JP7625977B2 - Optical system, light source device and image display device - Google Patents

Description

The present invention relates to an optical system, a light source device, and an image display device.

Patent Document 1 discloses a projector that includes a light source device 63, a display element, a projector control means, etc., and the light source device 63 has a plurality of segment areas on a base material that can be rotated, at least one of the segment areas of the base material is a reflective area, a phosphor layer that receives excitation light and emits light of a predetermined wavelength band is formed on the reflective area, and the segment area where the phosphor layer is not formed is a transparent area that transmits light, a first light source that irradiates the phosphor with excitation light in the visible light range, a second light source 82 that emits light of a wavelength band different from the fluorescent light emitted from the phosphor layer and the excitation light emitted from the first light source 72, a focusing optical system that focuses the light emitted from the fluorescent wheel 71 and the light emitted from the second light source 82 on the same optical path, and a light source control means that controls the light emission of the first light source 72 and the second light source 82.

Patent Document 2 discloses a light source device 2 that includes a laser light source 9 that emits excitation light, a phosphor wheel 12 that transmits a portion of the excitation light and emits fluorescence upon receiving the excitation light, and reflects the excitation light and the fluorescence, a dichroic mirror 10 provided on the optical path of the excitation light between the laser light source 9 and the phosphor wheel 12, and a quarter-wave plate 11 provided on the optical path of the excitation light between the phosphor wheel 12 and the dichroic mirror 10, and the dichroic mirror 10 has a polarization separation characteristic that transmits a first polarized component of the excitation light on the outbound path and reflects the second polarized component of the excitation light and the fluorescence on the return path.

The present invention aims to provide an optical system, a light source device, and an image display device that can be configured compactly.

The invention of claim 1 provides an optical system including an optical member that reflects a first light emitted from a light source, a wavelength conversion unit that receives the first light reflected by the optical member and converts at least a part of the first light into a second light having a wavelength different from the first light and emits the second light, a light guiding optical system between the optical member and the wavelength conversion unit that guides the first light reflected by the optical member to the wavelength conversion unit, and a holding member that holds the optical member, wherein the first light emitted from the light source is reflected by the optical member and enters the light guiding optical system from the light source side with respect to the optical axis of the light guiding optical system, passes through the light guiding optical system at an angle approaching the optical axis of the light guiding optical system and enters the wavelength conversion unit, and of the first light that is emitted from the light guiding optical system and enters the wavelength conversion unit, the first light that enters a reflecting portion in the wavelength conversion unit is specularly reflected by the reflecting portion and is guided to the light guiding optical system from the opposite side to the light source side with respect to the optical axis of the light guiding optical system. the optical member has an optical property of transmitting the second light; the second light enters a part of an optical system, passes through the light-guiding optical system at an angle away from the optical axis of the light-guiding optical system, and does not intersect with the optical member after exiting the light-guiding optical system; an optical path of the first light from being emitted from the light source to being incident on the reflecting section and an optical path of the first light after being specularly reflected by the reflecting section and exiting the light-guiding optical system do not intersect with each other; the optical member has an optical property of transmitting the second light; when one end of the optical member in a longitudinal direction is defined as a first end, the other end of the optical member in the longitudinal direction is defined as a second end, one end of the optical member in a lateral direction is defined as a third end, and the other end of the optical member in the lateral direction is defined as a fourth end, the optical member is held by the holding member at only the first end, the holding member is not present on the optical path of the second light, the first end is an end located on the light source side, and the second end is an end located on the optical axis side of the light-guiding optical system.

The present invention provides an optical system, a light source device, and an image display device that can be configured compactly.

2 is a schematic configuration diagram showing an optical path of blue laser light in a light source device according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing the optical path of fluorescent light in the light source device according to the embodiment; FIG. FIG. 2 is an explanatory diagram of the arrangement of dichroic mirrors according to the embodiment. 3A and 3B are explanatory diagrams illustrating a configuration of a phosphor unit included in the light source device according to the embodiment. 5A to 5C are explanatory diagrams of a fixing method of a dichroic mirror according to the embodiment. 13A and 13B are explanatory diagrams of a modified example of a fixing method of the dichroic mirror according to the embodiment. 3 is an explanatory diagram of a dichroic mirror according to the embodiment. FIG. 13A to 13C are explanatory diagrams of a modified example of a fixing method according to the embodiment. 13A to 13C are explanatory diagrams of a modified example of a fixing method according to the embodiment. 13A to 13C are explanatory diagrams of a modified example of a fixing method according to the embodiment. 13A to 13C are explanatory diagrams of a modified example of a fixing method according to the embodiment. 13A to 13C are explanatory diagrams of a modified example of a fixing method according to the embodiment. 1 is a schematic diagram showing a configuration of a projector device including a light source device according to an embodiment of the present invention.

Figure 1 is a schematic diagram showing the optical path of blue laser light in a light source device 20 according to an embodiment of the present invention.

As shown in FIG. 1, the light source device 20 has, arranged in order in the light propagation direction, a laser light source (excitation light source) 21, a coupling lens 22, a first optical system 23, a dichroic mirror 24 (an example of an optical element), which is an example of an optical element, a second optical system 25 (an example of a light guide optical system), a phosphor unit 26, which is an example of a wavelength conversion unit, a refractive optical system 27, and a light tunnel 29, which is an example of a light mixing element.

The laser light source 21 is, for example, an array of light sources that emit multiple laser beams. The laser light source 21 emits, for example, light in the blue band (blue laser light) with a center of emission intensity of 455 nm. Hereinafter, the blue laser light will be simply referred to as blue light. The blue light emitted from the laser light source 21 is linearly polarized light with a constant polarization direction, and is also used as excitation light to excite the phosphor in the phosphor unit 26 described later.

