A suspended rear-projection volume display system and method with constant optical path

Abstract

The present invention discloses a suspended rear-projection volumetric display system and method with a constant optical path. A vibration table, a reflection table, and a rear-projection table are arranged vertically in sequence from bottom to top. The vibration table is fixed, the reflection table is elastically connected to the vibration table via a first elastic member, the second reflector is fixed to the reflection table, the rear-projection table is elastically connected to the reflection table via a second elastic member, and the imaging screen is fixed to the rear-projection table, with the imaging plane being horizontal. Projection light emitted by a projector is reflected by the first and second reflectors in sequence, and then passes through the rear-projection table to illuminate the imaging screen from the back, forming an image on the front of the imaging screen. The rear-projection volumetric display is performed using the imaging screen's vibration range as the imaging area. The present invention can produce clear and uniform images regardless of the amplitude of the rear-projection table's vibration or the real-time height of the moving imaging screen, thereby obtaining clear voxels of uniform size. When the mass of the reflection table is significantly smaller than that of the rear-projection table, the force amplitude acting on the frame can be significantly reduced, thereby significantly reducing the counterweight mass of the entire device.

Description

Technical Field

[0001] The present invention relates to a true three-dimensional image display system and method, and in particular to a suspended rear-projection volume display system and method with a constant optical path. Background Art

[0002] The principle of the publicly available suspended rear projection volume display system is as follows: Figure 3 As shown. On a vibration table 1 that can generate vertical vibration (amplitude e and frequency f 0 are all adjustable), through the second elastic member 4 (stiffness coefficient is k , which may not be a constant), a rear projection platform 5 (with a mass of m ), the imaging screen 9 is fixedly connected to the rear projection table 5, and the imaging surface is horizontal; when the vibration table 1 is stationary ( e =0), which together constitute a first-order suspension system that vibrates in the vertical direction.

[0003] The mass of this first-order suspension system ( m ) and stiffness coefficient ( k ) is matched so that its natural frequency during free vibration is f 1 can be used as the scanning frequency of the rear projection volume display. When the vibration table 1 vibrates slightly at its natural frequency ( e >0 and f 0= f 1) The suspension system resonates, and the vibration table 1 vibrates greatly. The actual amplitude after stabilization is A By fine-tuning the amplitude of the vibration table e Control is performed. Simultaneously, light emitted from the fixed projector 6 is reflected by a fixed first reflector 7 and projected onto the moving imaging screen 9, forming a sequence of two-dimensional images of varying heights within the imaging area 10. Through the persistence of vision effect, these two-dimensional images are superimposed into a three-dimensional image for the observer. The advantage of this system is that, through its suspension, it effectively mitigates the noise generated by the high-speed reciprocating motion of the imaging screen. However, because the optical path from the projector 6 to the imaging screen 9 changes rapidly, this creates two significant limitations:

[0004] First, the shape of the imaging area 10 is a trapezoid, which is smaller at the bottom and larger at the top, so the voxel sizes are uneven;

[0005] Second, the height of the imaging area 10 A The size of is very limited because the projector can only form a clear image when the imaging screen 9 is near the focal plane. Summary of the Invention

[0006] In order to solve the problems existing in the background technology and to overcome the above two limitations, the purpose of the present invention is to provide a suspended rear-projection volume display system and method with a constant optical path.

[0007] The technical solution adopted by the present invention to solve its technical problem is:

[0008] 1. A suspended rear-projection volumetric display system with constant optical path:

[0009] The system includes a vibration table, a first elastic member, a reflection table, a second elastic member, a rear projection table, a projector, a first reflector, a second reflector and an imaging screen; the vibration table, the reflection table and the rear projection table are arranged in sequence from bottom to top in a vertical direction, the vibration table is fixedly installed, the reflection table is elastically connected to the vibration table via the first elastic member, the second reflector is fixed on the reflection table and faces the rear projection table, the rear projection table is elastically connected to the reflection table via the second elastic member, the imaging screen is fixedly connected to the rear projection table, and the imaging surface is horizontal; the projection light emitted from the fixedly installed projector is reflected by the first reflector and the second reflector in sequence, and is irradiated from the rear direction of the rear projection table to the imaging screen, and an image is formed on the front of the imaging screen; the vibration range of the imaging screen is used as the imaging area to perform rear projection volume display.

