JP2020181188A - Display device, control method of display device, control program, and storage medium - Google Patents

Abstract

To provide a display device capable of appropriately protecting observers when displaying using a laser beam with a large output that causes a plasma to be generated in gas while suppressing the frequency of display stoppages to protect the observers.SOLUTION: The display device includes: a laser irradiation device that irradiates a display position in a gas with a laser beam in a predetermined wavelength range to form plasma at the display position; an object detection device that detects the presence or absence of an object in a predetermined space; and a control unit that determines a prescribed space based on the display position and the intensity of laser light scattered at the display position or passed through the display position.SELECTED DRAWING: Figure 7

Description

The present invention relates to a display device, a control method for the display device, a control program thereof, and the like.

Conventionally, a technique has been proposed in which a laser beam is focused on a display position in the air to display an image. For example, Patent Document 1 discloses a display method in which plasma is locally formed by irradiation with a laser beam and the plasma light is used. In this technology, by irradiating a laser beam with a wavelength in the invisible region, local dielectric breakdown occurs in the air, and the gas locally forms a high-density plasma state, causing a flash (plasma emission). And display the light emission. This type of display method for displaying an image in the air using a laser beam includes, for example, a 2D display that can be observed from various directions, a 2D display that can be observed as a planar image, or a 3D display that can be observed as a stereoscopic image. There is a possibility and it is expected to be put into practical use.

In general, when handling a laser beam, it is necessary to take measures to protect humans and objects in the surrounding environment. In particular, in the case of a display device that emits plasma by irradiating a laser beam, it is necessary to irradiate a relatively high-power laser beam. For example, a human body such as skin or retina, an object in the environment, its coating, or a film. It is required to be able to reliably protect such things.

In Patent Document 1, when a laser beam is focused on a target position in front of a vehicle body to display plasma emission, a pedestrian or another vehicle or the like is described at a target position (a position where the laser beam is focused and plasma is emitted). A configuration is disclosed in which the display is stopped when the object of the above is detected.

JP-A-2015-156080

According to the method of stopping the display when an object such as a pedestrian or another vehicle is detected at a target position (a position where a laser beam is focused and emitted by plasma) as in Patent Document 1, a pedestrian or a vehicle It is possible to prevent the laser beam from being directly focused on another vehicle.

However, in the example of Patent Document 1, although the direct focusing (irradiation) of the laser beam to the pedestrian can be prevented, the protection of the observer (in the case of Patent Document 1, the driver of the automobile) who visually recognizes the displayed image is protected. Is not considered. Further, in the method of Patent Document 1, depending on the surrounding conditions, the display may be stopped frequently, and the practicality for the observer (driver) may be impaired.

Therefore, there is a need for a method that can appropriately protect the observer and suppress the frequency of display stoppage to protect the observer when displaying using a laser beam having a large output so as to generate plasma in the gas. Was being done.

A first aspect of the present invention is a laser irradiation device that irradiates a display position in a gas with a laser beam in a predetermined wavelength range to form a plasma at the display position, and an object detection device that detects the presence or absence of an object in a predetermined space. The display device includes the display position and a control device that determines the predetermined space based on the intensity of the laser beam scattered at the display position or passed through the display position.

A second aspect of the present invention is a method of controlling a display device including a laser irradiation device that irradiates a display position in a gas with laser light in a predetermined wavelength range to form plasma at the display position, wherein the object detection device is used. An object detection step for detecting the presence or absence of an object in a predetermined space determined based on the display position and the intensity of laser light scattered at the display position or passing through the display position, and the control device detects the object. It is a control method of a display device including a control step of stopping or reducing the output of the laser irradiation device and changing the position or shape of the predetermined space when the device detects the object in the predetermined space.

According to the present invention, when displaying is performed using a laser beam having a large output so as to generate plasma in a gas, the observer can be appropriately protected, and the frequency of display stoppage performed for the protection of the observer is suppressed. can do.

It is explanatory drawing which showed the schematic structure of the display device which concerns on embodiment of this invention. It is explanatory drawing which showed each irradiation direction and position at the time of forming a light emitting body in the air by the predetermined wavelength laser of the display device which concerns on embodiment of this invention, and measuring the radiant energy density by a spectroscope. It is explanatory drawing which showed the structural example which performs moving image display or stereoscopic image display by the display device which concerns on embodiment of this invention. It is explanatory drawing which showed the structural example of the display device which concerns on embodiment of this invention in detail. It is a block diagram which showed the detailed configuration example of the control system of the display device which concerns on embodiment of this invention. It is a flowchart which showed the flow of the display control which concerns on embodiment of this invention. It is explanatory drawing which showed the shape of the space which restricts the entry of an observer and other things in the display device which concerns on embodiment of this invention. In the display device according to the embodiment of the present invention, it is a diagram showing a spectrum obtained by forming a light emitting body in the air with a laser having a wavelength of 532 nm and measuring the spectrum from a position of 45 ° from the irradiation direction for 200 ms with a spectroscope. In the display device according to the embodiment of the present invention, it is a diagram showing a spectrum obtained by forming a light emitting body in the air with a laser having a wavelength of 532 nm and measuring the spectrum from a position of 45 ° from the irradiation direction for 10000 ms with a spectroscope. It is a diagram which showed the spectrum which measured the plasma formed in the air by a laser with a spectroscope. It is explanatory drawing which showed the XY chromaticity diagram of CIE 1931. In the display device according to the embodiment of the present invention, the ratio of the observed color of the illuminant formed in the air by a laser having a wavelength of 532 nm and the Y value of plasma emission at that time / the Y value near the laser wavelength is shown for each laser output. It is a table diagram. In the display device according to the embodiment of the present invention, the details of the ratio of the visually observable color of the illuminant formed in the air by the green laser to the Y value of the plasma emission at that time / the Y value near the laser wavelength are measured at a measurement angle. It is a table diagram shown for each.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. The configuration shown below is merely an example. For example, a person skilled in the art can appropriately change the detailed configuration without departing from the spirit of the present invention. Moreover, the numerical values taken up in this embodiment are examples.

