CN113409625A

CN113409625A - A projection device for outdoor teaching

Info

Publication number: CN113409625A
Application number: CN202110946233.0A
Authority: CN
Inventors: 林泽丹
Original assignee: Shenzhen Zhicheng Yuanda Technology Co ltd
Current assignee: Shenzhen Zhicheng Yuanda Technology Co ltd
Priority date: 2021-08-18
Filing date: 2021-08-18
Publication date: 2021-09-17
Anticipated expiration: 2041-08-18
Also published as: CN113409625B

Abstract

The invention belongs to the technical field of teaching equipment, in particular to a projection device for outdoor teaching, which aims at solving the problem that the projection device for outdoor in the prior art is unclear due to strong light. When the device is used in the outdoor projection, when the device meets the strong light weather, the fan-shaped blocking cloths on two sides can be pulled out by pulling out the rotating strips on two sides, the sunlight shielding is carried out on two sides of the screen, then the two sliding clamping blocks on the top end slide forwards, the sun-shading cloth wound on the top end and on the cloth rolling rod can be pulled out from the top end, and the sunlight shielding is carried out on the top end.

Description

A projection device for outdoor teaching

Technical Field

The invention relates to the technical field of teaching equipment, in particular to a projection device for outdoor teaching.

Background

The teaching and showing device is an appliance used for writing and demonstrating in the education industry, a common teaching board is a board surface placed in a classroom or a meeting room, contents are written by chalk or a water-based pen, the effect of explaining and demonstrating is achieved, and when the teaching and showing device is used indoors, the problem of shading and reflecting does not need to be considered because indoor light is adjustable.

The outdoor teaching board applied in the prior art has single structure and function, generally only a wheel convenient to move is installed on an indoor teaching projection device and then pushed to the outside to become outdoor teaching projection equipment, or an independent curtain device is adopted and cannot be moved, and due to strong outdoor light, a viewer sitting in front of the projection equipment often cannot clearly see what the screen is projected from the bottom of the teaching projection screen, so that the novel outdoor teaching projection device convenient to clearly see the screen is needed.

Disclosure of Invention

The invention provides a projection device for outdoor teaching, aiming at overcoming the problem that the projection device for outdoor teaching in the prior art is unclear in watching due to strong light.

In order to achieve the purpose, the invention adopts the following technical scheme: a projection device for outdoor teaching comprises a base which is of a transverse rectangular tubular structure, wherein rollers capable of extending are arranged at four corners of the lower surface of the base, guide posts are fixed at four corners of the upper surface of the base, two side guard plates which are parallel to each other are respectively connected at the top ends of the four guide posts in a sliding manner, the projection device is rotatably connected between the two side guard plates, supporting plate strips which are parallel to each other and in a vertical state are respectively fixed at the front surfaces of the two side guard plates, arc-shaped guide rails which are symmetrical to each other are respectively fixed at the top ends of the two supporting plate strips, a rotating strip is rotatably connected at one side, close to the bottom end, of each supporting plate strip, a fan-shaped blocking cloth is fixed between the side surface of each rotating strip and the supporting plate strip, and a cloth winding rod wound with a sun-shading cloth is rotatably connected between the top ends of the two supporting plate strips, the outer wall of arc guide rail is close to the top position sliding connection who rotates the strip has the slip fixture block, two exhibition litter before being fixed with same root between the slip fixture block, the other end of puggaree is fixed on the pole body outer wall of exhibition litter before, thereby can be when using, meet highlight weather when the device is outdoor showing, only need to pull out the rotation strip of both sides and can pull out the fan-shaped cloth that keeps off of both sides, carry out sunshine to the both sides of screen and shelter from, later slide two slip fixture blocks on top forward again, can take out the puggaree on the batching pole again in the top coiling from the top, carry out sunshine to the top and shelter from.

