JP6202655B2 - Light source device and projector - Google Patents

Description

  The present invention relates to a light source device including a phosphor and a projector using the same.

  Patent Document 1 describes a light source device for a projector using a phosphor as a light source. FIG. 1 shows the configuration of the light source device.

  Referring to FIG. 1, the excitation light source 116 includes a plurality of blue laser diodes (LD). The blue excitation light output from the excitation light source 116 is converted into a parallel light beam by the collimating lens array 106 and then enters the dichroic mirror 115. The excitation light source 116 is arranged so that the output light is incident on the dichroic mirror 115 as S-polarized light. The dichroic mirror 115 is arranged so that the incident angle of the blue excitation light is 45 °. Here, the incident angle is an angle formed between an incident light beam and a normal line set up at the incident point.

  FIG. 2 shows the spectral transmission characteristics of the dichroic mirror 115. The vertical axis represents the transmittance, and the horizontal axis represents the wavelength (nm). The solid line indicates the spectral transmission characteristic for S-polarized light, and the broken line indicates the spectral transmission characteristic for P-polarized light. The cutoff wavelength of S-polarized light is 456 nm, and the cutoff wavelength of P-polarized light is 434 nm. Here, the cutoff wavelength is a wavelength at which the transmittance is 50%.

  The dichroic mirror 115 has a characteristic of transmitting light of 456 nm or more with respect to S-polarized light and reflecting light of less than 456 nm, transmits light of 434 nm or more with respect to P-polarized light, It has a characteristic of reflecting light of less than 434 nm. The wavelength of the blue excitation light is, for example, 445 nm. Blue excitation light (S-polarized light) from the excitation light source 116 is reflected by the dichroic mirror 115.

  The blue excitation light (S-polarized light) reflected by the dichroic mirror 115 passes through the quarter wavelength plate 108 and becomes circularly polarized light. Blue excitation light (circularly polarized light) that has passed through the quarter-wave plate 108 is condensed on the phosphor layer 103 by the two condensing lenses 109a and 109b.

  The phosphor layer 103 is formed on a substrate on which dichroic coating has been applied. The substrate is divided into first to third segments in the circumferential direction, and the phosphor layer 103 includes a red phosphor region formed in the first segment and a green phosphor formed in the second segment. Area. A reflective coat is applied to the third segment. As the substrate rotates, the first to third segments are sequentially irradiated with blue excitation light (circularly polarized light).

  In the first segment, the phosphor excited by the blue excitation light emits red fluorescence. In the second segment, the phosphor excited by the blue excitation light emits green fluorescence. In the third segment, blue excitation light (circularly polarized light) is reflected by the reflective coating surface.

  The red fluorescent light from the first segment, the green fluorescent light from the second segment, and the blue light (circularly polarized light) reflected by the reflective coating surface of the third segment are the condensing lenses 109a and 109b and the quarter wavelength plate. 108 is sequentially passed. Here, blue light (circularly polarized light) from the third segment becomes P-polarized light when passing through the quarter-wave plate 108. Red fluorescent light, green fluorescent light, and blue light (P-polarized light) are transmitted through the dichroic mirror 115.

  Although not shown in FIG. 1, red fluorescent light, green fluorescent light, and blue light (P-polarized light) transmitted through the dichroic mirror 115 are collected on one end face of the rod integrator by a condenser lens. In the rod integrator, light incident from one end face propagates through the rod and is emitted from the other face. By using a rod integrator, output light having a uniform light intensity distribution in a plane perpendicular to the optical axis can be obtained.

  In general, when an LD is used as an excitation light source, a quarter-wave plate made of quartz having excellent light resistance is used. However, the quarter-wave plate of quartz works to give a phase difference of π / 2 (= 1 / 4λ) to the polarization plane of incident light for light with an incident angle of 5 ° or less. For light having an angle exceeding 5 °, it has an angle dependency of maintaining polarization. For this reason, it is necessary to arrange the quarter wavelength plate of quartz on the optical path close to the parallel light flux.

  Also in the light source device shown in FIG. 1, since the LD is used as the excitation light source 116, the quarter wavelength plate 108 is usually made of quartz. The quarter-wave plate 108 is disposed between the condensing lens 109a and the dichroic mirror 115. Since the blue excitation light between the condensing lens 109a and the dichroic mirror 115 is a parallel light flux, the quarter-wave plate The influence of the angle dependency of 108 does not occur.

JP 2012-108486 A

  However, the light source device described in Patent Document 1 has the following problems.

  Fluorescence from the phosphor layer 103 propagates as a divergent light beam between the phosphor layer 103 and the condensing lens on the rod integrator side. In this case, the longer the distance from the phosphor layer 103 is, the larger the fluorescent light beam diameter is. Therefore, when the distance from the phosphor layer 103 to the condenser lens on the rod integrator side is increased, the size of the condenser lens is increased. It is necessary to increase the size, resulting in an increase in size and cost of the optical system.

  In addition, when the distance from the phosphor layer 103 to the condensing lens on the rod integrator side increases, the distance between the condensing lens and the rod integrator also increases, resulting in further enlargement of the optical system.