[Embodiment]
(Laser irradiation device)
The image display device (image forming device) of the present embodiment uses a laser in a predetermined wavelength region, particularly in a visible light region, and mainly makes the observer visually recognize the emission color. There are various theories about the wavelength range of the predetermined wavelength range and the visible light region, and it is considered that there are individual differences of the observer, but in the present embodiment, the wavelength range of 380 nm or more and 780 nm or less is considered as the visible light region for convenience. .. However, even in a predetermined wavelength range (visible light region) that differs from the example of the numerical values described later in the range of about 0 to several tens of nm, almost the same effect can be expected by carrying out the same configuration or control as in the example described later. Needless to say.

In the case of this embodiment, the color displayed in the air, that is, in the gas of the atmosphere (atmosphere) is the color in the visible light region of the laser to be used. In principle, full-color display pixels can be realized by forming laser emitters that emit red, green, and blue at the same or close positions in the air, and a large number of display pixels can be formed. Can express a three-dimensional stereoscopic image. The present embodiment deals with the configuration and control for realizing the display pixel by the monochromatic laser beam, which is the basis for realizing the full-color display pixel.

As the laser used for display, a high-power laser, that is, a short pulse laser is suitable. As short pulse lasers, solid-state lasers, fiber lasers, semiconductor lasers, gas lasers and the like are known. Of these, for example, solid-state lasers and fiber lasers with good laser stability are considered to be preferable.

(Color image mechanism)
Here, the mechanism of color image (illuminant) generation in the present embodiment will be described. 1 to 4 show a schematic configuration of a display device (image forming device) of the present embodiment. In FIG. 1, the laser light source 101 is a visible light laser light source as described later, and the laser beam 201 irradiated by the visible light laser light source is used to generate display pixels at the display position 301.

When the display pixels are generated, the observer visually recognizes the illuminant as if it appeared at the display position. However, as will be described later, most of the light that arrives from the display position and is visually recognized by the observer is not the light emitted at the display position but the laser light in the visible wavelength range scattered at the display position. That is, the laser light in the visible wavelength range output by the laser light source generates a weak plasma at the display position, and the laser light is scattered by the plasma and reaches the observer. Since the observer sees the illuminant as if it appeared, in this specification, a minute spatial region in which the laser beam in the visible wavelength region is strongly scattered at the display position is described as the illuminant. May be done. In the present specification, with respect to the color displayed at the display position, colors other than white may be referred to as colored (or color). Further, in a table or the like, for convenience, white plasma light or the like may be referred to as colorless, but this does not mean that it is transparent, but simply means that it is not the above-mentioned colored (or color). Not too much.

The laser irradiation device 100 shown in FIG. 1 includes a laser light source 101, a beam expander 102, a polarizing plate 103, a beam splitter 104, and a condenser lens 105 (condenser). The laser light source 101 of FIG. 1 oscillates a laser beam 201 in a visible light region, for example, a wavelength of 532 nm. When this laser beam is visually confirmed, it is visually recognized as approximately green. The laser beam 201 is incident on the optical path shown in FIG. This optical path includes, for example, a beam expander 102 for expanding the laser diameter, a polarizing plate 103, a beam splitter 104 (polarizing beam splitter), and a condenser lens 105. This optical path is adjusted to focus the laser beam 203 at a display position at a predetermined distance, for example, a display position 90 mm from the tip of the condenser lens 105. The beam expander 102 expands the diameter of the laser beam 201 by, for example, about 10 times to obtain the laser beam 202. However, another magnification may be used for the beam expander 102 for the purpose of changing the magnification depending on the focal length.

As shown in FIG. 1, the display device (image forming device) of the present embodiment is provided with the biosensor 107 as an object detection device. This object detection device (biological sensor 107) detects the presence or absence of an object (living body) in a specific space range, for example, inside the protected space 404 described later. The method of the biological sensor 107 is not particularly limited as long as it can detect the presence or invasion of a living body. For example, a sensor that uses capacitance distribution or infrared reflection, or an optical sensor that irradiates space with detection light (infrared light, etc.) in a matrix and detects the entry of an object (living body) by blocking it. Can be used.

In FIG. 1, the irradiation intensity of the laser beam of the laser light source 101 is controlled by the control unit 1011. The control unit 1011 can control the emission intensity of the laser light of the laser light source 101, for example, by controlling the driving power of the laser light source 101. Further, the control unit 1011 can control the irradiation intensity of the laser beam by changing the combination of the polarization direction of the polarizing plate 103 and the beam expander 102, as described in detail in the second embodiment. Further, other control means as shown by 1012 in FIG. 1 may be arranged. The control means 1012 can be configured by an element capable of changing the light transmittance, such as a liquid crystal shutter.

Here, FIG. 5 shows an example of a specific configuration of the control system constituting the control unit 1011. The control system of FIG. 5 can be configured by a CPU 1601 as a main control means, a ROM 1602 as a storage device, and PC hardware including a RAM 1603. The ROM 1602 can store a control program of the CPU 1601 and constant information for realizing the manufacturing procedure described later. Further, the RAM 1603 is used as a work area of the CPU 1601 when executing the control procedure. Further, an external storage device 1606 is connected to the control system of FIG. The external storage device 1606 is not necessarily necessary for the practice of the present invention, but can be configured from an HDD, an SSD, an external storage device of another network-mounted system, or the like.

The control program of the CPU 1601 for realizing the laser output control of the present embodiment can be stored in a storage unit such as the above-mentioned external storage device 1606 or ROM 1602 (for example, EEPROM area). In that case, the control program of the CPU 1601 for realizing the control procedure of the present embodiment is supplied to each of the above-mentioned storage units via the network interface 1607 (NIF), and is updated to a new (another) program. Can be done. Alternatively, the control program of the CPU 1601 for realizing the control procedure described later is supplied to each of the above storage units via storage means such as various magnetic disks, optical disks, and flash memories, and a drive device for that purpose. The contents can also be updated. Various storage means, storage units, or storage devices in a state in which the control program of the CPU 1601 for realizing the control procedure of the present embodiment is stored constitutes a computer-readable recording medium in which the control procedure of the present invention is stored. It will be.

The laser light source 101 of FIG. 1 is connected to the CPU 1601. In FIG. 5, for simplification, the laser light source 101 is shown to be directly connected to the CPU 1601, but may be connected via a well-known interface or the like. Further, the laser light source 101 may be configured to be connected via the network interface 1607 and the network 1608.

