JP6072177B2 - Optical unit, optical device, light source device using the same, and projection display device - Google Patents

Description

  The present invention relates to an optical unit, an optical device using the optical unit, a light source device, and a projection display device. In particular, the present invention relates to a light source device using a solid light source such as a semiconductor laser as a light source.

  In recent years, a projector has been developed that irradiates a phosphor with a light beam emitted from a high-power laser diode (hereinafter referred to as an LD) as excitation light and uses wavelength-converted fluorescent light.

  In order to achieve high luminance with such a projector, it is conceivable to use a large number of LDs in an array. However, the light output of the LD decreases as the temperature rises. Therefore, if the LDs are closely arranged in order to prioritize the miniaturization of the projector, the light output of the LD decreases because the LDs heat each other. This will impair the brightness of the projected image.

  For this reason, when LDs are arranged, it is necessary to reduce the mutual thermal action as much as possible by widening the arrangement interval. However, if the arrangement interval is widened, the luminous flux emitted from the LD group becomes thick, and the subsequent optical element is also enlarged, which is not preferable in terms of cost and weight.

  In view of such a background, Patent Documents 1 and 2 disclose techniques aiming at making the luminous flux emitted from the LD group as thin as possible.

  Japanese Patent Application Laid-Open No. 2005-228561 discloses a technique for condensing on a phosphor by providing a plurality of plane mirrors in the traveling direction of light beams from a plurality of LDs and adjusting the angles of the plurality of plane mirrors.

  Patent Document 2 discloses a technique in which one parabolic mirror is provided in the traveling direction of light beams from a plurality of LDs, and the light beam from the parabolic mirrors is reflected by the mirror and condensed on the phosphor. Has been.

JP 2011-65770 A JP 2014-82144 A

  By using the techniques disclosed in Patent Documents 1 and 2 described above, it is possible to suppress the increase in size of the optical element described above.

  However, in the configuration described in Patent Document 1, since the reflecting surfaces of the plurality of mirrors are flat, it is difficult to collect the parallel light flux reflected by the plurality of mirrors in a small region on the phosphor.

  If the condensing spot on the phosphor is large, the parallelism when entering the optical system at the subsequent stage is lowered, and there is a possibility that the light utilization efficiency is lowered.

  In the configuration described in Patent Document 2, since the parabolic mirror is used, the light utilization efficiency described above is obtained by converging the convergent light beam from the parabolic mirror onto a small area on the phosphor. Can be suppressed.

  However, when the number of LDs is increased in order to achieve higher brightness with the configuration described in Patent Document 2, the area and depth of the parabolic mirror increase as the number of LDs increases, and the light source device increases in size. There is a risk that.

  Accordingly, an object of the present invention is to provide an optical device capable of realizing a smaller light source device while suppressing a decrease in light utilization efficiency, a light source device using the optical device, and a projection display device.

In order to achieve the above object, the optical device of the present invention comprises:
An optical unit comprising a plurality of reflecting surfaces for reflecting light beams from a plurality of light sources ;
A lens unit;
A mirror unit that guides light beams from the plurality of reflecting surfaces to the lens unit,
The plurality of reflecting surfaces are configured such that the light beams reflected by the plurality of reflecting surfaces are a plurality of convergent light beams, and the distance between the plurality of convergent light beams decreases as the distance from the plurality of reflecting surfaces increases. ,
The plurality of reflecting surfaces are a plurality of concave mirrors,
The plurality of concave mirrors include a first concave mirror and a second concave mirror provided at a position farther from the lens unit than the first concave mirror,
The focal length of the second concave mirror is longer than the focal length of the first concave mirror,
Said first concave mirror and the second concave mirror Ri part der plurality of concave respective different shapes,
In the optical axis direction of the lens unit, the mirror unit is provided between the second concave mirror and the lens unit.
It is characterized by that.

  ADVANTAGE OF THE INVENTION According to this invention, the optical device which can implement | achieve a more compact light source device, suppressing the fall of the utilization efficiency of light, a light source device using the same, and a projection type display apparatus can be provided.

Structure explanatory drawing of the projection type display apparatus which mounts the optical apparatus and light source device which are shown in the Example of this invention Structure explanatory drawing of the light source device shown in the embodiment of the present invention Explanatory drawing of the parabolic mirror array used in the Example of this invention Image of paraboloid mirror array used in an embodiment of the present invention Explanatory drawing of the relationship between the paraboloid mirror array focus used in the Example of this invention, and a concave lens focus.

