Light source device, image projection device, and light source optical system

Abstract

The present invention relates to a light source device, an image projection device, and a light source optical system, and its purpose is to realize the miniaturization of the image projection device and the high efficiency of light utilization. The light source device of the present invention is characterized by comprising a plurality of light source units that convert at least a part of a first color light emitted from a light source into a second color light different from the first color light and then emit the second color light, and a synthesis unit that forms a plurality of conjugate images of the light emitting areas of the second color light emitted from the plurality of light source units into a synthesis image that is adjacent to each other and partially overlaps on the incident surface of a light homogenizing element that emits the second color light after homogenizing the second color light, and the formation condition of the synthesis image is that when the light intensity in the plurality of conjugate images formed on the incident surface of the light homogenizing element is set to 1 / e of the peak intensity, 2 When the area of ​​the above portion, that is, the area of ​​the synthetic image is SC and the area of ​​the incident surface of the light uniformizing element is SI, the conditional expression 1.3>SC / SI>0.7 is satisfied.

Description

Technical Field

[0001] The invention relates to a light source device, an image projection device and a light source optical system. Background Art

[0002] Projectors (image projection devices) that magnify and project various images have become widely used today. The projector focuses light emitted from a light source onto a spatial light modulator such as a digital micromirror device (DMD) or a liquid crystal display element, and then displays the light emitted from the spatial light modulator modulated with an image signal as a color image on a screen.

[0003] In the past, projectors mainly used high-brightness ultra-high pressure mercury lamps, but due to their short lifespan, frequent maintenance was required. In response to this, in recent years, the number of projectors that have replaced ultra-high pressure mercury lamps with lasers and LEDs (Light Emitting Diodes) has gradually increased. Compared with projectors using ultra-high pressure mercury lamps, these projectors have a longer lifespan and, due to their monochromaticity, have good color reproduction performance.

[0004] In a projector, an image is formed by irradiating three primary colors, such as red, green, and blue, to an image display element such as a DMD. These three colors can be generated by a laser light source, but since the luminous efficiency of green lasers and red lasers is lower than that of blue lasers, they are not ideal. For this reason, a method is adopted in which a blue laser is irradiated onto a phosphor as excitation light, and green light and red light are generated from the fluorescence after wavelength conversion of the phosphor. Patent Documents 1 and 2 disclose a light source optical system using such a laser light source and a phosphor (combination thereof).

[0005] Patent Document 1: JP Patent No. 6094866

[0006] Patent Document 2: Japanese Patent Application Publication No. 2017-142482

[0007] The technical solution disclosed in Patent Document 1 is to separate the excitation light using a beam splitter to form two light spots on the phosphor, thereby preventing the phosphor conversion efficiency from decreasing due to a temperature rise or the like.

[0008] The technical solution disclosed in Patent Document 2 is to use two light source optical systems to synthesize the light paths at the conjugate position of the light emitting part of the fluorescence, that is, in front of the light homogenizing element, so that the shape of the incident surface of the light homogenizing element is consistent with the aspect ratio of the fluorescence image, and the conjugate images of the respective light points are adjacent to each other.

[0009] However, the technical solution disclosed in Patent Document 1 adopts a structure that utilizes the fluorescence generated by the synthesis of the rear lens. In this method, since the etendue representing the geometric light diffusion increases, there are problems such as a decrease in light utilization efficiency due to halos in the illumination optical system and the projection optical system, and an increase in the size of the device due to the brightening of the projection lens.

[0010] The technical solution disclosed in Patent Document 2 does not involve the light intensity distribution on the incident surface of the two images at the incident position and the respective incident angles of the light rays. It can be considered that the halo of the rear optical system and the enlargement of the projection optical system caused by the increase in the above-mentioned light diffusion cannot be avoided. Summary of the invention

[0011] The present invention is a technical solution proposed in view of the above-mentioned problems, and an object of the present invention is to realize miniaturization of an image projection device and high efficiency of light utilization.

[0012] In order to solve the above problems and achieve the above objects, the light source device of the present invention has the following characteristics, namely, it comprises a plurality of light source parts, which convert at least a part of the first color light emitted from the light source into a second color light different from the first color light and then emit it; and a synthesis part, which forms a plurality of conjugate images of the light emitting areas of the second color light emitted from the plurality of light source parts respectively into synthetic images adjacent to each other and partially overlapping on the incident surface of a light homogenizing element emitted after the second color light is homogenized, and the formation condition of the synthetic image is that when the light intensity in the plurality of conjugate images formed on the incident surface of the light homogenizing element is set to 1 / e of the peak intensity 2 When the area of ​​the above portion, that is, the area of ​​the synthetic image is SC and the area of ​​the incident surface of the light uniformizing element is SI, the following conditional expression is satisfied:

[0013] 1.3>SC / SI>0.7.

