JP2006100374A - Structure for fitting front panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure for fitting a front panel wherein fitting and removal to/from a circuit board is easy, and assembling workability during manufacture, maintenability and disassembling workability for discard are superior. <P>SOLUTION: The structure for fitting a front panel 1 is designed to fit it to a circuit board that is fitted to a circuit board fitting part of electronic devices such as computer or private branch exchange, etc. The structure therefor is provided with: a board retainer 5 formed orthogonally on the rear surface of the front panel 1; two or more projections 6 projecting from the rear surface of the front panel 1 while being parallel to the board retainer 5; an engaging claw 7 formed projecting on the side of the board retainer 5 of the tip end of the projection 6; a part to be engaged that is formed in the specified section of the circuit board and with which the engaging claw 7 is engaged in the state where the front end side of the circuit board is inserted between the board retainer 5 and the projection 6; and a fulcrum forming part 12 which is arranged along the side part of the circuit board from one side part of the front panel 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a structure for attaching a front panel to a circuit board mounted on a circuit board mounting portion of an electronic device such as a computer or a private branch exchange.

  In recent years, in electronic devices such as computers, private branch exchanges, office automation equipment, etc., circuit boards for expansion and optional circuits for incorporating new functions with respect to main circuit boards such as printed wiring boards incorporated at the time of manufacture A board | substrate etc. are integrated as needed suitably. Such an additional circuit board, an optional circuit board, etc. (hereinafter referred to as a sub circuit board) are electrically connected to the main circuit board via a connector provided in advance on the main circuit board.

(Patent Document 1) discloses a front panel (front panel) for supporting and fixing a front panel (front panel) to a circuit board in a slot mounting type circuit board unit mounted in a board mounting slot of an electronic device such as a computer. A support structure is described. This support structure uses a handle in which a gripping part, a fitting part, and a fixing member are integrally formed. The fixing member of the handle is inserted into the through hole of the front panel, and the fitting part is fitted into the through hole. In addition, the front panel is supported and fixed to the circuit board by bringing the circuit board into contact with the upper surface of the fixing member and screwing the screw into the screw hole of the circuit board and the screw hole of the fixing member. ing.
Utility Model Registration No. 3020594

However, the above conventional techniques have the following problems.
In (1) (Patent Document 1), the front panel is supported and fixed to the circuit board by screwing. Therefore, in assembly work at the time of manufacture, the circuit board is fixed with a dedicated fixing jig. It had to be done and had the problem that workability was bad.
(2) In addition, there has been a problem that the front panel removal work is complicated and lacks maintainability when the parts mounted on the circuit board are damaged or failed, or when the parts are replaced or maintained. Furthermore, for the same reason, there has been a problem that the disassembly workability for separating and collecting when the unit is discarded is lacking.

  SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and provides a front panel mounting structure that is easy to mount and separate on a circuit board, has excellent assembly workability and maintenance during manufacture, and excellent disassembly workability during disposal. The purpose is to do.

  In order to solve the above problems, a front panel mounting structure according to the present invention is a front panel mounting structure on a circuit board mounted on a circuit board mounting portion of an electronic device such as a computer or a private branch exchange. A substrate pressing portion formed orthogonal to the back surface of the front panel, two or more protruding portions protruding substantially parallel to the substrate pressing portion from the back surface of the front panel, and protruding from the front end portion of the protruding portion on the substrate pressing portion side. An engaged claw portion that is formed on a predetermined portion of the circuit board and is engaged with the engagement claw portion in a state where the front end portion side of the circuit board is inserted between the substrate pressing portion and the protruding portion. And a fulcrum-forming side surface disposed along the side of the circuit board from one side of the front panel.

Accordingly, it is possible to provide a front panel mounting structure that can be easily mounted and separated from the circuit board, and is excellent in assembling workability and maintainability during manufacture and in disassembling workability during disposal.

  As described above, according to the front panel mounting structure of the present invention, the following advantageous effects can be obtained.

  According to the first aspect of the present invention, since the board pressing portion and the protruding portion are provided, the engaging claw portion can be changed to the engaged portion simply by inserting the circuit board between the board pressing portion and the protruding portion. It is possible to provide a front panel mounting structure excellent in workability of mounting work that can be engaged and the front panel can be easily mounted on the circuit board. Since it has a fulcrum-forming side surface, it is easy to remove from the circuit board by simply rotating the front panel with the fulcrum formed on the edge of the fulcrum-forming side surface as a fulcrum. A front panel mounting structure can be provided.

