Light source device and head-up display device

Abstract

The present invention provides a light source device and the like that can improve the manufacturing yield. The light source device includes: a light source; a collimator (140) that is disposed opposite to the light source and includes a reflection portion (142) that adjusts the focusing distance of light incident on the collimator (140) from the light source; and a light guide body disposed on the exit side of the collimator (140). The reflection portion (142) of the collimator (140) includes a normal focal length region (142a), a long focal length region (142c), and a short focal length region (142b). The normal focal length region (142a) converts the light emitted from the light source and incident on the collimator (140) into substantially parallel light. The long focal length region (142c) converts the light incident on the collimator (142) into light that is slightly more divergent than the substantially parallel light. The short focal length region (142b) converts the light incident on the collimator (140) into light that is slightly more convergent than the parallel light.

Description

Technical Field

[0001] The present invention relates to a light source device and a head-up display device. Background Art

[0002] Patent Document 1 discloses a light source device that is small, lightweight, has high light utilization efficiency, and is modularized so that it can be easily used as a planar light source. The light source device of Patent Document 1 includes a light source unit, a collimator, a polarization conversion element, and a light guide. Among them, the light source unit includes a plurality of semiconductor light source elements, the collimator includes a plurality of collimating elements respectively arranged on the light emission axes of the plurality of semiconductor light source elements, the polarization conversion element is arranged on the emission side of the collimator, and the light guide is arranged on the emission side of the polarization conversion element.

[0003] In addition, the plurality of semiconductor light source elements and the plurality of collimating elements are arranged in a first direction (X direction) orthogonal to the light emission axis. The polarization conversion element includes a polarization beam splitter and a phase plate that extend in the first direction and are arranged at positions symmetric with respect to a plane formed by the first direction and a second direction corresponding to the light emission axis.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: WO 2018 / 229961 Summary of the Invention

[0007] Technical Problem to be Solved by the Invention

[0008] The light source device of Patent Document 1 is used, for example, in a head-up display (HUD) for vehicles. The HUD projects various information such as driving information or navigation information such as vehicle speed or engine speed onto a windshield (front window glass) for display. When using the HUD, the driver can obtain the information required for driving without moving the line of sight to an instrument assembled on the instrument panel, that is, a so-called instrument panel. Therefore, the HUD can contribute to safe driving of automobiles and the like.

[0009] However, when the relative position between the light source and the collimator deviates from a specified position, there is a case where the brightness of the displayed image or the brightness unevenness of the displayed image deviates from the specified design value. Here, the brightness unevenness of the displayed image refers to the value obtained by dividing the minimum brightness in the displayed image by the central brightness of the displayed image. In other words, the brightness unevenness is defined by the ratio of the minimum brightness in the displayed image to the central brightness of the displayed image.

[0010] A product with the brightness of the displayed image or the uneven brightness of the displayed image deviating from the design value is a non-conforming product. Since high-precision alignment requirements are imposed on the light source and the collimator, it is difficult to improve the manufacturing yield.

[0011] The present invention has been completed in view of the above problems, and one of its objects is to provide a light source device and the like that can improve the manufacturing yield.

[0012] The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0013] Technical means for solving the problem

[0014] A summary of a representative one of the inventions disclosed in the present application is briefly described as follows. A representative light source device includes: a light source; a collimator that is disposed opposite to the light source and includes a reflecting portion that adjusts the focusing distance of the light incident from the light source to the collimator; and a light guide disposed on the exit side of the collimator. The reflecting portion of the collimator includes a normal focal length region, a long focal length region, and a short focal length region. The normal focal length region transforms the light emitted from the light source and incident on the collimator into substantially parallel light. The long focal length region transforms the light incident on the collimator into light that is slightly more divergent than the substantially parallel light. The short focal length region transforms the light incident on the collimator into light that is slightly more convergent than the parallel light.

[0015] Advantages of the invention

[0016] A brief description of the effects that can be obtained by a representative one of the technical solutions disclosed in the present application is as follows. That is, the manufacturing yield can be improved in a head-up display device. Description of the drawings

[0017] Figure 1 It is a schematic diagram showing a structural example of a vehicle equipped with a head-up display device according to an embodiment of the present invention.

