Abstract:
In conventional self-lighting type push-button input devices there is adopted a construction wherein push-button portions and a base plate are formed using the same material. Since a light conducting function cannot be expected of the base plate, it is necessary to provide the same number of lamps as the number of push-button portions, with consequent increase of size and cost. In a self-lighting type push-button input device according to the present invention, a button base portion can be formed of a transparent material, holes can be formed in predetermined positions of the button base portion, and spring portions can be formed integrally with the holes by molding with use of transparent silicone rubber with a light diffusing agent incorporated therein. With this construction, the button base portion  2  serves as a light conducting portion able to effect the propagation of light without causing any loss, and the spring portions can uniformly diffuse the light distributed thereto by the light conducting portion, whereby lighting can be effected by a reduced number of light sources, that is, the reduction of size and cost can be attained to solve conventional problems.

Description:
[0001]     This application claims the priority benefit under 35 U.S.C. §119 of Japanese Patent Application No. 2003-351715, filed on Oct. 10, 2003, which is hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a self-lighting type push-button input device such as an operating panel of a portable telephone wherein plural push buttons are provided for input and are illuminated for convenience in using the input device in a dark place at night for example.  
         [0004]     2. Description of the Related Art  
         [0005]      FIG. 11  shows a constructional example of a conventional self-lighting type push-button input device  90 . In the input device  90 , a part of a push-button  91  and a spring portion  92  are formed using silicone rubber with a light diffusing agent incorporated therein for example, the spring portion  92  are formed using silicone rubber with a light diffusing agent incorporated therein for example, the spring portion  92  being adapted to deflect upon depression of the push-button portion  91  and give a stroke to the push-button portion  91 , and a key top portion  93  formed of a transparent or milk-white resin is mounted so as to cover the push-button portion  91 .  
         [0006]     Further, a light conducting portion  94  formed of a transparent and rigid resin is embedded in the silicone rubber by integral molding at a position in under the push-button  91  and inside the spring portion  92 . It is the construction of one push-button  95  that has been described above. In this conventional example, plural push-button units  95  are connected side by side through a base portion  96  formed of the silicone rubber referred to above. A light source  97 , e.g., LED lamp, is disposed face to face with the light conducting portion  94  in each in each of the push-button units  95  to effect illumination.  
         [heading-0007]     [Patent Literature 1] 
         [0008]     Japanese Unexamined Utility Model Publication No. Hei 7 (1995)-10701  
         [0009]     In the above conventional push-button input device  90 , since the push-button portion  91  is formed using silicone rubber with a light diffusing agent incorporated therein, light is diffused uniformly in the push-button portion  91  and there is obtained a key top surface of uniform brightness, thus affording a product superior in quality impression.  
         [0010]     In the conventional push-button input device  90 , however, the base portion  96 , as a portion other than the push-button  91  for which the diffusion of light is required, is also formed using silicone rubber with a light diffusing agent incorporated therein, so that when light is to be propagated by utilizing the base portion  96 , a great propagation loss occurs due to the diffusion. As a result, as noted above, it is required that one light source be provided for each of the push-button units  95 , thus giving rise to the problem of an increase of cost.  
       SUMMARY OF THE INVENTION  
       [0011]     According to one aspect of the invention there is provided a self-lighting type push-button input device comprising a button base portion formed of resin in a generally plate shape, a plurality of spring portions formed of a rubbery resin so as to permit a stroke motion thereof relative to button base portion, a plurality of push-button portions provided on the top of the spring portions respectively, and a light source, wherein a portion of the button base portion which permits distribution of light at least from an outer edge portion thereof to all of the spring portions and the push-button portions is formed as a light conducting portion thereof using a transparent resin, the light source is disposed face to face with the outer edge portion in the light conducting portion, and the spring portions are formed integrally with the light conducting portion by integral molding with use of a light diffuse-transmittable rubbery resin. With this self-lighting type push-button input device, it is made possible to reduce the number of light-sources, simplify the construction, and thereby solve the foregoing problem.  
