Patent Publication Number: US-9852853-B2

Title: Thermally fused spacers

Description:
BACKGROUND 
     Keyboards are utilized in a variety of applications. For example, keyboards may be utilized as an input device to provide letters, numbers and/or characters to a computer, among other possibilities. Ensuring that a keyboard operates as intended may be desirable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a profile view of an example of a keyboard membrane including a thermally fused spacer according to the disclosure. 
         FIG. 2  illustrates an exploded view of an example of a keyboard membrane including a thermally fused spacer according to the disclosure. 
         FIG. 3  illustrates a top view of an example of a keyboard membrane including a thermally fused spacer according to the disclosure. 
         FIG. 4  illustrates a flow diagram of an example of a method of manufacture of keyboard membranes including a thermally fused spacer according to the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     During an operational lifetime a keyboard may be subjected to environmental conditions such as humidity and/or liquid (e.g., liquids spilled on a surface of the keyboard), among other environmental conditions, that may cause the keyboard to experience temporary and/or permanent damage. As a result, the keyboard may not function as intended. For example, a particular key (e.g., a spacebar) on the keyboard may not produce a desired output (e.g., a space). As such, ensuring that a keyboard operates as intended may be desirable. 
     Examples of the disclosure include keyboard membranes including thermally fused spacers and methods of manufacturing the same. Keyboard membranes as used herein refer to those suitable in a keyboard. As used herein, sealed conductive traces refer a conductive trace (e.g., a silver conductive trace) coupled to contact (e.g., a key contact) included in a circuit such as a circuit included in a keyboard membrane where the conductive trace is at least partially sealed from environmental conditions such as humidity and/or liquids, among other environmental conditions by a layer of thermoplastic material. That is, while described herein with respect to keyboard membranes, thermally fused spacers can be utilized a variety of other applications and/or devices that employ a conductive trace or similar electrical component. 
     A keyboard membrane including a thermally fused spacer can, for example, include a first circuit including a first conductive trace and a first key contact of the keyboard membrane, where the first conductive trace is coupled to the key contact, a second circuit including a second conductive trace and a second key contact of the keyboard membrane, where the second conductive trace is coupled to the second key contact, and where the second key contact is to couple to the first key contact, and a spacer formed of a layer of thermoplastic material, a first thermoplastic film, and a second thermoplastic film, where the spacer is fused via the first thermoplastic film and the second thermoplastic film to the first circuit and the second circuit. 
     Desirably, keyboard membranes including thermally fused spacers, as described herein, provide protection from environmental conditions such as humidity and/or liquids while retaining desired functionality of the keyboard membrane (e.g., having a desired force to fire, etc.), in contrast to other keyboard membranes such as those that do not include thermally fused spacers and/or employ printed adhesives and/or solvent based adhesives within a keyboard membrane and therefore may not function as intended during and/or following being exposed to various environmental conditions such as exposure of the keyboard membrane to humidity and/or liquids. That is, the disclosure eliminates use of adhesives such as printed adhesive and/or solvent based adhesives, etc., within a keyboard membrane and instead circuits off a keyboard membrane are separated by a spacer formed of a layer of thermoplastic material, a first thermoplastic film, and a second thermoplastic film, where the spacer is fused via the first thermoplastic film and the second thermoplastic film to the first circuit and the second circuit (i.e., fused without intervening elements such as printed adhesives, solvent based adhesives, or mechanical fasteners) to the circuits to non-removably couple the first circuit and the second circuit to the spacer and thereby create a seal from an environment external to the keyboard membrane. 
       FIG. 1  illustrates a profile view of an example of a keyboard membrane including a thermally fused spacer according to the disclosure. The keyboard membrane  100  includes a first circuit  104  having a first face  108 , a second circuit  106  having a second face  100 , and a spacer  111  formed of thermoplastic material  116 , a first thermoplastic film  113 , and a second thermoplastic film  115 . However, while  FIG. 1  illustrates the keyboard membrane as including a particular number of elements, the present disclosure is not so limited. Rather, elements shown in the various figures herein can be added, exchanged, and/or eliminated so as to promote various aspects of thermally fused spacers according to the disclosure. For example, while not illustrated as such in  FIG. 1 , the keyboard membrane  100  can include a vent, as described herein. As mentioned, keyboard membranes herein such as keyboard membrane  100  employ thermally fused spacers and are free of adhesives such as printed adhesives and/or solvent based adhesives in contrast to other approaches that may employ printed and/or solvent based adhesives, among other types of adhesives, in an effort to couple a material (e.g., polyethylene terephthalate) to an internal of a circuit. That is, keyboard membranes herein are free of printed adhesive and solvent adhesive at least between the first circuit  104  and the second circuit  106 . 
