ILLUMINATOR AND PROJECTOR

An illuminator includes a light source apparatus and a homogenizing apparatus. The homogenizing apparatus includes a first lens array in which a plurality of first lenses divide light incident on the first leas array into a plurality of sub-light fluxes and a second lens array in which a plurality of second lenses superimpose the plurality of sub-light fluxes on one another in the illuminated area. The light source apparatus includes a solid-state light source, a wavelength conversion element that converts the wavelength of light emitted from the solid-state light source, and an anisotropic diffusion element that is disposed between the solid-state light source and the wavelength conversion element and changes the shape of the emitted light to a shape according to the shape of an effective area of each of the plurality of second lenses.

BACKGROUND

1. Technical Field

The present invention relates to an illuminator and a projector.

2. Related Art

There has been a known projector of related art including an illuminator including a solid-state light source that emits excitation light and a wavelength conversion element that emits fluorescence when excited by the excitation light (see JP-A-2015-106130, for example). Specifically, the projector described in JP-A-2015-106130 includes an illuminator including an array light source, a collimator system, an afocal system, a first retardation plate, a prism, a light emitting element (wavelength conversion element), a second retardation plate, a diffusive reflection element, an optical integration system, a polarization conversion element, and a superimposing system.

The array light source has a configuration in which a plurality of semiconductor lasers, each of which is a solid-state light source, are arranged in an array and emits S-polarized blue light, which is a laser beam. The S-polarized blue light is converted by the collimator system into a parallelized light flux, and the diameter of the light flux is adjusted by the afocal system. The polarization axis of the blue light is rotated when the blue light passes through the first retardation plate, which is a half-wave plate, and part of the blue light, which is S-polarized light, is converted into P-polarized light.

Out of the S-polarized light component and the P-polarized light component contained in the blue light described above, the S-polarized light component is reflected off a polarization separation element of the prism, and the P-polarized light component passes through the polarization separation element.

The reflected S-polarized light component is incident as excitation light on a phosphor layer of the light emitting element, whereby yellow fluorescence is produced. The fluorescence is non-polarized light having polarization directions that are not aligned with one another, passes through the polarization separation element with the non-polarized state maintained, and is incident on the optical integration system.

On the other hand, the P-polarized light component contained in the blue light and having passed through the polarization separation element passes through the second retardation plate and diffusively reflected off the diffusive reflection element. The blue light is incident again on the second retardation plate, which converts the blue light into the S-polarized light component, which is reflected off the polarization separation element and incident on the optical integration system.

The optical integration system includes a first lens array having a plurality of first lenses and a second lens array having a plurality of second lenses corresponding to the plurality of first lenses and divides illumination light containing the blue light and fluorescence described above into a plurality of sub-light fluxes, and the optical integration system along with the superimposing system superimposes the plurality of sub-light fluxes on one another in each light modulator, which is an illuminated area. The polarization conversion element is disposed between the optical integration system and the superimposing system and aligns the polarization directions of the sub-light fluxes with one another.

Color light fluxes (image light fluxes) modulated by the light modulators are combined with one another by a combining system, and the combined light is then enlarged and projected by a projection system on a screen.

The polarization conversion element has a configuration in which a polarization separation layer (polarization separation film) and a reflection layer (mirror) are alternately arranged along the direction orthogonal to the optical axis and retardation layers are disposed in the optical paths of the light fluxes having passed through the polarization separation layers or the light reflected off the polarization separation layers and then further reflected off the reflection layers. The focal position of each of the second lenses of the second lens array is so set that the sub-light fluxes are incident on the polarization separation layers. It is noted that there is a known configuration in which a light blocker that covers each of the reflection layers is provided on the light incident side in the polarization conversion element.

A semiconductor laser is characterized in that it emits light the shape of which in a plane orthogonal to the optical axis has an aspect ratio representing a horizontally elongated shape (roughly rectangular shape or roughly elliptical shape). The illumination light described above and produced by the light emitted from the array light source in which semiconductor lasers are arranged in an array also has a shape having the same aspect ratio, and the divided sub-light fluxes from the first lenses described above also have a shape having an aspect ratio representing a horizontally elongated shape on the second lenses.

In a case where each of the thus formed sub-light fluxes is incident on roughly the entire light incident surface of the corresponding second lens, part of the sub-light flux is incident on the second lens, specifically, a portion thereof according to the corresponding reflection layer of the polarization conversion element (in the case where the light blockers are provided, incident on a portion according to the corresponding light blocker). Since the light incident on the portion described above is not used in image formation performed by the light modulators, light loss occurs.

To avoid the light loss, it is conceivable to shorten the distance between the first lens array and the second lens array so that each of the sub-light fluxes from the first lenses is incident on the corresponding second lens, specifically, a roughly square effective area thereat that allows roughly the entire sub-light flux having exited out of the second lens is incident on the corresponding polarization separation layer.

In this case, it is necessary to shorten the distance between the superimposing system and the light modulators so that the sub-light fluxes are appropriately superimposed on one another. However, since the sub-light fluxes are caused to converge by the superimposing system and the convergent sub-light fluxes are incident on the light modulators, the angle of incidence of the light fluxes incident on the light modulators increases. As a result, the angle of emergence of the light that exits out of the light modulators increases, and the amount of image light that does not exit out of the projection optical apparatus increases, undesirably resulting in a decrease in brightness of a projected image.

To solve the problem, it is conceivable to use a homogenizer system having a pair of multi-lens arrays disposed between the first retardation plate and the prism to adjust the shape of the light incident on the light emitting element (wavelength conversion element) in such a way that roughly the entire sub-light fluxes are incident on the effective area described above with no decrease in the distance between the first lens array and the second lens array.