         [0012]     In another aspect of the invention there is provided a self-lighting type push-button input device comprising a button base portion including a plurality of push-button portions and an LED light source disposed sideways (on the plate thickness side) of the button base portion, wherein the button base portion is provided so as to surround the plural push-button portions, a light conducting portion is formed of a light transmitting resin on the button base portion, the light source is disposed sideways (on the plate thickness side) of the light conducting portion in such a manner that an optical axis thereof is substantially aligned with an intra-surface (plate thickness) direction or a light transmitting resin on the button base portion, and an optical barrier or a light diffusing portion ( 32   e ) is provided at a position including a straight line jointing at least the light source and the push-button portion positioned closest to the light source.  
         [0013]     According to an aspect of the invention, since the whole or a part of the button base portion is preferably formed as a light conducting portion using a transparent resin, all the push-button portions can be illuminated brightly with a smaller number of light sources than the number of the plural push-button portions provided on the button base portion. Consequently, there can be attained such excellent effects as a decrease in the number of parts, simplification of the construction, and the resulting reduction of cost. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a plan view of a self-lighting type push-button portion input device according to an embodiment of the invention;  
         [0015]      FIG. 2  is a sectional view taken on line A-A in  FIG. 1 ;  
         [0016]      FIG. 3  is a plan view showing a modification of the embodiment of  FIG. 1 ;  
         [0017]      FIG. 4  is a sectional view taken on line B-B in  FIG. 3 ;  
         [0018]      FIG. 5  is a plan view of a self-lighting type push-button portion input device according to another embodiment of the invention;  
         [0019]      FIG. 6  is a sectional view taken on line C-C in  FIG. 5 ;  
         [0020]      FIG. 7  is a plan view of a self-lighting type push-button portion input device according to another embodiment of the invention;  
         [0021]      FIG. 8  is a plan view of a self-lighting type push-button portion input device according to another embodiment of the invention;  
         [0022]      FIG. 9  is a plan view showing a portion of a self-lighting type push-button portion input device according to another embodiment of the invention;  
         [0023]      FIG. 10  is a sectional view showing a portion of a self-lighting type push-button portion input device according to another embodiment of the invention; and  
         [0024]      FIG. 11  is a schematic sectional view showing a portion of a conventional self-lighting type push-button input device. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0025]     The present invention will be described in detail hereunder by way of embodiments thereof.  FIGS. 1 and 2  show a self-lighting type push-button input device  1  according to an embodiment of the invention. Although the following description is based on the assumption that the self-lighting push-button input device  1  is an operating panel of a portable telephone, the present invention is not limited thereto.  
         [0026]     According to a basic construction of the self-lighting type push-button input device  1 , a generally plate-like button base portion  2  can be formed of a rigid resin. For example, three columns by five rows of push-button units  5  can be provided on the button base portion  2 . The push-button units  5  each can include a spring portion  3  formed of resin having a suitable elasticity such as silicone rubber and a push-button  4  formed of a rigid resin on top of the spring portion  3  to indicate a character or a symbol.  
         [0027]     As the material of the button base portion  2  there is adopted a preferably rigid and transparent resin such as, for example, acrylic resin or polycarbonate resin. An appropriate number of light sources  6 , e.g., LED lamps, can be disposed at appropriate positions along an outer periphery portion of the button base portion  2  so as to confront the outer periphery portion. The positions and number of the light sources  6  can be determined so that all of the push-button units  5  are illuminated as uniformly as possible in the actual self-lighting type push-button input device  1 .  
         [0028]     A predetermined number of holes  2   a  can be formed in the button base portion  2  at positions where the push-button units  5  are to be provided, and the spring portions  3  can be formed on inner surfaces of the holes  2   a  respectively by integral molding. The silicone rubber that preferably forms the spring portions  3  can be selected as a transparent one, in which a light diffusing agent is incorporated to diffuse light incident on the interiors of the spring portion  3 .  
