JP2024082138A - Display device - Google Patents

Abstract

A display device is provided that can appropriately control the luminance of an image displayed on each display surface even when different images are displayed on a plurality of display surfaces having different illumination distances.
[Solution] A head-up display device H includes a spatial phase modulator 13 that diffracts light output from a light source 11, an unwanted light cutting mask 18 that cuts out unwanted light in non-display areas, and a control unit 3 that controls the light source 11 and the spatial phase modulator 13, and displays different images G1 to G3 on multiple display surfaces P1 to P3 with different irradiation distances. The control unit 3 generates and synthesizes image formation patterns G13 to G33 for the spatial phase modulator 13 to form the images G1 to G3 on each of the display surfaces P1 to P3, and adds dummy patterns DP1 to DP3 to the non-display area when controlling the spatial phase modulator 13 based on the synthesized pattern, so that the sums of the gradation values of all pixels of each of the image formation patterns G13 to G33 match.
[Selected figure] Figure 5

Description

This disclosure relates to a display device.

There is known a display device that uses a spatial light modulator (SLM) to display an image including interference fringes (CGH pattern) based on a computer-generated hologram (CGH). For example, the projector disclosed in Patent Document 1 is known.

JP 2017-151444 A

However, with this type of display device, when trying to display different images on multiple display surfaces with different illumination distances, it is difficult to appropriately control the brightness of the images displayed on each display surface.

Therefore, the present disclosure aims to provide a display device that can appropriately control the brightness of the image displayed on each display surface, even when different images are displayed on multiple display surfaces with different illumination distances.

In one aspect, the following solution is provided.
A light source that outputs light;
a spatial phase modulator that diffracts the light output from the light source and forms image light including interference fringes based on a computer-generated hologram;
an unnecessary light cut mask that cuts unnecessary light in a non-display area from the image light output from the spatial phase modulator;
A display device comprising: a control unit that controls the light source and the spatial phase modulator; and a display device that displays different images on a plurality of display surfaces having different illumination distances,
The control unit is
a pattern generating means for generating a first image forming pattern for forming a first image to be displayed on a first display surface by the spatial phase modulator, and a second image forming pattern for forming a second image to be displayed on a second display surface by the spatial phase modulator;
a pattern synthesizing means for generating a composite pattern of the first image forming pattern and the second image forming pattern;
a multiple image display means for controlling the spatial phase modulator based on the composite pattern to display the first image on the first display surface and the second image on the second display surface,
A display device is provided, characterized in that the pattern generating means adds a dummy pattern to the non-display area so that the sum of the gradation values of all pixels of the first image forming pattern matches the sum of the gradation values of all pixels of the second image forming pattern.

In another aspect, the following solution is provided.
A light source that outputs light;
a spatial phase modulator that diffracts the light output from the light source and forms image light including interference fringes based on a computer generated hologram (CGH pattern);
an unnecessary light cut mask that cuts unnecessary light in a non-display area from the image light output from the spatial phase modulator;
A display device comprising: a control unit that controls the light source and the spatial phase modulator; and a display device that displays different images on a plurality of display surfaces having different illumination distances,
The control unit is
a pattern generating means for generating a first image forming pattern for forming a first image to be displayed on a first display surface by the spatial phase modulator, and a second image forming pattern for forming a second image to be displayed on a second display surface by the spatial phase modulator;
a multiple image display means for controlling the spatial phase modulator based on the first image forming pattern and the second image forming pattern to display the first image on the first display surface and the second image on the second display surface,
The display device is characterized in that the multiple image display means calculates a product of an image area and a gradation value of the first image formation pattern and a product of an image area and a gradation value of the second image formation pattern, and calculates a ratio between these products, and sequentially switches between the first image formation pattern and the second image formation pattern in a time division manner based on the ratio.

The present disclosure aims to provide a display device that can appropriately control the brightness of the image displayed on each display surface, even when different images are displayed on multiple display surfaces with different illumination distances.

1 is a schematic diagram showing a side view of a vehicle equipped with a head-up display device according to a first embodiment. 1 is a schematic cross-sectional view of a head-up display device according to a first embodiment. FIG. 2 is a schematic diagram showing the configuration of a display unit and a control unit. 11A to 11C are diagrams illustrating a procedure for generating an image forming pattern in a first monochrome mode. FIG. 13 is a diagram showing an example of an image displayed in a first monochrome mode. 11A and 11B are diagrams illustrating luminance balance adjustment in a first monochrome mode. 11A and 11B are diagrams illustrating luminance balance adjustment in a second monochrome mode. 13A and 13B are diagrams illustrating luminance balance adjustment in the third monochrome mode. FIG. 11 is an explanatory diagram of color matching in a first color mode. FIG. 11 is an explanatory diagram of color matching in a third color mode (second color mode). FIG. 11 is an explanatory diagram of secondary luminance balance adjustment in the third color mode (second color mode). FIG. 11 is a schematic diagram showing the configuration of a display and a control unit according to a second embodiment. FIG. 11 is an explanatory diagram of color matching in a fourth color mode. FIG. 11 is an explanatory diagram of color matching in a sixth color mode (fifth color mode). FIG. 13 is an explanatory diagram of secondary luminance balance adjustment in the sixth color mode (fifth color mode). FIG. 13 is a schematic diagram showing the configuration of a display and a control unit according to a third embodiment. FIG. 13 is a schematic diagram showing the configuration of a display and a control unit according to a fourth embodiment.

