JP2009231173A - Wiring board module and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting structure of electronic components which have smaller illumination unevenness on a rubber sheet and are reliable. <P>SOLUTION: A key switch mounting section 10 comprises an FPC 13 forming circuit layers on both sides, an LED 12 mounted on an end of the FPC 13, a light guide plate 17 arranged over the FPC 13 and having a light-extracting pattern 25, the rubber sheet 15 for supporting input keys 11, a dome support sheet 19 arranged under the FPC 13 and having a convex metal dome 18 at a lower part, and a fixed support plate 21 extending at a lower part of the dome support sheet 19 and having a projection section 21a. The input keys 11 are illuminated by light extracted from the light guide plate 17, but their illumination unevenness is lessened because they are not influenced by unevenness of the metal dome 18. Further, their reliability is improved since a projection section for improving click feeling is not arranged on the light guide plate 17. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wiring board module mounted on a portable terminal, a PDA, a personal computer or the like, and an electronic apparatus including the wiring board module.

Conventionally, as a structure of a key switch part of an electronic device such as a portable terminal, a structure in which a key is illuminated with a backlight has been proposed.
For example, in Patent Document 1, as shown in FIG. 5, the light emitted from the light emitting element 290 is guided to the side by total reflection through the light guide plate 220, and the light is irregularly reflected at an intermediate portion, thereby forming a film. Through 247, the one configured to illuminate the key button 245 is disclosed. In this structure, when the key button 245 is pressed, the protrusion 240 causes the metal dome 275, which is a dome-shaped contact member, to be recessed downward, so that the switch 265 on the printed circuit board 260 is turned on.

With the structure of the conventional key switch portion, the key button 245 is illuminated, so that the user can clearly grasp the numbers, symbols, etc. of the key button 245 even in a dark place, and the metal dome 275 is provided by the protrusion 245. It is possible to exhibit excellent functions such as improving the sense of clicking by pressing.
Patent Document 2 also discloses a similar structure.
JP 2006-324240 A JP 2005-268165 A

  However, the conventional key switch structure has a problem that the key button 245 has uneven illumination. In the technique of Patent Document 1, in order to cause irregular reflection of light, a small uneven pattern is formed on the lower surface of the light guide plate 220 around the protrusion 240 and the protrusion 240 to diffuse light as uniformly as possible. However, it is considered that the key button 245 is illuminated by the light that passes through the light guide plate 220 and the protrusion 240 and is reflected from the metal dome 275.

  Further, when the key button 245 is pressed, stress concentrates in the vicinity of the joint between the light guide plate 220 and the protruding portion 240. Therefore, if the pressing force is large, the light guide plate 220 is broken or the protruding portion 240 is peeled off. There was a risk of impairing reliability. On the other hand, if the protrusion 240 is eliminated, the click feeling is reduced.

  An object of the present invention is to provide a highly reliable wiring board module in which illumination unevenness with respect to an irradiated region is small.

In the wiring board module of the present invention, a plate-shaped light irradiator capable of irradiating light in a plane direction is disposed above a flexible printed wiring board on which a circuit layer is formed, and further below the flexible printed wiring board. Further, a downwardly convex dome-shaped contact member and a dome support sheet for supporting the contact member are arranged.
Examples of the plate-shaped light irradiator include a light guide plate that guides light of a light emitting element to the inside by total reflection, an organic EL panel, and an inorganic EL panel.

Thereby, since the flexible printed wiring board is interposed between the plate-shaped light irradiation body and the dome-shaped contact member, the light extracted from the plate-shaped light irradiation body in the surface direction by irregular reflection is the dome-shaped contact point. Irradiation unevenness in the irradiated area can be reduced without being affected by the member or the dome support sheet.
Further, even when a protrusion for denting the dome-shaped contact member is provided in order to improve the click feeling, the protrusion is not provided on the plate-shaped light irradiation body. Therefore, problems such as destruction of the plate-shaped light irradiator are not caused, and the reliability can be improved.

  When a rubber sheet is pressed by providing a fixed support plate for supporting each member and providing a protrusion on the fixed support plate below the center portion of the contact member, the center of the dome-shaped contact member is The click feeling is improved by coming into contact with the protrusion. In addition, as described above, since it is not necessary to provide a protrusion on the plate-shaped light irradiator, the reliability can be improved.

