JPH07107640A - Plate fixing mechanism - Google Patents

Abstract

PURPOSE:To provide a mechanism for facilitating the fixing and removal of a plate, covering a switch or a receptacle mounted on the indoor wall face of a housing or a building while sustaining a good appearance, to and from the wall surface. CONSTITUTION:A plate frame 2 made of a flexible material and a plate 1 made of an undeformable hard material are employed. The plate frame 2 is formed into a thin picture frame which is secured to the wall side and then fitted, at the upper and lower fringes thereof, with engaging claws 30, 31 protruding from the rear of the plate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate which protects a switch or an outlet fixed to an indoor wall surface of a house or a building and gives an aesthetic appearance, and more particularly to a plate which can be easily fixed to the wall surface. Regarding the fixing mechanism of.

[0002]

2. Description of the Related Art On the wall surface of a house or building, a switch or an outlet is attached for supplying power or switching wiring. Such a switch and an outlet are usually housed in an outlet box embedded in a wall surface, and their surfaces are usually exposed from the wall surface. However, if these switches and outlets are exposed on the wall surface, not only there is a risk of electric leakage and electric shock, but the appearance of the wall surface is spoiled. Therefore,
Conventionally, a thin plate made of metal or plastic is fixed as a cover to a switch or an outlet exposed from a wall surface. This plate exposes only the necessary parts of switches and outlets, covers the outlet box, etc., so that only the functions of the electrical components fixed to the wall surface are exposed.

For this purpose, switches and outlets are covered with rectangular or round plates, but in recent years, not only for safety, but also with the design and color of the plates, the interior of the room is decorated. Have been devised to be consistent with. In the case of such a specification, since the switch and the outlet are fixed in the wall and then the plate is fixed so as to be covered, the device has been devised so that the plate can be fixed without using screws. This is because if the plate is screwed from its surface, the head of the screw is exposed on the surface of the plate, which is unsightly.

Therefore, various methods of fixing the plate to the outlet box or the wall surface without using screws have been conventionally proposed. For example, there is also a configuration in which a claw for engagement is projected from the back surface of the plate and the claw is hooked on a fitting or a plate frame. In such a mounting method, after fixing the plate, it must be possible to remove the plate at a later date for repair or inspection of electric parts. For this reason, the plate itself is made of soft plastic, and the plate is made flexible so that it can be deformed by stress. By deforming the plate, the positions of the engaged claws are distorted, and the claws are disengaged from the fittings and the plate frame, so that the plate can be removed from the wall surface.

[0005]

As described above, in the plate having the conventional structure, its components are composed of soft plastic such as vinyl chloride, and the plate itself can be easily deformed so that it can be attached or detached. Was doing. However, in recent years, there has been a demand for using artificial marble or hard plastic (thermosetting resin, thermoplastic resin, etc.) as the material of the plate in view of characteristics such as appearance and robustness. Since these artificial marbles and hard plastics have a hard surface, they are hard to be scratched, and their aesthetic effect is generated due to their weight. Also, when installing a switch or outlet near a place where a sink made of artificial marble is used, such as in a kitchen or a washroom, a plate with the same material and the same color as the sink has an aesthetic sense. It is preferable. If the sink plate and the plate are not made of artificial marble or hard plastic of the same material,
The textures were the same, the colors of the two were kept uniform, and the aesthetics inside the kitchen, washroom, etc. were improved.

However, if a plate is molded from such artificial marble or hard plastic, the plate itself cannot be deformed because the material is hard,
The conventional structure cannot be detachably fixed to the mounting bracket or the plate frame. In order to eliminate this point, a method of making a through hole in a plate made of artificial marble or hard plastic and fixing it with screws is also conceivable. However, the head of the screw is projected on the surface of the plate to impair the aesthetics, and in places where water is used, water enters the electrical equipment through the through hole and causes electrical leakage. Therefore, there has been a demand for the development of a structure in which a plate made of artificial marble or hard plastic is detachably fixed to a mounting bracket or a plate frame, and the plate is fixed to a wall surface.

[0007]

According to the present invention, there is provided a plate frame made of a flexible material and fixed to the wall side, and a plate material made of a hard material which does not deform and detachably engaged with the plate frame. The plate frame is formed in a thin frame shape, the plate is formed in a thin planar shape, and engaging claws that engage with the upper and lower sides of the plate frame are projected on the upper and lower sides of the plate frame. The present invention provides a plate fixing mechanism characterized by the above.

