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 12 obtained by laminating a plurality of fluorescent layers containing phosphor from a first surface 26 toward a second surface 28; a first radiation unit 14 that radiates first excitation light 20 incident on the first surface 26 and exciting the phosphor, while changing a light collecting position 24 of the first excitation light 20 in the display body 12C; and a second radiation unit 16 that radiates second excitation light 22 incident on the second surface 28 and exciting the phosphor. The intensity of the second excitation light 22 is less than a threshold of the amplified spontaneous emission of the phosphor, and the total value of the intensities of the first excitation light 20 and the second excitation light 22 is equal to or more than the threshold of the amplified spontaneous emission of the phosphor.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 a three-dimensional image, a method has been proposed in which second-harmonic waves, which are visible light, are 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] Japanese Patent Application Laid-Open No. 2003-287711 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned prior art requires the use of a laser light source with a pulse width of several tens of picoseconds to several femtoseconds. Such ultrashort pulse laser light sources are very expensive, which may hinder the widespread use of stereoscopic display devices.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide a three-dimensional display technology that does not require an ultrashort pulse laser. [Means for solving the problem]

[0006] A display device according to one embodiment of the present invention includes a display element in which multiple fluorescent layers containing phosphors are stacked from a first surface to a second surface, a first irradiating unit that irradiates first excitation light that is incident on the first surface and excites the phosphors while changing the focusing position of the first excitation light within the display element, and a second irradiating unit that irradiates second excitation light that is incident on the second surface and excites the phosphors. The light intensity of the second excitation light is less than the threshold of amplified spontaneous emission of the phosphors, and the sum of the light intensities of the first excitation light and the second excitation light is equal to or greater than the threshold of amplified spontaneous emission of the phosphors.

[0007] Another aspect of the present invention is a display method. This method includes the steps of: irradiating a display having multiple fluorescent layers containing a phosphor stacked from a first surface to a second surface with first excitation light that is incident on a first surface of the display and excites the phosphor while changing the focusing position of the first excitation light within the display; and irradiating a display having second excitation light that is incident on the second surface and excites the phosphor. The light intensity of the second excitation light is less than the threshold of amplified spontaneous emission of the phosphor, and the sum of the light intensities of the first excitation light and the second excitation light is equal to or greater than the threshold of amplified spontaneous emission of the phosphor.

[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 aspects of the present invention. [Effects of the Invention]

[0009] According to the present invention, a stereoscopic display technique that does not require an ultrashort pulse laser can be provided. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram schematically illustrating a configuration of a display device according to a first embodiment. [Figure 2] 10 is a graph schematically showing an example of the light intensity distribution of the second excitation light. [Figure 3] 1 is a graph schematically showing the relationship between excitation light intensity and emission intensity of a phosphor. [Figure 4] FIG. 10 is a diagram schematically illustrating the configuration of a display device according to a second embodiment. [Figure 5] FIG. 10 is a diagram schematically illustrating the configuration of a display device according to a third embodiment. [Figure 6] FIG. 10 is a diagram schematically illustrating the configuration of a display according to a fourth embodiment. [Figure 7] FIG. 10 is a diagram schematically illustrating the configuration of an optical sensor according to a fourth embodiment. [Figure 8] FIG. 10 is a diagram schematically illustrating the configuration of a display device according to a fifth embodiment. [Figure 9] FIG. 10 is a diagram schematically illustrating the configuration of a display device according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] 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.

[0012] (First embodiment) 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, a first irradiating unit 14, a second irradiating unit 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 has a first surface 26 and a second surface 28, and includes a plurality of laminates 30 stacked in the z-direction from the first surface 26 to the second surface 28. Each of the plurality of laminates 30 includes a first fluorescent layer 31, a second fluorescent layer 32, and a third fluorescent layer 33. The display 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, and so on. 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, for example, a first phosphor having an emission color of red (R). 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, for example, a second phosphor having an emission color of green (G). The third fluorescent layer 33 is a fluorescent layer containing a third phosphor having an emission wavelength in the visible range different from that of the first and second phosphors, for example, a third phosphor having an emission color of blue (B).

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

[0016] The base material of the first fluorescent layer 31, the second fluorescent layer 32, and the third fluorescent layer 33 is made of a material that is transparent to visible light, such as a resin material or a glass material. The first fluorescent layer 31, the second fluorescent layer 32, and the third fluorescent layer 33 can be formed by mixing a phosphor into the transparent base material, and the display 12 can be formed by laminating the first fluorescent layer 31, the second fluorescent layer 32, and the third fluorescent layer 33 in this order.