The light emitted from the laser light source 21 may be light of a wavelength capable of exciting a phosphor, which will be described later, and is not limited to light in the blue wavelength band. Although the laser light source 21 has multiple light sources, the present invention is not limited to this, and may be composed of a single light source. Although the laser light source 21 can be configured as multiple light sources arranged in an array on a substrate, the present invention is not limited to this, and other arrangements may be used.

The coupling lens 22 is a lens that receives the blue light emitted from the laser light source 21 and converts it into parallel light (collimated light). In the following, parallel light is not limited to completely collimated light, but includes approximately collimated light. The number of coupling lenses 22 only needs to correspond to the number of light sources of the laser light source 21, and can be increased or decreased according to an increase or decrease in the number of light sources of the laser light source 21.

In the light source device 20 according to this embodiment, the laser light source 21 and the coupling lens 22 constitute a light source unit. For example, the laser light source 21 is composed of a plurality of laser diodes arranged in rows and columns. In other words, the light source unit is composed of these laser diodes and the coupling lens 22 arranged on the emission surface side of the laser diodes.

The first optical system 23 has positive power overall, and includes, in order from the laser light source 21 side to the phosphor unit 26 side, a large-diameter lens 23a and a negative lens 23b. The large-diameter lens 23a is an example of a large-diameter element, has positive power, and is composed of a lens that collects and combines the parallel light emitted from the coupling lens 22. The negative lens 23b is an example of a parallelizing element, and is composed of a lens that converts the blue light collected by the large-diameter lens 23a into parallel light. The first optical system 23 reduces the diameter of the blue light (excitation light) that is incident as approximately parallel light from the coupling lens 22, and guides it to the dichroic mirror 24.

The dichroic mirror 24 is disposed at an angle with respect to the propagation direction of the blue light emitted from the first optical system 23. More specifically, the dichroic mirror 24 is disposed with its front end inclined downward along the propagation direction of the blue light emitted from the first optical system 23. The dichroic mirror 24 has the optical property of reflecting the blue light that has been made substantially parallel by the first optical system 23, while transmitting the fluorescent light (an example of the second colored light, the second light) converted by the phosphor unit 26. For example, the dichroic mirror 24 is coated with a coating that has the optical property described above.

The dichroic mirror 24 has a length shorter than the width of the first optical system 23. Because the dimensions of the dichroic mirror 24 are short, the light source device 20 can be made smaller.

The refractive optical system 27 is composed of a lens that collects the light (blue light and fluorescent light) emitted from the second optical system 25. The light (blue light and fluorescent light) emitted from the phosphor unit 26 passes through and is transmitted by the dichroic mirror 24, then is collected (refracted) by the refractive optical system 27 and enters the light tunnel 29.

The optical path of blue light in the light source device 20 having such a configuration (hereinafter referred to as the "blue light optical path" as appropriate) will be described. The blue light optical path refers to the optical path along which light reflected by the reflecting portion of the phosphor unit 26 travels, out of the excitation light emitted by the laser light source 21.

The blue light emitted from the laser light source 21 is converted into parallel light by the coupling lens 22. The blue light emitted from the coupling lens 22 is collected and combined by the large-diameter lens 23a of the first optical system 23, and then converted into parallel light by the negative lens 23b. The blue light emitted from the negative lens 23b is reflected by the dichroic mirror 24 and travels toward the second optical system 25. The dichroic mirror 24 forms a reflective surface 24a that reflects the blue light emitted from the laser light source 21. A point P at the center of the projection image of the excitation light described above is formed on the dichroic mirror 24.

As described above, the dichroic mirror 24 is positioned offset toward the first optical system 23 with respect to the optical axis of the second optical system 25. Therefore, the blue light optical path is incident on a part of the second optical system 25 (more specifically, the positive lens 25A) on the first optical system 23 side. The blue light then travels toward the optical axis of the second optical system 25 at an angle, and is emitted from the second optical system 25 (more specifically, the positive lens 25B). The blue light emitted from the second optical system 25 is incident on the phosphor unit 26.

Here, the blue light incident on the phosphor unit 26 is incident on the reflecting section. The blue light incident on the reflecting section is specularly reflected. The blue light specularly reflected by the reflecting section is incident on a part of the second optical system 25 (more specifically, the positive lens 25B) on the opposite side to the first optical system 23. The blue light then travels away from the second optical system 25 at an angle to the optical axis of the second optical system 25, and exits from the second optical system 25 (more specifically, the positive lens 25A).

The blue light emitted from the second optical system 25 (more specifically, the positive lens 25A) does not intersect with the dichroic mirror 24. The blue light beam specularly reflected from the phosphor unit 26 constitutes the excitation light beam emitted from the phosphor unit 26. Because the blue light beam does not intersect with the dichroic mirror 24, a decrease in light utilization efficiency can be suppressed.

Here, one end 33b (an example of a first end) of the dichroic mirror 24 is the end farther from the blue light emitted from the second optical system 25, and the other end 33a (an example of a second end) of the dichroic mirror 24 is the end closer to the luminous flux of blue light emitted from the second optical system 25.

The blue light that passes through the dichroic mirror 24 without intersecting with it enters the refractive optical system 27. The blue light then travels toward the optical axis of the refractive optical system 27 at an angle and enters the light tunnel 29. After being reflected multiple times and homogenized inside the light tunnel 29, it enters the illumination optical system located outside the light source device 20.

Figure 2 is a schematic diagram showing the optical path of fluorescent light in the light source device 20 according to this embodiment.

The optical path of the fluorescent light in the light source device 20 (hereinafter referred to as the "fluorescent optical path" as appropriate) will be described. Note that in FIG. 2, for the sake of convenience, part of the optical path of the fluorescent light is omitted. The fluorescent optical path refers to the optical path along which light that is wavelength converted by the wavelength conversion section of the phosphor unit 26 travels, out of the excitation light emitted by the laser light source 21.

