Light source unit and projector

The invention includes an excitation light source, a light distribution adjusting member on which excitation light from the excitation light source is incident, and a luminescent material which emits luminous light of a different wavelength from that of the excitation light by the excitation light which passes through the light distribution adjusting member being shone on thereto, wherein the excitation light source is disposed so that the excitation light is incident on a light incident surface of the light distribution adjusting member at a predetermined angle.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority under 35 USC 119 of Japanese Patent Application No. 2012-206666 filed on Sep. 20, 2012, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light source unit capable of emitting a pencil of light having high in-plane uniformity and a projector.

2. Description of the Related Art

In these days, data projectors are used on many occasions as an image projection unit which projects images including an image of a screen and a video image of a personal computer, as well as images based on image data which is stored in a memory card on to a screen. In these data projectors, light emitted from a light source is caused to converge to a micromirror display element called a DMD (Digital Micromirror Device) or a liquid crystal panel so that a color image is displayed on a screen.

Conventionally, the mainstream of these projectors has been those which utilize a high-intensity discharge lamp as a light source. In recent years, however, there have been made various developments on projectors which use, as a light source, a light emitting diode, a laser diode, an organic EL device or a luminescent material.

The applicant of this patent application proposes in JP-A-2012-42964 a light source unit which includes a blue laser emitting device as an excitation light source, a luminescent wheel on which a luminous light emitting area is disposed circumferentially which is formed by laying a green luminescent material on a reflecting surface, and a red light emitting diode and a blue light emitting diode. In this proposal, light emitted from the red light emitting diode constitutes light source light of a range of red wavelengths, light emitted from the blue light emitting diode constitutes a light source light of a range of blue wavelengths, and luminous light emitted from the green luminescent material by using light emitted from the blue light emitting device as excitation light constitutes light source light of a range of green wavelengths.

Although the light source unit uses the blue laser emitting device and the green luminescent material as a green light source, when blue laser light functioning as excitation light is shone on to the luminescent material, unevenness in in-plane uniformity of light is produced in the whole of the pencil of light as excitation light, and therefore, it has been difficult to ensure the in-plain uniformity of luminous light emitted from the luminescent material as well.

SUMMARY OF THE INVENTION

The present invention has been made in view of these situations and an object thereof is to provide a high-intensity light source unit which can emit a pencil of light of higher in-plane uniformity by eliminating the problem described above and hence a projector which enables the projection of an image of little unevenness in luminance.

According to a preferred aspect of the invention, there is provided a light source unit having an excitation light source, a light distribution adjusting member on which excitation light from the excitation light source is incident, and a luminescent material which emits luminous light of a different wavelength from that of the excitation light by the excitation light which passes through the light distribution adjusting member being shone on thereto, wherein the excitation light source is disposed so that the excitation light is incident on a light incident surface of the light distribution adjusting member at a predetermined angle.

Further, according to another preferred aspect of the invention, there is provided a projector including a light source unit, a light-source-side optical system which guides light from the light source unit to a display element, a display element which forms an optical image by light shone on thereto, a projection-side optical system which projects an optical image formed by the display element on to a screen, and a projector control unit having a light source control device for the light source unit and a display element control device, wherein the light source unit is the light source unit according to the preferred aspect of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, a best mode for carrying out the invention will be described by the use of the accompanying drawings. However, although various limitations which are technically preferable to carry out the invention are given to an embodiment which will be described below, the scope of the invention should not be limited at all to the following embodiment and illustrated examples shown in the accompanying drawings.

A best mode of a light source unit for a projector according to the invention has, as shown inFIG. 3, excitation light sources70, a light tunnel81as a light distribution adjusting member through which excitation light from the excitation light sources70passes, and a luminescent wheel101which includes a luminescent material on to which excitation light which passes through the light tunnel81is shone. Then, luminous light emitted from the luminescent material by excitation light or the like passes through the light tunnel81in an opposite direction to the direction in which excitation light passes therethrough. The luminescent material is formed on the luminescent wheel101as an annular luminescent material layer103, and this annular luminescent material layer103is disposed on the luminescent wheel101so as to extend along a circumferential edge thereof in such a way as to be arranged continuously with an arc-shaped diffuse reflection portion105in an end-to-end fashion.

