Display device and display method

Abstract

To provide a stereoscopic display technique that does not require an ultrashort pulse laser.SOLUTION: A display unit 10 comprises: a display body 12D obtained by laminating a plurality of fluorescent layers containing phosphor from a first surface 26 toward a second surface 28; a first electrode 66 that is provided on the first surface 26; a second electrode 68 that is provided on the second surface 28; a power supply 70 that applies voltage between the first electrode 66 and the second electrode 68; and a radiation unit 14 that radiates excitation light 20 incident on the display body 12D and exciting the phosphor, while changing a light collecting position 24 of the excitation light 20 in the display body 12D.SELECTED DRAWING: Figure 8

Description

Technical Field

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

Background Art

[0002] As a stereoscopic image display device, a method has been proposed in which a second harmonic wave, which is visible light, is locally generated by irradiating a substance having a second-order nonlinear optical effect with an infrared ultrashort pulse laser (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above prior art, it is necessary to use a laser light source with a pulse width from several tens of picoseconds to several femtoseconds. Since such an ultrashort pulse laser light source is very expensive, it can be an obstacle to the popularization of a stereoscopic display device.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a stereoscopic display technology that does not require an ultrashort pulse laser.

Means for Solving the Problems

[0006] A display device according to an aspect of the present invention includes a display body in which a plurality of phosphor layers containing a phosphor are laminated from a first surface toward a second surface, a first electrode provided on the first surface, a second electrode provided on the second surface, a power supply that applies a voltage between the first electrode and the second electrode, and an irradiation unit that irradiates the display body with excitation light that enters the display body and excites the phosphor while changing a condensing position of the excitation light in the display body.

[0007] Another aspect of the present invention is a display method. This method includes a step of applying a voltage between a first electrode provided on a first surface of a display body in which a plurality of phosphor-containing fluorescent layers are laminated from the first surface toward the second surface, and a second electrode provided on the second surface, and a step of irradiating excitation light that enters the display body and excites the phosphor while changing the condensing position of the excitation light in the display body.

[0008] In addition, any combination of the above components, or those obtained by mutually substituting the components and expressions of the present invention among a method, an apparatus, a system, etc. are also effective as aspects of the present invention.

Advantages of the Invention

[0009] According to the present invention, a three-dimensional display technique that does not require an ultrashort pulse laser can be provided.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

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Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The specific numerical values and the like shown in such embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the drawings, elements not directly related to the present invention are omitted. For the sake of understanding the description, the dimensional ratios of the respective components in each drawing do not necessarily match the actual dimensional ratios.

[0012] (First Embodiment) FIG. 1 is a diagram schematically showing the configuration of a display device 10 according to the first embodiment. The display device 10 includes a display body 12, a first irradiation unit 14, a second irradiation unit 16, and a control unit 18. The display device 10 is a so-called volume display, and is configured to draw a three-dimensional image S inside the display body 12.

[0013] The display body 12 has a first surface 26 and a second surface 28, and includes a plurality of stacked bodies 30 stacked in the z direction from the first surface 26 toward the second surface 28. Each of the plurality of stacked bodies 30 has a first fluorescent layer 31, a second fluorescent layer 32, and a third fluorescent layer 33. The display body 12 has a structure in which a plurality of fluorescent layers are stacked in order, such as the first fluorescent layer 31, the second fluorescent layer 32, the third fluorescent layer 33, the first fluorescent layer 31, the second fluorescent layer 32, the third fluorescent layer 33,.... For example, the plurality of second fluorescent layers 32 are alternately arranged with the plurality of first fluorescent layers 31, and the plurality of third fluorescent layers 33 are alternately arranged with the plurality of first fluorescent layers 31 and the plurality of second fluorescent layers 32.

[0014] The first fluorescent layer 31 is a fluorescent layer containing a first phosphor having an emission wavelength in the visible range, and includes, for example, a first phosphor having a red (R) emission color. The second fluorescent layer 32 is a fluorescent layer containing a second phosphor having an emission wavelength in the visible range different from that of the first phosphor, and includes, for example, a second phosphor having a green (G) emission color. The third fluorescent layer 33 is a fluorescent layer containing a third phosphor having an emission wavelength in the visible range different from those of the first phosphor and the second phosphor, and includes, for example, a third phosphor having a blue (B) emission color.

[0015] The materials of the first phosphor, the second phosphor, and the third phosphor are not particularly limited. For example, quantum dot phosphors can be used. By using quantum dot phosphors, the excitation wavelengths of the first phosphor, the second phosphor, and the third phosphor can be made the same, and the emission wavelengths (i.e., emission colors) of the first phosphor, the second phosphor, and the third phosphor can be made different. As an example of a phosphor, nanocrystalline particles of cesium lead halide perovskite (CsPbX3, where X is a halogen, either Cl, Br, I, or a mixture thereof) can be used, with the excitation wavelength being ultraviolet light in the range of 300 nm to 400 nm, and the emission wavelengths of RGB can be obtained.

[0016] The base materials of the first phosphor layer 31, the second phosphor layer 32, and the third phosphor layer 33 are made of materials that are transparent to visible light, and are made of resin materials or glass materials. By mixing phosphors into the transparent base materials, the first phosphor layer 31, the second phosphor layer 32, and the third phosphor layer 33 can be formed respectively, and by laminating the first phosphor layer 31, the second phosphor layer 32, and the third phosphor layer 33 in order, the display body 12 can be formed.

[0017] The display body 12 is configured to have an overall solid column shape, and can be configured to have a cylindrical shape, a polygonal column shape, or a rectangular parallelepiped shape. The display body 12 is configured such that the surface of the display body 12 is mirror-finished so that the inside of the display body 12 can be seen through from the outside. The display body 12 is formed such that the interfaces of the plurality of phosphor layers 31, 32, 33 are invisible or difficult to see, so that the plurality of phosphor layers 31, 32, 33 are integrated.

