Optical hologram module, projection device and control device for floating projection

Abstract

Optical hologram module for a projection device for floating projection (1000, 1000'), comprising a first prism array (10) comprising a plurality of first prisms (11, 11a, 11b), each of which has a first surface (111), wherein two first prisms (11, 11a, 11b) are stacked such that their first surfaces (111) form a first optical interface (12); and a second prism array (20) comprising a plurality of second prisms (21, 21a, 21b), each of which has a second surface (212), wherein two second prisms (21, 21a, 21b) are stacked such that their second surfaces (212) form a second optical interface (12), wherein a light enters the first prism array (10) and strikes the first optical interface (12) at a first angle of incidence, wherein total reflection occurs at the first optical interface (12) at the first surface (111) of one of the prisms (11, 11a, 11b), thereby generating a first reflected light (L21); wherein another light enters the first prism array (10) and strikes the first optical interface (12) at a second angle of incidence, wherein total reflection occurs at the first optical interface (12) at the first surface (111) of another prism (11b), thereby generating a second reflected light (L12); and wherein the second reflection light (L12) enters the second prism array (20) and strikes the second optical interface (22) at a third angle of incidence, wherein total reflection occurs at the second optical interface (22) at the second surface (212) of one of the prisms (21a), thereby producing a third reflection light (L13); wherein the second prism array (20) is arranged stacked on the first prism array (10), wherein a third surface (113) of one of the prisms (11b) is arranged facing a fourth surface (214) of one of the prisms (21a) to form a third optical interface (30), and wherein the second reflection light (L12) passes through the third optical interface (30) and then enters the second prism array (20); characterized by that each of the second prisms (21, 21a, 21b) further comprises a sixth surface (216), wherein the second prisms (21, 21a, 21b) are designed as triangular prisms, and wherein the second surface (212), the fourth surface (214) and the sixth surface (216) are connected to each other in pairs, and wherein the included angle between the fourth surface (214) and the sixth surface (216) is 90 degrees, and wherein the included angle between the second surface (212) and the fourth surface (214) is 60 to 65 degrees and the included angle between the second surface (212) and the sixth surface (216) is 25 to 30 degrees; or the included angle between the second surface (212) and the fourth surface (214) is 25 to 30 degrees and the included angle between the second surface (212) and the sixth surface (216) is 60 to 65 degrees.

Description

[0001] The invention relates to the technical field of an optical projection device, particularly to an optical hologram module composed of a hologram and used to bend the optical path; a floating projection device using the optical hologram module, which allows the viewer to visually generate floating images; and a floating projection operating device that forms an operation interface using the floating projection device.

[0002] Floating projection involves reflecting the image light generated by the display, changing the optical path of the light direction. When the light enters the viewer's eyes, the viewer creates a floating visual image. Due to the use of holographic imaging technology, floating projection can increase the realism of images, thereby enhancing the sense of interaction with observers or users. Therefore, floating projection devices have recently been widely used in various performances.

[0003] The existing floating projection device uses a holographic optical element (HOE) to reflect light, which then enters the user's eyes to create a floating image. The existing holographic optical element undergoes a surface coating process, forming a mirror surface that reflects light. Therefore, the existing holographic optical elements require the use of coating processes and materials, which increases the manufacturing cost of the holographic optical elements and also increases the manufacturing steps for the holographic optical elements.

[0004] Document US 2023 / 0093229 A1 discloses a reflective structure and a method for visibility control and shows the features of a hologram module according to the preamble of claim 1.

[0005] The invention is based on the object of creating an optical hologram module, a projection device for floating projection and an operating device for floating projection.

[0006] This object is achieved according to the invention by an optical hologram module having the features specified in claim 1; a projection device for floating projection having the features specified in claim 7; and an operating device for floating projection having the features specified in claim 12. Further advantageous developments of the invention emerge from the features of the subclaims.

[0007] According to the invention, prisms are used for the optical hologram module, which serve as a component for light reflection. After entering the prism, the light enters the state of transition from a dense medium (prism) to a less dense medium (air) and strikes the interface at an angle of incidence greater than the critical angle, resulting in a phenomenon of total internal reflection. As a result, the reflected light is reflected into the user's eye at a suitable angle, creating a floating image.