Preferably, the projection device comprises a rotary drum rotatably connected between two more side guard plates, the rotary drum is internally provided with a cavity which is shaped like a triangular prism, two ends of the rotary drum are respectively provided with symmetrical stepped mounting holes, sliding bearings are clamped in the two stepped mounting holes, shaft cylinders with opposite openings are respectively and rotatably connected in the two sliding bearings, the barrel bottoms of the two shaft cylinders are respectively embedded with an internal threaded pipe, a rotating rod is screwed in the internal threaded pipe, the opposite ends of the two rotating rods are respectively fixed with a brake block, the inner edge of the inner wall of the rotary drum close to the circumference of the brake block is fixed with a rubber ring, therefore, when the rotating position of the rotating drum is required to be fixed in use, the rotating rod is required to be continuously rotated anticlockwise, so that the brake plate can be tightly pressed on the surface of the rubber ring, and the relative position of the rotating drum and the shaft cylinder is fixed.

As a preferable scheme in the invention, two ends of two adjacent surfaces of the rotary drum are respectively fixed with guide strips which are parallel to each other, the same curved screen is connected between the two guide strips on the same side of the rotary drum in a sliding manner, rectangular convex blocks which are matched with the diameter of the limiting slotted hole in the middle of the guide strips are fixed at both ends of the curved screen, and the bottom ends of the guide strips are provided with positioning pins, so that when one screen is used, the positioning pins and a device for fixing the rotary drum are only required to be loosened when the screen needs to be withdrawn for maintenance and page replacement, and then the screen is rotated clockwise by 120 degrees, if the screen is blocked, the curved screen can be slid along the guide strips, and the set double screens greatly improve the teaching efficiency.

As a preferable scheme in the invention, a round hole is formed in the middle of the upper surface of the base, an adjusting threaded pipe is rotatably connected in the round hole, a limiting snap ring matched with the diameter of the adjusting threaded pipe is fixed on the inner wall of the bottom of the base, an annular check ring and a check ring II are respectively fixed on the outer wall of the adjusting threaded pipe, which is close to the upper surface of the base, and the lower surface of the limiting snap ring, an annular check ring and a check ring II are fixed on the outer wall of the bottom of the adjusting threaded pipe, which are close to the top end, poking rods distributed at equal intervals are fixed on the outer wall of the circumference of the adjusting threaded pipe, a limiting ejector rod is screwed in the middle of the adjusting threaded pipe, a jack matched with the guide post is formed on the lower surface of the side guard plate, a positioning screw hole which is mutually penetrated through the jack is formed on the side surface of the side guard plate, and a positioning bolt is screwed in the positioning screw hole, so that when the height of the projection device needs to be adjusted, the projection device can be used, the projection device can be slowly pushed up by loosening the positioning bolt and then rotating the adjusting threaded pipe, thereby pushing the drum to the desired height.

As a preferable scheme in the invention, a triangular prism is fixed on the outer wall of the rotary drum close to the top end of the limit ejector rod, a sunk groove is formed on the lower surface of the triangular prism, a threaded hole is formed in the bottom of the sunk groove, and a stud matched with the threaded hole is fixed on the top end of the limit ejector rod, so that when the rotary drum is jacked to a required position by the limit ejector rod in use, the stud can be screwed into the threaded hole only by mounting the stud to the top end of the limit ejector rod and continuously rotating the stud for several circles, and the top end of the limit ejector rod and the triangular prism are relatively fixed.

According to the preferable scheme, the lower surface of the base, which is close to four corners, is provided with inclined holes, the four inclined holes are respectively clamped with a female pipe in a cross-shaped structure, one ends of the four female pipes, which are far away from the base, are respectively connected with an extension bar in a sliding manner, and the lower surface of one end of the extension bar, which is far away from the female pipe, is respectively fixed with a universal wheel with a brake.