[0017] The display body 12 is configured to have a solid columnar shape as a whole, such as a cylindrical, polygonal prism, or rectangular parallelepiped shape. The display body 12 is configured so that the surface of the display body 12 is mirror-finished so that the interior of the display body 12 can be seen from the outside. The display body 12 is formed so that the multiple fluorescent layers 31, 32, and 33 are integrated together so that the interfaces between the multiple fluorescent layers 31, 32, and 33 are invisible or difficult to see.

[0018] The size of the display 12 is not particularly limited, but for example, the size in the stacking direction (z direction) can be approximately 100 mm to 1000 mm, and the size in the directions perpendicular to the stacking direction (x direction and y direction) can be approximately 100 mm to 1000 mm. The thickness of each of the multiple fluorescent layers 31, 32, 33 can be approximately 10 μm to 10 mm. As an example, the size of the display 12 in the x, y, and z directions can be 200 mm, and the thickness of each of the multiple fluorescent layers 31, 32, 33 can be 200 μm.

[0019] The first irradiating unit 14 irradiates the display 12 with first excitation light 20 that excites the phosphor. The first excitation light 20 is incident on a first surface 26 of the display 12, and is irradiated onto the display 12 so that a focusing position 24 of the first excitation light 20 changes over time inside the display 12. The first irradiating unit 14 includes a light source 40, a focusing lens 42, a lens driving mechanism 44, a mirror 46, and a mirror driving 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 center wavelength in the range of 300 nm to 400 nm as the first excitation light 20. Any type of light source 40 may be used, but for example, a gallium nitride (GaN) based semiconductor laser or a semiconductor light emitting diode (LED) may be used as the light source 40.

[0021] The condensing lens 42 condenses the first excitation light 20 generated by the light source 40 toward the inside of the display body 12. The lens driving mechanism 44 is configured to change the position of the condensing lens 42 in the optical axis direction A. 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. The lens driving mechanism 44 varies the condensing position 24 in the irradiation direction of the first excitation light 20, and also varies the condensing position 24 in a direction intersecting with the first surface 26. Note that a variable-focus lens may be used instead of the condensing lens 42 and the lens driving mechanism 44 to vary the condensing position 24 in the direction intersecting with the first surface 26.

[0022] The mirror 46 reflects the first excitation light 20 that has passed through the condensing lens 42 toward the display 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 driving mechanism 48 is configured to change the orientation of the mirror 46. The mirror driving mechanism 48 is configured to change the orientation of the mirror 46 along two axes, and changes the focusing position 24 of the first excitation light 20 reflected by the mirror 46 in directions (x direction and y direction) along the first surface 26. In the example shown in the figure, one mirror 46 is used, but a first mirror for scanning in the x direction and a second mirror for scanning in the y direction may be combined.

[0023] The second irradiating unit 16 irradiates the display 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 12 and is irradiated onto the display 12 from the side opposite to the first excitation light 20. The second irradiating unit 16 is a surface-emitting light source configured to irradiate the entire second surface 28 of the display 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 serves to assist 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 12 attenuates as it passes through the display 12. Furthermore, when the focusing position 24 of the first excitation light 20 is changed by changing the position of a single focusing lens 42 as shown in FIG. 1 , the spot diameter of the first excitation light 20 increases and the focusing intensity of the first excitation light 20 decreases as the focusing position 24 approaches the second surface 28. Therefore, when the output intensity of the light source 40 is constant, the focusing intensity of the first excitation light 20 increases as the focusing position 24 approaches the first surface 26 and decreases as the focusing position 24 approaches the second surface 28. On the other hand, the light intensity of the second excitation light 22 increases as the focusing position 24 approaches the second surface 28 and decreases as the focusing position 24 approaches the first surface 26. By irradiating the display 12 with such second excitation light 22, excitation at the focusing position 24 is assisted, and the variation in the total light intensity of the first excitation light 20 and the second excitation light 22 at the focusing position 24 caused by changes in the position of the focusing position 24 can be reduced.

