Display device and display method

Abstract

A display device (10) comprises: a display body (12) that includes a phosphor; a light source (30) that outputs excitation light (20) for exciting the phosphor; a first lens (38) and a second lens (40) that condense the excitation light (20) toward a light collection position (22) inside the display body (12); a first drive mechanism (42) that drives the first lens (38) to change the light collection position (22); and a second drive mechanism (44) that drives the second lens (40) to reduce aberration caused by the change of the light collection position (22).

Description

Display device and display method

[0001] The present invention relates to a display device and a display method.

[0002] As a display device for stereoscopic images, a configuration has been proposed in which ultraviolet light is irradiated onto a display body containing a phosphor, and a stereoscopic image is drawn inside the display body by changing the irradiation position of the ultraviolet light (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2015-165611

[0004] It is preferable to be able to display a stereoscopic image with higher definition.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a technique for displaying higher-definition stereoscopic images.

[0006] A display device according to one embodiment of the present invention comprises a display body containing a phosphor, a light source that outputs excitation light that excites the phosphor, a first lens and a second lens that focus the excitation light toward a focusing position inside the display body, a first drive mechanism that drives the first lens to change the focusing position, and a second drive mechanism that drives the second lens to reduce aberrations that arise in response to changes in the focusing position.

[0007] Another aspect of the display device of the present invention includes a display body containing a phosphor and having a concave curved surface, a light source that outputs excitation light that excites the phosphor, a scan mirror that reflects the excitation light toward the concave curved surface, and a mirror drive mechanism that drives the scan mirror to change the incident position of the excitation light on the concave curved surface.

[0008] Yet another aspect of the present invention is a display method, comprising the steps of: using a first lens and a second lens to focus excitation light for exciting a phosphor toward a focusing position inside a display body containing the phosphor, driving the first lens to change the focusing position, and driving the second lens to reduce aberrations occurring in response to the change in the focusing position.

[0009] Yet another aspect of the present invention is a display method, comprising the steps of reflecting excitation light, which excites a phosphor, toward a concave curved surface of a display body containing the phosphor using a scan mirror, and driving the scan mirror to change the incident position of the excitation light on the concave curved surface.

[0010] Any combination of the above components or mutual substitution of the components or expressions of the present invention between methods, devices, systems, etc. are also valid aspects of the present invention.

[0011] According to the present invention, a higher-definition stereoscopic image can be displayed.

[0012] FIG. 1 is a diagram schematically showing the configuration of a display device according to a first embodiment; FIG. 2 is a graph showing an example of spherical aberration depending on the focusing position according to an example and a comparative example; FIG. 3 is a graph showing an example of spot diameter of excitation light depending on the focusing position according to an example and a comparative example; FIG. 4 is a diagram schematically showing the configuration of a display device according to a second embodiment; FIG. 5 is a diagram schematically showing the configuration of a display device according to a third embodiment; FIG. 6 is a graph showing an example of spherical aberration depending on the focusing position according to an example and a comparative example; and FIG. 7 is a graph showing an example of spot diameter of excitation light depending on the focusing position according to an example and a comparative example.

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Specific numerical values ​​and the like shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. Elements not directly related to the present invention are omitted from the drawings. To facilitate understanding of the description, the dimensional ratios of the components in the drawings do not necessarily correspond to the actual dimensional ratios.

[0014] 1 is a diagram schematically illustrating the configuration of a display device 10 according to a first embodiment. The display device 10 includes a display body 12, an irradiation unit 14, a sensor 16, and a control unit 18. The display device 10 is a so-called volume display, and is configured to render a three-dimensional image S inside the display body 12.

[0015] The display 12 includes a phosphor that emits light when irradiated with excitation light 20. The phosphor has an excitation wavelength in the ultraviolet light range and an emission wavelength in the visible light range. The material of the phosphor is not particularly limited, but for example, cesium lead halide perovskite (CsPbX ３ , X is a halogen, and is one of Cl, Br, I, or a mixture thereof), or a rare earth phosphor using a rare earth element such as europium (Eu), cerium (Ce), or yttrium (Y).

