JP2007233218A - Method for manufacturing illuminator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an illuminator capable of efficiently supplying polarized light in a specific oscillating direction. <P>SOLUTION: The method for manufacturing the illuminator including: a rod integrator 15 serving as a uniformizing part that substantially uniformizes the intensity distribution of a luminous flux from a light source part; a reflection type polarizing plate 16 that transmits polarization light emitted from the rod integrator 15 in the first oscillating direction and reflects polarization light in the second oscillating direction substantially perpendicular to the first oscillating direction; a 1/4-wavelength plate 14 disposed in an optical path between the light source part and the reflection type polarizing plate 16 includes: a light quantity detecting step in which a quantity of light transmitted by the reflection type polarizing plate 16 is detected; and a wavelength plate rotating step in which the 1/4-wavelength plate 14 is rotated around the optical axis AX so that the quantity of light detected in the light quantity detecting step is maximum. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a lighting device, and more particularly to a technique for manufacturing a lighting device used in a projector.

  A liquid crystal display device used as a spatial light modulation device of a projector modulates incident light by converting the polarization state of incident light. When a liquid crystal display device is used, the light from the light source unit can be efficiently used by converting the light from the light source unit into polarized light having a specific vibration direction and supplying it. For example, Patent Document 1 proposes a technique for supplying light after converting it into polarized light having a specific vibration direction.

JP 2003-57445 A

  Polarized light reflected by the reflective polarizing plate, for example, s-polarized light, can be converted into p-polarized light that is polarized light in a specific vibration direction by passing through the quarter-wave plate twice. However, it is conceivable that the light reflected by the reflective polarizing plate changes from linearly polarized light or circularly polarized light to elliptically polarized light by being repeatedly reflected by the rod integrator. When the polarization state of the light changes in the rod integrator, it becomes difficult to convert the light reflected by the reflective polarizing plate into polarized light having a specific vibration direction with high efficiency and to enter the reflective polarizing plate. Such a change in the polarization state becomes more prominent as a rod integrator that is long in the direction of the optical axis is used in order to make the light sufficiently uniform. For this reason, according to the conventional technique, there is a problem that it may be difficult to efficiently supply polarized light in a specific vibration direction. The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a method for manufacturing a lighting device for manufacturing a lighting device that can efficiently supply polarized light in a specific vibration direction.

  In order to solve the above-described problems and achieve the object, according to the present invention, a uniformizing unit that substantially uniforms the intensity distribution of the light beam from the light source unit, and polarization in the first vibration direction from the uniformizing unit. A reflective polarizing plate that transmits light and reflects polarized light in a second vibration direction substantially orthogonal to the first vibration direction; and a wave plate provided in an optical path between the light source unit and the reflective polarizing plate. A method of manufacturing an illuminating device comprising: a light amount detecting step for detecting the amount of light transmitted through a reflective polarizing plate; and a wave plate centering on the optical axis so that the amount of light detected in the light amount detecting step is maximized And a wave plate rotation step for rotating the illumination device.

  The quarter wave plate, which is a wave plate, converts linearly polarized light having a polarization axis of 45 degrees with respect to the optical axis into circularly polarized light and circularly polarized light into linearly polarized light. It is conceivable that the light reflected by the reflective polarizing plate changes its polarization state due to reflection at the uniformizing portion. By rotating the wave plate so that the amount of light transmitted through the reflective polarizing plate is maximized, polarized light in a specific vibration direction can be efficiently supplied regardless of the degree of polarization change at the homogenizing section. Possible configurations can be obtained. Thereby, the illuminating device which can supply the polarized light of a specific vibration direction efficiently can be manufactured.

  As a preferred embodiment of the present invention, it is desirable to detect the light amount using an integrating sphere in the light amount detection step. By using an integrating sphere, the amount of light from the reflective polarizing plate can be accurately detected. Thereby, the illuminating device which can supply the polarized light of a specific vibration direction efficiently can be manufactured with high precision.