[0014] The present invention has the effect of achieving miniaturization of the image projection device and improving light utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram showing the structure of the projector (image projection device) according to the first embodiment.

[0016] Figure 2 This is a schematic diagram of the light source unit configuration.

[0017] Figure 3 It is a schematic diagram of the composite image of each conjugate image on the incident surface of the light uniformizing element.

[0018] Figure 4 It is a schematic diagram of the cross-sectional profile of the light intensity of the synthetic image on the incident surface of the light uniformizing element.

[0019] Figure 5 This is a schematic diagram of the light beams from each light source unit and the light beam emitted from the light uniformizing element.

[0020] Figure 6 It is a schematic diagram of light beams emitted by each light source unit of the light source device provided in the projector according to the second embodiment and light beams emitted from the light uniformizing element.

[0021] Figure 7 It is a schematic diagram of the composite image of each conjugate image on the incident surface of the light uniformizing element.

[0022] Figure 8 It is a schematic diagram of the cross-sectional profile of the light intensity of the synthetic image on the incident surface of the light uniformizing element.

[0023] Fig. 9 FIG. 1 is a schematic diagram of a composite image of conjugate images on an incident surface of a light homogenizing element in a light source device included in a projector according to a third embodiment.

[0024] Fig.10 It is a schematic diagram of the cross-sectional profile of the light intensity of the synthetic image on the incident surface of the light uniformizing element.

[0025] Fig.11 FIG. 1 is a schematic diagram of a composite image of conjugate images on an incident surface of a light homogenizing element in a light source device included in a projector according to a fourth embodiment.

[0026] Fig.12 It is a schematic diagram of the cross-sectional profile of the light intensity of the synthetic image on the incident surface of the light uniformizing element.

[0027] Fig.13 It is a schematic diagram of a modification of the composite image of each conjugate image on the incident surface of the light uniformizing element.

[0028] Fig.14 It is a schematic diagram of a modification of the composite image of each conjugate image on the incident surface of the light uniformizing element.

[0029] Fig.15 It is a schematic diagram of a modification of the composite image of each conjugate image on the incident surface of the light uniformizing element. DETAILED DESCRIPTION

[0030] Embodiments of a light source device, an image projection device, and a light source optical system will be described in detail below with reference to the accompanying drawings.

[0031] <First Embodiment>

[0032] Figure 1 It is a schematic diagram showing the structure of a projector (image projection device) 1 according to the first embodiment.

[0033] The projector 1 includes a housing 10 , a light source device 20 , a light homogenizing element 30 , an illumination optical system 40 , an image forming element (image display element) 50 , and a projection optical system 60 .

[0034] The housing 10 accommodates the light source device 20 , the light homogenizing element 30 , the illumination optical system 40 , the image forming element 50 , and the projection optical system 60 .

[0035] The light source device 20 emits light having wavelengths corresponding to, for example, RGB colors. The light source device 20 includes a light source unit 20A, a light source unit 20B, and an optical path synthesis element 20C as a synthesis unit. The light source unit 20A and the light source unit 20B have the same structure and emit light beams of a predetermined shape. The internal structures of the light source unit 20A and the light source unit 20B will be described in detail below. The light beams emitted from the light source unit 20A and the light source unit 20B are respectively deflected by the optical path synthesis element 20C and enter the incident surface of the incident light homogenizing element 30. Although the present embodiment is described using a prism as an example of the optical path synthesis element 20C, the optical path synthesis element 20C is not limited thereto.

[0036] In addition, the light source device 20 of the present embodiment uses two light source units 20A and 20B as an example, but the present invention is not limited to this, and two or more light source units, for example, four light source units may be combined.

[0037] The light homogenizing element 30 mixes the light emitted from the light source device 20 to homogenize the light. In more detail, the light homogenizing element 30 repeatedly reflects the light beam incident from the incident surface while propagating the light beam inside, and finally emits it through the emission surface. The light homogenizing element 30 forms a uniform surface light source on the emission surface by repeatedly reflecting the light beam incident from the incident surface inside. The light homogenizing element 30 can be, for example, a light tunnel formed with a hollow interior and four reflectors on the inner side surface, a rod integrator formed of a prism made of transparent materials such as glass, a fly's eye lens, etc.

