JP2010061956A - Illumination key switch - Google Patents

Abstract

[PROBLEMS] To reduce the decrease in brightness and variation to produce stable brightness, to reduce distortion of a light guide member, to improve durability, and to reduce costs.
An illumination key switch (1) includes a substrate (3) provided with a fixed contact (9) and a movable contact (5) arranged opposite to the fixed contact (9), a light emitter (17) disposed on the back side of the substrate (3), A holding member 11 that covers and holds the movable contact 5 on the substrate 3; a light guide member 15 that is disposed on the back side of the substrate 3 and guides light from the light emitter 17 to the movable contact 5; It is characterized by providing.
[Selection] Figure 1

Description

  The present invention relates to an illumination key switch, and more particularly to an illumination key switch having an illumination function used in various electronic devices such as a mobile phone and a digital camera.

  In general, it is known that an operation key switch used in a mobile electronic device represented by a mobile phone has a structure including a substrate, a metal dome, a presser sheet, a key mat, and a housing. The LED mounted on the substrate plays the role of a backlight. In recent years, it is becoming mainstream to use a combination of an LED and a light guide film (LGF) aiming at cost reduction by reducing the number of LEDs. In addition to the above-described mobile phone, examples of the electronic device include a digital camera, a PDA, an MD, a CD player, and other electronic devices.

  For example, Patent Document 1 is a sheet switch module (lighting key switch), which includes an FPC (Flexible Printed Circuit), a light emitting element, and a light guide sheet, and changes the light path in the vicinity of the periphery of the movable contact. Has a rising part. The light guide sheet is coated on the movable contact through an adhesive or is directly adhered.

Patent Document 2 is a sheet switch module (illuminated key switch), in which a light reflecting portion is provided at a position corresponding to a circuit board, a light source, a sheet material made of a translucent resin film, and a movable contact. . The light guide sheet is configured to cover and hold the movable contact.
JP 2007-53063 A JP 2007-87749 A

  By the way, in the conventional illumination key switch, since both of Patent Document 1 and Patent Document 2 are fixed to the movable contact, the light guide sheet undulates according to the outer shape of the movable contact. There is a problem in that the luminance of the light emitting surface decreases because light from the light emitting element leaks.

  Further, since the light guide sheet is fixed to the movable contact, the light guide sheet is unstablely fixed, which causes a variation in luminance of the light emitting surface. In addition, there is a problem that the light guide sheet may hit the light source and damage the light source.

  In addition, since the light source is attached to the side surface of the light guide sheet, the heights must be matched. This process was inferior in workability and was liable to be displaced. When this misalignment occurs, there is a problem that the luminance of the light emitting surface decreases.

  In addition, when the position of the light guide sheet varies greatly depending on the product, the brightness of the display unit of the electronic device varies, and thus there is a problem that the yield decreases.

  Further, since the structure for fixing the light source is complicated, there is a problem that the cost increases.

  An object of the present invention is to reduce luminance reduction and variation to produce stable brightness, reduce distortion of a light guide member, improve durability, and reduce costs.

  In order to solve the above-described problems, an illumination key switch according to the present invention includes a substrate having a fixed contact and a movable contact disposed opposite the fixed contact, and a pressing member that covers and holds the movable contact on the substrate. And a light emitter disposed on the back surface side of the substrate, and a light guide member disposed on the back surface side of the substrate and for guiding light from the light emitter to the movable contact. It is characterized by.

Moreover, it is preferable that the illumination key switch of this invention is a structure in which the height of the said light-emitting body and a light guide member becomes the same phase in the said illumination key switch.

Moreover, the illumination key switch of the present invention is the illumination key switch,
It is preferable that the light guide member is fixed without interfering with the movement of the movable contact when the movable contact operates.

  In the illumination key switch of the present invention, in the illumination key switch, a light guide hole for guiding light guided to the light guide member to the surface side of the substrate is provided in the substrate. preferable.

Moreover, the illumination key switch of the present invention is the illumination key switch,
It is preferable that the pressing member is subjected to printing that diffuses light.

  In the illumination key switch according to the present invention, it is preferable that a light guide hole for guiding light guided to the light guide member to the outside is provided in the movable contact in the illumination key switch.

