JP2008226576A - Key sheet, key unit equipped with it, and manufacturing method of light guide plate of key sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively guide light from a light source to the lower part of a key top to be reflected toward the key top side on the lower side of the key top by being guided; to reduce the thickness of a key sheet; and thereby to reduce the thickness of an apparatus such as a cellular phone using the key sheet. <P>SOLUTION: In this key sheet 20 composed by arranging a plurality of key tops 18 on a key base formed of a resin having transparency, the key base 10 is formed, by insert molding, into a structure having a key top base part 16a used as a base of the key tops 18, and at least a pusher 14a on its front surface and back surface, respectively, by using, as an insert member, a light guide plate 12 having transparency, and having a reflection means 12a at least in a part of the back surface corresponding to parts to be displayed of the key tops 18. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an illuminated key sheet, such as a mobile phone, a PHS, a personal digital assistant (PDA, etc.), a portable audio, a remote controller for home appliances, a key unit including the same, and a guide for the key sheet. The present invention relates to a method for manufacturing an optical plate.

  For example, as a key sheet used in an electronic device such as a mobile phone, a PHS, a portable information terminal (PDA, etc.), a portable audio, a remote controller for home appliances, a key top or the like is made of a predetermined illumination light emitting means (for example, a light emitting diode). ) Is often illuminated. This is because there is an advantage that the key can be easily visually recognized even in a dark place and the operation becomes easy.

The applicant company of the present application has made various proposals regarding such an illuminated key sheet or a key unit in which such a key sheet is assembled to a wiring board or the like by, for example, Japanese Patent Application No. 2006-013232.
FIG. 6 is a sectional view showing a conventional example of a key unit in which such a narrow pitch type key sheet is arranged on a wiring board.
In the drawing, reference numeral 100 denotes a wiring board, which is a wiring film (not shown), a light emitting means for illumination (for example, composed of LED (Light Emitting Diode)) and a metal dome (for example, stainless steel / SUS steel) in which a switch is arranged. 102) on the surface.
104 is a reinforcing plate constituting the key base 107 with the keypads 106, 106,..., Which is made of a transparent resin such as polycarbonate or metal, for example, and has a plurality of keypad arrangement holes 104a in which the keypads 106 are arranged. , 104a,.

The keypads 106, 106,... Fit in the keypad arrangement holes 104a, 104a,... Of the reinforcing plate 104, and the keypad arrangement holes on the outer surface of the keypads 106, 106,. 104a, 104a,... Are fixed to the inner side surfaces thereof, and are reinforced by the reinforcing plate 104 so as to obtain the necessary mechanical strength as the key base 107.
Reference numeral 108 denotes a light-shielding mask sheet (: light-shielding plate) disposed on the key base (particularly when the reinforcing plate 104 is made of transparent resin), and between adjacent key tops (110 and 110) described later. It occupies the area corresponding to the lower side and shields light, and is made of a light-shielding film or a metal thin plate.

Reference numeral 110 denotes a key top, which is fixed to the upper surface of the base portion 106 a of the keypad 106. Reference numeral 106b denotes a pusher portion. The key top is generally made of a transparent resin such as polycarbonate, but from the viewpoint of design, aesthetics, etc., the key top may be made of metal or may have a surface plated with metal.
In JP 2006-318905 A, JP 2006-323843 A, and JP 2006-323843 A, a key base or a main part thereof is formed of a transparent resin and disposed on a side surface of the key base. There is a type in which a light source composed of an LED or the like is arranged, light from the light source is guided by the key base, and reflected to the key top side by reflecting means formed on the key base.
Japanese Patent Application No. 2006-0132232 JP 2006-318905 A JP 2006-323843 A JP 2006-324240 A

However, the conventional key sheet as shown in FIG. 6 has a problem that it is difficult to make the unevenness of the intensity of illumination light uniform.
In other words, there is no means to effectively guide the light generated from the LED that does not appear in the drawing to the bottom of the key top and effectively reflect it from the bottom of the key top to the key top. It is difficult to control without unevenness.
Therefore, it is difficult to make the unevenness of the intensity of illumination light uniform.

