Light source device and projection type image display device

Abstract

According to the present invention, a light source device comprises a light source element that outputs first light that is light of a first wavelength band, a first selective reflection element that is arranged at a position that is struck by the first light, transmits a first linearly polarized light component that is defined by the incidence direction and reflection direction of incident light, and reflects a second linearly polarized light component that has a plane of vibration that is orthogonal to the plane of vibration of the first linearly polarized light component, a second selective reflection element that is arranged at a position that receives light that has been transmitted or reflected by the first selective reflection element and transmits or reflects incident light in accordance with the wavelength band of the incident light, and a first polarization direction conversion element that is arranged between the first selective reflection element and the second selective reflection element and converts first linearly polarized light that has been transmitted or reflected by the first selective reflection element to circularly polarized light. The first polarization direction conversion element also converts circularly polarized light that is reflected by the second selective reflection element and reenters the first polarization direction conversion element to second linearly polarized light.

Description

[Technical field]

[0001] The present invention relates to a light source device and a projection-type image display device including the same. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there are light source devices that irradiate light from a light source onto a phosphor wheel to generate light with converted wavelengths, and emit the light from the light source and the light generated by the phosphor wheel, and projection-type image display devices equipped with the same.

[0003] The light source device, for example, irradiates a phosphor wheel with blue light emitted from a light source unit to generate yellow light, and generates white light by combining the generated yellow light with the blue light emitted from the light source unit. The projection type image display device further separates this white light into three primary color lights, modulates each color light, and recombines the modulated color lights to generate image light.

[0004] For example, in Patent Document 1, blue light emitted from a light source passes through a wavelength-selective polarization separation element, and the transmitted P-polarized blue light passes through a quarter-wave plate and is converted to circularly polarized light. The circularly polarized blue light is reflected by a color wheel and passes through the quarter-wave plate again and is converted to S-polarized light. The S-polarized blue light is reflected by the wavelength-selective polarization separation element and travels to a phosphor wheel. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-031823 A Summary of the Invention

[0006] However, in the technology described in Patent Document 1, there is a demand for further improving the efficiency of using the light emitted from the light source.

[0007] An object of the present disclosure is to provide a light source device and a projection-type image display device that improve the efficiency of light utilization.

[0008] A light source device according to the present disclosure includes a light source element that outputs a first light, which is light in a first wavelength range, and a first linearly polarized light beam that is disposed at a position where the first light is incident and is defined by the incident direction and reflection direction of the incident light. of a second linearly polarized light having a vibration plane perpendicular to the vibration plane of the first linearly polarized light component; Ingredients a first selective reflection element that reflects incident light; a second selective reflection element that is disposed at a position to receive light that has been transmitted through or reflected by the first selective reflection element and that transmits or reflects incident light in accordance with a wavelength range of the incident light; and a second selective reflection element that is disposed between the first selective reflection element and the second selective reflection element and that transmits or reflects incident light in accordance with a wavelength range of the incident light. or reflection and a first polarization direction conversion element that converts the first linearly polarized light into elliptically polarized light. The first polarization direction conversion element converts the elliptically polarized light that is reflected by the second selective reflection element and enters the first polarization direction conversion element again, into a second linearly polarized light.

[0009] In addition, the light source device according to the present disclosure includes a light source element that outputs a first light, which is light in a first wavelength range; a first selective reflection element that is arranged at a position where the first light is incident and transmits or reflects a first linearly polarized light defined by the incident direction and reflection direction of the incident light, and reflects or transmits a second linearly polarized light; a second selective reflection element that is arranged at a position to receive the light that has been transmitted or reflected by the first selective reflection element and transmits or reflects the incident light in accordance with the wavelength range of the incident light; a wavelength conversion element that is arranged at a position where the light that has been reflected or transmitted by the first selective reflection element is incident and converts the light that has been reflected or transmitted by the first selective reflection element into a second light, which is light in a second wavelength range; a reflection element that reflects the light that has been reflected by the wavelength conversion element and transmitted or reflected by the first selective reflection element; and a second polarization direction conversion element that is arranged between the first selective reflection element and the reflection element.

[0010] A projection-type image display device according to the present disclosure includes a light modulation section that generates image light using light emitted from a light source device, and a projection optical system that projects the image light.

[0011] The present disclosure can provide a light source device and a projection-type image display device that improve the efficiency of light utilization. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing a configuration example of a light source device according to a first embodiment. [Diagram 2] FIG. 1 is a plan view of a wavelength conversion element according to a first embodiment; [Diagram 3] FIG. 1 is a plan view showing an example of a color wheel according to a first embodiment; [Figure 4A] FIG. 1 is an explanatory diagram illustrating P-polarized light with respect to a first selective reflection element. [Figure 4B] FIG. 1 is an explanatory diagram illustrating S-polarized light with respect to a first selective reflection element. [Figure 4C] FIG. 1 is an explanatory diagram illustrating the optical path of light that is obliquely incident on and re-incident on a first selective reflection element. [Figure 5A] FIG. 1 is an explanatory diagram illustrating a light path from when light is incident on a first selective reflection element to when light is re-incident thereon in a comparative example. [Figure 5B] FIG. 1 is an explanatory diagram illustrating a light path from when the light is incident on a first selective reflection element until when the light is incident again on the first selective reflection element in the first embodiment. [Figure 6] FIG. 1 is an explanatory diagram showing an example of a linearly polarized state; [Figure 7] FIG. 1 is a schematic diagram showing a configuration example of a light source device according to a modification of the first embodiment. [Figure 8] FIG. 13 is a schematic diagram showing a configuration example of a light source device according to a second embodiment. [Figure 9] FIG. 13 is a schematic diagram showing a configuration example of a light source device according to a third embodiment. [Figure 10] FIG. 13 is a schematic diagram showing a configuration example of a light source device according to a fourth embodiment. [Figure 11] FIG. 13 is a diagram showing a configuration of a projection type image display device according to a fifth embodiment. [Figure 12] FIG. 13 is a diagram showing a configuration of a projection type image display device according to a sixth embodiment. [Figure 13] FIG. 13 shows a configuration of a projection type image display device according to a seventh embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

[0014] It should be noted that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0015] (Embodiment 1) [1-1. Configuration of light source device] Hereinafter, a light source device in the first embodiment will be described with reference to Fig. 1 to Fig. 3. In the first embodiment, for example, a light source device used in a projection type image display device will be described. Fig. 1 is a schematic diagram showing a configuration example of the light source device. Fig. 2 is a plan view of a wavelength conversion element. Fig. 3 is a plan view of a color wheel. In each figure, the direction in which light is emitted from the light source device 1 is the Z direction, the plane in which the first polarization direction conversion element 15 receives light is the XY plane formed by the X direction and the Y direction perpendicular to the X direction, and the XY plane and the Z direction are perpendicular to each other.

[0016] The light source device 1 includes a light source unit 3, a first selective reflection element 13, a first polarization direction conversion element 15, a color wheel 20, and a wavelength conversion element 25. The color wheel 20 is an example of a second selective reflection element. The light source device 1 further includes a convex lens 5, a diffuser plate 7, and a concave lens 11 on the optical path between the light source unit 3 and the first selective reflection element 13, and includes condenser lenses 21 and 23 on the optical path between the first selective reflection element 13 and the wavelength conversion element 25. The light source device 1 further includes a condenser element 19 between the first polarization direction conversion element 15 and the color wheel 20, and a rod integrator 33 at the rear of the color wheel 20.

[0017] The light source unit 3 includes a light source element 3a that emits a first light Lc1 that is a light in a first wavelength range, and a collimator lens 3b that converts the first light Lc1 emitted from the light source element 3a into a parallel beam. The collimator lens 3b is disposed corresponding to the light source element 3a, and the light source unit 3 includes a plurality of pairs of the light source element 3a and the collimator lens 3b. The light source element 3a outputs light in a blue wavelength range as the light in the first wavelength range, for example. In addition, in the first embodiment, as an example, a configuration will be described in which the light source element 3a is a laser light source element and outputs blue light that is mainly composed of linearly polarized light having a vibration direction in the Y-axis direction.