     The first circuit  104  can include a first conductive trace (not shown for ease of illustration in  FIG. 1 ) and a first key contact  105 . The first conductive trace is coupled to the key contact  105 . The second circuit  106  can include a second conductive trace (not shown for ease of illustration) and a second key contact  107 . The second conductive trace is coupled to the second key contact  107 . 
     The conductive traces, in some examples, are silver conductive traces. That is, the first conductive trace can be silver conductive trace and/or the second conductive trace can be a silver conductive trace. However, the present disclosure is not so limited. Rather, the conductive traces can be formed of a variety of suitable materials including silver and carbon and/or combinations thereof, among other types of suitable materials. 
     The second key contact  107  is to contact the first key contact  105 , for example, when the first key contact  105  of the first circuit  104  is displaced by a displacement force applied to a key  118  coupled to the first key contact  105 , among other possibilities to contact the first key contact  105  and the second key contact  107 . For instance, the first key contact  105  may be displaced along a path of travel that is substantially perpendicular to the first circuit  104  and/or the second circuit  106 . Contact between the first key contact  105  and the second key contract  107  can include causing the first key contact  105  to move along the path of travel to be positioned adjacent to and/or substantially adjacent to the second key contact  107  to couple (e.g., electrically couple) the first key contact  105  with the second key contract  107 . 
     As illustrated in  FIG. 1 , the keyboard membrane  100  can include a spacer  111  formed of thermoplastic material  116 , the first thermoplastic film  113 , and the second thermoplastic film  115 . The spacer  111  can be disposed between the first circuit  104  and the second circuit  106  to provide a distance separating the first circuit  104  from the second circuit  106  (e.g., separating the first circuit  104  from the second circuit  106  absent a displacement force applied to the first circuit). That is, the spacer  111  can promote various performance characteristics, for example, disposition of the first circuit  104  and the second circuit  106  to have a desired force to fire (i.e., an amount of force applied to the keyboard membrane  100  sufficient to complete a switch formed between the first key contract  105  and the second key contract  107 . 
     As illustrated in  FIG. 1 , spacer  111  is formed of the first thermoplastic film  113 , the second thermoplastic film  115 , and the layer of thermoplastic material  116 . In various examples, the first thermoplastic film  113  is disposed on a first face  124  of the layer of thermoplastic material  116  and the second thermoplastic film  115  is disposed on a second face  126  of the layer of thermoplastic material  116  to form the spacer  111 , as described herein. 
     The first thermoplastic film  113  and the second thermoplastic film  115  refer to thermoplastic films that have suitable glass transition temperatures and/or melting points for thermally fused spacers, as described herein, and can be activated by heat and/or pressure to fuse together elements without use of solvents and/or without use of printed adhesives. Examples of suitable films include polyester based films, polyurethane based films, and/or combinations thereof, among other suitable thermoplastic films that can be activated by heat and/or pressure to fuse together elements without use of solvents (i.e., do not include solvents) and/or without use of printed adhesives. The first thermoplastic film  113  and the second thermoplastic film  115  can have respective glass transition temperatures and respective melting points comparatively lower than a melting point of a various other materials included in a keyboard membrane such as the thermoplastic material, a first circuit and/or a second circuit included in a keyboard membrane. 
