Lighting equipment and projectors

Abstract

The present invention provides a lighting device and projector that offer a high degree of design flexibility for the optical path and can generate light with suppressed illumination unevenness. [Solution] The lighting device of the present invention comprises a light source, an optical separation element that separates first light incident from the light source into transmitted light and reflected light, a wavelength conversion element that converts the transmitted light into second light, and a first reflecting element that reflects the reflected light toward the optical separation element. The optical separation element has a translucent substrate having a first surface and a second surface, a first optical layer provided on the first surface that transmits the first component of the first light and reflects the second component of the first light, and a second optical layer provided on the second surface that transmits the third component of the first component that has reached the second surface and reflects the fourth component of the first component. The first light is incident on the first surface from a direction along the main surface of the first surface and a direction intersecting the normal direction of the main surface, the first optical layer transmits the fifth component of the fourth component incident from the second optical layer, and the second and fifth components are incident on the first reflecting element as reflected light.

Description

Technical Field

[0001] The present invention relates to a lighting device and a projector.

Background Art

[0002] Patent Document 1 below discloses a lighting device that increases the number of light beams in the reflected light by multiple-reflecting the laser light emitted from a light source unit and causing it to enter a diffusion element, thereby suppressing unevenness in luminance in a projected image.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the mirror used in the above lighting device adopts a configuration that multiple-reflects the light of the light source and extracts it only as reflected light, there are problems that the design freedom in the optical path of the light emitted from the light source is limited, and the illuminance unevenness in the plane of the extracted reflected light becomes large.

Means for Solving the Problems

[0005] To solve the above problems, according to a first aspect of the present invention, a light source that emits first light in a first wavelength band, an optical separation element that separates the first light incident from the light source into transmitted light and reflected light, a wavelength conversion element that converts the transmitted light separated by the optical separation element into second light in a second wavelength band different from the first wavelength band, and a first reflective element that reflects the reflected light separated by the optical separation element toward the optical separation element, wherein the optical separation element comprises a translucent substrate having a first surface and a second surface that are parallel to each other and facing opposite directions, and a first surface that transmits a first component which is a part of the first light incident from the light source and reflects the second component which is another part of the first light An illumination device is provided, comprising: a first optical layer that emits light; and a second optical layer provided on the second surface, which transmits a third component, which is a part of the first component that has passed through the first surface and reached the second surface, and reflects a fourth component, which is another part of the first component, wherein the first light is incident on the first surface of the translucent substrate from a direction along the main surface of the first surface and a direction intersecting the normal direction of the main surface, the first optical layer transmits a fifth component, which is a part of the fourth component incident from the second optical layer, and the second component reflected by the first optical layer and the fifth component transmitted by the first optical layer are incident on the first reflecting element as reflected light.

[0006] A projector is provided that comprises an illumination device according to the first embodiment, a light modulator for modulating light incident from the illumination device, and a projection optical device for projecting the light modulated by the light modulator. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows the schematic configuration of the projector according to the first embodiment. [Figure 2] This figure shows the schematic configuration of the lighting device according to the first embodiment. [Figure 3] This is a cross-sectional view showing the main components of the optical separation element. [Figure 4] This is a plan view of blue illumination light as seen from a direction along the optical axis. [Figure 5]This figure illustrates the behavior of light when considering refraction through a translucent substrate. [Figure 6] This figure shows the schematic configuration of the lighting device according to the second embodiment. [Modes for carrying out the invention]

[0008] (First Embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The projector of the first embodiment is an example of a liquid crystal projector comprising an illumination device and three light modulation devices. The following explanation will be given using diagrams, but in order to make each component easier to see, the dimensions of each component may be shown on different scales in the following diagrams.

[0009] Figure 1 shows a schematic configuration of the projector according to this embodiment. As shown in Figure 1, the projector 11 of this embodiment is a projection-type image display device that displays a color image on a screen SCR. The projector 11 is equipped with three light modulators 4B, 4G, and 4R corresponding to red light LR, green light LG, and blue light LB. The projector 11 uses a semiconductor laser that can produce high-brightness and high-power light as the light source of the illumination device 12.

[0010] The projector 11 comprises an illumination device 12, a color separation optical system 13, a red light modulation device 4R, a green light modulation device 4G, a blue light modulation device 4B, a composite optical system 15, and a projection optical device 16.

[0011] The illumination device 12 emits illumination light WL having a uniform illuminance distribution toward the color separation optical system 13. The illumination device 12 uses a light source device which is one embodiment of the present invention.

[0012] The color separation optical system 13 separates the illumination light WL emitted from the illumination device 12 into red light LR, green light LG, and blue light LB. The color separation optical system 13 comprises a first dichroic mirror 7a, a second dichroic mirror 7b, a first reflective mirror 8a, a second reflective mirror 8b, a third reflective mirror 8c, a first relay lens 9a, and a second relay lens 9b.

[0013] The first dichroic mirror 7a has the function of separating the illumination light WL emitted from the illumination device 12 into red light LR, green light LG, and blue light LB. The first dichroic mirror 7a transmits the red light LR and reflects the green light LG and blue light LB. The second dichroic mirror 7b has the function of separating the light reflected by the first dichroic mirror 7a into green light LG and blue light LB. The second dichroic mirror 7b reflects the green light LG and transmits the blue light LB.

[0014] The first reflecting mirror 8a is located in the optical path of red light LR. The first reflecting mirror 8a reflects the red light LR that has passed through the first dichroic mirror 7a toward the red light optical modulator 4R. The second reflecting mirror 8b and the third reflecting mirror 8c are located in the optical path of blue light LB. The second reflecting mirror 8b and the third reflecting mirror 8c reflect the blue light LB that has passed through the second dichroic mirror 7b toward the blue light optical modulator 4B. The green light LG is reflected by the second dichroic mirror 7b and travels toward the green light optical modulator 4G.