[0018] Figure 2 It shows Figure 1 a schematic diagram of a structural example around the image display unit.

[0019] Figure 3 It shows Figure 2 a more detailed structural example and operation example around the image display unit in

[0020] Figure 4 It shows Figure 3 a perspective view of an external shape example of a HUD device including an image display unit.

[0021] Figure 5 It is a cross-sectional view showing an example of the structure of a light source device.

[0022] Figure 6It is a cross-sectional view showing an example of the structure of a collimator.

[0023] Figure 7 It represents Figure 1 A block diagram showing an example of the structure of the main part of the control system included in the head-up display device.

[0024] Figure 8 It represents Figure 6 A block diagram showing an example of the structure of the part related to the acquisition of vehicle information in

[0025] Figure 9 It is a diagram showing the structure of the collimator of the embodiment.

[0026] Figure 10 It is a diagram showing the distribution of the brightness of the display image of the embodiment.

[0027] Figure 11 It is a diagram showing the distribution of the brightness unevenness of the display image of the embodiment.

[0028] Figure 12 It is a cross-sectional view of an existing collimator.

[0029] Figure 13 It is a diagram showing the structure of the collimator of the comparative example. Detailed implementation mode

[0030] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, the same reference numerals are basically assigned to the same components, and the repeated explanations thereof are omitted.

[0031] "Outline of the HUD device"

[0032] Figure 1 It is a schematic diagram showing an example of the structure of a vehicle equipped with a head-up display device according to an embodiment of the present invention. Figure 1 The head-up display (HUD) device 1 is mounted on the vehicle 2. The vehicle 2 is typically an automobile, but is not necessarily limited thereto, and may be a rail vehicle or the like depending on the situation. The HUD device 1 acquires vehicle information 4 from various sensors and the like provided in various parts of the vehicle 2. Various sensors detect various events generated in the vehicle 2, for example, or periodically detect the values of various parameters related to the driving condition.

[0033] The vehicle information 4 includes, for example, speed information or gear information of the vehicle 2, steering wheel steering angle information, headlight lighting information, ambient light information, distance information, infrared information, engine ON / OFF information, camera image information inside and outside the vehicle, acceleration gyro information, GPS (Global Positioning System) information, navigation information, vehicle-to-vehicle communication information, and road-to-vehicle communication information, etc. The GPS information also includes the information of the current time. Based on such vehicle information 4, the HUD device 1 projects a projection image onto the display area 5 of the windshield 3 by using the image display unit 12. Thus, the HUD device 1 enables the driver of the vehicle 2 to view the scenery with the projection image superimposed thereon.

[0034] Figure 2 It represents Figure 1 A schematic diagram of a structural example around the image display unit. Figure 2 The image display unit 12 shown has an image display device 35 and mirrors M1, M2. The mirror M1 is, for example, a concave mirror (magnifying glass). The image display device 35 is, for example, a projector that projects an image formed on an LCD (Liquid Crystal Display) by using projection light emitted from a light source device 100 (details will be described later). The LCD generates and displays an image based on the image data instructed by the control unit. The mirrors M1, M2 are, for example, free-form mirrors or mirrors having a shape asymmetric with respect to the optical axis. The mirror M2 reflects the image generated (displayed) by the image display device 35 toward the mirror M1. The mirror M1 reflects and magnifies the image reflected by the mirror M2 toward the windshield 3 and projects it onto the display area 5 via the opening 7.

[0035] Thus, the driver 6 views the projection image projected on the display area 5 as a virtual image in front of the transparent windshield 3 in a manner superimposed on the scenery outside the vehicle (roads or buildings, people, etc.). In the projection image (virtual image), various images such as road signs, the current speed of the vehicle itself, and various information (AR information) added to the objects in the scenery are included. In addition, in Figure 2 , for example, by adjusting the setting angle of the mirror M1, the position of the display area 5 on the windshield 3 can be adjusted, and the position of the virtual image viewed by the driver 6 can be adjusted in the vertical direction. Additionally, for example, by further enlarging the area of the mirror M1, the area of the display area 5 can be enlarged, and more information can be projected onto the display area 5. Thus, an AR function of adding and displaying various information to the objects in the scenery can be achieved.

