JP2023008930A - head-up display device - Google Patents

Abstract

To provide a head-up display device that can be miniaturized and allows one to simultaneously and clearly see multiple virtual images having different senses of distance.SOLUTION: A head-up display device 10 is composed of: a holographic projector part 10a that irradiates a hologram created such that each of multiple predetermined images is projected to a different, predetermined position with parallel light and emits diffracted light based on interference information of the hologram; a second half mirror 30 that is provided aslope while the diffracted light is applied and transmitted; and recursive reflection sheets 32a, 32b disposed in positions separated by predetermined distance from one surface side of the second half mirror 30 such that a projection image corresponding to each of the predetermined images is projected by irradiation of the diffracted light transmitted through the second half mirror 30 when seen from the one surface side of the second half mirror 30. The projection image projected to each of the recursive reflection sheets 32a, 32b is seen as a virtual image having a different sense of distance to the other surface side of the second half mirror 30.SELECTED DRAWING: Figure 1

Description

The present invention relates to a head-up display device.

2. Description of the Related Art A head-up display device is used in various devices, with which an operator can know information necessary for operation without changing his or her line of sight. For example, in Patent Document 1 below, as a vehicle display device, display patterns displayed on each of two display devices can be seen as virtual images at different positions through the windshield, at a predetermined distance from the windshield. It is described that a display device is installed at a position with a different distance from the half mirror surface on each of both surface sides of the half mirror installed at a distant place. Further, Japanese Patent Application Laid-Open No. 2002-200001 describes an image display unit and a display device from the image display unit, which is used in a game machine such as a pachinko machine, so that a virtual display image is formed in a space in front of a main body frame under predetermined game conditions. A game machine provided with a half mirror for reflecting a projected image toward the rear side of the game machine and a retroreflecting member for retroreflecting the reflected image reflected by the half mirror toward the half mirror. there is Further, Patent Document 2 states that the size, position, etc. of the virtual display image can be changed by providing a distance adjustment mechanism that adjusts the relative distance of the half mirror or the retroreflection member to the image display unit. Have been described.

Japanese Utility Model Laid-Open No. 63-164038 Japanese Patent Application Laid-Open No. 2020-18486

According to the head-up display devices described in Patent Literatures 1 and 2 mentioned above, the driver or the player, while driving or playing a game, can see information necessary for driving or that a predetermined game condition has been reached. You can know without changing.
However, according to the apparatus of Patent Document 1, a display device must be provided for each piece of information to be displayed, which increases the size of the apparatus. Moreover, when trying to display a large amount of information, a large number of display devices are required, making practical use difficult. Further, according to the apparatus of Patent Document 2, when adjusting the relative distance of the half mirror or the retroreflective member to the image display section, the virtual display image may become unclear unless the image display section is adjusted.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. It is an object of the present invention to provide a display device.

A head-up display device according to the present invention, which has been made to achieve the above object, irradiates parallel light onto a hologram created so that each of a plurality of predetermined images is projected at different predetermined positions, and A holographic projector unit that emits diffracted light diffracted based on interference information, a half mirror that is installed at an angle and transmits the diffracted light that is irradiated, and a predetermined distance away from one surface side of the half mirror. A single retroreflective element placed at the predetermined position where the diffracted light transmitted through the half mirror is irradiated and projection images corresponding to the predetermined images are projected, or they overlap each other and a plurality of retroreflecting elements arranged without any part, and the retroreflecting element reflects the retroreflected light of the projected image emitted from the retroreflected light exit surface thereof by the half mirror. , the retroreflective light exit surface is installed facing one side of the half mirror so that it can be seen as a virtual image on the other side of the half mirror, and the one retroreflective element or the plurality of retroreflective elements are installed. At least one retroreflective element among the reflective elements is movably provided at a corresponding projection position of the predetermined image, or all of the plurality of retroreflective elements or the movably provided retroreflective element Each of the remaining retroreflective elements other than the reflective element is characterized in that it is arranged at the projection position of the corresponding predetermined image.

Each of the retroreflective elements is arranged at the projection position corresponding to each of the predetermined images so that all virtual images corresponding to the plurality of predetermined images can be seen at the same time when viewed from one side of the half mirror. Therefore, clear virtual images of a plurality of predetermined images can be viewed at the same time.

The distance of the retroreflective element corresponding to each of the virtual images from the one surface of the half mirror is adjusted so that each of the virtual images can be seen at different distances from the other surface of the half mirror. , at the same time, distinct virtual images of a plurality of predetermined images can be seen at different positions.