[0010] The combination of four parameters, namely the stiffness coefficient of the first elastic member, the stiffness coefficient of the second elastic member, the mass of the reflection table and the mass of the rear projection table, ensures that the system has a natural mode that vibrates in the vertical direction, the natural frequency of the natural mode is not less than 10 Hz, the vibration phases of the rear projection table and the reflection table are the same, and the amplitude of the rear projection table is twice the amplitude of the reflection table, thereby keeping the optical path of the rear projection volume display constant.

[0011] In this way, the second reflector moves in a fixed direction along with the reflector, which is equivalent to a vibration table. The rear projection stage, on the other hand, moves in a fixed direction along with the vibration table. The stiffness coefficients of the first and second elastic members are typically different, and the masses of the reflector and rear projection stages are also different. This allows the vibration table to generate a vibration force on the first elastic member, which is then transmitted to the reflector, and then to the rear projection stage via the second elastic member, causing resonance and exciting natural modes.

[0012] The vibration table vibrates slightly in the vertical direction. By adjusting the frequency and amplitude of the vibration, the system resonates, and the vibration of the natural mode is excited. Driven by the first elastic member and the second elastic member, the rear projection table and the reflection table generate stable, in-phase, large-scale vibrations in the vertical direction, thereby keeping the optical path of the rear projection volume display constant.

[0013] By driving the rear projection table and the reflection table to vibrate relatively high and fast under the action of the first elastic member and the second elastic member, the surface of the rear projection table vibrates high and fast with the projection optical path unchanged, and rear projection stereoscopic display is performed in the imaging area.

[0014] The second reflector is horizontally fixedly connected to a side surface of the reflection platform facing the rear projection platform, and the first reflector faces the second reflector and is fixedly installed.

[0015] The first reflector and the second reflector are arranged at a right angle to each other, facing the rear projection stage, and are both fixed to the reflection stage.

[0016] The first elastic member and the second elastic member are tension springs or rubber bands, or compression springs or rubber, and can also be elastic materials in other shapes.

[0017] The vibration table is composed of 2 to 8 vibrators with the same phase and amplitude connected in parallel;

[0018] The first elastic member is composed of 2 to 8 parallel tension springs or rubber bands and arranged symmetrically, one end of the tension spring or rubber band is hung on the vibration table, and after being pulled obliquely in a substantially horizontal direction, the other end is hung on the reflection table;

[0019] The second elastic member is composed of 2 to 8 tension springs or rubber bands different from the first elastic member, which are connected in parallel and arranged symmetrically. One end of the tension spring or rubber band is hung on the reflection table, and after being pulled obliquely in a roughly horizontal direction, the other end is hung on the rear projection table.

[0020] The first elastic member and the second elastic member have the same structure and both include a guide rod, a guide cylinder and a limit ring. The guide cylinder is fixed to the reflection table, and the guide rod is movably mounted in the guide cylinder. Two springs are mounted on the outside of the guide rod portion mounted in the guide cylinder. An outer flange is provided on the outer peripheral surface of the guide rod between the two springs as a position-adjustable limit ring. One end of the two springs can be connected to the limit ring, and the other end can be connected to the two ends inside the guide cylinder; and one end of the guide rod extends out of the guide cylinder and is fixedly connected to the rear projection table or the vibration table.

[0021] The guide rod can be connected to the limit surface at most at one end, but not at both ends.

[0022] 2. Rear projection volume display method based on suspended rear projection volume display system:

[0023] The vibration table generates a small vibration in the vertical direction, which is transmitted to the reflection table through the first elastic member, and then transmitted to the rear projection table through the second elastic member, generating resonance. The rear projection table and the reflection table generate a large relative vibration in the vertical direction under the action of the first elastic member and the second elastic member, so that the optical path from the fixedly installed projector to the imaging screen fixedly connected to the rear projection table remains constant after being reflected by the fixedly installed first reflector and the second reflector fixedly connected to the reflection table. The vibration range of the imaging screen is used as the imaging area to perform rear projection volume display.