  In particular, when the front panel has two protrusions and engaging claws, and the circuit board has two engaged parts, it can be easily removed from the circuit board simply by rotating the front panel with a small force. It is possible to provide a front panel mounting structure with excellent workability. Since it can be easily attached to and detached from the circuit board, it is possible to provide a front panel attachment structure that is excellent in assembling workability and maintenance at the time of manufacturing and disassembling workability at the time of disposal.

  According to the second aspect of the invention, in addition to the effect of the first aspect, the reinforcing portion is disposed at the upper end portion and / or the lower end portion of the front panel. It is possible to provide a front panel mounting structure excellent in mechanical strength capable of preventing breakage and deformation.

  To provide a front panel mounting structure capable of protecting an external connection terminal by forming a reinforcing part so as to cover the external connection terminal when the external connection terminal is mounted on the front end of the circuit board. Can do.

  According to the third aspect of the present invention, in addition to the effect of the first or second aspect, the front panel includes a front-end portion of the front panel which is firmly sandwiched between the front-end portion of the circuit board. It is possible to provide a front panel mounting structure excellent in stability at the time of mounting that can prevent vertical displacement and wobbling of the panel.

  According to the fourth aspect of the present invention, in addition to the effect of any one of the first to third aspects, since the positioning portion and the positioning engagement portion are provided, the front panel in the horizontal direction with respect to the circuit board is provided. It is possible to provide a front panel mounting structure excellent in stability at the time of mounting that can prevent displacement and wobbling.

  According to the fifth aspect of the present invention, in addition to the effect of any one of the first to fourth aspects, since the rotation operation unit is provided, the front panel is removed when the front panel is removed from the circuit board. It is possible to provide a front panel mounting structure excellent in operability that can be easily rotated.

An object of the present invention is to provide a front panel mounting structure that can be easily mounted and separated from a circuit board, has excellent assembly workability and maintenance during manufacture, and has excellent disassembly workability during disposal. A substrate holding portion formed orthogonally to the substrate, two or more protruding portions protruding substantially in parallel with the substrate pressing portion from the back surface of the front panel, and protruding toward the substrate pressing portion side of the tip of the protruding portion. An engaging claw portion, an engaged portion that is formed in a predetermined portion of the circuit board and is engaged with the engaging claw portion with the front end portion of the circuit board being inserted between the substrate pressing portion and the protruding portion, and the front surface This is realized by providing a fulcrum-forming side surface portion disposed along the side portion of the circuit board from one side portion of the panel.

  A first invention made to solve the above problems is a structure for attaching a front panel to a circuit board to be mounted on a circuit board mounting portion of an electronic device such as a computer or a private branch exchange, and is provided on the back surface of the front panel. An orthogonally formed substrate holding portion, two or more protruding portions protruding substantially in parallel with the substrate holding portion from the rear surface of the front panel, and a protrusion protruding on the substrate pressing portion side of the tip of the protruding portion A mating claw portion, an engaged portion that is formed in a predetermined portion of the circuit board and that engages with the engaging claw portion in a state where the front end side of the circuit board is inserted between the board pressing portion and the protruding portion, and the front panel And a fulcrum-forming side surface portion disposed along the side portion of the circuit board from the one side portion.

  This configuration has the following effects.

  (1) When the front panel is attached to the circuit board, the front end side of the circuit board is inserted between the board holding part and the protruding part, and the front end part is held by the holding part, and the front end part of the protruding part is engaged. Since the pawl portion can be engaged with the engaged portion of the circuit board, the front panel can be easily attached to the circuit board simply by inserting the circuit board.

  (2) When removing the attached front panel from the circuit board, the front panel is rotated around the fulcrum part formed at the edge of the fulcrum forming side part, the front end part of the circuit board is removed from the clamping part, Since the joint claw portion can be removed from the engaged portion, it can be easily removed from the circuit board simply by rotating the front panel.