[0008]

In the present invention, the plate frame to be attached to the wall surface first is formed in the shape of a frame, and the plate frame is made of flexible soft plastic. The shape can be changed. A plurality of engaging claws vertically opposed to each other are projected on the plate for covering the switch, the outlet and the like. To fix this plate to the plate frame, contact the upper engaging claw with the upper edge of the plate frame and press on the plate to deform the plate frame. Pass the bottom edge of. After that, when the stress is released, the upper engaging claws of the plate engage with the upper side of the plate frame, and the lower engaging claws of the plate engage with the lower side of the plate frame. In this way, the plate can be fixed to the plate frame. When removing the plate from the plate frame, push the upper side of the plate downward to deform the plate frame due to its flexibility, and remove the lower engaging claw from the lower side of the plate frame to make the plate easier than the plate frame. Can be removed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 is an exploded perspective view showing a state before fixing a plate to a wall surface in the present embodiment, FIG. 2 is a vertical sectional view showing a state where the plate is fixed to the wall surface, and FIG. 3 is an upper engaging claw formed on the plate. It is an expanded sectional view showing the vicinity of a plate frame.

First, FIG. 1 shows the structure of each member for fixing the plate 1 to the wall surface. In this fixing structure,
It is composed of a plate 1, a plate frame 2, a mounting frame 3, and an outlet box 4.

The plate 1 in the shape of a rectangular flat plate is exposed on the surface of the wall surface, is made of artificial marble or hard plastic, and the plate 1 itself does not deform due to stress. The plate 1 is formed thin, the outer periphery is inclined, and a rectangular frame hole 10 is formed at the center thereof. Two engaging claws 30 and 31 are projected inside the upper and lower short pieces of the plate 1 so as to face each other.

The frame 2 having a frame shape is for holding the plate 1 on the wall surface and is made of, for example, soft plastic such as vinyl chloride. Then, a large frame hole 15 is opened at the center of the plate frame 2, and the periphery thereof has an elongated rod shape. Fixed pieces 16 are connected to the inside of each short side of the plate frame 2 so as to extend into the frame holes 15, and each fixed piece 16 has an elliptical through hole 1
7 is opened therethrough. The plate frame 2 is integrally formed by injection molding or the like.

Next, the mounting frame 3 is a strong one made by processing a thin metal material with a press or the like, and a plurality of switches 20 are mounted side by side in the center thereof. This mounting frame 3
A necessary number of electric components such as a switch 20 and an outlet (not shown) can be attached to the housing, which is a standard product that has been widely used as a building material from the past. Further, rectangular through holes 21 are opened at the upper and lower centers of the mounting frame 3, respectively.

The outlet box 4 is embedded and fixed in the wall and has a box shape made of a metal or plastic material. It is possible to lead indoor wiring into the outlet box 4 and connect electrical components and indoor wiring inside this. A somewhat rectangular mounting hole 25 is cut out on the upper surface of the outlet box 4, and the inside of the outlet box 4 communicates with the outside through the mounting hole 25. Furthermore, this mounting hole 25 of the outlet box 4
A screw hole 26 is formed vertically at a position close to the position. In addition, the through hole 17 and the through hole 1 in the plate frame 2
7. The through holes 21 and the through holes 21 in the mounting frame 3 and the screw holes 26 and the screw holes 26 in the outlet box 4 are arranged at the same intervals. is there.

Next, the procedure for fixing the plate 1 to the outlet box 4 housed inside the wall in such a structure will be described.

