Illuminated keypad

Many illuminated keyboards have different zones or portions that may illuminate independent from one another. Light guides are typically used to illuminate the different zones. If light from one active or illuminated light guide enters an inactive or non-illuminated light guide, the zone of the inactive light guide may illuminate when it should not. The user of the illuminated keypad may then be confused by the improper illumination.

FIG. 1 is a plan view of an embodiment of an illuminated keypad.

FIG. 2 is a side cutaway view of the keypad of FIG. 1 .

FIG. 3 is a view of an embodiment of the masking layer of FIG. 2 .

FIG. 4 is a side cutaway view of another embodiment of the keypad of FIG. 1 .

A top plan view of an embodiment of a keypad 100 is shown in FIG. 1 . The keypad 100 has a plurality of portions of zones 104 that may be individually illuminated or activated. When a zone is not illuminated, it is referred to herein as being inactive. Reference is made to a first zone 108 , a second zone 110 , and a third zone 112 as shown in FIG. 2 . It is noted that all the zones 104 may be substantially similar to the first zone 108 , the second zone 110 , and the third zone 112 . In conventional keypads, the light from an active zone may illuminate an otherwise inactive zone. This causes the inactive zone to illuminate when it should not. The keypad 100 described herein overcomes this problem.

A side cutaway view of the keypad 100 is shown in FIG. 2 . The keypad 100 has several layers as described below. One layer is a substrate 114 that has circuits and other devices commonly used on keypads. The substrate 114 has a surface 116 which holds some devices as described below. A first switch 120 is located on the surface 116 in the first zone 108 . A second switch 122 is located on the surface 116 in the second zone 110 .

A first plunger 126 is located in the first zone 108 adjacent the first switch 120 . The first plunger 126 serves to activate or toggle the first switch 120 upon a force applied to the first plunger 126 via the first zone 108 . Likewise, the second plunger 128 serves to activate or toggle the second switch 122 upon a force applied to the second plunger 128 via the second zone 110 .

A first light guide 130 is located in the first zone 108 proximate the first plunger 126 and the first switch 120 . The first light guide 130 has a first side 132 and an opposite second side 134 , wherein light may be emitted from the second side 134 to illuminate the first zone 108 . The first side 132 faces the first switch 120 . The first light guide 130 also has a first end 135 and an opposite second end 136 . A second light guide 138 is located in the second zone 110 proximate the second plunger 128 and the second switch 122 . The second light guide 138 has a first side 140 and an opposite second side 142 , wherein light may be emitted from the second side 142 to illuminate the second zone 110 . The first side 140 faces the second switch 122 . The second light guide 138 also has a first end 144 and an opposite second end 146 . A third light guide 139 is located in the third zone 112 and is similar to the first light guide 130 . The third light guide 139 illuminates the third zone 112 . Devices are described herein that serve to optically isolate the first light guides from each other.

A masking layer 160 is located above the light guides 130 , 138 , 139 . Holes may be cut or formed in the masking layer so as to allow light emitted by the light guides 130 , 138 , 139 to illuminate their corresponding zones. An embodiment of the masking layer 160 is shown in FIG. 3 . The masking layer 160 has a first side 162 and an opposite second side 164 , wherein the first side 162 faces toward the substrate surface 116 . In some embodiments, the first side 162 has an adhesive applied thereto or is adhesive. In some embodiments, the masking layer 160 is an adhesive tape. The masking layer 160 is flexible so as not to permanently deform when pressure is applied to a zone.

The masking layer 160 has cuts located therein that separate portions of the masking layer 160 from each other. In the embodiments described herein, the masking layer 160 has a first cut 168 and a second cut 170 . The first cut 168 separates the first zone 108 from the second zone 110 . The second cut 170 separates the second zone 110 from the third zone 112 . The masking layer 160 has a first portion 174 that is located proximate the first zone 108 , a second portion 176 that is located proximate the second zone 110 , and a third portion 177 that is located proximate the third zone 112 . The portions of the masking layer 160 are defined by the cuts 168 , 170 . The first portion 174 has a first end 178 that is defined by the first cut 168 . The third portion 177 has an end 180 that is defined by the second cut 170 .

The masking layer 160 serves to optically isolate the individual zones 104 from each other. Therefore, light emitted from one zone will not cause another zone to illuminate. With reference to the embodiments described above, the masking layer 160 optically isolates the first zone 108 and the second zone 110 from each other. Likewise, the second zone 110 and the third zone 112 are optically isolated from each other. As shown in FIG. 2 , the first portion 174 is bent or formed so that the end 178 is adjacent the surface 116 . In a similar manner, the end 180 of the third portion 177 is bent or formed so as to be adjacent the surface 116 of the substrate 114 . In some embodiments, the ends of the portions are adhered or affixed to the surface 116 .

By cutting and forming or bending the masking layer 160 , light paths between the light guides are blocked. For example, the light path between the second end 136 of the first light guide 130 and the first end 144 of the second light guide 138 is blocked by the first portion 174 of the masking layer 160 . Likewise, the light path between the second light guide and the third light guide 139 is blocked by the third portion 177 of the masking layer 160 . Therefore, light leaking from one active light guide will not cause another inactive light guide or zone to illuminate when it should not illuminate.

In some embodiments, the first side 162 of the masking layer 160 is adhesive. Thus, the masking layer 160 is able to be adhered to the surface 116 of the substrate. This adhesion assures that the masking layer 160 remains in the light paths to prevent light transfer between the light guides. It is noted that other mechanisms may be applied to adhere or affix the masking layer 160 to the surface 116 .

Another embodiment of the keypad 100 is shown in FIG. 4 . FIG. 4 is a side cutaway view of the keypad 100 . In summary, the masking layer 160 is folded between the light guides so as to block light paths that would otherwise extend between the light guides. As shown in FIG. 4 , the masking layer 160 has a first fold 200 and a second fold 204 . The folds 200 , 204 block the light paths between the light guides 130 , 138 , 139 . In some embodiments, the folds are attached to the surface 116 of the substrate 114 at locations 206 and 208 .

It is noted that the light guides described above are located proximate switches. However, the light guides may illuminate zones of the keypad that are not associated with switches.