As a preferable scheme in the invention, vertical fixing strips are fixed on the opposite sides of the two supporting laths, the two sides of the fan-shaped blocking cloth are respectively fixed on the side surfaces of the fixing strips and the rotating strips, the top ends of the fan-shaped blocking cloth are fixed with clamping blocks distributed at equal intervals, slide fasteners matched with the limiting grooves are reserved on the side surfaces of the clamping blocks, so that the fan-shaped blocking cloth can be smoothly unfolded under the pulling of the rotating strips, the two ends of the cloth rolling rod are respectively fixed with an L-shaped fixing block, and the L-shaped fixing blocks are fixed on the tops of the supporting laths on the side where the L-shaped blocking cloth is located.

As a preferable scheme in the invention, the top end of the rotating bar is provided with a slot, an extension ejector rod is connected in the slot in a sliding manner, the extension ejector rod is made of a permanent magnet material, one side of the extension ejector rod, which is far away from the curved screen, is provided with a notch, the inner wall of the notch is fixedly provided with a locking block, one end of the limiting groove, which is far away from the supporting plate strip, is fixedly provided with a stop lever matched with the notch, the top end of the extension ejector rod is provided with a top ball, and a compression spring is arranged between the bottom end of the extension ejector rod and the bottom of the slot, so that the rotating bar can be prevented from derailing when in use.

As a preferable scheme in the invention, the sliding fixture block comprises an upper fixture block and a lower fixture block slidably connected to the bottom end of the upper fixture block, the bottom end of the upper fixture block is provided with an insertion hole, a tension spring is fixed between the hole bottom of the insertion hole and the lower fixture block, one side of the upper fixture block opposite to the lower fixture block is provided with roller grooves, and rollers are arranged in the roller grooves, so that when the sunshade cloth is used, the sliding fixture block clamped on the arc-shaped guide rail can be driven to move along by shifting the support lath, and the sunshade cloth at the top end is unfolded.

To sum up, the beneficial effect in this scheme is:

this kind of a projection device for outdoor teaching, through setting up the fan-shaped cloth that keeps off at device top puggaree and both sides, can be when using, meet highlight weather when the device is in outdoor projection, only need to pull out the rotation strip of both sides can pull out the fan-shaped cloth that keeps off of both sides, carry out sunshine to the both sides of screen and shelter from, later slide two slip fixture blocks on top forward again, can take out the puggaree on the batching pole again with the top coiling, carry out sunshine to the top and shelter from, based on above function, the device has solved outdoor strong light and has influenced to teaching equipment ground, realized that teaching projection device is normal at outdoor teaching ground beneficial effect.

Drawings

FIG. 1 is a schematic view of the overall structure of a projection device for outdoor teaching;

FIG. 2 is a schematic view of a front view of a projection device for outdoor teaching;

FIG. 3 is a schematic cross-sectional view of the projection device for outdoor instruction taken along line B-B in FIG. 2;

FIG. 4 is a schematic view of the construction of a projection device drum for outdoor teaching;

FIG. 5 is a schematic cross-sectional view of the end of the projection device drum for outdoor instruction;

FIG. 6 is an enlarged view of the projection device for outdoor instruction at A in FIG. 3;

FIG. 7 is a schematic perspective view of a sunshade device in a projection device for outdoor teaching;

FIG. 8 is a schematic perspective view of a projection mechanism of a projection device for outdoor instruction;

fig. 9 is an enlarged view of the projection device for outdoor teaching at C in fig. 3;

fig. 10 is a schematic perspective view of a sliding block of a projection device for outdoor teaching.

In the figure: 1 base, 2 annular retainer rings, 3 adjusting threaded pipes, 301 poke rods, 302 opposite-top nuts, 4 guide posts, 5 limiting ejector rods, 501 studs, 6 curved screens, 601 rectangular lugs, 7 side guard plates, 8 brake plates, 801 shaft cylinders, 802 rotating rods, 9 rotating cylinders, 901 triangular prisms, 902 sinking grooves, 10 fixing strips, 11L-shaped fixing blocks, 12 cloth rolling rods, 13 sun-shading cloth, 1301 front spreading sliding rods, 14 clamping blocks, 15 extending ejector rods, 1501 notches, 1502 top balls, 1503 locking blocks, 16 sliding clamping blocks, 1601 grooves, 1602 inner sliding rods, 1603 rollers, 17 arc-shaped guide rails, 18 limiting grooves, 19 retainer rods, 20 sector-shaped retaining cloth, 21 rotating strips, 22 supporting laths, 23 extension rods, 24 female pipes, 25 limiting clamping rings, 26 retainer rings, 27 rubber rings, 28 guide strips and 29 positioning pins.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