Further, the conventional key sheet as shown in FIG. 6 has a problem that it is difficult to reduce the thickness of the key base because it is difficult to reduce the thickness of the key base. This is a problem that cannot be overlooked because it becomes a factor that obstructs the thinning required for mobile phones and the like.
On the other hand, according to the techniques described in JP-A-2006-318905, JP-A-2006-323843, and JP-A-2006-323843, light from a light source is guided by a key base and formed on the key base. Since the reflecting means reflects the light toward the key top, the intensity of the illumination light can be controlled relatively easily. Therefore, it is relatively easy to make the unevenness of the intensity of illumination light uniform.
However, the technology has not been devised to make the key sheet thinner, and this has been a problem that prevents the thinning required for mobile phones and the like, and cannot be overlooked.

  The present invention has been made to solve such a problem. In a key sheet provided with a plurality of key tops on a key base made of a resin having transparency, or a key unit using the key sheet, a light source from a light source is provided. The light is effectively guided to the bottom of the key top so that the light is guided and reflected to the key top side under the key top. Further, the key sheet is made thinner, and the key sheet is An object is to reduce the thickness of a device used, for example, a mobile phone.

  The key sheet according to claim 1 is a key sheet in which a plurality of key tops are provided on a key base made of a resin having transparency. The key base has transparency, and at least the key top on the back surface should be displayed. A light guide plate having a reflecting means in a part corresponding to the part is used as an insert member, and the surface thereof is formed by insert molding in a structure having a key top base part serving as a base of the key top on the back side and at least a presser on the back side. It is characterized by.

The key sheet according to claim 2 is a key sheet in which a plurality of key tops are provided on a key base made of a resin having transparency, the key base has transparency, a reflecting means is formed on the back surface, The key top is formed directly, and a pusher is formed directly on the back surface of the reflecting means of the key base.
A key sheet according to a third aspect is the key sheet according to the first or second aspect, wherein the reflecting means is formed of irregularities formed on a back surface of the key base.

A key sheet according to a fourth aspect is the key sheet according to the first or second aspect, wherein the reflecting means is formed of a reflective coating film formed on the back surface of the key base.
A key unit according to claim 5 corresponds to the key sheet according to claim 1, 2, 3 or 4, the wiring board on which the key sheet is placed, and the key bases of the key sheet on the wiring board. The light emitting part is located on the switching element which is disposed at a position and switched by the operation of the key top on the pad, and the side surface of the key base (including the inner side surface of the hole when a hole is formed in the key base). A light source for illumination arranged in such a manner that light emitted from the light source for illumination is guided by the key base and reflected to the key top side by the reflecting means to illuminate the key top. It is characterized by being made.

  The method of manufacturing a light guide plate according to claim 6 is a method of manufacturing a light guide plate having an unevenness forming a key base or a part of the key base and forming a reflecting means on the back surface, by resin molding using a mold having an uneven surface. The light guide plate is manufactured.

According to the key sheet of claim 1, the key base has a light guide plate having transparency as an insert member, and a structure having a key top base portion and a presser as a base of the key top on the front and back surfaces thereof by insert molding. Since it is formed, the core of the key sheet can be hardened and strengthened.
Therefore, even if it is thin, it is possible to obtain the required strength of the key base.
Therefore, the key base can be thinned, and thus the key sheet can be thinned.

And the light from the light source for illumination can be effectively guided in the plane direction of the key base by the light guide plate which is the core of the key base, so that the light is effectively guided under each key top. It can be reflected and reflected to the key top side by the reflecting means formed on the back surface of the light guide plate.
Therefore, it is easy to control the intensity of light reflected by each key top, and unevenness of the light intensity can be reduced.