[0015] The first relay lens 9a and the second relay lens 9b are positioned on the light-emitting side of the second dichroic mirror 7b in the optical path of the blue light LB. The first relay lens 9a and the second relay lens 9b compensate for the light loss of the blue light LB caused by the blue light LB's optical path length being longer than that of the red light LR and green light LG.

[0016] The red light light modulation device 4R modulates the red light LR according to image information and forms image light corresponding to the red light LR. The green light light modulation device 4G modulates the green light LG according to image information and forms image light corresponding to the green light LG. The blue light light modulation device 4B modulates the blue light LB according to image information and forms image light corresponding to the blue light LB.

[0017] For the red light light modulation device 4R, the green light light modulation device 4G, and the blue light light modulation device 4B, for example, a transmissive liquid crystal panel is used. Also, a pair of polarizing plates (not shown) are arranged on the incident side and the emission side of the liquid crystal panel. The pair of polarizing plates transmit linearly polarized light in a specific direction.

[0018] A field lens 10R is arranged on the incident side of the red light light modulation device 4R. A field lens 10G is arranged on the incident side of the green light light modulation device 4G. A field lens 10B is arranged on the incident side of the blue light light modulation device 4B. The field lens 10R collimates the red light LR incident on the red light light modulation device 4R. The field lens 10G collimates the green light LG incident on the green light light modulation device 4G. The field lens 10B collimates the blue light LB incident on the blue light light modulation device 4B.

[0019] The combining optical system 15 combines the image lights corresponding to the red light LR, the green light LG, and the blue light LB respectively, and emits the combined image light toward the projection optical device 16. For the combining optical system 15, for example, a cross dichroic prism is used.

[0020] The projection optical device 16 is composed of a projection lens group including a plurality of projection lenses. The projection optical device 16 enlarges and projects the image light combined by the combining optical system 15 toward the screen SCR. Thereby, an enlarged color image is displayed on the screen SCR.

[0021] Hereinafter, the lighting device 12 will be described. FIG. 2 is a diagram showing a schematic configuration of the lighting device 12 of the present embodiment. As shown in Figure 2, the lighting device 12 comprises a light source 20, a light separation element 30, a first pickup optical system 22, a diffuse reflection element 23, a second pickup optical system 24, a wavelength conversion element 25, an integrator optical system 28, a polarization conversion element 26, and a superimposed lens 29.

[0022] The configuration of the light source device will be described below using the XYZ Cartesian coordinate system. The central axis of the blue light BL emitted from the light source 20 is called the optical axis ax1. The axis along the optical axis ax1 is defined as the X axis, with the direction of emission of the blue light BL being the +X side and the opposite direction being the -Z side. The central axis of the blue light BL emitted from the diffuse reflector element 23 is called the optical axis ax2. The axis along the optical axis ax2 is defined as the Z axis, with the direction of emission of the blue light BL being the +Z side and the opposite direction being the -Z side. The axis perpendicular to the X and Z axes is defined as the Y axis, with one side along the Y axis being the +Y side and the opposite direction being the -Y side.

[0023] Of the above configuration requirements, the light source 20, the light separation element 30, the second pickup optical system 24, and the wavelength conversion element 25 are arranged side by side on the optical axis ax1. The diffuse reflector element 23, the first pickup optical system 22, the light separation element 30, the integrator optical system 28, the polarization conversion element 26, and the superimposed lens 29 are arranged side by side on the optical axis ax2. The optical axes ax1 and ax2 lie in the same plane and are orthogonal to each other.

[0024] The light source 20 of this embodiment includes a plurality of light-emitting units 120. The plurality of light-emitting units 120 include a first light-emitting unit row 123 in which a plurality of first light-emitting units 121 are arranged, and a second light-emitting unit row 124 in which a plurality of second light-emitting units 122 are arranged. In this embodiment, the first light-emitting unit row 123 consists of four first light-emitting units 121 arranged along the Y-axis. The second light-emitting unit row 124 consists of four second light-emitting units 122 arranged along the Y-axis. The second light-emitting unit row 124 is arranged parallel to the first light-emitting unit row 123 in the Z-axis direction.

[0025] The first light-emitting unit 121 is composed of a semiconductor laser (Laser Diode; LD) that emits blue light having a peak wavelength in the wavelength band of, for example, 380 nm to 495 nm. Therefore, the first light-emitting unit row 123 emits a first luminous beam LB1 that includes four blue light rays BB1 arranged in the Y-axis direction.

[0026] The second light-emitting unit 122, like the first light-emitting unit 121, is composed of a semiconductor laser that emits blue light having a peak wavelength in the wavelength band of, for example, 380 nm to 495 nm. Therefore, the second light-emitting unit row 124 emits a second light beam LB2 that includes four blue light rays BB2 aligned in the Y-axis direction.

[0027] Based on this configuration, the light source 20 emits blue light BL along the optical axis ax1, consisting of a first luminous flux LB1 and a second luminous flux LB2 containing multiple blue light rays BB1 and BB2. The blue light BL in this embodiment corresponds to an example of the "first light in the first wavelength band" of the present invention.

[0028] The blue light BL emitted from the light source 20 is incident on the light separation element 30. In this embodiment, the light separation element 30 is at a 45° angle with respect to the optical axes ax1 and ax2. The light separation element 30 transmits a portion of the blue light BL and reflects another portion of the blue light BL. The component of the blue light BL that has been transmitted through the light separation element 30 is incident on the wavelength conversion element 25, and the component of the blue light BL that has been reflected by the light separation element 30 is incident on the diffuse reflection element 23. In the following description, the component of the blue light BL that has been transmitted through the light separation element 30 and incident on the wavelength conversion element 25 is used to excite the phosphor layer and is therefore referred to as excitation light BL1. The component of the blue light BL that is incident on the diffuse reflection element 23 is used as part of the blue light of the illumination and is therefore referred to as blue illumination light BL2. In this embodiment, excitation light BL1 corresponds to an example of "transmitted light" in the present invention, and blue illumination light BL2 corresponds to "reflected light" in the present invention.