[0025] FIG. 2 is a graph schematically illustrating an example of the light intensity distribution of the second excitation light 22. The second irradiator 16 may irradiate the second excitation light 22 such that the light intensity on the second surface 28 is uniform, as indicated by the solid line C in FIG. 2. The second irradiator 16 may irradiate the second excitation light 22 such that the light intensity on the second surface 28 is uniform. The second irradiator 16 may irradiate the second excitation light 22 such that the light intensity is relatively low in the center of the second surface 28 and relatively high in the peripheral portion of the second surface 28, as indicated by the dashed line D in FIG. 2. The central portion of the display 12 is relatively close to the mirror 46 that reflects the first excitation light 20, and therefore the condensed light intensity of the first excitation light 20 is greater than that of the peripheral portion that is farther from the mirror 46. On the other hand, the peripheral portion of the display 12 is relatively far from the mirror 46, and therefore the condensed light intensity of the first excitation light 20 is relatively smaller. Therefore, by lowering the light intensity of the central part of the second excitation light 22 and increasing the light intensity of the peripheral part of the second excitation light 22, the variation in the total value of the light intensity of the first excitation light 20 and the second excitation light 22 at the focusing position 24 caused by changes in the position of the focusing position 24 can be reduced.

[0026] The light intensity of the second excitation light 22 is set so as not to exceed the threshold of amplified spontaneous emission (ASE) of the phosphor contained in the display 12. Meanwhile, the sum of the light intensities of the first excitation light 20 and the second excitation light 22 at the focusing position 24 is set so as to be equal to or greater than the threshold of amplified spontaneous emission (ASE threshold). Amplified spontaneous emission (ASE), also known as superluminescence, is a phenomenon in which a population inversion is generated in a phosphor by excitation light, amplifying the luminescence intensity of the phosphor. The threshold of amplified spontaneous emission (ASE threshold) corresponds to the minimum light intensity of excitation light required to generate ASE.

[0027] Figure 3 is a graph showing the relationship between the excitation light intensity and the emission intensity of a phosphor, and shows an example in which the phosphor is a nanocrystal of cesium lead halide perovskite. When the light intensity of the excitation light irradiated to the phosphor is greater than the ASE threshold (0.45 mJ / cm in Figure 3), 2), the ratio (slope) of the emission intensity to the excitation light intensity increases. By making the excitation light intensity at the focusing position 24 equal to or greater than the ASE threshold, the emission intensity of the phosphor at the focusing position 24 can be increased. On the other hand, by making the excitation light intensity at a location other than the focusing position 24 less than the ASE threshold, the emission intensity of the phosphor at a location other than the focusing position 24 can be reduced, and the contrast ratio with the focusing position 24 can be increased.

[0028] 1, the control unit 18 controls the operations of the first irradiating unit 14 and the second irradiating unit 16. In terms of hardware, the control unit 18 can be realized by elements and mechanical devices such as a computer CPU and memory, and in terms of software, it can be realized by a computer program, etc. Various functions provided by the control unit 18 can be realized by cooperation between hardware and software.

[0029] The control unit 18 controls the focusing position 24 of the first excitation light 20 in three dimensions (x direction, y direction, and z direction) by controlling the operation of the lens driving mechanism 44 and the mirror driving mechanism 48. For example, the control unit 18 periodically operates the lens driving mechanism 44 and the mirror driving mechanism 48, thereby causing the focusing position 24 of the first excitation light 20 to be scanned three-dimensionally inside the display body 12.

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

[0031] The control unit 18 controls the on / off of the light source 40 and the light emission intensity of the light source 40, for example, based on three-dimensional contour image data generated from the three-dimensional image data. The three-dimensional contour image data is data that specifies the three-dimensional position and display color of the contour of the three-dimensional image S to be drawn on the display body 12. The control unit 18 controls the display color by controlling the light intensity of the first excitation light 20 that is irradiated onto each of the adjacent first fluorescent layer 31, second fluorescent layer 32, and third fluorescent layer 33. Specifically, by controlling the amount of red light emitted by the first fluorescent layer 31, the amount of green light emitted by the second fluorescent layer 32, and the amount of blue light emitted by the third fluorescent layer 33, the control unit 18 controls the full color of the emitted light resulting from the mixture of red, green, and blue at the light-emitting positions.

[0032] The control unit 18 may change the light intensity of the second excitation light 22 according to the focusing position 24 of the first excitation light 20 by controlling the operation of the second irradiator 16. For example, the light intensity of the second excitation light 22 may be increased as the focusing position 24 of the first excitation light 20 approaches the second surface 28, that is, as it moves farther from the first surface 26. This may cause the sum of the light intensities of the first excitation light 20 and the second excitation light 22 at the focusing position 24 to be equal to or greater than the ASE threshold.

