JP7042586B2 - Head-up display device - Google Patents

Description

The present invention relates to a head-up display device, and particularly to measures against stray light.

In a vehicle such as an automobile, information such as vehicle speed and engine speed is usually displayed on the instrument panel in the dashboard. In addition, screens such as car navigation are displayed on a display built into the dashboard or installed on the dashboard. Since it is necessary for the driver to move the line of sight significantly when visually recognizing this information, as a technology for reducing the amount of movement of the line of sight, information such as vehicle speed and information such as instructions related to car navigation are windshielded. A head-up display (Head Up Display, hereinafter referred to as "HUD") that projects and displays on a (windshield) or the like is known.

As a technique related to HUD, for example, in Patent Document 1, a refracting lens included in HUD is arranged at an angle with respect to a reference ray to suppress the return of external light reflection, and a polarizing plate is arranged in front of the lens. A configuration is disclosed in which the brightness of the return light is reduced by doing so.

International Publication No. 2017/09424

In Patent Document 1, a part of the light incident on the refracting lens hits the side surface from the inside of the refracting lens and is reflected, so that the side surface of the lens shines. Therefore, when the driver sees a virtual image, the reflected light generated on this side surface becomes stray light, and there is a problem that the driver visually recognizes an unintended virtual image caused by the stray light.

As a countermeasure, it is conceivable to apply a low-reflecting material to the side surface of the refracting lens or cover the side surface of the refracting lens with a light absorbing material. Applying a reflective material is time-consuming. Further, when the light absorbing material is attached to the side surface of the refracting lens, a new problem that reflection by the adhesive occurs may occur. Therefore, there is room for further ingenuity in measures against stray light of the lens included in the HUD.

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 suppresses deterioration of image quality due to stray light while simplifying lens processing work.

In order to solve the above problems, the present invention has the configuration described in the claims. One example is a head-up display device that displays a virtual image to the driver of a vehicle, and is a display element that transmits a light source and light from the light source and emits image light to be displayed as a virtual image. The projection optical system includes a projection optical system that magnifies and projects the image light, and the projection optical system includes a lens and a free curved mirror arranged along the emission direction of the image light in order from a position closest to the display element. The lens is a resin molded product made of a transmissive resin, and has a lens incident surface on which the image light is incident on the lens, a lens exit surface on which the image light is emitted from the lens, and the lens. The surface is processed so that the surface roughness of the lens peripheral surface is the same as the surface roughness of the lens incident surface, including the incident surface and the lens peripheral surface that connects the lens emitting surface , or the image light is emitted. The peripheral surface of the lens is surface-processed so as to have a surface roughness that diverges in the lens, hits the peripheral surface of the lens, and suppresses reflection toward the inside of the lens, and the peripheral surface of the lens is subjected to injection molding. A gate mark indicating the position where the resin is injected is formed, and the surface roughness of the gate mark is polished so as to be the same as the surface roughness of the incident surface of the lens, or the image light is diverged in the lens. It is characterized in that it hits the peripheral surface of the lens and is polished so as to have a surface roughness that suppresses reflection toward the inside of the lens .

According to the present invention, it is possible to provide a head-up display device that suppresses deterioration of image quality due to stray light while simplifying lens processing work. The purposes, configurations, and effects other than those described above will be clarified in the following embodiments.

Schematic configuration of the HUD A perspective view showing an example of the appearance centering on the exterior housing of the HUD. A perspective view showing a state in which the HUD shown in FIG. 2A is disassembled into parts. Perspective view showing the state in which the image forming unit is disassembled into each part. External view of the lens The figure which shows the gate mark formed on the side surface of a lens The figure which shows the glass cutting finish surface which constitutes the side surface of a lens The figure which shows the optical path of the image light L The figure which shows the virtual image display example with the case where the surface is not processed on the peripheral surface of a lens. Schematic block diagram of the HUD according to another example

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in all the drawings for explaining the embodiment, the same members are designated by the same reference numerals in principle, and the repeated description thereof will be omitted. In each of the following embodiments, the case where the head-up display device (HUD) is installed in a vehicle such as an automobile will be described as an example, but the present invention can also be applied to other vehicles such as trains and aircraft. It can also be applied to HUDs used for applications other than vehicles.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings and the like. In all the drawings for explaining the present invention, those having the same function may be designated by the same reference numerals, and the repeated description thereof may be omitted.