[0029] In this way, the light separation element 30 separates the blue light BL incident from the light source 20 into excitation light BL1 and blue illumination light BL2. The light separation element 30 also reflects yellow fluorescence YL, which has a different wavelength band than the blue light BL. Details of the configuration of the light separation element 30 will be described later.

[0030] The excitation light BL1 that has passed through the light separation element 30 is incident on the second pickup optical system 24. The second pickup optical system 24 focuses the excitation light BL1 toward the phosphor layer 250 of the wavelength conversion element 25. The second pickup optical system 24 is composed of one or more lenses.

[0031] The wavelength conversion element 25 includes a phosphor layer 250 and a substrate 251 that supports the phosphor layer 250. When excitation light BL1 is incident on the phosphor layer 250, the phosphors contained in the phosphor layer 250 are excited, and yellow fluorescent light YL having a wavelength band different from the wavelength band of the excitation light BL1 is generated. A heat sink may be provided on the side of the substrate 251 that is different from the side on which the phosphor layer 250 is provided, in order to dissipate heat from the phosphor layer 250. The fluorescent light YL in this embodiment corresponds to an example of the "second light in the second wavelength band" of the present invention.

[0032] The material of the phosphor layer 250 includes, for example, a yttrium aluminum garnet (YAG) phosphor. Taking YAG:Ce, which contains cerium (Ce) as an activator, as an example, the material used for the phosphor layer 250 may be a material obtained by mixing raw material powders containing constituent elements such as Y2O3, Al2O3, and CeO3 and performing a solid-phase reaction; Y-Al-O amorphous particles obtained by wet methods such as the coprecipitation method and the sol-gel method; or YAG particles obtained by gas-phase methods such as spray drying, flame decomposition, and thermal plasma methods.

[0033] The fluorescent yellow light (YL) emitted from the phosphor layer 250 is parallelized by the second pickup optical system 24 and incident on the light separation element 30. The fluorescent yellow light (YL) is reflected by the light separation element 30 and travels toward the integrator optical system 28. Because the fluorescent yellow light (YL) is scattered when emitted from the phosphor layer 250, it has a more uniform illuminance distribution compared to the excitation light BL1.

[0034] Meanwhile, the blue illumination light BL2 reflected by the light separation element 30 is incident on the first pickup optical system 22. As described later, by passing through the light separation element 30, the number of blue light rays constituting the blue illumination light BL2 doubles compared to before it was incident on the light separation element 30. This makes it possible to suppress uneven illumination of the blue illumination light BL2 separated from the blue light BL which is composed of laser light.

[0035] The first pickup optical system 22 focuses the blue illumination light BL2 toward the diffuse reflector element 23. The first pickup optical system 22 is composed of one or more lenses. The diffuse reflector element 23 in this embodiment corresponds to an example of the "first reflector element" of the present invention.

[0036] The diffuse reflecting element 23 diffusely reflects the blue illumination light BL2 emitted from the first pickup optical system 22 toward the light separation element 30. In particular, it is preferable to use a diffuse reflecting element 23 that performs Lambertian reflection of the blue illumination light BL2 incident on the diffuse reflecting element 23.

[0037] The diffuse reflector element 23 comprises a substrate, a metal reflective film, and a dielectric multilayer film. The substrate is made of, for example, a metal plate having a predetermined rigidity, and has an uneven surface structure consisting of a plurality of recesses and a plurality of protrusions on one surface. The metal reflective film is provided along the uneven surface structure of the substrate. The metal reflective film is made of, for example, a material containing aluminum. The dielectric multilayer film is provided on the side of the metal reflective film opposite to the translucent substrate. The dielectric multilayer film has a structure in which multiple layers of two types of dielectric films with different refractive indices are alternately stacked. The lighting device 12 of this embodiment uses this type of diffuse reflecting element 23 to obtain blue illumination light BL2 with a uniform illuminance distribution while diffusely reflecting the blue illumination light BL2.

[0038] The blue illumination light BL2, diffusely reflected by the diffuse reflecting element 23, is parallelized by the first pickup optical system 22 and incident on the light separation element 30. The blue illumination light BL2 passes through the light separation element 30 and travels towards the integrator optical system 28. A portion of the blue illumination light BL2 is reflected by the light separation element 30 and returns to the light source 20.

[0039] In this embodiment, the blue illumination light BL2 is diffusely reflected by the diffuse reflecting element 23, resulting in a more uniform illuminance distribution within the plane. Therefore, the blue illumination light BL2 has a uniform illuminance distribution, which suppresses uneven illumination. Furthermore, if the number of blue light rays constituting the blue illumination light BL2 is small, there is a risk that unevenness caused by the irregularities of the diffuse reflecting element 23 may be reflected on the screen SCR. In contrast, in this embodiment, as described later, the number of blue light rays constituting the blue illumination light BL2 is increased, so it is possible to suppress the degradation of image quality due to the reflection of unevenness.

[0040] In this way, the blue illumination light BL2 is used as illumination light WL together with the fluorescent YL reflected by the light separation element 30. That is, the blue illumination light BL2 and the fluorescent YL are emitted from the light separation element 30 in the same direction, towards the +Z side. The fluorescent YL has a uniform illuminance distribution. In this way, the blue illumination light BL2 and the yellow fluorescent YL, which have uniform illuminance distributions, are combined to obtain white illumination light WL with a uniform illuminance distribution. In other words, the light separation element 30 also functions as a color synthesis element that combines the blue illumination light BL2 and the fluorescent YL.