  For the above reasons, it is desirable to make the distance from the phosphor layer 103 to the condensing lens on the rod integrator side as short as possible.

  However, in the light source device described in Patent Document 1, the quarter-wave plate 108 is disposed between the condensing lens 109 and the dichroic mirror 115, so that the distance between the condensing lens 109 and the dichroic mirror 115 is small. As a result, the distance from the phosphor layer 103 to the condensing lens on the rod integrator side increases. For this reason, the problem of the enlargement of said optical system and a cost increase arises.

  An object of the present invention is to provide a light source device capable of reducing the size and cost of an optical system and a projector using the same.

  In order to achieve the above object, according to one aspect of the present invention, a light source that outputs excitation light, a dichroic mirror that reflects or transmits the first linearly polarized light of the light from the light source, and a plurality of lenses are provided. A first condensing lens group for condensing the reflected light or transmitted light from the dichroic mirror, a phosphor region provided with a phosphor, and a reflecting region for reflecting incident light. A phosphor unit movable so that light from the optical lens group is sequentially irradiated onto the phosphor region and the reflection region, and a quarter wavelength plate provided between two adjacent lenses among the plurality of lenses Each of the first condenser lens group and the phosphor unit is configured such that the fluorescence emitted from the phosphor area and the reflected light from the reflection area are the first condenser lens group and Through a quarter-wave plate Wherein is arranged to be incident on the dichroic mirror, the light source device is provided.

  According to another aspect of the present invention, the light source device, a display element that spatially modulates light output from the light source device to form an image, and an image formed by the display element are enlarged and projected. A projection optical system is provided.

It is a schematic diagram which shows the structure of the light source device of patent document 1. FIG. It is a characteristic view which shows the spectral transmission characteristic of the dichroic mirror of the light source device shown in FIG. It is a schematic diagram which shows the structure of the light source device by the 1st Embodiment of this invention. It is a schematic diagram which shows an example of the fluorescent substance wheel used for the light source device shown in FIG. It is a schematic diagram which shows an example of the color wheel used for the light source device shown in FIG. It is a schematic diagram for demonstrating the relationship between the arrangement position of the quarter wavelength plate and incident area in the light source device shown in FIG. It is a figure which shows the light ray angle distribution in each position shown in FIG. It is a schematic diagram which shows the optical path of the blue light and fluorescence of the light source device shown in FIG. It is a schematic diagram which shows an example of a projector provided with the light source device shown in FIG. It is a schematic diagram which shows an example of the projector provided with the light source device by the 3rd Embodiment of this invention.

DESCRIPTION OF SYMBOLS 1a Light source 1b Collimator lens 1c-1e, 1i, 1k, 1m Lens 1f Polarization separation element 1g Diffusion plate 1h Dichroic mirror 1j 1/4 wavelength plate 1l Phosphor unit 1n Color filter unit

  Next, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 3 shows a configuration of the light source device according to the first embodiment of the present invention.

  Referring to FIG. 3, the light source device 1 includes a light source 1a, a collimator lens 1b, lenses 1c to 1e, 1i, 1k, 1m, a polarization separation element 1f, a diffusing plate 1g, a dichroic mirror 1h, a quarter wavelength plate 1j, and a fluorescence. A body unit 11 and a color filter unit 1n.

  The light source 1a includes a blue laser diode (LD) that outputs blue light having a peak wavelength in a blue wavelength region. For example, the light source 1a is composed of blue LDs arranged in a 6 × 4 matrix. However, the number of blue LDs is not limited to 24. The number of blue LDs may be increased or decreased as necessary.

  The collimator lens 1b is provided for each blue LD, and converts the blue light output from the blue LD into a parallel light beam.

  The lenses 1c to 1e convert each blue light (incident light beam) incident from the light source 1a via the collimator lens 1b into a parallel light beam with a reduced light beam diameter. By making the diameter of the outgoing light beam smaller than that of the incident light beam, the size of the members disposed after the lenses 1c to 1e can be reduced. Here, three lenses 1c to 1e are used, but the number of lenses is not limited to three. The number of lenses may be increased or decreased as necessary.

  The blue light emitted from the lenses 1c to 1e enters the dichroic mirror 1h via the polarization separation element 1f. A diffusion plate 1g is disposed on the optical path between the polarization separation element 1f and the dichroic mirror 1h. The diffusion plate 1g diffuses the blue light from the polarization separation element 1f. The diffusion angle is about 3 °, for example. Here, the diffusion angle is an angle formed by a light beam passing through the center of the light beam (center light beam) and a light beam passing through the outermost side of the light beam.

  The polarization separation element 1f has a characteristic of separating S-polarized light and P-polarized light. Here, the polarization separation element 1f has characteristics of reflecting S-polarized light and transmitting P-polarized light, and the light source 1a is arranged so that the output light (blue light) is incident on the separation element 1f as S-polarized light. ing. A polarizing plate or a dichroic mirror can be used as the polarization separation element 1f.