Then, the excitation light sources70each use a plurality of blue light sources71which are laser emitting devices which emit light of a range of blue wavelengths. The luminescent material is a luminescent material which emits light of a range of green wavelengths. A dichroic mirror91is provided between the light tunnel81and the luminescent wheel101, and this dichroic mirror91reflects light of a range of red wavelength and transmits light of the range of blue wavelengths and light of the range of green wavelengths. Light of a range of red wavelengths emitted from a red light emitting device120is reflected by the dichroic mirror91so that the direction of an axis of luminous light which passes through the dichroic mirror91and the direction of an axis of light of the range of red wavelengths coincide with each other.

Hereinafter, an embodiment of the invention will be described in detail based on the drawings.FIG. 1is an external perspective view of a projector10. In this embodiment, when left and right are referred to with respect to the projector10, they denote, respectively, left and right with respect to a projecting direction, and when front and rear are referred to with respect to the projector10, they denote, respectively, front and rear with respect to a direction towards a screen and the traveling direction of a pencil of light emitted from the projector10towards the screen.

As is shown inFIG. 1, the projector10has a substantially rectangular parallelepiped shape. The projector10has a lens cover19for covering a projection port which is laid to a side of a front panel12which is referred to as a front side panel of a projector casing. Additionally, a plurality of outside air inlet slits18are provided in the front panel12. Further, although not shown, the projector10includes an Ir reception unit which receives a control signal from a remote controller.

In addition, a keys/indicators unit37is provided on an upper panel11of the projector casing. Disposed on this keys/indicators unit37are keys and indicators which include a power supply switch key, a power indicator which informs whether the power supply is on or off, a projection switch key which switches on or off the projection by the projector, and an overheat indicator which informs of an overheat condition when the light source unit, the display element, a control circuit or the like overheats.

Further, provided in a back side or a back panel of the projector casing are an input/output connector unit where USB terminals, an image signal input D-SUB terminal, an S terminal, an RCA terminal and the like are provided and various types of terminals20including a power supply adaptor plug. Additionally, a plurality of outside air inlet slits18are formed in the back panel. A plurality of inside air outlet slits17are formed in each of a right panel, not shown, which is a side panel of the projector casing and a left panel15which is a side panel shown inFIG. 1. In addition, outside air inlet slits18are also formed in a portion of the left panel15which lies in a corner portion formed between the back panel and the left panel15.

Next, the projector control unit of the projector10will be described by the use of a functional block diagram shown inFIG. 2. The projector control unit includes a control module38, an input/output interface22, an image transforming module23, a display encoder24, a display drive module26and the like, whereby image signals of various standards that are inputted from an input/output connector unit21are sent via the input/output interface22and a system bus (SB) to the image transforming module23where the image signals are transformed so as to be unified into an image signal of a predetermined format which is suitable for display by the projector control unit. Thereafter, the image signals so transformed are outputted to the display encoder24.

The display encoder24deploys the image signals that have been inputted thereinto on a video RAM25for storage therein and generates a video signal from the contents stored in the video RAM25, outputting the video signal so generated to the display drive module26.

The display drive module26functions as a display element control module and drives the display element51, which is a spatial optical modulator (SOM), at an appropriate frame rate in response to the image signal outputted from the display encoder24.

In this projector10, a pencil of light which is emitted from a light source unit60is shone on to a display element51via a light-source-side optical system to thereby form an optical image based on reflected light which is reflected by the display element51. The image so formed is then projected on to a screen, not shown, for display thereon via a projection-side optical system, which will be described later. In addition, a movable lens group235of the projection-side optical system is driven by a lens motor45for zooming or focusing.

An image compression/expansion module31performs a recording operation in which a luminance signal and a color difference signal of an image signal are data compressed through processing such as ADCT and Huffman coding and the compressed data is sequentially written on a memory card32which is configured as a detachable recording medium. Further, when in a reproducing mode, the image compression/expansion module31reads out image data recorded on the memory card32and expands individual image data which make up a series of dynamic images frame by frame. Then, the image data is outputted to the display encoder24via the image transforming module23so as to enable the display of dynamic images based on the image data stored on the memory card32.

The control module38governs the control of respective operations of circuitries within the projector10and is made up of a CPU, a ROM which stores in a fixed fashion operation programs of various types of settings and a RAM which is used as a work memory.

Operation signals generated at the keys/indicators module37which is made up of the main keys and indicators provided on the upper panel11of the projector casing are sent out directly to the control module38. Key operation signals from the remote controller are received by the Ir reception unit35, and a code signal demodulated at an Ir processing module36is outputted to the control module38.