  (3) Especially when the front panel has two protrusions and engaging claws, and the circuit board has two engaged portions, the front panel is centered on the engaging claws closer to the fulcrum. Rotate in the direction of the arrow, remove the engaging claw part far from the fulcrum part from the engaged part, then rotate in the direction of the arrow with the fulcrum part as the fulcrum, and move the front end of the circuit board from the clamping part Since the engaging claw portion can be removed from the engaged portion while being pulled out, it can be easily removed from the circuit board by simply rotating the front panel with a small force.

  (4) Since it can be easily attached to and detached from the circuit board, it is excellent in assembling workability and maintenance at the time of manufacture, and disassembly workability at the time of disposal.

  A second invention made to solve the above-described problems is a front panel mounting structure according to the first invention, and includes a reinforcing portion disposed at an upper end portion and / or a lower end portion of the front panel. It has a configuration.

  With this configuration, in addition to the operation of the first invention, the following operation is provided.

  (1) Since the reinforcing part is arranged at the upper end and / or lower end of the front panel, the mechanical strength of the front panel can be increased, it can withstand bending stress applied during the removal operation, and is damaged or deformed. Can be prevented.

  (2) When the external connection terminal is mounted on the front end portion of the circuit board, the external connection terminal can be protected by forming the reinforcing portion so as to cover the external connection terminal.

  According to a third aspect of the present invention, there is provided a front panel mounting structure according to the first or second aspect, wherein the front panel is formed on the rear surface of the front panel and sandwiches the front end portion of the circuit board. It has the structure provided with the clamping part.

  With this configuration, in addition to the functions of the first or second invention, the following functions are provided.

  (1) Since the holding portion for holding the front end portion of the circuit board is provided, the front end portion of the front panel can be firmly held to prevent the front panel from being displaced or wobbled in the vertical direction.

  A fourth invention made to solve the above-described problems is the front panel mounting structure described in any one of the first to third inventions, wherein a convex shape formed on the back surface of the front panel or It has a configuration including a concave positioning portion and a concave or convex positioning engagement portion that is formed at the front end portion of the circuit board and engages with the positioning portion.

  With this configuration, in addition to the operation of any one of the first to third inventions, the following operation is provided.

  (1) Since the positioning portion and the positioning engagement portion are provided, it is possible to prevent horizontal displacement and wobbling of the front panel with respect to the circuit board.

  According to a fifth aspect of the present invention, there is provided a front panel mounting structure according to any one of the first to fourth aspects, wherein the front panel on the opposite side of the fulcrum-forming side surface portion is provided. It has the structure provided with the rotation operation part formed in the side part.

  With this configuration, in addition to the operation of any one of the first to fourth inventions, the following operation is provided.

  (1) Since the rotation operation unit is provided, when the front panel is removed from the circuit board, an operation of rotating the front panel can be easily performed.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a perspective view of the front panel, FIG. 2 (a) is a front view of the front panel, and FIG. 2 (b) is a cross-sectional view taken along line AA in FIG. 2 (a). 2 (c) is a cross-sectional view taken along line BB in FIG. 2 (a).

  In the figure, 1 is a front panel, 2 is a front part constituting the front side of the front panel 1, 3 is a plate-like upper reinforcing part integrally formed orthogonally to the upper end part of the front part 2, and 4 is a front face A plate-like lower reinforcing portion integrally formed perpendicular to the lower end portion of the portion 2, 5 is a plurality of substrate pressing portions linearly formed on the upper surface of the lower reinforcing portion 4, and 6 is a front portion 2. A tongue-like protrusion protruding from the rear surface substantially parallel to the upper portion of the substrate pressing portion 5, 6 a a rib formed on the upper surface of the protruding portion 6, and 7 protruding toward the substrate pressing portion 5 at the tip of the protruding portion 6. The engaging claw portion provided, 8 is an upper clamping piece formed on the back surface of the front surface portion 2, 9 is a step portion formed on the front surface portion 2 side of the lower reinforcing portion 4, and 9a is on the upper surface of the step portion 9. It is the some protrusion formed.

