CN109358471B

CN109358471B - Stereoscopic display device

Info

Publication number: CN109358471B
Application number: CN201811539949.3A
Authority: CN
Inventors: 刘邦宏
Original assignee: Qisda Suzhou Co Ltd; Qisda Corp
Current assignee: Qisda Suzhou Co Ltd; Qisda Corp
Priority date: 2018-12-17
Filing date: 2018-12-17
Publication date: 2021-01-05
Anticipated expiration: 2038-12-17
Also published as: CN109358471A

Abstract

The present invention provides a stereoscopic display device, including: the first driving unit is arranged on a first base on the first driving unit, and a first end of the first driving unit is arranged on a first scattering unit on the first base; the first scattering unit comprises a first number of scattering bodies for scattering the projected light; the first projection unit is arranged at the second end side of the first scattering unit and used for projecting a first light beam towards the first scattering unit; and the processing unit is electrically connected with the first driving unit and the first projection unit and used for controlling the first driving unit to rotate and controlling the first projection unit to project a first light beam to the scatterer so as to form a display image in a first space formed by the rotation of the first scattering unit. According to the stereoscopic display device provided by the invention, an observer can observe a more real stereoscopic display image at any angle outside the first space.

Description

Stereoscopic display device

Technical Field

The present invention relates to the field of display, and more particularly, to a stereoscopic display device having a persistence of vision effect by rotating a light emitting element.

Background

In recent years, with the rapid development of video display technology, development of technology for displaying stereoscopic video is being advanced, and the technology is widely used for entertainment, medical care, electronic catalogs, advertisements, and the like.

In the prior art, a light beam is usually projected to a tilted reflector capable of rotating at a high speed, the reflector projects reflected light rays to a cylindrical transmission screen parallel to a rotation axis, and the transmission screen can control the divergence angle of the transmitted light rays, so that left and right eyes of an observer can see images at different viewing angles to form a panoramic stereoscopic image. However, the viewing angle of this design is limited by the polarization angle of the diffuser, and when the head of the observer is tilted, the images of the left and right eyes cannot be effectively distinguished, so that the stereoscopic image cannot be observed.

Disclosure of Invention

It is an object of the present invention to provide a stereoscopic display device which overcomes the above problems.

To achieve the above object, the present invention provides a stereoscopic display device, comprising:

a first driving unit to rotate based on a first rotation axis;

the first base is arranged on the first driving unit and is used for rotating under the driving of the first driving unit;

the first scattering unit comprises a first number of scatterers and is used for scattering light projected to the scatterers; the first scattering unit comprises a first end and a second end which are opposite in position, and the first end is arranged on the first base;

the first projection unit is arranged at the second end side of the first scattering unit and used for projecting a first light beam towards the first scattering unit; and

and the processing unit is electrically connected with the first driving unit and the first projection unit, and is used for controlling the first driving unit to rotate and controlling the first projection unit to project the first light beam to the scatterer so as to form a display image in a first space formed by the rotation of the first scattering unit.

Preferably, the stereoscopic display device further includes a second projection unit, the second projection unit is located at the first end side of the first scattering unit, and the second projection unit is configured to project a second light beam toward the first scattering unit.

Preferably, the second projection unit is located below the first base, and the second light beam projected by the second projection unit penetrates through the first base and is projected towards the first scattering unit.

Preferably, the first scattering unit includes a first number of scattering objects, specifically:

the first scattering unit comprises a plurality of bars, and each bar comprises a second number of scattering bodies.

Preferably, each bar lies in a plane parallel to the first axis of rotation.

Preferably, each bar is parallel to the first rotating shaft, and the central line direction of the first light beam projected by the first projection unit forms an acute angle with the first rotating shaft; alternatively, the first and second electrodes may be,

each strip-shaped body forms a first acute angle with the first rotating shaft respectively; the central line direction of the first light beam projected by the first projection unit is parallel to the first rotating shaft, or the central line direction of the first light beam projected by the first projection unit forms a second acute angle with the first rotating shaft, and the second acute angle is different from each first acute angle.

Preferably, the first base further comprises a first shaft body, and the first shaft body is overlapped with the first rotating shaft; each strip-shaped body is perpendicular to the first rotating shaft and is fixed on the first shaft body.

