device can be reduced, the illumination light from the light source device 100 can be efficiently modulated by the spatial light modulation device.

  The polarizing film 107 may transmit s-polarized light and reflect p-polarized light. In this case, the polarizing film 107 combines the s-polarized light supplied from the LED 101 and directly incident on the polarizing film 107 with the s-polarized light reflected by the reflecting unit 103 and then incident on the polarizing film 107, in the illumination direction L. Make it progress. The light source device 100 emits s-polarized light that has passed through the polarizing film 107 as illumination light. The polarization separation unit is not limited to the case where the polarizing film 107 is used, and a wire grid type polarizing plate may be used. When a wire grid type polarizing plate is used instead of the polarizing film 107, the light source device 100 can be made inexpensive. The wire grid type polarizing plate will be described later.

  FIG. 2 is a modification of the present embodiment, and shows a configuration of a light source device 200 using collimator lenses 211 and 212. In the present embodiment and the later-described embodiments, the same parts as those of the light source device 100 are denoted by the same reference numerals, and redundant description is omitted. The collimator lens 211 is provided in the optical path between the LED 101 serving as the first light emitting unit and the λ / 4 phase plate 105. The collimator lens 212 is provided in the optical path between the LED 102 serving as the second light emitting unit and the λ / 4 phase plate 106.

  The collimator lenses 211 and 212 are optical elements that guide the light from the LEDs 101 and 102 to the polarizing film 107, respectively. The collimator lenses 211 and 212 make the light from the LEDs 101 and 102 substantially parallel, respectively. The collimator lens 211 illuminates the polarizing film 107 in a telecentric manner so that the principal ray of light emitted from the collimator lens 211 is substantially parallel to the optical axis AX. The collimator lens 212 illuminates the polarizing film 107 in a telecentric manner so that the principal ray of light emitted from the collimator lens 212 is substantially parallel to the axis BX. The light from the LEDs 101 and 102 can be efficiently guided to the polarizing film 107 by the collimator lenses 211 and 212.

  Further, by providing the collimator lens 211, the light traveling in the direction from the polarizing film 107 to the LED 101 travels in substantially the same optical path as when traveling in the direction from the LED 101 to the polarizing film 107. The light traveling in the direction from the polarizing film 107 to the LED 101 enters the LED 101 efficiently by traveling through substantially the same optical path as traveling from the LED 101 to the polarizing film 107. The collimator lens 212 also makes the light traveling from the polarizing film 107 in the direction of the LED 102 efficiently enter the LED 102. Light incident on the LEDs 101 and 102 from the polarizing film 107 is reflected by the reflecting portions 103 and 104, respectively, and travels again toward the polarizing film 107. By using the collimator lenses 211 and 212, light can be reused efficiently, and light from the LEDs 101 and 102 can be used efficiently.

  FIG. 3 shows a configuration of a light source device 300 using condensing lenses 311 and 312 as optical elements. The condenser lens 311 is provided in the optical path between the LED 101 and the λ / 4 phase plate 105. The condenser lens 312 is provided in the optical path between the LED 102 and the λ / 4 phase plate 106. The condensing lenses 311 and 312 condense light from the LEDs 101 and 102, respectively. The light from the LEDs 101 and 102 can be efficiently guided to the polarizing film 107 by the condenser lenses 311 and 312.

  Further, when the light from the LEDs 101 and 102 is converged using the condenser lenses 311 and 312, it is not necessary to illuminate the polarizing film 107 telecentrically. For this reason, the freedom degree of the structure of the light source device 300 can be made high. By using the condensing lenses 311 and 312, the light from the LEDs 101 and 102 can be efficiently guided to the polarizing film 107 with a high degree of freedom.

  FIG. 4 shows a configuration of a light source device 400 that uses rod integrators 411 and 412 as optical elements. The rod integrator 411 is provided in the optical path between the LED 101 and the λ / 4 phase plate 105. The rod integrator 412 is provided in the optical path between the LED 102 and the λ / 4 phase plate 106. The rod integrators 411 and 412 are made of a transparent glass member having a rectangular parallelepiped shape. Light incident on the rod integrators 411 and 412 travels inside the rod integrators 411 and 412 while repeating total reflection at the interface between the glass member and air.