         [0029]     The push-button portions  4  are for indication of characters, numerals, symbols, etc. and are operated by being touched by a user. Therefore, as the material of the push-button portions  4  there is selected a material such that the characters, numerals, or symbols formed by printing or stamping can be read clearly with light diffused in the spring portions  3  and are not easily worn or extinguished by contact therewith of the user&#39;s hand or fingers.  
         [0030]     Next, the operation and effect of the self-lighting type push-button input device  1  constructed as above will be described. Light which is emitted from the light sources  6  into the button base portion  2  prevails substantially the whole surface of the button base portion  2 , including upper and lower surfaces, while preferably making total reflection on boundary surface between the button and the atmosphere. For example, when the light sources  6  into the button base portion  2  so as to sandwich of the substantially the whole surface of the button base portion  2 , substantially the whole of an inner surface of the button base portion can be illuminated with uniform brightness.  
         [0031]     Light which has reached each hole  2   a  enters the spring portions  3  which are preferably in contact with the hole  2   a . Then, the light can be diffused with the light diffusing agent incorporated in silicone rubber which forms the spring portion  3  and can be released as diffused light to the exterior. The diffused light passes through the push-button portion  4  which covers the spring portion  3  from the operating side, whereby for example a character or figure formed in the push-button portion  4  can be seen in an illuminated state.  
         [0032]     In the self-lighting type push-button input device  1  of this type, a cover  10  may be attached to the device so that only the push-button portions  4  can be seen from the user side, as shown in  FIGS. 3 and 4 . Thus, a design-oriented modification may be made to improve the beauty of the device. For example, a portion to be kept invisible from the user side, such as the surface of the button base portion  2 , may be covered.  
         [0033]     Thus, since the button base portion  2  can be formed of a transparent resin, in the inner surface of the button base portion  2 , as noted above, the light from the light sources  6  once enters the interior through two opposed plate side faces repeats internal reflection within the button base portion  2  which has a higher refractive index than the atmosphere, thereby providing a nearly uniform brightness. Since the above internal reflection is performed at a high reflectance within the transparent material, a light quantity loss caused by reflection is very small.  
         [0034]     Thus, a nearly uniform and sufficient quantity of light can be fed to the holes  2   a , i.e., the spring portions  3 , no matter at which positions in the button base portion  2  the holes or the spring portions may be located. Therefore, the number of the push-button units  5  provided within the button base portion  2  and that of the light sources need not be made 1:1 corresponding to each other. In this embodiment, with four light sources  6  relative to fifteen push-button units  5 , illumination can be done at a uniform and sufficient quantity of light, thus permitting the reduction in the number of parts and simplification of construction.  
         [0035]      FIGS. 5 and 6  illustrate a self-lighting type push-button input device  1  according to another embodiment of the invention. The embodiment of  FIGS. 5 and 6  can simplify the construction and reduce the size. In this embodiment, the thickness t of a button base portion  12  can be made larger gradually from one end side toward an opposite end side and light sources  6  can be disposed on only the thicker end side.  
         [0036]     In the construction of the embodiment of  FIG. 1 , the brightness becomes lower with separation from the light sources, and for compensating this inconvenience, the light sources  6  can be mounted on two confronting sides for example. According to the construction of the embodiment of  FIGS. 5 and 6 , by making the thickness t smaller with separation from the light sources  6 , a luminous flux density is enhanced, and even with light sources  6  mounted on only one side (see  FIG. 5 ), a uniform light quantity can be fed to all of the push-button units  5 . Thus, it suffices to provide the light sources  6  and their mounting mechanism on only one side, whereby not only the simplification of construction but also the reduction of size can be attained.  
