Light source device and image projection device

Abstract

The present invention provides a light source device and an image projection device that make it possible to simplify the design of an optical system and that are capable of reducing unevenness. A light source device (10) that irradiates an irradiation unit with light, the light source device (10) including a first light source (12) that emits first emission light of a first wavelength, a second light source (13) that emits second emission light of a second wavelength, and a light guide member (14) disposed between the first light source (12) and the irradiation unit (16), wherein the light guide member (14) includes a transmission unit that transmits the first emission light in the direction of the irradiation unit (16) from the first light source (12) side, and the transmission unit guides the second emission light inside and includes a reflection recesses and protrusions that reflect light in the direction of the irradiation unit (16).

Description

Light source device and image projection device

[0001] The present invention relates to a light source device and an image projection device.

[0002] 2. Description of the Related Art One field of light source devices is a light source device that illuminates a liquid crystal display from the back, known as a backlight. JP-A-2003-129999 discloses such a light source device.

[0003] The light source device disclosed in Patent Document 1 is a light source device that illuminates a liquid crystal display used in an image projection device such as a head-up display (hereinafter referred to as "HUD") from behind, and is equipped with a light source unit in which a plurality of first light source elements that emit white light and a plurality of second light source elements that emit red light are arranged in a predetermined direction, a first lens that converts the light emitted from the light source unit into parallel light, and a second lens that deflects the light emitted from the first lens so that it is irradiated onto the effective range of the liquid crystal display.

[0004] In Patent Document 1, the first lens causes light emitted from multiple light source elements to overlap in a predetermined area on the incident surface of the LCD display, thereby enabling specific colors to be displayed efficiently and with high brightness in images displayed on the LCD display.

[0005] JP 2019-164285 A

[0006] Light source devices for liquid crystal displays are required to ensure the necessary brightness (generally relatively high brightness) and to be able to uniformly illuminate the entire liquid crystal display. Uniform illumination here refers to illumination that suppresses not only uneven illumination but also color unevenness. When used in HUDs and other displays, compactness is also required due to installation space limitations.

[0007] In this regard, the light source device disclosed in Patent Document 1 also aims to achieve high brightness. However, in the light source device disclosed in Patent Document 1, each of the emitted light from the first light source element and each of the emitted light from the second light source element is configured to illuminate the entire illumination area. Therefore, due to constraints of the optical system, it is difficult to shorten the distance between the light source element and the first lens, the distance between the first lens and the second lens, and the distance between the second lens and the illuminated object. This limits the miniaturization of the light source device disclosed in Patent Document 1. Furthermore, the configuration of the light source device disclosed in Patent Document 1 has the problem of color unevenness easily occurring depending on the arrangement of the first light source element and the second light source element.

[0008] SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned problems of the prior art, and aims to provide a light source device and an image projection device that can simplify the design of the optical system and reduce color unevenness.

[0009] In order to solve the above problem, the light source device of the present invention includes a first light source that emits a first emitted light of a first wavelength, a second light source that emits a second emitted light of a second wavelength, an irradiation section onto which the first emitted light and the second emitted light are irradiated, and a light-guiding member arranged between the first light source and the irradiation section, wherein the light-guiding member has a transmissive section that transmits the first emitted light from the first light source side toward the irradiation section, and the transmissive section has a reflective uneven section that guides the second emitted light internally and reflects it toward the irradiation section.

[0010] In the light source device of the present invention, the light-guiding member has a transmissive portion that transmits the first emitted light from the first light source side toward the irradiation portion, and the transmissive portion has a reflective uneven portion that guides the second emitted light internally and reflects it toward the irradiation portion, thereby making it possible to mix the first emitted light and the second emitted light throughout the entire transmissive portion, simplifying the design of the optical system and reducing color unevenness.

[0011] In one aspect of the present invention, the first light source and the second light source are mounted on a common substrate, the light-guiding member has a light guide portion connected to the side of the transmissive portion and guiding the second emitted light to the transmissive portion, and the light guide portion is curved from the light emission surface of the second light source to the side of the transmissive portion.

[0012] In one aspect of the present invention, the light guide member has a transmission portion that transmits the first emitted light, and the second light source is disposed opposite a side surface of the transmission portion.

[0013] In one aspect of the present invention, the first light source and the second light source are mounted on separate substrates.

[0014] In one aspect of the invention, the light guide member is disposed opposite the first light source and has a lens function of refracting the first emitted light to adjust its orientation.

[0015] In one aspect of the present invention, the light source includes a first wiring that supplies power to the first light source and a second wiring that supplies power to the second light source, and the first wiring and the second wiring are provided separately.

[0016] In order to solve the above problem, the image projection device of the present invention is characterized by comprising any one of the above light source devices, an image display unit that displays an image using the first emission light and the second emission light emitted from the light source device, and a projection optical unit that projects the first emission light and the second emission light emitted from the image display unit.