In each of the following embodiments, the case where the head-up display device (HUD) is installed in a vehicle such as an automobile will be described as an example, but the present invention can also be applied to other vehicles such as trains and aircraft. It can also be applied to HUDs used for applications other than vehicles.

The configuration of HUD1 according to the present embodiment will be described with reference to FIGS. 1, 2A, 2B, and 3. FIG. 1 is a schematic configuration diagram of HUD1 according to the present embodiment. FIG. 2A is a perspective view showing an example of the appearance centering on the exterior housing 50 of the HUD1. Further, FIG. 2B is a perspective view showing a state in which HUD1 shown in FIG. 2A is disassembled into individual parts. FIG. 3 is a perspective view showing a state in which the image forming unit is disassembled into each component.

As shown in FIG. 1, the HUD 1 is provided in the dashboard 4 provided in the vehicle 2. The dashboard 4 includes a dashboard opening 7 for passing the image light L emitted from the HUD 1. The image light L is reflected by the windshield 3 of the vehicle 2 and is incident on the eyes of the driver 5. The driver 5 visually recognizes the virtual image 80 by the image light L further in front of the windshield 3. The projected member is not limited to the windshield 3, and any member such as a combiner can be used as long as it is a member on which image light is projected.

The HUD 1 includes an exterior housing 50, an LCD (Liquid Crystal Display) 30 as an image forming unit mounted on the exterior housing 50 (see FIG. 2A), and projection optics for magnifying and projecting image light L emitted from the LCD 30. It is configured to include the system 40. The exterior housing 50 accommodates each element constituting the projection optical system 40.

On the upper surface of the exterior housing 50, a housing opening 51a (see FIG. 2B) that serves as an outlet for the image light L is formed. The housing opening 51a is covered with an antiglare plate (glare trap) 52 for preventing dust and dirt from entering the exterior housing 50. The antiglare plate 52 is composed of a member that transmits visible light.

In the projection optical system 40, the lens 43 and the free-form surface mirror 41 are arranged in order from the position closest to the LCD 30 along the emission direction of the image light L.

The free curved surface mirror 41 is a member that reflects the image light L transmitted through the lens 43 toward the housing opening 51a. The free curved mirror 41 is rotated by the mirror drive unit 42. The mirror drive unit 42 adjusts the angle of the free curved mirror 41 so that the image light L reflected by the free curved mirror 41 passes through the antiglare plate 52 and reaches the windshield 3.

As shown in FIG. 2B, the HUD 1 has a configuration in which the optical component holding member 53 is housed in the exterior case 54, and the upper portion is further covered by the exterior lid portion 51. Each member of the exterior case 54 and the exterior lid portion 51 constitutes the exterior housing 50. Then, the LCD 30 is attached to the side opening 54a of the outer case 54.

The optical component holding member 53 is a member that holds the free curved surface mirror 41 and the lens 43.

A main board 70 on which a control device for controlling the operation of the LCD 30 and the operation of the mirror drive unit 42 including a motor for changing the tilt angle of the free-form surface mirror 41 is mounted is attached to the outer case 54. May be good. In the present embodiment, a attachment / detachment mechanism such as a screw hole and a side opening 54a for incident image light L are further formed so that the LCD 30 can be attached / detached.

As shown in FIG. 3, the liquid crystal display panel 33 displays an image by modulating the light from the backlight 31 based on the image signal input from the main board 70 via the flexible cable 34. The displayed image is output to the projection optical system 40 through the side opening 54a of the exterior case 54 in FIG. 2, and a virtual image 80 visible to the driver 5 is generated.

The backlight 31 mainly includes an LED (Light Emitting Diode) light source 31a, a light funnel 32a, a light guide body 32b, and a diffuser plate 32c.

