Light source device and projection device

Abstract

To provide a light source device capable of emitting bright light while improving light utilization efficiency of a light source, and a projection device.SOLUTION: The light source device comprises: a light source; a plurality of wavelength conversion units each including a wavelength conversion area for receiving light emitted from the light source and emitting light different in wavelength from the received light; and a plurality of optical systems forming an image of each wavelength conversion area of the plurality of wavelength conversion units. The light source irradiates the plurality of wavelength conversion units with light at the same timing. The plurality of optical systems bring images of the wavelength conversion areas of the plurality of wavelength conversion units adjacent to or overlapped with each other.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a light source device and a projection device. [Background technology]

[0002] Projectors (image projection devices) that enlarge and project various images are widely used today. A projector is a device that focuses light emitted from a light source onto a spatial light modulation element (image display element) such as a DMD (Digital Mirror Device) or a liquid crystal display element, and displays the emitted light (reflected light) from the spatial light modulation element modulated based on a video signal as a color image on a screen.

[0003] Traditionally, projectors have mainly used high-intensity ultra-high pressure mercury lamps, but because of their short lifespan and the need for frequent maintenance, as well as the need to reduce the use of mercury, a hazardous substance, and to be environmentally conscious, there is a shift towards the use of solid-state light sources such as laser light sources or LED (Light Emitting Diode) light sources. Laser and LED light sources have a long lifespan and good color reproduction due to their monochromaticity, so in the future, projectors equipped with ultra-high pressure mercury lamps may be used only for special applications, and the majority of projectors on the market may switch to solid-state light sources.

[0004] Incidentally, to project color images, illumination light sources of at least the three primary colors are required, and although it is possible to generate all of them with laser light sources, this is not preferable because the luminous efficiency of green and red lasers is lower than that of blue lasers. For this reason, the mainstream method is to irradiate a phosphor with blue laser as excitation light, and generate red and green light from the fluorescent light that is wavelength-converted by the phosphor.

[0005] However, because excitation light of tens of watts is concentrated and irradiated onto phosphors, they are susceptible to burnout or temperature rise, resulting in a decrease in efficiency and deterioration over time. For this reason, a technology has been developed to form a phosphor layer on a circular plate and rotate it to prevent the excitation light from concentrating at a single point. However, this technology also has limitations when it comes to projecting with a brighter light source. One solution to this problem is to increase the number of phosphor wheels and combine the fluorescence emitted from each. Summary of the Invention [Problem to be solved by the invention]

[0006] However, in a system using multiple phosphors, when the wavelength color of the fluorescent light emitted from the phosphor (e.g., yellow or green) and the light source itself (e.g., blue light source or red light source) are used, the DLP (registered trademark) single-panel system, which allows for an extremely compact light source device, has the problem of loss occurring at the moment the color is switched.

[0007] The present invention has been made in view of the above, and has an object to provide a light source device and a projection device that can improve the light utilization efficiency of the light source and emit bright light. [Means for solving the problem]

[0008] In order to solve the above problems and achieve the objectives, No. 1 a light source; No. 1 Receives light emitted from a light source and emits light of a wavelength different from the wavelength of the received light. No. 1 Wavelength conversion region a first non-conversion region that outputs light received from the first light source without converting the wavelength of the light; having No. 1 a wavelength conversion unit; No. 1 The wavelength conversion unit No. 1 Forming an image of the wavelength-converted region No. 1 An optical system, a second wavelength conversion unit having a second light source, a second wavelength conversion region that receives light emitted from the second light source and emits light of a wavelength different from the wavelength of the received light, and a second non-conversion region that emits the light received from the second light source without converting the wavelength of the light; and a second optical system that forms an image of the second wavelength conversion region of the second wavelength conversion unit; Equipped with The first wavelength conversion unit alternates between the first wavelength conversion region and the first non-conversion region at a position where light from the first light source is irradiated, and emits light of different wavelengths in a time-division manner. The second wavelength conversion unit alternates between the second wavelength conversion region and the second non-conversion region at a position where light from the second light source is irradiated, and emits light of different wavelengths in a time-division manner. A relative moving speed between a first irradiation spot of light emitted from the first light source on the first wavelength conversion unit and the first wavelength conversion unit is defined as v1. A relative moving speed between a second irradiation spot of light emitted from the second light source on the second wavelength conversion unit and the second wavelength conversion unit is defined as v2. where S1 is a diameter that is the size of the irradiation spot, S2 is a diameter that is the size of the second irradiation spot, and Δt is a rotational deviation between the first wavelength conversion unit and the second wavelength conversion unit, then a period T1 during which the first irradiation spot passes through the boundary between the first wavelength conversion region and the first non-conversion region is T1=S1 / v1, and a period T2 during which the second irradiation spot passes through the boundary between the second wavelength conversion region and the second non-conversion region is T2=S2 / v2, and the second light source irradiates light onto the boundary between the second wavelength conversion region and the second non-conversion region during the period T1 during which the first irradiation spot passes through the boundary between the first wavelength conversion region and the first non-conversion region so as to satisfy 0≦Δt<2×T2, The aforementioned The first optical system and the second optical system The optical system is No. 1 Image of wavelength conversion region and an image of the second wavelength conversion region. of , at the entrance aperture of the light uniformizing element Adjacent to or overlapping each other. [Effects of the Invention]

[0009] According to the present invention, it is possible to improve the light utilization efficiency of the light source and to emit bright light. [Brief explanation of the drawings]

[0010] [Figure 1A] FIG. 1A is a schematic diagram of a projection device according to a first embodiment. [Figure 1B] FIG. 1B is a diagram illustrating an example of the configuration of a light source device of the projection device according to the first embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a wavelength conversion element included in the light source device according to the first embodiment. [Figure 3] FIG. 3 is a schematic diagram illustrating an example of the configuration of the light source device according to the first embodiment. [Figure 4] FIG. 4 is a schematic diagram showing an example of the configuration of the wavelength conversion light source unit included in the light source device according to the first embodiment. [Figure 5] FIG. 5 is a diagram for explaining an example of a basic characteristic part of the light source device according to the first embodiment. [Figure 6] FIG. 6 is a diagram for explaining an example of an operation for adjusting the timing of irradiating the wavelength conversion element with light in the light source device according to the first embodiment. [Figure 7A] Figure 7A is a diagram for explaining an example of the timing of driving the output of excitation light from the first and second light source units by the projection device of the first embodiment, the timing of outputting a rotation signal of the wavelength conversion element, and the timing of emitting fluorescent light emitted by the wavelength conversion element. [Figure 7B] FIG. 7B is a diagram for explaining an example of output timing of a rotation signal for the wavelength conversion element and emission timing of fluorescent light emitted by the wavelength conversion element in the projection device according to the first embodiment. [Figure 7C]FIG. 7C is a diagram illustrating an example of output timing of a rotation signal for the wavelength conversion element and emission timing of fluorescent light emitted by the wavelength conversion element in the projection device according to the first embodiment. [Figure 8A] FIG. 8A is a diagram for explaining an example of a pattern in which the boundary of a wavelength conversion element passes through an irradiation spot in the projection device according to the first embodiment. [Figure 8B] FIG. 8B is a diagram for explaining an example of a pattern in which the boundary of the wavelength conversion element passes through the irradiation spot in the projection device according to the first embodiment. [Figure 8C] FIG. 8C is a diagram for explaining an example of a pattern in which the boundary of the wavelength conversion element passes through the irradiation spot in the projection device according to the first embodiment. [Figure 8D] FIG. 8D is a diagram for explaining an example of a pattern in which the boundary of the wavelength conversion element passes through the irradiation spot in the projection device according to the first embodiment. [Figure 9] FIG. 9 is a diagram illustrating the spot size of excitation light irradiated onto a wavelength conversion element in the projection device according to the first embodiment. [Figure 10] FIG. 10 is a diagram showing an example of the configuration of a wavelength conversion element included in a light source device according to the first modification. [Figure 11] FIG. 11 is a diagram showing an example of image formation on the light uniformizing element when the image of the first wavelength conversion region and the image of the second wavelength conversion region are completely superimposed on each other in the projection device according to the second embodiment. [Figure 12A] FIG. 12A is a diagram showing an example of the configuration of a phosphor wheel included in a light source device according to the third embodiment. [Figure 12B] FIG. 12B is a diagram illustrating an example of the configuration of the phosphor wheel included in the light source device according to the first embodiment. [Figure 12C] FIG. 12C is a diagram illustrating an example of the configuration of a phosphor wheel included in the light source device according to the first embodiment. [Figure 12D] FIG. 12D is a diagram illustrating an example of the configuration of a phosphor wheel included in the light source device according to the first embodiment. [Figure 13] FIG. 13 is a diagram for explaining an example of a process for forming an image of wavelength-converted light in a light source device according to the fourth embodiment. [Figure 14] FIG. 14 is a diagram illustrating an example of the configuration of a light source device according to the fifth embodiment. [Figure 15] FIG. 15 is a diagram for explaining an example of the timing of driving the first and second excitation light sources to output excitation light and the timing of emitting fluorescent light from the wavelength conversion element in the projection device according to the fifth embodiment. [Figure 16] FIG. 16 is a diagram illustrating an example of the configuration of a light source device according to the sixth embodiment. [Figure 17] Figure 17 is a diagram for explaining an example of the timing of driving the output light of excitation light from the excitation light source by the light source device of the sixth embodiment, and the timing of emitting fluorescent light (e.g., blue or red laser light) from the wavelength conversion element. [Figure 18] FIG. 18 is a diagram for explaining an example of a method for forming an image of a wavelength conversion region by the light source device according to the present embodiment. [Figure 19] FIG. 19 is a diagram for explaining an example of a method for forming an image of a wavelength conversion region by the light source device according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of a light source device and a projection device will be described in detail with reference to the accompanying drawings.

