JP3243038B2 - Projection screen - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection screen.

[0002]

2. Description of the Related Art A conventional projection screen is disclosed, for example, in Japanese Utility Model Laid-Open Publication No. 1-133141.
The projection screen shown in this figure is provided such that the screen can be wound and unwound on a winding pipe, and an overhang rail is attached to the other end of the screen, and the overhang rail is composed of two arms. The overhanging rail can be moved in a direction approaching the wind-up pipe and in a direction away from the wind-up pipe by a link mechanism (which is configured in a pantograph shape because two link mechanisms are provided). That is, when the link mechanism is contracted, the screen is wound around the winding pipe. On the other hand, when the screen is used, the link mechanism is extended to apply a predetermined tension to the screen.

[0003]

When the take-up pipe of the above-mentioned projection screen is driven to rotate by a motor, if the overhang rail hits an obstacle while the screen is being developed, the overhang rail moves. In spite of the inability to do so, the winding pipe will continue to rotate.
For this reason, the screen is unwound from the winding pipe and accumulates around the winding pipe in a loose state. For this reason, there is a problem that the loosened screen is wound in the reverse direction by the winding pipe or the screen is creased. An object of the present invention is to solve such a problem.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by providing a limit switch capable of detecting when the screen is loose. That is, the projection screen according to the present invention comprises a support frame (14), a winding pipe (16) rotatably supported by the support frame (14), and a motor (22) capable of driving the winding pipe (16) to rotate. 18), a screen (20) having one end connected to the winding pipe (16) and capable of being wound or unwound by this, and an extending rail (22) attached to the other end of the screen (20). , One end of a frame-side arm (28) rotatably connected to the support frame (14) and the other end of a rail-side arm (30) rotatably connected to one end of the extension rail (22). And a spring (34) for applying a force to the link mechanism (24) in a direction to extend the link mechanism (24).
And a limit switch (52) for emergency stop of the motor is provided adjacent to the outer periphery of the winding pipe (16), and the operation of the limit switch (52) is performed. piece (52a) is, winding Topa
Reaches a position close to the outer circumference of the pipe (16) and takes up the winding pipe
Screen (20) that has loosened around (16) and swelled around the periphery
To stop the motor (18), and to set a clearance between the screen (20) and the screen (20) even when the screen (20) is all wound around the winding pipe (16). It is characterized by being.

[0005]

When the extension rail hits an obstacle during the development of the screen and its movement is prevented, the screen is fed out from the winding pipe that continues to rotate. When the dispensed screen expands around the winding pipe, the operating piece of the limit switch is pressed, thereby stopping the power supply to the motor. Thereby, it is possible to prevent the screen from being wound around the winding pipe in the opposite direction or being creased. If limit switches are provided near both ends of the winding pipe, the motor can be stopped even when one side of the screen is loosened.
This can also be detected when one of the link mechanisms breaks down or when the overhanging rail moves up.

[0006]

【Example】

(First Embodiment) FIGS. 1 and 2 show an embodiment of the present invention. Support frame 1 fixed in a storage box (not shown)
4, a take-up pipe 16 is rotatably supported. The winding pipe 16 can be driven to rotate by a motor 18. One end of a screen 20 is connected to the winding pipe 16, and the screen 20 can be wound and unwound on the winding pipe 16. On the other hand, an extension rail 22 for holding the other end of the screen 20 is connected thereto. The extension rail 22 and the support frame 14 are connected by a pair of link mechanisms 24. Link mechanism 24
A frame-side arm 28 rotatably supported at one end by a pin 26 on the support frame 14;
2 has one end rotatably connected to rail 2
The other ends of the frame-side arm 28 and the rail-side arm 30 are rotatably connected by pins 31. A wire 32 extends inside the arms 30 and 28. The upper end of the wire 32 is fixed to the upper end of the rail-side arm 30, and the wire 3
2 is provided inside the arm 30 and then bent by the pin 30, passes through the arm 28 on the frame side, is further bent along the pin 26, and the lower end of the wire 32 is connected to one end of the spring 34. Are linked. The spring 34 is arranged in parallel with the winding pipe 16,
The other end of the spring 34 is fixed to the support frame 14. A screen cover 54 is attached to the support frame 14. As shown in FIG. 2, the screen cover 54 has an arc-shaped cross section so as to cover an upper portion of the winding pipe 16, and is provided over the entire length of the winding pipe 16. Limit switches 52 are provided at positions near both ends of the screen cover 54, respectively.
The operation piece 52a of the limit switch 52 penetrates through the screen cover 54 as shown in FIG.
6 has reached a position close to the outer periphery. However, even when the screen 20 is completely wound around the winding pipe 16, a clearance is formed between the operation piece 52a and the screen 20. Limit switch 52
Is for motor 18 emergency stop.

