Stereoscopic display device and stereoscopic display method

Abstract

To control the state of a three-dimensional image in accordance with a situation of how it is observed.SOLUTION: A three-dimensional display device comprises: a laser light source; a conversion unit for converting laser light into collimated light of a prescribed diameter; a scanning unit for changing a focal position where collimated light is converged and an optical axis direction in which collimated light is emitted, with a drawing space where a fluorescent substance is included that emits light upon excitation with laser light defined as the range to be scanned, thereby three-dimensionally scanning the focal position of laser light; a distance detection unit for detecting the distance between an observer observing the drawing space and the drawing space; a distance correction information acquisition unit for acquiring distance correction information from a storage unit that stores a correspondence between distance and laser light intensity as the distance correction information; and an intensity control unit for controlling intensity at the focal position of laser light scanned by the scanning unit, on the basis of drawing data indicating emission intensity for each position in the drawing space, and distance correction information corresponding to the detected distance.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, various methods have been proposed for a stereoscopic display device that displays an image in the air. As an example of such a conventional stereoscopic display device, a technique is disclosed in which voxels (spatial pixels) are formed by condensing a laser to generate plasma and an image is displayed in the air (see, for example, Patent Document 1).

Prior Art Document

[0007] [2] In addition, in one aspect of the present invention, in the stereoscopic display device described in [1] above, the intensity control unit controls the intensity by making the number of light emission positions along the optical axis direction of the fluorescent material light emission at least three different numbers.

[0008] [3] Another aspect of the present invention is a stereoscopic display device as described in [1] above, further comprising: an illuminance detection unit for detecting the illuminance of the surrounding environment of the drawing space; and an illuminance correction information acquisition unit for acquiring illuminance correction information from a storage unit that stores the correspondence between the illuminance and the intensity of the laser light as illuminance correction information, wherein the intensity control unit controls the intensity of the laser light based on the illuminance correction information corresponding to the detected illuminance.

[0009] [4] In addition, in one aspect of the present invention, in the stereoscopic display device described in [1] above, the fluorescent material has a first region in which the self-luminescence intensity changes in response to a change in the intensity of the irradiated laser light, and a second region in which the self-luminescence intensity changes more slowly than the change in the self-luminescence intensity of the first region, and the intensity control unit causes the fluorescent material located at a position away from the focal point in the optical axis direction to emit light by setting the intensity of the laser light at the focal point to an intensity in which the fluorescent material at the focal point reaches the saturation region.

[0010] [5] In addition, one aspect of the present invention is a stereoscopic display device as described in [1] above, further comprising a modulation unit that changes the spatial frequency distribution of the laser light to give a periodic distribution to the intensity of the laser light along the optical axis from the focusing position, wherein the intensity control unit controls the number of emission positions in which the fluorescent material emits light along the optical axis, which are caused by the periodic distribution given by the modulation unit, to be at least three different numbers.

[0011] [6] One aspect of the present invention is a stereoscopic display method comprising: emitting laser light; converting the emitted laser light into collimated light of a predetermined diameter; scanning the focal length at which the collimated light converges and the optical axis direction from which the collimated light is emitted, with a drawing space containing a fluorescent substance that is excited and self-luminesces when irradiated with laser light as the scanning target range, by changing the focal length at which the collimated light converges and the optical axis direction from which the collimated light is emitted; detecting the distance between an observer observing the drawing space and the drawing space; acquiring distance correction information from a storage unit that stores the correspondence between the distance and the intensity of the laser light as distance correction information; and controlling the intensity of the laser light at the focal position based on drawing data indicating the emission intensity for each position in the drawing space and the distance correction information corresponding to the detected distance. [Effects of the Invention]