Until the blue light emitted from the laser light source 21 is guided to the phosphor unit 26, the fluorescent light path is the same as the blue light path described above. Here, the blue light incident on the phosphor unit 26 is assumed to be incident on the wavelength conversion section. The blue light incident on the wavelength conversion section acts as excitation light for the phosphor, and is wavelength converted by the phosphor to become fluorescent light including, for example, a yellow wavelength range, and is Lambertian reflected by the action of the reflective coating and phosphor layer.

The fluorescent light that is Lambert-reflected by the wavelength conversion unit is converted into parallel light by the second optical system 25. The fluorescent light that is emitted from the second optical system 25 passes through the dichroic mirror 24 and enters the refractive optical system 27.

Here, one end 33b of the dichroic mirror 24 is located outside the fluorescent light beam, and the other end 33a of the dichroic mirror 24 is located within the fluorescent light beam.

The fluorescent light then approaches the optical axis of the refractive optical system 27 at an angle and enters the light tunnel 29. After being reflected multiple times and homogenized inside the light tunnel 29, the light enters the illumination optical system located outside the light source device 20.

In this way, in the light source device 20 according to this embodiment, the optical path of the blue light emitted from the laser light source 21 is different before and after reflection from the phosphor unit 26. More specifically, the blue light optical path is formed so that the point at the center of the projection image of the blue light projected from the laser light source 21 onto the dichroic mirror 24 does not intersect with the blue light beam reflected from the phosphor unit 26. As a result, the blue light beam emitted from the phosphor unit 26 does not intersect with the center of the projection image of the blue light emitted from the laser light source 21, and therefore the blue light can be prevented from passing through the same point on the dichroic mirror 24. This makes it possible to suppress the situation in which the dichroic mirror 24 is damaged due to an increase in the light concentration density, and improves reliability.

In addition, since there is no need to prepare special optical elements such as a retardation plate or a polarizing beam splitter (polarizing beam splitter) to separate the optical path of the blue light emitted from the phosphor unit 26, the number of parts can be reduced, which reduces manufacturing costs and makes the light source device 20 more compact. Furthermore, since no optical components that manipulate polarized light such as a retardation plate or a polarizing beam splitter are used, it is possible to suppress a decrease in light utilization efficiency due to the reflectance, transmittance, absorptance, etc. of the optical components.

Furthermore, in the light source device 20 according to this embodiment, the blue light emitted from the laser light source 21 is linearly polarized light with a fixed polarization direction. In addition, the light source unit having multiple laser light sources 21 is arranged so that the directions of the linear polarization are all the same. Therefore, the directions of the linear polarization of the light emitted from the light source unit are uniform. The direction of the linear polarization can be determined by the direction in which the light source unit is arranged. If the light source unit is tilted to match the inclination of the light tunnel 29, the direction of the linear polarization will change. In such a situation where the direction of the linear polarization changes, if the configuration is such that the polarization is manipulated by a polarization separation element or the like, the light utilization efficiency may decrease when passing through the polarization separation element. In the light source device 20 according to this embodiment, since a configuration that manipulates the polarization is not adopted, it is possible to prevent the light utilization efficiency from decreasing due to the inclination of the laser light source 21.

FIG. 3 is a diagram for explaining the arrangement of the dichroic mirror 24 according to this embodiment. FIG. 3 is a diagram showing the dichroic mirror 24 and the second optical system 25 as viewed from the position of the refractive optical system 27 in the optical axis direction of the second optical system 25 (from above in the vertical direction of FIG. 1 and FIG. 2). The blue light emitted from the phosphor unit 26 propagates from the back to the front of the paper in FIG. 3, and is emitted toward the refractive optical system 27 as a blue light beam 71 converted into parallel light by the second optical system 25. The dichroic mirror 24 is disposed so as to overlap with the fluorescent light beam 72 emitted from the positive lens 25A of the second optical system 25. The dichroic mirror 24 is disposed so that one end 33b is outside the fluorescent light beam 72. The other end 33a of the dichroic mirror 24 is disposed in the fluorescent light beam 72.

The blue light reflected by the phosphor unit 26 enters the second optical system 25, and propagates from the positive lens 25A as a blue light beam 71 from the back side to the front side of the paper in FIG. 3, and enters the refractive optical system 27. The dichroic mirror 24 is positioned outside the blue light beam 71 so as not to overlap with the blue light beam 71. The dichroic mirror 24 is positioned on the opposite side of the blue light beam 71 with respect to the optical axis 25C of the second optical system 25.

Of the fluorescent light beam 72, the fluorescent light that overlaps with the dichroic mirror 24 passes through the dichroic mirror 24, but some of it is reflected or absorbed by the dichroic mirror, reducing its intensity. Therefore, the fluorescent light beam 72 has an asymmetric intensity distribution with respect to the optical axis 25C of the second optical system 25. In the arrangement of the dichroic mirror shown in Figure 3, the intensity is weak on the side of one end 33b with respect to the optical axis 25C (the left side of Figure 3), and the intensity is strong on the side opposite the one end 33b with respect to the optical axis 25C (the right side of Figure 3).

The arrangement in FIG. 3(A) is an example in which the center line 33 in the short side direction of the dichroic mirror 24 overlaps with the optical axis 25C of the second optical system 25. With this arrangement, the intensity distribution of the fluorescent light beam 72 can be made symmetrical with respect to the center line 33 in the short side direction of the dichroic mirror 24, and the intensity distribution of the fluorescent light emitted from the refractive optical system 27 can be made more uniform.

