WO2018062302A1

WO2018062302A1 - Head-up display device

Info

Publication number: WO2018062302A1
Application number: PCT/JP2017/035016
Authority: WO
Inventors: 昭央三沢; 達也中澤; 星野　茂樹
Original assignee: 日立マクセル株式会社
Priority date: 2016-09-29
Filing date: 2017-09-27
Publication date: 2018-04-05
Also published as: JP2019207263A

Abstract

An objective of the present invention is to suppress, in a head-up display device, an increase in the temperature of an image display element caused by external light. To this end, the head-up display device comprises: an image forming unit including an image display element; a projection optical system for projecting an image beam formed in the image forming unit onto a projection target, and forming a virtual image; a case for accommodating the image forming unit and the projection optical system; and a heat discharging structure for discharging the heat from inside the case to the outside of the case. The projection optical system includes a first optical element having the optical properties of transmitting infrared radiation and reflecting light other than infrared radiation, and the first optical element is disposed in the optical path of the image beam in the case. The heat discharging structure, which is a structure for discharging, from the inside to the outside of the case, heat due to the infrared radiation transmitted through the first optical element, forms a heat transfer path formed by using a medium having a higher thermal conductivity than air.

Description

Head-up display device

The present invention relates to a head-up display device.

As a technology relating to a head-up display device, Patent Document 1 discloses that “a liquid crystal display element 15 includes a liquid crystal cell 16, a first front polarizing member 17 disposed on the front surface of the liquid crystal cell 16, and a rear surface of the liquid crystal cell 16. A rear polarizing member 18 disposed on the liquid crystal display element 15 and having a polarization direction substantially the same as that of the first front polarizing member 17. The structure of “provided (summary excerpt)” is disclosed.

The head-up display device of Patent Document 1 suppresses the change in the viscosity of the liquid crystal cell due to the temperature of the liquid crystal cell of the liquid crystal display element rising due to the heat of sunlight entering the case. The ratio is kept appropriate.

JP 2000-131682 A

In the head-up display device disclosed in Patent Document 1, a reflective polarizing member is disposed in front of a front polarizing plate of a liquid crystal display element. As the reflective polarizing member, one having the same polarization direction as that of the front polarizing plate of the liquid crystal display element is used. Therefore, the sunlight that has passed through the reflective polarizing member passes through the front polarizing plate, is twisted 90 degrees in the liquid crystal cell, and also passes through the rear polarizing plate. That is, in the head-up display device disclosed in Patent Document 1, the reflective polarizing member reflects a part of sunlight toward the liquid crystal display element, and a part of the sunlight transmitted through the reflective polarizing member is liquid crystal. It is configured to pass through the display element. Accordingly, it is intended to prevent the sunlight from reaching the liquid crystal display element and to suppress the temperature rise of the liquid crystal cell due to the temperature of the liquid crystal display element due to the heat of sunlight.

Since the reflective polarizing member is heated by sunlight, it raises the temperature inside the case. Moreover, the temperature in a case will also be raised even if the sunlight reflected by the reflective polarizing member is scattered in the case. As a result, the temperature of the liquid crystal cell is increased.

In recent years, there has been an increasing demand for displaying the display position of a virtual image using a head-up display device at a farther distance and for increasing the display area. In order to display a virtual image in the distance, it is necessary to dispose a lens on the optical path of the image light beam emitted from the liquid crystal display element. Since the sunlight entering the case travels backward in the optical path of the image light flux, the sunlight on the optical path is easily condensed on the liquid crystal display element side by the lens on the optical path.

Also, in order to enlarge the virtual image, it is necessary to enlarge the mirror (concave mirror) that reflects the light emitted from the liquid crystal display element toward the screen. When the concave mirror is enlarged, the amount of sunlight that enters the case and reverses the optical path of the image light flux increases. This also makes it easy to raise the temperature of the liquid crystal display element.

