Patent Publication Number: US-2017371234-A1

Title: Wavelength conversion device, lighting device, and projector

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The entire disclosure of Japanese Patent Application No. 2016-127697, filed Jun. 28, 2016 and No. 2017-055478, filed Mar. 22, 2016 is expressly incorporated by reference herein. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a wavelength conversion device, a lighting device, and a projector. 
     2. Related Art 
     There has been known a light source device that performs wavelength conversion of excitation light emitted from a solid-state light source and emits fluorescent light (see, for example, JP-A-2013-156657 (Patent Literature 1)). 
     The light source device described in Patent Literature 1 includes three fluorescent-light generation devices that generate lights in wavelength bands of red, green, and blue. The fluorescent-light generation device includes an excitation light source, a condensing lens, a phosphor, a mirror surface box that supports the phosphor, a dichroic filter that transmits emitted light and reflects excitation light, and a condensing optical system. In the fluorescent-light generation device, excitation light emitted from the excitation light source is made incident on the phosphor via the condensing lens and an incident opening of the mirror surface box that supports the phosphor. Light subjected to wavelength conversion by the phosphor is emitted to the outside via the dichroic filter and the condensing optical system. 
     Incidentally, heat is generated in the phosphor that performs the wavelength conversion of the incident excitation light. When the temperature of the phosphor rises, adverse effects such as deterioration in wavelength conversion efficiency occur. 
     On the other hand, in the fluorescent-light generation device of the light source device described in Patent Literature 1, a component for cooling the phosphor is not provided. Therefore, the temperature of the phosphor (a wavelength conversion element) easily rises. Emission efficiency (wavelength conversion efficiency) of light emitted from the wavelength conversion element is easily deteriorated. 
     As measures against this problem, it is conceivable to extend a substrate, which supports the wavelength conversion element in a direction orthogonal to an incident direction of the excitation light, in the orthogonal direction and expands a heat radiation area of heat conducted from the wavelength conversion element. However, when the substrate is expanded in this way, the heat conducted to the substrate is easily filled in a substantially center portion of the substrate. The heat conducted from the wavelength conversion element cannot be efficiently radiated. Therefore, the wavelength conversion element cannot be effectively cooled. 
     SUMMARY 
     An advantage of some aspects of the invention is to provide a wavelength conversion device, a lighting device, and a projector that can suppress deterioration in wavelength conversion efficiency. 
     A wavelength conversion device according to a first aspect of the invention includes: a wavelength conversion element configured to convert at least a part of incident excitation light into converted light having a wavelength different from a wavelength of the excitation light and emit the converted light; and a substrate connected to the wavelength conversion element in a crossing direction crossing an incident direction of the excitation light on the wavelength conversion element and configured to radiate heat transferred from the wavelength conversion element. A dimension of the substrate along the incident direction is larger than a dimension of the wavelength conversion element along the incident direction. 
     According to the first aspect, it is possible to set an area of a cross section orthogonal to the crossing direction in the substrate (hereinafter referred to as substrate side sectional area) larger than an area of a cross section orthogonal to the crossing direction in the wavelength conversion element. Therefore, it is possible to increase the substrate side sectional area compared with when the dimension along the incident direction in the substrate is equal to or smaller than the dimension along the same direction in the wavelength conversion element. It is possible to expand an area of a conduction path on which heat transferred from the wavelength conversion element is conducted in a direction away from the wavelength conversion element on the inside of the substrate. Consequently, it is possible to reduce thermal resistance of the substrate. It is possible to efficiently conduct the heat, which is transferred from the wavelength conversion element to the substrate, to a part away from the wavelength conversion element in the substrate without allowing the heat to be filled in the inside of the substrate. Therefore, it is possible to effectively cool the wavelength conversion element. It is possible to suppress deterioration in wavelength conversion efficiency in the wavelength conversion element. 
     In the first aspect, it is preferable that the substrate includes an opening section piercing through the substrate along the incident direction, the wavelength conversion element being fit in the opening section. 
     With such a configuration, in a state in which the wavelength conversion element is surrounded by an inner end face of the opening section, the wavelength conversion element is connected to the inner end face. Consequently, for example, compared with when only a part of a side surface of the wavelength conversion element is connected to the substrate, it is possible to expand a contact area of the wavelength conversion element and the substrate. Therefore, it is possible to efficiently transfer the heat generated in the wavelength conversion element to the substrate. 
     In the first aspect, it is preferable that the substrate includes a projecting section located on at least either one of an incident side of the excitation light and an opposite side of the incident side of the excitation light with respect to the wavelength conversion element, and the projecting section includes an inclined surface further away from the wavelength conversion element toward a disposition side of the projecting section with respect to the wavelength conversion element. 
     With such a configuration, it is possible to surely set the dimension of the substrate larger than the dimension of the wavelength conversion element. Therefore, it is possible to surely set the substrate side sectional area larger than the element side sectional area. Consequently, it is possible to efficiently conduct the heat, which is transferred from the wavelength conversion element, in a direction away from the wavelength conversion element in the substrate. Therefore, it is possible to more effectively cool the wavelength conversion element. 
     Compared with a configuration without the inclined surface (e.g., a configuration in which the inner end face of the opening section extends along the incident direction), it is possible to suppress at least either one of light made incident on the wavelength conversion element and light emitted from the wavelength conversion element from being blocked by the substrate. 
     In the first aspect, it is preferable that the projecting section includes an incident-side projecting section located on an incident side of the excitation light with respect to the wavelength conversion element, and an incident-side inclined surface, which is the inclined surface in the incident-side projecting section, reflects the incident light. 
     With such a configuration, as explained above, compared with when the incident-side inclined surface is absent, it is possible to suppress the excitation light made incident on the wavelength conversion element from being blocked by the substrate. 
     Even when the excitation light is made incident on the incident-side inclined surface, since the excitation light is reflected by the incident-side inclined surface, it is possible to easily make the excitation light incident on the wavelength conversion element. Therefore, it is possible to effectively use the excitation light made incident on the wavelength conversion device. 
     In the first aspect, it is preferable that the wavelength conversion element includes: an incident surface on which the excitation light is made incident; and an emission surface located on an opposite side of the incident surface, the converted light being emitted from the emission surface, the projecting section includes an emission-side projecting section located on an opposite side of the incident side of the excitation light with respect to the wavelength conversion element, the opposite side being an emission side of the converted light from the emission surface, and an emission-side inclined surface, which is the inclined surface in the emission-side projecting section, reflects the incident light. 
     With such a configuration, when the wavelength conversion element is a wavelength conversion element of a transmission type that emits the converted light along the incident direction of the excitation light, compared with when the emission-side inclined surface is absent, it is possible to suppress the light emitted from the wavelength conversion element from being blocked by the substrate. 
