JP2010015794A - Light guide sheet switch unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide sheet switch unit capable of illuminating the whole light guide plate for covering over a plurality of key switches at uniform light-emitting chromaticity and uniform luminance without generating spotlike light-emitting. <P>SOLUTION: In the light guide sheet switch unit 20 having a substrate 21, light-emitting elements 25 arranged on one end of the substrate 21, a plurality of key switches 22 arranged on the substrate 21 along an advance direction of light emitted from the light-emitting elements 25, and the light guide plate 24 covering over the key switches 22 and having an incident light section 24b for taking in light of the light-emitting element 25 at the end, the light-emitting elements 25 are arranged to make its emitting surface 25a face a slanted inner side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light guide sheet switch unit mounted on an operation input unit of a small electronic device such as a mobile phone.

  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 Document 1).

  FIG. 7 shows an example of a planar configuration of the sheet switch unit 10 having the light guide function. The sheet switch unit 10 includes a key switch 12 including a plurality of fixed contacts and dome-shaped movable contacts formed on a substrate 11, a light guide plate 14 covering the key switch 12, and an outer peripheral portion of the light guide plate 14. And a light emitting element 15 mounted thereon.

The light guide plate 14 causes light emitted from a pair of light emitting elements 15 disposed at the end of the substrate 11 to enter one end of the outer peripheral portion and guide the light along the arrangement direction of the key switches 12. .
JP 2004-69751 A

  In the sheet switch unit 10 having the above configuration, the light emitting surface of the light emitting element 15 is directed so as to be substantially parallel to the direction in which the key switches 12 are arranged. A certain key switch 12 causes spot light emission. Such a spot-like strong light emission has a yellowish hue, so that there is a problem that the light emission chromaticity is not uniform and a luminance difference is caused.

  Accordingly, an object of the present invention is to provide a light guide sheet switch unit capable of illuminating the entire light guide plate covering a plurality of key switches with uniform light emission chromaticity and luminance without causing spot-like light emission. That is.

  In order to solve the above-described problems, a light guide sheet switch unit according to the present invention includes a substrate, a light emitting element disposed at one end of the substrate, and a traveling direction of light emitted from the light emitting element on the substrate. In the light guide sheet switch unit comprising a plurality of arranged key switches and a light guide plate that covers the key switches and has a light incident portion that takes in light of the light emitting elements at one end, the light emitting elements include: The emission surface is arranged obliquely inward.

  The light guide sheet switch unit of the present invention is disposed so that the light emitting element disposed at one end of the substrate is incident obliquely with respect to the light incident portion of the light guide plate. The key switch can be guided so as to cross diagonally between the key switches without being directly irradiated with strong light.

  In addition, since the light emitting element is disposed at one end of the substrate so as to face the inside of the substrate on which the plurality of key switches are arranged, the light emitted from the light emitting surface of the light emitting element is effectively guided to each key switch. It becomes possible to make it light. Accordingly, it is possible to prevent a specific key switch from emitting light in a spot manner, and it is possible to illuminate the entire plurality of key switches with uniform brightness and color development.

  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 to 3, the light guide sheet switch unit 20 of the present invention includes a substrate 21, a plurality of key switches 22 disposed on the substrate 21, and the plurality of key switches 22. The sheet material 23 is fixed on the light guide plate 24 disposed on the plurality of key switches 22, and a pair of light emitting elements 25 disposed obliquely toward one end of the light guide plate 24. .

  The substrate 21 is a rectangular epoxy resin, a BT resin, or a flexible substrate having a space in which a plurality of key switches 22 can be arranged in the vertical and horizontal directions and a planar space in which a pair of light emitting elements 25 can be arranged at the ends. An electrode pattern 21a for connecting the key switch 22 and the light emitting element 25 is formed on the surface. For example, when the substrate 21 is formed as a base of an operation panel of a mobile phone, it is formed in a shape and size substantially the same as the operation panel, and numeric keys, alphabet keys, other function keys, and the like are arranged. A plurality of fixed contacts 22a are provided according to the location.

  As shown in FIG. 2, the key switch 22 includes a fixed contact 22a formed on the substrate 21 and a movable contact 22b made of a tact spring disposed above the fixed contact 22a. The movable contact 22b is formed in a dome shape made of a thin metal material to obtain an appropriate click feeling, and is disposed so as to cover the fixed contact 22a. The plurality of arranged key switches 22 are held on the substrate 21 by a sheet material 23 that adheres along the shape of each movable contact 22b.

  The light emitting element 25 uses a side light emitting type light emitting diode, and is disposed at one end of the substrate 21 so that the emission surface 25 a faces the outer peripheral surface of the light incident portion 24 b of the light guide plate 24. Thereby, light emitted from the emission surface 25 a of the light emitting element 25 travels in a direction parallel to the surface of the substrate 21. The location and number of the light emitting elements 25 are appropriately set according to the number of the key switches 22 and the shape and size of the substrate 21 on which a plurality of the key switches 22 are arranged.

