JP2018036501A - Virtual image display device - Google Patents

Abstract

There is provided a virtual image display device capable of clearly viewing a virtual image while reducing the influence of external light.
A head-up display includes a light source unit 1 that emits image light of a vertically polarized component polarized in the vertical direction, a screen 2 on which image light from the light source unit 1 is incident to form an intermediate image, and an intermediate A combiner 5 having a reflection surface that reflects image light constituting an image and visually recognizes it as a virtual image, and a polarizing plate 4 that is disposed between the screen 2 and the combiner 5 and selectively transmits a vertical polarization component. The combiner 5 includes a vertical polarization reflection film 52 that selectively reflects image light of a vertical polarization component.
[Selection] Figure 8

Description

  The present invention relates to a technique for visually recognizing a virtual image.

  2. Description of the Related Art Conventionally, a technique for suppressing a reduction in visibility of a virtual image caused by sunlight is known. For example, Patent Document 1 discloses a projector that emits and projects polarized image light, a screen on which an intermediate image is formed by image display light from the projector, a combiner that displays an intermediate image as a virtual image, a projector, and a screen The polarizing plate is disposed so that a part of the light path of sunlight reflected by the polarizing plate does not coincide with the optical path of the light constituting the virtual image. A head-up display is disclosed.

JP 2014-10321 A

  In the head-up display described in Patent Document 1, since the image light emitted from the light source passes through the polarizing plate twice, there is a problem that the luminance of the image to be displayed is reduced due to the reduction in the amount of light generated there.

  Examples of the problem to be solved by the present invention are as described above. The main object of the present invention is to provide a virtual image display device capable of clearly viewing a virtual image while reducing the influence of external light.

  The invention described in claim is a virtual image display device, wherein a light source that emits image light polarized in a first polarization direction, a screen on which image light from the light source is incident to form an intermediate image, and An optical element that selectively reflects a light component in the first polarization direction and reflects the light of the intermediate image as a virtual image by the reflective film; and between the optical element and the screen And a polarization transmitting portion that selectively transmits the light component in the first polarization direction.

It is an example of composition of a head up display concerning the 1st example. It is the figure which showed the optical path of the sunlight which injected from the combiner. (A) Sectional drawing of the polarizing plate which concerns on the modification 1 is shown. (B) The reflectance of the glass according to the incident angle with respect to each of S polarized light and P polarized light is shown. It is an example of composition of a head up display concerning modification 2. It is an example of composition of a head up display concerning modification 3. It is an example of composition of a head up display concerning modification 4. 10 is a configuration example of a head-up display according to Modification 5. It is a structural example of the head-up display which concerns on 2nd Example.

  In one preferred embodiment of the present invention, the virtual image display device includes a light source that emits image light polarized in the first polarization direction, a screen that receives the image light from the light source and forms an intermediate image, and An optical element that selectively reflects the light component in the first polarization direction, reflects the light of the intermediate image by the reflective film and visually recognizes it as a virtual image, and between the optical element and the screen And a polarization transmitting portion that selectively transmits the light component in the first polarization direction.

  The virtual image display device includes a light source, a screen, an optical element, and a polarization transmission unit. The light source emits image light polarized in the first polarization direction. The screen receives the image light from the light source and forms an intermediate image. The optical element has a reflection film that selectively reflects the light component in the first polarization direction, and reflects the light of the intermediate image by the reflection film to make it visible as a virtual image. The polarization transmission unit is disposed between the optical element and the screen, and selectively transmits the light component in the first polarization direction.

  According to this aspect, the virtual image display device reflects the external light of the light component in the first polarization direction by the reflective film, reflects the intermediate image light by the reflective film, and guides it to the observer's eyes. Furthermore, since the light component of the external light that passes through the reflection film and reaches the polarization transmission part and orthogonal to the first polarization direction is reflected by the polarization transmission part, the incidence of external light on the screen is suitably suppressed. The Therefore, according to this aspect, the virtual image display apparatus can guide external light to the outside of the optical system of the virtual image display apparatus and make the observer clearly see the virtual image.

