JP2005174866A - Illuminated keypad and illumination structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance an illuminative property of a translucent resin keytop in the case a base sheet of an illuminated keypad is close to an illumination light source as if the sheet almost touches the source, and the resin keytop is located at a wide angle relative to the light source in the plane direction of the base sheet. <P>SOLUTION: For the illuminated keypad 1 provided with the translucent resin keytop 4 on the surface of the base sheet 5 made of a translucent rubber-like elastic body, the keytop 4 illuminates by the light emission of the illumination light source 6 facing the rear face of the base sheet, a striped face 10 having a plurality of heaped stripes 10a is formed in a floodlight area 11 of the illumination light source on the surface of the base sheet. As a result, the light of the light source 6 transmitting through the thickness of the translucent base sheet 5 is turned back to the inside of the base sheet 5 by reflection at the heaped stripes 10a of the striped face 10, which can enhance the illuminative property of the resin keytop. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an illuminated keypad for a push button switch used for portable information terminals such as a mobile phone and a PDA, various home remote controllers, card remote controllers, and various electrical devices such as a keyboard, and an illumination structure thereof.

  As a cover member for a push button switch used in an electric device, an electronic device, or the like, an illuminated keypad made up of a translucent resin key top and a translucent base sheet is known. By pressing the resin key top, this illuminated keypad conducts a fixed contact placed on the printed circuit board on the back side of the illuminated keypad. The resin key top is illuminated obliquely from below by an illumination light source such as a chip LED.

  By the way, in an electric device such as a cellular phone, in order to meet the demand for thinning of the device, the illuminated keypad itself is also thinned, and the base sheet and the resin key top are also being thin and adopting a planar shape. Specifically, the base sheet is configured as a flat flat thin sheet that lacks a skirt-like operating part for generating a click feeling that bulges upward in the resin key top mounting area on the surface. In addition, resin key tops tend to be as thin as possible. In addition, the arrangement in the cellular phone is also being implemented in a compact manner in which the distance between the printed board and the illuminated keypad is narrow. For this reason, the illumination type keypad tends to be disposed at an approach position where the back surface of the illumination type keypad comes into contact with an illumination light source such as a chip LED. In such an illuminated keypad in which the base sheet is in an approaching position as to whether or not to contact the illumination light source and the resin key top is at a wide angle position in the surface direction of the base sheet with respect to the illumination light source, It is difficult to directly irradiate the light from the resin key top directly on the entire back surface, and there is a problem that it is difficult to obtain the bright illumination of the resin key top.

As a solution to this problem, for example, a chip LED having a large directivity angle can be adopted as an illumination light source, or a light guide plate can be installed between an illumination keypad and a printed board. Japanese Patent Laid-Open No. 2001-167655 (Patent Document 1) is an example of the latter, and discloses that a light guide plate is provided on the back surface of a keypad.
JP 2001-167655 A

  However, if the base sheet is separated from the chip LED, the projection area can be enlarged by utilizing the size of the directivity angle. However, if the base sheet is close to the chip LED, the spectral projection area is narrowed. Therefore, it is still difficult to directly irradiate the entire back surface of the resin key top. In addition, when a light guide plate is used, its storage space is required, so that it is difficult to say that the solution is suitable for the demand for thinning the equipment.

  The present invention has been made against the background of the prior art as described above. The purpose is that the base sheet of the illumination type keypad is in an approaching position as to whether or not the illumination light source is in contact with the illumination light source, and the resin key top is at a wide angle position in the surface direction of the base sheet with respect to the illumination light source. The object is to increase the illumination of the translucent resin key top.

  In order to achieve this object, the present invention includes a translucent resin key top on the surface of a base sheet made of a translucent rubber-like elastic body, and emits light from an illumination light source facing the back surface of the base sheet. The illumination type keypad that illuminates is characterized in that a streaked surface portion made up of a plurality of mountain-shaped streaks is formed in the light projection region of the illumination light source on the surface of the base sheet.