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

[0034] The control unit 18 operates the lens driving mechanism 44 and the mirror driving 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 on the image sensor 50 while changing the position of the condenser lens 42, and thereby identifies the position of the condenser lens 42 at which the spot size of the first excitation light 20 is smallest. The identified position of the condenser lens 42 can be used as a reference for positioning in the z direction to match 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 results of the image sensor 50.

[0035] Next, the operation of the display device 10 will be described. The control unit 18 acquires three-dimensional contour image data and operates the first irradiator 14 based on the three-dimensional contour image data. The control unit 18 controls the operation of the lens drive mechanism 44 and the mirror drive mechanism 48 to three-dimensionally scan the focusing 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 focusing position 24 of the first excitation light 20 so that the display color specified for each drawing position by the three-dimensional contour image data is realized. The control unit 18 operates the second irradiator 16 to irradiate the display body 12 with second excitation light 22 to supplement the excitation by the first excitation light 20. This allows a three-dimensional image S corresponding to the three-dimensional contour image data to be drawn inside the display body 12.

[0036] The control unit 18 may acquire three-dimensional contour image data corresponding to each frame of the video data, and may draw a different three-dimensional image S for each frame, thereby displaying the three-dimensional image S as a video.

[0037] The control unit 18 may calibrate the focusing position 24 of the first excitation light 20 based on the measurement results of the image sensor 50. The control unit 18 may calibrate the focusing position 24 before starting to draw the three-dimensional image S based on the measurement results of the image sensor 50. The control unit 18 may also calibrate the focusing position 24 based on the measurement results of the image sensor 50 while the three-dimensional image S is being drawn or at the timing between drawing each frame of the three-dimensional image S that will become a moving image.

[0038] According to this embodiment, by setting the light intensity of the second excitation light 22 below the ASE threshold, it is possible to prevent the entire display body 12 from emitting bright light. 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 light-condensing position 24 to be equal to or greater than the ASE threshold, it is possible to obtain strong light emission by ASE at the light-condensing position 24, and to increase the contrast ratio with light emission (background light) at locations other than the light-condensing position 24.

[0039] (Second embodiment) 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 irradiating section 14A further includes a collimating lens 41. The following description of the second embodiment will focus on the differences from the first embodiment, and commonalities with the first embodiment will be omitted as appropriate.

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

[0041] The first irradiation unit 14A includes a light source 40, a collimator lens 41, a condenser lens 42, a lens driving mechanism 44, a mirror 46, and a mirror driving mechanism 48. The light source 40, the condenser 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, which has been collimated by the collimating lens 41, toward the inside of the display body 12. The lens driving mechanism 44 changes the position of the condensing lens 42, thereby changing the condensing position 24 of the first excitation light 20.

[0043] According to the present embodiment, by using the collimator lens 41, it is possible to suppress a change in the spot diameter of the first excitation light 20 according to the focusing position 24 of the first excitation light 20. This makes it possible to reduce fluctuations in the light intensity of the first excitation light 20 at the focusing position 24 due to changes in the focusing position 24. As a result, compared to the first embodiment, it is possible to reduce the proportion of assistance by the second excitation light 22 and reduce the proportion of change in the light intensity of the second excitation light 22 according to the focusing position 24. By reducing the proportion of assistance by the second excitation light 22, it is possible to reduce the intensity of the emission (background light) at locations other than the focusing position 24. Furthermore, by reducing the proportion of change in the light intensity of the second excitation light 22 according to the focusing position 24, it is possible to reduce variations in the intensity of the emission (background light) at locations other than the focusing position 24.

[0044] (Third embodiment) 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 in that the display device 10B further includes an optical sensor 52. The following description of the third embodiment will focus on the differences from the first embodiment, and will omit commonalities with the first embodiment as appropriate.

[0045] The display device 10B includes a display 12, a first irradiator 14, a controller 18, and an optical sensor 52. The display device 10B may or may not include a second irradiator 16. The display device 10B may or may not include an image sensor 50. The display device 12, the first irradiator 14, the second irradiator 16, the controller 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 a first emission color (e.g., red) of a first phosphor, the light intensity of a second emission color (e.g., green) of a second phosphor, and the light intensity of a third emission color (e.g., blue) of a 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 12. The optical sensor 52 may be disposed at a position different from that shown in the drawing, as long as it is able to detect light emitted from the display 12.