[0018] The size of the display body 12 is not particularly limited. For example, the size in the stacking direction (z direction) can be about 100 mm to 1000 mm, and the sizes in the directions orthogonal to the stacking direction (x direction and y direction) can be about 100 mm to 1000 mm. The thickness of each of the plurality of phosphor layers 31, 32, 33 can be, for example, about 10 μm to 10 mm. As an example, the sizes of the display body 12 in the x, y, and z directions can be 200 mm, and the thickness of each of the plurality of phosphor layers 31, 32, 33 can be 200 μm.

[0019] The first irradiation unit 14 irradiates the display body 12 with first excitation light 20 that excites the phosphor. The first excitation light 20 is incident on the first surface 26 of the display body 12, and the display body 12 is irradiated such that the condensing position 24 of the first excitation light 20 changes over time inside the display body 12. The first irradiation unit 14 includes a light source 40, a condenser lens 42, a lens drive mechanism 44, a mirror 46, and a mirror drive mechanism 48.

[0020] The light source 40 generates first excitation light 20 for exciting the first phosphor, the second phosphor, and the third phosphor. The light source 40 generates ultraviolet light having a central wavelength included in the range of 300 nm to 400 nm as the first excitation light 20. The type of the light source 40 is not limited, and for example, a gallium nitride (GaN)-based semiconductor laser or a semiconductor LED (Light Emitting Diode) can be used as the light source 40.

[0021] The condenser lens 42 condenses the first excitation light 20 generated by the light source 40 toward the inside of the display body 12. The lens drive mechanism 44 is configured to change the position of the condenser lens 42 in the optical axis direction A. The lens drive mechanism 44 changes the condensing position 24 of the first excitation light 20 by changing the position of the condenser lens 42. The lens drive mechanism 44 makes the condensing position 24 in the irradiation direction of the first excitation light 20 variable and makes the condensing position 24 in the direction intersecting the first surface 26 variable. Instead of the condenser lens 42 and the lens drive mechanism 44, a variable-focus lens may be used to make the condensing position 24 in the direction intersecting the first surface 26 variable.

[0022] Mirror 46 reflects the first excitation light 20 that has passed through the condenser lens 42 toward the display body 12. The mirror 46 reflects the first excitation light 20 so that the first excitation light 20 is incident on the first surface 26. The mirror drive mechanism 48 is configured to change the orientation of the mirror 46. The mirror drive mechanism 48 is configured to make the orientation of the mirror 46 variable in two axes, and changes the condensing position 24 of the first excitation light 20 reflected by the mirror 46 in the directions (x direction and y direction) along the first surface 26. In the illustrated example, a single mirror 46 is used, but a combination of a first mirror for scanning in the x direction and a second mirror for scanning in the y direction may be used.

[0023] The second irradiation unit 16 irradiates the display body 12 with second excitation light 22 for exciting the phosphor. The second excitation light 22 is incident on the second surface 28 of the display body 12 and irradiates the display body 12 from the side opposite to the first excitation light 20. The second irradiation unit 16 is a surface light source configured to irradiate the entire second surface 28 of the display body 12 with the second excitation light 22. The second excitation light 22 may have the same wavelength as the first excitation light 20, or may be ultraviolet light having a center wavelength in the range of 300 nm to 400 nm.

[0024] The second excitation light 22 has a role of assisting the excitation of the phosphor by the first excitation light 20. The intensity of the first excitation light 20 incident on the first surface 26 of the display body 12 decreases as it passes through the display body 12. Further, when changing the condensing position 24 of the first excitation light 20 according to the position of a single condenser lens 42 as shown in FIG. 1, the spot diameter of the first excitation light 20 increases as the condensing position 24 approaches the second surface 28, and the condensing intensity of the first excitation light 20 decreases. Therefore, when the output intensity of the light source 40 is constant, the condensing intensity of the first excitation light 20 becomes stronger as the condensing position 24 is closer to the first surface 26, and weaker as the condensing position 24 is closer to the second surface 28. On the other hand, the light intensity of the second excitation light 22 becomes stronger as it is closer to the second surface 28 and weaker as it is closer to the first surface 26. By irradiating the display body 12 with such second excitation light 22, the excitation at the condensing position 24 can be assisted, and the variation in the total value of the light intensities of the first excitation light 20 and the second excitation light 22 at the condensing position 24 due to the change in the position of the condensing position 24 can be reduced.

[0025] FIG. 2 is a graph schematically showing an example of the light intensity distribution of the second excitation light 22. The second irradiation unit 16 may irradiate the second excitation light 22 with uniform light intensity on the second surface 28, as indicated by the solid line C in FIG. 2. The second irradiation unit 16 may irradiate the second excitation light 22 having an intensity distribution corresponding to the position on the second surface 28. The second irradiation unit 16 may irradiate the second excitation light 22 having an intensity distribution in which the light intensity at the central portion of the second surface 28 is relatively low and the light intensity at the peripheral portion of the second surface 28 is relatively high, as indicated by the broken line D in FIG. 2. Since the distance from the mirror 46 that reflects the first excitation light 20 to the central portion of the display body 12 is relatively short, the condensing intensity of the first excitation light 20 is larger than that of the peripheral portion where the distance from the mirror 46 is far. On the other hand, since the distance from the mirror 46 to the peripheral portion of the display body 12 is relatively long, the condensing intensity of the first excitation light 20 is relatively small. Therefore, by lowering the light intensity at the central portion of the second excitation light 22 and increasing the light intensity at the peripheral portion of the second excitation light 22, the variation in the total value of the light intensities of the first excitation light 20 and the second excitation light 22 at the condensing position 24 due to the position change of the condensing position 24 can be reduced.