Example 1

Referring to fig. 1-5, a projection device for outdoor teaching, which comprises a base 1 with a horizontal rectangular tubular structure, if the weight of the base 1 is not enough, a counterweight can be arranged on the lower surface of the base 1 to improve the stability of the base, rollers which can extend in the opposite direction of the diagonal line are arranged on the four corners of the lower surface of the base 1, the bearing area is increased, and the stability effect is improved, guide posts 4 are fixed on the four corners of the upper surface of the base 1, two side guard plates 7 which are parallel to each other are respectively connected with the top ends of the four guide posts 4 in a sliding manner, the projection device is rotatably connected between the two side guard plates 7, supporting laths 22 which are parallel to each other and in a vertical state are respectively fixed on the front surfaces of the two side guard plates 7, arc guide rails 17 which are symmetrical to each other are respectively fixed on the top ends of the two supporting laths 22, rotating strips 21 are rotatably connected on the opposite sides of the two supporting laths 22 near the bottom ends, the fan-shaped blocking cloth 20 is fixed between the side face of the rotating strip 21 and the supporting strips 22, the same cloth rolling rod 12 wound with the sunshade cloth 13 is connected between the top ends of the two supporting strips 22 in a rotating mode, the outer wall of the arc-shaped guide rail 17 is close to the sliding block 16 is connected to the top end portion of the rotating strip 21 in a sliding mode, the same front stretching sliding rod 1301 is fixed between the two sliding block 16, the other end of the sunshade cloth 13 is fixed to the rod body outer wall of the front stretching sliding rod 1301, therefore, when the device is used in outdoor showing, when the device meets strong light weather, the fan-shaped blocking cloth 20 on the two sides can be pulled out only by pulling out the rotating strips 21 on the two sides, the two sides of the screen are shielded by sunlight, then the two sliding block 16 on the top end slide forwards, the sunshade cloth 13 wound on the top end cloth rolling rod 12 can be pulled out from the top end, and the top end is shielded by the sunlight.

In the invention, the projection device comprises a rotary drum 9 which is rotationally connected between two side guard plates 7, the rotary drum 9 is internally provided with a cavity which is in a triangular prism structure, two ends of the rotary drum 9 are respectively provided with symmetrical ladder mounting holes, sliding bearings are respectively clamped in the two ladder mounting holes, shaft cylinders 801 with opposite openings are respectively rotationally connected in the two sliding bearings, inner thread pipes are respectively embedded at the bottoms of the two shaft cylinders 801, rotating rods 802 are screwed in the inner thread pipes, brake plates 8 are respectively fixed at the opposite ends of the two rotating rods 802, rubber rings 27 are fixed at the inner edges of the inner wall of the rotary drum 9, which are close to the circumference of the brake plates 8, therefore, when the rotating position of the rotary drum 9 needs to be fixed in use, the brake plate 8 can be tightly pressed on the surface of the rubber ring 27 only by continuously rotating the rotary rod 802 anticlockwise, and then the relative position of the rotary drum 9 and the shaft barrel 801 is fixed.