     The thermoplastic material  116  refers to a thermoplastic material such as polyethylene terephthalate, among others thermoplastic materials having a suitable glass transition temperature and/or suitable melting point above glass transition temperatures and/or melting temperatures of the first thermoplastic film and the second thermoplastic film, as described herein, to promote thermally fused spacers. For example, the thermoplastic material  116  can have a glass transition temperature that is comparatively higher than a glass transition temperature of the first thermoplastic film  113  and/or a glass transition temperature the second thermoplastic film  115 . Similarly, the thermoplastic material  116  can have a melting point that is comparatively higher than a melting point of the first thermoplastic film  113  and/or a melting point the second thermoplastic film  115 . For instance, in some examples, the thermoplastic material  116  can have a melting point that is comparatively higher than a melting points of each of the first thermoplastic film  113  and the second thermoplastic film  115   
     In various examples, the spacer  111  overlays a portion of each of a first conductive trace and a second conductive trace to seal the first conductive trace and the second conductive trace, as described herein in greater detail with respect to  FIG. 2 . Put another way, the spacer  111  can include continuous layer of thermoplastic material that overlays both of a portion of the first conductive trace a portion of the second conductive trace. In some examples, the layer of thermoplastic material  116  of the spacer  111  overlays an entire length of at least one of the first conductive trace and the second conductive trace. 
     The spacer  111  can be from 10 microns to 1000 microns thick. All individual values and subranges from 10 microns to 1000 microns of thickness are included; for example, the thickness of the spacer  111  can be from a lower limit of 10 microns, 15 microns, 25, or 50 microns to an upper limit of 1000 microns, 900 microns, or 600 microns of thickness seal the first conductive trace and the second conductive trace. For example, the spacer  111  can have a particular thickness extending substantially perpendicular from a first face  108  of the first circuit  104  to a second face  110  of the second circuit  105 . 
     Put another way, the thickness of the spacer is equal to a total number of microns of thermoplastic material and thermoplastic material that form the spacer  111  and extend from the first face  108  of the first circuit  104  to the second face  110  of the second circuit  105 . In various examples, the first circuit  104  and the second circuit  105  can be co-planar at least with respect to their internal faces opposed to each other. For example, the first face  108  and the second face  110  can be co-planar as illustrated in  FIG. 1 . 
     The keyboard membrane  100  includes an opening  119  to permit the first key contact  105  to contact the second key contact  107 . For example, the opening  119  can extend from the first key contact  105  of the first circuit  104  to the second key contract  107  of the second circuit  106  through the spacer  111 , as illustrated in  FIG. 1 . 
     Such an opening can extend through cutouts included in a spacer, as described herein, to promote desired performance characteristics of a keyboard membrane including promoting a desired force to collapse the dome  118  (e.g., the desired force can be equal and/or in excess of a predetermined amount of force to collapse the dome  118 ) and/or a desired force to fire (e.g., the desired force to fire equal and/or in excess of a predetermined amount of force to fire), among other performance characteristics. Notably, at least of portion of the opening  119  extends through cutouts in the spacer  111  (i.e., through cutouts included in a layer of thermoplastic material  116  and through the first and second thermoplastic films forming the spacer  111 ) from the first key contact  105  to the second key contact  106 . For instance, at least a portion of the opening  119  extends from the first key contact  105  of the first circuit  104  to the second key contact  107  of the second circuit  106  to provide a potential for contact of the first key contact  105  with the second key contact  107  in response to a displacement force applied to the keyboard membrane  100 , as illustrated in  FIG. 1 . 
       FIG. 2  illustrates an exploded view of an example of a keyboard membrane  240  including a thermally fused spacer according to the disclosure. As mentioned, the keyboard membrane  240  includes a first circuit  204 , a second circuit  206 , and a spacer  211 . The keyboard membrane  240  is analogous to keyboard membranes  100  and  380  referenced by  FIG. 1  and  FIG. 3 , respectively. 
     The keyboard membrane  240  can include a vent  248 . Vent refers to an orifice extending through the first circuit  204  and/or the second circuit  206 . That is, while the vent  248  is illustrated as extending through an entire thickness of the second circuit  206  as illustrated in  FIG. 2 , the disclosure is not so limited. Rather, a location and/or a total number of vents included in the first circuit  204  and/or the second circuit  206  can be varied to vent the keyboard membrane  240  (e.g., to ensure intended movement of the key contacts) and/or otherwise promote thermally fused spacers. 
     As illustrated in  FIG. 2 , the keyboard membrane  240  can include a plurality of conductive traces  242 - 1 ,  242 - 2 , . . . ,  242 -T and/or  244 - 1 ,  244 - 2 , . . . ,  244 -B. However, while three conductive traces  242 - 1 ,  242 - 2 , . . . ,  242 -T are illustrated on the first circuit  204  and three conductive traces  244 - 1 ,  244 - 2 , . . . ,  244 -B are illustrated on the second circuit  206  the disclosure is not so limited. A total number, orientation, and/or a location of conductive traces and/or keycaps can be varied to promote thermally fused spacers. 