According to the key sheet of the second aspect, since the key top is directly formed on the surface of the key base and the pusher is directly formed on the back surface, the key sheet can be made thin.
The light from the illumination light source can be effectively guided in the plane direction of the key sheet by the light guide plate, so that the light can be effectively guided under each key top. The light can be reflected to the key top side by reflecting means formed on the back surface of the light plate.
Therefore, it is easy to control the intensity of light reflected by each key top, and unevenness of the light intensity can be reduced.

According to the key sheet of claim 3, since the reflecting means is formed by the irregularities on the back surface of the key base, the reflecting means consisting of irregularities is naturally formed by forming the key base by resin molding using an uneven mold. Is done.
Therefore, the reflecting means can be formed without providing a process only for forming the reflecting means.

According to the key sheet of the fourth aspect, since the reflecting means is formed on the coating film formed on the back surface of the key base, it can be provided by a simple means of printing the coating film on the back surface of the key base.
According to the key unit of claim 5, since the key unit is configured using the key sheet of any one of claims 1, 2, 3 or 4, the key of any one of claims 1, 2, 3 or 4 is used. The effect of the sheet can be enjoyed.

  According to the method for manufacturing the light guide plate of claim 6, since the mold having the unevenness constituting the reflecting means is used, the reflecting means made of unevenness is naturally formed in the step of simply forming the light guide plate by resin molding, and the reflecting means is No special process for forming is required.

  The key sheet of the present invention and the first one of the key unit using the same basically have a transparent key base, and at least a portion corresponding to a portion to be displayed on the key top on the back surface is provided with a reflecting means. The light guide plate having the insert member as the insert member is formed by insert molding into a structure having at least a pusher on the back surface of the key top base portion serving as the base of the key top on the surface thereof, and using the key sheet of the present invention and this In the second key unit, the key base is basically transparent, the reflecting means is formed on the back surface, the key top is directly formed on the surface, and the back surface of the reflecting means of the key base. The pusher is formed directly on the surface.

Specifically, the light guide plate is made of a hard resin such as polycarbonate and has a very thin thickness of about 0.1 mm to 0.3 mm, for example, about 0.2 mm. The key top base and the presser are made of silicone resin.
Although there is an aspect in which the unevenness formed on the back surface of the light guide plate is used as the reflecting means, there is also an aspect in which a coating film formed on the back surface of the light guide plate, for example, a film made of silver, gold, white ink or the like is used.

  Further, the light guide plate manufacturing method of the present invention is a method of manufacturing a light guide plate having unevenness forming a key base or a part thereof and forming reflection means on the back surface by resin molding using a mold having unevenness on the inner surface. The thickness is preferably 0.1 mm to 1.0 mm, for example, 0.2 or 0.3 mm.

Hereinafter, the present invention will be described in detail based on illustrated embodiments.
FIG. 1 is a view for explaining a first embodiment (first embodiment) of the present invention, where (A) is a sectional view, and (B-1) and (B-2) are key base manufacturing methods. It is sectional drawing which shows these in process order.
First, the key unit 2 will be described with reference to FIG.

Reference numeral 4 denotes a wiring board built in a mobile phone, for example, on the surface of which a wiring film (not shown), a metal dome 6 and an LED (Light Emitting Diode) 8 constituting a light source for illumination are provided. 8p is the light emission part of the LED8. In this embodiment, the LED 8 is provided on the surface of the wiring board 4, but it is not always necessary to do so, and the LED 8 may be attached to the back surface of a case (cover) 24 described later. good.
The metal dome 6 incorporates a switch (not shown) that is turned on when pressed from above by a pusher (14a) described later. A dome sheet for holding the metal dome 6 is also provided on the surface of the wiring board 4, but the illustration is omitted.