  In one aspect of the virtual image display device, the polarized light transmitting portion is disposed outside an optical path range of the image light incident on the screen. According to this aspect, since the image light emitted from the light source passes through the polarized light transmitting portion only once, it is possible to suitably suppress an unnecessary decrease in the amount of image light due to passing through the polarized light transmitting portion a plurality of times.

  In another aspect of the virtual image display device, the reflection film selectively transmits a light component orthogonal to the first polarization direction, thereby transmitting external light reflected by the polarization transmission unit. According to this aspect, the virtual image display device reflects the light component of the external light in the first polarization direction by the reflection film, and transmits the reflection film through the reflection film and reaches the polarization transmission unit. The light component of the light is also reflected by the polarized light transmitting portion and transmitted through the reflective film. Therefore, the virtual image display device can guide external light to the outside of the optical system of the virtual image display device and make the virtual image clearly visible to the observer.

  In another aspect of the virtual image display device, the light source emits image light polarized in a direction perpendicular to a horizontal direction as image light polarized in the first polarization direction. According to this aspect, even if the observer is wearing polarized sunglasses that cuts the polarization component in the horizontal direction, it is possible for the observer to visually recognize the virtual image suitably.

  In a preferred example of the virtual image display device, the screen is a transmissive screen. In another preferable example of the virtual image display device, the virtual image display device further includes a reflection unit that receives the light of the intermediate image from the screen and reflects the light of the intermediate image toward the polarization transmission unit.

  Hereinafter, preferred first and second embodiments of the present invention will be described with reference to the drawings.

<First embodiment>
[Schematic configuration]
FIG. 1 is a schematic configuration diagram of a head-up display according to the first embodiment. The head-up display is mounted on a vehicle or the like and makes an observer visually recognize a virtual image. The head-up display mainly includes a light source unit 1, a screen 2, a reflection mirror 3, a polarizing plate 4, and a combiner 5. In FIG. 1, “A1” to “A3” indicate light rays corresponding to the optical axis of light emitted from the light source unit 1 (also referred to as “image light”), and “R1” to “R4” indicate image light. It is a boundary line which shows the optical path range to the combiner 5.

  The light source unit 1 has laser elements of red (R), green (G), and blue (B), and screens image light, which is a combined light of a laser modulated based on an image signal, using a MEMS mirror. 2 scans up. In the present embodiment, the light source unit 1 emits light polarized in a direction perpendicular to the horizontal direction (also referred to as “vertical polarization”) as image light. In this case, the image light is incident on the polarizing plate 4 described later as P-polarized light.

  The screen 2 is a transmissive optical member that generates an intermediate image, and functions as an exit pupil expander (EPE) that expands the exit pupil by widening the divergence angle of image light emitted from the light source unit 1. For example, the screen 2 is a microlens array in which a plurality of microlenses are arranged. The image light transmitted through the screen 2 is incident on the reflection mirror 3. The reflection mirror 3 reflects the image light emitted from the screen 2 toward the combiner 5.

  The polarizing plate (polarized light transmitting portion) 4 is provided at a position where the image light reflected by the reflecting mirror 3 is incident, and has a property of selectively transmitting P-polarized light and selectively reflecting S-polarized light. Here, as shown in FIG. 1, the image light is emitted from the light source unit 1 as vertical polarized light, and is incident on the polarizing plate 4 as P-polarized light after being reflected by the reflection mirror 3. Therefore, the polarizing plate 4 transmits the image light reflected by the reflecting mirror 3 to reach the combiner 5. Further, as described later, the inclination of the polarizing plate 4 is adjusted so that the amount of sunlight reflected on the polarizing plate 4 is reflected to the combiner 5. The tilt adjustment of the polarizing plate 4 will be described later.