Preferably, the first scattering unit includes a transparent cylindrical body, wherein the cylindrical body includes the first number of scattering objects.

In order to achieve the above object, the present invention also provides a stereoscopic display device, comprising:

a first driving unit to rotate based on a first rotation axis;

the first scattering unit comprises a first number of scatterers and is used for scattering light projected to the scatterers; the first end of the first scattering unit is arranged on the first base, and the second end of the first scattering unit is far away from the first end; the first scattering unit is used for rotating to form a first space;

a second driving unit to rotate based on a second rotation shaft;

the second base is arranged on the second driving unit and is used for rotating under the driving of the second driving unit;

the second scattering unit comprises a first number of scatterers and is used for scattering light projected to the scatterers; the third end of the second scattering unit is arranged on the second base; the second scattering unit is used for rotating to form a second space, wherein the first space and the second space have an overlapping part;

the first projection unit is arranged at the second end side of the first scattering unit and used for projecting a first light beam to the space of the overlapped part; and

the processing unit is electrically connected with the first driving unit, the second driving unit and the first projection unit and is used for controlling the first driving unit and the second driving unit to synchronously rotate so as to ensure that the first scattering unit and the second scattering unit do not generate mechanical interference in the rotating process; and the processing unit is used for controlling the first projection unit to project the first light beam to the space of the overlapped part so as to form a display image.

Preferably, the first projection unit is further configured to project the first light beam to a space other than the overlapping portion in the first space and/or the second space.

Compared with the prior art, the stereoscopic display device provided by the invention rotates the scatterer in the transparent space and scatters the projected light, so that a stereoscopic display image is formed in the space formed by rotation, and an observer can observe a more real stereoscopic display image at any angle outside the space.

Drawings

Fig. 1 is a schematic structural diagram of a stereoscopic display device according to an embodiment of the invention;

fig. 2 is a schematic structural diagram of a stereoscopic display apparatus according to another embodiment of the invention;

FIG. 3 is a schematic structural diagram of a stereoscopic display apparatus according to another embodiment of the invention;

fig. 4A is a schematic structural diagram of a stereoscopic display apparatus according to another embodiment of the invention;

FIG. 4B is a partial top view of FIG. 4A;

fig. 5A is a schematic structural diagram of a stereoscopic display apparatus according to another embodiment of the invention;

fig. 5B is a partial top view of fig. 5A.

Detailed Description

In order to further understand the objects, structures, features and functions of the present invention, the following embodiments are described in detail.

Certain terms are used throughout the description and following claims to refer to particular components. As one of ordinary skill in the art will appreciate, manufacturers may refer to a component by different names. The present specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to.

Referring to fig. 1, a schematic structural diagram of a stereoscopic display device according to an embodiment of the invention is disclosed, which includes: the display device includes a first driving unit 100, a first base 110, a first scattering unit 120, a first projection unit 130, and a processing unit 140.

The first driving unit 100 is configured to rotate based on a first rotation axis S.

The first base 110 is disposed on the first driving unit 100, and the first base 110 is driven by the first driving unit 100 to rotate.

The first diffusion unit 120 includes a first number of diffusers 120s, and diffuses light incident on the diffusers 120 s. The first end 120a of the first scattering unit 120 is disposed on the first base 110, and includes a first end 120a and a second end 120b opposite to each other, i.e., the second end 120b is far away from the first end 120a, or the first scattering unit 120 has two

ends

120a and 120b along its length direction.

In one embodiment, the scattering body 120s is a scattering material, and except for the scattering body 120s, other parts of the first scattering unit 120 are made of a transparent material, including but not limited to silicon dioxide, acryl, plastic, and the like. The scattering material 120s may be translucent, for example, the scattering material 120s is a phosphor, an air bubble, or the like. The scattering material may also be transparent, for example, it may be liquid crystal, and the rotation of the liquid crystal particles is realized under the control of the electrode, so as to present a state capable of scattering light or transmitting light; in this case, a transparent conductor, such as ito (indium tin oxide); the invention is not limited thereto.

The scattering bodies 120S may be distributed at different heights and different radii (radii with respect to the first rotation axis S) in the first scattering unit 120. The scattering body 120s irradiated with the projected light scatters the light so as to be observable; the scatterer 120s not irradiated by the projection light is not observable or is easily ignored by the human eye.