  Moreover, as a preferable aspect of the present invention, it is desirable that the wave plate is provided in an optical path between the light source unit and the uniformizing unit. By providing the wave plate in the optical path between the light source unit and the uniformizing unit, the wave plate can be rotated with respect to the optical axis and the loss of light can be reduced.

  Moreover, as a preferable aspect of the present invention, it is desirable to have a reflecting portion that reflects light traveling from the homogenizing portion toward the light source portion toward the uniformizing portion. As a result, the light that has been reflected by the reflective polarizing plate and then travels toward the light source through the uniformizing portion can be advanced toward the uniformizing portion and guided toward the reflective polarizing plate.

  Moreover, as a preferable aspect of the present invention, the light source unit preferably includes a solid light source. As the solid light source, for example, a light emitting diode element (hereinafter, referred to as “LED” as appropriate) can be used. The LED is a small and lightweight light emitter. When an LED is used for the lighting device, the lighting device can be reduced in size and weight. Moreover, the electrode of LED can be used as a reflection part.

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

  FIG. 1 shows a schematic configuration of a lighting device 10 manufactured by a method for manufacturing a lighting device according to Embodiment 1 of the present invention. LED11 which is a solid light source is a light source part which supplies light. The LED 11 is a surface-emitting light source that mainly emits light from the surface of the chip. The LED 11 has a reflecting portion 12. The reflection part 12 is a metal electrode formed of a highly reflective metal member. The rod integrator 15 is a uniformizing unit that makes the intensity distribution of the light beam from the LED 11 that is a light source unit substantially uniform. A collimator lens 13 and a quarter wavelength plate 14 are provided in the optical path between the LED 11 and the rod integrator 15.

  The collimator lens 13 makes the light from the LED 11 substantially parallel. The quarter wave plate 14 which is a wave plate is provided in the optical path between the LED 11 which is a light source unit and the rod integrator 15 which is a uniformizing unit. The quarter-wave plate 14 is a birefringent element that gives a quarter-wave phase difference between polarized components whose vibration directions are orthogonal to each other. The quarter wave plate 14 can be formed using a birefringent crystal such as mica or quartz.

  The rod integrator 15 is made of a transparent glass member having a rectangular parallelepiped shape. The light incident on the rod integrator 15 travels inside the rod integrator 15 while repeating total reflection at the interface between the glass member and air. Thereby, the rod integrator 15 makes the intensity distribution of the light beam from the LED 11 substantially uniform. The rod integrator 15 is not limited to a glass member, but may be a hollow structure whose inner surface is 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.

  The reflective polarizing plate 16 is provided on the surface of the rod integrator 15 opposite to the LED 11 side. The reflective polarizing plate 16 transmits the polarized light in the first vibration direction from the rod integrator 15 and reflects 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. Each part from the LED 11 to the reflective polarizing plate 16 is arranged on the linear optical axis AX.

  As the reflective polarizing plate 16, for example, a wire grid type polarizing plate can be used. The wire grid type polarizing plate can use a configuration 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. 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 arranging 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. As the reflective polarizing plate, a polarizing beam splitter having a polarizing separation film may be used in addition to the wire grid polarizing plate. In addition, the illuminating device 10 is not restricted to the structure which arrange | positions each part from LED11 to the reflection type polarizing plate 16 on a straight line, You may deform | transform suitably.

  FIG. 2 explains the behavior of light from the LED 11. The LED 11 supplies light including p-polarized light and s-polarized light. The light from the LED 11 enters the rod integrator 15 after passing through the collimator lens 13 and the quarter wavelength plate 14. Of the light that has propagated through the rod integrator 15 and entered the reflective polarizing plate 16, p-polarized light passes through the reflective polarizing plate 16. Of the light incident on the reflective polarizing plate 16, the s-polarized light is reflected by the reflective polarizing plate 16 and then travels through the rod integrator 15 in the opposite direction.

  The s-polarized light incident on the quarter wavelength plate 14 from the rod integrator 15 is converted into circularly polarized light by passing through the quarter wavelength plate 14. The light from the quarter wave plate 14 travels in the direction of the LED 11 after passing through the collimator lens 13. The reflection unit 12 reflects light traveling from the rod integrator 15 toward the LED 11 toward the rod integrator 15. The light that has entered the LED 11 travels in the direction of the rod integrator 15 due to reflection by the reflection unit 12.