Each embodiment will be described in detail below with reference to the attached drawings. Note that in the drawings, for ease of viewing, only some of the parts with the same attribute may be labeled with reference symbols.

[Configuration of Head-Up Display Device]
Fig. 1 is a schematic diagram of a vehicle 10 equipped with a head-up display device H according to this embodiment, as seen from the side. Fig. 1A is a schematic cross-sectional view of the head-up display device H according to this embodiment. In Fig. 1 and Fig. 1A, three orthogonal axes (X-axis, Y-axis, and Z-axis) in a right-handed coordinate system are defined. Here, the X-axis corresponds to the left-right direction (width direction) of the vehicle 10, the Z-axis corresponds to the front-rear direction of the vehicle 10, and the Y-axis corresponds to the up-down direction of the vehicle 10.

As shown in FIG. 1, the head-up display device H is disposed inside the instrument panel 7 of the vehicle 10. The head-up display device H reflects projected display light PL by the windshield WS of the vehicle 10 toward the passenger P (e.g., the driver) of the vehicle 10, and displays a virtual image V. That is, the head-up display device H is a projection-type display device that emits (projects) the display light PL emitted from a display 1 (described later) onto the windshield WS (projection member), and allows the passenger P to view the display image (virtual image) V obtained by this emission. This allows the passenger P to view the virtual image V superimposed on the scenery.

As shown in FIG. 1A, the head-up display device H contains a display 1, a reflector 2, a control unit 3, etc., in a case 4. The case 4 has an emission port 41 on the upper surface side of the instrument panel 7, and the display light PL is emitted from inside the case 4 toward the windshield WS through the emission port 41. The emission port 41 may be covered with a transparent dust cover.

The display device 1 emits display light PL. In this embodiment, the display device 1 emits display light PL including interference fringes that constitute a computer-generated hologram, as described below. In this case, the display light PL forms an image on the retina (screen) of the passenger P, and a virtual image V is seen in front of the windshield WS. Details of the display device 1 will be described later with reference to Figure 2 onwards.

The reflector 2 is, for example, a concave mirror, and reflects the display light PL from the display device 1 while magnifying the light, directing the light PL toward the windshield WS. In other words, the reflector 2 magnifies the light PL while folding it back.

The control unit 3 is, for example, in the form of a control circuit board, and controls the display 1. For example, the control unit 3 generates display light PL corresponding to various vehicle information at appropriate timing so that the various vehicle information is transmitted to the passenger P via the virtual image V. The type of vehicle information transmitted via the virtual image V may be any type.

In the example shown in FIG. 1 and FIG. 1A, the head-up display device H has a reflector 2, but the reflector 2 may be omitted. In addition, other optical systems may be additionally arranged inside the case 4. For example, the display light PL may be projected onto the windshield WS via a screen.

[Display configuration]
FIG. 2 is a schematic diagram showing the configuration of the display device 1 and the control unit 3.

The display 1 includes a light source 11, a collimator section 12, a spatial phase modulator 13, a half mirror 14, a telescope optical system 15, a zero-order light cut mask 16, a dichroic mirror 17, and an unwanted light cut mask 18.

In this embodiment, the optical system consisting of the light source 11, collimator unit 12, spatial phase modulator 13, half mirror 14, telescope optical system 15, and zero-order light cut mask 16 is referred to as a monochromatic optical system 19. The display 1 in this embodiment also includes a plurality of light sources 11R, 11G, and 11B that emit light of different wavelengths, and a monochromatic optical system 19R, 19G, and 19B is configured for each light source 11R, 11G, and 11B. However, since the configuration of each monochromatic optical system 19R, 19G, and 19B is substantially the same, the following description may only cover one of the monochromatic optical systems 19.