  In the illuminated keypad of the present invention, since the streak surface portion composed of a plurality of mountain streaks is formed in the projection area of the illumination light source on the surface of the base sheet, it transmits through the thickness of the translucent base sheet. The light from the illuminating light source is returned to the inside of the base sheet by the reflection action on the mountain-shaped streaks on the streaks. Therefore, the amount of light that passes through the light projection area of the base sheet as it is and leaks to the outside of the base sheet is reduced, and the amount of reflected light that passes through the translucent resin key top through the inside of the base sheet increases. As a result, even if the base sheet is in an approaching position as to whether or not it comes into contact with the illuminating light source and the resin key top is at a wide-angle position in the surface direction of the base sheet with respect to the illuminating light source, If it is an illumination type keypad, the illumination property of the resin key top can be improved.

  In consideration of the reflection effect of the streaked surface portion as described above, the formation position of the streaked surface portion in the base sheet may be formed at a position that does not overlap with the placement region of the resin key top in the base sheet, or the placement region. It may be formed at a position that partially overlaps.

  The illumination type keypad is configured such that the interval between the top portions of adjacent mountain-shaped lines is formed narrower than the width of the light emitting portion of the illumination light source.

  According to the present invention, since the distance between the tops of the mountain-shaped streaks is narrower than the width of the light-emitting portion of the illumination light source, the light is reliably returned into the base sheet by the reflecting action of the plurality of mountain-shaped streaks.

  The illuminated keypad is configured such that the plurality of mountain streaks are continuously formed in parallel without a flat surface.

  According to the present invention, there is no flat surface through which the light from the illumination light source is transmitted as it is at the boundary portion between adjacent mountain streaks. Therefore, the light is reliably returned to the base sheet by the reflection action of the mountain streaks. .

  The illuminated keypad is configured by forming the plurality of mountain streaks as triangular streaks.

  Since the mountain-shaped streaks of the present invention are triangular streaks whose tops are corners, there is no flat surface that allows the light of the illumination source to pass through the tops of the mountain-shaped streaks. The light is reliably returned into the base sheet.

  In the illuminated keypad, the light projecting area of the base sheet and the placement area of the resin key top are spaced apart in the surface direction of the base sheet, and the streak surface portion extends from the light projecting area to the placement area. It is comprised as what was formed in the separation area | region which reaches. And about this illumination type keypad, furthermore, a plurality of mountain-shaped streaks on the streaks are formed so that the longitudinal direction thereof is along a virtual line that linearly connects the light projecting area and the placement area described above. Configured.

  According to the present invention, the streak surface portion is formed in the separation region, and the light reflecting action is applied to the base sheet even in the separation region, so that the light reflected by the streak surface portion of the light projecting region is directed to the placement region of the resin key top. The amount of light transmitted from the base sheet to the outside before reaching it can be reduced. In this case, if a plurality of mountain streaks on the streaked surface portion is formed so that the longitudinal direction thereof is along a virtual line that linearly connects the light projecting area and the placement area, the base sheet further outwards. The amount of transmitted light is reduced, and the illumination of the resin key top is further enhanced.

  In order to achieve the above object, the present invention is an illumination structure that includes the illumination type keypad according to the present invention on a printed circuit board and illuminates a resin key top with an illumination light source mounted on the printed circuit board. Provided is an illumination structure in which a light reflecting film is provided between the back surface of the illuminated keypad and a printed board.

  According to the present invention, the downward light reflection action to the inside of the base sheet by the stripe surface portion and the upward light reflection action to the inside of the base sheet by the light reflection film act complementarily at the vertical position. Further, the amount of light reaching the resin key top is further increased, and the bright illumination property can be further increased. In this case, the light reflecting film may be fixed to the base sheet, or may be fixed to a printed board facing the base sheet. In short, it does not matter whether the base sheet is fixed or not, as long as it can face the streak surface portion and can complementarily exhibit the reflecting action in the vertical position.

  More specifically, the base sheet in the illuminated keypad of the present invention as described above has a skirt-like operation portion for generating a click feeling that bulges upward in the mounting region of the resin key top on the surface. It is assumed that the flat flat thin sheet lacking is configured. According to this, clear illumination of the resin key top, which is difficult because the illumination type keypad is thin, can be obtained by the reflection action of the streaked surface portion.