Figure 3 (B) shows an example in which the center line of the dichroic mirror 24 in the short side direction is shifted from the optical axis 25C. Since the center of the dichroic mirror 24 is shifted upward in Figure 3b with respect to the optical axis 25C, the intensity distribution of the fluorescent light beam 72 becomes stronger on the lower right side of Figure 3b. In this case, if the orientation of the dichroic mirror 24 is not changed, the optical path of the blue light beam 71 does not change. Therefore, the arrangement of the dichroic mirror 24 in Figure 3 (B) can adjust the intensity distribution of the fluorescent light beam 72 regardless of the arrangement of the light source 21 and the first optical system 23. Thereby, the angular distribution of the fluorescent light emitted from the refractive optical system 27 can be adjusted to match the arrangement of the light tunnel 29. In this case, as described above, the distribution of the fluorescent light can be adjusted without being affected by the arrangement of the light source 21 and the first optical system 23.

Figure 4 is an explanatory diagram of the configuration of the phosphor unit of the light source device according to this embodiment. In Figure 4 (A), the phosphor unit 26 is shown from the direction of incidence of blue light, and in Figure 4 (B), the phosphor unit 26 is shown from a direction perpendicular to the direction of incidence of blue light. Note that the configuration of the phosphor unit 26 shown in Figure 4 is an example, and is not limited to this and can be modified as appropriate.

As shown in FIG. 4, the phosphor unit 26 has a disk member (substrate) 26A and a drive motor (drive unit) 26C that rotates around a rotation axis 26B that passes through the center of the disk member 26A and is perpendicular to the plane of the disk member 26A. The disk member 26A can be, for example, a transparent substrate or a metal substrate (such as an aluminum substrate), but is not limited to these.

The phosphor unit 26 (disk member 26A) is partitioned into a fluorescent region 26D over a large portion of the circumferential direction (an angular range greater than 270° in the first embodiment), and a small portion of the circumferential direction (an angular range less than 90° in the first embodiment) is partitioned into an excitation light reflection region 26E. The excitation light reflection region 26E is a first region that reflects (or diffusely reflects) the excitation light reflected by the dichroic mirror 24, and constitutes an example of a reflecting section. The fluorescent region 26D is a region that converts the excitation light reflected by the dichroic mirror 24 and emits fluorescent light, and constitutes an example of a wavelength conversion section. The fluorescent region 26D is configured by laminating a reflective coat 26D1, a phosphor layer 26D2, and an anti-reflection coat (AR coat) 26D3 in this order from the lower layer side to the upper layer side.

The reflective coating 26D1 has the property of reflecting light in the wavelength region of the fluorescent light (emitted light) produced by the phosphor layer 26D2. If the disk member 26A is made of a metal substrate with high reflectivity, it is possible to omit the reflective coating 26D1. In other words, it is possible to give the disk member 26A the function of the reflective coating 26D1.

For example, phosphor layer 26D2 may be a phosphor material dispersed in an organic or inorganic binder, a phosphor material crystallized directly, or a rare earth phosphor such as Ce:YAG. Phosphor layer 26D2 is an example of a wavelength conversion member that converts at least a part of the excitation light into fluorescent light of a different wavelength from the excitation light and emits it. The wavelength band of the fluorescent light (emission light) by phosphor layer 26D2 may be, for example, yellow, blue, green, or red, but in the first embodiment, a case where fluorescent light (emission light) having a yellow wavelength band is used will be described as an example. In this embodiment, a phosphor is used as the wavelength conversion element, but a phosphorescent material or a nonlinear optical crystal may also be used.

The anti-reflective coating 26D3 has the property of preventing light reflection on the surface of the phosphor layer 26D2.

A reflective coating (reflective surface) 26E1 having the property of reflecting light in the wavelength region of blue light guided from the second optical system 25 is laminated on the excitation light reflection region 26E. If the disk member 26A is made of a metal substrate with high reflectivity, it is possible to omit the reflective coating 26E1. In other words, it is possible to give the disk member 26A the function of the reflective coating 26E1.

By rotating disk member 26A by drive motor 26C, the irradiation position of the blue light on phosphor unit 26 moves over time. As a result, a part of the blue light (first colored light, an example of first light) incident on phosphor unit 26 is converted into fluorescent light (second colored light) having a different wavelength from the blue light (first colored light) in fluorescent region (wavelength conversion region) 26D and emitted. Meanwhile, the other part of the blue light incident on phosphor unit 26 is reflected as blue light by excitation light reflection region 26E.

The number and range of the fluorescent regions 26D and the excitation light reflecting regions 26E can be freely determined, and various design changes are possible. For example, two fluorescent regions and two excitation light reflecting regions may be alternately arranged at 90° intervals in the circumferential direction.

Figure 5 is an explanatory diagram of a method for fixing the dichroic mirror 24 according to this embodiment.

The dichroic mirror 24 has an area that is used optically and an area that is not used optically and is used to hold the dichroic mirror 24, and is fixed by a mirror holder 30 (an example of a holding member) that supports (holds) the dichroic mirror 24, and a mirror holder 31 that holds the dichroic mirror 24. The fixing method may be adhesive fixing, direct fixing of the dichroic mirror 24 with screws, etc., in addition to the configuration shown in the figure.

As shown in FIG. 2, one end 33b of the dichroic mirror 24 is located outside the light beam of the fluorescent light emitted from the second optical system 25. The one end 33b is included in an area that is not optically used, that is, an area that does not require any optical function. The mirror holder 30 holds this area that does not require any optical function.

The other end 33a of the dichroic mirror 24 is located within the light beam of the fluorescent light emitted from the second optical system 25, as shown in FIG. 2, and is not held by the mirror holder 30.

As shown in FIG. 5(b), an opening 30A is formed in the mirror holder 30, and the fluorescent light beam emitted from the second optical system 25 shown in FIG. 2 passes through the opening 30A.

