WO2023080003A1

WO2023080003A1 - Light source device and head-up display device

Info

Publication number: WO2023080003A1
Application number: PCT/JP2022/039552
Authority: WO
Inventors: 利昌永井; 智貴山本; 寿紀杉山
Original assignee: マクセル株式会社
Priority date: 2021-11-08
Filing date: 2022-10-24
Publication date: 2023-05-11
Also published as: JP2023069769A

Abstract

Provided is a light source device which can improve a manufacturing yield. Also, provided is a light source device which can reduce polarization loss that occurs depending on residual stress in a light guide body.　A light source device (100) of the present invention comprises: an LED element (121) as a slight source; a collimator (140) that is disposed on an emission side of the light source, and adjusts a traveling direction of light incident from the light source; a light guide body (160) that is disposed on an emission side of the collimator (140), and guides light incident from the collimator (140) toward a display panel (64); and a polarization conversion element (150) that is disposed between the light guide body (160) and the display panel (64) on an emission side of the light guide body (160), and makes polarization properties of light incident from the light guide body (160) uniform.

Description

Light source device and head-up display device

The present invention relates to the technology of light source devices and head-up display devices.

Patent Document 1 discloses a light source device that is compact and lightweight, has a high light utilization rate, and can be modularized and easily used as a planar light source. The light source device of Patent Document 1 includes: a light source section including a plurality of semiconductor light source elements; a collimator including a plurality of collimator elements arranged on the light emission axis of each of the plurality of semiconductor light source elements; A polarization conversion element is provided, and a light guide is provided on the output side of the polarization conversion element. Also, the plurality of semiconductor light source elements and the plurality of collimator elements are arranged in a first direction (X direction) perpendicular to the light emission axis, and the polarization conversion element extends in the first direction and emits light in the first direction. It includes a polarizing beam splitter and a phase plate positioned symmetrically with respect to a plane formed by a second direction corresponding to the axis.

WO2018/229961

The light source device of Patent Document 1 is used, for example, in a head-up display (head-up display, sometimes referred to as "HUD") for vehicles. The HUD projects various types of information such as driving information such as vehicle speed and engine speed and navigation information onto a windshield (in other words, a windshield) and displays them. By using the HUD, the driver can obtain information necessary for driving without moving his/her line of sight to a dashboard or the like incorporated in the dashboard. Therefore, the HUD contributes to safe driving of automobiles and the like.

By the way, in the conventional HUD device, a light source (for example, an LED element), a collimator, a polarization conversion element, a light guide, a diffusion plate, and a display panel (for example, a liquid crystal display) are arranged in this order from the light source side. ing. If the display panel is a liquid crystal display (LCD), the LCD panel can only use, for example, linearly polarized light as backlight (light source light for generating projection light). Therefore, if it is desired to improve the light utilization efficiency, it is necessary to use a polarization conversion element. The polarization conversion element converts random polarized light in the approximately parallel light from the collimator into linear polarized light. The light guide controls the distribution of the linearly polarized light and guides it toward the display panel.

On the other hand, the light guide is a resin molded product with a large thickness, and there is inherent residual stress due to this. When the linearly polarized light from the polarization conversion element passes through a portion with residual stress (residual stress portion) when passing through the light guide, the light passing through the residual stress portion has a phase difference. occurs. Therefore, the phase difference changes the polarization state. In other words, light beams passing through each part of the light guide are emitted as light beams with different polarization states according to the difference in residual stress of each part. The light enters the LCD panel. Therefore, a loss of polarization occurs on the LCD panel.

This polarization loss can cause a decrease in image light brightness, uneven brightness, and uneven color in the HUD. If the luminance is lowered, the HUD product will be defective, resulting in a poor manufacturing yield.

In order to prevent the above-mentioned decrease in luminance, etc., it is necessary to strictly inspect the specifications of residual stress even as a light guide, resulting in poor manufacturing yield.

One of the objects of the present invention is to provide a light source device etc. capable of improving the manufacturing yield. Another object is to be able to reduce the polarization loss that occurs in response to residual stress in the lightguide.

A representative embodiment of the present invention has the configuration shown below. A light source device according to an embodiment includes a light source, a collimator arranged on the exit side of the light source and adjusting a traveling direction of light incident from the light source, and a light guide that guides the light emitted from the light guide toward the display panel; and a polarization conversion element to align.

According to the representative embodiments of the present invention, it is possible to improve the manufacturing yield of light source devices and head-up display devices. According to representative embodiments of the present invention, polarization loss caused by residual stress in the light guide can be reduced. Problems, configurations, effects, etc. other than those described above will be described in the mode for carrying out the invention.

1 is a schematic diagram showing a configuration example of a vehicle equipped with a head-up display device (HUD device) according to an embodiment of the invention; FIG. 2 is a schematic diagram showing a configuration example of a video display unit and the like that constitute the HUD device of FIG. 1; FIG. FIG. 3 is a schematic diagram showing a more detailed configuration example of the image display unit of FIG. 2; FIG. 4 is a perspective view showing an appearance example of a HUD device including the video display unit of FIG. 3; 2 is a functional block diagram showing a configuration example of a control system of the HUD device of FIG. 1; FIG. FIG. 6 is a functional block diagram showing a configuration example related to a vehicle information acquisition unit shown in FIG. 5; 1 is a diagram showing a configuration of a light source device according to Embodiment 1; FIG. 4A and 4B are diagrams showing configuration examples of an LED substrate and a collimator, which constitute the light source device of the first embodiment; FIG. 3 is a cross-sectional view showing a configuration example of a collimator that constitutes the light source device of Embodiment 1. FIG. 3A and 3B are diagrams showing a configuration example of a light guide that constitutes the light source device of the first embodiment; FIG. 2 is a perspective view showing a configuration example of a polarization conversion element that constitutes the light source device of Embodiment 1. FIG. 4 is a cross-sectional view showing a configuration example of a polarization conversion element that constitutes the light source device of Embodiment 1. FIG. FIG. 4 is a diagram showing a configuration of a light source device of a modified example of Embodiment 1; FIG. 10 is a diagram showing the configuration of a light source device according to Embodiment 2; FIG. 10 is a diagram showing the configuration of a light source device according to Embodiment 3; FIG. 10 is a diagram showing the configuration of a light source device according to Embodiment 4; It is a figure which shows the structure of the light source device of a comparative example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, in principle, the same parts are denoted by the same reference numerals, and repeated explanations are omitted. In the drawings, the representation of each component may not represent the actual position, size, shape, range, etc. in order to facilitate understanding of the invention.

For the purpose of explanation, when explaining the processing by the program, there are cases where the program, function, processing unit, etc. are mainly explained, but the main body as hardware for them is the processor or the controller composed of the processor etc. , devices, computers, systems, etc. A computer executes processing according to a program read out on a memory by a processor while appropriately using resources such as a memory and a communication interface. As a result, predetermined functions, processing units, and the like are realized. The processor is composed of, for example, a semiconductor device such as a CPU or GPU. A processor is composed of devices and circuits capable of performing predetermined operations. The processing can be implemented not only by software program processing but also by dedicated circuits. FPGA, ASIC, CPLD, etc. can be applied to the dedicated circuit.

