JP6323072B2 - Lighting device and projector - Google Patents

Description

  The present invention relates to a lighting device and a projector.

  As a light source for a projector, a laser light source such as a semiconductor laser (LD) capable of obtaining light with high luminance and high output has attracted attention. A projector using a laser light source has advantages such as miniaturization of the apparatus, excellent color reproducibility, instant lighting, and a long light source life. On the other hand, the laser light emitted from the laser light source is generally coherent light. For this reason, in this type of projector, a speckle pattern generated by the interference of laser light, so-called speckles, may be visually recognized on the screen. Thereby, the display quality is greatly reduced.

  Patent Document 1 below discloses an illumination device including an integrator optical system for uniformly illuminating a spatial light modulation element, and an image display device including the illumination device. The integrator optical system in the illumination device of Patent Document 1 is configured by a fly-eye lens integrator optical system including a pair of fly-eye lenses, and uniformizes the luminance distribution of illumination light from a laser light source.

JP 2009-175681 A

  In the image display device described in Patent Document 1, one secondary light source image is formed for each lens of the second fly's eye lens constituting the integrator optical system. However, in this configuration, when the light emitted from the integrator optical system is applied to the spatial light modulation element via a lens subsequent to the integrator optical system, the angular distribution of the light incident on the spatial light modulation element is narrow. Therefore, there arises a problem that speckles are easily visually recognized by an observer of the image display apparatus.

  One aspect of the present invention is made to solve the above-described problem, and an illumination device that emits illumination light in which speckles are difficult to visually recognize, and a projector in which speckles are difficult to visually recognize using the illumination device. Is one of the purposes.

  In order to achieve the above object, an illumination device according to one aspect of the present invention includes a light source device including at least one solid-state light source, a collimating optical system on which light from the light source device is incident, and the collimating optical system. A first lens on which the light from the first lens enters, a second lens on which the light from the first lens enters, an optical element that guides the light from the second lens to an illuminated area, and the collimating optical system Light that is provided in an optical path between the first lens and the second lens, and generates a plurality of light fluxes having different traveling directions from incident light so that a plurality of secondary light source images are formed in the second lens. And a deflection element.

  In the illumination device according to one aspect of the present invention, a plurality of light beams having different traveling directions are generated from incident light by the light deflection element provided in the optical path between the collimating optical system and the second lens, A plurality of secondary light source images are formed in the second lens. Here, if there is no light deflection element, only one secondary light source image is formed in the second lens. On the other hand, in the illumination device according to one aspect of the present invention, a plurality of secondary light source images are formed in the second lens, and therefore the angular distribution of illumination light emitted from the second lens is light deflection. It is wider than when no element is present. As a result, it is possible to realize an illuminating device in which speckles are hardly visually recognized when used in a projector.

In the illumination device according to one aspect of the present invention, the light deflection element may be a deflection prism array.
If the light deflection element is a declination prism array, only the direction of the principal ray of each of the plurality of light beams can be changed while maintaining the angular distribution of the light from the collimating optical system. Therefore, it is possible to efficiently generate a plurality of light beams having different traveling directions.

In the illumination device according to one aspect of the present invention, the light deflection element may be provided in an optical path between the collimating optical system and the first lens.
According to this configuration, since no aberration is generated, a plurality of secondary light source images are not distorted in the second lens.

The illumination device according to one aspect of the present invention may further include a diffusion plate provided in an optical path between the collimating optical system and the first lens.
According to this configuration, the angular distribution of the illumination light emitted from the second lens can be made broader, and an illuminating device that can be applied to a projector in which speckle is difficult to be visually recognized can be realized.

In the illumination device according to one aspect of the present invention, the plurality of secondary light source images may be in a defocused state.
According to this configuration, the angular distribution of the illumination light emitted from the second lens can be made broader, and an illuminating device that can be applied to a projector in which speckle is difficult to be visually recognized can be realized.

A projector according to an aspect of the present invention includes an illumination device that irradiates illumination light, a light modulation device that modulates the illumination light to generate image light, and a projection optical system that projects the image light. The illumination device includes the illumination device according to one aspect of the present invention.
Since the projector according to one aspect of the present invention includes the illumination device according to one aspect of the present invention, it is possible to realize a projector in which speckle is difficult to be visually recognized.