[0024] The first reflecting mirror is only used to change the position of the projector, and may be absent or multiple. The number of the second reflecting mirrors fixedly connected to the reflecting platform is not limited, but there must be at least one.

[0025] The solution of the present invention specifically includes a rear projection table fixedly connected to an imaging screen, which is installed on a reflecting table fixedly connected to a reflecting mirror through a group of elastic members. The reflecting table is installed on one or a group of vibration tables that can generate vertical vibrations through another group of elastic members.

[0026] When the vibration table is stationary, the rear projection table, the reflection table, the vibration table and the two sets of elastic members together constitute a second-order suspension system that vibrates freely in the vertical direction.

[0027] The configuration of the mass and stiffness coefficients of this second-order suspension system is such that one of its two natural modes during free vibration, called the operating mode, satisfies the following conditions:

[0028] First, the natural frequency of vibration is no less than 10 Hz, which can be used as the scanning frequency of rear-projection volume display;

[0029] Second, the vibration phases of the rear projection table and the reflection table are the same, and the amplitude of the rear projection table is twice that of the reflection table.

[0030] When the vibration table vibrates at the natural frequency of the working mode, the second-order suspension system resonates and its working mode is excited. The actual amplitude of the working mode after stabilization is adjusted by changing the amplitude of the vibration table.

[0031] At the same time, when the light emitted from the fixed projector reaches the moving imaging screen after being reflected by the moving reflector, it meets the second condition in the working mode and can keep the optical path constant, thereby forming a two-dimensional image sequence of different heights but equal size in the imaging area. With the help of the visual persistence effect, these two-dimensional image sequences are superimposed into a clear three-dimensional image for the observer.

[0032] The beneficial effects of the present invention are:

[0033] Compared with the previously disclosed suspended rear-projection volume display system, the present invention has the following advantages:

[0034] First, regardless of the amplitude of the rear projection station A No matter how big the image is or where the imaging screen moves, it can still clearly image the earth, thus obtaining clear voxels of uniform size.

[0035] Second, when the quality of the reflector m 2Significantly smaller than the mass of the rear projection station m 1, the force amplitude acting on the frame can be significantly reduced, thereby significantly reducing the counterweight mass of the entire machine.

[0036] The present invention is particularly suitable for accurate display of three-dimensional objects and has broad application prospects in fields involving three-dimensional objects, such as industrial design, scientific research, teaching demonstration, medical CT analysis, and spatial mechanism motion simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the first optical path configuration of the present invention;

[0038] Figure 2 is a schematic diagram of the second optical path configuration of the present invention;

[0039] Figure 3 It is a schematic diagram of an existing suspended rear-projection volume display system;

[0040] Figure 4a It is a front view of the first embodiment of the present invention;

[0041] Figure 4b is a top view of the first embodiment of the present invention;

[0042] Figure 5a It is a front view of the second embodiment of the present invention;

[0043] Figure 5b is a top view of a second embodiment of the present invention;

[0044] Figure 6a It is a front view of the third embodiment of the present invention;

[0045] Figure 6b is a top view of a third embodiment of the present invention;

[0046] Figure 7a It is a front view of a fourth embodiment of the present invention;

[0047] Figure 7b It is a top view of the fourth embodiment of the present invention.

[0048] In the figure: 1. vibration table, 2. first elastic member, 3. reflection table, 4. second elastic member, 5. rear projection table, 6. projector, 7. first reflector, 8. second reflector, 9. imaging screen, 10. imaging area, 11. guide rod, 12. guide cylinder, 13. guide rod, 14. guide cylinder, 15. limit ring. DETAILED DESCRIPTION

[0049] The present invention will be further described below with reference to the accompanying drawings and specific implementations.