[0012] (First embodiment) 1A is a schematic diagram of a projection device according to a first embodiment. The projection device 1 according to this embodiment is a projector or the like, and includes a housing 10, a light source device 20, a light uniformizing element 30, an illumination optical system 40, an image forming element (image display element) 50, and a projection optical system 60.

[0013] The housing 10 houses a light source device 20, a light uniformizing element 30, an illumination optical system 40, an image forming element 50, and a projection optical system 60.

[0014] The light source device 20 emits light containing wavelengths corresponding to the respective colors of RGB, for example. The internal configuration of the light source device 20 will be described in detail later.

[0015] The light homogenizing element 30 homogenizes the light by mixing the light emitted from the light source device 20. As the light homogenizing element 30, for example, a light tunnel formed by combining four mirrors, a rod integrator, a fly's eye lens, or the like is used.

[0016] The illumination optical system 40 substantially uniformly illuminates the image forming element 50 with the light homogenized by the light homogenizing element 30. The illumination optical system 40 has, for example, one or more lenses and one or more reflecting surfaces.

[0017] The image forming element 50 has a light valve such as a digital micromirror device (DMD), a transmissive liquid crystal panel, or a reflective liquid crystal panel. The image forming element 50 forms an image by modulating the light illuminated by the illumination optical system 40 (light from the light source optical system of the light source device 20). In other words, the image forming element 50 functions as an example of a spatial modulator that turns on and off the light for each pixel of the image formed by the light source device 20 to form an image.

[0018] The projection optical system 60 enlarges and projects the image formed by the image forming device 50 onto a screen (projection surface) 70. The projection optical system 60 has, for example, one or more lenses.

[0019] 1B is a diagram showing an example of the configuration of a light source device of a projection device according to the first embodiment. Light source device 20 according to this embodiment has wavelength conversion light source units A and B. In the following explanation, the configuration of wavelength conversion light source unit A will be described, but wavelength conversion light source unit B will also have a similar configuration.

[0020] The wavelength conversion light source section A has a first light source unit composed of 2x4 semiconductor lasers LD1 and LD2. Light (light beams, light source light) emitted from the first light source unit (an example of a light source) is condensed by a collimator lens CL and guided to a dichroic mirror DM by an optical system of condensing elements L1 and L2. The light source light guided to the dichroic mirror DM is reflected by the dichroic mirror DM and irradiated onto a first wavelength conversion region A1 of a wavelength conversion element (e.g., a phosphor, an example of a wavelength conversion unit) F1 formed on a substrate C.

[0021] An image of the wavelength conversion region (first wavelength conversion region A1) of the wavelength conversion element F1, where the light from the light source reaches, is formed at a conjugate position in an imaging relationship by the optical elements L3, L4 and the mirrors M1, M2, etc. The conjugate position is a position where an image of the wavelength-converted light (image of the first wavelength-converted light) located in the first wavelength conversion region A1 shown in Fig. 1 is formed. Here, the wavelength-converted light is light whose wavelength has been converted by the wavelength conversion element F1.

[0022] On the other hand, a second wavelength conversion region A2 of a wavelength conversion element (phosphor) F2, which is different from the first wavelength conversion region A1 of the wavelength conversion element F1, is irradiated with light source light from a second light source unit (an example of a light source), and an image of the wavelength-converted light (an image of the second wavelength-converted light) that is conjugate with the second wavelength conversion region A2 is formed adjacent to (or superimposed on) the image of the first wavelength-converted light by optical elements L3, L4 and mirrors M1, M2, etc. In this embodiment, the first wavelength conversion region A1 and the second wavelength conversion region A2 function as an example of a wavelength conversion region that receives light emitted from the first and second light source units and emits light of a wavelength different from the wavelength of the received light. In addition, the collimator lens CL, the focusing elements L1, L2, the optical elements L3, L4, the dichroic mirror DM, and the mirrors M1, M2 function as a first optical system 501 (see Figure 5) and a second optical system 502 (see Figure 5) that form images of the first wavelength conversion region A1 and the second wavelength conversion region A2.

[0023] The combined image of the first wavelength-converted light and the second wavelength-converted light is located at the entrance opening of the light uniformizing element 30, indicated by the dashed line, and is then reflected and uniformized within the light uniformizing element 30. The light source device 20 according to this embodiment is characterized in that the first light source unit and the second light source unit emit light source light to the first and second wavelength conversion regions A1 and A2 of the wavelength conversion elements (phosphors) F1 and F2 at the same or approximately the same timing. The first optical system 501 (see FIG. 5) and the second optical system 502 (see FIG. 5) form a single image by placing the image of the first wavelength conversion region A1 and the image of the wavelength conversion region A2 adjacent to or overlapping each other. This increases the amount of light emitted from the light source device 20 and reduces the thermal load on the wavelength conversion elements F1 and F2, thereby improving the light utilization efficiency of the first and second light source units and enabling the emission of bright light.

[0024] The first and second light source units may be any light source that emits excitation light for the wavelength conversion elements F1 and F2, such as light in the blue or ultraviolet region. Specifically, the first and second light source units function as an example of a plurality of excitation light sources that simultaneously irradiate the first wavelength conversion region A1 and the second wavelength conversion region A2 with light. In this embodiment, the first and second light source units may each have a single LD, or may be an LD array in which LDs are arranged in multiple rows to form a rectangular shape. In this embodiment, the first and second light source units are a 2 x 4 array of eight LDs, but may also be a multi-chip type. In this embodiment, the same light source unit is used as the first and second light source units, but two light source units may also be used, with 4 x 4 LDs split by a mirror or separated by a half mirror.

[0025] In addition, in this embodiment, the first wavelength conversion region A1 and the second wavelength conversion region A2 of the wavelength conversion elements F1 and F2 are each composed of wavelength conversion sections formed on separate substrates C, but this is not limited thereto and they may be formed on the same substrate C. A suitable configuration for the substrate C is a disk-shaped substrate having a higher thermal conductivity than the phosphor, such as a ceramic or metal substrate, on which the phosphor is coated or fixed with an adhesive. The substrate C may also be disk-shaped and rotated around its center as a central axis, with the phosphor (wavelength conversion elements F1 and F2) formed along the circumference, and the phosphor (wavelength conversion elements F1 and F2) moved by the rotation.

[0026] 2 is a diagram showing an example of the configuration of a wavelength conversion element included in a light source device according to the first embodiment. As shown in FIG. 2, the wavelength conversion element F1 according to the present embodiment is a phosphor wheel on which at least two segments are formed: a phosphor region 201-1 (first wavelength conversion region A1) that is a region of a wavelength conversion member (phosphor), and a reflective region 202-1 that reflects light emitted from the first light source unit (in other words, a non-conversion region that outputs light received from the first light source unit without converting the wavelength). Similarly, the wavelength conversion element F2 is a phosphor wheel on which at least two segments are formed: a phosphor region 201-2 (second wavelength conversion region A2) that is a region of a wavelength conversion member (phosphor), and a reflective region 202-2 that reflects light emitted from the second light source unit (in other words, a non-conversion region that outputs light received from the second light source unit without converting the wavelength). In the following description, when there is no need to distinguish between the phosphor regions 201-1 and 201-2, they will be referred to as phosphor regions 201, and when there is no need to distinguish between the reflective regions 202-1 and 202-2, they will be referred to as reflective regions 202.

[0027] The wavelength conversion element F1 alternates between the phosphor region 201-1 and the reflective region 202-1 at an irradiation spot where light from the first light source unit is irradiated, and emits light of different wavelengths in a time-division manner. The wavelength conversion element F2 alternates between the phosphor region 201-2 and the reflective region 202-2 at an irradiation spot where light from the second light source unit is irradiated, and emits light of different wavelengths in a time-division manner.

[0028] In this case, it is preferable that the first and second light source units are light sources that emit blue light. In addition, in the light source device 20 according to this embodiment, a light absorbing or reflecting member is disposed on the wheels of the wavelength conversion elements F1 and F2 or on the member that supports and rotates the wheels, and the rotation speeds of the two wheels are made the same by checking with a photocoupler, etc.

[0029] Furthermore, in light source device 20 according to this embodiment, the first and second light source units irradiate the boundaries between phosphor regions 201-1 and 201-2 and reflective regions 202-1 and 202-2 with light at approximately the same timing. This shortens the spoke time, enabling light source device 20 to be bright and highly efficient in light utilization. Alternatively, light source device 20 according to this embodiment aligns the irradiation timing of the light source light from the first light source unit and the second light source unit so that the boundary between phosphor region 201-2 and reflective region 202-2 crosses the other irradiation spot at least within the time it takes for the boundary between phosphor region 201-1 and reflective region 202-1 to cross the other irradiation spot.