[0041] The illumination light WL emitted from the light separation element 30 is incident on the integrator optical system 28. The integrator optical system 28 divides the illumination light WL into multiple small beams of light. The integrator optical system 28 consists of a first lens array 28a and a second lens array 28b. Each of the first lens array 28a and the second lens array 28b has a configuration in which multiple microlenses are arranged in an array.

[0042] The illumination light WL emitted from the integrator optical system 28 is incident on the polarization conversion element 26. The polarization conversion element 26 aligns the polarization direction of the illumination light WL. The polarization conversion element 26 is composed of a polarization separation film, a phase difference plate, and a mirror. The polarization conversion element 26 aligns the polarization direction of the unpolarized fluorescent YL and the polarization direction of the linearly polarized blue illumination light BL2 in one direction. In this embodiment, the polarization conversion element 26 aligns the polarization direction of the illumination light WL with the polarization direction corresponding to the light transmission axis of the polarizer plate located on the light incidence side of each liquid crystal panel of the red light light modulator 4R, the green light light modulator 4G, and the blue light light modulator 4B.

[0043] The illumination light WL, whose polarization direction has been aligned by passing through the polarization conversion element 26, is incident on the superposition lens 29. The superposition lens 29 superimposes the multiple small beams of light emitted from the polarization conversion element 26 onto the object to be illuminated. This allows the object to be illuminated uniformly.

[0044] Next, the configuration of the light separation element 30 will be described. Figure 3 is a cross-sectional view showing the main components of the optical separation element 30. For the sake of simplicity, Figure 3 illustrates a state where the refraction of light during incidence onto or emission from the optical separation element 30 is not considered.

[0045] As shown in Figure 3, the light separation element 30 includes a first optical layer 31, a second optical layer 32, and a light-transmitting substrate 33. The light-transmitting substrate 33 is made of optical glass such as BK7. The light-transmitting substrate 33 has a first surface 33a and a second surface 33b that are parallel to each other and facing opposite directions.

[0046] The blue light BL is incident on the first surface 33a of the translucent substrate 33 from a direction along the main surface of the first surface 33a and from a direction intersecting the normal direction of the first surface 33a. In this embodiment, the light separation element 30 is positioned at an angle with respect to the optical axis ax1. Therefore, the blue light BL is incident on the first optical layer 31 and the second optical layer 32 of the light separation element 30 from an oblique direction, so as described later, the blue light BL passes through the first optical layer 31 and the second optical layer 32, causing the optical path to be separated into two.

[0047] The first optical layer 31 is provided on the first surface 33a of the light-transmitting substrate 33. The first optical layer 31 is composed of a dielectric multilayer film having optical properties that transmit a portion of the blue wavelength band of light and reflect the other portion. Therefore, the first optical layer 31 transmits the first component B1, which is a portion of the blue light BL incident from the light source 20, and reflects the second component B2, which is the other portion of the blue light BL. As a result, the second component B2 is emitted from the light separation element 30 toward the diffuse reflection element 23.

[0048] The first component B1, having passed through the first optical layer 31, passes through the transparent substrate 33 from the first surface 33a and reaches the second surface 33b. The second optical layer 32 is provided on the second surface 33b of the transparent substrate 33. The second optical layer 32 is composed of a dielectric multilayer film having optical properties that transmit a portion of the blue wavelength band blue light BL and reflect the other portion of the blue wavelength band blue light BL and the yellow wavelength fluorescence YL. Therefore, the second optical layer 32 transmits the third component B3, which is a portion of the first component B1 that has passed through the first surface 33a and reached the second surface 33b, and reflects the fourth component B4, which is the other portion of the first component B1. As a result, the third component B3 is emitted from the optical separation element 30 toward the wavelength conversion element 25.

[0049] The fourth component B4 reflected by the second optical layer 32 passes through the translucent substrate 33 from the first surface 33a and is incident on the first optical layer 31 provided on the first surface 33a. The first optical layer 31 transmits the fifth component B5, which is part of the fourth component B4 incident from the second optical layer 32. As a result, the fifth component B5 is emitted from the light separation element 30 toward the diffuse reflection element 23.

[0050] In this way, the light separation element 30 can cause the second component B2 and the fifth component B5 separated from the blue light BL to be incident on the diffuse reflector element 23 as the blue illumination light BL2. Furthermore, the light separation element 30 can cause the third component B3 and the sixth component B6 separated from the blue light BL to be incident on the wavelength conversion element 25 as the excitation light BL1.

[0051] As described above, the fluorescent YL generated by the wavelength conversion element 25 is parallelized by the second pickup optical system 24 and incident on the light separation element 30. Therefore, the fluorescent YL is incident on the second surface 33b from the wavelength conversion element 25 at an oblique angle, reflected by the second optical layer 32 provided on the second surface 33b, and emitted in a Z-axis direction different from the Z-axis direction when incident on the second optical layer 32.

[0052] As shown in Figure 3, a portion of the fourth component B4 incident on the first optical layer 31 is reflected and incident on the second optical layer 32, and a portion of it is transmitted through the second optical layer 32 and emitted as the sixth component B6 from the light separation element 30 toward the wavelength conversion element 25. A portion of the fourth component B4 reflected by the first optical layer 31 is reflected by the second optical layer 32 and incident on the first optical layer 31, and is transmitted through the first optical layer 31 and reflected from the light separation element 30 toward the diffuse reflection element 23. However, since this amount is very small compared to the second component B2 and the fifth component B5, it does not cause problems such as uneven illumination.

[0053] For example, the reflectances of the first optical layer 31 and the second optical layer 32 of the light separation element 30 are R1 and R2, respectively, and the amount of blue light BL incident on the light separation element 30 from the light source 20 is set to 1. In this case, the light intensity of the second component B2 is R1, and the light intensity of the fifth component B5 is R2 × (1 - R1). 2 The light intensity of the third component can be defined as (1-R1) × (1-R2).

