JP6822014B2 - Virtual image display device - Google Patents

Description

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

Conventionally, a technique for suppressing a decrease in visibility of a virtual image caused by sunlight has been known. For example, Patent Document 1 describes a projector that emits and projects polarized image light, a screen that forms an intermediate image by image display light from the projector, a combiner that displays the intermediate image as a virtual image, and a projector and a screen. A polarizing plate is provided in the light path between the and, and the polarizing plate is arranged so that a part of the light path of sunlight reflected by the polarizing plate does not match the light path of the light constituting the virtual image. The head-up display is disclosed.

Japanese Unexamined Patent Publication No. 2014-10321

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 brightness of the displayed image is lowered due to the reduction in the amount of light generated there.

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

The invention according to the claim is an imaginary image display device mounted on a vehicle, in which a light source that emits image light polarized in the first polarization direction and image light from the light source are incident to form an intermediate image. An optical element having a screen that selectively reflects the light component in the first polarization direction, and reflecting the light of the intermediate image by the reflecting film to make it visually recognized as a virtual image, the optical element and the above. It is provided with a polarization transmitting portion that is arranged between the screen and selectively transmits the light component in the first polarization direction, and the external light incident on the optical axis of the intermediate image is transmitted by the polarization. It is characterized in that it is reflected by a portion and incident on the ceiling of the vehicle .

This is a configuration example of the head-up display according to the first embodiment. It is a figure which showed the optical path of the sunlight incident from a combiner. (A) The cross-sectional view of the polarizing plate which concerns on 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. This is a configuration example of the head-up display according to the second modification. This is a configuration example of the head-up display according to the third modification. This is a configuration example of the head-up display according to the modified example 4. This is a configuration example of the head-up display according to the modified example 5. This is a configuration example of the head-up display according to the second embodiment.

In one preferred embodiment of the present invention, the virtual image display device comprises a light source that emits image light polarized in the first polarization direction, a screen on which image light from the light source is incident to form an intermediate image, and the like. It is provided with a polarization transmitting portion which is arranged between the screen and an optical element having a reflecting surface which reflects the light of the intermediate image and makes it visually recognized as a virtual image, and selectively transmits the light component in the first polarization direction. The polarization transmitting portion is arranged outside the optical path range of the image light incident on the screen, and reflects external light incident on the optical axis of the intermediate image light toward the outside of the reflecting surface. Tilt in the direction.

The virtual image display device includes a light source, a screen, and a polarization transmitting portion. The light source emits image light polarized in the first polarization direction. Image light from a light source is incident on the screen to form an intermediate image. The polarization transmitting portion is arranged between the screen and an optical element having a reflecting surface that reflects the light of the intermediate image and makes it visually recognized as a virtual image, and selectively transmits the light component in the first polarization direction. Here, the polarization transmitting portion is arranged outside the optical path range of the image light incident on the screen, and reflects the incident external light corresponding to the optical axis of the light of the intermediate image toward the outside of the reflecting surface of the optical element. Tilt in the direction. In this embodiment, the polarization transmitting portion transmits the image light toward the optical element and moves a part of the external light incident on the optical axis of the image light to the outside of the optical element so as not to be reflected again by the optical element. reflect. Further, in this configuration, the image light is transmitted through the polarized light transmitting portion only once. Therefore, the virtual image display device can suitably reduce the decrease in the amount of light of the image light, and can preferably reduce the deterioration of the visibility of the virtual image due to the external light.

In one aspect of the virtual image display device, the light source emits image light polarized in a direction perpendicular to the horizontal direction as image light polarized in the first polarization direction. According to this aspect, even when the observer wears polarized sunglasses that cut the polarized light component in the horizontal direction, the observer can preferably visually recognize the virtual image.

In another aspect of the virtual image display device, the optical element is provided with a reflective film that selectively reflects an optical component in the first polarization direction on the incident surface side of the external light. According to this aspect, the virtual image display device can preferably reflect the light component in the first polarization direction of the external light that is not reflected by the polarization transmitting portion by the reflective film, and suppress the external light from entering the screen or the like.

In another aspect of the virtual image display device, the virtual image display device includes an absorption unit that absorbs visible light, and the polarization transmitting unit receives external light incident on the optical axis of the intermediate image. It reflects toward the absorption part. According to this aspect, the virtual image display device can suitably suppress that the external light reflected by the polarized light transmitting portion repeatedly reflects and affects the visibility of the virtual image.

