Light source device and projector

A light source device includes: a light source lamp that has a light-emitting portion and sealing sections provided on both sides of the light-emitting portion; a reflector that aligns and irradiates a light beam radiated by the light source lamp in a predetermined direction; and a sub-reflection mirror of which reflection surface opposes to a reflection surface of the reflector and reflects the light beam radiated by the light-emitting portion of the light source lamp toward the reflector. In the sub-reflection mirror, an adhesion surface of an insertion hole is bonded to the sealing section by an adhesive in a condition that the sealing section is inserted in the insertion hole. A cutting portion of the sub-reflection mirror is so formed to extend over a portion bonded by the adhesive in plan view.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Exemplary aspects of the present invention relate to a light source device and a projector.

2. Description of Related Art

There is a related art projector that modulates a light beam irradiated by a light source in accordance with image information and projects the light beam in an enlarged manner. Such projector is used together with a personal computer for presentations at conferences or the like. In recent years, this type of projector is also used for home-theater purpose in response to increasing demand for watching movies etc. on a wide screen at home.

As a related art light source device of such projector, a discharge light source device such as a metal halide lamp and a high-pressure mercury lamp is used (see, for example, JP HEI 08-031382A).

This light source device is provided with: a discharge light-emitting tube that has a light-emitting portion for discharging electricity between electrodes to emit light, and sealing sections provided at both ends of the light-emitting portion; a first reflection mirror that aligns and projects light beams radiated from the discharge light-emitting tube in a predetermined direction; and a second reflection mirror bonded to the sealing section by cement and adapted to condense light beams irradiated from the discharge light-emitting tube and irradiate the light beams on the first reflection mirror.

In such light source device, the second reflection mirror efficiently condenses a light beam not in use contained in the light beams radiated from the light-emitting tube, thereby increasing the condensing efficiency.

According to the above-described light source device, however, when the temperature of the discharge light-emitting tube becomes high, the cement bonding the discharge light-emitting tube and the second reflection mirror is thermally expanded, so that a stress is applied to both of the discharge light-emitting tube and the second reflection mirror. This might be resulted in an explosion of the discharge light-emitting tube and a destruction of the second reflection mirror.

SUMMARY OF THE INVENTION

Exemplary aspects of present invention provide a light source device and a projector capable of reducing or preventing damage to a light-emitting tube and a sub-reflection mirror even in the case the sub-reflection mirror is bonded to the light-emitting tube by an adhesive.

A light source device according to an exemplary aspect of the present invention includes: a light-emitting tube having a light-emitting portion that discharges electricity between electrodes and emits a light beam, and sealing sections provided on both ends of the light-emitting portion; a reflector that aligns and irradiates the light beam radiated by the light-emitting tube in a predetermined direction; and a sub-reflection mirror of which reflection surface opposes to a reflection surface of the reflector and reflects the light beam radiated by the light-emitting portion of the light-emitting tube toward the reflector. The sub-reflection mirror has an insertion hole in which the sealing section is inserted and at least one cutting portion. An inner circumference of the insertion hole is bonded to the sealing section by an adhesive in a condition that the sealing section is inserted in the insertion hole. The at least one cutting portion and a portion bonded by the adhesive are at least partially overlapped.

The cutting portion may be formed to penetrate from the outer circumference to the inner circumference of the insertion hole, or it may be formed on either one of the inner circumference or the outer circumference without penetrating to the other surface.

According to the exemplary aspect of present invention, the inner circumference of the insertion hole is bonded to the outer circumference of the sealing section by the adhesive in a condition that the sealing section is inserted in the insertion hole, so that the sub-reflection mirror is attached to the light-emitting tube. Further, at least one cutting portion at least partially overlapping with the bonding portion is formed in the sub-reflection mirror. Accordingly, since the size in the circumferential direction of the insertion hole is changed by the at least one cutting portion even when the light-emitting tube is heated while the light source device is driven and therefore the adhesive between the light-emitting tube and the sub-reflection mirror thermally expands to cause stress in the direction to approach to the center axis of the insertion hole and in the direction to recede away from the center axis of the insertion hole, the stress by thermal expansion can be thus reduced. Therefore, even when the sub-reflection mirror is bonded to the light-emitting tube by the adhesive, the damage to the light-emitting tube and the sub-reflection mirror can be reduced or prevented, and the service life of the light source device can be extended.

In the light source device of an exemplary aspect of invention, the sub-reflection mirror may include: a neck section having the insertion hole and extending along the sealing section; and a reflection section connected to a base end side in the extending direction of the neck section and having the reflection surface. The at least one cutting portion is formed on the neck section.

With this arrangement of the exemplary aspect of the present invention, since the sub-reflection mirror has the neck section and the reflection section, the bonding area of the sub-reflection mirror for the light-emitting tube is wider than the one without the neck section, thereby improving a bonding state between the light-emitting tube and the sub-reflection mirror.

Also, since the neck section is bonded to the sealing section and at least one cutting portion is formed at the neck section, no cutting portion is formed in the reflection section, that is, no cutting portion is formed in the reflection surface. Therefore, the damage to the light-emitting tube and the sub-reflection mirror can be reduced or prevented, and the efficiency for the sub-reflection mirror to use the light of the light source device can be adequately maintained.

In the light source device of an exemplary aspect of the invention, the cutting portion may include a plurality of cutting portions formed on the sub-reflection mirror. The plurality of cutting portions are symmetrically located with respect to an axis passing a center of the insertion hole.

According to this configuration of the exemplary aspect of the present invention, since the plurality of cutting portions are formed in the sub-reflection mirror, the stress by the adhesive can be reduced comparing with the configuration having only one cutting portion, thereby reducing or preventing the damage to the light-emitting tube and the sub-reflection mirror.

Since the plurality of the cutting portions are symmetrically located with respect to an axis passing the center of the insertion hole, the stress by the adhesive can be dispersed, and therefore the damage to the light-emitting tube and the sub-reflection mirror can be efficiently reduced or prevented.