In the configuration using the reflective polarizing member disclosed in Patent Document 1, when a lens and a concave mirror are used for distant display and a large screen, the amount of sunlight entering the case is as described above. Since it increases, the sunlight reflected by the reflective polarizing member also increases. This further increases the temperature of the liquid crystal display element. Therefore, even if the conventional technique is used, there is a further problem in suppressing the temperature rise inside the head-up display device.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a head-up display device that alleviates or suppresses a temperature rise of a liquid crystal display element caused by heat generated by sunlight trapped inside a case. And

In order to solve the above-described problems, the present invention relates to a head-up display device, which includes a video forming unit including a video display element, and a video light beam formed in the video forming unit on a projection target to project a virtual image. A projection optical system, a case housing the image forming unit and the projection optical system, and a heat exhaust structure for exhausting heat inside the case to the outside of the case, the projection optical system The system includes a first optical element having an optical characteristic of transmitting infrared light and reflecting light other than the infrared light, and the first optical element is disposed in an optical path of the image light beam in the case, and The structure is a heat exhaust structure that exhausts heat from the infrared light transmitted through the first optical element from the inside of the case to the outside, and a medium having a higher thermal conductivity than air. Forming a heat transfer path formed by already there, characterized in that.

According to the present invention, it is possible to provide a head-up display device that alleviates or suppresses the temperature rise of the liquid crystal display element caused by the heat generated by sunlight being trapped inside the case. Objects, configurations, and effects other than those described above will be clarified in the following embodiments.

It is a block diagram of a head-up display apparatus. It is an external view of a head-up display device. It is a block diagram which shows the example of the structure of the projection optical system of a head-up display apparatus. It is explanatory drawing which shows a mode that sunlight approachs the inside of a head-up display apparatus. It is sectional drawing which shows the example of the exhaust heat structure of a head-up display apparatus. It is sectional drawing which shows the example of the exhaust heat structure of a head-up display apparatus. It is sectional drawing which shows the example of the exhaust heat structure of a head-up display apparatus. It is sectional drawing which shows another example of the exhaust heat structure of a head-up display apparatus. It is a block diagram which shows another example of the exhaust heat structure of a head-up display apparatus. It is a block diagram which shows another example of the structure of the projection optical system of a head-up display apparatus.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the present invention, and the repetitive description thereof may be omitted.

<Configuration of Head-Up Display Device 10>
First, a head-up display device 10 according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of a head-up display device according to the present embodiment. FIG. 2 is an external view of the head-up display device according to the present embodiment.

As shown in FIG. 1, the head-up display device 10 according to this embodiment includes an image forming unit 110 and a projection optical system 120 inside a case 130. The head-up display device 10 is configured to enlarge and project the image light beam L formed in the image forming unit 110 toward the projection target in the projection optical system 120.

The image forming unit 110 is configured by housing a liquid crystal display element 111 as a display element, a lens 112, and a polarizing member 113 in a lens barrel 114. The projection optical system 120 includes a flat mirror 122 and a concave mirror 121 that are fixed inside the case 130. The image light beam L emitted from the image forming unit 110 is enlarged and projected by the projection optical system 120 toward the windshield 3 (see FIG. 3) as a projection target. 1 and FIG. 3 to be described later, the plane mirror 122 is shown separated from the case inner wall surface 130a for convenience of explanation, but in actuality, as shown in FIGS. 5A to 5D and FIG. Is fixed to the case inner wall surface 130a.

The case 130 includes a heat exhaust structure that exhausts the heat of external light (sunlight SL) that travels backward through the optical path of the image light flux L to the outside of the case 130, as will be described later. As an example of the exhaust heat structure, as shown in FIG. 2, the case main body 135 of the case 130 is configured using a resin material. Further, the portion irradiated with infrared IR contained in the external light in the case 130 is formed by using a heat exhaust plate 136 made of a material having a higher thermal conductivity than air. More preferably, the exhaust heat plate 136 is formed using a material having a higher thermal conductivity than that of the case body 135. In the present embodiment, the case body 135 is formed using a resin, and the heat exhaust plate 136 is formed using a metal material such as iron, aluminum, or copper. The case 130 is configured by insert-molding a heat exhaust plate 136 made of a metal plate into resin, and the metal plate is exposed to the outside of the case 130. As a result, a heat transfer path 200 (see FIG. 5A) configured using a medium having a higher heat transfer property than air from the heat exhaust plate inner surface 136 a to the heat exhaust plate outer surface 136 b can be formed. . In this embodiment, an assembly having a configuration that forms the heat transfer path 200 is referred to as an exhaust heat structure.