[0047] The control unit 18 operates the lens driving mechanism 44 to change the position of the condenser lens 42, while acquiring the light intensities of the first, second, and third emitted colors measured by the optical sensor 52. Changing the condensing position 24 of the first excitation light 20 changes which of the first fluorescent layer 31, the second fluorescent layer 32, and the third fluorescent layer 33 the first excitation light 20 is more strongly condensed at, thereby changing the light intensities of the first, second, and third emitted colors. For example, the position of the condenser lens 42 at which the light intensity of the first emitted color measured by the optical sensor 52 is maximized (or local maximum) can be used as a reference for positioning in the z direction to align the condensing position 24 of the first excitation light 20 with the first fluorescent layer 31.

[0048] The control unit 18 can calibrate the focusing position 24 of the first excitation light 20 based on the measurement result of the optical sensor 52. The control unit 18 may also calibrate the focusing position 24 based on the measurement result of the optical sensor 52 before starting to draw the three-dimensional image S. The control unit 18 may also calibrate the focusing position 24 based on the measurement result of the optical sensor 52 while the three-dimensional image S is being drawn or at the timing between drawing each frame of the three-dimensional image S that will become a moving image. According to this embodiment, by calibrating the focusing position 24 of the first excitation light 20 based on the measurement result of the optical sensor 52, the positional accuracy for drawing the three-dimensional image S can be improved, and the display accuracy of the three-dimensional image S can be improved.

[0049] (Fourth embodiment) In the fourth embodiment, some of the fluorescent layers included in the display contain an infrared phosphor having an emission wavelength in the infrared range. The infrared phosphor is excited by the first excitation light 20 to emit infrared light. The intensity of the infrared light emitted from the infrared phosphor is detected by an optical sensor and used to determine on which fluorescent layer the focusing position 24 of the first excitation light 20 is located.

[0050] The infrared phosphor may be a plurality of types of infrared phosphors having different emission wavelengths in the infrared range. 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 may be used. By varying the types of infrared phosphors contained in the fluorescent layers, it is possible to determine in which fluorescent layer the focusing position 24 of the first excitation light 20 is located, based on the wavelength of the infrared light detected by the optical sensor.

[0051] The following description of the fourth embodiment will focus on the differences from the above-described third embodiment, and will omit commonalities with the third embodiment as appropriate. The display device according to the fourth embodiment has a similar configuration to the display device 10 according to the third embodiment, but the configurations of the display body 12 and the optical sensor 52 are different.

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

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

[0054] The laminates 30g and 30h each include a first fluorescent layer 31 containing a first phosphor but no infrared phosphor, second fluorescent layers 32a and 32b containing a second phosphor and an infrared phosphor, and a third fluorescent layer 33 containing a third phosphor but no infrared phosphor. The second fluorescent layer 32a included in the seventh laminate 30g contains the second phosphor and a first infrared phosphor (e.g., having an emission wavelength of 800 nm). The second fluorescent layer 32b included in the eighth laminate 30h contains the second phosphor and a second infrared phosphor (e.g., having an emission wavelength of 900 nm). The second fluorescent layer included in a laminate not shown in the figure contains the second phosphor and may also contain any one of the third, fourth, fifth, and sixth infrared phosphors.

[0055] The laminates 30i and 30j each include a first fluorescent layer 31 containing a first phosphor but not an infrared phosphor, a second fluorescent layer 32 containing a second phosphor but not an infrared phosphor, and third fluorescent layers 33a and 33b containing a third phosphor and an infrared phosphor. The third fluorescent layer 33a included in the ninth laminate 30i contains the third phosphor and a first infrared phosphor (e.g., having an emission wavelength of 800 nm). The third fluorescent layer 33b included in the tenth laminate 30j contains the third phosphor and a second infrared phosphor (e.g., having an emission wavelength of 900 nm). The third fluorescent layer included in a laminate not shown in the figure may contain the third phosphor as well as any one of the third, fourth, fifth, and sixth infrared phosphors.

[0056] 7 is a diagram illustrating a schematic configuration of an optical sensor 52C according to a fourth embodiment. The optical sensor 52C has a plurality of sensors 54, 56, 58, 60a, 60b, 60c, 60d, 60e, and 60f that can detect different wavelengths. The first sensor 54, the second sensor 56, and the third sensor 58 are configured similarly to those in the third embodiment and are configured to measure the light intensities of, for example, red, green, and blue colors.