     Even when light emitted from the emission surface is made incident on the emission-side inclined surface, since the light is reflected by the emission-side inclined surface, it is possible to easily emit the converted light to the outside of the wavelength conversion device. Therefore, it is possible to suppress a decrease in a light amount of light emitted from the wavelength conversion device. 
     In the first aspect, it is preferable that at least a part of the emission-side inclined surface is curved in a direction further away from the wavelength conversion element toward the emission side of the converted light. 
     The converted light emitted from the wavelength conversion element is emitted to diffuse from the emission surface of the wavelength conversion element. 
     On the other hand, with the configuration explained above, it is possible to easily separate the emission-side projecting section from the wavelength conversion element. Therefore, it is possible to suppress the light emitted from the wavelength conversion element from being incident on the emission-side projecting section. It is possible to suppress the emission-side projecting section from blocking the light. Therefore, it is possible to suppress a decrease in a light amount of the light emitted from the wavelength conversion device. 
     Since the emission-side inclined surface is curved, compared with when the emission-side inclined surface is formed in a flat shape, it is possible to easily expand an area of the emission-side inclined surface, that is, a heat radiation area of the heat transferred to the substrate. Therefore, it is possible to improve cooling efficiency of the wavelength conversion element. 
     In the first aspect, it is preferable that the wavelength conversion element is formed by an inorganic material. 
     Note that ceramic and the like can be illustrated as the inorganic material. 
     With such a configuration, compare with when the wavelength conversion element is formed by an organic material, it is possible to suppress deterioration of the wavelength conversion element. Therefore, it is possible to improve the reliability of the wavelength conversion device. 
     A lighting device according to a second aspect of the invention includes: the wavelength conversion device described above; and a light source configured to emit the excitation light. 
     According to the second aspect, it is possible to achieve effects same as the effects of the wavelength conversion device according to the first aspect. Consequently, it is possible to improve the reliability and the stability of the lighting device. 
     In the second aspect, it is preferable that the excitation light is blue light, and the converted light includes red light and green light. 
     With such a configuration, by adjusting a type and concentration of the phosphor included in the wavelength conversion element, it is possible to configure the lighting device such that white light including the excitation light and the converted light is emitted from the wavelength conversion element. Consequently, it is unnecessary to separately provide a component that divides the excitation light, which is the blue light, emitted from the light source and combines the excitation light with the converted light emitted from the wavelength conversion element and a light source that emits the blue light combined with the converted light. Therefore, it is possible to simplify the configuration of the lighting device. 
     A projector according to a third aspect of the invention includes: the lighting device described above; a light modulation device configured to modulate light emitted from the lighting device; and a projection optical device configured to project the light modulated by the light modulation device. 
     According to the third aspect, it is possible to achieve effects same as the effects of the wavelength conversion device according to the first aspect and the lighting device according to the second aspect. Consequently, it is possible to improve the reliability and the stability of the projector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is a schematic diagram showing the configuration of a projector according to an embodiment of the invention. 
         FIG. 2  is a schematic diagram showing the configuration of a lighting device of the projector according to the embodiment. 
         FIG. 3  is a front view of a wavelength conversion device according to the embodiment viewed from an incident side of excitation light. 
         FIG. 4  is a sectional view showing the wavelength conversion device according to the embodiment. 
         FIG. 5  is a sectional view showing a wavelength conversion device according to a first modification of the embodiment. 
         FIG. 6  is a sectional view showing a wavelength conversion device according to a second modification of the embodiment. 
         FIG. 7  is a sectional view showing a wavelength conversion device according to a third modification of the embodiment. 
         FIG. 8  is a sectional view showing a wavelength conversion device according to a fourth modification of the embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     An embodiment of the invention is explained below with reference to the drawings. 
     Schematic Configuration of a Projector 
       FIG. 1  is a schematic diagram showing a schematic configuration of a projector  1  according to this embodiment. 
     The projector  1  is a display apparatus that modulates a light beam emitted from a light source provided on the inside, forms an image corresponding to image information, and enlarges and projects the image on a projection surface PS such as a screen. 
     The projector  1  includes, as shown in  FIG. 1 , an exterior housing  2  and an image projection device  3  housed in the exterior housing  2 . Besides, although not shown in the figure, the projector  1  includes a control device that controls the projector  1 , a cooling device that cools a cooling target, and a power supply device that supplies electronic power to electronic components configuring the projector  1 . 
     As explained in detail below, the projector  1  includes a wavelength conversion element  43  that converts at least a part of incident excitation light into fluorescent light (converted light) and emits the fluorescent light and a substrate  41  that supports the wavelength conversion element  43  and radiates heat conducted from the wavelength conversion element  43 . As one of characteristics of the projector  1 , a dimension along an incident direction of the excitation light in the substrate  41  is larger than a dimension along the incident direction in the wavelength conversion element  43 . 
     The configuration of the projector  1  is explained below. 
     Configuration of the Image Projection Device 
     The image projection device  3  includes a lighting device  31 , a color separation device  32 , a collimating lens  33 , a plurality of light modulation devices  34 , a color combination device  35 , and a projection optical device  36  respectively disposed on an illumination light axis Ax, which is an optical axis in design. 
     The lighting device  31  emits illumination light WL. Note that the configuration of the lighting device  31  is explained in detail below. 
     The color separation device  32  separates the illumination light WL made incident from the lighting device  31  into three color lights, that is, red light LR, green light LG, and blue light LB. The color separation device  32  includes dichroic mirrors  321  and  322 , total reflection mirrors  323 ,  324 , and  325 , and relay lenses  326  and  327 . 
     The dichroic mirror  321  separates the blue light LB and light including the other color lights (the green light LG and the red light LR) from the illumination light WL emitted from the lighting device  31 . Specifically, the dichroic mirror  321  transmits the blue light LB and reflects the light including the green light LG and the red light LR. 
     The dichroic mirror  322  separates the green light LG and the red light LR from the lights separated by the dichroic mirror  321 . Specifically, the dichroic mirror  322  reflects the green light LG and transmits the red light LR. 
     The total reflection mirror  323  is disposed on an optical path of the blue light LB. The total reflection mirror  323  reflects the blue light LB transmitted by the dichroic mirror  321  toward the light modulation device  34  ( 34 B). 
     The total reflection mirrors  324  and  325  are disposed on an optical path of the red light LR. The total reflection mirrors  324  and  325  guide the red light LR transmitted through the dichroic mirror  322  to the light modulation device  34  ( 34 R). Note that the green light LG is reflected toward the light modulation device  34  ( 34 G) by the dichroic mirror  322 . 
     The relay lenses  326  and  327  are disposed downstream of the dichroic mirror  322  on the optical path of the red light LR. The relay lenses  326  and  327  have a function of compensating for an optical loss of the red light LR caused when the optical path length of the red light LR is longer than the optical path lengths of the blue light LB and the green light LG. 