In one embodiment, the first scattering unit 120 includes a plurality of bars, each bar includes a second number of scatterers 120s, and the scatterers 120s in all the bars are the first number of scatterers 120s included in the first scattering unit 120. Each bar may lie in a plane parallel to the first axis of rotation S. In particular implementation, each bar may be parallel to the first axis of rotation S; or each strip body and the first rotating shaft form a first acute angle, and the first acute angles formed by different strip bodies can be different or the same; for example, the end points of the plurality of bars formed at the first end 120a are arranged as a first line, the end points of the plurality of bars formed at the second end 120b are arranged as a second line, the projections of the first line and the second line in the plane perpendicular to the first rotation axis S are symmetrical around the first rotation axis S, and at this time, the first acute angles formed by different bars are different; for another example, the projections of the first line and the second line in a plane perpendicular to the first rotation axis S are symmetrical with respect to a diameter passing through the first rotation axis S, and the first acute angles formed by the different bars are the same. Each bar may also lie in a radial plane of the first axis of rotation S. The invention is not limited thereto.

In one embodiment, the second end 120b of the first scattering unit 120 may be a free end, or the second end 120b is not in contact with other mechanisms. In another embodiment, the second end 120b of the first scattering unit 120 may also be fixed in a base structure similar to the first base 110, and the base similar to the first base 110 may coaxially rotate in the same direction relative to the first base 110. For example, the first base 110 and the base similar to the first base 110 may be a disk-shaped structure, or may be another structure including the first end 120a or the second end 120b for fixing the first scattering unit 120, such as an oval, a fan, a curved cantilever, etc., and the first base 110 and the base similar to the first base 110 may be any one of the above-mentioned structures, which may be the same or different; the invention is not limited thereto.

The first projection unit 130 is disposed at the second end 120b side of the first diffusion unit 120, and projects the first light beam L1 toward the first diffusion unit. For example, as shown in fig. 1 to 3, when the first base 110 is located below the first diffusion unit 120, the first projection unit 130 is located above the first diffusion unit 120, and projects the first light beam L1 toward the lower first diffusion unit 120. The relative positions of the three are not limited to this, for example, the first base 110 may also be located above the first scattering unit 120, and the first projection unit 130 is located below the first scattering unit 120; the invention is not limited thereto.

The first projection unit 130 may be a directional light source that generates a parallel light beam or a light beam with a small divergence angle. For example, when the scattering body 120s is formed of liquid crystal, the scattering and transmission states of the liquid crystal are related to the angle of the projected beam, in addition to the rotation angle thereof; if the divergence angle of the projected first light beam L1 is too large, it is easy to generate false transmission or false scattering, and the final displayed image will generate errors, which are not in accordance with the desired projection effect.

The first projection unit 130 may be a single light source. For example, the first light beam L1 projected by the first projection unit 130 has a pattern, and the pattern projected by the single light source is projected onto the scatterers 120s distributed in the first scattering unit 120, so as to represent the pattern as a stereoscopic image; the first projection unit 130 may also project the first light beam L1 with a predetermined brightness and/or color such that a stereoscopic image presented by the diffuser 120s itself is exhibited; the pattern projected by the first projection unit 130 and the pattern of the scatterer 120s are superimposed to present a mixed type stereoscopic image; and so on. The first projection unit 130 may also be a plurality of light sources, which may project the first light beam L1 with the same or different parameters, including but not limited to projection direction, divergence angle, color, brightness, static or dynamic pattern, etc. The multiple light sources may be projected in a superposition manner or in an alternating manner, so as to show a specific image effect. The invention is not limited thereto.

In an embodiment, each of the bars of the first diffusion unit 120 is parallel to the first rotation axis S, as shown in fig. 1 and 3, when the first projection unit 130 projects the first light beam L1 in a direction inclined with respect to the first rotation axis S, or forming an acute angle with the first rotation axis S, so that the first light beam L1 can be projected to each of the scattering objects 120S in the bar of the first diffusion unit 120. The direction in which the first projection unit 130 projects the first light beam L1 may be a parallel light projection direction, or a center line direction of the first light beam L1 having a divergence angle.

