Light source unit and projector

A light source unit of the present invention includes a luminescent material plate, a joining plate on one side of which the luminescent material plate is disposed, a heat dissipating member disposed on the other side of the joining plate, and a heat conductive layer configured to thermally connect the joining plate and the heat dissipating member together and disposed between the joining plate and the heat dissipating member, and a heat conductivity of an area of the heat conductive layer which corresponds to the luminescent material plate is lower than a heat conductivity of a periphery of the area of the heat conductive layer which corresponds to the luminescent material plate.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is based upon and claims the benefit of priority under 35 USC 119 from Japanese Patent Application No. 2018-099648 filed on May 24, 2018, the entire disclosure of which, including the description, claims, drawings, and abstract, is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a light source unit and a projector including the light source unit.

Description of the Related Art

Data projectors are widely used on many occasions in these days as an image projector for projecting a screen of a personal computer, a video image, and further, an image based on image data recorded on a memory card or the like onto a screen. Conventionally, in the main stream of data projectors, high-intensity discharge lamps have been used. In recent years, however, projectors are proposed which include a light source unit employing a laser diode that is a semiconductor light emitting element that consumes less electric power, has an extended service life, and are highly bright.

A light source unit disclosed by Japanese Unexamined Patent Application No. 2013-187043 includes a luminescent material layer made up of ceramic of a luminescent material, that is, luminescent ceramic and a transparent layer provided an emerging side of the luminescent material layer from which light emerges, and a heat dissipating substrate is disposed on a side of the luminescent material layer which is situated opposite to the emerging side from which light emerges via a joining portion. The transparent layer is formed of, for example, transparent ceramic or transparent resin and has a higher heat conductivity than that of air. This transparent layer can effectively dissipate heat generated at an illuminated spot illuminated by excitation light shone from a solid light source in the luminescent material layer.

The transparent layer can increase a heat dissipating amount on the emerging side of the luminescent material layer (the luminescent material plate) that is made up of the luminescent ceramic or the like. However, even though thermal stress in the luminescent material plate is suppressed by increasing the heat dissipating amount on the emerging side of the luminescent material plate, in the event that a temperature difference between a front side and a rear side of the joining plate to which the luminescent material plate is joined is great, a warp is generated in the joining plate due to thermal expansion. Then, a drawback such as a crack or separation of the luminescent material plate may be generated from time to time.

SUMMARY OF THE INVENTION

The present invention has been made in view of the situations described above, and an object of the present invention is to provide a light source that can reduce the risk of cracking or separation of a luminescent material plate and a projector including this light source unit.

According to an aspect of the present invention, there is provided a light source unit including a luminescent material plate, a joining plate on one side of which the luminescent material plate is disposed, a heat dissipating member disposed on the other side of the joining plate, and a heat conductive layer configured to connect thermally the joining plate and the heat dissipating member and disposed between the joining plate and the heat dissipating member, wherein a heat conductivity of an area of the heat conductive layer which corresponds to the luminescent material plate is lower than a heat conductivity of a periphery of the heat conductive layer which corresponds to the luminescent material plate.

According to another aspect of the present invention, there is provided a projector including the light source unit described above, a display device on to which light source light is shone from the light source unit to form image light, a projection-side optical system configured to project the image light emitted from the display device on to a screen, and a projector control unit configured to control the display device and the light source unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, an embodiment according to the present invention will be described based on drawings.FIG. 1is a block diagram illustrating functional circuit blocks of a projector control unit of a projector10. The projector control unit includes a controller38, an input/output interface22, an image transforming module23, a display encoder24, a display driver26and the like.

This controller38governs the control of operations of individual circuitries inside the projector10and includes CPU, ROM storing fixedly operation programs of various settings, RAM that is used as a work memory, and the like.

Then, the controller38sends image signals of various standards which are inputted from an input/output connector unit21via the input/output interface22and a system bus (SB) to the image transforming module23, where the image signals are transformed so as to be unified into an image signal of a predetermined format which is suitable for display. Thereafter, the controller38outputs the unified image signal to the display encoder24.