[0030] As described above, a configuration including the first and second light source units, the first and second optical systems 501 and 502 (see FIG. 5) that guide the light source light emitted from the first and second light source units to the wavelength conversion elements F1 and F2, the wavelength conversion elements F1 and F2, and elements that form images of the wavelength conversion regions of the wavelength conversion elements F1 and F2 is referred to as wavelength conversion light source units A and B. As shown in FIG. 1B, the light source device 20 according to this embodiment synthesizes the conjugate images formed by the two pairs of wavelength conversion light source units A and B by using two mirrors M2 that are angled at approximately 90 degrees to bring the two conjugate images adjacent to each other to form a single image.

[0031] Fig. 3 is a schematic diagram showing an example of the configuration of a light source device according to the first embodiment. As shown in Fig. 3, the light source device 20 according to this embodiment has wavelength conversion light source units A and B, a light path combining element 80, and a light homogenizing element 30. The wavelength conversion light source units A and B are configured according to a basic design concept (the direction of reflection, etc. may differ), and emit a light beam with a predetermined shape.

[0032] The light beams emitted from the wavelength conversion light source units A and B are deflected by the light path combining element 80 and enter the incident surface of the light uniformizing element 30. The light beams that enter the light uniformizing element 30 from the incident surface propagate inside the light uniformizing element 30 while being repeatedly reflected, and are emitted from the exit surface. In the light source device 20 according to this embodiment, the light beams emitted from the wavelength conversion light source units A and B are reflected multiple times inside the light uniformizing element 30, thereby forming a uniform surface light source on the exit surface. Note that the light uniformizing element 30 can be a light tunnel with a hollow interior and a mirrored inner surface, a rod formed into a rectangular column made of a transparent material such as glass, or the like.

[0033] 4 is a schematic diagram showing an example of the configuration of a wavelength conversion light source unit included in the light source device according to the first embodiment. The wavelength conversion light source units A and B include light sources 21 (including LD1 and LD2) that are solid-state light sources, collimator lenses CL provided corresponding to each light source 21, a first lens group 23 (light-collecting elements L1 and L2), a dichroic mirror DM, a second lens group 25 (optical element L3), wavelength conversion elements (phosphor wheels) F1 and F2, a third lens group 27 (optical element L4), a light path combining element 80, a color wheel (not shown), and the like. The wavelength conversion light source units A and B are arranged in this order in the propagation direction of the excitation light emitted from the light source 21.

[0034] The light source 21 emits, for example, light in the blue band with a central wavelength of 455 nm in emission intensity as excitation light for exciting the phosphors included in the wavelength conversion elements F1 and F2. The blue light emitted from the light source 21 is linearly polarized with a constant polarization state and is arranged to be S-polarized relative to the polarizing beam splitter (dichroic mirror DM). The wavelength band is not limited to light in the blue band as long as it is light of a wavelength that can excite the wavelength conversion elements F1 and F2. Although the light source 21 uses multiple laser light sources as an example, it may also be a single laser light source. When the light source 21 is a multiple laser light source, the light source 21 may be a light source unit arranged in an array on a substrate, but is not limited to this.

[0035] The excitation light emitted from the multiple light sources 21 is converted into approximately parallel light by the collimator lenses CL corresponding to each light source 21. The approximately parallel excitation light passes through the first lens group 23 and is guided to the dichroic mirror DM. The dichroic mirror DM is a parallel-flat glass plate, and its incident surface is coated to reflect the wavelength band of the excitation light and transmit the fluorescent light generated by the wavelength conversion elements F1 and F2 so that it functions as a dichroic mirror DM. The light-guiding member may also be made of transparent resin. The center of the dichroic mirror DM is shifted with respect to the optical axis of the second lens group 25, so that the excitation light emitted from the light source 21 is incident at an angle with respect to the normal to the phosphor wheel (wavelength conversion elements F1 and F2).

[0036] The excitation light reflected by the dichroic mirror DM is guided to the wavelength conversion elements F1 and F2 by the second lens group 25. The excitation light reflected by the reflective regions 202-1 and 202-2 of the wavelength conversion elements F1 and F2 passes through the second lens group 25 again, passes through the opposite side of the dichroic mirror DM with respect to the optical axis of the second lens group 25, passes through the third lens group 27, is deflected by the optical path combining element 80, and enters the light homogenizing element 30.

[0037] In addition, the fluorescent light emitted when excitation light is incident on the phosphor regions 201-1, 201-2 of the wavelength conversion elements F1, F2 is converted into approximately parallel light by the second lens group 25, passes through the light-guiding member, is refracted by the third lens group 27 so as to be focused near the light uniformizing element 30, is deflected by the light path combining element 80, and enters the light uniformizing element 30 (light tunnel).

[0038] Next, an example of the basic characteristic parts of the light source device 20 according to this embodiment will be described with reference to Fig. 5. Fig. 5 is a diagram for explaining an example of the basic characteristic parts of the light source device according to the first embodiment. Fig. 5(a) is a diagram showing a conceptual configuration diagram of the light source device 20 according to this embodiment from another perspective. Fig. 5(b) is a diagram showing how an image of an excitation light source is formed near the entrance of the light uniformizing element 30. Fig. 5(c) is a diagram showing how fluorescent light is formed near the entrance of the light uniformizing element 30.

[0039] In the light source device 20 according to this embodiment, an image of the first wavelength conversion region A1 on the wavelength conversion element F1 is formed by the first optical system 501 near the position of the aperture of the light uniformizing element 30. If the first optical system 501 has a substantially circular aperture, its image circle will be a circle similar to the lens aperture. The image circle of the first optical system 501 is formed near the position of the aperture of the light uniformizing element 30. On the other hand, an image of the second wavelength conversion region A2 formed by the second optical system 502 is formed as an image of the phosphor region 201-2 of the wavelength conversion element F2, superimposed on the image of the first wavelength conversion region A1 (the image of the phosphor region 201-1 of the wavelength conversion element F1).

[0040] Here, when blue light emitted as excitation light from the light source 21 is reflected by the reflection regions 202-1 and 202-2 of the wavelength conversion elements F1 and F2, as shown in Fig. 5(b), spotted excitation light source images are formed in the imaging range, which is the image circle of the first optical system 501 and the second optical system 502, according to the number of excitation light sources 21. The light source 21 is illustrated assuming a 2 x 4 array of eight LDs, but the number and arrangement of LDs are not limited to this.

[0041] Specifically, the image of wavelength conversion light source unit A condensed on wavelength conversion element F1 is re-imaged and formed as eight spots as shown in Figure 5(b) within an image circle at a position conjugate with the entrance of light uniformizing element 30. Meanwhile, the image of wavelength conversion light source unit B is also reflected by the phosphor wheel (wavelength conversion element F2) and formed within the image circle of wavelength conversion light source unit B which partially overlaps with the image circle of wavelength conversion light source unit A. Note that, as stated again, LD1 and LD2 are not limited in any way to the shapes, arrangements, or number of arrangements.

[0042] At the conjugate position of the light homogenizing element 30, fluorescent light is generated around the spot of excitation light, and as shown in FIG. 5(c), the fluorescent light forms an image of the fluorescent light within the image circle of each wavelength conversion light source unit A, B in an arrangement similar to that of the excitation light image. This fluorescent light image becomes a fluorescent spot larger than the excitation spot size because the spot of excitation light is internally scattered by the wavelength conversion elements F1, F2. Therefore, as shown in FIG. 5(c), at the conjugate position, each spot is formed as if it were connected to another. The optical system is designed so that two adjacent 2 × 4 clusters of fluorescent light images are formed and fit almost within the entrance opening of the light homogenizing element 30.

[0043] Next, an example of the operation of synchronizing the timing of light irradiation onto the wavelength conversion elements F1 and F2 in the light source device 20 according to the present embodiment and an example of the effect thereof will be described with reference to FIG. 6. FIG. 6 is a diagram for explaining an example of the operation of synchronizing the timing of light irradiation onto the wavelength conversion elements in the light source device according to the first embodiment. FIG. 6(a) shows the behavior of the image of wavelength-converted light within the time it takes for the boundary between the phosphor region 201-1 and the reflection region 202-1 to cross the irradiation spot in a conventional light source device, that is, in a light source device having only one phosphor wheel. In order to obtain the required irradiation power, the light source unit, for example, focuses irradiation light from a 4×4 LD unit and irradiates the spot light.

[0044] 6(b) shows the behavior of the images of the first and second wavelength-converted lights during the time it takes for the boundary between the phosphor region 201-1 and the reflective region 202-1 and the boundary between the phosphor region 201-2 and the reflective region 202-2 to cross the irradiation spot when the light emitted from the light source 21 is split into two and each of the split lights is simultaneously irradiated onto a separate phosphor wheel (wavelength conversion elements F1, F2) in the light source device 20 according to this embodiment. As shown in FIG. 5(b), the upper two rows of irradiation spots irradiated onto the light uniformizing element 30 are images of the first wavelength-conversion region A1, and the lower two rows of irradiation spots irradiated onto the light uniformizing element 30 are images of the second wavelength-conversion region A2.