1 is a schematic configuration diagram of a projector according to a first embodiment of the invention. It is a schematic block diagram of the illuminating device of 1st Embodiment. It is a perspective view of a declination prism array. In the illuminating device of 1st Embodiment, it is a figure which respectively shows (A) several secondary light source image in a 2nd lens array, and (B) several secondary light source image after a polarizing beam splitter passage. In the illumination device of the comparative example, (A) a plurality of secondary light source images in the second lens array, and (B) a plurality of secondary light source images after passing through the polarization beam splitter, respectively. In the illuminating device of 1st Embodiment, it is a figure which respectively shows the simulation result of (A) several secondary light source image in a 2nd lens array, and (B) intensity distribution of several secondary light source image. In the illuminating device of a comparative example, it is a figure which respectively shows the simulation result of (A) several secondary light source image in a 2nd lens array, and (B) intensity distribution of several secondary light source image. It is a schematic block diagram of the illuminating device of 2nd Embodiment.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
In the present embodiment, an example of a projector using an illumination device including a plurality of laser light sources is shown.
FIG. 1 is a schematic configuration diagram illustrating the projector according to the first embodiment.
In the following drawings, in order to make each component easy to see, the scale of the size may be varied depending on the component.

As shown in FIG. 1, the projector 100 includes a red light illumination device 101R, a green light illumination device 101G, a blue light illumination device 101B, a red light liquid crystal light valve 102R, and a green light liquid crystal light valve. 102G, a blue light liquid crystal light valve 102B, a color composition element 103, and a projection optical system 104 are provided.
Each of the red light illumination device 101R, the green light illumination device 101G, and the blue light illumination device 101B of the present embodiment corresponds to the illumination device in the claims. Each of the red light liquid crystal light valve 102R, the green light liquid crystal light valve 102G, and the blue light liquid crystal light valve 102B of the present embodiment corresponds to the light modulation device in the claims.

The projector 100 generally operates as follows.
The red laser light emitted from the red light illumination device 101R enters the red light liquid crystal light valve 102R and is modulated. Similarly, the green laser light emitted from the green light illumination device 101G enters the green light liquid crystal light valve 102G and is modulated. The blue laser light emitted from the blue light source device 101B enters the blue light liquid crystal light valve 102B and is modulated. The red light modulated by the red light liquid crystal light valve 102R, the green light modulated by the green light liquid crystal light valve 102G, and the blue light modulated by the blue light liquid crystal light valve 102B are incident on the color composition element 103. And synthesized. The light synthesized by the color synthesizing element 103 is emitted as image light and enlarged and projected onto the screen 6 by the projection optical system 104. In this way, a full-color projection image is displayed.

Hereinafter, each component of the projector 100 will be described.
The red light illuminating device 101R, the green light illuminating device 101G, and the blue light illuminating device 101B differ only in the color of the emitted light, and have the same device configuration. As an example, a laser light source for red light emits light in a wavelength region of approximately 585 nm to 720 nm. The laser light source for green light emits light having a wavelength range of about 495 nm to 585 nm. The laser light source for blue light emits light having a wavelength range of approximately 380 nm to 495 nm.
Accordingly, only the green light illumination device 101G will be described below, and the description of the red light illumination device 101R and the blue light illumination device 101B will be omitted.

  As shown in FIG. 2, the green light illumination device 101G emits a plurality of green laser lights as illumination light. The green light illumination device 101G includes a light source device 10, a collimating optical system 11, a declination prism array 12, a diffuser plate 13, an integrator optical system 14, a superimposing lens 16, and a field lens 17. Yes. The integrator optical system 14 includes a first lens array 24 and a second lens array 25. A polarization conversion element 15 is provided in the optical path between the second lens array 25 and the superimposing lens 16.

The light source device 10 includes a plurality of laser light sources 19 that emit green light. The plurality of laser light sources 19 are two-dimensionally arranged. In FIG. 2, only four laser light sources 19 are illustrated, but the plurality of laser light sources 19 is an array of a plurality of rows and a plurality of columns (for example, 4 rows and 4 columns) as a whole in a plane perpendicular to the illumination optical axis AX. Are arranged in a shape. The laser light source 19 of this embodiment corresponds to the solid light source in the claims.
The illumination optical axis AX is defined as a central axis of a light beam when a bundle of a plurality of light beams emitted from the illumination device 101G is regarded as one light beam.

  The collimating optical system 11 is provided on the light emission side of the light source device 10, and light from the light source device 10 enters the collimating optical system 11. The collimating optical system 11 includes a plurality of collimating lenses 20 arranged in an array. Each of the plurality of collimating lenses 20 is disposed corresponding to each of the plurality of laser light sources 19. That is, the plurality of collimating lenses 20 are arranged in an array of a plurality of rows and a plurality of columns (for example, 4 rows and 4 columns) as a whole. Laser light emitted from each of the laser light sources 19 is approximately collimated by the action of the collimating lens 16. Instead of the configuration of the collimating optical system 11 described above, for example, a collimating optical system in which a plurality of cylindrical lenses arranged in the row direction and a plurality of cylindrical lenses arranged in the column direction may be used. .