[0038] The illumination optical system 40 irradiates the image forming element 50 substantially uniformly with the light homogenized by the light homogenizing element 30. The illumination optical system 40 includes, for example, one or more lenses or one or more reflecting surfaces.

[0039] Image forming element 50 includes a light valve such as a digital micromirror device (DMD), a transmissive liquid crystal panel, or a reflective liquid crystal panel, etc. Image forming element 50 forms an image by modulating light irradiated by illumination optical system 40 (light from the light source optical system of light source device 20).

[0040] The projection optical system 60 enlarges and projects the image formed by the image forming element 50 onto a screen (projection surface) 70. The projection optical system 60 includes, for example, one or more lenses.

[0041] Figure 2 20A is a schematic diagram showing the structure of the light source unit 20A. The light source unit 20B has the same structure.

[0042] The light source unit 20A (20B) includes a laser light source (excitation light source) 21 arranged in sequence in the light propagation direction, a collimating lens 22 arranged corresponding to each light source, a first lens group 23, a dichroic mirror 24, a second lens group 25, a wavelength conversion element 26 which is a fluorescent wheel, and a third lens group 27. For example, the components of the light source device 20 other than the laser light source 21 constitute a "light source optical system". The light source unit 20A (20B) sequentially arranges the above-mentioned components along the propagation direction of the excitation light emitted from the laser light source 21.

[0043] The laser light source 21 has a plurality of light sources (light emitting points). Figure 2 , six light sources are depicted arranged in the vertical direction, but in fact, the six light sources are arranged in four rows in the direction perpendicular to the drawing (depth direction), and a total of 6×4=24 light sources are arranged in two dimensions. Each light source of the laser light source 21 emits, for example, light in a blue band (blue laser) with a central wavelength of 455 nm of luminous intensity as excitation light for exciting the phosphor provided by the wavelength conversion element 26.

[0044] The blue laser light (first color light) emitted from each light source of the laser light source 21 is linearly polarized light with a certain polarization state, and is set to be S-polarized light relative to the dichroic mirror 24. The blue laser light emitted from each light source of the laser light source 21 is interference light. The excitation light emitted from each light source of the laser light source 21 can be any light having a wavelength capable of exciting the phosphor provided by the wavelength conversion element 26, and is not limited to light in the blue band.

[0045] The laser light source 21 is described by taking a plurality of light sources as an example, but a single laser light source may be used. As the laser light source 21, a light source unit arranged in an array on a bottom plate may be used, but the invention is not limited thereto.

[0046] 24 collimating lenses 22 are provided corresponding to the 24 light sources of the laser light source 21. Each collimating lens 22 is adjusted so that the excitation light emitted by each light source of the laser light source 21 becomes substantially parallel light. The number of collimating lenses 22 only needs to correspond to the number of light sources of the laser light source 21, and can be increased or decreased as the number of light sources of the laser light source 21 increases or decreases.

[0047] The excitation light emitted from the laser light source 21 becomes substantially parallel light through the collimator lenses 22 corresponding to the respective light sources of the laser light source 21. The substantially parallel excitation light passes through the first lens group 23 and is guided to the dichroic mirror 24.

[0048] The dichroic mirror 24 is a glass plate in the shape of a parallel plate. The incident surface of the dichroic mirror 24 is coated to reflect the S polarized light (first polarized light component) in the wavelength band of the excitation light introduced from the first lens group 23, and to transmit the P polarized light (second polarized light component) in the wavelength band of the excitation light introduced from the first lens group 23 and the fluorescence (second color light) from the wavelength conversion element 26.

[0049] The center of the dichroic mirror 24 is offset from the optical axis of the second lens group 25 , so that the excitation light is incident obliquely with respect to the normal line of the wavelength conversion element 26 .

[0050] Although the present embodiment uses a flat-plate dichroic mirror 24, a prism-type one may also be used. Although the dichroic mirror 24 of the present embodiment reflects S-polarized light in the wavelength band of the excitation light and transmits P-polarized light, it may be the other way around and reflect P-polarized light in the wavelength band of the excitation light and transmit S-polarized light.

[0051] The excitation light reflected by the dichroic mirror 24 is guided to the wavelength conversion element 26 through the second lens group 25. The excitation light reflected in the reflection area of ​​the wavelength conversion element 26 passes through the second lens group 25 again, passes through the opposite side of the dichroic mirror 24 relative to the optical axis of the second lens group 25, passes through the third lens group 27, is deflected by the optical path synthesis element 20C, and enters the incident light homogenization element 30.