However, since the homogenizer system includes the pair of multi-lens arrays so arranged as to be separate from each other, the configuration of the illuminator undesirably tends to be complicated and hence causes an increase in manufacturing cost.

SUMMARY

An advantage of some aspects of the invention is to provide an illuminator and a projector capable of improving light use efficiency with the configurations of the illuminator and the projector simplified.

An illuminator according to a first aspect of the invention includes a light source apparatus and a homogenizing apparatus that homogenizes illuminance of light emitted from the light source apparatus in a plane orthogonal to a central axis of the light. The homogenizing apparatus includes a first lens array in which a plurality of first lenses each of which has a shape roughly similar to a shape of an illuminated area are arranged in the orthogonal plane and the plurality of first lenses divide light incident on the first lens array into a plurality of sub-light fluxes and a second lens array in which a plurality of second lenses each of which has a shape roughly similar to the shape of the illuminated area are arranged in the orthogonal plane and the plurality of second lenses superimpose the plurality of sub-light fluxes on one another in the illuminated area. The light source apparatus includes a solid-state light source, a wavelength conversion element that converts a wavelength of light emitted from the solid-state light source, and an anisotropic diffusion element that is disposed between the solid-state light source and the wavelength conversion element and changes a shape of the emitted light to a shape according to a shape of an effective area of each of the plurality of second lenses.

The anisotropic diffusion element is an element capable of adjusting the degree of diffusion of light in at least one of two axes orthogonal to each other in a plane orthogonal to the optical axis to adjust the shape of a light flux that exits out of the anisotropic diffusion element, and examples of the anisotropic diffusion element also include an element capable of individually adjusting the degree of diffusion of light in both the two axes orthogonal to each other. Specific examples of the anisotropic diffusion element may include a hologram, multiple lenses formed of a plurality of lenslets arranged in a plane orthogonal to the optical axis, and a configuration having a roughened surface roughened differently in the two axes orthogonal to each other described above. Among them, the lenslets employed in the multiple lenses can, for example, be lenslets each having the shape of a cylindrical lens.

According to the first aspect described above, the anisotropic diffusion element can change the shape of the light emitted from the solid-state light source and incident on the homogenizing apparatus via the wavelength conversion element to a shape according to the shape of the effective area of each of the second lenses. Therefore, even when the solid-state light source emits light having a shape having an aspect ratio representing a horizontally elongated shape in a plane orthogonal to the optical axis, light having a shape according to the shape of the effective area, that is, light having a shape similar to the shape of the effective area is allowed to enter the first lens array. As a result, the sub-light fluxes produced by the first lenses become light fluxes each having a shape similar to the shape of the effective area, whereby roughly the entire sub-light fluxes are each allowed to enter roughly the entire surface of the effective area without decrease in the distance between the first lens array and the second lens array.

In a case where the illuminator is employed in a projector, and the illuminated area is set in a light modulator of the projector, an increase in the angle of emergence of light having exited out of the light modulator toward a projection optical apparatus can be suppressed, whereby the amount of light that does not enter the projection optical apparatus can be reduced, and a decrease in brightness of a projected image can therefore he suppressed. The light emitted from the light source apparatus can therefore he used with improved efficiency.

Further, in the first aspect, described above, since the anisotropic diffusion element can provide the advantageous effects described above, it is not necessary to employ a homogenizer system having a pair of multi-lens arrays. The configuration of the illuminator can therefore be simplified, whereby the manufacturing cost can be reduced.

In the first aspect described above, it is preferable that the light source apparatus further includes an optical element that causes the light emitted from the solid-state light source to converge and causes the convergent light to enter the anisotropic diffusion element.

The optical element described above can, for example, be a combination of a convex lens and a concave lens that form an afocal system.

According to the configuration described above, since the optical element described above can reduce the light flux diameter of the light incident on the anisotropic diffusion element, the size of the anisotropic diffusion element can be reduced, and the size of each optical element located in the optical path of the light having exited out of the anisotropic diffusion element can be reduced. The size of the illuminator can therefore be reduced.

In the first aspect described above, it is preferable that the homogenizing apparatus includes a polarization conversion element that aligns polarization directions of the plurality of sub-light fluxes with one another, the polarization conversion element has a plurality of polarization separation layers that incline with respect to a first direction that is a direction in which the plurality of sub-light fluxes travel, a plurality of reflection layers that are arranged alternately with the plurality of polarization separation layers along a second direction orthogonal to the first direction, incline with respect to the first direction, and reflect light fluxes reflected off the plurality of polarization separation layers in parallel to a direction in which light fluxes having passed through the plurality of polarization separation layers travel, and a plurality of retardation layers that are provided in optical paths of the light fluxes having passed through the plurality of polarization separation layers or optical paths of the light fluxes having been reflected off the plurality of reflection layers and convert polarization directions of light fluxes incident on the retardation layers, and when the second lens array is viewed from a side facing the first lens array, the effective area is an area that does not overlap with the plurality of reflection layers in each of the plurality of second lenses.

In a case where the polarization conversion element has a plurality of light blocking layers located on the side opposite the first direction side and in the positions corresponding to the plurality of reflection layers, the effective area described above can be alternately referred to as an area in each of the plurality of second lenses that does not overlap with the plurality of reflection layers when the second lens array is viewed from the side facing the first lens array.

According to the configuration described above, the polarization conversion element allows the illuminator to output light having polarization directions aligned with one another, whereby the versatility of the illuminator can be improved.

Since the effective area of each of the second lenses, in accordance with which the anisotropic diffusion element adjusts the shape of light incident thereon, is set as described above, each of sub-light flux is allowed to enter roughly the entire surface of the effective area, whereby roughly the entire sub-light flux having exited out of the second lens are allowed to enter the polarization separation layer without incidence of the sub-light flux on the reflection layer or the light blocking layers. Therefore, light loss can be suppressed, whereby the light use efficiency can be reliably improved.