The declination prism array 12 is provided in the optical path between the collimating optical system 11 and the second lens array 25. In particular, in the case of this embodiment, the deflection prism array 12 is provided in the optical path between the collimating optical system 11 and the diffusion plate 13. The declination prism array 12 generates a plurality of light fluxes having different traveling directions from incident light so that a plurality of secondary light source images are formed in the second lens array. In the present embodiment, the declination prism array 12 generates four types of light beams having different traveling directions from incident light.
The declination prism array 12 of the present embodiment corresponds to the light deflection element in the claims.

  As shown in FIG. 3, the declination prism array 12 has a rectangular shape when viewed from the direction of the illumination optical axis AX. The deflection prism array 12 includes a plurality of deflection prisms 22. The plurality of declination prisms 22 are arranged in an array of a plurality of rows and a plurality of columns as a whole. FIG. 3 is an enlarged view of the deflection prism 22 for 2 rows and 2 columns extracted from the deflection prism array 12. The entire deflection prism array 12 has a configuration in which a plurality of unit units each including the four deflection prisms shown in FIG. 3 are arranged. The inclination directions of the inclined surfaces 22c of the four declination prisms 22 are different from each other. The size of the declination prism 22 is desirably set to such a size that light emitted from one laser light source 19 is incident on at least two sets of unit units.

  The light transmission direction in the declination prism array 12 is defined as a z-axis direction, and two axes orthogonal to each other in a plane perpendicular to the z-axis are defined as an x-axis and a y-axis. In FIG. 3, the first declination prism 22A is inclined in the positive direction of the y-axis indicated by the arrow A1. The second declination prism 22B is inclined in the negative y-axis direction indicated by the arrow A2. The third declination prism 22C is inclined in the positive x-axis direction indicated by the arrow A3. The fourth declination prism 22D is inclined in the negative x-axis direction indicated by the arrow A4. Thereby, the light incident on the declination prism array 12 is divided into four types of light beams having different traveling directions and emitted. If the angle between the principal ray of light emitted from one deflection prism 22 and the illumination optical axis AX is defined as the deflection angle, the deflection angles of the light by the four deflection prisms 22 of this embodiment are Is about 5 °.

  The diffusion plate 13 diffuses the light emitted from the declination prism array 12 to a predetermined diffusion angle. In the case of this embodiment, the diffusion angle is about 4 ° or less in full width at half maximum. The diffuser plate 13 includes, for example, polished glass, a holographic diffuser, a surface of a transparent substrate that has been blasted to form irregularities, a scattering material such as beads is dispersed inside the transparent substrate, and light is scattered by the scattering material. A well-known diffuser plate such as a scattering member can be used. In the present embodiment, the diffusing plate 13 is provided in the optical path between the deflection prism array 12 and the first lens array 24. Instead of this arrangement, the collimating optical system 11 and the deflection prism are used. It may be provided in the optical path between the array 12.

  The integrator optical system 14 includes a first lens array 24 and a second lens array 25. The first lens array 24 has a configuration in which a plurality of first lenses 26 are arranged in a matrix of a plurality of rows and a plurality of columns in a plane orthogonal to the illumination optical axis AX. The first lens array 24 functions as a light beam splitting element that splits the light emitted from the diffusion plate 13 into a plurality of partial light beams. Although not illustrated, the outer shape of the first lens 26 is substantially similar to the outer shape of the image forming area of the liquid crystal light valve 102G.

  Similar to the first lens array 24, the second lens array 25 has a configuration in which a plurality of second lenses 27 are arranged in a matrix of a plurality of rows and a plurality of columns in a plane orthogonal to the illumination optical axis AX. . The second lens array 25 has a function of forming an image of the first lens 26 of the first lens array 24 in the vicinity of the image forming region of the liquid crystal light valve 102G together with the superimposing lens 16 at the subsequent stage. Since the laser light source 19 and the second lens array 25 are in a conjugate relationship, a secondary light source image is formed on the second lens array 25.