[0026] The light intensity of the second excitation light 22 is set so as not to exceed the threshold value of the amplified spontaneous emission (ASE) of the phosphor contained in the display body 12. On the other hand, the total value of the light intensities of the first excitation light 20 and the second excitation light 22 at the condensing position 24 is set to be equal to or higher than the threshold value of the amplified spontaneous emission light (ASE threshold value). Amplified spontaneous emission light (ASE) is also called superluminescence, and refers to a phenomenon in which an inverted distribution is generated in the phosphor by the excitation light, and the emission intensity of the phosphor is amplified. The threshold value of the amplified spontaneous emission light (ASE threshold value) corresponds to the minimum light intensity of the excitation light for generating ASE.

[0027] FIG. 3 is a graph schematically showing the relationship between the excitation light intensity and the emission intensity of the phosphor, and shows an example when the phosphor is a nanocrystal of cesium lead halide perovskite. When the light intensity of the excitation light irradiated on the phosphor is the ASE threshold value (0.45 mJ / cm in FIG. 3) 2)Above this level, the ratio (slope) of the emission intensity to the excitation light intensity increases. By setting the excitation light intensity at the light collection position 24 to be equal to or higher than the ASE threshold value, the emission intensity of the phosphor at the light collection position 24 can be increased even more. On the other hand, by setting the excitation light intensity at a location different from the light collection position 24 to be less than the ASE threshold value, the emission intensity of the phosphor at a location different from the light collection position 24 can be decreased, and the contrast ratio with the light collection position 24 can be increased.

[0028] Returning to FIG. 1, the control unit 18 controls the operations of the first irradiation unit 14 and the second irradiation unit 16. The control unit 18 can be realized, in terms of hardware, by elements and mechanical devices including a computer's CPU and memory, and in terms of software, by a computer program or the like. Various functions provided by the control unit 18 can be realized by the cooperation of hardware and software.

[0029] The control unit 18 controls the operations of the lens drive mechanism 44 and the mirror drive mechanism 48 to control the light collection position 24 of the first excitation light 20 in three dimensions (the x direction, the y direction, and the z direction). The control unit 18, for example, operates the lens drive mechanism 44 and the mirror drive mechanism 48 periodically so that the light collection position 24 of the first excitation light 20 is three-dimensionally scanned inside the display body 12.

[0030] The control unit 18, for example, controls the on / off of the light source 40 according to the light collection position 24 of the first excitation light 20. The control unit 18 turns on the light source when the light collection position 24 of the first excitation light 20 is a location to be drawn inside the display body 12. The control unit 18 turns off the light source when the light collection position 24 of the first excitation light 20 is a location not to be drawn inside the display body 12.

[0031] The control unit 18 controls the turning on and off of the light source 40 and the emission intensity of the light source 40, for example, based on the 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 positions and display colors of the contours of the three-dimensional image S to be drawn on the display body 12 are specified. The control unit 18 controls the display color by controlling the light intensity of the first excitation light 20 that irradiates each of the adjacent first fluorescent layer 31, second fluorescent layer 32, and third fluorescent layer 33. Specifically, the emission color resulting from the mixing of red, green, and blue at the emission position is controlled in full color by controlling the emission amount of red in the first fluorescent layer 31, the emission amount of green in the second fluorescent layer 32, and the emission amount of blue in the third fluorescent layer 33.

[0032] The control unit 18 may change the light intensity of the second excitation light 22 according to the condensing position 24 of the first excitation light 20 by controlling the operation of the second irradiation unit 16. For example, the closer the condensing position 24 of the first excitation light 20 is to the second surface 28, that is, the farther it is from the first surface 26, the greater the light intensity of the second excitation light 22 may be increased. Thereby, the total value of the light intensities of the first excitation light 20 and the second excitation light 22 at the condensing position 24 may be made equal to or greater than the ASE threshold value.

[0033] The display device 10 may further include an image sensor 50. The image sensor 50 is a two-dimensional light detector such as a CCD sensor or a CMOS sensor, and is provided for measuring the spot size of the first excitation light 20. The image sensor 50 is disposed at a position corresponding to the first surface 26 adjacent to the display body 12. The image sensor 50 may be provided at a position different from the illustrated location as long as the first excitation light 20 can be incident thereon.

[0034] The control unit 18 operates the lens drive mechanism 44 and the mirror drive mechanism 48 so that the first excitation light 20 is incident on the image sensor 50. The control unit 18 measures the size of the first excitation light 20 with the image sensor 50 while changing the position of the condenser lens 42, thereby identifying the position of the condenser lens 42 at which the spot size of the first excitation light 20 is minimized. The identified position of the condenser lens 42 can be used as a reference for z-direction positioning to align the condensing position 24 of the first excitation light 20 with the first surface 26. The control unit 18 can calibrate the condensing position 24 of the first excitation light 20 based on the measurement result of the image sensor 50.

[0035] 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 first irradiation unit 14 based on the three-dimensional contour image data. The control unit 18 controls the operations of the lens drive mechanism 44 and the mirror drive mechanism 48 to three-dimensionally scan the condensing position 24 of the first excitation light 20 inside the display body 12. The control unit 18 controls the output intensity of the light source 40 according to the condensing position 24 of the first excitation light 20 so that the display color specified for each drawing position is realized by the three-dimensional contour image data. The control unit 18 operates the second irradiation unit 16 to irradiate the display body 12 with the second excitation light 22 for assisting the excitation by the first excitation light 20. Thereby, the three-dimensional image S corresponding to the three-dimensional contour image data can be drawn inside the display body 12.