The hologram is a computer-generated hologram, and a spatial light modulator that modulates the parallel light into diffracted light based on the interference information of the computer-generated hologram is provided, so that a desired hologram can be easily created. .

に基づいて計算されていることにより、振幅ホログラムの計算速度を高めることができる。 The computer-generated hologram is an amplitude hologram, and the amplitude hologram is represented by the following formula (1)

can speed up the calculation of the amplitude hologram.

に基づいて計算されていることにより、位相ホログラムの計算速度を高めることができる。 The computer-generated hologram is a phase hologram, and the phase hologram is represented by the following formula (2)

can increase the calculation speed of the phase hologram.

A bright virtual image can be formed by using laser light as the parallel light.

The head-up display device according to the present invention uses a holographic projector unit capable of simultaneously projecting a plurality of projection images at respective predetermined positions as a display device, so that the size of the device can be reduced, and at the same time, a plurality of images with different senses of distance can be displayed. You can clearly see the virtual image of Further, by moving the movably provided retroreflective element to a predetermined position where the projection image is projected, it is possible to clearly see different virtual images or virtual images with different perspectives.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram explaining the head-up display apparatus to which this invention is applied. FIG. 3 is a perspective view illustrating an installation state of a retroreflective sheet used in the head-up display device to which the invention is applied; FIG. 5 is a schematic diagram illustrating how a virtual image looks when a light blocking object is placed on the other side of the second half mirror that constitutes the head-up display device to which the present invention is applied; FIG. 11 is a schematic diagram illustrating another head-up display device to which the present invention is applied; FIG. 11 is a schematic diagram illustrating another head-up display device to which the present invention is applied; FIG. 11 is a schematic diagram illustrating another head-up display device to which the present invention is applied; FIG. 11 is a perspective view illustrating an installation state of a retroreflective sheet used in another head-up display device to which the present invention is applied; It is a conceptual diagram for explaining the principle of creating a computer-generated hologram. FIG. 4 is a schematic diagram illustrating the configuration of a CGH calculator that calculates an amplitude hologram; Pseudocode to compute the amplitude hologram. Fig. 4 is a flow chart for computing amplitude holograms; FIG. 4 is a schematic diagram illustrating the configuration of a CGH calculator that calculates a phase hologram; Pseudocode to compute the phase hologram. Fig. 4 is a flow chart for computing a phase hologram; FIG. 15(a) is another pseudocode to compute the amplitude hologram and FIG. 15(b) is another pseudocode to compute the phase hologram.

Although the present invention will be described in detail below, the scope of the present invention is not limited thereto.

A head-up display device to which the present invention is applied is shown in FIG. A head-up display device 10 shown in FIG. 1A is composed of a holographic projector section 10a and a projection section 10b. The holographic projector section 10a is composed of a personal computer (PC) 12 to which a tablet terminal device 11 is connected, a reflective spatial light modulator (SLM) 14, a first half mirror 22, and a parallel light emitting section 15. . The parallel light emitting section 15 is composed of a laser light emitting section 16 , an objective lens 18 and a plano-convex lens 20 . In the holographic projector unit 10 a , a computer-generated hologram (CGH) of a predetermined image such as characters and figures input from the tablet terminal device 11 is calculated by the CGH calculation unit 17 of the PC 12 and displayed on the SLM 14 . The interference fringes displayed on the SLM 14 are interference information created so that a given image is formed at a given position. Parallel light is applied to the display surface of the SLM 14 on which such interference fringes are displayed. This parallel light is emitted from the laser light emitting portion 16 of the parallel light emitting portion 15. After being condensed once by the objective lens 18, the parallel light spreads, becomes parallel light by the plano-convex lens 20, and reaches the SLM 14 by the first half mirror 22. It is the light reflected in the direction of the display surface. The parallel light irradiated to the display surface of the SLM 14 becomes diffracted light based on the interference information of the hologram displayed on the display surface, emerges from the display surface of the SLM 14, and passes through the first half mirror 22. Then, the light is emitted to the projection unit 10b.

