Multi-lens array, light source device, and projector

A multi-lens array according to the present disclosure includes a substrate part, a first multi-lens surface which includes a plurality of first lens surfaces, and which is provided to the substrate part, a light transmissive layer provided to the substrate part, and an antireflection layer disposed on the light transmissive layer, wherein the antireflection layer is higher in thermal conductivity than the light transmissive layer.

The present application is based on, and claims priority from JP Application Serial Number 2020-048804, filed Mar. 19, 2020, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a multi-lens array, a light source device, and a projector.

2. Related Art

In the past, it has been known that a multi-lens array is used as an optical system of homogenously illuminating a liquid crystal panel as an illumination target area in a projector (see, e.g., JP-A-2013-120349).

In the projector, in order to realize high-luminance and high-contrast projection, a multi-lens array higher in accuracy becomes necessary, when the multi-lens array is molded using a metal mold, there is a possibility that the microscopic asperity of a surface of the metal mold is transferred to a lens surface of the multi-lens array.

Since the multi-lens array is disposed close to a light source in the projector, and is therefore easy to generate heat, it becomes important to enhance a radiation performance of the multi-lens array. In general, an antireflection layer is disposed on the lens surface in order to enhance the transmittance in some cases, but the thermal conductivity of Ta2O5, Nb2O5, or the like used as the antireflection layer is higher than the thermal conductivity of SiO2as a lens constituent material. Therefore, when the multi-lens array generates heat, the heat of the multi-lens array becomes difficult to be released toward the antireflection layer, and therefore, there is a problem that a crack occurs on the lens surface or the antireflection layer is separated due to the asperity transferred to the lens surface of the multi-lens array.

SUMMARY

In view of the problems described above, according to a first aspect of the present disclosure, there is provided a multi-lens array including a substrate part, a first multi-lens surface which includes a plurality of first lens surfaces, and which is provided to the substrate part, a light transmissive layer provided to the substrate part, and an antireflection layer disposed on the light transmissive layer, wherein the antireflection layer is higher in thermal conductivity than the light transmissive layer.

According to a second aspect of the present disclosure, there is provided a light source device including a light source, and an integrator optical system which light emitted from the light source enters, wherein the integrator optical system includes a first multi-lens array and a second multi-lens array, and at least one of the first multi-lens array and the second multi-lens array is formed of the multi-lens array according to the first aspect.

According to a third aspect of the present disclosure, there is provided a light source device including a light source, and an integrator optical system which light emitted from the light source enters, wherein the integrator optical system is constituted by the multi-lens array according to the first aspect.

According to a fourth aspect of the present disclosure, there is provided a projector including the light source device according to the second aspect or the third aspect of the present disclosure, a light modulation device configured to modulate light from the light source device in accordance with image information, and a projection optical device configured to project the light modulated by the light modulation device.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, an embodiment of the present disclosure will be described using the drawings.

A projector according to the present embodiment is an example of a projector using liquid crystal panels as light modulation devices.

It should be noted that in each of the drawings described below, the constituents are shown with the scale ratios of respective sizes set differently between the constituents in some cases in order to facilitate the visualization of each of the constituents.

First Embodiment

FIG. 1is a diagram showing a configuration of the projector according to the present embodiment.

The projector1according to the present embodiment shown inFIG. 1is a projection-type image display device for displaying a color image on a screen (a projection target surface) SCR. The projector1uses three light modulation devices corresponding to respective colored light beams, namely red light LR, green light LG, and blue light LB.

The projector1is provided with a light source device2, a color separation optical system3, a light modulation device4R, a light modulation device4G, a light modulation device4B, a combining optical system5, and a projection optical device6.

The light source device2emits illumination light WL having a white color toward the color separation optical system3. The color separation optical system3separates the illumination light WL having a white color into the red light LR, the green light LG, and the blue light LB. The color separation optical system3is provided with a first dichroic mirror7a, a second dichroic mirror7b, a first reflecting mirror8a, a second reflecting mirror8b, a third reflecting mirror8c, a first relay lens9a, and a second relay lens9b.

The first dichroic mirror7aseparates the illumination light WL from the light source device2into the red light LR and the other light (the green light LG and the blue light LB). The first dichroic mirror7atransmits the red light LR thus separated from, and at the same time reflects the other light (the green light LG and the blue light LB). Meanwhile, the second dichroic mirror7bseparates the other light into the green light LG and the blue light LB. The second dichroic mirror7breflects the green light LG thus separated from and transmits the blue light LB.

The first reflecting mirror8ais disposed in the light path of the red light LR, and the red light LR which has been transmitted through the first dichroic mirror7ais reflected by the first reflecting mirror8atoward the light modulation device4R. Meanwhile, the second reflecting mirror8band the third reflecting mirror8care disposed in the light path of the blue light LB, and the blue light LB which has been transmitted through the second dichroic mirror7bis reflected by the second reflecting mirror8band the third reflecting mirror8ctoward the light modulation device4B. Further, the green light LG Is reflected by the second dichroic mirror7btoward the light modulation device4G.

The first relay lens8aand the second relay lens9bare disposed at the light exit side of the second dichroic mirror7bin the light path of the blue light LB. The first relay lens9aand the second relay lens9bcorrect a difference in illuminance distribution of the blue light LB due to the fact that the blue light LB is longer in optical path length than the red light LR and the green light LG.

The light modulation device4R modulates the red light LP in accordance with image information to form image light corresponding to the red light LR. The light modulation device4G modulates the green light LG in accordance with the image information to form image light corresponding to the green light LG. The light modulation device4B modulates the blue light LB in accordance with the image information to form image light corresponding to the blue light LB.