[0016] The display body 12 includes, for example, a medium that is transparent to visible light and a phosphor dispersed in the medium. The medium may be a solid such as resin or glass, a liquid such as toluene, or a gas. If the medium is a liquid or gas, the display body 12 may include a transparent container for containing the medium. The transparent container may be made of a resin material or a glass material. Because the display body 12 includes a transparent solid material, it has a portion with a higher refractive index than the surroundings of the display body 12 (e.g., air).

[0017] The display body 12 has a first surface 24, a second surface 26, and a side surface 28. The first surface 24 is the surface onto which the excitation light 20 is incident. The second surface 26 is the surface opposite to the surface onto which the excitation light 20 is incident. The side surface 28 extends from the first surface 24 toward the second surface 26. The first surface 24, the second surface 26, and the side surface 28 are made of a material with a higher refractive index than the surroundings (e.g., air), such as a resin material or a glass material.

[0018] The display body 12 is configured to have, for example, a columnar shape, such as a cylindrical, polygonal prism, or rectangular parallelepiped shape. The display body 12 shown in Fig. 1 is cylindrical. The display body 12 is configured so that the surfaces (first surface 24, second surface 26, and side surface 28) of the display body 12 are mirror-finished so that the interior of the display body 12 can be seen from the outside.

[0019] The size of the display body 12 is not particularly limited, but for example, the size in the height direction (z direction) from the first surface 24 to the second surface 26 can be approximately 100 mm to 1000 mm, and the size in the directions perpendicular to the height direction (x direction and y direction) can be approximately 100 mm to 1000 mm. As an example, the size of the display body 12 in the x, y, and z directions can be 500 mm.

[0020] The irradiation unit 14 irradiates the display body 12 with excitation light 20 for exciting the phosphor contained in the display body 12. The excitation light 20 is incident on a first surface 24 of the display body 12 and is focused toward a focusing position 22 inside the display body 12. The excitation light 20 is irradiated so that the focusing position 22 inside the display body 12 changes over time. The irradiation unit 14 includes a light source 30, a focusing optical system 32, and a scanning optical system 34.

[0021] The light source 30 generates excitation light 20 for exciting the phosphor contained in the display 12. The light source 30 generates, for example, ultraviolet light having a center wavelength in the range of 300 nm to 400 nm as the excitation light 20. Any type of light source 30 can be used, but for example, a gallium nitride (GaN) semiconductor laser or a semiconductor light-emitting diode (LED) can be used as the light source 30.

[0022] The focusing optical system 32 focuses the excitation light 20 generated by the light source 30 toward the inside of the display body 12. The focusing optical system 32 changes the focusing position 22 in the irradiation direction of the excitation light 20, and makes the focusing position 22 variable in a direction intersecting with the first surface 24. The focusing optical system 32 includes a collimator lens 36, a first lens 38, a second lens 40, a first drive mechanism 42, and a second drive mechanism 44.

[0023] The collimating lens 36 collimates the excitation light 20 generated by the light source 30. The first lens 38 focuses the excitation light 20 collimated by the collimating lens 36 toward the inside of the display body 12. The first lens 38 is a variable-focus lens, and is driven by a first drive mechanism 42 so that its focal length is variable. The second lens 40 corrects and reduces aberrations (e.g., spherical aberrations) that occur at the focusing position 22. The second lens 40 is a variable-focus lens, and is driven by a second drive mechanism 44 so that its focal length is variable. The positions of the first lens 38 and the second lens 40 on the optical axis are fixed.

[0024] The variable-focus lens used as the first lens 38 or the second lens 40 is, for example, a liquid lens, and is configured so that the focal length can be changed by deforming a flexible transparent film that seals the liquid lens. The shape of the transparent film is controlled by changing the pressure applied to the transparent film. The first drive mechanism 42 or the second drive mechanism 44 is, for example, an electromagnetic actuator or a piezoelectric element that applies pressure to the transparent film, and the focal length of the variable-focus lens is electrically controlled by changing the pressure.

[0025] The first lens 38 functions as a focusing lens for focusing the parallel light at the focusing position 22. The first lens 38 provides a larger positive refractive power than the second lens 40. The first lens 38 provides a variable refractive power required to change the focusing position 22 (focal position) of the excitation light 20 over a range from the first surface 24 to the second surface 26. As an example, if the distance along the optical axis from the first lens 38 to the first surface 24 is 200 mm and the height from the first surface 24 to the second surface 26 is 500 mm, the focal length of the first lens 38 is configured to be variable over a range of 200 mm to 700 mm in air equivalent value.