     The collimating lens  33  collimates light made incident on the light modulation device  34 . Note that the collimating lenses for the color lights of red, green, and blue are respectively represented as  33 R,  33 G, and  33 B. The light modulation devices for the color lights of red, green, and blue are respectively represented as  34 R,  34 G, and  34 B. 
     The plurality of light modulation devices  34  ( 34 R,  34 G, and  34 B) respectively modulate the incident color lights LR, LG, and LB according to image information and form image lights corresponding to the color lights LR, LG, and LB. The light modulation devices  34  are configured by liquid crystal panels that modulate incident lights. Note that incident-side polarizing plates  341  and emission-side polarizing plates  342  are disposed on light incident sides and light emission sides of the light modulation devices  34 R,  34 G, and  34 B. 
     The color combination device  35  combines the image lights made incident from the light modulation devices  34 R,  34 G, and  34 B. In this embodiment, the color combination device  35  is configured by a cross dichroic prism. However, the color combination device  35  may be configured by a plurality of dichroic mirrors. 
     The projection optical device  36  projects the image light combined by the color combination device  35  on the projection surface PS such as the screen. 
     An enlarged image is projected on the projection surface PS by the configuration explained above. 
     Configuration of the Lighting Device 
       FIG. 2  is a schematic diagram showing the configuration of the lighting device  31  in the projector  1  in this embodiment. 
     The lighting device  31  emits uniform illumination light WL, a polarization direction of which is aligned, to the color separation device  32 . The lighting device  31  includes a solid-state light source  311 , a condensing optical device  312 , the wavelength conversion device  4 , a collimate lens  313 , a first lens array  314 , a second lens array  315 , and a polarization conversion element  316 . 
     The solid-state light source  311  is a laser light source that emits excitation light (the peak of light emission intensity: approximately 455 nm), which is blue laser light. The solid-state light source  311  is equivalent to the light source according to the invention. 
     Note that the solid-state light source  311  may include one laser light source (LD: Laser Diode) or may include a plurality of laser light sources. A solid-state light source that emits blue light, the peak of light emission intensity of which is a wavelength other than 455 nm, as excitation light may be adopted. 
     The condensing optical device  312  includes a first lens  3121  and a second lens  3122 . The condensing optical device  312  condenses, with the first lens  3121  and the second lens  3122 , excitation light made incident from the solid-state light source  311  and makes the excitation light incident on the wavelength conversion device  4 . As the first lens  3121  and the second lens  3122 , a combination of a convex lens and a concave lens can be illustrated. 
     The wavelength conversion device  4  converts a part of incident excitation light into converted light having a wavelength different from the wavelength of the excitation light and emits light including the converted light to the opposite side of an incident side of the excitation light. That is, the wavelength conversion device  4  is a wavelength conversion device of a transmission type that emits, along an incident direction of the excitation light, light including the part of the excitation light and fluorescent light. Note that a detailed configuration of the wavelength conversion device  4  is explained below. 
     The collimate lens  313  substantially collimates light made incident from the solid-state light source  311 . 
     The first lens array  314  includes a plurality of first small lenses  3141  that divide the light made incident from the collimate lens  313  into a plurality of partial light beams. 
     The second lens array  315  includes a plurality of second small lenses  3151  corresponding to the plurality of first small lenses  3141 . The second lens array  315  forms images of the first small lenses  3141  made incident from the first lens array  314  in the vicinities of image formation regions of the light modulation devices  34 R,  34 G, and  34 B to thereby superimpose the plurality of partial light beams on the image formation regions. Note that the second small lenses  3151  are also arrayed in a matrix shape in a plane orthogonal to the illumination optical axis Ax. 
     The polarization conversion element  316  has a function of aligning polarization directions of the partial light beams divided by the first lens array  314 . 
     Configuration of the Wavelength Conversion Device 
       FIG. 3  is a plan view of the wavelength conversion device  4  viewed from a light incident side.  FIG. 4  is a sectional view of the wavelength conversion device  4 . 
     The wavelength conversion device  4  includes, as shown in  FIGS. 3 and 4 , the substrate  41  and the wavelength conversion element  43 . 
     Note that, in the following explanation, a traveling direction of excitation light made incident from the solid-state light source  311  is represented as a +Z direction. Two directions orthogonal to the +Z direction and orthogonal to each other are respectively represented as a +X direction and a +Y direction. Although not shown in the figures, the opposite direction of the +Z direction is represented as a −Z direction. Among these directions, the +Z direction is a direction along an incident direction of the excitation light on the wavelength conversion element  43 . The +X direction and the +Y direction are directions included in a crossing direction crossing the incident direction. 
     Configuration of the Wavelength Conversion Element 
     The wavelength conversion element  43  is explained first. 
     The wavelength conversion element  43  converts apart of incident excitation light EL into fluorescent light (converted light) having a wavelength different from the wavelength of the excitation light EL and emits white emitted light LT (see  FIG. 4 ) including the fluorescent light and another part of the excitation light EL to the opposite side of an incident side of the excitation light EL. Specifically, the wavelength conversion element  43  converts a part of the excitation light EL made incident on the wavelength conversion element  43  into fluorescent light (a peak wavelength: approximately 550 nm) including red light and green light. The wavelength conversion element  43  includes a mixture of a yellow phosphor and either one of a green phosphor and a red phosphor. The concentrations of the phosphors are set on the basis of a wavelength distribution of the illumination light WL emitted from the lighting device  31 . The phosphors are formed by, for example, a ceramic phosphor formed by ceramic or a phosphor obtained by mixing phosphor powder and a glass binder. That is, the wavelength conversion element  43  is formed by an inorganic material. 
     An Irradiation Region of Excitation Light Made Incident on the Wavelength Conversion Element and an Emission Range of Emitted Light 
     The excitation light EL made incident on the wavelength conversion element  43  is made incident in an irradiation region R 1  having a substantially circular shape indicated by an alternate long and short dash line in  FIGS. 3 and 4  on an incident surface  431  of the wavelength conversion element  43 . 
     On the other hand, as shown in  FIG. 4 , the emitted light LT including excitation light not converted by the wavelength conversion element  43  and fluorescent light converted by the wavelength conversion element  43  is emitted from an emission surface  432 , which is a surface on the +Z-direction side in the wavelength conversion element  43 . The emitted light LT is diffused and emitted from the emission surface  432  as indicated by an alternate long and two short dashes line in  FIG. 4 . 