[0054] Here, if the difference in light intensity between the second component B2 and the fifth component B5 becomes too large, the illumination unevenness of the blue illumination light BL2 will increase, degrading the quality of the projected image. In contrast, the light separation element 30 of this embodiment is configured so that the light intensity ratio between the second component B2 and the fifth component B5 is 50% to 200%. The most preferable case is when the light intensity ratio between the second component B2 and the fifth component B5 is 100%, that is, when the light intensity of the second component B2 and the fifth component B5 are equal. Note that R2 = R1 / (1-R1) 2 If the following relationship is satisfied, the light intensity of the second component B2 and the fifth component B5 will be equal.

[0055] In the optical separation element 30 of this embodiment, the reflectance R2 of blue light BL in the second optical layer 32 is higher than the reflectance R1 of blue light BL in the first optical layer 31. With this configuration, the proportion of blue light BL reaching the second optical layer 32 can be increased by increasing the transmittance of blue light BL in the first optical layer 31. This prevents the amount of light in the second component B2 from becoming unnecessarily higher than the amount of light in the fifth component B5. For example, if the reflectance R1 of the first optical layer 31 is 13.0% and the reflectance R2 of the second optical layer 32 is 17.2%, then the light intensities of the second component B2 and the fifth component B5 can be made equal to 13.0% each, relative to the light intensity of the blue light BL of 100.

[0056] Figure 4 is a plan view of the blue illumination light BL2 emitted from the light separation element 30, viewed from a direction along the optical axis ax2. For comparison, Figure 4 also shows a plan view of the blue light BL incident on the light separation element 30, viewed from a direction along the optical axis ax1.

[0057] As shown in Figure 4, the blue light BL of this embodiment includes four blue rays BB1 that constitute the first luminous beam LB1 and four blue rays BB2 that constitute the second luminous beam LB2. In other words, in this embodiment, the blue light BL is composed of eight blue rays.

[0058] On the other hand, the blue illumination light BL2 separated from the blue light BL by the light separation element 30 includes a luminous flux LB12 corresponding to the second component B2 of the first luminous flux LB1, a luminous flux LB15 corresponding to the fifth component B5 of the first luminous flux LB1, a luminous flux LB22 corresponding to the second component B2 of the second luminous flux LB2, and a luminous flux LB25 corresponding to the fifth component B5 of the second luminous flux LB2. Each of the luminous fluxes LB12, 15, 22, and 25 is composed of four blue rays. Therefore, the blue illumination light BL2 is composed of 16 blue rays.

[0059] In this embodiment, as shown in Figure 4, the luminous beams LB15 and LB25, which correspond to the fifth component B5 in the blue light BL (first luminous beam LB1, second luminous beam LB2) emitted from the first light-emitting section 123 and the second light-emitting section 124, are shifted to the +X side in the X-axis direction, where the luminous beams LB12 and LB22, which correspond to the second component B2 in the blue light BL (first luminous beam LB1, second luminous beam LB2) emitted from the first light-emitting section 123 and the second light-emitting section 124, are aligned. Furthermore, the luminous beams LB15 and LB25 are positioned so as not to overlap with the luminous beams LB12 and LB22, respectively.

[0060] The luminous beams LB12 and LB22, corresponding to the second component B2, and the luminous beams LB15 and LB25, corresponding to the fifth component B5, are aligned along the X-axis. The four blue rays that make up each luminous beam LB12, 15, 22, and 25 are aligned along the Y-axis. In other words, in this embodiment, the direction in which the second component B2 and the fifth component B5 are aligned is the Z-axis direction, and the direction in which the multiple blue light rays emitted from the multiple light-emitting units 120 are aligned is the Y-axis direction. Therefore, in this embodiment, the direction in which the second component B2 and the fifth component B5 are aligned intersects (orthogonal to) the direction in which the multiple blue light rays emitted from the multiple light-emitting units 120 are aligned.

[0061] In this embodiment, the light separation element 30 prevents the luminous fluxes LB12, 15, 22, and 25 of the blue illumination light BL2, which are separated from the blue light BL, from overlapping. This improves the uniformity of the illuminance distribution of the blue illumination light BL2. Therefore, unevenness in the illuminance of the blue illumination light BL2 can be efficiently suppressed.

[0062] As described above, the blue illumination light BL2 is diffusely reflected by the diffuse reflector 23, passes through the light separation element 30, and is incident on the integrator optical system 28. In other words, the second component B2 and the fifth component B5 reflected by the diffuse reflector 23 pass through the light separation element 30, are combined with the fluorescent YL reflected by the second optical layer 32, and are emitted in the same direction as illumination light WL.

[0063] In the explanation using Figure 3, the model was simplified without considering the refraction of light during incidence or emission to the light separation element 30. However, in order to arrange the second component B2 and the fifth component B5 so that they do not overlap, it is necessary to consider the refraction of light in the translucent substrate 33.

[0064] Figure 5 shows the behavior of light when refraction of the translucent substrate 33 is considered. Note that the first optical layer 31 and the second optical layer 32 are not shown in Figure 5. In Figure 5, the angle of incidence of blue light BL on the first surface 33a of the translucent substrate 33 is θ, the refractive index of the translucent substrate 33 is n, the thickness of the translucent substrate 33 is L, and the distance between the second component B2 and the fifth component B5 is D.

[0065] As shown in Figure 5, the interval D between the second component B2 and the fifth component B5 is defined by the formula described above. For example, if the interval between the first luminous beam LB1 and the second luminous beam LB2 shown in Figure 4 is 6.36 mm, then in order to prevent the luminous beams LB12, 15, 22, and 25 from overlapping as described above, the translucent substrate 33 should be designed so that the interval D between the second component B2 and the fifth component B5 is half of 6.36 mm, which is 3.18 mm. For example, in the above formula, if the incident angle θ is 45° as in the lighting device 12 of this embodiment, then if D is 3.18 mm and the refractive index n of the translucent substrate 33 is 1.52, then the thickness L of the translucent substrate 33 will be 4.28 mm. For example, if the translucent substrate 33 is tilted clockwise by θ1, that is, if the incident angle θ is reduced by θ1, the optical axis ax2 will be tilted clockwise by 2θ1.