Reference numeral 10 denotes a key base, which includes a light guide plate 12, lower resin portions 14 and 14a, and upper resin portions 16 and 16a of the light guide plate 12. The key base 10 has a thickness of 0.2 to 1.0 mm, for example, 0.3 to 0.4 mm.
The light guide plate 12 is made of a resin having transparency and relatively high hardness, such as polycarbonate, and has a thickness of 0.1 to 0.3 mm, for example, 0.2 mm. 12a is an unevenness formed on the back surface of the light guide plate 12 and constitutes a reflecting means. The unevenness 12a may be formed over the entire back surface of the light guide plate 12, but may be formed only in a portion located below or in the vicinity of each key top (18) described later. good.

The height of the light guide plate 12 from the wiring board 4 is substantially the same as that of the light emitting portion 8p of the LED 8, and light generated from the LED 8 is incident on the light guide plate 12 from its side surface. .
The portions 14 and 14a below the light guide plate 12 of the key base 10 are made of, for example, silicone rubber. Of the resin portions 14 and 14a, 14a forms a pusher and is positioned on the metal dome 6. .
The key base 10 is bonded to the surface of the wiring board 4 at a portion 14 of the lower resin portions 14 and 14a other than the pusher 14a.

The parts 16 and 16a above the light guide plate 12 of the key base 10 are made of, for example, silicone rubber, like the lower parts 14 and 14a. Of the resin parts 16 and 16a, 16a is located above the pusher 14a. A key top 18 on which a display (not shown) of characters, numbers, symbols and the like is formed is bonded on the key top base 16a.
The key base 20 and the key top 18 constitute a key sheet 20.
Reference numeral 24 denotes a cellular phone case.

  According to the key unit 2, when light is generated from the light emitting portion 8 p of the LED 8, the light enters the light guide plate 12 that forms the core of the key base 10 from the side surface. Incident light travels in the light guide plate 12 along the plane direction while repeating internal reflection on the front and back surfaces, and a part of the light reaching under each key top 18 is irregularly reflected to the key top 18 side by the irregularities 12a. Then, the display by the key top 18 is illuminated.

Next, a method for manufacturing the key base 10 will be described in the order of steps with reference to FIGS. 1 (B-1) and (B-2).
(1) First, as shown in FIG. 1 (B-1), a key base forming mold 30 comprising a lower mold 30a and an upper mold 30b is prepared, and the light guide plate 12 is inserted into the mold 30. Insert as a thing.
(2) Next, by injecting silicone rubber into the cavities 32a and 32b of the mold 30, as shown in FIG. 1 (B-2), the resin portions 14, 14a, Resin portions 16 and 16a are formed on the upper side, and the key base 10 is completed.

According to the key sheet 20 and the key unit 2 using the key sheet 20, the key base 10 uses the transparent light guide plate 12 as an insert member, and the key top base portion serving as the base of the key top 18 on the front and back surfaces thereof. Since the structure having the 16a and the pusher 14a is formed by insert molding, the core of the key base, that is, the light guide plate 12 can be hardened and strengthened.
Therefore, the key base 10 can be provided with a required strength even if it is thin.
Therefore, the key base 10 can be thinned, and thus the key sheet 20 can be thinned.

The light from the LED 8 constituting the light source for illumination can be effectively guided in the plane direction of the key base 10 by the light guide plate 12 which is the core of the key base 10. The light can be effectively guided, and can be reflected to the key top 18 side by the reflecting means formed of the irregularities 12 a formed on the back surface of the light guide plate 12.
Therefore, it is easy to control the intensity of the light reflected by each key top 18, and the unevenness of the light intensity can be reduced.

2A and 2B are cross-sectional views showing one example of a method for manufacturing the light guide plate 12 of the embodiment shown in FIG.
(A) First, as shown in FIG. 2A, a light guide plate resin molding die 40 including a lower die 40a and an upper die 40b is prepared. On the inner surface of the lower mold 40a of the mold 40, there are formed irregularities 40c for forming irregularities 12a on the back surface of the light guide plate 12. Reference numeral 40 d denotes a cavity of the mold 40.