[0008] According to the invention, an optical hologram module is provided, comprising: a first prism array comprising a plurality of first prisms, each of which has a first surface, two first prisms being stacked such that their first surfaces form a first optical interface; and a second prism array comprising a plurality of second prisms, each of which has a second surface, wherein two second prisms are stacked such that their second surfaces form a second optical interface, wherein one of the lights enters the first prism array and strikes the first optical interface at a first angle of incidence, wherein total internal reflection occurs at the first optical interface at the first surface of one of the prisms, thereby producing a first reflected light; wherein another light enters the first prism array and strikes the first optical interface at a second angle of incidence, wherein total internal reflection occurs at the first optical interface at the first surface of another prism, thereby producing a second reflected light; and wherein the second reflection light enters the second prism array and strikes the second optical interface at a third angle of incidence, wherein total reflection occurs at the second optical interface at the second surface of one of the prisms, thereby generating a third reflection light (L13).

[0009] According to one embodiment of the invention, the first angle of incidence may be greater than or equal to 45 degrees.

[0010] According to one embodiment of the invention, the second angle of incidence may be greater than or equal to 45 degrees.

[0011] According to an embodiment of the invention, the angle between the third reflected light and the horizontal line may be greater than or equal to 45 degrees and less than or equal to 60 degrees.

[0012] According to the invention, the second prism array is stacked on the first prism array, wherein a third surface of one of the prisms is arranged facing a fourth surface of one of the prisms to form a third optical interface, and wherein the second reflection light passes through the third optical interface and then enters the second prism array.

[0013] According to an embodiment of the invention, each of the first prisms may further comprise a fifth surface, wherein the first prisms are designed as a triangular prism, and wherein the first surface, the third surface and the fifth surface are connected to one another in pairs, and wherein the included angle between the third surface and the fifth surface is 90 degrees, and wherein the included angle between the first surface and the third surface is 45 degrees, and wherein the included angle between the first surface and the fifth surface is also 45 degrees.

[0014] According to the invention, each of the second prisms further comprises a sixth surface, wherein the second prisms are designed as a triangular prism, and wherein the second surface, the fourth surface and the sixth surface are connected to each other in pairs, and wherein the included angle between the fourth surface and the sixth surface is 90 degrees, and wherein the included angle between the second surface (212) and the fourth surface is 60 to 65 degrees, and wherein the included angle between the second surface and the sixth surface is also 25 to 30 degrees.

[0015] Or each of the second prisms further comprises a sixth surface, wherein the second prisms are designed as a triangular prism, and wherein the second surface, the fourth surface and the sixth surface are connected to one another in pairs, and wherein the included angle between the fourth surface and the sixth surface is 90 degrees, and wherein the included angle between the second surface and the fourth surface is 25 to 30 degrees, and wherein the included angle between the second surface and the sixth surface is also 60 to 65 degrees.

[0016] According to the invention, a projection device for floating projection comprises a display module and an optical hologram module. The display module emits a plurality of lights that form an image. The optical hologram module bends the optical path of the lights and moves them along a visual generation direction, creating a floating image when viewed by an observer.

[0017] According to the invention, the projection device is further provided with an image magnification module through which the light passes and then enters the optical hologram module after being magnified.

[0018] According to one embodiment of the invention, the image magnification module (300) may comprise a Fresnel lens, wherein the lights pass through the Fresnel lens.

[0019] According to an embodiment of the invention, the projection device may be further provided with an optical path adjustment module, wherein the lights pass through the image magnification module and the optical path adjustment module one after the other, so that the lights are concentrated toward the optical hologram module and then enter the optical hologram module.

[0020] According to one embodiment of the invention, the optical path adaptation module may be provided with a plurality of optical microstructures arranged two-dimensionally.

[0021] According to one embodiment of the invention, the optical microstructure may be designed as a convex lens, wherein the sizes of the convex lenses are equal or unequal.

[0022] According to the invention, the floating projection control device may comprise: a projection device for floating projection; a signal transmitter that continuously emits a detection signal, wherein the detection signal and at least one of the lights forming the image synchronously pass through the optical hologram module and move along the visual direction; a signal receiver capable of continuously receiving the detection signal in the visual direction; a processor connected to the signal receiver, wherein when the signal receiver receives the detection signal, the detection signal is continuously transmitted to the processor, and wherein when the processor does not receive the detection signal, it generates a control signal.

[0023] The floating projection device according to the invention generates a floating image by arranging a first prism array and a second prism array, and lights forming the image enter the first optical interface and the second optical interface at a suitable angle of incidence, so that the lights are totally reflected at the first and second optical interface and enter the eyes of the user or observer along a specific light path, visually generating a floating image.