As the light modulation device4R, the light modulation device4G, and the light modulation device4B, there are used, for example, transmissive liquid crystal panels. Further, at the incident side and the exit side of the liquid crystal panel, there are disposed polarization plates (not shown), respectively, and thus, there is formed a configuration of transmitting only the linearly polarized light with a specific direction.

At the incident side of the light modulation device4R, the light modulation device4G, and the light modulation device4B, there are disposed a field lens10R, a field lens10G, and a field lens10B, respectively. The field lens10R, the field lens10G, and the field lens10B collimate principal rays of the red light LR, the green light LG, and the blue light LB which enter the light modulation device4R, the light modulation device4G, and the light modulation device4B, respectively.

The combining optical system5combines the image light corresponding to the red light LR, the image light corresponding to the green light LG, and the image light corresponding to the blue light LB with each other in response to incidence of the image light respectively emitted from the light modulation device4R, the light modulation device4G, and the light modulation device4B, and then emits the image light thus combined toward the projection optical device6. As the combining optical system5, there is used, for example, a cross dichroic prism.

The projection optical device6is constituted by a plurality of projection lenses. The projection optical device6projects the image light having been combined by the combining optical system5toward the screen SCR in an enlarged manner. Thus, an image is displayed on the screen SCR.

The light source device2according to the present embodiment is provided with a light source20, an integrator optical system31, a polarization conversion element32, and a superimposing optical system33. In the present embodiment, a known constituent such as a lamp, an LED, and a semiconductor laser is used as the light source20, and the light source20emits the illumination light WL having a white color. Further, as the light source20, it is possible to adopt a light source for preforming wavelength conversion on excitation light emitted from the LED or the semiconductor laser to thereby generate fluorescence.

The integrator optical system31is provided with a first multi-lens array21, and a second multi-lens array22. The illumination light WL having been transmitted through the integrator optical system31enters the polarization conversion element32. The polarization conversion element32is constituted by polarization split films and wave plates arranged in an array. The polarization conversion element32uniforms the polarization direction of the illumination light WL into a predetermined direction. Specifically, the polarization conversion element32uniforms the polarization direction of the illumination light WL into a direction of a transmission axis of the incident side polarization plate of each of the light modulation devices4R,4G, and4B.

Thus, the polarization direction of the red light LR, the green light LG, and the blue light LB obtained by separating the illumination light WL having been transmitted through the polarization conversion element32coincides with the transmission axis direction of the incident side polarization plate of each of the light modulation devices4R,4G, and4B. Therefore, the red light LR, the green light LG, and the blue light LB enter the image formation areas of the light modulation devices4R,4G, and4B, respectively, without being blocked by the incident side polarization plates, respectively.

Incidentally, the integrator optical system31disposed close to the light source20is easy to generate heat. The projector1according to the present embodiment cools a heat generation member such as the integrator optical system31with a cooling system (not shown) using, for example, air cooling, water-cooling, or a Peltier element. Therefore, the integrator optical system31in the present embodiment improves the radiation performance by adopting a configuration described later to thereby increase the cooling efficiency in the cooling system.

FIG. 2is a cross-sectional view showing a configuration of an essential part of the integrator optical system31.

As shown inFIG. 2, the first multi-lens array21has a substrate part42including a multi-lens surface (a first multi-lens surface)41aconstituted by a plurality of lens surfaces (first lens surfaces)41. Specifically, the first multi-lens array21has a plurality of first small lenses21a. Each of the surfaces of the first small lenses21ais formed of one of the lens surfaces41of the multi-lens surface41a.

It should be noted that the surface of the first small lens21aand the image formation area of each of the light modulation devices4R,4G and4B are conjugated with each other. Further, the shape of each of the first small lenses21ais a rectangular shape substantially similar to the shape of each of the image formation areas of the light modulation devices4R,4G and4B. Thus, each of the partial light beams emitted from the first multi-lens array21efficiently enters each of the image formation areas of the light modulation devices4R,4G, and4B.

The first multi-lens array21has a light transmissive layer43provided to the substrate part42, and an antireflection layer44disposed on the light transmissive layer43. The thickness of the light transmissive layer43is set in a range of 100 through 1500 nm such as a range of 400 through 600 nm. The thickness of the antireflection layer44is set in a range of 100 through 5000 nm such as 393 nm. The thickness of the substrate part42is set to be no smaller than 1500 nm such as no smaller than 1.5 mm. In other words, in the present embodiment, the thickness of the light transmissive layer43is smaller than the thickness of the substrate part42, and is larger than the thickness of the antireflection layer44.

The substrate part42has a reverse surface (a second surface)41bdifferent from the multi-lens surface41a. In the present embodiment, the reverse surface41bis a flat surface.

The light transmissive layer43is provided to the multi-lens surface41aof the substrate part42. The light transmissive layer43is a coating layer covering the multi-lens surface41a, and is formed of a light transmissive material such as SiO2or SiON. The light transmissive layer43in the present embodiment is formed of, for example, SiO2.

In the present embodiment, the antireflection layer44is a film for reducing the surface reflection of the first multi-lens array21, and is formed of a coating film made of, for example, SiO2, MgF2, Nb2O5, Ti3O5, Ta2O5, Al2O3, or ZrO2. The antireflection layer44in the present embodiment is formed of, for example, Ta2O5. The antireflection layer44covers the light transmissive layer43and the reverse surface41bof the substrate part42.

In the present embodiment, the thermal conductivity of the light transmissive layer43made of SiO2is 1.5 W/m·k, and the thermal conductivity of the antireflection layer44made of Ta2O5is 3 through 5 W/m·k. In other words, in the present embodiment, the thermal conductivity of the antireflection layer44is higher than the thermal conductivity of the light transmissive layer43.