[0036] Figure 3 It represents Figure 2 A more detailed structural example and operation example of the periphery of the image display unit. Figure 4 It represents including Figure 3A perspective view of an example of the external shape of the HUD device of the image display unit. As Figure 3 shown, Figure 2 The image display device 35 specifically includes a light source device 100 that emits projection light, and a display panel 64 that generates (displays) an image to be projected onto the display area 5 by modulating the projection light from the light source device 100. The light source device 100 typically includes an LED (Light Emitting Diode) light source. The display panel 64 is typically a liquid crystal panel (LCD), which modulates the transmittance of the light from the light source device 100 for each pixel according to the input image data to form an image corresponding to the image data.

[0037] A condenser lens 63 is provided between the display panel 64 and the mirror M2. A drive mechanism 62 for changing the setting angle of the mirror M1 is mounted on the mirror M1. The drive mechanism 62 includes a stepping motor or the like. The drive mechanism 62 adjusts the position of the virtual image by changing the setting angle of the mirror M1.

[0038] In addition, in Figure 3 the image display device 35, the mirror M1 with the drive mechanism 62, the mirror M2, and the condenser lens 63 are housed together with various control parts (not shown) in the housing 61.

[0039] In Figure 4 an opening 7 is formed in the housing 61, and a transparent colored covering member 71 such as a glare trap is provided at the opening 7. Inside the housing 61, as Figure 3 shown, the mirror M1 is arranged so as to reflect the light from the mirror M2 toward the covering member 71 (opening 7).

[0040] "Structure of the Light Source Device"

[0041] Next, the structure of the light source device 100 will be described. Figure 5 is a cross-sectional view showing an example of the structure of the light source device. As Figure 5 shown, the light source device has an LED element (light source) 120, a collimator 140, a polarization conversion element 150, a light guide 160, etc. provided on a substrate. In addition, Figure 5 although only one LED element is shown in

[0042] The collimator 140 is provided for each LED element, and each collimator is disposed at a prescribed position (relative position) with respect to the corresponding LED element 120. That is, the number of collimators 140 is the same as the number of LED elements 120. The collimator 140 is an optical component that adjusts the traveling direction of light emitted from the LED element 120 and incident on the collimator 140. Specifically, the collimator 140 transforms the incident light into substantially parallel light by appropriately optimizing the shape of the reflection portion 142 in the reflection portion 142.

[0043] A polarization conversion element 150 is provided on the emission side of the collimator 140, that is, on the side opposite to the LED element 120. The collimator 140 transforms the light emitted from the LED element 120 into substantially parallel light so as to travel toward the polarization conversion element 150.

[0044] Figure 6 It is a cross-sectional view showing an example of the structure of the collimator. As Figure 6 shown, the incident portion 141 of the collimator 140 faces the LED element 120 and is formed in a shape recessed with respect to the LED element 120.

[0045] Here, hereinafter, a normal focal length region, a long focal length region, and a short focal length region are defined in the reflection portion 142 of the collimator 140. Among them, the normal focal length region is a region that transforms the light emitted from the center of the LED element 120 into substantially parallel light, the long focal length region is a region that transforms the emitted light into relatively divergent light with respect to the substantially parallel light, and the short focal length region is a region that transforms the emitted light into relatively convergent light with respect to the substantially parallel light.

[0046] The reflection portion 142 of the collimator 140 is as Figure 6 shown, and includes a normal focal length region 142a, a long focal length region 142c, and a short focal length region 142b. Among them, the normal focal length region 142a transforms the light emitted from the LED element 120 and incident on the collimator 140 into substantially parallel light, the long focal length region 142c transforms the incident light into light that is slightly more divergent than the substantially parallel light, and the short focal length region 142b transforms the incident light into light that is slightly more convergent than the parallel light.

[0047] The curvatures of the reflection surfaces on the outside of the normal focal length region 142a, the short focal length region 142b, and the long focal length region 142c are different. The curvature of the reflection surface of the short focal length region 142b is larger than that of the normal focal length region 142a. On the other hand, the curvature of the reflection surface of the long focal length region 142c is smaller than that of the normal focal length region 142a. In Figure 6In this case, when viewed from the side of the LED element 120, a plurality of long focal length regions 142c and short focal length regions 142c are alternately formed. In addition, a normal focal length region 142a is formed at the position farthest from the LED element 120. In addition, the arrangement of each focal length region is not limited to this. For example, they can also be alternately arranged as the normal focal length region 142a, the short focal length region 142b, and the long focal length region 142c. In addition, a short focal length region 142b or a long focal length region 142c can also be provided at the position farthest from the LED element 120.

