Display device and display method

Abstract

To display a three-dimensional higher-definition image.SOLUTION: A display device 10 includes: a display body 12 including phosphors; a light source 30 which outputs excitation light 20 that excites the phosphors; a first lens 38 and a second lens 40 which collect the excitation light 20 toward a light-collection position 22 inside the display body 12; a first driving mechanism 42 which drives the first lens 38 to change the light-collection position 22; and a second driving mechanism 44 which drives the second lens 40 to reduce aberration generated according to the change of the light-collection position 22.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] As a display device for stereoscopic images, a configuration has been proposed in which a display body containing a phosphor is irradiated with ultraviolet light 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). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-165611 A Summary of the Invention [Problem to be solved by the invention]

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

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

[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 present invention is a display method, which includes 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 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.

[0008] 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 as aspects of the present invention. Effect of the Invention

[0009] According to the present invention, a higher definition stereoscopic image can be displayed. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a display device according to a first embodiment. [Diagram 2] 11 is a graph showing an example of spherical aberration depending on the light-collecting position in the example and the comparative example. [Diagram 3] 11 is a graph showing an example of a spot diameter of excitation light depending on a focusing position in an example and a comparative example. [Figure 4] FIG. 11 is a diagram illustrating a schematic configuration of a display device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Specific numerical values ​​and the like shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the drawings, elements that are not directly related to the present invention are omitted. In order to facilitate understanding of the description, the dimensional ratios of each component in each drawing do not necessarily match the actual dimensional ratios.

[0012] (First embodiment) 1 is a diagram illustrating a schematic 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.

[0013] 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 region and an emission wavelength in the visible light region. The material of the phosphor is not particularly limited, but examples include quantum dot phosphors using cesium lead halide perovskite (CsPbX3, X is a halogen and is either Cl, Br, or I, or a mixture of these) and rare earth phosphors using rare earth elements such as europium (Eu), cerium (Ce), and yttrium (Y).

[0014] The display body 12 includes, for example, a medium 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. When 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. Since the display body 12 includes a transparent solid material, it has a portion having a higher refractive index than the surroundings of the display body 12 (for example, air).

[0015] The display body 12 has a first surface 24, a second surface 26, and a side surface 28. The first surface 24 is a surface onto which the excitation light 20 is incident. The second surface 26 is a surface opposite to the surface onto which the excitation light 20 is incident. The side surface 28 extends from the first surface 24 towards the second surface 26. The first surface 24, the second surface 26, and the side surface 28 are made of a material having a higher refractive index than the surroundings (e.g., air), for example, a resin material or a glass material.

[0016] The display body 12 is configured to have, for example, a columnar shape, such as a cylindrical shape, a polygonal prism shape, or a rectangular parallelepiped shape. The display body 12 shown in Fig. 1 has a cylindrical shape. 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 inside of the display body 12 can be seen from the outside.

[0017] 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 about 100 mm to 1000 mm, and the size in the directions perpendicular to the height direction (x direction and y direction) can be about 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.

[0018] 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.

[0019] 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 central wavelength in the range of 300 nm to 400 nm as the excitation light 20. There is no particular limit to the type of light source 30, and for example, a gallium nitride (GaN)-based semiconductor laser or a semiconductor LED (Light Emitting Diode) can be used as the light source 30.

[0020] 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 driving mechanism 42, and a second driving mechanism 44.

[0021] 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 driving mechanism 42 so that the focal length is variable. The second lens 40 corrects aberration (e.g., spherical aberration) occurring at the focusing position 22, and reduces the aberration. The second lens 40 is a variable-focus lens, and is driven by a second driving mechanism 44 so that the focal length is variable. The positions of the first lens 38 and the second lens 40 on the optical axis are fixed.

[0022] 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 driving mechanism 42 or the second driving mechanism 44 is, for example, an electromagnetic actuator or a piezoelectric element that applies pressure to the transparent film, and electrically controls the focal length of the variable focus lens by changing the pressure.