[0018] The first light Lc1, which has been made into a parallel beam, enters the subsequent convex lens 5, which reduces the beam width, and then enters the subsequent diffuser plate 7 where it is diffused and the uniformity of the light is improved. The first light Lc1, whose uniformity has been improved, enters the subsequent concave lens 11 and is made into a parallel beam again.

[0019] The first light Lc1 collimated by the concave lens 11 is incident on the first selective reflection element 13 arranged at an angle of approximately 45 degrees around the X-axis with respect to the optical axis. The first selective reflection element 13 is, for example, a dichroic polarization separation mirror. In the first selective reflection element 13, the first light Lc1 in the first wavelength range emitted from the light source element 3a is transmitted, and the second light Lc2, for example, yellow light, which has been wavelength-converted by the wavelength conversion element 25 using light in the same wavelength range as the wavelength range of the first light Lc1 from the light source element 3a as excitation light, is reflected. Therefore, the first light Lc1 incident on the first selective reflection element 13 passes through the first selective reflection element 13, travels straight without changing its traveling direction, and enters the first polarization direction conversion element 15. In this way, the first selective reflection element 13 has the spectral characteristics of transmitting the first light Lc1, which is P-polarized blue light with respect to a plane determined by the incident light and the reflected light, and reflecting the S-polarized blue light and the second light Lc2, which will be described later, with respect to a plane determined by the incident light and the reflected light. The second light Lc2, which is light in the second wavelength range, is light obtained by wavelength conversion of light Lc1r in the same wavelength range as the first light Lc1 by the wavelength conversion element 25.

[0020] The first polarization direction conversion element 15 converts the linearly polarized light incident thereon into elliptically polarized light, and converts the elliptically polarized light incident thereon into linearly polarized light. The first polarization direction conversion element 15 is, for example, a retardation plate such as two quarter-wave plates, and includes a first quarter-wave plate 15a and a second quarter-wave plate 15b in this embodiment. The first quarter-wave plate 15a and the second quarter-wave plate 15b have different slow axes. In one example, the first quarter-wave plate 15a has a slow axis at 45 degrees relative to a reference axis, and the second quarter-wave plate 15b has a slow axis at 90 degrees relative to the reference axis. Here, the reference axis is, for example, the Y axis in the XY plane shown in FIG. 1. The direction of the slow axis of the first quarter-wave plate 15a can be adjusted with respect to the direction of the slow axis of the second quarter-wave plate 15b.

[0021] The first light Lc1 incident on the first polarization direction conversion element 15 is converted from the incident linearly polarized blue light to elliptically polarized blue light. The first light Lc1 whose polarization direction has been converted travels straight, passes through the light collecting element 19, and enters the color wheel 20.

[0022] The color wheel 20 includes a plurality of dichroic layers 20a formed on a transparent substrate and a motor 20c for rotating the transparent substrate. The dichroic layer 20a has four angle regions θR, θG, θB, and θYe in the circumferential direction. The dichroic layer 20a includes a dichroic layer 20R formed in the angle region θR that transmits red light, a dichroic layer 20G formed in the angle region θG that transmits green light, a dichroic layer 20B formed in the angle region θB that transmits blue light, and a dichroic layer 20Ye formed in the angle region θYe that transmits yellow light.

[0023] When yellow light is incident on the angular region θR of color wheel 20, only the red component of the yellow light is transmitted through dichroic layer 20R, and the light of the other color components is reflected, and the light is emitted from color wheel 20 as red light R. When yellow light is incident on the angular region θG of color wheel 20, only the green component of the yellow light is transmitted through dichroic layer 20G, and the light of the other color components is reflected, and the light is emitted from color wheel 20 as green light G. In other words, color wheel 20 can transmit or reflect light incident on color wheel 20 depending on the wavelength range of the incident light.

[0024] When yellow light is incident on the angle region θYe of the color wheel 20, the yellow light passes through the dichroic layer 20Ye and is emitted from the color wheel 20 as yellow light. When blue light is incident on the angle region θB of the color wheel 20, the yellow light passes through the dichroic layer 20B and is emitted from the color wheel 20. When yellow light is incident on the angle region θB of the color wheel 20, the yellow light is reflected. With the above configuration, the light source device 1 emits red light R, green light G, yellow light Ye, and blue light B in a time-division manner. Here, the configuration is exemplified using four types of dichroic films 20a with different characteristics, but it is not necessary to be limited to this configuration, and the light source device 1 may be configured with three types of dichroic films 20a with different characteristics. The dichroic layer 20Ye may have a characteristic of reflecting unnecessary wavelength ranges in the yellow spectrum.

[0025] The light Lc1r reflected by the color wheel 20 is reflected by the first selective reflecting element 13 toward the wavelength conversion element 25, passes through the condenser lens 21 and the subsequent condenser lens 23, and is condensed onto a ring-shaped wavelength conversion layer 29 provided on the wavelength conversion element 25. The wavelength conversion element 25 is, for example, a phosphor wheel.

[0026] The wavelength conversion element 25 includes a substrate 27, a wavelength conversion layer 29 formed on the substrate 27, and a motor 31 attached to the substrate 27. The wavelength conversion element 25 is disposed so that light collected by the collecting lenses 21 and 23 is incident on the annular wavelength conversion layer 29. The wavelength conversion element 25 is rotationally driven by the motor 31. The incident surface of the wavelength conversion layer 29 is disposed parallel to the XZ plane.

[0027] The wavelength conversion layer 29 generates second light Lc2, which is light in a second wavelength range different from the wavelength of the incident blue light. The wavelength conversion layer 29 is a phosphor layer formed using a resin such as silicone or alumina or an inorganic substance as a binder and containing a plurality of phosphor particles therein.

[0028] The phosphor particles of the wavelength conversion layer 29 emit second light Lc2 having a wavelength range longer than that of the irradiated blue light. The phosphor of the wavelength conversion layer 29 is, for example, a Ce-activated YAG yellow phosphor that is excited by the irradiated blue light and emits yellow light containing wavelength components of green light and red light. A typical chemical structure of the crystal matrix of this phosphor particle is Y3Al5O 12 It is.

[0029] A reflective layer that reflects the incident light Lc1r and the second light Lc2 generated in the wavelength conversion layer 29 may be disposed between the substrate 27 and the wavelength conversion layer 29. This allows the second light Lc2 traveling toward the substrate 27 in the wavelength conversion layer 29 to travel toward the first selective reflection element 13, thereby improving the fluorescence conversion efficiency.

[0030] In this way, the light Lc1r, which is blue light collected on the wavelength conversion layer 29 of the wavelength conversion element 25 by the collecting lenses 21 and 23, is wavelength-converted to fluorescent light, changes its traveling direction by 180 degrees, and enters the collecting lenses 21 and 23 again in this order, where it is converted into parallel light. Note that the second light Lc2, which is fluorescent light, is, for example, in the yellow wavelength range, and forms white light in combination with the blue light emitted from the light source element 3a.

[0031] The second light Lc2 that is emitted from the condenser lens 21 and converted to parallel light is incident on the first selective reflection element 13. As described above, the first selective reflection element 13 has the property of reflecting light in the wavelength region of the second light Lc2, and changes the traveling direction of the light by 90 degrees. The second light Lc2, whose traveling direction has been changed by 90 degrees by the first selective reflection element 13, passes through the first polarization direction conversion element 15 in the subsequent stage and is incident on the condensing element 19.