In addition, the blue light emitted from the second optical system 25 shown in FIG. 1 passes through the area of the opening 30A of the mirror holder 30 that does not overlap with the dichroic mirror 24.

Figure 6 is an explanatory diagram of a modified example of the method for fixing the dichroic mirror 24 according to this embodiment.

In FIG. 5, the mirror holder 30 holds the dichroic mirror 24 so that one end 33b protrudes, but in FIG. 6, the mirror holder 30 holds the dichroic mirror 24 so that one end 33b does not protrude.

Figure 7 is an explanatory diagram of the dichroic mirror 24 according to this embodiment.

The relationship between the dichroic mirror 24, a first straight line 32 in the X direction that passes through the mirror, and a second straight line 33 in the Y direction that passes through the mirror will be explained. The dichroic mirror 24 is made of a transparent substrate such as glass or sapphire, and has optical functions such as a polarization separation film, wavelength selective filter function, and reflective film applied to the surface. In particular, an optical thin film that transmits or reflects depending on the wavelength is applied to the surface of the dichroic mirror area that transmits or reflects depending on the wavelength. Two imaginary straight lines (32, 33) are defined on the surface.

In this example, the second straight line 33 is a line in the longitudinal direction of the dichroic mirror 24, and the first straight line 32 is a line along the short side direction of the dichroic mirror 24, and are perpendicular to each other. The first straight line 32 is a line in the long side direction of the dichroic mirror 24, and the second straight line 33 is a center line of the dichroic mirror 24 in the short side direction.

The optical element has ends on imaginary straight lines 32 and 33 , which are designated as 33a, 33b, 32a, and 32b.

As described above, one end 33b is located outside the light beam of the fluorescent light emitted from the second optical system 25 and is held by the mirror holder 30.

The other end 33a, as described above, is located within the light beam of the fluorescent light emitted from the second optical system 25 and is not held by the mirror holder 30.

Furthermore, as shown in Figures 5 and 6, one end 32b and the other end 32a are located within the light beam of the fluorescent light emitted from the second optical system 25 and are not held by the mirror holder 30.

The dichroic mirror 24 may be arranged so that the position where the blue light emitted from the laser light source 21 enters the reflecting surface 24a of the dichroic mirror 24 is the center in the direction of the imaginary first straight line 32. The other end 33a of the dichroic mirror 24 is located within the fluorescent light beam and the blue light beam. Therefore, the temperature of the reflecting surface 24a side of the dichroic mirror 24 increases when the fluorescent light and blue light are irradiated. The dichroic mirror 24 is distorted due to the increase in temperature on one side, and the reflecting surface 24a is curved. Even if the reflecting surface 24a is curved in this way, the change in angle with respect to the blue light beam near the center of the reflecting surface 24a in the direction of the first straight line 32 is smaller than the end of the reflecting surface 24a in the direction of the first straight line 32 (near the ends 32a and 32b of the reflecting surface 24a). Therefore, even if the temperature of the dichroic mirror 24 rises, the change in the emission direction of the blue light reflected by the reflecting surface 24a is small. As a result, the optical system of this embodiment can stabilize the emission direction of the blue light beam.

To position the center of the blue light flux at the center of the first straight line 32 of the dichroic mirror 24, the first optical system 23 and the dichroic mirror should be positioned so that the optical axis of the first optical system 23 intersects with the reflecting surface 24a at the center of the dichroic mirror 24 in the direction of the virtual line 32. Explaining this in the modified example of Figure 6, the intersection of the first straight line 32 and the second straight line 33 of the dichroic mirror 24 intersects with the optical axis of the first optical system.

The imaginary first straight line 32 and second straight line 33 are defined as being at an angle of approximately 90 degrees to each other, but this is not limited thereto.

In addition, the optical elements have been described as rectangular, but they may be square, polygonal, circular, or elliptical. The optical element shape should be designed to suit the unit composition.

Figure 8 is an explanatory diagram of a modified example of the method of fixing the dichroic mirror 24 according to this embodiment. The dichroic mirror 24 is sandwiched between the mirror holder 30 and the mirror holder 31, and is fixed by fastening the mirror holder 31 to the mirror holder 30 with a screw 35. The mirror holder 30 is provided with a recess 34c that matches the shape of the dichroic mirror 24. The bottom surface of the recess 34c abuts against the reflecting surface 24a of the dichroic mirror 24 to determine the angle of the reflecting surface 24a. The recess 34c has walls in three directions except for the opposite side to one end 33b of the dichroic mirror. These walls of the recess 34c fit with the side of the dichroic mirror 24. Furthermore, a protrusion 34a is provided on the bottom surface of the recess 34c, and a hole 34b is provided in the dichroic mirror 24. The protrusion 34a and the hole 34b fit together to determine the position in a direction parallel to the reflecting surface 24a of the dichroic mirror 24. Here, the recess 34c, the hole 34b, and the protrusion 34a are an example of a positioning part that determines the position of the dichroic mirror 24 relative to the position of the mirror holder 30. These positioning parts prevent horizontal positional deviation even if the optical system is subjected to shock or vibration, so the blue light flux and the dichroic mirror do not interfere with each other, and the amount of blue light emitted by the optical system can be stabilized.

Figure 9 is an explanatory diagram of another modified method of fixing the dichroic mirror 24 according to this embodiment. The dichroic mirror 24 is positioned and fixed by fitting into the recess 34c as in Figure 8 and being sandwiched between the mirror holder 30 and the mirror retainer 31. A protrusion 34d is provided on the side of the recess of the mirror holder 30, and a notch 34e is provided on the side of the dichroic mirror 24. The notch 34e fits into the protrusion 34d, allowing the positions of the dichroic mirror 24 and the mirror holder 30 to be determined.