[0024] The invention and its embodiments are explained in more detail below with reference to the drawings. The drawings show: Fig. 1 is a perspective view of an embodiment of an optical hologram module according to the invention in which a row of a first prism array and a row of a second prism array are stacked; Fig. 2 a perspective view of the optical hologram module according to the invention in Fig. 1; Fig. 3A is a front view of the embodiment of an optical hologram module according to the invention, wherein the included angle between the third reflected light and the plane on which the display module is located is 45 degrees; Fig. 3B is a front view of another embodiment of an optical hologram module according to the invention, wherein the included angle between the third reflected light and the plane on which the display module is located is 30 degrees; Fig. 3C is a front view of yet another embodiment of an optical hologram module according to the invention; Fig. 4 is a perspective view of the three-dimensional structure of the optical hologram module according to the invention; Fig. 5 shows a section through an embodiment of a projection device according to the invention for floating projection; Fig. 6 a section through a further embodiment of a projection device according to the invention for floating projection; and Fig. 7 a section through an embodiment of an operating device according to the invention for the floating projection.

[0025] In Fig. 1 to Fig. 3 shows an embodiment of an optical hologram module 100 according to the invention, which comprises a first prism array 10 and a second prism array 20, both of which can be formed on an acrylic substrate by embossing.

[0026] As in Fig. 1 and Fig. 2, the first prism array 10 includes a plurality of first prisms 11. Each of the first prisms 11 includes a first lower prism 11a arranged in the lower row and a first upper prism 11b arranged in the upper row. In the illustrated embodiment, each of the prisms 11a, 11b has a first surface 111, a third surface 113, and a fifth surface 115. The first surface 111, the third surface 113, and the fifth surface 115 are connected to one another to form a triangular microstructure with a triangular cross-section. The first surface 111 forms the hypotenuse of the triangle, while the third surface 113 and the fifth surface 115 form two legs of the triangle, such that the included angle between the third surface 113 and the fifth surface 115 is 90 degrees.The included angle between the first surface 111 and the third surface 113 is 45 degrees, as is the included angle between the first surface 111 and the fifth surface 115. The first lower prism 11a in the lower row and the first upper prism 11b in the upper row have the same structure. The first surface 111 of the first lower prism 11a in the lower row is arranged facing the first surface 111 of the first upper prism 11b in the upper row to form a first optical interface 12. The first surface 111 of the first lower prism 11a in the lower row and the first surface 111 of the first upper prism 11b in the upper row are stacked so tightly that no air gap is formed.

[0027] As in Fig. 1, Fig. 2 and Fig. 3, the second prism array 20 includes a plurality of second prism cubes 21. Each second prism cube 21 includes a second lower prism 21a arranged in the lower row and a second upper prism 21b arranged in the upper row. In the illustrated embodiment, each of the prisms 21a, 21b has a second surface 212, a fourth surface 214, and a sixth surface 216. The second surface 212, the fourth surface 214, and the sixth surface 216 are connected to form a triangular microstructure with a triangular cross-section. The second surface 212 forms the hypotenuse of the triangle, while the fourth surface 214 and the sixth surface 216 form two legs of the triangle, such that the included angle between the fourth surface 214 and the sixth surface 216 is 90 degrees.The included angle between the second surface 212 and the fourth surface 214 is 61 degrees, while the included angle between the second surface 212 and the sixth surface 216 is 29 degrees. The second lower prism 21a in the lower row and the second upper prism 21b in the upper row have the same structure. The second surface 212 of the second lower prism 21a in the lower row is arranged facing the second surface 212 of the second upper prism 21b in the upper row to form a second optical interface 22. It should also be noted that the second surfaces 212 of the lower and upper prisms 21a, 21b are stacked so tightly that no air gap is formed.

[0028] The fourth surface 214 of the second lower prism 21a in the lower row is arranged facing the third surface 113 of the first upper prism 11b so that a third optical interface 30 is formed.