[0032] The light collecting element 19 is, for example, a collecting lens, and is disposed at a position to receive the light emitted in the third direction. A rod integrator 33 is disposed after the light collecting element 19, and the light collecting element 19 collects the incident light onto the rod integrator 33.

[0033] The light transmitted through the first polarization direction conversion element 15 and the second light Lc2 from the wavelength conversion element 25 are incident on the condensing element 19 and condensed, and each of the lights transmitted through the color wheel 20 is incident on a rod integrator 33 whose entrance end is disposed approximately at the condensing position of the condensing element 19. The light whose luminous flux has been homogenized by the rod integrator 33 is emitted from the exit end of the rod integrator 33.

[0034] [1-2. Configuration of the first selective reflection element and the first polarization direction conversion element] The configurations of the first selective reflection element and the first polarization direction conversion element will be described with reference to Fig. 4A to Fig. 6. Fig. 4C is an explanatory diagram illustrating the optical path of light that is obliquely incident on and re-incident on the first selective reflection element 13. Fig. 5A is an explanatory diagram illustrating the optical path from when the light is incident on the first selective reflection element 13 until when the light is re-incident in a comparative example. Fig. 5B is an explanatory diagram illustrating the optical path from when the light is incident on the first selective reflection element 13 until when the light is re-incident in the first embodiment. Fig. 6 is an explanatory diagram illustrating an example of the state of linear polarization.

[0035] Here, the P polarized light and the S polarized light with respect to the first selective reflection element 13 will be described. As shown in FIG. 4A, the P polarized light Lp is a component of the first light Lc1 incident on the first selective reflection element 13, whose vibration plane is parallel to the plane P1 determined by the incident light Lc1a to the first selective reflection element 13 and the reflected light Lc1b from the first selective reflection element 13. The first selective reflection element 13 is disposed so that its polarization axis is parallel to the vibration plane of the P polarized light Lp component of the first light Lc1 traveling along the optical axis, so that most of the P polarized light Lp component of the first light Lc1 incident on the first selective reflection element 13 is transmitted through the first selective reflection element 13. The vibration plane of the first light Lc1 transmitted through the first selective reflection element 13, that is, the P polarized light Lp, is parallel to the plane P1.

[0036] 4B, the S-polarized light is a component of the first light Lc1 whose electric field vibration plane is perpendicular to a plane P1 determined by the incident light Lc1c to the first selective reflection element 13 and the reflected light Lc1d from the first selective reflection element 13. Most of the S-polarized light component Ls of the first light Lc1 is reflected by the first selective reflection element 13.

[0037] The light source element 3a is disposed so that the vibration plane of the light passing through the optical axis of the first light Lc1 emitted from the light source unit 3 passes through the polarization axis (transmission axis) of the first selective reflection element 13, but the first light Lc1 emitted from the light source unit 3 has a certain degree of range in the angle of the vibration plane. Therefore, the P-polarized light Lp component that passes through the first selective reflection element 13 may not necessarily have the same vibration plane as the polarization axis of the first selective reflection element 13, depending on the incident direction of the first light Lc1. In this way, the vibration plane of the P-polarized light component Lp1 of the first light Lc1 that passes through the first selective reflection element 13 varies depending on the direction of the incident light.

[0038] As shown in Figure 4C, for example, when the first light Lc1, which is blue light linearly polarized in the Y-axis direction, is incident on the first selective reflecting element 13 from the light source unit 3 for the first time, the light flux of the first light Lc1 that enters the first selective reflecting element 13 at an angle to the optical axis contains a component of S-polarized light Ls that is perpendicular to the incident / exit plane determined by the incident light and the reflected light, and therefore a portion of the light amount is reflected by the first selective reflecting element 13.

[0039] 4C, the first polarization direction conversion element 15, the light collecting element 19, and the color wheel 20 are omitted, but when the light passes through the first selective reflection element 13, is reflected by the color wheel 20, and is incident on the first selective reflection element 13 again for the second time, the direction of the reflected light is different from that of the first incident. Therefore, since the incident and exit faces determined by the incident light and the reflected light are different, the light that passes through the first selective reflection element 13 is not completely converted to S-polarized light at the second incident by only one quarter-wave plate, and the P-polarized component passes through the first selective reflection element 13. In this way, the amount of light that passes through the first selective reflection element 13 at the second incident of the light that is shifted from the optical axis and incidents on the first polarization direction conversion element 15 causes a decrease in the light utilization efficiency.

[0040] 1, for light rays of the first light Lc1 that are not parallel to the Z axis (optical axis), the directions of the incident and exit surfaces do not match when the blue light is incident on the first selective reflection element 13 for the first time and for the second time (see FIG. 4C), so the directions of P polarized light and S polarized light differ depending on the angle of the incident light. The polarization direction of P polarized light (S polarized light) for the first incidence on the first selective reflection element 13 and the polarization direction of P polarized light (S polarized light) for the second incidence are approximately symmetrical with respect to the Y axis.

[0041] Next, it will be described that the transmission and reflection conditions of the first selective reflection element 13 are different between the light Lca that travels along the optical axis and the light Lcb that travels obliquely to the optical axis among the first light Lc1. In the comparative example shown in FIG. 5A, the first polarization direction conversion element 15 is composed of only one first quarter-wave plate 15a. The first polarization direction conversion element 15 is arranged so that the slow axis forms an angle of 45 degrees with respect to the Y axis. In the first light Lcb that is inclined with respect to the optical axis, the second incident light to the first selective reflection element 13, that is, the light whose polarization direction is rotated 90 degrees from the P-polarized light for the first incident and converted to S-polarized light, also contains a P-polarized component for the second incident. As a result, the second incident light to the first selective reflection element 13 may contain a component that passes through the first selective reflection element 13 and returns to the light source unit 3.

[0042] 1 and 5B, the first polarization direction conversion element 15 of the present embodiment includes a first quarter-wave plate 15a and a second quarter-wave plate 15b whose slow axes do not coincide with each other, so that the polarization direction at the time of the second incidence on the first selective reflection element 13 can be made to coincide more with the S-polarized direction for the second incidence. In this way, the first polarization direction conversion element 15 mutually converts linearly polarized light and elliptically polarized light.

[0043] The light Lcb contained in the first light Lc1 is incident on the first selective reflecting element 13 at an angle to the optical axis. The light Lcb1, which is linearly polarized light transmitted through the first selective reflecting element 13, is inclined with respect to the Y axis as shown in FIG. 6. When the light Lcb1 is incident on the first selective reflecting element 13 again, it must be reflected toward the wavelength conversion element 25. At this time, the S-polarized light reflected by the first selective reflecting element 13 must be light having the vibration plane of the light Lcb2. The vibration plane of the light Lcb2 is the vibration plane of the light Lcb1a, which is obtained by converting the vibration plane of the light Lcb1 to be symmetrical with respect to the Y axis, and further rotating it by 90 degrees.

[0044] The light Lca1, which is linearly polarized light that is transmitted through the first selective reflecting element 13 from the light Lca traveling along the optical axis, has a vibration plane along the Y axis. Therefore, when the light Lca1 is again incident on the first selective reflecting element 13, the S-polarized light reflected toward the wavelength conversion element 25 is light Lca2, which has a vibration plane on the X axis.

[0045] The first quarter-wave plate 15a and the second quarter-wave plate 15b are disposed between the first selective reflection element 13 and the color wheel 20. The first quarter-wave plate 15a is disposed so that the slow axis forms an angle of 45 degrees with respect to the Y axis. When used alone, as in the comparative example of FIG. 5A, linearly polarized light incident on the optical axis (P-polarized light for the first incidence on the first selective reflection element 13) is converted into circularly polarized light, and the circularly polarized light reflected by the color wheel 20 and re-entered is converted into linearly polarized light rotated by 90 degrees (S-polarized light for the first incidence on the first selective reflection element 13).