The network interface 1607 can be configured using, for example, a wired communication standard such as IEEE 802.3 or a wireless communication standard such as IEEE 802.11, 802.11. The CPU 1601 can communicate with other devices 1104 and 1121 via the network interface 1607. The devices 1104 and 1121 correspond to, for example, a control control device, a management server, and the like, and perform control and logging related to an effect using the display of the display device.

Further, the control device of FIG. 5 includes a UI device 1604 (user interface device). The UI device 1604 is composed of an operation unit and a display device. The operation unit can be configured by a terminal such as a handy terminal, or a device such as a keyboard, a jog dial, or a pointing device (or a control terminal provided with them). Further, as the display device, for example, in addition to the liquid crystal system, any display device can be used as long as it can display and output.

The display device of the UI device 1604 can monitor and display various data related to the driving conditions of the laser light source 101. Further, on the screen of the display device of the UI device 1604, an image corresponding to the stereoscopic image displayed in the air by the laser display device of the present embodiment can be displayed in 3D. In that case, the data related to the driving conditions of the laser light source 101 may be displayed together with the 3D display corresponding to the stereoscopic image displayed in the air.

In FIG. 5, the measuring instrument 1605 corresponds to a measuring system including the high-speed camera 6 of FIG. 4, the spectroscope 7 (108 of FIG. 2), the calorimeter 8, and the like. The measuring instrument 1605 can be used, for example, for the CPU 1601 to determine the laser irradiation intensity by closed loop control. The high-speed camera 6, the spectroscope 7, the calorimeter 8, and the like that constitute the measuring instrument 1605 will be described later.

In FIG. 2, the irradiation direction (optical axis direction) of the condenser lens 105 is set to 0 °, and measurement is performed by the spectroscope 108 at observation angles arranged clockwise in the figure of 30 °, 45 °, 90 °, and so on. Is shown. On the other hand, in FIG. 4, the laser light source 101, the beam expander 102, the polarizing plate 103, and the beam splitter 104 of FIG. 1 are indicated by reference numerals 1, 2, 3, and 4, respectively. Here, when the irradiation energy of the laser output is adjusted by using the polarizing plate 103 (3) and the beam splitter 104 (4), the emission color of the laser light source 101, for example, a green emitter (laser light) is displayed at the display position 301. It was confirmed that there is an observation area where the laser can be seen (the spatial area where the laser is strongly scattered).

In particular, when the green illuminant was measured with a spectroscope (for example, AvaSpec-ULS2048CL manufactured by Avantes) at a distance of 50 mm from the light source and a measurement angle of 45 ° in FIG. 2 at a laser output of 1500 mW for a time of 200 ms. A spectrum as shown in FIG. 8 was obtained. In the spectrum of FIG. 8, light near 532 nm, which is a light source, is detected more strongly than other wavelength ranges, and matches the green display color visually recognized by the observer in this display (observation) direction.

However, specific conditions are required to condense a green (532 nm) laser to form a green illuminant (a spatial region in which the laser light is strongly scattered) in the air. For example, when the spectroscopic measurement data of FIG. 8 is confirmed, it can be seen that light emission is also slightly contained in other visible light regions. Since this light is faint, spectroscopic measurements are performed for 10000 ms (10 seconds), and the graph of the results is shown in FIG. What can be seen in FIG. 9 is that light is generated in a relatively wide visible light region. On the other hand, FIG. 10 is a measurement of plasma emission having an intensity such that an impact sound is generated together with a flash as seen in Patent Document 1. Comparing FIGS. 9 and 10, the shapes of the waveforms are similar, and it is considered that weak plasma emission is generated in the measurement of the present embodiment shown in FIG.

That is, one of the conditions for forming a light emitter that can be visually recognized as colored (for example, green) in the air may be considered to be that the output is controlled by a visible light laser to generate a weak plasma region in the air. This weak plasma has a slightly different refractive index from gas (air in this embodiment), so that a light scattering field can be created, and a colored (green) laser is scattered in the scattering field, and the colored (green) is scattered. ) Is considered to be confirmed. According to the method of forming a light emitter using such weak plasma, in a normal office environment or the like, noise caused by plasma generation is hardly generated, and it is similar to a normal display device such as a liquid crystal display. It can be used for various purposes.

As a result of experimenting the condition of the combination of the emission intensity of plasma light and the emission intensity due to the scattering of visible light laser, the inventors can confirm the colored (green) illuminant, and the result as shown in FIG. 12 is obtained. Obtained. In this experiment, in the wavelength range of 380 nm or more and 780 nm or less, the Y value of the emission of only plasma light and the scattering of visible light laser excluding plasma light when the emission intensity for each wavelength of 1 nm is converted into the XYZ tristimulus value of CIE1931. The ratio of light Y values was evaluated.

According to the experiments of the inventors, the condition for the observer to visually recognize the colored (for example, green) illuminant is that the Y value of the light emitted only by the plasma light is the Y value of the scattered light of the visible light laser excluding the plasma light. It was necessary to control the laser irradiation conditions so as to be 1% or more and 95% or less of the above. For example, when the Y value of the emission of only the plasma light is smaller than 1%, the scattering field of the plasma is weak and the laser scattering is also weak, so that it is considered that it is difficult for the observer to see the colored scattered light. More preferably, it is 25% or more, and if it is 25% or more, the colored illuminant becomes easy to see. Further, when the Y value of the emission of only the plasma light exceeds 95%, it is assumed that the emission intensity of the plasma is too strong and the colored scattered light loses to the intensity of the white light of the plasma, and the colored light is mixed. However, it is considered that the observer recognizes it as white light. When calculating the Y value of the scattered light of the visible light laser (FIG. 8: in the case of green) excluding the plasma light, the Y value of the scattered light itself of the colored (green) laser is measured. Therefore, when a 532 nm laser is used, the output data of the spectroscope arranged as shown in FIG. 2 is 10 nm (in this case, 522 nm to 542 nm) before and after the laser wavelength, and the other output data is 0. And.

