JP2010034008A - Light guide sheet switch unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide sheet switch unit capable of preventing that part of a place corresponding to a light-emitting element on a light guide plate emits light in a spot form, and illuminating on the sheet switch brightly and uniformly. <P>SOLUTION: In the light guide sheet switch unit 20 with a substrate 21, the sheet switch 22 arranged on this substrate 21, the light guide plate 23 mounted on the substrate 21 so as to cover on this sheet switch 22, and the light-emitting element 24 arranged toward one end of an outer peripheral part of this light guide plate 23, as for the light guide plate 23, a thick-walled light-incident part 23b is formed on the outer peripheral part opposed to the light-emitting element 24, and the lower surface of this light-incident part 23b is bonded on the substrate 21 via a light shielding member 33. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light guide sheet switch unit that constitutes an operation input unit of various electronic devices.

  2. Description of the Related Art Conventionally, an operation input unit of a thin electronic device such as a mobile phone or a portable information terminal is often configured using a light guide sheet switch having an illumination function. Such a light guide sheet switch includes a sheet switch composed of a plurality of key switches placed on a substrate, a light guide plate disposed on the sheet switch, and a light source disposed on one end of the light guide plate ( The light emitting element is a unit configuration (see Patent Documents 1 and 2).

  FIG. 5 shows an example of a cross-sectional structure of a sheet switch unit having a light guide function. The light guide sheet switch unit 10 includes a sheet switch 12 disposed on a substrate 11, a light guide plate 13 covering the sheet switch 12, and a light emitting element 14 placed toward the outer periphery of the light guide plate 13. And. The sheet switch 12 includes a base portion 15 on which a fixed contact 16 and a wiring pattern are formed, a movable contact 17 disposed on the fixed contact 16, and a fixed contact on the base portion 15. Sheet material (not shown).

The light guide plate 13 is integrally formed by a light guide main body portion 13 a covering the sheet switch 12 and an outer peripheral portion 13 b for supporting the light guide main body portion 13 a on the substrate 11. And the light emitted from the light emitting element 14 arranged toward one end of the outer peripheral portion 13b is guided to the light guide main body portion 13a, so that the entire sheet switch 12 is illuminated uniformly.
Japanese Patent Laid-Open No. 10-340612 JP 2001-84822 A

  In the light guide sheet switch unit 10 having the above structure, since the outer peripheral portion 13b of the light guide plate 13 facing the light emitting element 14 receives the strongest light, this portion emits light in a spot manner, and the light guide main body portion. The luminance difference from 13a becomes large. Further, the light guide plate 13 presses the movable contact 17 of the sheet switch 12 disposed below by pressing the upper surface of the light guide main body 13a. A gap is likely to occur between the outer peripheral portion 13b and the bottom surface of the outer peripheral portion 13b. For this reason, every time the pressing operation is performed, there is a problem that light emitted from the light emitting element 14 enters the sheet switch 12 side, and this portion emits light in a spot manner. As described above, when a spot-like light emission phenomenon occurs in part, light does not reach every corner of the light guide main body 13a, which causes a decrease in overall brightness and light emission unevenness.

  Accordingly, an object of the present invention is to provide a light guide sheet switch unit capable of preventing a part of a portion corresponding to the light emitting element of the light guide plate from emitting light in a spot manner and illuminating the sheet switch brightly and uniformly. Is to provide.

  In order to solve the above-described problems, a light guide sheet switch unit according to the present invention includes a substrate, a sheet switch disposed on the substrate, and a guide placed on the substrate so as to cover the sheet switch. In a light guide sheet switch unit including a light plate and a light emitting element disposed toward one end of an outer peripheral portion of the light guide plate, the light guide plate has a thick light incident on an outer peripheral portion facing the light emitting element. And a lower surface of the light incident portion is bonded onto the substrate via a light shielding member.

  The light guide sheet switch unit of the present invention absorbs strong light emitted from the front of the light emitting element because the outer periphery of the light guide plate facing the light emitting element is bonded to the substrate via a light shielding member. It is possible to suppress spot-like light emission. In addition, since the light guide plate and the substrate are in close contact with each other by the light shielding member, it is possible to prevent light emitted from the light emitting element from directly entering the sheet switch.

  Hereinafter, an embodiment of a light guide sheet switch unit according to the present invention will be described in detail with reference to the accompanying drawings. As shown in FIGS. 1 and 2, the light guide sheet switch unit 20 of the present invention includes a substrate 21, a sheet switch 22 disposed on the substrate 21, and a light guide plate placed on the sheet switch 22. 23 and a light emitting element 24 disposed at one end of the light guide plate 23.