[0052] The fluorescence emitted by the excitation light entering the fluorescent body region of the wavelength conversion element 26 is introduced into the light homogenizing element 30 via the optical path synthesizing element 20C. More specifically, the fluorescence becomes substantially parallel light through the second lens group 25, is refracted by the third lens group 27, is converged near the light tunnel, is deflected by the optical path synthesizing element 20C, and then enters the light homogenizing element 30.

[0053] However, in recent years, the demand for high brightness and high efficiency of laser projectors has become increasingly strong. The conversion efficiency of the phosphor varies with the energy density of the excitation light incident on the phosphor. If the incident energy density is high, the temperature rises or the number of electrons that can be excited in the phosphor layer decreases, thereby reducing the efficiency. Therefore, the energy density is made as uniform as possible, and the efficiency is improved by expanding the spot size.

[0054] On the other hand, since the energy density of the excitation light on the phosphor is reduced and the spot size of the excitation light on the phosphor is increased, the halo of the rear optical system and the like becomes larger, and thus the overall light utilization efficiency of the projector is reduced. Although the light utilization efficiency can be improved by brightening the Fno of the projection lens, in this case, the projection lens will become very large, the overall size of the projector will become larger, and the commercial quality will deteriorate.

[0055] That is to say, in order to improve the light utilization efficiency of the projector, it is very important to homogenize the energy density and obtain the optimal spot size.

[0056] In addition, as the brightness increases, the energy of the excitation light incident on the phosphor increases, and the temperature of the phosphor rises, causing the conversion efficiency to decrease.

[0057] In contrast, in the present embodiment, the temperature rise of the fluorescence is suppressed by separating the light spots of the excitation light on the fluorescent body, and the light spot size on the fluorescent body and the magnification of the light guide optical system are determined so that the synthetic image of the generated fluorescence has the same area as the incident surface of the light homogenizing element 30.

[0058] Specifically, multiple conjugate images of the light emitting area of ​​the fluorescence (second color light) from the wavelength conversion element 26 generate composite images that are adjacent to each other and at least partially overlap on the incident surface of the light homogenizing element 30. Let the area of ​​the composite image on the incident surface of the light homogenizing element 30 be SC, and the area of ​​the incident surface of the light homogenizing element 30 be SI. It is preferable that the following conditional formula (1) is satisfied.

[0059] 1.3>SC / SI>0.7 (1)

[0060] Conditional expression (1) represents an appropriate range of the area of ​​the composite image of the conjugate image of the fluorescent (second color light) emission area from the wavelength conversion element 26 on the incident surface of the light homogenizing element 30. Here, the composite image area means that the light intensity on the incident surface of the light homogenizing element 30 is 1 / e of the peak intensity in each conjugate image of the emission area of ​​the second color light formed on the incident surface of the light homogenizing element 30. 2 The incident surface of the light homogenizing element 30 refers to the surface closest to the incident point in the cross section of the surface perpendicular to the axis of the light guiding direction of the light homogenizing element 30. For example, when the light homogenizing element 30 is a light tunnel, it is the entrance of the light tunnel. When the light homogenizing element 30 is an optical component in which a glass rod and a prism are integrated, the cross section of the glass rod closest to the incident point is the incident surface.

[0061] If the upper limit of the conditional expression (1) is exceeded, the synthetic image cannot be sufficiently incident on the light homogenizing element 30, thereby not only reducing the light utilization efficiency of the entire optical system, but also the light that does not enter the light homogenizing element 30 becomes stray light and enters the projection optical system 60, etc., causing a reduction in contrast.

[0062] If the value is below the lower limit of conditional expression (1), the halo in the light homogenizing element 30 can be eliminated, but the incident angle of the light entering the light homogenizing element 30 becomes larger, so the etendue indicating geometric light diffusion becomes larger. If the etendue increases, the halo in the projection optical system 60 at the rear stage will lead to a decrease in light utilization efficiency, and the use of the projection optical system 60 with a bright Fno will lead to a larger device.

[0063] The etendue Et here is given by the following conditional expression: S represents the area of ​​the light source.

[0064] Et=π×S×(NA) 2

[0065] It is more preferable that the following conditional expression (2) is satisfied.

[0066] 1.2>SC / SI>0.8 (2)

[0067] It is more preferable that the following conditional expression (3) is satisfied.