  Reference numeral 10 denotes a clamping part that clamps a front end portion of a circuit board, which will be described later, by the upper clamping piece 8 and the step part 9, reference numeral 11 denotes a convex positioning part formed at a substantially central part of the upper surface of the step part 9, and reference numeral 12 denotes a front part. 2 is a fulcrum forming part integrally formed orthogonally to one side of 2, 13 is a fulcrum part formed at the edge of the fulcrum forming part 12, and 14 is a front part 2 on the other side of the front part 2. The rotation operation unit is connected to the same surface as the rotation operation unit, 15 is an operation unit reinforcement formed at the side edge of the rotation operation unit 14, and 16 is a screw fixing unit formed at the lower part of the rotation operation unit 14. Openings 17 are terminal openings for exposing external connection terminals formed on the front surface portion 2 and mounted on a circuit board described later.

Here, the front panel 1 is integrally formed of a synthetic resin such as an ABS resin, a PS resin, or polypropylene (PP). As a result, the manufacturing cost can be reduced, the productivity is excellent, and a non-conductive material is used, so that a short circuit can be prevented. The protruding portion 6 is formed in a tongue shape so as to be elastically deformed in the vertical direction. A rib 6 a is formed on the upper surface of the protruding portion 6, and the engaging claw portion 7 moves away from the engaged portion 21 when the front panel 1 is attached to the circuit board 20 so that the protruding portion 6 is not easily deformed. I try not to come off easily.

  The front panel mounting structure of the first embodiment configured as described above will be described with reference to FIGS. 3A is a perspective view showing the operation of attaching the front panel to the circuit board, FIG. 3B is a cross-sectional view of the main part showing the clamping part, and FIG. 3C is a circuit board holding part. FIG. 4A is a perspective view showing an operation of removing the front panel from the circuit board, and FIG. 4B is an operation of removing the front panel from the circuit board. 5 is a plan view, and FIG. 5 is a perspective view of a main part of a locking claw portion.

  In the figure, 20 is a circuit board to which the front panel 1 is attached, 21 is a long hole-like engaged part formed in a predetermined part of the circuit board 20, and 22 is an external connection terminal mounted on the front end of the circuit board 20 , 23 is a screw hole formed in a side portion on the front end side of the circuit board 20, and 24 is a concave positioning engagement portion formed at a substantially central portion of the front end portion of the circuit board 20.

  When the front panel 1 is attached to the circuit board 20, as shown in FIG. 3B, the front end side of the circuit board 20 is inserted between the board pressing part 5 and the protruding part 6 and inserted to the back. The front end portion of the circuit board 20 is held between the upper holding piece 8 and the stepped portion 9 of the holding portion 10, and the engaging claw portion 7 at the tip of the protruding portion 6 is connected to the circuit board 20 as shown in FIG. The engaged portion 21 is engaged. Further, the positioning portion 11 is engaged with the positioning engagement portion 24. In this way, the front panel 1 is attached to the front end portion of the circuit board 20.

  When removing the attached front panel 1 from the circuit board 20, as shown in FIG. 4, a finger or the like is put on the rotation operation unit 14 of the front panel 1, and the front panel 1 is engaged with the engaging claw closer to the fulcrum unit 13. The engaging claw part 7 far from the fulcrum part 13 is removed from the engaged part 21 by rotating in the direction of the arrow shown in FIG. Subsequently, the fulcrum part 13 is rotated in the direction of the arrow with the fulcrum part 13 as a fulcrum, and the engaging claw part 7 is removed from the engaged part 21 while the front end part of the circuit board 20 is removed from the clamping part 10. In this way, the front panel 1 is removed from the circuit board 20.

  In addition, since a protrusion 9a extending in the insertion direction of the circuit board 20 is formed at least on the lower surface of the upper holding piece 8 on the upper surface of the stepped portion 9, the front end portion of the circuit board 20 is connected to the upper holding piece 8. It can be firmly held by the protrusion 9a. Further, since the operation portion reinforcing portion 15 is formed on the side edge portion of the rotation operation portion 14, even when a large force is applied to the rotation operation portion 14 when removing the front panel 1 from the circuit board 20, the rotation operation portion 14 rotates. It is possible to prevent the operation unit 14 from being damaged or deformed.