[0029] As in Fig. As shown in Figure 3A, the light L1 of a lower display module 200 or a single light source enters the first prism array 10 from the third surface 113 of the first lower prism 11a in the lower row. Since the light L1 is vertically incident on the third surface 113, the incident light L1 is partially reflected by the third surface 113, with the remainder passing through the third surface 113 and entering the first surface 11a. The light L1 is further incident at a first angle of incidence on the first surface 111 of the first lower prism 11a, which is located on the first optical interface 12. As mentioned above, the first prism cubes 11 and the second prism cubes 21 are made of acrylic material. The refractive index of acrylic material is approximately 1.49. In addition, the light is totally reflected from a dense medium to a thin medium.According to the law of refraction [Snell's law] n1sinθ1=n2sinθ2, where n1 is the refractive index of the first lower prism 11a (the refractive index of acrylic material is 1.49) and n2 is the refractive index of air [1.000027≒1]. When total internal reflection occurs, θ2 = 90 degrees, so it can be calculated that the critical angle of incidence θ1 of the light incident on the first surface 111 is 42.1 degrees. In the illustrated embodiment, the light L1 is incident at a first angle of incidence of 45 degrees, which is larger than the critical angle of incidence of 42.1 degrees. As a result, the light L1 is totally reflected at the first surface 111, forming a first reflected light L11. The first reflection light L11 moves in a direction parallel to the first surface 111 and enters the adjacent first upper prism 11b in the upper row.In the illustrated embodiment, the first reflected light L11 enters the first upper prism 11b in the upper left row, but this is not limited to the invention. In another embodiment, the inclination direction of the first surface 111 may be opposite to that of this embodiment. This means that the first reflected light L11 is caused to enter the first upper prism 11b in the upper right row.

[0030] The first reflected light L11 entering the first upper prism 11b in the upper right row strikes the first surface 111 of the first upper prism 11b at the first optical interface 12 at a second incident angle of 45 degrees. Even if the second incident angle of the first reflected light L11 is greater than the critical angle for total internal reflection, it is reflected at the first surface 111 of the first upper prism 11b and forms a second reflected light L12. The second reflected light L12 enters through the third optical interface 30 formed by the third surface 113 of the first upper prism 11b and the fourth surface 214 of the second lower prism 21a in the lower row. The second reflection light L12 falls at a third angle of incidence of 61 degrees onto the second surface 212 at the second optical interface 22. Total reflection at the second surface 212 results in a third reflection light L13.In the illustrated embodiment, the third reflection light L13 forms an included angle of 30 degrees with the fourth surface 214 of the second upper prism 21b in the upper row.

[0031] Another light L2 emitted from the display module 200 enters the first prism array 10 through the third surface 113 of another first lower prism 11a in the lower row. After the light L2 is reflected at the first optical interface 12 by the first surface 111 of the first lower prism 11a, a first reflection light L21 is generated. The first reflection light L21 also enters the adjacent first upper prism 11b and is reflected at the first optical interface 12 by the first surface 111 of the first upper prism 11b in the upper row, resulting in a second reflection light L22. The second reflection light L22 then enters the second lower prism 21a of the second prism array 20 and is reflected at the second optical interface 22 by the second surface 212 of the second lower prism 21a, resulting in a third reflection light L23.The third reflected light L23 also forms an included angle of 30 degrees with the fourth surface 214 of the second upper prism 21b in the upper row.

[0032] In Fig. 5 illustrates an embodiment of a floating projection device. In the illustrated embodiment, the floating projection device 1000 includes a hologram optical module 100 and a display module 200. After the lights L1-Ln forming an image emitted from the display module 200 arranged on the horizontal plane enter the holographic optical module 100, the optical paths of the plurality of lights are bent by the holographic optical module 100 at an oblique angle of 30 degrees formed between the third reflected light L23 and the horizontally arranged fourth surface 214. The light then enters the eyes of the viewer or user along a visual direction. When the third reflected light L23 from the holographic optical module 100 enters the eyes of the viewer or user, it creates a floating image Q.This floating image is visually generated as it moves along a visual direction defined by the oblique angle of 30 degrees between the third reflected light and the horizontally arranged fourth surface of the optical hologram module.

[0033] In Fig. 3B shows another embodiment of the optical hologram module. The difference to the embodiment in Fig. 3A is that the second surface 212 of the triangular prisms 21a, 21b forms an included angle of 63.4 degrees with their fourth surface 214 and an angle of 26.6 degrees with their sixth surface 216. In addition, an included angle of 45 degrees is formed between the third reflected light L13, L23 and the fourth surface 214.