The display encoder24deploys the inputted image signal on a video RAM25for storage in it and generates a video signal from the contents stored in the video RAM25, outputting the video signal so generated to the display driver26.

The display driver26functions a display device controller and drives a display device51, which is a spatial optical modulator (SOM), at an appropriate frame rate corresponding to the image signal outputted from the display encoder24.

Then, in the projector10, pencils of light emitted from a light source unit60are shone onto the display device51by way of an optical system to form an optical image by reflecting light from the display device51, and the image so formed is then projected onto a screen, not illustrated, for display by way of a projection-side optical system. A movable lens group235of the projection-side optical system is driven by a lens motor45for zooming and focusing.

An image compression/expansion unit31performs a recording process in which a luminance signal and a color difference signal of an image signal are data compressed through Adaptive Discrete Cosine Transform (ADCT) and Huffman coding processes, and the compressed data is sequentially written on a memory card32which constitutes a detachable recording medium.

Further, with the projector10set in a reproducing mode, the image compression/expansion unit31reads out the image data recorded in the memory card32and expands the individual image data that makes up a series of dynamic images frame by frame. Then, the image compression/expansion unit31outputs the image data to the display encoder24by way of the image transforming module23and enables the display of dynamic images based on the image data stored in the memory card32.

Then, operation signals from a keys/indicators unit37including main keys and indicators which are provided on a casing of the projector10are sent out directly to the controller38. Key operation signals from a remote controller are received by an IR reception unit35and are then demodulated into a code signal at an IR processing unit36for output to the controller38.

An audio processing unit47is connected to the controller38by way of a system bus (SB). This audio processing unit47includes a circuitry for a sound source such as a PCM sound source. With the projector10set in a projection mode and the reproducing mode, the audio processing unit47converts audio data into analog signals and drives a speaker48to output loudly sound or voice based on the audio data.

The controller38controls a light source control circuit41, which is configured as a light source control unit. The light source control circuit41controls individually a red light source device, a green light source device, and a blue light source device of the light source unit60so that light in predetermined wavelength ranges is emitted from the light source unit60so as to generate an image as required.

Further, the controller38causes a cooling fan drive control circuit43to detect temperatures through a plurality of temperature sensors which are provided in the light source unit60so as to control the revolution speeds of cooling fans based on the results of the temperature detections. Additionally, the controller38also causes the cooling fan drive control circuit43to keep the cooling fans revolving by use of a timer or the like even after a power supply to a main body of the projector10is switched off. Alternatively, the controller38causes the cooling fan drive control circuit43to cut off the power supply to the main body of the projector10depending upon the results of the temperature detections by the temperature sensors.

Next, an internal structure of the projector10will be described.FIG. 2is a schematic plan view illustrating the internal structure of the projector10. Here, the casing of the projector10has a substantially box-like shape and includes an upper and lower panels, a front panel12, a rear panel13, a right panel14, and a left panel15. In the following description, when left and right are referred to in relation to the projector10, they denote, respectively, left and right directions with respect to a projecting direction of the projector10. When front and rear are referred to in relation to the projector10, they denote, respectively, front and rear directions with respect to the direction of a screen and a traveling direction of a pencil of light from the projector10.

The projector10includes the light source unit60at a central portion, and a lens barrel225of a projection-side optical system220is provided to the left of the light source unit60. The projector10includes the display device51, which is a Digital Micromirror Device (DMD), between the lens barrel225and the rear panel13. The projector10includes a heat sink191configured to cool the display device between the display device51and the rear panel13. Further, the projector10includes a main control circuit board, not shown, below the light source unit60.

The light source unit60is made up of a green light source device80configured to emit light having a wavelength in the green wavelength range or simply light in the green wavelength range, a red light source device120configured to emit light having a wavelength in the red wavelength range or simply light in the red wavelength range, a blue light source device300configured to emit light having a wavelength in the blue wavelength range or simply light in the blue wavelength range, and alight guiding optical system140. The green light source device80is made up of an excitation light shining device70and a luminescent plate device100.