  Blue light (S-polarized light) reflected by the polarization separation element 1f enters the dichroic mirror 1h. The dichroic mirror 1h transmits light having a first wavelength longer than the wavelength of the light source 1a (the wavelength of blue light) and reflects light having a wavelength less than the first wavelength with respect to light incident as S-polarized light. Have The dichroic mirror 1h transmits light having a second wavelength shorter than the wavelength of the light source 1a (blue light wavelength) and reflects light having a wavelength less than the second wavelength with respect to light incident as P-polarized light. Have the following characteristics: The dichroic mirror 1h having such characteristics (for example, the characteristics shown in FIG. 2) can be realized by a dielectric multilayer film.

  The dichroic mirror 1h guides blue light (S-polarized light) from the polarization separation element 1f to the phosphor unit 1l. A quarter-wave plate 1j and lenses 1i and 1k are arranged on the optical path between the dichroic mirror 1h and the phosphor unit 11.

  The phosphor unit 11 includes a phosphor wheel in which a phosphor region provided with a phosphor that emits fluorescence when excited by excitation light and a reflection region are sequentially arranged in the circumferential direction, and a drive unit that rotates the phosphor wheel ( Motor).

  FIG. 4 shows an example of the phosphor wheel. Referring to FIG. 4, the phosphor wheel includes a yellow phosphor region 10Y, a green phosphor region 10G, and a reflection region 10B. The yellow phosphor region 10Y, the green phosphor region 10G, and the reflection region 10B are formed to be aligned in the circumferential direction.

  The reflection region 10B reflects blue light from the light source 1a. The yellow phosphor region 10Y includes a phosphor that emits yellow fluorescence when excited by excitation light. The green phosphor region 10G includes a phosphor that emits green fluorescence when excited by excitation light. Both the yellow phosphor and the green phosphor can be excited by blue light from the light source 1a. The yellow fluorescence includes light in the wavelength range from green to red.

  The ratio of the area in the circumferential direction (division ratio in the circumferential direction) of each of the yellow phosphor region 10Y, the green phosphor region 10G, and the reflection region 10B is yellow light, red light, and green contained in the output light of the light source device 1. It is appropriately set according to the balance of light intensity of light and blue light.

  The quarter wave plate 1j is made of an inorganic material having excellent light resistance. For example, the quarter wave plate 1j has a birefringent multilayer film made of an inorganic material (dielectric). The birefringent multilayer film is configured to give a phase difference of π / 2 (= 1 / 4λ) to the polarization plane of incident light. For example, it is known that a birefringent layer having an oblique columnar structure formed by depositing particles from an oblique direction with respect to a substrate surface has birefringence with respect to a light beam incident perpendicularly to the substrate surface. . In such a birefringent layer, an arbitrary phase difference can be given to the polarization plane of incident light by adjusting the film thickness. Also in this embodiment, the quarter-wave plate 1j is formed by a birefringent multilayer film to which this oblique columnar structure is applied. Compared with a quarter-wave plate of quartz, the angle dependence of the inorganic quarter-wave plate 1j is small. For example, the inorganic quarter-wave plate 1j can give a phase difference to light having an incident angle of 40 ° or less. In addition, the inorganic quarter-wave plate 1j can be made thinner than a quartz quarter-wave plate, and for example, a thickness of 0.3 mm or less can be provided.

  The quarter wave plate 1j is disposed between the lenses 1i and 1k. The lenses 1i and 1k are a condensing lens group that condenses the blue light from the dichroic mirror 1h on the phosphor wheel of the phosphor unit 1l. In the present embodiment, the condensing lens group is configured by the two lenses 1i and 1k, but is not limited thereto. The condensing lens group may be composed of three or more lenses. In this case, the quarter wavelength plate 1j is disposed between any one of the condensing lens groups. However, between the lenses on which the quarter-wave plate 1j is arranged, a condition that the incident angle of blue light to the quarter-wave plate 1j is an angle that does not affect the angle dependency of the quarter-wave plate 1j. Meet. In order to satisfy this condition with certainty, the quarter-wave plate 1j includes a first lens located closest to the dichroic mirror 1h among a plurality of lenses, and a second lens adjacent to the first lens. It may be arranged between.

  Blue light (S-polarized light) from the dichroic mirror 1h passes through the quarter-wave plate 1j and becomes circularly polarized light. Blue light (circularly polarized light) that has passed through the quarter-wave plate 1j is irradiated onto the phosphor wheel through the lens 1k.

  By rotating the phosphor wheel, blue light (circularly polarized light) from the lens 1k is sequentially irradiated onto the yellow phosphor region 10Y, the green phosphor region 10G, and the reflection region 10B. In the yellow phosphor region 10Y, the yellow phosphor excited by blue light emits yellow fluorescence. In the green phosphor region 10G, the green phosphor excited by blue light emits green fluorescence. The reflection region 10B reflects the blue light from the lens 1k in the direction of the lens 1k.