[0050] like Figure 1 and Figure 2 As shown. A rear projection table 5 (mass is m 1), the imaging surface is horizontal, through the second elastic member 4 (stiffness coefficient is k1, which may not be a constant), is mounted on a reflector 3 (with a mass of m 2) above; on Figure 1 In the case of , the first reflector 7 is fixedly installed, the second reflector 8 is fixedly connected to the reflecting platform 3, and the reflecting surface is horizontal; Figure 2 In the case of the first reflector 7 and the second reflector 8, the first reflector 7 and the second reflector 8 are at right angles to each other, facing the rear projection stage 5 and fixed to the reflection stage 3; the reflection stage 3 is fixed to the reflection stage 3 by the first elastic member 2 (with a stiffness coefficient of k 2, which may not be a constant), is mounted on a vibration table 1 that can generate vertical vibration (frequency is f 0, the amplitude is e , both are adjustable); when the vibration table 1 is stationary ( e =0), which together constitute a second-order suspension system vibrating in the vertical direction.

[0051] The mass of this second-order suspension system ( m 1 and m 2) and stiffness coefficient ( k 1 and k 2) The system must have a natural mode that vibrates in the vertical direction, and the natural frequency of this mode is f 1 is not less than 10Hz, which can be used as the scanning frequency of the rear projection volume display, the vibration phase of the rear projection stage and the reflection stage is the same, and the amplitude of the rear projection stage is A 1 is the amplitude of the reflection platform A Twice as much as 2 ( A 1=2 A 2).

[0052] When the vibration table vibrates slightly at the natural frequency ( e >0 and f 0= f 1) The suspension system resonates, the natural mode is excited, and the actual amplitude of the mode after stabilization is A 1. A 2. By fine-tuning the amplitude of the vibration table e Take control.

[0053] At the same time, when the light emitted from the fixed projector 6 reaches the moving imaging screen 9 after being reflected by the first reflector 7 and the second reflector 8, the optical path can be kept constant based on the vibration characteristics of the inherent mode, thereby forming a two-dimensional image sequence of different heights but equal size in the imaging area; with the help of the visual persistence effect, these two-dimensional image sequences are superimposed into a clear three-dimensional image for the observer.

[0054] The embodiments of the present invention are as follows:

[0055] Example 1: Embodiment 1 of the present invention, as Figure 4a and Figure 4b shown.

[0056] A reflective platform 3 is suspended obliquely in a nearly horizontal direction on four vibration tables 1 capable of generating vertical vibrations via a first elastic member 2. A first reflector 7 is fixedly mounted facing a second reflector 8. The second reflector 8 is fixedly connected to the reflective platform 3, with its reflective surface facing horizontally upward. The first elastic member 2 is composed of eight tension springs or rubber bands, divided into four groups and symmetrically arranged on the outside of the four corners of the reflective platform 3.

[0057] On the reflection table 3, a rear projection table 5 is suspended in a nearly horizontal direction by a second elastic member 4. The imaging screen 9 is fixedly connected to the rear projection table 5, and the imaging surface is horizontal. The second elastic member 4 is composed of eight tension springs or rubber bands, which are divided into four groups and symmetrically arranged on the outside of the four corners of the rear projection table 5.

[0058] The light emitted from the projector 6 is reflected by the first reflector 7 and the second reflector 8 and then projected onto the imaging screen 9 to form a volume display.

[0059] The combination of four parameters, namely the stiffness coefficient of the first elastic member 2, the stiffness coefficient of the second elastic member 4, the mass of the reflecting table 3 and the mass of the rear projection table 5, ensures that the system has a natural mode of vibration in the vertical direction, the natural frequency of which is not less than 10 Hz, the vibration phases of the rear projection table 5 and the reflecting table 3 are the same, and the amplitude of the rear projection table 5 is twice the amplitude of the reflecting table 3, thereby keeping the optical path of the rear projection volume display constant; the vibration table 1 vibrates slightly in the vertical direction, and the vibration frequency and amplitude are adjustable. When the actual vibration frequency of the vibration table 1 is consistent with the natural frequency, the system resonates, the vibration of the natural mode is excited, and the rear projection table 5 and the reflecting table 3 vibrate significantly. The actual amplitude is controlled by fine-tuning the amplitude of the vibration table 1.

[0060] Example 2: Implementation method 2 of the present invention, as Figure 5a and Figure 5b shown.