[0048] In this way, by providing the normal focal length region 142a, the short focal length region 142b, and the long focal length region 142c in the reflection part 142 of the collimator 140, even when the relative position of the collimator 140 with respect to the LED element 120 is shifted, it is possible to suppress fluctuations in the brightness of the display image or unevenness in the brightness of the display image.

[0049] The shape of the reflection part 142 can also be different for each collimator 140. For example, when a plurality of collimators 140 are arranged in a row, the shape of the reflection part 142 can be made different between the collimator 140 on the central side and the collimator 140 on the end side. Thereby, the optical system can be optimized, the optical performance can be improved, and the utilization efficiency of light can be improved.

[0050] In addition, adjacent focal length regions are smoothly connected. In the Figure 6 example, the short focal length region 142b and the long focal length region 142c are smoothly connected. In addition, the long focal length region 142c and the normal focal length region 142a are smoothly connected. In addition, except Figure 6 for this, the short focal length region 142b and the normal focal length region 142a are also smoothly connected. That is, the normal focal length region 142a, the short focal length region 142b, and the long focal length region 142c are smoothly connected to each other.

[0051] Specifically, the curvatures of the respective focal length regions are different, but at the part where the focal length regions are connected, the curvatures of both focal length regions are almost the same. For example, the curvature at the part where the short focal length region 142b is connected to the long focal length region 142c is, for example, the same curvature as that of the normal focal length region 142a. Therefore, the short focal length region 142b and the long focal length region 142c locally include functions equivalent to those of the normal focal length region 142a. Therefore, as Figure 6 shown, even if the number of normal focal length regions 142a is small, it is possible to suppress a decrease in the performance of the light source device 100.

[0052] Figure 12 is a cross-sectional view of an existing collimator. As Figure 12As shown, the reflection part 542 of the existing collimator 540 is only the normal focal length region 542a. Therefore, when the relative position of the collimator 540 with respect to the LED element 120 shifts, the change in the brightness of the displayed image or the uneven brightness of the displayed image is relatively large.

[0053] The polarization conversion element 150 is as Figure 5 shown, and includes a polarization conversion prism 151 and a wave plate (phase difference plate) 152. The polarization conversion prism 151 is disposed opposite to the collimator 140. A part of the light incident on the polarization conversion prism 151 passes through the polarization conversion prism 151 as it is. This light exits from the central part on the exit side of the polarization conversion prism 151 and is incident on the light guide 160.

[0054] On the other hand, the remaining light is reflected within the polarization conversion prism 151 and then exits from the peripheral part on the exit side surrounding the central part on the exit side of the polarization conversion prism 151. A wave plate 152 is provided at the peripheral part on the exit side of the polarization conversion prism, and the light exiting from the peripheral part on the exit side of the polarization conversion prism 151 is incident on the wave plate 152. After the light incident on the wave plate 152 undergoes a prescribed polarization conversion in the wave plate 152, it is incident on the light guide 160.

[0055] The light guide 160 is as Figure 5 shown, and is, for example, in the shape of a pyramid with a substantially triangular cross section. In the light guide reflection part 162, as Figure 5 shown, a large number of reflection surfaces 162a and connection surfaces 162b are alternately formed in a zigzag shape. The light incident from the light guide entrance part 161 is reflected by the reflection surfaces 162a of the light guide reflection part 162 and travels toward the light guide exit part.

[0056] A diffusion plate 170 is provided at a position opposite to the light guide exit part 163. In addition, a display panel 64 is provided on the exit side of the diffusion plate 170. The light exiting from the light guide exit part 163 becomes uniform in intensity through the diffusion plate 170. The light exiting from the diffusion plate 170 is incident on the display panel 64 as projection light for an image. In this way, the light exiting from the collimator 140 is guided to the entrance surface of the display panel 64 disposed above in the drawing by the action of the light guide 160.