  Yellow fluorescent light (non-polarized light) from the yellow fluorescent region 10Y, green fluorescent light (non-polarized light) from the green fluorescent region 10G, and blue light (circularly polarized light) from the reflective region 10B are the lens 1k and quarter wavelength, respectively. The light passes through the plate 1j and the lens 1i sequentially and enters the dichroic mirror 1h. Here, the blue light (circularly polarized light) from the reflection region 10B passes through the quarter-wave plate 1j and becomes P-polarized light. This blue light (P-polarized light) enters the dichroic mirror 1h.

  Yellow fluorescent light (non-polarized light), green fluorescent light (non-polarized light) and blue light (P-polarized light) from the lens 1i are transmitted through the dichroic mirror 1h. The yellow fluorescent light, green fluorescent light, and blue light transmitted through the dichroic mirror 1h are condensed by the lens 1m onto the surface of one end of an optical element (not shown) (for example, a light uniformizing element such as a light tunnel or a rod integrator). The

  The color filter unit 1n includes a color wheel. The color wheel is disposed on the lens 1m side with respect to the focal position of the lens 1m.

  FIG. 5 shows an example of a color wheel. Referring to FIG. 5, the color wheel includes a yellow transmission filter 11Y, a red transmission filter 11R, a green transmission filter 11G, and a diffusion plate 11B. The yellow transmission filter 11Y, the red transmission filter 11R, the green transmission filter 11G, and the diffusion plate 11B are formed to be aligned in the circumferential direction.

  The areas of the yellow transmission filter 11Y and the red transmission filter 11R correspond to the yellow phosphor area 10Y of the phosphor wheel shown in FIG. 4, and the green transmission filter 11G and the diffusion plate 11B are respectively the phosphor wheels shown in FIG. Correspond to the green phosphor region 10G and the reflective region 10B. The ratio of the area of the yellow transmission filter 11Y, the red transmission filter 11R, the green transmission filter 11G, and the diffusion plate 11B in the circumferential direction is the same as the ratio of the corresponding region of the phosphor wheel shown in FIG.

  The ratio of the area of the yellow transmission filter 11Y and the red transmission filter 11R in the circumferential direction depends on the balance of the light intensity of the yellow light, red light, green light, and blue light included in the output light of the light source device 1. It is set appropriately.

  The color filter unit 1n and the phosphor unit 1l are configured to rotate in synchronization with each other. The yellow fluorescence from the yellow phosphor region 10Y includes yellow component light and red component light. The yellow component light is transmitted through the yellow transmission filter 11, and the red component light is transmitted through the red transmission filter 11R.

  Green fluorescence from the green phosphor region 10G passes through the green transmission filter 11G. Blue light from the reflection region 10B passes through the diffusion plate 11B. Blue diffused light is emitted from the diffusion plate 11B. The diffusion angle is, for example, about 10 °, but can be changed as necessary.

  Yellow light, red light, green light, and blue light that have passed through the color filter unit 1 n are output light of the light source device 1.

  According to the light source device of the present embodiment, the inorganic quarter-wave plate 1j having a smaller angle dependency than the quarter-wave plate of quartz is disposed between the lens 1i and the lens 1k, thereby reducing the size of the optical system. And cost reduction can be achieved. The reason will be specifically described below.

  FIG. 6 is a schematic diagram for explaining the relationship between the arrangement position of the quarter-wave plate and the incident region. When the quarter wavelength plate 1j is disposed at the position P1 of the lens 1i on the dichroic mirror 1h side, the size of the region through which the blue light passes through the quarter wavelength plate 1j is 32 mm square. When the quarter wavelength plate 1j is disposed at the position P2 on the lens 1k side of the lens 1i, the size of the region through which the blue light passes through the quarter wavelength plate 1j is 25 mm square. When the quarter wavelength plate 1j is disposed at the position P3 on the phosphor wheel side of the lens 1k, the size of the region through which the blue light passes through the quarter wavelength plate 1j is 20 mm square. Thus, the blue light passage region at position P3 is the smallest, and then the blue light passage region at position P2 is the smallest.

  FIG. 7 shows a ray angle distribution at each position shown in FIG. The vertical axis represents the intensity ratio (%), and the horizontal axis represents the ray angle (deg). The black rhombus mark connected by the solid line is the light angle distribution in the X direction at the position P1. A ray angle distribution in the Y direction at the position P1 is obtained by connecting black square marks with a solid line. A ray angle distribution in the X direction at the position P2 is obtained by connecting black triangle marks with solid lines. A line angle distribution in the Y direction at the position P2 is obtained by connecting the X marks with a solid line. A beam angle distribution in the X direction at the position P3 is obtained by connecting * marks with a solid line. A black circle connected by a solid line is a light ray angle distribution in the Y direction at the position P3.

  The ray angle of the blue light at the position P1 is ± 5 °. The ray angle of the blue light at the position P2 is ± 28 °. The ray angle of the blue light at the position P3 is ± 65 °. The inorganic quarter-wave plate 1j can maintain the characteristics with respect to light having an incident angle of 40 ° or less, and therefore the influence of the angle-dependent characteristics does not occur even when the inorganic quarter-wave plate 1j is disposed at the position P2. In addition, when the quarter wavelength plate 1j is arranged at the position P3, the influence of the angle-dependent characteristics occurs.