[0061] A reflector 3 is suspended diagonally in a nearly horizontal direction on four vibration tables 1 capable of generating vertical vibrations via first elastic members 2. A first reflector 7 and a second reflector 8 are fixedly attached to the reflector 3 at right angles, facing the rear projection stage 5. The first elastic members 2 are composed of eight tension springs or rubber bands arranged in four groups on the outside of the four corners of the reflector 3.

[0062] On the reflection table 3, a rear projection table 5 is suspended in a nearly horizontal direction by a second elastic member 4. The imaging screen 9 is fixedly connected to the rear projection table 5, and the imaging surface is horizontal. The second elastic member 4 is composed of eight tension springs or rubber bands, which are divided into four groups and symmetrically arranged on the outside of the four corners of the rear projection table 5.

[0063] The light emitted from the projector 6 is reflected by the first reflector 7 and the second reflector 8 and then projected onto the imaging screen 9 to form a volume display.

[0064] The combination of four parameters, namely the stiffness coefficient of the first elastic member 2, the stiffness coefficient of the second elastic member 4, the mass of the reflecting table 3 and the mass of the rear projection table 5, ensures that the system has a natural mode of vibration in the vertical direction, the natural frequency of which is not less than 10 Hz, the vibration phases of the rear projection table 5 and the reflecting table 3 are the same, and the amplitude of the rear projection table 5 is twice the amplitude of the reflecting table 3, thereby keeping the optical path of the rear projection volume display constant; the vibration table 1 vibrates slightly in the vertical direction, and the vibration frequency and amplitude are adjustable. When the actual vibration frequency of the vibration table 1 is consistent with the natural frequency, the system resonates, the vibration of the natural mode is excited, and the rear projection table 5 and the reflecting table 3 vibrate significantly. The actual amplitude is controlled by fine-tuning the amplitude of the vibration table 1.

[0065] Example 3: Embodiment 3 of the present invention, as Figure 6a and Figure 6b shown.

[0066] On four vibration tables 1 that can generate vibrations in the vertical direction, a reflection table 3 is suspended in the vertical direction through a first elastic member 2. The first reflector 7 faces the second reflector 8 and is fixedly installed. The second reflector 8 is fixedly connected to the reflection table 3, and the reflection surface is horizontally upward; the first elastic member 2 is composed of four components and is symmetrically arranged on the outside of the four corners of the reflection table 3. Each component is composed of two compression springs or rubbers, which are inserted outside the guide rod 11 and inside the guide cylinder 12, and are confined between the two end faces of the guide cylinder 12 and the limit ring 15; the guide rod 11 is installed vertically and extends from the open end below the guide cylinder 12 to be fixedly connected to the vibration table 1. Two position-adjustable limit rings 15 are installed on the guide rod 11, and the open end of the guide cylinder 12 is fixedly connected to the reflection table 3 downward.

[0067] On the reflection table 3, a rear projection table 5 is suspended vertically via a second elastic member 4, with an imaging screen 9 fixedly connected to the rear projection table 5, and the imaging surface is horizontal. The second elastic member 4 is composed of four components different from the first elastic member 2 and is symmetrically arranged on the outside of the four corners of the rear projection table 5. Each component is composed of two compression springs or rubbers, which are inserted outside the guide rod 13 and inside the guide cylinder 14 and are confined between the two end surfaces of the guide cylinder 14 and the limit ring 15. The guide rod 13 is installed vertically and extends from the open end above the guide cylinder 14 to be fixedly connected to the rear projection table 5. Two position-adjustable limit rings 15 are installed on the guide rod 13. The open end of the guide cylinder 14 is fixedly connected to the reflection table 3 upward.

[0068] The light emitted from the projector 6 is reflected by the first reflector 7 and the second reflector 8 and then projected onto the imaging screen 9 to form a volume display.