A light source device according to another exemplary aspect of the present invention includes: a light-emitting tube having a light-emitting portion that discharges electricity between electrodes and emits a light beam, and sealing sections provided on both ends of the light-emitting portion; a reflector that aligns and irradiates the light beam radiated by the light-emitting tube in a predetermined direction; and a sub-reflection mirror of which reflection surface opposes to a reflection surface of the reflector and reflects the light beam radiated by the light-emitting portion of the light-emitting tube toward the reflector. The sub-reflection mirror has: a neck section having an insertion hole in which the sealing section is inserted and of which inner circumference is bonded to the sealing section by an adhesive, the neck section extending along the sealing section; and a reflection section connected to a base end side in the extending direction of the neck section and having the reflection surface. At least one opening penetrating from an outer circumference of the neck section to the inner circumference of the insertion hole is formed on the neck section. The opening is closer to the base end side in the extending direction of the neck section than the portion bonded by the adhesive.

According to the exemplary aspect of the present invention, the inner circumference of the insertion hole is bonded to the outer circumference of the sealing section by the adhesive in a condition that the sealing section is inserted in the insertion hole of the neck section, so that the sub-reflection mirror is attached to the light-emitting tube. Also, on the neck section, at least one opening penetrating from the outer circumference of the neck section to the inner circumference of the insertion hole is formed at a position closer to the base end side in the extending direction of the neck section than the bonding portion. With this configuration of the exemplary aspect of the present invention, when the temperature of the light-emitting tube becomes high while the light source device is driven, the heat staying in the clearance between the light-emitting tube and the neck section of the sub-reflection mirror can be discharged to the outside through the opening. This suppresses the temperature rise of the connecting portion between the light-emitting tube and the sub-reflection mirror. Therefore, the thermal expansion of the adhesive between the light-emitting tube and the sub-reflection mirror is reduced. Further, even when the sub-reflection mirror is bonded to the light-emitting tube by the adhesive, the damage to the light-emitting tube and the sub-reflection mirror can be reduced or prevented, and the service life of the light source device can be extended.

Since the sub-reflection mirror has the neck section and the reflection section, the bonding area of the sub-reflection mirror for the light-emitting tube is wider than the one without the neck section, thereby improving a bonding state between the light-emitting tube and the sub-reflection mirror.

In the light source device of an exemplary aspect of invention, when a lower side is defined as a side on which the weight of the light source device is applied and an upper side is defined as a side opposite to the side on which the weight is applied, the opening may be formed on the upper side on the neck section.

According to this configuration of the exemplary aspect of invention, since the opening is formed on the upper side on the neck section, the opening is located in the convection direction of the air heated by the heat. Therefore, the air heated by the light-emitting tube and staying in the clearance between the light-emitting tube and the sub-reflection mirror can be smoothly discharged to the outside through the opening. This effectively suppresses the temperature rise of the connecting portion between the light-emitting tube and the sub-reflection mirror.

In the light source device of an exemplary aspect of invention, the openings may be formed on both of the upper side and the lower side on the neck section.

According to this configuration of the exemplary aspect of invention, since the openings are formed on both of the upper side and the lower side on the neck section, the natural convection of the air between the clearance between the light-emitting tube and the sub-reflection mirror and the outside of the sub-reflection mirror is easily caused. That is, the outside air easily flows into the clearance between the light-emitting tube and the sub-reflection mirror through the opening formed on the lower side, and the air in the clearance between the light-emitting tube and the sub-reflection mirror can be easily discharged to the outside through the opening formed on the upper side. Therefore, the air heated by the light-emitting tube and staying in the clearance between the light-emitting tube and the sub-reflection mirror can be smoothly discharged to the outside, while the cooling air flows into the clearance between the light-emitting tube and the sub-reflection mirror. Accordingly, the temperature rise of the connecting portion between the light-emitting tube and the sub-reflection mirror can be effectively suppressed.

In the light source device of an exemplary aspect of invention, at least one cutting portion at least partially overlapping with the portion bonded by the adhesive may be formed on the neck section.

The cutting portion may be formed to penetrate from the outer circumference to the inner circumference of the insertion hole, or it may be formed on either one of the inner circumference or the outer circumference without penetrating to the other surface.

According to this configuration of the exemplary aspect of invention, since at least one cutting portion at least partially overlapping with the bonding portion is formed on the neck section, the size in the circumferential direction of the insertion hole is changed by the at least one cutting portion even when the adhesive between the light-emitting tube and the sub-reflection mirror thermally expands to cause stress in the direction to approach to the center axis of the insertion hole and in the direction to recede away from the center axis of the insertion hole. The stress by the adhesive can be thus reduced.

Therefore, the damage to the light-emitting tube and the sub-reflection mirror can be effectively reduced or prevented due to the effect of the cutting portion for reducing the stress of the adhesive in addition to the effect of the openings for releasing the heat of the connecting portion between the light-emitting tube and the sub-reflection mirror.

In the light source device of an exemplary aspect of invention, the width of the opening in a direction orthogonal to the extending direction of the neck section may be greater than the width of the cutting portion in the direction orthogonal to the extending direction of the neck section, and the opening and the cutting portion are connected with each other.

According to this configuration of the exemplary aspect of invention, since the width of the opening is greater than the width of the cutting portion, and the opening and the cutting portion are connected with each other, the opening as well as the cutting portion serve to reduce the stress of the above-described adhesive. This allows larger size change of the insertion hole in the circumferential direction, and therefore the damage to light-emitting tube and the sub-reflection mirror can be effectively reduced or prevented even when the thermal expansion of the adhesive is large.

A projector according to a further exemplary aspect of the present invention, includes: any one of the above-described light source devices; an optical modulator that modulates a light beam irradiated by the light source device in accordance with image information; and a projection optical device that enlarges and projects the light beam modulated by the optical modulator.

With this arrangement of the exemplary aspect of invention, since the projector has the above-described light source device, the optical modulator and the projection optical device, the same functions and advantages as the above-described light source device can be obtained.

Since the projector has the light source device capable of reducing or preventing the damage to the light-emitting tube and the sub-reflection mirror, the service life of the projector can be extended, and the replacement work of the light source device can be reduced.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT(S)

1 First Embodiment

Structure of Projector

FIG. 1is a schematic illustration showing an optical equipment of a projector1equipped with a light source device according to an exemplary embodiment of the present invention.