  The rod integrators 411 and 412 are not limited to those made of a glass member, but may have a hollow structure having an inner surface made of a reflective surface. In the case of a rod integrator having an inner surface as a reflecting surface, light incident on the rod integrator travels inside the rod integrator while being repeatedly reflected on the reflecting surface. Further, the rod integrator may be configured to combine a glass member and a reflecting surface.

  By using the rod integrators 411 and 412, the light from the LEDs 101 and 102 can be efficiently guided to the polarizing film 107. The rod integrators 411 and 412 make the light intensity distribution from the LEDs 101 and 102 substantially uniform, respectively. By using the rod integrators 411 and 412, the light from the LEDs 101 and 102 can be efficiently and uniformized and guided to the polarizing film 107. The light source device 400 is not limited to a configuration in which the LED, the λ / 4 phase plate, the rod integrator, and the polarization beam splitter are all joined together, and may be arranged at intervals.

  The optical element is not limited to the configuration provided between the LEDs 101 and 102 and the λ / 4 phase plates 105 and 106, but is provided between the λ / 4 phase plates 105 and 106 and the polarization beam splitter 108. Also good. Further, the light source device may be used in combination with the optical elements described with reference to FIGS. 2 to 4, or may be combined with other optical elements.

  FIG. 5 shows a configuration of a light source device 500 according to a modification of the present embodiment. In the light source device 500, a λ / 4 phase plate 505 is provided between the polarization beam splitter 108 and the mirror 109. Further, the light source device 500 is provided with a reflective polarizing plate 520 on the exit side of the polarizing beam splitter 108. The reflective polarizing plate 520 transmits p-polarized light that is polarized light in the first vibration direction, and reflects s-polarized light that is polarized light in the second vibration direction.

  As the reflection type polarizing plate 520, a wire grid type polarizing plate in which wires made of metal, for example, aluminum are provided in a lattice shape on a substrate made of an optically transparent glass member can be used. The wire grid type polarizing plate 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 the wire grid type polarizing plate so that the wire is substantially perpendicular to the vibration direction of the polarized light in the specific vibration direction, only the polarized light in the specific vibration direction can be transmitted.

  The p-polarized light traveling from the LED 101 to the polarizing beam splitter 108 passes through the polarizing film 107 and the reflective polarizing plate 520 and travels in the illumination direction L. The p-polarized light traveling from the LED 102 to the polarization beam splitter 108 passes through the polarizing film 107 and travels toward the mirror 109. The p-polarized light traveling in the direction of the mirror 109 is converted into s-polarized light by passing through the λ / 4 phase plate 505 twice before being reflected by the mirror 109 and entering the polarization beam splitter 108.

  The s-polarized light incident on the polarizing beam splitter 108 is reflected by the polarizing film 107 and then travels in the direction of the reflective polarizing plate 520. The s-polarized light incident on the reflective polarizing plate 520 is reflected by the reflective polarizing plate 520 and returns to the polarizing beam splitter 108. The s-polarized light that has returned to the polarization beam splitter 108 is reflected by the polarizing film 107 and travels toward the mirror 109. The s-polarized light traveling in the direction of the mirror 109 is converted into p-polarized light by passing through the λ / 4 phase plate 505 twice before being reflected by the mirror 109 and entering the polarization beam splitter 108. The p-polarized light incident on the polarization beam splitter 108 passes through the polarizing film 107 and travels in the direction of the LED 102. The p-polarized light traveling in the direction of the LED 102 behaves in the same manner as the p-polarized light from the LED 102.

  The p-polarized light from the LED 102 is reflected twice by the reflecting portions 103 and 104, three times reflected by the polarizing film 107, two times reflected by the mirror 109, once reflected by the reflective polarizing plate 520, and the polarizing film 107. The light is emitted from the light source device 500 after passing through the light three times and passing through the reflective polarizing plate 520 once. The s-polarized light from the LED 101 is reflected three times by the reflecting portions 103 and 104, four times reflected by the polarizing film 107, two times reflected by the mirror 109, once reflected by the reflective polarizing plate 520, and the polarizing film 107. The light is emitted from the light source device 500 after passing through the light three times and passing through the reflective polarizing plate 520 once.