<Embodiment 1>
A light source device and the like according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 to 12 and the like. The HUD device of Embodiment 1 includes the light source device of Embodiment 1 and a display panel.

The light source device 100 of Embodiment 1 shown in FIG. 150 is not between the collimator 140 and the light guide 160 (in other words, before the light guide 160), but between the light guide 160 and the diffusion plate 170 (or the display panel 64) (in other words, the light guide 160). (after)).

In the light source device 100 of Embodiment 1, the polarization conversion element 150 downstream of the light guide 160 converts randomly polarized light from the light guide 160 into linearly polarized light. Therefore, even if residual stress exists in the light guide 160 , the influence of the residual stress, ie, the change in polarization state, is dealt with by conversion into linearly polarized light in the polarization conversion element 150 . Incident light to the LCD panel 64 becomes light in which the effect of residual stress, that is, the change in polarization state is eliminated. In other words, the light source device 100 of Embodiment 1 can eliminate the influence of the residual stress of the light guide 160 on the polarized light.

In particular, the polarization conversion element 150 may be arranged near the LCD panel 64 (at a position closer to the LCD panel 64 than the light guide 160). A diffusion plate 170 or the like may be arranged between the polarization conversion element 150 and the LCD panel 64 . Between the polarization conversion element 150 and the LCD panel 64, a thin lens or a Fresnel lens, which will be described later (Embodiment 2, etc.), may be arranged as an optical element. The function of this optical element (thin lens or Fresnel lens) is to control the light distribution to the lens 63 (FIG. 3) in the rear stage of the LCD panel 64 (control of the incident angle and area of light rays). This optical element may be placed either forward or backward with respect to the diffusion plate 170 . A member in which this optical element and the diffusion plate 170 are integrated may be used.

[HUD device and vehicle]
FIG. 1 is a schematic diagram showing a configuration example of a vehicle 2 equipped with a head-up display device (HUD device) 1 according to Embodiment 1. As shown in FIG. A HUD device 1 in FIG. 1 is mounted on a vehicle 2 . The vehicle 2 is typically an automobile, but is not necessarily limited to this, and may be a railroad vehicle or the like depending on the case.

The HUD device 1 acquires vehicle information 4 from various sensors installed in each part of the vehicle 2 . Various sensors, for example, detect various events occurring in the vehicle 2, and periodically detect the values of various parameters related to driving conditions. The vehicle information 4 includes, for example, speed information and gear information of the vehicle 2, steering angle information, lamp lighting information, external light information, distance information, infrared information, engine ON/OFF information, camera image information, acceleration gyro information, It includes GPS (Global Positioning System) information, navigation information, vehicle-to-vehicle communication information, road-to-vehicle communication information, and the like. The camera image information includes in-vehicle camera image information and exterior camera image information. GPS information includes current time information in addition to latitude and longitude.

Based on such vehicle information 4, the HUD device 1 projects an image onto the display area 5 of the windshield 3 using the image display unit 12 (Fig. 2). As a result, the HUD device 1 allows the driver of the vehicle 2 (driver's viewpoint) 6 to visually recognize the scenery superimposed as the virtual image 9 corresponding to the projected image.

FIG. 2 is a schematic diagram showing a configuration example of part of the vehicle 2 in FIG. The image display unit 12 is housed in the housing of the HUD device 1 . The image display unit 12 of FIG. 2 has an image display device 35, a reflection mirror M1, and a reflection mirror M2. Reflecting mirror M1 is a first mirror arranged at a later stage on the optical path. Reflecting mirror M2 is a second mirror arranged in the front stage on the optical path. The image light (in other words, projection light) emitted from the image display device 35 is reflected through the reflection mirrors M2 and M1 and emitted from the opening 71 (FIG. 3) of the housing. Image light emitted from the image display unit 12 travels through the opening 7 of the dashboard of the vehicle 2 toward the display area 5 of the windshield 3 . The image light is reflected by the display area 5 of the windshield 3 and goes to the viewpoint 6. - 特許庁A driver can visually recognize the image light as a virtual image 9 from a viewpoint 6 .

[Image display unit]
FIG. 3 shows a more detailed configuration example of the video display unit 12 of FIG. The image display unit 12 of FIG. 3 includes an image display device 35, a condenser lens 63, a reflection mirror M2, and a reflection mirror M1 with a drive mechanism 62. FIG. The image display device 35, the condenser lens 63, the reflection mirror M2, and the reflection mirror M1 with the driving mechanism 62 shown in FIG. An opening 71 is provided in the housing 61 . In the configuration example of FIG. 3, the optical system for projecting the image light onto the display area 5 includes a condensing lens 63, a reflecting mirror M2, and a reflecting mirror M1.

The video display device 35 includes, for example, the light source device 100 of Embodiment 1 (details will be described later) and a display panel 64 . The image display device 35 is a projector (projection-type image display device) that projects an image formed on the display panel 64 using light emitted from the light source device 100 (in other words, light source light). The light source device 100 typically includes an LED (Light Emitting Diode) light source.

The display panel 64 is typically a liquid crystal display (LCD). The display panel 64 creates an image based on the image data instructed and input from the control device, and displays it on the display screen of the display panel 64 . The display panel 64 modulates the transmittance of the light from the light source device 100 for each pixel according to the image data, thereby forming an image to be projected onto the display area 5 and generating image light (in other words, projection light). emitted as In the configuration example of FIG. 3, the direction of emission of image light from the image display device 35 is the vertically upward direction (Z direction). The dashed-dotted arrow indicates the optical axis of the image light.

A condenser lens 63 is installed as a lens between the display panel 64 of the image display device 35 and the reflection mirror M2. This condensing lens 63 is a lens for adjusting the optical distance necessary for forming the virtual image 9, and has the function of enlarging the projection light from the display panel 64 and causing it to enter the second mirror M2.

The reflecting mirror M1 and the reflecting mirror M2 are, for example, free-form surface mirrors or mirrors having an asymmetrical shape with respect to the optical axis. The reflection mirror M2 reflects the image light emitted from the image display device 35 and condensed through the condensing lens 63 toward the reflection mirror M1. Reflecting mirror M1 is, for example, a concave mirror (in other words, a magnifying glass). The reflection mirror M1 reflects and expands the image light reflected by the reflection mirror M2 toward the windshield 3 through the opening 71 at an angle set by the drive mechanism 62, and projects it onto the display area 5.

As a result, the driver 6 (FIG. 2) sees the image projected on the display area 5 as a virtual image 9 beyond the transparent windshield 3, which is superimposed on the scenery outside the vehicle (for example, roads, buildings, people, etc.). Observe in shape. The virtual image 9, which is a projected image, includes various information such as road signs, the current speed of the vehicle, and various information added to objects on the landscape. As a result, an augmented reality (AR) function or the like is realized that displays an object on the landscape with various information added.