In addition, an audio processing unit47is connected to the control module38via the system bus (SB). This audio processing module47includes a circuitry for a sound source such as a PCM sound source. When in a projection mode and a 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 control module38controls a light source control circuit41which is configured as a light source control unit. This light source control circuit41controls individually the emission of light from the light emitting elements of the excitation light source devices70of the light source unit60and a light emitting element of the red light emitting device120so that light source light of predetermined ranges of wavelengths which is required when an image is generated is emitted from the light source unit60. Further, the control module38controls a wheel motor110to drive rotationally the luminescent wheel101which is a rotational member of a luminous light emitting device100.

Further, the control module38causes a cooling fan drive control circuit43to detect temperatures through a plurality of temperature sensors which are provided in the light source unit60and the like so as to control individually the rotating speed of cooling fans based on the results of the temperature detection. Additionally, the control module38also causes the cooling fan drive control circuit43to keep the cooling fan rotating even after the power supply to a projector main body is switched off by use of a timer or the like. Alternatively, the control module38controls whether to cut off the power supply to the projector main body depending upon the results of the temperature detections by the temperature sensors.

Next, an internal construction of the projector10will be described.FIG. 3is an exemplary plan view showing an internal construction of the projector10. As shown inFIG. 3, the projector10includes a control circuit board241in proximity to the right panel14. This control circuit board241includes a power supply circuit block, a light source control block and the like. Additionally, the projector10includes the light source unit60, in a substantially central portion of the projector casing.

Further, the projector10includes a light-source-side optical system180and a projection-side optical system220between the light source unit60and the left panel15. In addition, the projection-side optical system220is disposed along the left panel15, and the display element51, which is a DMD (Digital Micromirror Device), is provided at the rear of the projection-side optical system220and near the back panel13, whereby light emitted from the light source unit60is guided to the display element51by the light-source-side optical system180.

As shown inFIGS. 3 and 4, the light source unit60includes the excitation light source devices70which are disposed in a substantially central portion with respect to a left-to-right direction of the projector casing and near the back panel13, the light tunnel81, which is the light distribution adjusting member, disposed substantially in the center of the projector casing, a collective lens83disposed on a side of the light tunnel81which faces the back panel13and a collective lens85disposed on a side of the light tunnel81which faces the front panel12, and the luminous light emitting device100disposed near to the front panel12so that a pencil of light emitted from the excitation light source device70is shone on to the luminous light emitting device100via the light tunnel81.

Further, the light source unit60also includes the red light emitting device120disposed between the excitation light source devices70and the luminous light emitting device100and the dichroic mirror91(corresponding to a first dichroic mirror) disposed between the light tunnel81and the luminous light emitting device100. The dichroic mirror91reflects light of the range of red wavelengths and transmits light of the range of blue wavelengths and light of the range of green wavelengths. Then, the dichroic mirror91reflects light emitted from the red light emitting device120so that the axis of the red light coincides with the axis of light emitted from the luminous light emitting device100, whereby light of the ranges of red, green and blue wavelengths is allowed to pass through the light tunnel81for emission from the light source unit60.

In addition, the light source unit60as shown inFIGS. 3 and 4has a light axis changing mirror181of the light-source-side optical system180which is located between the excitation light source device70and the light tunnel181and which is supposed to be situated on an central axis which coincides with an optical axis of the light tunnel81.

The excitation light sources70each include a light source group made up of a plurality of blue light sources71as excitation light sources which are disposed near the back panel13and heat sinks98,190which are disposed between the blue light sources71and the right panel14and near the back panel13, respectively.

In the light source group, collimator lenses73are disposed individually on respective optical axes of the blue light sources71, and the collimator lenses73convert light emitted from the corresponding blue light sources71into substantially parallel light so as to enhance the directivity of the light. Additionally, a cooling fan261is disposed between the heat sink98and the back panel13, and the blue light sources71of the excitation light source devices70are cooled by the cooling fan261and the heat sinks98,190.

Then, respective pencils of light emitted from the blue light sources71are caused to enter the light tunnel81, which is the light distribution adjusting member, obliquely via the collective lens83. This light tunnel81is such that light entering the light tunnel81is internally reflected a plurality of times in an interior thereof so as to enhance the in-plane uniformity of light which is to emanate therefrom.

