JP7081285B2 - Manufacturing method of virtual image display device, screen member and screen member - Google Patents

Description

The disclosure according to this specification relates to a virtual image display device, a screen member, and a method for manufacturing the screen member.

Conventionally, there is known a virtual image display device that visually displays an image by projecting an image onto a projection unit. In the virtual image display device of Patent Document 1, an image is formed by incident with a light source unit that emits light source light of a plurality of wavelengths discrete from each other and light source light of a plurality of wavelengths, and the light source light is guided to the projection unit side. It has a shining screen part. The screen portion has a plurality of convex structures arranged in an array.

Japanese Unexamined Patent Publication No. 2017-3803

In Patent Document 1, when the light source light is incident on the convex structure, the spreading angle of the light source light is expanded. As a result, the light source light reaches a wide range, and the viewing area where the observer can visually recognize the image as a virtual image can be enlarged. However, on the other hand, since the eyes of the observer who visually recognizes the virtual image are located in a part of the visual recognition area, the light source light incident on the pupil of the observer is relative to the entire emitted light source light. It is a little. Therefore, the screen portion having the convex structure can be regarded as a screen having a very low aperture ratio, and the observer sees that only a part of the convex structure emits light. Therefore, there is a problem that there are many gaps that do not seem to emit light between the convex structures arranged in an array, and a grainy feeling is recognized in the virtual image, and there is room for improvement in the visibility of the virtual image. ..

One object disclosed is to provide a virtual image display device having good visibility of a virtual image.

Further, one object disclosed is to provide a screen member capable of displaying an image with good visibility and a method for manufacturing the screen member.

One aspect disclosed here is a virtual image display device that visually displays an image by projecting an image onto a projection unit (3a).
A light source unit (10) that emits light source light containing a plurality of wavelengths,
An image is formed by incident light sources of a plurality of wavelengths, and a screen unit (20, 220, 320) that guides the light source light to the projection unit side is provided.
The screen unit has wavelength selectivity that interacts more with a specific wavelength among a plurality of wavelengths than other wavelengths, and has a radial light guide characteristic distribution that expands the spread angle of the light source light. It has a plurality of selection units (22r, 22g, 22b, 222).
Wavelengths in which specific wavelengths are different from each other in a plurality of wavelength selection units, and the extreme value positions (Cr, Cg, Cb) that take extreme values in the light guide characteristic distribution are shifted in the radial direction. There is a combination of selections.

According to such an aspect, in the combination of wavelength selection units having different specific wavelengths with large interaction, the extreme position of the light guide characteristic distribution of the wavelength selection unit is arranged so as to be displaced in the radial direction. Therefore, in the screen portion where the light source light including a plurality of wavelengths is incident, the spreading characteristics of the light source light of different wavelengths in this combination are shifted in the radial direction from each other. For this reason, when an observer whose eyes are located in a part of the viewing area visually recognizes a virtual image, the light emitting positions may be visually recognized as if they are displaced in the radial direction without completely overlapping with each other at different wavelengths. can. Therefore, it is possible to prevent the emission positions from being dispersed among a plurality of wavelengths and the portion that does not appear to emit light from being unintentionally generated. As described above, it is possible to provide a virtual image display device having good visibility of the virtual image.

Further, another disclosed aspect is a virtual image display device that visually displays an image by projecting an image onto a projection unit (3a).
A light source unit (10) that emits light source light containing a plurality of wavelengths,
An image is formed by incident light sources of a plurality of wavelengths, and a screen unit (20) that guides the light source light to the projection unit side is provided.
The screen unit has wavelength selectivity with a larger interaction than other wavelengths with respect to a specific wavelength among a plurality of wavelengths, and has a wavelength selection having a radial periodic structure that expands the spread angle of the light source light. It has a plurality of parts (22r, 22g, 22b, 222) and has a plurality of parts (22r, 22g, 22b, 222).
A wavelength selection unit in which specific wavelengths are different from each other in a plurality of wavelength selection units, the periods of the periodic structure are set to match each other, and the phases of the periodic structure are staggered. There is a combination of.

According to such an aspect, in the combination of wavelength selection units having different specific wavelengths with large interaction, the phases of the wavelength selection units in the periodic structure are arranged out of phase. Therefore, in the screen portion where the light source light including a plurality of wavelengths is incident, the spreading characteristics of the light source light of different wavelengths in this combination are shifted in the radial direction from each other. Therefore, when an observer whose eyes are located in a part of the visual recognition area visually recognizes a virtual image, the emission positions that can be arranged periodically are slightly displaced in the radial direction between the light sources of different wavelengths of the above combination. It is visually recognized. Therefore, the emission positions are dispersed among a plurality of wavelengths, and the presence of gaps that do not appear to emit light is suppressed. As described above, it is possible to reduce the graininess of the virtual image and provide a virtual image display device having good visibility of the virtual image.

Further, another aspect disclosed is a screen member that forms an image by projecting light.
Wavelength selection unit (22r, 22g, 22b, 222) having a wavelength selectivity with a larger interaction than other wavelengths with respect to a specific wavelength and having a radial periodic structure that expands the spreading angle of light. Have multiple
Among a plurality of wavelength selection units, specific wavelengths are different from each other, the periods of the periodic structure are set to match each other, and the phases of the periodic structure are shifted in the radial direction. There is a combination of wavelength selectors.

According to such an aspect, in the combination of wavelength selection units having different specific wavelengths with large interaction, the phases of the wavelength selection units in the periodic structure are arranged out of phase. Therefore, in the screen member in which the light source light including a plurality of wavelengths is incident, the spreading characteristics of the light source light of different wavelengths in this combination are shifted in the radial direction from each other. Therefore, when the observer visually recognizes the image displayed by using the screen member, the emission positions that can be arranged periodically can be visually recognized with a slight radial deviation between the light sources of different wavelengths of the above combination. Therefore, the emission positions are dispersed among a plurality of wavelengths, and the presence of gaps that do not appear to emit light is suppressed. As described above, it is possible to reduce the graininess in the image display, and it is possible to provide a screen member capable of displaying an image with good visibility.

Further, another aspect disclosed is a method for manufacturing a screen member (220a, 320a) that forms an image by projecting light.
A material preparation step (S21) for preparing a plate-shaped hologram material (90) having exposure sensitivity to light of a plurality of wavelengths discrete with each other, and
The pre-exposure step (S22) of exposing the hologram material with light of one wavelength out of a plurality of wavelengths,
After the pre-exposure step, the hologram material is shifted in the radial direction intersecting the optical axis of light (S23, S25).
After the shifting step, a post-exposure step (S24, S26) of exposing the hologram material with light having one wavelength different from the wavelength already exposed among the plurality of wavelengths is included.