[0045] In the light source device 20 according to this embodiment, because the phosphor wheels (wavelength conversion elements F1, F2) rotate, there is a finite time between the boundary between the reflective region 202-1 and the phosphor region 201-1 and the boundary between the reflective region 202-1 and the phosphor region 201-2 approaching the illumination spot and completely crossing the illumination spot. This time is called the spoke time, and it is the time during which the wavelength of blue light switches to the wavelength of the converted light, i.e., the period during which color mixing occurs. The shorter the spoke time, the higher the light utilization efficiency and the greater the color purity.

[0046] 6(a) and 6(b), it is clear that the spoke time is halved when the light emitted from the light source 21 is split and each of the split light beams is simultaneously irradiated onto the first and second wavelength conversion regions A1 and A2. This shortens the time required to switch from the blue light wavelength to the wavelength-converted light, preventing loss of spoke time and color mixing, and realizing a light source device 20 and a projection device 1 with high light utilization efficiency.

[0047] Thus, according to the projection device 1 of the first embodiment, the amount of light emitted from the light source device 20 can be increased and the thermal load on the wavelength conversion elements F1 and F2 can be reduced, thereby increasing the light utilization efficiency of the first and second light source units and enabling the emission of bright light.

[0048] 7A is a diagram illustrating an example of the timing of driving the output of excitation light from the first and second light source units, the timing of outputting a rotation signal for the wavelength conversion element, and the timing of emitting fluorescent light from the wavelength conversion element in the projection device according to the first embodiment. FIGS. 7B and 7C are diagrams illustrating an example of the timing of outputting a rotation signal for the phosphor wheel (wavelength conversion element) in the projection device according to the first embodiment, and the timing of emitting fluorescent light from the phosphor wheel (wavelength conversion element). The phosphor wheel (wavelength conversion elements F1 and F2) shown in FIG. 2 has a phosphor region 201 and a reflective region 202 arranged on its circumference. The irradiation spot of the excitation light irradiated on the phosphor wheels F1 and F2 alternates between the wavelength conversion region 201 and the reflective region 202 as the phosphor wheels F1 and F2 rotate.

[0049] One frame period shown in Figure 7A is the period in which the phosphor wheels F1 and F2 make one rotation. One frame period is divided into a period in which the illumination spot illuminates the phosphor region 201 and a period in which the illumination spot illuminates the reflective region. As shown in Figure 7A, the phosphor wheels F1 and F2 output fluorescent light (indicated as "1" in the figure) during the period in which the illumination spot illuminates the phosphor region 201, and output blue light (indicated as "1" in the figure) during the period in which the illumination spot illuminates the reflective region 202.

[0050] Here, the light output from the first light source unit and the second light source unit is constant, so the timing at which the phosphor wheels F1 and F2 output the fluorescent light and the blue light depends on the timing at which the illumination spot illuminates the phosphor region 201 and the timing at which the illumination spot illuminates the reflective region 202.

[0051] The phosphor wheels F1 and F2 are equipped with rotation detection sensors that monitor the rotation speeds of the phosphor wheels F1 and F2 to control their rotation. In the example shown in FIG. 7A, the rotation detection sensor outputs a rotation signal (rotation signals F1f1, F1f2, and F1f3) when the illumination spot passes through the boundary between the reflective region 202-1 and the phosphor region 201-1 on the phosphor wheel F1. Similarly, the rotation detection sensor outputs a rotation signal (rotation signals F2f1, F2f2, and F2f3) when the illumination spot passes through the boundary between the reflective region 202-2 and the phosphor region 201-2 on the phosphor wheel F2. The light source device 20 of this embodiment controls the rotation of the phosphor wheels F1 and F2 based on the rotation signals of the phosphor wheels F1 and F2.

[0052] 7B shows an example in which the rotation of the phosphor wheels F1 and F2 is controlled so that the timing of the rotation signal of the phosphor wheel F1 and the rotation signal of the phosphor wheel F2 are synchronized. The rotation signals F1f1, F1f2, and F1f3 of the phosphor wheel F1 (wavelength conversion element F1) are controlled to rotate at the same timing as the rotation signals F2f1, F2f2, and F2f3 of the phosphor wheel F2 (wavelength conversion element F2). Therefore, the timing at which the light output from the phosphor wheels F1 and F2 switches from blue light to fluorescent light is synchronized. This allows the output of the light combined by the light path combining element 80 to switch from blue light to fluorescent light in a short time. As a result, controlling the rotation of the phosphor wheels F1 and F2 using rotation signals can shorten the color mixing period (spoke time), which is the period during which the blue light and fluorescent light output from the light source device 20 mix together.

[0053] 7C is a diagram illustrating the timing of the blue light and fluorescent light output by light source device 20 when the rotation signal for phosphor wheel F1 and the rotation signal for phosphor wheel F2 are out of sync. The diagram illustrates a case in which rotation signals F2f1, F2f2, and F2f3 are delayed relative to rotation signals F1f1, F1f2, and F1f3. Therefore, the timing at which the illumination spot irradiates excitation light onto the boundary between reflective region 202-1 and fluorescent region 201-1 of phosphor wheel F1 is earlier than the timing at which the illumination spot irradiates the boundary between reflective region 202-2 and phosphor region 201-2 of phosphor wheel F2.

[0054] Therefore, the timing at which phosphor wheel F1 outputs blue light and fluorescent light is earlier than the timing at which phosphor wheel F2 outputs blue light and fluorescent light. As a result, the period (spoke time) during which the light combined by light path combining element 80 and output from light source device 20 switches from blue light to fluorescent light becomes longer, and the period during which blue light and fluorescent light mix (color mixing period) becomes longer. If the color mixing period becomes longer, measures such as turning off the output of light source device 20 during the color mixing period become necessary, resulting in a decrease in light utilization efficiency. As shown in FIG. 7B, light source device 20 of the present embodiment controls the rotation of phosphor wheels F1 and F2 based on the rotation signals of phosphor wheels F1 and F2, thereby shortening the color mixing period and improving light utilization efficiency.

[0055] The color mixing period of the light output by the light source device 20 also depends on the size of the irradiation spot of the excitation light irradiated onto the phosphor wheels F1 and F2. FIGS. 8A to 8D are diagrams illustrating an example of the relationship between the size of the irradiation spot irradiated onto the phosphor wheel (wavelength conversion element), the timing at which the irradiation spot passes through the boundary between the reflective region and the fluorescent region, and the fluorescent light output by the light source device in the light source device according to the first embodiment. In FIGS. 8A to 8D, the vertical axis represents the light output (relative value) from the phosphor wheels (wavelength conversion elements F1 and F2), and the horizontal axis represents time. S represents the diameter, which is the size of the irradiation spot of the excitation light irradiated onto the phosphor wheels F1 and F2, and v represents the relative movement speed between the irradiation spot on the wavelength conversion elements F1 and F2 and the phosphor wheels F1 and F2. FIG. 9 is a diagram illustrating the diameter S of the spot of the excitation light irradiated onto the phosphor wheel in the light source device according to the first embodiment. FIG. 9 shows a schematic illustration of an irradiation spot when 2×4 semiconductor lasers are used as the first light source unit (or the second light source unit).

[0056] The individual intensity distribution of each semiconductor laser of the first light source unit (or the second light source unit) exhibits a Gaussian distribution, as shown in Figure 9. Therefore, the intensity distribution of the irradiation spot is a composite intensity distribution obtained by adding up each Gaussian distribution. In addition, the diameter of the irradiation spot at this time is 1 / e of the peak value of the composite intensity distribution. 2 In this embodiment, a circular irradiation spot will be described, but if the irradiation spot is elliptical or rectangular, the size of the irradiation spot is defined as the size of the irradiation spot in the relative movement direction (direction of movement speed v) between the phosphor wheels F1, F2 and the irradiation spot.

[0057] The time period T1 required for the illumination spot to pass through the boundary between the reflective area 202-1 and the phosphor area 201-1 of the phosphor wheel F1 is expressed as T1 = S / v. Similarly, the time period T2 required for the illumination spot to pass through the boundary between the reflective area 202-2 and the phosphor area 201-2 of the phosphor wheel F1 is expressed as T2 = S / v. The time periods T1 and T2 correspond to the color mixing periods (spoke times) of the phosphor wheels F1 and F2, respectively. Therefore, reducing the diameter S of the illumination spot is effective in shortening the color mixing period. As described with reference to FIG. 6, the light source device 20 of this embodiment has two phosphor wheels (wavelength conversion elements F1 and F2), which allows the spot size to be reduced by approximately half, thereby shortening the color mixing period by half.