A projector according to a second aspect of the invention includes the illuminator described above, a light modulator that modulates light emitted from the illuminator, and a projection optical apparatus that projects the modulated light from the light, modulator, and the illuminated area is a modulation area where the light modulator modulates light incident thereon.

The second aspect described above can provide the same advantageous effects as those provided by the illuminator according to the first aspect described above. Since the illuminated area is the modulation areas of the light modulator, the modulation area can be illuminated with light having a uniform illuminance distribution. Brightness unevenness in a projected image can therefore be suppressed. Further, since it is not necessary to shorten the distance between the first lens array and the second lens array, an increase in the angle of emergence of the light that exits out of the light modulator (image light) toward the projection optical apparatus is suppressed. Therefore, a decrease in brightness of a projected image can be suppressed, and the use efficiency of the light from the light source apparatus is improved, whereby the brightness of the projected image can be increased.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

An embodiment of the invention will be described below with reference to the drawings.

Overall Configuration of Projector

FIG. 1is a diagrammatic view showing the configuration of a projector1according to the present embodiment.

The projector1according to the present embodiment is a display apparatus that modulates light emitted from an illuminator31provided in the projector1to form an image according to image information and enlarges and projects the image on a screen SCI or any other projection surface.

The projector1, which will be described later in detail, is partly characterized by a function of causing each sub-light flux to enter roughly the entire surface of an effective area AR of a second lens array52, which forms a homogenizing apparatus5, by adjusting the shape of the light fluxes incident on the homogenizing apparatus5in order to simplify the configuration with the use efficiency of light emitted from a light source increased.

The thus configured projector1includes an exterior enclosure2and an optical unit3, which is accommodated in the exterior enclosure2, as shown inFIG. 1. Although not shown, the projector1further includes a controller that controls the projector1, a cooler that cools components to be cooled, such as optical parts, and power source that supplies electronic parts with electric power.

Configuration of Optical Unit

The optical unit3includes an illuminator31, a color separation apparatus32, parallelizing lenses33, light modulators34, a light combining apparatus35, and a projection optical apparatus36.

Among them, the illuminator31outputs illumination light WL. The configuration of the illuminator31will be described later in detail.

The color separation apparatus32separates the illumination light WL incident from the illuminator31into red light LR, green light LG, and blue light LB. The color separation apparatus32includes dichroic mirrors321and322, reflection mirrors323,324, and325, and relay lenses326and327.

Among them, the dichroic mirror321separates the red light LR and the other color light fluxes (green light LG and blue light LB), which form the illumination light WL, from each other. The separated red light LR is reflected off the reflection mirror323and guided to a parallelizing lens33(33R). The separated other color light fluxes are incident on the dichroic mirror322.

The dichroic mirror322separates the green light LG and the blue light LB, which form the other color light fluxes, from each other. The separated green light LG is guided to a parallelizing lens33(33G). The separated blue light LB travels via the relay lens326, the reflection mirror324, the relay lens337, and the reflection mirror325and is guided to a parallelizing lens33(33B).

Each of the parallelizing lenses33(reference characters33R,33G, and33B denote parallelizing lenses for red light LR, green light LG, and blue light LB, respectively) parallelizes the light incident thereon.

The light modulators34(reference characters34R,34G, and34B denote light modulators for red light LR, green light LG, and blue light LB, respectively) modulate the color light fluxes LR, LG, and LB incident thereon to form image light fluxes according to image information. Each of the light modulators34includes a liquid crystal panel that modulates a color light flux incident thereon and a pair of polarizers disposed on the light incident side and the light exiting side of the light modulators34R,34G, and34B.

In each of the light modulators34, a modulation area341, which is an image formation area that modulates a color light flux incident thereon to form an image, is a modulation area of the liquid crystal panel. The modulator area341is an area having an aspect ratio (ratio of length of long side to length of short side) representing a horizontally elongated shape, and the aspect ratio is 16:9 in the present embodiment. The aspect ratio of the modulation area341is not limited to the value described above and may be 4:3.

The light combining apparatus35combines the image light fluxes incident from light modulators34R,34G, and34B (image light fluxes formed by color light fluxes LR, LG, and LB described above). The light combining apparatus35can be formed, for example, of a cross dichroic prism.

The projection optical apparatus36projects the image light fluxes combined by the light combining apparatus35on the screen SC1or any other projection surface. As the projection optical apparatus, although not shown, a lens unit in which a plurality of lenses are arranged in a lens barrel can be employed.

The thus configured optical unit3projects an enlarged image on the screen SC1.

Configuration of Illuminator

FIG. 2is a diagrammatic view showing the configuration of the illuminator31.

The illuminator31outputs the illumination light WL toward the color separation apparatus32, as described above. The illuminator31includes a light source apparatus4and a homogenizing apparatus5, as shown inFIG. 2.

Configuration of Light Source Apparatus

The light source apparatus4outputs a light flux to the homogenizing apparatus5. The light source apparatus4includes a light source section41, an afocal system42, a first retardation plate43, an anisotropic diffusion element44, a polarization separation apparatus45, a second retardation plate46, a first pickup lens47, a diffusive reflection element48, a second pickup lens49, and a wavelength conversion apparatus4A.

Among them, the light source section41, the afocal system42, the first retardation plate43, the anisotropic diffusion element44, the polarization separation apparatus45, the second retardation plate46, the first pickup lens47, and the diffusive inflection element48are arranged along an illumination optical axis Ax1. The polarization separation apparatus45is disposed at a point where the illumination optical axis Ax1intersects an illumination optical axis Ax2, which is orthogonal to the illumination optical axis Ax1.