[0017] The present invention can provide a light source device and an image projection device that can simplify the design of the optical system and reduce color unevenness.

[0018] 5A is a schematic diagram illustrating the projection of a virtual image using the image projection device 100 according to the first embodiment. FIG. 5B is a schematic cross-sectional view illustrating the overview of the image projection device 100 according to the first embodiment. FIG. 5C is a schematic cross-sectional view illustrating the structure of the first lens 14. FIG. 5D is a schematic enlarged view illustrating the transmission section 14c and the reflective uneven section 14e according to a modified example of the first embodiment. FIG. 5A shows the reflective uneven section 14e as a convex lens that protrudes toward the light source 12. FIG. 5B shows the reflective uneven section 14e as a concave lens that is recessed by a curved surface. FIG. 5C is a schematic diagram illustrating the overview of the image projection unit 10 according to the second embodiment. FIG. 6A shows an example in which an additional optical section 18 is used, and FIG. 6B shows an example in which the second lens 15 and the additional optical section 18 are used in combination. FIG. 6D is a schematic diagram illustrating the overview of the image projection unit 10 according to the third embodiment. FIG. 6E is a schematic diagram illustrating the overview of the image projection unit 10 according to the fourth embodiment. FIG. 6F is a schematic diagram illustrating the overview of the image projection unit 10 according to the fifth embodiment. 10(a) shows an example of the wiring pattern on the substrate 11, and FIG. 10(b) shows an example of the wiring pattern on the substrates 11a and 11b. It is a chromaticity diagram for explaining chromaticity adjustment in the image projection unit 10 according to the sixth embodiment.

[0019] First Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing will be denoted by the same reference numerals, and redundant description will be omitted where appropriate. In the following description, an image projection device 100 according to the present invention will be described, exemplarily, as applied to a HUD mounted on a vehicle or the like. FIG. 1 is a schematic diagram illustrating the projection of a virtual image using the image projection device 100 according to this embodiment. The dashed lines in FIG. 1 indicate the optical path of a first image light L1 (described later), and the dashed-dotted lines indicate the optical path of a second image light L2 (described later). As shown in FIG. 1, the first image light L1 and the second image light L2 projected from the image projection device 100 are reflected by a windshield (display unit) WS and irradiated toward the driver's viewpoint. The driver visually recognizes virtual images P1 and P2 formed on the extension of the optical paths of the incident first image light L1 and second image light L2. In this embodiment, an example is shown in which the image projection device 100 projects the first image light L1 and the second image light L2 to form two images P1 and P2, but the number of virtual images is not limited.

[0020] The windshield WS is a portion of the vehicle that is provided in front of the driver's seat and transmits visible light. The windshield WS, on the interior surface of the vehicle, reflects the first image light L1 and the second image light L2 incident from the image projection device 100 toward the viewpoint and transmits light from outside the vehicle toward the viewpoint, and therefore corresponds to the display unit of the present invention. While an example in which the windshield WS is used as the display unit is shown here, a combiner may be provided as a display unit separate from the windshield WS and reflect light from the image projection device 100 toward the viewpoint. Furthermore, the display unit is not limited to being located at the front of the vehicle, and may be located to the side or rear of the vehicle as long as it projects an image toward the viewpoint of the passenger.

[0021] The virtual images P1 and P2 are images that are displayed as if they were formed in space when the first image light L1 and the second image light L2 reflected by the windshield WS reach the viewpoint (eyebox) of the occupant. The positions at which the virtual images P1 and P2 are formed are determined by the combined focal length of the projection optical unit included in the image projection device 100 and the windshield WS.

[0022] In the image projection device 100 of this embodiment, a far image displayed in the far display area of ​​the image projection unit 10 is irradiated as a first image light L1, and a near image displayed in the near display area is irradiated as a second image light L2. Examples of far images displayed in the far display area include images calling attention to driving, emergency information, and other auxiliary information related to driving. Examples of near images displayed in the near display area include a speed and volume indicator, a driving direction guide, and the like.

[0023] FIG. 2 is a schematic cross-sectional view illustrating an overview of an image projection device 100 according to this embodiment. As shown in FIG. 2, the image projection device 100 includes an image projection unit 10, a first mirror 20, a second mirror 30, and a housing 40. In the image projection device 100, each unit is controlled using a control unit (not shown) connected to each unit so as to be able to communicate information with the unit. The configuration of the control unit is not limited, but an example includes a CPU (Central Processing Unit) for information processing, a memory device, a recording medium, an information communication device, and the like. The control unit controls the operation of each unit according to a predetermined program and sends information including an image (image information) to the image projection unit 10.

[0024] The image projection unit 10 is a part that, based on image information from the control unit, projects light containing an image onto the first mirror 20 as image light. In this embodiment, an example is shown in which two image lights displayed in two image display areas are projected onto the first mirror 20 as first image light L1 and second image light L2.