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

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

[0059] In the example of FIG. 6, each of the consecutive laminates 30a to 30h contains an infrared phosphor. In a modified example, laminates containing an infrared phosphor and laminates not containing an infrared phosphor may be alternately stacked. For example, a first laminate 30a containing a first infrared phosphor may be stacked on top of a plurality of (e.g., nine) laminates 30 not containing an infrared phosphor, and a second laminate 30b containing a second infrared phosphor may be stacked on top of that. For example, every ten laminates may be provided with a fluorescent layer containing an infrared phosphor to serve as a reference for positioning. This allows for setting a reference for positioning at appropriate intervals when the display 12C has a large number of laminates 30.

[0060] The example in FIG. 6 illustrates a case in which one fluorescent layer contains one type of infrared phosphor. In a further modification, two or more types of infrared phosphors may be contained in one fluorescent layer. For example, one fluorescent layer may contain a first infrared phosphor and a second infrared phosphor, or a first infrared phosphor, a second infrared phosphor, and a third infrared phosphor. The combination of infrared phosphors contained may also vary depending on the fluorescent layer serving as the reference for positioning. By combining two or more types of infrared phosphors, the number of patterns for identifying the fluorescent layers can be increased using a limited number of infrared phosphors. This allows for more precise identification of the positions of the fluorescent layers when the display body 12C has a large number of stacked layers 30, improving the display accuracy of the 3D image S.

[0061] (Fifth embodiment) 8 is a diagram schematically illustrating the configuration of a display device 10D according to a fifth embodiment. The fifth embodiment differs from the first embodiment in that a power supply 70 that applies a voltage between the first surface 26 and the second surface 28 of the display body 12 is provided instead of the second irradiating unit 16. The following description of the fifth embodiment will focus on the differences from the first embodiment, and commonalities with the first embodiment will be omitted as appropriate.

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

[0063] The display 12D is configured similarly to the display 12 according to the first embodiment, but differs from the first embodiment in that it is conductive. The first fluorescent layer 31, the second fluorescent layer 32, and the third fluorescent layer 33 included in the plurality of laminates 30 of the display 12D are each configured to be conductive. For example, the first fluorescent layer 31, the second fluorescent layer 32, and the third fluorescent layer 33 can be configured to be conductive by using a conductive polymer such as polyacetylene or polythiophene as the base material. Alternatively, the first fluorescent layer 31, the second fluorescent layer 32, and the third fluorescent layer 33 may be made conductive by incorporating conductive particles therein.

[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. Like the first electrode 66, the second electrode 68 is preferably a transparent electrode, but does not have to 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 12D, the power supply 70 electrically excites the phosphor contained in the display 12D. The power supply 70 applies an auxiliary voltage to the entire display 12D, which additionally excites the phosphor contained in the display 12D. When electrically exciting the phosphor, the amount of light emitted by the phosphor depends on the current density; the greater the current density, the greater the amount of light emitted. The power supply 70 controls the current flowing between the first electrode 66 and the second electrode 68 so that the current density is low enough that the phosphor does not generate ASE when the first excitation light 20 is not irradiated. In other words, 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," which is the current density required to generate ASE. The power supply 70 may include a constant current circuit.

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

[0067] The control unit 18 may control the operation of the power supply 70 to change the current density of the current flowing through the display body 12D depending on the focusing position 24 of the first excitation light 20. For example, the amount of current (or current density) flowing through the display body 12D may be increased as the focusing position 24 of the first excitation light 20 approaches the second surface 28, that is, as it moves farther from the first surface 26. This may allow the phosphor to generate ASE at the focusing position 24 while suppressing variation in the total contribution of the first excitation light 20 and the contribution of electrical excitation by the power supply 70 at the focusing position 24.

[0068] (Sixth embodiment) 9 is a diagram schematically illustrating the configuration of a display device 10E according to a sixth embodiment. The sixth embodiment differs from the fifth embodiment in that separate power supplies 70a and 70b are connected to the central and peripheral portions of a display body 12D. The following description of the sixth embodiment will focus on the differences from the fifth embodiment, and will omit commonalities with the fifth embodiment as appropriate.

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

[0070] The second electrode 68 has a central electrode 68a provided in the center of the second surface 28 of the display 12, and a peripheral electrode 68b provided in 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, which is higher than the first current density, through the peripheral portion of the display body 12D. Because the peripheral portion of the display body 12D is relatively far from the mirror 46, the focused intensity of the first excitation light 20 is relatively low compared to the central portion of the display body 12D. Therefore, by making the current density in the central portion of the display body 12D relatively low and the current density in the peripheral portion of the display body 12D relatively high, it is possible to reduce the variation in the total contribution of the first excitation light 20 and the electrical excitation at the focused position 24, which is caused by a change in the position of the focused position 24.