The light source (first light source, second light source) 11 outputs light of a predetermined wavelength. For example, the light source 11 includes an LD (laser diode) that emits laser light. As described above, the display 1 of this embodiment includes a plurality of light sources 11R, 11G, and 11B that emit light of different wavelengths. The light source 11R includes, for example, a red LD that emits red laser light with a wavelength of 630 nm. The light source 11G includes, for example, a green LD that emits green laser light with a wavelength of 532 nm. The light source 11B includes, for example, a blue LD that emits blue laser light with a wavelength of 450 nm. The light source 11 is not limited to an LD. For example, a combination of an LED, a wavelength filter, a polarizing filter, and a pinhole can be replaced with an LD.

The collimator 12 converts the light from the light source 11 into parallel light and outputs it toward the spatial phase modulator 13. The collimator 12 may cause the light from the light source 11 to be incident on the spatial phase modulator 13 in the form of a substantially plane wave.

The spatial phase modulator (first spatial phase modulator, second spatial phase modulator) 13 is a reflective modulator (spatial light modulator) that diffracts incident light and displays interference fringes based on a computer-generated hologram. The spatial phase modulator 13 operates under the control of the control unit 3 described above. For example, an LCOS-SLM (Liquid Crystal on Silicon-Spatial Light Modulator) is used as the spatial phase modulator 13. Note that the light reflected by the spatial phase modulator 13 may include not only light for transmitting vehicle information toward the passenger P, but also zero-order light that is not used for transmitting vehicle information.

The half mirror 14 is disposed between the collimator 12 and the spatial phase modulator 13, with a predetermined angle of inclination with respect to the optical axis. In other words, the half mirror 14 transmits the light emitted by the collimator 12, while reflecting the light diffracted by the spatial phase modulator 13 so that it enters the telescope optical system 15.

The telescope optical system 15 enlarges or reduces the real image IM produced by the diffracted light of the spatial phase modulator 13. As the telescope optical system 15, a Keplerian telescope optical system or a Galilean telescope optical system can be used. As shown in FIG. 2, the telescope optical system 15 of this embodiment is a Keplerian telescope optical system, and is composed of two lenses 151 and 152 having positive focal lengths f1 and f2. The two lenses 151 and 152 are disposed at a distance equivalent to the sum of the focal lengths f1 and f2 of the lenses 151 and 152. The magnification (magnification ratio) of the telescope optical system 15 can be expressed by the following formula, where the focal length of the lens 151 on the spatial phase modulator 13 side is f1, and the focal length of the lens 152 on the real image IM side is f2.
Magnification = f2/f1

In the display 1 of this embodiment, the size of the generated real image IM is adjusted for each wavelength using the telescope optical system 15, and the angle of view and pixel size are adjusted. This makes it possible to suppress image shifts caused by differences in wavelength without changing the resolution.

The zero-order light cut mask 16 blocks the zero-order light contained in the light emitted from the spatial phase modulator 13, preventing the zero-order light from reaching the real image IM. In the display 1 of this embodiment, the telescope optical system 15 is a Keplerian telescope optical system, and the zero-order light cut mask 16 is placed at or near the focal position of the Keplerian telescope optical system. In other words, in a Keplerian telescope optical system, an intermediate image is generated at the focal position, making it easy to deal with the zero-order light and allowing the zero-order light to be efficiently removed. A specific example of the zero-order light cut mask 16 is, for example, a transparent slide having a black spot capable of blocking the zero-order light. The position and size of the zero-order light cut mask 16 and the black spot can be empirically adjusted so that the zero-order light is blocked well.

As shown in FIG. 2, the dichroic mirror 17 is composed of a combination of multiple mirrors with different wavelengths of transmitted light and reflected light, and combines the light (real images IM_R, IM_G, IM_B) that has passed through the telescope optical system 15 of each monochromatic optical system 19R, 19G, 19B. In other words, the dichroic mirror 17 combines the real images IM_R, IM_G, IM_B of each color formed in front of the dichroic mirror 17. The combined real image IM is displayed as a reconstructed image (images G1 to G3) via the unnecessary light cut mask 18, which is placed in the rear of the dichroic mirror 17.

The unnecessary light cut mask 18 cuts out the unnecessary light in the non-display area from the image light output from the spatial phase modulator 13. In other words, the unnecessary light cut mask 18 has an opening 181 for passing only the light necessary for image display. The unnecessary light cut mask 18 in this embodiment is placed after the dichroic mirror 17. In other words, when the unnecessary light cut mask 18 is placed after the dichroic mirror 17, multiple unnecessary light cut masks 18 are required according to the number of monochromatic optical systems 19, but when placed after the dichroic mirror 17, the unnecessary light cut mask 18 can be reduced to one. In addition, a predetermined distance or more is required between the real image IM and the unnecessary light cut mask 18, but the dichroic mirror 17 is interposed between the real image IM and the unnecessary light cut mask 18, making it easier to ensure the required distance.