[0058] When the rotation signals of the phosphor wheel (wavelength conversion element) F1 and the phosphor wheel (wavelength conversion element) F2 deviate by Δt, the relative positional deviation between the boundary between the reflective area 202-1 and the phosphor area 201-1 of the phosphor wheel F1 and the boundary between the reflective area 202-2 and the phosphor area 201-2 of the phosphor wheel F2 is expressed as Δt × v. Here, Δt is the absolute value of the deviation of the rotational signal and takes a positive or negative value. FIG. 8A illustrates the state where Δt = 0, in which the relative positional deviation between the boundary of the phosphor wheel F1 and the boundary of the phosphor wheel F2 is minimized (Δt × v = 0). In this state, the output of the combined fluorescent light rises steadily over a period T1. This period T1 is the spoke time, which is the color mixing period. The color mixing period in FIG. 8A is shortest, at T1 = T2.

[0059] FIG. 8B illustrates a state in which the relative positions of the boundaries of phosphor wheels F1 and F2 are shifted by approximately half the size of the illumination spot (Δt×v=S / 2). Similar to FIG. 8A, the output of the combined fluorescent light is gradually increasing, and the color mixing period is 1.5×T1 (=1.5×T2). FIG. 8C illustrates a state in which the relative positions of the boundaries of phosphor wheels F1 and F2 are shifted by the size of the illumination spot (Δt×v=S). Similar to FIG. 8A, the output of the combined fluorescent light is gradually increasing, and the color mixing period is 2×T1 (=2×T2). Therefore, in the states of FIGS. 8A to 8C, i.e., within the range of 0≦Δt<2×T1 (=2×T2), the output of the combined fluorescent light during the color mixing period is in a monotonous increase state. Furthermore, by setting Δt within the above-mentioned range, the color mixing period (spoke time) can be shortened compared to the configuration shown in FIG. 6(a) in which a single wavelength conversion element is used.

[0060] Figure 8D illustrates a state in which the relative position between the boundary of phosphor wheel F1 and the boundary of phosphor wheel F2 is shifted by a larger amount than the size of the illumination spot (a state in which Δt×v>S). The output of the combined fluorescent light during the color mixing period tends to increase stepwise, and the color mixing period exceeds 2×T1, resulting in a decrease in light utilization efficiency. Therefore, by setting the range of 0≦Δt<2×T1 (=2×T2), i.e., the range shown in Figures 8A to 8C, the color mixing period (spoke time) can be sufficiently shortened, thereby improving light utilization efficiency.

[0061] Note that the above example describes an example in which the deviation Δt in the rotation signals of the phosphor wheels F1 and F2 is controlled according to the size of the irradiation spot and the relative speed v between the irradiation spot and the phosphor wheels F1 and F2. However, it is also possible to control the timing at which the irradiation spot irradiates the boundary between the reflective area and the phosphor area according to the number of segments of the phosphor area and the reflective area on the phosphor wheel, the diameter and rotation speed of the phosphor wheel, and the spot size.

[0062] As described above, the conditions under which the time required for mixing fluorescent light and blue light to be mixed can be shortened and light utilization efficiency can be improved are the conditions shown in Figures 8A to 8C under which excitation light is irradiated onto wavelength conversion elements F1 and F2. These conditions will be explained in terms of the relationship between the period T1 during which excitation light is irradiated onto the boundary between phosphor region 201-1 and reflective region 202-1 of phosphor wheel (wavelength conversion element) F1, and the period T2 during which excitation light is irradiated onto the boundary between phosphor region 201-2 and reflective region 202-2 of phosphor wheel (wavelength conversion element) F2.

[0063] Under the conditions of FIG. 8A, the period T1 during which excitation light is irradiated onto the boundary of the phosphor wheel (wavelength conversion element) F1 coincides with the period T2 during which excitation light is irradiated onto the boundary of the phosphor wheel (wavelength conversion element) F2. During the period T1, excitation light is irradiated onto the boundary of the phosphor wheel F1 and the boundary of the phosphor wheel F2. Under the conditions of FIG. 8B, the start time of the period T2 is earlier than the end time of the period T1, and there is a period during which the periods T1 and T2 overlap. Therefore, under the conditions of FIG. 8B, excitation light is irradiated onto the boundary of the phosphor wheel F1 and the boundary of the phosphor wheel F2 from the start time of the period T2 to the end time of the period T1. Under the conditions of FIG. 8C, the end time of the period T1 coincides with the start time of the period T2. At the end time of the period T1, excitation light is irradiated onto the boundary of the phosphor wheel F1 and the boundary of the phosphor wheel F2. 8A to 8C can be said to be a state in which excitation light is irradiated onto the boundary of the phosphor wheel F1 and the boundary of the phosphor wheel F2 during at least a part of the period T1. That is, during the period in which light is irradiated onto the boundary between the phosphor region (wavelength conversion region) 201 and the reflective region 202 of one of the phosphor wheels (wavelength conversion elements) included in the phosphor wheels (wavelength conversion elements) F1 and F2, the light source 21 irradiates light onto the boundary between the phosphor region (wavelength conversion region) 201 and the reflective region 202 of the other wavelength conversion element included in the phosphor wheels (wavelength conversion elements) F1 and F2.

[0064] Here, the preferred conditions of Figures 8A to 8C are shown as an example when there are two phosphor wheels (wavelength conversion elements) (wavelength conversion elements F1 and F2). However, as shown in Figures 12A to 12D described below, when two or more excitation light irradiation spots are irradiated onto one wavelength conversion element, a similar state can be set by setting a period T1 for irradiating excitation light onto the boundary between phosphor region 201-1 and reflective region 202-1 and a period T2 for irradiating excitation light onto the boundary between phosphor region 201-2 and reflective region 202-2.

[0065] (Modification 1 of the first embodiment) In the first embodiment, the phosphor wheels F1 and F2, which are wavelength conversion elements, have a reflective region 202 and a phosphor region 201, as shown in FIG. 2. Here, the phosphor region 201 may be further divided into regions made of a plurality of different phosphors. FIG. 10 is a diagram showing an example of the configuration of a wavelength conversion element included in a light source device according to Modification 1. As shown in FIG. 10, in this modification, the phosphor region 201 is divided into a phosphor region 201a (an example of a second region) and a phosphor region 201b (an example of a first region). In this case, the phosphor region 201a may be made of a phosphor that emits green fluorescence (an example of light of a first wavelength), and the phosphor region 201b (an example of a second region) may be made of a phosphor that emits fluorescence in a yellow wavelength range (an example of light of a second wavelength). By dividing the phosphor region 201 of the phosphor wheels F1, F2 into a plurality of phosphor regions 201a, 201b that emit different colors in this manner, it is possible to output fluorescent light of different colors from one phosphor wheel F1, F2.

[0066] At this time, a color mixing period (spoke time) occurs at boundary B3 between phosphor region 201a and phosphor region 201b of phosphor wheels F1 and F2, in which the green fluorescent light and the yellow fluorescent light mix, similar to the color mixing period that occurs when the irradiation spot of excitation light irradiates (passes through) boundary B1, B2 between reflection region 202 and phosphor region 201. Conditions for shortening the color mixing period (spoke time) of the green and yellow fluorescent light that occurs at boundary B3 can be set in the same way as in Figures 8A to 8C.

[0067] As shown in Figures 8A to 8C, if the period during which the irradiation spot of phosphor wheel F1 irradiates phosphor region 201a and phosphor region 201b is T1 and the period during which the irradiation spot of phosphor wheel F2 irradiates phosphor region 201a and phosphor region 201b is T2, the rotation of phosphor wheels F1 and F2 is controlled so that there is a period during which period T1 and period T2 overlap.

[0068] That is, the phosphor regions (wavelength conversion regions) of the phosphor wheels F1 and F2 include a phosphor region 201a (an example of a first region) that emits light in a green wavelength range (an example of light having a first wavelength) and a phosphor region 201b (an example of a second region) that emits light in a yellow wavelength range (an example of light having a second wavelength). The regions irradiated with the excitation light irradiation spot are switched between the phosphor region 201a and the phosphor region 201b, so that fluorescent light in the green wavelength range and fluorescent light in the yellow wavelength range are emitted in a time-division manner. During this time, the light source 21 irradiates the boundary B3 between the phosphor region 201a and the phosphor region 201b of the phosphor wheel F2 with light during the period in which it irradiates the boundary between the phosphor region 201a and the phosphor region 201b of the phosphor wheel F1 with light, thereby shortening the time required for mixing the green fluorescent light and the yellow fluorescent light. This improves the light utilization efficiency of the fluorescent light.

[0069] Although the example in which phosphor region 201 is divided into two phosphor regions, phosphor region 201a and phosphor region 201b, is shown, the number of divided phosphor regions is not limited to two. For example, it may be divided into three phosphor regions that emit fluorescence in the red, green, and yellow wavelength ranges, respectively. Furthermore, instead of reflective region 202, phosphor region 201 may be made of a phosphor that emits blue fluorescent light, and the excitation light may be light with a shorter wavelength than blue (for example, ultraviolet light) so as to emit blue fluorescent light.

[0070] (Second embodiment) In this embodiment, the image of the first wavelength conversion region and the image of the second wavelength conversion region are not placed next to each other, but are partially or completely superimposed. In the following explanation, the same configuration as in the first embodiment will not be described.