The projection unit 10b includes a mirror 24 and a second half mirror 30, which are arranged at an inclination angle of 45°, and a retroreflective element arranged on one surface side (inclined surface side) of the second half mirror 30. It is composed of retroreflective sheets 32a and 32b. The retroreflective sheet 32 a is arranged on the lower end side of the inclined surface of the second half mirror 30 , and the retroreflective sheet 32 b is arranged on the upper end side of the inclined surface of the second half mirror 30 . The retroreflection sheets 32a and 32b, which are arranged without overlapping each other, have their retroreflected light exit surfaces facing one side of the second half mirror 30, and the CGH is calculated by the CGH calculator 17 of the PC 12. It is also the projection plane of the predetermined image. As shown in FIG. 1(b), the retroreflective sheets 32a and 32b have a large number of glass beads 33b arranged in a transparent resin layer 33c formed on one side of the reflective sheet 33a. As shown in 1(b), the retroreflected light exits from the retroreflected light exit surface in the direction opposite to the incident light along the incident path of the incident light. Although the retroreflection sheet 32 shown in FIG. 1(b) uses a large number of glass beads 33b, it may be a retroreflection sheet using a large number of prisms.

The diffracted light incident on the projection unit 10b from the holographic projector unit 10a is reflected by the mirror 24, passes through the second half mirror 30, and irradiates the retroreflected light exit surfaces of the retroreflective sheets 32a and 32b. . A projected image a is projected onto the retroreflective light exit surface of the retroreflective sheet 32a irradiated with the diffracted light. From the retroreflected light exit surface of the retroreflective sheet 32a on which the projected image a is projected, the retroreflected light is emitted in the direction opposite to the incident light of the projected image a. This retroreflected light is reflected by one side of the second half mirror 30 and enters the human eye, and a virtual image a corresponding to the projected image a appears on the other side of the second half mirror 30 . The depth from the other side of the second half mirror 30 to the virtual image a (indicated by Fa′ in FIG. 1(a)) is the height from the one side of the second half mirror 30 to the retroreflective sheet 32a (in FIG. 1 (indicated by Fa in (a)). A projection image b is projected onto the retroreflection light exit surface of the retroreflection sheet 32b irradiated with the diffracted light. From the retroreflected light exit surface of the retroreflective sheet 32b on which the projected image b is projected, the retroreflected light is emitted in the direction opposite to the incident light of the projected image b. This retroreflected light is reflected by one surface side of the second half mirror 30 and enters the human eye, and a virtual image b corresponding to the projected image b is formed on the other surface side of the second half mirror 30 behind the virtual image a. looks like The depth from the other side of the second half mirror 30 to the virtual image b (indicated by Fb' in FIG. 1(a)) is also the height from the one side of the second half mirror 30 to the retroreflective sheet 32b (in FIG. 1 (indicated by Fb in (a)).
By the way, the height from one side of the second half mirror 30 to the projection plane of the retroreflective sheet 32a (indicated by Fa in FIG. 1A) is the same as the one side of the second half mirror 30 to the retroreflective sheet 32b. 1 (a) to the projection surface (indicated by Fb in FIG. 1A), the virtual image b can be seen behind the virtual image a because the retroreflective sheet 32a is tilted by the second half mirror 30. This is because it is arranged on the lower end side of the surface.

In FIG. 2, from the head-up display device 10, a character "A" is projected as a projection image a onto a projection surface (hereinafter simply referred to as a projection surface), which is the retroreflected light exit surface of the retroreflective sheet 32a. , shows a state in which a character "B" is projected as a projected image b onto a projection surface (hereinafter simply referred to as a projection surface), which is the retroreflected light exit surface of the retroreflective sheet 32b. The letter "A" projected onto the retroreflective sheet 32a appears as a virtual image a on the other side of the second half mirror 30, and the letter "B" is projected onto the projection plane of the retroreflective sheet 32b. , the character "B" as the virtual image b appears on the other side of the second half mirror 30 on the back side of the character "A" as the virtual image a. In this way, the single holographic projector unit 10a can project the letters "A" and "B" from one side of the second half mirror 30 to the other side of the second half mirror 30 with different senses of distance. virtual images can be seen at the same time.

Here, when mirrors were arranged instead of the retroreflective sheets 32a and 32b of FIG. 1(a), the virtual images a and b could not be seen. It is presumed that this is due to the difference in reflection between the mirror and the retroreflective sheet. Also, when white paper or black paper was placed instead of the retroreflective sheets 32a and 32b, the virtual images a and b were visible, but extremely unclear. It is presumed that the white paper or black paper has a lower reflectance in the direction of retroreflection than the retroreflective sheet.