In the present invention, the circuit layer may be formed on both surfaces of the flexible printed wiring board (double-sided circuit type), or may be formed only on one side of the flexible printed wiring board (single-sided circuit type). When using a single-sided circuit type flexible printed wiring board, it is preferable that the edge part is bent. By placing the light emitting element on the circuit layer that is bent and directed upward, the light emitting element can be caused to emit light using the circuit layer of the flexible printed wiring board.
Using only a single-sided circuit type flexible printed wiring board, which is less expensive than the double-sided circuit type, reduces the cost compared to providing a double-sided circuit type flexible printed wiring board or a separate substrate for sending signals to the light emitting element. While reducing, functions equivalent to those can be exhibited, and cost merit can be obtained.

  A rubber sheet having an input key attached to a portion located above the dome-shaped contact member is further provided above the plate-shaped light irradiator, so that the input key is illuminated by light extracted from the plate-shaped light irradiator. It will be. Therefore, a wiring board module with little illumination unevenness in the input key or the display member disposed above the input key can be obtained.

  An electronic apparatus according to the present invention includes the above-described wiring board module, and includes a portable terminal, a PDA, a personal computer, and the like. Thereby, an electronic device with small illumination unevenness with respect to the irradiated region (for example, an input key) and high reliability can be obtained.

  According to the wiring board module or the electronic apparatus of the present invention, it is possible to improve the reliability while suppressing uneven illumination on the irradiated region.

(Embodiment 1)
FIG. 1 is a perspective view schematically showing the structure of a portable terminal (electronic device) according to an embodiment of the present invention. FIG. 2 is a plan view showing the configuration of the input unit of the mobile terminal according to the embodiment.
As shown in FIGS. 1 and 2, the mobile terminal 1 has a display unit 3 for displaying various information, an input unit 4 for inputting items to be transmitted or displayed, and an input unit 4. And a hinge portion 5 that rotatably supports the display portion 3.

The display unit 3 is provided with a display device 6 using a liquid crystal display panel, and a speaker 8 disposed at an outer end facing the hinge unit 5 with the display device 6 interposed therebetween.
The input unit 4 includes a key switch mounting unit 10 on which a plurality of input keys 11 (rubber sheets) for inputting transmission or display items as numbers, characters, symbols, and the like, and a hinge unit sandwiching the key switch mounting unit 10 5 and a microphone 9 disposed at the outer end facing the 5. In addition, two LEDs 12 are arranged at the position of the broken line shown in FIG. 2, and the illuminated region Rlm including the input key 11 and its surrounding region through a light guide plate described later by light emitted from the LED 12. Is now illuminated.

  FIG. 3 is a longitudinal sectional view taken along line III-III shown in FIG. 2, and shows the configuration of the key switch mounting portion 10 including the wiring board module of the present invention. As shown in the figure, the key switch mounting portion 10 is disposed above the FPC 13, the FPC (flexible printed wiring board) 13 having circuit layers formed on both sides, the LED 12 mounted on the end of the FPC 13, and the FPC 13. In addition, a light guide plate 17 that is a plate-shaped light irradiator, a rubber sheet 15 (rubber sheet) that is disposed above the light guide plate 17 and supports the input key 11, and a dome that protrudes downward from the FPC 13 A dome support sheet 19 having a portion Rd, a metal dome 18 as a dome-shaped contact member attached to the dome support sheet 19, and a fixed support plate 21 extending below the dome support sheet 19 are provided.

The light guide plate 17 takes light emitted from the LED 12 from a light intake end Li (light intake portion) facing the LED 12, totally reflects the light inside, and guides light from the light extraction portion Lo in a plane direction. It is configured to take out. In the present embodiment, the back side of the region where the light extraction pattern 25 made of a dot pattern is formed is the light extraction portion Lo. Therefore, the light guide plate 17 is made of a translucent material such as polycarbonate resin, acrylic resin, cycloolefin resin, urethane resin, silicon resin, or PET resin. Further, the thickness of the light guide plate 17 is preferably about 0.025 mm to 0.5 mm so that light can pass through and bend when the input key 11 is pressed.
The light extraction pattern of the present invention is not limited to the irregular reflection pattern, and a diffraction pattern may be used. Moreover, even if it is a diffuse reflection pattern, it is not limited to a dot pattern, The solid pattern which solid-printed the light-scattering agent from which a reflectance differs from a foundation | substrate may be sufficient.

