Three-dimensional projection teaching equipment for history teaching and projection system thereof

Abstract

The invention relates to the technical field of projection sand tables, in particular to three-dimensional projection teaching equipment for history teaching and a projection system thereof.The equipment comprises an outer frame, supporting legs installed on the outer frame and a control box, a distant view disc is arranged in the outer frame, a jacking air cylinder is installed in the middle of the supporting legs, and a top seat is arranged at the top end of the jacking air cylinder; evolution discs are detachably assembled on the top seat and comprise a city evolution disc and a water system evolution disc; a plurality of circles of annularly distributed guide frames are arranged on the upper surface of the urban evolution disc, liftable building blocks are slidably mounted in the guide frames, an annular rail is arranged in the urban evolution disc and corresponds to the lower portion of each circle of annularly distributed guide frame, and at least one annular sliding seat is mounted on each annular rail in a driving manner. A jacking mechanism capable of jacking the building block upwards is arranged on the annular sliding seat; a water system bottom plate is embedded in the water system evolution disc, and riverbed blocks for limiting lifting are arranged on the water system bottom plate in an array mode; and the history teaching projection content can be more vivid.

Description

Technical Field

[0001] This invention relates to the field of projection sand table technology, specifically to a three-dimensional projection teaching device and its projection system for history teaching. Background Technology

[0002] 3D projection teaching equipment combines virtual 3D images with physical models or scenes to provide students with an immersive and interactive learning experience. In history teaching, such equipment is often used to demonstrate the layout of ancient cities, battle terrain, and the dynamic processes of civilizational change, effectively compensating for the shortcomings of traditional two-dimensional images and oral narration in terms of spatial representation and intuitiveness. Existing 3D projection teaching equipment mostly adopts a fixed terrain sand table combined with upper projection, projecting pre-made 3D animations onto the sand table surface to demonstrate changes in terrain and landforms.

[0003] However, existing 3D projection teaching equipment still has significant shortcomings: First, its sand table terrain is mostly a static structure, unable to adjust the terrain undulations or building layout in real time according to the teaching content, lacking the ability to dynamically change entities, resulting in monotonous demonstration content and difficulty in vividly representing dynamic processes such as changes in building density and river course changes during historical evolution; Second, existing equipment often relies on complex mechanical structures or manual intervention to achieve limited movements, with slow response speed, low positioning accuracy, and difficulty in achieving independent control of multiple units, failing to meet the demonstration needs of high-frequency, multi-point synchronous changes, and failing to achieve linkage between light and shadow and physical structures, resulting in insufficient realism and interactivity in teaching demonstrations; Finally, most equipment lacks modular design, requiring the replacement of the entire sand table for different teaching scenarios, making operation cumbersome and costly. Summary of the Invention

[0004] The purpose of this invention is to provide a three-dimensional projection teaching device and its projection system for history teaching, so as to make the projected content of history teaching more vivid and graphic, and to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a three-dimensional projection teaching device for history teaching, comprising an outer frame, support legs installed on the outer frame, and a control box, wherein a viewing disk is provided inside the outer frame, a lifting cylinder is installed in the middle of the support legs, and a top seat is provided at the top of the lifting cylinder; The top base is detachably equipped with evolution panels, which include urban evolution panels and water system evolution panels; The upper surface of the urban evolution plate is provided with multiple ring-shaped guide frames. Liftable building blocks are slidably installed inside the guide frames. Inside the urban evolution plate, there is a ring rail below each ring-shaped guide frame. At least one ring slide is driven and installed on the ring rail. The ring slide is provided with a lifting mechanism that can lift the building blocks upward. A water system base plate is embedded in the water system evolution plate. The water system base plate is arrayed with limit lifting riverbed blocks. The bottom of the riverbed blocks is equipped with a bottom frame. The bottom surface of the water system base plate is equipped with a straight rail. A straight slide is driven and installed on the straight rail. The straight slide is equipped with a push rod group that can press down the bottom frame to make the riverbed blocks sink. The control box is electrically connected to the lifting mechanism, push rod assembly, circular rail and linear rail drive mechanism to control the lifting of building blocks and the settling of riverbed blocks, so as to cooperate with the projection system to form a dynamic three-dimensional demonstration effect on the sand table surface.