[0046] The second quarter-wave plate 15b is disposed so that its slow axis is parallel or perpendicular to the Y axis. When used alone, it converts linearly polarized light (P-polarized light for the first incidence on the first selective reflection element 13) whose polarization direction is tilted with respect to the Y axis (slow axis) into elliptically polarized light whose major axis coincides with the slow axis regardless of the tilt. The elliptically polarized light reflected by the color wheel 20 and again incident on the second quarter-wave plate 15b is converted into linearly polarized light whose polarization direction is tilted at an angle opposite to that of the first incidence (symmetrical) with respect to the Y axis (slow axis), which almost coincides with the polarization direction of the P-polarized light for the second incidence on the first selective reflection element 13. Therefore, when it is further rotated by 90 degrees, it becomes S-polarized light for the second incidence.

[0047] As a result, by using the first quarter-wave plate 15a and the second quarter-wave plate 15b in combination, the effects of both plates are combined, and the polarization direction at the time of the second incidence on the first selective reflection element 13 approximately matches the S-polarization direction for the second incidence. Therefore, it is possible to reduce the P-polarized component that passes through the first selective reflection element 13 and returns to the light source unit 3. It is possible to prevent a reduction in the blue light reflected by the first selective reflection element 13, and to suppress a reduction in the amount of fluorescent light converted by the wavelength conversion element 25.

[0048] The first light Lc1 emitted from the light source element 3a is converted from P-polarized blue light (P-polarized with respect to the first incident surface to the first selective reflection element 13) to elliptically polarized blue light by passing through the first quarter-wave plate 15a and the second quarter-wave plate 15b. The first light Lc1 converted to elliptically polarized blue light is reflected by the color wheel 20. The light Lc1r reflected by the color wheel 20 is converted from elliptically polarized blue light to S-polarized blue light by passing through the first quarter-wave plate 15a and the second quarter-wave plate 15b again. The converted S-polarized blue light (S-polarized with respect to the second incident surface to the first selective reflection element 13) is reflected by the first selective reflection element 13 and proceeds to the wavelength conversion element 25. Note that, although an example of converting P-polarized light to S-polarized light has been shown here, a similar configuration is also possible when converting S-polarized light to P-polarized light.

[0049] [1-3. Effects, etc.] As described above, in the first embodiment, the light source device 1 includes the light source element 3a that outputs the first light Lc1, which is blue light, the first selective reflection element 13 that is disposed at a position where the first light Lc1 is incident and transmits the incident first linearly polarized light and reflects the second linearly polarized light perpendicular to the first linearly polarized light, the color wheel 20 that is disposed at a position where it receives the light that has passed through the first selective reflection element 13 and transmits or reflects the incident light according to the wavelength range, and the first polarization direction conversion element 15 that is disposed between the first selective reflection element 13 and the color wheel 20 and converts the first linearly polarized light that has passed through the first selective reflection element 13 into elliptically polarized light. The first polarization direction conversion element 15 converts the elliptically polarized light that is reflected by the color wheel 20 and enters again into the second linearly polarized light.

[0050] By converting the first linearly polarized light into elliptically polarized light, the elliptically polarized light reflected by the color wheel 20 can be converted into second linearly polarized light that can be reflected by the first selective reflection element 13. This makes it possible to reduce the amount of light that is not reflected by the first selective reflection element 13, thereby improving the light utilization efficiency of the light source device 1.

[0051] Moreover, the first linearly polarized light is either P polarized light or S polarized light, and the second linearly polarized light is the other of P polarized light and S polarized light. The first polarization direction conversion element 15 converts the first linearly polarized light incident parallel to the optical axis into circularly polarized light, converts the component of the first linearly polarized light incident at an angle to the optical axis into elliptically polarized light that is not circularly polarized light, and converts the circularly polarized light and elliptically polarized light reflected by the color wheel 20 and incident again into the second linearly polarized light.

[0052] This makes it possible to convert both the first linearly polarized light that is incident parallel to the optical axis and the first linearly polarized light that is incident at an angle to the optical axis into the second linearly polarized light, thereby improving the light utilization efficiency.

[0053] In other words, the light utilization efficiency can be improved by converting a first linearly polarized light that is obliquely transmitted through the first selective reflection element 13 having a first transmission axis into an elliptically polarized light that is converted into a second linearly polarized light that is reflected by the first selective reflection element 13 having a second transmission axis that is arranged in a mirror-like relationship with the first transmission axis on the optical path.

[0054] 1, the first selective reflection element 13 is disposed at an angle of approximately 45 degrees with respect to the optical axis around the x-axis, but in order to maximize its spectral characteristics, the angle of the first selective reflection element 13 with respect to the optical axis may be an angle other than approximately 45 degrees, and in that case, other components may be disposed according to that angle. Note that, in the first embodiment, a case has been described in which the light emitted from the light source element 3a is P-polarized, but a similar configuration is possible even if the light is S-polarized.

[0055] In addition, the first polarization direction conversion element 15 has two quarter-wave plates with different slow axes, but can be configured with one wave plate. When the first polarization direction conversion element 15 is configured with two quarter-wave plates with different slow axes, it can appropriately convert the linear polarization of light even when the first selective reflection element 13 is misaligned with respect to the optical axis. In addition, the first polarization direction conversion element 15 may have three or more wave plates with different slow axes.

[0056] Next, a light source device 1A which is a modified example of the light source device 1 of the embodiment 1 will be described with reference to Fig. 7. The light source device 1A is configured such that the first polarization direction conversion element 15 of the light source device 1 is rotatable. Other than this point and the points described below, the light source device 1 of the embodiment 1 and the modified light source device 1A have the same configuration.

[0057] The light source device 1A includes a rotation mechanism 18 (an example of a rotation drive unit) that rotates the first polarization direction conversion element 15. The rotation mechanism 18 is configured with, for example, a motor and a gear mechanism. The rotation mechanism 18 may rotate the first quarter-wave plate 15a and the second quarter-wave plate 15b individually, or may rotate only one of them. The first polarization direction conversion element 15 can adjust the slow axis by the rotation mechanism 18, thereby making it possible to set an optimal linear polarization direction for the first selective reflection element 13. The rotation mechanism 18 can be operated by a user.

[0058] Therefore, according to the light source device 1A, by rotating and adjusting the first quarter-wave plate 15a and the second quarter-wave plate 15b, even if the first selective reflection element 13 is misaligned with respect to the linearly polarized light incident from the light source element 3a, it is possible to convert the P-polarized light into S-polarized light, thereby improving the light utilization efficiency.

[0059] In addition, in the first embodiment, the light transmitted through the first selective reflection element 13 is transmitted to and reflected by the color wheel 20 for use, but this is not limited thereto. As a modified example, the light reflected by the first selective reflection element 13 may be transmitted to and reflected by the color wheel 20 for use. In this case, the color wheel 20 is disposed at a position where it receives the light reflected by the first selective reflection element 13. The first polarization direction conversion element 15 is disposed between the first selective reflection element 13 and the color wheel 20, and converts the first linearly polarized light reflected by the first selective reflection element 13 into elliptically polarized light.

[0060] (Embodiment 2) Next, light source device 1B of embodiment 2 will be described with reference to Fig. 8. Fig. 8 is a schematic diagram showing a configuration example of a light source device according to embodiment 2. Light source device 1B of embodiment 2 includes a reflecting element 41 and a second polarization direction conversion element 43 in light source device 1 of embodiment 1. Other than this point and the points described below, light source device 1B of embodiment 2 has the same configuration as light source device 1 of embodiment 1.

[0061] The reflecting element 41 reflects the light that is reflected by the first selective reflecting element 13 and travels in the opposite direction to the wavelength conversion element 25, toward the first selective reflecting element 13. The reflecting element 41 is, for example, a reflecting mirror.