[0066] According to the light separation element 30 of this embodiment, by appropriately setting parameters such as the incident angle θ, refractive index n, thickness L, and spacing D, it is possible to provide a light separation element that emits blue illumination light BL2 with suppressed illumination unevenness.

[0067] As described above, the lighting device 12 of this embodiment includes a light source 20 that emits blue light BL in the blue wavelength band, a light separation element 30 that separates the blue light BL incident from the light source 20, a wavelength conversion element 25 that converts the blue light BL into fluorescence YL in the yellow wavelength band which is different from the blue wavelength band, and a diffuse reflector element 23 that reflects the blue light BL incident from the light separation element 30 toward the light separation element 30. The light separation element 30 includes a translucent substrate 33 having a first surface 33a and a second surface 33b that are parallel to each other and facing opposite directions, a first optical layer 31 provided on the first surface 33a that transmits a first component B1, which is part of the blue light BL incident from the light source 20, and reflects a second component B2, which is another part of the blue light BL, and a second optical layer 32 provided on the second surface 33b that transmits a third component B3, which is part of the first component B1 that has passed through the first surface 33a and reached the second surface 33b, and reflects a fourth component B4, which is another part of the first component B1. The blue light BL is incident on the first surface 33a of the translucent substrate 33 from the X-axis direction that intersects the direction along the main surface of the first surface 33a and the direction normal to the main surface, and the first optical layer 31 transmits a fifth component B5, which is part of the fourth component B4 incident from the second optical layer 32. The second component B2 reflected by the first optical layer 31 and the fifth component B5 transmitted through the first optical layer 31 are incident on the diffuse reflector element 23.

[0068] According to the lighting device 12 of this embodiment, the blue light BL incident from the light source 20 can be separated in the light separation element 30 into the transmitted component, excitation light BL1, and the reflected component, blue illumination light BL2. Therefore, according to the lighting device 12 of this embodiment, since the blue light BL is transmitted or reflected to separate the optical path into two, a lighting device with a high degree of freedom in optical path design can be provided. Furthermore, the light separation element 30 separates the blue illumination light BL2 from the blue light BL by reflecting the second component B2 and the fifth component B5, thereby increasing the number of blue light rays that make up the blue illumination light BL2. As a result, uneven illumination of the blue illumination light BL2 separated from the blue light BL which is composed of laser light can be suppressed. Therefore, according to the lighting device 12 of this embodiment, it is possible to generate illumination light WL by combining blue illumination light BL2 with suppressed illuminance unevenness and fluorescent YL having a uniform illuminance distribution. Thus, the object to be illuminated can be illuminated with light with a uniform illuminance distribution.

[0069] The projector 1 of this embodiment comprises an illumination device 12, light modulators 4R, 4G, and 4B for each color that modulate the light incident from the illumination device 12, and a projection optical device 16 that projects the light modulated by the light modulators 4R, 4G, and 4B.

[0070] According to the projector 1 of this embodiment, by modulating the illumination light WL, which has little illumination unevenness incident from the lighting device 12, it is possible to project a bright, high-quality image with little color unevenness.

[0071] (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to the drawings. The difference between this embodiment and the first embodiment lies in the configuration of the lighting device; all other configurations are the same. Therefore, the following description will primarily focus on the configuration of the lighting device, and the descriptions of other configurations will be omitted or simplified. Furthermore, components and parts common to the above embodiment will be denoted by the same reference numerals.

[0072] Figure 6 shows a schematic configuration of the lighting device according to this embodiment. As shown in Figure 6, the illumination device 112 of this embodiment includes a light source 20, a light separation element 30, a first pickup optical system 22, a diffuse reflection element 23, a second pickup optical system 24, a wavelength conversion element 125, a third pickup optical system 21, an integrator optical system 28, a polarization conversion element 26, a superimposed lens 29, a mirror 27, and a composite optical system 40. The composite optical system 40 includes a composite prism 41, a first mirror 42, and a second mirror 43.

[0073] The lighting device 112 of this embodiment has optical axes ax3, ax4, and ax5 that are perpendicular to the optical axis ax1 and along the Z axis. Of the above configuration requirements, the light source 20, the light separation element 30, the second pickup optical system 24, the wavelength conversion element 25, the third pickup optical system 21, and the mirror 27 are arranged side by side on the optical axis ax1. The mirror 27 in this embodiment corresponds to an example of the "second reflective element" of the present invention. The diffuse reflecting element 23, the first pickup optical system 22, the light separation element 30, and the second mirror 43 of the composite optical system 40 are arranged in a line on the optical axis ax3. The composite prism 41 of the composite optical system 40, the integrator optical system 28, the polarization conversion element 26, and the superimposed lens 29 are arranged in a line on the optical axis ax5.

[0074] In this embodiment, the wavelength conversion element 125 emits fluorescent YL toward the mirror 27 opposite to the light separation element 30. That is, the wavelength conversion element 125 in this embodiment emits fluorescent YL in the direction opposite to the incident side of the excitation light BL1.

[0075] The fluorescent YL emitted from the wavelength conversion element 125 is incident on the third pickup optical system 21. The third pickup optical system 21 parallelizes the fluorescent YL and directs it onto the mirror 27. The third pickup optical system 21 is composed of one or more lenses. Mirror 27 reflects the fluorescent YL in the Z-axis direction of the blue illumination light BL2, which contains the second component B2 and the fifth component B5, and which has been reflected by the diffuse reflecting element 23 and transmitted through the light separation element 30.