[0036] The control unit 18 may acquire the three-dimensional contour image data corresponding to each frame of the moving image data and draw different three-dimensional images S for each frame. Thereby, a moving three-dimensional image S may be displayed.

[0037] The control unit 18 may calibrate the condensing position 24 of the first excitation light 20 based on the measurement result of the image sensor 50. The control unit 18 may calibrate the condensing position 24 before the start of drawing of the three-dimensional image S based on the measurement result of the image sensor 50. The control unit 18 may calibrate the condensing position 24 at the timing during the drawing of the three-dimensional image S or during the drawing of each frame of the moving three-dimensional image S based on the measurement result of the image sensor 50.

[0038] According to this embodiment, by setting the light intensity of the second excitation light 22 to be less than the ASE threshold value, it is possible to prevent the entire display body 12 from emitting light brightly. On the other hand, by setting the total value of the light intensities of the first excitation light 20 and the second excitation light 22 at the condensing position 24 to be equal to or greater than the ASE threshold value, strong light emission due to ASE can be obtained at the condensing position 24, and the contrast ratio with the light emission (background light) at a location different from the condensing position 24 can be increased.

[0039] (Second Embodiment) FIG. 4 is a diagram schematically showing the configuration of a display device 10A according to the second embodiment. In the second embodiment, it is different from the above-described first embodiment in that the first irradiation unit 14A further includes a collimating lens 41. Hereinafter, the second embodiment will be described centering on the differences from the first embodiment, and the common points with the first embodiment will be omitted as appropriate.

[0040] The display device 10A includes a display body 12, a first irradiation unit 14A, a second irradiation unit 16, and a control unit 18. The display body 12, the second irradiation unit 16, and the control unit 18 are configured in the same manner as in the first embodiment.

[0041] The first irradiation unit 14A includes a light source 40, a collimating lens 41, a condensing lens 42, a lens driving mechanism 44, a mirror 46, and a mirror driving mechanism 48. The light source 40, the condensing lens 42, the lens driving mechanism 44, the mirror 46, and the mirror driving mechanism 48 are configured in the same manner as in the first embodiment.

[0042] The collimating lens 41 collimates the first excitation light 20 generated by the light source 40. The condensing lens 42 condenses the first excitation light 20 collimated by the collimating lens 41 toward the inside of the display body 12. The lens driving mechanism 44 changes the condensing position 24 of the first excitation light 20 by changing the position of the condensing lens 42.

[0043] According to this embodiment, by using the collimating lens 41, it is possible to suppress the change in the spot diameter of the first excitation light 20 according to the condensing position 24 of the first excitation light 20. Thereby, the fluctuation of the light intensity of the first excitation light 20 at the condensing position 24 due to the change of the condensing position 24 can be reduced. As a result, compared with the first embodiment, the ratio of the assistance by the second excitation light 22 can be reduced, and the ratio of changing the light intensity of the second excitation light 22 according to the condensing position 24 can be reduced. By reducing the ratio of the assistance by the second excitation light 22, the intensity of the light emission (background light) at a location different from the condensing position 24 can be reduced. Further, by reducing the ratio of changing the light intensity of the second excitation light 22 according to the condensing position 24, the variation in the intensity of the light emission (background light) at a location different from the condensing position 24 can be reduced.

[0044] (Third Embodiment) FIG. 5 is a diagram schematically showing the configuration of the display device 10B according to the third embodiment. The third embodiment is different from the above-described first embodiment in that the display device 10B further includes an optical sensor 52. Hereinafter, the third embodiment will be described centering on the differences from the first embodiment, and the common points with the first embodiment will be omitted as appropriate.

[0045] The display device 10B includes a display body 12, a first irradiation unit 14, a control unit 18, and an optical sensor 52. The display device 10B may or may not include a second irradiation unit 16. The display device 10B may or may not include an image sensor 50. The display body 12, the first irradiation unit 14, the second irradiation unit 16, the control unit 18, and the image sensor 50 are configured in the same manner as in the first embodiment.

[0046] The optical sensor 52 is configured to be able to measure the light intensity for each wavelength. The optical sensor 52 is configured to be able to measure, for example, the light intensity of the first emission color (e.g., red) of the first phosphor, the light intensity of the second emission color (e.g., green) of the second phosphor, and the light intensity of the third emission color (e.g., blue) of the third phosphor. The optical sensor 52 includes, for example, a first sensor 54 having a first filter that selectively transmits red light, a second sensor 56 having a second filter that selectively transmits green light, and a third sensor 58 having a third filter that selectively transmits blue light. The optical sensor 52 is disposed, for example, on the second surface 28 of the display body 12. The optical sensor 52 may be provided at a position different from the illustrated position as long as it can detect the light emission generated in the display body 12.

[0047] The control unit 18 operates the lens drive mechanism 44 to change the position of the condenser lens 42, and acquires the light intensity of each of the first emission color, the second emission color, and the third emission color measured by the optical sensor 52. By changing the condensing position 24 of the first excitation light 20, which excitation light is strongly condensed on which of the first phosphor layer 31, the second phosphor layer 32, and the third phosphor layer 33 changes, and the light intensity of each of the first emission color, the second emission color, and the third emission color changes. For example, the position of the condenser lens 42 at which the light intensity of the first emission color measured by the optical sensor 52 becomes maximum (or maximum) can be used as a reference for positioning in the z direction for matching the condensing position 24 of the first excitation light 20 with the first phosphor layer 31.