[0069] The combination of four parameters, namely the stiffness coefficient of the first elastic member 2, the stiffness coefficient of the second elastic member 4, the mass of the reflecting table 3 and the mass of the rear projection table 5, ensures that the system has a natural mode of vibration in the vertical direction, the natural frequency of which is not less than 10 Hz, the vibration phases of the rear projection table 5 and the reflecting table 3 are the same, and the amplitude of the rear projection table 5 is twice the amplitude of the reflecting table 3, thereby keeping the optical path of the rear projection volume display constant; the vibration table 1 vibrates slightly in the vertical direction, and the vibration frequency and amplitude are adjustable. When the actual vibration frequency of the vibration table 1 is consistent with the natural frequency, the system resonates, the vibration of the natural mode is excited, and the rear projection table 5 and the reflecting table 3 vibrate significantly. The actual amplitude is controlled by fine-tuning the amplitude of the vibration table 1.

[0070] Example 4: Embodiment 4 of the present invention, as Figure 7a and Figure 7b shown.

[0071] A reflecting table 3 is vertically suspended on four vibration tables 1 capable of generating vertical vibrations, via a first elastic member 2. A first reflector 7 and a second reflector 8 are arranged at right angles, facing the rear projection table 5, and fixedly connected to the reflecting table 3. The first elastic member 2 is composed of four components and is symmetrically arranged outside the four corners of the reflecting table 3. Each component is composed of two compression springs or rubbers, which are inserted outside the guide rod 11 and inside the guide cylinder 12 and are confined between the two end surfaces of the guide cylinder 12 and a limit ring 15. The guide rod 11 is vertically installed and extends from the open end below the guide cylinder 12 to be fixedly connected to the vibration table 1. Two position-adjustable limit rings 15 are installed on the guide rod 11. The open end of the guide cylinder 12 is fixedly connected downward to the reflecting table 3.

[0072] On the reflection table 3, a rear projection table 5 is suspended vertically via a second elastic member 4, with an imaging screen 9 fixedly connected to the rear projection table 5, and the imaging surface is horizontal. The second elastic member 4 is composed of four components different from the first elastic member 2 and is symmetrically arranged on the outside of the four corners of the rear projection table 5. Each component is composed of two compression springs or rubbers, which are inserted outside the guide rod 13 and inside the guide cylinder 14 and are confined between the two end surfaces of the guide cylinder 14 and the limit ring 15. The guide rod 13 is installed vertically and extends from the open end above the guide cylinder 14 to be fixedly connected to the rear projection table 5. Two position-adjustable limit rings 15 are installed on the guide rod 13. The open end of the guide cylinder 14 is fixedly connected to the reflection table 3 upward.

[0073] The light emitted from the projector 6 is reflected by the first reflector 7 and the second reflector 8 and then projected onto the imaging screen 9 to form a volume display.

[0074] The combination of four parameters, namely the stiffness coefficient of the first elastic member 2, the stiffness coefficient of the second elastic member 4, the mass of the reflecting table 3 and the mass of the rear projection table 5, ensures that the system has a natural mode of vibration in the vertical direction, the natural frequency of which is not less than 10 Hz, the vibration phases of the rear projection table 5 and the reflecting table 3 are the same, and the amplitude of the rear projection table 5 is twice the amplitude of the reflecting table 3, thereby keeping the optical path of the rear projection volume display constant; the vibration table 1 vibrates slightly in the vertical direction, and the vibration frequency and amplitude are adjustable. When the actual vibration frequency of the vibration table 1 is consistent with the natural frequency, the system resonates, the vibration of the natural mode is excited, and the rear projection table 5 and the reflecting table 3 vibrate significantly. The actual amplitude is controlled by fine-tuning the amplitude of the vibration table 1.