[0006] Preferably, the lifting mechanism includes a guide cylinder fixedly installed on an annular slide, a top rod movably installed inside the guide cylinder, and a magnetic end block provided at the bottom end of the top rod; An electromagnetic base is installed at the bottom of the guide tube. When the electromagnetic base is energized, it generates a magnetic repulsive force that drives the magnetic end block and the push rod to rise.

[0007] Preferably, a limiting spring is provided between the magnetic end block and the inner wall of the guide cylinder.

[0008] Preferably, the inner wall of the guide frame is provided with a damping structure to keep the building block in position without external force.

[0009] Preferably, the side of the bottom frame is connected to a rubber rope, and the other end of the rubber rope is connected to the bottom surface of the water system base plate to provide the riverbed block with a restoring elastic force.

[0010] Preferably, a trapezoidal block is fixedly installed inside the bottom frame, and the push rod assembly drives the bottom frame and the riverbed block to move downward by squeezing the trapezoidal block.

[0011] Preferably, the push rod assembly consists of two electrically driven push rods arranged in opposite directions.

[0012] Preferably, the top seat is provided with a limiting hole, and the bottom of the evolution plate is provided with an assembly seat. The assembly seat is provided with a retractable inclined pin. The connection and locking between the evolution plate and the top seat are realized by the cooperation of the inclined pin and the limiting hole.

[0013] Preferably, the bottom of the evolution plate is equipped with a plug and the support foot is equipped with a socket. When the evolution plate is lowered to the working position, the plug and the socket are connected to realize power supply and signal transmission.

[0014] A projection system for a 3D projection teaching device includes: At least one projector is installed above the outer frame of the teaching equipment to project dynamic light and shadow images onto the surface of the viewing disk and the evolution disk of the teaching equipment; The image processing unit is located in the control box of the teaching equipment and is connected to the projector signal. It is used to generate or call up three-dimensional animations of terrain, building and water system changes. The control module, integrated in the control box, is electrically connected to the image processing unit, the lifting mechanism of the teaching equipment, the push rod group, the ring rail and the linear rail drive mechanism. It is used to receive control commands and coordinate the projection content of the projector to change synchronously with the lifting and lowering movements of the building blocks and riverbed blocks. The software system runs on the touchscreen interface of the control box, providing a graphical user interface for selecting historical period parameters and controlling the demonstration process. This allows the projected content to be matched in real time with the dynamic changes of the physical model, creating a fused 3D demonstration effect.

[0015] Compared with existing technologies, the beneficial effects of this invention are as follows: Through a projection sand table structure that can dynamically change the terrain, combined with high-precision controlled building modules and riverbed modules, a vivid and three-dimensional demonstration of urban changes and water system evolution in historical teaching is achieved; utilizing a circular and linear rail drive system in conjunction with electromagnetic lifting and electric push rod mechanisms, the lifting and lowering of individual building blocks or riverbed blocks can be precisely controlled, simulating changes in building density and river morphology during different historical periods; through modularly designed urban evolution and water system evolution panels, which can be quickly replaced and stably installed on the lifting cylinder, combined with the dynamic light and shadow effects of the projection system, a deep integration of physical models and virtual projection is achieved, significantly enhancing the intuitiveness, interactivity, and interest of historical teaching, enabling students to more deeply understand the relationship between historical geographical changes and human activities. Attached Figure Description Figure 1 This is a first schematic diagram of the overall structure of the sand table of the present invention.

[0016] Figure 2 This is a second schematic diagram of the overall structure of the sand table of the present invention.

[0017] Figure 3 This is a schematic diagram of the urban evolution disk of the present invention in its raised state.

[0018] Figure 4 This is a schematic diagram of the outer frame structure of the present invention.

[0019] Figure 5 This is a schematic diagram of the external structure of the urban evolution disk of the present invention.