  Compared with the configuration in which the quarter-wave plate 1j is disposed at the position P1, according to the configuration in which the quarter-wave plate 1j is disposed at the position P2, the blue light passage region is reduced from 32 mm square to 25 mm square. Therefore, the size of the quarter-wave plate 1j can be reduced, and the cost can be reduced.

  In addition, according to the configuration in which the quarter-wave plate 1j is arranged at the position P2, it is possible to reduce the size and cost of the optical system including the system that condenses the fluorescence. The reason will be specifically described below.

  FIG. 8 schematically shows optical paths of blue light and fluorescence. A broken line indicates a reflected light path of blue light from the reflective region 10B, and a solid line indicates an optical path of yellow fluorescence from the yellow phosphor region 10Y or green fluorescence from the green phosphor region 10G.

  The lenses 1i and 1k are designed to collect the blue light from the dichroic mirror 1h on the irradiation surface of the phosphor wheel, and the fluorescence (completely diffused light) from the yellow phosphor region 10Y and the green phosphor region 10G. ) Is not designed to collect light. For this reason, the blue light from the reflection region 10B is collected by the lenses 1i and 1k, becomes a substantially parallel light beam L1, and passes through the dichroic mirror 1h, but the fluorescence from the yellow phosphor region 10Y and the green phosphor region 10G. (Completely diffused light) is collected by the lenses 1i and 1k, but passes through the dichroic mirror 1h as a divergent light beam L2. That is, the fluorescence from the yellow phosphor region 10Y and the green phosphor region 10G propagates as a divergent light beam L2 between the phosphor wheel and the lens 1m. In this case, the longer the distance from the phosphor wheel is, the larger the beam diameter of the divergent light beam L2 is. Therefore, when the distance from the phosphor wheel to the lens 1m increases, it is necessary to increase the size of the lens 1m. This increases the size and cost of the optical system.

  In addition, when the distance from the phosphor wheel to the lens 1m increases, the distance between the lens 1m and the light tunnel 2a also increases, leading to an increase in the size of the optical system.

  For the above reasons, it is desirable to make the distance from the phosphor wheel to the lens 1 m as short as possible.

  According to this embodiment, by arranging the inorganic quarter-wave plate 1j at the position P2, it is possible to solve the problems of the increase in size and cost of the optical system.

  Specifically, the lenses 1i and 1k are plano-convex lenses, and the convex surfaces are directed to the dichroic mirror 1h side. The dichroic mirror 1h is arranged so that the angle formed by the optical axes of the lenses 1i and 1k is smaller than 45 °. In this case, the distance between the dichroic mirror 1h and the lens 1i can be shortened by arranging the lens 1i so that the outer peripheral portion of the lens 1i and the end of the dichroic mirror 1h located on the lens 1i side are close to each other.

  Further, the quarter wavelength plate 1j can be attached to the lens 1i or directly formed on the lens 1i, and does not require a holder for holding the quarter wavelength plate 1j. Is increased by the thickness of the quarter-wave plate 1j. Since the inorganic quarter-wave plate 1j can be thinned by 0.3 mm or less, an increase in the distance between the lenses 1i and 1k is slight.

  On the other hand, in the configuration in which the quarter wavelength plate 1j is arranged at the position P1, the quarter wavelength plate 1j and the convex surface of the lens 1i are arranged so as not to be buffered, and the quarter wavelength plate 1j and the dichroic mirror 1h are arranged. It is necessary to arrange so that it does not buffer with the edge part. Further, since it is necessary to hold the ¼ wavelength plate 1j with a holder, the dichroic mirror 1h and the 1/0 so that the holder of the ¼ wavelength plate 1j is not buffered with the holder of the lens 1i and the dichroic mirror 1h. It is necessary to set the interval between the 4-wavelength plate 1j and the interval between the lens 1i and the quarter-wave plate 1j. Therefore, the distance between the lens 1i and the dichroic mirror 1h is significantly larger than the configuration in which the quarter wavelength plate 1j is disposed at the position P2.

  As described above, according to the configuration in which the quarter-wave plate 1j is arranged at the position P2, the distance between the lens 1i and the dichroic mirror 1h can be reduced, so that the distance from the phosphor wheel to the lens 1m is shortened. Therefore, it is possible to reduce the size and cost of the optical system.

  According to the light source device of the present embodiment, in addition to the above effects, there are the following effects.

  By disposing the dichroic mirror 1h so that the incident angle θ of the central ray of the blue light from the reflection region 10B is greater than 45 °, the wavelength range in which S-polarized light and P-polarized light can be separated is expanded. For example, the dichroic mirror 1h is arranged so that the incident angle of blue light is 55 °. Thereby, it is possible to suppress the influence of variations in the emission wavelength of the LD due to individual differences and temperature dependency.