  Preferred embodiments of the present invention will be illustratively described below with reference to the drawings. However, the shape and relative arrangement of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions. In other words, the shape and relative position of the component parts are not stipulated in order to limit the scope of the present invention to the following embodiments.

[Description of Configuration of Projection Display Device]
First, the configuration of a projector 1000 equipped with the optical device shown in the embodiment of the present invention will be described with reference to FIG.

  The projector (projection display device) 1000 includes a light source device 100, an illumination optical system 200, a color separation / synthesis system 300, and a projection lens 400. Thereby, the projector 1000 can project an image on the screen 500.

  The light source device 100 includes a plurality of LDs (light sources) 1, a plurality of collimator lenses (positive lenses) 2 into which a plurality of light beams from the plurality of LDs 1 are incident, and an optical device 10. The light source device 100 further includes a dichroic mirror 12, a condenser lens unit 20, and a phosphor (wavelength conversion element) 13.

  The light source device 100 further includes a motor (drive means) 14 for rotating the phosphor 13 and a base 15 that supports the motor 14.

  The LD 1 emits blue light, and the collimator lens 2 converts the divergent light beam from the LD 1 into a parallel light beam. In FIG. 1, only a part of the plurality of LDs 1 and the plurality of collimator lenses 2 shown in FIGS.

  The phosphor 13 converts a part of the light beam from the optical device 10 into fluorescent light (converted light) having a wavelength different from that of the light beam from the optical device 10, and has the same wavelength as the fluorescent light and the light beam from the optical device 10. Unconverted light is emitted.

  In this embodiment, the fluorescent light is a green and red light beam, and the non-converted light is a blue light beam.

  The dichroic mirror 12 reflects the blue light beam compressed into a thin parallel light beam by the optical device 10 described later, and guides the blue light beam to the phosphor 3 via the condenser lens unit 20.

  In the embodiment of the present invention, the condenser lens unit 20 includes three condenser lenses 20A, 20B, and 20C.

  Further, the dichroic mirror 12 reflects non-converted light among fluorescent light and non-converted light traveling from the phosphor 13 via the condenser lens unit 20. On the other hand, the fluorescent light passes through the dichroic mirror 12 and is guided to the illumination optical system 200 described later. Of the non-converted light from the phosphor 13, non-converted light that does not enter the dichroic mirror 12 is guided to the illumination optical system 200 described later.

  Thus, in this embodiment, it is possible to guide fluorescent light including unconverted light that is blue and green and red light beams to the illumination optical system 200 described later.

  The optical device 10 is an optical device shown in the embodiment of the present invention, and its configuration is as described later.

  The illumination optical system 200 guides the light beam from the light source device 100 to a color separation / synthesis system 300 described later.

  The light beam emitted from the light source device 100 is split by the first fly eye lens 41 and the second fly eye lens 42. Further, the light beam emitted from the light source device 100 is converted into S-polarized light by the polarization conversion element 43. Here, the S-polarized light is a light beam linearly polarized in the direction perpendicular to the paper surface.

  The light beam emitted from the polarization conversion element 43 is condensed by the condenser lens unit 44 so as to illuminate a liquid crystal panel 58 (58R, 58G, 58B) described later in a superimposed manner.

  In the embodiment of the present invention, the condenser lens unit 44 is configured to include three condenser lenses 44A, 44B, and 44C.

  The color separation / synthesis system 300 decomposes the light flux from the illumination optical system 200 for each wavelength, synthesizes image light to be displayed on the screen, and guides the image light to a projection lens 400 described later.

  The dichroic mirror 50 has characteristics of reflecting red light (R light) and blue light (B light) and transmitting green light (G light). The R light and B light reflected by the dichroic mirror 50 enter the wavelength selective phase plate 54. The wavelength-selective phase plate 54 has a characteristic that gives a phase difference of half wavelength to the B light and does not give a phase difference to the R light. Therefore, the B light incident on the wavelength selective phase plate 54 becomes P-polarized light, and the R light becomes S-polarized light and enters a PBS (polarized beam splitter) 53 described later. The P-polarized light is a light beam linearly polarized in the horizontal direction on the paper.