[Configuration of control unit]
As shown in FIG. 2, the control unit 3 includes, as hardware components, a controller IC 31, a driver IC 32, and a microcomputer (not shown), and, as software components, a CGH engine 33 that operates the controller IC 31.

The controller IC 31 inputs a display image signal and a control signal from the vehicle ECU 8. The display image signal includes an image signal related to navigation information and an image signal related to vehicle information. The control signal includes an image display ON/OFF signal, a brightness adjustment signal, and a user operation signal. The controller IC 31 generates an image formation pattern based on the display image signal input from the vehicle ECU 8 and outputs it to the spatial phase modulator 13. This image formation pattern is a CGH pattern that the spatial phase modulator 13 uses to form image light that includes interference fringes based on a computer-generated hologram. The controller IC 31 also performs ON/OFF control and output control (brightness control) of the light source 11 via the driver IC 32.

The driver IC 32 drives the light source 11 with a predetermined power in response to a drive signal from the controller IC 31. The microcomputer communicates with the vehicle ECU 8 to control the overall operation of the head-up display device H (including turning the power on and off). Note that the controller IC 31 and the CGH engine 33 do not have to be one, but may be divided into multiple parts according to their roles (for example, according to the display color).

The control unit 3 realizes a plurality of display modes. The plurality of display modes include first to third monochromatic modes in which monochromatic images G1 to G3 are displayed using one of the monochromatic optical systems 19, and first to third color modes in which color images G1 to G3 are displayed using three monochromatic optical systems 19. In any of the display modes, the control unit 3 can display different images G1 to G3 on a plurality of display surfaces P1 to P3 with different illumination distances. Below, the functional configuration of the control unit 3 that realizes these display modes and the processing contents of each functional configuration in each display mode will be described with reference to Figures 3 to 10.

The control unit 3 includes a pattern generation means, a pattern synthesis means, a multiple image display means, a color matching means, and a secondary brightness adjustment means, which are functional components realized by the cooperation of hardware and software. The pattern generation means performs a predetermined process in all display modes, but the content of the process differs for each display mode. The pattern synthesis means performs a predetermined process in the first monochrome mode and the first color mode. The multiple image display means performs a predetermined process in all display modes, but the content of the process differs for each display mode. The color matching means performs a process in the first to third color modes. The secondary brightness adjustment means performs a predetermined process in the second and third color modes.

As shown in FIG. 3, the pattern generating means of the first monochrome mode generates first to third image forming patterns G13 to G33. The first image forming pattern G13 is a CGH pattern for forming the first image G1 that the spatial phase modulator 13 displays on the first display surface P1. The second image forming pattern G23 is a CGH pattern for forming the second image G2 that the spatial phase modulator 13 displays on the second display surface P2. The third image forming pattern G33 is a CGH pattern for forming the third image G3 that the spatial phase modulator 13 displays on the third display surface P3. These image forming patterns G13 to G33 are obtained by combining the CGH patterns G11 to G31 that are the basis of the images G1 to G3 and the CGH patterns G12 to G32 of the lenses that correspond to the irradiation distances (virtual image positions) of the respective display surfaces P1 to P3. The pattern synthesis means in the first monochromatic mode generates a synthesis pattern GA in which the first to third image formation patterns G13 to G33 are synthesized, as shown in Figure 3. The multiple image display means in the first monochromatic mode controls the spatial phase modulator 13 based on the synthesis pattern GA to display the first image G1 on the first display surface P1, the second image G2 on the second display surface P2, and the third image G3 on the third display surface P3.

According to the first monochromatic mode, as shown in FIG. 4, different images G1 to G3 can be displayed on multiple display surfaces P1 to P3 with different irradiation distances, and can be viewed by the passenger P. However, in the monochromatic mode, since the images are drawn on a single spatial phase modulator 13, the amount of light irradiated is always the same for the multiple images G1 to G3. Therefore, if the usage rate of any of the images G1 to G3 relative to the entire screen area is low, the light may be concentrated there, making the displayed image appear brighter than the other images G1 to G3. Conversely, if the usage rate of the entire screen area is high, the light may not be concentrated there, making the displayed image appear darker than the other images G1 to G3. This difference in brightness causes a problem of inconsistency between the image to be displayed and the actual displayed image.

As shown in FIG. 5, the pattern generating means in the first monochrome mode adds dummy patterns DP1 to DP3 to the non-display area of each image forming pattern G13 to G33 so that the sum of the gradation values of all pixels of each image forming pattern G13 to G33 matches. In this way, it is possible to suppress the luminance imbalance between the images G1 to G3 and to align the image to be displayed with the actual displayed image.