[0025] The first mirror 20 is an optical member that reflects the first image light L1 and the second image light L2 arriving from the image irradiation unit 10 toward the second mirror 30. In the example shown in Fig. 2, the first mirror 20 is a flat reflecting mirror, but a concave or convex reflecting mirror may also be used. Furthermore, when the first mirror 20 is configured with a curved surface, it is not limited to one with a constant curvature, and a paraboloid of revolution, an ellipsoid, a free-form surface mirror, or the like may be used.

[0026] The second mirror 30 is an optical member that reflects the first image light L1 and the second image light L2 that have arrived from the first mirror 20 toward the windshield WS. In the example shown in Fig. 1, the second mirror 30 is a free-form mirror with an optically designed concave shape necessary for projecting the first image light L1 and the second image light L2 as virtual images P1 and P2.

[0027] The reflective surfaces of the first mirror 20 and the second mirror 30 are designed to expand the light diameter in the driver's viewing direction in order to project the first image light L1 and the second image light L2 as virtual images P1 and P2 through the windshield WS. Here, "expanding the light diameter in the viewing direction" includes not only the case where the light diameter expands consistently after reflection, but also the case where the light diameter shrinks and expands after forming an image at an intermediate point. The combination of the first mirror 20 and the second mirror 30 has the function of projecting the first image light L1 and the second image light L2 through the windshield WS and corresponds to the irradiation optical unit in the present invention.

[0028] 1 and 2, the optical paths of the first image light L1 and the second image light L2 are depicted as a single straight line. However, the actual first image light L1 and the second image light L2 are displayed in a predetermined area in the image projection unit 10, and have a predetermined area in a direction perpendicular to the traveling direction. Furthermore, the first image light L1 and the second image light L2 may be reflected by the first mirror 20, and their light diameters may be reduced as they travel, and they may form intermediate images at an intermediate image position F (not shown) between the first mirror 20 and the second mirror 30.

[0029] The housing 40 constitutes the outer shape of the image projection device 100 and is a container that houses each component. The housing 40 is provided with a light exit port for emitting the first image light L1 and the second image light L2. An angle adjustment unit for adjusting the angle of the second mirror 30 may be provided within the housing 40 to adjust the irradiation angle of the first image light L1 and the second image light L2 projected onto the windshield WS and change the imaging height of the virtual images P1 and P2. The housing 40 may also be provided with an optical filter that cuts out ultraviolet light and infrared light contained in light (external light) arriving from outside.

[0030] FIG. 3 is a schematic diagram illustrating an overview of the image projection unit 10 according to this embodiment. As shown in FIG. 3, the image projection unit 10 according to this embodiment includes a substrate 11, light sources 12 and 13, a first lens 14, a second lens 15, a light diffusion unit 16, and an image display unit 17. In the figure, solid arrows schematically indicate the paths of light emitted from the light sources 12 and 13. Here, the combination of the substrate 11, the light sources 12 and 13, the first lens 14, and the second lens 15 corresponds to the light source device in the present invention. Furthermore, the light diffusion unit 16 or the image display unit 17 is an object onto which light is irradiated from the light source device, and corresponds to the irradiation unit in the present invention.

[0031] The substrate 11 is a plate-like member on which a wiring pattern (not shown) is formed and on which the light sources 12, 13 and electronic components are mounted. The wiring pattern of the substrate 11 is connected to a power source, and light is emitted from the light sources 12, 13 by power supplied from the power source. In addition, the electronic components mounted on the substrate 11 may form a drive circuit that controls the drive of the light sources 12, 13.

[0032] The light sources 12 and 13 are electronic components that emit light of a predetermined wavelength in response to supplied power. The light sources 12 and 13 are, for example, semiconductor light-emitting elements such as LEDs (Light Emitting Diodes) and are arranged in a predetermined direction (horizontal direction in FIG. 3 ). The light sources 12 and 13 emit light of different wavelengths, although the light source colors are not particularly limited. In this embodiment, for example, the light source 12 emits yellow or white light, and the light source 13 emits blue light. While the light sources 12 and 13 are arranged in one row in this embodiment, they may be arranged in two or more rows. Furthermore, the light sources 12 and 13 are not limited to LEDs and may be organic EL (Electro Luminescence) elements or the like.

[0033] In this embodiment, an example is shown in which light source 12 and light source 13 are mounted on a common substrate 11. Furthermore, light source 12 is arranged together in a central region on substrate 11, and light source 13 is arranged in a peripheral region on substrate 11. Furthermore, in this embodiment, light sources 12 and 13 each emit light in a direction perpendicular to substrate 11, as shown in Fig. 3. Here, light source 12 corresponds to a first light source that emits first emitted light of a first wavelength, and light source 13 corresponds to a second light source that emits second emitted light of a second wavelength.