The projector1is an optical equipment that modulates a light beam irradiated by a light source in accordance with image information to form an optical image, and projects the optical image on a screen in an enlarged manner.

As shown inFIG. 1, the projector1includes a light source device10, an integrator illumination optical system20, a color-separating optical system30, a relay optical system35, an optical device40and a projection optical system50as a projection optical device. Optical elements of these optical systems20to35and the optical device40are positioned and housed in an optical component casing2in which a predetermined illumination optical axis A is set.

The light source device10aligns and irradiates a light beam radiated from a light source lamp11in a predetermined direction to illuminate the optical device40. The light source device10, which will be described later in detail, includes the light source lamp11, an ellipsoidal reflector12, a sub-reflection mirror13and a not-shown lamp housing supporting theses components. On the downstream of a light-irradiation direction of the ellipsoidal reflector12, a parallelizing concave lens14is provided. The parallelizing concave lens14may be integrally formed with the light source device10or may be provided separately.

The light beam emitted by the light source lamp11is irradiated toward the front side of the light source device10as a convergent light after the irradiating direction thereof is aligned by the ellipsoidal reflector12. The convergent light is then parallelized by the parallelizing concave lens14and irradiated on the integrator illumination optical system20.

The integrator illumination optical system20is an optical system that splits the light beam irradiated by the light source device10into a plurality of sub-beams to equalize the in-plane luminance of an illumination area. The integrator illumination optical system20has a first lens array21, a second lens array22, a polarization converter23, a superposing lens24and a reflection mirror25.

The first lens array21is a light-beam splitting optical element for splitting the light beam irradiated by the light source device10into a plurality of sub-beams, and is provided with a plurality of small lenses arranged in a matrix in a plane orthogonal to the illumination optical axis A.

The second lens array22is an optical element for condensing the plurality of sub-beams split by the first lens array21, and is provided with a plurality of small lenses arranged in a matrix in a plane orthogonal to the illumination optical axis A in the same manner as the first lens array21.

The polarization converter23is a polarization-converting element for aligning the polarization direction of the respective sub-beams split by the first lens array21to have the beams linearly polarized in substantially single direction.

Though not illustrated, the polarization converter23has a configuration in which polarization separating films and reflection films inclined relative to the illumination optical axis A are alternately arranged. The polarization separating film transmits either one of P polarized light beam or S polarized light beam contained in the respective sub-beams and reflects the other one of the polarized light beams. The reflected polarized light beam is refracted by the reflection film and is irradiated in the irradiation direction of the transmitted polarized light beam, i.e., the direction along the illumination optical axis A. Either one of the irradiated polarized light beams is polarization-converted by a phase plate provided on the light-irradiation surface of the polarization converter23so that the polarization direction of substantially all of the polarized light beams are aligned. With the use of the polarization converter23, the light beam irradiated by the light source lamp11can be aligned as a light beam polarized in substantially single direction, thereby enhancing the utilization ratio of the light source beam used in the optical device40.

The superposing lens24is an optical element for condensing the plurality of sub-beams having passed through the first lens array21, the second lens array22and the polarization converter23to superpose the sub-beams on an image formation area of later-described three liquid crystal panels of the optical device40.

The light beam irradiated by the superposing lens24is refracted by the reflection mirror25to be irradiated to the color-separating optical system30.

The color-separating optical system30includes two dichroic mirrors31and32and a reflection mirror33, and separates the plurality of sub-beams irradiated from the integrator illumination optical system20by the dichroic mirrors31and32into three color lights of red (R), green (G) and blue (B).

The dichroic mirrors31and32are optical elements having a substrate on which a wavelength-selection film that reflects a light beam of a predetermined wavelength and transmits a light beam of the other wavelength is formed. The dichroic mirror31disposed on the upstream of the optical path is a mirror that transmits the red light and reflects the other color lights. The dichroic mirror32disposed on the downstream of the optical path is a mirror that reflects the green light and transmits the blue light.

The relay optical system35has an incident-side lens36, a relay lens38and reflection mirrors37and39, and guides the blue light transmitted through the dichroic mirror32of the color-separating optical system30to the optical device40. Herein, because the optical path length of the blue light is longer than those of the other color lights, the relay optical system35is used for the optical path of the blue light, thereby preventing deterioration in the light utilization efficiency caused by the light dispersion and the like. This exemplary embodiment adopts such arrangement since the optical path of the blue light is long. However, the optical path of the red light may alternatively be lengthened so that the relay optical system35is used for the optical path of the red light.

The red light separated by the above-described dichroic mirror31is refracted by the reflection mirror33, and then supplied to the optical device40through a field lens41. The green light separated by the dichroic mirror32is directly supplied to the optical device40through the field lens41. The blue light is condensed and refracted by the lenses36,38and the reflection mirrors37,39of the relay optical system35, and then supplied to the optical device40through the field lens41. Incidentally, the field lenses41provided on the upstream of the optical path of the respective color lights of the optical device40are provided for converting the respective sub-beams irradiated by the second lens array22into light beams parallel to the illumination optical axis.

The optical device40modulates the incident light beam in accordance with image information to form a color image. The optical device40includes liquid crystal panels42R,42G and42B (defining liquid crystal panel at the red light side as42R, liquid crystal panel at the green light side as42G, and the liquid crystal panel at the blue light side as42B) as an optical modulator to be illuminated and a cross dichroic prism43. Incidentally, incident-side polarization plates44are interposed between the field lenses41and the respective liquid crystal panels42R,42G and42B and, though not illustrated, irradiation-side polarization plates are interposed between the respective liquid crystal panels42R,42G and42B and a cross dichroic prism43, so that the incident-side polarization plates44, the liquid crystal panels42R,42G and42B and the irradiation-side polarization plates modulate the respective incident color lights.