[0057] "Structure of the Control System of the HUD Device"

[0058] Figure 7 is a block diagram showing an example of the structure of the main part of the control system included in the head-up display device Figure 1 . Figure 8 is a block diagram showing an example of the structure of the part related to the acquisition of vehicle information in Figure 7 . Figure 7The head-up display (HUD) device 1 shown includes a control unit (ECU: Electronic Control Unit), a speaker 11, and an image display unit 12. The image display unit 12 includes Figure 3 the image display device 35 shown, a mirror M1 with a drive mechanism 62, and the like.

[0059] The control unit 10 mainly controls the display of a projected image (virtual image) in the HUD device 1, sound output, and the like. The control unit 10 is constituted by, for example, a wiring circuit board, etc., and this wiring circuit board is mounted, for example, in Figure 4 the housing 61. The control unit 10 includes a vehicle information acquisition unit 15, a microcontroller (MCU) 16, a non-volatile memory 17, a volatile memory 18, a sound driver 19, a display driver 20, a communication unit 21, etc. mounted on the wiring circuit board. As is well known, the MCU 16 has various peripheral functions in addition to the CPU (Central Processing Unit). Therefore, Figure 7 each module other than the MCU 16 in the control unit 10 can also be appropriately mounted in the MCU 16.

[0060] The vehicle information acquisition unit 15 is, for example, a CAN (Controller Area Network) interface or a LIN (Local Interconnect Network) interface, etc., and acquires vehicle information 4 based on communication protocols such as CAN or LIN. The vehicle information 4 is Figure 8 generated by information acquisition devices such as various sensors connected to the vehicle information acquisition unit 15. Figure 8 One example of various information acquisition devices is shown.

[0061] For example, a vehicle speed sensor 41 detects Figure 1 the speed of the vehicle 2, and generates speed information as the detection result. A gear position sensor 42 detects the current gear position and generates gear position information as the detection result. A steering wheel steering angle sensor 43 detects the current steering wheel steering angle and generates steering wheel steering angle information as the detection result. A headlight sensor 44 detects the ON / OFF of the headlights and generates headlight lighting information as the detection result.

[0062] The illuminance sensor 45 and the chromaticity sensor 46 detect ambient light and generate ambient light information as the detection result. The distance measurement sensor 47 measures the distance between the vehicle 2 and an external object and generates distance information as the detection result. The infrared sensor 48 detects the presence or absence of an object in the vicinity of the vehicle 2 and its distance, etc., and generates infrared information as the detection result. The engine start sensor 49 detects the ON / OFF of the engine and generates ON / OFF information as the detection result.

[0063] The acceleration sensor 50 and the gyro sensor 51 respectively detect the acceleration and angular velocity of the vehicle 2 and generate acceleration gyro information indicating the attitude and movement of the vehicle 2 as the detection result. The temperature sensor 52 measures the temperature inside and outside the vehicle and generates temperature information as the detection result. For example, the temperature sensor 52 can be used to detect the ambient temperature Ta around the HUD device 1. However, as Figure 4 described above, a temperature sensor can also be additionally installed inside the HUD device 1.

[0064] The vehicle-to-road communication wireless transceiver 53 generates vehicle-to-road communication information through vehicle-to-road communication between the vehicle 2 and roads, signs, traffic lights, etc. The vehicle-to-vehicle communication wireless transceiver 54 generates vehicle-to-vehicle communication information through vehicle-to-vehicle communication between the vehicle 2 and other surrounding vehicles. The in-vehicle camera 55 and the out-of-vehicle camera 56 respectively capture the inside and outside of the vehicle to generate in-vehicle camera image information and out-of-vehicle camera image information. Specifically, the in-vehicle camera 55 is, for example, a DMS (Driver Monitoring System) camera that captures Figure 2 the attitude of the driver 6 or the position and movement of the eyes, etc. In this case, by analyzing the captured image, the fatigue condition of the driver 6 or the position of the line of sight can be grasped.

[0065] On the other hand, the out-of-vehicle camera 56 captures the surrounding conditions such as the front or rear of the vehicle 2, for example. In this case, by analyzing the captured image, the presence or absence of obstacles such as other vehicles or people in the vicinity, the building or terrain, the road conditions such as rain or snow, ice, bumps, etc., and road signs can be grasped. In addition, the out-of-vehicle camera 56 also includes, for example, a dash cam that records the driving conditions using images.