  The positions of the LEDs 101 and 102 and the mirror 109 are not limited to the positions shown in the configuration of the light source device 500. A light source device 600 shown in FIG. 6 is obtained by replacing the LED 102 and the mirror 109 from the configuration of the light source device 500. A light source device 700 illustrated in FIG. 7 is obtained by replacing the LED 101 and the mirror 109 from the configuration of the light source device 500. Further, the configuration is not limited to the configuration in which the mirror 109 is provided, and the mirror 109 may be omitted as in the light source device 800 illustrated in FIG. A light source device 900 shown in FIG. 9 is a modification of the light source device 100, and uses a single LED 101. The light source device 900 includes a mirror 109 instead of the LED 102 and the λ / 4 phase plate 106.

  FIG. 10 shows the relationship between the configuration of the light source device and the intensity of illumination light. As shown in FIG. 11, the positions of the LED, mirror, λ / 4 phase plate, and reflective polarizing plate are the position on the exit side of the polarization beam splitter 108 and the position of the incidence of the polarization beam splitter 108 in the clockwise direction. It will be expressed as 1, 2, 3. Similar to the description of the light source device 100, the total power of the illumination light is expressed by assuming that the intensity of the illumination light when the p-polarized light from one LED is extracted and illuminated is 0.5. The brightness magnification represents the intensity of the illumination light of the light source device of the present embodiment as a magnification with reference to the case where p-polarized light from one LED is taken out and illuminated.

  The transmittance and reflectance of the reflective polarizing plate 520 are both 82%. In addition, the reflectance of the reflecting portions 103 and 104, the polarizing film 107, the mirror 109, and the transmittance of the polarizing film 107 are the same as those described for the light source device 100. Configuration A shows the light source device 100 of FIG. Configuration B is obtained by adding a reflective polarizing plate 520 to the configuration of the light source device 100. The configuration C is obtained by adding a λ / 4 phase plate to the configuration B, and shows the light source device 500 of FIG. The configuration D is obtained by replacing the LED and the mirror of the configuration B, and shows the light source device 600 of FIG. In the configuration E, a λ / 4 phase plate is added to the configuration D.

  Configuration F is a configuration in which LEDs are arranged at positions 1 and 3, and shows light source device 700 of FIG. The configuration G is obtained by removing the mirror from the configuration B, and shows the light source device 800 of FIG. In the configuration H, the arrangement of the LEDs and the λ / 4 phase plate is changed from the configuration G. Configuration I shows the light source device 900 of FIG. As shown in the table of FIG. 10, particularly bright illumination light can be obtained when LEDs are arranged at positions 1 and 2.

  FIG. 12 shows a schematic configuration of the light source device 120 according to the second embodiment of the present invention. The light source device 120 includes an LED 121 that is a third light emitting unit in addition to the LED 101 that is a first light emitting unit and the LED 102 that is a second light emitting unit. The LED 121 is provided on the opposite side of the polarizing beam splitter 108 from the side on which the LED 102 is provided. The LED 121 is arranged around the axis BX as in the LED 102. The LED 121 has a reflecting portion 122 that is a metal electrode. A reflective polarizing plate 520 is provided between the LED 121 and the polarizing beam splitter 108. A λ / 4 phase plate 505 is provided between the reflective polarizing plate 520 and the LED 121.

  The LED 121 supplies light including p-polarized light and s-polarized light. Of the light incident on the reflective polarizing plate 520 from the LED 121, the p-polarized light passes through the reflective polarizing plate 520 and the polarizing beam splitter 108 and then travels toward the LED 102. The p-polarized light from the LED 121 passes through two reflections at the reflection units 103 and 104, one reflection at the polarizing film 107, two transmissions through the polarizing film 107, and one transmission through the reflective polarizing plate 520. The light is emitted from 120.

  Of the light incident on the reflective polarizing plate 520 from the LED 121, the s-polarized light travels in the direction of the LED 121 after being reflected by the reflective polarizing plate 520. The s-polarized light traveling in the direction of the LED 121 is converted into p-polarized light by passing through the λ / 4 phase plate 505 twice before being reflected by the reflecting portion 122 and entering the reflective polarizing plate 520 again. . The light converted into p-polarized light is transmitted through the reflective polarizing plate 520 and behaves in the same manner as the p-polarized light from the LED 121. In this way, the light from the LED 121 can travel in the predetermined illumination direction L.