It should be noted that it becomes possible to arbitrarily control the refractive index of the light transmissive layer43in accordance with the coating method selected when forming the film. By controlling the refractive index of the light transmissive layer43as described above, it is possible to increase the degree of design freedom of the antireflection layer44.

The multi-lens surface41aand the lens surfaces41constituting the first multi-lens array21according to the present embodiment are manufactured using a molding method of transferring the metal mold shape. There is created the state in which the microscopic asperity on the metal mold surface is also transferred to the multi-lens surface41aand the lens surfaces41of the substrate part42manufactured using the molding method described above.

FIG. 3is an enlarged view showing a configuration of an essential part of the first multi-lens array21.

As shown inFIG. 3, the multi-lens surface41ais provided with the asperity45caused by the metal mold surface shape. The light transmissive layer43is formed so as to get into the asperity45provided to the multi-lens surface41a. In other words, the light transmissive layer43planarizes the asperity45on the multi-lens surface41a. It should be noted that the light transmissive layer43is formed using a wide variety of processing methods such as DIP, spraying, or spin coating.

In the present embodiment, the light transmissive layer43can fill a microscopic crack occurring in the vicinity of a ridge line portion located on a boundary between the lens surfaces41, and can therefore relax the stress concentration due to thermal expansion to increase the mechanical strength of the first multi-lens array21. As a result, the thickness of the first multi-lens array21is decreased from the design viewpoint to achieve reduction in cost by reduction in material cost, and reduction in product weight.

In the present embodiment, the surface roughness of the light transmissive layer43is lower than the surface roughness of the multi-lens surface41a. Specifically, the surface roughness of the light transmissive layer43is no higher than 20 nm. According to this configuration, since the surface roughness of the foundation for forming the antireflection layer44is low, it becomes easy to generate the antireflection layer44. Therefore, since it is possible to form the antireflection layer44with a film high in homogeneity, it is possible for the antireflection layer44to obtain a desired antireflection performance.

Further, for example, when forming the light transmissive layer43using a liquid phase method, it is possible for the light transmissive layer43to easily fill ail gaps in a short time due to a capillary action even when there exist the asperity45provided to the multi-lens surface41ato be the foundation, porous gaps which cannot be removed by etching or grinding, or a defect such as a micro crack in a range of, for example, 0.01 μm through 10 μm such as an affected layer. Therefore, the light transmissive layer43has a function of increasing the mechanical strength of the substrate part42.

According to the first multi-lens array21related to the present embodiment, the heat generated in the substrate part42by the illumination light WL emitted from the light source device2becomes to efficiently be transferred toward the antireflection layer44high in thermal conductivity via the light transmissive layer43. Thus, the first multi-lens array21becomes excellent in radiation performance. Therefore, since the cooling effect of the first multi-lens array21is further enhanced, the cooling performance in the projector1is improved.

Here, as a comparative example, there will be described when directly forming the antireflection layer44on the multi-lens surface41awithout disposing the light transmissive layer43.

FIG. 4is an enlarged view showing a configuration of an essential part of a first multi-lens array according to the comparative example.

The first multi-lens array21A according to the comparative example shown inFIG. 4is smaller in contact area with the antireflection layer44due to an influence of the asperity45provided to the multi-lens surface41a. Therefore, the heat transfer from the substrate part42to the antireflection layer44becomes poor. Further, the heat is accumulated in gaps formed between the antireflection layer44and the multi-lens surface41a, namely the asperity45.

In the first multi-lens array21A according to the comparative example, the asperity45is in a state of including air or in a vacuum state, and is therefore poor in thermal conductivity. Therefore, when the first multi-lens array21A becomes high in temperature while being in use, since, for example, the substrate part42and the antireflection layer44are different in amount of thermal expansion from each other, there is a possibility that a crack occurs in the substrate part42, or the antireflection layer44is separated. As a result, there is a possibility that the display quality of the projector deteriorates, or that the light use efficiency of the projector decreases to make the display image dark due to the Fresnel reflection caused by a separated part of the antireflection layer44.

In contrast, according to the first multi-lens array21related to the present embodiment, since the heat is easy to be transferred from the substrate part42to the antireflection layer44as described above, it is possible to prevent a defect such as a crack from occurring. Further, according to the first multi-lens array21related to the present embodiment, since the thermal conductivity is improved by providing the light transmissive layer43, it is possible to prevent the deterioration of the display quality described above and the decrease in brightness of the display image.

Further, in the configuration of the first multi-lens array21A according to the comparative example, there is a possibility that diffusion or absorption of the incident light due to the asperity45occurs, and as a result, the light reaching the screen decreases to decrease the light use efficiency. Further, there occurs rise in temperature due to the irradiation of the optical member in the light path with the light thus diffused, or rise in temperature due to absorption of the light by the multi-lens array itself, and thus, a high performance cooling system for the projector becomes necessary.

In contrast, according to the first multi-lens array21related to the present embodiment, by filling the asperity45with the light transmissive layer43, it is possible to prevent the light use efficiency from decreasing due to the diffusion or the absorption of the incident light. Further, since it is also possible to suppress the rise in temperature of optical components and the multi-lens array itself, it is possible to simplify the cooling system for the projector, and thus, it is possible to achieve reduction in cost, and at the same time, it is possible to reduce the size of the device.

Further, in the configuration of the first multi-lens array21A according to the comparative example, when, for example, the depth of the asperity45is around the wavelength of the incident light, total reflection occurs on the interface with the air or vacuum, and a shift occurs in the phase of the light. As a result, there is a possibility that the light use efficiency decreases in a wavelength band in which the polarization conversion efficiency of the polarization conversion element32disposed in the posterior stage is inferior from the design viewpoint.

In contrast, according to the first multi-lens array21related to the present embodiment, since the asperity45is filled with the light transmissive layer43, the phase shift in the light does not occur, and this, such a decrease in light use efficiency as described above can be prevented.