First, the lower surface of the mounting frame 3 on which the plurality of switches 20 are mounted is brought into close contact with the surface of the outlet box 4. At this time, the rear half of each switch 20 has a mounting hole 2
5 is inserted into the outlet box 4 and only the head of each switch 20 is projected from the wall surface. After that, the lower surface of the plate frame 2 is brought into close contact with the upper surface of the mounting frame 3,
After the axes of the through hole 17, the through hole 21, and the screw hole 26 are aligned, the fixing screw 28 is inserted into the through hole 17 and the through hole 21, and the fixing screw 28 is screwed into the screw hole 26. By screwing the fixing screw 28, the plate frame 2 and the mounting frame 3
Will be screwed to the outlet box 4. In this way, when the plate frame 2 is fixed to the outlet box 4, the lower surface of the plate 1 is oriented so as to face the upper surface of the plate frame 2, and the engaging claw 30 above the plate 1 is placed above the plate frame 2. Hook it on the rim and push the plate 1 itself slightly downward. Then, since the plate frame 2 is flexible, the plate frame 2 is bent by the stress, and the vertical length of the plate frame 2 is slightly shortened. In this state, plate 1
The engaging claw 31 on the lower side of the plate frame 2 is passed through the lower edge of the plate frame 2, and the plate frame 2
Position the bottom side of. After that, when the stress pushing the plate 1 is released, the elasticity of the plate frame 2 restores the vertical length to the original length, and the engaging claw 30 and the engaging claw 31
Since the upper and lower sides of the plate frame 2 are engaged with each other, the plate 1 is held by the plate frame 2. When the plate 1 is removed from the plate frame 2 for repair or inspection, the upper part of the plate 1 is slightly pushed down to deform the plate frame 2, and the lower engaging claw 31 and the lower side of the plate frame 2 are engaged. The plate 1 can be removed from the plate frame 2 by removing the connection, pulling up the plate 1 from the lower side, and then raising it up.

FIG. 2 shows a plate 1, a plate frame 2, a mounting frame 3 and an outlet box 4 on the wall X in this embodiment.
It is sectional drawing which shows the state which fixed it integrally. As shown in FIG. 3, the outlet box 4 is housed inside the wall X and is embedded and fixed in concrete or the like. The rear portion of the switch 20 is located in the mounting hole 25 of the outlet box 4,
The back surface of the mounting frame 3 is brought into close contact with the front surface of the plate frame 2, and the back surface of the plate frame 2 is brought into close contact with the front surface of the mounting frame 3. Then, the fixing screws 28 are inserted into the through holes 17 and the through holes 21 in the plate frame 2 and the mounting frame 3, and the fixing screws 28 are screwed into the screw holes 26, whereby the plate frame 2 and the mounting frame 3 are connected to the outlet box 4. It is fixed to. After that, the upper and lower engaging claws 30 and 31 of the plate 1 can be fixed by engaging with the upper and lower sides of the plate frame 2. Since the plate 1 is cut at the center in FIG. 2, the engaging claws 30 and 31 are not shown in the drawing.

FIG. 3 shows how the upper engaging claws 30 are engaged with each other when the plate 1 and the plate frame 2 are engaged with each other. In this case, there is a gap between the engaging claw 30 projected on the back surface of the plate 1 and the back surface of the plate 1, and this gap is set to be slightly larger than the thickness of the upper side of the plate frame 2. For this reason, the engaging claw 30 is attached to the plate frame 2.
To the lower side (the right side in FIG. 3), the front side (the left side in FIG. 3) of the plate frame 2 closely contacts the inner wall of the plate 1, and the plate frame 2 has an upper side between the plate 1 and the engaging claw 30. Engagement is engaged. Thus, the plate 1 and the plate frame 2 are vertically engaged with each other, so that the plate 1 is fixed without coming off from the plate frame 2.

Next, FIG. 4 shows a second embodiment of the present invention.

In this embodiment, the plate frame 33 is entirely made of elastic soft plastic and is a square formed by a pair of left and right long peripheral edges 34 and a pair of upper and lower short peripheral edges 35. It has a frame shape. For this reason, the plate frame 33 is provided with a frame hole 39 having a large rectangular opening at the center thereof.
A slit-shaped transparent window 36 is opened at the center of each short peripheral edge 35. Further, a pair of fixing pieces 37 are projected on the inner edge of the frame hole 39, and an elliptical through hole 38 is opened at the center of each fixing piece 37.

In this embodiment, since a long thin through window 36 is formed in the short peripheral edge 35 in the shape of a slit, when stress is applied to the portion A in FIG. 4 where the engaging claws 30 and 31 contact. The short peripheral edge 35 is deformed by the stress, and the vertical length of the plate frame 33 is deformed to be shorter than the distance between the engaging claws 30 and 31. Therefore, the stress A is applied to the plate frame 33 while the engagement claw 30 of the plate 1 is locked to the short peripheral edge 35, and the engagement claw 31 is passed through the lower short peripheral edge 35 of the plate frame 33. After that, when the stress A is released, the engaging claws 30 and 31 mesh with the upper and lower short peripheral edges 35 of the plate frame 33, and the both are engaged.