The excitation light shining device70is disposed substantially central in a left-right direction of the projector10and near the rear panel13. The excitation light shining device70is made up of two blue laser diodes71, which are semiconductor light emitting elements. The two blue laser diodes71are disposed side by side in the left-right direction in such a manner that optical axes thereof are at right angles to the rear panel13. Then, a heat sink81is disposed between the laser diodes71and the rear panel13. Collimator lenses73are disposed individually on the optical axes of the blue laser diodes71, and these collimator lenses73convert light emitted from the corresponding blue laser diodes71into parallel light so as to enhance the directivity of light emitted from the blue laser diodes71. A cooling fan261is disposed between the heat sink81and the rear panel13. The blue laser diodes71are cooled by the cooling fan261and the heat sink81.

The luminescent plate device100emits light in the green wavelength range as a result of excitation light being shone on thereto from the excitation light shining device70. The luminescent plate device100is disposed on an optical path of excitation light emitted from the excitation light shining device70and near the front panel12. The luminescent plate device100includes a luminescent material plate member110and a collective lens group111. The luminescent material plate section101includes a luminescent material plate101, and this luminescent material plate101is disposed so as to be parallel to the front panel12, that is, so as to be at right angles at an axis of light emitted from the excitation light shining device70. The collective lens group111collects a pencil of excitation light emitted from the excitation light shining device70on to the luminescent material plate101and collects a pencil of luminescent light in the green wavelength range which is emitted from the luminescent material plate member110in the direction of the rear panel13. The luminescent material plate member110of the luminescent plate device100will be described in detail later. A cooling fan261is disposed between the luminescent material plate member110and the front panel12. The luminescent plate device100and the like are cooled by this cooling fan261.

The red light source device120includes a red light source121and a collective lens group125configured to collects light emitted from the red light source121. The red light source121is a red light emitting diode which is a semiconductor light emitting element emitting light in the red wavelength range. Then, the red light source device120is disposed in such a manner that an axis of light in the red wavelength range which is emitted from the red light source121of the red light source device120intersects an axis of light in the blue wavelength range which is emitted from the blue light source device300and an axis of light in the green wavelength range which is emitted from the luminescent material plate101and is reflected by a first dichroic mirror141, which will be described later. Further, the red light source device120includes a heat sink130that is disposed at a side the red light source121which faces the rear panel13. A cooling fan261is disposed between the heat sink130and the rear panel13, and the red light source device121is cooled by the cooling fan261and the heat sink130.

The blue light source device300is disposed substantially central in a front-rear direction of the projector10and near the right panel14. The blue light source device300includes a blue laser diode301which is a semiconductor light emitting element and a collimator lens320, and this collimator lens320converts light emitted from the blue laser diode301into parallel light so as to enhance the directivity of light emitted from the blue laser diode301. Light emitted from the blue laser diode301by way of the collimator lens320is directed towards the left panel15in such a manner that an axis of the light so emitted becomes parallel to the front panel12. Consequently, light emitted from the blue light source device300intersects light emitted from the excitation light shining device70, light emitted from the luminescent plate device100and light emitted from the red light source device120at right angles. Then, a heat sink190is disposed at a side of the blue light source device300which faces the right panel14.

A heat sink135is disposed between cooling fans261disposed on a side of the luminescent plate device100which faces the front panel12and the front panel12, and this heat sink135extends from a position on a side of the cooling fan261which faces the front panel12to a side of the heat sink190which faces the front panel12. Then, a cooling fan261is disposed between a portion of the heat sink135which lies near the right panel14and the front panel12. The heat sinks135,190are cooled by this cooling fan261.