Further, in the configuration of the first multi-lens array21A according to the comparative example, when, for example, the asperity45is composed of such holes as mesopores in a range of 2 through 50 nm in diameter, the antireflection layer44is disposed in the state in which moisture is adsorbed in the mesopores, and thus, the moisture is confined in the asperity45in some cases. Further, when, for example, TiO2in an amorphous state is used as the antireflection layer44, when the temperature of the multi-lens array rises to a high temperature, a state transition to a tetragonal structure is caused. In such a structure, due to, for example, the irradiation with an ultraviolet ray from a high-pressure mercury lamp light source, a strong catalytic action occurs, and thus, the moisture included in the asperity45is decomposed to generate radical oxygen. The radical oxygen separates the oxygen combined with Ti included in the antireflection layer44to decrease the transmittance of the antireflection layer44, and thus, there arises a problem such as a decrease in light use efficiency of the projector or a decrease in brightness of the display image.

In contrast, according to the first multi-lens array21related to the present embodiment, by providing the light transmissive layer43, it is possible to block the mesopores included in the asperity45to prevent the moisture from adsorbing, and at the same time it is possible to improve the thermal conductivity to suppress the rise in temperature of the multi-lens array, and thus it is possible to prevent such a decrease in light use efficiency of the projector as described above.

Further, it is conceivable to improve the surface shape by performing a surface treatment on the multi-lens surface41ato thereby Increase the contact area between the antireflection layer44and the multi-lens surface41a. However, in order to obtain the surface roughness no higher than, for example, 20 nm, removal processing such as grinding processing or blast processing becomes necessary, and since the processing time is long, productivity slowdown is incurred. Further, when processing the surface shape of the multi-lens surface41a, there is a possibility of incurring a decrease in surface shape accuracy depending on an amount of the processing or a place of the processing.

In contrast, in the first multi-lens array21according to the present embodiment, since the light transmissive layer43can be formed using a wide variety of processing methods such as DIP, spraying, or spin coating, the productivity is extremely high, it is easy to make an amount of coating constant, and it is possible to suppress the influence on the surface shape of the multi-lens surface41aby controlling the film thickness to be no larger than 1 μm. Therefore, in the first multi-lens array21according to the present embodiment, the change in surface shape caused by performing surface processing on the multi-lens surface41adoes not occur.

On the other hand, the second multi-lens array22has a substrate part52including a multi-lens surface (a first multi-lens surface)51aconstituted by a plurality of lens surfaces (first lens surfaces)51. Specifically, the second multi-lens array22has a plurality of second small lenses22a. Each of the surfaces of the second small lenses22ais formed of one of the lens surfaces51of the multi-lens surface51a.

The plurality of second small lenses22acorresponds to the plurality of first small lenses21aof the first multi-lens array21. The second multi-lens array22forms images of the respective first small lenses21aof the first multi-lens array21in the vicinity of each of the image formation areas of the respective light modulation devices4R,4G, and4B in cooperation with the superimposing optical system33.

The second multi-lens array22has a light transmissive layer53provided to the substrate part52, and an antireflection layer54disposed on the light transmissive layer53. In the present embodiment, the second multi-lens array22has substantially the same configuration as that of the first multi-lens array21. Specifically, the thickness and the material of the light transmissive layer53, the antireflection layer54, and the substrate part52are set to be substantially the same as the thickness and the material of the light transmissive layer43, the antireflection layer44, and the substrate part42of the first multi-lens array21. In the present embodiment, the thickness of the light transmissive layer53is smaller than the thickness of the substrate part52, and is larger than the thickness of the antireflection layer54.

The substrate part52has a reverse surface (a second surface)51bdifferent from the multi-lens surface51a. In the present embodiment, the reverse surface51bis a flat surface.

In the present embodiment, the second multi-lens array22is disposed with respect to the first multi-lens array21so that the reverse surface51bis opposed to the reverse surface41bof the first multi-lens array21.

The light transmissive layer53is provided to the multi-lens surface51aof the substrate part52. The antireflection layer54covers the light transmissive layer53and the reverse surface51bof the substrate part52. The thermal conductivity of the antireflection layer54is higher than the thermal conductivity of the light transmissive layer53.

According to the second multi-lens array22related to the present embodiment, similarly to the first multi-lens array21, since the heat generated in the substrate part52is efficiently transferred to the antireflection layer44via the light transmissive layer53, the radiation performance becomes excellent.

Further, according to the light source device2related to the present embodiment, since the light transmissive layers43,53are respectively provided to both of the first multi-lens array21and the second multi-lens array22, it is possible to dramatically improve the cooling performance of the integrator optical system31. Thus, since the heat generation of the integrator optical system31can be suppressed, the thermal deterioration of other optical components such as the polarization conversion element32and the superimposing optical system33to be disposed in the posterior stage of the integrator optical system31is suppressed.

Advantages of First Embodiment

The first multi-lens array21according to the present embodiment is a multi-lens array having the substrate part42including the multi-lens surface41aconstituted by the plurality of lens surfaces41, and has the light transmissive layer43provided to the substrate part42and the antireflection layer44disposed on the light transmissive layer43, and the thermal conductivity of the antireflection layer44is higher than the thermal conductivity of the light transmissive layer43.

Further, the second multi-lens array22according to the present embodiment is a multi-lens array having the substrate part52including the multi-lens surface51aconstituted by the plurality of lens surfaces51, and has the light transmissive layer53provided to the substrate part52and the antireflection layer54disposed on the light transmissive layer53, and the thermal conductivity of the antireflection layer54is higher than the thermal conductivity of the light transmissive layer53.