In addition, light emitted from the excitation light source devices70enters the light tunnel81via the collective lens83after passing by sides of the light axis changing mirror181of the light-source-side optical system180which is disposed on the central axis of the light tunnel81.

Consequently, excitation light which enters the light tunnel81is reflected a plurality of times on an inner wall of the light tunnel81, whereafter the excitation light is shone on to the luminescent wheel101of the luminous light emitting device100via the collective lens85.

In this embodiment, the excitation light sources are disposed by adjusting the position and orientation of the blue light sources71and the orientation and position of the collimator lenses73so that respective pencils of light emitted from the blue light sources71do not enter the light axis changing mirror181but enter a light incident surface of the light tunnel81.

Alternatively, the diffuse reflection area of the luminescent wheel101, which will be described in details later, may be converted into an area of a luminescent material which emits blue light of a different range of blue wavelengths from that of light emitted from the blue light sources71by light from the blue light sources71being shone on thereto. In addition, the light axis changing mirror181may be converted into a dichroic mirror which transmits light from the excitation light sources and reflects light of the range of green wavelengths and light of the range of blue wavelengths which are emitted from the luminescent wheel101and light of the range of red wavelengths which is emitted from the red light emitting device120.

In this way, by causing respective pencils of light emitted from the blue light sources71to enter the light incident surface of the light tunnel81obliquely, the excitation light that enters the light tunnel81in that way is allowed to be reflected a certain number of more of times within the light tunnel81so as to preferably enhance the in-plane uniformity of the excitation light emanating from the light tunnel81.

In addition, as shown inFIG. 4, the plural pairs of blue light sources71are disposed in symmetrical positions with respect to a straight line which passes through a middle point of the light incident surface of the light tunnel81and which is normal to the light incident surface, whereby the pairs of blue light sources71are disposed inclined at the same angle towards the light tunnel81. Namely, a pencil of excitation light emitted from one of the pairs of blue light sources71enters the light tunnel81while being inclined at a first angle with respect to the straight line normal to the light incident surface of the light tunnel81, and a pencil of excitation light emitted from the other pair of blue light sources71enters the light tunnel81while being inclined at a second angle which is equal in magnitude to the first angle with respect to the straight line normal to the light incident surface.

By disposing the blue light sources71in this way, light shone from the pairs of blue light sources71which are disposed in the symmetrical positions with respect to the central axis of the light tunnel81can be reflected the same number of times within the light tunnel81, thereby making it possible to preferably enhance the in-plane uniformity of light which is to emanate from the light tunnel81.

The entry of pencils of excitation light into the light tunnel81is not limited to the entry with the axes of the pencils of excitation light from the pairs of blue light sources71inclined symmetrically with respect to the central axis of the light tunnel81, and hence, any type of entry of excitation light should be accepted as long as excitation light from the pairs of blue light sources71enters the light incident surface of the light tunnel81and then passes through the light tunnel81to be collected to a required position on the luminescent wheel101by the collective lens85. Thus, there may be a situation in which angles of incidence differ from each other at which pencils of excitation light from the pairs of blue light sources71enter the light tunnel81.

The luminous light emitting device100includes the luminescent wheel101, which is the rotational member thereof, disposed so as to be parallel to the front panel12or intersect the central axis of the light tunnel81at right angles, the wheel motor110which drives rotationally the luminescent wheel101and a group of collective lenses111which not only collects a pencil of light emanating from the light tunnel81to the luminescent wheel101but also collets a pencil of light emitted from the luminescent wheel101in the direction of the back panel13.

The luminescent wheel is formed by using a thin circular disk-shaped metallic base of copper, aluminum or the like. As shown inFIG. 5, the luminescent material103and the diffuse reflection portion105are provided on one side of the luminescent wheel101so as to be disposed circumferentially along a circumferential edge of the luminescent wheel101in an end-to-end fashion. The luminescent material103is configured as a green luminous light emitting area which emits luminous light of the range of green wavelength by receiving light emanating from the light tunnel81as excitation light. The diffuse reflection portion105is configured as a diffuse reflection area which reflects light shone on thereto from the light tunnel81while diffusing it.

A portion of a surface of the base which faces the back panel13where the green luminous light emitting area is to be formed is mirror finished through silver deposition. The luminescent material103, which is the green luminescent material, is laid on the mirror-finished surface. Further, minute irregularities are formed on a portion of the surface of the metallic base where the diffuse reflection area is to be formed through sandblasting, whereby the diffuse reflection portion105is formed which reflects incident light while diffusing it.