As shown in FIG. 6, in the second monochromatic mode, the first to third image formation patterns G13 to G33 generated by the pattern generation means are not synthesized, but different images G1 to G3 are displayed on multiple display surfaces P1 to P3 with different irradiation distances, and are visually recognized by the passenger P. In other words, the multiple image display means in the second monochromatic mode controls the spatial phase modulator 13 in a time-division manner to sequentially switch the first to third image formation patterns G13 to G33, thereby displaying the images G1 to G3 on the multiple display surfaces P1 to P3. At this time, the multiple image display means calculates the product of the image area and gradation value of the first image formation pattern G13, the product of the image area and gradation value of the second image formation pattern G23, and the product of the image area and gradation value of the third image formation pattern G33, and the ratio of each product. Then, the multiple image display means sequentially switches the first to third image formation patterns G13 to G33 in a time-division manner based on the calculated ratio. In this way, it is possible to suppress the luminance imbalance between the images G1 to G3 and align the image to be displayed with the actual displayed image without adding dummy patterns DP1 to DP3 to the non-display area.

However, in the second monochrome mode, if the product of the image area and gradation value of any of the image forming patterns G13 to G33 is extremely small, the allocated display period may become extremely short, and the image may not be visible. Therefore, as shown in FIG. 7, the pattern generating means in the third monochrome mode adds dummy patterns DP1 to DP3 to the non-display area of each image forming pattern G13 to G33 so that the above ratio is equal. In this way, even if the product of the image area and gradation value is extremely small, the display period can be allocated evenly, improving the visibility of the image.

The first color mode is a display mode in which the first monochrome mode is expanded to a color display. Specifically, the pattern generating means of the first color mode generates the first to third image forming patterns G13 to G33 for three colors. Dummy patterns DP1 to DP3 are added to the non-display areas of the image forming patterns G13 to G33 for each color, as in the first monochrome mode. The pattern synthesis means of the first color mode generates three-color synthesis patterns GA(R), GA(G), and GA(B) in which the first to third image forming patterns G13 to G33 for each color are synthesized, as shown in FIG. 8. The multiple image display means of the first color mode controls the spatial phase modulators 13 for each color based on the synthesis patterns GA(R), GA(G), and GA(B) for each color. As a result, in the first color mode, it is possible to display a first color image G1 on the first display surface P1, a second color image G2 on the second display surface P2, and a third color image G3 on the third display surface P3.

The color matching means in the first color mode performs color matching of images G1 to G3 based on output control of the three color light sources 11R, 11G, and 11B. For example, the light sources 11R, 11G, and 11B are continuously turned on in advance to obtain the output values of the light sources 11R, 11G, and 11B of each color that can display the reference white color, and the light sources 11R, 11G, and 11B are driven and controlled to achieve the obtained output values. Note that any control method can be selected for output control of the light sources 11R, 11G, and 11B, such as voltage control or PWM control.

The second color mode is a display mode in which the second monochrome mode is expanded into a color display, and the third color mode is a display mode in which the third monochrome mode is expanded into a color display. Note that the color matching processes of the second color mode and the third color mode are similar, so illustration and description of the second color mode are omitted.

As shown in FIG. 9, the pattern generating means in the third color mode generates the first to third image forming patterns G13 to G33 for three colors. The multiple image display means in the third color mode controls the spatial phase modulator 13 for each color based on the image forming patterns G13 to G33 for each color. Specifically, the spatial phase modulator 13 for each color is controlled in a time-division manner to sequentially switch the first to third image forming patterns G13 to G33. This makes it possible to display color images G1 to G3 on the multiple display surfaces P1 to P3, respectively. In the third color mode, as in the third monochrome mode, dummy patterns DP1 to DP3 are added to the non-display area to suppress the luminance imbalance between the images G1 to G3. In the second color mode, as in the second monochrome mode, the luminance imbalance between the images G1 to G3 is suppressed by changing the ratio of time division.

The color matching means in the third color mode (second color mode) performs color matching of images G1 to G3 based on output control of the three color light sources 11R, 11G, and 11B. For example, similar to the first color mode, the light sources 11R, 11G, and 11B are continuously turned on in advance to obtain the output values of the light sources 11R, 11G, and 11B of each color capable of displaying the reference white color, and the light sources 11R, 11G, and 11B are driven and controlled to achieve the obtained output values.

However, in the second and third color modes, the display periods assigned to each image forming pattern G13 to G33 are shorter than in the first color mode. Therefore, there is a possibility that the luminance balance between the images G1 to G3 cannot be adjusted sufficiently by simply changing the time division ratio or adding dummy patterns DP1 to DP3. Therefore, the secondary luminance adjustment means in the second and third color modes switches the output of the light sources 11R, 11G, and 11B each time the image forming patterns G13 to G33 are switched sequentially in a time division manner, as shown in FIG. 10. This adjusts the luminance of the images G1 to G3 secondarily. Such secondary luminance adjustment means makes it possible to more appropriately suppress the luminance imbalance between the images G1 to G3.