  However, the transmittance of the dichroic mirror 1h decreases as the incident angle increases. For this reason, a part of the blue light (P-polarized light) from the reflection region 10B is reflected by the dichroic mirror 1h. If the blue light (P-polarized light) reflected by the dichroic mirror 1h returns to the light source 1a, the oscillation operation of the LD becomes unstable and the output of the LD decreases. In particular, when the reflection region 10B and the light source 1a (LD emission point) are in an imaging relationship, the blue light from the reflection region 10B returns to the light emission point of the light source 1a. It will be a thing.

  In the present embodiment, in order to remove blue light returning from the dichroic mirror 1h to the light source 1a side, the polarization separation element 1f is disposed on the optical path between the dichroic mirror 1h and the light source 1a. Blue light (P-polarized light) reflected by the dichroic mirror 1h passes through the polarization separation element 1f. The blue light (P-polarized light) transmitted through the polarization separation element 1f proceeds in a direction different from the direction of the light source 1a and does not return to the light emitting point of the light source 1a. Therefore, the oscillation operation of the LD does not become unstable.

(projector)
FIG. 9 shows a configuration of a projector including the light source device 1 shown in FIG.

  Referring to FIG. 9, the projector includes a light source device 1, an illumination optical system 2, a projection optical system 3, and a display element 4.

  The illumination optical system 2 guides output light from the light source device 1 to the display element 4 and supplies rectangular and uniform light to the display element 4. The illumination optical system 2 includes a light tunnel 2a, lenses 2b, 2c, and 2e and a mirror 2d.

  The light tunnel 2a has a rectangular parallelepiped shape, and the output light of the light source device 1 enters the inside from one end, and the incident light propagates inside and is emitted from the other end. The surface (incident surface) at one end of the light tunnel 2a is arranged at the focal position of the lens 1m of the light source device 1 shown in FIG. The irradiation surface of the phosphor wheel of the phosphor unit 11 and the incident surface of the light tunnel 2a are in an imaging relationship.

  The light emitted from the other end of the light tunnel 2a is applied to the display element 4 through the lenses 2b, 2c, the mirror 2d, and the lens 2e. The lenses 2b, 2c, and 2e are condensing lenses.

  The display element 4 spatially modulates the light beam from the illumination optical system 2 according to the video signal to form an image. The display element 4 is, for example, a digital micromirror device (DMD). The DMD has a plurality of micromirrors, and each micromirror is configured such that the angle changes according to the drive voltage. When the drive voltage indicating the on state is supplied and the drive voltage indicating the off state The reflection angle differs depending on whether or not is supplied. By controlling on / off of each micromirror according to a video signal, an incident light beam is spatially modulated to form an image. As the display element 4, a liquid crystal panel or the like can be used in addition to the DMD.

  The projection optical system 3 enlarges and projects the image formed on the display element 4 on the projection surface. The projection surface may be anything that can project an image, such as a screen or a wall.

(Second Embodiment)
A light source device according to a second embodiment of the present invention will be described.

  The light source device of the present embodiment is configured such that the relationship between S-polarized light and P-polarized light is reversed in the light source device 1 shown in FIG. Specifically, in FIG. 3, the polarization separation element 1f, the diffusion plate 1g, the dichroic mirror 1h, the lens 1m, and the color filter unit 1n are arranged as they are. The light source 1a, the collimator lens 1b, and the lenses 1c to 1e are arranged on the side opposite to the diffusion plate 1g side of the polarization separation element 1f. The quarter-wave plate 1j, the lenses 1i, 1k, and the phosphor unit 11 are arranged on the opposite side of the dichroic mirror 1h from the polarization separation element 1f side.

  The polarization separation element 1f has characteristics of reflecting S-polarized light and transmitting P-polarized light. The light source 1a is arranged so that the output light enters the polarization separation element 1f as P-polarized light.

  Blue light (P-polarized light) from the light source 1a enters the polarization separation element 1f via the collimator lens 1b and the lenses 1c to 1e. Blue light (P-polarized light) passes through the polarization separation element 1f and enters the dichroic mirror 1h via the diffusion plate 1g.

  The dichroic mirror 1h has a first characteristic of transmitting light having a wavelength equal to or shorter than the wavelength of blue light and reflecting light having a wavelength longer than the first wavelength with respect to light incident as P-polarized light. . The dichroic mirror 1h transmits a second wavelength shorter than the wavelength of the blue light and reflects a light having a wavelength longer than the second wavelength with respect to the light incident as S-polarized light. Has characteristics. Here, the first wavelength is a cutoff wavelength of the first characteristic, and the second wavelength is a cutoff wavelength of the second characteristic. The dichroic mirror 1h having such characteristics can be realized by a dielectric multilayer film.

  Blue light (P-polarized light) from the polarization separation element 1f passes through the dichroic mirror 1h, and is irradiated to the phosphor unit 11 through the lenses 1i and 1k and the quarter wavelength plate 1j. Blue light (P-polarized light) becomes circularly polarized light after passing through the quarter-wave plate 1j. Blue light (circularly polarized light) is sequentially irradiated onto the yellow phosphor region 10Y, the green phosphor region 10G, and the reflection region 10B.

