WO2015064497A1

WO2015064497A1 - In-vehicle projection device

Info

Publication number: WO2015064497A1
Application number: PCT/JP2014/078337
Authority: WO
Inventors: 染野　義博; 酒井　重史
Original assignee: アルプス電気株式会社
Priority date: 2013-10-31
Filing date: 2014-10-24
Publication date: 2015-05-07

Abstract

[Problem] To provide an in-vehicle projection device that can safely project a display image onto a windshield even when using laser light and can be made small in size. [Solution] A collimated beam of laser light emitted by a light-emitting unit (23A, 23B) is converted by an FT lens (33), reflected by a light-transmission mirror (34), and reflected by a first intermediate mirror (35) and a second intermediate mirror (36) such that a holographic image is formed on a screen (51). Projection light (B7) that contains said holographic image is reflected by a first projection mirror (55) and the reflected projection light (B8) is further reflected by a second projection mirror (56) such that a display image is projected onto a windshield. Since the modulating light beam (B4) and the projection light (B8) intersect each other between the first projection mirror (55) and the second projection mirror (56), the device as a whole can be made small in size even if the light path is long.

Description

In-vehicle projector

The present invention relates to an in-vehicle projector that projects a display image on a display area that functions as a semi-reflective surface such as a windshield of an automobile.

Patent Document 1 discloses an invention related to an in-vehicle projection device called a head-up display.

This projection device is composed of an optical scanning device, and a first mirror and a second mirror that apply light from the optical scanning device to a semi-transmissive mirror that is a windshield.

The optical scanning device includes three light source elements that emit laser beams of different wavelengths, a combining element that combines the three types of laser light, and an optical deflector that applies the laser light combined by the combining element to the semi-transmissive mirror. Have. The optical deflector includes a minute mirror that swings with respect to two orthogonal axes.

JP 2013-61554 A

In the on-vehicle projector described in Patent Document 1, a micro mirror is vibrated in a two-dimensional direction in an optical deflector, and a display image is generated when a laser beam scans a semi-transmissive mirror. In this structure, laser light is directly applied to a semi-transparent mirror such as a windshield, so it is dangerous because the laser light may be directly irradiated to the human eye when wiping and cleaning the outer surface of the windshield. is there.

Also, in the method of scanning a semi-transparent mirror with a laser beam using a minute mirror, it is difficult to greatly change the brightness of an image to be generated, and it is also difficult to perform a three-dimensional display.

Further, in the projection apparatus described in Patent Document 1, the optical axes from the light source element toward the semi-transmissive mirror are all included in the same plane. In an in-vehicle projection apparatus, it is necessary to apply scanning light upward from a second mirror to a semi-transmissive mirror such as a windshield, and it is necessary to direct the plane including the optical axis almost vertically. Therefore, the arrangement direction of various optical members is the vertical direction, and the vertical height dimension of the projection apparatus is increased. As a result, problems such as the inability to embed the projection device in the dashboard in the vehicle cabin are likely to occur.

SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide an in-vehicle projection apparatus that can perform a safe and clear display on a display area such as a windshield by using a laser beam. .

Another object of the present invention is to provide an in-vehicle projection apparatus that can be configured to be thin and small.

The present invention relates to an in-vehicle projection device that projects a display image onto a display area that functions as a semi-reflective surface in a vehicle interior of an automobile.
A laser light source, a phase modulation array that phase-modulates laser light emitted from the laser light source, a screen that forms an image of a modulated light beam phase-modulated by the phase modulation array as a hologram image, and an image formed on the screen A projection unit for enlarging the hologram image and projecting the hologram image onto the display area as the display image.

The on-vehicle projector of the present invention is safe because the hologram image generated from the laser beam is projected onto a semi-reflective surface such as a windshield, so that the laser beam does not directly enter the human eye. In addition, by generating a display image with a hologram image, the dynamic range of luminance change can be expanded, and three-dimensional display changes such as changing the distance of the virtual image displayed in front of the display area can be performed. It is possible to give.