Since the Y value of the emission of only the plasma light is weak under the condition where the color is confirmed, the plasma light can be confirmed by integrating the measurement time as, for example, 10000 ms. However, in this measurement, since the colored laser becomes relatively strong, the base of the light intensity of the colored laser expands from 515 nm to the vicinity of 603 nm as shown in FIG. 9. However, when the XYZ value at this time is calculated, the laser beam is obtained. It will contain a lot. This is because the laser light is too strong for the plasma light, so that the laser light affects the wavelength region close to the laser wavelength. At this time, even if the light intensity of only 532 nm is removed, the light intensity of the foot portion is too strong, so that the Y value is different from that of the plasma light alone. Therefore, in order to calculate the Y value of only the plasma light, the waveform of the spectrum output by the spectroscope is confirmed, and the light intensity on the long wavelength side within the range of 10 nm (the number of counts in the apparatus of this embodiment) is doubled. Check the wavelength that becomes. In the experiment according to this embodiment, the count number at 515 nm was 1061 and the count number at 505 nm was 521.

Next, the waveform of the spectrum output by the spectroscope is confirmed, and the wavelength at which the light intensity on the longer wavelength side (count number in the apparatus of the present embodiment) is halved within the range of 10 nm is confirmed. In the experiment according to this embodiment, the count number at 603 nm was 1190 and the count number at 613 nm was 212. At this time, the wavelength of the laser was 532 nm, but the spread of the base by integration was as wide as 515 nm to 603 nm.

When this is removed and set to 0, it is calculated to be lower than the Y value of only the plasma light, so that the waveform of FIG. 9 has a shorter wavelength side of 505 nm so as to have a waveform curve of only the plasma light (for example, FIG. 10). On the long wavelength side, a straight line 501 connecting the vicinity of 613 nm is drawn. Then, using this straight line 501, a numerical value including a value for each 1 nm between the count values of 505 nm on the short wavelength side and 613 nm on the long wavelength side is obtained. In FIG. 9 of this embodiment, since the measurement was performed for 50 times as long as the measurement of the colored laser (FIG. 8), XYZ was calculated assuming that the count number of each wavelength was 1/50, and the measured value of the Y value of plasma emission was measured. To get.

Further, when the plasma emission is strong and the light intensity of the colored laser is buried in the plasma light, it is not necessary to extend the measurement time. Here, the XYZ value (tristimulus value) of CIE 1931 is the intensity of red, green, and blue colors experimentally calculated from the sensitivity of the human eye for the intensity of the wavelength of each light in the visible light region. It is an index used and shown, and in particular, the Y value is used as an index showing the brightness of a color.

In the present embodiment, the display state is evaluated by the XYZ tristimulus value instead of the light intensity at each wavelength because the state recognized as a color by the observer is important, and the XYZ tristimulus value is the XYZ tristimulus value. This is because it is the best means for humans to express color and light intensity.

Next, the direction dependence of the light arriving from the illuminant will be considered. In the present embodiment, the forward scattering direction is 0 ° to less than 30 ° and more than 330 ° to 0 (360) ° with respect to the optical axis direction of the condenser lens 105, as shown in FIG. 2 or FIG. The scattering angle in the range (402) up to. On the other hand, in the present embodiment, the suitable display angle range in which the laser light scattered at the display position 301 can be observed with high color purity is the range excluding the forward scattering direction (402), that is, the light of the condenser lens 105. The range is 30 ° or more and 330 ° or less with respect to the axial direction.

The broken line shown in FIG. 2 or the solid line shown in FIG. 7 indicates the shape of the outer edge of the protected space 404 according to the protection mode described later. The protection space 404 and the protection mode will be described in detail later with reference to FIGS. 6, 7 and the like.

The inventors have confirmed that when the plasma emission generated in the air in the emission experiment of the invisible region laser is observed from the above-mentioned forward scattering direction, the plasma emitter is green instead of white. The wavelength of this green is about 500 nm. This is considered to be the emission color when the atoms or molecules of nitrogen and oxygen in the air are turned into plasma. The reason why the color of the plasma light in the forward scattering direction is green is unknown, but from this experiment, it was found that the display direction (observation direction) is important for controlling the display color.

For example, when observing a light emitter by irradiation with a green laser from a forward scattering direction, it is considered that the light of 532 nm scattered by the laser light and the light of about 500 nm of plasma emission due to the composition of the gas are mixed. As a result, even if the same green color is used, the XY values of the light emitting pixels are different, and the light emitting color is different from that of the intended laser wavelength, which makes it difficult to express a desired color. Further, in a light emitter by irradiation with another colored laser (for example, red or blue), it is caused by the composition of gas in the forward scattering direction of 0 ° to less than 30 ° and 330 ° to 360 ° with respect to the laser irradiation direction. A mixture of plasma emission and scattered light at about 500 nm occurs. Therefore, the purity of the display color may decrease.

Therefore, in the present embodiment, the display direction is a range excluding the forward scattering direction of 0 ° to less than 30 ° and 330 ° to 0 (360) ° with respect to the laser irradiation direction. As a result, color mixing does not occur, and the user can observe the emission color of the colored laser itself of the display device as the display color.

That is, in the present embodiment, in FIG. 2, the display direction is preferably 30 ° or more and 330 ° or less. For that purpose, for example, in the arrangement of the optical axis as shown in FIG. 2, the audience (observer) who visually recognizes the display so that the illuminant can be observed only from the range of 30 ° or more and 135 ° or less and 225 ° or more and 330 ° or less. Group) is placed. Alternatively, in the optical axis arrangement as shown in FIG. 2, the viewing angle of the audience (observer group) who visually recognizes the display is limited to a range of 30 ° or more and 135 ° or less and 225 ° or more and 330 ° or less. Place shielding devices such as walls, shielding plates, and shielding plates.

By arranging such a shielding device, the emission color of the colored laser itself of the display device can be used as the display color without being affected by the color mixing with the emission of the atmosphere by the plasma.

(Spectroscopic measurement method of illuminant)
Using a spectroscope (for example, manufactured by Avantes Co., Ltd., trade name: AvaSpec-ULS2048CL) as a measuring device for the illuminant formed in the air as described above, the intensity of light of each wavelength is measured from each measurement angle in FIG. It was measured. Since wavelengths other than the wavelength of the laser beam have very low intensity, the measurement is performed every 1 nm. The numerical value of the light intensity of each wavelength output by the spectroscope is a count number, and although it is different from the brightness, it may be treated as the light intensity, for example, the light intensity equivalent to the spectral irradiance.