[0012] According to the present invention, the state of the three-dimensional image can be controlled according to the circumstances under which it is observed. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows an example of the configuration of the stereoscopic display device according to this embodiment. [Figure 2] This figure shows an example of the operation flow of the stereoscopic display device of this embodiment. [Figure 3] This figure shows an example of the luminescence intensity characteristics of the fluorescent material in this embodiment. [Figure 4] This figure shows an example of the luminescence state of the fluorescent material in this embodiment. [Figure 5] This figure shows an example of scanning the converged light in this embodiment. [Figure 6] This figure shows another example of scanning the converged light in this embodiment. [Figure 7] This figure shows an example of distance correction information stored in the memory unit of this embodiment. [Figure 8] This figure shows an example of illuminance correction information stored in the memory unit of this embodiment. [Figure 9] This figure shows an example of a control table stored in the memory unit of this embodiment. [Figure 10] This figure shows an example of a control mode by the control unit of this embodiment. [Modes for carrying out the invention]

[0014] A preferred embodiment of the three-dimensional display device according to an aspect of the present invention will be described in detail below with reference to the accompanying drawings. Note that the embodiments described below are merely examples, and the embodiments to which the present invention is applied are not limited to the following embodiments. In addition, as used in the present application, "based on XX" means "based on at least XX", and includes cases where it is based on another element in addition to XX. Also, "based on XX" is not limited to the case where XX is directly used, and includes cases where it is based on something obtained by performing operations or processing on XX. "XX" is an arbitrary element (for example, arbitrary information). In addition, in the following drawings, in order to make each configuration easier to understand, the scale and number in each structure may be different from the scale and number in the actual structure. Hereinafter, embodiments will be described with reference to FIGS. 1 to 10.

[0015] [[ID=*6*]][Functional Configuration of Three-Dimensional Display Device 1] FIG. 1 is a diagram showing an example of the configuration of the three-dimensional display device 1 of the present embodiment. The three-dimensional display device 1 is a device that displays a three-dimensional image in the drawing space 2 by scanning the laser beam L with the drawing space 2 containing the fluorescent substance 21 as the scanning target range. The drawing space 2 is a space capable of holding the fluorescent substance 21 inside. As an example, the drawing space 2 is the internal space of a cylindrical container having a cylindrical transparent wall in which a powdery fluorescent substance 21 is enclosed. In this case, the drawing space 2 is a hollow region. As another example, the drawing space 2 is an object formed of a transparent resin in which the fluorescent substance 21 is kneaded. In this case, the drawing space 2 is a solid region. That is, the "space" of the drawing space 2 only needs to be a region that spreads three-dimensionally, regardless of whether it is hollow or solid. Also, the drawing space 2 may be composed of any of gas, liquid, and solid.

[0016] [[ID=1*5*]] The three-dimensional display device 1 includes a light source unit 10, an emitting unit 20, a storage unit 30, a distance detection unit 40, an illuminance detection unit 50, and a control unit 60.

[0017] The light source unit 10 includes a laser light source 110 and a conversion unit 120. Note: In the translation, the content in the tags , ,

[0015] , , , , , ,

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[0017] , are preserved as they are because they are likely some kind of specific identifiers or codes in the original patent text and need to be kept unchanged for accurate reference in the patent context. Also, the text in [* brackets *] in the original is likely a formatting or marking error in the provided text, and I have made a best guess for the translation based on the overall context. If there is a specific rule or correction for these marked parts, please let me know for a more accurate translation. The laser light source 110 emits a laser beam L. The laser light source 110 may be, for example, an ultraviolet laser or a small laser diode with a wavelength of 405 nm. In the following description, the laser beam L emitted by the laser light source 110 is also referred to as the source light L1.

[0018] The source light L1 emitted from the laser light source 110 is not a parallel beam, but has the property of spreading and advancing in a conical shape with the laser light source 110 as the apex. The source light L1 immediately after being emitted from the laser light source 110 has a sufficiently small diameter. On the other hand, the source light L1 at a position far from the laser light source 110 has a larger diameter compared to the source light L1 immediately after being emitted. Therefore, the source light L1 immediately after being emitted from the laser light source 110 has a relatively high energy per unit area in the radial direction. Also, the source light L1 at a position far from the laser light source 110 has a relatively low energy per unit area in the radial direction. <00001​​​​​​​​​​​​As described above, the focused light L3 is light obtained by focusing (i.e., reducing the diameter) the collimated light L2. Therefore, the focused light L3 has a relatively higher energy per unit area in the radial direction compared to the collimated light L2. The energy per unit area in the radial direction of the focused light L3 is highest at the position where it is most focused (reduced in diameter). In other words, the energy of the focused light L3 incident on the fluorescent material 21 is highest at the position where it is most focused (reduced in diameter).