Each of the liquid crystal panels42R,42G and42B is a pair of light-transmissive glass substrates with liquid crystal (electrooptic material) sealed therebetween, which modulates the polarization direction of the polarized light beam irradiated by the incident-side polarization plates44in accordance with given image signal using, for instance, polycrystalline silicon TFT as a switching element.

The cross dichroic prism43is an optical element for combining the optical images irradiated by the irradiation-side polarization plates and modulated for each color light to form a color image. The cross dichroic prism43has a square profile in plan view with four right-angle prisms adhered with each other, and dielectric multi-layered films are formed on adhesion surfaces between the respective right-angle prisms. One of the multi-layered films arranged in approximately X-shape reflects the red light and the other multi-layer film reflects the blue light. The multi-layered films refract the red light and the blue light to be aligned with the advancing direction of the green light, thereby combining the three color lights.

The color image irradiated by the cross dichroic prism43is projected by the projection optical system50in an enlarged manner to form a large image on a screen (not shown).

Structure of Light Source Device

FIG. 2is a schematic cross section showing the structure of the light source device10.

In the light source device10, as shown inFIG. 2, the sub-reflection mirror13is attached to the light source lamp11as a light-emitting tube. The light source lamp11and the sub-reflection mirror13are arranged inside the ellipsoidal reflector12.

As shown inFIG. 2, the light source lamp11is a silica glass tube with a spherical center part, and is provided with a light-emitting portion111at the center portion, a sealing section1121and another sealing section1122extending on both sides of the light-emitting portion111.

Various light-emitting tubes for emitting light with high luminance may be used as the light source lamp11, which may be metal halide lamp, high-pressure mercury lamp, extra high-pressure mercury lamp or the like.

A pair of tungsten electrodes111A with a predetermined distance inbetween, mercury, rare gas and small portion of halogen are sealed inside the light-emitting portion111.

Metal foils112A made of molybdenum electrically connected with the electrodes of the light-emitting portion111are inserted in the sealing section1121and the sealing section1122extending on both sides of the light-emitting portion111, and are sealed by glass material etc. A lead wire113(electrode-connecting wire) is connected to the metal foils112A, the lead wire113extending toward the outside of the light source lamp11.

When a predetermined voltage is applied to the lead wire113, as shown inFIG. 2, voltage potential difference is caused between the electrodes111A through the metal foils112A and the electricity is thus discharged, so that an arc image D is generated and the light-emitting portion111emits light.

If the outer circumference of the light-emitting portion111is covered by a multilayer antireflection coat containing a tantalum oxide film, a hafnium oxide film, a titanium oxide film or the like, light loss due to the reflection of the light passing therethrough can be reduced.

As shown inFIG. 2, the ellipsoidal reflector12is a glass molding integrally having a neck section121to which the sealing section1122at the base end side of the light source lamp11is inserted and a reflection section122of ellipsoidal surface extending from the neck section121.

An insertion hole123is formed at the center of the neck section121, and the sealing section1122is disposed at the center of the insertion hole123.

The reflection section122includes a reflection surface122A, which is an ellipsoid of revolution glass surface with a metal thin film evaporated thereon. The reflection surface122A of the reflection section122is a cold mirror reflecting visible light and transmitting infrared ray.

The light source lamp11is disposed inside the reflection section122of the ellipsoidal reflector12so that the light-emitting center between the electrodes11A inside the light-emitting portion111is positioned in the vicinity of a first focal point position L1of the ellipsoid of revolution surface of the reflection surface122A of the reflection section122.

When the light source lamp11is lit, the light beam radiated by the light-emitting portion111is reflected by the reflection surface122A of the reflection section122to be a convergent light converging at a second focal point position L2of the ellipsoid of revolution surface of the reflection section122.

In such condition, the area inside the boundary lines L3and L4connecting the second focal point position L2and the end of the sealing section1121at the front side in the light-irradiating direction of the light source lamp11is a light-beam non-available area, because the light beam reflected by the ellipsoidal reflector12is shielded by the sealing section1121without reaching the second focal point position L2.

FIGS. 3A and 3Bare schematic illustrations each showing the structure of the sub-reflection mirror13. Specifically,FIG. 3Ais a front view of the sub-reflection mirror13seen from the light-incident side thereof.FIG. 3Bis a cross section taken along a line B—B inFIG. 3A.

FIG. 4is a schematic showing how the sub-reflection mirror13is arranged with respect to the light source lamp11.

As shown inFIGS. 3A,3B and4, the sub-reflection mirror13with the substantially same shape as the ellipsoidal reflector12has a neck section131with a substantially cylindrical shape to which the sealing section1121at the front end side of the light source lamp11is inserted and a substantially spherical reflection section132extending from the neck section131so that the neck section131and the reflection section132are integrally formed.

The neck section131is a portion for bonding the sub-reflection mirror13to the light source lamp11.

As shown inFIGS. 3A,3B and4, the neck section131has four cutting portions131A symmetrically located with respect to a cylindrical shaft. Each of the cutting portions131A is extended from the front end side to the base end side connected to the reflection section132.

On the neck section131, the sealing section1121of the front end side of the light source lamp11is inserted in a cylindrical insertion hole131B, so that the sub-reflection mirror13is set on the light source lamp11as shown inFIG. 4. The inner circumference of the insertion hole131B, as will be described later, is an adhesion surface131C on which a fixing adhesive133is filled to be fixed to the sealing section1122.

As shown inFIG. 4, the bowl-shaped reflection section132is a reflection member that substantially covers the front half side of the light-emitting portion111of the light source lamp11when the sub-reflection mirror13is set on the light source lamp11.

As shown inFIGS. 3A and 3B, the reflection section132has an inner surface as a reflection surface132A formed to be spherical along the spherical surface of the light-emitting portion111of the light source lamp11, and an outer circumference132B curved according to the curvature of the reflection surface132A. Although not shown inFIGS. 3A and 3B, the reflection surface132A has a reflection film formed by evaporating metal. This reflection surface, like the reflection surface122A of the ellipsoidal reflector12, is a cold mirror reflecting visible light and transmitting infrared ray and ultraviolet ray.