FIG. 5 shows a third embodiment of the present invention.

In this embodiment, a corrugated leaf spring 40 is inserted in the space of the see-through window 36 in the second embodiment shown in FIG. The leaf spring 40 is made of a highly elastic material such as a phosphor bronze plate. Due to this configuration, when the stress B is applied to the upper surface of the short peripheral edge 35 and the position where the engaging claw 30 contacts, the short peripheral edge 35 bends downward. By the stress B pressed downward,
The upper and lower lengths of the plate frame 33 are reduced, and a gap into which the engaging claw 31 can be inserted is formed in the lower side of the plate frame 33. In this state, the engaging claw 31 is fitted into the lower side of the plate frame 33. After that, by releasing the stress B from above, the elasticity of the leaf spring 40 and the short peripheral edge 35 causes the short peripheral edge 3 to move.
5 returns to the original length. Thus, the plate frame 33
The upper and lower sides of the plate engage with the engaging claws 30 and 31, and the plate 1
The engaging claws 30 and 31 are fixed by engaging the plate frame 33.

Next, FIG. 6 shows a fourth embodiment of the present invention.

In this embodiment, the plate frame 43 is entirely formed of elastic soft plastic, and is a square formed by a pair of left and right long peripheral edges 44 and a pair of upper and lower short peripheral edges 45. It has a frame shape, and a frame hole 50 having a large opening is formed in the center thereof. A slit-shaped see-through window 46 is opened through each of the short peripheral edges 45, and a semicircular-shaped restricting projection 47 is projected at each of two places inside the see-through window 46. . The tip of the regulation protrusion 47 and the see-through window 46
A gap is formed between the inner circumference and the inner circumference. Also, the short edge 4
Fixing pieces 48 are projected on the inner edge of the frame hole 50 and inside the frame hole 50, and each fixing piece 48 has an oval through hole 49.
Is opened through.

In this embodiment, the engaging claw 30 is provided at the outer edge of the short peripheral edge 45 and at the position facing the regulating projection 47.
31 is in contact. Therefore, when the engaging claw 30 of the plate 1 is hooked on the upper edge of the plate frame 43 and pushed downward, stress C is applied to the upper edge of the plate frame 43, and the short peripheral edge 45 is bent by its elasticity. become. Therefore, the vertical length of the plate frame 43 is reduced, and the lower engagement claw 31 is inserted into the lower edge of the plate frame 43. After that, when the downward stress C due to the plate 1 is released, the shape of the short peripheral edge 45 is restored, the upper and lower short peripheral edges 45 are engaged with the engaging claws 30 and 31, and the plate 1 is connected to the plate frame 4
It will be fixed at 3. When the stress C is applied, the restriction protrusion 47 contacts the inner circumference of the transparent window 46, and restricts the short peripheral edge 45 from being largely deformed by the stress C.

Next, FIG. 7 shows a fifth embodiment of the present invention.

In this embodiment, the plate frame 53 is entirely made of elastic soft plastic, and is a square formed by a pair of left and right long peripheral edges 54 and a pair of upper and lower short peripheral edges 55. It has a frame shape, and a frame hole 59 is largely opened in the center thereof. A slit-shaped transparent window 56 is opened at the left and right of each short peripheral edge 55, and a slightly eyeglass-shaped through hole is formed at each short peripheral edge 55.
Further, a fixing piece 57 is projected on the inner edge of each short peripheral edge 55 so as to extend to the inside of the frame hole 59, and an elliptical through hole 58 is formed in the center of each fixing piece 57 so as to penetrate therethrough. is there.