  The polarizing plate 4 is disposed at a position overlapping the optical path range of the image light sandwiched between the boundary lines R3 and R4, and the optical path range of the image light sandwiched between the boundary lines R1 and R2 (that is, the light source unit 1). To the screen 2 and the optical path range from the screen 2 to the reflecting mirror 3). Thus, the head-up display shown in FIG. 1 has a configuration in which image light passes through the polarizing plate 4 only once.

  The combiner (optical element) 5 projects the light constituting the intermediate image generated by the screen 2 and partially reflects the projected light to the position of the observer's eyes, thereby allowing the observer to visually recognize the virtual image. . Preferably, the image light reflecting surface of the combiner 5 has a substantially concave shape. Thereby, the combiner 5 displays a virtual image in an enlarged manner.

[Inclination of polarizing plate]
Next, the inclination of the polarizing plate 4 will be described. In the first embodiment, the polarizing plate 4 is tilted so as to reflect sunlight incident at least in accordance with the optical axis of the image light toward the outside of the combiner 5. This will be specifically described with reference to FIG. FIG. 2 is a diagram showing an optical path of sunlight incident from the combiner 5. In FIG. 2, “B1” to “B4” indicate sunlight rays that are incident on the polarizing plate 4 from the combiner 5 in alignment with the optical axis of the image light (see arrow A2).

  The sunlight B1 is incident on the combiner 5 in a state including both the light polarized in the horizontal direction (also referred to as “horizontal polarization”) and the vertical polarization, and at least a part of them is transmitted through the combiner 5. Incident on the polarizing plate 4. In this case, the S-polarized light (that is, horizontally polarized light) component of the sunlight B1 incident on the polarizing plate 4 is reflected by the polarizing plate 4 as the solar light B2 and goes outside the combiner 5 without entering the combiner 5. . Thus, the polarizing plate 4 reflects the sunlight B2 in a direction not hitting the combiner 5. In other words, the polarizing plate 4 is tilted in a direction that reflects incident sunlight that coincides with the optical axis of the image light toward the outside of the combiner 5. Thereby, the polarizing plate 4 suppresses that the sunlight reflected by the polarizing plate 4 is reflected by the combiner 5, and the visibility of the virtual image is reduced based on the multiple reflection of the sunlight in the optical system of the head-up display. Can be suitably reduced.

  On the other hand, the vertical polarization component of the sunlight B1 passes through the polarizing plate 4 as the sunlight B3 and enters the reflection mirror 3. Then, the sunlight B3 incident on the reflection mirror 3 is reflected by the reflection mirror 3 and reaches the screen 2 as the sunlight B4. In addition, in the modified example 2 and 2nd Example etc. which are mentioned later, it has the structure which suppresses generation | occurrence | production of such sunlight rays B3 and B4 suitably.

  Here, a supplementary explanation will be given on the effect of converting the image light into vertically polarized light. As shown in FIG. 1, the image light beam A3 that reaches the eyes of the observer is polarized in the vertical direction. Polarized sunglasses generally have a property of cutting a horizontal polarization component (that is, S-polarized light). From the above, in the configuration of the first embodiment, even when the observer is wearing polarized sunglasses, the image light passes through the polarized sunglasses and suitably reaches the eyes of the observer. Therefore, the observer can visually recognize the virtual image suitably even when the polarized sunglasses are worn.

  As described above, the head-up display according to the first embodiment includes the light source unit 1 that emits the image light of the vertically polarized component polarized in the vertical direction, and the image light from the light source unit 1 is incident to the intermediate image. Are disposed between the screen 2 and the combiner 5 and selectively transmit vertically polarized components. The polarizing plate 4 is provided. The polarizing plate 4 is arranged outside the optical path range of the image light incident on the screen 2 and directs the incident external light that coincides with the optical axis of the image light constituting the intermediate image to the outside of the reflecting surface of the combiner 5. Tilted in the direction of reflection. Thereby, the head-up display can reduce the visibility reduction of the virtual image by sunlight suitably while making image light reach | attain suitably for an observer's eyes.