According to the first multi-lens array21and the second multi-lens array22related to the present embodiment, the heat generated in the substrate part42,52is efficiently transferred toward the antireflection layer44,54high in thermal conductivity via the light transmissive layer43,53, respectively. Thus, the multi-lens array excellent in radiation performance is provided as the first multi-lens array21and the second multi-lens array22.

In the present embodiment, the thickness of the light transmissive layer43is smaller than the thickness of the substrate part42, and is larger than the thickness of the antireflection layer44, and the thickness of the light transmissive layer53is smaller than the thickness of the substrate part52, and is larger than the thickness of the antireflection layer54.

According to this configuration, since the light transmissive layer43,53fills the asperity45provided to the surface of the substrate part42,52, the surface roughness of the substrate part42,52is suppressed to a level no higher than 20 nm. Thus, since contact area between the antireflection layer44,54and the light transmissive layer43,53increases, it is possible to enhance the cooling effect of the first multi-lens array21and the second multi-lens array22. Further, since the thickness of the light transmissive layer43is thinner than the thickness of the substrate part42, and the thickness of the light transmissive layer53is thinner than the thickness of the substrate part52, the material cost of the light transmissive layer43and the light transmissive layer53is suppressed, and thus, it is possible to enhance the cooling effect at lower cost.

The light source device2according to the embodiment is provided with the light source20and the integrator optical system21which the light emitted from the light source20enters, and the integrator optical system31includes the first multi-lens array21and the second multi-lens array22.

According to the light source device2related to the present embodiment, since there is provided the integrator optical system31including the first multi-lens array21and the second multi-lens array22excellent in radiation performance, it is possible to provide the light source device high in reliability.

The projector1according to the embodiment is provided with the light source device2described above, the light modulation devices4R,4G, and4B for modulating the light from the light source device2in accordance with the image information, and the projection optical device6for projecting the light modulated by the light modulation devices4R,4G, and4B.

According to the projector1related to the present embodiment, since there is provided the light source device2including the integrator optical system31excellent in radiation performance, it is possible to provide the projector with the cooling performance improved.

Second Embodiment

Then, a light source device according to a second embodiment will be described. The light source device according to the present embodiment is different in the configuration of the integrator optical system from the light source device2according to the first embodiment. Hereinafter, the integrator optical system will mainly be described. It should be noted that members common to the first embodiment will be denoted by the same reference symbols, and the detailed description thereof will be omitted.

FIG. 5is 3 cross-sectional view showing a configuration of an essential part of an integrator optical system131in the present embodiment. As shown inFIG. 5, the integrator optical system131in the present embodiment is provided with the first multi-lens array21, and a second multi-lens array122.

The second multi-lens array122has the substrate part52including the multi-lens surface51aconstituted by the plurality of lens surfaces51, and the antireflection layer54. The antireflection layer54covers the multi-lens surface51aand the reverse surface51bof the substrate part52. In other words, the second multi-lens array122according to the present embodiment does not have the light transmissive layer, and the antireflection layer54alone is disposed on the surface of the substrate part52.

In the integrator optical system131in the present embodiment, the light transmissive layer43is provided only to the substrate part42of the first multi-lens array21.

Advantages of Second Embodiment

According to the integrator optical system131in the present embodiment, since the light transmissive layer43is provided only to the first multi-lens array21, the constituent material of the light transmissive layer halves compared to the integrator optical system31in the first embodiment. Further, the integrator optical system131in the present embodiment has a configuration effective when putting a high priority on the reduction in cost, or when the radiation performance required for the integrator optical system is relatively low compared to the first embodiment.

In general, in the integrator optical system, the optical design is made so that the multi-lens array located at the light incident side of the pair of multi-lens arrays is brought into focus. Therefore, when the integrator optical system in which the surface roughness of the multi-lens array located at the light incident side is high is supposedly used as the light source device for a projector, there is a possibility that color unevenness, a shadow, or the like is reflected in the picture to be projected on the screen to degrade the image quality.

In contrast, according to the integrator optical system131in the present embodiment, since the light transmissive layer43is provided to the first multi-lens array21located at the light incident side, such a degradation in image quality due to the reflection of the color unevenness, the shadow, or the like as described above is prevented.

Third Embodiment

Then, a light source device according to a third embodiment will be described. The light source device according to the present embodiment is different in the configuration of the integrator optical system from the light source device2according to the first embodiment. Hereinafter, the integrator optical system will mainly be described. It should be noted that members common to the first embodiment will be denoted by the same reference symbols, and the detailed description thereof will be omitted.

FIG. 6is a cross-sectional view showing a configuration of an essential part of an integrator optical system231in the present embodiment. As shown inFIG. 6, the integrator optical system231in the present embodiment is provided with a first multi-lens array121, and the second multi-lens array22.

The first multi-lens array121has the substrate part42including the multi-lens surface41aconstituted by the plurality of lens surfaces41. In the first multi-lens array121according to the present embodiment, the antireflection layer44covers the multi-lens surface41aand the reverse surface41bof the substrate part42. In other words, the first multi-lens array121according to the present embodiment does not have the light transmissive layer, and the antireflection layer44alone is disposed on the surface of the substrate part42.

In the first multi-lens array121according to the present embodiment, the mechanical strength of glass material is increased using a chemical strengthening treatment. The chemical strengthening treatment is performed by performing ionic substitution on an Na component included in the glass material constituting the substrate part42and a K component included in an alkali solvent.

In the integrator optical system231in the present embodiment, the light transmissive layer53is provided only to the substrate part52of the second multi-lens array22.

Advantages of Third Embodiment

According to the integrator optical system231in the present embodiment, since the light transmissive layer53is provided only to the second multi-lens array22, the constituent material of the light transmissive layer halves compared to the integrator optical system31in the first embodiment. Further, the integrator optical system231in the present embodiment has a configuration effective when putting a high priority on the reduction in cost, or when the radiation performance required for the integrator optical system231is relatively low.