[0020] Figure 6 This is a schematic diagram of the bottom structure of the urban evolution disk of the present invention.

[0021] Figure 7 This is a schematic diagram of the installation of the annular rail structure of the present invention.

[0022] Figure 8 This is a schematic diagram of the annular slide and guide cylinder structure of the present invention.

[0023] Figure 9 This is a schematic diagram of the internal structure of the guide tube of the present invention.

[0024] Figure 10 This is a schematic diagram of the building module structure of the present invention.

[0025] Figure 11 This is a schematic diagram of the external structure of the water system evolution plate of the present invention.

[0026] Figure 12 This is a schematic diagram of the water system base plate structure of the present invention.

[0027] Figure 13 This is a schematic diagram of the combined state of the riverbed module of the present invention.

[0028] Figure 14 This is a schematic diagram of the riverbed module structure of the present invention.

[0029] Figure 15 This is a schematic diagram of the linear rail and linear slide structure of the present invention.

[0030] Figure 16 This is a schematic diagram of the internal structure of the assembly base of the present invention.

[0031] In the diagram: 1. Outer frame; 2. Support leg; 3. Control box; 4. Vision panel; 5. Lifting cylinder; 6. Top seat; 7. Urban evolution panel; 8. Waterway channel; 9. Guide frame; 10. Building block; 11. Circular rail; 12. Circular slide; 13. Guide cylinder; 14. Top rod; 15. Magnetic end block; 16. Limiting spring; 17. Electromagnetic seat; 18. Water system evolution panel; 19. Water system base plate; 20. Riverbed block; 21. Bottom frame; 22. Rubber rope; 23. Trapezoidal block; 24. Linear rail; 25. Linear slide; 26. Push rod assembly; 27. Limiting hole; 28. Assembly seat; 29. ​​Reset guide rod; 30. Pressure seat; 31. Control board; 32. Pressure rod; 33. Reset guide groove; 34. Angled pin; 35. Plug; 36. Socket. Detailed Implementation

[0032] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. It should be understood that the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] Please see Figures 1 to 16 The present invention provides a technical solution: a three-dimensional projection teaching device for history teaching, which is a projection sand table that can change the terrain as needed. By changing the terrain and combining it with light and shadow effects, a more vivid and graphic demonstration effect can be achieved, making history teaching more interesting.

[0034] like Figure 1 , Figure 2 As shown, the three-dimensional projection teaching equipment includes a base structure consisting of an outer frame 1, support legs 2, and a control box 3. The outer frame 1 is a ring structure, and the support legs 2 are installed at the bottom of the outer frame 1 by bolts. The support legs 2 can support the outer frame 1. The control box 3 is located on one side of the outer frame 1 and the support legs 2. The control box 3 adopts a full touch screen structure and can control the projection sand table and the matching projector.

[0035] like Figure 3 As shown, the inner ring of the outer frame 1 is provided with a ring-shaped distant view disk 4. The distant view disk 4 is fixed to the support foot 2 by bolts. The coastline or distant mountain model is set on the distant view disk 4. They are all statically arranged and are mainly used to shape the outline of distant mountains, plateaus and continental coastlines.

[0036] like Figure 4 As shown, a lifting cylinder 5 is fixedly mounted in the middle of the support leg 2. A top seat 6 is installed at the top of the telescopic rod of the lifting cylinder 5 by welding. The central sand table is assembled through the top seat 6.

[0037] The central sand table is divided into two types: the urban evolution panel 7 and the water system evolution panel 18, which have the same basic structure.

[0038] like Figures 5-7 As shown, the city evolution disk 7 has a water channel 8 on its disk body. The water channel 8 is a curved groove in the middle of the disk body. Multiple sets of building modules are set on both sides of the water channel 8. These building modules are distributed on the multiple ring tracks 11 of the city evolution disk 7. The radius of the ring tracks 11 on the city evolution disk 7 increases at equal intervals from the inside to the outside. The distribution of building modules on the city evolution disk 7 can simulate the distribution of city buildings.