[0076] The fluorescent YL reflected by mirror 27 is reflected by the first mirror 42 of the composite optical system 40 and incident on the composite prism 41. The blue illumination light BL2 is reflected by the second mirror 43 of the composite optical system 40 and incident on the composite prism 41. The composite prism 41 emits illumination light WL, which is a combination of the fluorescent YL and the blue illumination light BL2, toward the integrator optical system 28.

[0077] In the lighting device 112 of this embodiment, the light path is separated into two by transmitting or reflecting the blue light BL, and then the fluorescent YL and the blue illumination light BL2 are combined again to generate illumination light WL, thus providing a lighting device with a high degree of freedom in designing the light path. Also, similar to the lighting device 12 of the first embodiment, when separating the blue illumination light BL2, the number of blue light rays constituting the blue illumination light BL2 can be increased, so that illuminance unevenness of the blue illumination light BL2 can be suppressed. Therefore, in the lighting device 112 of this embodiment as well, illumination light WL can be generated by combining blue illumination light BL2 with suppressed illuminance unevenness and fluorescent YL having a uniform illuminance distribution. Thus, the object to be illuminated can be illuminated with light with a uniform illuminance distribution.

[0078] In this embodiment, the illumination device 112 is shown as an example where the fluorescent YL and blue illumination light BL2 are combined by the combining optical system 40 and then incident on the integrator optical system 28. However, the fluorescent YL and blue illumination light BL2 may be emitted in the Z-axis direction without using the combining optical system 40. In this case, the fluorescent YL is incident directly on the first dichroic mirror 7a of the color separation optical system 13 shown in Figure 1, and the blue illumination light BL2 is incident directly on the third reflective mirror 8c of the color separation optical system 13.

[0079] The technical scope of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, in the above embodiment, a diffuse reflector 23 is used as the first reflector that reflects the blue illumination light BL2 toward the light separation element 30, but a mirror that simply reflects light without diffusing it may also be used. Furthermore, although the above embodiment uses laser elements as the multiple light-emitting parts 120 of the light source 20 that emits blue light BL as an example, light-emitting diodes may also be used.

[0080] Furthermore, the specific details regarding the shape, number, arrangement, materials, and other components of the lighting device and projector are not limited to the above-described embodiment and can be modified as appropriate.

[0081] A summary of this disclosure is provided below.

[0082] (Note 1) A light source that emits first light in the first wavelength band, A light separation element that separates the first light incident from the light source into transmitted light and reflected light, A wavelength conversion element that converts the transmitted light separated by the light separation element into a second light in a second wavelength band different from the first wavelength band, A first reflecting element that reflects the reflected light separated by the light separation element toward the light separation element, Equipped with, The aforementioned optical separation element is A translucent substrate having a first surface and a second surface that are parallel to each other and facing in opposite directions, A first optical layer provided on the first surface transmits a first component, which is a part of the first light incident from the light source, and reflects a second component, which is another part of the first light; The second surface is provided with a second optical layer that transmits a third component, which is a part of the first component that has passed through the first surface and reached the second surface, and reflects a fourth component, which is another part of the first component. The first light is incident on the first surface of the translucent substrate from a direction along the main surface of the first surface and a direction intersecting the normal direction of the main surface. The first optical layer transmits the fifth component, which is a part of the fourth component, that is incident from the second optical layer. The second component reflected by the first optical layer and the fifth component transmitted through the first optical layer are incident on the first reflecting element as reflected light. Lighting device.

[0083] With this lighting device configuration, the first light incident from the light source is transmitted and reflected by the light separation element, thereby separating the optical path into two. This provides a lighting device with a high degree of design flexibility for the optical path of the first light. Furthermore, the light separation element reflects the second and fifth components from the first light source, separating the reflected light and thus increasing the number of light rays that make up the reflected light. This suppresses uneven illumination of the reflected light separated from the first light source. Therefore, with this lighting device configuration, the object to be illuminated can be illuminated with light that has a uniform illumination distribution.

[0084] (Note 2) The second optical layer has optical properties that reflect the second light, The second light is incident on the second surface from the wavelength conversion element at an oblique angle, reflected by the second optical layer provided on the second surface, and emitted in a direction different from when it was incident on the second optical layer. The lighting device described in Appendix 1.

[0085] With this configuration, the optical path of the second light can be deflected in the second optical layer and extracted in a desired direction.

[0086] (Note 3) The reflected light from the first reflecting element passes through the light separation element and is combined with the second light reflected from the second optical layer to emit illumination light in the same direction. The lighting device described in Appendix 2.

[0087] With this configuration, reflected light containing the second and fifth components and illumination light containing the second light can be combined by an optical separation element and extracted in one direction.

[0088] (Note 4) The first reflective element is a diffuse reflector that reflects incident light while diffusing it. The lighting device described in Appendix 3.

[0089] With this configuration, the uniformity of the illuminance distribution in the reflected light can be further improved by diffusely reflecting the second and fifth components.

[0090] (Note 5) The reflectance of the first light in the second optical layer is higher than the reflectance of the first light in the first optical layer. A lighting device described in any one of the appendices 1 through 4.

[0091] This configuration allows for an increase in the proportion of the first light reaching the second optical layer by increasing the transmittance of the first light in the first optical layer. This prevents the amount of light in the second component from becoming excessively high compared to the amount of light in the fifth component.

[0092] (Note 6) The relative light intensity ratio of the second and fifth components contained in the reflected light is 50% to 200%. A lighting device described in any one of the appendices 1 through 5.

[0093] This configuration suppresses the excessive difference in light intensity between the second and fifth components of the reflected light, thereby preventing problems such as reduced projected image quality due to uneven illumination of the reflected light.

[0094] (Note 7) The light source has a plurality of light-emitting parts that emit the first light, In the reflected light, the direction in which the second and fifth components are aligned intersects with the direction in which the multiple light rays emitted from the multiple light-emitting units are aligned. A lighting device described in any one of the appendices 1 through 6.