Configuration of Light Source Section

The light source, section41includes a plurality of solid-state light sources411, each of which is an LD (laser diode), and a plurality of parallelizing lenses412corresponding to the solid-state light sources411and outputs excitation light that is blue light toward the afocal system42. In the present embodiment, each of the solid-state light sources411emits excitation light the intensity of which peaks, for example, at a wavelength of 440 nm, but an LD that emits excitation light the intensity of which peaks at a wavelength, of 446 nm may be employed as each of the solid-state light sources411, or an LD that emits excitation light the intensity of which peaks at a wavelength of 440 nm and an LD that emits excitation light the intensity of which peaks at a wavelength of 446 nm may be mixed with each other. The excitation light emitted from each of the solid-state light sources411is parallelized by the parallelizing lens412and incident on the afocal system42. In the present embodiment, the excitation light emitted from each of the solid-state light sources411is S-polarized light.

Configuration of Afocal System

The afocal system42adjusts the light flux diameter of the excitation light incident from the light source section41. Specifically, the afocal system42is an optical element that causes the excitation light incident as parallelized light from the light source section41to converge so that the light flux diameter decreases, parallelizes the convergent light and outputs the parallelized light. The afocal system42includes lenses421and422, which are a convex lens and a concave lens, respectively, and the excitation light emitted from the light source section41is caused to converge by the afocal system42and incident on the first retardation plate43and then the anisotropic diffusion element44.

Configuration of First Retardation Plate

The first retardation plate43is a half-wave plate. The excitation light, which is S-polarized light emitted from the light source section41, passes through the first retardation plate43, which converts part of the S-polarized light into P-polarized light, whereby the excitation light becomes light formed of S-polarized light and P-polarized mixed with each other. Then excitation light having passed through the first retardation plate43is incident on the anisotropic diffusion element44.

Configuration of Anisotropic Diffusion Element

The anisotropic diffusion element44replaces the homogenizer system having a pair of multi-lens arrays described above. The anisotropic diffusion element44not only diffuses a light flux incident thereon at diffusion factors different from each other in two axes orthogonal to each other in a plane orthogonal to the optical axis (plane orthogonal to illumination optical axis Ax1) to homogenize the illuminance of the light flux that exits out of the anisotropic diffusion element44in the plane orthogonal to the optical axis but also adjusts the shape of the exiting light flux.

The thus functioning anisotropic diffusion element44can, for example, have a configuration having a hologram or can, for example, be multiple lenses formed of a plurality of lenslets arranged in a plane orthogonal to the optical axis or a plate-shaped body having a roughened surface roughened differently in the two axes orthogonal to each other described above. Among them, each of the lenslets employed in the multiple lenses can, for example, be a lenslet having the shape of a cylindrical lens.

The shape of the light flux incident on the anisotropic diffusion element44and the shape of the light flux that exits out of the anisotropic diffusion element44will be described later in detail.

Configuration of Polarization Separation Apparatus

The polarization separation apparatus45is a prism-shaped PBS (polarizing beam splitter), is formed by bonding prisms451and452, each of which is formed in a roughly triangular columnar shape, along surfaces thereof, and therefore has a roughly box-like shape as a whole. The interface between the prisms451and452is inclined by about 45° with respect to both the illumination optical axes Ax1and Ax2. In the polarization separation apparatus45, a polarization separation layer453having wavelength selectivity is formed along the interface of the prism451, which is located on the side facing the anisotropic diffusion element44(that is, the side facing the light source section41).

The polarization separation layer453is characterized in that it separates the S-polarized light and the P-polarized light contained in the excitation light from each other. The polarization separation layer453further has a function of transmitting fluorescence produced when the excitation light is incident on the wavelength conversion apparatus4A, which will be described later, irrespective of the polarization state of the fluorescence. That is, the polarization separation layer453has a wavelength selective polarization separation characteristic that affects light within a predetermined wavelength region in such a way that S-polarized light and P-polarized light are separated from each other but transmits light within another predetermined wavelength region without S-polarized light and P-polarized light separated from each other.

The thus configured polarization separation apparatus45, which receives the excitation light incident from the anisotropic diffusion element44, transmits P-polarized light toward the second retardation plate46along the illumination optical axis Ax1and reflects S-polarized light toward the second pickup lens49along the illumination optical axis Ax2.

Configurations of Second Retardation Plate, First Pickup Lens, and Diffusive Reflection Element

The second retardation plate46is a quarter-wave plate and rotates the polarization direction of the excitation light incident from the polarization separation apparatus45.

The first pickup lens47focuses the excitation light having passed through the second retardation plate46onto the diffusive reflection element48. The number of lenses that form the first pickup lens47is three in the present embodiment but can be any number.

The diffusive reflection element48diffusively reflects the excitation light incident thereon in the same manner the fluorescence is produced by and outputted from a wavelength conversion element4A1, which will be described later. The diffusive reflection element48can, for example, be a reflection member that causes light incident thereon to undergo Lambertian reflection.

The excitation light diffusively reflected off the thus configured diffusive reflection element48is incident again on the second retardation plate46via the first pickup lens47. In the process in which the excitation light passes through the second retardation plate46, the polarization direction of the excitation light is further rotated so that the excitation light is converted into S-polarized excitation light. The excitation light is then reflected off the polarization separation layer453of the polarization separation apparatus45, travels along the illumination optical axis Ax2, and is incident as blue light on the homogenizing apparatus5.

The second pickup lens49and the wavelength conversion apparatus4A are disposed in the illumination optical axis Ax2described above.

On the second pickup lens49is incident the S-polarized excitation light having passed through the anisotropic diffusion element44and having been reflected off the polarization separation layer453. The second pickup lens49focuses the excitation light onto the wavelength conversion element4A1. The number of lenses that form the second pickup lens49is three in the present embodiment but can be any number.