On the lower surface of the light guide plate 17, a light extraction pattern 25 composed of a dot pattern is formed in a region located below the input key 11, and light transmitted through the light guide plate 17 is diffusely reflected by the light extraction pattern 25. The illuminated area Rlm of the upper input key 11 is illuminated. As a method for forming the light extraction pattern 25, a light scattering agent made of a resin (acrylic resin, urethane resin, silicon resin, etc.) having a refractive index different from that of the light guide plate 17 is applied to the dome support sheet by screen printing, inkjet, or the like. There are a method of applying to the surface, forming fine unevenness by embossing, sandblasting, laser, etc., a method of doping with a dopant that changes the refractive index, a method of bonding sheets, etc. Any method may be adopted.
The light extraction pattern 25 may be formed on any of the upper surface, the lower surface, and the inside of the light guide plate 17.

In the present embodiment, the dimensions of the dots of the light extraction pattern 25 made of a dot pattern are, for example, a height of at most about 0.05 mm and a diameter of at most about 0.5 mm. In the present embodiment, the brightness of each input key 11 increases by increasing the number of dots in the light extraction pattern 25, increasing the size of the dots, or decreasing the pattern interval as the distance from the light intake portion Li increases. The thickness is made as uniform as possible.
When the above-described solid pattern is used as the light extraction pattern instead of the dot pattern, a large number of light scattering agents having a diameter of at most about 0.5 mm may be printed. The brightness of each input key 11 can be made uniform as much as possible by increasing the number of keys, increasing the size of the light scattering agent, or changing the light scattering rate of the light scattering agent.

  As shown in the enlarged view at the lower left of FIG. 3, the FPC 13 exposes a base film 31, a circuit layer 32 provided on both surfaces of the base film 31, and a part of the circuit layer 32 and covers the other parts. And a through-hole conductor layer 34 that connects the upper and lower circuit layers 32 to each other.

As a material of the base film 31, a polyimide film having a thickness of about 12.5 μm to 50 μm is used. Not only a polyimide film but also a polyester film, a glass epoxy film, or the like can be used.
The material of the circuit layer 32 and the through-hole conductor layer 34 is generally copper, but is not limited to this.

  As the cover lay 33, a film cover lay made of the same material as the base film 31, a cover coat ink formed by printing a liquid epoxy resin ink, or a resin such as epoxy, acrylic, polyimide, or polyurethane is used. There is a photosensitive coverlay, and any of them may be used. In the present embodiment, a film coverlay using a polyimide film is used. And it forms by sticking the polyimide film processed with the metal mold | die etc. with a board | substrate with a thermosetting adhesive.

  A switch circuit Sc including a central portion 32a and an outer circle portion 32b is formed in a region located above the metal dome 18 in the lower circuit layer 32. The central portion 32a and the outer circle portion 32b of the circuit layer 32 are normally in a non-conductive state, but when the metal dome 18 comes into contact with the central portion 32a and the outer circle portion 32b, the conductive portion is brought into a conductive state.

  The metal dome 18 is generally formed by pressing a SUS thin film, but a thin film of another metal such as copper or copper alloy may be used. The film thickness of the metal dome 18 is, for example, 0.01 mm to 0.1 mm.

  The dome support sheet 19 is also referred to as a “dome sheet”. Generally, by attaching the metal dome 18 to a resin sheet, the portion in contact with the metal dome 18 (dome portion Rd) is deformed into a dome shape. To do. However, the metal dome 18 may be attached to the dome portion Rd of the dome support sheet 19 on which the dome portion Rd is formed from the beginning. A typical height of the dome portion Rd of the dome support sheet 19 is about 0.15 mm to 0.5 mm.

  A spacer 22 made of PET resin having a thickness of, for example, about 0.01 mm to 0.1 mm is attached below the dome support sheet 19 by lamination. The spacer 22 provides a gap between the metal dome 18 and the lower surface of the FPC 13 so that the metal dome 18 can be vented.