  Circularly polarized light incident on the quarter-wave plate 14 from the LED 11 is converted to p-polarized light by passing through the quarter-wave plate 14. Thus, by allowing light to pass through the quarter-wave plate 14 twice, the vibration direction of the light can be rotated by 90 degrees. The p-polarized light that has entered the reflective polarizing plate 16 through the quarter-wave plate 14 and the rod integrator 15 passes through the reflective polarizing plate 16. In this way, the lighting device 10 converts the light reflected by the reflective polarizing plate 16 into polarized light having a specific vibration direction and returns it to the reflective polarizing plate 16, thereby efficiently converting the polarized light having a specific vibration direction. Can be supplied well.

  It is conceivable that the light reflected by the reflective polarizing plate 16 changes from linearly polarized light or circularly polarized light to elliptically polarized light by being repeatedly reflected in the rod integrator 15. When the polarization state of the light changes in the rod integrator 15, the light reflected by the reflective polarizing plate 16 is converted into polarized light having a specific vibration direction with high efficiency and is incident on the reflective polarizing plate 16. It becomes difficult. Such a change in the polarization state becomes more conspicuous as the rod integrator 15 that is long in the optical axis direction is used in order to make the light sufficiently uniform. The illuminating device 10 is desired to be able to efficiently supply polarized light having a specific vibration direction regardless of the change in the polarization state in the rod integrator 15.

  FIG. 3 is a flowchart illustrating a procedure for manufacturing the lighting device 10. In step S <b> 1, each optical element of the illumination device 10 is installed from the LED 11 to the reflective polarizing plate 16. Next, in step S2, an integrating sphere and an illuminometer are installed. As shown in FIG. 4, the integrating sphere 20 is disposed on the exit side of the reflective polarizing plate 16 in the illumination device 10. The integrating sphere 20 is a hollow sphere. A scattering surface 21 that scatters light is formed on the entire inner surface of the integrating sphere 20. The integrating sphere 20 is installed by fitting the reflective polarizing plate 16 into the sample opening.

  The illuminometer 22 is installed in the detector opening of the integrating sphere 20. The illuminometer 22 measures the amount of light from the reflective polarizing plate 16. The integrating sphere 20 is provided with a shielding portion (not shown) that shields light traveling directly from the reflective polarizing plate 16 toward the illuminometer 22 so that light sufficiently scattered in the integrating sphere 20 enters the illuminometer 22. Let By detecting the light made sufficiently uniform by scattering in the integrating sphere 20 with the illuminance meter 22, the amount of light from the reflective polarizing plate 16 can be accurately detected.

  Returning to FIG. 3, in step S <b> 3, the quarter-wave plate 14 is rotated while measuring the amount of light by the illuminometer 22. The quarter wavelength plate 14 is rotated about the optical axis AX as shown in FIG. The light quantity measurement in step S3 and the rotation of the quarter wavelength plate 14 are continued until it can be recognized that the light quantity measured by the illuminometer 22 is maximum in step S4. When it is recognized in step S4 that the light amount measured by the illuminometer 22 is maximum, in step S5, the rotation of the quarter wavelength plate 14 is performed at the position where the light amount measured by the illuminometer 22 is maximum. The movement is stopped, and the position of the quarter-wave plate 14 is determined about the optical axis AX. Steps S3 and S4 are ¼ centering on the optical axis AX so that the amount of light detected in the amount of light transmitted through the reflective polarizing plate 16 and the amount of light detected in the amount of light detection step are maximized. This is a wave plate rotating step of rotating the wave plate 14. The lighting device 10 is manufactured through such a procedure.