  As shown in FIG. 5, the engaging claw portion 7 is formed in a substantially elliptical column shape, and is formed with an inclined portion 7 a that is obliquely cut from the bottom surface of the substantially elliptical column toward the upper corner. . Further, the engaged portion 21 is formed in a substantially elliptical long hole shape corresponding to the shape of the engaging claw portion 7 so that the engaging claw portion 7 is inserted. As a result, when the circuit board 20 is inserted between the board pressing part 5 and the protruding part 6, the front end part of the circuit board 20 comes into contact with the inclined part 7a of the engaging claw part 7, and the protruding part 6 is moved upward. In order to push up, the circuit board 20 can be smoothly inserted, and also when the front panel 1 is removed, when the front panel 1 is rotated with respect to the circuit board 20, the arcuate outer wall surface of the engaging claw portion 7 is Since it slides out while coming into contact with the arcuate inner wall surface of the engaged portion 21, the attaching / detaching operation can be performed smoothly.

Next, the operation of mounting the circuit board 20 to which the front panel 1 is attached to the electronic device will be described with reference to FIGS. FIG. 6 is a perspective view illustrating an operation of mounting the circuit board to which the front panel is attached to the electronic device, and FIG. 7 is a perspective view illustrating another mode of the operation of mounting the circuit board to the electronic device. In the figure, 30 is an electronic device casing such as a computer or private branch exchange, 30a is a terminal opening formed on the side of the electronic device casing 30, 31 is a main circuit board, and 32 and 32 'are main circuit boards 31. The mounted main-side board connection terminal, 33 is a screw fixing bracket fixed inside the electronic device housing 30, 34 and 34 'are board connection terminals mounted on the lower surface or rear end of the circuit board 20, and 35 is A board insertion opening formed on the side surface of the electronic device casing 30, 36 is a screw, and X and X 'are circuit board mounting parts. 6 and 7, the top cover of the electronic device housing 30 is omitted for easy understanding.

  When the circuit board 20 to which the front panel 1 is attached is mounted on the circuit board mounting portion X in the electronic device housing 30, the circuit board 20 is arranged in parallel with the upper part of the main circuit board 31 as shown in FIG. The board connecting terminal 34 on the lower surface of the circuit board 20 is connected to the main board connecting terminal 32, and the screw 36 is inserted into the screwing hole 23 communicating with the screwing opening 16 of the front panel 1, thereby fixing the screw. Screw to 33. At this time, the external connection terminal 22 exposed on the front surface of the front panel 1 is exposed from the terminal opening 30a. In this way, the circuit board 20 is mounted inside the electronic device casing 30.

  Further, as shown in FIG. 7, the circuit board 20 to which the front panel 1 is attached may be inserted from the side of the electronic device housing 30 and mounted on the circuit board mounting portion X ′. In this case, the circuit board 20 is inserted into the board insertion opening 35 formed in substantially the same shape as the front panel 1, and the board connection terminal 34 'at the rear end of the circuit board 20 is used as the main board connection terminal 32'. Connecting. The front panel 1 is fitted into the board insertion opening 35, and the external connection terminal 22 is exposed on the side surface of the electronic device casing 30.

  As described above, the mounting structure of the front panel 1 according to the first embodiment is configured, and thus has the following operation.

  (1) The front end side of the circuit board 20 is inserted between the board pressing part 5 and the protruding part 6 so that the front end part of the circuit board 20 is held by the holding part 10 and the front end part of the protruding part 6 is engaged. Since the claw portion 7 can be engaged with the engaged portion 21 of the circuit board 20, the front panel 1 can be attached to the circuit board 20 simply by inserting the circuit board 20.

  (2) Since the front panel 1 has the two protruding portions 6 and the engaging claw portions 7 on the left and right, and the circuit board 20 has the two engaged portions 21, first, the front panel 1 is attached to the fulcrum portion. By rotating about the engaging claw portion 7 closer to 13, the engaging claw portion 7 far from the fulcrum portion 13 is removed from the engaged portion 21, and then the fulcrum portion 13 is further used as a fulcrum. Since the engaging claw portion 7 can be detached from the engaged portion 21 while rotating and removing the front end portion of the circuit board 20 from the clamping portion 10, the circuit board can be simply rotated by rotating the front panel 1 with a small force. 20 can be removed.

  (3) Since the front panel 1 can be easily attached to and detached from the circuit board 20, it is excellent in assembly workability and maintenance at the time of manufacture and disassembly workability at the time of disposal.