2 and 3, the positions of the display area 5 and the virtual image 9 on the windshield 3 can be adjusted by adjusting the installation angle of the reflection mirror M1 with the driving mechanism 62. It's becoming A driving mechanism 62 for changing the installation angle of the reflecting mirror M1 is attached to the reflecting mirror M1. The drive mechanism 62 is a mechanism including a stepping motor and the like. The driving mechanism 62 changes the installation angle of the reflecting mirror M1 based on the control from the control device or based on the user's manual operation. As a result, the position of the virtual image 9 visually recognized by the driver 6 in the display area 5 can be adjusted, for example, in the vertical direction.

Further, for example, by increasing the area of the reflecting mirror M1, the area of the display area 5 can be expanded, and more information can be projected onto the display area 5.

FIG. 4 is a perspective view showing the appearance of a mounting example of the HUD device 1 including the video display unit 12 of FIG. An opening 71 is formed in the housing 61 . The opening 71 is provided with a transparent cover member 71a called a glare trap (anti-dazzle) or the like. Inside the housing 61, a reflecting mirror M1 is installed so as to reflect the light from the reflecting mirror M2 toward the cover member 71a of the opening 71. As shown in FIG.

[Control system of HUD device]
FIG. 5 is a functional block diagram showing a configuration example of main parts of the control system in the HUD device 1 of FIG. FIG. 6 is a functional block diagram showing a configuration example of the vehicle information acquiring section 15, which is a part involved in acquiring the vehicle information 4 in FIG.

The HUD device 1 of FIG. 5 includes a control device 10, a video display unit 12, a speaker 11, and a solar radiation sensor 66. The control device 10 is composed of, for example, an electronic control unit (ECU). The video display unit 12 has the configuration shown in FIGS. 2 and 3. FIG.

The control device 10 corresponds to a controller that controls the entire HUD device 1 and each part, and mainly controls the display of the projected image (virtual image 9) in the HUD device 1, the control of the audio output, and the like. The control device 10 is configured by, for example, a wiring board. This wiring board is mounted, for example, in the housing 61 shown in FIGS. The control device 10 includes a vehicle information acquisition unit 15, a microcontroller (MCU) 16, a nonvolatile memory 17, a volatile memory 18, an audio driver 19, a display driver 20, and a communication device mounted on the wiring board. A part 21 and the like are provided.

As is widely known, the MCU 16 includes a processor such as a CPU (Central Processing Unit), memory, and various peripheral functions. Therefore, each block in the control device 10 except for the MCU 16 may be mounted in the MCU 16 as appropriate.

The vehicle information acquisition unit 15 acquires vehicle information 4 based on a communication protocol compatible with, for example, a CAN (Controller Area Network) interface or a LIN (Local Interconnect Network) interface.

As shown in FIG. 6, the vehicle information 4 is generated by an information acquisition device such as various sensors connected to the vehicle information acquisition unit 15. FIG. 6 shows an example of various information acquisition devices. Note that the various information acquisition devices in FIG. 6 can be deleted, added to other types of devices, or replaced with other types of devices as appropriate.

For example, the vehicle speed sensor 41 detects the speed of the vehicle 2 in FIG. 1 and generates speed information as a detection result. The shift position sensor 42 detects the current gear and generates gear information as a detection result. The steering wheel steering angle sensor 43 detects the current steering wheel steering angle and generates steering wheel steering angle information as a detection result. The headlight sensor 44 detects ON/OFF of the headlight and generates lamp lighting information as a detection result.

The illuminance sensor 45 and the chromaticity sensor 46 detect outside light and generate outside light information as detection results. The ranging sensor 47 detects the distance between the vehicle 2 and an external object, and generates distance information as a detection result. The infrared sensor 48 detects the presence or absence of an object in the short distance of the vehicle 2, the distance, and the like, and generates infrared information as a detection result. The engine start sensor 49 detects ON/OFF of the engine and generates ON/OFF information as a detection result.

The acceleration sensor 50 and the gyro sensor 51 detect the acceleration and angular velocity of the vehicle 2, and generate acceleration gyro information representing the attitude and behavior of the vehicle 2 as detection results. The temperature sensor 52 detects the temperature inside and outside the vehicle and generates temperature information as a detection result. For example, the temperature sensor 52 can detect the ambient temperature of the HUD device 1 . A temperature sensor may be separately mounted in the HUD device 1 .

The road-to-vehicle communication radio transmitter/receiver 53 generates road-to-vehicle communication information through road-to-vehicle communication between the vehicle 2 and roads, signs, signals, and the like. The vehicle-to-vehicle communication radio transmitter/receiver 54 generates vehicle-to-vehicle communication information through vehicle-to-vehicle communication between the vehicle 2 and other vehicles in the vicinity. The in-vehicle camera 55 and the exterior camera 56 generate in-vehicle camera image information and exterior camera image information by photographing the interior and exterior of the vehicle. Specifically, the in-vehicle camera 55 is, for example, a DMS (Driver Monitoring System) camera that captures the posture of the driver 6 in FIG. 2 and the position and movement of the eyes. In this case, it is possible to grasp the fatigue state of the driver 6, the position of the line of sight, etc. by analyzing the imaged video.

On the other hand, the vehicle exterior camera 56 photographs the surrounding conditions such as the front and rear of the vehicle 2, for example. In this case, by analyzing the captured images, it is possible to detect the presence of obstacles such as other vehicles and people in the surrounding area, buildings and topography, road conditions such as rain, snow, ice, unevenness, road signs, etc. become comprehensible. In addition, the vehicle exterior camera 56 includes, for example, a drive recorder that records a video of the driving situation.

The GPS receiver 57 generates GPS information obtained by receiving GPS signals from GPS satellites. For example, the GPS receiver 57 can obtain the current time, latitude and longitude. A VICS (Vehicle Information and Communication System, registered trademark) receiver 58 generates VICS information obtained by receiving VICS signals. The GPS receiver 57 and VICS receiver 58 may be provided as part of the navigation system.

In FIG. 5, the MCU 16 receives such vehicle information 4 via the vehicle information acquisition unit 15. The MCU 16 generates audio data directed to the speaker 11, image data directed to the image display device 35, and the like based on the vehicle information 4 and the like. The MCU 16 includes an audio data generation section 27 , a video data generation section 28 , a distortion correction section 29 , a light source adjustment section 30 , a mirror adjustment section 31 and a protection processing section 75 . These units are mainly implemented by the CPU of the MCU 16 reading and executing programs stored in the nonvolatile memory 17 or volatile memory 18 .

The audio data generation unit 27 generates audio data based on the vehicle information 4 and the like as necessary. The voice data is generated, for example, when performing voice guidance of the navigation system or when issuing a warning to the driver 6 by the AR function. The audio driver 19 drives the speaker 11 based on the audio data and causes the speaker 11 to output audio.