As another example, the case main body 135 may be configured using a metal material. Further, the material other than the heat exhaust plate 136 in the case main body 135 is not limited to resin, and a member that can be appropriately selected may be used.

A case opening 132 that communicates the internal space of the case 130 and the outside of the case 130 at a predetermined position on the upper wall surface (the surface on which the exit of the image light flux L is formed), which is a part of the wall surface of the case 130. Is provided. The case opening 132 serves as an exit for the image light beam L. The case opening 132 has a dustproof cover 131 made of a material that can transmit the image light flux L so that dust does not enter the case 130 or the driver 5 accidentally touches the optical element inside the case 130. It is blocked by.

<Usage Mode of Head-Up Display Device 10>
First, a usage mode of the head-up display device 10 will be described with reference to FIG. FIG. 3 is a configuration diagram illustrating an example of the structure of the projection optical system 120 of the head-up display device.

As shown in FIG. 3, the head-up display device 10 is arranged inside a dashboard 4 installed in front of the driver's seat of the vehicle 2. The image light flux L emitted from the head-up display device 10 passes through a dashboard opening 7 provided on the top surface of the dashboard 4 and is enlarged and projected onto the windshield 3 as a projection target.

The image light beam L projected on the windshield 3 is reflected in the direction of the driver 5, and the image light beam L forms an image on the retina of the driver 5. Accordingly, the driver 5 visually recognizes that the virtual image 6 is displayed at a position further forward than the actual position of the windshield 3. That is, the head-up display device 10 projects the virtual image 6 on the windshield 3 using the image light beam L. The virtual image 6 displays information related to the operation status of the vehicle 2, navigation information that informs the route to the destination set by the driver 5, and other information useful for the driver 5 to drive the vehicle 2.

As shown in FIG. 3, in the head-up display device 10, the image light beam L emitted from the image forming unit 110 is converted into two reflecting members provided in the projection optical system 120, specifically, a plane mirror 122 and a concave mirror 121. And is projected on the windshield 3.

<Influence of sunlight SL>
Next, a mechanism for raising the internal environment of the case 130 and the temperature of the liquid crystal display element 111 when sunlight SL enters the head-up display device 10 will be described with reference to FIG. FIG. 4 shows a case where the head-up display device 10 is mounted on the vehicle 2, and the sunlight SL from the sun S travels backward in the projection direction of the image light flux L and enters the head-up display device 10. It is explanatory drawing which shows.

As shown in FIG. 4, sunlight SL passes through the windshield 3, passes through the dashboard opening 7 of the vehicle 2, passes through the dust cover 131 covering the case opening 132, and enters the inside of the case 130. To do. The sunlight SL that has entered the inside of the case 130 is reflected by the concave mirror 121 and travels toward the flat mirror 122. The flat mirror 122 reflects light rays in a wavelength region of the sunlight SL that cannot be cut by the windshield 3 toward the liquid crystal display element 111. That is, infrared IR and visible light contained in sunlight SL are reflected toward the liquid crystal display element 111. In addition, in the windshield 3, the ultraviolet-ray whose wavelength is shorter than visible light is cut. Therefore, the above-mentioned “wavelength region that cannot be cut by the windshield” means a light region having a wavelength longer than that of ultraviolet light, that is, a wavelength region corresponding to visible light or infrared light.

In the head-up display device 10 shown in FIG. 4, since the polarizing member 113 is not disposed, the sunlight SL directly hits the liquid crystal display element 111. As a result, the liquid crystal display element 111 is heated by sunlight SL and adversely affects image quality.

If the polarizing member 113 having a reflection function is disposed in front of the lens 112, it is possible to prevent the sunlight SL from directly hitting the liquid crystal display element 111. However, in this case, the polarizing member 113 is heated by sunlight SL. Since the heat of the polarizing member 113 is transmitted to the liquid crystal display element 111 through the lens barrel 114, the liquid crystal display element 111 is adversely affected by the heat. Further, the heat of the sunlight SL reflected by the polarizing member 113 having a reflection function increases the temperature inside the case 130. Therefore, if the projection optical system 120 does not have a function of exhausting the heat of sunlight SL outside the case 130, the temperature of the liquid crystal display element 111 is likely to rise.