Even if a shielding plate 31 is inserted as shown in FIG. 3 between the virtual image a and the virtual image b shown in FIG. 1A, the virtual image b can be seen through the shielding plate 31 . Further, as shown in FIG. 4, by moving the retroreflective sheet 32b in the direction of the arrow F (the direction of the second half mirror 30) to the position 32b', the virtual image b can be seen at the position indicated by the arrow f (in the direction of the second half mirror 30), and can be positioned at a position b' in front of the virtual image a. However, when the retroreflective sheet 32b is moved, a computer-generated hologram (CGH) in which the projection image b is projected at the position 32b' shown in FIG. It is necessary to be

As shown in FIGS. 1 to 4, the positions at which the virtual images a and b are visible correspond to the distances (optical path lengths) between the retroreflective sheets 32a and 32b and the second half mirror 30. The longer the distance (optical path length) to the mirror 30 is, the farther the virtual image appears from the second half mirror 30 . When it is desired to increase the distance (optical path length) between the retroreflective sheet and the second half mirror 30, and there are physical restrictions such as the size of the room, the retroreflective sheet 32a shown in FIG. and the second half mirror 30 to bend the optical path between the retroreflective sheet 32a and the second half mirror 30 to lengthen the optical path length.

In the projection unit 10b shown in FIGS. 1 to 5, two retroreflective sheets are arranged, but in the projection unit 10b shown in FIG. 6, there is only one movable retroreflective sheet 32a. may Since diffracted light is projected from the holographic projector unit 10a so as to project the projection images a and b onto a predetermined position on one surface side (inclined surface) of the second half mirror 30, the retroreflective sheet shown in FIG. At the position 32 a , the projection image a is projected and the virtual image a appears on the other side of the second half mirror 30 . When the retroreflection sheet 32a at the projection position of the projection image a is moved to the projection position 32a' where the projection image b is projected, the virtual image a disappears, but the projection image b is not projected onto the retroreflection sheet 32a. A virtual image b appears on the other side of the second half mirror 30 . The virtual image b can be seen on the back side of the virtual image a. By moving the movably provided retroreflective sheet 32a to the position where the projected image b is projected, the virtual image b can be viewed with a perspective different from that of the virtual image a.

1 to 6, the retroreflective sheets 32a and 32b are arranged in series on the lower end side and the upper end side of the second half mirror 30 as shown in FIG. The position of is also affected by the tilt of the second half mirror 30 . In order to avoid such an influence due to the inclination of the second half mirror 30, as shown in FIG. is preferred. By arranging the retroreflection sheets 32a and 32b in this way, as shown in FIG. It can be predicted that the virtual images a and b will appear at the corresponding positions.

で表すことができる。 In the head-up display device 10 described above, a computer-generated hologram (CGH) of a predetermined image input from the tablet terminal device 11 to the PC 12 is calculated by the CGH calculator 17 and output to the SLM 14 . A computer-generated hologram (CGH) calculated by the CGH calculator 17 will be described.
A computer-generated hologram (hereinafter simply referred to as CGH) of a three-dimensional object composed of N object points shown in FIG. When the position coordinates of the point light source P are P(x _n , y _n , z _n ), _{the light intensity I comp ( x h ,} y _h ,0) is the following formula (3)

can be expressed as

で表すことができる。 By the way, the SLM 14 includes one that displays an amplitude hologram and one that displays a phase hologram. Here, as shown in FIG. 8, the position coordinates of the n-th point light source P on the three-dimensional object are P(x _n , y _n , z _n ), its brightness is A _n , and the size of one pixel is Δ _x ×Δ _y , where the coordinates of the i-th and j-th CGH pixels in the x and y directions are (x _h , y _h )=(iΔ _x , jΔ _y ), each point on the amplitude hologram (x The light intensity I _amp (x _h ,y _h ,0) at _h ,y _h ,0) is given by the following formula (4)

can be expressed as

で表すことができる。
上記数式（５）のIm{I_comp}は虚部であり、Re{I_comp}は実部であって、上記数式（４）
と同じであるから、上記数式（５）は下記数式（６）