     Configuration of the Substrate 
     The substrate  41  functions as a supporting member that supports the wavelength conversion element  43  and functions as a heat radiation member that radiates heat transferred from the wavelength conversion element  43 . As shown in  FIG. 3 , the substrate  41  is formed in a substantially rectangular shape when viewed from the incident side (the −Z-direction side) of the excitation light EL. The substrate  41  includes, as shown in  FIG. 4 , a main body section  411  connected to the wavelength conversion element  43  and a projecting section  412  formed integrally with the main body section  411 . 
     Note that, in this embodiment, the substrate  41  is configured by aluminum having relatively high thermal conductivity. However, the material of the substrate  41  is not limited to this. For example, the substrate  41  may be configured by another material as long as the material is a material having high thermal conductivity and high heat radiation such as other kind of metal such as magnesium or ceramic. 
     As shown in  FIGS. 3 and 4 , the main body section  411  includes an opening section  4111 , in which the wavelength conversion element  43  is fit, in substantially the center. The opening section  4111  is formed in a substantially rectangular shape when viewed from the incident side of the excitation light EL. The opening section  4111  pierces through the main body section  411  (the substrate  41 ) along the incident direction (the +Z direction) of the excitation light EL. A reflection layer  42  is formed on an inner end face of the opening section  4111 . The wavelength conversion element  43  is disposed in the opening section  4111  to be connected to the inner end face via the reflection layer  42 . That is, a side surface  433  crossing a crossing direction (e.g., the +X direction and the +Y direction) crossing the +Z direction in the wavelength conversion element  43  is connected to the inner end face of the opening section  4111 . 
     The projecting section  412  is a part including the emission-side projecting section according to the invention. The projecting section  412  projects from the main body section  411  to the +Z-direction side (the opposite side of the incident side of the excitation light EL). The projecting section  412  includes an inclined surface  4121  inclined in a direction further away from the wavelength conversion element  43  toward the +Z direction from an end portion on the +Z-direction side on the inner end face of the opening section  4111 . In other words, the projecting section  412  includes the inclined surface  4121  inclined in a direction further away from the inner end face of the opening section  4111  toward the +Z direction. Since the projecting section  412  is provided in the substrate  41 , a dimension along the +Z direction of the substrate  41  is larger than a dimension along the +Z direction of the wavelength conversion element  43 . 
     As explained above, the emitted light LT is diffused and emitted from the emission surface  432  of the wavelength conversion element  43 . Therefore, when an inclination angle of the inclined surface  4121  with respect to the +Z direction is small, a phenomenon called optical vignetting easily occurs in which a part of the emitted light LT is made incident on the projecting section  412  (the inclined surface  4121 ) and light on the outer circumference side in the emitted light LT is blocked. 
     On the other hand, the inclined surface  4121  (an emission-side inclined surface) is formed as a reflection surface on which the reflection layer  42  is formed. Therefore, since the part of the emitted light LT made incident on the projecting section  412  is reflected by the inclined surface  4121 , an emitted light amount from the wavelength conversion device  4  is suppressed from being reduced by the optical vignetting. Substantially the entire emitted light LT is made incident on the collimate lens  313 . If the inclination angle of the inclined surface  4121  with respect to the +Z direction is an angle that does not cause the optical vignetting, the reflection layer  42  maybe absent on the inclined surface  4121 . 
     Note that the reflection layer  42  is formed on the inner end face of the opening section  4111  and the inclined surface  4121  by, for example, vapor deposition. The heat of the wavelength conversion element  43  is conducted to the substrate  41  in the inner surfaces via the reflection layer  42 . 
     Thickness Dimension of the Substrate with Respect to the Wavelength Conversion Element 
     In the wavelength conversion device  4 , a dimension L 2  of the substrate  41  along the +Z direction (a sum of a dimension L 21  of the main body section  411  and a dimension L 22  of the projecting section  412  along the +Z direction) is set to approximately 1.9 times as large as a dimension L 1  of the wavelength conversion element  43  along the +Z direction. 
     Specifically, in the wavelength conversion device  4 , the dimension L 1  of the wavelength conversion element  43  along the +Z direction is set to approximately 1 mm. On the other hand, the dimension L 2  of the substrate  41  along the +Z direction is set to approximately 1.9 mm. Specifically, the dimension L 21  of the main body section  411  along the +Z direction is set to approximately 1 mm same as the dimension L 1  of the wavelength conversion element  43  along the +Z direction. The dimension L 22  of the projecting section  412  along the +Z direction is set to approximately 0.9 mm smaller than the dimension L 1  of the wavelength conversion element  43  along the +Z direction. 
     Effects of the Embodiment 
     The projector  1  according to this embodiment explained above achieves effects explained below. 
     The dimension L 2  along the +Z direction of the substrate  41  that supports the wavelength conversion element (the dimension L 2  along the incident direction of the excitation light EL) is larger than the dimension L 1  along the +Z direction of the wavelength conversion element  43 . Consequently, it is possible to set an area of a cross section orthogonal to the crossing direction (e.g., the +X direction and the +Y direction) crossing the +Z direction in the substrate  41  larger than an area of a cross section orthogonal to the crossing direction in the wavelength conversion element  43  (a contact area of contact with the inner end face of the opening section  4111  in the wavelength conversion element  43 ). Therefore, since it is possible to set the area of the cross section of the substrate  41  large compared with when the dimension L 2  is equal to or smaller than the dimension L 1 , it is possible to expand a sectional area of a conduction path of heat conducted in a direction away from the wavelength conversion element  43  on the inside of the substrate  41 . Consequently, it is possible to reduce the thermal resistance of the substrate  41 . It is possible to efficiently conduct heat, which is transferred from the wavelength conversion element  43  to the substrate  41 , to a part away from the wavelength conversion element  43  in the substrate  41  without allowing the heat to be filled in the inside of the substrate  41 . It is possible to effectively radiate the heat in the substrate  41 , the area of the cross section of which is larger than the area of the cross section of the wavelength conversion element  43 . Therefore, it is possible to effectively cool the wavelength conversion element  43 . It is possible to suppress wavelength conversion efficiency from being deteriorated in the wavelength conversion element  43 . 
     The wavelength conversion element  43  is fit in the opening section  4111  of the substrate  41 . Therefore, the wavelength conversion element  43  is connected to the inner end face of the opening section  4111  in a state in which the side surface  433  crossing in the crossing direction crossing the +Z direction is surrounded by the inner end face of the opening section  4111 . Accordingly, for example, compared with when only a part of the side surface  433  is connected to the substrate  41 , it is possible to expand the contact area of the wavelength conversion element  43  and the substrate  41 . Therefore, it is possible to efficiently transfer heat generated in the wavelength conversion element  43  to the substrate  41 . 
     The substrate  41  includes the projecting section  412  located in the +Z direction (the opposite side of the incident side of the excitation light EL) with respect to the wavelength conversion element  43 . Accordingly, it is possible to surely set the area of the cross section of the substrate  41  larger than the area of the cross section of the wavelength conversion element  43 . Consequently, it is possible to efficiently conduct the heat which is transferred from the wavelength conversion element  43 , in a direction away from the wavelength conversion element  43  in the substrate  41 . Therefore, it is possible to more effectively cool the wavelength conversion element  43 . 