In the present invention, it is preferable that the projection light is applied upward from the projection unit to the display area, and the optical path of the modulated light beam directed from the phase modulation array to the screen is directed substantially horizontally.

Further, it is preferable that the optical path of the laser light from the laser light source toward the phase modulation array is also directed substantially horizontally.

¡By directing each optical path horizontally, the in-vehicle projector can be made thin and can be easily embedded in a dashboard or the like in the vehicle interior.

In the present invention, it is preferable that the modulated light beam phase-modulated by the phase modulation array intersects with other light in the process of reaching the projection unit.

For example, the projection unit is configured so that a first projection mirror and a second projection mirror are opposed to each other, and projection light including a hologram image formed on the screen receives the first projection mirror and the second projection mirror. The modulated light beam reflected by the projection mirror and projected onto the display area and phase-modulated by the phase modulation array passes between the first projection mirror and the second projection mirror and passes through the screen. Given, the optical path of the projection light directed from the first projection mirror to the second projection mirror can be configured to intersect the modulated light flux.

Further, a first intermediate mirror and a second intermediate mirror are provided for directing the modulated light flux that has passed between the first projection mirror and the second projection mirror to the screen, and the second intermediate mirror is provided. The screen is disposed on an optical path from an intermediate mirror toward the first projection mirror.

Furthermore, it is preferable that the optical path from the second intermediate mirror to the first projection mirror and the optical path of the modulated light beam from the phase modulation array to the first intermediate mirror are opposite to each other.

Although it is possible to increase the magnification of the display image by lengthening the optical path for imaging the modulated light beam phase-modulated by the phase modulation array on the screen, in the present invention, by crossing the optical path in the apparatus, Even if the optical path is long, the apparatus can be made compact.

Further, in the present invention, a plurality of apertures are arranged on an optical path from the phase modulation array to the screen.

Since the in-vehicle projector of the present invention does not directly apply laser light to a display area such as a windshield, it is safe for human eyes. Moreover, various display forms can be selected by using the hologram image.
Furthermore, according to the present invention, the entire apparatus can be configured to be thin and small.

Explanatory drawing which shows the state with which the vehicle-mounted projection apparatus of embodiment of this invention was mounted in the vehicle, Explanatory drawing which shows an example of the display image by the vehicle projector. 1 is an exploded perspective view of an in-vehicle projector according to an embodiment of the present invention; The top view which shows arrangement | positioning of the main components of the vehicle-mounted projection apparatus of embodiment of this invention, The partial perspective view which shows the structure of a phase modulation part, and was seen from the V arrow direction shown in FIG. Partial enlarged plan view showing the configuration of the phase modulation unit, VII arrow view of FIG. 6, FIG. 4 is a partial perspective view showing the configuration of the hologram imaging unit, seen from the direction of arrow VIII shown in FIG.

As shown in FIG. 1, an in-vehicle projector 10 according to an embodiment of the present invention is used by being embedded in a dashboard 2 in front of a passenger compartment of an automobile 1. A display image 70 shown in FIG. 2 is projected from the in-vehicle projection device 10 onto the display area 3 a of the windshield 3.

Since the display area 3a functions as a semi-reflective surface, the display image 70 projected on the display area 3a is reflected toward the driver 5 in the display area 3a, and a virtual image 6 is formed in front of the windshield 3. To do. By viewing the virtual image 6 in front of the windshield 3, it appears to the driver 5 that various information is displayed in front of the steering wheel 4.

3 and 4 show the overall structure of the in-vehicle projector 10.
As shown in FIG. 3, the case of the in-vehicle projector 10 is separated into a lower case 11 and an upper case 12, and the optical unit 20 is housed inside the case. The optical unit 20 has an optical base 21, and the optical base 21 is supported inside the lower case 11 via an elastic member such as an elastomer or a metal spring. The lower case 11 is fixed to the interior of the dashboard 2 in the passenger compartment, but since the optical base 21 is supported via an elastic member, it is possible to prevent the vehicle body vibration from directly affecting the optical unit 20. .