[0034] The first lens 14 is an optical element disposed between the light source 11 and the second lens 15. The first lens 14 extends along the arrangement direction of the plurality of light sources 12. The first lens 14 transmits the first emitted light irradiated from the light source 12 and guides and scatters the second emitted light irradiated from the light source 13, mixing the first emitted light and the second emitted light before outputting the light. The first lens 14 also functions to condense the first emitted light from the light source 12, which has a relatively large directivity angle, and output the light as, for example, parallel light or a light beam close to parallel light (hereinafter, both of these will be collectively referred to as "approximately parallel light"). The first lens 14 may be, for example, a lens having positive power, and its shape is not particularly limited. However, the positive and negative powers of the first lens 14 should be determined depending on the directivity angle of the light irradiated from the light source 12, and are not limited to one type. In this embodiment, a plano-convex lens is used as an example of the first lens 14. In this embodiment, the first lens 14 corresponds to the light-guiding member of the present invention. The structure of the first lens 14 will be described in detail below.

[0035] The second lens 15 is an optical element disposed between the first lens 14 and the light diffusion unit 16. The first and second output lights mixed by the first lens 14 enter the second lens 15, and the second lens 15 controls the light flux so that the first and second output lights uniformly illuminate the entire light diffusion unit 16. Therefore, the shape and positive and negative power of the second lens 15 are selected to suit this purpose. In this embodiment, a convex lens is used as an example of the second lens 15. If the entire light diffusion unit 16 is configured to be uniformly illuminated using only the first lens 14, the second lens 15 may be omitted. The first lens 14 and the second lens 15 are formed of, for example, a resin such as acrylic resin, glass, or the like. In this embodiment, the illuminated area is, for example, the back surface of the light diffusion unit 16 (the surface facing the light source 12). However, the illuminated area may be determined taking into account the specifications of the light source device, and may be, for example, the back surface of the image display unit 17.

[0036] The light diffusion unit 16 is an optical member disposed on the rear side of the image display unit 17, and diffuses the first exit light and the second exit light irradiated from the second lens 15, and transmits the light as backlight. The light diffusion unit 16 diffuses the highly directional light deflected by the first lens 14 and the second lens 15, and emits the light to the image display unit 17, thereby functioning to illuminate the image display unit 17 more uniformly.

[0037] The image display unit 17 functions as a spatial light modulation unit that receives backlight that has passed through the light diffusion unit 16 from the rear surface, modulates the light according to image information, and emits the modulated light from the emission surface. The specific configuration of the image display unit 17 is not limited, but as an example, a transmissive liquid crystal display device that transmits light that has entered from the rear surface and emits the light from the front surface can be used.

[0038] Fig. 4 is a schematic cross-sectional view showing the structure of first lens 14. As shown in Fig. 4, first lens 14 includes light incident portion 14a, light guide portion 14b, light transmitting portion 14c, light incident surface 14d, reflective uneven portion 14e, light exit surface 14f, and incident-side space 14g. Furthermore, light incident portion 14a, light guide portion 14b, and light transmitting portion 14c are integrally formed from a light-transmitting material.

[0039] The light incident portion 14a is provided at a position corresponding to the light source 13, and is a portion that takes in the second outgoing light emitted from the light source 13 into the first lens 14. In the example shown in Fig. 4, the light incident portion 14a has a shape that is wider than the light guide portion 14b, but the shape is not limited as long as it can efficiently take in the second outgoing light from the light source 13.

[0040] The light guide portion 14b connects the light incident portion 14a and the transmission portion 14c and guides the second outgoing light to the transmission portion 14c inside. In the example shown in Fig. 3, the light guide portion 14b has a curved shape from the top of the light incident portion 14a to the side of the transmission portion 14c. Although Fig. 4 shows the light guide portion 14b as an arc shape with a constant curvature, the shape is not limited as long as it can change the direction of the second outgoing light from the light incident portion 14a and guide it to the side of the transmission portion 14c.

[0041] The transmitting portion 14c is provided at a position corresponding to the light source 12, transmits the first outgoing light emitted from the light source 12, reflects the second outgoing light guided from the light guide portion 14b, and emits the first outgoing light and the second outgoing light from the light outgoing surface 14f. In addition, a plurality of reflective uneven portions 14e are formed on the surface of the transmitting portion 14c facing the light source 12.

[0042] The light incident surface 14d is a surface facing the light source 13 provided in the light incident portion 14a, and is a portion that takes in the second outgoing light emitted from the light source 13 into the light incident portion 14a. In Fig. 4, an example is shown in which the light incident surface 14d is formed as a flat surface and is wider than the light source 13, but the shape and size are not limited as long as it can efficiently take in the second outgoing light from the light source 13. Other examples of the light incident surface 14d include a convex lens shape facing the light source 13 and a Fresnel lens shape.