  Since the PBS 53 has characteristics of transmitting P-polarized light and reflecting S-polarized light, the B light passes through the PBS 53 and enters the liquid crystal panel 58B, and the R light is reflected by the PBS 53 and enters the liquid crystal panel 58R. .

  On the other hand, the G light transmitted through the dichroic mirror 50 passes through the dummy glass 56 for correcting the optical path length and enters the PBS 51. Since the PBS 51 has characteristics of transmitting P-polarized light and reflecting S-polarized light, the G light is reflected by the PBS 51 and enters the liquid crystal panel 58G.

  The above is the description until the light flux from the light source device 100 enters the liquid crystal panel 58. Next, a process until image light is emitted from the liquid crystal panel 58 and an image is projected onto the screen 500 will be described. Here, the image light is a light beam for displaying an image to be projected on the screen 500.

  The light beam incident on the liquid crystal panel (light modulation element) 58 is given a phase difference so as to become a light beam having a desired polarization direction according to the modulation state of the pixels arranged on the liquid crystal panel 58. Among the light beams to which the phase difference is given, the component having the same polarization direction as the light beam from the light source device 100 returns to the light source device 100 side and is excluded from the image light. On the other hand, components having a 90-degree polarization direction different from the light flux from the light source device 100 are guided to the combining prism 32.

  When the R light from the light source device 100 is converted from the S-polarized light to the P-polarized light by the R light liquid crystal panel 58R, the R light of the P-polarized light passes through the PBS 53 and enters the wavelength selective phase plate 55. To do. The wavelength selective phase plate 55 has a characteristic that does not give a phase difference to the B light and gives a phase difference corresponding to a half wavelength to the R light. For this reason, the R light transmitted through the wavelength selective phase plate 55 enters the combining prism 52 as S-polarized light.

  When the B light from the light source device 100 is converted from P-polarized light to S-polarized light by the B light liquid crystal panel 58 </ b> B, the S-polarized light is reflected by the PBS 53 and passes through the wavelength selective phase plate 55. Since the wavelength selective phase plate 55 does not give a phase difference to the B light, the S-polarized B light is incident on the combining prism 52.

  When the G light from the light source device 100 is converted from S-polarized light to P-polarized light by the G light liquid crystal panel 58G, the P-polarized light is transmitted through the PBS 51 and applied to the dummy glass 57 for correcting the optical path length. Incident. The G light transmitted through the dummy glass 57 enters the combining prism 52.

  Since the combining prism 52 has characteristics of transmitting P-polarized light and reflecting S-polarized light, when the above modulation is performed, the G light is transmitted through the combining prism 52, and the B light and the R light are transmitted by the combining prism 52. The light is reflected and guided to the projection lens 400. As a result, a color image can be projected onto the screen 500 via the projection lens 400.

[First embodiment]
The configuration of the light source device equipped with the optical device shown in the first embodiment of the present invention will be described with reference to FIGS.

  FIG. 2 is a diagram showing a configuration of a light source device on which the optical device shown in this embodiment is mounted. 2A is a projection view onto the YZ section, and FIG. 2B is a projection view onto the XZ section.

  2 to 5, the direction parallel to the optical axis of the later-described concave lens 5 is defined as the Y-axis direction, the direction orthogonal to the Y-axis and the direction parallel to the long side direction of the reflecting surface of the later-described flat mirror 4 is illustrated. The direction is the X-axis direction, and the direction orthogonal to the Y-axis direction and the Z-axis direction is the X-axis direction.

  The optical device 10 includes a plurality of parabolic mirrors (reflection surfaces) 3. The optical device 10 further includes a concave lens (lens unit) 5 and a mirror unit 40.

  The light source device 100 includes a plurality of LDs 1 and a plurality of collimator lenses 2 in addition to the optical device 10 described above, and emits a compressed parallel light beam from the concave lens 5. In this embodiment, the plurality of parabolic mirrors 3 are referred to as a parabolic mirror array (optical unit) 30, and the plurality of plane mirrors 4 are referred to as a mirror unit 40. Instead of the mirror unit 40, a prism having a plurality of reflecting surfaces may be used. Similar to the mirror unit 40, this prism is configured to guide the light beam from the parabolic mirror array 30 to the concave lens 5.

  First, a description will be given of how the light beams from the plurality of LDs 1 travel toward the parabolic mirror array 30 via the collimator lens 2.