で表すことができる。 Also, the phase I _phase (x _h , y _h , 0) at each point (x _h , y _h , 0) on the phase hologram is expressed by the following formula (5)

can be expressed as
Im{I _comp } in the above equation (5) is the imaginary part, Re{I _comp } is the real part, and the above equation (4)
is the same as, the above formula (5) becomes the following formula (6)

can be expressed as

のように変形した。
また、位相ホログラムの位相（I_phase(x_h,y_h,0)）を表す上記数式（６）を下記数式（８）

のように変形した。 The amplitude hologram can be calculated based on the above equation (4), and the phase hologram can be calculated based on the above equation (6), which can be used for CGH calculation of a three-dimensional still image.
However, in the case of 3D moving images, a further improvement in calculation speed is required compared to the calculation of CGH using the above formula (4) or the above formula (6). Therefore, in order to improve the calculation speed of CGH, the above formula (4) representing the light intensity of the amplitude hologram (I _amp (x _h , y _h , 0)) is changed to the following formula (7)

transformed like
Also, the above formula (6) representing the phase of the phase hologram (I _phase (x _h , y _h , 0)) is changed to the following formula (8)

transformed like

In order to calculate the amplitude hologram based on the above formula (7) in the CGH calculation unit 17 of the PC 12 shown in FIG. A position coordinate data storage unit 17a for storing position coordinate data of the point light source of the original image, and a CGH for storing values obtained by calculating sinX and cosX in the x direction of the CGH based on the position coordinate data in the position coordinate data storage unit 17a. a trigonometric function table 17b in the x direction of the CGH, a trigonometric function table 17c in the y direction of the CGH that stores values obtained by calculating sinY and cosY in the y direction of the CGH based on the position coordinate data of the position coordinate data storage unit 17a, The amplitude hologram calculator 17d calculates the light intensity of the amplitude hologram (I _amp (x _h , y _h , 0)) using the trigonometric function values stored in the function tables 17b and 17c, and the amplitude hologram calculator 17d. and an amplitude hologram data storage unit 17e for storing the light intensity (I _amp (x _h , y _h , 0)) of the amplitude hologram obtained and outputting it to the SLM 14 .

FIG. 10 is a pseudo code for calculating the amplitude hologram in the CGH calculator 17 shown in FIG. 9, and FIG. 11 is a flow chart thereof. The pseudo code shown in FIG. 10 assumes that the CGH resolution is W×H, and the flowchart shown in FIG. 11 is for a 3D moving image, but it can also be applied to a 3D still image.
10 and 11, the trigonometric function table 17c is created after creating the trigonometric function table 17b, but the trigonometric function table 17b may be created after creating the trigonometric function table 17c. 17b and 17c may be created in parallel. The creation of the trigonometric function tables 17b and 17c, the calculation of the amplitude hologram by the amplitude hologram calculator 17d, and the output of the amplitude hologram to the SLM 14 by the amplitude hologram data storage unit 17e may be processed in parallel. Furthermore, when the trigonometric function tables 17b and 17c are created in advance for each frame of the three-dimensional moving image, and the amplitude holograms to be displayed on the SLM 14 can be created and displayed by using them, the point light source loop is the first in the flow chart shown in FIG. It may be an inner loop.

In order to calculate the phase hologram based on the above formula (8) in the CGH calculation unit 17 of the PC 12 shown in FIG. A position coordinate data storage unit 17a for storing the position coordinate data of the point light source of the original image, and a CGH for storing values obtained by calculating sinX and cosX in the x direction of the CGH based on the position coordinate data of the position coordinate data storage unit 17a. An x-direction trigonometric function table 17b, a CGH y-direction trigonometric function table 17c that stores values obtained by calculating sinY and cosY in the y-direction of the CGH based on the position coordinate data of the position coordinate data storage unit 17a, and a trigonometric function An imaginary/real part calculator 17f that calculates an imaginary part Im{Icomp} and a real part Re{Icomp} using the trigonometric function values stored in the tables 17b and 17c, and an imaginary/real part calculator 17f The imaginary part/real part storage unit 17g of the imaginary part Im{Icomp} and the real part Re{Icomp} calculated in , and the imaginary part Im{Icomp} and the real part Re stored in the imaginary/real part storage unit 17g A phase hologram calculator 17h that calculates the phase of the phase hologram (I _phase (x _h , y _h , 0)) using {Icomp}, and the phase of the phase hologram calculated by the phase hologram calculator 17h (I _phase ( and a phase hologram data storage unit 17i for storing _xh , _yh , 0)) and outputting it to the SLM .