In this embodiment, when stress B is applied to the short edge 55, the short edge 55 is deformed because the transparent window 56 is a space. Therefore, when the engaging claw 30 of the plate 1 is hooked on the upper edge of the plate frame 53 and pushed downward, a stress D is applied to the upper edge of the plate frame 53, and the short peripheral edge 55.
Will bend due to its elasticity. Therefore, the vertical length of the plate frame 53 is reduced, and the lower engagement claw 31 is inserted into the lower edge of the plate frame 53. Thereafter, when the downward stress D by the plate 1 is released, the short peripheral edge 55
Returns to its shape, and the upper and lower short peripheral edges 55 are engaged with the engaging claws 30, 31.
And the plate 1 is fixed to the plate frame 53. In this way, the plate 1 is fixed to the upper and lower short peripheral edges 55 of the plate frame 53 by the engaging claws 30 and 31.

Next, FIG. 8 shows a sixth embodiment of the present invention.

In this embodiment, the plate frame 63 is entirely made of elastic soft plastic, and has long peripheries 64 arranged in parallel to the left and right, and slightly extended to the lower part of both long peripheries 64. A character-shaped outer peripheral edge 67, a slightly U-shaped inner peripheral edge 68 extending to the lower part of the outer peripheral edge 67 and located inside the outer peripheral edge 67, and a short peripheral edge 65 hung over the upper ends of both long peripheral edges 64. It is formed in a frame shape, and a frame hole 71 is largely opened in the center thereof. Therefore, between the outer peripheral edge 67 and the inner peripheral edge 68, there is a slightly U-shaped separation hole 6
6 is formed. Then, the short peripheral edge 65 and the inner peripheral edge 68
Fixing pieces 69 are located in the space of the frame hole 71 so as to project from the surfaces facing each other, and elliptical through holes 70 are formed through the fixing pieces 69.

In this embodiment, when the engaging claw 31 on the lower side of the plate 1 is engaged with the lower side of the outer peripheral edge 67 and the plate 1 is pushed up from the lower side, the stress E is applied to the outer peripheral edge 67. Become. Then, the outer peripheral edge 67 is formed in a U-shape, and is separated from the inner peripheral edge 68 by the separation hole 66, and the upper and lower lengths of the plate frame 63 are shortened due to its elasticity. Therefore, the plate 1
The engaging claw 30 on the upper side of the engaging claw 30 forms a gap enough to pass through the upper edge of the short peripheral edge 65.
When the stress E is released after the engagement of the engaging claws, the upper surface of the short peripheral edge 65 bites into the gap of the engaging claws 30, and the plate 1 engages the engaging claws 3.
0 and 31 mesh with the upper and lower edges of the short peripheral edge 65 and the outer peripheral edge 67. Therefore, the plate 1 is fixed to the plate frame 63.

Next, FIG. 9 shows a seventh embodiment of the present invention.

In this embodiment, the plate 72 is shown in FIG.
Although the shape of the plate 1 is the same as that of the outer periphery of the plate 1, a wide upper engaging claw 73 is projected downward on the upper surface of the back surface of the plate 72, and lower engaging parts are provided on two lower left and right positions. The engaging claw 74 is projected. The plate frame 33 is entirely made of elastic soft plastic and has a rectangular frame shape formed by a pair of left and right long peripheral edges 76 and a pair of upper and lower short peripheral edges 77. ing. For this reason, the plate frame 75 has a frame hole 81 formed in a large square shape at the center thereof.
A slit-shaped transparent window 78 is opened at the center of the lower short peripheral edge 35.

To fix the plate 72 to the plate frame 75 in this embodiment, the lower engaging claws 74 of the plate 72 are used.
Is engaged with the lower short peripheral edge 77, the plate 72 is pulled upward, and stress F is applied to the short peripheral edge 77. Since the transparent window 78 is opened in the lower short edge 77, the short edge 77 is deformed by the stress F, and the plate frame 7
The length above and below 5 will shrink. Therefore, the upper engaging claw 73 bends enough to pass the upper surface of the short peripheral edge 77,
The upper engaging claw 73 passes through the upper short peripheral edge 77, and the plate 7
The back surface of 2 and the surface of the plate frame 75 are in close contact with each other. Thereafter, when the stress F from the bottom to the top is released, the short peripheral edge 77 is restored to its original shape, the upper short peripheral edge 77 bites into the gap of the upper engaging claw 73, and the lower short peripheral edge 77 is engaged. The plate 72 is bitten into the gap between the jaws 74, and the plate 72 is a plate frame 75.
Will be fixed to.