  The LED 12 has a light emitting surface on the side surface, and has an electrode for transmitting and receiving power and signals on the lower surface. The LED 12 is installed on an end portion of the FPC 13 and emits light by power and a signal supplied from a circuit layer above the FPC 13, and the emitted light enters the light intake end Li of the light guide plate 17 from the side surface. In the present embodiment, two LEDs 12 are used, but only one or three or more may be used. Further, the arrangement location of the LED 12 is not limited to the site in the present embodiment.

The fixed support plate 21 supports the rubber sheet 15, the light guide plate 17, the LED 12, the FPC 13, the dome support sheet 19, the spacer 22, and the like, and is connected to the dome support sheet 19 through an adhesive layer 23. In the present embodiment, the FPC 13, the metal dome 18, the dome support sheet 19, the spacer 22 and the like are fixed to each other by, for example, an adhesive. And the center part of the metal dome 18 in the fixed support plate 21, that is, the part located below the top of the dome is a protruding part 21a protruding upward. The fixed support plate 21 is made of a resin such as an ABS resin in addition to a metal such as SUS or Mg alloy.
Instead of the adhesive layer 23, the rubber sheet 15, the light guide plate 17, the LED 12, the FPC 13, the dome support sheet 19, the spacer 22, and the like may be fixed to the fixed support plate 21 with fixing pins.

  In the present embodiment, the protruding portion 21a is integrally provided with the fixed support plate 21 by pressing or injection molding. However, the protruding portion 21a is separately welded to a cylindrical member, brazed, coated with an adhesive, printed with resin, or the like. It may be provided. Unlike the conventional structure (see FIG. 5), optical functions such as diffused reflection and diffraction of light are not necessary for the protrusion 21a of the present embodiment, so the selection range of structure and manufacturing method is wide.

  3 and FIG. 3, when the input key 11 is pressed, the rubber sheet 15, the light guide plate 17, the FPC 13, and the dome support sheet 19 are bent, and the metal dome 18 and the dome support sheet 19 are moved. The metal dome 18 and the center portion 32a and the outer circle portion 32b of the circuit layer 32 come into contact with each other. Thereby, the switch circuit Sc of the circuit layer 32 is turned on, and when the input key 11 is stopped, the switch circuit Sc is turned off.

  The protrusion 21a is not necessarily required, and the metal dome (or the dome support sheet as in the present embodiment) may contact the flat fixed support plate when the input key is pressed. By providing, there is an advantage that the click feeling is enhanced.

  The electronic component mounting structure according to the above-described embodiment or modification includes a circuit board module in which a dome support sheet 19 provided with a metal dome 18 is mounted on the FPC 13, a circuit board module in which a fixed support board 21 is added, and The wiring board module to which the LED 12 and the light guide plate 17 are added, and the wiring board module to which the input key 11 and the rubber sheet 15 are further added can be integrated.

According to the key switch mounting portion 10 including each wiring board module of the present embodiment, the following operational effects are obtained.
First, since the metal dome 18 that is a dome-shaped contact member exists below the FPC 13 and the light guide plate 17 that is a plate-shaped light irradiator exists above the FPC 13, the light guide plate 17 The FPC 13 is interposed between the metal dome 18 and the metal dome 18. Therefore, the light irradiated from the light guide plate 17 to the input key 11 (or the display sheet disposed above the input key 11) by irregular reflection is not affected by the uneven shape or color unevenness of the metal dome 18, Variations in illumination can be reduced.

  Moreover, although the protrusion part 21a for denting the metal dome 18 is provided in order to improve a click feeling, since the metal dome 18 has a shape protruding downward, the protrusion part 21a is not provided on the light guide plate 17. Also good. Therefore, the light guide plate 17 is not damaged as in the conventional structure shown in FIG. 5, and the reliability can be improved.

  Then, by providing the protruding portion 21a below the metal dome 18 (a part of the fixed support plate 21 in the present embodiment), the protruding portion 21a needs to have a function such as light irregular reflection as in the conventional structure. Therefore, a mechanically reliable structure can be adopted.

(Modification)
FIG. 4 is a longitudinal sectional view showing the configuration of the key switch mounting unit 10 according to a modification of the above embodiment. In this modification, only members (see FIG. 3) having a structure different from that of the embodiment will be described, and members having the same structure as the embodiment will be denoted by the same reference numerals as those in FIG. To do.