Pseudo code for calculating the phase hologram in the CGH calculator 17 shown in FIG. 12 is shown in FIG. 13, and its flow chart is shown in FIG. The pseudo code shown in FIG. 13 assumes that the CGH resolution is W×H, and the flowchart shown in FIG. 14 is for a 3D moving image, but it can also be applied to a 3D still image.
13 and 14, the trigonometric function table 17c is created after creating the trigonometric function table 17b, but the trigonometric function table 17b may be created after creating the trigonometric function table 17c. 17b and 17c may be created in parallel. In addition, the trigonometric function tables 17b and 17c are created, the imaginary part Im{Icomp} and the real part Re{Icomp} are calculated in the imaginary/real part calculator 17f, and the phase hologram phase is calculated in the phase hologram calculator 17h. The calculation of (I _phase (x _h , y _h , 0)) and the output of the phase hologram from the phase hologram data storage unit 17i to the SLM 14 may be processed in parallel. Furthermore, when the trigonometric function tables 17b and 17c are created in advance in each frame of the three-dimensional moving image, and the phase hologram to be displayed on the SLM 14 can be created and displayed by using them, the point light source loop is the first in the flow chart shown in FIG. It may be an inner loop.

A CPU (Central Processing Unit) and/or the CGH calculator 17 shown in FIG. It can be provided in a GPU (Graphics Processing Unit).
By the way, both CPU and GPU have a plurality of cores, but in order to realize real-time reproduction of 3D moving images, at least 30 CGHs must be calculated per second and reproduced. However, the number of cores that a CPU has is much smaller than that of a GPU, and the processing speed of the CPU is slow. Although it can be used for processing 3D still images, it is not suitable for processing 3D moving images. On the other hand, a GPU has many cores and can be used not only for processing 3D still images but also for 3D moving image processing.
Although the above explanation of CGH was for a three-dimensional object, it can be handled by calculating Zn as a constant value in the above equations (3) to (8) in the case of a two-dimensional object.

1 is projected onto the retroreflective sheet 32a at a predetermined position, and at the same time, the letter "B" of the projected image b shown in FIG. 1 is projected onto the retroreflective sheet 32b at a predetermined position. The CGH to be displayed is displayed on the SLM 14 . In this CGH, in Equation (7) or Equation (8), Zn of the character "A" input from the tablet-type terminal device 11 is set to a predetermined value a, and Zn of the character "B" input from the tablet-type terminal device 11 is Zn is set to a predetermined value b, and calculated all at once. By displaying one calculated CGH on the SLM 14, the character "A" and the character "B" can be simultaneously projected onto the respective predetermined positions a and b.

In the above description, a reflective SLM was used as the SLM 14, but a transmissive SLM may be used. may be entered. Further, although the computer-generated hologram calculated by the PC 12 is displayed on the SLM 14, the hologram interference fringes may be printed on a film. Further, although the SLM 14 is irradiated with laser light, it may be irradiated with light from a light emitting diode (LED).

Examples of the present invention will be described in detail below, but the scope of the present invention is not limited to these examples.

(Example 1)
In the projection part 10b of the head-up display device 10 shown in FIG. As shown in FIG. 7, retroreflective sheets 32a and 32b are horizontally arranged in parallel in the lateral direction of the rectangular second half mirror 30 at a predetermined height. The retroreflection sheets 32 a and 32 b use Scotchlite reflective cloth 8910 manufactured by 3M Company, and the projection surface, which is the exit surface of each retroreflected light, faces the inclined surface of the second half mirror 30 . The height of the projection surface of the retroreflection sheet 32a from the inclined surface of the second half mirror 30 (indicated by Fa in FIG. 1(a)) is 100 cm. The height from the slope of 30 (indicated by Fb in FIG. 1(a)) is 70 cm.
The characters "A" and "B" and projection position data of each character were input from the tablet terminal device 11 of the holographic projector unit 10a to the PC 12 toward the projection unit 10b. One CGH is calculated by the formula (8) based on the input data and displayed on the SLM 14 . As a result, the character "A" can be projected onto the projection surface of the retroreflective sheet 32a, and the character "B" can be projected onto the projection surface of the retroreflective sheet 32b at the same time. Pseudocode for calculating equation (8) is shown in FIG. 13 and its flow chart is shown in FIG.
Green laser light (wavelength: 532 nm) emitted from the laser light emitting unit 16 is collimated through the objective lens 18 and the plano-convex lens 20 to the SLM 14 on which the CGHs related to the letters "A" and "B" are displayed. , and the diffracted light diffracted based on the interference information about the characters "A" and "B" displayed on the SLM 14 is transmitted through the first half mirror 22 to the projection unit shown in FIG. Injected at 10b.
The diffracted light incident on the projection unit 10b passes through the mirror 24 and the second half mirror 30, illuminates the projection surfaces of the retroreflection sheets 32a and 32b as shown in FIG. The character "A" was projected on the projection surface, and the character "B" was simultaneously projected on the projection surface of the retroreflective sheet 32b.
Furthermore, when viewed from the inclined surface side of the second half mirror 30, as shown in FIG. was clearly seen, and the letter "A" of the virtual image a was seen on the back side of the letter "B" of the virtual image b.