  A characteristic feature of the present invention is that, as shown in FIG. 1, the light emitting surfaces 25a of the pair of light emitting elements 25 are arranged in an inclined state so as to be directed inward. In particular, the light emitting element 25 is disposed at an angle such that light emitted in a direction orthogonal to the emission surface 25 a passes through a substantially central portion of the light guide plate 24. By arranging them obliquely in this way, the strongest light emitted from the front surface of each light emitting element 25 is guided in the light guide plate 24 toward the center of the substrate 21 in a direction that crosses the plurality of key switches 22 diagonally. Can be made. Further, as shown in FIG. 3, the light emitted from the pair of light emitting elements 25 crosses in the vicinity of the central portion of the light guide plate 24 and spreads the light to the end of the light guide plate 24 farthest from the light emitting element 25. Can be made. Further, the light emitted from the front surface of the light emitting element 25 is incident on the key switch 22 from an oblique direction, so that reflection from the key switch 22 disposed closest to the light emitting element 25 can be reduced. Therefore, spot-like light emission in this portion can be suppressed, and uniform color development and luminance can be obtained as a whole.

  In order to obtain the above effects, it is necessary to provide at least a pair of light emitting elements 25 in the direction in which the plurality of key switches 22 are arranged as shown in the present embodiment. Moreover, it is preferable that the angle at which the light emitting elements are arranged is symmetrical, and that each light emitting front face is directed to the vicinity of the central portion of the light guide plate 24. In order to further enhance the illumination effect, as shown in FIG. 4, another light emitting element 35 is additionally arranged between a pair of light emitting elements 25 arranged obliquely, or the pair of light emitting elements 25 is arranged as described above. It is also possible to adopt a configuration in which another pair is provided on the opposite side across the light guide plate 24.

  As shown in FIG. 2, the light guide plate 24 is a transparent or translucent thin plate member. The light guide plate 24 has a shape and a planar size corresponding to the arrangement space of the key switches 22, and a thick end portion. It is integrally formed with the light incident portion 24b formed in a meat shape. For the light guide body 24a, for example, a material having high light guide properties such as acrylic resin, silicon resin, polycarbonate resin, or polyethylene terephthalate resin is used. The thickness is not particularly limited, but it is preferably formed in the range of 0.05 mm to 0.2 mm in consideration of the light guide efficiency and the bending deformability.

  The light incident part 24b extends substantially parallel to one end surface of the substrate 21 having a rectangular shape, and the light emission surface 25a of the light emitting element 25 is disposed obliquely inward with respect to the light incident part 24b. Further, a substantially central longitudinal section facing the light emitting element 25 has a substantially fan shape as shown in FIG. 2, and is formed so as to surround the light emitting direction of the light emitting element 25 in a substantially semicircular shape. The light incident part 24b forms a lens surface 24c for converging light, like a convex lens, and collects light from the light emitting element 25 and makes it enter the light guide body part 24a. Further, the light guide main body 24a is provided with a hemispherical protrusion 26 on the back surface corresponding to the apex of the movable contact 22b. The protrusions 26 are formed by printing the same resin as that of the light guide main body 24a.

  In FIG. 2, reference numerals 27 and 28 denote first and second adhesive layers. The first adhesive layer 27 is provided on the surface of the substrate 21 facing the light incident portion 24 b of the light guide plate 24, and fixes the light incident portion 24 b to the substrate 21. The second adhesive layer 28 is provided on the apex portion 23 a of the sheet material 23, and fixes the protrusion 26 of the light guide plate 24 to the apex portion 23 a of the sheet material 23.

  A light shielding sheet 29 for suppressing light emission leakage is attached above the light emitting element 25 and above the light incident part 24b on the light emitting front surface of the light emitting element 25. A light shielding layer 30 for preventing reflection is formed on the upper surface of the end portion of the sheet material 23 extending near the light incident portion 24b by printing or the like.

  As shown in FIG. 5, a key top sheet 32 having a key top 31 at a position corresponding to the key switch 22 is disposed on the light guide plate 24 in the light guide sheet switch unit 20 having the above configuration. The key top 31 has translucency, and is set so that the key top 31 is illuminated by the light guide plate 24 to shine. For this reason, as shown in FIG. 6, the light diffusion part 33 which consists of several dots 33a is provided in the part which faces the keytop 31 in the surface or the back surface of the light-guide plate 24, and a light-guide plate is this dot 33a. The light in the light 24 is diffused and irradiated outward. The dots 33a in this embodiment are arranged so as to form a gradation pattern whose density increases as the distance from the light emitting element 25 increases in order to make the light emission uniform. The dots 33a are formed by any one of transparent, translucent, and white printing, or a combination thereof. When combining transparent, translucent, and white printing in this way, the number and density of the dots 33a are fixed, and the transparent, translucent, and white dots 33a are arranged in order from the side closer to the light emitting element 25. Thus, it is possible to make the light emission uniform.