  The substrate 21 is a rectangular epoxy resin, a BT resin, or a flexible substrate having a space in which the sheet switch 22 and the light emitting element 24 can be arranged, and an electrode for connecting the sheet switch 22 and the light emitting element 24 to the surface. And a wiring pattern is formed.

  As shown in FIG. 3, the sheet switch 22 includes a plurality of key switches 22 a including a fixed contact 26 and a movable contact 27 on a sheet-like base portion 25, and a thin sheet material 28 that covers the movable contact 27. The base portion 25 is fixed.

  For example, when the base portion 25 is formed as a seat switch of an operation panel of a mobile phone, the base portion 25 is formed in a shape and size substantially the same as that of the operation panel, and includes numeric keys, alphabet keys, and other function keys. A plurality of fixed contacts 26 are provided in accordance with the locations to be arranged. The movable contact 27 is formed in a dome shape made of a thin metal material in order to obtain an appropriate click feeling, and is disposed so as to cover the fixed contact 26 above.

  The light emitting element 24 uses a side light emitting type light emitting diode, and is disposed at one end of the substrate 21 with its light emitting surface facing one side surface of the outer peripheral portion of the light guide plate 23. The location and number of the light emitting elements 24 are appropriately set according to the shape and size of the sheet switch 22 and the number of key switches. For example, numeric keys or function keys such as a mobile phone are arranged. In the case of such a rectangular sheet switch, several switches are arranged at equal intervals on at least one side.

  The light guide plate 23 is a transparent or translucent thin plate member, and includes a light guide main body portion 23a having substantially the same shape and plane size as the sheet switch 22, and a light incident portion 23b having a thick end portion. It is integrally molded. For the light guide body 23a, for example, a material having high light guide properties such as acrylic resin, silicon resin, polycarbonate resin, or polyethylene terephthalate resin is used. Although the thickness is not particularly limited, it is desirable that the thickness is formed in the range of 0.05 mm to 0.2 mm in consideration of light guide efficiency and bending deformability.

  As shown in FIG. 2, the light incident portion 23b is formed thick so as to be gently inclined from the end portion of the light guide main body portion 23a. The light incident portion 23b includes a light receiving surface 30 facing the light emitting direction of the light emitting element 24, a placement surface 31 placed on the substrate 21, and a light guide body portion 23a from the inner end of the placement surface. And an inclined surface 32 that inclines in a tapered shape toward the rear surface side. As shown in FIGS. 1 and 4, the light receiving surface 30 is formed in an arc surface along the light emitting direction of the light emitting element 24, and has a thickness corresponding to substantially the same height as the key switch 22a. As a result, the back surface of the light guide main body 23a is held in contact with the upper portion of the movable contact 27 covered with the sheet material 28 or slightly separated. The placement surface 31 of the light incident portion 23b is a surface that is placed and fixed on the substrate 21, and is bonded and fixed on the substrate 21 with the light shielding member 33 interposed therebetween in the direction facing the light emitting element 24. Is done. In addition, the part except the front surface of the light emitting element 24 that does not sandwich the light shielding member 33 is fixed on the substrate 21 with a transparent adhesive. The inclined surface 32 is formed in a tapered shape so as to spread from the inner end portion of the mounting surface 31 toward the back surface of the light guide main body portion 23a. The inclined surface 32 is connected to the back surface of the light guide body portion 23a at an inclination angle of about 45 degrees from the inner end portion of the placement surface 31 so as to avoid the end portion of the sheet switch 22. By providing such an inclination angle, the light received by the light receiving surface 30 can be effectively and efficiently guided toward the light guide main body 23a.

  For the light shielding member 33, a black double-sided pressure-sensitive adhesive tape having adhesive surfaces on both front and back surfaces is used. This double-sided adhesive tape cut to an appropriate size is affixed to a position facing the light emitting element 24 on the substrate 21, and then the placement surface 31 of the light guide plate 23 is placed on the top surface of the double-sided adhesive tape. And adhere. Spot-like light emission can be adjusted according to the sticking range of the light shielding member 33. Usually, as shown in FIG. 2 (a), the width of the mounting surface 31 is sufficient as long as it is substantially the same width as the front surface of the opposing light emitting element 24, but as shown in FIG. 2 (b). In addition, the light shielding range can be widened by extending along the substrate 21 so as to extend from the inner end of the mounting surface 31 to the lower side of the inclined surface 32. In this way, by extending the sticking range of the light shielding member 33 to the inside of the light guide plate 23, it is possible to prevent a spot-like light emission phenomenon from occurring according to the luminance of the light emitting element 24 and the size of the light guide plate 23. Can be adjusted. Further, by forming the light shielding member 33 so as to protrude from the light receiving surface 30 toward the light emitting element 24, it is possible to adjust the amount of incident light and the spot light emission amount on the light receiving surface 30.