[0043] The reflective uneven portion 14e has an uneven shape provided on the surface of the transmissive portion 14c facing the light source 12, and is a portion that reflects the second emitted light guided in the in-plane direction of the transmissive portion 14c toward the image display portion 17. In the example shown in Fig. 4, recesses with a triangular cross section are arranged at equal intervals as the reflective uneven portion 14e, but the shape, interval, and number are not limited, and a lenticular lens, a Fresnel lens, a step shape, or the like can be used. As another example, the reflective uneven portion 14e may be formed in a fan shape within the plane of the transmissive portion 14c, centered on the connection portion between the light guide portion 14b and the transmissive portion 14c.

[0044] The light exit surface 14f is a surface provided on the image display unit 17 side of the transmission unit 14c, and is a portion from which the first exit light emitted from the light source 12 and the second exit light reflected by the reflective uneven portion 14e are emitted. In the example shown in Fig. 4, the light exit surface 14f is a curved surface that is convex toward the image display unit 17 and functions as a convex lens, but the shape of the light exit surface 14f is not limited.

[0045] The incident-side space 14g is a space on the light source 12 side that is secured between the substrate 11 and the transmitting portion 14c. As shown in Figures 3 and 4, the transmitting portion 14c is formed integrally with the light incident portion 14a and the light guide portion 14b, and is held at a distance from the substrate 11 by the light incident portion 14a and the light guide portion 14b. Because the incident-side space 14g is provided in the first lens 14, the first outgoing light irradiated from the light source 12 spreads at a predetermined spread angle in the incident-side space 14g before entering the transmitting portion 14c.

[0046] 3, the first outgoing light emitted from the light source 12 passes through the incident-side space 14g and enters the transmissive portion 14c, then passes through the transmissive portion 14c and is emitted from the light exit surface 14f toward the image display unit 17. The second outgoing light emitted from the light source 13 enters the light incident portion 14a from the light incident surface 14d, passes from the light incident portion 14a through the light guide portion 14b, and reaches a side of the transmissive portion 14c. The second outgoing light that has reached the side of the transmissive portion 14c is guided in the in-plane direction of the transmissive portion 14c (the left-right direction in the figure), reflected by the reflective uneven portion 14e, and is emitted from the light exit surface 14f toward the image display unit 17.

[0047] For simplicity, in Figure 3, the path of the second exit light is indicated by a single arrow. However, in reality, the second exit light is guided while repeatedly reflected along multiple paths within the light entrance portion 14a, the light guide portion 14b, and the transmissive portion 14c. Furthermore, the second exit light guided in the in-plane direction of the transmissive portion 14c is guided toward the reflective uneven portion 14e at a depression angle and reflected by the multiple reflective uneven portions 14e. Therefore, the second exit light emitted from the light exit surface 14f has a uniform luminance distribution within the plane. As a result, the first exit light transmitted through the transmissive portion 14c and the second exit light reflected by the reflective uneven portion 14e are uniformly mixed in the plane and emitted toward the image display unit 17.

[0048] As described above, in the light source device and image projection device 100 of this embodiment, the first lens 14 has a transmissive portion 14c that transmits the first emitted light from the light source 12 side toward the image display unit 17, and the transmissive portion 14c has a reflective uneven portion 14e that guides the second emitted light internally and reflects it toward the image display unit 17, thereby allowing the first emitted light and the second emitted light to mix over the entire area of ​​the transmissive portion 14c, simplifying the design of the optical system and reducing color unevenness.

[0049] In addition, the second emitted light irradiated from the light source 13 is guided by the light incident portion 14a and the light guide portion 14b, and is guided into the plane from the side of the transmission portion 14c, so that the light source 12 and the light source 13 can be mounted on the same substrate 11, thereby reducing the number of parts and making the device smaller.

[0050] (Modification of First Embodiment) Next, a modification of the first embodiment of the present invention will be described with reference to FIG. 5. Description of content that overlaps with the first embodiment will be omitted. FIG. 5 is a schematic enlarged view showing the transmission portion 14c and the reflective uneven portion 14e according to this modification. In the example shown in FIG. 5(a), the reflective uneven portion 14e is a convex lens that protrudes toward the light source 12. In the example shown in FIG. 5(b), the reflective uneven portion 14e is a concave lens that is recessed with a curved surface. By using a lens shape for the reflective uneven portion 14e, it is possible to achieve both the function of reflecting the second output light propagating in the in-plane direction of the transmission portion 14c and the function of adjusting the spread angle of the first output light incident from the light source 12.

[0051] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 6. Description of content that overlaps with the first embodiment will be omitted. Fig. 6 is a schematic diagram illustrating an overview of the image projection unit 10 according to this embodiment, Fig. 6(a) shows an example in which an additional optical unit 18 is used, and Fig. 6(b) shows an example in which a second lens 15 and the additional optical unit 18 are used in combination.