In the integrator optical system231in the present embodiment, by performing the chemical strengthening treatment on the first multi-lens array121which is located at the light incident side to thereby be exposed to a high temperature, it is possible to improve the heat resistance of the first multi-lens array121. Incidentally, the light transmissive layer is formed of a material not containing Na in some cases, and therefore, it is unachievable to perform the chemical strengthening treatment on the multi-lens array provided with the light transmissive layer. According to the configuration of the present embodiment, the first multi-lens array121which is located at the light incident side and is exposed to a high temperature is improved in heat resistance by the chemical strengthening treatment, and regarding the second multi-lens array22disposed in the posterior stage, the improvement in radiation performance and the mechanical strength is realized by the light transmissive layer53. Therefore, according to the present embodiment, since both of the chemical strengthening treatment and the light transmissive layer are used, there is provided a configuration effective from the viewpoint of the degree of design freedom in the integrator optical system.

FIRST MODIFIED EXAMPLE

Then, a first modified example of the light source device will be described. The present modified example is a modified example related to the light source device2according to the first embodiment. The present modified example is different in the configuration of the integrator optical system from the first embodiment. Hereinafter, the integrator optical system will mainly be described. It should be noted that members common to the first embodiment will be denoted by the same reference symbols, and the detailed description thereof will be omitted.

FIG. 7is a cross-sectional view showing a configuration of an essential part of the integrator optical system331in the present modified example. As shown inFIG. 7, in the integrator optical system331in the present modified example, the light transmissive layer43is disposed so as to cover the both surfaces of the first multi-lens array21. Similarly, the light transmissive layer53is disposed so as to cover the both surfaces of the second multi-lens array22.

Specifically, the light transmissive layer43includes a first light transmissive layer43aand a second light transmissive layer43b. The first light transmissive layer43ais provided to the multi-lens surface41aof the substrate part42. The second light transmissive layer43bis provided to the reverse surface41bof the substrate part42. Since the reverse surface41bof the substrate part42is covered with the second light transmissive layer43bto thereby be planarized, processing such as lap-less working becomes unnecessary, and thus, the cost reduction is achieved.

Specifically, the light transmissive layer53includes a first light transmissive layer53aand a second light transmissive layer53b. The first light transmissive layer53ais provided to the multi-lens surface51aof the substrate part52. The second light transmissive layer53bis provided to the reverse surface51bof the substrate part52. Since the reverse surface51bof the substrate part52is covered with the second light transmissive layer53bto thereby be planarized, processing such as lap-less working becomes unnecessary, and thus, the cost reduction is achieved.

In the first multi-lens array21, the antireflection layer44is disposed on the first light transmissive layer43aand the second light transmissive layer43b. The antireflection layer44is disposed so as to cover the multi-lens surface41aand the reverse surface41bof the substrate part42.

In the second multi-lens array22, the antireflection layer54is disposed on the first light transmissive layer53aand the second light transmissive layer53b. The antireflection layer54is disposed so as to cover the multi-lens surface51aand the reverse surface51bof the substrate part52.

In the present modified example, the thickness of the first light transmissive layer43aand the thickness of the second light transmissive layer43bcan be made different from each other. By making the first light transmissive layer43aand the second light transmissive layer43bcovering the both surfaces of the substrate part42different in thickness from each other as described above, it becomes possible to control the radiation direction of the heat from the substrate part42. Similarly, by making the first light transmissive layer53aand the second light transmissive layer53bcovering the both surfaces of the substrate part52different in thickness from each other, it becomes possible to control the radiation direction of the heat from the substrate part52.

When making one of the first light transmissive layer43aand the second light transmissive layer43blarger in thickness than the ether, the heat accumulated in the substrate part42becomes apt to be released toward the light transmissive layer larger in thickness. Similarly, when making one of the first light transmissive layer53aand the second light transmissive layer53blarger in thickness than the other, the heat accumulated in the substrate part52becomes apt to be released toward the light transmissive layer larger in thickness.

In other words, in the projector, when cooling the first multi-lens array21and the second multi-lens array22with a cooling wind supplied from, for example, a cooling system, by enlarging the thickness of the light transmissive layer located at the side supplied with the cooling wind, the cooling effect of the cooling system is further enhanced. Therefore, it is possible to increase the degree of design freedom of the cooling system in the projector.

SECOND MODIFIED EXAMPLE

Then, a second modified example of the light source device will be described. The present modified example is a modified example related to the light source device2according to the second embodiment. The present modified example is different in the configuration of the integrator optical system from the second embodiment. Hereinafter, the integrator optical system will mainly be described. It should be noted that members common to the second embodiment will be denoted by the same reference symbols, and the detailed description thereof will be omitted.

FIG. 8is a cross-sectional view showing a configuration of an essential part of an integrator optical system431in the present modified example. As shown inFIG. 8, the integrator optical system431in the present modified example is provided with the first multi-lens array21, and the second multi-lens array122. In the integrator optical system431in the present modified example, the light transmissive layer43is disposed so as to cover the both surfaces of the first multi-lens array21.

According to the integrator optical system431in the present modified example, since only the both surfaces of the first multi-lens array21are covered with the light transmissive layer43, the constituent material of the light transmissive layer halves compared to the configuration of the first modified example. Therefore, the present modified example has a configuration effective when putting a high priority on the reduction in cost, or when the radiation performance required for the integrator optical system is relatively low compared to the first modified example.

THIRD MODIFIED EXAMPLE

Then, a third modified example of the light source device will be described. The present modified example is a modified example related to the light source device2according to the third embodiment. The present modified example is different in the configuration of the integrator optical system from the third embodiment. Hereinafter, the integrator optical system will mainly be described. It should be noted that members common to the third embodiment will be denoted by the same reference symbols, and the detailed description thereof will be omitted.