In the reflection section132, as shown inFIG. 3B, an end face at the front side extending from the neck section131is a slanted surface132C so formed that the height of the bowl is gradually lowered from the end side of the reflection surface132A (left end inFIG. 3B) toward the end side of the outer circumference132B.

For shortening the length of the ellipsoidal reflector12in the direction of the optical axis A, an angle θ is preferably 105° or less.

Although the slanted surface is slanted along the angle θ in the present exemplary embodiment, the slanted surface132C may be orthogonal to the optical axis A if the shielding amount of the radial light in the θ direction is small.

The above-mentioned sub-reflection mirror13is a material with low thermal expansivity and/or high thermal conductivity. For example, the sub-reflection mirror13is made of an inorganic material such as quartz and alumina ceramics.

By attaching the sub-reflection mirror13to the light source lamp11, as shown inFIG. 2, a light beam L5, which is contained in the light beam radiated from the light-emitting portion111and is radiated to the opposite side of the ellipsoidal reflector12(the front side), is reflected by the reflection surface132A of the sub-reflection mirror13toward the ellipsoidal reflector12, and further reflected by the reflection surface122A of the ellipsoidal reflector12, and then irradiated from the reflection section122of the ellipsoidal reflector12to be converged toward a second focal point F2position.

With the use of such sub-reflection mirror13as previously mentioned, the light beam radiated from the light-emitting portion111to the opposite side of the ellipsoidal reflector12(the front side) can be converged on the second focal point F2position of the ellipsoidal reflector12in the same manner as the light beam directly incident from the light source lamp11onto the reflection surface122A of the ellipsoidal reflector12.

In a conventional light source device without the sub-reflection mirror13, it is required to converge the light beam irradiated from the light source lamp11on the second focal point F2position only by the ellipsoidal reflector, and therefore the opening of the ellipsoidal reflector must be wide.

However, with the sub-reflection mirror13, since the light beam radiated from the light source lamp11to the opposite side of the ellipsoidal reflector12(the front side) can be reflected to the rear side by the sub-reflection mirror13so that the light beam is incident on the reflection surface122A of the ellipsoidal reflector12, almost all the light beams irradiated from the light-emitting portion111can be irradiated to be converged on a predetermined position even if the reflection section122is small. Accordingly, the size in the optical axis direction and the diameter of the opening of the ellipsoidal reflector12can be reduced. That is, the size of the light source device10and the projector1can be reduced, and therefore the light source device10may be easily incorporated in the projector1.

Further, since the sub-reflection mirror13is provided, even if a first focal point F1and the second focal point F2of the ellipsoidal reflector12are located closer to each other to reduce the diameter of the light-condensing spot on the second focal point F2, almost all the light radiated from the light-emitting portion111is converged by the ellipsoidal reflector12and the sub-reflection mirror13onto the second focal point and can be utilized, therefore considerably enhancing the light utilization efficiency. Accordingly, a light source lamp11with a relatively low output can be employed, and also the light source lamp11and the light source device10can be kept at lower temperature.

Available marginal lights L3and L4as boundary lines between an available area and the non-available area are lights, which are contained in the light irradiated from the light-emitting portion111to the ellipsoidal reflector12, corresponding to inner boundaries of the area that can be actually utilized as an illumination light. The available marginal lights L3and L4are determined by the configuration of the light source lamp11, or otherwise determined by the configuration of the ellipsoidal reflector12. The available marginal light determined by the configuration of the light source lamp11is an effective light, which is contained in the light irradiated from the light-emitting portion111toward the ellipsoidal reflector12(i.e. the rear side of the light source device10), on the boundary with the light shielded by the sealing section1122and the like. The available marginal light determined by the configuration of the ellipsoidal reflector12is an effective light, which is contained in the light irradiated as the effective light from the light-emitting portion111toward the ellipsoidal reflector12(i.e. the rear side of the light source device10) without being shielded by the sealing section1122and the like, on the boundary with a light that can not be reflected by the reflection surface122A due to the ellipsoidal reflector12such as the presence of the insertion hole123of the ellipsoidal reflector12and therefore can not be utilized as illumination light. Accordingly, an inner area of a circular cone formed by the available marginal lights L3and L4is a light-beam non-available area. In the case the available marginal light is determined by the configuration of the light source lamp11, almost all the lights irradiated from the light-emitting portion111to the rear side of the light source device10can be utilized according to the present exemplary embodiment.

When the outer circumference132B of the sub-reflection mirror13is extended out of the circular cone formed by the available marginal lights L3and L4, the light advancing forward after being reflected by the ellipsoidal reflector12is shielded, therefore lowering the light utilization efficiency. Accordingly, for preventing the light utilization ratio from lowering, it is preferable to make the outer circumference132B of the sub-reflection mirror13as small as possible.

Next, a method for fixing the sub-reflection mirror13and the ellipsoidal reflector12to the light source lamp11will be descried below.

FIGS. 5A and 5Bare illustrations each showing how to fix the sub-reflection mirror13to the light source lamp11. Specifically,FIG. 5Ais a cross section of the light source lamp11and the sub-reflection mirror13seen from the lateral side thereof.FIG. 5Bis a cross section taken along a line B—B inFIG. 5A.

The above-described sub-reflection mirror13is attached to the light source lamp11as follows.

Firstly, the sub-reflection mirror13is located on the light source lamp11so that an incident light irradiated between a pair of the electrodes111A of the light-emitting portion111to be incident on the sub-reflection mirror13matches a normal line of the reflection surface132A of the sub-reflection mirror13.

Then, as shown inFIG. 5A, the sub-reflection mirror13is positioned at a position in the direction orthogonal to the optical axis A with respect to the light source lamp11so that the slanted surface132C is arranged along the angle θ formed by the base end portion of the light-irradiating direction of the illumination optical axis A of the ellipsoidal reflector12and the light beam radiated by the light-emitting portion111as well as so that the outer circumference132B of the sub-reflection mirror13is located inside the circular cone formed by the above-described available marginal lights L3and L4.