[0023] 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 positive refractive power larger than that of the second lens 40. The first lens 38 provides a variable refractive power required for changing 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, when 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 in the range of 200 mm to 700 mm in air equivalent value.

[0024] The second lens 40 functions as an aberration correction lens for reducing aberration caused by refraction of the excitation light 20 at the first surface 24. Since the display body 12 has a higher refractive index than the surroundings (e.g., air), the excitation light 20 is refracted at the first surface 24, causing 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 inside 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 depending on 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, and the stereoscopic image S can be drawn with higher resolution. The second lens 40 provides a smaller positive refractive power than the first lens 38. In the above-mentioned example, the focal length of the second lens 40 is configured to be variable over 3000 mm.

[0025] 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 the directions along the first surface 24 (x direction and y direction). The scanning optical system 34 includes a scanning mirror 46 and a mirror driving mechanism 48. The scanning mirror 46 reflects the excitation light 20 toward the first surface 24 of the display body 12. The mirror driving mechanism 48 is configured to change the orientation of the scanning mirror 46 in two axes. In the illustrated example, one scanning mirror 46 is used, but a first scanning mirror for scanning in the x direction and a second scanning mirror for scanning in the y direction may be combined.

[0026] The sensor 16 is disposed around the display body 12 and 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 disposed, 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 disposed at a position facing the side surface 28 of the display body 12, or may be disposed in an oblique direction with respect to the display body 12.

[0027] 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 an element or a mechanical device such as a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), or a memory 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 is understood by those skilled in the art that the functional block of the control unit 18 can be realized in various ways by a combination of hardware and software.

[0028] The control unit 18 controls the focusing position 22 of the excitation light 20 three-dimensionally (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, so that the focusing position 22 of the excitation light 20 is scanned three-dimensionally inside the display body 12.

[0029] The control unit 18 controls the operation of the second driving mechanism 44 to reduce the aberration corresponding to the focusing position 22 of the excitation light 20 and reduce the spot diameter of the excitation light 20 at the focusing position 22. The control unit 18 stores in advance table information that associates the focusing position 22 with the first driving amount of the first driving mechanism 42 and the second driving amount of the second driving mechanism 44, for example, and drives the first driving mechanism 42 and the second driving mechanism 44 in accordance with the table information.

[0030] 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 focusing position 22. The control unit 18 may drive the second drive mechanism 44, for example, so that the spot diameter of the excitation light 20 at the focusing position 22 is minimized. 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 at which the spot diameter of the excitation light 20 is minimized. The control unit 18 may store combinations of the determined first drive amount and 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.

[0031] The control unit 18 controls the on / off of the light source 30 according to 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 to be drawn inside the display body 12. The control unit 18 turns off ... not inside the display body 12. 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 drawn on the display body 12 is specified.

[0032] Next, the operation of the display device 10 will be described. The control unit 18 acquires the 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, and three-dimensionally scans the focusing position 22 of the excitation light 20 inside the display body 12, and reduces the aberration according to the focusing position 22.

[0033] 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 that a display specified for each drawing position by the three-dimensional contour image data is realized. In this way, a three-dimensional image S corresponding to the three-dimensional contour image data can 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. In this way, a three-dimensional image S that becomes a video may be displayed.

[0034] 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 occurring in response to the change in the focusing position 22.

[0035] Next, the effects of the present embodiment will be described. FIG. 2 is a graph showing an example of spherical aberration according to the condensing position 22 in the examples and comparative examples. FIG. 3 is a graph showing an example of the spot diameter of the excitation light 20 according to the condensing position 22 in the examples and comparative examples. The examples show a case where the second lens 40 for correcting the aberration is provided, and the comparative examples show a case where the second lens 40 for correcting the aberration is not provided. In the examples and comparative examples, the wavelength of the excitation light 20 is 405 nm, the beam diameter of the excitation light 20 collimated by the collimating lens 36 is 200 mm, the distance along the optical axis from the first lens 38 to the first surface 24 of the display body 12 is 260 mm, and the refractive index of the display body 12 is 1.51. In the examples, the distance from the first lens 38 to the second lens 40 is 30 mm.