[0071] 11 is a diagram showing an example of image formation on a light uniformizing element when an image of the first wavelength conversion region and an image of the second wavelength conversion region are completely superimposed in a projection device according to the second embodiment. Fig. 11 shows the behavior of the images of the first and second wavelength-converted light during the time (i.e., spoke time) from when the irradiation spot, which has a finite size, starts to cross the boundary between the reflective region 202-1 and the phosphor region 201-1 and the boundary between the reflective region 202-2 and the phosphor region 201-2 until it passes through, and it can be seen that the crossing takes half the time of the spoke time in Fig. 6(a).

[0072] Here too, the effect of shortening the spoke time is maximized when the timing of irradiating the first wavelength conversion region A1 and the second wavelength conversion region A2 with light from the light source 21 is the same. As the irradiation timing is shifted, the spoke time becomes longer by the amount of the shift, but this time should be within the range of the time it takes for the spot light to cross the boundary between the phosphor region 201 and the reflective region 202 of the phosphor wheel.

[0073] In this way, the projection device 1 according to the second embodiment can achieve the same effects as those of the first embodiment.

[0074] (Third embodiment) This embodiment is an example in which a plurality of irradiation spots are formed on one phosphor wheel. In the following description, the same configuration as in the above-described embodiment will not be described.

[0075] The first and second embodiments are examples in which two phosphor wheels (wavelength conversion elements F1 and F2) are each provided with an irradiation spot, while the third embodiment is an example in which one phosphor wheel is arranged to simultaneously generate multiple irradiation spots (first irradiation spot and second irradiation spot).

[0076] FIG. 12A is a diagram illustrating an example of the configuration of a phosphor wheel included in a light source device according to a third embodiment. In this embodiment, the phosphor wheel has two periods of reflective regions 202 and phosphor regions 201 formed around the circumference of the phosphor wheel. That is, in this embodiment, one phosphor wheel has multiple phosphor regions 201. Each region is defined so that the time it takes for a first irradiation spot to cross the boundary between one reflective region 202-1 and the phosphor region 201-1 is approximately the same as the time it takes for a second irradiation spot to cross the boundary between the other reflective region 202-2 and the phosphor region 201-2. That is, in this embodiment, the phosphor wheel alternates between the phosphor region 201 and the reflective region 202 in the irradiation spot, emitting light of different wavelengths in a time-division manner. The light source 21 irradiates each of the multiple phosphor regions 201 with light at the boundary between the reflective region 202 and each of the multiple phosphor regions 201 at approximately the same timing. In this embodiment, the phosphor wheel includes a substrate C having a plurality of phosphor regions 201, reflective regions 202, and boundaries. That is, the phosphor wheel has the phosphor regions 201, reflective regions 202, and boundaries on a single substrate C.

[0077] As described above, according to the projection device 1 of the third embodiment, it is not necessary to synchronize the two phosphor wheels, and therefore there is no need to control the two phosphor wheels.

[0078] Example 1 In this example, multiple sets of reflective regions and phosphor regions are formed on two bands arranged along the direction from the rotation center of the phosphor wheel toward the outer diameter. In the following explanation, explanations of the same configuration as in the third embodiment will be omitted.

[0079] 12B to 12D are diagrams showing an example of the configuration of a phosphor wheel included in the light source device according to Example 1. In this example, as shown in FIG. 12B, the phosphor wheel has two bands arranged along a direction from the rotation center of the phosphor wheel toward the outer diameter thereof, and reflective regions 202 and phosphor regions 201 are formed on each of the bands. That is, in this example, similar to the third embodiment, one phosphor wheel has multiple phosphor regions 201. As shown in FIGS. 12C and 12D, each region is defined so that the time it takes for the first irradiation spot to cross the boundary between one reflective region 202-1 and phosphor region 201-1 and the time it takes for the second irradiation spot to cross the boundary between the other reflective region 202-2 and phosphor region 201-2 are substantially the same.

[0080] 12C shows a state in which the first and second irradiation spots cross the boundary between the reflective region 202 and the phosphor region 201. That is, in this embodiment, the phosphor wheel alternates between the phosphor region 201 and the reflective region 202 in the irradiation spot, emitting light of different wavelengths in a time-division manner. The light source 21 irradiates each of the plurality of phosphor regions 201 with light at the boundary between the reflective region 202 and the phosphor region 201 at approximately the same timing. Also, in this embodiment, the phosphor wheel includes a substrate C having a plurality of phosphor regions 201, a reflective region 202, and a boundary. That is, the phosphor wheel has the phosphor regions 201, the reflective region 202, and a boundary on a single substrate C.

[0081] 12B and 12C, the positions of the first and second irradiation spots are set on either side of the center of rotation of the phosphor wheel, but this is not necessarily limited to this position. For example, as shown in FIG. 12D, the boundary between phosphor region 201 and reflective region 202 does not have to be located symmetrically with respect to the center of rotation of the phosphor wheel, and the positions of the first and second irradiation spots can be set with some freedom. The boundary between phosphor region 201 and reflective region 202 may be determined in accordance with the layout of the optical system that forms the first and second irradiation spots.

[0082] On the other hand, in the projection device 1 according to the above embodiment, the timing for crossing the boundary between each of the plurality of phosphor regions 201 and the reflective region 202 may not be synchronized simply by assembling the device, because the physical positional error when forming the phosphor regions 201 and the reflective region 202 is not zero. To avoid this, the drive timing of the light source 21 may be adjusted during manufacture, for example, by monitoring the light emitted from the light source 21. In this case, if the adjustment amount for the drive timing of the light source 21 is recorded in a separate memory mounted on the projection device 1, the adjustment amount can be read from the memory when the projection device 1 is started, and the drive timing of the light source 21 can be controlled according to the adjustment amount, thereby accurately synchronizing the timing for crossing the boundary between each of the plurality of phosphor regions 201 and the reflective region 202.

[0083] As described above, with the projection device 1 according to the first embodiment, the rotation speed of the phosphor wheel can be controlled at the same rotation speed as when multiple phosphor wheels are used, which simplifies control. Furthermore, when applying the light source device 20 of this embodiment to the projection device 1, synchronized control with a color wheel or another light source is required, but since only one phosphor wheel is required, control is simplified. Furthermore, the degree of freedom in determining the location on the substrate C where the boundary between the phosphor region 201 and the reflective region 202 is to be located increases, which improves the degree of freedom in determining the positions of the first and second irradiation spots and the layout of the projection device 1.

[0084] The timing of irradiating the boundaries between the plurality of phosphor regions 201 and the reflective region 202 with an irradiation spot of excitation light depends on the positional accuracy of the irradiation spot and the positional accuracy of the boundaries between the phosphor regions 201-1, 201-2 and the reflective regions 202-1, 202-2 of the phosphor wheel. Light source device 20 of the present embodiment is preferably configured to irradiate the boundary between phosphor region 201-2 and reflective region 202-2 with an irradiation spot during at least a portion of the period during which the irradiation spot irradiates the boundary between phosphor region 201-1 and reflective region 202-1. This shortens the color mixing period (spoke time) of the combined light emitted from light source device 20.

[0085] Also in this example, similar to the first modification of the first embodiment, each of the plurality of phosphor regions 201-1 and 201-2 may be divided into phosphor region 201a and phosphor region 201b as shown in Fig. 10. In this case, light source device 20 may be configured so that the timing at which the irradiation spot of the excitation light irradiates boundary B3 between phosphor region 201a and phosphor region 201b is within the range of Figs. 8A to 8C. This makes it possible to shorten the color mixing period (spoke time) of the fluorescent light, thereby improving the light utilization efficiency of light source device 20.

[0086] (Fourth embodiment) In this embodiment, the light source device has a single light source unit, and the light emitted from the light source unit is split and irradiated onto the first wavelength conversion region and the second wavelength conversion region. In the following description, the same configuration as the above-mentioned embodiment will not be described.

[0087] FIG. 13 is a diagram illustrating an example of a process for forming an image of wavelength-converted light in a light source device according to a fourth embodiment. In this embodiment, light source light emitted from a light source 21 including 4×4 LDs in a single light source unit is collected by light collecting elements L1 and L2, and the light source light is split by a dichroic mirror DM2 (an example of a splitter) so that the power of the light source light is halved. The light source light split by the dichroic mirror DM2 is irradiated onto wavelength conversion elements F1 and F2, as in the above-described embodiments. In this embodiment, the first and second wavelength conversion regions A1 and A2 of the wavelength conversion elements F1 and F2 are static. This eliminates the need for a drive unit for rotating and moving the first and second wavelength conversion regions A1 and A2, thereby achieving a highly reliable light source device 20.

[0088] As described above, according to the projection device 1 of the fourth embodiment, a single light source unit is used to irradiate the wavelength conversion elements F1 and F2 with light source light, so there is no need to synchronize the irradiation timing when irradiating the wavelength conversion elements F1 and F2 with light source light from the multiple light sources 21.

[0089] (Fifth embodiment) In this embodiment, a light source unit for wavelength conversion is mainly used as a light source for emitting excitation light, and a separate light source unit is used that uses the light emitted from the light source as is without wavelength conversion. In the following explanation, explanations of the same configuration as in the above-mentioned embodiment will be omitted.