[0022] The output unit 20 comprises a modulation unit 220, a convergence unit 230, and a scanning unit 240. The modulation unit 220 includes, for example, a spatial phase modulator 221 and a two-dimensional diffraction grating 222, which change the spatial frequency distribution of the collimated light L2. As a result, a periodic distribution occurs in the intensity of the laser light L in the direction of the optical axis AX of the focused light L3 emitted from the emission unit 20. In other words, the modulation unit 220 changes the spatial frequency distribution of the collimated light L2, thereby giving a periodic distribution to the intensity of the focused light L3 (laser light L) along the direction of the optical axis AX (optical axis direction) from the focusing position 23. In Figure 1, the spatial phase modulator 221 is depicted as a transmissive type, but it may also be a reflective type. Transmissive and reflective spatial light modulators are distinguished by the direction of the incident light (readout light) relative to the output light. In a transmissive spatial light modulator, the incident light (readout light) passes through the spatial light modulator and irradiates the output light, while in a reflective spatial light modulator, the incident light (readout light) is reflected from the spatial light modulator and irradiates the output light.

[0023] The focusing unit 230 includes a focusing lens 231. The focusing lens 231 can change the position (i.e., focal length) where the transmitted laser light L converges, based on the control of the control unit 60.

[0024] The scanning unit 240 is equipped with a scanning mirror 241 (for example, a galvanometer mirror, a polygon mirror, etc.) and changes the emission direction of the laser beam L that the focusing unit 230 focuses. Here, the direction in which the scanning unit 240 scans the drawing space 2 will be explained using a three-dimensional Cartesian coordinate system of XYZ. The X and Y axes of the three-dimensional Cartesian coordinate system represent the field of view when viewed from the emission unit 20 in the drawing space 2. The X axis indicates the horizontal direction of the drawing space 2 (left-right direction in Figure 1). The Y axis indicates the vertical direction of the drawing space 2 (up-down direction in Figure 1). The scanning unit 240 can emit the convergent light L3 toward any position in the XY plane of the drawing space 2 by changing the direction of the scanning mirror 241. In other words, the scanning unit 240 can be described as a two-dimensional scanning unit that scans the convergent light L3 in two dimensions in the XY plane. The Z-axis of the three-dimensional Cartesian coordinate system represents the depth when looking from the emission unit 20 into the drawing space 2. The aforementioned converging unit 230 can change the focusing position 23 of the converging light L3 in the Z-axis direction by changing the focusing position of the converging light L3 (the focal length of the converging lens 231). In other words, the converging unit 230 and the scanning unit 240 together constitute a three-dimensional scanning unit that performs three-dimensional scanning of the converging light L3 in XYZ space. In the following explanation, the scanning unit 240 may also refer to the three-dimensional scanning unit which is the combination of the converging unit 230 and the scanning unit 240.

[0025] In other words, the scanning unit 240 scans the focusing position 23 of the laser light L in three dimensions by changing the focal length at which the focusing light L3 converges and the direction of the optical axis AX from which the focusing light L3 is emitted, using the drawing space 2, which contains a fluorescent substance 21 that is excited and self-luminescent when irradiated with light source L1, as the scanning target range.

[0026] In this embodiment, the scanning unit 240 may also include a light intensity adjustment unit (e.g., an aperture) for adjusting the amount of light emitted from the laser beam L (collimating light L2 or focusing light L3), and a blocking unit (e.g., a shutter) for blocking the emission of the laser beam L (neither of which are shown). These light intensity adjustment units and blocking units are synchronized with the focusing unit 230 and the scanning unit 240 to control the focusing position 23 of the focusing light L3 to any position in the drawing space 2.