The luminous efficiency with respect to the input power of the LED varies depending on the emission color, but is about 20 to 30%, and most of the rest is converted into heat. Therefore, the frame 35 to which the LED light source 31a is attached is provided with fins (heat sink 31b) for heat dissipation made of a member having high thermal conductivity (for example, a metal member such as aluminum) to dissipate heat to the outside.

In the example of FIG. 3, a light guide body 32b and a diffuser plate 32c are used in order to efficiently guide the divergent light from the LED light source 31a to the liquid crystal display panel 33. In this case, in order to prevent the adhesion of dust and the like, for example, the light guide body 32b, the diffusion plate 32c, the liquid crystal display panel 33, and the like are entirely covered with the first exterior member 36a and the second exterior member 36b, and modularized as the LCD 30. do.

Further, in the example of FIG. 3, in order to take in the divergent light from the LED light source 31a and make it parallel light, a plurality of light funnels 32a made of a collimating lens or the like are provided. In each light funnel 32a, the opening that takes in the divergent light from the LED light source 31a is, for example, a flat surface and an optical connection by inserting a medium between the light funnel 32a and the LED light source 31a, or condensing as a convex shape. Have an effect. As a result, the divergent light is made parallel light as much as possible, and the incident angle of the light incident on the interface of the light funnel 32a is reduced. As a result, since the divergence angle becomes smaller after passing through the light funnel 32a, it becomes easy to control the light source light directed to the liquid crystal display panel 33 after being reflected by the light guide body 32b.

The surface (hereinafter referred to as “element emission surface”) 33a on which the image light L is emitted in the liquid crystal display panel 33 is an element of the element emission surface 33, which is a region through which the image light L including the image information of the intended virtual image 80 is transmitted. The effective region 33a1 is provided.

The lens 43 is arranged so as to face the element ejection surface 33a. The lens 43 may be a resin molded product obtained by injection molding a transparent resin, or may be a glass cut product formed by cutting glass.

The surface roughness of the lens 43 made of a resin molded product will be described with reference to FIGS. 4, 5A and 5B. FIG. 4 is an external view of the lens 43. FIG. 5A is a diagram showing a gate mark 44 formed on the side surface of the lens 43. FIG. 5B is a diagram showing a glass cutting finished surface 45 constituting the side surface of the lens 43.

As shown in FIG. 4, the lens 43 faces the liquid crystal display panel 33, and the lens incident surface 43a on which the image light L is incident on the lens 43, the lens emitting surface 43b on which the image light L is emitted from the lens 43, and the lens 43. It includes a first side surface 43c, a second side surface 43d continuous with the first side surface 43c, a third side surface 43e continuous with the second side surface 43d, and a fourth side surface 43f continuous with the third side surface 43e and the first side surface 43c.

Of the surfaces exposed to the outside of the lens 43, the first side surface 43c, the second side surface 43d, the third side surface 43e, and the fourth side surface 43f are collectively referred to as the lens peripheral surface.

As shown in FIG. 5A, in the lens 43 made of an injection molded product, a gate mark 44 indicating a resin injection position is formed on any side surface of the lens 43, for example, the first side surface 43c. The surface roughness of the gate mark 44 is coarser than other parts on the peripheral surface of the lens, the incident surface of the lens 43a, and the exit surface of the lens 43b.

The image light L emitted from the liquid crystal display panel 33 is not completely parallel light, but has a divergence angle with respect to the optical axis of the image light L. Therefore, the image light L incident from the lens incident surface 43a spreads toward each side surface inside the lens 43 and reaches each side surface. A part of the image light L reaching each side surface is transmitted, and a part of the image light L is reflected. The larger the surface roughness of the side surface, the higher the reflectance of the image light L. Therefore, in the gate mark 44 of the first side surface 43c, more reflected light is generated as compared with other parts, and the reflected light becomes stray light and is emitted from the lens 43 together with the image light L to reach the windshield 3. It is incident on the eyes of the driver 5. As a result, the driver 5 visually recognizes the unintended virtual images 202 and 212 (see FIG. 7) caused by the stray light.

Therefore, in the lens 43 of the present embodiment, surface processing, for example, polishing processing is performed to smooth the gate mark 44.