[0052] The additional optical unit 18 is an optical element disposed between the first lens 14 and the light source 12, and applies a predetermined optical action to the first output light emitted from the light source 12, causing the first output light to enter the first lens 14. While FIG. 6 shows the additional optical unit 18 as having a shape extending in the arrangement direction of the light sources 12, a plurality of additional optical units 18 may be provided for each light source 12. The shape and function of the additional optical unit 18 are not limited, and examples include a lens that adjusts the light distribution and a reflecting mirror that controls the direction of light irradiation. When a lens is used as the additional optical unit 18, a TIR (Total Internal Reflection) lens may be used, which has a refractive unit in the center that refracts light and reflecting units on both sides of the refractive unit that reflect light.

[0053] As described in Figures 3 and 4, the first lens 14 has an incident-side space 14g between the substrate 11 and the transmission portion 14c, which is formed by the light incident portion 14a and the light guide portion 14b, so that an additional optical portion 18 can be placed in the incident-side space 14g to save space.

[0054] Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG. 7. Description of content overlapping with the first embodiment will be omitted. FIG. 7 is a schematic diagram illustrating an overview of an image projection unit 10 according to this embodiment. As shown in FIG. 7, the image projection unit 10 of this embodiment includes substrates 11a and 11b, light sources 12 and 13, a first lens 14, a second lens 15, a light diffusion unit 16, and an image display unit 17. This embodiment differs from the first embodiment in that the substrates 11a and 11b are configured as separate bodies, and the light sources 12 and 13 are mounted on each of the substrates, with the light source 13 being disposed to the side of the first lens 14.

[0055] The substrate 11a is a plate-shaped member on which a wiring pattern (not shown) is formed and on which the light source 12 and electronic components are mounted. The substrate 11b is a plate-shaped member on which a wiring pattern (not shown) is formed and on which the light source 13 and electronic components are mounted. The substrates 11a and 11b may be electrically connected by a wiring cable or the like (not shown). The substrate 11b is disposed upright relative to the substrate 11a and to the side of the first lens 14, and the light emission surface of the light source 13 is disposed opposite the side surface of the first lens 14. In this embodiment, the entire first lens 14 can be considered as a transmission portion.

[0056] As indicated by the arrows in FIG. 7 , the first outgoing light emitted from the light source 12 passes through the incident-side space 14g and enters the first lens 14, then passes through the first lens 14 and is emitted toward the image display unit 17. The second outgoing light emitted from the light source 13 enters the first lens 14 from its side surface. The second outgoing light is guided in the in-plane direction of the first lens 14 (the left-right direction in the figure), reflected by the reflective uneven portion 14e, and emitted toward the image display unit 17. Therefore, the luminance distribution of the second outgoing light emitted from the first lens 14 is uniform within the plane. As a result, the first outgoing light passing through the first lens 14 and the second outgoing light reflected by the reflective uneven portion 14e are mixed uniformly within the plane and emitted toward the image display unit 17.

[0057] 7 shows an example in which the substrates 11a and 11b are configured as separate bodies, but the substrates 11a and 11b may be configured as the same flexible substrate. In this case, the area between the region where the light source 13 is mounted and the region where the light source 12 is mounted is curved, and the light source 13 is held in a position facing the side surface of the first lens 14.

[0058] In the light source device and image projection device 100 of this embodiment, the first lens 14 transmits the first emitted light from the light source 12 side toward the image display unit 17, and the first lens 14 guides the second emitted light internally and has a reflective uneven portion 14e that reflects the second emitted light toward the image display unit 17, thereby allowing the first emitted light and the second emitted light to mix over the entire area of ​​the first lens 14, simplifying the design of the optical system and reducing color unevenness.

[0059] (Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIG. 8. Description of content overlapping with the first embodiment will be omitted. FIG. 8 is a schematic diagram illustrating an overview of an image projection unit 10 according to this embodiment. As shown in FIG. 8, the image projection unit 10 of this embodiment includes substrates 11a and 11b, light sources 12 and 13, a first lens 14, a second lens 15, a light diffusion unit 16, and an image display unit 17. This embodiment differs from the third embodiment in that the light source 13 is disposed to the side of the second lens 15, and a reflective uneven portion 15a is formed on the second lens 15.

[0060] Substrate 11b is disposed to the side of second lens 15 and stands upright relative to substrate 11a, and the light emission surface of light source 13 is disposed facing the side surface of second lens 15. Reflective uneven portion 15a is an uneven shape provided on the surface of second lens 15 facing first lens 14, and is a portion that reflects the second emission light that has been guided in the in-plane direction toward image display unit 17. In this embodiment, the entire second lens 15 can be considered as a transmissive portion.

[0061] As indicated by the arrows in FIG. 8 , the first outgoing light emitted from the light source 12 passes through the incident-side space 14g, transmits through the first lens 14 and the second lens 15, and is emitted toward the image display unit 17. The second outgoing light emitted from the light source 13 enters the second lens 15 from its side surface. The second outgoing light is guided in the in-plane direction of the second lens 15 (the left-right direction in the figure), reflected by the reflective uneven portion 15a, and emitted toward the image display unit 17. Therefore, the luminance distribution of the second outgoing light emitted from the second lens 15 is uniform within the plane. As a result, the first outgoing light that transmits through the second lens 15 and the second outgoing light that is reflected by the reflective uneven portion 15a are mixed uniformly within the plane and are emitted toward the image display unit 17.