[0039] like Figure 10 As shown, the building module consists of a guide frame 9 and building blocks 10. The guide frame 9 is fixed to the upper surface of the urban evolution disk 7 by an inlay installation method and is distributed and installed according to the circular track 11. The building blocks 10 are slidably installed in the guide frame 9. The inner wall of the guide frame 9 is provided with damping, and the damping structure is a rubber coating on the inner wall of the guide frame 9, which is used to increase the friction between the building blocks 10 and the guide frame 9. Therefore, when the building blocks 10 are not subjected to external force, they can be self-positioned in the guide frame 9. The density change of buildings during the urban transformation process is simulated by the rise and fall of the building blocks 10 in the guide frame 9. It can be demonstrated in conjunction with the light and shadow changes of the projector. Before the formal demonstration, all the building blocks 10 can be manually pressed to the bottom of the guide frame 9 to show the state without buildings.

[0040] like Figure 7As shown, further, the interior of the city evolution disk 7 is equipped with multiple circular tracks 11. The circular tracks 11 follow the same path as the aforementioned circular tracks 11. The circular tracks 11 are located below the concentric building modules. The circular tracks 11 are driven by high-power servo motors via synchronous belts. These servo motors are equipped with high-precision encoders. Circular slide blocks 12 are installed in the circular tracks 11 and are driven by synchronous belts. Each circular track 11 has at least one circular slide block 12. Multiple circular slide blocks 12 can be segmented on the large-sized circular tracks 11 for rapid response. In addition, origin sensors and absolute encoders are installed on the circular tracks 11. Each circular slide block 12 has a unique ID, which can be identified via RFID. Therefore, the circular tracks 11 can move the circular slide blocks 12 directly under a specific individual building module.

[0041] like Figure 8 , Figure 9 As shown, the top of the annular slide block 12 is equipped with a lifting mechanism, which can lift the building block 10 of the upper building module when needed, so as to simulate the construction of the building.

[0042] The lifting mechanism includes a guide cylinder 13 mounted on an annular slide block 12 by screws. A top rod 14 is movably mounted inside the guide cylinder 13. A magnetic end block 15 is fitted at the bottom of the top rod 14, and a limit spring 16 is mounted on the magnetic end block 15 by a pin. The other end of the limit spring 16 is fixed to the inner wall of the guide cylinder 13 by a pin. At the same time, an electromagnetic seat 17 is assembled at the bottom of the guide cylinder 13. When the electromagnetic seat 17 receives a control signal, it can be energized to generate a magnetic repulsion force, which causes the magnetic end block 15 and the top rod 14 to rise against the elastic force of the limit spring 16. The top rod 14 lifts the building block 10 from the bottom and makes it protrude from the city demonstration panel.

[0043] like Figure 11 As shown, a water system base plate 19 is embedded in the water system evolution plate 18. A pixel-like waterway change simulation mechanism is set on the water system base plate 19. Through the corresponding settlement of multiple riverbed blocks 20 on the water system base plate 19, combined with the light and shadow changes of the projector, the changes in the riverbed and the changes in human activities are demonstrated, guiding students to understand the relationship between river changes and urban changes.

[0044] like Figure 12 As shown, the riverbed blocks 20 array is set on the water system bottom plate 19, and the limiting lifting of the riverbed blocks 20 is installed in the limiting guide groove of the water system bottom plate 19. A bottom frame 21 is integrally formed at the bottom of the riverbed blocks 20. The lifting and lowering of the riverbed blocks 20 can be controlled through the bottom frame 21. Therefore, by changing the lifting and lowering of adjacent riverbed blocks 20, scenarios such as river diversion and embankment breach can be simulated.

[0045] like Figure 13 , Figure 14As shown, the bottom frame 21 has a U-shaped structure and is set through the bottom surface of the water system base plate 19. The side of the bottom frame 21 is glued with a rubber rope 22, which provides elasticity. The other end of the rubber rope 22 is glued to the bottom surface of the water system base plate 19. When there is no external force, the elasticity of the rubber rope 22 can keep the riverbed block 20 at the same height as the water system evolution plate 18. A trapezoidal block 23 is fixedly installed in the bottom frame 21 with screws. The bottom frame 21 and the riverbed block 20 are moved down by pressing the trapezoidal block 23 from the side.