In the illumination key switch of the present invention, in the illumination key switch, at least a part of the light guide member includes a prism structure or a printing member for extracting light guided to the light guide member to the surface side of the substrate. It is preferable to provide.

  As can be understood from the means for solving the above problems, according to the present invention, since the light guide member is disposed on the back side of the substrate, the movable contact has an adverse effect on the light path on the light guide member. Since there is not, the fall of the brightness | luminance of a light guide member and variation can be reduced.

  In addition, since the light guide member is disposed on the back side of the substrate, the movement of the movable contact is not hindered. Therefore, the material selectivity of the light guide member is improved, and the transmittance and durability can be improved. .

  Embodiments of the present invention will be described below with reference to the drawings.

  Referring to FIGS. 1 and 2, an illumination key switch 1 according to this embodiment is an operation key switch used in a mobile phone, a digital camera, a PDA, an MD, a CD player, or other mobile electronic devices. The printed circuit board 3 such as PCB (Printed Circuit Board) or FPC (Flexible Printed Circuit) as the substrate according to this embodiment, for example, a switch dome 5 (metal dome or metal click as a movable contact) Spring) is incorporated.

  The switch dome 5 is obtained by processing a plate material of, for example, stainless steel or copper-based metal as a conductive material. Furthermore, it is of a saddle shape having flexibility that can be brought into and out of contact with the contact portion on the substrate 3. The switch dome 5 has a diameter of, for example, 4 mm and a height of, for example, 0.2 mm.

  The printed wiring board 3 is provided with a central contact (central electrode) 9A made of a conductive material on an insulating sheet 7, and an outer peripheral contact (outer peripheral electrode) 9B is annularly provided around the central contact 9A. The central contact 9A and the outer peripheral contact 9B constitute a fixed contact 9 serving as an electrode pair. A circuit is formed on the printed wiring board 3 in a pattern.

  On the printed wiring board 3 described above, the switch dome 5 described above is arranged in alignment with the central contact 9A and the outer peripheral contact 9B of the electrode pair. That is, the switch dome 5 has a contact portion 5A located on the concave side of the top of the switch dome 5 at the center contact 9A in order to turn on / off the conduction between the center contact 9A and the outer peripheral contact 9B. It has flexibility that allows contact and separation, and is mounted with its outer periphery in a bowl shape connected to the outer peripheral contact 9B.

The above-mentioned switch dome 5 is positioned on the base plate 3 by a presser sheet 11 made of a resin sheet such as an insulating rubber sheet, for example, on the convex surface side of the bowl shape.

  Since the presser sheet 11 also serves as a light guide material, it is necessary to select a transparent material. However, a high transmittance is not necessarily required because the light is guided substantially by the sheet thickness.

  The presser sheet 11 includes, for example, a sheet material 11A having a resin sheet such as transparent PET (polyethylene terephthalate) as a base material, and an adhesive layer made of, for example, an acrylic or silicon-based adhesive material applied to one surface of the sheet material 11A. 11B, and the adhesive layer 11B that holds the switch dome 5 is the same as the adhesive that is applied to the surface of the substrate 3 as it is.

  Further, the surface of the presser sheet 11 is subjected to diffusion printing 13 within a range where the switch dome 5 is pressed.

  The switch dome 5 is arranged so as to cover the center contact 9A substantially in the center, that is, the center contact 9A is located on the center direction side of the bowl-shaped concave surface. That is, when the top of the dome 5 for the switch is pressed downward, the vicinity of the top is reversed and depressed so that the contact 5A contacts the central contact 9A and is conductive. .

  Further, for example, a light guide sheet 15 as a light guide member is disposed on the back surface side of the substrate 3 so that the optical path is not obstructed by the switch dome 5. Furthermore, at least a part of the light guide sheet 15 is provided with a prism structure 15A for light extraction or a printing member, and the light guide sheet 15 is provided with an incident surface 15B for incident light. Yes.

  Therefore, by arranging the light guide sheet 15 on the back surface side of the substrate 3, the light guide sheet 15 is fixed without being interfered with the movement of the switch dome 5 when the switch dome 5 is operated. It will be.