[0026] The second lens 40 functions as an aberration correction lens for reducing aberrations caused by refraction of the excitation light 20 at the first surface 24. Because the display body 12 has a refractive index higher than that of the surroundings (e.g., air), refracting the excitation light 20 at the first surface 24 causes over-spherical aberration at the focusing position 22. The magnitude of this spherical aberration varies depending on the transmission distance (optical path length) of the excitation light 20 within the display body 12, and the spherical aberration tends to increase as the transmission distance increases. As a result, the amount of aberration correction required varies depending on the focusing position 22 of the excitation light 20. The second lens 40 reduces the spherical aberration corresponding to the focusing position 22 by changing the focal length depending on the focusing position 22. By reducing the aberration at the focusing position 22, the spot diameter of the excitation light 20 at the focusing position 22 can be reduced, allowing the three-dimensional image S to be displayed with higher resolution. The second lens 40 provides a smaller positive refractive power than the first lens 38. In the above example, the focal length of the second lens 40 is configured to be variable over a range of 3000 mm or more.

[0027] The scanning optical system 34 scans the excitation light 20 that has passed through the focusing optical system 32, and changes the focusing position 22 of the excitation light 20 in directions (x and y directions) along the first surface 24. The scanning optical system 34 includes a scan mirror 46 and a mirror drive mechanism 48. The scan mirror 46 reflects the excitation light 20 toward the first surface 24 of the display body 12. The mirror drive mechanism 48 is configured to change the orientation of the scan mirror 46 along two axes. In the example shown in the figure, a single scan mirror 46 is used, but a first scan mirror for scanning in the x direction and a second scan mirror for scanning in the y direction may be combined.

[0028] The sensor 16 is arranged around the display body 12 and is configured to detect the light collection position 22. The sensor 16 is, for example, a two-dimensional photodetector such as a CCD sensor or a CMOS sensor, and is a camera that captures an image of the display body 12. The sensor 16 is arranged, for example, at a position facing the second surface 26 of the display body 12. The position of the sensor 16 is not particularly important, and the sensor 16 may be arranged at a position facing the side surface 28 of the display body 12, or may be arranged at an angle to the display body 12.

[0029] The control unit 18 controls the operation of the irradiation unit 14. The control unit 18 may be realized by a combination of hardware and software. The hardware of the control unit 18 may be realized by elements or mechanical devices such as a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), and memories such as a ROM (Read Only Memory) or a RAM (Random Access Memory). The software of the control unit 18 may be realized by a computer program or the like. In this case, the control unit 18 is depicted as a functional block realized by the cooperation of hardware and software. It will be understood by those skilled in the art that the functional blocks of the control unit 18 can be realized in various ways by combining hardware and software.

[0030] The control unit 18 controls the focusing position 22 of the excitation light 20 in three dimensions (x direction, y direction, and z direction) by controlling the operation of the first driving mechanism 42 and the mirror driving mechanism 48. The control unit 18 periodically operates the first driving mechanism 42 and the mirror driving mechanism 48, thereby causing the focusing position 22 of the excitation light 20 to be scanned three-dimensionally inside the display body 12.

[0031] The control unit 18 controls the operation of the second drive mechanism 44 to reduce the aberration corresponding to the focus position 22 of the excitation light 20 and reduce the spot diameter of the excitation light 20 at the focus position 22. The control unit 18 stores in advance table information that associates the focus position 22 with the first drive amount of the first drive mechanism 42 and the second drive amount of the second drive mechanism 44, for example, and drives the first drive mechanism 42 and the second drive mechanism 44 in accordance with the table information.