In another embodiment, each of the bars of the first scattering unit 120 forms a first acute angle with the first rotation axis S, as shown in fig. 2, and at this time, the direction of the first light beam L1 projected by the first projection unit 130 may be parallel to the first rotation axis S, that is, the first light beam L1 may be projected to each of the scattering bodies 120S in the bars of the first scattering unit 120; at this time, the first projection unit 130 may project the first light beam L1 in a direction forming a second acute angle with the first rotation axis S, the second acute angle being different from each first acute angle, and may project the first light beam L1 to each scattering body 120S in the bar-shaped body of the first scattering unit 120. The direction in which the first projection unit 130 projects the first light beam L1 may be a parallel light projection direction, or a center line direction of the first light beam L1 having a divergence angle.

The processing unit 140 is electrically connected to the first driving unit 100 and the first projecting unit 130. The processing unit 140 controls the first driving unit 100 to rotate and controls the first projecting unit 130 to project the first light beam L1 so as to form a display image in the first space formed by the rotation of the first scattering unit 120.

Referring to fig. 3, a schematic structural diagram of a stereoscopic display device according to an embodiment of the invention is disclosed. The stereoscopic display device further includes a second projection unit 150, and the second projection unit 150 is located at the first end 120a side of the first diffusion unit 120 and projects the second light beam L2 toward the first diffusion unit 120. In one embodiment, the second projection unit 150 is located below the first base 110, and projects the second light beam L2 to the first scattering unit 120 after penetrating through the first base 110. The projection directions of the first projection unit 130 and the second projection unit 150 are related to the arrangement of the first scattering unit 120, and reference is made to the relationship between the projection direction of the first projection unit 130 and the first scattering unit 120, which is not described herein again.

The second projection unit 150 may cooperate with the first projection unit 130 to project in an overlapping manner, so as to improve the brightness of the portion of the first scattering unit 120 far away from the first projection unit 130 to be lower than the brightness of the portion near the first projection unit 130. The second projection unit 150 can also project alternately with the first projection unit 130 to present richer image effects; in this case, the brightness, color, and position of the irradiation scatterer 120s of the first projection unit 130 and the second projection unit 150 may be set as necessary according to the projection effect. For example, the first projection unit 130 projects a stereoscopic image of a first object in a first color, the second projection unit 150 projects a stereoscopic image of a second object in a second color, and the first object and the second object may even have an interaction and a blending of images in a projection space. The first projection unit 130 and the second projection unit 150 may also project to different areas in the space to provide integrated image illumination, for example, the outer ring side with lower brightness illumination to create a subdued effect and the inner ring side with higher brightness illumination to emphasize the inner stereoscopic image. The invention is not limited thereto.

Referring to fig. 4A and 4B, a schematic structural diagram of an embodiment of a stereoscopic display apparatus according to the invention is disclosed. The first base 110 further includes a first shaft body 110S, and the first shaft body 110S coincides with the first rotation axis S. The first scattering unit 120 has a plurality of bars. The strip is perpendicular to the first rotating shaft S, and one end of the strip is fixed to the first shaft 110S, or the strip is radially distributed and fixed to the first rotating shaft S. In a preferred embodiment, the strips in the first scattering unit 120 may be distributed with rotational symmetry about the first rotation axis S to obtain better mechanical stability, as shown in fig. 4B. At this time, the direction of the first light beam L1 projected by the first projection unit 130 is parallel to the first rotation axis S, that is, the second light beam L1 can be projected to each scattering body 120S in the bar-shaped body of the first scattering unit 120; at this time, the direction of the first light beam L1 projected by the first projection unit 130 may also form an acute angle with the first rotation axis S, so as to enhance the brightness of the image viewable in a certain viewing angle region.

In a preferred embodiment, the first base 110 includes only the first shaft 110 s. At this time, it is preferable that the first scattering unit 120 is visually separated from the first driving unit 100 by a flat object fixed to the fixed portion of the first driving unit 100; it is also possible to design the fixed branch portion of the first driving unit 100 to conform to the appearance of the first shaft body 110s, such as a cylinder with uniform radial dimension, a shape with continuous appearance, a pattern, and so on; the invention is not limited thereto.

In one embodiment, the first scattering unit 120 may further include a transparent cylinder including the first number of scattering bodies 120s therein. The composition and structure of the scattering body 120s are similar to those of the scattering body 120s in the foregoing embodiments, and are not described again here.