It is noted that there may be a situation in which the diffuse reflection area is converted into a light transmitting diffuse reflection portion by forming a diffuse transmission layer which transmits light while diffusing it on a mirror-finished surface of the metallic base which is mirror finished in a similar way to that in which the green luminous light emitting area is done. The light transmitting diffuse reflection area so formed functions in the same way as that of the diffuse reflection portion105which is subjected to sandblasting and hence reflects incident light while diffusing it.

Then, light shone on to the green luminous light emitting area on the luminescent wheel101from the excitation light source devices70by way of the light tunnel81excites the green luminescent material in the green luminous light emitting area to emit green luminous light. Pencils of green luminous light are emitted from the green luminescent material in every direction, and some travel directly towards the back panel13and others are reflected on the surface of the luminescent wheel101so as to travel towards the back panel13. Thereafter, these pencils of green luminous light enter the group of collective lenses111to be collected and emanate therefrom towards the light tunnel81, as shown inFIG. 6.

Light shone on to the diffuse reflection area of the luminescent wheel101from the excitation light source devices70enters the group of collective lenses111as diffused reflected light which is diffused by the minute irregularities to be collected and thereafter emanates therefrom towards the light tunnel81. A cooling fan261is disposed between the wheel motor110and the front panel12, whereby the luminous light emitting device100and the like are cooled by this cooling fan261.

The red light emitting device120is a monochromatic light emitting device which includes the red light emitting element121which is disposed so that an optical axis thereof intersects the axis of light emanating from the light tunnel81at right angles and a group of collective lenses125which collects light emitted from the red light emitting element121. This red light emitting element121is a red light emitting diode which emits light of a range of red wavelengths.

As shown inFIG. 6, light emitted from the red light emitting device120is shone on to the dichroic mirror91to be reflected by the dichroic mirror91and enters the light tunnel81via the collective lens85with the axis of the red light caused to coincide with the axis of luminous light which is light of the range of green wavelengths emitted from the luminescent wheel101and the axis of light of the range of blue wavelengths reflected by the luminescent wheel101.

The red light emitting device120includes a heat sink130which is disposed at a side of the red light emitting element12which faces the right panel14. Additionally, a cooling fan261is disposed between the heat sink130and the front panel12, whereby the red light emitting element121is cooled by this cooling fan261. It is noted that inFIG. 6, although pencils of luminous light emitted in every direction from the green luminescent material, light shone on to the diffuse reflection area from the excitation light source devices70, and light emitted from the red light emitting device120are shown only by their central axes, in reality, it is, of course, natural to think that the light emitted from the luminescent material and the light source and light emitting devices passes through the light tunnel81while being reflected internally.

In addition, the light-source-side optical system180is designed to guide light emitted from the light source unit60to the display element51and includes, as shown inFIG. 3, the light axis changing mirror181, the collective lens183and a light shining mirror185.

The light axis changing mirror181is disposed on the optical axis of the light tunnel81and is designed to reflect light of the range of red wavelengths, light of the range of green wavelengths and light of the range of blue wavelengths which emanate from the light tunnel81and pass through the collective lens183in the direction of the left panel15so as to change the axes of the red, green and blue light emanating from the light tunnel81towards the back panel13in the direction of the left panel15.

Then, the red, green and blue light reflected by the light axis changing mirror181is shone on to the light shining mirror185via the collective lens183and is shone on to the display element51, which is the DMD, by the light shining mirror185. Then, red, green and blue images are formed based on the light in the display element51, and the light forming these monochromatic images of the three primary colors is caused to enter the projection-side optical system220.

A heat sink190to cool the display element51is disposed between the display element51and the back panel14, whereby the display element51is cooled by this heat sink190. Additionally, a collective lens195as part of the projection-side optical system220is disposed near the front of the display element51.

The projection-side optical system220is a variable-focus lens which includes a group of fixed lenses225which is incorporated in a fixed lens barrel and a group of movable lenses235which is incorporated in a movable lens barrel, thus a zooming function being given to the variable-focus lens. The group of movable lenses235is moved by a lens motor for zooming and focusing.

By configuring the projector10in this way, when the luminescent wheel101is rotated and light is emitted at different timings from the excitation light source devices70and the red light emitting device120, light of the range of red wavelength, light of the range of green wavelengths and light of the range of blue wavelengths are caused to enter sequentially the light tunnel81so as to enhance the respective in-plane uniformities of the red, green and blue light, whereafter the red, green and blue light enters the display element51via the light-source-side optical system180.