[0032] The control unit 18 may control the operation of at least one of the first drive mechanism 42 and the second drive mechanism 44 based on the detection result of the sensor 16 that detects the light-focus position 22. The control unit 18 may, for example, drive the second drive mechanism 44 so as to minimize the spot diameter of the excitation light 20 at the light-focus position 22. The control unit 18 may change the first drive amount in stages, detect the spot diameter of the excitation light 20 for each first drive amount using the sensor 16, and determine the second drive amount that minimizes the spot diameter of the excitation light 20. The control unit 18 may store the determined combinations of the first drive amount and the second drive amount as table information and drive the first drive mechanism 42 and the second drive mechanism 44 in accordance with the stored table information.

[0033] The control unit 18 controls the on / off of the light source 30 in accordance with the focusing position 22 of the excitation light 20. The control unit 18 turns on the light source when the focusing position 22 of the excitation light 20 is a location inside the display body 12 where rendering should be performed. The control unit 18 turns off the light source when the focusing position 22 of the excitation light 20 is a location inside the display body 12 where rendering should not be performed. The control unit 18 controls the on / off and emission intensity of the light source 30 based on, for example, three-dimensional contour image data generated from the three-dimensional image data. The three-dimensional contour image data is data in which the three-dimensional position of the contour of the three-dimensional image S to be rendered on the display body 12 is specified.

[0034] Next, the operation of the display device 10 will be described. The control unit 18 acquires three-dimensional contour image data and operates the irradiation unit 14 based on the three-dimensional contour image data. The control unit 18 controls the operations of the first drive mechanism 42, the second drive mechanism 44, and the mirror drive mechanism 48 to three-dimensionally scan the focusing position 22 of the excitation light 20 inside the display body 12 and reduce aberrations corresponding to the focusing position 22.

[0035] The control unit 18 controls the output intensity of the light source 30 according to the focusing position 22 of the excitation light 20, so as to realize a display specified for each drawing position by the three-dimensional contour image data. This allows a three-dimensional image S corresponding to the three-dimensional contour image data to be drawn inside the display body 12. The control unit 18 may obtain three-dimensional contour image data corresponding to each frame of the video data, so that a different three-dimensional image S is drawn for each frame. This may allow a three-dimensional image S to be displayed as a video.

[0036] The display method according to this embodiment includes the steps of focusing excitation light 20 toward a focusing position 22 inside the display body 12 using a first lens 38 and a second lens 40, driving the first lens 38 to change the focusing position 22, and driving the second lens 40 to reduce aberrations that arise in response to the change in the focusing position 22.

[0037] Next, the effects of this embodiment will be described. FIG. 2 is a graph showing an example of spherical aberration as a function of the focusing position 22 in an example and a comparative example. FIG. 3 is a graph showing an example of spot diameter of the excitation light 20 as a function of the focusing position 22 in an example and a comparative example. The example shows a case where a second lens 40 for correcting aberration is provided, while the comparative example shows a case where a second lens 40 for correcting aberration is not provided. In the example and the comparative example, the wavelength of the excitation light 20 is 405 nm, the beam diameter of the excitation light 20 collimated by the collimator lens 36 is 200 mm, the distance along the optical axis from the first lens 38 to the first surface 24 of the display 12 is 260 mm, and the refractive index of the display 12 is 1.51. In the example, the distance from the first lens 38 to the second lens 40 is 30 mm.

[0038] FIG. 2 shows the maximum value of spherical aberration occurring at the focusing position 22. The horizontal axis of the graph indicates the depth from the first surface 24 toward the second surface 26 of the display 12, with the first surface 24 positioned at 0 mm. In the comparative example shown by the dashed line 50, it can be seen that the amount of aberration increases as the focusing position 22 deepens. Note that the amount of aberration does not monotonically increase as the focusing position 22 deepens; rather, it tends to peak at a focusing position 22 of approximately 300 mm to 400 mm and then decrease. This is thought to be because spherical aberration is proportional to the cube of the numerical aperture (NA) of the excitation light 20, and therefore, as the focusing position 22 deepens and the NA decreases, the amount of aberration decreases. On the other hand, in the example shown by the solid line 52, the amount of aberration can be kept below 0.1 mm regardless of the focusing position 22, demonstrating that the aberration is appropriately reduced. In particular, in the range where the light-condensing position 22 is 750 mm or less, the amount of aberration can be reduced to 0.05 mm or less.