[0072] 9 shows the case where two electrodes 68a, 68b are provided on the second surface 28. In a further modification, three or more electrodes may be provided concentrically on the second surface 28, and each of the three or more electrodes may be connected to a separate power supply. In this case, a voltage may be applied so that the current density is lower in the center of the display body 12D and higher in the peripheral portion of the display body 12D.

[0073] 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.

[0074] In the third and fourth embodiments, the second irradiating unit 16 may not be used, and the power supply 70 for applying the auxiliary voltage in the fifth or sixth embodiment may be used instead of the second irradiating unit 16. Furthermore, in the third to sixth embodiments, the first irradiating unit 14A including the collimating lens 41 in the second embodiment may be used.

[0075] Several aspects of the present invention are described below.

[0076] [Aspect 1] a display body in which a plurality of fluorescent layers containing a phosphor are stacked from a first surface to a second surface; a first irradiating unit that irradiates first excitation light that is incident on the first surface and excites the phosphor while changing a focusing position of the first excitation light within the display; a second irradiating unit that irradiates second excitation light that is incident on the second surface and excites the phosphor, the light intensity of the second excitation light is less than a threshold of the amplified spontaneous emission of the phosphor; A display device, wherein a total value of the light intensity of the first excitation light and the second excitation light is equal to or greater than a threshold value of amplified spontaneous emission light of the phosphor. [Aspect 2] 2. The display device according to aspect 1, wherein the second irradiator changes the light intensity of the second excitation light depending on the focused position of the first excitation light. [Aspect 3] 3. The display device of aspect 1 or 2, wherein the second irradiator irradiates the entire second surface with the second excitation light. [Aspect 4] 4. The display device of aspect 3, wherein the second irradiator irradiates the second excitation light having an intensity distribution in which the light intensity is higher in a peripheral portion of the second surface than in a central portion of the second surface. [Aspect 5] a step of irradiating a first excitation light incident on a first surface of a display body in which a plurality of fluorescent layers containing a phosphor are stacked from a first surface to a second surface to excite the phosphor, while changing a focusing position of the first excitation light within the display body; irradiating the second surface with second excitation light that is incident on the second surface and excites the phosphor; the light intensity of the second excitation light is less than a threshold of the amplified spontaneous emission of the phosphor; A display method, wherein the sum of the light intensities of the first excitation light and the second excitation light is equal to or greater than a threshold value for amplified spontaneous emission of the phosphor.

[0077] [Aspect 6] a display body in which 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 are stacked; an irradiation unit that irradiates the display body with excitation light that is incident on the display body and excites the first phosphor and the second phosphor, while changing a focusing position of the excitation light within the display body; an optical sensor that measures the light intensity of each wavelength of light emitted from the display; a control unit that controls the focusing 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 includes a fluorescent layer containing an infrared phosphor having an emission wavelength in the infrared region, 7. The display device according to aspect 6, wherein the control unit controls a focusing position of the excitation light, further based on the light intensity of the emission wavelength of the infrared phosphor measured by the optical sensor. [Aspect 8] the display includes a fluorescent layer containing a first infrared phosphor having an emission wavelength in an infrared region, and a fluorescent layer containing a second infrared phosphor having an emission wavelength in an infrared region different from that of the first infrared phosphor, The display device described in aspect 7, wherein the control unit controls the focusing 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. [Aspect 9] the display includes a fluorescent layer containing two or more of a plurality of types of infrared phosphors having different emission wavelengths in the infrared range, 10. The display device according to claim 8, wherein the control unit controls the focusing position of the excitation light based further on the light intensity of each of the emission wavelengths of the plurality of types of infrared phosphors measured by the optical sensor. [Aspect 10] a step of irradiating excitation light incident on a display body in which 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 are stacked, the excitation light exciting the first phosphor and the second phosphor, while changing a focusing position of the excitation light within the display body; measuring the intensity of light emitted from the display by wavelength using an optical sensor; and controlling the focusing 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.