Figure 10 is a diagram illustrating a modified example in which a biasing member is added to the embodiment of Figure 9. The dichroic mirror 24 of the modified example of Figure 10 is provided with a notch 34h as in the modified example of Figure 9. The notch 34h is V-shaped when viewed from a direction perpendicular to the reflecting surface 24a of the dichroic mirror. The mirror holder 30 is provided with a biasing member 34f. The biasing member 34f is provided with a protrusion 34g that fits into the notch 34h. The biasing member 34f biases the dichroic mirror 24 to press against the wall 34i, which is an example of the reference surface of the mirror holder 30, using a biasing means such as a leaf spring (not shown). Here, the shape of the protrusion 34g is semicircular, and the arc of the protrusion 34g is made to abut against the two surfaces of the V-shape of the notch 34h at two points. The dichroic mirror 24 is fixed by being sandwiched between the mirror holder 30 and the mirror retainer 31, as in the modified example of FIG. 9. By providing the biasing member 34f in this manner, the position of the dichroic mirror 24 can be kept normal even if the external shape of the dichroic mirror 24 changes due to temperature changes.

Figure 11 is an explanatory diagram of another modified example of the method of fixing the dichroic mirror 24 according to this embodiment. As with the modified example of Figure 8, the dichroic mirror 24 is fixed by fitting into the recess 34c and being clamped between the mirror holder 30 and the mirror retainer 31. In the modified example of Figure 11, the end faces 34j and 34k of the dichroic mirror 24 abut against the walls 34i and 34m of the recess. The end 34k is not parallel to the end 34j, and the wall 34m is not parallel to the wall 34i. After the dichroic mirror 24 is positioned so that it fits into the recess 34c, one end 33b of the dichroic mirror 24 is urged in the direction indicated by the arrow 34n by an urging means (not shown). End faces 34j and 34k are tapered, and wall portions 34i and 34m are tapered, so that the dichroic mirror 24 is biased to determine its position in a direction parallel to the reflecting surface 24a. Since the dichroic mirror 24 is constantly biased, even if it temporarily shifts position due to vibration or impact, it is repositioned by the bias, so it can maintain a stable position for a long period of time. In addition, the dichroic mirror 24 in FIG. 11 does not require the processing of specially shaped notches or holes, so the dichroic mirror can be easily manufactured.

FIG. 12 shows another modified example of the fixing method of the dichroic mirror 24 according to the present embodiment. In the modified example of FIG. 12, the dichroic mirror 24 is fixed by being sandwiched between the mirror holder 30 and the mirror holder 31, as in the fixing method shown in FIG. 10, but is different in that a heat transfer member 36 is provided between the dichroic mirror 24 and the mirror holder 30 and between the dichroic mirror 24 and the mirror holder 31, as shown in FIG. 12B. The heat transfer member 36 is disposed so as to be in close contact with the top and bottom of the dichroic mirror 24, and is sandwiched together with the dichroic mirror 24 by the mirror holder 30 and the mirror holder 31. The heat transfer member 36 disposed between the mirror holder 30 and the dichroic mirror 24 is in thermal contact with the dichroic mirror 24 and the mirror holder 30 by being in close contact with each of them. Similarly, the heat transfer member 36 disposed between the mirror holder 31 and the dichroic mirror 24 is in thermal contact with the dichroic mirror 24 and the mirror holder 31 by being in close contact with each of them. The dichroic mirror 24 is heated by the incident blue light and fluorescent light, and the temperature rises. In particular, the fluorescent light emitted from the phosphor unit 26 contains infrared rays , and therefore the dichroic mirror 24 is easily heated. Therefore, the light incident surface of the dichroic mirror 24 is heated by the incident blue light and fluorescent light, and the temperature rises. When the temperature of the dichroic mirror 24 rises, the dichroic mirror 24 is deformed due to thermal expansion of the material of the substrate of the dichroic mirror 24 and the material of the coating. In particular, when the temperature of one side of the dichroic mirror 24 becomes high, the dichroic mirror 24 is warped or distorted due to stress caused by the thermal expansion of one side of the dichroic mirror 24. When the dichroic mirror 24 is distorted, the angle of the reflecting surface 24a changes, and the direction in which the incident blue light is reflected changes. Furthermore, if the temperature change of the dichroic mirror 24 is large, the position of the dichroic mirror 24 with respect to the mirror holder 30 fluctuates, causing a problem of misalignment.

In the modified example of FIG. 12, the heat transfer member 36 is placed between the dichroic mirror 24 and the mirror holder 30 and mirror retainer 31, so that the heat of the dichroic mirror 24 can be efficiently transferred to the mirror holder 30 and mirror retainer 31, thereby reducing the temperature rise of the dichroic mirror 24. This makes it possible to reduce the positional deviation and deformation of the dichroic mirror 24.

The material of the heat transfer member 36 is preferably a material that has high thermal conductivity and high adhesion to the dichroic mirror 24 and the mirror holder 30. For example, it is preferable to use a metal with relatively low rigidity such as aluminum, tin, or solder, a film-like resin with high thermal conductivity, or a rubber material with high thermal conductivity.

The heat transfer members 36 may be disposed on both sides of the dichroic mirror 24, or may be disposed on one side. When the heat transfer members 36 are disposed on both sides, the heat of the dichroic mirror 24 can be efficiently transferred, so that the temperature rise of the dichroic mirror 24 can be suppressed. When the heat transfer members 36 are disposed between the dichroic mirror 24 and the mirror retainer 31, the heat of the dichroic mirror 24 is less likely to be transferred to the mirror holder 30 , so that the temperature rise of the mirror holder 30 can be suppressed. In that case, the mirror holder 30 can be prevented from being deformed due to a temperature rise of the mirror holder 30 , so that the position of the dichroic mirror 24 is stabilized.