(B) Next, for example, polycarbonate resin is injected into the cavity 40 d of the mold 40. Thereby, the light guide plate 12 is formed as shown in FIG.
The light guide plate 12 is used for manufacturing the key base 10 whose method is shown in FIGS. 1 (B-1) and 1 (B-2).
According to such a method of manufacturing the light guide plate 12, the irregularities 12a that constitute the reflection means are naturally formed in the process of manufacturing the light guide plate 12, so that a step only for forming the reflection means is not necessary.
Therefore, the number of manufacturing steps of the light guide plate 12 can be reduced.

FIGS. 3A to 3C are cross-sectional views showing another example of the manufacturing method of the light guide plate 12 of the embodiment shown in FIG.
(A) First, as shown in FIG. 3A, a press mold 50 for forming a light guide plate composed of a lower mold 50a and an upper mold 50b is prepared. The inner surface (upper surface) of the lower mold 50a of the mold 50 is formed with irregularities 50c for forming the irregularities 12a on the back surface of the light guide plate 12.
And the flat light-guide plate 12 is inserted between the metal mold | die 50 of the state which fully opened between the lower mold | type 50a and the upper mold | type 50b.

(B) Next, as shown in FIG. 3B, the upper mold 50b is lowered to a predetermined position, and the light guide plate 12 is pressed toward the lower mold 50a by the upper mold 50b, and the lower mold 50a. The light guide plate 12 having the irregularities 12a formed thereon is formed by transferring the irregularities 50a on the rear surface to the rear surface.
(C) Thereafter, as shown in FIG. 3 (C), the upper mold 50b is raised to open the mold 50 as shown in FIG. 3 (A). Then, the completed light guide plate 12 exists on the lower mold 50a, and is ready to be taken out.

Thereafter, the extracted light guide plate 12 is used for manufacturing the key base 10 whose method is shown in FIGS. 1 (B-1) and 1 (B-2).
According to such a method of manufacturing the light guide plate 12, since the irregularities 12 a that constitute the reflection means are naturally formed in the process of manufacturing the light guide plate 12, a process only for forming the reflection means is not necessary. Needless to say, the number of twelve manufacturing steps can be reduced.

FIG. 4 is a cross-sectional view showing a second embodiment (embodiment 2) 2a of the present invention. This Example 2a has a part in common with the first Example 2, and the common part is denoted by the same reference numeral as that in FIG. 1 and description thereof is omitted.
A diode 8 is bonded to the wiring board 4. However, it may be adhered to the back surface of the case (cover) 24.

The key base 10 includes a light guide plate 12 and a pusher 14a formed on the back surface thereof. The light guide plate 12 is made of a resin having transparency and relatively high hardness, such as polycarbonate, and has a thickness of 0.05 to 0.3 mm, for example, 0.2 mm, and is provided with unevenness 12a that constitutes a reflecting means. This is the same as in the first embodiment.
The key top 18 is formed directly on the surface (upper surface) of the key base 10, that is, on the surface (upper surface) of the light guide plate 12.
And, the portion that protrudes outward from the key top groups 18, 18,... Of the key base 10 (only one key top 18 is shown in FIG. 3) is the case (cover) 24. Bonded to the back.

Also in this embodiment 2a, when light is generated from the light emitting portion 8p of the LED 8, the light enters the light guide plate 12 forming the core of the key base 10 from the side surface.
The incident light travels in the light guide plate 12 along the plane direction while repeating internal reflection on the front and back surfaces thereof, and a part of the light reaching under each key top 18 is formed on the side of the key top 18 by the unevenness 12a. The light is diffusely reflected to illuminate the display by the key top 18.

According to this Example 2a, the light from the LED 8 that constitutes the illumination light source can be effectively guided in the plane direction of the light guide plate 12 by the light guide plate 12. Light can be effectively guided, and can be reflected to the key top 18 side by the unevenness 12a forming the reflecting means formed on the back surface of the light guide plate 12.
Therefore, it is easy to control the intensity of the light reflected by each key top 18, and the unevenness of the light intensity can be reduced.
And since the key top 18 is directly formed in the surface of the light-guide plate 12 which comprises the key base 10, and the pusher 14a is directly formed in the back surface of the light-guide plate 12, the key sheet | seat 20 can be made thin.