[0039] FIG. 3 shows the spot diameter (RMS, root mean square) of the excitation light 20 at the focusing position 22. As in FIG. 2 , the horizontal axis of the graph indicates the depth from the first surface 24 toward the second surface 26 of the display body 12, with the first surface 24 positioned at 0 mm. In the comparative example shown by the dashed line 54, it can be seen that the spot diameter increases as the focusing position 22 deepens. Note that the spot diameter does not monotonically increase as the focusing position 22 deepens, but rather tends to decrease after reaching a maximum at a focusing position 22 of approximately 250 mm. The focusing position 22 of approximately 250 mm may be near the center of the display body 12. However, if the spot diameter near the center of the display body 12 is approximately 200 μm, it may be difficult to render a three-dimensional image S with high resolution, resulting in a blurred and unclear three-dimensional image S. On the other hand, in the example shown by the solid line 56, the spot diameter can be kept below 2 μm, close to the diffraction limit, regardless of the focusing position 22. This makes it possible to draw the three-dimensional image S with high resolution, and a clearer three-dimensional image S can be displayed compared to the comparative example.

[0040] Second Embodiment Fig. 4 is a diagram schematically illustrating the configuration of a display device 10A according to a second embodiment. The second embodiment differs from the first embodiment in that the first lens 38A is not a variable-focus lens but a fixed-focus lens that is movable in the optical axis direction 60. The following description of the second embodiment will focus on the differences from the first embodiment, and will omit a description of the commonalities as appropriate.

[0041] The display device 10A includes a display 12, an irradiation unit 14A, a sensor 16, and a control unit 18. The display 12, the sensor 16, and the control unit 18 can be configured in the same manner as in the first embodiment described above.

[0042] The irradiation unit 14A includes a light source 30, a condensing optical system 32A, and a scanning optical system 34. The light source 30 and the scanning optical system 34 can be configured similarly to those in the first embodiment described above. The condensing optical system 32A includes a collimating lens 36, a first lens 38A, a second lens 40, a first driving mechanism 42A, and a second driving mechanism 44. The collimating lens 36, the second lens 40, and the second driving mechanism 44 can be configured similarly to those in the first embodiment described above.

[0043] The first lens 38A focuses the excitation light 20, which has been collimated by the collimator lens 36, toward the inside of the display body 12. The first lens 38A is a fixed-focus lens, and is driven by a first drive mechanism 42A so that its position in the optical axis direction 60 is variable. The first drive mechanism 42A is configured to change the position of the first lens 38A in the optical axis direction 60. The first drive mechanism 42A changes the position of the first lens 38A, thereby changing the focusing position 22 of the excitation light 20. The first drive mechanism 42A changes the focusing position 22 in the irradiation direction of the excitation light 20, and changes the focusing position 22 in a direction intersecting the first surface 24.

[0044] Unlike the first lens 38A, the second lens 40 has a fixed position in the optical axis direction 60. The second lens 40 is a variable-focus lens, and reduces spherical aberration corresponding to the light-focus position 22 by changing the focal length according to the light-focus position 22.

[0045] The control unit 18 controls the operation of the second drive mechanism 44 to reduce the aberration corresponding to the focus position 22 of the excitation light 20 and reduce the spot diameter of the excitation light 20 at the focus position 22. The control unit 18 stores in advance table information that associates the focus position 22 with the first drive amount of the first drive mechanism 42A and the second drive amount of the second drive mechanism 44, for example, and drives the first drive mechanism 42A and the second drive mechanism 44 in accordance with the table information.

[0046] In this embodiment, the same effects as in the first embodiment can be achieved.

[0047] 5 is a diagram schematically illustrating the configuration of a display device 10B according to a third embodiment. The third embodiment differs from the first embodiment described above in that the first surface 24B of the display body 12B is configured to have a concave curved surface 62. The following description of the third embodiment will focus on the differences from the first embodiment, and will omit a description of the commonalities as appropriate.

[0048] The display device 10B includes a display 12B, an irradiation unit 14, a sensor 16, and a control unit 18. The irradiation unit 14, the sensor 16, and the control unit 18 can be configured in the same manner as in the first embodiment described above.