[0062] The second polarization direction conversion element 43 is disposed between the first selective reflection element 13 and the reflection element 41. The second polarization direction conversion element 43 is, for example, a quarter-wave plate with a slow axis of 45 degrees. As shown in FIG. 4C , the S-polarized light Ls contained in the first light Lc1 reflected by the first selective reflection element 13 toward the reflection element 41 is converted from S-polarized light to elliptically polarized light by the second polarization direction conversion element 43. The light converted into elliptically polarized light is reflected by the reflection element 41 and passes through the second polarization direction conversion element 43 again. At this time, the elliptically polarized light reflected by the reflection element 41 is converted into P-polarized light.

[0063] The light converted into P-polarized light passes through the first selective reflection element 13 and enters the wavelength conversion element 25. This allows a part of the blue light of the first light Lc1 reflected by the first selective reflection element 13 in the opposite direction to the wavelength conversion element 25 to be converted into yellow light, improving the light utilization efficiency. In one example, the second polarization direction conversion element 43 may have at least two quarter-wave plates. The at least two quarter-wave plates have different slow axes. The direction of the slow axis of at least one of the at least two quarter-wave plates is adjustable. In this way, the polarization direction of the light passing through the second polarization direction conversion element 43 can be matched by adjusting the direction of the slow axis of at least one quarter-wave plate of the at least two quarter-wave plates relative to the direction of the slow axis of another quarter-wave plate. That is, the polarization direction of the light can be further matched by using two or more quarter-wave plates compared to the case where only one quarter-wave plate is used. This can further improve the light utilization efficiency of the light source device 1B. In one example, one quarter-wave plate of the second polarization direction conversion element 43 has a slow axis at 45 degrees with respect to the reference axis, and the other quarter-wave plate has a slow axis at 90 degrees with respect to the reference axis. Here, the reference axis is, for example, the X-axis in the XZ plane shown in FIG. 8.

[0064] Alternatively, a configuration may be used in which part of the second light Lc2, which is the fluorescence converted by the wavelength conversion layer 29, passes through the region of the dichroic layer 20B of the color wheel 20.

[0065] Furthermore, the light source device 1B includes a half-wave plate 65 and a rotation mechanism 68 (an example of a rotation drive unit). The half-wave plate 65 is disposed between the concave lens 11 and the first selective reflection element 13, and is configured to be rotatable. The half-wave plate 65 can also be disposed between the convex lens 5 and the concave lens 11. That is, the half-wave plate 65 is disposed between the light source element 3a and the first selective reflection element 13. The rotation mechanism 68 is connected to the half-wave plate 65, and is configured to rotate the half-wave plate 65. The rotation mechanism 68 has a similar configuration to the rotation mechanism 18 (see FIG. 7).

[0066] By rotating the half-wave plate 65, it is possible to adjust the ratio of P-polarized light and S-polarized light in the light that passes through the half-wave plate 65 and enters the first selective reflecting element 13. By adjusting the ratio of P-polarized light and S-polarized light, it is possible to adjust the ratio of the light that passes through the first selective reflecting element 13 and the light that is reflected by the first selective reflecting element 13. This makes it possible to adjust the ratio of blue and yellow light that passes through the color wheel 20 and enters the rod integrator 33. In other words, it is possible to adjust the ratio of blue and yellow light by simply rotating the half-wave plate 65, without changing the configuration behind the first selective reflecting element 13.

[0067] With the above configuration, the manufacturer of the light source device 1B can adjust the color of the light emitted by the light source device 1B by rotating the half-wave plate 65 via the rotation mechanism 68. Furthermore, even if the color of the light emitted by the light source device 1B has changed over time due to a long period of use of the light source device 1B, the user of the light source device 1B can readjust the color of the light to the original color by rotating the half-wave plate 65. Furthermore, the user of the light source device 1B can intentionally change the color of the light emitted by the light source device 1B to a preferred hue by rotating the half-wave plate 65.

[0068] In light source device 1B, half-wave plate 65 and rotation mechanism 68 are not essential components. That is, light source device 1B does not have to include half-wave plate 65 and rotation mechanism 68. By not including half-wave plate 65 and rotation mechanism 68 in light source device 1B, it is possible to suppress a decrease in light efficiency caused by light absorption by half-wave plate 65, and also to reduce costs.

[0069] (Embodiment 3) Next, a light source device 1C according to a third embodiment will be described with reference to FIG. 9. FIG. 9 is a schematic diagram showing a configuration example of a light source device according to the third embodiment. The light source device 1C according to the third embodiment further includes a third polarization direction conversion element 45 disposed between the wavelength conversion element 25 and the first selective reflection element 13 in addition to the light source device 1B according to the second embodiment. An example of the third polarization direction conversion element 45 is a quarter-wave plate. In this respect and other points to be described below, the light source device 1C according to the third embodiment has the same configuration as the light source device 1B according to the second embodiment.

[0070] The first polarization direction conversion element 15 converts the light Lc1r into S-polarized light, and the first selective reflection element 13 reflects this light toward the wavelength conversion element 25. The third polarization direction conversion element 45 converts the blue light reflected by the first selective reflection element 13 from S-polarized light relative to the first selective reflection element 13 into elliptically polarized light. The elliptically polarized blue light is converted from blue light to yellow light by the wavelength conversion element 25. Here, the elliptically polarized blue light that has not been converted into yellow light is reflected by the wavelength conversion element 25, passes through the third polarization direction conversion element 45 again, and is converted from elliptically polarized light to P-polarized light that can be transmitted to the first selective reflection element 13. The light converted into P-polarized light and emitted from the third polarization direction conversion element 45 passes through the first selective reflection element 13 and then passes through the second polarization direction conversion element 43. Since the second polarization direction conversion element 43 is, for example, a quarter-wave plate with a slow axis of 45 degrees, the blue light transmitted through the second polarization direction conversion element 43 is converted from P-polarized light that is transmissible to the first selective reflection element 13 to elliptically polarized light. The blue light converted to elliptically polarized light is reflected by the reflection element 41 and enters the second polarization direction conversion element 43 again.

[0071] The blue light incident again on the second polarization direction conversion element 43 is converted from elliptically polarized light to P-polarized blue light that can be transmitted to the first selective reflection element 13. The blue light converted to P-polarized light for the first selective reflection element 13 transmits through the first selective reflection element 13 and the third polarization direction conversion element 45, and enters the wavelength conversion element 25.

[0072] As a result, the light reflected by the wavelength conversion element 25 without being converted from blue to yellow can be reflected by the reflecting element 41 and can be made to enter the wavelength conversion element 25 again. Therefore, the light can be converted from blue to yellow again, and the light utilization efficiency can be improved. In one example, the third polarization direction conversion element 45 may have at least two quarter-wave plates. The at least two quarter-wave plates have different slow axes. The direction of the slow axis of at least one of the at least two quarter-wave plates is adjustable. In this way, the direction of the slow axis of at least one quarter-wave plate of the at least two quarter-wave plates can be adjusted with respect to the direction of the slow axis of another quarter-wave plate, so that the polarization direction of the light passing through the third polarization direction conversion element 45 can be made to match. That is, compared to the case where only one quarter-wave plate is used, the polarization direction of the light can be made to match by using two or more quarter-wave plates. This can further improve the light utilization efficiency of the light source device 1C. In one example, one quarter-wave plate of the third polarization direction conversion element 45 has a slow axis at 45 degrees to the reference axis, and the other quarter-wave plate has a slow axis at 90 degrees to the reference axis. Here, the reference axis is, for example, the X-axis in the XZ plane shown in FIG. 9.

[0073] (Embodiment 4) Next, light source device 1D of embodiment 4 will be described with reference to Fig. 10. Fig. 10 is a schematic diagram showing a configuration example of a light source device according to embodiment 4. Light source device 1D of embodiment 4 includes a selective reflection element 17 instead of color wheel 20 in light source device 1C of embodiment 3. Apart from this point and points described below, light source device 1D of embodiment 4 has the same configuration as light source device 1C of embodiment 3.