  In the yellow phosphor region 10Y, the yellow phosphor excited by blue light emits yellow fluorescence. In the green phosphor region 10G, the green phosphor excited by blue light emits green fluorescence. The reflection region 10B reflects the blue light from the lens 1k in the direction of the lens 1k.

  Yellow fluorescent light (non-polarized light) from the yellow fluorescent region 10Y, green fluorescent light (non-polarized light) from the green fluorescent region 10G, and blue light (circularly polarized light) from the reflective region 10B are the lens 1k and quarter wavelength, respectively. The light passes through the plate 1j and the lens 1i sequentially and enters the dichroic mirror 1h. Here, the blue light (circularly polarized light) from the reflection region 10B passes through the quarter-wave plate 1j and becomes S-polarized light. This blue light (S-polarized light) enters the dichroic mirror 1h.

  Yellow fluorescent light (non-polarized light), green fluorescent light (non-polarized light) and blue light (P-polarized light) that have passed through the quarter-wave plate 1j are reflected by the dichroic mirror 1h. Yellow fluorescent light, green fluorescent light, and blue light reflected by the dichroic mirror 1h enter the color hole of the color filter unit 1n through the lens 1m.

  Also in the present embodiment, as in the first embodiment, the quarter wave plate 1j is made of an inorganic material and is disposed between the lens 1i and the lens 1k. Thereby, the same effect as 1st Embodiment is acquired.

  Also in the present embodiment, the modifications described in the first embodiment can be applied. Further, the light source device of the present embodiment can be applied to the projector shown in FIG. Specifically, in the projector shown in FIG. 9, the light source device 1 is replaced with the light source device of the present embodiment.

(Third embodiment)
FIG. 10 shows a configuration of a projector including a light source device according to the third embodiment of the present invention.

  The light source device 10 is the light source device of this embodiment. In the light source device 10, the polarization separating element 1f is arranged so that the incident angle of the central light beam of blue light from the light source 1a is 45 °, and the dichroic mirror 1h is incident of the central light beam of blue light from the reflection region 10B. It arrange | positions so that an angle | corner may be 45 degrees. The other configuration is the same as that of the light source device of the first embodiment.

  The quarter-wave plate 1j is the same as that described in the first embodiment. Also in this embodiment, the quarter wavelength plate 1j is disposed between the lens 1i and the lens 1k. Thereby, the same effect as 1st Embodiment is acquired.

  When the condenser lens group is composed of three or more lenses, the quarter wavelength plate 1j is disposed between any one of the condenser lens groups. However, between the lenses on which the quarter-wave plate 1j is arranged, a condition that the incident angle of blue light to the quarter-wave plate 1j is an angle that does not affect the angle dependency of the quarter-wave plate 1j. Meet.

  The projector shown in FIG. 10 includes a light source device 10, an illumination optical system 2, a projection optical system 3, and a display element 4. The illumination optical system 2, the projection optical system 3, and the display element 4 are the same as those of the projector described in the first embodiment. Also in this projector, an image is enlarged and projected by the same operation as the projector described in the first embodiment.

  Also in the present embodiment, the modifications described in the first embodiment can be applied.

(Fourth embodiment)
A light source device according to a fourth embodiment of the present invention will be described.

  The light source device of this embodiment is configured such that the relationship between S-polarized light and P-polarized light is reversed in the light source device 10 shown in FIG. Specifically, in FIG. 10, the polarization separating element 1f, the diffusion plate 1g, the dichroic mirror 1h, the lens 1m, and the color filter unit 1n are arranged as they are. The light source 1a, the collimator lens 1b, and the lenses 1c to 1e are arranged on the side opposite to the diffusion plate 1g side of the polarization separation element 1f. The quarter-wave plate 1j, the lenses 1i, 1k, and the phosphor unit 11 are arranged on the opposite side of the dichroic mirror 1h from the polarization separation element 1f side.

  The operation of the light source device of this embodiment is the same as that of the light source device of the second embodiment. In the projector including the light source device of the present embodiment, the image is enlarged and projected by the same operation as that of the projector including the light source device of the second embodiment.

  Also in the present embodiment, the modifications described in the first embodiment can be applied.

  The light source device and projector of each embodiment described above are examples of the present invention, and the configuration and operation thereof can be changed as appropriate.

  For example, in the first embodiment, the color filter unit 1n is deleted, and in the phosphor wheel of the phosphor unit 1l shown in FIG. 4, a diffusion layer is provided on the reflection region 10B, and a part of the yellow phosphor region 10Y. Alternatively, the whole may be replaced with a red phosphor region. This modification can also be applied to the second to fourth embodiments.

  In the first embodiment, the light source device 1 may include a part or all of the illumination optical system 2. This modification can also be applied to the second to fourth embodiments.

  In each embodiment, the inorganic quarter-wave plate may be an inorganic birefringent multilayer film formed on a glass or quartz substrate by a vapor deposition technique, or an inorganic birefringent multilayer film. May be formed directly on the lens by a vapor deposition technique.