After positioning the sub-reflection mirror13at a predetermined position with respect to the light source lamp11, as shown inFIGS. 5A and 5B, the adhesive133is filled throughout the circumference around the optical axis A between the adhesion surface131C of the neck section131and the outer circumference of the sealing section1121of the light source lamp11, so that the sub-reflection mirror13is adhered and fixed to the light source lamp11. In this step, as shown inFIGS. 5A and 5B, the cutting portions131A of the neck section131are arranged to extend over the adhesion portion of the adhesive133.

As for the material of the adhesive133, an inorganic adhesive of silica/alumina group is applicable. Glass fusion may also be applicable for the adhesion between the sub-reflection mirror13and the light-source lamp11.

Next, a method for fixing the light source lamp11to the ellipsoidal reflector12will be descried.

When the light source lamp11is fixed to the above-described ellipsoidal reflector12, the sealing section1122of the light source lamp11is inserted to the insertion hole123of the ellipsoidal reflector12so that the light-emitting center between the electrodes111A in the light-emitting portion111is located at the first focal point position L1of the ellipsoid of revolution surface of the reflection surface122A of the reflection section122, and an inorganic adhesive made mainly of silica and alumina is filled in the insertion hole123.

The dimension of the reflection section122in the optical axis direction is shorter than the length of the light source lamp11so that the front sealing section1121of the light source lamp11protrudes from the light-irradiation opening of the ellipsoidal reflector12when the light source lamp11is fixed to the ellipsoidal reflector12as in the above.

According to the first exemplary embodiment, since the sub-reflection mirror13has four cutting portions131A extending over the bonding portion of the sealing section1121of the light source lamp11by the adhesive133, the size in the circumferential direction of the neck section131is changed by the four cutting portions131A even when the light source lamp11is heated while the light source device10is driven and therefore the adhesive133thermally expands to cause stress in the direction to approach to the center axis of the insertion hole131B and in the direction to recede away from the center axis of the insertion hole131B. The stress by the adhesive133is thus reduced. Accordingly, even when the sub-reflection mirror13is bonded to the light source lamp11by the adhesive133, the damage to the light source lamp11and the sub-reflection mirror13can be reduced or prevented, and the service life of the light source device10can be extended. Consequently, the service life of the projector1can be extended.

Since the sub-reflection mirror13has the neck section131and the reflection section132, the bonding area of the sub-reflection mirror13for the light source lamp11is wider than the one without the neck section131, thereby improving a bonding state between the light source lamp11and the sub-reflection mirror13. As a result, the displacement of the sub-reflection mirror13can be properly reduced or prevented.

Since the neck section131is bonded to the sealing section1121and the four cutting portions131A are formed at the neck section131, no cutting portion is formed in the reflection section132, that is, no cutting portion is formed in the reflection surface132A. Therefore, the damage to the light source lamp11and the sub-reflection mirror13can be prevented, and the efficiency for the sub-reflection mirror13to use the light of the light source device10can be adequately maintained.

Since the sub-reflection mirror13has the four cutting portions131A, the stress by the adhesive133is reduced more properly than the one having only one cutting portion131A, thereby reducing or preventing the damage to the light source lamp11and the sub-reflection mirror13. The four cutting portions131A are symmetrically located with respect to an axis passing the center of the insertion hole131B, the stress by the adhesive133can be dispersed, and therefore the damage to the light source lamp11and the sub-reflection mirror13can be efficiently reduced or prevented.

Since the projector has the light source device10capable of reducing or preventing the damage to the light source lamp11and the sub-reflection mirror13, the replacement work of the light source device10required due to the damage of the light source lamp11and the sub-reflection mirror13can be reduced, thereby enhancing the convenience thereof.

2 Second Embodiment

A second exemplary embodiment of the present invention will be described with reference to the attached drawings.

In the following description, the components same as those in the first exemplary embodiment are indicated by the same reference symbols or numerals for omitting or simplifying the detailed description thereof.

In the first exemplary embodiment, the neck section131of the sub-reflection mirror13only has the cutting portions131A.

In the second exemplary embodiment, on the other hand, a neck section131of a sub-reflection mirror13A has openings134in addition to cutting portions131A. The configuration other than the sub-reflection mirror13A is the same as in the first exemplary embodiment.

FIGS. 6A and 6Bare schematic illustrations each showing the sub-reflection mirror13A according to the second exemplary embodiment. Specifically,FIG. 6Ais a plan view of the sub-reflection mirror13A seen from the upper side (wherein a lower side is defined as a side on which the weight of the light source device10is applied, and an upper side is defined as a side opposite to the side on which the weight is applied).FIG. 6Bis a cross section taken along a line B-B inFIG. 6A.

As shown inFIG. 6A, each of the openings134formed at the neck section131of the sub-reflection mirror13A is positioned at the base end side connected to a reflection section132, and is formed substantially in a rectangular shape in plan view extending in the direction orthogonal to the cylindrical shaft direction of the neck section131.

As shown inFIG. 6B, the openings134consist of two opposing openings134A and134B respectively formed on the upper side and the lower side of the neck section131.

The opening134can be easily formed by rotating a not-show grinding tool such as a discoid grinding stone in the circumferential direction and contacting the neck section131on the grinding stone so that the cylindrical shaft direction of the neck section131is orthogonal to a plate surface of the grinding stone.

In the second exemplary embodiment, two cutting portions131A are formed on the upper side and the lower side of the neck section131corresponding to the above-described two openings134(seeFIG. 7). The two cutting portions131A are respectively connected to the two openings134as shown inFIG. 6A. The cutting portions131A are connected to the approximate center portion in the extending direction (the vertical direction inFIG. 6A) in the openings134. As shown inFIG. 6A, the width of the opening134in the extending direction (the vertical direction inFIG. 6A) is greater than the width of the cutting portion131A.

Since a method for fixing the sub-reflection mirror13A and the ellipsoidal reflector12to the light source lamp11is the same as the fixing method in the first exemplary embodiment, the description thereof will be omitted.

Next, a cooling mechanism by the above-described openings134for a connecting portion between the light source lamp11and the sub-reflection mirror13A will be described.

FIG. 7is an illustration showing the cooling mechanism by the openings134for the connecting portion between the light source lamp11and the sub-reflection mirror13A. Specifically,FIG. 7is a cross section of the light source lamp11and the sub-reflection mirror13A seen from the lateral side.