Then, the light guiding optical system140includes collective lenses configured to collect pencils of light in the red, green and blue wavelength ranges, and reflecting mirrors configured to change the axis of light in each of the red, green and blue wavelength ranges so that the axes of red light, green light and blue light are aligned. Specifically, the first dichroic mirror141is disposed in a position where the axis of light in the blue wavelength range which is emitted from the blue light source device300intersects the axes of light in the blue wavelength range which is emitted from the excitation light shining device70and light in the green wavelength range which is emitted from the luminescent plate device100at right angles. This dichroic mirror141transmits light in the blue wavelength range and reflects light in the green wavelength range and changes the axis of this green light through 90 degrees in the direction of the left panel15. The first dichroic mirror141aligns the axis of light in the blue wavelength range which is emitted from the blue light source device300with the axis of light in the green wavelength range which is emitted from the luminescent plate device100so that the axes of the green light and the blue right are directed in the same direction.

Then, a second dichroic mirror142is disposed in a position where the axis of light in the blue wavelength range which is emitted from the blue light source device300and is transmitted through the first dichroic mirror141and the axis of light in the green wavelength which is emitted from the luminescent plate device100and is reflected by the first dichroic mirror141intersects the axis of light in the red wavelength range which is emitted from the red light source device120at right angles. This second dichroic mirror142transmits light in the blue wavelength range and light in the green wavelength range and reflects light in the red wavelength range to change the axis of the red light through 90 degrees in the direction of the left panel15. The second dichroic mirror142aligns the axis of light in the blue wavelength range which is emitted from the blue light source device300, the axis of light in the green wavelength range which is emitted from the luminescent plate device100and the axis of light in the red wavelength range which is emitted from the red light source device120with one another so that the axes of the green light, the blue right and the red light are directed in the same direction.

A diffuser plate144is disposed on a side of the second dichroic mirror142which faces the left panel15. The diffuser plate144diffuses light in each of the blue, green and red wavelength ranges. Then, a microlens array145is disposed on a side of the diffuser plate144which faces the left panel15. The microlens array145not only diffuses further light in each of the blue, green and red wavelength ranges but also superposes light which passes through the microlens array145on one another to uniformly distribute the intensity of light in each of the blue, green and red wavelength ranges.

In the microlens array of this embodiment, biconvex lenses each having a horizontally elongated rectangular shape when viewed from above are arranged into a lattice configuration. Then, a collective lens147is disposed on a side of the microlens array145which faces the left panel15. The collective lens147collects diffuse light of the uniform intensity which passes through the microlens array145down to an effective size of the display device51. In this way, the light guiding optical system140is made up of the first dichroic mirror141, the second dichroic mirror142, the diffuser plate144, the microlens array145, and the collective lens147.

A light source-side optical system170is disposed on a side of the rear panel13and near the left panel15and includes a light axis changing mirror173and a condenser lens174. The condenser lens174collects light emitted from the display device51and causes the light to be incident on the lens barrel225, and due to this, the condenser lens174is considered to constitute one constituent element of the projection-side optical system220.

Light emitted from the light source unit60is shone on to the light axis changing mirror173. On the other hand, the condenser lens174is provided in front of the display device51. Thus, light source light reflected by the light axis changing mirror173is shone on to the display device51effectively by the condenser lens174.

On light which is reflected on the display device51is emitted towards a screen as projection light by the projection-side optical system220. The lens barrel225of the projection-side optical system220includes a fixed lens group and the movable lens group235, which are incorporated in the lens barrel225, and thus, the lens barrel225is configured as a variable-focus lens. The movable lens group235is moved by the lens motor, which is a drive source, for zooming and focusing.

With the projector10configured as described heretofore, when light is emitted at different timings from the excitation light shining device70, which shines excitation light on to the luminescent material plate101of the luminescent plate device100, the red light source device120, and the blue light source device300, light in the red wavelength range, light in the green wavelength range, and light in the blue wavelength range are incident on the display device51by way of the light guiding optical system140and the light source-side optical system170, whereby the DMD, which is the display device51of the projector10, displays red light, green light and blue light in time division, thereby making it possible to project a color image on to the screen.