Since the gate mark 44 is one of the causes of generating stray light, it is desirable that the gate mark 44 is not on the optical path of the image light L emitted toward the free curved mirror 41. Therefore, it is desirable to evacuate the image light L from the optical path and provide the gate mark 44 on the peripheral surface of the lens as in the present embodiment. Hereinafter, an example in which the gate mark 44 is located on the first side surface 43c will be described.

The first side surface 43c is polished so that the surface roughness of the gate mark 44 is the same as or within an allowable range that can be regarded as the same as the lens incident surface 43a.

There are various parameters representing surface roughness such as "arithmetic mean roughness" (Ra), "maximum height" (Rz), "average length of elements" (Rms), "reflection surface accuracy" (PV value), etc. , Any of them may be used as a parameter representing the surface roughness in the present embodiment, or a plurality of parameters may be combined to evaluate the surface roughness.

For example, when "arithmetic mean roughness" (Ra) is used, the surface roughness Ra1 of the portion where the gate mark 44 after the surface processing is present is an allowable range which can be regarded as the same as the surface roughness Ra0 of the lens incident surface 43a. It is included in the range multiplied by the margin rate α indicating.

Further, among the outer peripheral surfaces of the lens 43, the outer peripheral surfaces other than the gate mark 44 are also surface-treated so that the surface roughness thereof is equal to the surface roughness of the lens incident surface 43a.

As a result, the surface roughness of the peripheral surface of the lens becomes the same as or within the allowable range that can be regarded as the same as the surface roughness of the incident surface 43a of the lens, and the image light L is diverged inside the lens 43 to the peripheral surface of the lens. When it hits a surface, the reflectance is lower than that before surface processing. As a result, most of the image light L is transmitted, the reflected light to the inside of the lens 43 can be reduced, and stray light is less likely to occur.

As another example of the lens 43, when the lens 43 is formed as a glass-cut product, as shown in FIG. 5B, the glass-cut finished surface 45 has streaks during cutting. Similar to the gate mark 44, this streak causes the image light L that hits the peripheral surface of the lens to be reflected from the inside of the lens 43. Therefore, the glass-cut finished surface 45 is polished to smooth the surface so that the surface roughness of the glass-cut finished surface 45 is the same as or within an allowable range that can be regarded as the same as the lens incident surface 43a.

The optical path of the image light L will be described with reference to FIG. FIG. 6 is a diagram showing an optical path of the image light L.

A blanket 57 is attached to the surface of the optical component holding member 53 facing the lens 43 as a measure against stray light. A low-reflection coating may be applied instead of the blanket 57.

Of the lens incident surface 43a of the lens 43, the projection surface when the lens effective region 43a1 on which the image light L is incident is projected onto the liquid crystal display panel 33 along the optical axis direction of the image light L is included in the element effective region 33a1. .. By being included here, it means that the size of the projection surface is the same as or smaller than the element effective region 33a1, and the projection surface does not extend beyond the element effective region 33a1. The liquid crystal display panel 33 and the lens 43 are installed in a positional relationship in which the projection surface and the element effective region 33a1 substantially overlap.

The above allowable range is such that even if the outer edge of the light flux of the image light L diverges inside the lens 43, the lens effective region 43a1 and the element effective region 33a1 are within the range where the light beam is emitted from the lens emission surface 43b instead of the lens peripheral surface. It means that the error of the lens is settled.

The image light L emitted from the element effective region 33a1 is incident on the lens effective region 43a1. The image light L is emitted from the lens exit surface 43b while being emitted inside the lens 43. In the example of FIG. 6, even if the image light L diverges in the lens 43, it does not diverge to the extent that it hits the peripheral surface of the lens, so that the image light L hardly leaks from the peripheral surface of the lens.

However, even if the image light L reaches the peripheral surface of the lens, the surface roughness of the peripheral surface of the lens is the same as that of the incident surface of the lens 43a, so that the reflectance is the incident surface of the lens. It is suppressed to the same level as 43a. Therefore, almost no stray light is generated inside the lens 43.