In the state in which the optical unit 20 is housed inside, the lower case 11 and the upper case 12 are positioned with respect to each other by concave and convex fitting by positioning pins 15 formed integrally with the lower case 11. Female screw holes 16 are formed at a plurality of locations in the lower case 11, and fixing screws inserted through the upper case 12 are screwed into the female screw holes 16, so that the lower case 11 and the upper case 12 are fixed to each other.

The projection window 13 is opened in the upper case 12. The projection window 13 is disposed so as to be exposed on the upper surface of the dashboard 2, and the display image 70 is projected from the projection window 13 onto the display area 3 a of the windshield 3. A transparent cover plate 14 is attached to the projection window 13. The cover plate 14 prevents dust from entering the case. The cover plate 14 is configured with an optical filter that suppresses transmission of light having a wavelength other than the display light of the hologram image projected onto the display region 3a so that external light does not directly enter the case from the projection window 13. Is preferred.

As shown in FIGS. 3 and 4, in the optical unit 20, various optical components are mounted on the optical base 21. As shown in FIG. 4, the optical unit 20 includes a phase modulation unit 20A, a hologram imaging unit 20B, and a projection unit 20C due to the configuration of the optical components.

As shown in FIG. 5, the reference base 22 is provided in the phase modulation unit 20A, and the reference base 22 is fixed on the optical base 21 by screws.

On the reference base 22, the first light emitting unit 23A and the second light emitting unit 23B are arranged so as to overlap each other. The first light emitting unit 23A has a first positioning block 24A, and the second light emitting unit 23B has a second positioning block 24B. The first positioning block 24A is installed on a positioning reference surface 22A formed on the reference base 22, and is fixed to the reference base 22 with a plurality of fixing screws 25A. The second positioning block 24B is installed on the first positioning block 24A, and is fixed to the first positioning block 24A with a plurality of fixing screws 25B.

FIG. 6 shows the internal structure of the second positioning block 24B. An optical path 26B is formed in the positioning block 24B. A second laser unit 27B, which is a laser light source, is attached to the closed side end portion (the end portion on the right side of FIG. 6) of the optical path 26B. The second laser unit 27B is configured by housing a semiconductor laser chip in a case. A collimating lens 28B is fixed inside the light path 26B.

The laser beam B0 emitted from the second laser unit 27B is divergent light, and as shown in FIG. 7, the cross-sectional shape of the laser beam B0 is elliptical or oval. The major axis of the laser beam B 0 is directed in the horizontal direction (i) parallel to the upper surface of the reference base 22, and the minor axis is directed in the vertical direction (ii) perpendicular to the upper surface of the reference base 22.

As shown in FIG. 7, the effective diameter (effective region) of the collimator lens 28B is rectangular, and the long side of the rectangle is oriented in the same horizontal direction (i) as the major axis direction of the cross section of the laser beam B0. Yes. Therefore, when the laser beam B0 passes through the collimating lens 28B, it is converted into a collimated beam B1 having a rectangular cross section.

As shown in FIG. 6, the opening end (opening end on the left side in FIG. 6) of the light path 26B of the positioning block 24B is closed by the light transmitting cover 29B. In the laser beam B0 shown in FIG. 7, when the ratio of the P wave component to the S wave component is large in the short axis direction (vertical direction (ii)), that is, the polarization direction of the light of the P wave component is mainly directed to the short axis direction. In such a case, the translucent cover 29B is preferably composed of a half-wave plate. When the half-wave plate is used, the polarization direction is changed by 90 degrees, and in the collimated light beam B1, the P wave component whose polarization direction is the horizontal direction (i) increases. As a result, as shown in FIG. 2, the luminous flux of the display image projected on the display area 3a is such that the polarization direction of many P-wave components is directed in the horizontal direction (i) with respect to the windshield 3. In the display area 3a, the display image 70 is easily semi-reflected.

Although the internal structure of the first positioning block 24A provided in the first light emitting unit 23A shown in FIG. 5 is not shown, it is substantially the same as the second positioning block 24B shown in FIG. Also in the first positioning block 24A, the first laser unit 27A is provided at the closed end of the internal optical path 26A (not shown in the drawing). A collimating lens 28A (not shown) is housed in the optical path 26A, and the laser beam emitted from the first laser unit 27A has a rectangular cross section with a long side in the horizontal direction (i). Converted to B1. Further, a translucent cover 29A (not shown in the drawing) is provided at the opening end of the light passage 26A.