When the light source lamp11emits light and the temperature thereof becomes high and thereby heating the air in a clearance between the light source lamp11and the sub-reflection mirror13A, natural convection is caused between the clearance and the outside of the sub-reflection mirror13A as shown inFIG. 7.

More specifically, as shown inFIG. 7, the heated air rises to the upper side along the clearance to be discharged to the outside of the sub-reflection mirror13A through the opening134A on the upper side. At the same time, the air outside the sub-reflection mirror13A flows into the clearance through the opening134B on the lower side.

The above-described natural convection inhibits the heated air from staying in the clearance, thereby suppressing the temperature rise of the connecting portion between the light source lamp11and the sub-reflection mirror13A.

In the above-described second exemplary embodiment, comparing with the first exemplary embodiment, since the sub-reflection mirror13A has the openings134at the neck section131, the heat heated by the light source lamp11and staying in the clearance between the light source lamp11and the neck section131of the sub-reflection mirror13A can be discharged to the outside of the sub-reflection mirror13A through the opening134. This suppresses the temperature rise of the connecting portion between the light source lamp11and the sub-reflection mirror13A. Accordingly, the thermal expansion of the adhesive133is reduced, thereby reducing or preventing the damage to the light source lamp11and the sub-reflection mirror13A.

Since the neck section131has the openings134A and134B respectively on both of the upper end and the lower end, the natural convection of the air between the clearance between the light source lamp11and the sub-reflection mirror13A and the outside of the sub-reflection mirror13A is easily caused. This suppresses the temperature rise of the connecting portion between the light source lamp11and the sub-reflection mirror13A, and the thermal expansion of the adhesive133is thus reduced, thereby efficiently reducing or preventing the damage to the light source lamp11and the sub-reflection mirror13A.

Since both of the cutting portions131A and the openings134are formed at the neck section131, the damage to the light source lamp11and the sub-reflection mirror13A can be effectively reduced or prevented due to the effect of the cutting portions131A for reducing the stress of the adhesive133in addition to the effect of the openings134for releasing the heat of the connecting portion between the light source lamp11and the sub-reflection mirror13A.

Since the width of the opening134is greater than the width of the cutting portion131A, and the opening134and the cutting portion131A are connected with each other, the opening134as well as the cutting portion131A serve to reduce the stress of the above-described adhesive133. This allows larger size change of the neck section131in the circumferential direction, and therefore the damage to the light source lamp11and the sub-reflection mirror13A can be effectively reduced or prevented even when the thermal expansion of the adhesive133is large.

While the present invention has been described above with the preferable exemplary embodiments, the present invention is not limited to the above-described exemplary embodiments, but includes improvements and modifications as long as an object of the present invention can be achieved.

In the respective exemplary embodiments, the shape and the number of the cutting portion formed in the sub-reflection mirror13is not limited as long as the cutting portion extends over the bonding portion between the light source lamp11and the sub-reflection mirror13in plan view.

For example, although the adhesive133is applied throughout the circumference of the sealing section1121so that the bonding portion formed by the adhesive133and the cutting portion131A are in close contact in the respective exemplary embodiments, the adhesive133may be applied intermittently on the circumference of the sealing section1121so that the bonding portion formed by the adhesive133and the cutting portion131A are spaced apart. In this case, the cutting portion131A is so arranged to extend over the trajectory of the bonding portion drawn by the rotation when the bonding portion formed by the adhesive133is rotated around an axis passing the center of the insertion hole131B.

The cutting portion131A penetrates from the outer circumference to the inner circumference of the neck section131in the above description, it may be formed on either one of the inner circumference or the outer circumference without penetrating to the other.

In the sub-reflection mirror, for example, the cutting portion may be extended to the reflection section without limiting to the neck section.

Specifically,FIG. 8is an illustration showing a modification of the formation position of the cutting portion in the first exemplary embodiment.

As shown inFIG. 8, in a sub-reflection mirror13B, a cutting portion131A′ extends from the front end of a neck section131to a base end side connected to a reflection section132, and further extends to a front end portion stretching from the neck section131in the reflection section132. Namely, in the sub-reflection mirror13B, the cutting portion131A′ is formed on both a neck section131and a reflection section132along the axial direction thereof.

An adhesion surface131C of the neck section131and the outer circumference of the sealing section1121of the light source lamp11are bonded by the adhesive133, so that the sub-reflection mirror13B is attached to the light source lamp11in the same manner as the sub-reflection mirror13in the first exemplary embodiment.

The number of the cutting portion131A′ to be formed is not limited to one and may be two or more.

Specifically,FIG. 9is an illustration showing a modification ofFIG. 8.

As shown inFIG. 9, a sub-reflection mirror13C has two cutting portions131A′. In other words, the sub-reflection mirror13C is separated into a pair of a first sub-reflection mirror13C1and a second sub-reflection mirror13C2by two cutting portions131A′.

The respective adhesion surfaces131C of respective neck sections131and the outer circumference of the sealing section1121of the light source lamp11are bonded by the adhesive133so that the first sub-reflection mirror13C1and the second sub-reflection mirror13C2are combined, and thus the sub-reflection mirror13C is attached to the light source lamp11in the same manner as the sub-reflection mirror13in the first exemplary embodiment.

The configurations shown inFIGS. 8 and 9may be applied to the configuration having the opening134in the second exemplary embodiment without limiting to the first exemplary embodiment. In the case that the cutting portions131A′ is applied to the configuration having the openings134, above-described cutting portions131A′ are so formed to be connected to respective opposing end sides of the openings134.

In the first exemplary embodiment, the neck section131of the sub-reflection mirrors13B and13C in the configuration shown inFIGS. 8 and 9may not be provided. In such case, the adhesive133is applied to the inner circumference of an opening portion having a small opening area in the reflection section132and the outer circumference of the sealing section1121of the light source lamp11for bonding them.

Although the above-mentioned cutting portions131A and131A′ are formed along the extending direction of the sealing section1121of the light source lamp11, they may be inclined with respect to the extending direction.