[Second embodiment]
Next, a second embodiment of the present invention will be described with reference to Figures 11 to 14. However, for configurations common to the first embodiment, the same reference numerals as in the first embodiment are used, and the description of the first embodiment may be used.

The display 1 of the first embodiment described above is composed of a combination of multiple light sources 11R, 11G, 11B and multiple spatial phase modulators 13. In contrast, the display 1B of the second embodiment shown in FIG. 11 is composed of a combination of multiple light sources 11R, 11G, 11B and one spatial phase modulator 13. In other words, the spatial phase modulator 13 of the second embodiment diffracts the light incident from the light sources 11R, 11G, 11B via the collimator section 12 and the dichroic mirror 17B, and displays multiple images G1 to G3 on multiple display surfaces P1 to P3.

The control unit 3B of the second embodiment can realize the first to third monochrome modes by the same processing as the control unit 3 of the first embodiment. At this time, the light sources 11R, 11G, and 11B may be selectively driven one by one, or multiple light sources may be driven simultaneously to display any color.

The control unit 3B of the second embodiment realizes three color modes using a process different from that of the control unit 3 of the first embodiment. Below, these color modes will be described as the fourth to sixth color modes.

The fourth color mode is a display mode for realizing a color display equivalent to the first color mode of the first embodiment on the display 1B of the second embodiment. Specifically, when the fourth color mode is selected, the control unit 3B of the second embodiment first generates three-color composite patterns GA (R), GA (G), and GA (B). After that, as shown in FIG. 12, the control unit 3B sequentially switches between the first color display period, the second color display period, and the third color display period to display color images G1 to G3 on the display surfaces P1 to P3, respectively. That is, during the first color display period, while outputting red light from the light source 11R, the spatial phase modulator 13 is controlled based on the composite pattern GA (R) for red to display red images G1 to G3 on the display surfaces P1 to P3. During the second color display period, while outputting green light from the light source 11G, the spatial phase modulator 13 is controlled based on the composite pattern GA (G) for green to display green images G1 to G3 on the display surfaces P1 to P3. During the third color display period, blue light is output from the light source 11B, and the spatial phase modulator 13 is controlled based on the blue composite pattern GA(B) to display blue images G1-G3 on the display surfaces P1-P3.

In the fourth color mode, the control unit 3B performs color matching of the images G1 to G3 based on the output control of the three color light sources 11R, 11G, and 11B. For example, while turning on the light sources 11R, 11G, and 11B in advance in a predetermined time division manner, it obtains the output values of the light sources 11R, 11G, and 11B of each color that can display the reference white color, and controls the drive of the light sources 11R, 11G, and 11B to achieve the obtained output values.

The fifth color mode is a display mode for realizing a color display equivalent to the second color mode of the first embodiment on the display 1B of the second embodiment. The sixth color mode is a display mode for realizing a color display equivalent to the third color mode of the first embodiment on the display 1B of the second embodiment. Note that the color matching processes of the fifth color mode and the sixth color mode are similar, so illustration and description of the fifth color mode will be omitted.

When the sixth color mode is selected, the control unit 3B first generates the first to third image formation patterns G13 to G33 for three colors. After that, as shown in FIG. 13, the control unit 3B sequentially switches between the first color display period, the second color display period, and the third color display period to display color images G1 to G3 on the display surfaces P1 to P3. That is, during the first color display period, while outputting red light from the light source 11R, the spatial phase modulator 13 is controlled in a time-division manner based on the red image formation patterns G13(R) to G33(R) to display red images G1 to G3 on the display surfaces P1 to P3. During the second color display period, while outputting green light from the light source 11G, the spatial phase modulator 13 is controlled in a time-division manner based on the green image formation patterns G13(G) to G33(G) to display green images G1 to G3 on the display surfaces P1 to P3. During the third color display period, blue light is output from the light source 11B, and the spatial phase modulator 13 is controlled based on the blue image forming patterns G13(B) to G33(B) to display blue images G1 to G3 on the display surfaces P1 to P3.

In the sixth color mode, the control unit 3B performs color matching of the images G1 to G3 based on the output control of the three color light sources 11R, 11G, and 11B. For example, while turning on the light sources 11R, 11G, and 11B in advance in a predetermined time division manner, it obtains the output values of the light sources 11R, 11G, and 11B of each color that can display the reference white color, and controls the drive of the light sources 11R, 11G, and 11B to achieve the obtained output values.