  According to the illuminated keypad and illumination structure of the present invention, the bright illumination of the resin key top can be obtained without depending on the illumination light source, such as selecting an illumination light source having a large directivity angle or a high emission luminance. It is done. Therefore, when applied to a portable terminal such as a mobile phone or a PDA, various problems on the device side caused by causing the illumination light source to emit light with higher brightness, for example, shortening the driving time due to increased power consumption, and increasing the battery capacity There is no inconvenience such as weight increase and size increase. Even if the base sheet of the illumination type keypad is in an approaching position as to whether or not the illumination light source is in contact with the illumination light source, and the resin key top is at a wide angle position in the surface direction of the base sheet with respect to the illumination light source, the resin key Since the bright illumination of the top can be obtained, the illuminated keypad can be thinned, and can greatly contribute to the thinning of portable terminals such as mobile phones and PDAs.

  An illuminated keypad according to an embodiment of the present invention will be described in more detail with reference to the drawings. FIG. 1 is an external front view of a mobile phone 2 including an illuminated keypad 1 according to an embodiment, and FIG. 2 is a cross-sectional view showing a positional relationship between the illuminated keypad 1 and a printed circuit board 3. The illuminated keypad 1 includes a translucent resin key top 4 that is exposed from the casing 2 a of the mobile phone 2 and receives a pressing operation, and a base sheet that is placed on the printed circuit board 3 and supports the resin key top 4. And 5. In addition, the printed circuit board 3 is electrically connected to the twelve chip LEDs 6 as an illumination light source, a metal disc spring 7 that buckles by a pressing operation to generate a click feeling, and a contact with the disc spring 7. A fixed contact 8 or the like having a function is provided.

  The base sheet 5 is formed in the shape of a flat thin sheet by a light-transmitting rubber-like elastic body such as silicone rubber. The base sheet 5 has protrusions (not shown) for supporting the base sheet 5 so as to float from the printed circuit board 3 as shown in FIG. 2, and a pusher 9 for pressing the disc spring 7 is formed downward. Has been. Such a base sheet 5 is formed to be as thin as 0.5 mm or less in average thickness including the protrusions and the pushers 9.

  On the surface of the base sheet 5 (surface on the resin key top 4 side), a streaked surface portion 10 as shown in FIG. 3 or FIG. 4 is formed. The streaked surface portion 10 is formed with a plurality of mountain-shaped streaks 10a and 10b that are respectively directed in one direction d1 and d2. The cross-sectional shape of the mountain-shaped stripes 10a and 10b is formed as a shape that tapers toward the top. Specifically, in addition to the triangular shape shown in FIG. 3, it may be a semicircular shape shown in FIG.

  The triangular streaks 10a may be an isosceles triangular shape that is subject to right and left or a triangular shape that is not subject to right and left, but the apex angle is preferably 90 ° ± 30 °. If the angle is less than 60 °, the light cannot be reflected efficiently. If the angle is greater than 120 °, the pitch of the mountain-shaped streaks 10a becomes wide. In either case, the light is sufficiently guided to the resin key top 4. Because there is no. The top angle can be determined within a range of 90 ° ± 30 ° depending on the directivity angle of the chip LED 6 and the distance between the resin key top 4 and the chip LED 6. For example, when the chip LED 6 having a directivity angle of 30 ° is used, it is preferable that the mountain-shaped streaks 10a have an isosceles triangle shape having an apex angle of 90 °.

  A pitch P (interval between tops) P between adjacent mountain-shaped lines 10a and 10b is formed to be narrower than the width of the light emitting part 6a of the chip LED 6, and is approximately 25 μm to 300 μm. If this distance is 10 μm or less, light may interfere, and if it is less than 25 μm, molding becomes difficult. On the other hand, when the thickness exceeds 300 μm, the reflecting action for improving the illumination property decreases. In addition, the light emission part 6a in chip LED6 shown by this embodiment means the window part from which light emits from chip LED6. Therefore, the length of the pitch P of the mountain-shaped stripes 10a and 10b is formed to be smaller than the length of one side of the light emitting portion 6a of the chip LED 6.

  The height of the mountain streaks 10a and 10b is 10 μm to 100 μm. Even if it is higher than 100 μm, the light guide property to the resin key top 4 due to the light reflecting action is not improved, and there arises a problem that it becomes difficult to adhere the resin key top 4 and the base sheet 5. On the other hand, when the thickness is lower than 10 μm, it is difficult to obtain the light guide property due to the reflecting action of the mountain-shaped streaks 10a and 10b.