Further, since visible light hits the liquid crystal display element 111 as it is in the sunlight SL reflected by the flat mirror 122, the temperature of the liquid crystal display element 111 may rise due to the influence of the visible light. Accordingly, as will be described below with reference to FIG. 1, the head-up display device 10 according to the present embodiment includes a first optical element having optical characteristics that transmits infrared IR and reflects visible light in the projection optical system 120. Prepare. In addition, the head-up display device 10 according to the present embodiment includes a second optical element having an optical characteristic of polarizing the visible light included in the sunlight SL so as to pass through the liquid crystal display element 111 in the image forming unit 110. .

<Configuration of Image Forming Unit 110>
Returning to FIG. As already described, the image forming unit 110 is configured by housing the liquid crystal display element 111, the lens 112, and the polarizing member 113 in the lens barrel 114. The lens barrel 114 is a cylindrical member made of metal or resin, and the polarizing member 113 is disposed in the vicinity of one opening, and the liquid crystal display element 111 is disposed in the vicinity of the other opening. The lens 112 is disposed between the liquid crystal display element 111 and the polarizing member 113. The image forming unit 110 condenses the image light beam L formed by the liquid crystal display element 111 at the lens 112, passes the light beam L through the polarizing member 113 disposed in front of the lens 112, and emits it.

<Liquid crystal display element 111>
The liquid crystal display element 111 is an image display element including a liquid crystal panel, and has a structure in which a planar liquid crystal layer 111c is sandwiched between a front polarizing member 111a and a rear polarizing member 111b. Therefore, the outer shape of the liquid crystal display element 111 is a flat plate shape, and as shown in FIG. 1, two axes forming a plane parallel to the plane formed by the liquid crystal display element 111 are an X axis and a Y axis. An axis orthogonal to the X axis and the Y axis and parallel to the emission direction of the image light beam L is defined as a Z axis.

<Lens 112>
The lens 112 is an optical element that condenses the image light beam L. As described above, the virtual image 6 is displayed in front of the windshield 3 and far away by the action of the lens 112. That is, by using the lens 112, the virtual image 6 is displayed farther to the driver 5 than when the lens 112 is not used.

<Polarizing member 113>
The polarizing member 113 is a second optical element that polarizes visible light contained in sunlight SL that travels in the reverse direction of the image light beam L in the Y-axis direction. The polarization direction of the polarization member 113 is the same as the polarization direction of the front side polarization member 111 a included in the liquid crystal display element 111. In other words, sunlight that travels backward along the optical path of the image light flux L is reflected by the flat mirror 122, is polarized by the polarizing member 113, and reaches the liquid crystal display element 111.

<Configuration of Projection Optical System 120>
The projection optical system 120 is configured to include a reflecting member configured by combining a plurality of optical elements including a plane mirror 122 and a concave mirror 121 inside the case 130. The reflecting member that transmits IR contained in the sunlight SL is accommodated in contact with the exhaust heat plate inner surface 136a. The projection optical system 120 enlarges and projects the image light flux L emitted from the image forming unit 110 toward the windshield 3.

<Flat mirror 122>
The plane mirror 122 is a plane reflecting plate as a first optical element that reflects the image light beam L emitted from the image forming unit 110 toward the concave mirror 121. The plane mirror 122 is a so-called cold mirror having a function of transmitting the infrared IR contained in the sunlight SL reflected by the concave mirror 121. That is, an optical thin film that transmits infrared IR and reflects visible light is provided on the reflecting surface of the plane mirror 122. The sunlight SL that hits the plane mirror 122 transmits infrared IR having a wavelength longer than that of visible light through the plane mirror 122 toward the case inner wall surface 130a. The transmitted light other than the infrared IR is reflected by the plane mirror 122 and travels toward the image forming unit 110.