According to such an aspect, the hologram material is displaced in the radial direction to perform exposure at each wavelength. By such multiple exposure, in the light guide characteristic distribution of each wavelength due to the interference fringes recorded on the hologram material, the extreme value position can be shifted in the radial direction between each wavelength. As a result, when the observer visually recognizes the image displayed by using the screen member, the light emitting positions can be visually recognized as if they are displaced in the radial direction without completely overlapping each other at different wavelengths. Therefore, it is possible to prevent the emission positions from being dispersed among a plurality of wavelengths and the portion that does not appear to emit light from being unintentionally generated. Therefore, it is possible to manufacture a screen member capable of displaying an image with good visibility.

Further, another aspect disclosed is a method for manufacturing a screen member (20a, 320a) that forms an image by projecting light.
Material preparation step (S11) for preparing a plurality of plate-shaped hologram materials (90) having exposure sensitivity to light of a specific wavelength among a plurality of wavelengths discrete with each other and having different specific wavelengths from each other. When,
An exposure step (S12) in which each hologram material is sequentially replaced and exposed at the same position by light of a specific wavelength corresponding to each hologram material individually.
After the exposure step, a staggered laminating step (S13) of staggering and laminating the hologram materials in the radial direction intersecting the optical axis of light is included.

According to such an aspect, a plurality of hologram materials corresponding to each wavelength are exposed and then laminated so as to be displaced from each other in the radial direction. By such a shift stacking, in the light guide characteristic distribution of each wavelength due to the interference fringes recorded on the hologram material, the extreme value position can be shifted in the radial direction between each wavelength. As a result, when the observer visually recognizes the image displayed by using the screen member, the light emitting positions can be visually recognized as if they are displaced in the radial direction without completely overlapping each other at different wavelengths. Therefore, it is possible to prevent the emission positions from being dispersed among a plurality of wavelengths and the portion that does not appear to emit light from being unintentionally generated. Therefore, it is possible to manufacture a screen member capable of displaying an image with good visibility.

It should be noted that the reference numerals in parentheses exemplify the correspondence with the parts of the embodiments described later, and are not intended to limit the technical scope.

It is a figure which shows the structure of the HUD apparatus of 1st Embodiment. It is a figure which shows the light source part and the screen member of 1st Embodiment. It is sectional drawing of the screen member of 1st Embodiment. It is a graph which shows the wavelength dependence of the diffraction efficiency in the hologram layer which makes the green wavelength of 1st Embodiment a specific wavelength. It is a figure for demonstrating the phase shift of Example 1. FIG. It is a figure for demonstrating the phase shift of Example 2. FIG. It is a figure for demonstrating the phase shift of Example 3. FIG. It is a figure for demonstrating the phase shift of Example 4. FIG. It is a figure for demonstrating the phase shift of Example 5. FIG. It is a figure for demonstrating the phase shift of Example 6. It is a figure for demonstrating the phase shift of Example 7. FIG. It is a reference figure for demonstrating the shift of the light emitting point of the virtual image of 1st Embodiment. It is a flowchart which shows the manufacturing method of the screen member of 1st Embodiment. It is a figure for demonstrating the exposure process of 1st Embodiment. It is sectional drawing of the screen member of 2nd Embodiment. It is a flowchart which shows the manufacturing method of the screen member of 2nd Embodiment. It is a figure which shows the structure of the HUD apparatus of 3rd Embodiment. It is a flowchart which shows the manufacturing method of the screen member of 3rd Embodiment. It is a figure for demonstrating the process of making a master hologram of 3rd Embodiment. It is a figure for demonstrating the process of making a transmission type hologram of 3rd Embodiment.

Hereinafter, a plurality of embodiments will be described with reference to the drawings. By assigning the same reference numerals to the corresponding components in each embodiment, duplicate description may be omitted. When only a part of the configuration is described in each embodiment, the configuration of the other embodiment described above can be applied to the other parts of the configuration. Further, not only the combination of the configurations specified in the description of each embodiment but also the configurations of a plurality of embodiments can be partially combined even if the combination is not specified. ..

(First Embodiment)
As shown in FIG. 1, the virtual image display device according to the first embodiment of the present disclosure is used in a vehicle, and is housed in the instrument panel 2 of the vehicle, so that the head-up display mounted on the vehicle is mounted on the vehicle. It is a device (hereinafter, HUD device) 100. The HUD device 100 projects an image onto a projection unit 3a set on the windshield 3 of the vehicle, so that the image is visually displayed as a virtual image by an occupant as an observer. That is, when the display light of the image reflected by the projection unit 3a reaches the visual recognition area EB provided in the interior of the vehicle, the occupant whose eye point EP is located in the visual recognition area EB displays the display light as a virtual image VRI. Perceive as. Then, the occupant can recognize various information displayed as a virtual image VRI. Examples of the various information displayed as a virtual image include information indicating the state of the vehicle such as the speed of the vehicle and the remaining amount of fuel, navigation information such as visibility assistance information and road information, and the like.

In the following, unless otherwise specified, the notations in the front, rear, front-rear direction, upward, downward, vertical, left, right, and left-right directions are described with reference to the vehicle on the horizontal plane.

The windshield 3 of the vehicle is formed in the shape of a translucent plate by, for example, glass or synthetic resin, and is arranged above the instrument panel 2. The windshield 3 forms a projection portion 3a on which the display light is projected into a smooth concave or planar shape. The projection unit 3a may not be provided on the windshield 3. For example, a combiner that is separate from the vehicle may be installed in the vehicle, and the combiner may be provided with the projection unit 3a.

The viewing area EB is a spatial area in which the virtual image VRI displayed by the HUD device 100 can be visually recognized so as to satisfy a predetermined standard (for example, the entire virtual image VRI can be visually recognized at a predetermined brightness or higher), and is also referred to as an eye box. Will be done. The visible area EB is typically set to overlap the eyelips set on the vehicle. The eye lip is set in an ellipsoidal shape based on an eye range that statistically represents the spatial distribution of the occupant's eye point EP.

A specific configuration of such a HUD device 100 will be described below with reference to FIGS. 2 and 3. As shown in FIG. 1, the HUD device 100 includes a light source unit 10, a screen unit 20, an enlarged light guide unit 30, and the like. These components are housed, for example, inside a hollow housing 9 having a light-shielding property.

The light source unit 10 emits light source light including a plurality of wavelengths discrete (for example, 20 nm or more apart) from each other. In particular, a laser scanner is adopted in the light source unit 10 of the present embodiment. As shown in FIG. 2, the light source unit 10 has a laser projection unit 11 and a scanning unit 15.

The laser projection unit 11 has a plurality of laser oscillators 12a, 12b, 12c, a plurality of condenser lenses 13a, 13b, 13c, a folded mirror 14a, and a plurality of dichroic mirrors 14b, 14c. In this embodiment, three laser oscillators 12a, 12b, 12c and three condenser lenses 13a, 13b, 13c are provided, and two dichroic mirrors 14b, 14c are provided.