[0049] The display body 12B has a first surface 24B, a second surface 26, and a side surface 28. Fig. 5 shows a cross section of the display body 12B in the xz plane. The first surface 24B has a concave curved surface 62 onto which the excitation light 20 is incident. The display body 12B can be configured in the same manner as the display body 12 according to the first embodiment, except that the concave curved surface 62 is provided on the first surface 24B.

[0050] The concave curved surface 62 has a shape in which the distance R from the scan mirror 46 is constant, and is configured, for example, as a spherical surface centered on the scan mirror 46. As a result, even if the irradiation direction of the excitation light 20 is inclined from the z direction, the excitation light 20 can be made to be perpendicularly incident on the concave curved surface 62. In other words, even if the incident position 64 of the excitation light 20 on the concave curved surface 62 changes when the scan mirror 46 is driven, the excitation light 20 can be made to be perpendicularly incident on the concave curved surface 62 regardless of the change in the incident position 64. This makes it possible to reduce aberrations (e.g., astigmatism and coma) that occur when the excitation light 20 is obliquely incident on the first surface of the display.

[0051] For example, when the scan mirror 46 includes a first scan mirror and a second scan mirror, the concave curved surface 62 may have a first curvature in a first direction (e.g., the x direction) that is different from a second curvature in a second direction (e.g., the y direction). For example, when the first scan mirror scans the excitation light 20 in the first direction (e.g., the x direction), the radius of curvature of the concave curved surface 62 in the first direction may be equal to a first distance from the first scan mirror to the concave curved surface 62. When the second scan mirror scans the excitation light 20 in the second direction (e.g., the y direction), the radius of curvature of the concave curved surface 62 in the second direction may be equal to a second distance from the second scan mirror to the concave curved surface 62. When the excitation light 20 is reflected by the first scan mirror, then reflected by the second scan mirror, and then incident on the concave curved surface 62, the first distance is greater than the second distance, so the concave curved surface 62 is configured so that the radius of curvature in the first direction is greater than the radius of curvature in the second direction. The concave curved surface 62 may be configured to be, for example, an ellipsoidal surface, so that even if the first scan mirror and the second scan mirror are driven to change the incident position 64 of the excitation light 20 on the concave curved surface 62, the excitation light 20 can be incident perpendicularly on the concave curved surface 62 regardless of the change in the incident position 64.

[0052] The display method according to this embodiment includes the steps of reflecting excitation light 20, which excites a phosphor, using a scan mirror 46 toward a concave curved surface 62 of a display body 12B containing the phosphor, and driving the scan mirror 46 to change an incident position 64 of the excitation light 20 on the concave curved surface 62. The display method may further include the step of driving the first lens 38 to change the focusing position 22. The display method may further include the step of driving the second lens 40 to reduce aberrations occurring in accordance with the change in the focusing position 22.

[0053] Next, the effects of this embodiment will be described. FIG. 6 is a graph showing an example of coma aberration as a function of the focusing position 22 for an example and a comparative example. FIG. 7 is a graph showing an example of the spot diameter of the excitation light 20 as a function of the focusing position 22 for an example and a comparative example. The first example, indicated by solid lines 70 and 76, shows a case in which a concave curved surface 62 is provided on the first surface 24B of the display body 12B and a second lens 40 for correcting aberrations is provided. The second example, indicated by dashed and dotted lines 68 and 74, shows a case in which a concave curved surface 62 is provided on the first surface 24B of the display body 12B but a second lens 40 for correcting aberrations is not provided. The comparative example, indicated by dashed lines 66 and 72, shows a case in which the first surface 24 of the display body 12 is a flat surface and a second lens 40 for correcting aberrations is not provided, similar to the comparative example according to the first embodiment.

[0054] In the first example, the second example, and the comparative example, the wavelength of the excitation light 20 is 405 nm, the beam diameter of the excitation light 20 collimated by the collimator lens 36 is 100 mm, and the refractive index of the display body 12B is 1.51. In the first and second examples, the distance from the scan mirror 46 to the concave curved surface 62 is 100 mm, and the radius of curvature of the concave curved surface 62 is 100 mm. In the first example, the distance from the first lens 38 to the second lens 40 is 30 mm.