[0066] The GPS receiver 57 generates GPS information obtained by receiving GPS signals. For example, the current time can be obtained by the GPS receiver 57. The VICS (Vehicle Information and Communication System, registered trademark) receiver 58 generates VICS information obtained by receiving VICS signals. The GPS receiver 57 or the VICS receiver 58 may also be provided as part of a navigation system. In addition, regarding Figure 8 For various information acquisition devices, deletion can be appropriately performed, or other types of devices can be added, or replaced with other types of devices.

[0067] In Figure 7 , the MCU 16 receives such vehicle information 4 via the vehicle information acquisition unit 15, and generates sound data for the speaker 11, image data for the image display device 35, etc. based on the vehicle information 4 and the like. Specifically, the MCU 16 includes a sound data generation unit 27, an image data generation unit 28, a distortion correction unit 29, a light source adjustment unit 30, a mirror adjustment unit 31, and a protection processing unit 75. These units are mainly implemented by the CPU executing programs stored in the non-volatile memory 17 or the volatile memory 18.

[0068] The sound data generation unit 27 generates sound data based on the vehicle information 4 and the like as needed. The sound data is generated, for example, when performing voice guidance of the navigation system, or when warning the driver 6 through the AR function. The sound driver 19 drives the speaker 11 based on the sound data, causing the speaker 11 to output sound.

[0069] The image data generation unit 28 generates image data for determining the display content of the projected image projected in the display area 5 such as Figure 2 . The distortion correction unit 29 generates corrected image data obtained by performing distortion correction on the image data from the image data generation unit 28. Specifically, the distortion correction unit 29 corrects the distortion of the image caused by the curvature of the windshield 3 when projecting the image from the image display device 35 onto the display area 5 as shown in Figure 2 .

[0070] The display driver 20 drives each display element (pixel) included in the display panel 64 within the image display device 35 based on the corrected image data from the distortion correction unit 29. Thus, the image display device 35 generates (displays) an image for projection onto the display area 5 based on the corrected image data. The light source adjustment unit 30 controls the brightness of the light source 65 within the image display device 35. The mirror adjustment unit 31 changes the setting angle of the mirror M1 within the image display unit 12 via the drive mechanism 62 when it is necessary to adjust the position of the display area 5 on the windshield 3.

[0071] The non-volatile memory 17 mainly pre-stores programs to be executed by the CPU within the MCU 16, setting parameters used in the processing of each part within the MCU 16, specified sound data, image data, and the like.

[0072] The volatile memory 18 mainly appropriately holds the acquired vehicle information 4 and various data used in the processing of each part within the MCU 16. The communication unit 21 communicates based on communication protocols such as CAN or LIN between it and the outside of the HUD device 1. The communication unit 21 may also be integrated with the vehicle information acquisition unit 15. In addition, Figure 4 each part within the control unit (ECU) 10 may also be appropriately implemented by an FPGA (Field Programmable Gate Array) or the like.

[0073] [Embodiment]

[0074] Next, an embodiment of the HUD using the light source device including the collimator 140 of the present embodiment will be described. Figure 9 is a diagram illustrating the structure of the collimator of the embodiment. In the present embodiment, a structure in which eight collimators 140 are arranged in a row is used.

[0075] Figure 9 The Z-axis is the axis passing through the center of the LED element 120 and the center of the collimator 140, for example, the vertical direction of the LED substrate. The R-axis in the vertical direction in the drawing is the axis in the radial direction of the collimator. The intersection of the Z-axis and the R-axis is the reference point O. The structure of the central four reflecting portions 142 among the collimators arranged in a row is represented by Figure 9 Equation 1. On the other hand, the structure of the four reflecting portions 142 at both ends among the collimators 140 arranged in a row is represented by Figure 9 Equation 2.

[0076] Here, the shape of the reflecting surface (i.e., the shape of the outer contour) in the reflecting portion 142 is defined by a concentric circle shape with R>0 and the Z-axis as the rotation center in Equations 1 and 2.

[0077] Figure 13This is a diagram showing the structure of the collimator of the comparative example. Figure 13 The Z-axis and R-axis shown are the same as Figure 9 those. The structure of the reflection part 542 of the collimator 540 of the comparative example is represented by Figure 13 Equation 3.