Because of this, the DMD, which is the display element51of the projector10, forms red, green and blue images according to data, and by superposing the monochromatic images free from unevenness of luminance one on top of another, a color image can be produced on the screen.

In the embodiment, while the light-source-side optical system180which guides light emitted from the light source unit60to the display element51is described as having the light axis changing mirror181, so that the axes of red light, green light and blue light emanating from the light tunnel81towards the back panel13are changed in the direction of the left panel15, by adopting a light source unit60in which an central axis of a light tunnel81is made substantially parallel to the back panel13as shown inFIG. 7, a light-source-side optical system180is realized from which the light axis changing mirror181is omitted, so that luminous light which passes through the light tunnel81, which is the light distribution adjusting member, or the like is shone directly on to the display element51from the light source unit60via a collective lens183of the light-source-side optical system180.

Further, in the embodiment, while the luminescent wheel101is described as being disposed on the central axis of the light tunnel81and luminous light and reflected light emitted from and reflected by the luminescent wheel101and light emitted from the red light emitting device120are described as being caused to pass through the light tunnel81through which excitation light from the excitation light source devices70is allowed to pass so as to be shone on to the luminescent wheel101in the opposite direction to the direction in which excitation light passes therethrough, as in a conventional light source unit, a light tunnel153exclusive for light to be emitted from the light source unit60may be provided as shown inFIG. 8so that light to be emitted from the light source unit60passes therethrough to be reflected a plurality of times in an interior thereof so as to enhance the in-plane uniformity of such light.

As this occurs, the dichroic mirror91which is disposed on the axis of light emitted from the red light emitting device120is converted into a dichroic mirror91which reflects luminous light emitted from the luminescent wheel101of the luminous light emitting device100and transmits excitation light and light of the range of red wavelengths emitted from the red light emitting device120, so that the axis of light of the range of red wavelengths emitted from the red light emitting device120and the axis of light of the range of green wavelengths emitted from the luminescent wheel101are caused to coincide with each other in a direction which differs from the axis of excitation light.

Further, a second dichroic mirror147is disposed in a position where the axis of light of the range of red wavelength emitted from the red light emitting device120which has passed through the dichroic mirror91intersects the axis of light of a range of blue wavelengths emitted from a blue light emitting device140. This second dichroic mirror147reflects luminous light emitted from the luminescent wheel101of the luminous light emitting device100and light of the range of red wavelengths emitted from the red light emitting device120whose axes are caused to coincide with each other by the dichroic mirror91and transmits light of the range of blue wavelengths.

In this way, light of the range of blue wavelengths from the blue light emitting device140is added to light of the range of red wavelengths and light of the range of green wavelengths by the second dichroic mirror147. Then, light of the ranges of red, green and blue wavelengths, which are the three primary colors, is caused to enter the light tunnel153exclusive for light to be emitted from the light source unit60for emission therefrom. Separately from the light tunnel153exclusive for light to be emitted, a light tunnel81exclusive for excitation light is disposed between excitation light sources70and the luminous light emitting device100, whereby excitation light is shone on to the luminescent wheel101via this light tunnel81.

The blue light emitting device140is a monochromatic light emitting device which has a blue light emitting element141which is a blue light emitting diode and a group of collective lenses145which collects light emitted from the blue light emitting element141.

InFIG. 8, although pencils of luminous light emitted from the green luminescent material in every direction, light emitted from the blue light emitting device140and light emitted from the red light emitting device120are illustrated only by their central axes, in reality, it is, of course, natural to think that the light emitted from the luminescent material and the light emitting devices passes through the light tunnel153while being reflected internally.

In addition, when the blue light emitting device140is used, as the luminescent wheel101, the diffuse reflection portion105does not have to be formed thereon, and it is good enough to form only a luminescent material layer103which is an annular green luminous light emitting area along the full circumference of the luminescent wheel101.

In addition, the following configuration may be adopted. Only a green luminescent material is formed into an annular shape on the luminescent wheel101, and as a device for emitting light of a range of blue wavelengths, a blue light emitting device140which uses a light emitting diode which emits light of a range of blue wavelengths as the red light emitting device120does is disposed near the luminous light emitting device100together with the red light emitting device120. Then, as shown inFIG. 9, light of the range of blue wavelengths emitted from the blue light emitting device140is caused to enter the light tunnel81, which is the light distribution adjusting member, by using the second dichroic mirror147.