[0055] FIG. 6 shows the maximum value of coma aberration occurring at the light-condensing position 22. The horizontal axis of the graph indicates the depth from the first surface 24 or the concave curved surface 62 toward the second surface 26 of the display body 12B, with the position of the first surface 24 or the concave curved surface 62 being 0 mm. In the comparative example shown by the dashed line 66, it can be seen that the amount of aberration increases as the light-condensing position 22 becomes deeper. In the second example shown by the dashed line 68, it can be seen that the amount of aberration is reduced compared to the comparative example. In the first example shown by the solid line 70, it can be seen that the amount of aberration is reduced to almost zero (for example, 1 μm or less) by combining the second lens 40 for correcting aberration.

[0056] FIG. 7 shows the spot diameter (RMS, root mean square) of the excitation light 20 at the focusing position 22. As in FIG. 6 , the horizontal axis of the graph indicates the depth from the first surface 24 or the concave curved surface 62 of the display body 12B toward the second surface 26, with the first surface 24 or the concave curved surface 62 being set at 0 mm. In the comparative example shown by the dashed line 72, it can be seen that the spot diameter increases as the focusing position 22 becomes deeper. In the second example shown by the dotted line 74, it can be seen that the spot diameter is reduced compared to the comparative example. In the first example shown by the solid line 76, the spot diameter can be kept at 2 μm or less, close to the diffraction limit, regardless of the focusing position 22. This enables the three-dimensional image S to be rendered with high resolution, resulting in a clearer three-dimensional image S than in the comparative example.

[0057] The display device 10B according to the third embodiment may include the irradiation unit 14A according to the second embodiment, instead of the irradiation unit 14 according to the first embodiment. That is, the display device 10B may change the depth position of the light-condensing position 22 by changing the position of the first lens 38A in the optical axis direction 60.

[0058] The display device 10B according to the third embodiment may be configured without the second lens 40 and the second drive mechanism 44, and may be configured similarly to the second embodiment shown in Figures 6 and 7. In the case of the second embodiment, the effect of reducing aberration is smaller than in the first embodiment which includes the second lens 40 and the second drive mechanism 44, but the aberration can be reduced and the spot diameter at the light-condensing position 22 can be made smaller than in the comparative example which does not include the concave curved surface 62. This makes it possible to render the three-dimensional image S with high resolution, and to display a clearer three-dimensional image S than in the comparative example.

[0059] In the above-described embodiments, the display devices 10, 10A, and 10B are shown to include the sensor 16. In other embodiments, the display devices 10, 10A, and 10B may not include the sensor 16. In this case, the display devices 10, 10A, and 10B may operate the first drive mechanisms 42, 42A and the second drive mechanism 44 in accordance with table information stored in advance in the control unit 18. The table information may include data indicating the first drive amount and the second drive amount corresponding to the light collection position 22.

[0060] The present invention has been described above with reference to the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments, and appropriate combinations or substitutions of the configurations shown in each display example are also included in the present invention.

[0061] Several aspects of the present disclosure are described below.

[0062] A first aspect of the present disclosure is a display device comprising: a display body including a phosphor; a light source that outputs excitation light that excites the phosphor; a first lens and a second lens that focus the excitation light toward a focusing position inside the display body; a first drive mechanism that drives the first lens to change the focusing position; and a second drive mechanism that drives the second lens to reduce aberrations that occur in response to changes in the focusing position.

[0063] In the first aspect, the first lens and the second lens may be variable-focus lenses, and the first drive mechanism and the second drive mechanism may change the focal length of the variable-focus lenses.

[0064] In a first aspect, the first lens may be a fixed-focus lens, the second lens may be a variable-focus lens, the first drive mechanism may change the position of the fixed-focus lens in the optical axis direction, and the second drive mechanism may change the focal length of the variable-focus lens.

[0065] In the first aspect, the optical system may further include a sensor that detects the focusing position, and a control unit that controls the operation of at least one of the first drive mechanism and the second drive mechanism based on the detection result of the sensor.

[0066] A second aspect of the present disclosure is a display method comprising the steps of: using a first lens and a second lens to focus excitation light that excites a phosphor toward a focusing position inside a display body that includes the phosphor; driving the first lens to change the focusing position; and driving the second lens to reduce aberrations that occur in response to the change in the focusing position.