[0027] The distance detection unit 40 is equipped with a known distance measurement function such as a TOF (Time of Flight) sensor, and detects the distance D between the observer 400 observing the drawing space 2 and the drawing space 2. Alternatively, the distance detection unit 40 may be a camera or the like.

[0028] The illuminance detection unit 50 is equipped with a known illuminance detection function, such as an illuminance meter, and detects the illuminance of the surrounding environment of the drawing space 2. Here, the illuminance of the surrounding environment of the drawing space 2 is, for example, the brightness of the room if the drawing space 2 is located indoors, and for example, the brightness of the space if the drawing space 2 is located in an open space outdoors. Here, "illuminance" can refer to a physical quantity with the unit [lx (lux)], or it can refer to brightness in a broader sense, including physical quantities related to the intensity of light such as "luminous flux" and "luminous intensity." In the following explanation, when "illuminance" is used, it also includes the meaning of "brightness."

[0029] The memory unit 30 has known storage functions, such as semiconductor memory devices and magnetic memory devices, and stores various types of information used by the control unit 60. For example, the memory unit 30 stores distance correction information 310. Distance correction information 310 is information that shows the correspondence between distance D and the intensity of the focused light L3 (laser light L).

[0030] The control unit 60 is, for example, a CPU or computer device, and provides predetermined functions based on programs and data stored in the storage unit 30. The control unit 60 includes, as its functional units, a distance correction information acquisition unit 610, an intensity control unit 620, an illuminance correction information acquisition unit 630, and a phase control unit 640.

[0031] The distance correction information acquisition unit 610 acquires distance correction information 310 from the storage unit 30. That is, the distance correction information acquisition unit 610 acquires distance correction information 310 from the storage unit 30, which stores the correspondence between distance D and the intensity of laser light L (for example, focused light L3) as distance correction information 310.

[0032] The intensity control unit 620 controls the intensity of the laser light L emitted by the emission unit 20 based on the drawing data stored in the memory unit 30. The drawing data is information indicating the brightness of the image at each three-dimensional position in the drawing space 2. In other words, the drawing data is information for displaying the three-dimensional image 22. In other words, the intensity control unit 620 controls the intensity of the converged light L3 (laser light L) scanned by the scanning unit 240 at the focusing position 23, based on drawing data indicating the emission intensity for each position in the drawing space 2 and distance correction information 310 corresponding to the distance D detected by the distance detection unit 40. The intensity control unit 620 of this embodiment controls the intensity of the laser light L based on the distance D between the drawing space 2 and the observer 400, thereby forming a three-dimensional image that is easy for the observer 400 to see.

[0033] The illuminance correction information acquisition unit 630 acquires illuminance correction information 320 from the storage unit 30. That is, the illuminance correction information acquisition unit 630 acquires illuminance correction information 320 from the storage unit 30, which stores the correspondence between illuminance and the intensity of the laser light L as illuminance correction information 320. The intensity control unit 620 controls the intensity of the laser light L based on the illuminance correction information 320 corresponding to the detected illuminance. In other words, the intensity control unit 620 controls the intensity of the focused light L3 (laser light L) scanned by the scanning unit 240 at the focusing position 23, based on drawing data indicating the light emission intensity for each position in the drawing space 2 and illuminance correction information 320 corresponding to the illuminance detected by the illuminance detection unit 50. The illuminance detected by the illuminance detection unit 50 indicates the brightness of the surrounding environment of the drawing space 2. The intensity control unit 620 in this embodiment controls the intensity of the laser light L based on the brightness of the surrounding environment of the drawing space 2, thereby forming a three-dimensional image that is easy for the observer 400 to see.

[0034] The phase control unit 640 controls the phase of the focused light L3 at the focusing position 23 by controlling the modulation state of the spatial frequency distribution of the collimated light L2 by the spatial phase modulator 221 and the two-dimensional diffraction grating 222 provided in the modulation unit 220.