     The projecting section  412  includes the inclined surface  4121  further away from the wavelength conversion element  43  toward the +Z direction. Accordingly, compared with when the inclined surface  4121  is absent (e.g., when the inner end face of the opening section  4111  extends along the +Z direction), it is possible to suppress the emitted light LT emitted from the wavelength conversion element  43  from being blocked by the projecting section  412 . 
     The inclined surface  4121 , on which the reflection layer  42  is formed, functions as a reflection surface. Accordingly, even when a part of the emitted light LT diffused and emitted from the wavelength conversion element  43  is made incident on the projecting section  412 , it is possible to reflect the part of the emitted light LT with the inclined surface  4121 . Therefore, since it is possible to easily emit the part of the emitted light LT to the outside of the wavelength conversion device  4 , it is possible to easily make substantially the entire emitted light LT incident on the collimate lens  313  located downstream on the optical path. 
     The wavelength conversion element  43  is formed by an inorganic material. Accordingly, compared with when the wavelength conversion element  43  is formed by an organic material, it is possible to suppress deterioration of the wavelength conversion element  43 . 
     Therefore, it is possible to improve the reliability of the wavelength conversion device  4 . 
     The lighting device  31  including the wavelength conversion device  4  can effectively cool the wavelength conversion element  43 . Therefore, it is possible to suppress deterioration in wavelength conversion efficiency in the wavelength conversion element  43 . Consequently, it is possible to stably convert the wavelength of the excitation light EL made incident on the wavelength conversion device  4  (the wavelength conversion element  43 ). The lighting device  31  can stably emit illumination light. Therefore, it is possible to improve the reliability and the stability of the lighting device  31 . 
     The excitation light EL made incident on the wavelength conversion element  43  is blue light. The converted light of the excitation light EL converted and emitted by the wavelength conversion element  43  is fluorescent light including red light and green light. Accordingly, as explained above, by adjusting the type and the concentration of the phosphor such that a part of the excitation light EL and the fluorescent light are emitted from the wavelength conversion element  43 , it is possible to configure the lighting device  31  such that the emitted light LT, which is white light, is emitted. Consequently, it is unnecessary to separately provide a component that divides the excitation light EL emitted from the solid-state light source  311  and combines the excitation light EL with the fluorescent light emitted from the wavelength conversion element  43  and a light source that emits the blue light combined with the fluorescent light. Therefore, it is possible to simplify the configuration of the lighting device  31 . 
     The projector  1  includes the lighting device  31  including the wavelength conversion device  4 . Therefore, it is possible to modulate the illumination light stably emitted from the lighting device  31  and form and project an image. Therefore, it is possible to improve the reliability and the stability of the projector  1 . 
     Modifications of the Embodiment 
     The invention is not limited to the embodiment. Modifications, improvements, and the like within a range in which the object of the invention can be achieved are included in the invention. 
     In the embodiment, the substrate  41  of the wavelength conversion device  4  includes the main body section  411  and the projecting section  412 . The projecting section  412  is located on the emission side of the emitted light LT with respect to the wavelength conversion element  43 . However, the invention is not limited to this. The shape of the substrate  41  may be other shapes. For example, wavelength conversion devices  4 A to  4 D explained below may be adopted in the lighting device  31  instead of the wavelength conversion device  4 . 
     Note that, in the following explanation, portions same as or substantially the same as the portions explained above are denoted by the same reference numerals and signs and explanation of the portions is omitted. 
     First Modification 
       FIG. 5  is a sectional view showing the wavelength conversion device  4 A, which is a first modification of the wavelength conversion device  4 . 
     The wavelength conversion device  4 A includes components and functions same as the components and the functions of the wavelength conversion device  4  except that the wavelength conversion device  4 A includes a substrate  41 A instead of the substrate  41  as shown in  FIG. 5 . 
     The substrate  41 A is a member including the main body section  411  and a projecting section  412 A, which are integrally formed. The projecting section  412 A includes an incident-side projecting section  413 A and an emission-side projecting section  414 A. 
     The incident-side projecting section  413 A is a part projecting to the −Z direction (the incident side of the excitation light EL) in the substrate  41 A. The incident-side projecting section  413 A includes an incident-side inclined surface  4131 A, which is an inclined surface inclined in a direction further away from the wavelength conversion element  43  fit in the opening section  4111  toward the −Z direction from an end portion on the −Z-direction side on the inner end face of the opening section  4111 . The incident-side inclined surface  4131 A is a reflection surface on which the reflection layer  42  is formed. 
     The emission-side projecting section  414 A is a part projecting to the +Z-direction side (the opposite side of the incident side of the excitation light EL; the emission side of the emitted light LT) in the substrate  41 A. The emission-side projecting section  414 A includes an emission-side inclined surface  4141 A, which is an inclined surface inclined in a direction further away from the wavelength conversion element  43  toward the +Z direction from an end portion on the +Z-direction side on the inner end face of the opening section  4111 . The emission-side inclined surface  4141 A is a reflection surface on which the reflection layer  42  is formed. 
     Inclination angles with respect to the +Z direction of the incident-side inclined surface  4131 A and the emission-side inclined surface  4141 A are the same. The inclination angles are larger than an inclination angle with respect to the +Z direction of the inclined surface  4121 . 
     The inclination angle of the incident-side inclined surface  4131 A is set to an angle at which the excitation light EL made incident on the wavelength conversion element  43  is not made incident on the incident-side projecting section  413 A (the incident-side inclined surface  4131 A). Similarly, the inclination angle of the emission-side inclined surface  4141 A is set to an angle at which occurrence of the optical vignetting explained above is suppressed and the emitted light LT diffused and emitted from the emission surface  432  is not made incident on the emission-side projecting section  414 A (the emission-side inclined surface  4141 A). Therefore, the reflection layer  42  does not have to be formed on the inclined surfaces  4131 A and  4141 A. 
     In the wavelength conversion device  4 A, a dimension L 3  of the substrate  41 A along the +Z direction (a sum of a dimension L 31  of the main body section  411 , a dimension L 32  of the incident-side projecting section  413 A, and a dimension L 33  of the emission-side projecting section  414 A along the +Z direction) is set to approximately 1.7 times as large as the dimension L 1  of the wavelength conversion element  43  along the +Z direction. 
     Specifically, in the wavelength conversion device  4 A, the dimension L 3  of the substrate  41 A along the +Z direction is set to approximately 1.7 mm. The dimension L 31  of the main body section  411  along the +Z direction is set to approximately 1 mm same as the dimension L 1  of the wavelength conversion element  43  along the +Z direction. On the other hand, the dimension L 32  of the incident-side projecting section  413 A and the dimension L 33  of the emission-side projecting section  414 A along the +Z direction are respectively set to approximately 0.35 mm. 