Although the opening134is formed in a rectangular shape in the second exemplary embodiment, it may be formed in other shapes.

For example,FIGS. 10A and 10Bare illustrations each showing a modification of the opening of the second exemplary embodiment. Specifically,FIG. 10Ais an illustration of a sub-reflection mirror13D seen from the upper side.FIG. 10Bis a cross section taken along a line B—B inFIG. 10A.

In the sub-reflection mirror13D, each of openings134′ has a substantially circular shape as shown inFIG. 10A. Like the openings134of the second exemplary embodiment, the openings134′ consist of two opposing openings134A′ and134B′ respectively formed on the upper side and the lower side of a neck section131.

The openings134′ can be easily formed by, for example, drilling from the upper side of the neck section131to the lower side thereof using a cutting tool such as a drill.

In the second exemplary embodiment, although the neck section131of the sub-reflection mirror13A has both of the cutting portions131A and openings134, it may have only the openings134.

For example,FIGS. 11A and 11Bare illustrations each showing a modification of the second exemplary embodiment. Specifically,FIG. 11Ais an illustration of a sub-reflection mirror13E seen from the upper side.FIG. 11Bis a cross section taken along a line B—B inFIG. 11A.

As shown inFIGS. 11A and 11B, the cutting portion131A of the second exemplary embodiment is not formed at a neck section131of the sub-reflection mirror13E, but only the openings134(134A and134B) of the second exemplary embodiment are formed.

Even with such sub-reflection mirror13E in which only the openings134are formed at the neck section131, the natural convection can be caused between the clearance between the light source lamp11and the sub-reflection mirror13E and the outside of the sub-reflection mirror13E. This can suppress the temperature rise of the connecting portion between the light source lamp11and the sub-reflection mirror13E, and thus the object of the present invention can be sufficiently achieved.

Although the sub-reflection mirror13A shown inFIGS. 6A and 6Bin the second exemplary embodiment has the openings134A and134B respectively formed on the upper end and the lower end of the neck section131, it may have only the opening134A on the upper end. Even with such configuration, the air in the clearance between the light source lamp11and the sub-reflection mirror13A can be discharged to the outside of the sub-reflection mirror13A through the opening134A, thereby sufficiently achieving the object of the present invention. The same applies to the sub-reflection mirrors13D and13E shown inFIGS. 10A to 11B.

Although the sub-reflection mirror13A shown inFIGS. 6A and 6Bin the second exemplary embodiment has the openings134A and134B respectively formed on the upper end and the lower end of the neck section131, it may have openings on other positions at the neck section131in addition to the openings134A and the134B. The same applies to the sub-reflection mirrors13D and13E shown inFIGS. 10A to 11B.

In the second exemplary embodiment, the temperature rise of the connecting portion between the light source lamp11and the sub-reflection mirror13A is suppressed due to the natural convection. However, without limiting thereto, a cooling fan may be installed in the projector1so that the cooling air sent from the cooling fan flows into the light source device10. The cooling air then flows in the clearance between the light source lamp11and the sub-reflection mirror13A through the opening134B, and flows from the clearance between the light source lamp11and the sub-reflection mirror13A to the outside of the sub-reflection mirror13A through the opening134A. The same applies to the sub-reflection mirrors13D and13E shown inFIGS. 10A to 11B. According to such configuration, the air heated by the light source lamp11and staying in the clearance between the light source lamp11and the sub-reflection mirror13A can be forcibly discharged to the outside of the sub-reflection mirror13A. This suppresses the temperature rise of the connecting portion between the light source lamp11and the sub-reflection mirror13A more effectively.

In the case that the forced cooling with use of the above-described cooling fan is performed, the position of the openings134A and134B to be formed is not limited to the position described in the second exemplary embodiment. Specifically, in the above-described configuration, in order to send the cooling air in the direction orthogonal to the paper inFIG. 6A, the openings134A and134B are formed on respective end positions (upper end position and lower end position) crossing with a flow path of the cooling air on the neck section131. Alternatively, in order to send the cooling air in other directions, two openings are formed on respective end positions crossing with the flow path of the cooling air on the neck section131. The same applies to the sub-reflection mirrors13D and13E shown inFIGS. 10A to 11B.

In the respective exemplary embodiments, the above-described cutting portion131A and/or the opening134may be formed at the neck section121of the ellipsoidal reflector12. In this case, a cutting portion and/or an opening to be formed at the neck section121may be the above-described cutting portion131A and/or opening134′.

Though the projector1using three liquid crystal panels42R,42G and42B is taken as an example in the above exemplary embodiments, the present invention may be applied to a projector using a single liquid crystal panel, two liquid crystal panels or more than three liquid crystal panels.

Though the transmissive liquid crystal panel separately having a light-incident side and a light-irradiation side is used in the above exemplary embodiments, a reflective optical liquid crystal panel having common light-incident side and light-irradiation side may be used.

Though the liquid crystal panel is used as the optical modulator in the above exemplary embodiments, an optical modulator other than the liquid crystal panel such as a device using a micro-mirror may be used. In such case, the polarization plates at the light-incident side and the light-irradiation side can be omitted.

Though the front-type projector that projects an image in a direction from which a screen is observed taken as an example in the above exemplary embodiments, the present invention may be applied to a rear-type projector that projects an image in a direction opposite to the direction from which the screen is observed.

Though the light source device of the present invention is employed in a projector in the above exemplary embodiments, the light source device may be applied in other optical equipments.

Although the best configuration for implementing the present invention has been disclosed above, the present invention is not limited to thereto. In other words, the present invention is mainly illustrated and described on the specific exemplary embodiments, however, a person skilled in the art can modify the specific configuration such as shape, material, quantity in the above-described exemplary embodiment as long as a technical idea and an object of the present invention can be achieved.

Therefore, the description that limits the shape and the material is only the example to make the present invention easily understood, but does not intend to limit the present invention, so that the present invention includes the description using a name of component without a part of or all of the limitation on the shape and the material etc.

The priority applications No. JP2004-085042 and JP2004-125768 upon which this patent application is based are hereby incorporated by reference.