[0036]

As described above, a plate made of a hard material made of artificial marble or hard plastic can be fixed to the wall surface by engaging the elastic plate frame. With this plate, it is possible to cover the switch and the outlet that are exposed on the wall surface and maintain the aesthetic appearance. Although this plate is not made of soft plastic as in the past, it does not deform itself, but since the plate frame can be deformed in the vertical direction, it is sufficient to engage the engaging claws of the plate by applying stress. It can be deformed. Therefore, the conventional plate fixing method cannot fix the hard plate molded from artificial marble or hard plastic to the wall surface, but in the present invention, the hard plate can be easily fixed so as not to fall off. And since the plate can be molded with artificial marble or hard plastic, it can give a feeling of material that could not be expressed with conventional plates, and it can be attached to kitchens or washrooms using artificial marble sinks. As a result, it is possible to unify the feeling of weight and color and generate an aesthetic appearance.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of each member showing an embodiment of a plate fixing mechanism of the present invention.

FIG. 2 is a side sectional view showing a state in which a member of a plate fixing mechanism is fixed to a wall surface.

FIG. 3 is an enlarged cross-sectional view of an upper portion showing an engaged state of the plate and the plate frame.

FIG. 4 is a perspective view of a plate and a plate frame showing a second embodiment of the present invention.

FIG. 5 is a perspective view of a plate and a plate frame showing a third embodiment of the present invention.

FIG. 6 is a perspective view of a plate and a plate frame showing a fourth embodiment of the present invention.

FIG. 7 is a perspective view of a plate and a plate frame showing a fifth embodiment of the present invention.

FIG. 8 is a perspective view of a plate and a plate frame showing a sixth embodiment of the present invention.

FIG. 9 is a perspective view of a plate and a plate frame showing a seventh embodiment of the present invention.

[Explanation of symbols]

 1 plate 2 plate frame 3 mounting frame 4 outlet box 10 window 15 frame hole 20 switch 28 fixing screw 30 engaging claw 31 engaging claw 33 plate frame 36 transparent window 40 leaf spring 43 plate frame 46 transparent window 47 regulating protrusion 53 Plate frame 56 Transparent window 63 Plate frame 72 Plate 75 Plate frame 77 Transparent window

Claims (8)

[Claims] 1. A plate frame which is made of a flexible material and fixed to the wall side, and a plate which is made of a hard material that does not deform and is detachably engaged with the plate frame. The plate frame is formed into a thin frame shape,
The plate fixing mechanism, wherein the plate is formed in a thin planar shape, and engaging claws that engage with the upper and lower sides of the plate frame are projected on the upper and lower sides of the plate. 2. An outlet box housed in a wall surface, a mounting frame that is closely attached to the outlet box and can fix electric parts in the center thereof, and an attachment frame that is closely attached to the mounting frame and is made of a flexible material and is centered. A plate frame having a frame opening through which electric parts can be inserted, and a window formed of a hard material through which electric parts can be inserted are opened, and upper and lower sides of the rear surface are engaged with upper and lower sides of the plate frame. A plate fixing mechanism comprising a plate having a projecting claw. 3. The plate fixing mechanism according to claim 1, wherein through holes are provided in the upper and lower peripheral edges of the plate frame so as to have elasticity. 4. A transparent window hole having elasticity is formed in each of the upper and lower peripheral edges of the plate frame, and springs for reinforcing elasticity are inserted into the transparent window hole. Alternatively, the plate fixing mechanism according to item 2. 5. A transparent window hole having elasticity is formed in each of the upper and lower peripheral edges of the plate frame, and a protrusion for restricting a deformation amount is provided inside the transparent window hole. 1
Alternatively, the plate fixing mechanism according to item 2. 6. The plate fixing mechanism according to claim 1 or 2, wherein a plurality of through window holes each having elasticity are opened at upper and lower peripheral edges of the plate frame. 7. The plate according to claim 1 or 2, wherein the plate frame is formed with a transparent window hole continuously provided below the center of the side edge thereof and having a slightly U-shaped elasticity. Fixing mechanism. 8. A wide engaging claw is projected on the upper part of the back surface of the plate, and a plurality of engaging claws are projected on the lower part,
The plate fixing mechanism according to claim 1 or 2, wherein a transparent window hole for giving elasticity is opened in a lower peripheral edge of the plate frame.