  Each mountain-like stripe 10a, 10b is formed on the surface of the base sheet 5 continuously in parallel without a flat surface. This is because if a flat surface is interposed between the adjacent mountain streaks 10a and 10b, light leaks from the flat surface. In addition, when the light leakage from a flat surface is slight and it is accept | permitted, you may interpose a flat surface.

  The cross-sectional shape of the mountain-shaped streaks 10b is the same as in the case of the triangular shape, even in the case of other shapes including the semicircular shape as shown in FIG. is there.

  The mountain streaks 10a and 10b may be provided on the entire surface of the base sheet 5 (the surface of the base sheet 5 on the resin key top 4 side), or may be partially provided. FIG. 5 is a diagram schematically showing the positional relationship between the resin key top 4 and the chip LED 6 as the illumination light source as viewed from the direction perpendicular to the base sheet 5. In the case of providing the streaked surface portion 10 composed of the mountain-shaped streaks 10 a and 10 b, first, the streaked surface portion 10 is provided in the light projecting region 11 from the light emitting portion 6 a of the illumination light source 6 on the surface of the base sheet 5. For example, as shown in FIG. 5, when the light projection area 11 and the placement areas 12 a to 12 d of the resin key tops 4 a to 4 d are separated from each other, they are also provided in the separation area 13. As a result, in the example of FIG. 5, both the light projecting area 11 and the separated area 13 become the streaked surface portion 10.

  On the other hand, the mountain-shaped streaks 10a and 10b are not formed on the back surface (surface on the printed circuit board 3 side) of the base sheet 5, but in this case, a smooth surface or a surface that has been subjected to surface processing such as embossing may be used. Good. However, as shown in FIG. 6, a light reflecting film 5 a may be provided on the back surface of the base sheet 5. That is, since the light of the chip LED 6 can be reflected on the top and bottom of the streaked surface portion 10 and the light reflecting film 5a, the light guide property to the resin key top 4 can be improved. The bright illumination of the resin key top 4 can be obtained. Further, as shown in FIG. 7, a light reflecting film 5 b may be provided on the surface of the printed circuit board 3.

  The streak direction (longitudinal direction) of the mountain-shaped streaks 10a, 10b is not particularly limited and can be any direction. However, in FIG. 5, an imaginary line L that linearly connects the light projection area 11 from the light emitting portion 6 a of the illumination light source 6 on the surface of the base sheet 5 and the placement area 12 of the resin key top 4 on the surface of the base sheet 5. If the streak direction is provided so as to extend along the line, the brightness of the resin key top 4 becomes higher.

  The base sheet 5 having the mountain lines 10a and 10b is made of a light-transmitting rubber-like elastic body, and is made of thermoplastics such as silicone rubber, ethylene propylene rubber, polyisobutylene rubber, polystyrene, polyolefin, and polyurethane. An elastomer is used. However, silicone rubber is a preferred material from the viewpoints of cold resistance, heat resistance, weather resistance, precision moldability, and electrical insulation.

  The base sheet 5 is formed by general molding using a molding die, but the manufacturing method of the mountain streaks 10a and 10b differs depending on the material of the mountain streaks 10a and 10b. The first method is a method in which a mold groove for manufacturing the base sheet 5 is provided with a mountain-shaped groove whose concavities and convexities are opposite to those of the mountain-shaped streaks 10 a and 10 b in advance, and is molded together with the base sheet 5. The second method is a method in which the mountain-shaped streaks 10a and 10b are formed of a resin separately from the base sheet 5, and the resin-made mountain-shaped streaks 10a and 10b are bonded to a base sheet having a smooth surface. is there. The third method is a method in which a hard resin film is formed in the shape of the mountain-shaped streaks 10a and 10b and bonded to a base sheet having a smooth surface.

  For the resin key top 4 that is directly pressed with a finger or the like, a thermoplastic resin such as polycarbonate, acrylic, or ABS, a thermosetting resin such as epoxy or silicone, or a translucent resin such as an ultraviolet curable resin is used. . These resins are preferable in terms of moldability and easy decoration after molding.