         [0037]      FIG. 7  illustrates a self-lighting type push-button input device according to another embodiment of the invention. In both the embodiments of  FIG. 1  and  FIG. 5 , the whole of the button base portions  2  and  12  is preferably formed of a rigid and transparent resin, and holes  2   a  and  12   a  for mounting the push-button units  5  are formed at predetermined positions.  
         [0038]     In the embodiment of  FIG. 7 , a button base portion  22  can be formed by a combination of a rigid and transparent resin such as an acrylic resin or a polycarbonate resin and a relatively soft, elastic and light diffuse-transmittable resin such as silicone rubber with a light diffusing agent incorporated therein. In the portion formed by the silicone rubber, spring portions  3  can be formed of the same material by integral molding (see  FIGS. 4 and 6 ). According to this construction, the portion through which the light from a light source  6  is conducted can be the only portion formed of the transparent resin. In the embodiment of  FIG. 7 , this portion formed of the transparent resin is designated a light conducting portion  22   b , and the light source  6  is attached to the light conducting portion  22   b.    
         [0039]     A description will now be given of the other portion, indicated at  22   c , than the light conducting portion  22   b . Since the other portion  22   c  can be formed of silicone rubber with a light diffusing agent incorporated therein, the light passing through the interior thereof is not diffused, but is radiated to the exterior. Consequently, the light transfer distance is short and thus the other portion  22   c  may not be suitable as a light conducting portion. It is preferable not to introduce light into this portion because the amount of light capable of being distributed to the spring portions  3  can be increased.  
         [0040]     In the embodiment of  FIG. 7 , on the basis of the results obtained above, at the time of integrally molding the light conducting portion  22   b  and the other portion  22   c  of silicone rubber to constitute the button base portion  22 , slits  22   d  can be formed in the other portion  22   c  at positions other than the vicinity of the spring portions  3  to prevent the light transmitted through the interior of the light conducting portion  22   b  from leaking out directly to the other portion  22   c.    
         [0041]     The width w of the light conducting portion  22   b  becomes narrower as the distance from the mounted position of the light source  6  becomes longer, whereby a uniform illuminance can be obtained in the longitudinal direction. By so doing, light can be radiated to only the required portion, and even in the case where a part of the button base portion  22  is formed using a light diff-using material with a light diffusing agent incorporated therein, it is possible to apply light to only the required portion and the deficiency in light quantity does not occur even without increasing the number of light source  6 .  
         [0042]      FIG. 8  illustrates a self-lighting type push-button input device  1  according to another embodiment of the invention. This embodiment comprises adding the method/apparatus adopted in the embodiment of  FIG. 7  to the embodiment of  FIG. 1  (or to the embodiment of  FIG. 5 ), thereby making illumination still more uniform and improvingly the quality without any substantial increase of cost.  
         [0043]     A study will now be made about the problem in quality of for example the self-lighting type push-button input device  1  of the embodiment of  FIG. 1 . The brightness at each of various positions in the button base portion  2  (12) can be determined by the total of the quantity of light propagated by repetition of internal reflection on the surface of contact total of the button base portion  2  with the atmosphere and the quantity of light emitted directly from the light sources  6 .  
         [0044]     The quantity of propagated by repetition of internal reflection has a strong tendency to making the brightness of the interior of the button base portion  2  uniform, while the quantity of direct light from the light sources  6  is in inverse proportion to the square of distance and hence the shorter the distance, the stronger the brightness. Therefore, if the direct light portion is excluded from the light emitted from the light sources  6  and reaching the spring portion  3 , the push button portions  4  can be illuminated with a more uniform brightness.  
         [0045]     In the embodiment of  FIG. 8 , on the basis of the conclusion obtained above, slits  32   d  are preferably formed as optical barriers through a button base portion  32  in the thickness direction of the button base portion and at positions substantially confronting the positions where light sources  6  are installed. Preferably, the angle of each slit  32   d  is set at an angle shallower than about 45° relative to the traveling direction of the light emitted from the associated light source  6  so as to induce an internal reflection and lest the slit  32   d  should release light into the atmosphere which would cause a loss in light quantity. In the embodiment of  FIG. 8 , the slits  32   d  can be formed in the four corners of the button base position  32  which positions are easy to satisfy the above condition.  