The action and effect of the HUD according to the present embodiment will be described with reference to FIG. 7. FIG. 7 is a diagram showing an example of displaying a virtual image in the case where the surface of the peripheral surface of the lens is not processed. The left figure of FIG. 7 shows an example in which the desired virtual images 2011 and 211 and the virtual images 202 and 212 due to stray light appear under the desired virtual images 2011 and 11 when the surface processing on the peripheral surface of the lens is not performed. In the left figure of FIG. 7, the image display example 200 shows an actual display example when the surface is not processed, and the image display example 210 schematically shows the screen display example 200.

In the image display example 200, the virtual image 202 due to stray light appears in the virtual image 201 and its vicinity (lower in the figure). Schematically shown, a virtual image 212 due to stray light appears in the virtual image 211 and its vicinity (lower in the figure).

On the other hand, when the peripheral surface of the lens 43 is surface-treated as in the present embodiment, an example in which only virtual images 221,231 appear as shown in the right figure of FIG. 7 is shown. In the right figure of FIG. 7, the image display example 220 shows an actual display example when the surface is processed, and the image display example 230 schematically shows the screen display example 220.

As described above, according to the present embodiment, the image light L is the lens by processing the surface so that the surface roughness of the peripheral surface of the lens is the same as or the same as the surface roughness of the incident surface 43a of the lens. It is possible to suppress the reflection inside the lens by diverging inside and hitting the peripheral surface of the lens. As a result, it is possible to suppress the appearance of a virtual image due to stray light and improve the image quality of the virtual image.

Further, if a fleece cloth is attached to the peripheral surface of the lens in order to suppress the reflection on the peripheral surface of the lens, there is a concern that the adhesive may generate reflected light. There is no concern.

Further, since careful work is required to apply the low reflective material to the peripheral surface of the lens while avoiding contamination of the incident surface 43a of the lens and the exit surface 43b of the lens, the lens processing work takes time and effort, and mass productivity cannot be expected. On the other hand, in the present embodiment, a widely used surface processing technique such as polishing for smoothing the surface of the peripheral surface of the lens can be applied, so mass productivity can be expected.

Further, in the present embodiment, the element effective region 33a1 of the liquid crystal display panel 33 and the lens effective region 43a1 on the lens incident surface 43a face each other, and the projection surface of the lens effective region 43a1 on the liquid crystal display panel 33 is the element effective region 33a1. By arranging the light so as not to protrude from the lens 43, it is possible to prevent the image light L emitted from the liquid crystal display panel 33 from being incident on the lens 43 from the external region of the lens effective region 43a1. As a result, it is possible to further suppress the occurrence of stray light when the image light L incident from the effective lens region 43a1 hits the peripheral surface of the lens.

The above-described embodiment is not limited to the present invention, and various modifications within the scope of the present invention are included in the present invention.

FIG. 8 is a schematic configuration diagram of HUD1a according to another example. As shown in FIG. 8, in addition to the configuration of HUD1 shown in FIG. 1, the HUD1a may include a folded mirror 49 made of a flat mirror between the lens 43 and the free curved mirror 41. Further, the HUD1a is different from the HUD1 in FIG. 1 in that the liquid crystal display panel 33 and the lens 43 are housed in the lens barrel 48, and the backlight 31 is provided on the back surface (the side opposite to the lens 43) of the liquid crystal display panel 33.

According to HUD1a, the image light L emitted from the lens 43 is once incident on the folded mirror 49, reflected here, and incident on the free curved mirror 41. As a result, the optical path length of the image light L can be lengthened in the HUD1a of FIG. 8 as compared with the HUD1 of FIG. 1 in which the image light L emitted from the lens 43 is directly incident on the free curved surface mirror 41. As a result, the virtual image 80 can be displayed farther from the driver 5.