  The front or back surface of the resin key top 4 can be decorated with characters, symbols, patterns and the like. In this case, the characters, symbols, etc. may be either so-called blank characters or character shapes. This decoration processing can be performed by screen printing, tampo printing, painting, transfer of a transfer foil provided with a metal thin film, or the like.

  The resin key top 4 and the base sheet 5 may be bonded together by a fitting groove formed in advance in the resin key top 4 and the base sheet 5 in addition to fixing them together with an adhesive.

  A small chip LED 6 mounted on the printed circuit board 3 can be used as an illumination light source that appropriately illuminates the illumination keypad 1. The chip LED 6 emits light in a single color such as orange, green, blue, white, or a mixed color thereof, and is packaged so that the directivity angle can be changed by attaching a lens. Light is emitted from the portion 6a. A normal chip LED 6 having a directivity angle of about 30 ° to 60 ° can be used, and it is not necessary to use a chip LED having a wide directivity angle. As the illuminating light source, in addition to the chip LED 6, an LED that is not made into a chip can be used, but it is preferable to use the chip LED 6 that emits light concentratedly from the window portion for illuminating. The light emitting source can be arranged at a distance of whether or not to contact the base sheet 5, and the light emitting part 6 a of the chip LED 6 can be used in contact with the lower surface of the base sheet 5. It is preferable to use them in contact with each other because light from the light emitting portion 6a directly enters the base sheet 5 without causing light leakage. Further, in the case of using a non-chip LED, by providing a recess in the base sheet 5 and disposing an illumination light source therein, the light from the illumination light source is guided to the base sheet 5 without leakage. It can be arranged.

  It is also preferable to improve the light guiding effect by placing a hard plastic film made of PET or PEN that diffusely reflects white light on the printed circuit board 3, or an elastic film such as a thermoplastic elastomer or silicone rubber.

  The embodiment described above is merely one embodiment of the present invention, and other modifications can be made. For example, the number and shape of the resin key tops 4 can be changed as appropriate. Also, the base sheet may have a shape having a base portion 14 in which the joint surface with the resin key top 4 bulges in a convex shape like a base sheet 15 shown in FIG. In the present embodiment, a thin base sheet having a thickness of 0.5 mm or less is used. However, a slightly thick base sheet having a thickness exceeding 0.5 mm may be used.

  An illumination test was performed using the illuminated keypad of the present invention and a chip LED. Hereinafter, the present invention will be described in more detail based on this illumination test.

  Sample 1 (FIG. 9): A base sheet (25) made of transparent silicone rubber having a thickness of 0.5 mm (thickness up to the top of the mountain-shaped streaks), and four polycarbonate resins made at the positions of the square apexes. An illuminated keypad (21) with resin key tops (24a to 24d) arranged thereon was prepared. A white translucent printing layer is provided on the back of each resin key top (24a to 24d), and the pitch is 0.1 mm on the entire surface of the base sheet (25) on the resin key top (24a to 24d) side. A mountain streak (10a) having an apex angle of 90 ° and a height of 50 μm was applied. The direction of the mountain-shaped streaks (10a) is formed so as to face a direction d4 rotated by 45 ° opposite to the rotation direction of the watch with respect to the arrangement direction d3 of the resin key top (24). This illuminated keypad (21) was designated as Sample 1. FIG. 9 shows a plan view of the illuminated keypad (21).

  Sample 2: Compared to Sample 1, the same conditions except that the direction of the streaks (10a) toward the streaks is in the same direction d3 as the resin key top (24a-24d) placement direction d3. Sample 2 as an illuminated keypad (31) was prepared.

  Sample 3: Compared with sample 1, the ridges (10a) are illuminated under the same conditions except that they are provided on the surface of the chip LED (26) instead of on the surface of the resin key top (24a-24d) Sample 3 as a keypad (41) was prepared.

  Sample 4: Compared with Sample 1, instead of forming a mountain-shaped streak (10a), a square pyramid-shaped projection (50) having a shape that is no longer a streak as shown in FIG. 10 was applied. Prepared a sample 4 as an illuminated keypad (51) under the same conditions as in sample 1. The quadrangular pyramidal protrusions (50) have a pitch of 0.1 mm and a height of 50 μm.

  Sample 5: Compared with Sample 1, Sample 5 which is an illuminated keypad (61) was prepared under the same conditions as Sample 1 except that the mountain streaks (10a) were not provided.