[0090] FIG. 14 is a diagram illustrating an example of the configuration of a light source device according to a fifth embodiment. As shown in FIG. 14, the light source device 20 according to this embodiment has a plurality of (two in this embodiment) first and second excitation light sources 101-1 and 101-2. The excitation light emitted from the first and second excitation light sources 101-1 and 101-2 is guided by dichroic mirrors DM1 and DM2 to the wavelength conversion element F1 and wavelength conversion element F2, respectively, to form irradiation spots. Furthermore, the first wavelength conversion region A1 of the wavelength conversion element F1 forms an image of the first wavelength conversion region A1 (in other words, an image of the first wavelength-converted light located in the first wavelength conversion region A1) by the first optical system 501. Furthermore, the second wavelength conversion region A2 of the wavelength conversion element F2 forms an image of the second wavelength conversion region A2 (in other words, an image of the second wavelength-converted light located in the second wavelength conversion region A2) by the second optical system 502. The image of the first wavelength conversion region A1 and the image of the second wavelength conversion region A2 are adjacent to or overlap each other to form one image.

[0091] The wavelength conversion elements F1 and F2 are phosphors arranged on a substrate C and are converted into light of wavelengths such as yellow, green, or red by excitation light. It has been known that when the wavelength conversion elements F1 and F2 are irradiated with excitation light from the first and second excitation light sources 101-1 and 101-2, not all of the energy of the excitation light is converted into light of wavelengths such as yellow, but rather some of it becomes heat, reducing the wavelength conversion efficiency. Therefore, the light source device 20 according to this embodiment is provided with heat dissipation members (heat sinks) H1 and H2 via the substrate C to dissipate heat from the wavelength conversion elements F1 and F2. Alternatively, the light source device 20 according to this embodiment may have the heat dissipation members H1 and H2 in direct contact with the wavelength conversion elements F1 and F2 (phosphors), or may have the heat dissipation members H1 and H2 adhered to each other using thermally conductive grease or the like to minimize thermal resistance.

[0092] Furthermore, in this embodiment, the light source device 20 does not combine a single wavelength conversion region onto which excitation light from the first and second excitation light sources 101-1 and 101-2 is irradiated, but rather separate wavelength conversion regions (first and second wavelength conversion regions A1 and A2). This improves the heat dissipation effect of the wavelength conversion elements F1 and F2, and also improves the wavelength conversion efficiency. In this case, the first and second wavelength conversion regions A1 and A2 are fixed and do not move, and the excitation light from the excitation light sources is irradiated onto the first and second wavelength conversion regions A1 and A2 at the same irradiation timing.

[0093] The light source device 20 according to this embodiment has a light source 102 that emits blue light in addition to the first and second excitation light sources 101-1 and 101-2, and is configured to combine (configure) the blue light with the imaging optical path of the fluorescent light at, for example, a dichroic mirror DM1. The dichroic mirror DM1 also serves as a folding mirror for the excitation light source, but may of course be a separate mirror.

[0094] FIG. 15 is a diagram for explaining an example of the timing of driving the first and second excitation light sources to output excitation light and the timing of emitting fluorescent light from the wavelength conversion element in the projection device according to the fifth embodiment.

[0095] The first and second excitation light sources 101-1 and 101-2 start emitting excitation light (LD output) in response to an emission start trigger signal Sr1. That is, the first excitation light source 101-1 synchronizes with this trigger signal Sr1 to synchronize the timing (output drive timing) and control the emission of excitation light. FIG. 15(A) is a time chart of the excitation light LD output of each excitation light source and the output of fluorescent light from the wavelength conversion elements F1 and F2 when the timing (output drive timing) of the first and second excitation light sources 101-1 and 101-2 are synchronized. The period from the trigger signal Sr1 to the next trigger signal Sr2 corresponds to one frame. As shown in FIG. 15(A), if the output drive timing of excitation light from the first and second excitation light sources 101-1 and 101-2 is synchronized, the start and stop of the output of fluorescent light from the wavelength conversion elements F1 and F2 is instantaneous.

[0096] However, if the output drive timing of the first and second excitation light sources 101-1 and 101-2 differs by a very small time difference Δt, the fluorescent light output from each of the first and second wavelength conversion regions A1 and A2 will be stepped by the time difference Δt, as shown in Figure 15(B). This time difference Δt is the spoke time required for switching from fluorescent light to another color (e.g., blue light). The time difference Δt can be reduced to nearly zero by adjusting the output drive timing, but a delay can also be added as needed. Since color mixing occurs during the spoke time, it is desirable to shorten the spoke time by turning off the light source or the display to increase color purity. However, depending on the application, color mixing may be actively created, and in that case, the time difference Δt can be made sufficiently long to create color mixing. In this case, the boundary between a single color and a mixed color is the spoke time, and this time can be minimized using this technology.

[0097] Thus, according to the projection device 1 of the fifth embodiment, the wavelength conversion regions onto which excitation light is irradiated from the first and second excitation light sources 101-1 and 101-2 are not one, but are separate wavelength conversion regions (first and second wavelength conversion regions A1 and A2), thereby improving the heat dissipation effect of the wavelength conversion elements F1 and F2 and also improving the wavelength conversion efficiency.

[0098] (Sixth embodiment) In this embodiment, the pumping light emitted from the pumping light source is divided into a plurality of divided pumping lights, and one of the divided pumping lights is irradiated onto one wavelength conversion element, and the other divided pumping light is irradiated onto the other wavelength conversion element. In the following description, the description of the same configuration as the above-mentioned embodiment will be omitted.

[0099] 16 is a diagram illustrating an example of the configuration of a light source device according to a sixth embodiment. In this embodiment, the output (power) of the excitation light from the excitation light source 101 is twice that of the first and second excitation light sources 101-1 and 101-2 of the light source device 20 according to the fifth embodiment. Furthermore, in this embodiment, dichroic mirrors DM1 and DM2 (an example of a splitter) split the excitation light emitted from the excitation light source 101 into two split excitation lights, and each of the split excitation lights is irradiated onto a separate wavelength conversion element F1 or F2 (the first wavelength conversion region A1 or the second wavelength conversion region A2). This allows the excitation light source 101 to start and stop emitting light using a simple power wiring configuration, without the need to drive the excitation light sources in series to suppress timing discrepancies in the output drive timing. As a result, there is no longer a time difference Δt between the emission timing of the fluorescent light from the wavelength conversion elements F1 and F2, and sharp fluorescent light with high wavelength conversion efficiency can be obtained.

[0100] Light source device 20 according to this embodiment has a light source 102 that emits blue light, separate from excitation light source 101, and is configured (combined) so that the blue light intersects with the imaging optical path of the fluorescent light at, for example, a dichroic mirror DM1. Dichroic mirror DM1 also serves as a folding mirror for excitation light source 101, but may of course be a separate entity. Light source 102, separate from excitation light source 101, is not limited to being a blue light source, and may be a green light source or a red light source.

[0101] Figure 17 is a diagram for explaining an example of the timing of driving the output light of excitation light from the excitation light source by the light source device of the sixth embodiment, and the timing of emitting fluorescent light (e.g., blue or red laser light) from the wavelength conversion element.

[0102] The excitation light source 101 starts emitting (emitting) excitation light in response to an emission start trigger signal Sr1. That is, the excitation light source 101 synchronizes with this trigger signal Sr1 to synchronize the timing (output drive timing) and control the emission of excitation light. When it is desired to stop the output of fluorescent light from the wavelength conversion elements F1 and F2 and output light from another light source 102, the light source device 20 according to this embodiment stops the output of excitation light from the excitation light source 101 in response to an excitation light drive stop signal St1. Alternatively, the light source device may stop the output of fluorescent light from the wavelength conversion elements F1 and F2 after a certain time has elapsed since the output of the trigger signal Sr1. Meanwhile, the light source 102 emitting blue light controls the start of emission of blue light, triggered by the excitation light drive stop signal St1 or an emission start signal from a controller that outputs the drive stop signal St.

[0103] If a time difference Δt occurs between the timing at which the excitation light source 101 stops emitting excitation light and the timing at which the other light source 102 starts emitting blue light, the emission of fluorescent light from the wavelength conversion elements F1 and F2 and the light (e.g., blue light) from the other light source 102 will be mixed, as shown in FIG. 17(B). This time difference Δt corresponds to the spoke time during color switching, as described in the above embodiment. When a time difference Δt occurs, the color mixing time increases accordingly, resulting in a decrease in color purity. In this case, control is required to turn off the light source for the duration of the time difference Δt so that no display is displayed, resulting in a significant decrease in light utilization efficiency. Therefore, the light source device 20 according to this embodiment can suppress a decrease in light utilization efficiency by controlling the timing at which the excitation light source 101 and the other light source 102 are driven.

[0104] As a result, according to the projection device 1 of the sixth embodiment, it is possible to start and stop the emission of the excitation light source 101 using a simple driving power wiring structure, without having to drive the excitation light sources in series in order to suppress deviations in the output drive timing of the excitation light sources. As a result, a state in which a time difference Δt occurs in the emission timing of the fluorescent light from the wavelength conversion elements F1 and F2 is eliminated, and sharp fluorescent light with high wavelength conversion efficiency can be obtained.