In a preferred example of the virtual image display device, the screen is a transmissive screen. In another preferred example of the virtual image display device, the virtual image display device further includes a reflection unit in which the light of the intermediate image is incident from the screen and the light of the intermediate image is reflected toward the polarization transmitting portion.

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

<First Example>
[Outline 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 to allow an observer to 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 the light (also referred to as "image light") emitted by the light source unit 1, and "R1" to "R4" are image lights. It is a boundary line indicating the optical path range up to the combiner 5.

The light source unit 1 has laser elements of each color of red (R), green (G), and blue (B), and screens image light, which is synthetic light of a laser modulated based on an image signal, with a MEMS mirror. 2 Scan on. In this embodiment, the light source unit 1 emits light polarized in a direction perpendicular to the horizontal direction (also referred to as "vertical polarized light") 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 magnifier (EPE) that expands the exit pupil by widening the divergence angle of the 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 vertically polarized light, and after being reflected by the reflection mirror 3, is incident on the polarizing plate 4 as P-polarized light. Therefore, the polarizing plate 4 transmits the image light reflected by the reflection mirror 3 and reaches the combiner 5. Further, as will be described later, the inclination of the polarizing plate 4 is adjusted so as to reduce the amount of light reflected by the sunlight incident on the polarizing plate 4 to the combiner 5. The inclination adjustment of the polarizing plate 4 will be described later.

Further, the polarizing plate 4 is arranged 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). It is installed at a position that does not overlap the optical path range from the screen 2 to the screen 2 and the optical path range from the screen 2 to the reflecting mirror 3. As described above, the head-up display shown in FIG. 1 has a configuration in which the image light passes through the polarizing plate 4 only once.

The combiner (optical element) 5 projects the light forming the intermediate image generated by the screen 2 and partially reflects the projected light to the position of the observer's eyes to make the observer visually recognize the virtual image. .. Preferably, the reflecting surface of the image light of the combiner 5 has a substantially concave shape. As a result, the combiner 5 enlarges the virtual image.

[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 line 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 incident on the polarizing plate 4 from the combiner 5 in accordance with the optical axis of the image light (see arrow A2).

The sun's rays B1 enter the combiner 5 in a state of containing both horizontally polarized light (also referred to as "horizontal polarized light") and vertically polarized light, and at least a part of them is transmitted through the combiner 5. It is 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 sunlight B2 and goes out of the combiner 5 without being incident on the combiner 5. .. In this way, the polarizing plate 4 reflects the sunlight B2 in a direction that does not hit the combiner 5. In other words, the polarizing plate 4 is tilted in a direction in which the incident sunlight that coincides with the optical axis of the image light is reflected toward the outside of the combiner 5. As a result, the polarizing plate 4 suppresses the sunlight reflected by the polarizing plate 4 from being reflected by the combiner 5, and the visibility of the virtual image based on the multiple reflection of sunlight in the optical system of the head-up display is reduced. Can be suitably reduced.

On the other hand, the vertically polarized light component of the sunlight B1 passes through the polarizing plate 4 as the sunlight B3 and is incident on the reflection mirror 3. Then, the sun rays B3 incident on the reflection mirror 3 are reflected by the reflection mirror 3 and reach the screen 2 as the sun rays B4. It should be noted that the modified examples 2 and the second embodiment described later have a configuration that preferably suppresses the generation of such solar rays B3 and B4.

Here, the effect of using vertically polarized light for image light will be supplementarily described. As shown in FIG. 1, the image ray A3 reaching the observer's eyes is vertically polarized. In addition, polarized sunglasses generally have the property of cutting the polarized component in the horizontal direction (that is, S-polarized light). From the above, in the configuration of the first embodiment, even when the observer wears polarized sunglasses, the image light passes through the polarized sunglasses and preferably reaches the observer's eyes. Therefore, the observer can preferably visually recognize the virtual image even when wearing polarized sunglasses.

As described above, in the head-up display according to the first embodiment, the light source unit 1 that emits the image light of the vertically polarized component vertically polarized and the image light from the light source unit 1 are incident to form an intermediate image. A combiner 5 having a screen 2 forming an intermediate image and a reflecting surface for reflecting image light forming an intermediate image to make it visually recognized as a virtual image, and a combiner 5 arranged between the screen 2 and the combiner 5 to selectively transmit a vertically polarized light component. 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 corresponding to the optical axis of the image light forming the intermediate image to the outside of the reflecting surface of the combiner 5. It is tilted in the direction of reflection. As a result, the head-up display can suitably reduce the deterioration of the visibility of the virtual image due to sunlight while allowing the image light to reach the eyes of the observer.