     In this way, the dimension L 3  of the substrate  41 A along the +Z direction is larger than the dimension L 1  of the wavelength conversion element  43  along the +Z direction. Therefore, as in the substrate  41 , compared with when the dimension L 3  is equal to or smaller than the dimension L 1 , it is possible to expand a sectional area of a conduction path of heat conducted in a direction away from the wavelength conversion element  43  on the inside of the substrate  41 A. Consequently, it is possible to reduce the thermal resistance of the substrate  41 A. It is possible to efficiently conduct heat, which is transferred from the wavelength conversion element  43  to the substrate  41 A, to a part away from the wavelength conversion element  43  in the substrate  41  without allowing the heat to be filled in the inside of the substrate  41 A. Therefore, it is possible to effectively cool the wavelength conversion element  43 . It is possible to suppress deterioration in wavelength conversion efficiency in the wavelength conversion element  43 . 
     Effects of the First Modification 
     The wavelength conversion device  4 A explained above is adopted in the lighting device  31  instead of the wavelength conversion device  4 . Consequently, it is possible to achieve effects explained below besides achieving effects same as the effects of the lighting device  31  including the wavelength conversion device  4 . 
     The substrate  41 A includes the incident-side projecting section  413 A and the emission-side projecting section  414 A. Accordingly, compared with when the projecting sections  413 A and  414 A are absent, it is possible to expand an area of the conduction path. It is possible to efficiently conduct heat, which is transferred from the wavelength conversion element  43 , to a part away from the wavelength conversion element  43  without allowing the heat to be filled in the inside of the substrate  41 A. Therefore, it is possible to effectively cool the wavelength conversion element  43 . It is possible to suppress wavelength conversion efficiency from being deteriorated in the wavelength conversion element  43 . 
     The incident-side projecting section  413 A includes the incident-side inclined surface  4131 A. The emission-side projecting section  414 A includes the emission-side inclined surface  4141 A. The reflection layer  42  is formed on the inclined surfaces  4131 A and  4141 A. Accordingly, even when the excitation light EL is made incident on the incident-side inclined surface  4131 A, it is possible to reflect the excitation light EL on the incident-side inclined surface  4131 A. Even when the emitted light LT is made incident on the emission-side inclined surface  4141 A, it is possible to reflect the emitted light LT on the emission-side inclined surface  4141 A. Therefore, it is possible to suppress a decrease in a light amount of the excitation light EL made incident on the wavelength conversion element  43  and a decrease in a light amount of the emitted light LT emitted from the wavelength conversion element  43 . It is possible to suppress a decrease in a light amount of the illumination light emitted from the wavelength conversion device  4 A and the lighting device  31 . 
     Second Modification 
       FIG. 6  is a sectional view showing a wavelength conversion device  4 B, which is a second modification of the wavelength conversion device  4 . 
     The wavelength conversion device  4 B includes components and functions same as the components and the functions of the wavelength conversion device  4 A except that the wavelength conversion device  4 B includes a substrate  41 B instead of the substrate  41 A as shown in  FIG. 6 . 
     The substrate  41 B is a member including the main body section  411  and a projecting section  412 B, which are integrally formed. The projecting section  412 B includes an incident-side projecting section  413 B and an emission-side projecting section  414 B. 
     An incident-side inclined surface  4131 B included in the incident-side projecting section  413 B is inclined with respect to the +Z direction like the incident-side inclined surface  4131 A. An emission-side inclined surface  4141 B included in the emission-side projecting section  414 B is inclined with respect to the +Z direction like the emission-side inclined surface  4141 A. However, inclination angles with respect to the +Z direction of the inclined surfaces  4131 B and  4141 B are different from the inclination angles of the inclined surfaces  4131 A and  4141 A. Note that the inclined surfaces  4131 B and  4141 B are also reflection surfaces on which the reflection layer  42  is formed. 
     Specifically, the inclination angle of the incident-side inclined surface  4131 B with respect to the +Z direction is set to an angle smaller than the inclination angle of the incident-side inclined surface  4131 A with respect to the +Z direction. The inclination angle of the incident-side inclined surface  4131 B is also set to an angle at which the excitation light EL made incident on the wavelength conversion element  43  is not made incident on the incident-side inclined surface  4131 B. Therefore, the reflection layer  42  does not have to be formed on the incident-side inclined surface  4131 B. 
     On the other hand, the emission-side inclined surface  4141 B is sharply inclined with respect to the inner end face of the opening section  4111 . The inclination angle of the emission-side inclined surface  4141 B with respect to the +Z direction is set to an angle larger than the inclination angles of the inclined surface  4121  and the emission-side inclined surface  4141 A with respect to the +Z direction. The inclination angle of the emission-side inclined surface  4141 B is also set to an angle at which the emitted light LT is not made incident on the emission-side inclined surface  4141 B. Therefore, the reflection layer  42  does not have to be formed on the emission-side inclined surface  4141 B. 
     In the wavelength conversion device  4 B explained above, a dimension L 4  of the substrate  41 B along the +Z direction (a sum of a dimension L 41  of the main body section  411 , a dimension L 42  of the incident-side projecting section  413 B, and a dimension L 43  of the emission-side projecting section  414 B along the +Z direction) is set to approximately 1.7 times as large as the dimension L 1  of the wavelength conversion element  43  along the +Z direction. 
     Specifically, in the wavelength conversion device  4 B, the dimension L 4  of the substrate  41 B along the +Z direction is set to approximately 1.7 mm. The dimension L 41  of the main body section  411  along the +Z direction is set to approximately 1 mm same as the dimension L 1  of the wavelength conversion element  43  along the +Z direction. On the other hand, the dimension L 43  of the incident-side projecting section  413 B along the +Z direction is set to approximately 0.5 mm. The dimension L 42  of the emission-side projecting section  414 B is set to approximately 0.20 mm. 
     Effects of the Second Modification 
     The wavelength conversion device  4 B explained above is adopted in the lighting device  31  instead of the wavelength conversion device  4 A. Consequently, it is possible to achieve effects explained below besides achieving effects same as the effects of the lighting device  31  including the wavelength conversion device  4 A. 
     The inclination angle of the emission-side inclined surface  4141 B with respect to the +Z direction is larger than the inclination angle of the emission-side inclined surface  4141 A with respect to the +Z direction. Accordingly, it is possible to further suppress the emitted light LT diffused and emitted from the emission surface  432  of the wavelength conversion element  43  from being made incident on the emission-side inclined surface  4141 B. Therefore, it is possible to more effectively suppress the emitted light LT from being blocked by the substrate  41 B (the emission-side projecting section  414 B). 