[0068] 1.1>SC / SI>0.9 (3)

[0069] It is further preferred that the synthesized image has a feature that is substantially consistent with the shape of the incident surface of the light homogenizing element 30. By appropriately setting the shape and magnification of the light emitting area of ​​the second color light so that the synthesized image synthesized by the optical path synthesizing element 20C is substantially consistent with the shape of the incident surface of the light homogenizing element 30, not only can the halo of the light homogenizing element 30 be reduced, but also the reduction in the conversion efficiency of the fluorescent body caused by maximizing the light emitting area of ​​the fluorescent light can be prevented.

[0070] For example, when the light homogenizing element 30 is rectangular, the synthetic image may be rectangular. The shape of the light emitting area of ​​each second color light is not limited to a rectangle, but may be a triangle, a polygon, or a combination of different shapes.

[0071] It is further preferred that the intensity of the second color light at the boundary of the plurality of conjugate images on the incident surface of the light homogenizing element 30 is 10, and the light intensity in each conjugate image on the incident surface of the light homogenizing element 30 is 1 / e of the peak value. 2 The average light intensity of the above portion is Iave, which satisfies the following conditional expression (4). The conditional expression (4) represents the appropriate degree of overlap of the conjugate images of the second color light.

[0072] 0.1<IO / Iave<1.2 (4)

[0073] When the value of conditional expression (4) is below the lower limit, the synthetic image area on the incident surface of the light homogenizing element 30 becomes larger, the light collection rate increases, and the reduction in light utilization efficiency and the enlargement of the projection optical system are inevitable, or the light intake efficiency of the light homogenizing element 30 is reduced.

[0074] On the other hand, if the upper limit of the conditional expression (4) is exceeded, the incident angle to the light homogenizing element 30 increases, which results in an increase in the etendue.

[0075] More preferably, the aperture value of the incident light of the plurality of second color lights entering the light homogenizing element 30 is NAI, and the aperture value of the light emitted from the light homogenizing element 30 is NA0, so as to satisfy the following conditional expression (5).

[0076] 0.8<NAI / NA0<1.2 (5)

[0077] By synthesizing the optical paths in a manner that satisfies conditional expression (5), synthesis can be performed while keeping the light collection rate low, and the light utilization efficiency can be improved without reducing the conversion efficiency, making it possible to miniaturize the image projection device.

[0078] It is further preferred that the emission directions of at least two of the second color lights emitted from the plurality of light sources 20A and 20B are parallel. By forming the above configuration, the installation can be simplified and the image projection device can be miniaturized.

[0079] More preferably, the plurality of light source units 20A and 20B that respectively emit the second color light are arranged symmetrically with respect to the central axis of the light homogenizing element 30. By making the optical paths of the opposing conjugate images the same optical path, uniformity can be improved.

[0080] It is further preferred that at least two of the conjugate images of the second color light emitted from the plurality of light source units 20A and 20B have substantially the same shape. By using a common optical element, cost reduction can be achieved.

[0081] More preferably, an incident angle θ between the principal ray of the second color light emitted from the plurality of light source units 20A and 20B and the incident surface of the incident light equalizing element 30 satisfies the following conditional expression (6).

[0082] 0≤θ<10 (6)

[0083] Conditional formula (6) represents the appropriate incident angle of each second color light incident on the incident surface of the light homogenizing element 30. Here, the principal ray refers to the center line of the second color light beam. When the incident angle satisfies conditional formula (6), it is possible to prevent the light collection rate from increasing, prevent the overall size of the optical system from increasing, and prevent the light utilization efficiency from decreasing.

[0084] Here, Figure 3Schematic diagram of a composite image of conjugate images on the incident surface of the light homogenizing element 30 . Figure 3 In the figure, the solid line indicates the incident surface of the light homogenizing element 30 , and the dotted lines indicate the conjugate images formed by the respective light sources of the laser light source 21 .

[0085] like Figure 3 As shown, on the incident surface of the light homogenizing element 30, the conjugate images of the laser light sources 21 are combined to be adjacent and overlapped, and the area SC of the combined image is slightly larger than the area SI of the light homogenizing element 30. In this embodiment, SC / SI=1.05.

[0086] In this embodiment, the conjugate images have the same shape, but the conjugate images may have different shapes.

[0087] Figure 4 Schematic diagram of the light intensity cross-sectional profile of the synthetic image on the incident surface of the light homogenizing element 30 . Figure 4 Displayed on the incident surface of the light homogenizing element 30 Figure 3 Light intensity profile of the cross section shown (dash-dotted line).

[0088] like Figure 4 As shown in FIG. 1 , the light intensity on the incident surface of the light homogenizing element 30 has a profile in which the light intensity decreases at the boundary of each conjugate image. Assuming that the light intensity in the conjugate image is 1 / e of the peak intensity 2 The average light intensity of the above portion is Iave, and the light intensity of the boundary portion is IO. IO / Iave=0.45.