Configuration of Wavelength Conversion Apparatus

The wavelength conversion apparatus4A converts the excitation light incident thereon into fluorescence. The wavelength conversion apparatus4A includes the wavelength conversion element4A1and a rotating apparatus4A5.

Out of the two components, the rotating apparatus4A5is formed, for example, of a motor that rotates the wavelength conversion element4A1around the central axis thereof.

The wavelength conversion element4A1has a substrate4A2, and a phosphor layer4A3and a reflection layer4A4, which are located on an excitation light incident surface of the substrate42A.

The substrate4A2is formed in a roughly circular shape when viewed from the excitation light incident side. The substrate4A2can be made, for example, of a metal or ceramic material.

The phosphor layer4A3contains a phosphor that is excited by the excitation light incident thereon and emits fluorescence (fluorescence the intensity of which peaks at a wavelength within a wavelength range, for example, from 500 to 700 nm). Part of the fluorescence produced by the phosphor layer4A3exits toward the second pickup lens49, and another part of the fluorescence exits toward the reflection layer4A4.

The reflection layer4A4is disposed between the phosphor layer4A3and the substrate4A2and reflects the fluorescence incident from the phosphor layer4A3toward the second pickup lens49.

The fluorescence emitted from the thus configured wavelength conversion element4A1is non-polarized light. The fluorescence is incident on the polarization separation layer453of the polarization separation apparatus45via the second pickup lens49, passes through the polarization separation layer453along the illumination optical axis Ax2, and enters on the homogenizing apparatus5.

As described above, out of the two components of the excitation light incident on the polarization separation apparatus45via the anisotropic diffusion element44, the P-polarized light is diffused when it is incident on the diffusive reflection element48, passes through the second retardation plate46twice, is reflected off the polarization separation apparatus45, and enters as blue light the homogenizing apparatus5. On the other hand, the S-polarized light is converted in terms of wavelength into fluorescence (green light and red light) by the wavelength conversion apparatus4A, then passes through the polarization separation apparatus45, and enters the homogenizing apparatus5. That is, the blue light, the green light, and the red light axe combined with one another by the polarization separation apparatus45, and the resultant white illumination light WL enters the homogenizing apparatus5.

Configuration of Homogenizing Apparatus

The homogenizing apparatus5homogenizes the illuminance of the illumination light WL incident from the light source apparatus4in a plane orthogonal to the central axis of the illumination light WL (plane orthogonal to optical axis), specifically, homogenizes the illuminance distribution of the light flux in the modulation area341, which is an illuminated area in each of the light modulators34(34R,34G, and34B). The homogenizing apparatus5includes a first lens array51, a second lens array52, a polarization conversion element53, and a superimposing lens54.

Configurations of First Lens Array, Second Lens Array, and Superimposing Lens

The first lens array51has a configuration in which a plurality of first lenses511, each of which is a lenslet, are arranged in a matrix in a plane orthogonal to the optical axis, and the plurality of first lenses511divide the illumination light WL incident thereon into a plurality of sub-light fluxes. The lens surface of the first lens array51(imaginary surface formed of valleys located between the plurality of first lenses511and connected to each other) is conjugate with the modulation area341of each of the light modulator34via the optical parts. Therefore, the shape of each of the first lenses511is similar to the shape of the modulation area341, and each of the first lenses511is formed in a rectangular shape having an aspect ratio representing a horizontally elongated shape in the present embodiment, as in the case of the modulation area341.

The second lens array52has a configuration in which a plurality of second lenses521, each of which is a lenslet, are arranged in a matrix in a plane orthogonal to the optical axis, as in the case of the first lens array51, and each of the second lenses521is related to the corresponding first lens511in the 1:1 relationship. That is, on a second lens521is incident a sub-light flux having exited out of the corresponding first lens511. The second lenses521along with the superimposing lens54superimpose the plurality of divided sub-light fluxes from the first lenses511on one another in the modulation area341of each of the light modulators34. The shape of each of the second lenses521is similar to the shape of the corresponding first lens511.

Configuration of Polarization Conversion Element

FIG. 3is a cross-sectional view diagrammatically showing part of the polarization conversion element53.

The polarization conversion element53is disposed between the second lens array52and the super-imposing lens54and has a function of aligning the polarization directions of the plurality of sub-light fluxes incident on the polarization conversion element53. The polarization conversion element53has a light transmissive member531, retardation layers534, and light blockers535, as shown inFIG. 3.

The light transmissive member531has a configuration in which columnar bodies5311, each of which has a triangular or parallelogram cross-sectional shape, are bonded to each other and is formed in a roughly rectangular-plate-like shape as a whole. The columnar bodies5311are made of a light transmissive material that allows the sub-light fluxes described above to pass and is, for example, white glass. A polarization separation layer532or a reflection layer533is formed on a surface of each of the columnar bodies5311.

The polarization separation layer532and the reflection layer533incline by about 45° with respect to a direction Z (first direction), which is not only the direction in which the incident sub-light fluxes travel but also the direction along the illumination optical axis Ax2, and the polarization separation layer532and the reflection layer533are alternately arranged along a direction X (second direction), which is orthogonal to the direction Z.

Each of the polarization separation layer532and the reflection layer533, although not illustrated in detail, is formed in a rectangular shape having a widthwise direction that coincides with the direction X and a longitudinal direction that coincides with a direction Y, which is orthogonal to the direction X, in a plane orthogonal to the direction Z. Each of the divided sub-light fluxes from the first lens array51passes a light incident surface531A (light incident surface531A of light transmissive member531) according to the polarization separation layer532corresponding to the sub-light flux and impinges on the polarization separation layer532.

Each of the polarization separation layers532is a layer that transmits one of the P-polarized light and the S-polarized light incident thereon and reflects the other and is formed of a dielectric multilayer film.