  As described above, the light beam emitted from the LD 1 is a divergent light beam, and if it is left as it is, the subsequent optical element is enlarged. Therefore, the collimator lens 2 is provided immediately after the light beam from the LD 1 is emitted, and the collimator lens 2 makes the divergent light beam from the LD 1 a parallel light beam, thereby suppressing the increase in the size of the optical element described above. .

  Note that the light beam from the collimator lens 2 is not necessarily a completely parallel light beam, and may be slightly diverged or slightly converged within a range that can be used.

  Further, in this embodiment, as shown in FIGS. 2A and 2B, a total of 24 LD groups of 6 rows in the X-axis direction and 4 columns in the Z-axis direction sandwich the concave lens 5. Two groups are provided symmetrically. That is, the number of LD1 is 48.

  Next, the process until the light beam from the collimator lens 2 travels toward the plane mirror 4 via the parabolic mirror array 30 will be described.

  3A and 3B are diagrams for explaining the function of the parabolic mirror array 30. FIG. 3A is a projection onto the YZ section, and FIG. 3B is a projection onto the XZ section. (C) is a projection view on an XY cross section.

  Note that FIG. 3 omits the mirror unit 40 and the concave lens 5 described above and does not illustrate the function of the parabolic mirror array 30. In FIG. 3, only one of the two parabolic mirror arrays 30 is shown.

  As shown in FIG. 3A, the parabolic mirror array 30 converts the parallel light flux from the plurality of collimator lenses 2 into a convergent light flux, and the convergent light flux from the parabolic mirror array 30 is collected at the focal point F. You can see that

  That is, the plurality of parabolic mirrors 3 convert the plurality of parallel light beams from the plurality of LDs 1 into a plurality of convergent light beams, and reduce the distance between the plurality of convergent light beams as they move away from the plurality of parabolic mirrors 3. A plurality of parallel light beams from the plurality of LDs 1 are reflected.

  In other words, the central rays of the plurality of light fluxes from the plurality of LDs 1 travel while reducing the mutual distance toward the concave lens 5 via the plurality of parabolic mirrors 3.

  In other words, a plurality of light beams passing through the optical axes of the plurality of collimator lenses 2 travel through the plurality of parabolic mirrors 3 while decreasing the distance from each other toward the concave lens 5. Further, as shown in FIG. 3A, the parabolic mirror array 30 has a focal point F on which the parabolic mirror 3 converges on the side opposite to the LD1 and the collimator lens 2 with respect to the parabolic mirror array 30 ( It is preferable that the Y direction is positioned in a positive direction. As a result, the light flux from the parabolic mirror 3 is reduced compared to the case where the focal point F is located on the same side as the LD 1 and the collimator lens 2 (negative direction in the Y direction) with respect to the parabolic mirror array. It can be made thinner. In other words, the cross section of the convergent light beam emitted from the parabolic mirror 3 can be further reduced. As a result, the width of the light beam from the concave lens 5 becomes narrower, and the subsequent optical system can be made smaller.

  In other words, the parabolic mirror 3 has an angle of 45 degrees between the normal line at the position where the principal ray of the light beam from the light source and the parabolic mirror 3 intersect with the principal ray of the light beam from the light source. It is comprised so that it may become the above. In other words, the angle formed between the center line of the cone circumscribing the plurality of convergent light beams from the plurality of parabolic mirrors 3 and the principal ray of the light beam from the light source is 90 degrees or more. It is comprised so that it may become.

  Note that it is not necessary that all the parabolic mirrors 3 are configured as described above. It is preferable that at least one of the plurality of parabolic mirrors 3 has the above-described configuration, and more preferably, at least half of the plurality of parabolic mirrors 3 has the above-described configuration. That is, at least one parabolic mirror 3 among the plurality of parabolic mirrors 3 is configured such that the light beam from the parabolic mirror 3 is light of the concave lens 5 with respect to the concave lens 5 as the parabolic mirror 3 moves away from the parabolic mirror 3. It is preferable to be configured to approach the axial direction.

  The paraboloidal mirror 3 has a common focal point F as a paraboloid, but the positions where the plurality of parabolic mirrors 3 are provided are different from each other. For this reason, the plurality of paraboloid mirrors 3 have different shapes, and the light beams from the plurality of paraboloid mirrors 3 can be condensed at the focal point F by making the shapes different.