As shown in FIGS. 3 and 4, the phase modulation unit 20A is provided with a heat radiation cooling unit 37 that radiates heat generated from the first laser unit 27A and the second laser unit 27B.

The laser unit 27A of the first light emitting unit 23A and the laser unit 27B of the second light emitting unit 23B have different wavelengths of emitted laser light. In the in-vehicle projector 10 according to the embodiment, the wavelength of the collimated light beam B1 emitted from the first light emitting unit 23A is red at 642 nm, and the wavelength of the collimated light beam B1 emitted from the second light emitting unit 23B is 515 nm. There is a green system.

Therefore, in the following, the collimated light beam obtained from the first light emitting unit 23A will be described with reference symbol B1r, and the collimated light beam obtained from the second light emitting unit 23B will be described with reference character B1g.

As shown in FIG. 5, the reference base 22 is integrally formed with a positioning holding portion 22B, and the phase modulation array 31 is held inside a holding frame portion 22C formed in the positioning holding portion 22B. Since the positioning reference surface 22A for positioning the first light emitting part 23A and the second light emitting part 23B and the holding frame part 22C are integrally formed on the same reference base 21, the first light emitting part 23A and The collimated light beams B1r and B1g emitted from the second light emitting units 23B can be incident on the optical surface 31a of the phase modulation array 31 at an optimal incident angle.

The phase modulation array 31 is LCOS (Liquid Crystal On On Silicon). LCOS is a reflective panel having a liquid crystal layer and an electrode layer such as aluminum. In LCOS, electrodes that apply an electric field to a liquid crystal layer are regularly arranged to form a plurality of pixels. The tilt angle in the thickness direction of the crystal layer in the liquid crystal layer changes due to the change in electric field strength applied to each electrode, and the phase of the reflected laser light is changed for each pixel.

3 and 4, the phase modulation unit 20A is provided with a heat radiation cooling unit 38 that radiates heat generated in the phase modulation array 31.

As shown in FIG. 5, the collimated light beam B1r converted by the collimating lens 28A in the first light emitting unit 23A is given to the region below the phase modulation array 31, and the collimating lens 28B in the second light emitting unit 23B. The collimated light beam B1g converted in (1) is given to the upper region of the phase modulation array 31. In the phase modulation array 31, the region to which the collimated light beam B1r is given becomes the first modulation region M1, and the region to which the collimated light beam B1g is given becomes the second modulation region M2.

Since the cross section of the collimated light beam B1r and the collimated light beam B1g is rectangular, the first modulation region M1 and the second modulation region M2 are also rectangular. By adjusting the relative position in the vertical direction (ii) of the first light emitting unit 23A and the second light emitting unit 23B with the reference base 22, the first modulation region M1 and the second modulation region M2 Are set so as not to overlap each other.

The phase of the collimated light beam B1r given to the first modulation region M1 is modulated by passing through each of the plurality of pixels of the phase modulation array 31, and the collimated light beam B1g given to the second modulation region M2 is also The phase is modulated by passing through each of the plurality of pixels. As shown in FIG. 6, the modulated light beam B 2 reflected from the phase modulation array 31 becomes interference light in which lights that have passed through the respective pixels interfere with each other. The interference light includes interference between light components of the red collimated light beam B1r, interference between light components of the green collimated light beam B1g, and further, light components of the collimated light beam B1r and the collimated light beam B1g. Interference.

As shown in FIG. 3, a lens holder 32 is provided in the phase modulation unit 20A. The lens holder 32 is positioned and fixed on the reference base 22. An FT lens (Fourier transform lens) 33 is held on the lens holder 32. The modulated light beam B2 reflected by the phase modulation array 31 is transmitted through the FT lens 33 to become a modulated light beam B3 subjected to Fourier transform.