[0046] like Figure 15 As shown, the control mechanism of the riverbed block 20 is located on the bottom surface of the water system base plate 19. It includes a linear rail 24 fixed to the water system base plate 19 by screws. The linear rail 24 is inserted into the same row of bottom frames 21. A linear slide block 25 is driven and installed on the linear rail 24. The linear rail 24 is also driven by a high-power servo motor through a synchronous belt. The servo motor is equipped with a high-precision encoder and is also equipped with an origin sensor and an absolute encoder. The linear slide block 25 has a unique ID, which can be identified by RFID. Therefore, the linear rail 24 can drive the linear slide block 25 to move directly below the specific individual riverbed block 20 and directly above the bottom frame 21.

[0047] like Figure 14 , Figure 15 As shown, a push rod assembly 26 is installed on the linear slide 25 by screws. The push rod assembly 26 is composed of two opposing electric push rod assemblies 26. When the linear slide 25 moves the push rod assembly 26 above a certain bottom frame 21, the electric push rod itself can squeeze the trapezoidal block 23, causing it to move the bottom frame 21 and the riverbed block 20 downward. This riverbed block 20 is the center position of the river channel. Furthermore, the electric push rod can extend, and the bottom frames 21 on both sides can be pressed down by the electric push rod to achieve the demonstration effect of widening the river channel.

[0048] like Figures 11-15 As shown, the dense array of riverbed blocks 20 is set on the water system base plate 19, similar to pixel blocks. A straight rail 24 controls the riverbed blocks 20 in the same row, and each column is set with a separate straight rail 24 for control. As adjacent riverbed blocks 20 descend, a structure approximating the direction of the river is formed. Combined with the changes in light and shadow of the projector, a three-dimensional demonstration effect is achieved. At the same time, the movement of the linear slide block 25 and the push rod group 26 driven by the straight rail 24, as well as the extension and retraction of the electric push rod in the push rod group 26, can control the specific lifting and lowering movements of a single riverbed block 20, forming a demonstration of changes in the river topography.

[0049] Depending on the specific needs of history teaching, the city evolution panel 7 and the water system evolution panel 18 can be replaced.

[0050] like Figure 4 , Figure 6As shown, a limiting hole 27 is provided on the top seat 6. The city evolution disk 7 and the water system evolution disk 18 are of the same size. Furthermore, both of them are provided with the same assembly base 28 at their bottom. The assembly base 28 can be quickly connected to the limiting hole 27, thereby fixing the evolution disk on the lifting cylinder 5. When the lifting cylinder 5 raises the evolution disk, it can be disassembled and installed. When the lifting cylinder 5 lowers the evolution disk, the evolution disk can be fitted into the vision disk 4. The two form a complete disc structure for projection demonstration.

[0051] like Figure 16 As shown, a reset guide rod 29 is vertically arranged inside the assembly base 28. A reset spring is installed on the reset guide rod 29, and a pressure seat 30 is movably sleeved on the reset guide rod 29. The reset spring can restrict the pressure seat 30 to the lower part of the guide rod. At the same time, a control plate 31 is welded and fixed on the pressure seat 30. The control plate 31 is located outside the assembly base 28, and thus drives the pressure seat 30 to move up and down from the outside through the control plate 31. Furthermore, horizontal pressure rods 32 are welded and fixed on both sides of the pressure seat 30. A horizontal reset guide groove 33 is provided at the bottom of the assembly base 28. An elastic rope is installed in the reset guide groove 33, and a slanted pin 34 is slidably installed in the reset guide groove 33 for limiting. The slanted pin 34 is kept in the retracted state by the elastic rope, and when the pressure seat 30 is in the retracted state... When pressed down, the pressure rod 32 acts on the inclined pin 34, causing its end to extend out from the assembly base 28 and be inserted into the limiting hole 27 of the top seat 6 for connection. This connects the assembly base 28 with the top seat 6, allowing the evolution plate to move with the top seat 6 without easily shifting. The spring force generated by the return spring is more than twice that of the elastic rope, thus the inclined pin 34 can be pressed out of the assembly base 28 by the pressure seat 30. When the evolution plate needs to be disassembled and replaced, the pressure seat 30 is raised by the control plate 31, allowing the inclined pin 34 to retract. Since the control plate 31 is located below the evolution plate, the lifting of the control plate 31 can be performed simultaneously with the lifting of the evolution plate, making it easier to operate and preventing damage to the evolution plate.