[Modification]
Next, a modification suitable for the first embodiment will be described. These modifications may be applied in any combination to the first embodiment described above.

(Modification 1)
When the polarizing plate 4 is configured by superimposing a polarizing element and a base material, the polarizing plate 4 is preferably tilted so that the transmittance of image light incident as P-polarized light is increased.

  FIG. 3A shows a cross-sectional view of the polarizing plate 4 according to this modification. In the example of FIG. 3A, the polarizing plate 4 has a two-layer structure of a polarizing element 41 that selectively transmits P-polarized light and a glass substrate 42. In such a configuration, even when the P-polarized image light is transmitted through the polarizing element 41, if the glass equipment 42 reflects the P-polarized image light transmitted through the polarizing element 41, the visibility of the virtual image is improved. Will be reduced. In general, the transmittance of the glass substrate 42 with respect to P-polarized light varies depending on the incident angle. Therefore, the polarizing plate 4 is preferably installed so that the image light is incident at an angle at which the transmittance of the glass substrate 42 with respect to the P-polarized light is high.

  FIG. 3B shows the reflectance of the glass according to the incident angle with respect to each of S-polarized light and P-polarized light. As shown in FIG. 3B, the reflectance of the P-polarized light varies depending on the incident angle to the glass, and the reflectance of the P-polarized light is low (that is, the transmittance of the P-polarized light is high) around 40 to 70 degrees. Yes.

  In consideration of the above, in this modification, the polarizing plate 4 has an incident angle at which the transmittance of the P-polarized light is increased in an angular range in which sunlight that matches the optical axis of the image light is reflected outside the combiner 5. The inclination is adjusted so that the angle at which the image light is incident (for example, 40 to 70 degrees). Thereby, while preventing suitably the reflected light from the polarizing plate 4 of sunlight being irradiated to the combiner 5, the reflectance of the image light in the polarizing plate 4 is reduced and sufficient image light is observed by an observer. Can reach the eyes.

(Modification 2)
The head-up display may further have a configuration that cuts the P-polarized component of sunlight transmitted through the polarizing plate 4.

  FIG. 4 is a configuration example of a head-up display according to the second modification. In the example of FIG. 4, a polarizing filter (reflective film) 51 that cuts the P-polarized component (that is, the vertical polarized component) of sunlight is provided on the surface of the combiner 5 on which sunlight enters. In this case, the sunlight B11 that coincides with the optical axis of the image light is divided into a vertically polarized component sunlight B12 that is reflected by the polarization filter 51 and a horizontal polarization component sunlight B13 that is transmitted through the polarization filter 51 and the combiner 5. . Thereafter, the sunlight B13 of the horizontal polarization component is incident on the polarizing plate 4 as S-polarized light and is reflected by the polarizing plate 4 (see the sunlight B14). In this case, the sunlight B14 is emitted in a direction away from the combiner 5.

  Therefore, according to the configuration of FIG. 4, the vertical polarization component of sunlight is cut by the polarizing filter 51, the horizontal polarization component of sunlight is cut by the polarizing plate 4, and the sunlight passes through the polarizing plate 4 and passes through the screen 2. Can be suitably suppressed.

(Modification 3)
The head-up display may further include a light absorber that absorbs sunlight reflected by the polarizing plate 4.

  FIG. 5 is a configuration example of a head-up display according to the third modification. In the example of FIG. 5, the head-up display includes a light absorber (absorber) 6 in a direction in which the polarizing plate 4 reflects sunlight in addition to the polarizing filter 51 described in the second modification. The light absorber 6 is a black member configured to have a low visible light reflectance, and may be, for example, a dashboard. In this case, the sunlight B21 of the horizontal polarization component (that is, the S polarization component) that passes through the polarizing filter 51 and the combiner 5 is incident on the polarizing plate 4 and reflected by the polarizing plate 4 as the sunlight B22. In this case, the sunlight B22 enters the light absorber 6 and is absorbed. Therefore, according to the configuration of FIG. 5, multiple reflections in the optical system of the head-up display due to the reflected light of the polarizing plate 4 can be prevented, and deterioration of the visibility of the virtual image can be suitably suppressed.

