JP4628553B2 - Pushbutton unit and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a push button unit made by forming a general-purpose sheet and a method for manufacturing the same. More specifically, the present invention relates to a push button made by thermoforming a thermoplastic synthetic resin sheet, and a manufacturing method thereof.
[0002]
[Prior art]
With the recent spread of computer-related devices and communication devices, input operation units such as control panels for inputting / outputting information to / from these devices are required to be extremely cost-effective without sacrificing operability. . On the other hand, in addition to increasing the precision of electronic parts, sealing is also required to prevent destruction of electronic parts due to dust and static electricity.
[0003]
For example, with regard to control panels for parts used in electronic devices such as portable telephones, the ultimate cost reduction is required in order to popularize these devices at a low price. Improvements in functionality are also required. In terms of functionality, design, safety, etc., there is a strong demand to supply the market with products that satisfy consumers' purpose or design and that can be used with peace of mind.
[0004]
Applicants Therefore proposes a control panel of an electronic device using the sheet (JP-A-9-259696, JP-A No. 9-259697, JP-Open 2000-285762 Patent Publication). In the former two inventions among the proposed ones, the assembly of the control panel and the push button employs a mechanical assembly structure. When this mechanical assembly structure is employed, the structure becomes complex and the number of parts tends to increase.
[0005]
The latter invention improves this and reduces the number of assembly steps by thermal bonding. However, since the film that is the base material of the sheet molded product is transparent, and the molten resin to be welded is also transparent, in the case of a push button that is cut and pasted when performing a switching operation, the portion around the weld, That is, there is a problem that the welded portion and the unwelded border portion of the molded sheet molded product are irregularly reflected and difficult to see. In order to prevent erroneous operation, there has been a demand for a sheet molded product that has a clean design, is stable, and has improved functions. Further, further improvement has been demanded in terms of cost reduction.
[0006]
[Problems to be solved by the invention]
The present invention has been made based on such a technical background, and achieves the following object.
SUMMARY OF THE INVENTION An object of the present invention is to provide a push button unit that is manufactured by thermoforming a sheet so that there is no risk of erroneous operation, and is inexpensive, and a method for producing the push button unit.
Still another object of the present invention is to provide a push button unit which can manufacture a uniform sheet over the outer periphery of the concave portion of the molded sheet and is excellent in mass productivity, and a method for manufacturing the same.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the following means are adopted.
The push button unit of the present invention is a control panel provided with a sheet forming push button, wherein a sheet having a printing layer is thermoformed into an outer shell, and a formed sheet having a recessed portion is formed, and the recessed portion of the formed sheet is surrounded by an outer edge. A molten resin stretched and filled by injection molding, a plurality of pushbuttons made by cutting the sheet filled with the molten resin, and formed in the recesses of the plurality of pushbuttons across the periphery of the outer edge The formed resin portion is elastically bent and supported from below, and is composed of a push button support integrated with the push button.
[0008]
Further, the manufacturing method of the push button unit includes a process of forming a sheet having a printed layer into a concave shaped sheet by thermoforming in a control panel having a sheet forming push button, and the molding sheet is formed in an injection mold. A step of cutting the sheet filled with molten resin across the recess and the outer periphery of the recess to form a plurality of push buttons, and the periphery of the outer periphery of the recesses of the plurality of push buttons The resin portion formed over the substrate is elastically bent and supported by the push button support, and is integrated with the push button.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. In order to understand the present invention, an outline of a panel body configuration will be described as an example in which a control panel of an electronic device to which the pushbutton unit of the present invention is applied is adopted in a portable telephone. The present invention is also intended was improved developing technology invention of the Japanese Open 2000-285762 Patent Publication. Therefore details of the body structure because it is described in this publication, a detailed description thereof will be omitted.
[0010]
FIG. 1 is a perspective view of a portable telephone equipped with the push button unit of the present invention. The portable telephone 1 is composed of a telephone body 2 made of synthetic resin or the like, and an electronic device such as an IC that realizes a telephone function is built in the telephone body 2.
[0011]
The telephone body 2 is composed of two bodies, and is divided into two by a dividing surface 6 between the thicknesses. A case cover 3 is disposed on the upper surface of the telephone body 2, and a rear surface body 5 is disposed on the rear surface. The case cover 3 fulfills both functions of the control panel and the telephone body 2, and a plurality of push buttons 4 are arranged to constitute a key group 7. The case cover 3 and the back surface main body 5 are integrally fixed by fixing means such as screws or notches.
[0012]
(Printing the display)
The case cover 3 is provided with a push button 4 made by a method described later.