  (4) Since the plate-like upper reinforcing portion 3 and lower reinforcing portion 4 are integrally disposed perpendicular to the upper end portion and the lower end portion of the front panel 1, the mechanical strength of the front panel 1 can be increased. It is possible to withstand bending stress applied during the detaching operation, prevent damage and deformation, and the upper reinforcing portion 3 is formed so as to cover the external connection terminal 22, so that the external connection terminal 22 can be protected. .

(5) An upper clamping piece 8 and a step 9 that clamp the front end of the circuit board 20 on the back side of the front part 2.
Since the front end portion of the front panel 1 can be firmly clamped to prevent the front panel 1 from being displaced or wobbled in the vertical direction, the positioning portion 11 and the positioning engagement portion 24 are provided. Since it is provided, it is possible to prevent horizontal displacement and wobbling of the front panel 1 with respect to the circuit board 20.

  (6) Since the rotation operation part 14 is provided, when removing the front panel 1 from the circuit board 20, operation which rotates the front panel 1 can be performed easily.

  The present invention relates to a structure for attaching a front panel to a circuit board mounted on a circuit board mounting portion of an electronic device such as a computer or a private branch exchange, and in particular, according to the present invention, mounting and separation on a circuit board are easy, It is possible to provide a front panel mounting structure that is excellent in assembling workability and maintainability at the time of manufacturing and disassembling workability at the time of disposal.

Front panel perspective view (A) Front view of front panel, (b) Cross sectional view taken along line AA in FIG. 2 (a), (c) Cross sectional view taken along line BB in FIG. 2 (a). (A) Perspective view showing operation of attaching front panel to circuit board, (b) principal part sectional view showing clamping part, (c) principal part sectional view showing substrate pressing part and projecting part. (A) Perspective view showing operation of removing front panel from circuit board, (b) Plan view showing operation of removing front panel from circuit board Perspective view of the main part of the locking claw The perspective view which shows the operation | movement which mounts the circuit board with which the front panel was attached to an electronic device. The perspective view which shows another form of operation | movement which mounts a circuit board in an electronic device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Front panel 2 Front part 3 Upper reinforcement part 4 Lower reinforcement part 5 Substrate pressing part 6 Protrusion part 6a Rib 7 Engagement claw part 7a Inclination part 8 Upper clamping piece 9 Step part 9a Projection part 10 Holding part 11 Positioning part 12 Supporting point formation Part 13 Supporting point part 14 Rotation operation part 15 Operation part reinforcement part 16 Opening part for screwing 17 Opening part for terminal 20 Circuit board 21 Engaged part 22 External connection terminal 23 Screwing hole 24 Positioning engagement part 30 Electronic equipment housing Body 30a Terminal opening 31 Main circuit board 32, 32 'Main side board connection terminal 33 Screw fixing bracket 34, 34' Board connection terminal 35 Board insertion opening X, X 'Circuit board mounting part

Claims (5)

A front panel mounting structure to a circuit board mounted on a circuit board mounting part of an electronic device such as a computer or a private branch exchange,
A substrate pressing portion formed orthogonal to the back surface of the front panel;
Two or more protrusions protruding substantially in parallel with the substrate pressing portion from the back surface of the front panel;
An engaging claw projecting from the tip of the projecting portion on the side of the substrate presser,
An engaged portion that is formed in a predetermined portion of the circuit board and is engaged with the engaging claw portion in a state where the front end portion side of the circuit board is inserted between the substrate pressing portion and the protruding portion;
A fulcrum-forming side surface disposed along the side of the circuit board from one side of the front panel;
A front panel mounting structure characterized by comprising: The front panel mounting structure according to claim 1, further comprising a reinforcing portion disposed at an upper end portion and / or a lower end portion of the front panel. 3. The front panel mounting structure according to claim 1, further comprising a clamping portion that is formed on a back surface of the front panel and clamps a front end portion of the circuit board. A convex or concave positioning portion formed on the back surface of the front panel; and a concave or convex positioning engaging portion formed on a front end portion of the circuit board and engaged with the positioning portion. The front panel mounting structure according to any one of claims 1 to 3, wherein the front panel mounting structure is provided. The front panel mounting according to any one of claims 1 to 4, further comprising a rotation operation portion formed on a side portion of the front panel opposite to the fulcrum forming side surface portion. Construction.

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