[0034] In Fig. 3C shows yet another embodiment of the optical hologram module, which differs from the embodiment in Fig. 3A. The second surface 212 of the triangular prisms 21a, 21b forms an included angle of 30 degrees with its fourth surface 214 and an angle of 60 degrees with its sixth surface 216. Due to this geometry, the third reflected light L23 is directed toward the first prism array 10. This embodiment can be used when the optical hologram module 100 is arranged at a higher position than the user. The exit of the third reflected light L23 and its entry into the user's eyes create a floating image.

[0035] In Fig. 6 shows another embodiment of a floating projection device. In the illustrated embodiment, the floating projection device 1000' includes an optical hologram module 100, a display module 200, and an image magnification module 300. The image magnification module 300 includes a Fresnel lens, with the lights L1 passing through the Fresnel lens so that the image generated by the display module 200 can be magnified. In this way, a smaller display module can be used. The 1000' in the illustrated embodiment further includes an optical path adjustment module 400. The lights L1-Ln pass through the image magnification module 300 and the optical path adjustment module 400 one after another, so that the lights L1-Ln are concentrated toward the optical hologram module 100 and then enter the optical hologram module 100.The optical path adjustment module 400 serves to converge the diverging light toward the center and is provided with several optical microstructures (not shown). For example, a micro-convex lens array or a micro-triangular prism array can be used as optical microstructures (not shown).

[0036] In Fig.7 shows a floating projection control device. In the illustrated embodiment, the floating projection control device includes the above-mentioned floating projection device, a signal transmitter 2000, a signal receiver 3000, and a processor 4000. The signal transmitter 2000 continuously transmits a detection signal Si. The detection signal Si and at least one of the lights Lm constituting the image synchronously pass through the optical hologram module 100 and move along the visual direction. The signal receiver 3000 can continuously receive the detection signal Si in the visual direction. The processor 4000 is connected to the signal receiver 3000. When the signal receiver 3000 receives the detection signal Si, the detection signal Si is continuously transmitted to the processor 4000. When the processor 4000 does not receive the detection signal Si, it generates a control signal So.The floating projection operating device according to the embodiment can be used as a control device. A floating image is used as the operating surface, such as a computer keyboard or elevator operating buttons. The floating projection device 1000 or 1000' generates a floating image as the operating surface, and the travel path of the detection signal Si can be adapted to the operating buttons of the operating surface. When the user presses the floating operating button with their hand, the detection signal Si is interrupted by the hand, so the processor 4000 cannot receive the detection signal Si.

[0037] The processor 4000 then generates a control signal So corresponding to the operation of the button to control the device.

[0038] The floating projection device according to the invention creates a floating image by arranging a first prism array 10 and a second prism array 20 and lights forming the image entering the first optical interface 12 and the second optical interface 22 at a suitable angle of incidence, so that the lights are totally reflected at the first and second optical interfaces and enter the eyes of the user or observer along a specific light path, visually creating a floating image. List of reference symbols 10 first prism array 11 first prism cube 11a first lower prism 11b first upper prism 12 first optical interface 20 second prism array 21 second prism cube 21a first lower prism 21b first upper prism 22 second optical interface 30 third optical interface 100 optical hologram module 111 first surface 113 third surface 115 fifth surface 200 display module 212 second surface 214 fourth surface 216 sixth surface 300 image magnification module 400 optical path adjustment module 1000 Projection device for floating projection 1000' projection device for floating projection 2000 signal transmitters 3000 signal receivers 4000 processor L1 Light L11 first reflected light L12 second reflection light L13 third reflected light L2 Light L21 first reflected light L22 second reflection light L23 third reflected light Ln Light Lm light Q floating image Si detection signal So control signal