Hereinafter, this manufacturing method will be described in detail. As the outer skin of the push button 4, a single sheet 10 which is a single-layer sheet having a uniform thickness as shown in the plan view of FIG. 2 is used. The single sheet 10 is, for example, a thin film-shaped thermoplastic synthetic resin cut into a transparent body or a translucent body having a thickness of about 0.25 mm to 0.8 mm, that is, a light-transmitting rectangular shape.
[0013]
Specifically, a resin such as polycarbonate (PC), a mixture of polybutylene terephthalate (PBT) and PC, polyethylene terephthalate (PET), PBT, ABS resin, polyurethane (PUR), or the like may be used. The single sheet 10 has high tensile strength and is not easily torn, and is mass-produced by many manufacturers. A general-purpose product that is commercially available at an extremely low cost is desirable.
[0014]
On the surface of the single sheet 10, a display unit 13 for a plurality of numbers, characters, symbols, and the like is arranged. The display unit 13 is formed as a print layer 11 by being printed on the entire back surface when viewed from the front side of the push button 4. As shown in FIG. 2, in a state in which each printing layer 11 of the single sheet 10 is on the upper surface (illustrated), the necessary display unit 13 is printed on the back surface of the finger contact unit 9 of the push button 4, To do.
[0015]
However, the printing layer 11 may be printed by overlapping the entire surface of the single sheet 10 while changing the ground color without printing only the display unit 13 such as numbers, characters, symbols, and the like. . Since the single sheet 10 is a transparent material, the color of the ink printed from the back side can be used as the display unit 13.
[0016]
The printing of the printing layer 11 is performed by a known printing means such as silk printing. Since the single sheet 10 is a flat plate, there is an advantage that printing on the surface can be easily performed without requiring a special apparatus. Positioning holes 12 are arranged at the upper and lower positions of the single sheet 10. In order to use the display unit 13 of each printing layer 11 of the single sheet 10 as a key group, each display unit 13 is thermoformed into a convex shape from the back side by thermoforming described later. The portion thermoformed in a convex shape from the back side of the single sheet 10 becomes the push button 4, and this front side becomes the finger contact portion 9.
[0017]
(Thermoforming)
Next, the molding procedure when the key sheet is molded by pressure molding (pressure molding) will be described. FIG. 3 is an explanatory diagram of a process of forming a concave portion on the single sheet 10 on the protruding back surface side. The printed layer 11 of the single sheet 10 that has been printed is placed on the lower mold 15 so as to be on the lower surface. The single sheet 10 is placed on the lower mold 15 at a position where the thermoforming recess 16 is formed corresponding to the display unit 13 of the printing layer 11. An upper mold 17 that also serves as a heating plate (which may be configured as a separate member) is disposed immediately above the mold 15 so as to correspond to the thermoforming convex portions 16 of the lower mold 15.
[0018]
Positioning of the single sheet 10 on the lower mold 15 is performed by engaging a positioning pin (not shown) with the positioning hole 12 of the single sheet 10. Next, the upper mold 17 is pressed against the single sheet 10 and the single sheet 10 is heated and softened.
[0019]
While supplying compressed air (not shown) of 1 kg / cm ² or less from the upper mold 17 side to the upper surface of the softened single sheet 10, a thermoforming convex portion 16 is provided from below the lower mold 15. The inside air is exhausted and the lower surface side of the single sheet 10 is sucked. By this suction and heating, a plurality of sheet concave portions 14 corresponding to the respective display portions 13 are formed. Thereby, each display part 13 of the single sheet 10 is positioned inside the bottom surface (convex back surface) of the sheet concave part 14, and the opposite surface is the finger contact part 9 of the push button 4, that is, the outer skin of the push button 4. The molded sheet 19 is formed as follows.
[0020]
In addition, this finger contact part 9 is shape | molded according to the shape of the pushbutton 4, and is formed in arbitrary shapes, such as square shape, circular shape, or elliptical shape. The thermoforming of the single sheet 10 is not the above-described pressure forming, but the single sheet 10 which is a thermoplastic synthetic resin is fixed on a mold, and the sheet softened by heating with a heater is sucked into the mold in a vacuum. Vacuum forming may be used. As the thermoforming method for forming the molded sheet 19 from the single sheet 10, various methods may be used as long as various methods are well known and the above-described forming is possible.