In this measurement, the laser irradiation direction (optical axis direction of the condenser lens 105) is 0 °, and 20 °, 30 °, 45 °, 90 °, 135 °, 225 °, 270 °, 315 °, 330 °, 340. Measured at each angle of °. Further, although FIG. 2 shows an angle in a plane including the optical axis, the angle at which measurement (observation is the same) is the same even if an arbitrary angle is selected with respect to the circumferential direction of the circumference around the optical axis, for example. Is. Of course, the angle in the circumferential direction in which the measurement (same for observation) around the optical axis is performed does not limit the present invention.

(Calculation of CIE XYZ tristimulus values and xy)
In the calculation method of the XYZ tristimulus value, the number of counts in the wavelength range of 380 nm or more and 780 nm or less measured spectroscopically was included in the CIE value to calculate XYZ. The calculation method is to integrate the data for each 1 nm using the color matching function of (CIE 1931 2-deg, XYZ CMFs).
Further, xy is calculated from XYZ, and the calculation formula is shown in the following formulas (1) and (2).

The x and y of the above equations (1) and (2) represent colors, and the color classification of the illuminant of the present embodiment was determined by the CIExy chromaticity diagram (FIG. 11). In the present embodiment, as a judgment based on the xy chromaticity diagram (FIG. 11), the white (achromatic color) is in the range of 0.24 to 0.40 for x and 0.24 to 0.41 for y. In addition, red is in the range of 0.50 to 0.74 and y is in the range of 0.25 to 0.35, green is in the range of 0 to 0.23 and y is in the range of 0.40 to 0.84, and blue is in the range of x. Was determined to be in the range of 0.16 to 0.30, and y was determined to be in the range of 0 to 0.30. The CIExy chromaticity diagram as shown in FIG. 11 originally represents color development in the coordinate system by color representation. However, in FIG. 11 of the present embodiment, as a convenience for using the black-and-white representation in the illustration, "W" and "W" are shown in order to show the approximate coordinate ranges occupied by the white (achromatic color), red, green, and blue colors, respectively. Letters such as "R", "G", and "B" are shown in the chromaticity diagram.

(Aerial image display)
When scanning a laser to form an image in the air, the laser irradiation device 100 as shown in FIG. 3 can be used. As the two mirror devices 106 shown in FIG. 3, for example, two digital galvano scanners (for example, Canon Inc., GM-1020) are used, and a motor driver (for example, Canon Inc., GC-211) or the like is used. Can be done. Basically, the diameter of the colored laser beam is expanded by the beam expander 102, and the light is focused by the condenser lens 105 having a focal length corresponding to a desired display position. As a result, a visible image, that is, a colored display pixel that is not white is formed at the display position 301.

Further, if the mirror device 106 for moving the focusing point to a desired position in the air is installed in the optical path, an image can be drawn in the air. A galvano mirror, a polygon mirror, or the like can be used for the mirror device 106. Further, when displaying a 2D / 3D image in the air, a zoom lens or a movable lens that changes the focal length can be used to select the distance of the display position. Note that a configuration other than that illustrated above may be used to control these display positions.

If the biological sensor 107 shown in FIG. 1 has sensitivity directivity, the display position is scanned in a three-dimensional space by following the change in the irradiation optical axis by the scanning device. A tracking device for changing the detection direction of the biological sensor 107 (object detection device) is provided.

(Spectroscopic irradiance)
The spectroscopic curve was measured by arranging the spectroscope 7 (108) at an angle of 45 ° from the optical axis direction of the condenser lens 105 while changing the laser output using the green laser light source (L1). Further, the spectroscopic irradiance was measured by the spectroscope 7 (108) from each observation angle shown in FIG.

At this time, the laser beam is irradiated, and the energy of the condensing unit is changed by the polarizing plate and the beam splitter, and the Y value of each of the light emitters at this time of 522 nm to 542 nm is compared with the Y value of the plasma, and the condensing unit Adjusted the energy of. The measurement position of the light emitter was 45 ° from the optical axis direction of the condenser lens 105, and the distance from the light emitter was 50 mm. In this case, the laser output was 1500 mW. Under this condition, a green illuminant could be confirmed in the observation direction in the range of 30 ° to 330 °.

Further, FIG. 13 shows the result of calculating the xy value of this illuminant from XYZ (this XYZ includes laser scattered light and plasma emission). As shown in FIG. 13, in this example, all the light emission in the green range (green is 0 to 0.23 for x and 0.40 to 0.84 for y) can be visually recognized. In this way, by selecting the ratio of the Y value of the plasma light of the illuminant to the Y value near the laser wavelength, the observer can visually recognize the illuminant having the emission color of the laser (for example, green) instead of white. Can be done.

Further, in the observation direction at an angle of 20 ° (far left in FIG. 13), although it was green, light of about 500 nm was observed in addition to the main wavelength of 532 nm of the laser. A color that is a mixture of two colors is observed instead of pure green, and its xy value also moves slightly to the blue side. If the colors are mixed in this way, it becomes difficult to adjust the colors when displaying a full-color image using red, green, and blue. Therefore, in the present embodiment, the irradiation direction (condensing lens 105: When (optical axis direction) is set to 0 °, the observation angle within the range of ± 30 ° should not be used. Further, assuming that the irradiation direction is 0 °, the range of ± 30 ° is a range substantially in front of the laser irradiation direction, and the observation angle in this range is limited from the viewpoint of protecting the observer, particularly the retina. For that purpose, as described above, a shielding wall or a shielding plate that limits the field of view of the audience (observer group) who visually recognizes the display to a range of 30 ° or more and 135 ° or less and 225 ° or more and 330 ° or less. Place a shielding device such as a shading plate.