  In the example of FIG. 5, the polarizing plate 4 is directed downward, but instead of this, the polarizing plate 4 is directed upward as in the other configuration examples shown in FIGS. 1, 3, 4, and the like. Also good. In this case, for example, the light absorber 6 is provided on the ceiling of the vehicle.

(Modification 4)
The head-up display may not have the reflection mirror 3.

  FIG. 6 is a configuration example of a head-up display according to the fourth modification. In the example of FIG. 6, the light source unit 1, the screen 2, the polarizing plate 4, and the combiner 5 are provided side by side in the same direction, and the light beam A 31 indicating the optical axis of the image light emitted from the light source unit 1 is 2 and the polarizing plate 4, enter the combiner 5, and are reflected by the combiner 5 as light rays A <b> 32 to reach the eyes of the observer. Further, the sunlight B31 incident on the combiner 5 from the direction coincident with the optical axis of the image light is transmitted through the combiner 5, and the horizontal polarization component (that is, the S polarization component) is deviated from the combiner 5 as the sunlight B32. Reflected and vertically polarized components are transmitted through the polarizing plate 4 as sunlight rays B33.

  As described above, in the configuration of FIG. 6 as well, similarly to the embodiment, it is possible to suitably reduce the reduction in the visibility of the virtual image due to the sunlight while appropriately allowing the image light to reach the eyes of the observer.

(Modification 5)
The screen 2 is a transmissive screen, but may be a reflective screen instead.

  FIG. 7 is a configuration example of a head-up display according to the fifth modification. In the example of FIG. 7, the head-up display has a reflective screen 2A. The screen 2A is a reflective optical member that generates an intermediate image, and functions as an exit pupil magnifier (EPE). In the screen 2A, for example, a microlens array in which a plurality of microlenses are arranged is formed on a surface on which image light from the light source unit 1 is incident, and a reflective surface is formed on a surface opposite to the microlens array. Is done. In this configuration, the image light emitted from the light source unit 1 is reflected toward the combiner 5 by the screen 2A. And the polarizing plate 4 is provided between the screen 2A and the combiner 5, and inclination is adjusted similarly to an Example.

  Even with this configuration, similarly to the configuration of the first embodiment, the reflectance of the image light at the polarizing plate 4 can be reduced while suitably preventing the reflected light from the polarizing plate 4 from being irradiated to the combiner 5. The image light with a sufficient amount of light can be reduced and reach the eyes of the observer.

(Modification 6)
The head-up display may cause a part of the windshield of the vehicle to function as an optical element that reflects a part of the image light and reaches the eyes of the observer, like the combiner 5. In this case, the irradiation area of the windshield irradiated with the image light is an example of the “reflection surface” in the present invention.

<Second embodiment>
FIG. 8 is a configuration example of a head-up display according to the second embodiment. The head-up display shown in FIG. 8 is different from the head-up display according to the first embodiment in that a vertical polarization reflection film 52 is provided on the surface of the combiner 5 that reflects image light.

  The vertical polarization reflection film 52 is a reflection film configured to reflect P-polarized light and transmit S-polarized light. In the example of FIG. 8, the vertically polarized component of sunlight incident as P-polarized light is reflected and the horizontally polarized component sunlight that is reflected light from the polarizing plate 4 is transmitted. Further, the vertical polarization reflection film 52 reflects the image light transmitted through the polarizing plate 4 to reach the observer's eyes.