[0035] [Operation of the 3D display device 1] Next, with reference to Figure 2, an example of the operation flow of the stereoscopic display device 1 will be described. Figure 2 shows an example of the operation flow of the stereoscopic display device 1 of this embodiment. (Step S10) The control unit 60 acquires drawing data from the storage unit 30. As described above, the drawing data is information for displaying the three-dimensional image 22. (Step S20) The control unit 60 acquires distance information from the distance detection unit 40. As described above, the distance information is information indicating the distance D between the drawing space 2 and the observer 400 detected by the distance detection unit 40. (Step S30) The control unit 60 acquires illuminance information from the illuminance detection unit 50. As described above, illuminance information is information indicating the brightness of the surrounding environment of the drawing space 2 detected by the illuminance detection unit 50.

[0036] (Step S40) The control unit 60 acquires correction information for the intensity of the laser light L from the storage unit 30. Specifically, the distance correction information acquisition unit 610 acquires distance correction information 310 from the storage unit 30. The illuminance correction information acquisition unit 630 acquires illuminance correction information 320 from the storage unit 30. (Step S50) The control unit 60 controls the emission intensity of the laser light L by controlling the laser light source 110. Here, an example of the emission intensity characteristics of the fluorescent material 21 will be described with reference to Figure 3.

[0037] Figure 3 shows an example of the emission intensity characteristics of the fluorescent material 21 in this embodiment. The figure shows the emission intensity characteristics F1 of the first fluorescent material and the emission intensity characteristics F2 of the second fluorescent material superimposed on each other. The horizontal axis of the figure represents the intensity of the laser light L (i.e., excitation light) incident on the fluorescent material 21, and the vertical axis represents the intensity of emission emitted by the fluorescent material 21 excited by the excitation light (i.e., the emission intensity of the fluorescent material 21). The first fluorescent material is, for example, a quantum dot (QD) dispersion. A QD dispersion is obtained by scattering quantum dots in an organic solvent (e.g., toluene), a gas, or a solid at a predetermined volume concentration. The second fluorescent material is, for example, a multiphoton absorber. The second fluorescent material may also be a QD dispersion. Various materials such as CdS, CdSe, CdTe, ZnCdSe / ZnS, and Cd-free perovskite can be used as quantum dots. In addition to quantum dots, various known fluorescent materials such as YAG, CASN, CSO, and SBCA can be used.

[0038] The first fluorescent material exhibits a monotonically increasing emission intensity from an excitation light intensity of 0 to a threshold th1, reaching an emission intensity of E1 at the threshold th1. When the excitation light intensity exceeds the threshold th1, the emission intensity of the first fluorescent material ceases to increase. In other words, the first fluorescent material has an emission intensity characteristic F1 that has a change region (first region) and a saturation region (second region) separated by an inflection point IP1. In other words, in the case of the first fluorescent material, the fluorescent material 21 has a change region in which the intensity of self-luminescence changes in response to changes in the intensity of the irradiated laser light L, and a saturation region in which the intensity of self-luminescence does not change. However, although the intensity of self-luminescence in the saturation region is said to not change, it is not limited to this, and small changes are permitted. That is, in the saturation region, the intensity of self-luminescence only needs to change more slowly than the change in the intensity of self-luminescence in the change region.

[0039] The second fluorescent material has an emission intensity characteristic F2 in which the emission intensity of the fluorescent material 21 does not increase when the excitation light intensity is between 0 (zero) and the threshold th2, and the emission intensity increases monotonically when it exceeds the threshold th2. When using the second fluorescent material (multiphoton absorber), an ultrashort pulse infrared laser can be used as the laser light source 110.

[0040] Figure 4 shows an example of the emission state of the fluorescent material 21 in this embodiment. Figure (A) shows an example of the focusing position 23 of the focused light L3. Figure (B) shows a first example of the emission state of the fluorescent material 21 at the focusing position 23. Figure (C) shows a second example of the emission state of the fluorescent material 21 at the focusing position 23.