     Third Modification 
       FIG. 7  is a sectional view showing a wavelength conversion device  4 C, which is a third modification of the wavelength conversion device  4 . 
     The wavelength conversion device  4 C includes components and functions same as the components and the functions of the wavelength conversion device  4 B except that the wavelength conversion device  4 C includes a substrate  41 C instead of the substrate  41 B as shown in  FIG. 6 . 
     The substrate  41 C includes a main body section  411 C and the projecting section  412 B including the incident-side projecting section  413 B and the emission-side projecting section  414 B. The main body section  411 C and the projecting section  412 B are integrally formed. 
     The main body section  411 C includes an extending section  415 C that extends to the wavelength conversion element  43  side. The opening section  4111  is formed in the extending section  415 C. In other words, the inclined surfaces  4131 B and  4141 B of the incident-side projecting section  413 B and the emission-side projecting section  414 B are inclined as explained above from positions a predetermined dimension away from the inner end face of the opening section  4111  in a direction crossing the +Z direction by the length of the extended section  415 C. 
     Note that the reflection layer  42  is formed in a part of the substrate  41 C, which includes the extending section  415 C, opposed to the wavelength conversion element  43 . The wavelength conversion element  43  is connected to the inner end face of the opening section  4111  via the reflection layer  42 . 
     Effects of the Third Modification 
     The wavelength conversion device  4 C explained above is adopted in the lighting device  31  instead of the wavelength conversion device  4 B. Consequently, it is possible to achieve effects explained below besides achieving effects same as the effects of the lighting device  31  including the wavelength conversion device  4 B. 
     Since the main body section  411 C of the substrate  41 C includes the extending section  415 C, compared with the substrate  41 B, it is possible to easily separate the projecting sections  413 B and  414 B from the wavelength conversion element  43 . Consequently, it is possible to further suppress the excitation light EL made incident from the wavelength conversion element  43  from being made incident on the incident-side projecting section  413 B. Further, it is possible to further suppress the emitted light LT emitted from the wavelength conversion element  43  from being made incident on the emission-side projecting section  414 B. Therefore, it is possible to suppress the excitation light EL and the emitted light LT from being blocked by the substrate  41 C. It is possible to suppress a decrease in a light amount of light emitted from the wavelength conversion device  4 C and the lighting device  31 . 
     Fourth Modification 
       FIG. 8  is a sectional view showing a wavelength conversion device  4 D, which is a fourth modification of the wavelength conversion device  4 . 
     The wavelength conversion device  4 D includes components and functions same as the components and the functions of the wavelength conversion device  4  except that the wavelength conversion device  4 D includes a substrate  41 D instead of the substrate  41  as shown in  FIG. 8 . 
     The substrate  41 D is a member including the main body section  411  and a projecting section  412 D, which are integrally formed. The projecting section  412 D includes an incident-side projecting section  413 D and an emission-side projecting section  414 D. 
     The incident-side projecting section  413 D is a part projecting to the −Z-direction side (the incident side of the excitation light EL) in the substrate  41 D. The incident-side projecting section  413 D includes an incident-side inclined surface  4131 D, which is an inclined surface inclined in a direction further away from the wavelength conversion element toward the −Z direction from the end portion on the −Z-direction side on the inner end face of the opening section  4111 . An inclination angle with respect to the +Z direction of the incident-side inclined surface  4131 D is set the same as the incident-side inclined surface  4131 B. The inclination angle is set such that the excitation light EL is not made incident on the incident-side projecting section  413 D. As in the above explanation, the reflection layer  42  is formed on the incident-side inclined surface  4131 D. 
     The emission-side projecting section  414 D is a part projecting to the +Z-direction side (the opposite side of the incident side of the excitation light EL) in the substrate  41 D. The emission-side projecting section  414 D includes an emission-side inclined surface  4141 D inclined in the direction further away from the wavelength conversion element  43  toward the +Z direction from the end portion on the +Z-direction side on the inner end face of the opening section  4111  and a plane  4142 D located on the +Z-direction side with respect to the emission-side inclined surface  4141 D. 
     The emission-side inclined surface  4141 D is curved in a direction further away from the wavelength conversion element  43  toward the +Z direction. For example, a sectional shape along a YZ plane of the emission-side inclined surface  4141 D is formed in a concave shape. 
     The plane  4142 D extends substantially in parallel to the inner end face of the opening section  4111  from the end portion on the +Z-direction side in the emission-side inclined surface  4141 D. 
     The reflection layer  42  is also formed on the emission-side inclined surface  4141 D and the plane  4142 D. 
     In the wavelength conversion device  4 D, a dimension L 5  of the substrate  41 D along the +Z direction (a sum of a dimension L 51  of the main body section  411 , a dimension L 52  of the incident-side projecting section  413 D, and a dimension L 53  of the emission-side projecting section  414 D along the +Z direction) is set to approximately 5.5 times as large as the dimension L 1  of the wavelength conversion element  43  along the +Z direction. 
     Specifically, in the wavelength conversion device  4 D, the dimension L 5  of the substrate  41 D along the +Z direction is set to approximately 7.8 mm. The dimension L 51  of the main body section  411  along the +Z direction is set to approximately 1 mm same as the dimension L 1  of the wavelength conversion element  43  along the +Z direction. On the other hand, the dimension L 52  of the incident-side projecting section  413 D along the +Z direction is set to approximately 2.7 mm. The dimension L 53  of the emission-side projecting section  414 D is set to approximately 4.1 mm. 
     Effects of the Fourth Modification 
     The wavelength conversion device  4 D explained above is adopted in the lighting device  31  instead of the wavelength conversion devices  4 A to  4 C. Consequently, it is possible to achieve effects explained below besides achieving effects same as the effects of the lighting device  31  including the wavelength conversion devices  4 A to  4 C. 
     Since the emission-side inclined surface  4141 D is curved as explained above, it is possible to easily separate the emission-side inclined surface  4141 D (the emission-side projecting section  414 D) from the wavelength conversion element  43 . Consequently, it is possible to suppress the emitted light LT emitted from the wavelength conversion element  43  from being made incident on the emission-side projecting section  414 D. It is possible to suppress the emission-side projecting section  414 D (the substrate  41 D) from blocking the emitted light LT. Therefore, it is possible to suppress a decrease in alight amount of light emitted from the wavelength conversion device  4 D. 
     Since the emission-side inclined surface  4141 D is curved, compared with when the inclined surface  4141 D is formed in a flat shape, it is possible to expand an area of the emission-side inclined surface  4141 D, that is, a heat radiation area of heat transferred to the substrate  41 D. Therefore, it is possible to improve cooling efficiency of the wavelength conversion element  43 . 