Based on the vehicle information 4 and the like, the video data generation unit 28 generates video data that defines the display contents of the projection video projected onto the display area 5 shown in FIG. 2 and the like. The distortion correction unit 29 generates corrected image data by applying distortion correction to the image data from the image data generation unit 28 . Specifically, the distortion corrector 29 corrects image distortion caused by the curvature of the windshield 3 when the image from the image display device 35 is projected onto the display area 5, as shown in FIG.

The display driver 20 drives each display element (pixel) included in the display panel 64 in the image display device 35 based on the corrected image data from the distortion correction unit 29 . Thereby, the image display device 35 creates and displays an image to be projected onto the display area 5 based on the corrected image data.

The light source adjustment unit 30 controls the brightness of the light source (LED elements described later) in the image display device 35, and the like. When the position of the display area 5 on the windshield 3 needs to be adjusted, the mirror adjusting section 31 changes the installation angle of the reflecting mirror M1 through driving the driving mechanism 62 in the image display unit 12 of FIG. .

The non-volatile memory 17 mainly stores in advance programs executed by the CPU in the MCU 16, setting parameters used in processing of each part in the MCU 16, prescribed audio data and video data, and the like.

The volatile memory 18 mainly stores the acquired vehicle information 4 and various data used in the processing process of each part in the MCU 16 as appropriate. The communication unit 21 is a device in which a communication interface is mounted, and communicates with the outside of the HUD device 1 based on a communication protocol such as CAN or LIN. The communication unit 21 may be integrated with the vehicle information acquisition unit 15 . Each unit in the control device 10 of FIG. 5 may be appropriately implemented by a dedicated circuit such as an FPGA (Field Programmable Gate Array).

[Comparative example]
FIG. 17 shows a configuration example of a light source device as a comparative example with respect to the first embodiment. This light source device corresponds to the light source device described in Patent Document 1. This light source device includes, in order from the light source side, an LED substrate 91 provided with a plurality of LED elements 91A as light sources, a collimator 92, a polarization conversion element 93, a light guide 94, and a diffusion plate 95. . FIG. 17 also shows an LCD panel 64 as a display panel. Since FIG. 17 is a YZ cross section, only one LED element 91A and one collimator element are shown. LED elements 91A are similarly provided, and correspondingly a plurality of collimator elements are similarly provided in the X direction.

A collimator 92 is provided on the side of the LED substrate 91 where light from the LED elements 91A is emitted (positive side in the Y direction). The collimator 92 converts the light from the LED element 91A into substantially parallel light. A polarization conversion element 93 is provided on the light exit side (positive side in the Y direction) from the collimator 92 . The polarization conversion element 93 converts the light having random polarization as substantially parallel light from the collimator 92 into light having linear polarization. The polarization conversion element 93 is configured by combining a polarization conversion prism 931 and a wavelength plate 932 .

A light guide 94 is provided on the light exit side (positive side in the Y direction) from the polarization conversion element 93 . The light guide 94 causes the linearly polarized light from the polarization conversion element 93 to enter from the incident portion 941 and is reflected by the reflecting portion 942 toward the Z direction different from the Y direction, that is, the direction in which the display panel 64 is located. light distribution control. The light guide 94 has a reflecting portion 942 that performs reflection and light distribution control. The reflecting portion 942 is formed by alternately repeating reflecting surfaces and connecting surfaces.

The exit surface of the exit portion 943 of the light guide 94 has, for example, a free curved surface shape for light distribution control.

The light emitted from the emitting portion 943 of the light guide 94 is directed roughly upward in the Z direction, slightly obliquely upward in this example. A diffusion plate 95 is provided on the light exit side (positive side in the Z direction) of the light guide 94 . The light from the light guide 94 is diffused by the diffusion plate 95 and enters the rear side of the display panel 64 . The display panel 64 generates image light using this incident light as a backlight.

[Light source device]
Next, a detailed configuration example of the light source device 100 of FIG. 3 will be described as the light source device of the first embodiment. FIG. 7 is a cross-sectional view showing an example of the configuration of the light source device 100 according to Embodiment 1. As shown in FIG. In addition to the light source device 100 , FIG. 7 also shows a display panel 64 (LCD panel), that is, shows a configuration example of the image display device 35 . In FIG. 7, the YZ cross section is schematically shown using (X, Y, Z) as the direction in space and the coordinate system. The X and Y directions are two orthogonal directions forming a horizontal plane, and the Z direction is the vertical direction. The X direction is a direction perpendicular to the paper surface of FIG. 7, and is one direction (horizontal direction, left-right direction) that constitutes the main surface of the LED substrate 120 (the surface on which the LED elements 121 are arranged). , the other direction (vertical direction, vertical direction) constituting the main surface of the LED substrate 120, the Y direction is the direction perpendicular to the main surface of the LED substrate 120, and is the optical axis of light emitted from the LED element 121. direction. The display panel 64 is connected to the control device 10 (FIG. 5) through a flexible printed circuit board 64f, for example.

The light source device 100 of Embodiment 1 includes an LED substrate 120 provided with a plurality of LED elements 121 as a light source, a collimator 140, a light guide 160, a polarization conversion element 150, and a diffusion plate 170. . These components have a predetermined positional relationship and are fixed to the housing 61 (FIG. 3). Since FIG. 7 is a cross-sectional view, only one LED element 121 and one collimator element 141 are shown. An LED element 121 is provided. Correspondingly, a plurality of collimator elements 141 are provided in the X direction. The LED element 121 is an example of a semiconductor light source element.

As will be described later (FIG. 8), the LED substrate 120 has a plurality of LED elements 121 arranged in the X direction on the XZ plane, which is the main surface. Each LED element 121 emits light as a light source. Light emission from each LED element 121 is light emission with an optical axis in the Y direction, and the light emission is incident on each collimator element 141 of the collimator 140 .

The collimator 140 has a collimator element 141 provided corresponding to each LED element 121 as described later (FIG. 8). The collimator 140 has a plurality of collimator elements 141 arranged in the X direction. Collimator 140 has a plurality of collimator elements 141 as a whole. The number of collimator elements 141 is the same as the number of LED elements 121 . Each collimator element 141 is installed at a predetermined position, in other words, at a predetermined relative position with respect to the associated LED element 121 .

The collimator 140 is an optical member that adjusts the traveling direction of light emitted from the LED element 121 and incident on the collimator 140 . The collimator 140 adjusts the light emitted from the LED element 121 so that it travels toward the light guide 160 . The collimator element 141 has an incident portion 14a, a reflecting portion 14b, and an emitting portion 14c. Specifically, each collimator element 141 of the collimator 140 receives the light from the LED element 121 through the incident portion 14a, and converts the light into approximately parallel light along the Y direction by the shape of the reflective portion 14b optimized for design. , exit from the exit portion 14c. A light ray 130 is a light ray that constitutes the light that is emitted from the collimator 140 and travels toward the positive side in the Y direction.

A light guide 160 is provided with a predetermined space on the output side (positive side in the Y direction) of the collimator 140 opposite to the LED element 121 . The light guide 160 has an incident portion 161 , a reflecting portion 162 and an emitting portion 163 . The incident part 161 is a light guide body incident part having an incident surface on which the light from the collimator 140 is incident. The reflecting portion 162 is a light guide reflecting portion having a reflecting surface that reflects the light from the incident portion 161 . The emitting portion 163 is a light guide emitting portion having an emitting surface for emitting light from the reflecting portion 162 .