[0021]
(Injection molding inside key)
FIG. 4 is an explanatory diagram of a process in which resin is filled into each sheet concave portion 14 formed on the molded sheet 19 by injection molding. The finger contact portion 9 of the molded sheet 19 is inserted and arranged in the cavity recess 22 formed in the cavity 18 of the movable side template 20. The molded sheet 19 is placed on the movable mold plate 20 in a state where the molded sheet 19 is inserted into the cavity recess 22, and the fixed mold plate 25 is pressed against the molded sheet 19 in this state. In a state where the movable side mold plate 20 and the fixed side mold plate 25 are pressure-bonded, a space is formed in each sheet concave portion 14 of the molded sheet 19 by the fixed side mold plate 25 to form a cavity 18.
[0022]
Conventionally, as shown in FIG. 12, the sheet concave portion B is not partly overhanging from the mold. This is because it is necessary to bend the sheet in this portion by a push button operation. For this reason, the finished product was a cause of irregular reflection of this part. The present invention eliminates this and provides an improved push button unit. As shown in FIG. 5, the above-described cavity 18 protrudes from the outer edge 14 a of the sheet concave portion 14 and is provided with a space portion.
[0023]
Molten resin 27 is supplied to the cavity 18 through the gate 26, and the molten resin 27 is projected and filled into the sheet concave portion 14, and a key sheet (molded sheet) is completed as shown in FIG. As shown in FIG. 6, the cavity 18 may be protruded around the outer edge 14 a along the shape of the concave portion 14 to have a concave shape. In this case, the amount of molten resin used can be reduced. Further, the heat welding force of the push button support 35 described later is strengthened because the contact area is widened.
[0024]
In this way, since the molten resin is supplied and solidified across the outer edge 14a of the concave portion 14, the diffused light reflection refracted around the push button 4 when the panel is assembled as the push button 4 is eliminated. The As a result, there is no risk of erroneous operation when the push button 4 is visually operated. In addition, the design is neat and has no visual problems.
[0025]
If necessary, some of the sheet concave portions 14 may be left hollow. When the molten resin 27 supplied through the gate 26 is solidified and then removed from the molds 20 and 25, the key sheet 24 is formed as a key sheet 24 as described above.
[0026]
The part of the molten resin 27 supplied to the cavity 18 becomes the part of the push button 4 after molding. By pressing the finger contact part 9, the convex part of the molten resin 27, the actuator 44 pushes the curved shape part of the mating switching element, Switching operation is performed. As described above, the molten resin 27 is supplied over the outer edge 14a of the concave portion of the cavity 18 to the protruding portion, in other words, to cover the outer edge 14a of the concave portion 14 of the molded sheet 19 from the lower surface.
[0027]
The molten resin filled in the concave portion 14 is arbitrarily selected depending on the characteristics required for a push button such as engineering plastic or synthetic resin elastomer. Preferably, the molded sheet 19 and the injected molten resin 27 are desirably selected from synthetic resin materials that are thermally welded to each other. The key sheet 24 is obtained by supplying the molten resin 27 to the molded sheet 23. The key sheet 24 is cut as a single push button 4 by cutting an excess portion.
[0028]
FIG. 7 is a plan view after the key sheet 24 is cut with a laser beam. The key sheet 24 is cut by fusing along a cutting line 23 with a laser beam by a laser cutting device (not shown). The cutting line 23 has a certain groove width and is cut along the outer periphery of the formed push button 4. Since the shape of the cutting line 23 is controlled by the NC device provided in the laser cutting device, any shape can be selected. However, a part of the cutting line 23 remains without being cut, and the space between the push buttons 4 remains as the connecting portion 21. FIG. 8 shows a state after cutting along the cutting line 23 by the laser cutting device and removing chips, and only the key group 7 connected to the connecting portion 21 is obtained.
[0029]
As shown in FIG. 9, the key group 7 described above is inserted into the moving side mold 31 of the injection mold 30. Molten resin is injected into the cavity 33 between the moving side mold 31 and the fixed side mold 32 through the gate 34. The cavity 33 constitutes a push button support 35 for elastically supporting the key group 7. The push button support 35 is made of a synthetic resin elastic body (elastomer). Preferably, the push button support 35 is selected from materials that are heat-sealed in the injection mold 30 integrally with the key group 7.
[0030]
The key group 7 thus formed and the push button support 35 are assembled together to form the control panel 36. Next, an assembling method for incorporating the control panel 36 into the above-described portable telephone will be described. FIG. 10 is a cross-sectional view showing a state when the control panel 36 is fixed to the case cover 3 of the mobile phone. Each push button 4 of the control panel 36 is inserted and arranged so as to protrude from the opening 8 of the case cover 3.