  FIG. 5 explains the rotation of the quarter-wave plate 14. When linearly polarized light is incident on the quarter wavelength plate 14, the linearly polarized light is divided into a polarization component in the optical axis direction of the quarter wavelength plate 14 and a polarization component in a direction orthogonal to the optical axis. The polarization component in the direction orthogonal to the optical axis of the quarter wavelength plate 14 is delayed by a quarter wavelength when transmitted through the quarter wavelength plate 14. When the ¼ wavelength plate 14 is arranged so that the polarization axis of the linearly polarized light is 45 degrees with respect to the optical axis of the ¼ wavelength plate 14, the linearly polarized light is in the optical axis direction of the ¼ wavelength plate 14. The light beam is equally divided into a polarized light component and a polarized light component in a direction orthogonal to the optical axis. At this time, since the polarization component in the direction orthogonal to the optical axis is delayed by 1/4 wavelength with respect to the polarization component in the optical axis direction of the quarter wavelength plate 14, the light emitted from the quarter wavelength plate 14 is circular. It becomes polarized light. As described above, when the quarter wavelength plate 14 is arranged so that the polarization axis of the linearly polarized light is 45 degrees with respect to the optical axis of the quarter wavelength plate 14, the linearly polarized light is converted into circularly polarized light. Moreover, circularly polarized light can be converted into linearly polarized light by the reverse action.

  When linearly polarized light or circularly polarized light changes to elliptically polarized light due to reflection at the rod integrator 15, it is considered that the efficiency of converting s-polarized light into p-polarized light by passing through the quarter-wave plate 14 twice is considered to be reduced. By rotating the optical axis of the quarter-wave plate 14 while detecting the amount of light transmitted through the reflective polarizing plate 16, it is possible to convert s-polarized light into p-polarized light with the highest efficiency. Correction can be performed. Since the quarter-wave plate 14 is rotated so that the amount of light transmitted through the reflective polarizing plate 16 is maximized, polarized light in a specific vibration direction is used regardless of the degree of change of the polarization state by the rod integrator 15. Can be supplied efficiently. Thereby, the illuminating device 10 which can supply the polarized light of a specific vibration direction efficiently can be manufactured.

  The quarter-wave plate 14 is not limited to being disposed on the LED 11 side of the rod integrator 15, and may be provided at least in the optical path between the LED 11 and the reflective polarizing plate 16. For example, like the illumination device 30 in FIG. 6, the quarter-wave plate 14 may be provided between the rod integrator 15 and the reflective polarizing plate 16. The quarter-wave plate 14 needs to be rotatable by being arranged away from the rod integrator 15. Further, in order to reduce the loss of light between the rod integrator 15 and the quarter wavelength plate 14 as much as possible, it is desirable that the quarter wavelength plate 14 is disposed as close as possible to the rod integrator 15. The illumination device manufactured according to the present embodiment may use a solid light emitting element other than the LED, for example, an organic EL element or a semiconductor laser.

  The light quantity detection step is not limited to the case where the light quantity is measured using the integrating sphere 20. It is only necessary to recognize the state where the light transmitted through the reflective polarizing plate 16 is maximized. For example, the illuminance meter 22 may be disposed directly on the exit side of the reflective polarizing plate 16. The means for detecting the light quantity is not limited to the case where the light quantity is measured using the illuminance meter 22. What can detect a light quantity should just be used, for example, it is good also as detecting a light quantity using an optical power meter etc.

  FIG. 7 shows a schematic configuration of the projector 40 according to the second embodiment of the invention. The projector 40 is a so-called front projection type projector that supplies light to the screen 44 and observes an image by observing the light reflected by the screen 44. The projector 40 includes a red (R) light illumination device 10R, a green (G) light illumination device 10G, and a blue (B) light illumination device 10B.

  The R light LED 11R provided in the R light illumination device 10R is a light source unit that supplies R light. The R light illumination device 10 </ b> R supplies R light to the R light spatial light modulation device 41 </ b> R to be illuminated. The spatial light modulator 41R for R light is a transmissive liquid crystal display device that modulates R light according to an image signal. The R light modulated by the R light spatial light modulator 41R is incident on a cross dichroic prism 42 which is a color synthesis optical system.