  The polarization conversion element 15 aligns the polarization direction of the light emitted from the integrator optical system 14. The polarization conversion element 15 is composed of a polarization beam splitter in which a polarization separation film and a phase difference plate are combined. In particular, the polarization conversion element 15 has a function of converting non-polarized incident light into predetermined linearly polarized light. The light emitted from the polarization conversion element 15 enters the superimposing lens 16. If the light emitted from the integrator optical system 14 is linearly polarized light, the polarization conversion element 15 is not necessarily provided.

A superimposing lens 16 and a field lens 17 are provided on the optical path between the polarization conversion element 15 and the liquid crystal light valve 102G. The superimposing lens 16 and the field lens 17 superimpose a plurality of light beams emitted from the second lens array 25 on the liquid crystal light valve 102G that is an illuminated area. A plurality of laser beams emitted from the second lens array 25 are incident on the liquid crystal light valve 102G via the superimposing lens 16 and the field lens 17. The plurality of light beams are superimposed on the liquid crystal light valve 102G by the superimposing lens 16 and the field lens 17. Thereby, the intensity distribution of the light that illuminates the liquid crystal light valve 102G is made uniform, and the axial symmetry about the illumination optical axis AX is enhanced.
The superimposing lens 16 and the field lens 17 of the present embodiment correspond to the optical elements in the claims.

  Although not shown, the green light liquid crystal light valve 102G includes a liquid crystal panel in which a liquid crystal layer is sandwiched between a pair of glass substrates, a light incident side polarizing plate disposed on the light incident side of the liquid crystal panel, and a liquid crystal A light emission side polarizing plate disposed on the light emission side of the panel. The mode of the liquid crystal layer is not particularly limited, such as a TN mode, a VA mode, and a transverse electric field mode. The liquid crystal light valve for red light and the liquid crystal light valve for blue light have the same configuration.

  As shown in FIG. 1, the color synthesizing element 103 includes a cross dichroic prism or the like. The cross dichroic prism has a structure in which four triangular prisms are bonded to each other. The surface to be bonded in the triangular prism is the inner surface of the cross dichroic prism. On the inner surface of the cross dichroic prism, a dichroic surface that reflects red light and transmits green light and a dichroic surface that reflects blue light and transmits green light are orthogonal to each other. The green light incident on the cross dichroic prism passes through the dichroic surface and is emitted as it is. Red light and blue light incident on the cross dichroic prism are selectively reflected by the dichroic surface and emitted in the same direction as the emission direction of the green light. In this way, the three color lights are superimposed and synthesized, and the synthesized color lights are emitted toward the projection optical system 104.

  The projection optical system 104 is configured by a plurality of lenses, for example. The projection optical system 104 projects the image light emitted from the color synthesizing element 103 onto the screen SCR that is a projection surface.

  In the case of the illumination device of the comparative example in which the declination prism array is not provided, as shown in FIG. 5A, each of the plurality of second lenses 127 constituting the second lens array 125 has one piece. A secondary light source image W is formed. Further, after the light passes through the polarization conversion element 115, the number of the secondary light source images W is doubled in the polarization separation direction by the action of the polarization separation film, as shown in FIG. 5B.

  On the other hand, in the case of the illumination device according to the present embodiment, as described above, four types of split light beams having different traveling directions are generated by the action of the declination prism array 12. Further, the deflection angles of the four types of split light beams are as small as about 4 ° or less. As a result, as shown in FIG. 4A, four secondary light source images W that partially overlap each other are formed on each of the plurality of second lenses 27 constituting the second lens array 25. The After the light passes through the polarization conversion element 15, the secondary light source image W is as shown in FIG. In particular, since the illumination device includes the diffusion plate 13, the individual secondary light source images W overlap each other in a slightly blurred state.

  6A, 6B, 7A, and 7B are diagrams showing the results of simulation of the intensity distribution of the secondary light source image on the second lens array performed by the present inventors. is there. FIGS. 6A and 6B show the results of the illumination device of this embodiment, and FIGS. 7A and 7B show the results of the illumination device of the comparative example having no declination prism array. 6A and 7A show the secondary light source image itself, and FIGS. 6B and 7B show the intensity distribution of the secondary light source image. 6B and 7B, the solid line indicates the intensity distribution along the x-axis direction, and the broken line indicates the intensity distribution along the y-axis direction.

  As shown in FIGS. 7A and 7B, in the case of the comparative example, the intensity distribution of the secondary light source image W has one peak. However, as shown in FIGS. In the case of the embodiment, it has four peaks. If the peak intensity in the comparative example is 1, the maximum peak intensity in this embodiment is about 0.7. Thus, in the present embodiment, the intensity distribution of the secondary light source image W is widened and the maximum value of the peak intensity is also reduced as compared with the comparative example. The intensity distribution in the present embodiment is closer to a so-called top hat shape than the intensity distribution of the comparative example. An increase in the intensity distribution of the secondary light source image W means an increase in the angular distribution of the light that illuminates the liquid crystal light valve.