Next, referring toFIGS. 3A, 3B, the luminescent material plate member110of the luminescent plate device100will be described.FIG. 3Ais a diagram illustrating the luminescent material plate member110as viewed from an emerging side, andFIG. 3Bis a cross-sectional view illustrating a cross section taken along a line IIIb-IIIb inFIG. 3Aand as viewed in the same direction as a direction in which the luminescent material plate member110is viewed in the schematic plan view inFIG. 2. The luminescent material plate member110includes the luminescent material plate101, a joining plate102, and a heat sink103, which constitutes a heat dissipating member.

The luminescent material plate101has a substantially square plate-like shape when viewed from the front thereof as described inFIG. 3A. The luminescent material plate101can be formed using a ceramic binder in a green luminescent material. In addition, the luminescent material plate101can be formed using an inorganic material such as glass, a transparent resin binder, and the like.

The joining plate102has a substantially square plate-like shape when viewed from the front thereof as described inFIG. 3A. The luminescent material plate101is fixed to one side of the joining plate102in a substantially central position through brazing or the like. The joining plate102is made of a metallic base of copper, aluminum, or the like, and the side of the joining pate102where the luminescent material plate101is provided is mirror finished through silver deposition or the like. Consequently, when excitation light, which is light in the blue wavelength range, from the excitation light shining device70is shone on to the luminescent material plate101, a green luminescent material in the luminescent material plate101is excited, whereby light in the green wavelength range is emitted in every direction from the luminescent material plate101. At this time, luminescent light that is emitted towards an emitting direction, which is a direction in which the excitation light shining device70is disposed is emitted as it is as emerging light, and luminescent light emitted in an opposite direction to the emitting direction is reflected on a surface of the mirror-finished side of the joining plate102and is then emitted in the emitting direction.

The heat sink103is formed into a rectangular flat surface on one side thereof which faces a light emerging side of the luminescent material plate member110. In the front view ofFIG. 3A, the one side of the heat sink103and the one side and the other side of the joining plate102have the same shape. Multiple fins, not shown, are formed on the other side of the heat sink103. A heat dissipating member can also be made up of another device (a heat pipe or the like) having a heat dissipating function, in addition to the heat sink103.

A heat conductive area105is formed between the other side of the joining plate102and the one side of the heat sink103. Heat generated from the luminescent material plate101when excitation light is shone on thereto is conducted from the joining plate102to the heat sink103by way of the heat conductive area105. Specifically, the heat conductive area105is specified by a gap t1defined between sides h1, h2of the joining plate102, the other side of the joining plate102, and the one side of the heat sink103. Then, in this embodiment, a heat conductive layer106is disposed in the heat conductive area105. The heat conductive layer106thermally connects the joining plate102and the heat sink103together. The heat conductive layer106is formed into a thin sheet-like shape and is disposed so as to tightly adhere to the other side of the joining plate102and the one side of the heat sink103.

In the heat conductive layer106, an area of the heat conductive area105which corresponds to the luminescent material plate105is formed of a carbon sheet106a, and an area of the heat conductive area105which corresponds to a periphery of the area corresponding to the luminescent material plate101is formed of a thermal sheet106b. In this embodiment, the carbon sheet106aof the area of the heat conductive area105which corresponds to the luminescent material plate106is formed larger than the luminescent material plate101to some extent. Here, a heat conductivity of the carbon sheet106ain a direction from the joining plate102to the heat sink103is lower than that of the thermal sheet106b. In this way, the heat conductive layer106is formed by combining the materials having the different heat conductivities. Consequently, the heat conductivity of the area of the heat conductive area105which corresponds to the luminescent material plate101becomes lower than the heat conductivity of the periphery of the area of the heat conductive area105which corresponds to the luminescent material plate101.

Here, the carbon sheet106ahas a nature in which a heat conductivity in a horizontal direction (a direction intersecting the emitting direction at right angles, that is, an in-layer direction that is parallel to the one side and the other side of the joining plate102) is higher than a heat conductivity in a vertical direction (the emitting direction, that is, a normal direction to the one side and the other side of the joining plate102). On the other hand, the thermal sheet106bhas a heat conductivity that is uniform in both the horizontal direction and the vertical direction.