[0048] The control unit 18 can calibrate the condensing position 24 of the first excitation light 20 based on the measurement result of the optical sensor 52. The control unit 18 may calibrate the condensing position 24 before starting the drawing of the stereoscopic image S based on the measurement result of the optical sensor 52. The control unit 18 may calibrate the condensing position 24 at the timing during the drawing of the stereoscopic image S or during the drawing of each frame of the stereoscopic image S that becomes a moving image based on the measurement result of the optical sensor 52. According to the present embodiment, by calibrating the condensing position 24 of the first excitation light 20 based on the measurement result of the optical sensor 52, the positioning accuracy for drawing the stereoscopic image S can be increased, and the display accuracy of the stereoscopic image S can be improved.

[0049] (Fourth Embodiment) In the fourth embodiment, some of the fluorescent layers included in the display body contain an infrared phosphor having an emission wavelength in the infrared region. The infrared phosphor is excited by the first excitation light 20 to emit infrared light. The light intensity of the infrared light generated from the infrared phosphor is detected by a photosensor and is used to determine in which fluorescent layer the condensing position 24 of the first excitation light 20 is located.

[0050] As the infrared phosphor, a plurality of types of infrared phosphors having different emission wavelengths in the infrared region can be used. For example, a first infrared phosphor having an emission wavelength of 800 nm, a second infrared phosphor having an emission wavelength of 900 nm, a third infrared phosphor having an emission wavelength of 1000 nm, a fourth infrared phosphor having an emission wavelength of 1100 nm, a fifth infrared phosphor having an emission wavelength of 1200 nm, and a sixth infrared phosphor having an emission wavelength of 1300 nm can be used. By varying the types of infrared phosphors contained in the fluorescent layer, it is possible to determine in which fluorescent layer the condensing position 24 of the first excitation light 20 is located based on the wavelength of the infrared light detected by the photosensor.

[0051] Hereinafter, the fourth embodiment will be described centering on the differences from the above-described third embodiment, and the common points with the third embodiment will be omitted as appropriate. The display device according to the fourth embodiment has the same configuration as the display device 10 according to the third embodiment, but the configurations of the display body 12 and the photosensor 52 are different.

[0052] FIG. 6 is a diagram schematically showing the configuration of a display body 12C according to the fourth embodiment. The display body 12C includes a plurality of stacked bodies 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j stacked in the z direction.

[0053] The laminate bodies 30a to 30f include first phosphor layers 31a to 31f containing a first phosphor and an infrared phosphor, a second phosphor layer 32 containing a second phosphor and not containing an infrared phosphor, and a third phosphor layer 33 containing a third phosphor and not containing an infrared phosphor. The first phosphor layer 31a included in the first laminate body 30a contains a first phosphor and a first infrared phosphor (for example, having an emission wavelength of 800 nm). The first phosphor layer 31b included in the second laminate body 30b contains a first phosphor and a second infrared phosphor (for example, having an emission wavelength of 900 nm). The first phosphor layer 31c included in the third laminate body 30c contains a first phosphor and a third infrared phosphor (for example, having an emission wavelength of 1000 nm). The first phosphor layer 31d included in the fourth laminate body 30d contains a first phosphor and a fourth infrared phosphor (for example, having an emission wavelength of 1100 nm). The first phosphor layer 31e included in the fifth laminate body 30e contains a first phosphor and a fifth infrared phosphor (for example, having an emission wavelength of 1200 nm). The first phosphor layer 31f included in the sixth laminate body 30f contains a first phosphor and a sixth infrared phosphor (for example, having an emission wavelength of 1300 nm).

[0054] The laminate bodies 30g and 30h include a first phosphor layer 31 containing a first phosphor and not containing an infrared phosphor, second phosphor layers 32a and 32b containing a second phosphor and an infrared phosphor, and a third phosphor layer 33 containing a third phosphor and not containing an infrared phosphor. The second phosphor layer 32a included in the seventh laminate body 30g contains a second phosphor and a first infrared phosphor (for example, having an emission wavelength of 800 nm). The second phosphor layer 32b included in the eighth laminate body 30h contains a second phosphor and a second infrared phosphor (for example, having an emission wavelength of 900 nm). Note that the second phosphor layer included in a laminate body not shown in the figure may contain a second phosphor and any one of a third infrared phosphor, a fourth infrared phosphor, a fifth infrared phosphor, and a sixth infrared phosphor.

[0055] The laminate bodies 30i and 30j include a first phosphor layer 31 that contains a first phosphor and does not contain an infrared phosphor, a second phosphor layer 32 that contains a second phosphor and does not contain an infrared phosphor, and third phosphor layers 33a and 33b that contain a third phosphor and an infrared phosphor. The third phosphor layer 33a included in the ninth laminate body 30i contains a third phosphor and a first infrared phosphor (for example, having an emission wavelength of 800 nm). The third phosphor layer 33b included in the tenth laminate body 30j contains a third phosphor and a second infrared phosphor (for example, having an emission wavelength of 900 nm). The third phosphor layer included in a laminate body not shown in the figure may contain a third phosphor and any one of a third infrared phosphor, a fourth infrared phosphor, a fifth infrared phosphor, and a sixth infrared phosphor.

[0056] FIG. 7 is a diagram schematically showing the configuration of the optical sensor 52C according to the fourth embodiment. The optical sensor 52C has a plurality of sensors 54, 56, 58, 60a, 60b, 60c, 60d, 60e, 60f having different detectable wavelengths. The first sensor 54, the second sensor 56, and the third sensor 58 are configured in the same manner as in the third embodiment and are configured to measure, for example, the light intensities of red, green, and blue.