  More specifically, as shown in FIG. 3A, the parabolic mirror 3 a closest to the optical axis of the concave lens 5 and the optical axis of the concave lens 5 among the plurality of parabolic mirrors 3 in the YZ cross section. The shape is compared with the parabolic mirror 3b far from the center. Comparing both shapes, it can be seen that the parabola vertex position and the paraxial radius of curvature are different.

  That is, the apex positions of the parabolic mirror 3a and the parabolic mirror 3b are different from each other, but the focal positions are the same at the focal point F.

  In the YZ section, the parabolic mirror 3a and the parabolic mirror 3b are provided at different positions. However, the focal lengths of the parabolic mirror 3a and the parabolic mirror 3b are different from each other so that the focal positions of both the parabolic mirror 3a and the parabolic mirror 3b are the same at the focal point F. Yes.

  More specifically, the paraboloidal mirror array 30 is configured such that the focal length becomes longer as the parabolic mirror 3 provided at a position away from the optical axis of the concave lens 5.

  In other words, the parabolic mirror array 30 includes a parabolic mirror 3b (first concave mirror) and a parabolic mirror 3a (second concave mirror) that is further away from the lens unit than the parabolic mirror 3a. And the focal length of the parabolic mirror 3a is also long that of the parabolic mirror 3b.

  If the plurality of paraboloid mirrors 3 are all part of the same shape of paraboloid, it is difficult to condense a plurality of convergent light beams from the plurality of paraboloid mirrors 3 at one point.

  Further, when the plurality of paraboloid mirrors 3 are all part of the same shape of paraboloid, the paraboloid surface is used to collect the plurality of convergent light beams from the plurality of paraboloid mirrors 3 at one point. When the position of the mirror 3 is adjusted and a plurality of parabolic mirrors 3 are connected, a parabolic surface having a continuous shape is obtained. With such a configuration, the parabolic mirror array 30 may be increased in size as compared with the configuration shown in the present embodiment.

  Further, when the parabolic mirror array 30 is increased in size, the light flux from the parabolic mirror array 30 is increased, so that the mirror unit 40 and the concave lens 5 may be increased in size.

  Let us consider a configuration in which a parabolic mirror having a continuous shape is used without increasing the size of the mirror unit and the concave lens. In such a configuration, when the parabolic mirrors are provided on the left and right with the optical axis of the concave lens as the axis of symmetry as in this embodiment, the interval between the left and right paraboloid mirrors is greater than the configuration shown in the present embodiment. Need to be larger. For this reason, there exists a possibility that it may enlarge as a whole light source device.

  Further, when only one parabolic mirror is provided, it is necessary to provide the mirror unit and the concave lens at a position away from the parabolic mirror, as compared with the configuration shown in the present embodiment. For this reason, in this case, the entire light source device may be increased in size.

  That is, as in the present embodiment, the plurality of parabolic mirrors 3 are part of paraboloids having different shapes, and the parabolic mirror 3 that is separated from the concave lens 5 among the plurality of parabolic mirrors 3. As the focal length is longer, the above-described increase in size can be suppressed.

  The plurality of parabolic mirrors 3 having different shapes indicates that the focal lengths of the plurality of parabolic mirrors 3 are different from each other.

  Furthermore, the parabolic mirror 3 that is farther from the concave lens 5 among the plurality of parabolic mirrors 3 has a longer focal length. In other words, the paraboloid that is close to the plurality of LDs 1 among the plurality of parabolic mirrors 3. It indicates that the focal length of the plane mirror 3 is longer.

  In addition, being away from the concave lens 5 indicates that the optical path length from the parabolic mirror 3 to the concave lens 5 is long, that the optical path is provided at a position away from the concave lens 5, or that both are satisfied.

  Furthermore, according to the parabolic mirror array 30 shown in the present embodiment, a plurality of convergent light beams from the plurality of parabolic mirrors 3 can be collected at one point, and the parallelism of the light beams emitted from the phosphors Can be increased.

  Here, a surface including the optical axis of the concave lens 5 and the long side direction of the mirror unit 40 is defined as a first cross section, and a surface orthogonal to the first cross section and including the optical axis of the concave lens 5 is defined as a second cross section. At this time, among the plurality of parabolic mirrors 3, the parabolic mirrors 3 (reflecting surfaces) provided symmetrically with respect to the first cross section or the second cross section are symmetrical parabolic shapes. Is part of. In this embodiment, the first cross section is an XY cross section, and the second cross section is a YZ cross section.