  In the second embodiment, the polarizing plate 4 is different from the first embodiment in that the inclination is not adjusted in consideration of the sunlight reflection direction. In the example of FIG. It arrange | positions so that the sunlight which overlaps with the optical axis may be reflected toward the combiner 5. In this case, preferably, as described in the first modification of the first embodiment, the polarizing plate 4 is configured such that the incident angle of the image light is an angle at which the transmittance of the polarizing plate 4 with respect to the P-polarized light is increased. In addition, the tilt may be adjusted.

  Here, the optical path of the image light in the example of FIG. 8 will be described. First, a light beam A51 indicating the optical axis of the image light emitted from the light source unit 1 is transmitted through the screen 2, enters the reflection mirror 3, and is reflected as a light beam A52. Since the light beam A52 is incident on the polarizing plate 4 as P-polarized light, the light beam A52 is transmitted through the polarizing plate 4 and is incident on the vertical polarization reflection film 52. In this case, since the light beam A52 that has passed through the polarizing plate 4 and entered the vertical polarization reflection film 52 is vertical polarization, it is reflected as the light beam A53 by the vertical polarization reflection film 52 and reaches the eyes of the observer.

  Next, an optical path of sunlight that coincides with the optical axis of the image light will be described. The sunlight B51 that coincides with the optical axis of the image light passes through the combiner 5, and then is reflected by the vertically polarized reflection film 52 as the sunlight B52 with respect to the vertically polarized component, and vertically polarized as the sunlight B53 with respect to the horizontally polarized component. It penetrates the membrane 52. The sunlight B53 of the horizontal polarization component that has passed through the vertical polarization reflection film 52 enters the polarizing plate 4 and is reflected by the polarizing plate 4 as the sunlight B54. Here, since the sunlight B54 is incident on the vertical polarization reflection film 52 as S-polarized light, it passes through the vertical polarization reflection film 52. In this way, in the second embodiment, sunlight is reflected by either the vertical polarization reflection film 52 or the polarizing plate 4 and guided outside the optical system of the head-up display. Deterioration can be suitably suppressed.

  As described above, the head-up display according to the second embodiment includes the light source unit 1 that emits the image light of the vertically polarized component polarized in the vertical direction, and the image light from the light source unit 1 is incident to the intermediate image. Are disposed between the screen 2 and the combiner 5 and selectively transmit vertically polarized components. The polarizing plate 4 is provided. The combiner 5 includes a vertical polarization reflection film 52 that selectively reflects image light of a vertical polarization component. Thereby, the head-up display can reduce the visibility reduction of the virtual image by sunlight suitably while making image light reach | attain suitably for an observer's eyes.

  Each (Modification 1) to (Modification 6) of the first embodiment can be applied to the second embodiment in the same manner as the first embodiment.

DESCRIPTION OF SYMBOLS 1 Light source part 2, 2A Screen 3 Reflection mirror 4 Polarizing plate 5 Combiner 6 Light absorber

Claims (6)

A light source that emits image light polarized in a first polarization direction;
A screen on which image light from the light source is incident to form an intermediate image;
An optical element having a reflective film that selectively reflects the light component in the first polarization direction, and reflecting the light of the intermediate image by the reflective film and visually recognizing it as a virtual image;
A polarized light transmitting part that is disposed between the optical element and the screen and selectively transmits the light component in the first polarization direction;
A virtual image display device comprising:   The virtual image display device according to claim 1, wherein the polarized light transmitting unit is disposed outside an optical path range of the image light incident on the screen.   The said reflective film permeate | transmits the external light reflected in the said polarized light transmission part by selectively permeate | transmitting the light component orthogonal to the said 1st polarization direction, The Claim 1 or 2 characterized by the above-mentioned. Virtual image display device.   The light source emits image light polarized in a direction perpendicular to a horizontal direction as image light polarized in the first polarization direction. The virtual image display device described.   The virtual image display device according to claim 1, wherein the screen is a transmissive screen.   The light of the said intermediate image injects from the said screen, It further has a reflection part which reflects the light of the said intermediate image toward the said polarized light transmission part, The Claim 1 characterized by the above-mentioned. Virtual image display device.