[0041] When the laser light L is emitted as focused light L3, the energy per unit volume at the focusing position 23 is higher than the energy per unit volume in the space outside the focusing position 23. The stereoscopic display device 1 of this embodiment emits laser light L with an intensity such that the fluorescent material 21 does not emit light in the space other than the focusing position 23, but the fluorescent material 21 does emit light at the focusing position 23. With the stereoscopic display device 1 configured in this way, as shown in Figure 4(B), a stereoscopic image 22 can be drawn in the drawing space 2 by controlling the fluorescent material 21 at the focusing position 23 to emit light and the fluorescent material 21 in the space other than the focusing position 23 to not emit light. In one example shown in Figure 4(B), the light emission point P1 can be drawn.

[0042] Here, we will explain the case where the fluorescent material 21 has saturation characteristics (luminescence intensity characteristics F1), as described above for the first fluorescent material. If the fluorescent material 21 has saturation characteristics, even if it is irradiated with excitation light stronger than the threshold th1 described above, it will not emit light brighter. On the other hand, if excitation light stronger than the threshold th1 is irradiated, some of the multiple fluorescent materials 21 at the focusing position 23 may emit light, particularly those near the saturated fluorescent material 21 (specifically, at a position shifted in the Z direction on the optical axis AX). As shown in Figure (C), if the intensity of the laser light L is increased above the threshold th1, in addition to the emission point P1 where the laser light L is sufficiently focused (reduced in diameter), emission points P2 and P3 where the laser light L is not sufficiently focused (reduced in diameter) can also be drawn at the focusing position 23.

[0043] In this embodiment, the intensity control unit 620 can cause the fluorescent material 21 located at a position away from the focal point 23 in the direction of the optical axis AX (optical axis direction) to emit light by adjusting the intensity of the laser light L at the focal point 23 to an intensity that causes the fluorescent material 21 at the focal point 23 to reach a saturation region.

[0044] In some cases, the fluorescent material 21 may be a second fluorescent material (for example, a multiphoton absorber). In this case, the fluorescent material 21 emits light according to the number of photons it absorbs. The intensity control unit 620 can also control the emission position of the fluorescent material 21 by controlling the intensity of the laser light L, thereby changing the number of photons absorbed by the fluorescent material 21.

[0045] (Step S60) Returning to Figure 2, the phase control unit 640 of the control unit 60 controls the phase of the focused light L3. As described above, the emission state of the fluorescent material 21 at the focusing position 23 can be controlled by changing the intensity of the laser light L at the focusing position 23 (more precisely, the intensity distribution of the laser light L in space). By controlling the phase of the focused light L3, the phase control unit 640 can cause only one point to emit light in the direction of the optical axis AX (the emission point P1 described above), or multiple points (for example, three points) to emit light in the direction of the optical axis AX (the emission points P1 to P3 described above).

[0046] In the following explanation, illuminating one point along the optical axis AX is referred to as "single-point drawing," illuminating two points along the optical axis AX is referred to as "two-point drawing," and illuminating three points along the optical axis AX is referred to as "three-point drawing."

[0047] In other words, the intensity control unit 620 controls the number of emission positions where the fluorescent material 21 emits light along the direction of the optical axis AX (optical axis direction), which is generated by the periodic distribution provided by the modulation unit 220, by setting the number of emission positions to at least three different numbers.

[0048] (Step S70) The control unit 60 controls the focusing position 23 of the focused light L3 by controlling the focusing lens 231 of the focusing unit 230 and the scanning mirror 241 of the scanning unit 240 (i.e., by driving the scanning unit).

[0049] Figure 5 shows an example of scanning of the convergent light L3 in this embodiment. The control unit 60 sequentially moves the optical axis AX of the convergent light L3 in the X-axis direction from the first irradiation (first scan SC1) to the nth irradiation (nth scan SCn), and performs two-point drawing. When two-point drawing is performed at the first focusing position, light emission points P21 and P31 can be made to emit light. When two-point drawing is performed at the second focusing position, light emission points P22 and P32 can be made to emit light.