  In other words, among the plurality of parabolic mirrors 3, the parabolic mirrors 3 positioned at the same distance from the optical axis of the concave lens 5 in the XZ cross section are part of the same parabolic shape. By configuring the parabolic mirror array 30 in this manner, as shown in FIG. 2A, even if the parabolic mirror array 30 is provided on the left and right with the optical axis of the concave lens 5 as the axis of symmetry. The plurality of convergent light beams from the parabolic mirror array 30 can be collected at one point.

  Further, as shown in FIG. 4, the parabolic mirror array 30 is configured as one optical element. Specifically, the base member 6 has a plurality of parabolic mirrors 3 provided discontinuously. In other words, a plurality of paraboloidal mirrors 3 are provided on the base member 6 at predetermined intervals. Note that the interval between the parabolic mirrors 3 is matched to the arrangement interval of the LDs 1.

  The parabolic mirror array 30 which is an optical element shown in FIG. 4 may be formed by molding a glass material, or may be formed by cutting or molding a metal part.

  Further, if the plurality of parabolic mirrors 3 are part of paraboloids having different shapes, the plurality of parabolic mirrors 3 may be formed discontinuously as shown in FIG.

  Here, when manufacturing the parabolic mirror array 30 by glass molding using a mold, in order to suppress the occurrence of sagging when the parabolic mirror array 30 is removed from the mold, a parabolic mirror is used. It is desirable that the array 30 has less irregularities. That is, it is desirable that the distance in the Y-axis direction from the base member 6 to the end point of the parabolic mirror 3 is short.

  For this reason, it is desirable to fill the gaps between the plurality of parabolic mirrors 3 with a glass material or a metal material having a smooth curved surface such as a spline curved surface passing through the end points of the parabolic mirror 3. Thereby, the unevenness | corrugation of the surface of the parabolic mirror array 30 can be decreased, and the drooping at the time of the above-mentioned shaping | molding can be suppressed.

  Note that the base member 6 does not have to be flat, and may be curved, for example.

  In addition, the parabolic mirror 3 is not provided on the base member 6, but is a stepped parabolic mirror array having a constant thickness and a plurality of reflecting surfaces, for example, by press-molding a flat metal plate. May be. Although the reflective surface of the parabolic mirror 3 is coated, the coating may be a metal reflective film such as aluminum or silver or a dielectric multilayer film. In the case of a dielectric multilayer film, the use efficiency of light can be further increased by using the dielectric multilayer film having the maximum reflectance at the wavelength of the light beam from the LD 1.

  Here, in general, the LD emits linearly polarized light. However, by arranging a plurality of LD1 so that the polarization direction of the light beam from the LD1 is in the X-axis direction, the parabolic mirror 3 in the YZ cross section is arranged. The reflectance is increased, and the light utilization efficiency can be further increased.

  As shown in FIG. 2A, in the YZ section, in order to allow all of the plurality of light beams from the plurality of LDs 1 arranged in the Z-axis direction to enter the mirror unit 40, the YZ section is compared with other sections. Therefore, it is necessary to reflect the light beams from the plurality of LDs 1 at a steeper angle.

  For this reason, it is desirable to increase the reflectance at the parabolic mirror 3 in the YZ section by arranging a plurality of LDs 1 so that the polarization direction of the light beam from the LD 1 is the X-axis direction.

  Further, the incident angle of the light beam from the LD 1 on each parabolic mirror 3 is different for each of the parabolic mirrors 3. As will be described later, the parabolic mirror 3 that guides the light beam incident on the position away from the optical axis of the concave lens 5 to the mirror unit 40 is formed by the optical axis of the concave lens 5 and the parabolic mirror 3. This is because the parabolic mirror array 30 is configured so that the angle becomes small.

  Therefore, by adjusting the coating of each parabolic mirror 3 so that the reflectance is maximized at the incident angle of the light beam from the LD 1 to each parabolic mirror 3, the use efficiency of light can be further improved. It becomes possible.

  However, the present invention is not limited to the configuration in which the coating of the parabolic mirror 3 is adjusted for each of the plurality of parabolic mirrors 3. Good.

  In such a configuration, a coating having a range of incident angles at which the reflectivity is maximized is preferable instead of a coating having a maximum reflectivity at a predetermined incident angle.