However, in the fifth and sixth color modes, the display period assigned to each image forming pattern G13 to G33 is shorter than in the fourth color mode. Therefore, there is a possibility that the luminance balance between the images G1 to G3 cannot be adjusted by simply changing the time division ratio or adding dummy patterns DP1 to DP3. Therefore, when the fifth or sixth color mode is selected, the control unit 3B switches the output of the light sources 11R, 11G, and 11B each time the image forming patterns G13 to G33 are switched sequentially in a time division manner, as shown in FIG. 14. This adjusts the luminance of the images G1 to G3 secondarily. Such a second-order adjustment of luminance makes it possible to more appropriately suppress the luminance imbalance between the images G1 to G3.

[Third and Fourth Examples]
Next, a third and fourth embodiment of the present invention will be described with reference to Figures 15 and 16. However, for configurations common to the first and second embodiments, the same reference numerals as in the first and second embodiments are used, and the description of the first and second embodiments may be used.

The displays 1 and 1B of the first and second embodiments have a configuration suitable for a projection type display device, whereas the displays 1C and 1D of the third and fourth embodiments have a configuration suitable for a direct viewing type display device. For example, the displays 1C and 1D of the third and fourth embodiments can be suitably used in a direct viewing type head-up display device.

In the direct viewing method, the closer the distance between the eyes of the passenger P and the real image IM (IM_R + IM_G + IM_B), the wider the eyebox becomes, which is advantageous in terms of visibility. For example, in the display 1C of the third embodiment, as shown in FIG. 15, the real images IM_R, IM_G, and IM_B of each color are formed on the same surface behind the dichroic mirror 17. In addition, in the display 1D of the fourth embodiment, the real images IM_R, IM_G, and IM_B of each color are formed on the same surface behind the unnecessary light cut mask 18. These image formation positions are close to the eyes of the passenger P, and the passenger P can clearly see the images G1 to G3 through the half mirror HM over the real image IM.

The display 1C of the third embodiment also has an unnecessary light cut mask 18C for cutting unnecessary light. The unnecessary light cut mask 18C of the third embodiment is provided between the telescope optical system 15 of the three monochromatic optical systems 19R, 19G, and 19B and the dichroic mirror 17. The number of unnecessary light cut masks 18C required in the third embodiment is three, but by interposing the dichroic mirror 17 between the real image IM and the unnecessary light cut mask 18C, a predetermined distance or more can be secured between the real image IM and the unnecessary light cut mask 18C. The control unit 3C of the third embodiment executes substantially the same process as the control unit 3 of the first embodiment, and the control unit 3D of the fourth embodiment executes substantially the same process as the control unit 3B of the second embodiment.

Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes are possible within the scope of the claims. It is also possible to combine all or a combination of multiple components of the above-mentioned embodiments.

For example, in the first to fourth embodiments, the display device of the present invention is described as a head-up display. However, the projection-type display device shown in the first and second embodiments may be applied to a head-mounted display that is worn on the viewer's head, or a road projector that projects an image onto the road surface. Also, the direct-view type display device shown in the third and fourth embodiments may be applied to a head-mounted display.

H Head-up display device (display device)
1, 1B, 1C, 1D Display 2 Reflector 3 Control unit 31 Controller IC
32 Driver IC
33 CGH engine 4 Case 41 Exit port 11 (11R, 11G, 11B) Light source 12 Collimator section 13 Spatial phase modulator 14 Half mirror 15 Telescope optical system 151, 152 Lens 16 Zero-order light cut mask 17, 17B Dichroic mirror 18, 18C Unwanted light cut mask 181 Opening 19 (19R, 19G, 19B) Monochromatic optical system IM (IM_R, IM_G, IM_B) Real images G1 to G3 Images P1 to P3 Display surface

Claims (9)