Each of the reflection layer533reflects the polarized light reflected off the corresponding polarization separation layer532in the direction parallel to the direction in which the polarized light having passed through the polarization separation layer532travels and directed in the same orientation of the polarized light having passed through the polarization separation layer532.

The retardation layers534are provided on a light exiting surface531B of the light transmissive member531. In the present embodiment, the retardation layers534are disposed in the optical paths of the polarized light fluxes having passed through the polarization separation layers532and rotate the polarization direction of the light fluxes incident on the

retardation layers534by 90° to make the polarization direction of the incident polarized light fluxes coincide with the polarization direction of the polarized light fluxed reflected off the polarization separation layers532. The retardation layers534align the polarization directions of the light fluxes that exit out of the polarization conversion element53(polarization separation layers532) with one another.

The retardation layers534may be disposed in the optical paths of the polarized light fluxes reflected off the reflection layers533. That is, in the case where the retardation layers534are disposed in the optical paths of the light fluxes having passed through the polarization separation layers532and the polarization separation layers532are configured to transmit S-polarized light, the sub-light fluxes having exited out of the polarization conversion element53are P-polarized light fluxes, whereas the polarization separation layers532are configured to transmit P-polarized light, the sub-light fluxes having exited out of the polarization conversion element53are S-polarized light fluxes. Instead, in the case where the retardation layers534are disposed in the optical paths of the light reflected off the reflection layers533and the polarization separation layers532are configured to transmit S-polarized light, the sub-light fluxes having exited out of the polarization conversion element53are S-polarized light fluxes, whereas the polarization separation layers532are configured to transmit P-polarized light, the sub-light fluxes having exited out of the polarization conversion element53are P-polarized light fluxes. In any of the cases described above, the light having exited out of the polarization conversion element53is polarized light of one type.

The light blockers535are made, for example, of stainless, an aluminum alloy, or any other metal and located at a plurality of locations on the light incident side of the light transmissive member531. Specifically, the light blockers535are provided on the light incident side of the light transmissive member531and in positions corresponding to the reflection layers533. The thus provided light blockers535are so disposed that the sub-light fluxes having exited out of the second lenses521are incident only on the polarization separation layers532, and light that is likely to be directly incident on the reflection layers533is blocked by the light blockers535. Roughly the entire sub-light fluxes having exited out of the second lenses521are therefore incident on the light incident surface531A that is not covered with the light blockers535and then incident on the polarization separation layers532described above.

In a case where part of the light having exited out of the second lenses521does not greatly affect image formation even if the light is incident on the reflection layers533, the light blockers535may be omitted.

Effective Areas in Second Lenses

FIG. 4shows the positions of overlap areas RE in the second lens array52, which overlap with the light blockers535when the second lens array52is viewed from the light incident side (side facing first lens array51).FIG. 5is an enlarged view of the positional relationship between a second lens521and overlap areas RE. In other words,FIG. 5shows the relationship between the lens shape of each second lens521and an effective area AR. InFIGS. 4 and 5, only part of the second lenses521is labeled with the reference character in consideration of clarity.

The light blockers535described above are disposed in positions corresponding to the reflection layers533. Therefore, when the second lens array52is viewed from the light incident side, that is, from the side facing the first lens array51, part of each of the second lenses521(second lens521indicated by the two-dot chain line inFIG. 5) overlaps with light blockers535(or reflection layers533), as shown inFIGS. 4 and 5. In other words, part of a transmission area through which the light having exited out of a second lens521passes is blocked by light blockers535.

In the second lens array52, the overlap areas RE, which overlap with the light blockers535(or reflection layer533), are located in opposite end portions in the longitudinal direction of the horizontally elongated second lenses521having the aspect ratio described above, that is, in the direction X described above. In other words, in each of the second lenses521, a roughly square area other than the overlap areas RE is the effective area AR (effective area AR of second lens521), which allows the light incident on the second lens521to be reliably incident on the corresponding polarization separation layer532.

It is noted that the widthwise direction of the second lenses521is the direction Y described above.

Incident Light Shape Adjustment performed by Anisotropic Diffusion Element

FIG. 6shows the shape of excitation light BL in a plane orthogonal to the optical axis, which is incident on the anisotropic diffusion element44.

Light emitted from a typical LD is light having an aspect ratio representing a horizontally elongated shape, so is excitation light emitted from, each of the solid-state light sources411described above, which are formed of LDs. Since the light source section41superimposes the light fluxes emitted from the plurality of solid-state light sources411on one another before outputting them, excitation light BL having an aspect ratio representing a horizontally elongated shape is incident on the anisotropic diffusion element44, as indicated by the dotted light inFIG. 6.

In a case where no anisotropic diffusion element44is provided, the shape of the illumination light WL described above in a plane orthogonal to the optical axis, which is produced on the basis of the excitation light BL having the aspect ratio representing a horizontally elongated shape described above, is similar to the shape of the excitation light BL.

When the thus formed illumination light WL is incident on the first lens array51, the sub-light fluxes having exited out of the first lenses511are light fluxes each having the aspect ratio representing a horizontally elongated shape. In a case where the thus shaped sub-light flux is incident on an area PL indicated by the one-dot chain line in the second lens521indicated by the two-dot chain line inFIG. 5, when the sub-light flux passes through the second lens521and is incident on the polarization conversion element53, portions of the light on the opposite ends in the longitudinal direction are blocked by the light blockers535. Since the blocked light is not used in image formation performed by the light modulators34, the use efficiency of the light emitted from the light source section41decreases, undesirably resulting in a decrease in brightness of a projected image.