Claims

1. A suspended rear-projection volumetric display system with a constant optical path, characterized by: The invention comprises a vibration table (1), a first elastic member (2), a reflection table (3), a second elastic member (4), a rear projection table (5), a projector (6), a first reflector (7), a second reflector (8) and an imaging screen (9); the vibration table (1), the reflection table (3) and the rear projection table (5) are arranged in sequence from bottom to top in a vertical direction, the vibration table (1) is fixedly installed, the reflection table (3) is elastically connected to the vibration table (1) through the first elastic member (2), and the second reflector (8) is fixed on the reflection table (3) and faces the rear projection screen. The projection platform (5) and the rear projection platform (5) are elastically connected to the reflection platform (3) via a second elastic member (4); the imaging screen (9) is fixedly connected to the rear projection platform (5); and the imaging surface is horizontal; the projection light emitted from the fixedly installed projector (6) is reflected by the first reflector (7) and the second reflector (8) in sequence, and is irradiated from the rear side of the rear projection platform (5) to the imaging screen (9), and an image is formed on the front side of the imaging screen (9); the vibration range of the imaging screen (9) is used as the imaging area (10), and rear projection volume display is performed; The combination of the four parameters of the stiffness coefficient of the first elastic member (2), the stiffness coefficient of the second elastic member (4), the mass of the reflection table (3) and the mass of the rear projection table (5) enables the system to have a natural mode that vibrates in the vertical direction, the natural frequency of the natural mode is not less than 10 Hz, the vibration phases of the rear projection table (5) and the reflection table (3) are the same and the amplitude of the rear projection table (5) is twice the amplitude of the reflection table (3), thereby keeping the optical path of the rear projection volume display system constant.

2. The suspended rear-projection volumetric display system with a constant optical path according to claim 1, characterized in that: The second reflector (8) is horizontally fixed to a side surface of the reflection platform (3) facing the rear projection platform (5), and the first reflector (7) faces the second reflector (8) and is fixedly installed.

3. The suspended rear-projection volumetric display system with a constant optical path according to claim 1, characterized in that: The first reflector (7) and the second reflector (8) are arranged at a right angle to each other, and the first reflector (7) and the second reflector (8) are arranged toward the rear projection table (5) and are both fixedly connected to the reflection table (3).

4. The suspended rear-projection volumetric display system with a constant optical path according to claim 1, characterized in that: The first elastic member (2) and the second elastic member (4) are tension springs or rubber bands, or compression springs or rubber.

5. The suspended rear-projection volumetric display system with a constant optical path according to claim 1, characterized in that: The vibration table (1) is composed of 2 to 8 vibrators with the same phase and amplitude connected in parallel; The first elastic member (2) is composed of 2 to 8 parallel tension springs or rubber bands and arranged symmetrically, one end of the tension spring or rubber band is hung on the vibration table (1), and after being pulled obliquely in a substantially horizontal direction, the other end is hung on the reflection table (3); The second elastic member (4) is composed of 2 to 8 tension springs or rubber bands that are different from the first elastic member (2) and are connected in parallel and arranged symmetrically. One end of the tension spring or rubber band is hung on the reflection table (3), and after being pulled obliquely in a roughly horizontal direction, the other end is hung on the rear projection table (5).

6. The suspended rear-projection volumetric display system with a constant optical path according to claim 1, characterized in that: The first elastic member (2) and the second elastic member (4) have the same structure and both include a guide rod, a guide cylinder and a limit ring (15). The guide cylinder is fixed to the reflection table (3). The guide rod is movably sleeved in the guide cylinder. Two springs are sleeved on the outer surface of the guide rod sleeved in the guide cylinder. An outer flange is provided on the outer peripheral surface of the guide rod between the two springs as a position-adjustable limit ring (15). One end of the two springs is connected to the limit ring (15), and the other end is connected to the two ends inside the guide cylinder. One end of the guide rod extends out of the guide cylinder and is fixedly connected to the rear projection table (5) or the vibration table (1).

7. A rear projection volumetric display method applied to the suspended rear projection volumetric display system with a constant optical path according to any one of claims 1 to 6, characterized in that: The vibration table (1) generates vibration in the vertical direction, which is transmitted to the reflection table (3) through the first elastic member (2), and then transmitted to the rear projection table (5) through the second elastic member (4), generating resonance. The rear projection table (5) and the reflection table (3) generate relative vibration in the vertical direction under the action of the first elastic member (2) and the second elastic member (4), so that the optical path from the projector (6) to the imaging screen (9) remains constant after being reflected by the first reflector (7) and the second reflector (8), and the vibration range of the imaging screen (9) is used as the imaging area (10) to perform rear projection volume display.

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