(Comparative example 1)
When mirrors are used in place of the retroreflective sheets 32a and 32b in the first embodiment, although the corresponding characters are projected on the reflecting surface of each mirror, when viewed from the inclined surface side of the second half mirror 30, , I could not see the virtual image at all.
Also, when black paper is used instead of the retroreflective sheets 32a and 32b, although the corresponding characters are projected on the irradiation surface of each black paper, when viewed from the inclined surface side of the second half mirror 30, The virtual image was unclear. Even if this black paper was replaced with white paper, although the corresponding characters were projected on the irradiation surface of each white paper, the virtual image was unclear when viewed from the inclined surface side of the second half mirror 30 .

(Example 2)
The CGH calculation unit 17 of the PC 12 shown in FIG. 1 was provided in the CPU or GPU, and the CGH creation speed depending on the difference in the CGH calculation formula of the amplitude hologram was measured by changing the number of object points. The results are shown in Table 1 below.
Calculation formula for amplitude hologram Equation (4) above [pseudocode: FIG. 15(a)]
Equation (7) above [pseudocode: FIG. 10]
CGH calculator 17
CPU: Core (trademark) i7-8700K manufactured by INTEL Corporation
GPU: GeForce RTX™ 3080 from NVIDIA Corporation

表１から明らかなように、数式（７）によるＣＧＨ作成速度は、数式（４）よりも速く、且つＧＰＵのＣＧＨ作成速度はＣＰＵよりもかなり速いことから、ＧＰＵの数式（７）による振幅ホログラムを三次元動画に適用可能であることが判る。
ここで、数式(４)の計算をＣＰＵで行う際、ｃｏｓ関数の計算負荷が大きくなるため、０～２πの１周期において２５６等分にサンプリングし、サンプリングしたｃｏｓ関数の値域－１～＋１を８ビットの－１２７～１２７の整数値としたｃｏｓテーブルを用いて計算高速化した。また、コンパイラとしてIntel C++ compiler classic Version 2021.2.0 (オプション： -O3 -xCORE-AVX2 -qopenmp) を用い、OpenMPのスレッド数を１２とした。

As is clear from Table 1, the CGH creation speed by Equation (7) is faster than Equation (4), and the CGH creation speed of GPU is considerably faster than that of CPU. can be applied to 3D moving images.
Here, when the calculation of formula (4) is performed by the CPU, the calculation load of the cos function becomes large. A cos table with 8-bit integer values from -127 to 127 was used to speed up the calculation. Also, Intel C++ compiler classic Version 2021.2.0 (option: -O3 -xCORE-AVX2 -qopenmp) was used as a compiler, and the number of OpenMP threads was set to 12.

(Example 3)
The CGH calculation unit 17 of the PC 12 shown in FIG. 1 was provided in the CPU or GPU, and the CGH creation speed depending on the difference in the CGH calculation formula of the phase hologram was measured by changing the number of object points. The results are shown in Table 2 below.
Calculation formula for phase hologram Equation (6) above [pseudocode: FIG. 15(b)]
Equation (8) above [pseudocode: FIG. 13]
CGH calculator 17
CPU: Core (trademark) i7-8700K manufactured by INTEL Corporation
GPU: GeForce RTX™ 3080 from NVIDIA Corporation

表２から明らかなように、数式（８）によるＣＧＨ作成速度は、数式（６）よりも速く、且つＧＰＵのＣＧＨ作成速度はＣＰＵよりもかなり速いことから、ＧＰＵの数式（８）による位相ホログラムを三次元動画に適用可能であることが判る。
ここで、数式(６)の計算をＣＰＵで行う際、ｃｏｓ及びｓｉｎ関数の計算負荷が大きくなるため、０～２πの１周期において２５６等分にサンプリングし、サンプリングしたｃｏｓ及びｓｉｎ関数の値域－１～＋１を８ビットの－１２７～１２７の整数値としたｃｏｓ及びｓｉｎテーブルを用いて計算高速化した。また、コンパイラとしてIntel C++ compiler classic Version 2021.2.0 (オプション： -O3 -xCORE-AVX2 -qopenmp) を用い、OpenMPのスレッド数を12とした。

As is clear from Table 2, the CGH creation speed by Equation (8) is faster than Equation (6), and the CGH creation speed of GPU is considerably faster than that of CPU. can be applied to 3D moving images.
Here, when the calculation of formula (6) is performed by the CPU, the calculation load of the cosine and sin functions becomes large. Calculation speed was increased using cos and sin tables in which 1 to +1 are integer values of -127 to 127 of 8 bits. In addition, Intel C++ compiler classic Version 2021.2.0 (options: -O3 -xCORE-AVX2 -qopenmp) was used as the compiler, and the number of OpenMP threads was set to 12.