  Of the light incident on the polarization beam splitter 108 from the LED 102, the p-polarized light passes through the polarizing film 107 and the reflective polarizing plate 520 and travels in the direction of the LED 121. The p-polarized light traveling in the direction of the LED 121 is converted into s-polarized light by passing through the λ / 4 phase plate 505 twice before being incident on the reflection-type polarizing plate 520 reflected again by the reflection unit 122. The light converted into s-polarized light is reflected by the reflective polarizing plate 520 and travels in the direction of the LED 121. The s-polarized light traveling in the direction of the LED 121 is reflected by the reflecting unit 122 and behaves in the same manner as the s-polarized light from the LED 121.

  Assuming that the intensity of the illumination light when the p-polarized light from one LED is taken out for illumination is 0.5, the total power of the illumination light emitted from the light source device 120 of this embodiment is about 0.889. It is. The utilization efficiency of the emitted light of the LEDs 101, 102, 121 is approximately 30% per LED. Further, based on the case where illumination is performed by extracting p-polarized light from one LED, the light source device 120 of the present embodiment can supply illumination light having an intensity of about 1.78 times. The reflectances of the reflecting portions 103, 104, 122, the polarizing film 107, and the reflective polarizing plate 520 and the transmittances of the polarizing film 107 and the reflective polarizing plate 520 are the same as those in the first embodiment.

  According to the present embodiment, the light from the LED 121 as the third light emitting unit can also travel in the illumination direction L. Thereby, brighter illumination light can be supplied. In addition, by using the reflective polarizing plate 520, only polarized light in the first vibration direction is extracted from the LED 121. The polarized light in the second vibration direction reflected by the reflective polarizing plate 520 can be reused by converting it into polarized light in the first vibration direction using the λ / 4 phase plate 505. Thereby, the polarized light in the first vibration direction can be supplied with high efficiency. The light source device 120 of the present embodiment may be provided with an optical element as in the first embodiment.

  FIG. 13 shows a configuration of a light source device 130 according to a modification of the present embodiment. The light source device 130 is provided with a reflective polarizing plate 520 on the exit side of the polarizing beam splitter 108. The p-polarized light incident on the polarization beam splitter 108 from the LED 101 passes through the polarizing film 107 and the reflective polarizing plate 520 and travels in the illumination direction L. The p-polarized light incident on the polarization beam splitter 108 from the LED 121 passes through the polarizing film 107 and travels toward the LED 102. The p-polarized light traveling in the direction of the LED 102 behaves in the same manner as the p-polarized light from the LED 102.

  The s-polarized light incident on the polarization beam splitter 108 from the LED 121 is reflected by the polarizing film 107 and then incident on the reflective polarizing plate 520. The s-polarized light incident on the reflective polarizing plate 520 is reflected by the reflective polarizing plate 520 and is incident on the polarizing beam splitter 108 again. The s-polarized light incident on the polarization beam splitter 108 is reflected by the polarizing film 107 and travels in the direction of the LED 121. The s-polarized light traveling in the direction of the LED 121 is converted into p-polarized light by passing through the λ / 4 phase plate 505 twice before being reflected by the reflection unit 122 and entering the polarization beam splitter 108. The p-polarized light incident on the polarization beam splitter 108 behaves in the same manner as the p-polarized light from the LED 121. Thus, also in this modification, the light from LED121 can be made to advance to the illumination direction L. FIG.

  The λ / 4 phase plate is not limited to the configuration provided corresponding to each LED 101, 102, 121 like the light source device 120 or the light source device 130. The λ / 4 phase plate may be configured to be provided between each LED 101, 102, 121 and the polarizing beam splitter 108 and at least one place on the emission side of the polarizing beam splitter 108. For example, like the light source device 140 shown in FIG. 14, the λ / 4 phase plate 505 may be removed from the configuration of the light source device 130. Further, a λ / 4 phase plate 155 may be provided between the reflective polarizing plate 520 and the polarizing beam splitter 108 as in the light source device 150 shown in FIG. Furthermore, a configuration in which a λ / 4 phase plate is not provided between each LED 101, 102, 121 and the polarizing beam splitter 108 and on the exit side of the polarizing beam splitter 108 may be employed.