FIG. 9is a cross-sectional view showing a configuration of an essential part of an integrator optical system531in the present modified example. As shown inFIG. 9, the integrator optical system531in the present modified example is provided with the first multi-lens array121, and the second multi-lens array22. In the integrator optical system531in the present modified example, the light transmissive layer53is disposed so as to cover the both surfaces of the second multi-lens array22.

According to the integrator optical system531in the present modified example, since only the both surfaces of the second multi-lens array22are covered with the light transmissive layer53, the constituent material of the light transmissive layer halves compared to the configuration of the first modified example. Therefore, the present modified example has a configuration effective when putting a high priority on the reduction in cost, or when the radiation performance required for the integrator optical system is relatively low compared to the first modified example.

Fourth Embodiment

Then, a light source device according to a fourth embodiment will be described. The light source device according to the present embodiment is different in the configuration of the integrator optical system from the light source device2according to the first embodiment. Hereinafter, the integrator optical system will mainly be described. It should be noted that members common to the first embodiment will be denoted by the same reference symbols, and the detailed description thereof will be omitted.

FIG. 10is a cross-sectional view showing a configuration of an essential part of an integrator optical system631in the present embodiment. As shown inFIG. 10, the integrator optical system631in the present embodiment is formed of a single multi-lens array60.

The multi-lens array60according to the present embodiment has a substrate part62including a first multi-lens surface61aconstituted by a plurality of first lens surfaces61. Specifically, the multi-lens array60has a plurality of first small lenses62adisposed at one surface side. Each of the surfaces of the first small lenses62ais formed of one of the first lens surfaces61of the first multi-lens surface61a.

The substrate part62has a second multi-lens surface (a second surface)63adifferent from the first multi-lens surface61a. In the present embodiment, the second multi-lens surface63ais disposed at an opposite side to the first multi-lens surface61aof the substrate part62. The second multi-lens surface63ais constituted by a plurality of second lens surfaces63. Specifically, the multi-lens array60has a plurality of second small lenses62bdisposed at an opposite side to the plurality of first small lenses62a. Each of the surfaces of the second small lenses62bis formed of one of the second lens surfaces63of the second multi-lens surface63a.

In other words, the multi-lens array60according to the present embodiment has the first multi-lens surface61aand the second multi-lens surface63aprovided to the respective surfaces of the substrate part62.

The multi-lens array60has the light transmissive layer43provided to the substrate part62, and the antireflection layer44disposed on the light transmissive layer43. In the present embodiment, the light transmissive layer43is provided to the first multi-lens surface61aand the second multi-lens surface63aof the substrate part62. The antireflection layer44covers the first multi-lens surface61aand the second multi-lens surface63avia the light transmissive layer43.

Similarly to other embodiments, the substrate part62constituting the multi-lens array60according to the present embodiment is manufactured using a molding method of transferring the metal mold shape. Therefore, there is created the state in which the microscopic asperity on the metal mold surface is also transferred to the first multi-lens surface61aand the second multi-lens surface63a.

Advantages of Fourth Embodiment

The multi-lens array60according to the present embodiment has the substrate part62provided with the first multi-lens surface61aand the second multi-lens surface63a, the light transmissive layer43provided to the substrate part62, and the antireflection layer44disposed on the light transmissive layer43, and the thermal conductivity of the antireflection layer44is higher than the thermal conductivity of the light transmissive layer43.

According to the multi-lens array60related to the present embodiment, the heat generated in the substrate part62is efficiently transferred toward the antireflection layer44high in thermal conductivity via the light transmissive layer43. Thus, there is provided the multi-lens array60which is provided with a plurality of lenses disposed on both surfaces, and is excellent in radiation performance.

Further, according to the integrator optical system631related to the present embodiment, since the integrator optical system is formed of the single multi-lens array60, the number of components decreases to thereby achieve reduction in weight and reduction in size. Further, in the light source device and the projector each provided with the integrator optical system631according to the present embodiment, reduction in weight and reduction in size are also achieved.

Fifth Embodiment

Then, a light source device according to a fifth embodiment will be described. The light source device according to the present embodiment is different in the configuration of the integrator optical system from the light source device2according to the first embodiment. Hereinafter, the integrator optical system will mainly be described. It should be noted that members common to the first embodiment will be denoted by the same reference symbols, and the detailed description thereof will be omitted.

FIG. 11is a cross-sectional view showing a configuration of an essential part of an integrator optical system731in the present embodiment. As shown inFIG. 11, the integrator optical system731in the present embodiment is formed of a single multi-lens array150.

The multi-lens array160according to the present embodiment has the substrate part62, the light transmissive layer43, and the antireflection layer44. In the integrator optical system731in the present embodiment, the light transmissive layer43is provided only to the first multi-lens surface61ain the substrate part62.

Advantages of Fifth Embodiment

According to the integrator optical system731in the present embodiment, since the light transmissive layer43is provided only to the first multi-lens surface61a, the constituent material of the light transmissive layer halves compared to the integrator optical system631in the fourth embodiment. Further, the integrator optical system731in the present embodiment has a configuration effective when putting a high priority on the reduction in cost, or when the radiation performance required for the integrator optical system is relatively low compared to the fourth embodiment.

Sixth Embodiment

Then, a light source device according to a sixth embodiment will be described. The light source device according to the present embodiment is different in the configuration of the integrator optical system from the light source device2according to the first embodiment. Hereinafter, the integrator optical system will mainly be described. It should be noted that members common to the first embodiment will be denoted by the same reference symbols, and the detailed description thereof will be omitted.