In the luminescent material plate member110formed in the way described heretofore, when excitation light is shone on to an illuminated spot S on the luminescent material plate101where excitation light is to be shone, heat is generated. Heat generated from the luminescent material plate101is conducted to the carbon sheet106aof the heat conductive layer106by way of the joining plate102. Since the carbon sheet106ahas the nature described above, in the heat transmitted to the carbon sheet106aby way of the joining plate102, one portion is conducted in a vertical direction as indicated by an arrow d1to arrive at the heat sink103, whereas most heat is conducted in a horizontal direction as indicated by arrows d2, d3. The heat conducted in the horizontal direction from the carbon sheet106ais conducted to the thermal sheet106band is then conducted to the heat sink103by way of the thermal sheet106bas indicated by arrows d4, d5.

FIGS. 4A, 4Billustrate schematic diagrams of thermal gradients (isotherms) in the joining plate102.

When heat generated in the luminescent material plate101is dissipated in the way described above, as illustrated inFIG. 4A, since heat is conducted in the horizontal direction from the luminescent material plate101, which is a heat generation source, a temperature on the other side of the joining plate102becomes close to a temperature on the one side of the joining plate102, whereby a thermal gradient becomes moderate on the front and rear of the joining plate102. Consequently, a difference in horizontal elongation due to thermal expansion between the one side and the other side of the joining plate102becomes small, whereby the generation of a warp in the joining plate102is suppressed.

As in the case of the conventional light source unit, in the event that the heat conductive layer106of the luminescent material plate member110is all formed o the thermal sheet106b, as illustrated inFIG. 4B, in the joining plate102, a concentric thermal gradient centered at the luminescent material plate101is generated in the horizontal direction, whereas a laminar thermal gradient is generated in the vertical direction. Then, a difference in elongation due to thermal expansion is generated between the front and rear of the joining plate102, whereby cracking or separation of the luminescent material plate101occurs.

FIRST MODIFIED EXAMPLE

Next, a modified example of the embodiment of the present invention will be described. As illustrated inFIG. 5A, a rectangular recessed portion103ais formed on one side of the heat sink103in an area of the heat conductive area15which corresponds to the luminescent material plate101, and the heat conductive layer106is provided so as to tightly adhere to the other side of the joining plate102and the one side of the heat sink103including the recessed portion103a. As this occurs, the heat conductive layer106can be formed only of the thermal sheet106b. Since the thermal sheet106bof the area of the heat conductive area105which corresponds to the luminescent material plate101is formed thicker than the thermal sheet106bof the periphery of the area of the heat conductive area105which corresponds to the luminescent material late101, a heat conductivity of the area of the heat conductive area105which corresponds to the luminescent material plate106becomes lower than a heat conductivity of the periphery of the area of the heat conductive area105which corresponds to the luminescent material plate101.

SECOND MODIFIED EXAMPLE

As illustrated inFIG. 5B, an irregular shape103bmade up of a continuous wavy shape is formed on the one side of the heat sink103in the area of the heat conductive area105which corresponds to the luminescent material plate101. Then, the heat conductive layer106which is now formed uniformly of the thermal sheet106bis provided to tightly adhere to the other side of the joining plate102, whereas the thermal sheet106bis brought into point contact with the irregular shape103bon the one side of the heat sink103, while the thermal sheet106bis brought into surface contact with a periphery of the irregular shape103b(the periphery of the area of the heat conductive area105which corresponds to the luminescent material plate101) which is formed flat while tightly adhering thereto. In this modified example, too, a heat conductivity of the area of the heat conductive area105which corresponds to the luminescent material plate101becomes lower than a heat conductivity of the periphery of the area of the heat conductive area105which corresponds to the luminescent material pate101.