[0036] FIG. 2 shows the maximum value of spherical aberration occurring at the focusing position 22. The horizontal axis of the graph shows the position in the depth direction from the first surface 24 toward the second surface 26 when the position of the first surface 24 of the display body 12 is set to 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 becomes deeper. Note that the amount of aberration does not monotonically increase as the focusing position 22 becomes deeper, but shows a tendency to decrease after reaching a maximum at a position where the focusing position 22 is about 300 mm to 400 mm. This is considered to be because the spherical aberration is proportional to the cube of the numerical aperture (NA) of the excitation light 20, and the amount of aberration decreases as the focusing position 22 becomes deeper and the NA becomes smaller. On the other hand, in the embodiment shown by the solid line 52, it can be seen that the amount of aberration can be made 0.1 mm or less regardless of the focusing position 22, and the aberration can be appropriately reduced. In particular, in the range where the light-collecting position 22 is 750 mm or less, the amount of aberration can be reduced to 0.05 mm or less.

[0037] 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 shows the depth direction position from the first surface 24 toward the second surface 26 when the position of the first surface 24 of the display body 12 is set to 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 becomes deeper. Note that the spot diameter does not monotonically increase as the focusing position 22 becomes deeper, but shows a tendency to decrease after reaching a maximum at a position where the focusing position 22 is about 250 mm. The focusing position 22 at about 250 mm can be near the center of the display body 12, but if the spot diameter near the center of the display body 12 is about 200 μm, it is difficult to draw the stereoscopic image S with high resolution, and the stereoscopic image S may become blurred and unclear. On the other hand, in the embodiment shown by the solid line 56, the spot diameter can be made 2 μm or less, which is close to the diffraction limit, regardless of the focusing position 22. This makes it possible to render the stereoscopic image S with high resolution, and a clearer stereoscopic image S can be displayed as compared to the comparative example.

[0038] Second embodiment 4 is a diagram showing a schematic 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 second embodiment will be described below, focusing on the differences from the first embodiment, and descriptions of the commonalities will be omitted as appropriate.

[0039] 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.

[0040] 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 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 the first embodiment described above.

[0041] The first lens 38A focuses the excitation light 20 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 the 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 to change 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.

[0042] 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 according to the light-focus position 22 by changing the focal length according to the light-focus position 22.

[0043] The control unit 18 controls the operation of the second driving mechanism 44 to reduce the aberration corresponding to the focusing position 22 of the excitation light 20 and reduce the spot diameter of the excitation light 20 at the focusing position 22. The control unit 18 stores in advance table information that associates the focusing position 22 with the first driving amount of the first driving mechanism 42A and the second driving amount of the second driving mechanism 44, for example, and drives the first driving mechanism 42A and the second driving mechanism 44 in accordance with the table information.

[0044] In this embodiment as well, the same effects as in the first embodiment can be achieved.

[0045] In the above-described embodiment, the display device 10, 10A includes the sensor 16. In other embodiments, the display device 10, 10A may not include the sensor 16. In this case, the display device 10, 10A may operate the first drive mechanism 42, 42A and the second drive mechanism 44 according to 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.

[0046] 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. [Explanation of symbols]

[0047] 10, 10A... display device, 12... 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.

Claims

1. A display body including a phosphor; a light source that outputs excitation light for exciting the phosphor; a first lens and a second lens that focus the excitation light toward a focusing position inside the display; a first driving mechanism that drives the first lens to change the focusing position; a second driving mechanism that drives the second lens and reduces aberration occurring in response to a change in the focusing position. Display device.

2. the first lens and the second lens are variable focus lenses; the first driving mechanism and the second driving mechanism change a focal length of the focus variable lens; The display device according to claim 1 .

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

4. A sensor for detecting the focusing position; and a control unit that controls an operation of at least one of the first drive mechanism and the second drive mechanism based on a detection result of the sensor. The display device according to claim 1 .

5. A step of collecting excitation light for exciting a phosphor by using a first lens and a second lens toward a light collecting 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 a change in the focusing position. Display method.

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