  The G light LED 11G provided in the G light illumination device 10G is a light source unit that supplies G light. The G light illumination device 10 </ b> G supplies G light to the G light spatial light modulation device 41 </ b> G to be illuminated. The spatial light modulator 41G for G light is a transmissive liquid crystal display device that modulates G light according to an image signal. The G light modulated by the G light spatial light modulator 41G is incident on a cross dichroic prism 42 which is a color synthesis optical system.

  The B light LED 11B provided in the B light illumination device 10B supplies B light. The B light illumination device 10 </ b> B supplies B light to the B light spatial light modulation device 41 </ b> B to be illuminated. The B light spatial light modulation device 41B is a transmissive liquid crystal display device that modulates B light according to an image signal. The B light modulated by the B light spatial light modulator 41B is incident on a cross dichroic prism 42 which is a color synthesis optical system.

  The cross dichroic prism 42 has two dichroic films 42a and 42b arranged so as to be substantially orthogonal to each other. The first dichroic film 42a reflects R light and transmits G light and B light. The second dichroic film 42b reflects B light and transmits R light and G light. The cross dichroic prism 42 combines the R light, G light, and B light incident from different directions and emits the light toward the projection lens 43. The projection lens 43 projects the light combined by the cross dichroic prism 42 in the direction of the screen 44.

  The projector 40 can efficiently supply polarized light in a specific vibration direction by each of the lighting devices 10R, 10G, and 10B manufactured by the manufacturing method of the lighting device according to the first embodiment. Thereby, the projector 40 capable of displaying a bright image with high light use efficiency can be obtained. The projector 40 according to the present embodiment is not limited to the configuration in which the three transmissive liquid crystal display devices are provided. For example, the projector 40 may be configured to have one transmissive liquid crystal display device or a reflective liquid crystal display device. good.

  As described above, the method for manufacturing an illumination device according to the present invention is suitable for manufacturing an illumination device used for a projector.

The figure which shows schematic structure of the illuminating device manufactured by the manufacturing method which concerns on Example 1. FIG. The figure explaining the behavior of the light from LED. The flowchart explaining the procedure which manufactures an illuminating device. The figure explaining a light quantity detection process and a wave plate rotation process. The figure explaining rotation of a quarter wavelength plate. The figure of the structure which provides a wavelength plate between a rod integrator and a reflection type polarizing plate. FIG. 6 is a diagram illustrating a schematic configuration of a projector according to a second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Illuminating device, 11 LED, 12 Reflection part, 13 Collimator lens, 14 1/4 wavelength plate, 15 Rod integrator, 16 Reflective polarizing plate, AX Optical axis, 20 Integrating sphere, 21 Scattering surface, 22 Illuminometer, 30 Illumination Device, 10R R light illumination device, 10G G light illumination device, 10B B light illumination device, 40 projector, 41R R light spatial light modulation device, 41G G light spatial light modulation device, 41B B light spatial light Modulator, 42 Cross dichroic prism, 42a First dichroic film, 42b Second dichroic film, 43 projection lens, 44 screen

Claims (5)

A uniformizing unit that makes the intensity distribution of the luminous flux from the light source unit substantially uniform;
A reflective polarizing plate that transmits polarized light in the first vibration direction from the uniformizing section and reflects polarized light in the second vibration direction substantially orthogonal to the first vibration direction;
A wave plate provided in an optical path between the light source unit and the reflective polarizing plate, and a manufacturing method of a lighting device,
A light amount detection step of detecting the amount of light transmitted through the reflective polarizing plate;
And a wave plate rotating step of rotating the wave plate about the optical axis so that the amount of light detected in the light amount detecting step is maximized.   The method of manufacturing an illumination device according to claim 1, wherein in the light amount detection step, the light amount is detected using an integrating sphere.   3. The method of manufacturing an illumination device according to claim 1, wherein the wave plate is provided in an optical path between the light source unit and the uniformizing unit.   The manufacture of the lighting device according to any one of claims 1 to 3, further comprising a reflection unit that reflects light traveling from the uniformizing unit toward the light source unit toward the uniformizing unit. Method. The said light source part is provided with a solid light source, The manufacturing method of the illuminating device as described in any one of Claims 1-4 characterized by the above-mentioned.

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