The mirror retainer 31 or mirror holder 30 in FIG. 12 can be a heat dissipation member. The mirror retainer 31 or mirror holder 30 may be formed with fins for heat dissipation, or may be formed with a fan for air cooling or a flow path for cooling water.

Figure 13 is a schematic diagram showing a projector device (image projection device) 1 equipped with a light source device 20 according to the first embodiment.

The projector device 1 has a housing 10, a light source device 20, an illumination optical system 130, an image forming element (image display element) 40, a projection optical system 50, and a cooling device 60. The housing 10 houses the light source device 20, the illumination optical system 130, the image forming element 40, the projection optical system 50, and the cooling device 60.

The illumination optical system 130 illuminates the image forming element 40 approximately uniformly with the light homogenized by the light tunnel 29 of the light source device 20. The illumination optical system 130 has, for example, one or more lenses and one or more reflective surfaces.

The image-forming element 40 forms an image by modulating the light illuminated by the illumination optical system 130 (light from the light source optical system of the light source device 20). The image-forming element 40 is composed of, for example, a digital micromirror device (DMD) or a liquid crystal display element. The image-forming element 40 drives a micromirror surface in synchronization with the light (blue light, green light, red light, yellow light) irradiated from the illumination optical system 130 to generate a color image.

The projection optical system 50 enlarges and projects the image (color image) formed by the image forming element 40 onto a screen (projection surface). The projection optical system 50 has, for example, one or more lenses. The cooling device 60 cools each element and device that generates heat within the projector device 1.

●Summary●
As described above, the optical systems 24, 25, and 26 according to one embodiment of the present invention are optical systems including a dichroic mirror 24 (an example of an optical member) that reflects blue light (an example of a first light) emitted from a light source, and a fluorescent region 26D (an example of a wavelength conversion section) of a phosphor unit 26 that receives the blue light reflected by the dichroic mirror 24, converts at least a part of the blue light into fluorescent light (an example of a second light) having a wavelength different from that of the blue light, and emits the fluorescent light. The dichroic mirror 24 has an optical characteristic of transmitting fluorescent light, and includes one end 33b (an example of a first end) located outside the light flux of the fluorescent light, and the other end 33a (an example of a second end) located within the light flux of the fluorescent light. A mirror holder 30 (an example of a holding member) that holds the dichroic mirror 24 outside the light flux of the fluorescent light is provided. As an example, the mirror holder 30 holds the dichroic mirror 24 at one end 33b.

This allows the optical system to be constructed more compactly than if both ends of the dichroic mirror 24 were held outside the fluorescent light beam.

The other end 33a is located on the opposite side of the one end 33b. This allows the optical system to be configured compactly in the direction connecting the other end 33a and the one end 33b.

The second end located within the fluorescent light beam includes not only the other end 33a located opposite the one end 33b, but also one end 32b and the other end 32a located on a straight line 32 perpendicular to the straight line 33 connecting the one end 33b and the other end 33a. This allows the optical system to be configured compactly in the directions of the straight line 33 and the straight line 32.

The center position of the blue light incident on the dichroic mirror 24 is at the midpoint between one end 32b and the other end 32a. As a result, even if the temperature of the dichroic mirror 24 rises, the change in the emission direction of the blue light reflected by the reflective surface 24a is small, and the emission direction of the blue light beam can be stabilized.

The dichroic mirror 24 is not held at the other end 33a, which prevents a decrease in the quality of the fluorescent light caused by providing a holding member at the other end 33a.

The dichroic mirror 24 is not held in the portion located within the fluorescent light beam. This prevents the quality of the fluorescent light from being reduced due to the provision of a holding member.

The holding structure for the end 33b of the dichroic mirror 24, which does not require any optical function, is preferably held by adhesion or clamping.

It is preferable to provide a structure to protect the end 33b of the dichroic mirror 24 that does not require any optical function and the optically functional portion of the dichroic mirror 24.

The phosphor unit 26 has an excitation light reflection region 26E (an example of a reflecting section) that reflects the blue light reflected by the dichroic mirror 24, and the dichroic mirror 24 is located outside the light beam of the blue light reflected by the excitation light reflection region 26E.

This prevents the dichroic mirror 24 from degrading the quality of the blue light reflected by the excitation light reflection region 26E.

The dichroic mirror 24 is not held at the other end 33a, which is the end closer to the blue light beam reflected by the excitation light reflection area 26E. This allows the optical system to be configured more compactly than when the dichroic mirror 24 is held at the other end 33a, which is the end closer to the blue light beam reflected by the excitation light reflection area 26E.

The dichroic mirror 24 and the mirror holder 30 may have a hole 34a and a protrusion 34b, which are positioning parts that determine their relative positions. This allows the hole 34b of the dichroic mirror to fit into the protrusion 34a of the mirror holder, stabilizing the position of the dichroic mirror 24 and preventing a decrease in the quality of the blue light reflected by the dichroic mirror 24.

The dichroic mirror 24 may have a notch 34e as a positioning portion, and the mirror holder 30 may have a protrusion 34d that fits into the notch 34e. This prevents the dichroic mirror 24 from shifting position relative to the mirror holder 30, and prevents a decrease in the quality of the blue light reflected by the dichroic mirror 24.

The mirror holder 30 may include a biasing member 34f that biases the dichroic mirror 24. This biases the dichroic mirror 24 to abut against the reference surface 34i of the mirror holder 30, thereby stabilizing the position of the dichroic mirror 24 and preventing a decrease in the quality of the blue light.

The mirror holder 30 has a heat transfer member 36 between it and the dichroic mirror 24. Alternatively, the mirror holder 30 has a heat dissipation member that dissipates heat from the dichroic mirror 24. This makes it possible to reduce positional deviation and deformation of the dichroic mirror 24.