[0074] The light source device 1D of the fourth embodiment is, for example, a light source device for a three-chip liquid crystal projection type image display device. The selective reflection element 17 is disposed between the first polarization direction conversion element 15 and the light collecting element 19.

[0075] The selective reflection element 17 reflects a part of the first light Lc1 and transmits the remainder of the first light Lc1, thereby separating the first light Lc1 into light Lc1r that is later converted into fluorescence and light Lc1t that is emitted as blue light, and transmits the yellow second light Lc2. The selective reflection element 17 is, for example, a single dichroic mirror.

[0076] The selective reflection element 17 has, for example, a reflectance of 70% or more for the first light Lc1 and a transmittance of 95% or more for the second light Lc2. A dielectric film is uniformly formed on the surface of the selective reflection element 17, and the transmittance of the first light Lc1 is uniform. The first light Lc1 transmitted through the selective reflection element 17 is incident on the light collecting element 19 (see FIG. 12).

[0077] A portion of the first light Lc1 reflected by the selective reflection element 17, namely light Lc1r, is transmitted through the first polarization direction conversion element 15 and converted from elliptically polarized light into S-polarized blue light that is reflected by the first selective reflection element 13. The light Lc1r, which is S-polarized blue light, has its traveling direction changed by 90 degrees by the first selective reflection element 13 and is reflected in the direction of the wavelength conversion element 25, where it is converted into the second light Lc2, which is yellow light.

[0078] In light source device 1D of the fourth embodiment, blue light and yellow light can be emitted simultaneously, and light utilization efficiency can be improved in the same way as light source device 1C of the third embodiment.

[0079] (Embodiment 5) Next, a projection-type image display device 101 according to a fifth embodiment will be described with reference to Fig. 11. Fig. 11 is a diagram showing a configuration of the projection-type image display device 101 according to the fifth embodiment. As shown in Fig. 11, the projection-type image display device 101 according to the fifth embodiment is, for example, a one-chip DLP type projection-type image display device. The projection-type image display device 101 includes a light source device 1C.

[0080] The light emitted from rod integrator 33 is imaged by a relay lens system consisting of convex lenses 131, 132, and 133 onto DMD 141, which will be described later.

[0081] The light that passes through convex lenses 131 , 132 , and 133 and enters total reflection prism 134 enters minute gap 135 of total reflection prism 134 at an angle equal to or greater than the total reflection angle, and is reflected to change the direction of travel of the light before entering DMD 141 .

[0082] The DMD 141 changes the direction of the micromirrors in response to a signal from a video circuit (not shown) synchronized with the colored light emitted from the color wheel 20, and emits the light in a different traveling direction.

[0083] The light, whose direction of travel has been changed in response to the video signal in DMD 141, enters total reflection prism 134 and enters tiny gap 135 of total reflection prism 134 at an angle less than the total reflection angle, thereby passing through as is and entering projection lens unit 151, which serves as a projection optical system, and is projected onto a screen not shown.

[0084] According to the projection type image display device 101 of the fifth embodiment, the light utilization efficiency of the light source device 1C can be improved, and therefore the brightness of the projected image can be improved.

[0085] (Embodiment 6) Next, a projection-type image display device 101A according to a sixth embodiment will be described with reference to Fig. 12. Fig. 12 is a diagram showing a configuration of the projection-type image display device 101A according to the sixth embodiment. As shown in Fig. 12, the sixth embodiment is a projection-type image display device 101A that uses the light source device 1D according to the fourth embodiment.

[0086] Projection-type image display device according to the sixth embodiment 101A This is a so-called 3-chip type projection display device. Note that the 3-chip DLP type is an example of a projection display device that uses the device of this invention, and the number of display elements may be other than 3.

[0087] Light emitted from light source device 1D via condenser element 19 and rod integrator 33 is projected by a relay lens system consisting of convex lenses 301, 302, and 303 onto DMDs (Digital Micromirror Devices) 311, 312, and 313 serving as light modulation sections.

[0088] Light that leaves the relay lens system composed of convex lenses 301, 302, and 303 enters total reflection prism 304 with minute gap 305. Light that leaves the relay lens system and enters total reflection prism 304 at an angle equal to or greater than the total reflection angle is reflected by minute gap 305, changing the direction of travel of the light, and enters color prism 309 composed of three glass blocks 306, 307, and 308 with minute gap 305.

[0089] Of the blue light and fluorescent light incident on the first glass block 308 of color prism 309 from total reflection prism 304, the blue light is first reflected by a spectrally-characteristic reflective film with blue reflection properties provided in front of the tiny gap, changes its direction, travels to total reflection prism 304, and enters the tiny gap provided between total reflection prism 304 and color prism 309 at an angle greater than the total reflection angle, and enters DMD 313, which displays a blue image.

[0090] Next, the red light of the fluorescent light that passes through the minute gap is reflected by a spectrally-characteristic reflective film that is provided between the second glass block 307 and the third glass block 306 of the color prism 309 and has spectral characteristics that reflect light in the red wavelength range and transmit green light, and then changes its direction of travel toward the first glass block 308.

[0091] The red light, whose traveling direction has been changed, is reflected again by a minute gap provided between first glass block 308 and second glass block 307 of color prism 309, and its traveling direction is changed again to enter DMD 312 for red light.

[0092] In addition, the green light of the fluorescent light that passes through the micro gap reflects light in the red wavelength region provided between the second glass block 307 and the third glass block 306 of the color prism, passes through a spectrally-characteristic reflective film that has spectral characteristics that allow green light to pass through, and proceeds directly to the third glass block 306, and then enters the green DMD 311 as is.

[0093] DMDs 311, 312, and 313 change the direction of light travel by changing the direction of the mirror for each pixel in response to a video signal for each color from a video circuit (not shown).

[0094] The green light, whose direction of travel has been changed in response to the video signal by the green DMD 311, enters the third glass block 306 of the color prism 309 and passes through a reflective film with spectral characteristics provided between the third glass block 306 and the second glass block 307 of the color prism 309.

[0095] The red light, whose direction of travel has been changed by red DMD 312 in response to a video signal, enters second glass block 307 of color prism 309 and is reflected by entering a minute gap provided between second glass block 307 and first glass block 308 of color prism 309 at an angle equal to or greater than the angle of total reflection. The red light then changes its direction of travel to third glass block 306 of color prism 309, where it is reflected by a reflective film with spectral characteristics provided between second glass block 307 and third glass block 306 of color prism 309, changing its direction of travel and being combined with the green light.

[0096] The light combined by the spectrally-characteristic reflective film travels toward the first glass block 308 of the color prism 309, and is transmitted by entering a tiny gap between the second glass block 307 and the first glass block 308 of the color prism 309 at an angle less than the total reflection angle.

[0097] Furthermore, the blue light, whose traveling direction has been changed by blue DMD 313 in response to the video signal, enters first glass block 308 of color prism 309, travels toward total reflection prism 304, and travels toward second glass block 307 of color prism 309 by entering a gap between total reflection prism 304 and color prism 309 at an angle equal to or greater than the total reflection angle. The blue light is then reflected by a reflective film with spectral characteristics provided on the first glass block 308 side in front of the minute gap provided between first glass block 308 and second glass block 307 of color prism 309, changes its traveling direction toward total reflection prism 304, is combined with the light from green DMD 311 and red DMD 312, and enters total reflection prism 304.

[0098] The light from DMDs 311, 312, and 313 that is incident on total reflection prism 304 passes through total reflection prism 304, enters projection lens unit 321 as a projection optical system, and is irradiated onto a screen (not shown).

[0099] According to light source device 1D and projection-type image display device 101A in the sixth embodiment, the light utilization efficiency of light source device 1D can be improved, and therefore the brightness of the projected image can be improved.