         [0046]     Each slit  32   d  is preferably formed in such a range as to prevent the direct light from the associated light source  6  from reaching the spring portion  3 . According to the results of studies made by the present inventors, it has been confirmed that if the slit  32   d  is formed so that the direct light from the light source  6  and the light emitted from the light source  6  and after a single internal reflection do not reach the spring portion  3 , there is obtained a substantially uniform illumination effect.  
         [0047]      FIG. 9  illustrates a self-lighting type push-button input device according to another embodiment of the invention. In view of a conclusion mentioned in the discussion of the embodiment of  FIG. 8 , if the direct light from each light source  6  is prevented from reaching the spring portion  3 , the uniformity of illumination between adjacent push-button units  5  can be improved to a considerable extent.  
         [0048]     In the embodiment of  FIG. 9 , therefore, the formation of the slit  32   d  in the incident portion of the direct light from each light source  6  on the spring portion  3  can be the same as in the embodiment of  FIG. 8 , but the same material as the material of the spring portion  3  is preferably incorporated into the slit  32   d  in the spring portion forming step to afford a light diffusion portion  32   e.    
         [0049]     With the light diffusion portion  32   e , the light passing through the light diffusing portion  32   e  is diffused and can reach the spring portion  3  in the diffused state. That is, diffusion of light is conducted again in each spring portion  3 , so that such an extreme increase of brightness as in the arrival of the direct light at the spring portion is not felt and it becomes possible to make the illumination uniform between adjacent push-button units  5 .  
         [0050]     In the case of each slit  32   d  formed in the embodiment of  FIG. 9 , it suffices to transmit the diffuse light by a light diffusing agent—added silicone rubber or the like injected into the slit, and such an internal reflecting function for the light emitted from each light source as in the embodiment of  FIG. 8  is not required. Therefore, the degree of morphological freedom at the time of forming the slits  32   d  is high and there accrues an advantage that the formation of the slits  32   d  is easy.  
         [0051]      FIG. 10  illustrates a portion of a self-lighting type push-button input device according to another embodiment of the invention. According to the recent tendency, even in the case where light emitted from each light source  6  such as an LED lamp is used for illumination, it sometimes is required that the illumination be made using light of a color different from the color of the light emitted from the LED lamp.  
         [0052]     To meet such a requirement, the present invention provides the construction shown in  FIG. 8 . Spring portions  3  can be integrally formed using silicone rubber with a light diff-using agent incorporated therein at predetermined positions on the button base portion  2  (˜32) which is formed in the same way as in any of the above-described embodiments. Thereafter, a color transformation layer  7  can be formed for example by the same integral molding means as above using silicone rubber with a fluorescent material incorporated therein, the fluorescent material being for example blue photo-excited and emitting yellow color, or using a suitable resin. Alternatively, spring portions  3  are formed beforehand in a disc shape and are then attached to the button base portion by sticking or fusion. In addition, push-button portions  4  can be attached to the spring portion  3 . As light sources  6  there can be adopted LED lamps which emit blue color.  
         [0053]     According to this construction, light radiated to the exterior from the push-button portions  4  becomes a mixed light of blue light emitted from the LED lamps as the light sources  6  and yellow light photo-excited by the fluorescent material. That is, white light is obtained. This white light may be obtained by the combination of LED lamps which emits a near-ultraviolet light and a fluorescent material which emits the three primary colors of R (red), G (green), and B (blue). Also in this case, the same construction as above is applicable.  
         [0054]     Having described preferred embodiments consistent with the invention, other embodiments and variations consistent with the invention will be apparent to those skilled in the art. Therefore, the invention should not be viewed as limited to the disclosed embodiments but rather should be viewed as limited only by the spirit and scope of the appended claims.