FIG. 12is a cross-sectional view showing a configuration of an essential part of an integrator optical system831in the present embodiment. As shown inFIG. 12, the integrator optical system831in the present embodiment is formed of a single multi-lens array151.

The multi-lens array161according to the present embodiment has the substrate part62, the light transmissive layer43, and the antireflection layer44. In the integrator optical system831in the present embodiment, the light transmissive layer43is provided only to the second multi-lens surface63ain the substrate part62.

Advantages of Sixth Embodiment

According to the integrator optical system831in the present embodiment, since the light transmissive layer43is provided only to the second multi-lens surface63a, the constituent material of the light transmissive layer halves compared to the integrator optical system631in the fourth embodiment. Further, the integrator optical system831in the present embodiment has a configuration effective when putting a high priority on the reduction in cost, or when the radiation performance required for the integrator optical system is relatively low compared to the fourth embodiment.

It should be noted that the scope of the present disclosure is not limited to the embodiments described above, but a variety of modifications can be provided thereto within the scope or the spirit of the present disclosure.

For example, in the embodiments and the modified examples described above, it is possible for the light transmissive layer to be disposed so as to cover up to side surfaces of the multi-lens array.FIG. 13is a diagram showing a configuration example in which the side surfaces of the multi-lens arrays are covered with the light transmissive layers.FIG. 13is a diagram showing the configuration in which the light transmissive layers cover up to the side surfaces of the multi-lens arrays in the integrator optical system in the first modified example.

In an integrator optical system331shown inFIG. 13, the light transmissive layer43is disposed so as to cover the both surfaces and side surfaces23of the first multi-lens array21, and the light transmissive layer53is disposed so as to cover the both surfaces and side surfaces24of the second multi-lens array22. It should be noted that the antireflection layer44disposed on the light transmissive layer43is disposed so as to cover the both surfaces and the side surfaces23of the first multi-lens array21, and the antireflection layer54disposed on the light transmissive layer53is disposed so as to cover the both surfaces and the side surfaces24of the second multi-lens array22.

By disposing the light transmissive layer43,53so as to cover up to the side surfaces23,24of the multi-lens array21,22as described above, edge parts of the multi-lens array21,22are covered with the light transmissive layer13,53. Therefore, since sharp portions in the edge parts dull, chamfering processing becomes unnecessary. As a result, it is possible to obtain the advantages such as reduction in cost due to reduction in process, or an improvement of operation safety in an assembling operation and so on.

Further, when there is adopted a structure in which the first multi-lens array21and the second multi-lens array22are disposed close to each other, a gap between the first multi-lens array21and the second multi-lens array22is made small. In this configuration, when, for example, performing air cooling of the first multi-lens array21and the second multi-lens array22, by supplying the cooling wind to an outer side of the lens arrays21,22, the cooling wind blows the light transmissive layers43,53covering the side surfaces23,24of the multi-lens arrays21,22, and thus, it becomes possible to enhance the cooling effect.

Besides the above, the specific descriptions of the shape, the number, the arrangement, the material, and so on of the constituents of the light source device and the projector are not limited to those in the embodiments described above, but can arbitrarily be modified. Although in the embodiments described above, there is described the example of installing the light source device according to the present disclosure in the projector using the liquid crystal light valves, the example is not a limitation. The light source device according to the present disclosure can also be applied to a projector using digital micromirror devices as the light modulation devices. Further, the projector is not required to have a plurality of light modulation devices, and can be provided with just one light modulation device.

Although in the embodiments described above, there is described the example of applying the light source device according to the present disclosure to the projector, the example is not a limitation. The light source device according to the present disclosure can also be applied to lighting equipment, a headlight of a vehicle, and so on.

It is also possible for the multi-lens array according to an aspect of the present disclosure to have the following configuration.

The multi-lens array according to the aspect of the present disclosure includes a substrate part, a first multi-lens surface which includes a plurality of first lens surfaces, and which is provided to the substrate part, a light transmissive layer provided to the substrate part, and an antireflection layer disposed on the light transmissive layer, wherein the antireflection layer is higher in thermal conductivity than the light transmissive layer.

In the multi-lens array according to the aspect of the present disclosure, the light transmissive layer may be smaller in thickness than the substrate part, and larger in thickness than the antireflection layer.

In the multi-lens array according to the aspect of the present disclosure, the substrate part may have a second surface different from the first multi-lens surface, the light transmissive layer may include a first light transmissive layer and a second light transmissive layer, the first light transmissive layer may be provided to the first multi-lens surface, and the second light transmissive layer may be provided to the second surface.

In the multi-lens array according to the aspect of the present disclosure, the first light transmissive layer may be different in thickness from the second light transmissive layer.

In the multi-lens array according to the aspect of the present disclosure, the second surface may be a flat surface.

In the multi-lens array according to the aspect of the present disclosure, the second surface may be a second multi-lens surface constituted by a plurality of second lens surfaces.

It is also possible for the light source device according to another aspect of the present disclosure to have the following configuration.

The light source device according to the aspect of the present disclosure includes a light source, and an integrator optical system which light emitted from the light source enters, wherein the integrator optical system includes a first multi-lens array and a second multi-lens array, and at least one of the first multi-lens array and the second multi-lens array is formed of the multi-lens array according to the aspect of the present disclosure.

The light source device according to the aspect of the present disclosure includes a light source, and an integrator optical system which light emitted from the light source enters, wherein the integrator optical system is constituted by the multi-lens array according to the aspect of the present disclosure.

It is also possible for the projector according to another aspect of the present disclosure to have the following configuration.

The projector according to another aspect of the present disclosure includes the light source device according to the aspect of the present disclosure, a light modulation device configured to modulate the light from the light source device in accordance with image information, and a projection optical device configured to project the light modulated by the light modulation device.