  FIG. 16 shows the relationship between the configuration of the light source device and the intensity of illumination light. The positions of the λ / 4 phase plate and the reflective polarizing plate are represented by the numbers shown in FIG. 11 as in the first embodiment. In the configurations J to Z, the LEDs 101, 102, and 121 are provided at the position 1, the position 2, and the position 3, respectively. Further, the total power of illumination light and the brightness magnification are the same as those in the first embodiment.

  Configurations J, K, and L indicate the light source device 120 in FIG. 12, the light source device 130 in FIG. 13, and the light source device 140 in FIG. 14, respectively. Configurations M and N are obtained by changing the positions of the two λ / 4 phase plates from the configuration of the light source device 140. In the configuration O, the λ / 4 phase plate 105 at the position 2 is removed from the configuration of the light source device 140, and the λ / 4 phase plate 106 is disposed only at the position 1. In the configurations P and Q, the position of the λ / 4 phase plate is changed from the configuration O, respectively. Configuration R is obtained by removing all λ / 4 phase plates from the configuration of the light source device 130.

  The configuration S is obtained by adding the λ / 4 phase plate 155 at the position 4 to the configuration of the light source device 140, and shows the light source device 150 of FIG. Configurations T to Z are obtained by changing the arrangement of the λ / 4 phase plates at positions 1, 2, and 3 from the light source device 150. As shown in the table of FIG. 16, particularly bright illumination light can be obtained when the reflective polarizing plate 520 is disposed at the position 3.

  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 three-plate projector provided with three liquid crystal type spatial light modulators 172R, 172G, and 172B. The projector 1700 includes a light source device for R light 170R, a light source device for G light 170G, and a light source device for B light 170B. Each of the light source devices 170R, 170G, and 170B has the same configuration as the light source device 100 of the first embodiment.

  The light source device for R light 170R has two LEDs for R light 171R. The LED 171R for R light supplies R light. The R light source device 170R converts the R light from the R light LED 171R into polarized light having a specific vibration direction, for example, p-polarized light, and proceeds in the direction of the liquid crystal spatial light modulator 172R, which is a predetermined direction. Let The liquid crystal spatial light modulator 172R 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 172R is converted into s-polarized light by modulation. The R light converted into s-polarized light by the liquid crystal type spatial light modulator 172R enters the cross dichroic prism 173.

  The light source device for G light 170G includes two LEDs for G light 171G. The G light LED 171G supplies G light. The G light source device 170G converts the G light from the G light LED 171G into polarized light having a specific vibration direction, for example, p-polarized light, and proceeds in the direction of the liquid crystal spatial light modulator 172G, which is a predetermined direction. Let The liquid crystal spatial light modulator 172G 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 172G is converted into s-polarized light by modulation. The G light converted into s-polarized light by the liquid crystal spatial light modulator 172G enters the cross dichroic prism 173 from a surface different from the R light.

  The light source device for B light 170B has two LEDs for R light 171B. The B light LED 171B supplies B light. The B light source device 170B converts the B light from the B light LED 171B into polarized light having a specific vibration direction, for example, p-polarized light, and proceeds in the direction of the liquid crystal spatial light modulator 172B, which is a predetermined direction. Let The liquid crystal spatial light modulator 172B 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 172B is converted into s-polarized light by modulation. The B light converted into the s-polarized light by the liquid crystal type spatial light modulator 172B enters the cross dichroic prism 173 from a plane different from the R light and the G light.

  A cross dichroic prism 173 that is a color synthesis optical system includes two dichroic films 173a and 173b. The dichroic films 173a and 173b are arranged orthogonal to the X shape. The dichroic film 173a reflects R light and transmits G light. The dichroic film 173b reflects B light and transmits G light. In this manner, the cross dichroic prism 173 combines the R light, G light, and B light modulated by the liquid crystal type spatial light modulators 172R, 172G, and 172B, respectively. The projection optical system 174 projects the light combined by the cross dichroic prism 173 onto the screen 175.