[0050] Figure 6 shows another example of scanning of the convergent light L3 in this embodiment. The control unit 60 sequentially moves the optical axis AX of the convergent light L3 in the X-axis direction from the first irradiation (first scan SC1) to the nth irradiation (nth scan SCn) to perform two-point drawing. In this example, the multiple focusing positions 23 are closer to each other in the Z-axis direction compared to the case shown in Figure 5. When two-point drawing is performed in this state, the light emission point P21 at the first focusing position and the light emission point P22 at the second focusing position are close in the Z-axis direction. As a result, the number of light emission points P per unit volume (i.e., the volume density of light emission points P) is higher compared to the case shown in Figure 5. As described above, the control unit 60 of this embodiment can freely control the number of light-emitting points P in the optical axis AX direction by controlling the intensity and phase of the laser light L. With a stereoscopic display device 1 equipped with such a control unit 60, the rendering state of the stereoscopic image 22 (for example, the brightness, contrast, spatial resolution, etc. of the stereoscopic image 22) can be freely controlled.

[0051] The control unit 60 may implement the "single-point drawing," "two-point drawing," and "three-point drawing" described above by combining the intensity of the laser light L (laser output) with phase control by the spatial phase modulator 221. The control unit 60 may also select "single-point drawing," "two-point drawing," and "three-point drawing" according to the distance D detected by the distance detection unit 40, or the combination of distance D and illuminance detected by the illuminance detection unit 50. The control unit 60 performs control based on distance correction information 310 and illuminance correction information 320 that are pre-stored in the memory unit 30.

[0052] Figure 7 shows an example of distance correction information 310 stored in the memory unit 30 of this embodiment. As an example of distance correction information 310, control mode "mode A" is associated with distance D "less than 50 cm", control mode "mode B" is associated with distance D "50 cm or more and less than 100 cm", and control mode "mode C" is associated with distance D "100 cm or more".

[0053] Figure 8 shows an example of illuminance correction information 320 stored in the memory unit 30 of this embodiment. As an example of illuminance correction information 320, one of the control modes "Mode A", "Mode B", and "Mode C" is associated with a combination of distance D and the illuminance (brightness) of the surrounding environment.

[0054] The control unit 60 selects a control mode by referring to the combination of the distance D detected by the distance detection unit 40 and the distance correction information 310. Alternatively, the control unit 60 selects a control mode by referring to the combination of the distance D detected by the distance detection unit 40, the illuminance (brightness) of the surrounding environment of the drawing space 2 detected by the illuminance detection unit 50, and the illuminance correction information 320.

[0055] Figure 9 shows an example of a control table 330 stored in the memory unit 30 of this embodiment. In the control table 330, each of the control modes described above (for example, mode A, mode B, mode C) is associated with the intensity of the laser light L (laser output) and the state of phase control by the spatial phase modulator 221 (for example, 1-point control, 2-point control, 3-point control).

[0056] The control unit 60 refers to the control table 330 and controls the laser light source 110 and the spatial phase modulator 221 based on the intensity of the laser light L (laser output) according to the control mode and the state of phase control by the spatial phase modulator 221.

[0057] Figure 10 shows an example of a control mode by the control unit 60 of this embodiment. The control unit 60 selects one of the above modes A, mode B, or mode C based on the combination of the distance D between the drawing space 2 (i.e., the display) and the observer 400, and the illuminance (brightness) of the surrounding environment of the drawing space 2, and controls the number of light emission positions (i.e., number of light emission points) of the fluorescent material 21 on the optical axis AX.

[0058] In other words, the intensity control unit 620 controls the intensity by setting the number of emission positions where the fluorescent material 21 emits light along the direction of the optical axis AX (i.e., the optical axis direction) to at least three different numbers.

[0059] For example, if the 3D display device 1 wants to prioritize high definition over brightness when displaying the 3D image 22, it will render it using "single-point drawing". For example, if the stereoscopic display device 1 prioritizes brightness over high resolution when displaying the stereoscopic image 22, it will render it using "two-point rendering" or "three-point rendering". For example, the 3D display device 1 can also switch between "single-point drawing," "two-point drawing," or "three-point drawing" depending on the display dimensions (size) of the 3D image 22 in the drawing space 2.