  The incident angle of the light beam from the LD 1 to each parabolic mirror 3 is a method at a position where a light beam passing through the optical axis of the collimator lens 2 is incident on the parabolic mirror 3. The angle between the line and the incident ray.

  The angle formed by the optical axis of the concave lens 5 and the parabolic mirror 3 may be an angle formed by a line segment connecting the end points of the parabolic mirror 3 and the optical axis of the concave lens 5. Further, an angle formed between a tangent line at a position where a light beam passing through the optical axis of the collimator lens 2 of the light beam from the LD 1 is incident on the parabolic mirror 3 and the optical axis of the concave lens 5 may be used.

  In this embodiment, the plurality of LDs 1 are all LDs that emit blue light, but the present invention is not limited to this.

  For example, the plurality of LDs 1 may include an LD that emits blue light, an LD that emits red light, and an LD that emits green light. Further, the plurality of LDs 1 may be configured by an LD that emits blue light and an LD that emits red light.

  Thus, when the plurality of LDs 1 are configured to include a plurality of LDs having different wavelengths, the coating of the plurality of parabolic mirrors 3 may be made different according to the wavelength from the LD. Furthermore, when the plurality of LDs 1 are configured to include LDs that emit blue light, red light, and green light, the dichroic mirror 12 and the phosphor 13 described above may not be provided.

  Next, a description is given of the process until the light beam from the mirror unit 40 goes to the subsequent system via the concave lens 5.

  A plurality of convergent light beams from the parabolic mirror array 30 are reflected by the mirror unit 40 and enter the concave lens 5.

  The concave lens 5 is a meniscus lens having negative power and having a convex side on which light beams from a plurality of LDs 1 are incident.

  As described above, the plurality of convergent light beams from the parabolic mirror array 30 are condensed on the common focal point F as shown in FIG.

  Further, in this embodiment, as shown in FIG. 5, when the focal point of the concave lens 5 is F ′, a plurality of convergent light beams from the mirror unit 40 are condensed to the focal point F ′ when there is no concave lens 5. To do.

  That is, the focal points of the plurality of parabolic mirrors 3 and the focal points of the concave lens 5 overlap. With this configuration, the concave lens 5 can convert a plurality of convergent light beams from the mirror unit 40 into a plurality of parallel light beams.

  In addition, when the concave lens 5 is comprised with a spherical lens, since spherical aberration generate | occur | produces, the parallelism of the light beam from the concave lens 5 may fall.

  In such a case, it is possible to suppress a decrease in the parallelism of the light beam from the concave lens 5 by shifting the focal positions of the plurality of parabolic mirrors 3 so as to cancel the spherical aberration caused by the concave lens 5. is there.

  Specifically, the angle formed between the optical axis of the concave lens 5 and the parabolic mirror 3 is smaller as the parabolic mirror 3 guides the light beam incident on the position away from the optical axis of the concave lens 5 to the mirror unit 40. Thus, the parabolic mirror array 30 is configured. In other words, the parabolic mirror array is arranged such that the angle between the optical axis of the concave lens 5 and the parabolic mirror 3 becomes smaller as the parabolic mirror 3 away from the concave lens 5 among the plurality of parabolic mirrors 3. 30.

  With such a configuration, it is possible to condense a plurality of convergent light beams from a plurality of parabolic mirrors 3 in a narrower range on the phosphor while suppressing the spherical aberration due to the concave lens 5 described above. Become.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist.

[Other Embodiments]
In the above-described embodiment, the configuration in which the concave lens is used to convert the light beam from the parabolic mirror array into a parallel light beam, that is, the lens unit has a negative power, but the present invention is not limited thereto. is not. For example, an optical device capable of realizing a smaller light source device while suppressing a decrease in light utilization efficiency is provided with a convex lens on the far side in the Y-axis direction from the condensing position of the light beam from the mirror unit 40, for example. Also good. That is, the lens unit may have a positive power. In such a configuration, the convex lens is provided so that the focal point of the convex lens is the condensing position of the light beam from the mirror unit 40.