1, 1a ... HUD, 2 ... Vehicle, 3 ... Windshield, 4 ... Dashboard, 5 ... Driver, 30 ... LCD, 31 ... Backlight, 31a ... LED light source, 31b ... Heat sink, 32a ... Light funnel, 32b ... Light guide body, 32c ... Diffusing plate, 33 ... Display element, 331 ... First polarizing plate, 332 ... Second polarizing plate, 333 ... Liquid crystal layer, 34 ... Flexible cable, 35 ... Frame, 36a ... First exterior member, 36b ... Second exterior member, 41 ... Free curved mirror, 42 ... Mirror drive unit, 43 ... Lens, 49 ... Folded mirror, 50 ... Exterior housing, 51 ... Exterior lid, 52 ... Anti-glare plate, 53 ... Optical component holding Member, 54 ... Exterior case, 70 ... Main board, 80 ... Virtual image

Claims (5)

A head-up display device that displays a virtual image to the driver of a vehicle.
Light source and
A display element that transmits light from the light source and emits image light to be displayed as a virtual image.
Includes a projection optical system that magnifies and projects the image light.
The projection optical system includes a lens and a free-form surface mirror arranged along the emission direction of the image light in order from a position closest to the display element.
The lens is a resin molded product made of a transmissive resin, and has a lens incident surface on which the image light is incident on the lens, a lens emitting surface on which the image light is emitted from the lens, a lens incident surface, and the lens incident surface. Including a lens peripheral surface that makes the lens emission surface continuous,
The surface roughness of the peripheral surface of the lens is surface-processed so as to be the same as the surface roughness of the incident surface of the lens, or the image light is diverged in the lens and hits the peripheral surface of the lens to enter the inside of the lens. The peripheral surface of the lens is surface-processed so as to have a surface roughness that suppresses reflection toward the lens.
A gate mark indicating the position where the resin was injected at the time of injection molding is formed on the peripheral surface of the lens, and the surface roughness of the gate mark is polished so as to be the same as the surface roughness of the incident surface of the lens.
Alternatively, the image light is diverged in the lens, hits the peripheral surface of the lens, and is polished so as to have a surface roughness that suppresses reflection toward the inside of the lens.
A head-up display device characterized by that. A head-up display device that displays a virtual image to the driver of a vehicle.
Light source and
A display element that transmits light from the light source and emits image light to be displayed as a virtual image.
Includes a projection optical system that magnifies and projects the image light.
The projection optical system includes a lens and a free-form surface mirror arranged along the emission direction of the image light in order from a position closest to the display element.
The lens is a cut glass product, and the lens incident surface on which the image light is incident on the lens, the lens emitting surface on which the image light is emitted from the lens, the lens incident surface, and the lens emitting surface are continuous. Including the lens peripheral surface,
The surface roughness of the peripheral surface of the lens is surface-processed so as to be the same as the surface roughness of the incident surface of the lens, or the image light is diverged in the lens and hits the peripheral surface of the lens to enter the inside of the lens. The peripheral surface of the lens is surface-processed so as to have a surface roughness that suppresses reflection toward the lens.
The peripheral surface of the lens includes a glass-cut finished surface obtained by cutting glass, and the surface roughness of the glass-cut finished surface is polished so as to be the same as the surface roughness of the lens incident surface, or the image light is emitted. It is polished so as to have a surface roughness that diverges in the lens, hits the peripheral surface of the lens, and suppresses reflection toward the inside of the lens.
A head-up display device characterized by that. The head-up display device according to claim 2.
An optical component holding member that holds the lens and the free-form surface mirror is included, and a blanket is attached to or painted with a low-reflection paint on the surface of the optical component holding member that faces the lens .
A head-up display device characterized by that. The head-up display device according to claim 1 or 2.
The display element is a liquid crystal display panel including an element emission surface that emits the image light.
The lens incident surface faces the liquid crystal display panel,
The projection surface formed when the lens incident surface is projected onto the liquid crystal display panel along the optical axis of the image light is included in the element effective region that emits the image light on the element emission surface.
The size of the projection surface is the same as the effective area of the element, or smaller than the effective area of the element.
A head-up display device characterized by that. The head-up display device according to claim 1 or 2.
The projection optical system further includes a folded mirror between the lens and the free curved mirror, which reflects the image light emitted from the lens emitting surface toward the free curved mirror.
A head-up display device characterized by that.

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