In the range of 30 ° or more and 135 ° or less and 225 ° or more and 330 ° or less from the optical axis direction of the condenser lens 105, the Y value of the emission of only the plasma light is the scattered light of the visible light laser excluding the plasma light. Even if it exceeds 95% of the Y value, the observed color does not become white. This is because the phenomenon described above occurs and the white color of the plasma light does not occur. Further, when the green display pixels were formed under the irradiation conditions of FIG. 13, almost no noise was generated. For example, the sound pressure level measured at a distance of 1 m from the light emitting point by a precision sound level meter (for example, TYPE6224 manufactured by Accor Co., Ltd.) was 40 dB or less. In addition, it was possible to scan the laser with a galvano mirror with the device of FIG. 3 and draw an image in the air using the green display pixels.

Further, in the range of 30 ° or more and 135 ° or less and 225 ° or more and 330 ° or less from the optical axis direction of the condenser lens 105, the scattered light is emitted by the spectroscope 108 from a distance of 100 mm from the illuminant at the following angles. The radiant energy density was measured. The measurement results were as follows.
-200 μW / cm ² / nm or less at 45 ° (= 315 °) and a distance of 100 mm.
100 μW / cm ² / nm or less at 90 ° (= 270 °) and a distance of 100 mm.
80 μW / cm ² / nm or less at 135 ° (= 225 °) and a distance of 100 mm.

The spectroscope 108 used at this time is a fiber probe type high-speed spectroscope that measures the irradiance of each wavelength of the illuminant, and is, for example, AvaSpec-ULS2048CL manufactured by Avantes.

Here, for reference, a green laser pointer (JIS C6802 class 2) was used to measure from a distance of 100 mm using the same spectroscope 108 at an irradiation direction of 0 ° (= directly viewed from the laser propagation direction). In that case, the spectral irradiance (radiant energy density) was 400 KμW / cm ² / nm. From this, the radiant energy density of the scattered light at an observation angle of 45 ° (= 315 °) from the optical axis direction of the condenser lens 105 at a distance of 100 mm from the illuminant is the case where the green laser pointer (class 2) is directly viewed. It turns out that it is 1/20000 of the radiant energy density. Further, the radiant energy density of the scattered light at an observation angle of 135 ° (= 225 °) from the optical axis direction of the condenser lens 105 and a distance of 100 mm from the illuminant is the radiation when the green laser pointer (class 2) is directly viewed. It turns out that it is 1 / 40,000 of the energy density.

(Protected space)
As described above, in the case of a light emitter formed by irradiation with a laser output of 1500 mW, the light emitter is within an observation angle range of 45 ° (= 315 °) to 135 ° (= 225 °) from the optical axis direction of the condenser lens. When the distance from the distance was 100 mm, the irradiance of the scattered light was relatively small. From this, if the observer observes the display position (light emitting body) from the side with respect to the irradiation direction of the laser light (the traveling direction of the laser light from the light source to the light emitting body), the observer's safety It can be understood that it may be possible to suppress the interruption of the display made for.

However, if the intensity of the laser beam is modulated according to the brightness information of the image signal, for example, a space (range) in which the laser beam scattered by the illuminant reaches with excessive intensity may be generated around the illuminant. Moreover, the size of the space can be changed by modulating the laser beam intensity. From the viewpoint of protecting the observer, it is not sufficient to control the intermittent display by detecting only the presence or absence of a person at the display position (plasma generation position) where the laser beam is focused, as in Patent Document 1. is there. That is, not only the display position (plasma generation position) for focusing the laser light, but also the presence of a person in a space where the laser light scattered at the display position and the laser light passing through the display position can reach with high intensity. It is desirable to control the display by detecting the entry of a person into the space.

For example, a space in which the intensity of scattered light scattered in various directions from the illuminant at the display position is equal to or higher than a predetermined irradiance (radiation energy density) is defined as a protected space (predetermined space), and an object entering the protected space. It is desirable to detect (living body).

Then, when the entry or presence of an object into the protected space is detected, the protection mode for stopping the irradiation of the laser beam of the laser irradiation device 100 or reducing the laser output of the laser irradiation device 100 is executed.

Here, the above-mentioned measurement result, that is, an angle range of 45 ° (= 315 °) to 135 ° (= 225 °) from the optical axis direction of the condenser lens (the traveling direction of the laser beam from the light source to the illuminant). In, the measurement result of the irradiance at a distance of 100 mm from the illuminant is evaluated again. Based on the irradiation direction of the laser beam (the direction in which the laser beam travels toward the illuminant), the irradiance is relatively large on the front side of the illuminant, and the irradiance on the side and rear sides is higher than that on the front side. Was small. That is, the irradiance of the scattered light is 45 ° (= 315 °) with respect to the irradiation direction of the laser light (the traveling direction of the laser light from the light source to the light emitting body) with reference to the position of the light emitting body. Is relatively large, 200 μW / cm ² / nm. On the other hand, in the direction of 90 ° (= 270 °) with respect to the irradiation direction of the laser light (the traveling direction of the laser light from the light source to the illuminant), the irradiance of the scattered light is 100 μW / cm ² /. It was as small as nm. Further, in the direction of 135 ° (= 225 °) with respect to the irradiation direction of the laser light (the traveling direction of the laser light from the light source to the illuminant), the irradiance is higher than the direction of 90 ° (= 270 °). It is even smaller, 80 μW / cm ² / nm.

Here, it is considered that the position where the irradiance of the scattered light is the same, that is, the distance from the illuminant differs depending on the observation angle. For example, when the observation angle is 135 ° (= 225 °) and the distance from the illuminant is 100 mm, the irradiance is 80 μW / cm ² / nm, but the observation angle is 90 ° (= 270 °). The distance from the illuminant at the same irradiance position is larger than 100 mm. Further, it is considered that when the observation angle is 45 ° (= 315 °), the distance from the illuminant at the position where the same irradiance is obtained is further larger than when the observation angle is 90 ° (= 270 °).

Similarly, a range in which the irradiance of scattered light is equal to or higher than a predetermined value is obtained for each observation angle, and the space in which they are aggregated is defined as a protected space. That is, when the irradiance that should not be exceeded in order to ensure the safety of the human body is set as a predetermined value and a person enters or exists in the protected space within the range where the irradiance exceeds the predetermined value, the protection mode is used. To execute.