     As illustrated, the keyboard membrane  240  can include a plurality of keycaps coupled to the plurality of conductive traces. For example, a first key contact  205  is coupled to a first conductive trace. Similarly, a second key contact  207  is coupled to a second conductive trace  244 - 1 . 
     As mentioned, the spacer  211  is formed of a first thermoplastic film  213 , a second thermoplastic film  215 , and a layer of thermoplastic material  216 . The spacer  211  can include a plurality of cutouts  262 - 1 ,  262 - 2 , . . . ,  262 -C. It is noted that keycaps, key mechanisms, and domes of the keycaps have been omitted from  FIG. 2  and  FIG. 3  for ease of illustration. As illustrated, the cutouts  262 - 1 , . . . ,  262 -C extend through the spacer  211 . The plurality of cutouts  262 - 1 , . . . ,  262 -C (e.g., each of plurality of cutouts) can be coupled to an opening in the keyboard membrane  260  described with respect to  FIG. 1 . For example, the plurality of cutouts  262 - 1 , . . . ,  262 -C can permit a key (e.g., key  118  as described with respect to  FIG. 1 ) to travel through the plurality of cutouts. For instance, the plurality of cutouts  262 - 1 , . . . ,  262 -C can permit a key to travel through the cutouts and/or into a portion of a volume of the space in the keyboard membrane, as described herein. While  FIG. 2  illustrates three cutouts  262 - 1 ,  262 - 2 , . . . ,  262 -C having particular shapes and orientations the present disclosure is not so limited. That is, a total number, location, and/or shape, among other aspects of the plurality of cutouts  262 - 1 , . . . ,  262 -C can be varied to promote thermally fused spacers. 
     It is noted that the  262 - 1 ,  262 - 2 , . . . ,  262 -C are formed in a manner such that each of the cutouts interconnects a plurality of key contacts such as cutout  262 - 1  the interconnects two key contacts Similarly, cutout  262 - 2  interconnects three key contacts. Having the cutouts  262 - 1 ,  262 - 2 , . . . ,  262 -C each interconnect a plurality of key contacts can promote venting of the keyboard membrane, which can be particularly evident when a cutout such as cutout  262 - 2  interconnects a plurality of key contacts and at least one vent such as vent  248  that is overlapped by the cutout  262 - 2  and thereby the vent  248  is interconnected via the cutout  262 - 2  with three key contacts, as is illustrated in  FIG. 2  and  FIG. 3 . That is, in some examples, the spacer includes cutouts in communication with at least one vent. 
       FIG. 3  illustrates a top view of an example of a keyboard membrane  380  including a thermally fused spacer according to the disclosure. Keycaps, key mechanisms, domes of the keycaps, and electrical bridges have been omitted from  FIG. 3  for ease of illustration. For descriptive purposes elements such as cutouts and conductive traces of a second circuit are illustrated in  FIG. 3  although such elements may ordinarily be obstructed from the top view of the keyboard membrane  380 . 
     As illustrated in  FIG. 3 , the keyboard membrane  380  includes a first circuit including conductive traces  342 - 1 ,  342 - 2 , . . .  342 -T, a spacer (not shown for ease of illustration) formed of thermoplastic material including cutouts  362 - 1 ,  362 - 2 , . . . ,  362 -C, a second circuit (not show for ease of illustration) including conductive traces  364 - 1 ,  364 - 2 , . . . ,  364 -B, and vent  348 . The conductive traces  342 - 1 , . . . ,  342 -T and  364 - 1 , . . . ,  364 -B can be coupled to key contacts. For example, a first conductive trace  342 - 1  is coupled to a first key contact  305 , as illustrated in  FIG. 3 . 
       FIG. 4  illustrates a flow diagram of an example of a method of manufacture of keyboard membranes including a thermally fused spacer according to the disclosure. As illustrated at  494 , the method  490  can include providing a first circuit including a first conductive trace and a first key contact of the keyboard membrane, where the first conductive trace is coupled to the key contact. 
     Similarly, the method  490  can include providing a second circuit including a second conductive trace and a second key contact of the keyboard membrane, where the second conductive trace is coupled to the second key contact, as illustrated at  495 . Providing can include manufacture of and/or otherwise procuring the first circuit and the second circuit. 