The three laser oscillators 12a, 12b, and 12c oscillate laser luminous fluxes having different wavelengths. Specifically, the laser oscillator 12a oscillates a laser luminous flux having a green wavelength in the range of, for example, a peak wavelength of 500 to 560 nm, preferably 540 nm. The laser oscillator 12b is adapted to oscillate a laser luminous flux having a blue wavelength in the range of, for example, a peak wavelength of 430 to 470 nm, preferably 450 nm. The laser oscillator 12c is adapted to oscillate a laser luminous flux having a red wavelength in the range of, for example, a peak wavelength of 600 to 650 nm, preferably 640 nm. Each laser luminous flux oscillated from each laser oscillator 12a, 12b, 12c is incident on the corresponding condenser lenses 13a, 13b, 13c, respectively.

The three condenser lenses 13a, 13b, 13c are arranged at predetermined intervals in the traveling direction of each laser light beam with respect to the corresponding laser oscillators 12a, 12b, 12c, respectively. Each condenser lens 13a, 13b, 13c is formed of, for example, synthetic resin or glass with translucency, and has positive optical power. Each condenser lens 13a, 13b, 13c concentrates the laser light flux of the corresponding color by refraction so that the beam waist of each laser light beam is located near the screen portion 20, more preferably on the screen portion 20. To adjust.

The folded mirror 14a is arranged with respect to the condenser lens 13a at a predetermined interval in the traveling direction of the laser light beam, and reflects the green laser light beam transmitted through the condenser lens 13a.

The two dichroic mirrors 14b and 14c are arranged at predetermined intervals in the traveling direction of each laser light beam with respect to the corresponding condenser lenses 13b and 13c, respectively. Each of the dichroic mirrors 14b and 14c reflects the laser light flux of a specific wavelength among the laser light fluxes transmitted through the corresponding condenser lenses 13b and 13c, and transmits the other laser light flux. Specifically, the dichroic mirror 14b corresponding to the condenser lens 13b reflects the blue laser light flux and transmits the green laser light beam. The dichroic mirror 14c corresponding to the condenser lens 13c reflects the red laser light flux and transmits the green and blue laser light flux.

Here, the dichroic mirrors 14b are arranged at predetermined intervals in the traveling direction of the green laser light flux after being reflected by the folded mirror 14a. Further, the dichroic mirrors 14c are arranged at predetermined intervals in the traveling direction of the blue laser light flux after being reflected by the dichroic mirror 14b. With these arrangements, the green laser light flux after reflection by the folded mirror 14a passes through the dichroic mirror 14b and is superimposed on the blue laser light flux after reflection by the dichroic mirror 14b. Further, the green laser light flux and the blue laser light flux pass through the dichroic mirror 14c and are superimposed on the red laser light flux after being reflected by the dichroic mirror 14c.

Further, each laser oscillator 12a, 12b, 12c is electrically connected to the controller 17. Each laser oscillator 12a, 12b, 12c oscillates a laser luminous flux according to an electric signal from the controller 17. Then, by adding and mixing the laser light fluxes of three colors oscillated from the laser oscillators 12a, 12b, and 12c, it is possible to reproduce various colors. In this way, the laser projection unit 11 emits laser light fluxes having different wavelengths toward the scanning unit 15 in a superposed state.

The scanning unit 15 has a scanning mirror 16. The scanning mirror 16 is a MEMS mirror configured to be able to scan a laser luminous flux in time by using a Micro Electro Mechanical Systems (MEMS). In the scanning mirror 16, a reflective surface 16a is formed on a surface facing the dichroic mirror 14c at a predetermined distance by metal vapor deposition of aluminum or the like. The reflective surface 16a is rotatable around two rotation axes Ax and Ay that are substantially orthogonal to each other along the reflective surface 16a.

Such a scanning mirror 16 is electrically connected to the controller 17, and can change the direction of the reflecting surface 16a by rotating with the scanning signal. In this way, the scanning unit 15 is controlled by the controller 17 to control the scanning mirror 16, and in conjunction with the laser projection unit 11, for example, the scanning unit 15 is temporally starting from the deflection point TP, which is the incident point of the laser light flux on the reflecting surface 16a. It is possible to deflect the projection direction of the laser luminous flux. The laser luminous flux scanned by the scanning unit 15 due to the deflection at the deflection point TP is incident on the screen unit 20.

The screen unit 20 forms an image when each laser luminous flux is incident, and reflects the laser luminous flux to guide the laser luminous flux to the projection unit 3a side on the optical path as display light of the image. It is a reflective screen member 20a.

The screen portion 20 is formed in a plate shape having a rectangular outer contour, for example, and is extended along the radial direction. In the optical system, the radial direction means a direction that intersects the optical axis direction OAD (that is, is not limited to a direction orthogonal to the optical axis direction OAD), and is a virtual surface that intersects the optical axis direction OAD. It is broadly interpreted to mean any direction above. The optical axis direction OAD in the present embodiment can be defined by the direction indicated by the average value of the projection direction of the laser luminous flux, in other words, the traveling direction of the light ray passing through the center position of the image and the virtual image VRI.

An image is drawn on the projection region PAR extending in the radial direction in the screen unit 20 due to the incident of the laser luminous flux scanned by the scanning unit 15. Specifically, the scanning unit 15 is sequentially scanned along the plurality of scanning lines SL under the control of the controller 17. As a result, the position where the laser luminous flux is incident is moved in the projection region PAR, and the laser luminous flux is intermittently pulsed to draw an image. The image drawn in the projection region PAR is drawn at 60 frames per second, for example, as an image having 720 pixels in the xs direction along the scanning line SL and 240 pixels in the ys direction substantially perpendicular to the scanning line SL. The xs direction corresponds to the left-right direction in the virtual image VRI, and the ys direction corresponds to the vertical direction in the virtual image VRI.

Further, since the surface including the xs direction and the ys direction intersects the optical axis direction OAD, the xs direction and the ys direction, and any direction on the surface including the xs direction and the ys direction are described above. Corresponds to the radial direction.

Here, the laser luminous flux incident on the screen unit 20 is reflected by the light guide characteristic distribution of the screen unit 20 to be described in detail later, and the spread angle is expanded, while the projection unit 3a side on the optical path, more specifically. The light is guided toward the magnified light guide unit 30.

As shown in FIG. 1, the magnifying light guide unit 30 guides the display light from the screen unit 20 to the projection unit 3a of the windshield 3. The magnifying light guide unit 30 has a magnifying mirror 31. The magnifying mirror 31 forms a reflective surface 31a by, for example, metal vapor deposition of aluminum on the surface of a base material made of synthetic resin, glass, or the like. The reflective surface 31a is formed in a concave shape that is curved in a concave shape due to the concave center. Then, the magnifying mirror 31 has a function of expanding the virtual image VRI with respect to the size of the image in the projection region PAR by reflecting the display light from the screen unit 20 to the projection unit 3a.

Further, the magnifying mirror 31 is rotatable around a rotation axis extending in the left-right direction, and the position of the virtual image VRI in the vertical direction can be adjusted.

The display light reflected on the reflecting surface 31a of the magnifying mirror 31 passes through the translucent dustproof sheet 9a arranged at the opening of the housing 9 and is emitted to the outside of the HUD device 100 to the projection unit 3a. Incident. When the display light reflected by the projection unit 3a reaches the occupant's eye point EP, the occupant can visually recognize the virtual image VRI.