On the contrary to the example illustrated inFIG. 5B, an irregular shape is formed on the one side of the heat sink103on the periphery of the area of the heat conductive area105which corresponds to the luminescent material plate101, while the area of the heat conductive area105which corresponds to the luminescent material plate101is formed into a flat surface. Then, the heat conductive layer106is brought into surface contact with both the irregular shape and the flat surface while tightly adhering thereto. This increases an area where the thermal sheet106b, which is the heat conductive layer106, is brought into contact with the one side of the heat sink103on the irregular shape, and hence, in this case, too, a heat conductivity of the area of the heat conductive area105which corresponds to the luminescent material plate101becomes lower than a heat conductivity of the periphery of the area of the heat conductive area105which corresponds to the luminescent material pate101.

The heat conductive layer106on the heat conductive area105may not tightly adhere wholly to the other side of the joining plate102and the one side of the heat sink103, and a space may be formed at part of the heat conductive area105.

Thus, according to the embodiment of the present invention, the light source unit60includes the luminescent material plate101, the joining plate102on the one side of which the luminescent material plate101is disposed, and the heat conductive area105including the heat conductive layer106, and the heat conductivity of the area of the heat conductive area105which corresponds to the luminescent material plate101is lower than the heat conductivity of the periphery of the area of the heat conductive area105which corresponds to the luminescent material plate101.

Due to this, in the area of the heat conductive area105which corresponds to the luminescent material plate101, in the heat generated from the luminescent material plate101, the conduction of the heat in the vertical direction is interrupted, whereby the thermal gradient becomes moderate on the front and rear of the joining plate102, and this suppresses the difference in elongation due to thermal expansion between the front side and the rear side of the joining plate102, thereby reducing the risk of a warp being generated in the joining plate102. Consequently, even though the luminescent material layer101is illuminated by excitation light shone on thereto, the risk of cracking or separation of the luminescent material plate101is reduced.

In addition, the horizontal heat conductivity of the area of the heat conductive area105which corresponds to the luminescent material plate101can be made higher than the vertical heat conductivity. This can suppress the difference in elongation due to thermal expansion between the front side and the rear side of the joining plate102.

The heat conductive layer106can be formed by combining materials having different heat conductivities. As a result, since the other side of the joining plate102and the one side of the heat sink103can be formed flat, the fabrication of the joining plate102and the heat sink103can be facilitated.

In the heat conductive layer106, the area of the heat conductive area105which corresponds to the luminescent material plate101is formed of the carbon sheet106a, while the periphery of the area of the heat conductive area105which corresponds to the luminescent material plate101is formed of the thermal sheet106b. As a result, since the heat conductive layer106can be formed into a single sheet-like shape, the assembly of the luminescent material plate member110can be improved.

In the heat conductive layer106, the thickness of the area of the heat conductive area105which corresponds to the luminescent material plate101is thicker than the thickness of the periphery of the area of the heat conductive area105which corresponds to the luminescent material plate101. In addition, the continuous irregular shape103bis formed on the one side of the heat sink103which constitutes the portion corresponding to the area of the heat conductive area105which corresponds to the luminescent material plate101. As a result, the heat conductive layer106can be formed only of a single material as can be formed only of the thermal sheet106b, and therefore, the fabrication of the heat conductive layer106can be facilitated.

The heat sink103can be used as the heat dissipating member. As a result, the heat sink103including the multiple fins can be formed through extrusion molding, and therefore, the fabrication of the heat sink103can be facilitated.

The projector10includes the light source unit60, the display device51, the projection-side optical system220, and the projector control unit. As a result, the generation of thermal stress resulting from shining excitation light is reduced, whereby the projector10can be provided which includes the light source unit60in which cracking or separation of the luminescent material plate101is reduced.

While the embodiment of the present invention has been described heretofore, the embodiment including the modified examples is presented as an example, and hence, there is no intention to limit the scope of the present invention by the embodiment. This novel embodiment can be carried out in other various forms, and various omissions, replacements and modifications can be made to the embodiment without departing from the spirit and scope of the invention. Those resulting embodiments and their modifications are included in the spirit and scope of the present invention and are also included in the scope of inventions claimed for patent under claims below and their equivalents.