InFIG. 9, although pencils of luminous light emitted from the green luminescent material in every direction, light emitted from the blue light emitting device140and light emitted from the red light emitting device120are illustrated only by their central axes, in reality, it is, of course, natural to think that the light emitted from the luminescent material and the light emitting devices passes through the light tunnel81while being reflected internally.

In addition, in the embodiment, while the luminescent material layer103which is the green luminous light emitting area and the diffuse reflection portion105which is the diffuse reflection area are provided along the circumferential edge of the luminescent wheel101in the end-to-end fashion so as to be formed into an annular shape, a configuration may be adopted in which the diffuse reflection area is not formed, but a blue luminous light emitting area is formed by using a luminescent material which emits light of a range of blue wavelengths as a luminescent material which is applied on to a mirror-finished base.

When the luminescent material which emits light of the range of green wavelengths and the luminescent material which emits light of the range of blue wavelengths are formed into the annular shape on the luminescent wheel101in this way, as the excitation light sources, a laser emitting device is used which emits visible light of a shorter wavelength than those of light of the range of blue wavelengths or ultraviolet radiation.

Then, when laser emitting devices which output light of a shorter wavelength than those of light of the range of blue wavelengths such as ultraviolet light is used as the excitation light sources, a dichroic mirror which transmits light from the excitation light sources and reflects light of the range of green wavelengths and light of the range of blue wavelengths from the luminescent wheel101and light of the range of red wavelengths from the red light emitting device120is used as the light axis changing mirror181provided in the light-source-side optical system180.

In this way, by using the dichroic mirror181as the light axis changing mirror181of the light-source-side optical system180, when causing excitation light from the excitation light sources70to enter the light tunnel81, excitation light does not have to be restricted by the light axis changing mirror181of the light-source-side optical system180, that is, excitation light may enter the light axis changing mirror181of the light-source-side optical system180, whereby the excitation light sources can be disposed so as to facilitate the adjustment of their positions relative to the optical axis of the light tunnel81, which is the light distribution adjusting member, thereby making it possible to facilitate the design of arrangement of the laser emitting devices which constitute the excitation light sources.

Also when the dichroic mirror181is used as the light axis changing mirror181, the invention is not limited to the configuration in which light of the range of green wavelengths and light of the range of blue wavelengths are emitted from the luminescent wheel101, and hence, the configuration shown inFIG. 9may be adopted in which the luminescent material layer103which constitutes the green luminous light emitting area is provided on the luminescent wheel101and the blue light emitting device140which shines light of the range of blue wavelengths is additionally provided.

In addition, when the dichroic mirror181is used as the light axis changing mirror181, which transmits light from the excitation light sources and reflects light of the range of green wavelengths and light of the range of blue wavelengths which are emitted from the luminescent wheel101and light of the range of red wavelengths emitted from the red light emitting device120, there may a situation in which the red light emitting device120which uses the red light emitting element which is the red light emitting diode is omitted and a luminescent material layer made up of a luminescent material which emits light of the range of red wavelengths is formed on the luminescent wheel101together with the luminescent material layers made up of the luminescent materials which emit light of the range of green wavelengths and light of the range of blue wavelengths.

In addition, the light tunnel81, which is the light distribution adjusting member, is not limited to the light tunnel81, and hence, there may be a situation in which a light guiding rod which is a solid glass rod is used in place of the light tunnel81. Further, there may be a situation in which a microlens array is used as the light distribution adjusting member so as to make the intensity of light emanating therefrom distributed uniformly.

Further, in the embodiment, while the plurality of laser emitting devices are used as the excitation light sources, the invention is not limited to the use of the plurality of laser emitting devices. Hence, as shown inFIG. 11, a single laser emitting device may be used as the excitation light source. Incidentally, when the plurality of laser emitting devices are used, the in-plane uniformity in terms of luminance of light shone on to the luminescent wheel101can be enhanced through adjustment of respective positions of laser emitting devices.

In addition, when the plurality of laser emitting devices are used as the excitation light sources, the invention is not limited to the configuration in which the pairs of laser emitting devices are disposed substantially laterally symmetrical with respect to the central axis of the light tunnel81as shown inFIG. 4. Hence, the numbers of laser emitting devices to be disposed to the left and right of the central axis of the light tunnel81should be determined as required, and angles at which the axes of pencils of excitation light from the laser emitting devices intersect the central axis of the light tunnel81should also be determined as required.