As shown in FIG. 3, the phase modulator 20A is provided with a light transmission mirror 34 held by a mirror holder 34a. The light transmission mirror 34 is a plane mirror, and the optical axis of the FT lens 33 is incident on the reflection surface at a predetermined angle. The modulated light beam B3 Fourier-transformed by the FT lens 33 is reflected by the light transmission mirror 34, and the reflected modulated light beam B4 passes through the optical unit 20 and is sent to the hologram imaging unit 20B.

As shown in FIG. 3, the hologram imaging unit 20B is provided with a first intermediate mirror 35 held by the mirror holding unit 35a and a second intermediate mirror 36 held by the mirror holding unit 36a. Yes. The first intermediate mirror 35 and the second intermediate mirror 36 are plane mirrors. As shown in FIG. 4, the reflection surface of the first intermediate mirror 35 faces the reflection surface of the light transmission mirror 34 provided in the phase modulation unit 20A. Further, the reflecting surfaces of the first intermediate mirror 35 and the second intermediate mirror 36 face each other at a predetermined angle. In the hologram imaging unit 20B, the screen 51 is arranged in the reflection direction by the reflection surface of the second intermediate mirror 36.

As shown in FIG. 4, the modulated light beam B4 reflected by the light transmission mirror 34 travels in the right direction in the figure after being reflected in the first intermediate mirror 35, and the reflected modulated light beam B5 is second reflected. Are reflected by the intermediate mirror 36. Then, the modulated light beam B 6 reflected by the second intermediate mirror 36 is given to the screen 51.

In the phase modulation array 31, the phase of the red laser light is modulated for each pixel in the first modulation region M1, and the green laser light is modulated for each pixel in the second modulation region M2. . The light in which the interference light of the red and green laser beams is mixed is Fourier-transformed by the FT lens, and the modulated light beams B3, B4, B5, and B6 are defocused on the screen 51 through the optical path in the case. The hologram image is formed on the screen 51.

When the interference light that has passed through the phase modulation array 31 is condensed through the FT lens 33, the first-order diffracted light is imaged on the screen 51. On the screen 51, a hologram image having substantially the same content as the display image 70 posted in the display area 3a shown in FIG. This hologram image is formed with a red color and a green color and a mixed color of two hues. Since the modulated light beams B3, B4, B5, and B6 contain light interference components, a large number of stray light images generated by second-order diffracted light, third-order diffracted light, and the like exist in the space from the phase modulation array 31 to the screen 51. . Therefore, a plurality of apertures are formed on the optical path from the phase modulation array 31 to the screen 51 so that only the first-order diffracted light can reach the screen 51.

As shown in FIGS. 3 and 4, a light shielding wall 41a is provided at a light emitting portion from the phase modulation unit 20A, and a rectangular first aperture 41 is opened in the light shielding wall 41a. A light shielding wall 42a is provided at a light incident portion on the hologram imaging portion 20B, and a rectangular second aperture 42 is opened in the light shielding wall 42a. A light shielding wall 43a is provided between the second intermediate mirror 36 and the screen 51, and a rectangular third aperture 43 is opened in the light shielding wall 43a. The third aperture 43 is also shown in FIG.

Three-

stage apertures

41, 42, and 43 are provided on the optical path from the modulated light beam reflected by the light transmission mirror 34 to the screen 51, and stray light other than the first-order diffracted light is shielded. Only the first-order diffracted light that forms the image can be reached.

As shown in FIG. 8, in the hologram imaging unit 20 B, a screen 51 is disposed on the front side (light emission side) of the third aperture 43. The modulated light beam B 6 reflected by the second intermediate mirror 36 passes through the third aperture 43 and reaches the screen 51, and a hologram image by the first-order diffracted light is generated on the screen 51. The screen 51 is a transmissive diffuser having fine irregularities formed on the surface, and light including a hologram image formed on the screen 51 passes through the screen 51 and becomes divergent projection light B7. . As shown in FIG. 4, the projection light B7 passes through the fourth aperture 44 formed in the light shielding wall 42a and is given to the projection unit 20C.