  In the above-described embodiment, the configuration using the plurality of parabolic mirrors 3 as the plurality of reflecting surfaces and the plurality of concave mirrors is illustrated, but the present invention is not limited to this. For example, a plurality of plane mirrors are used as a plurality of reflecting surfaces, and a second positive lens that converts a parallel beam from the collimator lens 2 into a converged beam is provided between the collimator lens 2 and the plane mirror, and converges on the plane mirror. The structure which guides a light beam may be sufficient. That is, the light beams from the plurality of light sources are not limited to parallel light beams, and the plurality of reflecting surfaces are not limited to concave mirrors including paraboloids.

3 Parabolic mirror (reflective surface, concave mirror)
3a Parabolic mirror (second concave mirror)
3b Parabolic mirror (first concave mirror)
5 Concave lens (lens unit)
30 Parabolic mirror array (optical unit)

Claims (8)

An optical unit comprising a plurality of reflecting surfaces for reflecting light beams from a plurality of light sources ;
A lens unit;
A mirror unit that guides light beams from the plurality of reflecting surfaces to the lens unit,
The plurality of reflecting surfaces are configured such that the light beams reflected by the plurality of reflecting surfaces are a plurality of convergent light beams, and the distance between the plurality of convergent light beams decreases as the distance from the plurality of reflecting surfaces increases. ,
The plurality of reflecting surfaces are a plurality of concave mirrors,
The plurality of concave mirrors include a first concave mirror and a second concave mirror provided at a position farther from the lens unit than the first concave mirror,
The focal length of the second concave mirror is longer than the focal length of the first concave mirror,
Said first concave mirror and the second concave mirror Ri part der plurality of concave respective different shapes,
In the optical axis direction of the lens unit, the mirror unit is provided between the second concave mirror and the lens unit.
An optical device . The concave surface is a paraboloid;
The optical apparatus according to claim 1. The lens unit is configured to convert a plurality of convergent light beams from the mirror unit into a plurality of parallel light beams parallel to each other.
The optical device according to claim 1, wherein the optical device is an optical device. The lens unit includes a meniscus lens having negative power and a convex side on which a light beam from the plurality of light sources is incident.
The optical apparatus according to claim 3 . A plane parallel to the optical axis of the lens unit and the long side direction of the mirror unit is a first cross section,
When a surface perpendicular to the first cross section and parallel to the optical axis of the lens unit is a second cross section, the first cross section or the second cross section of the plurality of reflective surfaces is provided symmetrically with respect to the symmetry plane. The reflecting surfaces being a part of the parabolic shape of the same shape,
The optical device according to claim 3 or 4, characterized in that. Multiple light sources;
A plurality of positive lenses on which a plurality of light beams from the plurality of light sources respectively enter;
An optical device according to any one of claims 3 to 5 ,
A part of the light beam from the optical device is converted into converted light having a wavelength different from that of the light beam from the optical device, and the converted light and non-converted light having the same wavelength as the light beam from the optical device are emitted. A wavelength conversion element;
A dichroic mirror, and
The dichroic mirror is configured such that a light beam from the optical device enters the wavelength conversion element via the dichroic mirror.
A light source device characterized by that. The light source device according to claim 6 ;
A light modulation element;
A light separation unit that divides a light beam from the light source device into a plurality of light beams and guides it to the light modulation element, and combines a light beam from the light modulation element;
An illumination optical system that guides a light beam from the light source device to the color separation / synthesis system,
A projection type display device characterized by that. An optical unit that includes a plurality of reflecting surfaces that reflect light beams from a plurality of light sources and guide the light beams to a lens unit via a mirror unit,
The plurality of reflecting surfaces are configured such that the light beams reflected by the plurality of reflecting surfaces are a plurality of convergent light beams, and the distance between the plurality of convergent light beams decreases as the distance from the plurality of reflecting surfaces increases. ,
The plurality of reflecting surfaces are a plurality of concave mirrors,
Each of the plurality of concave mirrors is a part of each of a plurality of concave surfaces having different shapes,
The plurality of concave mirrors include a first concave mirror and a second concave mirror provided at a position farther from the lens unit than the first concave mirror, and the focal length of the second concave mirror is the first concave mirror Longer than the focal length of the concave mirror,
A plane parallel to the optical axis of the lens unit and the long side direction of the mirror unit is a first cross section,
When a surface perpendicular to the first cross section and parallel to the optical axis of the lens unit is a second cross section, the first cross section or the second cross section of the plurality of reflective surfaces is provided symmetrically with respect to the symmetry plane. The reflecting surfaces being a part of the parabolic shape of the same shape,
An optical unit characterized by that.

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