  In this modification, an FPC (flexible printed wiring board) 13 in which a circuit layer is formed only on one side (in this embodiment, the lower side) is used as the FPC 13. In this case, with the structure shown in FIG. 3, there is no circuit layer below the LED 12. Therefore, the FPC 13 is folded so that the circuit layer of the FPC 13 is connected to the electrode on the lower surface of the LED 12.

Also in this modification, the dome support is provided with the input key 11 and the rubber sheet 15 disposed above the light guide plate 17 and the metal dome 18 which is disposed below the FPC 13 and is a convex dome-shaped contact member. By providing the sheet 19 and the fixed support plate 21 extending below the dome support sheet 19, the same operational effects as those of the embodiment can be exhibited.
When the double-sided circuit type FPC is used as in the above-described embodiment, it is not necessary to bend the end portion and the assembly is simplified. However, there is a disadvantage that the board cost is higher than that of the single-sided circuit type FPC. .
Further, a substrate or the like for sending a signal to the light emitting element may be provided separately as in the conventional structure shown in FIG. 5 without bending the single-sided circuit type FPC. Since there is no need to provide a cost merit.

(Other embodiments)
As the plate-shaped light irradiator of the present invention, the light guide plate 17 that receives the light emitted from the LED 12 is provided in the above-described embodiment and modification. A structure such as an inorganic EL panel may be used.

  The structure of the embodiment of the present invention disclosed above is merely an example, and the scope of the present invention is not limited to the scope of these descriptions. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  The wiring board module of the present invention can be used for an electronic device equipped with a rubber sheet, such as a portable terminal, a PDA, and a personal computer.

It is a perspective view which shows roughly the structure of the portable terminal which concerns on embodiment of this invention. It is a top view which shows the structure of the input part of the portable terminal which concerns on implementation. It is a longitudinal cross-sectional view of the key switch mounting part in the III-III line shown in FIG. It is a longitudinal cross-sectional view of the key switch mounting part which concerns on the modification of embodiment. It is a longitudinal cross-sectional view which shows the conventional mounting structure described in patent document 1.

Explanation of symbols

1 Mobile terminal (electronic equipment)
DESCRIPTION OF SYMBOLS 3 Display part 4 Input part 5 Hinge part 6 Display apparatus 8 Speaker 9 Microphone 10 Key switch mounting part 11 Input key 12 LED
13 FPC (Flexible Printed Circuit Board)
DESCRIPTION OF SYMBOLS 15 Rubber sheet 18 Metal dome 19 Dome support sheet 21 Fixed support plate 21a Protrusion part 25 Light extraction pattern 31 Base film 32 Circuit layer 32a Center part 32b Outer circle part 33 Coverlay 34 Through-hole conductor layer Rlm Illuminated area Rd Dome part Li light intake end (light intake part)
Lo light extraction unit Sc switch circuit

Claims (7)

A flexible printed wiring board having a circuit layer formed on at least one side;
A plate-shaped light illuminator disposed above the flexible printed wiring board and capable of extracting light in a plane direction;
A dome-shaped contact member that is disposed below the flexible printed wiring board and protrudes downward, and a dome support sheet that supports the contact member;
A wiring board module comprising: The wiring board module according to claim 1,
A fixed support plate for supporting the flexible printed wiring board, the plate-shaped light irradiation body, and the dome support sheet;
A wiring board module, wherein a protrusion protruding upward is provided at a portion of the fixed support plate located below the central portion of the contact member. The wiring board module according to claim 1 or 2,
The said plate-shaped light irradiation body is a wiring board module which is a light-guide plate which guides the light emission from a light emitting element inside, or an organic EL panel or an inorganic EL panel. In the wiring board module as described in any one of Claims 1-3,
The circuit board module is a wiring board module formed on both surfaces of a flexible printed wiring board. In the wiring board module as described in any one of Claims 1-3,
The circuit layer is formed on only one surface of a flexible printed wiring board, and the end portion of the flexible printed wiring board is bent. In the wiring board module according to any one of claims 1 to 5,
The wiring board module further provided with the rubber sheet | seat which was arrange | positioned above the said plate-shaped light irradiation body, and the input key was attached to the site | part located above the said dome-shaped contact member.   The electronic device which has a wiring board module as described in any one of Claims 1-6.

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