A light source that outputs light;
a spatial phase modulator that diffracts the light output from the light source and forms image light including interference fringes based on a computer-generated hologram;
an unnecessary light cut mask that cuts unnecessary light in a non-display area from the image light output from the spatial phase modulator;
A display device comprising: a control unit that controls the light source and the spatial phase modulator; and a display device that displays different images on a plurality of display surfaces having different illumination distances,
The control unit is
a pattern generating means for generating a first image forming pattern for forming a first image to be displayed on a first display surface by the spatial phase modulator, and a second image forming pattern for forming a second image to be displayed on a second display surface by the spatial phase modulator;
a pattern synthesizing means for generating a composite pattern of the first image forming pattern and the second image forming pattern;
a multiple image display means for controlling the spatial phase modulator based on the composite pattern to display the first image on the first display surface and the second image on the second display surface,
The pattern generating means adds a dummy pattern to the non-display area so that a sum of gradation values of all pixels of the first image forming pattern matches a sum of gradation values of all pixels of the second image forming pattern. A light source that outputs light;
a spatial phase modulator that diffracts the light output from the light source and forms image light including interference fringes based on a computer-generated hologram;
an unnecessary light cut mask that cuts unnecessary light in a non-display area from the image light output from the spatial phase modulator;
A display device comprising: a control unit that controls the light source and the spatial phase modulator; and a display device that displays different images on a plurality of display surfaces having different illumination distances,
The control unit is
a pattern generating means for generating a first image forming pattern for forming a first image to be displayed on a first display surface by the spatial phase modulator, and a second image forming pattern for forming a second image to be displayed on a second display surface by the spatial phase modulator;
a multiple image display means for controlling the spatial phase modulator based on the first image forming pattern and the second image forming pattern to display the first image on the first display surface and the second image on the second display surface,
the multiple image display means calculates a product of an image area and a gradation value of the first image formation pattern and a product of an image area and a gradation value of the second image formation pattern, and a ratio between these products, and sequentially switches between the first image formation pattern and the second image formation pattern in a time division manner based on the ratio. The display device according to claim 2, wherein the pattern generating means adds a dummy pattern to the non-display area so that the ratio is uniform. a first light source that outputs light of a first color;
a first spatial phase modulator that diffracts the first color light and displays an image including an interference pattern based on a computer-generated hologram;
a second light source that outputs light of a second color;
a second spatial phase modulator that diffracts the second color light and displays an image including an interference pattern based on a computer-generated hologram;
the control unit generates the composite pattern of the first color and the composite pattern of the second color, and then controls the first spatial phase modulator and the second spatial phase modulator based on the composite pattern of the first color and the second color to display the first image consisting of the first color and the second color on the first display surface and the second image consisting of the first color and the second color on the second display surface, respectively;
The display device according to claim 1 , wherein the control unit further comprises a color matching unit that performs color matching of the first image and the second image based on an output control of the first light source and the second light source. a first light source that outputs light of a first color;
a first spatial phase modulator that diffracts the first color light and displays an image including an interference pattern based on a computer-generated hologram;
a second light source that outputs light of a second color;
a second spatial phase modulator that diffracts the second color light and displays an image including an interference pattern based on a computer-generated hologram;
the control unit generates the first image forming pattern of the first color and the second color and the second image forming pattern of the first color and the second color, and then controls the first spatial phase modulator and the second spatial phase modulator based on the first image forming pattern of the first color and the second color and the second image forming pattern of the first color and the second color to display the first image consisting of the first color and the second color on the first display surface and the second image consisting of the first color and the second color on the second display surface, respectively;
4. The display device according to claim 2, further comprising a color matching unit configured to perform color matching of the first image and the second image based on an output control of the first light source and the second light source. The display device according to claim 5, further comprising a secondary brightness adjustment means for adjusting the brightness of the first image and the second image by switching the output of the first light source and the second light source at each switching when the first image formation pattern and the second image formation pattern are sequentially switched in a time division manner based on the ratio. a first light source that outputs light of a first color;
a second light source that outputs light of a second color,
the control unit generates the composite pattern of the first color and the composite pattern of the second color, and then sequentially switches between a first color display period in which the control unit controls the spatial phase modulator based on the composite pattern of the first color while outputting light of the first color from the first light source to display the first image of the first color on the first display screen and the second image of the first color on the second display screen, and a second color display period in which the control unit controls the spatial phase modulator based on the composite pattern of the second color while outputting light of the second color from the second light source to display the first image of the second color on the first display screen and the second image of the second color on the second display screen, thereby displaying the first image consisting of the first color and the second color on the first display screen and the second image consisting of the first color and the second color on the second display screen,
The display device according to claim 1 , wherein the control unit further comprises a color matching unit that performs color matching of the first image and the second image based on an output control of the first light source and the second light source. a first light source that outputs light of a first color;
a second light source that outputs light of a second color,
the control unit generates the first image forming pattern of the first color and the second color and the second image forming pattern of the first color and the second color, and then controls the spatial phase modulator based on the first image forming pattern and the second image forming pattern of the first color while outputting light of the first color from the first light source to display the first image of the first color on the first display screen and the second image of the first color on the second display screen, respectively, and controls the spatial phase modulator based on the first image forming pattern and the second image forming pattern of the second color while outputting light of the second color from the second light source to display the first image of the second color on the first display screen and the second image of the second color on the second display screen, respectively, by sequentially switching between a first color display period and a second color display period.
4. The display device according to claim 2, further comprising a color matching unit configured to perform color matching of the first image and the second image based on an output control of the first light source and the second light source. The display device according to claim 8, wherein the control unit further comprises a secondary brightness adjustment means for adjusting the brightness of the first image and the second image by switching the output of the first light source and the second light source each time the first image formation pattern and the second image formation pattern are sequentially switched in a time division manner based on the ratio.