The exhaust heat structure formed in the case 130 will be described with reference to FIGS. 5A, 5B, 5C, and 5D. Each of FIG. 5A, FIG. 5B, FIG. 5C, and FIG. 5D is sectional drawing which shows an example of a heat exhaust structure.

In the example of FIG. 5A,

leaf springs

140 and 141 are formed on the exhaust heat plate inner surface 136a. The plate spring 140 includes a fixed end 140a fixed to the heat exhaust plate inner surface 136a, an open end 140b formed on the opposite side of the plate spring 140 from the fixed end 140a, and a space between the fixed end 140a and the fixed end 140a. And a pressing point 140 c that is bent toward the inner surface 136 a of the heat exhaust plate and is in contact with the flat mirror 122. The leaf spring 141 similarly includes a fixed end 141a, an open end 141b, and a pressing point 141c.

The flat mirror 122 is urged by the

leaf springs

140 and 141 toward the inner surface 136a of the heat removal plate and is brought into close contact (contact). Thereby, the heat transfer path 200 from the flat mirror 122 through the exhaust heat plate inner surface 136a to the exhaust heat plate outer surface 136b can be formed using a material having a higher thermal conductivity than air.

The leaf springs 140 and 141 are an example of a member (contact member) that causes the flat mirror 122 to contact the inner surface 136a of the heat removal plate. As another example of the contact member, L-shaped

metal fittings

142 and 143 may be used as shown in FIG. 5B. The flat mirror 122 may be supported between the L-shaped

metal fittings

142 and 143 and the exhaust heat plate inner surface 136a and in contact with the exhaust heat plate inner surface 136a.

As another example of the contact member, the flat mirror 122 may be fastened to the heat exhaust plate 136 with

screws

144 and 145 as shown in FIG. 5C.

It is desirable that the L-shaped

metal fittings

142 and 143 and the

screws

144 and 145 are provided at positions off the optical path of the image light flux L.

As another example of the exhaust heat structure, as shown in FIG. 5D, a flat mirror 122 may be bonded to the exhaust heat plate inner surface 136a via a heat conductive sheet 146. The heat conductive sheet 146 is formed using a material having a higher thermal conductivity than air. Thus, as in the example of FIGS. 5A to 5C using the abutting member, the material having a higher thermal conductivity than air from the flat mirror 122 through the heat exhaust plate inner surface 136a to the heat exhaust plate outer surface 136b. A heat transfer path using is formed.

The infrared IR that has passed through the plane mirror 122 hits the inner surface 136a of the heat exhaust plate and is heated. However, since the metal has a higher thermal conductivity than air, the heat transfer plate 200 is transmitted through the heat transfer path 200 faster than the heat transfer to the liquid crystal display element 111 using air as a medium inside the case main body 135, and the outer surface of the exhaust heat plate. Heat is transferred to 136b. And it is discharged | emitted from the heat sink outer surface 136b to the air layer outside the case main body 135. As a result, most of the heat from the infrared IR is exhausted to the outside of the case 130. Thereby, the temperature rise inside the case 130 due to the sunlight SL entering the inside of the case 130 can be prevented. Further, since the infrared IR contained in the sunlight SL is not reflected by the image forming unit 110, the temperature rise of the liquid crystal display element 111 can be suppressed.

Further, as shown in FIG. 6, heat radiating fins 148 may be formed on the heat exhaust plate outer surface 136b. When the case main body 135 is made of metal, a radiation fin 148 is provided on any part of the outer surface of the case main body 135, preferably on the outer surface opposite to the plane mirror 122 across the wall surface of the case main body 135. Also good. Thereby, the heat dissipation efficiency of the exhaust heat plate 136 can be further improved. As a result, the heat of the plane mirror 122 is easily transferred by the heat exhaust plate 136, and the heat trapped inside the case body 135 can be effectively discharged to the outside.

<Concave mirror 121>
The concave mirror 121 is a free-form surface mirror, and is an optical element that magnifies and projects the image light beam L toward the windshield 3. As a result, the image light beam L is spread and projected onto a predetermined area of the windshield 3, and the virtual image 6 can be displayed in a large size.