To solve the problem, it is conceivable to shorten the distance between the first lens array51and the second lens array52to allow the sub-light fluxes having the aspect ratio representing a horizontally elongated shape to enter the effective area AR described above, which is indicated by the dotted line inFIG. 5, with the aspect ratio maintained. In this case, since the sub-light flux is not blocked for the most part by the light blockers535, roughly the entire sub-light flux incident on the second lens521is allowed to enter the light incident surface531A described above and then the polarization separation layer532.

However, shortening the distance between the first lens array51and the second lens array52requires shortening the distance between the superimposing lens54and the light modulators34and superimposing the sub-light fluxes on one another in such a way that the sub-light fluxes converge onto the light modulators34. In this case, since light in the vicinity of the edge of each of the sub-light fluxes is incident on the light modulators34at a large angle of incidence, the modulated light fluxes (image light fluxes) outputted from the light modulators34undesirably exit at a large angle of emergence. In this case, the amount of light that does not enter the projection optical apparatus36tends to increase, undesirably resulting in a decrease in brightness of a projected image. That is, in this case as well, the problem of a decrease in the use efficiency of the light emitted from the light source section41occurs.

FIG. 7shows the shape of the excitation light BL in a plane orthogonal to the optical axis, which exits out of the anisotropic diffusion element44.

To solve the problems described above, in the present embodiment, the anisotropic diffusion element44adjusts the shape of the light that exits out of the anisotropic diffusion element44in such a way that the shape accords with the effective area AR. That is, the anisotropic diffusion element44diffuses the excitation light BL in such a way that the shape of the excitation light BL incident on each of the second lenses521is similar to the shape of the effective area AR. Specifically, the anisotropic diffusion element44so diffuses the excitation light BL as to be wider in the widthwise direction than in the longitudinal direction so that the longitudinal length dimension of the excitation light BL shown inFIG. 6is roughly equal to the widthwise length dimension thereof.

As a result, the excitation light BL has a roughly square shape, as indicated by the dotted line inFIG. 7, as in the effective area AR described above does (seeFIG. 5).

The anisotropic diffusion element44may instead diffuse the excitation light BL in the longitudinal direction as long as the shape of the diffused excitation light BL is roughly similar to the shape of the effective area AR, or the angle of diffusion performed on the excitation light BL that exits out of the anisotropic diffusion element44may be so adjusted that the diameter of the excitation light BL is reduced in the longitudinal direction.

Causing the excitation light BL to pass through the anisotropic diffusion element44and converting the shape of the excitation light BL into a shape according to the shape of the effective area AR as described above allows the shape of the illumination light WL to be similar to the shape of the effective area AR, as described above. Therefore, the shape of each of the sub-light fluxes produced by the division of the illumination light WL performed by the first lenses511of the first lens array51is similar to the shape of the effective area AR. Roughly the entirety of each of the sub-light fluxes is thus allowed to enter the entire surface of the effective area AR. The light fluxes having passed through the effective areas AR are superimposed via the polarization conversion element53on one another by the superimposing lens54on the modulation areas342, resulting in improvement in the use efficiency of the light emitted from the light source section41in image formation.

It is noted that the shape of the sub-light fluxes in the second lenses521differs in an exact sense from the shape of the sub-light fluxes in the polarization conversion element53. However, the shapes of the sub-light fluxes at the two locations can be considered as to be roughly the same as long as the second lens array52is located sufficiently close to the polarization conversion element53. Therefore, when the sub-light fluxes are incident on the entire surfaces of the effective areas AR of the second lenses521, roughly the entire sub-light fluxes are not blocked by the light blockers535but are allowed to enter the polarization conversion element53. The advantageous effect described above can therefore be reliably provided.

The projector1according to the present embodiment described above provides the following advantageous effects.

The anisotropic diffusion element44can change the shape of the light emitted from each of the solid-state light sources411, which are LDs, and incident on the homogenizing apparatus5via the wavelength conversion element4A1and the diffusive reflection element48to a shape according to the shape of the effective area AR of each of the second lenses521. Therefore, even when each of the solid-state light sources411emits light having a shape having the aspect ratio described above representing a horizontally elongated shape, light having a shape similar to the shape of the effective area AR is allowed to enter the first lens array51. As a result, the sub-light fluxes produced by the first lenses511become light fluxes each having a shape similar to the shape of the effective areas AR. Roughly the entire sub-light fluxes are therefore allowed to enter Roughly the entire surfaces of the effective areas AR.

Since the distance between the first lens array51and the second lens array52does not need to be shortened, the increase in the angle of emergence of the light that exits out of the light modulators34toward the projection optical apparatus36can be suppressed. As a result, the amount of light that does not enter the projection optical apparatus36can be reduced, whereby a decrease in brightness of a projected image can be suppressed. The use efficiency of the light emitted from the light source apparatus4(light source section41) can therefore be improved.

Further, since the anisotropic diffusion element44can provide the advantageous effects described above, it is not necessary to employ a homogenizer system having a pair of multi-lens arrays. The configuration of the illuminator31can therefore be simplified, whereby the manufacturing cost can be reduced.

The illuminator31described above has the afocal system42, which serves as an optical element that causes the light fluxes emitted from the solid-state light sources411and incident via the parallelizing lenses412(excitation light) to converge and causes the convergent light fluxes to enter the anisotropic diffusion element44. Since the afocal system42can reduce the light flux diameter of the light incident on the anisotropic diffusion element44, the size of the anisotropic diffusion element44can be reduced, and the size of each optical element (components44to49and4A described above, for example) located in the optical path of the light having exited out of the anisotropic diffusion element44can be reduced. The size of the illuminator31can therefore be reduced.

The homogenizing apparatus5, which forms the illuminator31, has the polarization conversion element53described above. The polarization conversion element53allows the illuminator31to output the illumination light WL having polarization directions aligned with one another, whereby the versatility of the illuminator31can be improved.