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

(Modification example 1)
When the polarizing plate 4 is formed by superimposing a polarizing element and a base material, the polarizing plate 4 may be tilted so as to increase the transmittance of image light incident as P-polarized light.

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 base material 42. In such a configuration, even when the P-polarized image light is transmitted through the polarizing element 41, the visibility of the virtual image becomes high when the glass equipment 42 reflects the P-polarized image light transmitted through the polarizing element 41. It will decrease. Further, in general, the transmittance of the glass base material 42 with respect to P-polarized light differs depending on the incident angle. Therefore, preferably, the polarizing plate 4 is installed so that the image light is incident at an angle at which the transmittance of the glass base material 42 with respect to P-polarized light is high.

FIG. 3B shows the reflectance of 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 P-polarized light differs depending on the angle of incidence on the glass, and the reflectance of P-polarized light is low (that is, the transmittance of P-polarized light is high) in the vicinity of 40 to 70 degrees. There is.

In consideration of the above, in this modification, the polarizing plate 4 has an incident angle at which the transmittance of P-polarized light becomes high in an angle range in which sunlight corresponding to the optical axis of the image light is reflected to the outside of the combiner 5. The tilt is adjusted so that the angle at which the image light is incident is (for example, 40 to 70 degrees). As a result, the reflector 5 is suitably prevented from being irradiated with the reflected light from the polarizing plate 4 of sunlight, and the reflectance of the image light on the polarizing plate 4 is reduced to allow the observer to obtain a sufficient amount of image light. Can be reached in the eyes of.

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

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

Therefore, according to the configuration of FIG. 4, the polarizing filter 51 cuts the vertical polarization component of sunlight, the polarizing plate 4 cuts the horizontal polarization component of sunlight, and the sunlight passes through the polarizing plate 4 and the screen 2 It is possible to preferably suppress the incident on the light.

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

FIG. 5 is a configuration example of the head-up display according to the modified example 3. In the example of FIG. 5, in the head-up display, in addition to the polarizing filter 51 described in the modified example 2, a light absorber (absorbing portion) 6 is provided in the direction in which the polarizing plate 4 reflects sunlight. The light absorber 6 is a black member configured to have a low reflectance of visible light, and may be, for example, a dashboard. In this case, the sun rays B21 of the horizontally polarized light component (that is, the S polarized light component) transmitted through the polarizing filter 51 and the combiner 5 enter the polarizing plate 4 and are reflected by the polarizing plate 4 as the sun rays B22. In this case, the sun rays B22 are incident on the light absorber 6 and 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 was directed downward, but instead, it was directed upward as in the other configuration examples shown in FIGS. 1, 3, 4, 4, and the like. May be good. In this case, for example, the light absorber 6 is provided on the ceiling of the vehicle.

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

FIG. 6 is a configuration example of the head-up display according to the modified example 4. 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 ray A31 indicating the optical axis of the image light emitted from the light source unit 1 is a screen. It passes through 2 and the polarizing plate 4 and is incident on the combiner 5, is reflected by the combiner 5 as light rays A32, and reaches the observer's eyes. Further, the sunbeam B31 incident on the combiner 5 from the direction corresponding to the optical axis of the image light passes through the combiner 5, and the horizontally polarized light component (that is, the S polarized light component) is regarded as the sunbeam B32 in the direction deviating from the combiner 5. It is reflected and the vertically polarized light component is transmitted through the polarizing plate 4 as sunlight B33.

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

(Modification 5)
The screen 2 was a transmissive screen, but instead of this, a reflective screen may be used.

FIG. 7 is a configuration example of the head-up display according to the modified example 5. In the example of FIG. 7, the heads-up display has a reflective screen 2A. The screen 2A is a reflective optical member that produces 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 the surface on which the image light from the light source unit 1 is incident, and a reflective surface is formed on the surface opposite to the microlens array. Will be done. In this configuration, the image light emitted from the light source unit 1 is reflected by the screen 2A toward the combiner 5. Then, the polarizing plate 4 is provided between the screen 2A and the combiner 5, and the inclination is adjusted in the same manner as in the embodiment.

Similar to the configuration of the first embodiment, this configuration also preferably prevents the combiner 5 from being irradiated with the reflected light from the polarizing plate 4 of sunlight, and reduces the reflectance of the image light by the polarizing plate 4. It can be reduced to bring a sufficient amount of image light to the observer's eyes.