Hereinafter, the screen unit 20 of the present embodiment will be described in detail. As shown in FIG. 3, the screen portion 20 is formed in a state where a plurality of wavelength selection units 21r, 21g, 21b are laminated with each other in the thickness direction. In particular, in the present embodiment, the plurality of wavelength selection units 21r, 21g, 21b are provided in three, which corresponds to the wavelength of each laser luminous flux individually and is the same as the number of installed laser oscillators 12a, 12b, 12c. .. The thickness direction of the screen portion 20 of the present embodiment is defined so as to be substantially orthogonal to the virtual surface formed by the radial direction.

Each wavelength selection unit 21r, 21g, 21b is a volume hologram. Each wavelength selection unit 21r, 21g, 21b has a thin plate shape by sandwiching the respective hologram layers 22r, 22g, 22b with a pair of translucent substrate layers 23 made of, for example, synthetic resin or glass and having translucency. Is formed in. The hologram layers 22r, 22g, and 22b are formed in a state in which information on the amplitude and phase of the object light is recorded as interference fringes with the reference light on the hologram material 90 (see also FIG. 14). As the hologram material 90, a material capable of recording amplitude and phase information of object light by modulation of the refractive index, such as a material mainly composed of synthetic resin, a gelatin photosensitive material, or a silver salt photosensitive material, can be selectively adopted. ..

The hologram layers 22r, 22g, 22b of each wavelength selection unit 21r, 21g, 21b have a more substantial interaction than the other wavelengths with respect to a specific wavelength individually corresponding to each wavelength of the laser luminous flux. By having a large wavelength selectivity, it functions as a wavelength selection unit. That is, the hologram layers 22r, 22g, and 22b are different from each other in specific wavelengths having a large substantial interaction. The hologram layer 22r having a specific wavelength as a red wavelength functions as a red wavelength selection unit, and the hologram layer 22g having a specific wavelength as a green wavelength functions as a green wavelength selection unit and has a specific wavelength as a blue wavelength. The hologram layer 22b functions as a blue wavelength selection unit.

Specifically, each of the hologram layers 22r, 22g, and 22b has high diffraction efficiency for a specific wavelength in order to increase the spread angle of the corresponding laser luminous flux of a specific wavelength, and has a radial direction. It has a light guide characteristic distribution that spreads to. In particular, the light guide characteristic distribution of the present embodiment using a volume hologram is for the hologram layers 22r, 22g, and 22b to exert a diffraction action due to interference as a substantial interaction with a laser light beam having a specific wavelength. It means the refractive index distribution in the thickness direction and the radial direction of each hologram layer 22r, 22g, 22b for the specific wavelength.

That is, each of the hologram layers 22r, 22g, and 22b is configured as a reflection type volume hologram, and has a wavelength dependence with high diffraction efficiency due to Bragg reflection. For example, the diffraction efficiency of each hologram layer 22r, 22g, 22b is 80% or more with respect to the corresponding specific wavelength, and 20% or more with respect to a wavelength in the vicinity of the specific wavelength (for example, a specific wavelength ± 5 nm). , Less than 20% or approximately 0% at other wavelengths (see the example of hologram layer 22g in FIG. 4).

The hologram layers 22r, 22g, and 22b are refracted by recording the object light from the same master micromirror array 91, so that the periodic structures having periodicity in the radial direction are refracted in a state where the periods are matched with each other. It has by the rate distribution. More specifically, the periods and periodicities of the hologram layers 22r, 22g, 22b are matched to each other and set substantially the same.

The periodicity of this periodic structure is substantially transferred from the periodicity of the master micromirror array 91 as the master optical element. Therefore, if the master micromirror array 91 has a structure in which rectangular curved mirror elements are arranged along two axes substantially orthogonal to each other, the periodic structure of each hologram layer 22r, 22g, 22b is formed in a rectangular grid pattern. Will be done. If the master micromirror array 91 has a structure in which hexagonal curved mirror elements are spread, the periodic structures of the hologram layers 22r, 22g, and 22b are formed in a hexagonal lattice pattern.

One cycle in this periodic structure is preferably set to about the spot diameter at the beam waist of each laser light flux, for example, in the range of 50 to 200 μm, preferably 100 μm.

The outer contour shape of the cell 24 (see also FIGS. 5-11) that defines one cycle in such a periodic structure functions like a diaphragm with respect to the visible region EB. Therefore, when the periodic structure is a rectangular grid, the shape of the visual recognition region EB formed by expanding the spread angle of the laser luminous flux by the rectangular cell 24 is rectangular, and the periodic structure is a hexagonal grid. In some cases, the shape of the visual recognition area EB formed by expanding the spread angle of the laser luminous flux by the hexagonal cell 24 becomes a hexagonal shape.

The refractive index distribution for a specific wavelength in each cell 24 is formed so that the refractive index modulation interval gradually increases or decreases as the distance from the center positions Cr, Cb, and Cb of each cell 24 increases radially. ..

The plurality of hologram layers 22r, 22g, and 22b are composed of hologram layers in which the extreme value positions (for example, the center positions Cr, Cg, and Cb of the cell 24) that take extreme values in the light guide characteristic distribution are displaced from each other in the radial direction. There are combinations. More specifically, in the plurality of hologram layers 22r, 22g, 22b, there is a combination of hologram layers arranged so as to be out of phase with each other in the periodic structure. In particular, in the present embodiment, in all combinations of the hologram layers 22r, 22g, and 22b, the phases in the periodic structure are arranged so as to be offset from each other. That is, even in the combination of the hologram layer 22r corresponding to the red wavelength and the hologram layer 22g corresponding to the green wavelength, the phases in the periodic structure are out of phase with each other.

As a result, the emission display positions in which the images are formed and displayed as a virtual image VRI are within a range smaller than one cycle of the periodic structure between the wavelengths of the plurality of laser luminous fluxes, and the diameters of each other are increased according to the phase shift. It will be shifted in the direction. As shown in FIG. 12 for reference, since the emission points Br, Bg, and Bb as the emission display positions of the virtual image VRI shift for each wavelength of the laser luminous flux, the generation of gaps between the emission points Br, Bg, and Bb is suppressed. ..

Hereinafter, details of the periodic structure and the phase shift recognized as variations of the first embodiment will be illustrated in Examples 1 to 7. In each embodiment, the hologram layer 22g having the green wavelength having the highest relative visibility as a specific wavelength among the laser beams is used as a reference wavelength selection unit, and the hologram layers 22r and 22b are used as other wavelength selection units. It is explained as.

<Example 1>
The periodic structure of Example 1 shown in FIG. 5 is formed in a rectangular grid pattern. In FIG. 5, the cell 24 in the periodic structure of the hologram layer 22 g as the reference wavelength selection part is shown by a broken line. The center position Cg of each cell 24 of the hologram layer 22 g is indicated by a circular marker. A vector from the center position Cg of any cell 24 of the hologram layer 22g toward the center position Cg of the cell 24 adjacent in the xs direction is defined as Px = (x, 0). A vector from the center position Cg of any cell 24 of the hologram layer 22g toward the center position Cg of the cell 24 adjacent in the ys direction is defined as Py = (0, y). These vectors Px and Py can be called the fundamental translation vectors in this periodic structure of the real space formed by the radial direction.