A second optical system 25 (an example of a light guiding optical system) is provided between the dichroic mirror 24 and the fluorescent region 26D, which guides the blue light reflected by the dichroic mirror 24 to the fluorescent region 26D. The second optical system 25 converts the fluorescent light incident from the fluorescent region 26D into parallel light and emits it. The optical axis of the second optical system 25 is midway between one end 32b and the other end 32a of the dichroic mirror 24. This makes it possible to make the intensity distribution of the fluorescent light flux 72 symmetrical with respect to the center line 33 in the short side direction of the dichroic mirror 24.

A second optical system 25 is provided between the dichroic mirror 24 and the fluorescent region 26D, which guides the blue light reflected by the dichroic mirror 24 to the fluorescent region 26D. The second optical system 25 converts the fluorescent light incident from the fluorescent region 26D into parallel light and emits it. The optical axis of the second optical system 25 is shifted from the midpoint between one end 32b and the other end 32a of the dichroic mirror 24. This makes it possible to adjust the intensity distribution of the fluorescent light beam 72 regardless of the arrangement of the light source 21 and the first optical system 23.

The light source device 20 can be configured compactly by including a laser light source 21 (an example of a light source) and the optical system described above.

The projector device 1 (an example of an image projection device) can be configured compactly by including a light source device 20, an illumination optical system 130 that guides the light emitted from the light source device 20 to an image display element, and a projection optical system 50 that projects an image generated by the image display element 40 using the light guided by the illumination optical system 130.

1: Projector device 10: Housing 20: Light source device 21: Laser light source 22: Coupling lens 23: First optical system 23a: Large diameter lens 23b: Negative lens 24: Dichroic mirror (an example of an optical member)
25: Second optical system (light guiding optical system)
25A, 25B: positive lens 26: phosphor unit 26D: fluorescent region (an example of a wavelength conversion section)
26E: Excitation light reflection area (an example of a reflection portion)
27: Refractive optical system 29: Light tunnel 30: Mirror holder (an example of a holding member)
31: Mirror holder 32: First straight line in the X direction passing through the mirror 33: Second straight line in the Y direction passing through the mirror 33a: The other end (second end)
33b: One end (first end)
34a, 34d: protrusions (examples of positioning portions)
34b: Hole portion (an example of a positioning portion)
34c: Recess 34e, 34g: Protrusion (an example of a positioning portion)
34f: Pressing member 36 Heat transfer member 40: Image forming element 50: Projection optical system 60: Cooling device 130: Illumination optical system

Patent No. 4711156 Patent No. 5817109

Claims (10)

an optical member that reflects a first light emitted from the light source;
a wavelength conversion unit that receives the first light reflected by the optical member, converts at least a part of the first light into a second light having a wavelength different from that of the first light, and outputs the second light;
a light guiding optical system between the optical member and the wavelength converting unit, the light guiding optical system guiding the first light reflected by the optical member to the wavelength converting unit;
A holding member for holding the optical member;
An optical system comprising:
The first light emitted from the light source is reflected by the optical member to enter the light-guiding optical system from the light source side with respect to the optical axis of the light-guiding optical system, passes through the light-guiding optical system at an angle approaching the optical axis of the light-guiding optical system, and enters the wavelength conversion unit,
Of the first light emitted from the light-guiding optical system and incident on the wavelength conversion unit, the first light incident on a reflecting portion in the wavelength conversion unit is specularly reflected by the reflecting portion, enters a part of the light-guiding optical system from the side opposite to the light source side with respect to the optical axis of the light-guiding optical system, passes through the light-guiding optical system at an angle away from the optical axis of the light-guiding optical system, and does not intersect with the optical member after being emitted from the light-guiding optical system,
an optical path of the first light from being emitted from the light source to being incident on the reflecting unit and an optical path of the first light after being specularly reflected by the reflecting unit and being emitted from the light-guiding optical system do not intersect with each other;
the optical member has an optical property of transmitting the second light,
when one end of the optical member in a longitudinal direction is defined as a first end, the other end of the optical member in the longitudinal direction is defined as a second end, one end of the optical member in a lateral direction is defined as a third end, and the other end of the optical member in the lateral direction is defined as a fourth end, the optical member is held by the holding member only at the first end,
the holding member is not present on an optical path of the second light,
An optical system , wherein the first end is an end located on the light source side, and the second end is an end located on the optical axis side of the light guiding optical system . 2. The optical system according to claim 1, wherein a center position of the first light beam incident on the optical member is at a midpoint between the third end and the fourth end . the optical member has a reflective surface that reflects the first light,
3. The optical system according to claim 1, wherein the optical member has a positioning portion that determines a position of the optical member relative to the holding member in a direction parallel to the reflecting surface . 4. The optical system according to claim 3, wherein the holding member has a biasing member for biasing the optical member in a direction parallel to the reflecting surface . 5. The optical system according to claim 1, wherein the holding member has a heat transfer member between it and the optical member . 5. The optical system according to claim 1, wherein the holding member includes a heat dissipation member that dissipates heat from the optical member . The optical system described in any one of claims 1 to 6, characterized in that the light-guiding optical system converts the second light incident from the wavelength conversion unit into parallel light and emits it, and the optical axis of the light-guiding optical system is midway between the third end and the fourth end of the optical element . The optical system described in any one of claims 1 to 6, characterized in that the light-guiding optical system converts the second light incident from the wavelength conversion unit into parallel light and emits it, and the optical axis of the light-guiding optical system is shifted from the midpoint between the third end and the fourth end of the optical element . A light source device comprising the light source and the optical system according to any one of claims 1 to 8. The light source device according to claim 9 ;
an illumination optical system that guides light emitted from the light source device to an image display element;
a projection optical system that projects an image generated by the image display element using the light guided by the illumination optical system.