The stereo display device provided by the invention can also display images by adopting two or more groups of combinations. Referring to fig. 5A and 5B, a schematic structural diagram of an embodiment of a stereoscopic display apparatus according to the invention is disclosed. The stereoscopic display device in fig. 5A and 5B includes two sets of rotators, and specifically includes a first driving unit 100, a first base 110, a first scattering unit 120, a second driving unit 100 ', a second base 110 ', a second scattering unit 120 ', a first projecting unit 130, and a processing unit 140.

The first driving unit 100 is configured to rotate based on a first rotation axis S. The first base 110 is disposed on the first driving unit 100, and the first base 110 is driven by the first driving unit 100 to rotate. The first scattering unit 120, including the first number of scattering objects 120s, may scatter light incident on the scattering objects 120 s. The first end 120a of the first scattering unit 120 is disposed on the first base 110, and the first scattering unit 120 is configured to rotate to form a first space.

The second driving unit 100 'is configured to rotate based on the second rotation axis S'. The second base 110 'is disposed on the second driving unit 100', and the second base 110 'is configured to rotate under the driving of the second driving unit 100'. The second diffusion unit 120' includes a first number of diffusers 120s, and diffuses light incident on the diffusers 120 s. The first end 120a 'of the second scattering unit 120' is disposed on the second base 110 ', and the second scattering unit 120' is configured to rotate to form a second space. The first space and the second space have an overlapping portion a.

The first projection unit 130 is disposed at the second end 120b side of the first scattering unit 120, and is used for projecting the first light beam L1 to the overlapping portion a.

The processing unit 140 is electrically connected to the first driving unit 100, the second driving unit 100 ' and the first projection unit 130, and the processing unit 140 is configured to control the first driving unit 100 and the second driving unit 100 ' to rotate synchronously, so that the first scattering unit 120 and the second scattering unit 120 ' do not interfere with each other mechanically during the rotation process; the processing unit 140 is configured to control the first projection unit to project the first light beam L1 to the overlapping portion a to form a display image. When the first base 110 and the second base 110 'include the first shaft 110s and the second shaft 110 s' as shown in fig. 5A and 5B, the overlapping portion a is used as the area for displaying the image, so as to further avoid the adverse effect on the displayed image caused by the shielding of the shafts. In practical operation, the first driving unit 100 and the second driving unit 100' may be motors, or may be a rotating structure driven by the motors, which is not limited in the present invention.

In one embodiment, the first projection unit 130 is further configured to project the first light beam L1 to a space other than the overlapping portion a in the first space and/or the second space.

As shown in fig. 5A and 5B, when the first scattering unit 120 employs a plurality of bars, especially when one end of the bar is fixed in the transverse direction, the length of the bar has a certain limit due to the influence of its own gravity. By adopting the combined type three-dimensional display device, a plurality of spaces formed by rotating the shorter strip-shaped bodies can be combined to form a larger space for displaying images, so that the display requirement in a wider range is met.

As shown in fig. 5B, the relative angles of the first rotating shaft S and the second rotating shaft S' may be adjusted so that the strips of the first scattering units 120 of the two rotate in the same direction or in different directions in a manner of passing through the overlapping portion a alternately, thereby avoiding collision. Preferably, the first and second rotation axes S and S' are parallel to each other. The first rotation axis S and the second rotation axis S' may also form a certain angle, thereby combining into an image display region with a specific shape.

The combination manner of the first base 110 and the first scattering unit 120 may also be similar to that of the first base 110 and the first scattering unit 120 in fig. 1 to 3, and the combination manner of the second base 110 'and the second scattering unit 120' may also be similar to that of the first base 110 and the first scattering unit 120 in fig. 1 to 3, which is not described herein again. As shown in fig. 1 to 3, when the first diffusion unit 120 covers only a local angular space of the first space and the second diffusion unit 120 ' covers only a local angular space of the second space, the first diffusion unit 120 and the second diffusion unit 120 ' may pass through the overlapping portion a in a staggered manner, and the first rotation axis S and the second rotation axis S ' are rotated in synchronization. Preferably, the first and second rotation axes S and S' are parallel to each other. The first rotating shaft S and the second rotating shaft S' rotate in the same direction or in different directions. Preferably, in order to increase the ratio of the overlapping portion a to the first space and the second space, the rotation in the same direction is preferred. The first rotation axis S and the second rotation axis S' may also form a certain angle, thereby combining into an image display region with a specific shape.