Wherein, the both ends of two adjacent faces of rotary drum 9 are fixed with the gib block 28 that is parallel to each other respectively, sliding connection has same curved screen 6 between two gib blocks 28 of rotary drum 9 with one side, curved screen 6's both ends all are fixed with the rectangle lug 601 of the spacing slotted hole footpath looks adaptation in the middle of the gib block 28, the bottom of gib block 28 is provided with locating pin 29, thereby can be when using, only need become flexible locating pin 29 and be used for fixed rotary drum 9's device when curved screen 6 need withdraw from to maintain the change space of a whole page, later clockwise rotation 120 degrees can again, if block, can along gib block 28 slip curved screen 6 can, the double screen of setting, teaching efficiency has been improved greatly.

Example 2

Referring to fig. 6-8, a projection apparatus for outdoor teaching, in this embodiment, compared with embodiment 1, the projection apparatus further includes a circular hole opened in the middle of the upper surface of the base 1, an adjusting threaded pipe 3 is rotatably connected in the circular hole, a limiting snap ring 25 adapted to the diameter of the adjusting threaded pipe 3 is fixed on the inner wall of the bottom of the base 1, an annular check ring 2 and a check ring two 26 are respectively fixed on the outer wall of the adjusting threaded pipe 3 near the upper surface of the base 1 and the lower surface of the limiting snap ring 25, a poking rod 301 equidistantly distributed near the top end of the circumferential outer wall of the adjusting threaded pipe 3, a limiting ejector rod 5 is screwed in the middle of the adjusting threaded pipe 3, a jack adapted to the guide post 4 is opened on the lower surface of the side guard plate 7, a positioning screw hole mutually penetrating through the jack is opened on the side of the side guard plate 7, a positioning bolt is screwed in the positioning screw hole, so that when the projection apparatus is used and needs to be adjusted in height, only need loosen positioning bolt earlier, later rotate the regulation screwed pipe 3 and can slowly drive spacing ejector pin 5 and slowly push up, and then push away rotary drum 9 to the height that needs.

Wherein, the top that the outer wall of rotary drum 9 is close to spacing ejector pin 5 is fixed with triangular prism 901, the lower surface of triangular prism 901 is opened there is heavy groove 902, the tank bottom of heavy groove 902 is opened threaded hole, spacing ejector pin 5's top is fixed with the double-screw bolt 501 with threaded hole looks adaptation, thereby can be when using, when spacing ejector pin 5 pushes up rotary drum 9 to required position, only need to install double-screw bolt 501 to the top of spacing ejector pin 5 and last rotate several rings again can with double-screw bolt 501 precession screw hole, make the top of spacing ejector pin 5 and triangular prism 901 form relatively fixed.

Wherein, base 1's lower surface is close to four corners department and has all opened the inclined hole, and equal joint has female pipe 24 that is fork-shaped structure in four inclined holes, and four female pipe 24 keep away from the equal sliding connection of base 1's one end has extension bar 23, and extension bar 23 keeps away from the one end lower surface of female pipe 24 and all is fixed with the area universal wheel of stopping, can increase the bearing area on chassis, improves the stable wind resistance of device.

Wherein, the relative one side of two support laths 22 all is fixed with vertical fixed strip 10, the both sides of fan-shaped fender cloth 20 are fixed respectively in the side of fixed strip 10 and rotation strip 21, the top of fan-shaped fender cloth 20 is fixed with the fixture block 14 that the equidistance distributes, the side of fixture block 14 reserves the smooth knot with spacing groove 18 looks adaptation to ensure that fan-shaped fender cloth 20 can launch smoothly under the pulling of rotation strip 21, the both ends of batching pole 12 all are fixed with L shape fixed block 11, L shape fixed block 11 is fixed at the top of the support lath 22 of side at this.

Example 3

Referring to fig. 9-10, compared with embodiment 1, in embodiment 1, on the basis of embodiment 1, a slot is formed at the top end of a rotating bar 21, an extending ejector rod 15 is slidably connected in the slot, the extending ejector rod 15 is made of a permanent magnet material, a notch 1501 is formed in one side, away from a curved screen 6, of the extending ejector rod 15, a locking block 1503 is fixed on the inner wall of the notch 1501, a stop rod 19 matched with the notch 1501 is fixed at one end, away from a supporting lath 22, of a limiting groove 18, a top ball 1502 is arranged at the top end of the extending ejector rod 15, and a compression spring is arranged between the bottom end of the extending ejector rod 15 and the bottom of the slot, so that the rotating bar 21 cannot derail in use.