[0057] The optical sensor 52C has a plurality of infrared sensors 60a to 60f. The first infrared sensor 60a is configured to measure the light intensity of the emission wavelength of the first infrared phosphor, and has, for example, a filter that selectively transmits infrared light of 800 nm. The second infrared sensor 60b is configured to measure the light intensity of the emission wavelength of the second infrared phosphor, and has, for example, a filter that selectively transmits infrared light of 900 nm. The third infrared sensor 60c is configured to measure the light intensity of the emission wavelength of the third infrared phosphor, and has, for example, a filter that selectively transmits infrared light of 1000 nm. The fourth infrared sensor 60d is configured to measure the light intensity of the emission wavelength of the fourth infrared phosphor, and has, for example, a filter that selectively transmits infrared light of 1100 nm. The fifth infrared sensor 60e is configured to measure the light intensity of the emission wavelength of the fifth infrared phosphor, and has, for example, a filter that selectively transmits infrared light of 1200 nm. The sixth infrared sensor 60f is configured to measure the light intensity of the emission wavelength of the sixth infrared phosphor, and has, for example, a filter that selectively transmits infrared light of 1300 nm.

[0058] The control unit 18 operates the lens drive mechanism 44 to change the position of the condenser lens 42, and acquires the light intensity for each wavelength measured by the optical sensor 52C. The control unit 18 determines, based on the light intensity for each wavelength measured by the optical sensor 52C, in which fluorescent layer containing any of the plurality of types of infrared phosphors the condensing position 24 of the first excitation light 20 is located. For example, when the light intensity of the emission wavelength (red) of the first phosphor becomes maximum (or maximum), and the light intensity of the emission wavelength (800 nm) of the first infrared phosphor becomes maximum (or maximum), it can be determined that the condensing position 24 is located in the first fluorescent layer 31a containing the first phosphor and the first infrared phosphor.

[0059] In the example of FIG. 6, the case where each of the consecutive laminates 30a to 30h contains an infrared phosphor is shown. In a modified example, a laminate containing an infrared phosphor and a laminate not containing an infrared phosphor may be alternately laminated. For example, a plurality (e.g., 9) of laminates 30 that do not contain an infrared phosphor may be laminated on the first laminate 30a containing the first infrared phosphor, and the second laminate 30b containing the second infrared phosphor may be laminated thereon. For example, a fluorescent layer containing an infrared phosphor as a positioning reference may be provided every 10 laminates. Thereby, when the number of laminates 30 of the display body 12C is large, a positioning reference can be set with an appropriate interval.

[0060] In the example of FIG. 6, the case where one fluorescent layer contains one type of infrared phosphor is shown. In a further modified example, one fluorescent layer may contain two or more types of infrared phosphors. For example, one fluorescent layer may contain the first infrared phosphor and the second infrared phosphor, or may contain the first infrared phosphor, the second infrared phosphor, and the third infrared phosphor. Also, depending on the fluorescent layer serving as a positioning reference, the combination of infrared phosphors to be contained may be varied. By combining two or more types of infrared phosphors, the number of patterns for identifying the fluorescent layer can be increased using a limited number of types of infrared phosphors. Thereby, when the number of laminates 30 of the display body 12C is large, the position of the fluorescent layer can be grasped more finely, and the display accuracy of the stereoscopic image S can be improved.

[0061] (Fifth Embodiment) FIG. 8 is a diagram schematically showing the configuration of a display device 10D according to the fifth embodiment. The fifth embodiment is different from the above-described first embodiment in that a power supply 70 for applying a voltage between the first surface 26 and the second surface 28 of the display body 12 is provided instead of the second irradiation unit 16. Hereinafter, the fifth embodiment will be described centering on the differences from the first embodiment, and the common points with the first embodiment will be omitted as appropriate.

[0062] The display device 10D includes a display body 12D, a first irradiation unit 14, a control unit 18, a first electrode 66, a second electrode 68, and a power supply 70. The first irradiation unit 14 and the control unit 18 are configured in the same manner as in the first embodiment.

[0063] The display body 12D is configured in the same manner as the display body 12 according to the first embodiment, but is different from the first embodiment in that it has conductivity. Each of the first fluorescent layer 31, the second fluorescent layer 32, and the third fluorescent layer 33 included in the plurality of laminate bodies 30 of the display body 12D is configured to have conductivity. For example, by using a conductive polymer such as polyacetylene or polythiophene as the base material of the first fluorescent layer 31, the second fluorescent layer 32, and the third fluorescent layer 33, it can be configured to have conductivity. Alternatively, the first fluorescent layer 31, the second fluorescent layer 32, and the third fluorescent layer 33 may be made conductive by containing conductive particles.

[0064] The first electrode 66 is provided on the first surface 26 of the display body 12D. The first electrode 66 is a transparent electrode that transmits the first excitation light 20 and is made of a conductive oxide material such as indium tin oxide (ITO). The second electrode 68 is provided on the second surface 28 of the display body 12D. The second electrode 68 is preferably a transparent electrode in the same manner as the first electrode 66, but may not be a transparent electrode.

[0065] The power supply 70 applies a voltage between the first electrode 66 and the second electrode 68. By applying a voltage to the display body 12D, the power supply 70 electrically excites the phosphors included in the display body 12D. The power supply 70 applies an auxiliary voltage to the entire display body 12D to auxiliary-excite the phosphors included in the display body 12D. When the phosphors are electrically excited, the emission amount of the phosphors depends on the current density, and the larger the current density, the greater the emission amount. The power supply 70 controls the current flowing between the first electrode 66 and the second electrode 68 so that the current density is such that the phosphors do not generate ASE in a state where the first excitation light 20 is not irradiated. That is, the current density flowing between the first electrode 66 and the second electrode 68 is controlled to be less than the "threshold current density of amplified spontaneous emission light", which is the current density required to generate ASE. The power supply 70 may have a constant current circuit.