[0078] Figure 10 This is a diagram showing the distribution of the brightness of the display image of the embodiment. In addition, Figure 10 the results obtained using the collimator 540 of the comparative example described in Figure 12 are also shown. Figure 10 The horizontal axis of represents the position offset of the collimator relative to the LED element. "0" on the horizontal axis is the ideal mounting position of the collimator relative to the LED element. Figure 10 The vertical axis of represents the ratio (relative brightness) of the brightness of the display image to the brightness of the display image when the collimator is in the ideal position (hereinafter, also referred to as the brightness of the ideal display image).

[0079] According to Figure 10 it can be seen that when the collimator 140 of the present embodiment is offset to the side opposite to the LED element 120 (the positive side in the figure) compared to the ideal position, the decrease in the brightness of the display image is smaller than that of the comparative example. In particular, as the collimator 140 moves away from the LED element 120, the difference in the brightness of the display image between the present embodiment and the comparative example becomes larger, and an improvement in the brightness of the display image can be seen.

[0080] In addition, when the collimator 140 of the present embodiment is offset to the side of the LED element 120 (the negative side in the figure) compared to the ideal position, the brightness of the display image is lower than that when using the existing collimator 540. However, the brightness of the display image in this area reaches 90% or more of the brightness of the ideal display image. Therefore, even in this case, sufficient brightness of the display image for use can be ensured, and the decrease in the brightness of the display image in this area does not become a problem. In this way, by adopting the present embodiment, even if the position of the collimator 140 changes, the variation in the amount of projection light incident on the display panel 64 can be suppressed.

[0081] Next, the brightness unevenness of the display image will be described. Figure 11 This is a diagram showing the distribution of the brightness unevenness of the display image of the embodiment. In addition, Figure 11 the results obtained using the collimator 540 of the comparative example are also shown. Figure 11 The horizontal axis of represents the position offset of the collimator 140 relative to the LED element 120. "0" on the horizontal axis is the ideal position of the collimator 140 relative to the LED element 120. Figure 11 The vertical axis represents the brightness unevenness of the display image by expressing the ratio of the minimum brightness in the display image to the central brightness of the display image. Specifically, Figure 11The non-uniformity of the brightness of the display image shown on the vertical axis is with respect to the non-uniformity of the brightness of the display image when the collimator 140 is in the ideal position (relative brightness non-uniformity).

[0082] As Figure 11 shown, in either the case where the collimator 140 is shifted toward the LED element 120 side (negative side in the figure) compared to the ideal position, or the case where the collimator 140 is shifted toward the side opposite to the LED element 120 (positive side in the figure) compared to the ideal position, the relative brightness non-uniformity is improved. That is, in this embodiment, the non-uniformity of the brightness of the display image becomes smaller. In this way, by adopting this embodiment, even when the position of the collimator 140 is shifted, it is possible to suppress the variation in the amount of projection light between the regions of the display panel 64.

[0083] <Main effects of this embodiment>

[0084] According to this embodiment, the reflection part 142 of the collimator 140 includes a normal focal length region 142a, a short focal length region 142b, and a long focal length region 142c. With this structure, even when the position (relative position) of the collimator 140 with respect to the LED element 120 is shifted, it is possible to suppress the reduction in the brightness of the display image and improve the non-uniformity of the brightness of the display image. Thereby, the alignment accuracy requirements between the LED element 120 as the light source and the collimator 140 can be relaxed, so the manufacturing yield can be improved.

[0085] In addition, according to this embodiment, the curvatures of the reflecting surfaces in the normal focal length region 142a, the short focal length region 142b, and the long focal length region 142c are different respectively. Specifically, the curvature of the reflecting surface of the short focal length region 142b is larger than that of the normal focal length region 142a, and the curvature of the reflecting surface of the long focal length region 142c is smaller than that of the normal focal length region 142a. With this structure, even when the position of the collimator 140 is shifted, it is possible to suppress the reduction in the amount of projection light supplied to the display panel 64 and suppress the variation in the amount of projection light between the regions of the display panel 64.