The light guide 160 allows the light in the Y direction from the collimator 140 to be incident from the incident portion 161 and reflected by the reflecting portion 162 toward the Z direction (that is, the direction in which the display panel 64 is located) different from the Y direction. lead to The light guide 160 has a function of performing light distribution control as well as its reflection. The light guide 160 includes a reflecting portion 162 having functions of reflection and light distribution control. The reflecting portion 162 is formed by alternately repeating a reflecting surface and a connecting surface, which will be described later (FIG. 10).

The light emitted from the emitting portion 163 of the light guide 160 is directed roughly upward in the Z direction, in this example slightly obliquely to the upper right. A polarization conversion element 150 is provided with a predetermined space on the light exit side (positive side in the Z direction) from the light guide 160 . An optical axis 700 indicated by a dashed-dotted line is the optical axis of light emitted from the light guide 160 and directed to the display panel 64 via the polarization conversion element 150. there is

As shown, the direction of light emitted from the emitting portion 163 of the light guide 160 (the direction of the optical axis 700) is perpendicular to the plane of incidence of the polarization conversion element 150. FIG. In other words, the polarization conversion element 150 is arranged such that the plane of incidence is perpendicular to the direction of light emitted from the emission portion 163 of the light guide 160 (the direction of the optical axis 700).

The polarization conversion element 150 (FIGS. 11 and 12 to be described later) receives randomly polarized light from the light guide 160 in the direction of the optical axis 700 from the incident surface, and converts the light into linearly polarized light as polarization conversion. , the converted linearly polarized light is emitted in the direction of the optical axis 700 from the emission surface. All of the light emitted from the emission surface of the polarization conversion element 150 has linear polarization characteristics.

The polarization conversion element 150 is configured by combining a polarization conversion prism 151 and a wavelength plate 152 (see later-described FIG. 11, etc.). The basic function of the polarization conversion element 150 is to convert randomly polarized light from the light source (LED element 121) into linearly polarized light in correspondence with the configuration of the polarizing plate provided in the LCD panel 64. be. Light with that linear polarization is the preferred backlight for the LCD panel 64 .

A diffusion plate 170 is arranged with a predetermined space on the light exit side from the polarization conversion element 150 . The diffusion plate 170 is a diffusion element having a diffusion function of diffusing the light from the polarization conversion element 150 to make the intensity uniform. The diffusion plate 170 receives the linearly polarized light (substantially parallel light) from the polarization conversion element 150 , diffuses the light, and emits the light toward the LCD panel 64 . More specifically, the diffuser plate 170 is arranged with its main surface inclined with respect to the polarization conversion element 150 . The diffuser plate 170 is not perpendicular to the optical axis 700 of the light from the polarization conversion element 150, but is arranged slightly downward on the positive side in the Y direction in the drawing. The diffuser plate 170 has a shape that realizes a diffusion function, for example, by molding with a mold.

A display panel 64 is provided on the emission side of the diffusion plate 170 with a predetermined space therebetween. The display panel 64 is also substantially the same as the diffuser plate 170 , and is arranged with its main surface inclined with respect to the polarization conversion element 150 . The light from the polarization conversion element 150 is diffused through the diffuser plate 170 to make the intensity uniform, and the light is incident on the rear side of the display panel 64 . The display panel 64 generates image light based on the incident light.

In the configuration example of FIG. 7, the direction of the light emitted from the light guide 160 and incident on the display panel 64 via the polarization conversion element 150 is an optical axis slightly tilted to the right with respect to the illustrated Z direction. 700 direction. This is a design example for suppressing external light reflection in the optical system of the HUD device, and is not limited to this. Depending on the design, the direction of the light emitted from the light guide 160 and incident on the display panel 64 via the polarization conversion element 150 may be the vertical direction (Z direction) or may be slightly oblique left with respect to the Z direction. may be tilted toward (a modified example to be described later).

In Embodiment 1, the exit surface of the exit portion 163 of the light guide 160 in FIG. 7 does not need to have a free curved surface shape for the light distribution control function as in the comparative example (FIG. 17). It is configured. The light distribution control function is, for example, a function of controlling light distribution to the lens 63 arranged behind the display panel 64 . In Embodiment 1, when this light distribution control function is implemented, a free curved surface shape for the light distribution control function is implemented, for example, on the diffusion plate 170 . In other words, diffusion plate 170 in Embodiment 1 is an optical element having a light distribution control function in addition to a diffusion function, and has a shape for realizing those functions. The diffusing plate 170 is not limited in mounting details as long as those shapes are mounted on the entrance surface and the exit surface. The diffuser plate 170 may have, for example, a free curved surface shape for light distribution control function on the entrance surface and a shape for diffusion function on the exit surface, or vice versa.

[LED board]
FIG. 8 shows an XY plan view as an explanatory diagram showing an arrangement configuration example of the plurality of LED elements 121 of the LED substrate 120 of FIG. 7 and the plurality of collimator elements 141 of the collimator 140. As shown in FIG. The configuration example of FIG. 8 shows five portions of the plurality of LED elements 121 and the plurality of collimator elements 141 arranged in one row in the X direction. , 121-5 as the plurality of LED elements 121 and 141-1, . . . , 141-5 as the plurality of collimator elements 141 . These multiple LED elements 121 and multiple collimator elements 141 are arranged at a predetermined pitch in the X direction. The dashed-dotted arrow indicates the direction of the optical axis of light emitted from each LED element 121, and corresponds to the Y direction.

As the main surface of the LED substrate 120, each LED element 121 is provided so as to protrude on the positive side in the Y direction from the XZ plane on which the LED element 121 is provided. A plurality of collimator elements 141 are arranged such that the central position of each LED element 121 corresponds to the central position of the collimator element 141 . In addition, each output part 14 c of the plurality of collimator elements 141 can be mounted like a substrate common to the plurality of collimator elements 141 . In addition, it is possible without being limited to such a configuration example of the LED substrate 120 and the collimator 140 . For example, two or more LED elements 121 or collimator elements 141 may be arranged in the Z direction.

[Collimator]
FIG. 9 shows a YZ plane view as a cross-sectional view showing an example of the configuration of the collimator element 141 of the collimator 140 of FIG. Light emitted from the LED element 121 includes light beams diverging in each direction with the Y direction as the optical axis 901, as shown. An optical axis 901 is an axis passing through the center of the LED element 121 and the center of the collimator element 141 . An axis 902 indicated by a dashed arrow with respect to the optical axis 901 is a radial axis of the collimator element 141 .