[0060] As described above, the stereoscopic display device 1 of this embodiment controls the number of light-emitting positions (i.e., the number of light emission points) of the fluorescent material 21 on the optical axis AX based on the detection results of the distance detection unit 40 and the illuminance detection unit 50. In other words, the stereoscopic display device 1 of this embodiment can control the state of the stereoscopic image according to the situation in which it is observed.

[0061] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the invention. Furthermore, the above embodiments may be combined as appropriate. [Explanation of Symbols]

[0062] 1...3D display device, 2...Drawing space, 10...Light source unit, 20...Emission unit, 21...Fluorescent material, 22...3D image, 23...Light collection position, 30...Storage unit, 40...Distance detection unit, 50...Illuminance detection unit, 60...Control unit, 110...Laser light source, 120...Conversion unit, 220...Modulation unit, 230...Convergence unit, 240...Scanning unit, 610...Distance correction information acquisition unit, 620...Intensity control unit, 630...Illuminance correction information acquisition unit, 640...Phase control unit

Claims

1. A laser light source that emits laser light, A conversion unit that converts emitted laser light into collimated light of a predetermined diameter, A scanning unit scans the focusing position of the laser beam in three dimensions by changing the focal length at which the collimating light converges and the optical axis direction from which the collimating light is emitted, using a drawing space containing a fluorescent substance that is excited and self-luminesced by irradiation with laser light as the scanning target area. An observer observing the drawing space, and a distance detection unit that detects the distance between the observer and the drawing space, A distance correction information acquisition unit acquires distance correction information from a storage unit that stores the correspondence between the distance and the intensity of the laser light as distance correction information. An intensity control unit controls the intensity of the laser beam scanned by the scanning unit at the focusing position based on drawing data indicating the emission intensity for each position in the drawing space and distance correction information corresponding to the detected distance. A stereoscopic display device equipped with the following features.

2. The intensity control unit controls the intensity by setting the number of light emission positions along the optical axis of the fluorescent material to at least three different numbers. The stereoscopic display device according to claim 1.

3. An illuminance detection unit for detecting the illuminance of the surrounding environment in the drawing space, An illuminance correction information acquisition unit acquires the illuminance correction information from a storage unit that stores the correspondence between the illuminance and the intensity of the laser light as illuminance correction information. Furthermore, The intensity control unit further controls the intensity of the laser light based on the illuminance correction information corresponding to the detected illuminance. The stereoscopic display device according to claim 1.

4. The fluorescent material has a first region in which the intensity of self-luminescence changes in response to a change in the intensity of the irradiated laser light, and a second region in which the intensity of self-luminescence changes more slowly than the change in the intensity of self-luminescence in the first region. The intensity control unit causes the fluorescent material located at a position away from the focal point in the optical axis direction to emit light by adjusting the intensity of the laser light at the focal point to an intensity that causes the fluorescent material at the focal point to become part of the second region. A stereoscopic display device according to any one of claims 1 to 3.

5. A modulation unit that changes the spatial frequency distribution of the laser light to give a periodic distribution to the intensity of the laser light along the optical axis from the focusing position. Furthermore, The intensity control unit controls the number of emission positions along the optical axis where the fluorescent substance emits light, which are generated by the periodic distribution provided by the modulation unit, to be at least three different numbers. A stereoscopic display device according to any one of claims 1 to 3.

6. Emitting laser light, Converting emitted laser light into collimated light of a predetermined diameter, The scanning range is defined as a drawing space containing a fluorescent substance that is excited and self-luminesces when irradiated with laser light. The focusing position of the laser light is scanned in three dimensions by changing the focal length at which the collimating light converges and the optical axis direction from which the collimating light is emitted. The distance between the observer observing the drawing space and the drawing space is detected. The distance correction information is obtained from a storage unit that stores the correspondence between the distance and the intensity of the laser light as distance correction information. Based on drawing data indicating the emission intensity for each position in the drawing space and distance correction information corresponding to the detected distance, the intensity of the laser light at the focusing position is controlled. A method for displaying three-dimensional objects.

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