  Further, on the back surface side of the substrate 3, for example, a light emitting element 17 as a light emitter (light source) that emits light so as to enter the incident surface 15 </ b> B of the light guide sheet 15 is provided according to the height of the light guide sheet 15. It has been. That is, the light guide sheet 15 and the light emitting element 17 are provided at a substantially constant height so as to have the same phase. The light guide sheet 15 is preferably a transparent urethane resin.

  The substrate 3 is provided with a light guide hole 19 that guides the light guided to the light guide sheet 15 to the surface side of the substrate 3. For example, the light reflected by the prism structure 15 </ b> A passes through the light guide hole 19 and is guided to the pressing sheet 11 or the switch dome 5 on the surface side of the substrate 3. A light guide hole 21 through which light passes is provided at the top of the switch dome 5.

  Further, the illumination key switch 1 is always urged upward in FIG. 1 by an urging means such as a spring (not shown), for example, a key mat 23 as an actuator for pushing the switch dome 5 above the presser sheet 11. It is arranged at a position separated from the printed wiring board 3.

  The key mat 23 is an insulating sheet formed by attaching a hard plastic such as polycarbonate to a silicon rubber or urethane sheet. Further, the key mat 23 is provided with a push button portion 25 at a portion aligned with the presser sheet 11, and a protrusion 27 is provided at the center of the back surface of the push button portion 25. It is comprised so that it may touch and touch the top of the head.

  In addition, the periphery of the push button portion 25 in the key mat 23 is extremely thin, and the push button portion 25 is configured to be able to move slightly in the vertical direction with respect to the surface of the key mat 23. .

  The key mat 23 is provided inside the housing 29, and is assembled using a positioning hole or the like so that the protrusion 27 of the key mat 23 is directly or indirectly positioned directly above the switch dome 5. It is done.

  With the above-described configuration, the illuminated key switch 1 of this embodiment has the protrusion 27 provided on the back side of the push button portion 25 when the push button portion 25 of the key mat 23 is pushed by a human finger or the like. 11 near the top of the top of the switch dome 5 is pushed down. The vicinity of the top of the dome 5 for the switch is displaced and deformed, and the switch dome 5 is pushed in so as to be inverted and recessed. As a result, the contact portion 5A of the switch dome 5 comes into contact with the center contact 9A, and the center contact 9A and the outer peripheral contact 9B, which are paired electrodes, are electrically connected to each other via the switch dome 5 and illuminated. The key switch 1 is turned on.

  At this time, the switch dome 5 is inverted and recessed near the top of the switch dome 5, so that a click feeling can be obtained during this deformation. Further, when the finger or the like is released from the push button portion 25, the switch dome 5 returns to the original position of the initial shape by its own elastic force, and there is an electrical connection between the central contact 9A and the outer peripheral contact 9B as the paired electrodes. The illumination key switch 1 is turned off.

  When the light emitting element 17 is energized to emit light, the light of the light emitting element 17 is propagated from the incident surface 15 </ b> B of the light guide sheet 15 into the light guide sheet 15. At this time, since the height of the light guide sheet 15 is in the same phase as that of the light emitting element 17, the light guide sheet 15 can reduce luminance reduction and variation without hindering the optical path. That is, light is emitted with stable and strong luminance with little variation in the range of the prism structure 15A provided in advance of the light guide sheet 15.

  The light extracted to the light guide sheet 15 propagates through the light guide sheet 15 and passes through the light guide hole 19 opened in the substrate 3 and the light guide hole 21 opened at the top of the switch dome 5. The key portion can be made to emit light uniformly by the diffusion printing 13 applied to the surface of the presser sheet 11 after passing through and entering the presser sheet 11.

  Since the light guide sheet 15 is not arranged to obstruct the movement of the switch dome 5, it is not necessary to select a soft material, so that the material selectivity is improved and the transmittance and durability of the light guide sheet 15 are improved. Can do.

  As described above, by disposing the light guide sheet 15 on the back surface side of the substrate 3, it is possible to reduce a decrease in brightness and variations.

  Next, in order to investigate the effect of the illumination key switch 1 of the above embodiment, an example based on the configuration of this embodiment was created, and a comparative example was created to compare with this example. . In addition, the same code | symbol is attached | subjected to the same member in an Example and a comparative example, detailed description is abbreviate | omitted, and a different point is mainly demonstrated in detail.