In FIG. 5, the illustration of the cell 24 in the periodic structure of the hologram layers 22r and 22b is omitted. On the other hand, the center position Cr of each cell 24 of the hologram layer 22r is indicated by a rectangular marker, and the center position Cb of each cell of the hologram layer 22b is indicated by a triangular marker. Anyone can measure and know the arrangement of each cell 24 from the marker illustration of the center positions Cr and Cb.

In Example 1, the vector component indicating the phase difference of the periodic structure of the hologram layer 22r with respect to the hologram layer 22g is (−x / 3, + y / 3). The vector component indicating the phase difference of the periodic structure of the hologram layer 22b with respect to the hologram layer 22g is (+ x / 3, + y / 3). Therefore, the hologram layers 22r, 22g, and 22b are deviated by 1/3 cycle in the xs direction and the ys direction, respectively, so that they are deviated in the xs direction and the ys direction at an angle of 45 degrees. The phase shift of the periodic structure of each hologram layer 22r, 22b is smaller than 1/2 cycle in each direction of the basic translation vector with respect to the periodic structure of the reference hologram layer 22g.

<Example 2>
The periodic structure of Example 2 shown in FIG. 6 is also formed in a rectangular lattice shape as in Example 1. Therefore, the vectors Px and Py are also defined in the same manner as in the first embodiment.

In Example 2, the component of the vector indicating the phase difference of the periodic structure of the hologram layer 22r with respect to the hologram layer 22g is (−x / 3,0). The vector component indicating the phase difference of the periodic structure of the hologram layer 22b with respect to the hologram layer 22g is (+ x / 3,0). Therefore, the hologram layers 22r, 22g, and 22b are deviated by 1/3 cycle only in the xs direction. The phase shift of the periodic structure of each hologram layer 22r, 22b is smaller than 1/2 cycle in each direction of the basic translation vector with respect to the periodic structure of the reference hologram layer 22g.

<Example 3>
The periodic structure of Example 3 shown in FIG. 7 is also formed in a rectangular lattice shape as in Example 1. Therefore, the vectors Px and Py are also defined in the same manner as in the first embodiment.

In Example 3, the vector component indicating the phase difference of the periodic structure of the hologram layer 22r with respect to the hologram layer 22g is (0, + y / 3). The vector component indicating the phase difference of the periodic structure of the hologram layer 22b with respect to the hologram layer 22g is (0, −y / 3). Therefore, the hologram layers 22r, 22g, and 22b are deviated by 1/3 cycle only in the ys direction. The phase shift of the periodic structure of each hologram layer 22r, 22b is smaller than 1/2 cycle in each direction of the basic translation vector with respect to the periodic structure of the reference hologram layer 22g.

<Example 4>
The periodic structure of Example 4 shown in FIG. 8 is also formed in a rectangular lattice shape as in Example 1. Therefore, the vectors Px and Py are also defined in the same manner as in the first embodiment.

In Example 4, the vector component indicating the phase difference of the periodic structure of the hologram layer 22r with respect to the hologram layer 22g is (0, + y / 2). The vector component indicating the phase difference of the periodic structure of the hologram layer 22b with respect to the hologram layer 22g is (+ x / 2, −y / 4). Therefore, the hologram layer 22r and the hologram layer 22g are deviated by 1/2 cycle in the ys direction. At the same time, the hologram layer 22g and the hologram layer 22b are displaced in an oblique direction forming an angle of 30 degrees with respect to the xs direction.

In the fourth embodiment, there are hologram layers 22r and 22b in which a phase shift of 1/2 cycle or more occurs in any direction of the basic translation vector with respect to the periodic structure of the reference hologram layer 22g.

<Example 5>
The periodic structure of Example 5 shown in FIG. 9 is also formed in a rectangular lattice shape as in Example 1. Therefore, the vectors Px and Py are also defined in the same manner as in the first embodiment.

In Example 5, the vector component indicating the phase difference of the periodic structure of the hologram layer 22r with respect to the hologram layer 22g is (+ x / 2,0). The vector component indicating the phase difference of the periodic structure of the hologram layer 22b with respect to the hologram layer 22g is (+ x / 4, + y / 2). Therefore, the hologram layer 22r and the hologram layer 22g are deviated by 1/2 cycle in the xs direction. At the same time, the hologram layer 22g and the hologram layer 22b are displaced in an oblique direction forming an angle of 30 degrees with respect to the ys direction.

In the fifth embodiment, there are hologram layers 22r and 22b in which a phase shift of 1/2 cycle or more occurs in any direction of the basic translation vector with respect to the periodic structure of the reference hologram layer 22g.

<Example 6>
The periodic structure of Example 6 shown in FIG. 10 is also formed in a rectangular lattice shape as in Example 1. In FIG. 10, the periodic structures of the hologram layers 22r, 22g, and 22b are arranged in phase with each other so as to draw an equilateral triangle in the radial direction.

<Example 7>
The periodic structure of Example 7 shown in FIG. 11 is formed in a hexagonal lattice pattern. In this structure, the two basic translation vectors Pa and Pb from the center position Cg of any cell 24 of the hologram layer 22g toward the center position Cg of each cell 24 adjacent in the xs direction form an angle of 60 degrees with each other. Can be defined.

At this time, the vector showing the phase difference of the periodic structure of the hologram layer 22r with respect to the hologram layer 22g can be expressed as + 1/3 (Pa-Pb). The vector indicating the phase difference of the periodic structure of the hologram layer 22b with respect to the hologram layer 22g can be expressed as -1/3 (Pa-Pb). By setting the phase shift in this way, the three hologram layers 22r, 22g, and 22b can be dispersed substantially uniformly.

The cells 24 and the center positions Cr, Cg, and Cb shown in FIGS. 5 to 11 are only partially marked with reference numerals.

Hereinafter, a method of manufacturing the screen member 20a of the first embodiment will be described with reference to the flowchart of FIG.

First, in the material preparation step S11, among a plurality of wavelengths discrete from each other, a plurality of thin plate-shaped hologram materials 90 having exposure sensitivity to light of a specific wavelength and having different specific wavelengths from each other are prepared. .. In particular, in the present embodiment, three hologram materials 90 corresponding to the wavelength of each laser luminous flux are prepared. Each hologram material 90 is prepared in a form corresponding to a single wavelength selection unit sandwiched between the translucent substrate layers 23.

Next, in the exposure step S12, each hologram material 90 is sequentially replaced by light having a specific wavelength corresponding to each hologram material 90, and exposed at the same position. Specifically, as shown in FIG. 14, the master micromirror array 91 is installed at an actual installation angle, and a laser light source can be irradiated so that the laser light flux can be irradiated from the position corresponding to the deflection point TP of the actual scanning mirror 16. 92 is installed. Then, one of the three hologram materials 90 is arranged in the vicinity of the master micromirror array 91. Then, for example, a laser light flux having a red wavelength is irradiated from the laser light source 92.