[0089] Figure 5 FIG. 2 is a schematic diagram of light beams from the light source units 20A and 20B and light beams emitted from the light homogenizing element 30. Figure 5 In FIG. 1 , a light beam from one of the light source units 20A is indicated by a solid line, and a light beam from the other light source unit 20B is indicated by a dotted line. The center line of each light beam from each of the light source units 20A and 20B is defined as a principal ray.

[0090] This embodiment is as Figure 5 As shown, it is assumed that the aperture value NA of the light incident from each light source unit 20A, 20B to the light homogenizing element 30 is NAI, the aperture value NA of the light beam emitted from the light homogenizing element 30 is NAO, and NAI / NAO=1.0.

[0091] In this embodiment, when the angle between the axis perpendicular to the incident surface of the light homogenizing element 30 and the principal ray is defined as the incident angle θ, the principal ray is incident at the incident angle θ=0 degrees, that is, perpendicular to the incident surface of the light homogenizing element 30 .

[0092] Thus, since the aperture value NA on the incident side and the aperture value NA on the outgoing side can be made the same, the etendue representing the geometric diffusion of light can be kept constant.

[0093] As described above, this embodiment can realize miniaturization of the image projection device and high efficiency of light utilization.

[0094] <Second Embodiment>

[0095] A second embodiment will be described below.

[0096] The second embodiment has different cross-sectional profiles, incident angles to the light uniformizing element, and synthetic image areas from the first embodiment. In the second embodiment, descriptions of the same parts as the first embodiment are omitted, but differences from the first embodiment are described.

[0097] Figure 6 FIG. 2 is a schematic diagram of light beams emitted from the light source units 20A and 20B of the light source device 20 included in the projector 1 according to the second embodiment and light beams emitted from the light homogenizing element 30. Figure 6 As shown, the light source device 20 of this embodiment is different from that of the first embodiment. Figure 5 On the contrary, the incident angle θ of the principal ray, which is the center line of each light beam from each light source unit 20A, 20B, with respect to the incident surface of the light homogenizing element 30 is 3 degrees.

[0098] Here, Figure 7 Schematic diagram of the composite image of each conjugate image on the incident surface of the light homogenizing element 30. By making the incident light from each light source unit 20A, 20B of the light source device 20 slightly tilted to enter the light homogenizing element 30, as shown in FIG. Figure 7 As shown, the overlap of the boundaries of the conjugate images on the incident surface of the light homogenizer 30 can be increased, thereby increasing the amount of light incident on the light homogenizer 30. At this time, the relationship between the area SC of the composite image and the area SI of the light homogenizer 30 is SC / SI=0.9.

[0099] Figure 8 Schematic diagram of the light intensity cross-sectional profile of the synthetic image on the incident surface of the light homogenizing element 30 . Figure 8 Displayed on the incident surface of the light homogenizing element 30 Figure 7 Light intensity profile of the cross section shown (dash-dotted line).

[0100] like Figure 8 As shown, the light intensity on the incident surface of the light homogenizing element 30 is similar to that of the first embodiment. Figure 4 The light intensity profile is different, and the light intensity from the conjugate image is 1 / e of the peak intensity at the boundary of each conjugate image. 2The light intensity average value Iave of the portion above is convex upward. At this time, IO / Iave=1.15.

[0101] This embodiment is as Figure 6 As shown, the aperture value NA of the light incident from each light source unit 20A, 20B to the light homogenizing element 30 is assumed to be NAI, and the aperture value NA of the light beam emitted from the light homogenizing element 30 is assumed to be NAO, and NAI / NAO=1.1.

[0102] In this way, this embodiment can perform synthesis in a state of low light collection rate, improve light utilization efficiency without reducing conversion efficiency, and realize miniaturization of the image projection device.

[0103] <Third Embodiment>

[0104] Next, a third embodiment will be described.

[0105] The third embodiment is different from the first embodiment in the cross-sectional profile and the area of ​​the synthetic image. In the third embodiment, the description of the same parts as the first embodiment will be omitted, and the differences from the first embodiment will be described.

[0106] Fig. 9 FIG. 2 is a schematic diagram of a composite image of conjugate images on the incident surface of the light homogenizing element 30 of the light source device 20 included in the projector 1 according to the third embodiment. Fig. 9 In FIG. 1 , the incident surface of the light homogenizing element 30 is indicated by a solid line, and the conjugate images formed by the light sources of the laser light source 21 are indicated by a dotted line.