The outer edge of the protective space 404 is shown by a solid line in FIG. 7. The shape of the protective space 404 is the shape of a rotating body centered on the irradiation light axis of the laser beam, and the light emitting body (display position 301) is formed along the irradiation light axis. ), The diameter of the protective space 404 increases as it moves away from the front side. In FIG. 7, the protected space 404 shows a shape of a tip having a relatively small diameter on the rear side of the display position 301 and a relatively large diameter on the front side, but this is only an example. The shape, size, and position of the protected space 404 can be changed depending on the irradiation conditions such as the intensity of the laser beam, the irradiation position, and the focusing condition. For example, the CPU 1601 calculates it according to the irradiation condition of the laser light. You may.

To determine the protected space 404, for example, for various irradiation conditions, the irradiance in each direction of the observation angle is actually measured based on the actual measurement performed in advance, and a function obtained by interpolation processing from the plot of the irradiance, or Get the table data. Based on this function or table data, the CPU 1601 can calculate the shape and size of the space having a predetermined irradiance (radiant energy density). In that case, the CPU 1601 calculates the shape and size of the protected space according to at least one of the laser pulse width of the laser irradiation device 100, the repetition frequency of the laser pulse, the beam diameter of the laser light, the focal length, and the like. .. Further, when the shape of the protected space is changed, the irradiation condition of the laser beam can be changed based on the changed shape of the protected space. For example, the mirror device 106 can change the direction of the irradiation optical axis of the laser beam to change the display position 301 based on the changed shape of the protected space. When the shape of the space is changed, the control device determines the size of the image drawn (generated) in the air based on the changed shape of the space. Then, by changing the scanning distance of the laser beam, the mirror device 106 can display an image at the display position 301 with the determined size.

The predetermined irradiance (minimum value of the illuminance in the protected space) that defines the outer edge of the protected space is, for example, 80 μW / cm ² / of 135 ° (= 225 °) on the rear side of the above optical axis. It is conceivable to adopt irradiance of nm. However, for the predetermined or constant irradiance value that defines the outer edge of the protected space, a value in an arbitrary range such as several tens of μW / cm ² to several 100 mW / cm ² is adopted by those skilled in the art depending on the product specifications and the like. Good.

Further, it is conceivable to display an illuminant of an arbitrary display color at or near the display position by additive mixing of the three primary colors R, G, and B. In that case, for example, the laser output of the laser irradiation device 100 of each color of R, G, and B may be different depending on the desired display conditions. As a result, the shape and size of the protected space may be different from each other for each color of R, G, and B. In that case, the protected space calculated for each color of R, G, and B may be combined, and the outermost outer edge thereof may be the shape of the entire protected space related to the three-color composite display of R, G, and B. Conceivable.

For example, the intensity of scattered light for each color of laser light is added, and the protected space is a space range where the added scattered light intensity is equal to or greater than the irradiance (predetermined value) that should not be exceeded in order to ensure the safety of the human body. May be.

In FIG. 7, the conical space 4041 through which the collimated laser light 403 passes from the condenser lens 105 toward the display position 301 may also be included as a part of the protective space. Further, as described above, it is preferable to limit the observation field of view by a shielding device or the like within a narrow angle range of 60 ° of 330 ° to 0 ° to 30 ° centered on the irradiation optical axis. However, this cloaking device may be omitted when controlling the protection mode based on the following object (living body) detection.

In the display device of the present embodiment, the protection mode is realized by the following control.
(Detection process)
Detects the entry of an object into the space where the intensity of the laser beam emitted from the laser irradiation device 100 and the laser beam scattered at the display position or passed through the display position becomes a predetermined value or more. For example, the biological sensor 107 is used to detect the entry of a living body into the protected space and the presence of the living body in the protected space.
(Protection control process)
When the entry of an object into the space is detected, the laser irradiation of the laser irradiation device 100 is stopped, or the laser output of the laser irradiation device 100 is reduced. When a living body enters the protected space or the presence of a living body in the protected space is detected, the mode shifts to the protection mode, and the shape and position of the protection space can be changed by changing the irradiation conditions of the laser beam. To do. At that time, the irradiation conditions of the laser beam are changed so that the living body does not exist in the changed protected space. Changes in the irradiation conditions of the laser beam performed in the protection mode can include stopping the irradiation of the laser beam, reducing the irradiation intensity, changing the irradiation (condensing) position, and changing the size and shape of the displayed image.

Irradiation of the laser beam may be stopped immediately after shifting to the protection mode, but it will be described later while reducing the irradiation intensity, changing the irradiation (condensing) position, changing the size and shape of the displayed image, and the like. It is also possible to repeat step S14 and step S16. According to this method, since the frequency of stopping the display in order to protect the living body (observer) can be suppressed, it is possible to achieve both the protection of the observer and the practicality of the display.

FIG. 6 is a flowchart showing an example of the display control procedure according to the present embodiment including the protection mode. Step S12 shown in FIG. 6 shows a display process of irradiating the laser beam from the laser irradiation device 100 toward the display position. This display process (S12) may include a laser scanning process by a scanning device as shown in FIG. Further, while the display process (S12) is in progress, the object detection step of step S10 is repeatedly performed.

The object detection step (S10) is executed by, for example, a biosensor 107 (FIG. 1) provided as an object detection device. The biological sensor 107 determines, for example, whether or not an object, in this case, a living body has entered the range of the protected space 404 of FIG. When the biological sensor 107 detects that a living body has entered the range of the protected space 404 (S10: YES), a transition from step S10 to step S14 occurs, and the protection mode is executed.

In this protection mode (protection control step), for example, the irradiation of the laser light of the laser irradiation device 100 is stopped, or the laser output of the laser irradiation device 100 is reduced. The shape of the protected space is changed according to the changed irradiation conditions of the laser beam, and the object detection step by the biosensor 107 is executed in step S16 for the changed protected space.

Then, in the object detection step (S16), when the living body is still detected inside the range of the protected space, the protection mode (S14) and the object detection step (S16) are repeatedly executed. When the biological detection is turned off in the object detection step (S16) (S16: YES), the process transitions from step S16 to S12 and returns to the display process.