In this way, the light that passes through the hologram material 90 from the laser luminous flux can be used as the reference light. Further, the light reflected by the master micromirror array 91 and transmitted through the hologram material 90 from the side opposite to the reference light can be used as the object light. Then, as described above, the amplitude and phase information of the object light can be recorded on the hologram material 90 as interference fringes with the reference light. This completes the exposure of the first hologram material 90.

The first hologram material 90 that has been exposed is removed, the second hologram material 90 is placed at the same position, and a laser beam of green wavelength is irradiated to expose the second hologram material 90. Complete. Further, the same exposure is performed for the third hologram material 90.

Next, in the shift laminating step S13, the hologram materials 90 are laminated by shifting each other in the radial direction based on the exposed position. In practice, the wavelength selection units 21r, 21g, 21b are laminated with a shift direction and a shift amount corresponding to a desired phase shift as selectively carried out in Examples 1 to 7. Since the phase between the periodic structures may be out of phase, the amount of shift may not be smaller than one cycle of the periodic structure, and may be a value obtained by adding n cycles to the phase difference. Here, n is a natural number. From the above, the screen member 20a is completed.

(Action effect)
The effects of the first embodiment described above will be described again below.

According to the HUD apparatus 100 of the first embodiment, in the combination of wavelength selection units having large interactions and different specific wavelengths from each other, the extreme value positions of the light guide characteristic distribution of the wavelength selection unit are arranged so as to be displaced in the radial direction. ing. Therefore, in the screen unit 20 in which the light source light including a plurality of wavelengths is incident, the spreading characteristics of the light source light of different wavelengths in this combination are shifted in the radial direction from each other. Therefore, when an observer whose eyes are located in a part of the viewing area EB visually recognizes the virtual image VRI, the light emitting positions are visually recognized as if they are displaced in the radial direction without completely overlapping with each other at different wavelengths. be able to. Therefore, it is possible to prevent the emission positions from being dispersed among a plurality of wavelengths and the portion that does not appear to emit light from being unintentionally generated. As described above, it is possible to provide the HUD device 100 having good visibility of the virtual image VRI.

Further, according to the HUD apparatus 100 of the first embodiment, in the combination of wavelength selection units having large interactions and different wavelengths from each other, the phases of the wavelength selection units in the periodic structure are shifted. Therefore, in the screen unit 20 in which the light source light including a plurality of wavelengths is incident, the spreading characteristics of the light source light of different wavelengths in this combination are shifted in the radial direction from each other. Therefore, when an observer whose eyes are located in a part of the viewing area EB visually recognizes the virtual image VRI, the emission positions that can be arranged periodically are slightly different in the radial direction between the light sources having different wavelengths in the above combination. It is visually displaced. Therefore, the emission positions are dispersed among a plurality of wavelengths, and the presence of gaps that do not appear to emit light is suppressed. As described above, the graininess of the virtual image VRI can be reduced, and the HUD device 100 having good visibility of the virtual image VRI can be provided.

Further, according to the first embodiment, in the combination of the red wavelength selection unit and the green wavelength selection unit, the phases of the wavelength selection unit in the periodic structure are arranged out of phase. Since the emission position can be shifted in the radial direction between the red wavelength and the green wavelength, which have relatively high luminous efficiency, a virtual image can be displayed, so that the part that does not seem to emit light can be effectively suppressed. , The effect of reducing the graininess of the virtual image VRI can be enhanced.

Further, according to the first embodiment, the phase shift of all the other wavelength selection units is 1/2 period in each direction along each basic translation vector with respect to the periodic structure of the reference wavelength selection unit. It is disclosed that it is set smaller than. With such a setting, since the virtual image is displayed as if the light emitting position is shifted inside one cell 24, it is possible to suppress the situation where the light emitting position is displayed straddling the pixels of the image, and color bleeding can be suppressed. It can make it difficult to feel. Therefore, the visibility of the virtual image VRI can be improved.

Further, according to the first embodiment, the phase shift is set to 1/2 cycle or more in any direction along each basic translation vector with respect to the periodic structure of the reference wavelength selection unit. Is disclosed. With such a setting, since the light emitting position is shifted so as to protrude from one cell 24 and a virtual image is displayed, it is possible to suppress the occurrence of a gap portion between the cells 24. Therefore, the light emitting positions are more uniformly dispersed, and the effect of reducing the graininess of the virtual image VRI can be enhanced.

Further, according to the first embodiment, the viewing area EB can be formed in a rectangular shape by forming the periodic structure of the wavelength selection unit into a rectangular grid shape, so that both eyes of the observer can be easily accommodated in the viewing area EB. It is possible to improve the visibility of the virtual image VRI.

Further, according to the first embodiment, by forming the periodic structure of the wavelength selection unit into a hexagonal lattice pattern, when the three primary colors of light are adopted for a plurality of wavelengths, light is emitted in the periodic structure of the three wavelength selection units. Since it becomes easy to realize a phase shift for uniformly distributing the positions, the graininess of the virtual image VRI can be further reduced.

Further, according to the first embodiment, each wavelength selection unit is a volume hologram having a refractive index distribution in the thickness direction and the radial direction. By adopting the volume hologram, the refractive index distribution can be given in the thickness direction as well, and the wavelength selectivity of the peaky diffraction efficiency for a specific wavelength can be easily realized.

Further, according to the screen member 20a of the first embodiment, in the combination of wavelength selection units having large interactions and different wavelengths from each other, the phases of the wavelength selection units in the periodic structure are shifted. Therefore, in the screen member 20a in which the light source light including a plurality of wavelengths is incident, the spreading characteristics of the light source light of different wavelengths in this combination are shifted in the radial direction from each other. Therefore, when the observer visually recognizes the image displayed by using the screen member 20a, the emission positions that can be arranged periodically may be visually recognized with a slight radial deviation between the light sources of different wavelengths of the above combination. .. Therefore, the emission positions are dispersed among a plurality of wavelengths, and the presence of gaps that do not appear to emit light is suppressed. As described above, it is possible to reduce the graininess in the image display, and it is possible to provide the screen member 20a capable of displaying the image with good visibility.

Further, according to the method for manufacturing the screen member 20a of the first embodiment, a plurality of hologram materials 90 corresponding to each wavelength are exposed and then laminated so as to be displaced from each other in the radial direction. By such a staggered stacking, in the light guide characteristic distribution of each wavelength due to the interference fringes recorded on the hologram material 90, the extreme value position can be shifted in the radial direction between each wavelength. As a result, when the observer visually recognizes the image displayed by using the screen member 20a, the light emitting positions can be visually recognized as if they are displaced in the radial direction without completely overlapping each other at different wavelengths. Therefore, it is possible to prevent the emission positions from being dispersed among a plurality of wavelengths and the portion that does not appear to emit light from being unintentionally generated. Therefore, the screen member 20a capable of displaying an image with good visibility can be manufactured.