[0107] like Fig. 9 As shown, on the incident surface of the light homogenizing element 30, the conjugate images of the laser light sources 21 are synthesized to be adjacent and overlapped, and the area SC of the synthesized image is slightly larger than the area SI of the light homogenizing element 30. In this embodiment, the relationship between the area SC of the synthesized image and the area SI of the incident surface of the light homogenizing element is SC / SI=1.1.

[0108] Fig.10 Schematic diagram of the cross-sectional profile of the light intensity of the synthetic image on the incident surface of the light homogenizing element 30 . Fig.10 Indicated in Fig. 9 The cross-sectional profile of the light intensity on the incident surface of the light homogenizing element 30 is shown in the cross-sectional view (dash-dotted line).

[0109] like Fig.10 As shown, the light intensity on the incident surface of the light homogenizing element 30 is similar to that of the first embodiment. Figure 4 Differently, the ratio of the light intensity at the boundary of each conjugate image to the average light intensity is IO / Iave=0.15.

[0110] In this way, the present embodiment can perform synthesis when the light collection rate is relatively low, thereby improving the light utilization efficiency without reducing the conversion efficiency, thereby achieving miniaturization of the image projection device.

[0111] <Fourth Embodiment>

[0112] Next, a fourth embodiment will be described.

[0113] The fourth embodiment differs from the first embodiment in that four light source units are used for synthesis. In the following description of the fourth embodiment, the same parts as the first embodiment are omitted, and the differences from the first embodiment are described.

[0114] Fig.11 FIG. 2 is a schematic diagram of a composite image of conjugate images on the incident surface of the light homogenizing element 30 of the light source device 20 included in the projector 1 according to the fourth embodiment. Fig.11 The four light source units of the light source device 20 are used for synthesis. There are methods such as using a prism for synthesis. Fig.11 In FIG. 1 , the incident surface of the light homogenizing element 30 is indicated by a solid line, and the conjugate images formed by the light sources of the laser light source 21 are indicated by a dotted line.

[0115] like Fig.11 As shown, on the incident surface of the light homogenizing element 30, the conjugate images of the laser light sources 21 are synthesized to be adjacent to each other and partially overlapped, and the area SC of the synthesized image is slightly larger than the area SI of the light homogenizing element 30. In this embodiment, the relationship between the area SC of the synthesized image and the area SI of the incident surface of the homogenizing element is SC / SI=1.08.

[0116] like Fig.11 As shown, by making the shapes of the opposing conjugate images the same, the efficiency can be improved.

[0117] Fig.12 Schematic diagram of the light intensity cross-sectional profile of the synthetic image on the incident surface of the light homogenizing element 30 . Fig.12 Show in Fig.11 The cross-sectional profile of light intensity on the incident surface of the light homogenizing element 30 is shown in the cross section (dash-dotted line).

[0118] like Fig.12 As shown, the light intensity at the incident surface of the light homogenizing element 30 is similar to that of the first embodiment. Figure 4 Different, let the light intensity in the conjugate image be the peak intensity 1 / e 2 The average light intensity of the above portion is Iave, the light intensity of the boundary portion of each conjugate image is IO, and IO / Iave=0.2 to 0.4.

[0119] In this embodiment, the principal rays of the light beams incident on the incident surface from the four light sources are respectively perpendicularly incident on the incident surface of the light homogenizing element 30. When the aperture value NA of the light beams incident on the light homogenizing element 30 from each light source is denoted as NAI and the aperture value NA of the light beams emitted from the light homogenizing element 30 is denoted as NAO, NAI / NAO=1.0.

[0120] In this way, this embodiment can perform synthesis when the light collection rate is relatively low, improve the light utilization efficiency without reducing the conversion efficiency, and realize the miniaturization of the image projection device.

[0121] Although this embodiment adopts Fig.11 The conjugate image arrangement shown in FIG. 1 is not limited thereto. For example, Fig.13 The conjugate image setup shown, Fig.14 The conjugate image setup shown, Fig.15 As shown in the arrangement of the conjugate images, the shape of the conjugate images of each light source unit is designed to be the same shape as the incident surface of the light homogenizing element 30. Fig.13 as well as Fig.14 An example is to form a synthetic image into a rectangular shape by combining four rectangular shapes. Fig.15 An example is to form a synthetic image into a rectangular shape by combining four triangular shapes.

[0122] The above-mentioned various embodiments are specific examples of the best implementation of the present invention, but the present invention is not limited to these contents.