[0052] like Figures 3-6 As shown, plugs 35 are provided at the bottom of both the urban evolution plate 7 and the water system evolution plate 18, while sockets 36 are provided on the support feet 2. When the urban evolution plate 7 and the water system evolution plate 18 are lowered and fitted into the distant view plate 4, the plugs 35 can be inserted into the sockets 36 to complete the power connection and signal access. The control box 3 is electrically connected to the lifting mechanism, the push rod group 26, the ring rail 11 and the linear rail 24 drive mechanism, so that the building blocks 10 on the urban evolution plate 7 and the riverbed blocks 20 on the water system evolution plate 18 can be controlled through the control box 3, so as to cooperate with the projection system to form a dynamic three-dimensional demonstration effect on the surface of the sand table.

[0053] A projection system is also included to work in conjunction with the aforementioned 3D projection teaching equipment, projecting dynamic light and shadow effects onto the sand table surface to enhance the visual representation of historical and geographical changes. The projection system includes projection equipment, an image processing unit, a control module, and supporting software.

[0054] The projection equipment includes at least one high-lumen projector, typically a laser light source projector, which is suspended above the outer frame 1 to ensure that the projection area covers the entire surface of the sand table, including the distant view panel 4, the urban evolution panel 7, or the water system evolution panel 18. The projector resolution is no less than 1920×1080, and it supports vertical correction and edge blending functions to adapt to the curved surfaces and multi-layered structures of the sand table.

[0055] The image processing unit is integrated into control box 3, including a graphics processor, memory, and storage devices. It comes pre-installed with 3D modeling and animation rendering software, capable of generating or calling preset animations of historical landforms, buildings, and water system changes in real time. The image processing unit connects to the projector via HDMI or DP interfaces, supports multi-channel output, and can achieve regional and layered projection.

[0056] The control module includes a main controller and multiple sub-controllers. The main controller is embedded in the control box 3 and communicates with the servo motors, electromagnetic bases 17, electric push rods, and other actuators in the city evolution panel 7 and water system evolution panel 18 via CAN bus or Ethernet to achieve synchronized movement between the projected content and the physical model. For example, when building block 10 is lifted, the projector will project a three-dimensional light and shadow effect of the building in that area; when riverbed block 20 descends to form a river channel, the projection will display a water flow animation.

[0057] The accompanying software system runs on the touchscreen interface of control box 3, providing a graphical user interface that allows teachers to select landforms and urban forms from different historical periods. The software automatically calls up the corresponding 3D models and animation sequences, and controls the presentation progress via a timeline. The system also supports manual intervention, allowing teachers to adjust the building density or river course of a specific area in real time, and the projected content will update dynamically accordingly.

[0058] To further enhance the immersive experience, the projection system can also integrate an ambient light sensor and automatic brightness adjustment function to ensure clear display of projected content under different lighting conditions. In addition, the system supports integration with external multimedia devices, such as speakers and electronic whiteboards, to achieve integrated audio-visual teaching demonstrations.