Since the effective area AR of each of the second lenses521, in accordance with which the anisotropic diffusion element44adjusts the shape of the excitation light, is an area that allows the light incident on the second lens521to be reliably incident on the polarization separation layer532, roughly the entire sub-light flux is allowed to enter roughly the entire surface of the effective area AR, whereby roughly the entire sub-light flux having exited out of the second lens521is allowed to enter the polarization separation layer532without incidence of the sub-light flux on the reflection layer533or the light blocker535. Therefore, light loss can be suppressed, whereby the light use efficiency can be reliably improved.

Since the area illuminated with the light fro(r) the illuminator31is the modulation areas341of the light modulators34, the modulation areas341can be illuminated with light having a uniform illuminance distribution. Brightness unevenness in a projected image can therefore be suppressed. Further, since it is not necessary to shorten the distance between the first lens array51and the second lens array52, the increase in the angle of emergence of the light fluxes that exit out of the light modulators34(image light fluxes) toward the projection optical apparatus36is suppressed, as described above. Therefore, a decrease in brightness of a projected image can be suppressed, and the use efficiency of the light from the light source section41is improved, whereby the brightness of the projected image can be increased.

Variations of Embodiment

The invention is not limited to the embodiment described above, and changes, improvements, and other modifications to the extent that the advantage of the invention is achieved fall within the scope of the invention.

The anisotropic diffusion element44is configured to diffuse, in the widthwise direction, a light flux incident thereon (excitation light) and having an aspect ratio representing a horizontally elongated shape. The anisotropic diffusion element44is, however, not necessarily configured as described above, and an element that reduces the diameter of the light flux in the longitudinal direction may be employed as the anisotropic diffusion element44. That is, the anisotropic diffusion element44only needs to adjust the shape of the light flux that exits out of the anisotropic diffusion element44in such a way that the shape is similar to the shape of the effective area AR of each of the second lenses521.

Further, as the thus functioning anisotropic diffusion element44, a configuration having a roughened surface roughened differently in two axes that intersect each other in a plane orthogonal to the optical axis has been shown by way of example as well as a configuration having a hologram or multiple lenses. However, the configuration of the anisotropic diffusion element44is not limited to those described above and can be changed as appropriate.

Moreover, the anisotropic diffusion element44is not necessarily configured to transmit a light flux incident thereon and may be configured to reflect the incident light flux.

The light source apparatus4has the afocal system42disposed between the light source section41having the solid-state light sources411and the anisotropic diffusion element44. However, the thus configured afocal system42may be omitted. Further, in place of the afocal system42, another optical element that causes the light flux from the light source section41to be convergent and the convergent light flux to enter the anisotropic diffusion element44may be employed.

The effective area AR of each of the second lenses521is set as an area that allows the light incident on the second lens521to be reliably incident on the polarization separation layer532. The effective area AR is not necessarily set as described above and may be defined by another factor. For example, in a case where the shape of the modulation areas341of the light modulators34is not similar to the shape of the second lenses521, an area of each of the second lenses521that allows roughly the entire sub-light flux having passed through the second lens521to enter roughly the entire modulation area341may be defined as the effective area.

The wavelength conversion apparatus4A is configured to have the reflection layer4A4, which reflects the fluorescence produced by the phosphor layer4A3, when the excitation light is incident through the second pickup lens49on the phosphor layer4A3, toward the second pickup lens49. That is, the wavelength conversion apparatus4A is a reflective wavelength conversion apparatus that reflects fluorescence produced by incidence of excitation light. In contrast, the wavelength conversion apparatus4A may be configured as a transmissive wavelength conversion element that outputs fluorescence along the direction in which excitation light incident on the wavelength conversion element travels. In this case, for example, in place of the reflection layer4A4, a wavelength selective reflection layer that transmits the excitation, light but reflects the fluorescence may be disposed on the excitation light incident side of the phosphor layer4A3, and the substrate4A2may be a light transmissive substrate.

Further, the wavelength, conversion element4A1(substrate4A2) may not be rotated in a case where the problem of the heat generated in the phosphor layer4A3is solved.

The projector1includes the three light modulators34(34R,34G, and34B), each of which has a liquid crystal panel as a light modulator. The invention is, however, also applicable to a projector fewer than or equal to two or greater than or equal to four light modulators.

Each of the light modulators34is configured to have a transmissive liquid crystal panel having a light flux incident surface and a light flux exiting surface different from each other and may instead be configured to have a reflective liquid crystal panel having a single surface that serves both as the light incident surface and the light exiting surface. Further, a light modulator that does not use a liquid crystal material but can modulate an incident light flux to form an image according to image information, such as a device using a micromirror, for example, a DMD (digital micromirror device), may be used.

The optical unit3is configured to have the optical parts and the arrangement thereof shown inFIGS. 1 and 2by way of example, but not necessarily, and may employ another configuration and arrangement.

For example, in the illuminator31, the first retardation plate43and the polarization separation apparatus45separate part of the excitation light emitted from the light source section41and combine the part of the excitation light as blue light with the fluorescence to produce the illumination light WL. In contrast, instead of separating part of the excitation light emitted from the light source section41and using the separated excitation light as blue light, another light source section that outputs blue light may be employed in addition to the light source section41. In this case, the fluorescence produced by the excitation light emitted from the light source section41may be combined with the blue light emitted from the other light source section to produce the illumination light WL, or the green light LG and the red light LR separated from the fluorescence may be caused to enter the light modulators34G and34R, respectively, and the blue light emitted from the other light source section described above may be caused to enter the light modulator34B.

The illuminator31described above is used in the projector1, but not necessarily, and can be used in a lighting apparatus, a light source apparatus of an automobile, and other apparatus.

The entire disclosure of Japanese Patent Application No. 2015-211604, filed Oct. 28, 2015 is expressly incorporated by reference herein.