[0123] In particular, the specific shapes and numerical values ​​of each part illustrated in the above-mentioned embodiments are only specific examples when implementing the present invention, and therefore the technical scope of the present invention should not be interpreted restrictively.

[0124] Therefore, the present invention is not limited to the contents described in the above-mentioned embodiments, and appropriate changes are allowed within the scope not departing from the gist of the present invention.

[0125] Explanation of symbols

[0126] 1 image projection device, 20 light source device, 20A, 20B light source units, 20C synthesis unit, 21 light source, 26 wavelength conversion element, 30 light homogenization element, 50 image display element, 60 projection optical system.

Claims

1. A light source device, characterized in that: have: A plurality of light source units, each having a wavelength conversion element that can be excited by laser light, and converting at least a portion of a first color light emitted from the light source into a second color light different from the first color light and then emitting the second color light; a light homogenizing element for homogenizing the second color lights emitted from the plurality of light sources, and a synthesis unit configured to make the second color lights emitted from the plurality of light source units respectively incident on the incident surface of the light homogenizing element, and to generate a plurality of conjugate images of the second color lights of the plurality of light source units in a plurality of light-emitting areas as synthetic images adjacent to each other and partially overlapping on the incident surface of the light homogenizing element, The formation condition of the synthetic image is that when the light intensity of the plurality of conjugate images formed on the incident surface of the light homogenizing element is set to 1 / e of the peak intensity 2 When the area of ​​the above portion, that is, the area of ​​the synthetic image is SC and the area of ​​the incident surface of the light homogenizing element is SI, the following conditional expression is satisfied: 1.3>SC / SI>0.

7.

2. The light source device according to claim 1, characterized in that: The synthetic image has a shape consistent with the incident surface of the light homogenizing element.

3. The light source device according to claim 1 or 2, characterized in that: The formation condition of the synthetic image is as follows: the light intensity of the second color light at the boundary of the plurality of conjugate images on the incident surface of the light homogenizing element is I0, and the light intensity in the plurality of conjugate images on the incident surface of the light homogenizing element is 1 / e of the peak intensity. 2 The average light intensity of the above part is Iave, which satisfies the following conditional expression: 0.1<I0 / Iave<1.

2.

4. The light source device according to claim 1 or 2, characterized in that: The formation condition of the synthetic image is that, assuming that the aperture value of the incident light of the second color light entering the light equalizing element is NAI and the aperture value of the outgoing light emitted from the light equalizing element is NAO, the following conditional expression is satisfied: 0.8<NAI / NAO<1.

2.

5. The light source device according to claim 1 or 2, characterized in that: Among the second color lights emitted from the plurality of light source units, emission directions of at least two of the second color lights are parallel.

6. The light source device according to claim 1 or 2, characterized in that: A plurality of light source units that respectively emit the second color light are symmetrically arranged with respect to a central axis of the light homogenizing element.

7. The light source device according to claim 1 or 2, characterized in that: Among the conjugate images of the second color light emitted from the plurality of light source units, at least two conjugate images have the same shape.

8. The light source device according to claim 1 or 2, characterized in that: The formation condition of the synthetic image is that the incident angle θ between the center line of the second color light beam emitted from the plurality of light source units, that is, the principal light, and the incident surface of the light homogenizing element satisfies the following conditional expression: 0 degrees ≤ θ < 10 degrees.

9. An image projection device, characterized in that: have: The light source device according to any one of claims 1 to 8; A light homogenizing element, which homogenizes the second color light incident from the light source device and then emits it; an image display element that modulates the light from the light homogenizing element to form an image; as well as The projection optical system magnifies the image and projects it onto the projection surface.

10. A light source optical system, characterized in that: have: a plurality of wavelength conversion elements, converting at least a portion of first color light emitted from a plurality of light sources into a second color light different from the first color light; and a light homogenizing element for homogenizing the second color light emitted from the plurality of wavelength conversion elements, and a synthesis unit configured to make the second color lights emitted respectively from the plurality of wavelength conversion elements incident on the incident surface of the light homogenizing element, and to generate a plurality of conjugate images of the second color lights of the plurality of wavelength conversion elements in a plurality of light-emitting areas as synthetic images adjacent to each other and partially overlapping on the incident surface of the light homogenizing element, The formation condition of the synthetic image is that when the light intensity of the plurality of conjugate images formed on the incident surface of the light homogenizing element is set to 1 / e of the peak intensity 2 When the area of ​​the above portion, that is, the area of ​​the synthetic image is SC and the area of ​​the incident surface of the light homogenizing element is SI, the following conditional expression is satisfied: 1.3>SC / SI>0.7.

Images