[0100] (Embodiment 7) Next, a projection-type image display device 101B according to a seventh embodiment will be described with reference to Fig. 13. Fig. 13 is a diagram showing the configuration of the projection-type image display device 101B according to the seventh embodiment. As shown in Fig. 13, the seventh embodiment is a projection-type image display device 101B that uses the light source device 1D according to the fourth embodiment.

[0101] The projection type image display device 101B uses, as an image forming means, a TN (Twisted Nematic) mode or VA (Vertical Alignment) mode, active matrix type transmissive liquid crystal panel in which thin film transistors are formed in the pixel region.

[0102] The light emitted from light source device 1D is incident on projection lens 224 via an optical system consisting of first lens array plate 199, mirror 200, second lens array plate 201, polarization conversion element 202, superposition lens 203, blue-reflecting dichroic mirror 204, green-reflecting dichroic mirror 205, reflecting mirrors 206, 207, 208, relay lenses 209, 210, field lenses 211, 212, 213, incident side polarizing plates 214, 215, 216, liquid crystal panels 217, 218, 219, exit side polarizing plates 220, 221, 222, and a color synthesis prism 223 composed of a red-reflecting dichroic mirror and a blue-reflecting dichroic mirror.

[0103] White light from the light source device 1D is incident on a first lens array plate 199 composed of a plurality of lens elements. The light beam incident on the first lens array plate 199 is divided into a number of light beams. The divided number of light beams are reflected by a mirror 200 and converge on a second lens array plate 201 composed of a plurality of lenses. The lens elements of the first lens array plate 199 have an opening shape similar to that of the liquid crystal panels 217, 218, and 219. The focal length of the lens elements of the second lens array plate 201 is determined so that the first lens array plate 199 and the liquid crystal panels 217, 218, and 219 are in a substantially conjugate relationship. The light emitted from the second lens array plate 201 is incident on a polarization conversion element 202.

[0104] The polarization conversion element 202 is composed of a polarization separation prism and a half-wave plate, and converts natural light from a light source into light with one polarization direction. Since fluorescent light is natural light, it is polarized and converted into one polarization direction, but since blue light enters as S-polarized light, it is converted into P-polarized light. The light from the polarization conversion element 202 enters the superimposing lens 203. The superimposing lens 203 is a lens for superimposing and illuminating the light emitted from each lens element of the second lens array plate 201 onto the liquid crystal panels 217, 218, and 219. The first lens array plate 199, the second lens array plate 201, the polarization conversion element 202, and the superimposing lens 203 form an illumination optical system.

[0105] The light from superimposing lens 203 is separated into blue, green, and red color lights by blue-reflecting dichroic mirror 204 and green-reflecting dichroic mirror 205, which are color separation means. The green light passes through field lens 211 and incident side polarizer 214, and enters liquid crystal panel 217. The blue light is reflected by reflecting mirror 206, then passes through field lens 212 and incident side polarizer 215, and enters liquid crystal panel 218. The red light is refracted and reflected by relay lenses 209, 210 and reflecting mirrors 207, 208, passes through field lens 213 and incident side polarizer 216, and enters liquid crystal panel 219.

[0106] The three liquid crystal panels 217, 218, 219 change the polarization state of the incident light by controlling the voltage applied to the pixels according to the video signal, and modulate the light by combining the incident side polarizing plates 214, 215, 216 and the exit side polarizing plates 220, 221, 222 arranged on both sides of each liquid crystal panel 217, 218, 219 so that the transmission axis is perpendicular to each other, to form green, blue, and red images. The red and blue light transmitted through the exit side polarizing plates 220, 221, 222 is reflected by a color synthesis prism 223 by a red-reflecting dichroic mirror and a blue-reflecting dichroic mirror, respectively, and is synthesized with the green light, and enters a projection lens 224. The light incident on the projection lens 224 is enlarged and projected onto a screen (not shown).

[0107] According to the projection type image display device 101B of the seventh embodiment, the light utilization efficiency of the light source device 1D can be improved, and therefore the brightness of the projected image can be improved.

[0108] (Other embodiments) As described above, the above-mentioned embodiment has been described as an example of the technology disclosed in this application. For this purpose, the attached drawings and detailed description have been provided. However, the technology in this disclosure is not limited to this, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. In addition, it is also possible to combine the components described in the above-mentioned embodiment to create a new embodiment.

[0109] In addition, among the components described in the attached drawings and detailed description, not only are there components essential for solving the problem, but there may also be components that are not essential for solving the problem in order to illustrate the above technology. Therefore, the fact that such non-essential components are described in the attached drawings or detailed description should not be interpreted as immediately indicating that such non-essential components are essential.

[0110] Furthermore, since the above-described embodiments are intended to illustrate the technology in the present disclosure, various modifications, substitutions, additions, omissions, and the like can be made within the scope of the claims or their equivalents.

[0111] (Outline of the embodiment) (1) A light source device according to the present disclosure includes a light source element that outputs a first light, which is light in a first wavelength range, and a first linearly polarized light beam that is disposed at a position where the first light is incident and is defined by the incident direction and reflection direction of the incident light. of The first linearly polarized light component is transmitted. of A second linearly polarized light having a plane of vibration perpendicular to that of the first component. Ingredients a first selective reflection element that reflects light having a wavelength range other than that of the first selective reflection element, a second selective reflection element that is disposed at a position to receive light having been transmitted through or reflected by the first selective reflection element and transmits or reflects the incident light in accordance with a wavelength range, and a third selective reflection element that is disposed between the first selective reflection element and the second selective reflection element and transmits or reflects the incident light in accordance with a wavelength range. or reflection and a first polarization direction conversion element that converts the first linearly polarized light reflected by the second selective reflection element into elliptically polarized light. The first polarization direction conversion element converts the elliptically polarized light that is reflected by the second selective reflection element and enters again into second linearly polarized light.

[0112] This makes it possible to suppress a decrease in conversion efficiency and reduce changes in the proportion of light irradiated to two types of wavelength conversion layers, each of which converts light into light of different wavelength regions, caused by misalignment of the irradiated light spot.

[0113] (2) In the light source device of (1), the first linearly polarized light is either P polarized light or S polarized light, and the second linearly polarized light is the other of P polarized light or S polarized light. The first polarization direction conversion element converts the first linearly polarized light incident parallel to the optical axis into circularly polarized light and converts the component of the first linearly polarized light incident at an angle to the optical axis into elliptically polarized light. The second selective reflection element reflects the circularly polarized light and elliptically polarized light incident again, and converts them into the second linearly polarized light.

[0114] (3) In the light source device of (1) or (2), the first polarization direction conversion element has at least two wave plates.

[0115] (4) In the light source device of (3), at least two wave plates have different slow axes.

[0116] (5) In the light source device of (4), the at least two wave plates include a wave plate having a slow axis at 45 degrees and a wave plate having a slow axis at 90 degrees.

[0117] (6) In the light source device according to any one of (3) to (5), at least one of the at least two wave plates has an adjustable slow axis direction.

[0118] (7) The light source device of (6) further comprises a rotation drive unit that rotates at least one of the at least two wave plates.

[0119] (8) The light source device of the present disclosure includes a light source element that outputs a first light, which is light in a first wavelength range; a first selective reflection element that is arranged at a position where the first light is incident and transmits or reflects a first linearly polarized light defined by the incident direction and reflection direction of the incident light and reflects or transmits a second linearly polarized light; a second selective reflection element that is arranged at a position to receive the light that has been transmitted or reflected by the first selective reflection element and transmits or reflects the incident light in accordance with the wavelength range; a wavelength conversion element that is arranged at a position where the light that has been reflected or transmitted by the first selective reflection element is incident and converts the light that has been reflected or transmitted by the first selective reflection element into second light, which is light in a second wavelength range; a reflection element that is arranged between the first selective reflection element and the wavelength conversion element and reflects light that has been transmitted through or reflected by the first selective reflection element; and a second polarization direction conversion element that is arranged between the first selective reflection element and the reflection element.