  The dichroic films 173a and 173b are usually excellent in the reflection characteristics of s-polarized light. For this reason, it is desirable that the R light and B light to be reflected by the dichroic films 173a and 173b are incident on the cross dichroic prism 173 as s-polarized light. Further, it is desirable that the G light to be transmitted through the dichroic films 173a and 173b becomes p-polarized light and enters the cross dichroic prism 173. In order to make the G light converted into the s-polarized light enter the cross dichroic prism 173, for example, a λ / 2 phase plate may be provided between the liquid crystal type spatial light modulator 172G and the cross dichroic prism 173.

  By using each color light source device 170R, 170G, 170B, the projector 1700 can supply light with high efficiency to the liquid crystal type spatial light modulators 172R, 172G, 172B to be illuminated. As a result, a bright image can be displayed with high light utilization efficiency. Each light source device for color light 170R, 170G, and 170B may have the same configuration as the light source device 100 of the first embodiment, and may have the same configuration as the other light source devices of the first and second embodiments.

  FIG. 18 shows a schematic configuration of a projector 1800 that is an image display apparatus according to Embodiment 4 of the present invention. The same parts as those of the projector 1800 of the third embodiment are denoted by the same reference numerals, and redundant description is omitted. The projector 1800 is a so-called single-plate projector that includes one liquid crystal type spatial light modulator 182. The projector 1800 includes a light source device 180 having the same configuration as that of the light source device 120 of the second embodiment. The light source device 180 includes a G light LED 171G that is a first light emitting unit, a B light LED 171B that is a second light emitting unit, and an R light LED 171R that is a third light emitting unit. The light source device 180 converts G light, B light, and R light into polarized light having a specific vibration direction, for example, p-polarized light, and advances the light toward the liquid crystal spatial light modulator 182 that is a predetermined direction.

  A color filter (not shown) is provided on the incident side of the liquid crystal spatial light modulator 182. The color filter separates each color light from the light source device 180. The color filters include an R light transmission color filter, a G light transmission color filter, and a B light transmission color filter corresponding to the R light pixel, G light pixel, and B light pixel of the liquid crystal spatial light modulator 182. Is provided. The liquid crystal spatial light modulator 182 is a transmissive liquid crystal display device that modulates R light, G light, and B light transmitted through a color filter in accordance with an image signal. The light modulated by the liquid crystal type spatial light modulator 182 enters the projection optical system 174.

  By using the light source device 180, the projector 1800 can supply light with high efficiency to the liquid crystal type spatial light modulation device 182 to be illuminated. The light source device 180 is not limited to the configuration in which the LED for G light 171G, the LED for B light 171B, and the LED for R light 171R are provided, and an LED for supplying white light including R light, G light, and B light may be provided. . The projector 1800 is not limited to the color separation using the color filter, and the G light LED 171G, the B light LED 171B, and the R light LED 171R may be sequentially turned on.

  In addition, although the light source device of each said Example uses LED as a light emission part, it is not restricted to this. Instead of the LED, other solid light emitting elements such as an EL element and a semiconductor laser may be used. The spatial light modulation device used for the projector is not limited to the transmissive liquid crystal display device, and a reflective liquid crystal display device may be used. Furthermore, the image display device provided with the light source 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 light source device according to the present invention is useful when used in a projector, and is particularly suitable for a projector that modulates polarized light in a specific vibration direction.

1 is a schematic configuration diagram of a light source device according to Embodiment 1 of the present invention. The block diagram of the light source device using a collimator lens. The block diagram of the light source device using a condensing lens. The block diagram of the light source device using a rod integrator. The figure explaining the modification of a light source device. The figure explaining the modification of a light source device. The figure explaining the modification of a light source device. The figure explaining the modification of a light source device. The figure explaining the modification of a light source device. The figure which shows the relationship between the structure of a light source device, and the intensity | strength of illumination light. The figure explaining the position of the structure of a light source device. The schematic block diagram of the light source device which concerns on Example 2 of this invention. The figure explaining the modification of a light source device. The figure explaining the modification of a light source device. The figure explaining the modification of a light source device. The figure which shows the relationship between the structure of a light source device, and the intensity | strength of illumination light. FIG. 6 is a schematic configuration diagram of a projector according to a third embodiment of the invention. FIG. 10 is a schematic configuration diagram of a projector according to a fourth embodiment of the invention.