  Next, based on FIG.2 and FIG.3, the light guide effect | action of the light guide sheet switch unit 20 by the said structure is demonstrated. A current is supplied to the pair of light emitting elements 25 from the outside via a connector (not shown) provided on the substrate 21. Here, the light emitted from the pair of light emitting elements 25 is incident on the light incident portion 24b at an oblique angle, and is collected in the light incident portion 24b. In this manner, by making the light incident on the light incident portion 24b obliquely, the reflected light due to the reflection at the key switch 22 located in front of the light emitting element 25 can be reduced, and at the same time from the light emitting element 25. Light can be distributed to the corner of the farthest light guide plate 24. Further, by arranging the pair of light emitting elements 25 obliquely toward the inside, it is possible to illuminate the entire light guide plate 24 in a wide range and evenly with a minimum light source.

  The light guide plate 24 has a structure in which the light guide plate 24 is supported in a flat state by the light incident portion 24 b and the apex portion 23 a of the sheet material 23. Thus, the light guide plate 24 supported in a flat state can efficiently guide the light taken inside without being diffused at the bent portion. When the light guide plate 24 is supported flat, there is no gap between the light guide plate 24 and each key top 31 as well as between the light guide plate 24 and each vertex 23a of the sheet material 23. It is possible to improve the operational feeling of the operation 31, and to prevent the generation of abnormal noise that occurs when the key top 31 is attached to or separated from the sheet material 23 during operation. Since the light guide plate 24 is flat, the key top sheet 32 disposed thereon does not generate a gap as described above even if the key top 31 is not bonded to the light guide plate 24. By avoiding the portion, the vicinity of the outer periphery of the key top sheet 32 can be adhered and fixed to the light guide plate 24, the substrate 21, and the like. If the key top 31 and the key switch 22 are brought into close contact with each other in this manner, the click feeling of the key switch 22 can be prevented from deteriorating. In the present embodiment, the protrusion 26 is provided on the portion of the light guide plate 24 that contacts the apex 23a of the sheet material 23 to improve the pressing feeling and adjust the height with the light incident portion 24b. The back surface of the light guide plate 24 may be directly fixed to the apex portion 23a without providing the protrusions 26.

  On the other hand, the light incident part 24b is formed as a lens surface 24c facing the light emitting element 25 as shown in FIG. Thereby, the light emitted from the light emitting element 25 can be received at a wide angle, and the light can be collected and incident in a direction that forms a parallel or shallow angle with respect to the front and back surfaces of the light guide plate 24. In addition, although a part of the light irradiated from the light emitting element 25 or a part of the light received by the light incident part 24b may shine in a dot shape by moving toward the front surface or the back surface of the light guide plate 24, the light is blocked. By providing the sheet 29 and the light shielding layer 30, unnecessary light can be cut.

  Further, as shown in FIG. 6, a light diffusion portion 33 composed of a plurality of dots 33a is formed in a portion corresponding to each key switch 22 of the light guide plate 24, or a filter or coloring of red, blue, green, etc. The light guide from the light emitting element 25 can be changed by applying. As a result, the design and interior can be enhanced, and key switches that are frequently used or require attention for operation can be distinguished from other key switches.

It is a top view which shows the principal part of the light guide sheet switch unit which concerns on this invention. It is sectional drawing of the said light guide sheet switch unit. It is a top view of the whole light guide sheet switch unit. It is a top view of the light guide sheet switch unit comprised by adding the light emitting element. It is sectional drawing of the light guide sheet switch unit provided with the key top sheet. It is a top view which shows the principal part of the light guide sheet switch unit provided with the light guide plate in which the light-diffusion part was formed. It is a top view of the conventional light guide sheet switch unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Sheet switch unit 11 Board | substrate 12 Key switch 14 Light guide plate 15 Light emitting element 20 Light guide sheet switch unit 21 Board | substrate 22 Key switch 22a Fixed contact 22b Movable contact 23 Sheet material 23a Vertex part 24 Light guide plate 24a Light guide main-body part 24b Light incident part 24c Lens surface 25 Light emitting element 25a Emission surface 26 Protrusion 27, 28 Adhesive layer 29 Light shielding sheet 30 Light shielding layer 31 Key top 32 Key top sheet 33 Light diffusion part 33a Dot 35 Light emitting element

Claims (6)

A substrate, a light emitting element disposed at one end of the substrate, a plurality of key switches arranged on the substrate along a traveling direction of light emitted from the light emitting element, and covering the key switch, In a light guide sheet switch unit comprising a light guide plate having a light incident portion for taking in light of the light emitting element.
The light-emitting sheet switch unit, wherein the light-emitting element is disposed with an emission surface obliquely inward. 2. The light guide according to claim 1, wherein the light incident portion of the light guide plate extends substantially parallel to one end surface of the rectangular substrate, and the light emitting element has an emission surface disposed obliquely inward with respect to the light incident portion. Light sheet switch unit. 2. The light guide sheet switch unit according to claim 1, wherein at least one pair of the light emitting elements is provided at one end corner of the substrate. 2. The light guide sheet switch unit according to claim 1, wherein the light emitting element is disposed at an angle such that light beams emitted in a direction orthogonal to an emission surface pass through a substantially central portion of the light guide plate. The light guide sheet switch unit according to claim 1, wherein the light guide plate has a light incident portion formed thick and has a convex lens surface toward the light emitting element. The light guide sheet switch unit according to claim 1, wherein a light shielding sheet is attached to a surface of the light guide plate corresponding to the light incident portion.

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