[0062] In the light source device and image projection device 100 of this embodiment, the second lens 15 transmits the first emitted light from the light source 12 side toward the image display unit 17, and the second lens 15 guides the second emitted light internally and has a reflective uneven portion 15a that reflects the second emitted light toward the image display unit 17, thereby mixing the first emitted light and the second emitted light throughout the entire area of ​​the second lens 15, simplifying the design of the optical system and reducing color unevenness.

[0063] Fifth Embodiment Next, a fifth embodiment of the present invention will be described with reference to FIG. 9. Description of content overlapping with the first embodiment will be omitted. FIG. 9 is a schematic diagram illustrating an overview of an image projection unit 10 according to this embodiment. As shown in FIG. 9, the image projection unit 10 according to this embodiment includes substrates 11a and 11b, light sources 12 and 13, a first lens 14, a second lens 15, a light diffusion unit 16, an image display unit 17, and a third lens 19. This embodiment differs from the third embodiment in that the light source 13 is disposed to the side of the third lens 19, and a reflective uneven portion 19a is formed on the third lens 19.

[0064] The third lens 19 is an optical member disposed between the second lens 15 and the light diffusion unit 16. The first outgoing light that has passed through the first lens 14 and the second lens 15 is incident on the third lens 19 from the light source side, and passes through the third lens 19 toward the image display unit 17. The third lens 19 also reflects the second outgoing light that has entered from the side toward the image display unit 17. A reflective uneven portion 19a is provided on the light source 11 side of the third lens 19.

[0065] Substrate 11b is disposed to the side of third lens 19 and stands upright relative to substrate 11a, and the light emission surface of light source 13 is disposed facing the side surface of third lens 19. Reflective uneven portion 19a is an uneven shape provided on the surface of third lens 19 facing second lens 15, and is a portion that reflects the second emission light that has been guided in the in-plane direction toward image display unit 17. In this embodiment, the entire third lens 19 can be considered as a transmissive portion.

[0066] As indicated by the arrows in FIG. 9 , the first outgoing light emitted from the light source 12 passes through the incident-side space 14g, transmits through the first lens 14, the second lens 15, and the third lens 19, and is emitted toward the image display unit 17. The second outgoing light emitted from the light source 13 enters the third lens 19 from its side surface. The second outgoing light is guided in the in-plane direction of the third lens 19 (the left-right direction in the figure), reflected by the reflective uneven portion 19a, and emitted toward the image display unit 17. Therefore, the luminance distribution of the second outgoing light emitted from the third lens 19 is uniform within the plane. As a result, the first outgoing light that transmits through the third lens 19 and the second outgoing light that is reflected by the reflective uneven portion 19a are mixed uniformly within the plane and are emitted toward the image display unit 17.

[0067] In the light source device and image projection device 100 of this embodiment, the third lens 19 transmits the first emitted light from the light source 12 side toward the image display unit 17, and the third lens 19 guides the second emitted light internally and has a reflective uneven portion 19a that reflects the second emitted light toward the image display unit 17, thereby mixing the first emitted light and the second emitted light throughout the entire area of ​​the third lens 19, simplifying the design of the optical system and reducing color unevenness.

[0068] Sixth Embodiment Next, a sixth embodiment of the present invention will be described with reference to Fig. 10 and Fig. 11. Description of content that overlaps with the first embodiment will be omitted. Fig. 10 is a schematic diagram illustrating the wiring pattern of the image projection unit 10 according to this embodiment, with Fig. 10(a) showing an example of the wiring pattern on the substrate 11 and Fig. 10(b) showing an example of the wiring pattern on the substrates 11a and 11b.

[0069] 10(a), light sources 12 and 13 are mounted on a common substrate 11, with wiring pattern 12a connecting multiple light sources 12 in series and wiring pattern 13a connecting multiple light sources 13 in series. The wiring patterns 12a and 13a are provided separately on the substrate 11 and are not electrically connected to each other. Furthermore, the wiring patterns 12a and 13a are each provided with a terminal portion (not shown) to which a different voltage is supplied. The wiring pattern 12a corresponds to the first wiring in the present invention, and the wiring pattern 13a corresponds to the second wiring in the present invention.

[0070] In the example shown in FIG. 10( b), light sources 12 and 13 are mounted on separate substrates 11a and 11b, respectively. On substrate 11a, wiring pattern 12a connects multiple light sources 12 in series. On substrate 11b, wiring pattern 13a is connected to light source 13. Therefore, wiring patterns 12a and 13a are provided separately on substrates 11a and 11b and are not electrically connected to each other. Furthermore, wiring patterns 12a and 13a are each provided with a terminal portion (not shown) to which different voltages are supplied. Although FIGS. 10( a) and 10(b) show an example in which wiring pattern 12a connects multiple light sources 12 in series, wiring pattern 12a may also be connected in parallel to multiple light sources 12.