Next, the operation of this embodiment will be described. In a state where the projection screen is not used, the screen 20 is completely wound around the winding pipe 16, and the link mechanism 24 is in a folded state, that is, in a contracted state. When a projection screen is used for projection, the motor 18 is operated to rotate the winding pipe 16 in the unwinding direction. The wire 32 is bent in a “<” shape along the rail side arm 30 and the frame side arm 28, and the tension of the spring 34 is acting on this wire 32, so that the link mechanism 24 always extends. Receiving force in the direction you want. Therefore, when the screen 20 is unwound from the winding pipe 16, the link mechanism 24 is extended by the force of the spring 34, and the extension rail 22 is lifted. The motor 18 is stopped with the screen 20 completely unwound. In this state, the screen 20 is
Is maintained in a predetermined tension state by the force from the link mechanism 24 acting on the second member. Therefore, the screen 20 forms a flat surface without wrinkles, on which an image can be projected. Overhanging rail 2 while deploying screen 20
When the lift 2 is stopped by hitting the obstacle, the motor 18 continues to rotate, so that the screen 20 is loosened around the winding pipe 16 and swells to the outer periphery. Therefore, the operation piece 52a of the limit switch 52 operates, and the motor 18
Is stopped, and the screen 20 is prevented from loosening any more. Therefore, the screen 20 is connected to the winding pipe 16.
It is not wound up in the opposite direction or wrinkled.

[0008]

As described above, according to the present invention, the limit switch for emergency stop of the motor is provided adjacent to the outer periphery of the winding pipe, so that the overhang rail may hit an obstacle. In addition, the motor can be stopped, so that the screen is prevented from being wound around the winding pipe in the reverse direction or wrinkled. In addition, by providing limit switches at both ends of the take-up rail in the axial direction, even if one of the link mechanisms breaks down or the overhang rail moves up, the motor is stopped immediately by detecting this. Can be done.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a limit switch installation section.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Storage box 14 Support frame 16 Winding pipe 20 Screen 22 Projection rail 24 Link mechanism 28 Frame side arm 30 Rail side arm 34 Spring 52 Limit switch 52a Working piece

Continuing from the front page (72) Inventor Kenichi Ikeda 1006 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Akira Nakajima 3-15-4 Nihonbashi, Chuo-ku, Tokyo Inside Nichibei 72) Inventor Akio Miyazaki 4-4 Kojimachi, Chiyoda-ku, Tokyo Inside Tsuchiya Kogyo Co., Ltd. (72) Inventor Kazutaro Kanayama 1-11-12 Higashi-Ueno, Taito-ku, Tokyo Sakurai Co., Ltd. JP-A-4-163433 (JP, A) JP-A-2-105495 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03B 21/58

Claims (2)

(57) [Claims] 1. A support frame, a winding pipe rotatably supported by the support frame, a motor capable of driving the winding pipe to rotate, and one end connected to the winding pipe for winding or winding. A releasable screen, an overhang rail attached to the other end of the screen, one end of a frame-side arm rotatably connected to the support frame at one end, and one end rotatably connected to the overhang rail. A projection screen having a pair of link mechanisms formed by rotatably connecting the other end of the rail-side arm to each other, and a spring for applying a force in a direction to extend the link mechanisms to the link mechanism; adjacent the outer periphery of the pipe limit switch is provided for emergency stop motor, the actuating piece of the limit switch, proximity to the outer periphery of the winding pipe It reaches the position, winding Topa
It is pressed by the screen that has loosened around
The projection screen is set so as to have a clearance between the motor and the screen while the motor is stopped, even when the screen is all wound around the winding pipe. 2. Two limit switches are provided,
2. The projection screen according to claim 1, wherein each of the limit switches is disposed near both ends in the axial direction of the winding pipe.