[0078] [Aspect 11] a display body in which a plurality of fluorescent layers containing a phosphor are stacked 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 excitation light that is incident on the display body and excites the phosphor, while changing a focusing position of the excitation light within the display body. [Aspect 12] 12. The display device according to aspect 11, wherein the power supply changes the amount of current flowing between the first electrode and the second electrode depending on the focused position of the excitation light. [Aspect 13] the power supply is configured to pass a current between the first electrode and the second electrode that is less than a threshold current density for amplified spontaneous emission at which the phosphor can generate amplified spontaneous emission; 13. The display device according to aspect 11 or 12, wherein the irradiating unit irradiates the phosphor with the excitation light having a light intensity that enables the phosphor to generate amplified spontaneous emission light. [Aspect 14] the second electrode has a central electrode provided in a central portion of the second surface and a peripheral electrode provided in a peripheral portion of the second surface, A display device described in any one of aspects 11 to 13, wherein the power supply has a first power supply for passing a current of a first current density between the first electrode and the central electrode, and a second power supply for passing a current of a second current density greater than the first current density between the first electrode and the peripheral electrode. [Aspect 15] a step of applying a DC voltage between a first electrode provided on a first surface of a display body in which a plurality of fluorescent layers containing a phosphor are stacked from a first surface to a second surface, and a second electrode provided on the second surface; and irradiating the display body with excitation light that is incident on the display body and excites the phosphor while changing a focusing position of the excitation light within the display body. [Explanation of symbols]

[0079] 10...display device, 12...display body, 14...first irradiation section, 16...second irradiation section, 18...control section, 20...first excitation light, 22...second excitation light, 24...focusing position, 26...first surface, 28...second surface, 30...laminated body, 31...first fluorescent layer, 32...second fluorescent layer, 33...third fluorescent layer, 40...light source, 41...collimating lens, 42...focusing lens, 44...lens driving mechanism, 46...mirror, 48...mirror driving mechanism, 50...image sensor, 52...optical sensor, 66...first electrode, 68...second electrode, 70...power supply.

Claims

1. a display body in which a plurality of fluorescent layers containing a phosphor are stacked from a first surface to a second surface; a first excitation light that is incident on the first surface and excites the phosphor, a first irradiating unit that irradiates the first excitation light while changing a focusing position of the first excitation light; The light intensity of the second excitation light incident on the second surface and exciting the phosphor is adjusted to be equal to or greater than the light intensity of the first excitation light. a second irradiating unit that irradiates the light while changing the irradiating light depending on the condensed position of the light, the light intensity of the second excitation light is less than a threshold of the amplified spontaneous emission of the phosphor; The sum of the light intensities of the first excitation light and the second excitation light is the spontaneous emission amplification of the phosphor. A display device that is above the light threshold.

2. A display body in which a plurality of fluorescent layers containing a phosphor are stacked from a first surface toward a second surface; a first excitation light that is incident on the first surface and excites the phosphor, a first irradiating unit that irradiates the first excitation light while changing a focusing position of the first excitation light; a second irradiating unit that irradiates the entire second surface with second excitation light that excites the phosphor; Preparation, the light intensity of the second excitation light is less than a threshold of the amplified spontaneous emission of the phosphor; The sum of the light intensities of the first excitation light and the second excitation light is the spontaneous emission amplification of the phosphor. A display device that is above the light threshold.

3. A display body in which a plurality of fluorescent layers containing a phosphor are stacked from a first surface toward a second surface; a first excitation light that is incident on the first surface and excites the phosphor, a first irradiating unit that irradiates the first excitation light while changing a focusing position of the first excitation light; a second irradiating unit that irradiates second excitation light that is incident on the second surface and excites the phosphor; Equipped with the light intensity of the second excitation light is less than a threshold of the amplified spontaneous emission of the phosphor; The sum of the light intensities of the first excitation light and the second excitation light is the spontaneous emission amplification of the phosphor. above the light threshold, The second irradiating unit has a light intensity at a peripheral portion of the second surface higher than that at a central portion of the second surface. the display device irradiates the second excitation light having a high intensity distribution.

4. In front of a display body in which a plurality of fluorescent layers containing a fluorescent material are stacked from a first surface to a second surface a first excitation light incident on the first surface to excite the phosphor; irradiating the first excitation light while changing the focusing position of the first excitation light; The light intensity of the second excitation light incident on the second surface and exciting the phosphor is adjusted to be equal to or greater than the light intensity of the first excitation light. and irradiating the light while changing the light intensity depending on the focusing position of the light, the light intensity of the second excitation light is less than a threshold of the amplified spontaneous emission of the phosphor; The sum of the light intensities of the first excitation light and the second excitation light is the spontaneous emission amplification of the phosphor. A method of displaying light that is above the threshold of light.

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