As shown in FIG. 8, in the hologram imaging unit 20 B, the motor 52 is fixed to the light shielding wall 43 a in which the third aperture 43 is opened, and the disk-shaped screen 51 is always rotated by the power of the motor 52. It has been made. By rotating the screen 51, speckle noise that causes flickering of the display image 70 can be reduced.

As shown in FIG. 8, in the hologram image forming unit 20B, a monitor detection unit 53 is provided on the light shielding wall 43a. The monitor detection unit 53 is provided below the third aperture 43. The monitor detection unit 53 includes three detection units: a red wavelength detection unit 53a, a green wavelength detection unit 53b, and a position detection unit 53c. Each of the

detectors

53a, 53b, and 53c has a light receiving element such as a pin photodiode housed in a closed space, and an opening is formed on the side facing the second intermediate mirror 36. In the red wavelength detection unit 53a, the opening is covered with a wavelength filter that transmits red light, and in the green wavelength detection unit 53b, the opening is covered with a wavelength filter that transmits green light.

Each

detection unit

53a, 53b, 53c is irradiated with either the first-order diffracted light or multi-order diffracted light other than the first-order diffracted light. Based on the detection output of the position detection unit 53c, the positions of the first light emitting unit 23A, the second light emitting unit 23B, and other optical components are adjusted. Further, the emission intensity of the first laser unit 27A and the second laser unit 27B is automatically adjusted based on the detection outputs from the red wavelength detection unit 53a and the green wavelength detection unit 53b, and the phase modulation by the phase modulation array 31 is performed. Operation is also automatically controlled.

3 and 4, the projection unit 20C is provided with a first projection mirror 55 and a second projection mirror 56 facing each other. The reflecting surface 55a of the first projection mirror 55 and the reflecting surface 56a of the second projection mirror 56 are concave mirrors (magnifying mirrors). The projection light B 7 including the hologram image formed on the screen 51 is diverged by the screen 51 and given to the first projection mirror 55. The projection light B8 obtained by enlarging the hologram image by the first projection mirror 55 is given to the second projection mirror 56, and the hologram image is further enlarged. As shown in FIG. 3, the projection light B9 reflected by the reflecting surface 56a of the second projection mirror 56 becomes an upward light beam, passes through the cover plate 14, and, as shown in FIG. 1, the display area of the windshield 3 3a is projected.

As shown in FIG. 2, in the display image 70, various information associated with the traveling of the vehicle such as a vehicle speed display 71, a shift lever position information 72, and navigation information 73 are displayed. The display image 70 is displayed with red light or green light, or is displayed with a mixed color of red light and green light.

Since the windshield 3 functions as a semi-reflective surface, it appears to the driver 5 that the display image 70 exists at the imaging position of the virtual image 6 ahead of the windshield 3.

In this in-vehicle projector 10, since the hologram image formed on the screen 51 is enlarged and projected onto the display area 3 a, even if the inside of the cover plate 14 is viewed from the outside of the windshield 3, Laser light is not directly applied to human eyes, and safety can be ensured.

In the in-vehicle projector 10 installed in a car, the optical base 21 of the optical unit 20 is oriented almost horizontally. As shown in FIG. 4, collimated light beams B1r and B1g emitted from the first light emitting unit 23A and the second light emitting unit 23B, the modulated light beam B2 modulated by the phase modulation array 31, and the modulated light beam B3 through the FT lens. These optical axes extend horizontally so as to be parallel to the optical base 21. The optical axes of the modulated light beam B4 reflected by the light transmission mirror 34, the modulated light beam B5 reflected by the first intermediate mirror 35, and the modulated light beam B6 reflected by the second intermediate mirror 36 are also represented by the optical base. 21 and extends horizontally. The optical axis of the projection light B7 that has passed through the screen 51 is also horizontal, and the projection light B8 reflected by the first projection mirror 55 is given slightly upward to the second projection mirror 56, so that the second projection mirror 56 The projection light B 9 reflected by 56 is irradiated upward toward the windshield 3.

Since the light beams of the light components other than the projection lights B8 and B9 are directed almost horizontally across the upward projection direction of the projection light B9, the in-vehicle projector 10 can be configured to be thin, It becomes easy to embed inside the dashboard 2.