[0095] With this configuration, the multiple light rays that make up the reflected light are arranged in a balanced manner, which helps to suppress unevenness in the illumination of the reflected light in a balanced way.

[0096] (Note 8) The plurality of light-emitting units include a first light-emitting unit row in which a plurality of first light-emitting units are arranged, and a second light-emitting unit row arranged parallel to the first light-emitting unit row in which a plurality of second light-emitting units are arranged. In the reflected light, each of the fifth components in the first light emitted from the first and second light-emitting units is shifted in the direction in which each of the second components in the first light emitted from the first and second light-emitting units are aligned, and is positioned so as not to overlap with each of the second components. The lighting device described in Appendix 7.

[0097] With this configuration, the individual rays constituting the reflected light separated from the first light source are arranged without overlapping, thereby improving the uniformity of the illuminance distribution of the reflected light. Therefore, unevenness in the illuminance of the reflected light can be efficiently suppressed.

[0098] (Note 9) The wavelength conversion element emits the second light toward the second reflecting element opposite to the light separation element. The second reflecting element reflects the second light in the direction in which the reflected light, which includes the second and fifth components, is propagated after being reflected by the first reflecting element and transmitted through the light separation element. A lighting device described in any one of the appendices 1 through 8.

[0099] This configuration provides a setup in which the second light and the reflected light are emitted in the same direction, in a configuration where the second light is emitted on the opposite side of the light separation element.

[0100] (Note 10) A lighting device described in any one of the appendices 1 to 9, A light modulator that modulates the light incident from the aforementioned lighting device, A projection optical device that projects light modulated by the aforementioned optical modulation device, Equipped with, projector

[0101] With this projector configuration, by modulating the illumination light with minimal illuminance unevenness incident from the lighting device, it is possible to project a bright, high-quality image with minimal color unevenness. [Explanation of Symbols]

[0102] 1,11...Projector, 4B,4R...Optical modulator, 12,112...Illumination device, 16...Projection optical device, 20...Light source, 23...Diffuse reflector element, 25,125...Wavelength conversion element, 30...Optical separation element, 31...First optical layer, 32...Second optical layer, 33...Transparent substrate, 33a...First surface, 33b...Second surface, 100...Light intensity, 120...Light-emitting part, 121...First light-emitting part, 122...Second light-emitting part, 123...First light-emitting part row, 124...Second light-emitting part row, 251...Substrate, B1...First component, B2...Second component, B3...Third component, B4...Fourth component, B5,R5...Fifth component, R1,R2...Reflectance, WL...Illumination light, BL1...Excitation light (transmitted light), BL2...Blue illumination light (reflected light).

Claims

1. A light source that emits first light in the first wavelength band, A light separation element that separates the first light incident from the light source into transmitted light and reflected light, A wavelength conversion element that converts the transmitted light separated by the light separation element into a second light in a second wavelength band different from the first wavelength band, A first reflecting element that reflects the reflected light separated by the light separation element toward the light separation element, Equipped with, The aforementioned optical separation element is A translucent substrate having a first surface and a second surface that are parallel to each other and facing in opposite directions, A first optical layer is provided on the first surface, which transmits a first component, which is a part of the first light incident from the light source, and reflects a second component, which is another part of the first light. The second surface is provided with a second optical layer that transmits a third component, which is a part of the first component that has passed through the first surface and reached the second surface, and reflects a fourth component, which is another part of the first component. The first light is incident on the first surface of the translucent substrate from a direction along the main surface of the first surface and a direction intersecting the normal direction of the main surface. The first optical layer transmits the fifth component, which is a part of the fourth component, that is incident from the second optical layer. The second component reflected by the first optical layer and the fifth component transmitted through the first optical layer are incident on the first reflecting element as reflected light. Lighting device.

2. The second optical layer has optical properties that reflect the second light, The second light is incident on the second surface from the wavelength conversion element at an oblique angle, reflected by the second optical layer provided on the second surface, and emitted in a direction different from when it was incident on the second optical layer. The lighting device according to claim 1.

3. The reflected light reflected by the first reflecting element passes through the light separation element and is combined with the second light reflected by the second optical layer to be emitted in the same direction as illumination light. The lighting device according to claim 2.

4. The first reflective element is a diffuse reflector that reflects incident light while diffusing it. The lighting device according to claim 3.

5. The reflectance of the first light in the second optical layer is higher than the reflectance of the first light in the first optical layer. The lighting device according to claim 1.

6. The ratio of the light intensity of the second and fifth components contained in the reflected light is between 50% and 200%. The lighting device according to claim 1.

7. The light source has a plurality of light-emitting parts that emit the first light, In the reflected light, the direction in which the second and fifth components are aligned intersects with the direction in which the multiple light rays emitted from the multiple light-emitting units are aligned. The lighting device according to claim 1.

8. The plurality of light-emitting units include a first light-emitting unit row in which a plurality of first light-emitting units are arranged, and a second light-emitting unit row arranged parallel to the first light-emitting unit row in which a plurality of second light-emitting units are arranged. In the reflected light, each of the fifth components in the first light emitted from the first and second light-emitting units is shifted in the direction in which each of the second components in the first light emitted from the first and second light-emitting units are aligned, and is positioned so as not to overlap with each of the second components. The lighting device according to claim 7.

9. The wavelength conversion element emits the second light toward the second reflecting element opposite to the light separation element. The second reflecting element reflects the second light in the direction in which the reflected light, which includes the second and fifth components, is propagated after being reflected by the first reflecting element and transmitted through the light separation element. The lighting device according to claim 1.

10. A lighting device according to any one of claims 1 to 9, A light modulator that modulates the light incident from the aforementioned lighting device, A projection optical device that projects light modulated by the aforementioned optical modulation device, Equipped with, projector.

Images