<Operation of Flat Mirror 122>
Next, the operation and effect of the plane mirror 122 will be described in more detail. As shown in FIG. 1, sunlight SL is reflected by the concave mirror 121, and this reflected light strikes the plane mirror 122. The plane mirror 122 is a cold mirror. Accordingly, the infrared IR contained in the sunlight SL is transmitted through the plane mirror 122. Since the plane mirror 122 is attached to the metal part inside the case 130, the infrared light transmitted through the plane mirror 122 strikes the metal part of the case 130. The metal portion that is irradiated with infrared IR is heated, but this heat is propagated to the external space of the case 130 and discharged. Thereby, an increase in the internal temperature of the case 130 due to the infrared IR contained in the sunlight SL can be suppressed. Further, it is possible to prevent the infrared IR contained in the sunlight SL from being reflected to the image forming unit 110 side.

In the sunlight SL that has entered the head-up display device 10, only visible light is reflected by the plane mirror 122 toward the image forming unit 110.

<Operation of Polarizing Member 113>
Next, the action and effect of the polarizing member 113 will be described in detail. Visible light of sunlight SL reflected by the plane mirror 122 is polarized in the Y-axis direction and passes through the polarizing member 113. Visible light that has passed through the polarizing member 113 passes through the lens 112 and reaches the liquid crystal display element 111.

The polarization direction of the polarization member 113 and the polarization direction of the front polarization member 111a of the liquid crystal display element 111 are the same. Therefore, the visible light passes through the front polarizing member 111a, is twisted by 90 degrees in the liquid crystal layer 111c, and passes through the rear polarizing member 111b. As a result, visible light of sunlight SL is transmitted through the liquid crystal display element 111 and can be prevented from being heated in the liquid crystal display element 111.

<Operation and effect of this embodiment>
As described above, according to the head-up display device 10 according to the present embodiment, when sunlight SL enters the inside of the case 130, the infrared portion included in the sunlight SL is exposed to the outside via the case 130. Exhaust heat. Further, the visible light contained in the sunlight SL is transmitted through the liquid crystal display element 111 by the polarizing member 113.

As described above, even when sunlight SL enters the inside of the case 130 and becomes backlight with respect to the image light beam L, a structure that can suppress the temperature of the head-up display device 10 from rising due to this backlight is suppressed. I have. Thus, heat that adversely affects the operation of the liquid crystal display element 111 that is a liquid crystal display element can be efficiently eliminated.

The above embodiments are not intended to limit the present invention, and various changes and modifications can be made by those skilled in the art within the scope of the technical idea disclosed in the present specification.

For example, the projection optical system 120 may be configured differently from the above embodiment. Another example will be described with reference to FIG. FIG. 7 is a configuration diagram showing another example of the structure of the projection optical system 120 of the head-up display device 10. In FIG. 7, for convenience of explanation, the reflection mirror 120a is illustrated as being separated from the case inner wall surface 130a. However, the reflection mirror 120a actually contacts the case inner wall surface 130a.

In the optical system in the head-up display device 10 of FIG. 7, the projection optical system 120 is configured by using a single reflection mirror 120a. That is, the concave mirror 121 and the plane mirror 122 described above are configured using a single reflection mirror 120a. On the reflection surface of the reflection mirror 120a, an optical thin film that transmits infrared IR and reflects visible light is provided, and the reflection mirror 120a is formed as a cold mirror. Thereby, the reflection mirror 120a functions as a first optical element. A heat exhaust plate 136 is formed at a portion of the case body 135 that faces the back surface of the reflection mirror 120a, and a heat exhaust structure is formed by bringing the reflection mirror 120a into contact with the inner surface 136a of the heat exhaust plate. The configuration in which the reflecting mirror 120a is brought into contact with the heat exhausting plate 136 may be any of the modes shown in FIGS. 5A to 5D. Further, as shown in FIG. 6, heat radiation fins 148 may be provided on the outer wall surface of the heat exhaust plate 136.

In the example of FIG. 7, the image light beam L emitted from the image forming unit 110 is reflected once by the reflection mirror 120 a and enlarged and projected onto the windshield 3. On the other hand, sunlight SL which permeate | transmitted the windshield 3 permeate | transmits the dust cover 131, and reaches | attains the reflective mirror 120a. The heat from the infrared IR contained in the sunlight SL is transmitted through the reflection mirror 120a and discharged from the heat exhaust plate 136 to the outside of the case body 135.