  In the illumination experiment, an illumination type keypad (21) as shown in FIG. 9 and FIG. 11 was used, and the light emitting portion (4) was placed at the center of the four resin key tops (24a to 24d) below the base sheet (25). The window as 26a) was performed by placing a 0.3 mm square LED chip (26) (luminance: 10 mcd) in contact. The chip LED (26) was turned on at 3 V and 20 mA in a dark room, and the luminance of the surface of the center of each resin key top (24a to 24d) was measured using a luminance meter (LS-100 manufactured by Minolta Co., Ltd.). The luminance measurement results are shown in Table 1 below.

  As is clear from Table 1, Sample 5 without the mountain-shaped streaks (10a), Sample 4 with the simple protrusion (50) that can no longer be a streak, and peaks on the chip LED (6) side. Sample 3 with a streak has low brightness, whereas Sample 1 and Sample 2 with a chevron streak (10a) on the resin key top (4) side have high brightness and good illumination function It can be seen that Further, when comparing the sample 1 and the sample 2, the longitudinal direction of the plurality of mountain streaks (10a) is along the imaginary line that linearly connects the light projecting area and the mounting area of the base sheet (5). It can be seen that the resin key tops (24a, 24d) of the provided sample 1 have higher brightness than the resin key tops (24a to 24d) of the sample 2.

1 is an external plan view of a mobile phone including an illuminated keypad according to one embodiment. FIG. 3 is a sectional view taken along line SA-SA in FIG. 1. The expansion perspective view of the base sheet in the area | region A of FIG. The expansion perspective view equivalent to FIG. 3 of another base sheet used for this invention. The projection figure to the base sheet surface of resin key top and chip | tip LED. Sectional drawing of the illumination type keypad and printed circuit board by other embodiment. Sectional drawing of the illumination type keypad and printed circuit board by other embodiment. Sectional drawing of the illumination type keypad and printed circuit board by other embodiment. The top view of the illumination type keypad by other embodiment. The expansion perspective view equivalent to FIG. 3 of the base sheet used as a comparative example. SB-SB sectional view taken on the line of FIG.

Explanation of symbols

1, 21, 31, 41, 51, 61 Illuminated keypad 2 Mobile phone 2a Case 3 Printed circuit board 4, 24a, 24b, 24c, 24d, 102 Resin key top
102a Resin key top back surface 5, 15, 25 Base sheet 5a, 5b Light reflecting film 6, 26, 101 Chip LED (illuminating light source)
6a, 26a Light emitting part 7 Belleville spring 8 Fixed contact 9 Pusher
10 Streaks
10a, 10b Yamagata
11 Translucent area
12 Mounting area
13 Spacing area
14 Base

Claims (7)

In an illuminated keypad that has a translucent resin key top on the surface of a base sheet made of a translucent rubber-like elastic body, and the key top illuminates by light emitted from an illumination light source facing the back surface of the base sheet.
An illumination type keypad, wherein a streak surface portion made up of a plurality of mountain streaks is formed in a light projection region of an illumination light source on a surface of a base sheet.   The illuminated keypad according to claim 1, wherein the interval between the tops of adjacent mountain-shaped lines is narrower than the width of the light emitting part of the illumination light source.   The illuminated keypad according to claim 1 or 2, wherein the plurality of mountain-shaped streaks are continuously formed in parallel without a flat surface.   The illuminated keypad according to any one of claims 1 to 3, wherein each of the plurality of mountain-shaped lines is formed as a triangular line.   The light projecting area of the base sheet and the placement area of the resin key top are separated from each other in the surface direction of the base sheet, and the streaked surface portion is formed in a separated area extending from the light projecting area to the placement area. The illuminated keypad according to any one of claims 1 to 4.   6. The illuminated keypad according to claim 5, wherein a plurality of mountain-shaped streaks in the streaked surface portion are formed such that the longitudinal direction thereof follows a virtual line that linearly connects the light projecting area and the placement area. An illuminated keypad according to any one of claims 1 to 6 on a printed circuit board, and an illumination structure for illuminating a resin key top with an illuminated light source mounted on the printed circuit board, wherein the illuminated keypad Illumination structure in which a light reflection film is provided between the back surface of the substrate and the printed board.

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