Wherein, slip fixture block 16 includes fixture block and sliding connection at the lower fixture block of last fixture block bottom, and it has the jack to go up the bottom of fixture block and open, is fixed with the extension spring between the hole bottom of jack and the lower fixture block, goes up the fixture block and all is provided with roller groove 1601 with one side that lower fixture block is relative, all is provided with roller 1603 in the roller groove 1601 to can be when using, can drive the slip fixture block 16 of joint on arc guide 17 and also follow the removal through stirring the backup plate strip 22, and then expand the puggaree 13 on top.

The device provides the following beneficial effects:

this kind of a projection device for outdoor teaching, through setting up fan-shaped fender cloth 20 at device top puggaree 13 and both sides, can be when using, meet highlight weather when the device is in outdoor projection, only need to pull out the rotation strip 21 of both sides and can tear out the fan-shaped fender cloth 20 of both sides, carry out sunshine to the both sides of screen and shelter from, later slide two slip fixture blocks 16 forward with the top again, can take out puggaree 13 on top batching pole 12 from the top, carry out sunshine to the top and shelter from, based on above function, the device has solved outdoor strong light and has influenced to teaching equipment ground, the beneficial effect that teaching projection device normally was outdoor teaching has been realized.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. The projection device for outdoor teaching comprises a base (1) which is of a transverse rectangular tubular structure, wherein idler wheels capable of extending are arranged at four corners of the lower surface of the base (1), guide columns (4) are fixed at four corners of the upper surface of the base (1), four top ends of the guide columns (4) are respectively connected with two side guard plates (7) which are parallel to each other in a sliding manner, the two side guard plates (7) are rotatably connected with a projection device, the projection device is characterized in that supporting laths (22) which are parallel to each other in a vertical state are respectively fixed at the front surfaces of the two side guard plates (7), arc-shaped guide rails (17) which are symmetrical to each other are respectively fixed at the top ends of the two supporting laths (22), rotating strips (21) are rotatably connected close to the bottom ends of the opposite sides of the two supporting laths (22), and fan-shaped blocking cloth (20) are fixed between the side surfaces of the rotating strips (21) and the supporting laths (22), two it has batching pole (12) of puggaree (13) to rotate to be connected with same root coiling between the top of support lath (22), the outer wall of arc guide rail (17) is close to the top position sliding connection who rotates strip (21) has slip fixture block (16), two be fixed with exhibition litter (1301) before the same root between slip fixture block (16), the other end of puggaree (13) is fixed on the pole body outer wall of exhibition litter (1301) before.

2. The projection device for the outdoor teaching according to claim 1, wherein the projection device comprises a rotary drum (9) rotatably connected between two side protection plates (7), the rotary drum (9) is internally provided with a cavity with a triangular prism shape, two ends of the rotary drum (9) are respectively provided with symmetrical stepped mounting holes, sliding bearings are respectively clamped in the two stepped mounting holes, shaft cylinders (801) with opposite openings are respectively and rotatably connected in the two sliding bearings, the barrel bottoms of the two shaft cylinders (801) are respectively embedded with an internal threaded pipe, a rotating rod (802) is screwed in the internal threaded pipe, one ends of the two rotating rods (802) opposite are respectively fixed with a brake plate (8), and a rubber ring (27) is fixed on the inner wall of the rotary drum (9) close to the inner edge of the circumference of the brake plate (8).

3. The projection device for the outdoor teaching according to claim 2, wherein two ends of two adjacent surfaces of the rotary drum (9) are respectively fixed with guide strips (28) which are parallel to each other, the same curved screen (6) is connected between the two guide strips (28) on the same side of the rotary drum (9) in a sliding manner, both ends of the curved screen (6) are respectively fixed with a rectangular convex block (601) which is matched with the diameter of a limiting groove hole in the middle of each guide strip (28), and the bottom ends of the guide strips (28) are provided with positioning pins (29).