[0071] In the image projection unit 10 of this embodiment, the wiring patterns 12a and 13a that supply power to the light sources 12 and 13, respectively, are provided separately, so that different voltages can be applied to the light sources 12 and 13 using different signals. This allows the light sources 12 and 13 to be controlled using different PWM (Pulse Width Modulation) techniques, allowing the current values ​​and pulse widths flowing through the light sources 12 and 13 to be adjusted separately. When LEDs are used as the light sources 12 and 13, the color temperature of the light source 12 may change depending on conditions such as temperature. Therefore, by adjusting the pulse width and current value of the light source 13 in response to the change in color temperature of the light source 12, the change in color temperature of the first emitted light emitted from the light source 12 can be compensated for by the second emitted light emitted from the light source 13.

[0072] 11 is a chromaticity diagram illustrating chromaticity adjustment in the image projection unit 10 according to this embodiment. As an example, consider a case where a blue LED and a yellow phosphor are used as the light source 12, white light is emitted from the blue LED and yellow light wavelength-converted by the yellow phosphor, and blue light is emitted from the light source 13.

[0073] In this case, the white light emitted corresponds to the double-headed arrow connecting the light emitted by the blue LED (B-LED) and the light emitted by the yellow phosphor in the chromaticity diagram shown in Figure 11. If the balance between blue and yellow changes due to temperature changes or the wavelength conversion efficiency of the phosphor, the color temperature of the resulting white light will also change. Therefore, by adjusting the amount of blue light by increasing or decreasing the amount of second emitted light from the blue LED of light source 13, it is possible to irradiate the image display unit 17 with a white light of the desired color temperature.

[0074] The image projection device 100 projects a virtual image forward through the windshield WS and superimposes it on the background for the driver to view. In this case, if the background is white, such as a snowy landscape or a white wall, displaying the virtual image at a color temperature of 5000K to 6000K, which is similar to the color temperature of sunlight, reduces the visibility of the virtual image. Therefore, by increasing the amount of the second emitted light from the light source 13 and raising the color temperature of the backlight light, the visibility of the virtual image can be ensured even when it is superimposed on a white background.

[0075] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0076] This international application claims priority based on Japanese Patent Application No. 2023-124715, filed on July 31, 2023, the entire contents of which are incorporated herein by reference.

[0077] The above descriptions of specific embodiments of the present invention have been presented for purposes of illustration. They are not intended to be exhaustive or to limit the invention to the precise forms described. Numerous modifications and variations will be apparent to those skilled in the art in light of the above description.

[0078] 100...Image projection device 10...Image irradiation section 20...First mirror 30...Second mirror 40...Housing 11, 11a, 11b...Substrate 12, 13...Light source 12a, 13a...Wiring pattern 14...First lens 14a...Light incident section 14b...Light guide section 14c...Transmitting section 14d...Light incident surface 14e, 15a, 19a...Reflecting uneven section 14f...Light exit surface 14g...Incidence side space 15...Second lens 16...Light diffusion section 17...Image display section 18...Additional optical section 19...Third lens

Claims

1. A light source device that irradiates light to an irradiation section, comprising: a first light source that emits a first emitted light of a first wavelength; a second light source that emits a second emitted light of a second wavelength; and a light guiding member arranged between the first light source and the irradiation section, wherein the light guiding member has a transmissive portion that transmits the first emitted light from the first light source side toward the irradiation section, and the transmissive portion has a reflective uneven portion that internally guides the second emitted light and reflects it toward the irradiation section.

2. A light source device as described in claim 1, wherein the first light source and the second light source are mounted on a common substrate, the light-guiding member has a light guide portion connected to the side of the transmissive portion and guiding the second emitted light to the transmissive portion, and the light guide portion is curved from the light emission surface of the second light source to the side of the transmissive portion.

3. A light source device according to claim 1, characterized in that the light guide member has a transmissive portion that transmits the first emitted light, and the second light source is disposed opposite a side surface of the transmissive portion.

4. A light source device according to claim 3, characterized in that the first light source and the second light source are mounted on separate substrates.

5. A light source device according to claim 1, characterized in that the light guide member is disposed opposite the first light source and has a lens function for refracting the first emitted light and adjusting its orientation.

6. A light source device according to claim 1, comprising: a first wiring for supplying power to the first light source; and a second wiring for supplying power to the second light source, the first wiring and the second wiring being provided separately.

7. An image projection device comprising: a light source device according to any one of claims 1 to 6; an image display unit that displays an image using the first and second emitted light emitted from the light source device; and a projection optical unit that projects the first and second emitted light from the image display unit.

Images