  In the illuminated key switch 31 of the comparative example, as shown in FIG. 2, the light guide sheet 35 covers the outer peripheral surface of the switch dome 5 via the spacer 33 and presses the switch dome 5. It is the composition which is. In addition, the spacer 33 and the light guide sheet 35 are attached by adhesive layers 37 and 39.

  In Examples and Comparative Examples, transparent urethane was used for the light guide sheets 15 and 35, and transparent PET was used for the presser sheet 11.

With respect to the above examples and comparative examples, as shown in FIG. 3, the light emitting surfaces of the light guide sheets 15 and 35 are divided into nine sections (1) to (9), and the luminance is measured. The luminance at the measurement positions in the sections (1) to (9) and the distribution thereof were evaluated. The results are as shown in Table 1. The unit of luminance is “cd / m ² ”.

  As can be seen from Table 1, the comparative example had lower luminance and greater variation than the examples. This is because the switch dome 5 obstructs the optical path of the light guide sheet 35. The embodiment has higher luminance and less variation than the above comparative example.

  From the above, the illumination key switch 1 of this embodiment has the following effects.

(1) Since the light guide sheet 15 is disposed on the back side of the substrate 3 and the height of the light guide sheet 15 is set to the same phase as the light emitting element 17, the switch dome 5 has an adverse effect on the light path with respect to the light guide sheet 15. Therefore, it is possible to reduce the luminance reduction and variation of the light guide sheet 15. Further, since the light guide sheet 15 does not match the outer shape of the switch dome 5, the manufacture becomes easy and the cost can be reduced.

(2) Since the light guide sheet 15 is arranged on the back side of the substrate 3 and the height of the light guide sheet 15 is set to the same phase as the light emitting element 17, the switch dome 5 has an adverse effect on the light path with respect to the light guide sheet 15. Therefore, the material selectivity of the light guide sheet 15 is increased, and the transmittance and durability can be improved.

It is sectional drawing of the illumination key switch of embodiment of this invention. It is sectional drawing of the illumination key switch of a comparative example. It is state explanatory drawing of the brightness | luminance measurement in the illumination key switch of an Example and a comparative example.

Explanation of symbols

1 Illuminated key switch (in this embodiment)
3 Printed circuit board (board)
5 Dome for switch (movable contact)
5A Contact part 7 Insulation sheet 9 Fixed contact 9A Center contact (center electrode)
9B Peripheral contact (peripheral electrode)
11 Presser sheet (presser member)
11A Sheet material 11B Adhesive layer 13 Diffusion printing 15 Light guide sheet (light guide member)
15A Prism structure (or printing member)
15B incident surface 17 light emitting element (light emitting body; light source)
19 Light guiding hole (of substrate 3)
21 Light guiding hole (of switch dome 5)
23 Key mat 25 Push button part 27 Projection part 29 Case 31 Illuminated key switch (for comparison example)
33 Spacer (comparative example)
35 Light guide sheet (for comparative example)
37,39 Adhesive layer

Claims (7)

  A substrate having a fixed contact and having a movable contact disposed opposite to the fixed contact, a pressing member for covering and holding the movable contact on the substrate, a light emitting element disposed on the back side of the substrate, and the substrate And a light guide member for guiding the light from the light emitting element to the movable contact.   2. The illuminated key switch according to claim 1, wherein the light emitting element and the light guide member have the same height.   3. The illuminated key switch according to claim 1, wherein the light guide member is fixed without interfering with the movement of the movable contact when the movable contact is operated.   4. The illuminated key switch according to claim 1, wherein a light guide hole for guiding light guided to the light guide member to the surface side of the substrate is provided on the substrate.   5. The illumination key switch according to claim 1, wherein a light guide hole for guiding light guided to the light guide member to the outside is provided in the movable contact.   The illumination key switch according to any one of claims 1 to 5, wherein the pressing member is printed to diffuse light.   The prism structure or the printing member for taking out the light guided by the light guide member to the surface side of the substrate is provided on at least a part of the light guide member. Illuminated key switch as described in.

Images