[0105] 18 and 19 are diagrams illustrating an example of a method for forming an image of a wavelength conversion region by a light source device according to this embodiment. In the above-described embodiment, in an example in which the light source device 20 uses two wavelength conversion light source units, the movement direction of the phosphor wheel (wavelength conversion elements F1 and F2) relative to the irradiation spot is determined so that the images (fluorescent light or light source light) of the secondary light sources (first wavelength conversion region A1, second wavelength conversion region A2) formed by the wavelength conversion light source units A and B are arranged vertically as shown in FIG. 6. However, as shown in FIG. 18, the movement direction of the phosphor wheel relative to the irradiation spot may be determined horizontally. For example, a mirror or the like may be used in the optical path until the image of the wavelength-converted light is formed at the conjugate position to determine the incident direction to the phosphor wheel, and the folded image may be rotated by 90°.

[0106] Although the light source device 20 according to the present embodiment includes two wavelength conversion light source units A and B, it may include two or more (three or four) wavelength conversion light source units. For example, as shown in FIG. 19, the light source device 20 may include four 2×2 light sources, four wavelength conversion regions, or four phosphor wheels (wavelength conversion elements). Alternatively, the light source device 20 may use two sets of phosphor holes (see FIG. 12) each having two or more segments of phosphor region 201 and reflective region 202, four phosphor regions 201, and four optical systems for forming the images thereof to form four images into a single image. In this case, the light source device 20 may be configured so that the boundaries between the four phosphor regions 201 and reflective region 202 pass through the position of the focused spot of the excitation light, as shown in FIG. 19. Depending on the direction in which the boundaries pass, the spoke time may be shortened by the number of boundaries provided. It goes without saying that the direction of the image of the wavelength-converted light can be set in various directions, and FIG. 19 shows one example.

[0107] In this way, by having multiple wavelength conversion light source units, the size of the wavelength conversion region that each unit is responsible for can be reduced, and the power of the excitation light received can also be reduced, thereby increasing the ratio of wavelength-converted light per unit of irradiation energy. In other words, the conversion efficiency can be increased. Although not shown, by applying the above light source device to a projection device that irradiates a spatial modulator and enlarges and projects the information formed on the spatial modulator using a projection lens or the like, an unprecedentedly efficient and bright projection device can be realized. [Explanation of symbols]

[0108] 1 Projection device 10. Cabinet 20 Light source device 21 Light source 23 First lens group 25 Second lens group 30 Light uniformizing element 40 Illumination optical system 50 Image forming element 60 Projection optical system 70 screens 80 Optical path combining element 201-1, 201-2 Phosphor region 202-1,202-2 Reflection area 501 1st optical system 502 Second optical system A,B Wavelength conversion light source A1 First wavelength conversion region A2 Second wavelength conversion region C board CL Collimator Lens DM, DM1, DM2 dichroic mirrors F1,F2 wavelength conversion element L1, L2 light-collecting element L3, L4 optical elements M1, M2 mirrors [Prior art documents] [Patent documents]

[0109] [Patent Document 1] Japanese Patent Application Publication No. 2019-184628

Claims

1. A first light source; a first wavelength conversion unit including: a first wavelength conversion region that receives light emitted from the first light source and emits light having a wavelength different from the wavelength of the received light; and a first non-conversion region that emits the light received from the first light source without converting the wavelength of the light; a first optical system that forms an image of the first wavelength conversion region of the first wavelength conversion unit; A second light source; a second wavelength conversion unit including: a second wavelength conversion region that receives light emitted from the second light source and emits light having a wavelength different from the wavelength of the received light; and a second non-conversion region that emits the light received from the second light source without converting the wavelength of the light; a second optical system that forms an image of the second wavelength conversion region of the second wavelength conversion unit, the first wavelength conversion unit alternates between the first wavelength conversion region and the first non-conversion region at a position where light from the first light source is irradiated, and emits light of different wavelengths in a time-division manner; the second wavelength conversion unit alternates between the second wavelength conversion region and the second non-conversion region at a position where light from the second light source is irradiated, and emits light of different wavelengths in a time-division manner; v1 is a relative moving speed between a first irradiation spot of light emitted from the first light source on the first wavelength converting unit and the first wavelength converting unit; a relative moving speed between the second irradiation spot of the light emitted from the second light source on the second wavelength converting unit and the second wavelength converting unit is defined as v2; The diameter of the first irradiation spot is S1, The diameter of the second irradiation spot is S2. When the rotational deviation between the first wavelength converting unit and the second wavelength converting unit is defined as Δt, a period T1 during which the first irradiation spot passes through the boundary between the first wavelength-conversion region and the first non-conversion region is T1=S1 / v1; a period T2 during which the second irradiation spot passes through the boundary between the second wavelength-conversion region and the second non-conversion region is T2=S2 / v2, the second light source irradiates the boundary between the second wavelength-conversion region and the second non-conversion region with light so as to satisfy 0≦Δt<2×T2 during a period T1 during which the first illumination spot passes through the boundary between the first wavelength-conversion region and the first non-conversion region; a light source device, wherein the first optical system and the second optical system cause the images of the first wavelength conversion region and the second wavelength conversion region to be adjacent to or overlap each other at the entrance opening of a light homogenizing element;

2. the first wavelength conversion region and the second wavelength conversion region have a first region that emits light of a first wavelength and a second region that emits light of a second wavelength different from the first wavelength, and the first region and the second region are switched at a position where light is irradiated from the first light source or the second light source, and the light of the first wavelength and the light of the second wavelength are emitted in a time-division manner; 2. The light source device according to claim 1, wherein the second light source irradiates light onto the boundary between the first region and the second region of the second wavelength conversion unit during a period in which the first light source irradiates light onto the boundary between the first region and the second region of the first wavelength conversion unit.

3. A first light source; A second light source; a wavelength conversion unit including: a first wavelength conversion region and a second wavelength conversion region that receive light emitted from the first light source or the second light source and emit light of a wavelength different from the wavelength of the received light; and a first non-conversion region and a second non-conversion region that receive light emitted from the first light source or the second light source and emit the received light without converting the wavelength of the light; a first optical system that forms an image of the first wavelength conversion region; a second optical system that forms an image of the second wavelength conversion region, the wavelength conversion unit alternates between the first wavelength conversion region, the first non-conversion region, the second wavelength conversion region, and the second non-conversion region in this order at a position where light emitted from the first light source or the second light source is irradiated, and emits light of different wavelengths in a time-division manner; the second light source irradiates light onto the boundary between the second wavelength-conversion region and the second non-conversion region during a period in which the first light source irradiates light onto the boundary between the first wavelength-conversion region and the first non-conversion region; a light source device, wherein the first optical system and the second optical system cause an image of the first wavelength conversion region and an image of the second wavelength conversion region to be adjacent to or overlap each other at an entrance opening of a light homogenizing element;

4. the first wavelength conversion region and the second wavelength conversion region have a first region that emits light of a first wavelength and a second region that emits light of a second wavelength different from the first wavelength, and the first region and the second region are switched at a position where light is irradiated from the first light source or the second light source, and the light of the first wavelength and the light of the second wavelength are emitted in a time-division manner; The second light source is During a period in which the first light source irradiates light onto the boundary between the first region and the second region of the first wavelength conversion region, The light source device according to claim 3 , wherein the light is irradiated onto a boundary between the first region and the second region of the second wavelength conversion region.

5. A first light source; A second light source; a wavelength conversion unit including: a first wavelength conversion region and a second wavelength conversion region that receive light emitted from the first light source or the second light source and emit light of a wavelength different from the wavelength of the received light; and a first non-conversion region and a second non-conversion region that receive light emitted from the first light source or the second light source and emit the received light without converting the wavelength of the light; a first optical system that forms an image of the first wavelength conversion region; a second optical system that forms an image of the second wavelength conversion region, The wavelength conversion unit is the first wavelength conversion region and the first non-conversion region are provided in one of two bands provided along a direction from a rotation center of the wavelength conversion unit toward the outside, and the second wavelength conversion region and the second non-conversion region are provided in the other band; the first wavelength-converting region and the first non-converting region are alternately positioned in this order at a position where light emitted from the first light source is irradiated, and light of different wavelengths is emitted in a time-division manner; the second wavelength-converting region and the second non-converting region are alternately positioned in this order at a position where light emitted from the second light source is irradiated, and light of different wavelengths is emitted in a time-division manner; the second light source irradiates light onto the boundary between the second wavelength-conversion region and the second non-conversion region during a period in which the first light source irradiates light onto the boundary between the first wavelength-conversion region and the first non-conversion region; a light source device, wherein the first optical system and the second optical system cause an image of the first wavelength conversion region and an image of the second wavelength conversion region to be adjacent to or overlap each other at an entrance opening of a light homogenizing element;

6. a spatial modulator that forms an image by turning on and off light for each pixel of an image of the first wavelength conversion region and the second wavelength conversion region formed by the light source device according to claim 1; and a projection optical system that enlarges and projects the image formed by the spatial modulator onto a projection surface; A projection device comprising:

Images