When an object (living body) enters the range of the protected space 404 by the protection mode control as described above, the laser irradiation of the laser irradiation device 100 is stopped, the laser output of the laser irradiation device 100 is reduced, and the like. Can be processed. As a result, damage to an object in the display environment can be prevented, and the skin and retina of a living body such as an observer can be reliably protected. As described above, the protected space 404 is calculated as having a shape such that the irradiance (light intensity) related to the irradiation or scattering of the laser beam is a predetermined value on the outer edge surface thereof, and the irradiance is larger than that inside the protected space 404. Will be done. Therefore, it is possible to reliably protect an object or a living body from irradiation with a light intensity of a certain level or higher or exposure to scattered laser light.

[Other Embodiments]
The present invention is not limited to the embodiments described above, and many modifications and combinations are possible within the technical idea of the present invention.

The display control using the protection mode related to the protected space can be applied regardless of the laser display method as long as it is a display device that irradiates the display position with a laser. As a laser display method capable of implementing the configuration and control of the present embodiment, for example, a method of generating plasma by using a laser in an invisible wavelength region and displaying a visible image with the plasma light can be considered. Further, the configuration and control of the present embodiment can be carried out even by a method in which the fluctuation of the gas generated by the laser in the invisible wavelength region is colored by the laser of visible light. Further, the configuration and control of the present embodiment can also be applied to other methods in which plasma light is generated by high-power laser light and used for display. In both the above-described embodiment and these display methods, the laser light is scattered at the display position and irradiates in various directions. Therefore, the control of the protection mode using the protection space of the present embodiment is the same. Can be carried out.

The display device according to the present invention can be installed in various facilities such as a conference room, a theater, and a classroom.
Further, the display device according to the present invention can be mounted on a moving body such as a drone to display an image in the air.

Further, if the display device according to the present invention is mounted on a vehicle such as an automobile, for example, an image for supporting driving is displayed to the driver, or information such as a warning is displayed to a pedestrian who is an observer of the image. An image can be displayed in the surrounding space of the vehicle for the purpose of driving.

Further, the display device according to the present invention can also be mounted on an image forming device as a multifunction device having multiple functions such as a copy, a printer, a scanner, and a fax machine. When mounted on an image forming device, the operation screen and job list image are displayed in the air, the print image is displayed in the air, and the print image displayed in the air is processed to create new print data. It is also possible.

The present invention is also realized by supplying a program that realizes one or more of the above-mentioned functions to a system or a device via a network or a storage medium, and reading and executing the program by one or more processors in the computer of the system or the device. It is possible. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

100 ... laser irradiation device, 101 ... laser light source, 2, 102 ... beam expander, 103 ... polarizing plate, 7, 108 ... spectroscope, 104 ... beam splitter, 5, 105 ... condenser lens, 106 ... mirror device, 107 ... Biosensor, 201, 202, 203 ... Laser beam, 1601 ... CPU, 1602 ... ROM, 1603 ... RAM, 1604 ... UI device, 1605 ... Measuring instrument.

Claims (16)

A laser irradiation device that irradiates a display position in a gas with laser light in a predetermined wavelength range and forms plasma at the display position.
An object detection device that detects the presence or absence of an object in a predetermined space,
A display device including the display position and a control device that determines the predetermined space based on the intensity of laser light scattered at the display position or passed through the display position. In the display device according to claim 1, when the object detection device detects the object in the predetermined space, the control device stops or reduces the output of the laser irradiation device, and the position or shape of the predetermined space. Display device to change. In the display device according to claim 1 or 2, the control device determines the position or shape of the predetermined space, the laser output of the laser irradiation device, the laser pulse width, the repetition frequency of the laser pulse, the beam diameter of the laser beam, and the like. A display device that determines according to at least one of the focal distances. The display device according to any one of claims 1 to 3, wherein the shape of the predetermined space is a rotating body whose central axis is the irradiation light axis of the laser beam. In the display device according to any one of claims 1 to 4, the irradiation intensity of the laser light irradiated by the control device so that the light intensity at the outer edge of the predetermined space becomes a predetermined value. A display device that controls. The display device according to claim 5 includes a measuring device for measuring the energy density of the laser light emitted by the laser irradiating device at the display position, and the control device is based on the energy density measured by the measuring device. , A display device that controls the irradiation intensity of the laser beam. The display device according to any one of claims 1 to 6, wherein the object is a living body and the object detecting device is a living body sensor. The display device according to any one of claims 1 to 7, wherein the laser irradiation device includes a scanning device that changes the direction of the irradiation optical axis of the laser beam to change the display position. The display device according to claim 8, further comprising a tracking device that changes the detection direction of the object detection device in accordance with a change in the irradiation optical axis by the scanning device. In the display device according to claim 8 or 9, when the shape of the predetermined space is changed, the control device determines the size of the image to be generated based on the changed shape of the predetermined space. apparatus. In the display device according to any one of claims 1 to 10, the control device converts the light intensity at the display position into an XYZ tristimulus value of CIE1931 for each wavelength 1 nm in a wavelength range including the predetermined wavelength range. In this case, the laser light of the laser irradiation device with respect to the display position so that the Y value of the plasma light emitted by the plasma is in the range of 1% or more and 95% or less of the Y value of the scattered light of the laser light. A display device that controls the irradiation intensity. In the display device according to any one of claims 1 to 11, the laser irradiation device includes a visible light laser light source, a beam expander that expands the beam diameter of the laser light output by the visible light laser light source, and the like. A display device including a light collecting device for condensing laser light whose beam diameter has been expanded by the beam expander at the display position. In the display device according to any one of claims 1 to 12, the direction in which the observer visually recognizes the display is an angle of 30 ° or more and 330 ° or less with respect to the irradiation direction of the laser beam of the laser irradiation device. A display device with a shielding device that limits the range. In a control method of a display device provided with a laser irradiation device that irradiates a display position in a gas with a laser beam in a predetermined wavelength range and forms plasma at the display position.
An object detection step in which an object detection device detects the presence or absence of an object in a predetermined space determined based on the display position and the intensity of laser light scattered at the display position or passed through the display position.
When the control device detects the object in the predetermined space, the control device stops or reduces the output of the laser irradiation device and changes the position or shape of the predetermined space.
How to control the display device, including. A control program for causing a computer constituting the control device to execute each step of the display device control method according to claim 14. A computer-readable recording medium containing the control program according to claim 15.

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