Moreover, although this invention can take a form like the following additional remarks 1-7, it is not limited to these forms.
[Appendix 1]
A light source that outputs excitation light;
A dichroic mirror that reflects or transmits the first linearly polarized light from the light source;
A first condenser lens group having a plurality of lenses and condensing the reflected light or transmitted light from the dichroic mirror;
A fluorescent light that includes a fluorescent region provided with a fluorescent material and a reflective region that reflects incident light, and is movable so that light from the first condenser lens group is sequentially irradiated onto the fluorescent region and the reflective region. A body unit,
A quarter wave plate provided between two adjacent lenses of the plurality of lenses,
Each of the first condenser lens group and the phosphor unit is configured such that the fluorescence emitted from the phosphor region and the reflected light from the reflection region pass through the first condenser lens group and the quarter wavelength plate. A light source device disposed so as to be incident on the dichroic mirror.
[Appendix 2]
The quarter-wave plate is disposed between a first lens disposed on the dichroic mirror side and a second lens adjacent to the first lens among the plurality of lenses. The light source device according to attachment 1.
[Appendix 3]
The wavelength of the light source is λ, and the quarter-wave plate is composed of an inorganic birefringent multilayer film configured to give a phase difference of ¼λ to the polarization plane of incident light. The light source device according to 1.
[Appendix 4]
A second condenser lens group comprising a plurality of lenses for condensing the output light of the light source;
The light source device according to any one of appendices 1 to 3, wherein the first and second condenser lens groups form a light source image of the light source on a surface including the phosphor region and the reflection region.
[Appendix 5]
Fluorescence emitted from the phosphor region and reflected light from the reflection region are provided so as to enter via the first condenser lens group, a quarter-wave plate, and a dichroic mirror, and the incident light is The light source device according to any one of appendices 1 to 4, further comprising a condensing lens for condensing light.
[Appendix 6]
A color that has a yellow transmission filter, a red transmission filter, a green transmission filter, and a diffusion region, and is movable so that light from the condensing lens sequentially enters the yellow transmission filter, the red transmission filter, the green transmission filter, and the diffusion region. A filter unit,
The phosphor region has a yellow phosphor region provided with a phosphor emitting yellow fluorescence, and a green phosphor region provided with a phosphor emitting green fluorescence,
The yellow fluorescence from the yellow phosphor region is sequentially incident on the yellow transmission filter and the red transmission filter, the green fluorescence from the green phosphor region is incident on the green transmission filter, and the blue light from the reflection region is The light source device according to appendix 5, which is incident on the diffusion region.
[Appendix 7]
The light source device according to any one of appendices 1 to 6,
A display element that spatially modulates the light output from the light source device to form an image;
A projector optical system for enlarging and projecting an image formed by the display element;

Claims (7)

A light source that outputs excitation light;
A dichroic mirror that reflects or transmits the first linearly polarized light from the light source;
A first condenser lens group having a plurality of lenses and condensing the reflected light or transmitted light from the dichroic mirror;
A fluorescent light that includes a fluorescent region provided with a fluorescent material and a reflective region that reflects incident light, and is movable so that light from the first condenser lens group is sequentially irradiated onto the fluorescent region and the reflective region. A body unit,
A quarter wave plate provided between two adjacent lenses of the plurality of lenses,
Each of the first condenser lens group and the phosphor unit is configured such that the fluorescence emitted from the phosphor region and the reflected light from the reflection region pass through the first condenser lens group and the quarter wavelength plate. A light source device disposed so as to be incident on the dichroic mirror.   The quarter-wave plate is disposed between a first lens disposed on the dichroic mirror side and a second lens adjacent to the first lens among the plurality of lenses. The light source device according to claim 1.   The wavelength of the light source is λ, and the quarter-wave plate is formed of an inorganic birefringent multilayer film configured to give a phase difference of ¼λ to a polarization plane of incident light. 2. The light source device according to 2. A second condenser lens group comprising a plurality of lenses for condensing the output light of the light source;
4. The light source device according to claim 1, wherein the first and second condenser lens groups form a light source image of the light source on a surface including the phosphor region and a reflection region. 5. .   Fluorescence emitted from the phosphor region and reflected light from the reflection region are provided so as to enter via the first condenser lens group, a quarter-wave plate, and a dichroic mirror, and the incident light is The light source device according to claim 1, further comprising a condensing lens for condensing light. A color that has a yellow transmission filter, a red transmission filter, a green transmission filter, and a diffusion region, and is movable so that light from the condensing lens sequentially enters the yellow transmission filter, the red transmission filter, the green transmission filter, and the diffusion region. A filter unit,
The phosphor region has a yellow phosphor region provided with a phosphor emitting yellow fluorescence, and a green phosphor region provided with a phosphor emitting green fluorescence,
The yellow fluorescence from the yellow phosphor region is sequentially incident on the yellow transmission filter and the red transmission filter, the green fluorescence from the green phosphor region is incident on the green transmission filter, and the blue light from the reflection region is The light source device according to claim 5, wherein the light source device is incident on the diffusion region. The light source device according to any one of claims 1 to 6,
A display element that spatially modulates the light output from the light source device to form an image;
A projector optical system for enlarging and projecting an image formed by the display element;

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