[0120] (9) In the light source device of the present disclosure, the second polarization direction conversion element has at least two wave plates.

[0121] In the light source device of (10)(9), at least two wave plates have different slow axes.

[0122] (11) In the light source device of (9) or (10), at least one of the at least two wave plates has an adjustable slow axis direction.

[0123] (12) In any one of the light source devices (1) to (7), the light source device further comprises: a wavelength conversion element arranged at a position where light reflected from the first selective reflection element is incident, and converting the light reflected from the first selective reflection element into a second light that is light in a second wavelength range; a reflection element that reflects the second light emitted from the wavelength conversion element and transmitted through the first selective reflection element toward the first selective reflection element; a second polarization direction conversion element arranged between the wavelength conversion element and the reflection element; and a third polarization direction conversion element arranged between the wavelength conversion element and the first selective reflection element.

[0124] (13) In the light source device of (12), the third polarization direction conversion element has at least two wave plates.

[0125] (14) In the light source device of (13), at least two wave plates of the third polarization direction conversion element have different slow axes.

[0126] (15) In the light source device of (13) or (14), at least one of the at least two wave plates of the third polarization direction conversion element has an adjustable slow axis direction.

[0127] (16) A projection type image display device according to the present disclosure includes a light source device according to any one of (1) to (15), a light modulation unit that generates image light using light emitted from the light source device, and and a projection optical system that projects the image light. [Industrial Applicability]

[0128] The present disclosure is applicable to wavelength conversion devices that irradiate illumination light and convert the wavelength of the light, phosphor wheels, light source devices that use light whose wavelength has been converted by a phosphor wheel, and projection-type image display devices. [Explanation of symbols]

[0129] 1, 1A, 1B, 1C, 1D light source device 3 Light source section 3a Light source element 3b Collimator lens 5 Convex Lens 7 Diffuser 11 Concave Lens 13 First selective reflection element 15 First polarization direction conversion element 15a First quarter-wave plate 15b Second quarter-wave plate 17 Selective Reflection Element 18 Rotation mechanism 19 Light-collecting element 20. Color Wheel 21 Condenser lens 23 Condenser Lens 25 Wavelength conversion element 27 Substrate 29 Wavelength conversion layer 31 Motor 33 Rod Integrator 41 Reflective elements 43 Second polarization direction conversion element 45 Third polarization direction conversion element 51 First Frey Eye Lens 53 Second Frey Eye Lens 65 Half-wave plate 68 Rotation Mechanism 101, 101A, 101B Projection type image display device Lc1 First Light Lc2 Second Light

Claims

1. a light source element that outputs a first light, which is light in a first wavelength range; a first selective reflection element that is disposed at a position where the first light is incident, transmits a first linearly polarized component having a vibration plane that is a plane defined by the incident direction and reflection direction of the incident light, and reflects a second linearly polarized component having a vibration plane that is orthogonal to the vibration plane of the first linearly polarized component; a second selective reflection element that is disposed at a position to receive light transmitted through or reflected by the first selective reflection element and transmits or reflects incident light in accordance with a wavelength range of the incident light; a first polarization direction conversion element disposed between the first selective reflection element and the second selective reflection element, the first polarization direction conversion element converting the first linearly polarized light transmitted through or reflected by the first selective reflection element into elliptically polarized light; the first polarization direction conversion element converts the elliptically polarized light, which is reflected by the second selective reflection element and enters the first polarization direction conversion element again, into the second linearly polarized light; Light source device.

2. the first linearly polarized light is P-polarized light, the second linearly polarized light is S-polarized light, The first polarization direction conversion element is converting the first linearly polarized light parallel to an optical axis into circularly polarized light, and converting a component of the first linearly polarized light tilted relative to the optical axis into non-circularly polarized elliptically polarized light; The circularly polarized light and the non-circularly polarized elliptically polarized light, which are reflected by the second selective reflection element and then enter the first polarization direction conversion element again, are converted into the second linearly polarized light. The light source device according to claim 1 .

3. the first linearly polarized light is S-polarized light, the second linearly polarized light is P-polarized light, The first polarization direction conversion element includes: converting the first linearly polarized light parallel to an optical axis into circularly polarized light, and converting a component of the first linearly polarized light tilted relative to the optical axis into non-circularly polarized elliptically polarized light; The circularly polarized light and the non-circularly polarized elliptically polarized light, which are reflected by the second selective reflection element and then enter the first polarization direction conversion element again, are converted into the second linearly polarized light.

2. The light source device of claim 1.

4. The first polarization direction conversion element has at least two wave plates. The light source device according to claim 1 .

5. The at least two wave plates are a first quarter wave plate having a first slow axis; a second quarter-wave plate having a second slow axis different from the first slow axis; 、 The light source device according to claim 4 .

6. The first quarter-wave plate has a 45° slow axis as the first slow axis, The second quarter-wave plate has a 90 degree slow axis as the second slow axis. The light source device according to claim 5 .

7. The direction of the slow axis of at least one of the at least two wave plates is adjustable. The light source device according to claim 4 .

8. Further comprising a rotary drive unit that rotates the at least one wave plate. The light source device according to claim 7.

9. a wavelength conversion element that is disposed at a position where the light reflected or transmitted through the first selective reflection element is incident, and that converts the light reflected or transmitted through the first selective reflection element into a second light that is light in a second wavelength range; a reflecting element that reflects the first light emitted from the wavelength conversion element and transmitted through or reflected by the first selective reflecting element toward the first selective reflecting element; a second polarization direction conversion element disposed between the reflecting element and the first selective reflecting element; A third polarization direction conversion element is disposed between the wavelength conversion element and the first selective reflection element. The light source device according to claim 1 .

10. The third polarization direction conversion element has at least two wave plates. The light source device according to claim 9 .

11. The at least two wave plates of the third polarization direction conversion element have slow axes different from each other. The light source device according to claim 10.

12. The direction of the slow axis of at least one of the at least two wave plates of the third polarization direction conversion element is adjustable. The light source device according to claim 10.

13. a light source element that outputs a first light, which is light in a first wavelength range; a first selective reflection element that is disposed at a position where the first light is incident, transmits or reflects a first linearly polarized light having a vibration plane that is a plane defined by the incident direction and reflection direction of the incident light, and reflects or transmits a second linearly polarized light; a second selective reflection element that is disposed at a position to receive light transmitted through or reflected by the first selective reflection element and transmits or reflects incident light in accordance with a wavelength range of the incident light; a wavelength conversion element that is disposed at a position where the light reflected or transmitted through the first selective reflection element is incident, and that converts the light reflected or transmitted through the first selective reflection element into a second light that is light in a second wavelength range; a reflecting element that reflects the first light that is reflected by the wavelength conversion element, enters the first selective reflecting element, and is transmitted or reflected by the first selective reflecting element; a second polarization direction conversion element disposed between the first selective reflection element and the reflection element; Light source device.

14. The second polarization direction conversion element has at least two wave plates. The light source device according to claim 13.

15. The at least two wave plates have different slow axes. The light source device according to claim 14.

16. The direction of the slow axis of at least one of the at least two wave plates is adjustable. The light source device according to claim 14.

17. a half-wave plate disposed between the light source element and the first selective reflector and configured to rotate; The light source device according to claim 13.

18. a rotary drive configured to rotate the half-wave plate, 18. A light source device according to claim 17.

19. the first light is blue light; the second light is a yellow light; The light source device according to claim 9 .

20. A light source device according to any one of claims 1 to 19, a light modulation unit that generates image light using light emitted from the light source device; A projection optical system that projects the image light. Projection type image display device.

Images