[0067] A third aspect of the present disclosure is a display device comprising: a display body including a phosphor and having a concave curved surface; a light source that outputs excitation light that excites the phosphor; a scan mirror that reflects the excitation light toward the concave curved surface; and a mirror drive mechanism that drives the scan mirror to change the incident position of the excitation light on the concave curved surface.

[0068] In the third aspect, the concave curved surface may have a shape that keeps a constant distance from the scan mirror.

[0069] In a third aspect, the scan mirror may include a first scan mirror for scanning the excitation light in a first direction and a second scan mirror for scanning the excitation light in a second direction, and the concave curved surface may have a shape in which a first curvature in the first direction and a second curvature in the second direction are different.

[0070] In a third aspect, the display device may further include a first lens and a second lens that focus the excitation light toward a focusing position inside the display body, a first drive mechanism that drives the first lens to change the focusing position, and a second drive mechanism that drives the second lens to reduce aberrations that occur in response to changes in the focusing position.

[0071] A fourth aspect of the present disclosure is a display method comprising the steps of: reflecting excitation light that excites a phosphor toward a concave curved surface of a display body containing the phosphor using a scan mirror; and driving the scan mirror to change the incident position of the excitation light on the concave curved surface.

[0072] According to the present invention, a higher-definition stereoscopic image can be displayed.

[0073] 10, 10A, 10B...display device, 12, 12B...display body, 14, 14A...irradiation unit, 16...sensor, 18...control unit, 20...excitation light, 22...focusing position, 30...light source, 32, 32A...focusing optical system, 34...scanning optical system, 36...collimating lens, 38, 38A...first lens, 40...second lens, 42, 42A...first driving mechanism, 44...second driving mechanism, 46...scanning mirror, 48...mirror driving mechanism, 62...concave curved surface.

Claims

1. A display device comprising: a display body including a phosphor; a light source that outputs excitation light that excites the phosphor; a first lens and a second lens that focus the excitation light toward a focusing position inside the display body; a first drive mechanism that drives the first lens to change the focusing position; and a second drive mechanism that drives the second lens to reduce aberrations that occur in response to changes in the focusing position.

2. The display device according to claim 1, wherein the first lens and the second lens are variable-focus lenses, and the first drive mechanism and the second drive mechanism change the focal length of the variable-focus lenses.

3. The display device according to claim 1, wherein the first lens is a fixed focus lens, the second lens is a variable focus lens, the first drive mechanism changes the position of the fixed focus lens in the optical axis direction, and the second drive mechanism changes the focal length of the variable focus lens.

4. A display device as described in any one of claims 1 to 3, further comprising: a sensor that detects the focusing position; and a control unit that controls the operation of at least one of the first driving mechanism and the second driving mechanism based on the detection result of the sensor.

5. A display device as described in any one of claims 1 to 4, wherein the display body has a concave curved surface onto which the excitation light is incident, and further comprises a scan mirror that reflects the excitation light toward the concave curved surface, and a mirror driving mechanism that drives the scan mirror to change the incident position of the excitation light on the concave curved surface.

6. A display device comprising: a display body including a phosphor and having a concave curved surface; a light source outputting excitation light for exciting the phosphor; a scan mirror reflecting the excitation light toward the concave curved surface; and a mirror drive mechanism driving the scan mirror to change the incident position of the excitation light on the concave curved surface.

7. The display device according to claim 5 or 6, wherein the concave curved surface has a shape such that the distance from the scan mirror is constant.

8. A display device as described in any one of claims 5 to 7, wherein the scan mirror comprises a first scan mirror for scanning the excitation light in a first direction and a second scan mirror for scanning the excitation light in a second direction, and the concave curved surface has a first curvature in the first direction and a second curvature in the second direction that have different shapes.

9. A display method comprising the steps of: using a first lens and a second lens to focus excitation light that excites a phosphor toward a focusing position inside a display body including the phosphor; driving the first lens to change the focusing position; and driving the second lens to reduce aberration occurring in response to the change in the focusing position.

10. A display method comprising the steps of: reflecting excitation light for exciting a phosphor toward a concave curved surface of a display body including the phosphor using a scan mirror; and driving the scan mirror to change the incident position of the excitation light on the concave curved surface.

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