The incident portion 14a of the collimator element 141 is a concave portion that is open facing the LED element 121 side (negative side in the Y direction) and has a concave curved surface. The light emitting surface of the LED element 121 and the opening surface of the recess are arranged close to each other. The light-emitting surface of the LED element 121 may be placed inside the recess. The incident portion 14a guides the light from the LED element 121 to the reflecting portion 14b and the emitting portion 14c. Some of the rays that have entered the concave portion of the incident portion 14a go to the emitting portion 14c via the bottom surface of the concave portion. The bottom surface of the recess has, for example, a convex curved surface on the incident side (negative side in the Y direction) as an incident surface, as shown in the drawing. Another part of the light rays that have entered the concave portion of the incident portion 14a travels to the reflecting portion 14b via the side surface of the concave portion.

The reflecting portion 14b of the collimator element 141 has a rotationally symmetrical shape with the optical axis 901 as the central axis of rotation, for example, a roughly parabolic shape (or conical shape). The reflecting portion 14b includes an outer peripheral surface having a predetermined shape as a reflecting surface. The reflecting portion 14b reflects the light from the incident portion 14a toward a predetermined focal point and guides it to the emitting portion 14c. Light from the incident portion 14a is totally reflected by the reflecting surface of the reflecting portion 14b and travels to the emitting portion 14c. The shape of the reflecting portion 14b is optimized and designed for light collection and light distribution control.

The light from the incident portion 14a and the light from the reflecting portion 14b are emitted in the Y direction as light rays 130 from the emission surface of the emission portion 14c. The output surface of the output portion 14c has a flat or curved shape. The exit surface of the exit portion 14c may have a convex curved surface on the exit side (the positive side in the Y direction) at a location facing the entrance surface of the entrance portion 14a. Light rays emitted from the emission surface of the emission portion 14c are substantially parallel rays as shown. The collimator element 141 achieves a predetermined light collecting function and the like by means of the shapes of the incident portion 14a, the reflecting portion 14b, and the emitting portion 14c.

It should be noted that the plurality of collimator elements 141 (FIG. 8) in the collimator 140 may have different optical characteristics such as different shapes of the reflecting portions 14b for each collimator element 141. For example, in a plurality of collimator elements 141 in one row, the shape of the reflecting portion 14b may be different between the collimator element 141 on the central side and the collimator element 141 on the peripheral side in the X direction. For example, as the shape of the reflecting portion 14b, focal areas (areas with different curvatures of the reflecting surface) for forming different focal points for each position may be provided. As a result, the optical system of the light source device 100 can be optimized, and the light utilization efficiency can be improved.

[Light guide]
FIG. 10 is an explanatory diagram showing a configuration example of the light guide 160. As shown in FIG. FIG. 10A is a perspective view showing an overview of the outer shape of the light guide 160. FIG. The light guide 160 has a roughly triangular prism shape as shown, and has an incident portion 161 , a reflecting portion 162 and an emitting portion 163 . When looking at the YZ cross section, it has a roughly triangular shape. A fixing portion 165 for fixing the light guide 160 is also provided on the side portion 164 of the light guide 160 . The light guide 160 is formed by resin molding using translucent resin such as acrylic.

The incident surface of the incident part 161 is roughly arranged on the XZ plane, and is not limited to a flat surface, and may have a curved surface shape (for example, a free curved surface shape) for light distribution control as shown in the figure. good. The reflecting surface of the reflecting portion 162 is arranged so as to be inclined with respect to the Y direction and the Z direction. Output portion 163 has a plane as an output surface. The plane, which is the emission surface, may be arranged on the XY plane, or may be inclined with respect to the XY plane as shown in FIG. state).

Although the exit surface of the exit portion 163 is flat in Embodiment 1, it is not limited to this, and may have a curved surface shape (for example, a free curved surface shape) for light distribution control as a modification.

(B) of FIG. 10 is an explanatory diagram of the details of the reflector 162 in particular. (B) shows a part of the reflecting surface of the reflecting section 162 . When this reflecting surface is enlarged, as shown, a plurality of reflecting surfaces 162a and a plurality of connecting surfaces 162b are alternately formed in a sawtooth shape. In FIG. 7 and the like, the plurality of reflecting surfaces 162a of the reflecting section 162 are schematically shown to be rougher than they actually are for the sake of clarity. is provided. The light incident from the incident portion 161 is totally reflected by the reflecting surfaces (plurality of reflecting surfaces 162 a ) of the reflecting portion 162 and travels toward the emitting portion 163 .

Each reflecting surface 162a (a line segment rising to the right in the drawing) is formed at a predetermined angle (for example, an angle greater than 0 degree and 43 degrees or less, reflecting surface elevation angle) with respect to the horizontal plane (XY plane). It is Each connecting surface 162b (a line segment extending substantially horizontally in the drawing) forms a predetermined angle (a relative angle between the reflecting surface 162a and the connecting surface 162b. For example, 90 degrees or more) with respect to the adjacent reflecting surface 162a. 180 degrees or less.).

[Polarization conversion element]
FIG. 11 is an explanatory diagram showing a configuration example of the polarization conversion element 150, and particularly shows a perspective view of the incident side (incident surface arranged on the XY plane) viewed obliquely from above. 12 shows a YZ plane view as a cross-sectional view of the polarization conversion element 150. As shown in FIG. As shown in FIG. 11, the polarization conversion element 150 as a whole has a rectangular entrance surface 150a (XY plane) and an exit surface 150b (XY plane) that are relatively long in the X direction and short in the Y direction. , is a roughly rectangular parallelepiped (in other words, plate-shaped) element. In FIG. 7, the polarization conversion element 150 is arranged slightly tilted with respect to the Z direction. The polarization conversion prism 151 is configured by combining a translucent member and a polarizing beam splitter (PBS) film.

In FIG. 11, polarization conversion element 150 includes

translucent members

1101, 1102, 1103, 1104, and 1105, PBS film 1111 and reflection film 1112, and wavelength plate 152, which constitute polarization conversion prism 151 described above. It is configured with The wave plate 152 is an optical element that performs predetermined polarization conversion, such as half-wave (λ/2) polarization conversion, in other words, a half wave plate. Incidentally, the polarization conversion element 150 may be accommodated in a holder (not shown). The holder is a component for fixing a plurality of components such as translucent members in the arrangement relationship shown in FIG. 11 .

Each translucent member, PBS film 1111 and reflective film 1112 are arranged symmetrically with respect to the XZ plane 1100 in FIG. The angle ε is the angle of arrangement of the PBS film 1111 and the like with respect to the Z direction, and is designed as a predetermined angle. The translucent member 1101 is a right-angled triangular prism-shaped block.

Translucent members

1102 and 1104 are parallelogram-shaped blocks. The translucent member 1103 is a triangular prism-shaped block. A PBS film 1111 is provided between the

translucent members

1102 and 1104 and the translucent member 1103 . A reflective film 1112 is provided between the

translucent members

1101 and 1105 and the

translucent members

1102 and 1104 . Wave plate 152 is provided in output side peripheral portion 1212 .

The PBS film 1111 (specifically, an electric multilayer film) converts incident light into P-polarized light (polarized light with an electric field oscillating parallel to the plane of incidence) and S-polarized light (polarized light with an electric field perpendicular to the plane of incidence) that is reflected light. is an element that separates the oscillating polarized light) and the Randomly polarized light is converted into linearly polarized light by the action of the PBS film 1111 .