[0066] When the auxiliary voltage is applied by the power supply 70, the first irradiation unit 14 irradiates the phosphor with the first excitation light 20 having a light intensity that enables the phosphor to generate ASE at the condensing position 24 of the first excitation light 20. The first irradiation unit 14 causes the phosphor to generate ASE at the condensing position 24 by the sum of the contribution of the first excitation light 20 at the condensing position 24 and the contribution of electrical excitation by the power supply 70.

[0067] The control unit 18 may change the current density of the current flowing through the display body 12D according to the condensing position 24 of the first excitation light 20 by controlling the operation of the power supply 70. For example, as the condensing position 24 of the first excitation light 20 gets closer to the second surface 28, that is, as it gets farther from the first surface 26, the amount of current (or current density) flowing through the display body 12D may be increased. Thereby, while suppressing the variation in the sum of the contribution of the first excitation light 20 at the condensing position 24 and the contribution of electrical excitation by the power supply 70, the phosphor may be caused to generate ASE at the condensing position 24.

[0068] (Sixth Embodiment) FIG. 9 is a diagram schematically showing the configuration of the display device 10E according to the sixth embodiment. In the sixth embodiment, it is different from the above-described fifth embodiment in that separate power supplies 70a and 70b are connected to the central portion and the peripheral portion of the display body 12D. Hereinafter, the sixth embodiment will be described centering on the differences from the fifth embodiment, and the common points with the fifth embodiment will be omitted as appropriate.

[0069] The display device 10E includes a display body 12D, a first irradiation unit 14, a control unit 18, a first electrode 66, a second electrode 68, and a power supply 70. The display body 12D, the first irradiation unit 14, and the control unit 18 are configured in the same manner as in the fifth embodiment.

[0070] The second electrode 68 has a central electrode 68a provided at the central portion of the second surface 28 of the display body 12, and a peripheral electrode 68b provided at the peripheral portion of the second surface 28. The power supply 70 has a first power supply 70a connected between the first electrode 66 and the central electrode 68a, and a second power supply 70b connected between the first electrode 66 and the peripheral electrode 68b.

[0071] The first power supply 70a is configured to pass a current with a first current density through the central portion of the display body 12D. The second power supply 70b is configured to pass a current with a second current density greater than the first current density through the peripheral portion of the display body 12D. Since the distance from the mirror 46 to the peripheral portion of the display body 12D is relatively long, the condensing intensity of the first excitation light 20 is relatively small compared to the central portion of the display body 12D. Therefore, by relatively lowering the current density of the central portion of the display body 12D and relatively increasing the current density of the peripheral portion of the display body 12D, it is possible to reduce the variation in the total of the contribution of the first excitation light 20 at the condensing position 24 and the contribution of the electrical excitation due to the positional change of the condensing position 24.

[0072] In the example of FIG. 9, the case where two electrodes 68a and 68b are provided on the second surface 28 is shown. In a further modification, three or more electrodes set concentrically on the second surface 28 may be provided, and separate power supplies may be connected to each of the three or more electrodes. In this case, a voltage may be applied so that the current density of the central portion of the display body 12D becomes small and the current density of the peripheral portion of the display body 12D becomes large.

[0073] As described above, the present invention has been described with reference to the above-described embodiments. However, the present invention is not limited to the above-described embodiments, and the present invention also includes those in which the configurations shown in each display example are appropriately combined or replaced.

[0074] In the third and fourth embodiments, a configuration that does not use the second irradiation unit 16 may be employed, and instead of the second irradiation unit 16, a power supply 70 for applying an auxiliary voltage in the fifth or sixth embodiment may be used. Further, in the third to sixth embodiments, the first irradiation unit 14A including the collimating lens 41 in the second embodiment may be used.

[0075] Hereinafter, some aspects of the present invention will be described.

[0076] [Aspect 1] A display body in which a plurality of phosphor-containing fluorescent layers are laminated from a first surface toward a second surface, a first irradiation unit that irradiates a first excitation light that enters the first surface and excites the phosphor while changing a condensing position of the first excitation light in the display body, and a second irradiation unit that irradiates a second excitation light that enters the second surface and excites the phosphor, wherein the light intensity of the second excitation light is less than a threshold value of spontaneous emission amplified light of the phosphor, and a total value of the light intensities of the first excitation light and the second excitation light is equal to or greater than the threshold value of the spontaneous emission amplified light of the phosphor. [Aspect 2] The display device according to Aspect 1, wherein the second irradiation unit changes the light intensity of the second excitation light according to the condensing position of the first excitation light. [Aspect 3] The display device according to Aspect 1 or 2, wherein the second irradiation unit irradiates the entire second surface with the second excitation light. [Aspect 4] The display device according to Aspect 3, wherein the second irradiation unit irradiates the second excitation light having an intensity distribution in which the light intensity in a peripheral portion of the second surface is higher than that in a central portion of the second surface. [Aspect 5] A step of irradiating a first excitation light that enters the first surface of a display body in which a plurality of phosphor-containing fluorescent layers are laminated from the first surface toward the second surface and excites the phosphor while changing a condensing position of the first excitation light in the display body, and a step of irradiating a second excitation light that enters the second surface and excites the phosphor, wherein the light intensity of the second excitation light is less than a threshold value of spontaneous emission amplified light of the phosphor, and a total value of the light intensities of the first excitation light and the second excitation light is equal to or greater than the threshold value of the spontaneous emission amplified light of the phosphor.