As shown in FIGS. 3 and 4, the modulated light beam B 4 from the light transmission mirror 34 to the first intermediate mirror 35 passes between the first projection mirror 55 and the second projection mirror 56, and the first The projection light B8 directed from the projection mirror 55 to the second projection mirror 56 intersects the modulated light beam B4. By making the light intersect at the projection unit 20C, a long optical path from the FT lens 33 to the screen 51 can be secured, and a hologram image can be formed on the screen 51 at an appropriate magnification. Further, by crossing the light beams, the in-vehicle projector 10 can be made compact even if the optical path is long.

As shown in FIG. 4, the direction of the light is opposite between the modulated light beam B4 directed from the light transmission mirror 34 to the first intermediate mirror 35 and the modulated light beam B6 directed from the second intermediate mirror 36 to the screen 51. In addition, the direction of the projection light B7 from the screen 51 toward the first projection mirror 55 is also opposite to the direction of the modulated light beam B4. As described above, the entire apparatus can also be made compact by reversing the direction of the light beam in the case.

DESCRIPTION OF SYMBOLS 1 Car 2 Dashboard 3 Windshield 5 Driver 10 Vehicle projection device 11 Lower case 12 Upper case 14 Cover plate 20 Optical unit 20A Phase modulation unit 20B Hologram imaging unit 20C Projection unit 21

Optical bases

23A and 23B

Light emitting unit

27A, 27B Laser units 28A, 28B Collimating lens 31 Phase modulation array 33 FT lens 34 Transmitting mirror 35 First intermediate mirror 36 Second

intermediate mirror

41, 42, 43, 44 Aperture 51 Screen 55 First projection mirror 56 Second Projection mirror 70 Display image B0 Laser beam B1r, B1g Collimated beam B1, B2, B3, B4, B5, B6 Modulated beam B7, B8 Projected light M1 First conversion region M2 Second conversion region

Claims

In an in-vehicle projection device that projects a display image onto a display area that functions as a semi-reflective surface in a vehicle interior
A laser light source, a phase modulation array that phase-modulates laser light emitted from the laser light source, a screen that forms an image of a modulated light beam phase-modulated by the phase modulation array as a hologram image, and an image formed on the screen An in-vehicle projection apparatus, comprising: a projection unit that enlarges a hologram image and projects the hologram image onto the display area as the display image.
The in-vehicle projection apparatus according to claim 1, wherein projection light is given upward from the projection unit to the display area, and an optical path of a modulated light beam directed from the phase modulation array to the screen is directed substantially horizontally.
3. The on-vehicle projector according to claim 2, wherein an optical path of the laser beam directed from the laser light source to the phase modulation array is also directed substantially horizontally.
The in-vehicle projector according to any one of claims 1 to 3, wherein the modulated light beam phase-modulated by the phase modulation array intersects with other light in the process of reaching the projection unit.
The projection unit is configured so that a first projection mirror and a second projection mirror are opposed to each other, and projection light including a hologram image formed on the screen is transmitted to the first projection mirror and the second projection. Reflected by the mirror and projected onto the display area,
The modulated light beam phase-modulated by the phase modulation array passes between the first projection mirror and the second projection mirror and is given to the screen, and the second projection mirror transmits the second projection light from the first projection mirror. The in-vehicle projector according to claim 4, wherein an optical path of projection light directed to the projection mirror intersects the modulated light beam.
There are provided a first intermediate mirror and a second intermediate mirror for directing the modulated light flux that has passed between the first projection mirror and the second projection mirror to the screen, and the second intermediate mirror The in-vehicle projector according to claim 5, wherein the screen is disposed on an optical path from the projector toward the first projection mirror.
The in-vehicle use according to claim 6, wherein an optical path from the second intermediate mirror toward the first projection mirror and an optical path of a modulated light beam from the phase modulation array toward the first intermediate mirror are opposite to each other. Projection device.
The in-vehicle projector according to any one of claims 1 to 7, wherein a plurality of apertures are arranged on an optical path from the phase modulation array to the screen.