The polarization conversion prism 151 is arranged to face the exit surface of the exit portion 163 of the light guide 160 . Light (randomly polarized light) from the exit surface of the light guide 160 is directed in the Z direction to the center of the incident side (translucent members 1102, 1104), which is a predetermined area of the incident surface 150a of the polarization conversion prism 151. area corresponding to ). Note that light with random polarization is also indicated by circled x marks. Light with linear polarization is also indicated by circled arrows.

Part of the light incident on the incident surface 150a (for example, the light ray 1201 in FIG. 12) passes through the polarization conversion prism 151 (the

translucent members

1102 and 1104, the PBS film 1111, and the translucent member 1103) as it is. . Light passing through the PBS film 1111 is converted from random polarized light to linear polarized light. This linearly polarized light is emitted in the Z direction from the central portion 1211 on the emission side, which is a predetermined area (area corresponding to the translucent member 1103) on the emission surface 150b of the polarization conversion prism 151. FIG.

On the other hand, the other light among the light incident on the incident surface 150a is reflected inside the polarization conversion prism 151 (the

translucent members

1102 and 1104, the PBS film 1111, and the reflective film 1112), and then is reflected by the wavelength plate on the exit surface 150b. 152 is emitted in the Z direction from the emission side peripheral portion 1212, which is a predetermined area. The exit-side peripheral portion 1212 is arranged outside the exit-side central portion 1211 in the Y direction. Light reflected by the PBS film 1111 remains randomly polarized. The light reflected by the PBS film 1111 is reflected by the reflective film 1112 from the Y direction to the Z direction. The light reflected by the reflective film 1112 enters and passes through the wavelength plate 152, thereby being converted from random polarized light into linear polarized light.

As described above, the light emitted in the Z direction from a predetermined region (the output-side central portion 1211 and the output-side peripheral portion 1212) of the output surface 150b of the polarization conversion element 150 passes through a predetermined region (the incident side) of the incident surface 150a. While being expanded in the Y direction from the central portion), all of the light becomes linearly polarized light.

Even if the incident light of the polarization conversion element 150 undergoes a polarization change according to the residual stress of the light guide 160, the random polarized light in the incident light is transformed into the linearly polarized light as described above by the function of the polarization conversion element 150. is converted to The emitted light having this linear polarization passes through the diffusion plate 170 and enters the LCD panel, which is the display panel 64, and functions as a suitable backlight for the LCD panel.

[Effects, etc.]
As described above, according to Embodiment 1, it is possible to provide a light source device and the like capable of improving the manufacturing yield. According to Embodiment 1, the manufacturing yield of the HUD device and the light guide can be improved, and the manufacturing cost can be reduced. According to Embodiment 1, by devising the layout of the light source device and the like, it is possible to reduce the polarization loss that occurs according to the residual stress of the light guide. According to Embodiment 1, from the reduction of polarization loss, the brightness of the HUD image is increased, the in-plane uniformity of image brightness is improved (in other words, the brightness unevenness is reduced), and the uniformity of image chromaticity is improved (in other words, reduction of color unevenness) can be realized. According to Embodiment 1, even if residual stress due to resin molding is inherent in the light guide, it is allowed to some extent, so the specification of the light guide does not have to be too strict, and the manufacturing yield can be improved. .

[Modification]
FIG. 13 shows the configuration of a light source device 100 according to a modification of the first embodiment. This modified example differs from the first embodiment in the arrangement direction of the polarization conversion element 150 and the direction of the optical axis of the light incident on the display panel 64 from the light source device 100 . The polarization conversion element 150 in FIG. 13 is arranged such that the negative side of the Y-axis is slightly inclined downward when the Y-axis is horizontal. In Embodiment 1 described above, the light from the light guide 160 to the display panel 64 is emitted in a slightly upward right direction with respect to the Z-axis (vertical direction). On the other hand, in this modified example, the light from the light guide 160 to the display panel 64 is emitted in a slightly upper left direction with respect to the Z-axis (vertical direction). The basic effect is the same in any form. In either form, the above-described lens 63 and second mirror M2 are arranged in front of the projected light from the display panel 64 .

<Embodiment 2>
FIG. 14 is a YZ plane view showing the configuration of the light source device 100 according to the second embodiment. The second embodiment is different from the first embodiment in that a thin lens 180, which is a light distribution control element, is additionally provided. In FIG. 14, the thin lens 180 is provided on the optical path between the polarization conversion element 150 and the display panel 64 at a position slightly spaced in front of the diffusion plate 170 . Polarization conversion element 150 in the second embodiment is arranged between light guide 160 and thin lens 180 .

The thin lens 180 is a light distribution control element, and has a light distribution control function of controlling light distribution to the lens 63 (FIG. 3) in the rear stage of the LCD panel 64 . The light distribution control function of the thin lens 180 is, in other words, a function of adjusting the direction of incidence of each light ray on a predetermined area of the entrance surface of the lens 63 . Diffusion plate 170 has a shape for light distribution control function in addition to diffusion function.

In the configuration example of FIG. 14, the light distribution control function that combines the thin lens 180 and the diffusion plate 170 adjusts the incident light to the LCD panel 64 so that it is suitable. is adjusted so that the incident light of

In the second embodiment, thin lens 180 and diffuser plate 170, which are light distribution control elements, are provided with light distribution control elements based on a free-form surface shape, which was performed by output portion 943 of light guide 94 in the comparative example (FIG. 17). functions are also implemented. In other words, the exit portion 163 of the light guide 160 according to Embodiment 2 does not need to have a free-form surface shape on the exit surface, and is formed, for example, in a planar shape.

In Embodiment 2 and the like, the polarization conversion element 150 arranged behind the light guide 160 changes the direction ( In other words, the range of the incident angle) is limited, and it is desirable to set the direction perpendicular to the incident surface 150a (the direction of the optical axis 700 in FIG. 7, the Z direction in FIG. 12). For example,

light rays

1251 and 1252 that are not incident perpendicular to the plane of incidence 150a in FIG. 12 do not become efficient light rays. Therefore, when the light distribution is controlled by the free-form surface shape as in the comparative example at the output portion 163 of the light guide 160, the light whose light distribution is controlled is transferred to the polarization conversion element arranged behind the light guide 160. 150 cannot be efficiently incident on the area of the incident surface 150a.

Therefore, in Embodiment 2 and the like, thin lens 180 and diffuser plate 170 (at least one of them is sufficient, but in Embodiment 2, both of them are used), which are light distribution control elements, have a light distribution control function based on a free-form surface shape. are also mounted together, and the light emitting surface of the light emitting portion 163 of the light guide 160 has a planar shape. In Embodiment 2, both the thin lens 180 and the diffusion plate 170 are equipped with a light distribution control function based on a free-form surface shape. In other words, a predetermined light distribution control function is realized by a combination of the free curved surface shape of the thin lens 180 and the free curved surface shape of the diffusion plate 170 . The free curved surface shape of the diffusion plate 170 is formed, for example, on one surface of the diffusion plate 170 by molding using a mold.