In summary, the first projection unit projects a light beam to the first scattering unit driven to rotate, and the light beam is scattered by the corresponding scattering body in the first scattering unit, so that an image formed in a space outside the space formed by the rotation of the first scattering unit can be observed due to the human eye persistence effect, and the image is not affected by the viewing angle. In addition, two or more scattering units can be combined to form a larger display space, so that the larger display space can be realized by using the scattering unit components with smaller sizes, and the problems of bending, difficult driving and the like caused by the overlarge size of the scattering unit are avoided.

The present invention has been described in relation to the above embodiments, which are only exemplary of the implementation of the present invention. It should be noted that the disclosed embodiments do not limit the scope of the invention. Rather, it is intended that all such modifications and variations be included within the spirit and scope of this invention.

Claims

1. A stereoscopic display apparatus, comprising:

a first driving unit to rotate based on a first rotation axis;

the first projection unit is arranged at the second end side of the first scattering unit and used for projecting a first light beam towards the first scattering unit;

a second projection unit located at the first end side of the first scattering unit, the second projection unit being configured to project a second light beam toward the first scattering unit; and

2. The stereoscopic display apparatus according to claim 1, wherein the second projection unit is located below the first base, and the second light beam projected by the second projection unit penetrates the first base and is projected toward the first scattering unit.

3. The stereoscopic display apparatus according to claim 1, wherein the first scattering unit comprises a first number of scatterers, in particular:

4. A stereoscopic display apparatus according to claim 3, wherein each bar lies in a plane parallel to the first axis of rotation.

5. The stereoscopic display apparatus according to claim 4, wherein each of the bars is parallel to the first rotation axis, and a center line direction of the first light beam projected by the first projection unit forms an acute angle with the first rotation axis; alternatively, the first and second electrodes may be,

6. The stereoscopic display apparatus according to claim 3, wherein the first base further comprises a first shaft body, the first shaft body is coincident with the first rotating shaft; each strip-shaped body is perpendicular to the first rotating shaft and is fixed on the first shaft body.

7. The stereoscopic display apparatus according to claim 1, wherein the first scattering unit comprises transparent pillars, wherein the pillars comprise the first number of scatterers.

8. A stereoscopic display apparatus, comprising:

a first driving unit to rotate based on a first rotation axis;

the first scattering unit comprises a first number of scatterers and is used for scattering light projected to the scatterers; the first scattering-scattering unit comprises a first end and a second end which are opposite in position, and the first end is arranged on the first base;

the processing unit is electrically connected with the first driving unit and the first projection unit, and is used for controlling the first driving unit to rotate and controlling the first projection unit to project the first light beam to the scatterer so as to form a display image in a first space formed by the rotation of the first scattering unit;

wherein each strip forms a first acute angle with the first rotating shaft; the central line direction of the first light beam projected by the first projection unit is parallel to the first rotating shaft, or the central line direction of the first light beam projected by the first projection unit forms a second acute angle with the first rotating shaft, and the second acute angle is different from each first acute angle.

9. The stereoscopic display apparatus according to claim 8, further comprising a second projection unit located at the first end side of the first scattering unit, the second projection unit being configured to project a second light beam toward the first scattering unit.

10. The stereoscopic display apparatus according to claim 9, wherein the second projection unit is located below the first base, and the second light beam projected by the second projection unit penetrates the first base and is projected toward the first scattering unit.

11. The stereoscopic display apparatus according to claim 8, wherein the first scattering unit comprises a first number of scatterers, in particular:

12. The stereoscopic display apparatus according to claim 11, wherein the first base further comprises a first shaft body, the first shaft body coinciding with the first rotating shaft; each strip-shaped body is perpendicular to the first rotating shaft and is fixed on the first shaft body.

13. The stereoscopic display apparatus according to claim 8, wherein the first scattering unit comprises transparent pillars, wherein the pillars comprise the first number of scatterers.

14. A stereoscopic display apparatus, comprising:

a first driving unit to rotate based on a first rotation axis;

a second driving unit to rotate based on a second rotation shaft;

15. The stereoscopic display apparatus of claim 14,

the first projection unit is further configured to project the first light beam to a space other than the overlapping portion in the first space and/or the second space.