(Second Embodiment)
As shown in FIGS. 15 and 16, the second embodiment is a modification of the first embodiment. The second embodiment will be described focusing on the differences from the first embodiment.

The screen unit 220 of the second embodiment is a reflective screen member 220a as in the first embodiment. However, as shown in FIG. 15, the screen unit 220 of the second embodiment is not a stack of a plurality of wavelength selection units 21r, 21g, 21b, but a pair of one-layer hologram layers 222 having translucency. It is formed in a thin plate shape by being sandwiched by the translucent substrate layer 23 of the above.

The hologram layer 222 is formed in a state in which information on the amplitude and phase of the object light is recorded as interference fringes with the reference light on the hologram material 90 by multiple exposure with the wavelength of each laser luminous flux. Therefore, since the hologram layer 222 corresponds to the wavelengths of all the laser light fluxes, it functions as a red wavelength selection unit, a green wavelength selection unit, and further functions as a blue wavelength selection unit. That is, the function of each wavelength selection unit is shared by the hologram layer 222 of one layer.

Hereinafter, a method of manufacturing the screen member 220a of the second embodiment will be described with reference to the flowchart of FIG.

First, in the material preparation step S21, a thin plate-shaped hologram material 90 having exposure sensitivity to light of a plurality of wavelengths discrete from each other is prepared. In particular, in the present embodiment, one hologram material 90 corresponding to the wavelength of each laser luminous flux is prepared. The hologram material 90 is prepared in a form sandwiched between the translucent substrate layers 23.

Next, in the pre-stage exposure step S22, the hologram material 90 is exposed with light having one wavelength out of a plurality of wavelengths. Specifically, as in the exposure step S12 of the first embodiment, the master micromirror array 91 can be installed at an actual installation angle, and the laser light beam can be irradiated from a position corresponding to the deflection point TP of the actual scanning mirror 16. As described above, the laser light source 92 is installed. Then, the hologram material 90 is arranged in the vicinity of the master micromirror array 91. Then, for example, a laser light flux having a red wavelength is irradiated from the laser light source 92.

Then, with respect to the red wavelength, information on the amplitude and phase of the object light can be recorded on the hologram material 90 as interference fringes with the reference light. This completes the exposure of the hologram material 90 with the first wavelength.

Next, in the first shift step S23, the hologram material 90 is shifted in the radial direction. In practice, the hologram material 90 is moved in a shift direction and shift amount corresponding to a desired phase shift as selectively carried out in Examples 1 to 7 of the first embodiment. The shift amount does not have to be smaller than one cycle of the periodic structure, and may be a value obtained by adding n cycles to the phase difference. Here, n is a natural number.

Next, in the first post-stage exposure step S24, the hologram material 90 is exposed with light having one wavelength different from the wavelength already exposed among the plurality of wavelengths. For example, a laser luminous flux having a green wavelength is emitted from the laser light source 92. This completes the exposure of the hologram material 90 with the second wavelength.

Next, in the second shifting step S25, the hologram material 90 is shifted in the radial direction in the same manner as in the first shifting step S23. At this time, it is preferable to shift the position of the hologram material 90 to another position instead of returning it to the position in the previous exposure step S22.

Next, in the second post-stage exposure step S26, similarly to the first post-stage exposure step S24, the hologram material 90 is exposed with light having one wavelength different from the wavelength already exposed among the plurality of wavelengths. For example, a laser luminous flux having a blue wavelength is emitted from the laser light source 92. This completes the exposure of the hologram material 90 with the third wavelength. As a result, the multiple exposure is completed, and the screen member 220a is completed.

According to the second embodiment described above, the hologram material 90 is displaced in the radial direction to perform exposure at each wavelength. By such multiple exposure, in the light guide characteristic distribution of each wavelength due to the interference fringes recorded on the hologram material 90, the extreme value position can be shifted in the radial direction between each wavelength. As a result, when the observer visually recognizes the image displayed by using the screen member 220a, the light emitting positions can be visually recognized as if they are displaced in the radial direction without completely overlapping each other at different wavelengths. Therefore, it is possible to prevent the emission positions from being dispersed among a plurality of wavelengths and the portion that does not appear to emit light from being unintentionally generated. Therefore, the screen member 220a capable of displaying an image with good visibility can be manufactured.

(Third Embodiment)
As shown in FIGS. 17 to 20, the third embodiment is a modification of the first embodiment or the second embodiment. The third embodiment will be described focusing on the differences from the first embodiment.

As shown in FIG. 17, unlike the first embodiment, the screen unit 320 of the third embodiment is a transmissive screen member 320a. That is, the screen unit 320 guides the incident laser light beam to the projection unit side on the optical path, more specifically to the magnified light guide unit 30, while transmitting and expanding the spread angle.

Hereinafter, a method of manufacturing the screen member 320a of the first embodiment will be described with reference to the flowchart of FIG.

First, in the master hologram creating step S31, as shown in FIG. 19, the reflection having the same configuration as the screen portions 20 and 220 is used by using the manufacturing method of the screen portions 20 and 220 of the first embodiment or the second embodiment. Create a master hologram 93 of the mold. However, the master hologram 93 corresponds to the "hologram material" in the manufacturing method of the screen portions 20, 220 of the first embodiment or the second embodiment.

Next, in the transmission type hologram creation step S32, a transmission type hologram is created using the reflection type master hologram 93. Specifically, as shown in FIG. 20, the real image of the master hologram 93 is obtained by injecting the conjugate wave of the laser luminous flux irradiated at the time of creating the master hologram 93 into the master hologram 93 as irradiation light using the laser light source 92. Reproduce. Here, the conjugated wave means a reverse traveling wave of the reference light at the time of creating the master hologram 93.

Then, the hologram material 90 is arranged at the reproduction position of the real image of the master hologram 93. That is, the light reflected by the master hologram 93 (hereinafter referred to as regenerated light) is incident on the hologram material 90. At the same time, a part of the irradiation light from the laser light source 92 is incident on the master hologram 93 from the same side as the incident of the reproduced light by using the reference light mirror 94.

As a result, the reproduced light can be used as the object light, and the irradiation light reflected by the reference light mirror 94 can be used as the reference light. Information on the amplitude and phase of the object light can be recorded on the hologram material 90 as interference fringes with the reference light. As a result, the exposure of the hologram material 90 is completed, and the transmissive screen member 320a is completed.

(Other embodiments)
Although the plurality of embodiments have been described above, the present disclosure is not construed as being limited to those embodiments, and is to be applied to various embodiments and combinations without departing from the gist of the present disclosure. Can be done.

Specifically, as a modification 1, an optical element such as a lens may be added between the scanning unit 15 and the screen unit 20.

As a modification 2 of the first embodiment, the wavelength selection units 21r, 21g, and 21b may not form an integral screen member 20a, and may be arranged apart from each other.

As a modification 3 regarding the first embodiment, the wavelength selection unit 21g and the wavelength selection unit 21b may be grouped together in a common wavelength selection unit as in the second embodiment. That is, the function of the green wavelength selection unit and the function of the blue wavelength selection unit may be shared by one hologram layer.