  As described above, in the present embodiment, the angular distribution of the illumination light emitted from the second lens array 25 is wider than when the declination prism array 12 is not present. As a result, it is possible to realize a projector in which speckles are hardly visible. Further, the intensity distribution of the secondary light source image W shown in FIG. 4A is adjusted by changing the deflection angle of light by each deflection prism 22 of the deflection prism array 12 and the diffusion angle of the diffusion plate 13. be able to. Thereby, the speckle reduction effect can be adjusted.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIG.
In the present embodiment, an example of a projector using an illumination device including a plurality of laser light sources is shown.
FIG. 8 is a schematic configuration diagram illustrating the illumination device according to the second embodiment.
In FIG. 8, the same components as those in FIG. 2 used in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the illuminating device 101G of the first embodiment, the laser light source 19 is disposed at the focal position of the collimating lens 20, and the light emitted from the collimating lens 20 is substantially parallel light. On the other hand, as shown in FIG. 8, in the illumination device 201 </ b> G of the second embodiment, the laser light source 19 is arranged at a position shifted from the focal point of the collimating lens 20. Therefore, the light emitted from the collimating lens 20 is not completely parallel light. Moreover, the illuminating device 201G of the second embodiment does not include the diffusion plate 13. Other configurations are the same as those of the first embodiment.

  Also in the illumination device 201G of the second embodiment, as in the first embodiment, four secondary light source images W that partially overlap each other are formed on the second lenses 27 that constitute the second lens array 25. Is done. At this time, since the laser light source 19 is disposed at a position shifted from the focus of the collimating lens 20, the individual secondary light source images W are defocused and overlapped. As described above, the fact that the position of the laser light source 19 is deviated from the focal point of the collimating lens 20 has substantially the same effect as the diffusion plate 13 of the first embodiment. That is, since the position of the laser light source 19 is deviated from the focus of the collimating lens 20, the intensity distribution of the secondary light source image W in the second lens 27 becomes a shape closer to the top hat shape.

  Also in the present embodiment, the same effect as in the first embodiment that a projector in which speckles are difficult to visually recognize can be realized.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, an example has been shown in which the deflection prism array includes four types of deflection prisms with different inclinations of the inclined surfaces, and generates four types of light beams with different traveling directions. The deflection angle prism array may include at least two types of deflection angle prisms having different inclinations of the inclined surfaces, and generate at least two types of light beams having different traveling directions.

In the above embodiment, an example in which the light modulation device is a liquid crystal light valve has been described. However, a digital micromirror device (DMD) may be used as the light modulation device.
In addition, the number, arrangement, and the like of various components of the projector disclosed in the above embodiment can be changed as appropriate.

  DESCRIPTION OF SYMBOLS 10 ... Light source device, 11 ... Collimating optical system, 12 ... Deflection prism array (light deflecting element), 13 ... Diffusing plate, 16 ... Superimposing lens (optical element), 17 ... Field lens (optical element), 26 ... 1st 27 ... second lens, 100 ... projector, 101R, 101G, 101B ... illumination device, 102R, 102G, 102B ... liquid crystal light valve (light modulation device), 104 ... projection optical system.

Claims (5)

A light source device comprising at least one solid-state light source;
A collimating optical system into which light from the light source device is incident;
A first lens on which light from the collimating optical system is incident;
A second lens on which light from the first lens is incident;
An optical element for guiding light from the second lens to an illuminated area;
Provided in a light path between the collimating optical system and the second lens, a plurality of light beams having different traveling directions are incident on the second lens so that a plurality of secondary light source images are formed in the second lens. and an optical deflection element for generating from
The illumination device, wherein the plurality of secondary light source images are in a defocused state .   The illumination device according to claim 1, wherein the light deflection element is a deflection prism array.   The illumination device according to claim 1, wherein the light deflection element is provided in an optical path between the collimating optical system and the first lens.   The illumination device according to any one of claims 1 to 3, further comprising a diffusion plate provided in an optical path between the collimating optical system and the first lens. An illumination device that emits illumination light;
A light modulator that modulates the illumination light to generate image light;
A projection optical system for projecting the image light,
The projector provided with the illuminating device as described in any one of Claim 1- Claim 4 as said illuminating device.