(Modification 6)
The head-up display may function as an optical element in which a part of the windshield of the vehicle reflects a part of the image light and reaches the observer's eyes like the combiner 5. In this case, the irradiation region of the windshield to which the image light is irradiated is an example of the "reflecting surface" in the present invention.

<Second Example>
FIG. 8 is a configuration example of the 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 vertically polarized light reflecting film 52 is provided on the surface of the combiner 5 that reflects image light.

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

Further, in the second embodiment, unlike the first embodiment, the polarization of the polarizing plate 4 is not adjusted in consideration of the reflection direction of sunlight, and in the example of FIG. 8, the polarizing plate 4 is the image light. It is arranged so as to reflect the sunlight overlapping the optical axis of the combiner 5 toward the combiner 5. In this case, preferably, the polarizing plate 4 has an incident angle of image light such that the transmittance of the polarizing plate 4 with respect to P-polarized light becomes high, as described in (Modification 1) of the first embodiment. In addition, the tilt should be adjusted.

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

Next, the optical path of sunlight that coincides with the optical axis of the image light will be described. After passing through the combiner 5, the sunbeam B51 that coincides with the optical axis of the image light is reflected by the vertically polarized light reflecting film 52 as the sunbeam B52 for the vertically polarized light component and vertically polarized as the sunbeam B53 for the horizontally polarized light component. It penetrates the film 52. The horizontally polarized sun ray B53 transmitted through the vertically polarized light reflecting film 52 is incident on the polarizing plate 4, and is reflected as the sunbeam B54 by the polarizing plate 4. Here, since the sunlight B54 is incident on the vertically polarized light reflecting film 52 as S-polarized light, it passes through the vertically polarized light reflecting film 52. As described above, in the second embodiment, the sunlight is reflected by either the vertically polarized light reflecting film 52 or the polarizing plate 4 and guided to the outside of the optical system of the head-up display, so that the visibility of the virtual image caused by the sunlight is visible. Deterioration can be suitably suppressed.

As described above, in the head-up display according to the second embodiment, the light source unit 1 that emits the image light of the vertically polarized component vertically polarized and the image light from the light source unit 1 are incident to form an intermediate image. A combiner 5 having a screen 2 forming an intermediate image and a reflecting surface for reflecting image light forming an intermediate image to make it visually recognized as a virtual image, and a combiner 5 arranged between the screen 2 and the combiner 5 to selectively transmit a vertically polarized light component. The polarizing plate 4 is provided. The combiner 5 has a vertically polarized light reflecting film 52 that selectively reflects the image light of the vertically polarized light component. As a result, the head-up display can suitably reduce the deterioration of the visibility of the virtual image due to sunlight while allowing the image light to reach the eyes of the observer.

In addition, each (modification example 1) to (modification example 6) of the first embodiment can be applied to the second embodiment in the same manner as the first embodiment.

1 Light source 2, 2A screen 3 Reflective mirror 4 Polarizing plate 5 Combiner 6 Light absorber

Claims (6)

It is a virtual image display device mounted on a vehicle.
A light source that emits image light polarized in the first polarization direction,
A screen on which image light from the light source is incident to form an intermediate image,
A polarization transmitting portion is provided between an optical element having a reflecting surface that reflects the light of the intermediate image and visually recognized as a virtual image and the screen, and selectively transmits a light component in the first polarization direction. ,
The polarization transmitting portion is arranged outside the optical path range of the image light incident on the screen, and is tilted in a direction in which the incident external light corresponding to the optical axis of the light of the intermediate image is reflected outside the reflecting surface. Be,
A virtual image display device in which external light incident on the optical axis of the intermediate image is reflected by the polarization transmitting portion and incident on the ceiling of the vehicle . The virtual image display device according to claim 1, wherein the light source emits image light polarized in a direction perpendicular to the horizontal direction as image light polarized in the first polarization direction. The virtual image display device according to claim 1 or 2, wherein the reflective film that selectively reflects the light component in the first polarization direction includes the optical element arranged on the incident surface side of the external light. According to any one of claims 1 to 3, wherein the obtaining Bei the absorbing portion external light entering coincides with the optical axis of the intermediate image light absorbing visible light to the ceiling incident Virtual image display device. The virtual image display device according to any one of claims 1 to 4, wherein the screen is a transmissive screen. The invention according to any one of claims 1 to 5, further comprising a reflecting portion in which the light of the intermediate image is incident from the screen and the light of the intermediate image is reflected toward the polarized light transmitting portion. Virtual image display device.