In this way, in the case of the light source unit with the luminescent material according to this embodiment, since excitation light is shone on to the luminescent material via the light distribution adjusting member in shining excitation light on to the luminescent material, by allowing excitation light to pass through the light distribution adjusting member while being reflected in the interior thereof, the in-plane uniformity in terms of luminance of excitation light is enhanced, and hence, the in-plane uniformity of luminous light can be enhanced.

Consequently, it is possible to form a monochromatic image free from unevenness of luminance, thereby making it possible to provide the projector10which can project an image free from unevenness of luminance and a beautiful image free from partial color drift or partial unevenness of color.

In addition, by allowing excitation light to enter the light incident surface of the light distribution adjusting member such as the light tunnel81at a predetermined angle, the number of times of reflection of excitation light within the light distribution adjusting member can be adjusted, whereby the in-plane light distribution of excitation light emanating from the light distribution adjusting member can be made appropriate.

In addition, with luminous light caused to pass through the light distribution adjusting member in the opposite direction to the direction in which excitation light passes through it, the light distribution adjusting member can be used not only as the light distribution adjusting member which is required to make uniform light of the ranges of red, green and blue wavelengths which is to emanate from the light source unit but also as the light distribution adjusting member which distributes the intensity of excitation light uniformly, thereby making it possible to facilitate the reduction in size of the light source unit and hence the reduction in size of the projector10.

In addition, with the light axis changing mirror181of the light-source-side optical system180disposed in the position where excitation light is not incident and between the excitation light sources and the light distribution adjusting member, the setting of a direction in which the light source unit60is disposed is facilitated.

Further, with the dichroic mirror which transmits excitation light and reflects luminous light from the luminescent material disposed between the excitation light sources and the light distribution adjusting member, the excitation light sources of the light source unit which emit light of the different range of wavelengths from that of light emitted from the luminescent material as excitation light can easily be disposed in the appropriate position.

In addition, when light emitted from the light source unit60is guided directly without using the light axis changing mirror181, the projector10including the light source unit60can be simplified in construction.

Additionally, with the light source unit in which the collective lenses are disposed individually at the light entry side and the light emanating side of the light distribution adjusting member, not only excitation light is allowed to enter the light distribution adjusting member efficiently, but also the excitation light which has passed through the light distribution adjusting member can easily be collected to the required position on the luminescent material.

With the excitation light sources disposed in the symmetrical positions with respect to the straight line which passes through the middle point of the light incident surface of the light distribution adjusting member and which is normal to the light incident surface, thereby making it possible to facilitate the reduction in size of the excitation light sources while causing the excitation light from respective excitation light sources to effectively enter the light distribution adjusting member.

Further, with the excitation light sources disposed in the symmetrical positions with respect to the straight line which passes through the middle point of the light incident surface of the light distribution adjusting member and which is normal to the light incident surface so as to make equal the angles of incident at which excitation light from the left and right pairs of excitation light sources is incident on the light incident surface of the light distribution adjusting member, excitation light from the pairs of excitation light sources which are disposed symmetrically is allowed to pass through the light distribution adjusting member under the same conditions, thereby making it possible to realize an even in-plane light distribution.

Further, with the luminescent material layer103and the diffuse reflection portion105provided on the luminescent wheel101, which is the circular rotational member, side by side with each other in the end-to-end fashion, light of the range of luminous light wavelengths and light of the range of excitation light wavelengths, which are different in color, can be produced by the light source unit made up of the excitation light sources and the luminous light emitting device100.

In addition, with the excitation light sources made up of the laser emitting devices which emit light of the range of blue wavelengths and luminous light made up of light of the range of green wavelengths, it is possible to provide the high-intensity light source unit which forms and emits easily the two colors in the three primary colors which are necessary to form a color image.

In addition, the invention is not limited to the embodiments that have been described heretofore, and hence, the invention can be modified variously in stages where the invention is carried out without departing from the spirit and scope of the invention. Additionally, in carrying out the invention, the functions executed in the embodiments may be combined as required as much as possible. The embodiments include various stages, and various inventions can be extracted by appropriate combinations of the constituent elements disclosed. For example, as long as an advantage can be obtained even though some of all the constituent elements disclosed in the embodiments are deleted, the configuration in which some such constituent elements are deleted can be extracted as an invention.