  In each of the above Examples 2 and 2a, the unevenness 12a is provided on the back surface of the light guide plate 12 as a means for reflecting light toward the key top 18, but the light is reflected on the back surface of the light guide plate 12 as shown in FIG. For example, the coating film 44 may be formed by printing. As the material of the coating film 44, inks such as white, silver and gold are suitable.

  The present invention relates to an illuminated key sheet, such as a mobile phone, a PHS, a personal digital assistant (PDA, etc.), a portable audio, a remote controller for home appliances, a key unit including the same, and a guide for the key sheet. There is a possibility of being used in a method of manufacturing a light plate.

BRIEF DESCRIPTION OF THE DRAWINGS It is for demonstrating the 1st Example (: Example 1) of this invention, (A) is sectional drawing, (B-1) and (B-2) are the manufacturing methods of a key base in order of a process. It is sectional drawing shown. (A), (B) is sectional drawing which shows one example of the manufacturing method of the light-guide plate of the Example shown in FIG. 1 in order of a process. (A)-(C) are sectional drawings which show another example of the manufacturing method of the light-guide plate of the Example shown in FIG. 1 in order of a process. It is sectional drawing which shows the 2nd Example (: Example 2) of this invention. It is sectional drawing which shows another example of a light-guide plate. It is sectional drawing which shows background art.

Explanation of symbols

2, 2a ... key unit, 4 ... wiring board, 6 ... metal dome,
8 ... Light source for illumination (LED), 10 ... Key base, 12 ... Light guide plate,
12a: Concavities and convexities that constitute the reflecting means, 14 ... Parts below the light guide plate,
14a ... pusher, 16 ... part above the light guide plate,
16a ... key top base, 18 ... key top, 20 ... key sheet,
24 ... Case (body), 30 ... Mold for insert molding, 30a ... Lower die,
30b: upper mold, 32a: lower cavity, 32b: upper cavity,
40 ... mold for light guide plate resin molding, 40a ... lower mold, 40b ... upper mold,
40c ... irregularities, 44 ... coating film forming reflecting means,
50 ... Light guide plate pressing mold, 50a ... Lower mold, 50b ... Upper mold,
50c ... irregularities.

Claims (6)

In a key sheet provided with a plurality of key tops on a key base made of a resin having transparency,
The key base has transparency, and a light guide plate having a reflecting means at least on the back surface corresponding to the portion to be displayed of the key top is used as an insert member. A key sheet characterized in that the base part is formed by insert molding into a structure having at least a pusher on the back surface. In a key sheet provided with a plurality of key tops on a key base made of a resin having transparency,
The key base has transparency, the reflecting means is formed on the back surface, and the key top is directly formed on the surface.
A key sheet in which a pusher is directly formed on the back surface of the reflecting means of the key base. The key sheet according to claim 1, wherein the reflecting means is formed of unevenness formed on a back surface of the key base. The key sheet according to claim 1, wherein the reflecting means is formed of a reflective coating film formed on a back surface of the key base. The key sheet according to claim 1, 2, 3 or 4,
A wiring board on which the key sheet is placed;
A switching element disposed at a position corresponding to each key base of the key sheet on the wiring board and switched by operation of the key top on the pad;
An illumination light source disposed such that a light emitting portion is positioned on a side surface of the key base;
Having at least
The key unit, wherein light emitted from the illumination light source is guided by the key base and reflected by the reflecting means toward the key top side to illuminate the key top. In the method of manufacturing a light guide plate having a key base or a rugged portion that forms part of the key base and forms a reflecting means on the back surface,
A method for producing a light guide plate, comprising producing the light guide plate by resin molding using a mold having irregularities on an inner surface.

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