[0031]
Ribs 40 are formed on the back surface inside the case cover 3 so as to surround each opening 8. The connecting portion 21 of the control panel 36 and the push button support 35 are thermally welded to the end face of the rib 40. In this thermal welding, when ultrasonic vibration energy is applied to the connecting portion 21 and the push button support 35, the ultrasonic welding changes to mechanical vibration at the joining surface of the end surface 41 of the rib 40 and the control panel 36, and friction is caused on the joining surface. Heat is generated, the part is melted and welded, and both are welded.
[0032]
Since the case cover 3 and the control panel 36 are unitized as one unit, and the end face 41 of the rib 40 and the push button support 35 of the control panel 36 are thermally welded, foreign matter can be externally introduced into the electronic device from the outside. , Moisture and the like will not enter. The switching element 44 mounted on the printed circuit board 43 is pressed in the direction P as shown in FIG. 11 via the actuator 42 of the push button 4.
[0033]
At this time, the portion of the push button support body 35 mainly made of a synthetic resin elastic body is elastically deformed as shown in the figure. A part of the circuit of the switching element 44 rises in a curved shape to form a curved portion. The curved portion has a movable contact on the back surface and is elastically deformed like a disc spring.
[0034]
The circuit board is made of epoxy resin or the like, and a fixed contact, a light emitter, a click plate, and the like are provided on the surface. The curved portion of the switching element portion 44 is a part of the click plate. When the push button 4 is pressed, the tip of the actuator 42 contacts and presses the bending portion, and the bending portion is deformed to contact the fixed contact and perform switching. When the finger is released from the push button 4, the push button 4 returns to the original state, and the curved portion also returns to the original state.
[0035]
【The invention's effect】
As described above in detail, by applying the present invention, it is possible to manufacture a push button unit with high confidentiality and no risk of erroneous operation with less man-hours and low cost.
In addition, the switching operation of the push button which is covered with the outer skin and arranged on the back surface becomes stable.
[Brief description of the drawings]
FIG. 1 is a perspective view of a portable telephone device in which the present invention is adopted.
FIG. 2 is a plan view of a printed single sheet serving as a cover of a push button.
FIG. 3 is an explanatory diagram of a process of thermoforming a single sheet into a molded sheet.
FIG. 4 is a cross-sectional view of an injection mold showing a manufacturing process of a key sheet from a molded sheet.
FIG. 5 is a cross-sectional view showing a state in which molten resin is filled in a sheet concave portion.
FIG. 6 is a cross-sectional view showing another embodiment of a state in which molten resin is filled in a sheet concave portion.
FIG. 7 is a plan view of a cut key sheet.
FIG. 8 is a plan view showing a key group in which a plurality of push buttons are connected by a connecting portion.
FIG. 9 is a cross-sectional view illustrating a state in which a control panel is attached to a case cover from a key group.
FIG. 10 is a cross-sectional view showing a state in which the push button unit is attached to the case cover.
FIG. 11 is a cross-sectional view showing a state where a push button attached to a case cover is pressed.
FIG. 12 is a cross-sectional view showing a state of a conventional push button unit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Portable telephone 2 ... Telephone body 3 ... Case cover 4 ... Push button 8 ... Opening part 9 ... Finger contact part 10 ... Single sheet | seat 11 ... Print layer 14 ... Sheet | seat concave part 14a ... Outer edge 15 ... Mold 17 ... Heating plate 19 ... molded sheet 24 ... key sheet 26 ... gate 27 ... molten resin

Claims (2)

In a control panel with sheet forming pushbuttons,
Thermoforming a sheet having a printed layer into an outer skin, and a molded sheet with a concave portion formed,
A molten resin that is stretched and filled by injection molding across the periphery of the outer edge of the concave portion of the molded sheet;
A plurality of push buttons made by cutting the sheet filled with the molten resin;
A pushbutton unit comprising a pushbutton support integrally formed with the pushbuttons, which elastically bends and supports a resin portion formed across the periphery of the outer edge in the recesses of the plurality of pushbuttons. In a control panel with sheet forming pushbuttons,
A step of forming a sheet having a printed layer into a concave shaped sheet by thermoforming;
Inserting the molded sheet into an injection mold and cutting the sheet filled with molten resin across the periphery of the recess and the outer edge of the recess to form a plurality of push buttons;
A process for producing a push button unit comprising: a step of elastically bending and supporting a resin portion formed across the periphery of the outer edge of the recesses of the plurality of push buttons with a push button support, and integrating with the push buttons .

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