[0077] [Aspect 6] A display body in which a plurality of first phosphor layers containing a first phosphor and a plurality of second phosphor layers containing a second phosphor having an emission wavelength different from that of the first phosphor are laminated, An irradiation unit that irradiates excitation light that enters the display body and excites the first phosphor and the second phosphor while changing the condensing position of the excitation light in the display body, An optical sensor that measures the light intensity of the light emitted from the display body by wavelength, A display device including a control unit that controls the condensing position of the excitation light based on at least one of the light intensity of the emission wavelength of the first phosphor and the light intensity of the emission wavelength of the second phosphor measured by the optical sensor. [Aspect 7] The display body includes a phosphor layer containing an infrared phosphor having an emission wavelength in the infrared region, The control unit controls the condensing position of the excitation light further based on the light intensity of the emission wavelength of the infrared phosphor measured by the optical sensor. The display device according to Aspect 6. [Aspect 8] The display body includes a phosphor layer containing a first infrared phosphor having an emission wavelength in the infrared region and a phosphor layer containing a second infrared phosphor having an emission wavelength in the infrared region different from that of the first infrared phosphor, The control unit controls the condensing position of the excitation light further based on the light intensity of the emission wavelength of the first infrared phosphor and the light intensity of the emission wavelength of the second infrared phosphor measured by the optical sensor. The display device according to Aspect 7. [Aspect 9] The display body includes a phosphor layer containing two or more of a plurality of types of infrared phosphors having different emission wavelengths in the infrared region, The control unit controls the condensing position of the excitation light further based on the light intensity of the emission wavelength of each of the plurality of types of infrared phosphors measured by the optical sensor. The display device according to Aspect 8 or 9. [Aspect 10] Exciting light that is incident on a display body formed by laminating a plurality of first fluorescent layers containing a first phosphor and a plurality of second fluorescent layers containing a second phosphor having an emission wavelength different from that of the first phosphor, and irradiating the exciting light while changing the condensing position of the exciting light in the display body; Measuring, with a light sensor, the intensity of the light emitted from the display body for each wavelength; Controlling the condensing position of the exciting light based on at least one of the light intensity of the emission wavelength of the first phosphor and the light intensity of the emission wavelength of the second phosphor measured by the light sensor. A display method comprising the steps of:

[0078] [Aspect 11] A display body in which a plurality of fluorescent layers containing a phosphor are laminated from a first surface to a second surface; A first electrode provided on the first surface; A second electrode provided on the second surface; A power source that applies a voltage between the first electrode and the second electrode; An irradiation unit that irradiates the display body with exciting light that excites the phosphor while changing the condensing position of the exciting light in the display body. A display device comprising: [Aspect 12] The power source changes the amount of current flowing between the first electrode and the second electrode according to the condensing position of the exciting light. The display device according to Aspect 11. [Aspect 13] The power source is configured to flow a current between the first electrode and the second electrode that is less than the threshold current density of the spontaneous emission amplified light that the phosphor can generate the spontaneous emission amplified light, The irradiation unit irradiates the phosphor with the exciting light having a light intensity that allows the phosphor to generate the spontaneous emission amplified light. The display device according to Aspect 11 or 12. [Aspect 14] The second electrode has a central electrode provided at the central portion of the second surface and a peripheral electrode provided at the peripheral portion of the second surface. The power supply includes a first power supply for flowing a current with a first current density between the first electrode and the central electrode, and a second power supply for flowing a current with a second current density greater than the first current density between the first electrode and the peripheral electrode. The display device according to any one of Aspects 11 to 13. [Aspect 15] Applying a DC voltage between a first electrode provided on the first surface of a display body in which a plurality of phosphor-containing phosphor layers are laminated from the first surface toward the second surface, and a second electrode provided on the second surface; Irradiating the display body with excitation light that enters the display body and excites the phosphor while changing the condensing position of the excitation light in the display body. A display method comprising the steps of:

Explanation of Reference Numerals

[0079] 10... Display device, 12... Display body, 14... First irradiation unit, 16... Second irradiation unit, 18... Control unit, 20... First excitation light, 22... Second excitation light, 24... Condensing position, 26... First surface, 28... Second surface, 30... Laminate, 31... First phosphor layer, 32... Second phosphor layer, 33... Third phosphor layer, 40... Light source, 41... Collimating lens, 42... Condensing lens, 44... Lens drive mechanism, 46... Mirror, 48... Mirror drive mechanism, 50... Image sensor, 52... Optical sensor, 66... First electrode, 68... Second electrode, 70... Power supply.

Claims

1. A display device comprising: a display body having a plurality of phosphor-containing phosphor layers laminated from a first surface toward a second surface; a first electrode provided on the first surface; a second electrode provided on the second surface; a power source for applying a voltage between the first electrode and the second electrode; an irradiation unit that irradiates the display body with excitation light that enters the display body and excites the phosphor, while changing the condensing position of the excitation light within the display body.

2. The display device according to claim 1, wherein the power source changes the amount of current flowing between the first electrode and the second electrode according to the condensing position of the excitation light.

3. The power source is configured to cause a current less than the threshold current density of the spontaneous emission amplified light, at which the phosphor can generate spontaneous emission amplified light, to flow between the first electrode and the second electrode, and the irradiation unit irradiates the display body with the excitation light having an optical intensity at which the phosphor can generate spontaneous emission amplified light. The display device according to claim 1 or 2.

4. The second electrode has a central electrode provided at a central portion of the second surface and a peripheral electrode provided at a peripheral portion of the second surface, and the power source has a first power source for causing a current having a first current density to flow between the first electrode and the central electrode, and a second power source for causing a current having a second current density greater than the first current density to flow between the first electrode and the peripheral electrode. The display device according to any one of claims 1 to 3.

5. A display method comprising: applying a voltage between a first electrode provided on a first surface of a display body having a plurality of phosphor-containing phosphor layers laminated from the first surface toward a second surface, and a second electrode provided on the second surface; irradiating the display body with excitation light that enters the display body and excites the phosphor, while changing the condensing position of the excitation light within the display body.

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