Claims

[1] Optical hologram module for a projection device for floating projection (1000, 1000'), comprising a first prism array (10) comprising a plurality of first prisms (11, 11a, 11b), each of which has a first surface (111), wherein two first prisms (11, 11a, 11b) are stacked such that their first surfaces (111) form a first optical interface (12); and a second prism array (20) comprising a plurality of second prisms (21, 21a, 21b), each of which has a second surface (212), wherein two second prisms (21, 21a, 21b) are stacked such that their second surfaces (212) form a second optical interface (12), wherein a light enters the first prism array (10) and strikes the first optical interface (12) at a first angle of incidence, wherein total reflection occurs at the first optical interface (12) at the first surface (111) of one of the prisms (11, 11a, 11b), thereby generating a first reflected light (L21); wherein another light enters the first prism array (10) and strikes the first optical interface (12) at a second angle of incidence, wherein total reflection occurs at the first optical interface (12) at the first surface (111) of another prism (11b), thereby generating a second reflected light (L12); and wherein the second reflection light (L12) enters the second prism array (20) and strikes the second optical interface (22) at a third angle of incidence, wherein total reflection occurs at the second optical interface (22) at the second surface (212) of one of the prisms (21a), thereby producing a third reflection light (L13); wherein the second prism array (20) is arranged stacked on the first prism array (10), wherein a third surface (113) of one of the prisms (11b) is arranged facing a fourth surface (214) of one of the prisms (21a) to form a third optical interface (30), and wherein the second reflection light (L12) passes through the third optical interface (30) and then enters the second prism array (20); characterized by , that each of the second prisms (21, 21a, 21b) further comprises a sixth surface (216), wherein the second prisms (21, 21a, 21b) are designed as triangular prisms, and wherein the second surface (212), the fourth surface (214) and the sixth surface (216) are connected to each other in pairs, and wherein the included angle between the fourth surface (214) and the sixth surface (216) is 90 degrees, and wherein the included angle between the second surface (212) and the fourth surface (214) is 60 to 65 degrees and the included angle between the second surface (212) and the sixth surface (216) is 25 to 30 degrees; or the included angle between the second surface (212) and the fourth surface (214) is 25 to 30 degrees and the included angle between the second surface (212) and the sixth surface (216) is 60 to 65 degrees. [2] Optical hologram module according to claim 1, characterized by that the first reflection light (L21) enters the other two adjacent overlapping first prisms (11b) of the first prism array (10). [3] Optical hologram module according to claim 1, characterized by that the first angle of incidence is greater than or equal to 45 degrees. [4] Optical hologram module according to claim 1, characterized by that the second angle of incidence is greater than or equal to 45 degrees. [5] Optical hologram module according to claim 1, characterized by that the angle between the third reflected light (L13) and a fourth surface (214) of each second prism (21) is greater than or equal to 30° degrees and less than or equal to 45 degrees. [6] Optical hologram module according to claim 1, characterized byin that each of the first prisms (11, 11a, 11b) further comprises a fifth surface (115), wherein the first prisms (11, 11a, 11b) are designed as triangular prisms, and wherein the first surface (111), the third surface (113) and the fifth surface (115) are connected to one another in pairs, and wherein the included angle between the third surface (113) and the fifth surface (115) is 90 degrees, and wherein the included angle between the first surface (111) and the third surface (113) is 45 degrees, and wherein the included angle between the first surface (111) and the fifth surface (115) is also 45 degrees. [7] Projection device for floating projection, comprising a display module (200) that emits a plurality of lights forming an image; an optical hologram module (100) according to one of claims 1 to 6; and an image magnification module (300) through which the light passes and then enters the optical hologram module (100) after being magnified; wherein the optical hologram module (100) directs the light in a specific direction and bends it in that direction to produce a floating image (Q) that can be viewed by an observer. [8] Projection device according to claim 7, characterized by that the image magnification module (300) has a Fresnel lens, wherein the lights pass through the Fresnel lens. [9] The projection apparatus according to claim 8, further comprising an optical path adjusting module (400), wherein the lights pass through the image magnifying module (300) and the optical path adjusting module (400) in sequence so that the lights are concentrated toward the optical hologram module (100) and then enter the optical hologram module (100). [10] Projection device according to claim 9, characterized by that the optical path adaptation module (400) is provided with a plurality of optical microstructures which are arranged two-dimensionally. [11] Projection device according to claim 10, characterized by that the optical microstructure is designed as a convex lens, with the sizes of the convex lenses being equal or unequal. [12] Control device for floating projection, comprising a floating projection device (1000, 1000') according to any one of claims 7 to 11; a signal transmitter (2000) continuously emitting a detection signal (Si), wherein the detection signal (Si) and at least one of the lights forming the image synchronously pass through the optical hologram module (100) and move along the visual direction; a signal receiver (3000) capable of receiving the detection signal (Si) continuously in the visual direction; and a processor (4000) connected to the signal receiver (3000), wherein when the signal receiver (3000) receives the detection signal (Si), the detection signal (Si) is continuously transmitted to the processor (4000), and wherein when the processor (4000) does not receive the detection signal (Si), it generates a control signal (So).

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