[0086] In addition, according to this embodiment, in the collimator 140, a plurality of long focal length regions 142c and short focal length regions 142b are alternately formed. With this structure, even when the position of the collimator 140 is shifted, it is possible to suppress the reduction in the amount of projection light supplied to the display panel 64 and suppress the variation in the amount of projection light between the regions of the display panel 64.

[0087] In addition, according to the present embodiment, the normal focal length region 142a, the short focal length region 142b, and the long focal length region 142c are smoothly connected to each other. According to this structure, it is possible to ensure the amount of light when there is no positional deviation, and it is possible to suppress a decrease in the amount of projected light supplied to the display panel 64 and suppress variations in the amount of projected light between the respective regions of the display panel 64.

[0088] In addition, according to the present embodiment, the shape of the reflecting portion 142 is different for each collimator 140. According to this structure, the optical system of the light source device 100 can be optimized.

[0089] The invention completed by the present inventor has been specifically described based on the embodiments, but the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist thereof. For example, the above embodiments are detailed descriptions for making the present invention easy to understand, and the present invention is not limited to having all the structures described. In addition, a part of the structure of a certain embodiment can be replaced with the structure of another embodiment, and the structure of another embodiment can also be added to the structure of a certain embodiment. In addition, other structures can be added to, deleted from, or replaced with a part of the structure of each embodiment.

[0090] Description of Reference Numerals

[0091] 1... HUD device, 3... windshield, 5... display area, 10... control unit (ECU), 35... image display device, 64... display panel, 100... light source device, 140... collimator, 142... reflecting portion, 142a... normal focal length region, 142b... short focal length region, 142c... long focal length region, 160... light guide.

Claims

1. A light source device, characterized in that, comprising: a light source; a collimator, which is disposed opposite to the light source and includes a reflecting portion for adjusting the focusing distance of light incident from the light source; and a light guide disposed on the exit side of the collimator, the reflecting portion of the collimator includes a normal focal length region, a long focal length region, and a short focal length region, wherein the normal focal length region transforms the light emitted from the light source and incident on the collimator into substantially parallel light, the long focal length region transforms the light incident on the collimator into light that is slightly more divergent than the substantially parallel light, and the short focal length region transforms the light incident on the collimator into light that is slightly more convergent than the parallel light.

2. The light source device according to claim 1, characterized in that: the curvatures of the reflecting surfaces in the normal focal length region, the short focal length region, and the long focal length region are respectively different.

3. The light source device according to claim 2, characterized in that: the curvature of the reflecting surface in the short focal length region is larger than the curvature of the reflecting surface in the normal focal length region, and the curvature of the reflecting surface in the long focal length region is smaller than the curvature of the reflecting surface in the normal focal length region.

4. The light source device according to claim 1, characterized in that: in the collimator, a plurality of the long focal length regions and the short focal length regions are alternately formed.

5. The light source device according to claim 1, characterized in that: the normal focal length region, the short focal length region, and the long focal length region are smoothly connected to each other.

6. The light source device according to claim 1, characterized in that, comprising: a plurality of the light sources; and a plurality of the collimators corresponding to each of the light sources, the shape of the reflecting portion is different for each collimator.

7. The light source device according to claim 1, characterized in that, comprising: a plurality of the light sources; and a plurality of the collimators corresponding to each of the light sources, a plurality of the light sources are arranged in a row, the shape of the reflecting portion of the collimator corresponding to the light source on the central side and the shape of the reflecting portion of the collimator corresponding to the light source on the end side are different from each other.

8. A head-up display device, which projects an image onto a display area of a windshield so that a driver of a vehicle can view a scenery with the image superimposed thereon, characterized in that, comprising: a light source device; a display panel, which generates an image for projection onto the display area by modulating light from the light source; and a mirror, which reflects the image generated by the display panel and projects it onto the display area, the light source device includes: a light source; a collimator, which is disposed opposite to the light source and includes a reflecting portion for adjusting the focusing distance of light incident from the light source; and a light guide disposed on the exit side of the collimator, The reflecting portion of the collimator includes a normal focal length region, a long focal length region, and a short focal length region. Among them, the normal focal length region transforms the light emitted from the light source and incident on the collimator into substantially parallel light, the long focal length region transforms the light incident on the collimator into light that is slightly more divergent than the substantially parallel light, and the short focal length region transforms the light incident on the collimator into light that is slightly more convergent than the parallel light.

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