As a modification 4, in a rectangular grid-like or hexagonal grid-like periodic structure, a flat cell 24 may be formed so that the dimension in the ys direction is longer than the dimension in the xs direction, for example.

As a modification 5, the period of the periodic structure may be slightly modulated.

As a modification 6, the hologram layers 22r, 22g, 22b, and 222 have an aperiodic structure by recording interference fringes in which optical elements in which curved mirror elements are randomly arranged are used as object light. You may.

As the modification 7, a hologram having a refractive index distribution only in the radial direction may be adopted as the wavelength selection unit instead of the volume hologram, and a diffraction grating may be adopted as an example other than the hologram.

As a modification 8, in all combinations of wavelength selection units, the phases in the periodic structure may not be arranged so as to be offset from each other. That is, there may be a combination of wavelength selection units whose phases match each other in the periodic structure.

As a modification 9, in the light source light emitted by the light source unit 10, the plurality of wavelengths discrete from each other may be two wavelengths or four or more wavelengths.

As a modification 10 according to the third embodiment, the hologram material 90 may be shifted in the transmission type hologram creating step S32 without shifting the master hologram 93 in the master hologram creating step S31.

As a modification 11, the virtual image display device can be applied to various vehicles such as an aircraft, a ship, or a non-moving housing (for example, a game housing).

100 HUD device (virtual image display device), 3a projection unit, 10 light source unit, 20, 220, 320 screen unit, 20a, 220a, 320a screen member, 22r, 22g, 22b, 222 hologram layer (wavelength selection unit), 90 hologram Material, S11 Material preparation process, S12 exposure process, S13 shift laminating process, S21 material preparation process, S22 pre-stage exposure process, S23 first shift process (shift process), S24 first post-stage exposure process (post-stage exposure process), S25 first 2 Shifting step (shifting step), S26 second second stage exposure step (second stage exposure step), Cr, Cg, Cb center position (extreme value position)

Claims (12)

A virtual image display device that visually displays a virtual image by projecting an image onto a projection unit (3a).
A light source unit (10) that emits light source light containing a plurality of wavelengths,
The image is formed by incident light sources having a plurality of wavelengths, and a screen unit (20, 220, 320) that guides the light source light to the projection unit side is provided.
The screen portion has a wavelength selectivity that interacts with a specific wavelength among the plurality of wavelengths more than other wavelengths, and has a radial light guide characteristic distribution that expands the spread angle of the light source light. It has a plurality of wavelength selection units (22r, 22g, 22b, 222) having a plurality of wavelength selection units (22r, 22g, 22b, 222).
In the plurality of wavelength selection units, the specific wavelengths are different from each other, and the extreme value positions (Cr, Cg, Cb) having extreme values in the light guide characteristic distribution are arranged so as to be shifted in the radial direction. A virtual image display device in which the combination of the wavelength selection units is present. A virtual image display device that visually displays a virtual image by projecting an image onto a projection unit (3a).
A light source unit (10) that emits light source light containing a plurality of wavelengths,
The image is formed by incident light sources having a plurality of wavelengths, and a screen unit (20) that guides the light source light to the projection unit side is provided.
The screen portion has a wavelength selectivity with a larger interaction than other wavelengths with respect to a specific wavelength among the plurality of wavelengths, and has a radial periodic structure that expands the spread angle of the light source light. It has a plurality of wavelength selection units (22r, 22g, 22b, 222).
In the plurality of wavelength selection units, the specific wavelengths are different from each other, the periods of the periodic structure are set to match each other, and the phases of the periodic structure are staggered. A virtual image display device in which the combination of the wavelength selection units is present. The combination according to claim 2, wherein the combination includes a combination of a red wavelength selection unit having the specific wavelength as a red wavelength and a green wavelength selection unit having the specific wavelength as a green wavelength. Virtual image display device. The wavelength selection unit in which a plurality of the wavelength selection units are compared and the wavelength having the highest relative visibility is the specific wavelength is defined as a reference wavelength selection unit, and the wavelength other than the reference wavelength selection unit is defined. When the selection unit is defined as another wavelength selection unit and two basic translational vectors representing one period in the periodic structure are defined,
With respect to the periodic structure of the reference wavelength selection unit, the phase shifts of all the other wavelength selection units are set to be smaller than 1/2 period in each direction along each basic translation vector. The virtual image display device according to claim 2 or 3. The wavelength selection unit in which a plurality of the wavelength selection units are compared and the wavelength having the highest relative visibility is the specific wavelength is defined as a reference wavelength selection unit, and the wavelength other than the reference wavelength selection unit is defined. When the selection unit is defined as another wavelength selection unit and two basic translational vectors representing one period in the periodic structure are defined,
The other wavelength selection unit whose phase shift is set to 1/2 period or more in any direction along each basic translation vector with respect to the periodic structure of the reference wavelength selection unit , The virtual image display device according to claim 2 or 3, which is present. The virtual image display device according to any one of claims 2 to 5, wherein the periodic structure is formed in a rectangular grid pattern. The virtual image display device according to any one of claims 2 to 5, wherein the periodic structure is formed in a hexagonal lattice pattern. The virtual image display device according to any one of claims 1 to 7, wherein each wavelength selection unit is a volume hologram having a refractive index distribution in the radial direction and the thickness direction. 6. Virtual image display device. A screen member that forms an image by projecting light.
A wavelength selection unit (22r, 22g, 22b, 222) having a wavelength selectivity with a larger interaction than other wavelengths with respect to a specific wavelength and having a radial periodic structure that expands the spreading angle of the light. ),
Among the plurality of wavelength selection units, the specific wavelengths are different from each other, the periods of the periodic structure are set to match each other, and the phase of the periodic structure is shifted in the radial direction. A screen member in which the combination of the wavelength selection units arranged in the above is present. A method for manufacturing screen members (220a, 320a) that form an image by projecting light.
A material preparation step (S21) for preparing a plate-shaped hologram material (90) having exposure sensitivity to light of a plurality of wavelengths discrete with each other, and
The pre-exposure step (S22) of exposing the hologram material with light having one wavelength out of the plurality of wavelengths.
After the pre-exposure step, the hologram material is shifted in the radial direction intersecting the optical axis of the light (S23, S25).
After the shift step, the screen member includes a post-stage exposure step (S24, S26) of exposing the hologram material with light having one wavelength different from the wavelength already exposed among the plurality of wavelengths. Production method. A method for manufacturing a screen member (20a, 320a) that forms an image by projecting light.
A material preparation step (S11) for preparing a plurality of plate-shaped hologram materials (90) having exposure sensitivity to light of a specific wavelength among a plurality of wavelengths discrete with each other and having the specific wavelengths different from each other. )When,
An exposure step (S12) in which each hologram material is sequentially replaced and exposed at the same position by light of the specific wavelength corresponding to each hologram material individually.
A method for manufacturing a screen member, comprising a staggered laminating step (S13) of staggering and laminating the hologram materials in a radial direction intersecting the optical axis of the light after the exposure step.

Images