The head-up display device according to the present invention can be used for guidance head-up displays, aerial message boards, show windows, and digital signage.

10: Head-up display device, 10a: Holographic projector section, 10b: Projection section, 11: Tablet type terminal device, 12: Personal computer (PC), 14: Spatial light modulator (SLM), 15: Parallel light emission section , 16: Laser beam emitting unit, 17: CGH calculation unit, 17a: Position coordinate data storage unit, 17b: CGH x-direction trigonometric function table, 17c: CGH y-direction trigonometric function table, 17d: Amplitude hologram calculation unit , 17e: amplitude hologram data storage unit, 17f: imaginary/real part calculation unit, 17g: imaginary/real part data storage unit, 17h: phase hologram calculation unit, 17i: phase hologram data storage unit, 18: objective lens, 20: planoconvex lens, 22: first half mirror, 24, 34: mirror, 30: second half mirror, 31: light blocking plate, 32a, 32b: retroreflective sheet, 32a': movement position of retroreflective sheet 32a , 32b': movement position of the retroreflective sheet 32b, 33a: reflective sheet, 33b: glass beads, 33c: transparent resin layer, Fa, Fb: height, Fa', Fb': depth, F, f: arrow, b': the position where the virtual image b can be seen when the retroreflective sheet 32b is moved to the position 32b', W: the number of horizontal pixels of the CGH, _H : the number of vertical pixels of the CGH, xh: x of the pixel on the hologram. Directional position coordinates, y _h : y-direction position coordinates of pixels on the hologram, Δ _x : x-direction pixel size, Δ _y : y-direction pixel size, P(x _n , y _n , z _n ): position coordinates of the n-th object point P of the 3D object

Claims (7)

a holographic projector unit that irradiates parallel light onto a hologram created so that each of a plurality of predetermined images is projected at different predetermined positions, and emits diffracted light that is diffracted based on interference information of the hologram;
a half mirror installed at an angle and through which the diffracted light is irradiated and transmitted;
The diffracted light transmitted through the half mirror is applied at a predetermined distance from one surface side of the half mirror, and the projection image corresponding to each of the predetermined images is projected at the predetermined position. , Consists of a single retroreflective element or a plurality of retroreflective elements arranged without overlapping portions,
The retroreflective element is configured so that the retroreflected light of the projected image emitted from the retroreflected light exit surface thereof is reflected by the half mirror and appears as a virtual image on the other side of the half mirror. The light emitting surface of the reflective light is installed facing one side of the half mirror,
At least one retroreflective element out of the one retroreflective element or the plurality of retroreflective elements is provided movably to the projection position of the corresponding predetermined image,
Alternatively, all of the plurality of retroreflective elements or each of the remaining retroreflective elements excluding the movably provided retroreflective elements are arranged at the projection positions of the corresponding predetermined images. A head-up display device characterized by: Each of the retroreflective elements is arranged at the projection position corresponding to each of the predetermined images so that all virtual images corresponding to the plurality of predetermined images can be seen at the same time when viewed from one side of the half mirror. 2. The head-up display device according to claim 1, wherein the head-up display device comprises: The distance of the retroreflective element corresponding to each of the virtual images from the one side of the half mirror is adjusted so that each of the virtual images can be seen at different distances from the other side of the half mirror. 3. A head-up display device according to claim 1 or 2. 2. The hologram according to claim 1, wherein said hologram is a computer-generated hologram, and a spatial light modulator is provided for modulating said parallel light into diffracted light based on interference information of said computer-generated hologram. Head-up display device. The computer-generated hologram is an amplitude hologram, and the amplitude hologram is represented by the following formula (1)

5. The head-up display device according to claim 4, wherein the calculation is based on. The computer-generated hologram is a phase hologram, and the phase hologram is represented by the following formula (2)

5. The head-up display device according to claim 4, wherein the calculation is based on. 2. A head-up display device according to claim 1, wherein said parallel light is laser light.

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