4. The showing device for the outdoor teaching according to claim 3, wherein a round hole is formed in the middle of the upper surface of the base (1), the adjusting threaded pipe (3) is rotatably connected in the round hole, a limiting snap ring (25) matched with the diameter of the adjusting threaded pipe (3) is fixed on the inner wall of the bottom of the base (1), an annular check ring (2) and a second check ring (26) are respectively fixed on the outer wall of the adjusting threaded pipe (3) close to the upper surface of the base (1) and the lower surface of the limiting snap ring (25), poking rods (301) distributed at equal intervals are fixed on the outer wall of the circumference of the adjusting threaded pipe (3) close to the top end, a limiting ejector rod (5) is screwed in the middle of the adjusting threaded pipe (3), a jack matched with the guide column (4) is formed on the lower surface of the side protection plate (7), and a positioning screw hole mutually penetrating through the jack is formed on the side surface of the side protection plate (7), the positioning screw hole is screwed with a positioning bolt.

5. The projection device for the outdoor teaching according to claim 4, wherein a triangular prism (901) is fixed on the outer wall of the rotary drum (9) close to the top end of the limiting mandril (5), a sunken groove (902) is formed in the lower surface of the triangular prism (901), a threaded hole is formed in the bottom of the sunken groove (902), and a stud (501) matched with the threaded hole is fixed on the top end of the limiting mandril (5).

6. The projection device for the outdoor teaching according to any one of claims 4 to 5, wherein inclined holes are formed in the lower surface of the base (1) near the four corners, the four inclined holes are respectively clamped with a main pipe (24) in a cross structure, one ends of the four main pipes (24) far away from the base (1) are respectively connected with an extension bar (23) in a sliding manner, and universal wheels with brakes are fixed on the lower surfaces of the ends of the extension bars (23) far away from the main pipes (24).

7. The projection device for the outdoor teaching according to claim 6, wherein the two opposite sides of the supporting laths (22) are fixed with vertical fixing strips (10), the two sides of the fan-shaped cloth stopper (20) are respectively fixed on the sides of the fixing strips (10) and the rotating strips (21), the top end of the fan-shaped cloth stopper (20) is fixed with clamping blocks (14) distributed at equal intervals, the side of each clamping block (14) is reserved with a sliding buckle matched with the limiting groove (18), the two ends of the cloth winding rod (12) are fixed with L-shaped fixing blocks (11), and the L-shaped fixing blocks (11) are fixed on the tops of the supporting laths (22) on the side where the L-shaped fixing blocks are located.

8. The projection device for outdoor teaching of claim 7, wherein the top end of the rotating bar (21) is provided with a slot, the slot is internally and slidably connected with an extending ejector rod (15), the extending ejector rod (15) is made of a permanent magnet material, one side of the extending ejector rod (15) far away from the curved screen (6) is provided with a notch (1501), the inner wall of the notch (1501) is fixed with a locking block (1503), one end of the limiting groove (18) far away from the supporting lath (22) is fixed with a stop lever (19) matched with the notch (1501), the top end of the extending ejector rod (15) is provided with a top ball (1502), and a compression spring is arranged between the bottom end of the extending ejector rod (15) and the slot bottom, so that the rotating bar (21) can be ensured not to derail when in use.

9. The projection device for the outdoor teaching according to claim 8, wherein the sliding fixture block (16) comprises an upper fixture block and a lower fixture block slidably connected to the bottom end of the upper fixture block, the bottom end of the upper fixture block is provided with an insertion hole, a tension spring is fixed between the hole bottom of the insertion hole and the lower fixture block, one side of the upper fixture block opposite to the lower fixture block is provided with a roller groove (1601), and rollers (1603) are arranged in the roller grooves (1601).