Furthermore, the case main body 135 of the head-up display device 10 of FIG. 7 may be formed of metal. In this case, the reflection mirror 120a may be brought into contact with any part of the case inner wall surface 135a.

DESCRIPTION OF SYMBOLS 10 Head-up display apparatus 110 Image | video formation unit 111 Display element 113 Polarizing member 120 Projection optical system 121 Concave mirror 122 Plane mirror 130 Case

Claims

An image forming unit including an image display element;
A projection optical system for projecting the image light flux formed in the image forming unit onto a projection target to form a virtual image;
A case housing the image forming unit and the projection optical system;
An exhaust heat structure for exhausting heat inside the case to the outside of the case;
With
The projection optical system includes a first optical element having an optical characteristic of transmitting infrared light and reflecting light other than the infrared light,
The first optical element is disposed in an optical path of the image light beam in the case,
The exhaust heat structure is an exhaust heat structure that exhausts heat from the infrared rays that has passed through the first optical element from the inside of the case to the outside, and is formed using a medium having a higher thermal conductivity than air. Form a heat transfer path,
A head-up display device.
The head-up display device according to claim 1,
The first optical element is a reflecting member,
The reflection member includes an optical thin film that transmits the infrared light and reflects the light on a reflection surface.
A head-up display device.
The head-up display device according to claim 2,
The exhaust heat structure includes a metal plate disposed on a portion of the case that is irradiated with the infrared light that has passed through the first optical element, an inner wall surface of the metal plate forms an inner wall surface of the case, and the metal plate The outer surface of the case forms the outer surface of the case,
The first optical element is disposed in contact with an inner wall surface of the metal plate;
A head-up display device.
The head-up display device according to claim 3,
The main body of the case is formed using a resin, and is formed using the metal plate only on a portion where the infrared ray hits the inner wall surface.
A head-up display device.
The head-up display device according to claim 2,
The body of the case is formed using metal,
The first optical element is disposed in contact with an inner wall surface of the case;
A head-up display device.
The head-up display device according to claim 3,
An abutting member for supporting the first optical element on the inner wall surface of the case by contacting the inner wall surface of the metal plate;
A head-up display device.
The head-up display device according to claim 3,
The first optical element is fixed to the metal plate via a heat conductive sheet having a property of higher thermal conductivity than air.
A head-up display device.
The head-up display device according to claim 3,
Provide heat dissipation fins on the outer surface of the metal plate,
A head-up display device.
The head-up display device according to claim 5,
And further comprising at least one leaf spring for supporting the first optical element on the inner wall surface of the case,
The leaf spring is attached by pressing the first optical element against the inner wall surface of the case.
A head-up display device.
The head-up display device according to claim 5,
The first optical element is fixed to the inner wall surface of the case through a heat conductive sheet having a property of higher thermal conductivity than air.
A head-up display device.
The head-up display device according to claim 5,
Provide heat dissipation fins on the outer surface of the case,
A head-up display device.
The head-up display device according to claim 1,
A second optical element having an optical property of polarizing the light reflected by the first optical element so as to pass through the image forming unit;
A polarizing member that is the second optical element and a reflecting member that is the first optical element are arranged in order from the side closer to the image display element in the optical path of the image light beam,
The head-up display device, wherein the reflection member includes an optical thin film that transmits the infrared light and reflects the light on a reflection surface.
The head-up display device according to claim 12,
The video display element is a liquid crystal display element,
The polarization direction of the light in the polarization member is the same polarization direction as the front side polarization member of the liquid crystal display element.
A head-up display device.
The head-up display device according to claim 12,
The reflecting member is configured by combining a planar reflecting plate and a concave mirror,
The planar reflecting plate has the optical thin film on a reflecting surface,
The concave mirror has a reflecting surface composed of a free-form surface that enlarges and projects the image light beam onto the projection target.
A head-up display device.
The head-up display device according to claim 13,
The image forming unit includes the liquid crystal display element, and a lens that condenses the image light beam emitted from the liquid crystal display element.