[0059] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure based on the specific circumstances. Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A three-dimensional projection teaching device for history teaching, comprising an outer frame, support legs mounted on the outer frame, and a control box, characterized in that: The outer frame contains a viewing plate, and the middle of the support leg is equipped with a lifting cylinder, with a top seat at the top of the lifting cylinder. The top base is detachably equipped with evolution panels, which include urban evolution panels and water system evolution panels; The upper surface of the urban evolution plate is provided with multiple ring-shaped guide frames. Liftable building blocks are slidably installed inside the guide frames. Inside the urban evolution plate, there is a ring rail below each ring-shaped guide frame. At least one ring slide is driven and installed on the ring rail. The ring slide is provided with a lifting mechanism that can lift the building blocks upward. A water system base plate is embedded in the water system evolution plate. The water system base plate is arrayed with limit lifting riverbed blocks. The bottom of the riverbed blocks is equipped with a bottom frame. The bottom surface of the water system base plate is equipped with a straight rail. A straight slide is driven and installed on the straight rail. The straight slide is equipped with a push rod group that can press down the bottom frame to make the riverbed blocks sink. The control box is electrically connected to the lifting mechanism, push rod assembly, circular rail and linear rail drive mechanism to control the lifting of building blocks and the settling of riverbed blocks, so as to cooperate with the projection system to form a dynamic three-dimensional demonstration effect on the sand table surface.

2. The three-dimensional projection teaching device for history teaching according to claim 1, characterized in that: The lifting mechanism includes a guide cylinder fixedly installed on the annular slide block, a top rod movably installed inside the guide cylinder, and a magnetic end block provided at the bottom end of the top rod; The bottom of the guide tube is equipped with an electromagnetic base. When the electromagnetic base is energized, it generates a magnetic repulsive force to drive the magnetic end block and the top rod to rise.

3. The three-dimensional projection teaching device for history teaching according to claim 2, characterized in that: A limiting spring is provided between the magnetic end block and the inner wall of the guide cylinder.

4. The three-dimensional projection teaching device for history teaching according to claim 1, characterized in that: The inner wall of the guide frame is provided with a damping structure to keep the building block in position without external force.

5. A three-dimensional projection teaching device for history teaching according to claim 1, characterized in that: A rubber rope is connected to the side of the bottom frame, and the other end of the rubber rope is connected to the bottom surface of the water system base plate to provide the riverbed block with a restoring elastic force.

6. A three-dimensional projection teaching device for history teaching according to claim 5, characterized in that: A trapezoidal block is fixedly installed inside the bottom frame, and the push rod assembly moves the bottom frame and the riverbed block downward by squeezing the trapezoidal block.

7. A three-dimensional projection teaching device for history teaching according to claim 1, characterized in that: The push rod assembly consists of two electrically driven push rods arranged in opposite directions.

8. A three-dimensional projection teaching device for history teaching according to claim 1, characterized in that: The top seat is provided with a limiting hole, and the bottom of the evolution plate is provided with an assembly base. The assembly base is provided with a retractable inclined pin. The connection and locking of the evolution plate and the top seat are realized by the cooperation of the inclined pin and the limiting hole.

9. A three-dimensional projection teaching device for history teaching according to claim 1, characterized in that: The bottom of the evolution plate is equipped with a plug, and the support foot is equipped with a socket. When the evolution plate is lowered to the working position, the plug and the socket are connected to realize power supply and signal transmission.

10. A projection system for a three-dimensional projection teaching device as described in claim 1, characterized in that: include: At least one projector is installed above the outer frame of the teaching equipment to project dynamic light and shadow images onto the surface of the viewing disk and the evolution disk of the teaching equipment. An image processing unit is located in the control box of the teaching equipment and is connected to the projector signal. It is used to generate or call up three-dimensional animations of terrain, building and water system changes. The control module, integrated in the control box, is electrically connected to the image processing unit, the lifting mechanism of the teaching equipment, the push rod group, the circular rail and the linear rail drive mechanism. It is used to receive control commands and coordinate the projection content of the projector with the lifting and lowering movements of the building block and the riverbed block. The software system runs on the touchscreen interface of the control box, providing a graphical user interface for selecting historical period parameters and controlling the demonstration process, so that the projected content and the dynamic changes of the physical model are matched in real time to form a fused display of a three-dimensional demonstration effect.

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