According to the light source device 100 of Embodiment 2, the same effects as those of Embodiment 1 can be obtained. Although thin lens 180 is required in Embodiment 2, formation of a free-form surface shape on the exit surface of light guide 160 is not required.

As a modification of the second embodiment, a Fresnel lens may be applied instead of the thin lens 180, which is the light distribution control element. As a modification, the thin lens 180 or the like, which is the light distribution control element, may be arranged behind the diffusion plate 170 and before the display panel 64 .

<Embodiment 3>
FIG. 15 is a YZ plane view showing the configuration of the light source device 100 according to the third embodiment. Embodiment 3 corresponds to a modification of Embodiment 2, and differs from

Embodiments

1 and 2 in that diffusion sheet 175 is applied instead of diffusion plate 170 and a thin light distribution control element is used. A diffusion sheet 175 is arranged in front of the lens 180 . In other words, in Embodiment 3, the thin lens 180, which is the light distribution control element, is arranged behind the diffusion sheet 175, which is the diffusion element. Diffusion sheet 175 is a thin sheet having a predetermined diffusion function. In the configuration example of FIG. 15, a diffusion sheet 175 is attached to the incident surface of the thin lens 180, for example. According to the light source device 100 of Embodiment 3, the same effects as those of Embodiment 2 can be obtained.

As a modification of the third embodiment, it is possible to provide a diffusion element such as the diffusion sheet 175 together with the holding member at a distance in front of the thin lens 180 .

<Embodiment 4>
FIG. 16 is a YZ plane view showing the configuration of the light source device 100 according to the fourth embodiment. Embodiment 4 is provided as one element in which the diffusion element and the light distribution control element described above are integrated ("diffusion function integrated thin lens", in other words, "diffusion/light distribution control element"). .

In FIG. 16, a diffusion/light distribution control element 190 (thin lens integrated with diffusion function) is provided between the polarization conversion element 150 and the display panel 64 . The polarization conversion element 150 in Embodiment 4 is arranged between the light guide 160 and its diffusion/light distribution control element 190 .

The diffusion/light distribution control element 190 is an element having a shape such as a free-form surface for realizing both the above-described diffusion function and light distribution control function, based on a thin lens. Various implementation details are possible and non-limiting. For example, with respect to the entrance surface and the exit surface of the diffusion/light distribution control element 190, the entrance surface may have the shape, the exit surface may have the shape, or the entrance surface and the exit surface may have the same shape. The shape may be implemented by dividing the As an example, the diffusion/light distribution control element 190 in FIG. 16 has a plane-based shape for the diffusion function (for example, a porous shape obtained by a print transfer method) on the entrance surface, and the above-mentioned lens on the exit surface. 63 has a shape for light distribution control function. That is, the shape of the exit surface of the diffusion/light distribution control element 190 in FIG. 16 is the same as the shape of the exit surface of the thin lens 180 in FIGS.

According to the fourth embodiment, the same effects as those of the first embodiment and the like can be obtained, and the constituent elements arranged between the polarization conversion element 150 and the LCD panel 64 are combined into a single diffusion/light distribution control element. Element 190 can suffice.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. Addition, deletion, replacement, etc. are possible for the components of the embodiments, except for essential components. Unless otherwise specified, each component may be singular or plural. A configuration in which various configuration examples are combined is also possible.

With the technology according to the present embodiment, it is possible to reduce polarization loss, increase light utilization efficiency, and achieve high brightness images. As a result, in addition to navigation information such as the destination and speed projected on the windshield, it is also possible to view images of information necessary for driving, such as alert information when oncoming vehicles or pedestrians are detected, making it possible to make the vehicle safer. Traffic accidents can be prevented by providing an information display device (head-up display device) that contributes to driving assistance. In this way, we will contribute to "3 good health and well-being for all" in the Sustainable Development Goals (SDGs) advocated by the United Nations.

REFERENCE SIGNS LIST 1 HUD device (head-up display device), 2 vehicle, 3 windshield, 5 display area, 10 control device, 35 image display device, 63 lens, 64 display panel, 100 light source device, DESCRIPTION OF SYMBOLS 120... LED board, 121... LED element, 140... Collimator, 141... Collimator element, 150... Polarization conversion element, 151... Polarization conversion prism, 152... Wave plate, 160... Light guide, 170... Diffusion plate.

Claims

a light source;
a collimator arranged on the emission side of the light source and adjusting the traveling direction of the light incident from the light source;
a light guide disposed on the output side of the collimator and guiding the light incident from the collimator toward the display panel;
a polarization conversion element disposed between the light guide and the display panel on the exit side of the light guide and for aligning polarization characteristics of light incident from the light guide;
A light source device.
The light source device according to claim 1,
a diffusing element disposed between the polarization conversion element and the display panel;
Light source device.
In the light source device according to claim 2,
a light distribution control element disposed before or after the diffusion element between the polarization conversion element and the display panel, the light distribution control element controlling the distribution of light emitted to the display panel;
Light source device.
In the light source device according to claim 3,
The light distribution control element is composed of a thin lens or a Fresnel lens,
Light source device.
The light source device according to claim 1,
A diffusion/light distribution control element disposed between the polarization conversion element and the display panel for diffusing light emitted to the display panel and controlling light distribution,
Light source device.
In the light source device according to claim 3,
The light guide has a plane exit surface,
The light distribution control element has a free-form surface shape for light distribution control to a lens arranged on the output side of the display panel,
Light source device.
In the light source device according to claim 5,
The light guide has a plane exit surface,
The diffusion/light distribution control element has a free-form surface shape for light distribution control to a lens arranged on the output side of the display panel,
Light source device.
In the light source device according to any one of claims 1 to 7,
The polarization conversion element includes a polarization conversion prism and a wavelength plate, and converts the randomly polarized light from the light guide into linearly polarized light through the polarization conversion prism and the wavelength plate. Convert,
Light source device.
In the light source device according to any one of claims 1 to 7,
The light guide has a reflecting portion that reflects light incident from the collimator and traveling in a first direction so as to be emitted as light traveling in a second direction different from the first direction,
The polarization conversion element receives light from the second direction and emits light after polarization conversion in the second direction.
Light source device.
A head-up display device that forms a virtual image by projecting image light onto a display area of a windshield of a vehicle,
a light source device;
a display panel that is arranged on the emission side of the light source device and that modulates the light from the light source device to create an image and emit it as the image light;
an optical system that projects image light from the display panel onto the display area;
with
The light source device
a light source;
a collimator arranged on the emission side of the light source and adjusting the traveling direction of the light incident from the light source;
a light guide disposed on the output side of the collimator and guiding the light incident from the collimator toward the display panel;
a polarization conversion element disposed between the light guide and the display panel on the exit side of the light guide and for aligning polarization characteristics of light incident from the light guide;
comprising
Head-up display device.