     Other Modifications 
     In the embodiment and the modifications explained above, the substrates  41  and  41 A to  41 D include the opening section  4111  that pierces through the substrate  41  along the +Z direction and in which the wavelength conversion element  43  is fit. However, the invention is not limited to this. For example, the substrates  41  and  41 A to  41 D may be configured by a plurality of members that are in contact with the side surface  433  of the wavelength conversion element  43  and support (hold) the wavelength conversion element  43  in the direction crossing the +Z direction. The members configuring the substrates  41  and  41 A to  41 D may be one member. That is, the substrates  41  and  41 A to  41 D only have to be in contact with at least a part of the side surface  433 . The opening section  4111  may be absent. The shape of the opening section  4111  is not limited to the rectangular shape and may be, for example, a circular shape. 
     In the embodiment and the modifications, the substrates  41  and  41 A to  41 D include the projecting section  412  and the emission-side projecting sections  414 A,  414 B, and  414 D projecting in the +Z-direction side with respect to the wavelength conversion element  43 . However, the invention is not limited to this. The substrates  41  and  41 A to  41 D may include only the incident-side projecting section projecting to the incident side of the excitation light with respect to the wavelength conversion element. 
     The incident-side inclined surface of the incident-side projecting section may be curved like the emission-side inclined surface  4141 D. Even when an inclined surface is curved, only a part of the inclined surface may be curved. 
     In the embodiment and the modifications, the wavelength conversion devices  4  and  4 A to  4 D are the wavelength conversion device of the transmission type that emits the emitted light LT along the incident direction of the excitation light EL. That is, the wavelength conversion devices  4  and  4 A to  4 D include the wavelength conversion element  43  in which the incident surface  431  of the excitation light EL and the emission surface  432  of the emitted light LT are on the opposite sides each other. However, the invention is not limited to this. The invention may be applied to a wavelength conversion device of a reflection type that emits the emitted light LT in a direction opposite to the incident direction of the excitation light EL. 
     In the embodiment and the modifications, the projecting sections  412 ,  412 A,  412 B, and  412 D include the inclined surface inclined (curved) in the direction further away from the wavelength conversion element  43  toward the +Z direction or the −Z direction. However, the invention is not limited to this. The projecting sections  412 ,  412 A,  412 B, and  412 D do not have to include the inclined surface. For example, the substrates  41  and  41 A to  41 D may have a configuration in which the inner end face of the opening section  4111  extends to the +Z-direction side or the −Z-direction side with respect to the wavelength conversion element  43  fit in the opening section  4111 . For example, the substrate  41  and  41 A to  41 D may be inclined in a direction further approaching the wavelength conversion element  43  toward the +Z direction or the −Z direction as long as the substrates  41  and  41 A to  41 D do not block the excitation light EL made incident on the wavelength conversion element  43  and the emitted light LT emitted from the wavelength conversion element  43 . 
     In the embodiment and the modifications, the wavelength conversion element  43  is configured by the inorganic material (the ceramic phosphor). However, the invention is not limited to this. For example, the wavelength conversion element  43  may be formed by an organic material such as resin (a phosphor or the like including a resin binder). 
     In the embodiment and the modifications, the reflection layer  42  is formed on the inner end face of the opening section  4111 , the inclined surface  4121 , the incident-side inclined surfaces  4131 A,  4131 B, and  4131 D, the emission-side inclined surfaces  4141 A,  4141 B, and  4141 D, and the plane  4142 D. However, the invention is not limited to this. For example, as explained above, the reflection layer  42  may be absent. 
     For example, if the reflection layer  42  is absent on the inner end face of the opening section  4111 , the side surface  433  of the wavelength conversion element  43  and the inner end face of the opening section  4111  are in direct contact with each other. Therefore, it is possible to more efficiently transfer the heat of the wavelength conversion element  43  to the inner end face of the opening section  4111  and the substrate  41  functioning as the heat radiation member. 
     In the embodiment and the modifications, the lighting device  31  includes, as the light source that emits the excitation light made incident on the wavelength conversion devices  4  and  4 A to  4 D, the solid-state light source  311  that emits the excitation light having the peak wavelength in the wavelength region of approximately 455 nm. The wavelength conversion device  4  emits, as the converted light, the fluorescent light including the green light and the red light. However, the invention is not limited to this. The wavelengths of the excitation light and the converted light are not limited to the above as long as the wavelength of the light made incident on the wavelength conversion element  43  and the wavelength of the light generated in the wavelength conversion element  43  are different. 
     The wavelength conversion element  43  converts a part of the incident excitation light EL into the fluorescent light, which is the converted light, and emits the emitted light LT including another part of the excitation light and the converted light. 
     However, the invention is not limited to this. The wavelength conversion element  43  may be configured to convert the wavelength of the entire incident excitation light into the wavelength of the converted light. 
     In the embodiment and the modifications, the dimensions L 2  to L 5  of the substrates  41  and  41 A to  41 D in the +Z direction are set to approximately 1.9 times, approximately 1.7 times, and approximately 5.5 times as large as the dimension L 1  of the wavelength conversion element  43  in the +Z direction. However, the invention is not limited to this. Magnifications of the dimensions L 2  to L 5  with respect to the dimension L 1  can be changed as appropriate as long as the magnifications exceed 1. The dimensions of the main body sections  411  and  411 C, the projecting section  412 , the incident-side projecting sections  413 A,  413 B, and  413 D, and the emission-side projecting sections  414 A,  414 B, and  414 D in the +Z direction can also be changed as appropriate. 
     In the embodiment and the modifications, the projector  1  includes the three light modulation devices  34  ( 34 R,  34 G, and  34 B). However, the invention is not limited to this. The invention can also be applied to, for example, a projector including two or less or four or more light modulation devices. 
     The light modulation device  34  includes the liquid crystal panel, the light incident surface and the light emission surface of which are different. However, the invention is not limited to this. A light modulation device including a liquid crystal panel of a reflection type, a light incident surface and a light emission surface of which are the same may be adopted. A light modulation device other than liquid crystal such as a device including a micro mirror, for example, a device including a DMD (Digital Micromirror Device) may be adopted as long as the light modulation device is a light modulation device capable of modulating an incident light beam and forming an image corresponding to image information. 
     In the embodiment and the modifications, the wavelength conversion devices  4  and  4 A to  4 D are explained as the wavelength conversion device used in the projector  1 . However, the invention is not limited to this. 
     For example, the wavelength conversion devices  4  to  4 A to  4 D may be configured to be used in an independently usable lighting device rather than the lighting device  31  of the projector  1 . In this case, the lighting device only has to include the solid-state light source  311  and the wavelength conversion device  4 . For example, any one of the condensing optical device  312 , the collimate lens  313 , the first lens array  314 , the second lens array  315 , and the polarization conversion element  316  may be absent.