  Further, as shown in FIG. 1, a T-shaped upper surface light shielding member 34 is placed and covered so as to cover the light shielding member 33 and the light emitting element 24 after the light guide plate 23 is disposed. By disposing the upper surface light shielding member 34, light emitted upward from the light emitting element 24 can be suppressed, spot-like light emission can be prevented, and light guide efficiency to the light guide main body 23a can be improved.

  Next, the light guide action of the light guide sheet switch unit 20 configured as described above will be described with reference to FIG. A current is supplied to the light emitting element 24 from the outside via a connector (not shown) provided on the substrate 21. Here, the light emitted radially from the light emitting surface 24a of the light emitting element 24 enters the light incident portion 23b from the light receiving surface 30 facing the front. In the light incident portion 23b, the light received by the light receiving surface 30 can be condensed, and the light can be guided along the inclined surface 32 to the light guide main body portion 23a.

  The light receiving surface 30 located in front of the light emitting element 24 of the light incident portion 23 b receives the light emitted from the light emitting element 24 most strongly, but the mounting surface 31 is bonded onto the substrate 21 via the light shielding member 33. Therefore, it is possible to absorb a part of the received light and reduce the excess reflection, and to suppress strong spot-like light emission. Further, since the mounting surface 31 is in close contact with the substrate 21 by the light shielding member 33, light emitted from the light emitting element 24 even when the pressing operation through the light guide main body 23a is frequently performed. Can be prevented from leaking to the sheet switch 22, and spot light emission generated at the end of the sheet switch 22 can be prevented.

  As shown in FIG. 4, the present embodiment is a configuration in which two light emitting elements 24 are arranged at one end of the substrate 21. However, even if the number and arrangement positions of the light emitting elements are different, By providing the light shielding member on the mounting surface of the light incident portion in the range facing the light emitting element, the spot light emitting action can be reduced and the entire sheet switch can be illuminated with uniform brightness.

  Further, the light shielding member 33 is not limited to a double-sided tape, and light shielding by applying or printing black ink or the like directly on the placement surface 31 of the light incident portion or the substrate 21 on which the placement surface 31 is placed. It can also be formed by an adhesive coating. In addition, the black ink or the like adjusts the density according to the reflection state of light, or adjusts the area to be formed, so that a spot-like light emission action according to the intensity of light emitted from the light emitting element. Can be reduced. The light-shielding coating film is not limited to black ink, and a black powder material or the like can also be used.

It is a disassembled perspective view of the light guide sheet switch unit according to the present invention. It is sectional drawing of the said light guide sheet switch unit. It is sectional drawing which shows the structure of a sheet switch. It is a top view of the said light guide sheet switch unit. It is sectional drawing of the conventional light guide sheet switch unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light guide sheet switch unit 11 Board | substrate 12 Sheet switch 13 Light guide plate 13a Light guide main-body part 13b Outer peripheral part 14 Light emitting element 15 Base part 16 Fixed contact 17 Movable contact 20 Light guide sheet switch unit 21 Board | substrate 22 Sheet switch 22a Key switch 23 Guide Optical plate 23a Light guide body portion 23b Light incident portion 24 Light emitting element 25 Base portion 26 Fixed contact 27 Movable contact 28 Sheet material 30 Light receiving surface 31 Placement surface 32 Inclined surface 33 Light blocking member 34 Upper surface light blocking member

Claims (4)

A substrate, a sheet switch disposed on the substrate, a light guide plate placed on the substrate so as to cover the sheet switch, and light emission disposed toward one end of the outer peripheral portion of the light guide plate In a light guide sheet switch unit comprising an element,
The light guide plate has a thick light incident portion formed on an outer peripheral portion facing the light emitting element, and a lower surface of the light incident portion is bonded onto the substrate through a light shielding member. Light guide sheet switch unit. The light guide plate has an inclined surface extending incline in a direction in which the sheet switch is disposed from a lower surface of the light incident portion, and a flat light guide extending from the inclined surface so as to cover the upper side of the sheet switch. The light guide sheet switch unit according to claim 1, further comprising a main body. The light-shielding member is made of a black adhesive tape having adhesive surfaces on both front and back surfaces, the lower surface of the light incident part is adhered to the adhesive surface on the front surface side, and the adhesive surface on the rear surface side is adhered to the substrate. The light guide sheet switch unit according to 1. The light guide sheet switch unit according to claim 2, wherein the light shielding member extends along a substrate from a lower surface of a light incident portion of the light guide plate to a position below the inclined surface.

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