Explanation of symbols

  100 light source device, 101, 102 LED, 103, 104 reflector, 105, 106 λ / 4 phase plate, 107 polarizing film, 108 polarizing beam splitter, 109 mirror, AX optical axis, BX axis, L illumination direction, 200 light source device , 211, 212 Collimator lens, 300 Light source device, 311, 312 Condensing lens, 400 Light source device, 411, 412 Rod integrator, 500 Light source device, 505 λ / 4 phase plate, 520 Reflective polarizing plate, 600, 700, 800 , 900 light source device, 120 light source device, 121 LED, 122 reflector, 130, 140, 150 light source device, 155 λ / 4 phase plate, 1700 projector, 170R light source device for R light, 170G light source device for 170 G light, 170B B Light source device for light, 172R, 172G, 172B Liquid crystal type spatial light modulator, 173 Cross dichroic prism, 173a, 172b Dichroic film, 174 projection optical system, 175 screen, 1800 projector, 180 light source device, 182 Liquid crystal type spatial light modulator

Claims (11)

At least two light emitting units for supplying light;
Light from the light emitting unit is transmitted by transmitting polarized light in the first vibration direction out of light from the light emitting unit and reflecting polarized light in the second vibration direction substantially orthogonal to the first vibration direction. A polarization separation unit that separates the polarized light in the first vibration direction and the polarized light in the second vibration direction,
The light emitting unit includes a reflecting unit that reflects light traveling in the direction of the light emitting unit from the polarization separating unit in the direction of the polarization separating unit,
The polarized light separating unit is supplied with light from the light emitting unit and directly enters the polarized light separating unit, and the first vibration is reflected by the reflecting unit and then incident on the polarized light separating unit. A light source device characterized by combining polarized light in a direction and traveling in a predetermined direction.   2. The light source device according to claim 1, further comprising: a phase plate provided at least at one position between the light emitting unit and the polarization separation unit and on an emission side of the polarization separation unit.   The light source device according to claim 1, further comprising an optical element that is provided between the light emitting unit and the polarization separating unit and guides light from the light emitting unit to the polarization separating unit.   The light source device according to claim 3, wherein the optical element is a rod integrator that makes light from the light emitting section substantially uniform.   The light source device according to claim 3, wherein the optical element is a collimator lens that makes light from the light emitting portion substantially parallel.   The light source device according to claim 3, wherein the optical element is a condenser lens that collects light from the light emitting unit.   The light source device according to claim 1, further comprising a mirror that reflects light traveling in a direction different from the predetermined direction from the polarization separation unit toward the polarization separation unit. Having at least a first light emitting part and a second light emitting part,
The first light emitting unit travels in the predetermined direction after the polarized light in the first vibration direction incident on the polarization separating unit from the first light emitting unit is transmitted through the polarization separating unit, and the first light emitting unit The polarized light in the second vibration direction incident on the polarization separation unit from the two light emission units is provided at a position so as to travel in the direction of the first light emission unit after reflecting the polarization separation unit,
The second light emitting unit travels in the direction of the second light emitting unit after the polarized light having the second vibration direction incident on the polarization separating unit from the first light emitting unit is reflected by the polarization separating unit. The light source device according to claim 1, wherein the light source device is provided at such a position. Furthermore, it has a 3rd light emission part,
The third light emitting unit travels in the direction of the second light emitting unit after the polarized light having the first vibration direction incident on the polarization separating unit from the third light emitting unit is transmitted through the polarization separating unit. The light source device according to claim 8, wherein the light source device is provided at such a position.   Provided on at least one of the third light emitting unit and the polarization separation unit and on the emission side of the polarization separation unit, transmits polarized light in the first vibration direction, and the second vibration direction. The light source device according to claim 9, further comprising a reflective polarizing plate that reflects the polarized light. The light source device according to any one of claims 1 to 10,
And a spatial light modulator that modulates light from the light source device according to an image signal.

Images