     As illustrated at  496 , the method  490  can include disposing a first thermoplastic film on a first face of a layer of thermoplastic material. The method  490  can include disposing a second thermoplastic film on a second face of the layer of thermoplastic material to form a spacer, as illustrated at  497 . Notably and in contrast to other approaches, the method  490  does not include printing adhesive and/or use of solvent based adhesives to form the keyboard membrane. That is, keyboard membranes as described herein are formed without and therefore do not include various materials (e.g., UV curable inks and/or printed adhesives) employed by other approaches. 
     As illustrated at  498 , the method  490  can include causing the first thermoplastic film and the second thermoplastic film to a reach a temperature above respective glass transition temperatures of the first thermoplastic film and the second thermoplastic film to fuse the spacer to the first circuit and the second circuit when the spacer is adjacent to the first circuit and the second circuit to form the keyboard membrane. Causing refers to directly causing the first thermoplastic film and the second thermoplastic film to a reach temperature above respective glass transition temperatures of the first thermoplastic film and the second thermoplastic film or performing an action with an expectation of the first thermoplastic film and the second thermoplastic film to a reach temperature above respective glass transition temperatures of the first thermoplastic film and the second thermoplastic film. 
     Causing the first thermoplastic film and the second thermoplastic film to reach the temperature above the respective glass transition temperatures can include heating and/or applying pressure to the first thermoplastic film and the second thermoplastic film. In some examples, causing the first thermoplastic film and the second thermoplastic film to reach the temperature above the respective glass transition temperatures comprises heating the first thermoplastic film and the second thermoplastic film to a temperature between about 40° C. to about 65° C. Causing can, in some examples, include applying at least 448 kilopascals of pressure to the first thermoplastic film and the second thermoplastic film. 
     For example, the first thermoplastic film and the second thermoplastic film can be fused or otherwise suitable coupled to a first circuit and/or a second circuit when the first thermoplastic film and the second thermoplastic film included in the spacer are positioned between the first and second circuits and brought above respective glass transition temperatures of the first thermoplastic film and the second thermoplastic film to form a keyboard membrane, as described herein. For instance, in some examples, spacer including the first thermoplastic film and the second thermoplastic film can be positioned between the first circuit and the second circuit and subsequently brought above respective glass transition temperatures the first thermoplastic film and the second thermoplastic film and/or above respective melting points of the first thermoplastic film and the second thermoplastic film such that the first thermoplastic film and the second thermoplastic film are allowed to cool to a temperature lower than the respective glass transition temperatures and/or the respective melting points to form keyboard membrane where the spacer is fused to the second circuit and the first circuit. 
     In some examples, the method  490  can include bringing the thermoplastic material above its glass transition temperature comprises heating the thermoplastic material to a temperature between about 40° C. to about 65° C. and applying at least 448 kilopascals of pressure to the thermoplastic material. That is, all temperatures included in the range between about 40° C. to about 65° C. are included. For instance, the thermoplastic material can be heated to about 40° C., 50° C., ° C., 60° C., or about 65° C., among other possibilities to promote thermally fused spacers as described herein. 
     It will be understood that when an element is referred to as being “on,” “connected to”, “coupled to”, or “coupled with” another element, it can be directly on, connected, or coupled with the other element or intervening elements may be present. In contrast, when an object is “directly coupled to” or “directly coupled with” or ‘directly fused’ to another element it is understood that are no intervening elements (adhesives, screws, other elements) etc. and/or no other intervening elements other than a particular intervening element specified (e.g., a thermoplastic film). 
     In the foregoing detailed description of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration how examples of the disclosure may be practiced. These examples are described in sufficient detail to enable those of ordinary skill in the art to practice the examples of this disclosure, and it is to be understood that other examples (e.g., having different thickness) may be utilized and that process, electrical, and/or structural changes may be made without departing from the scope of the disclosure. 
     The figures herein follow a numbering convention in which the first digit corresponds to the drawing figure number and the remaining digits identify an element or component in the drawing. For example, reference numeral  105  may refer to element  105  in  FIG. 1  and an analogous element may be identified by reference numeral  205  in  FIG. 2 . 
     Elements shown in the various figures herein can be added, exchanged, and/or eliminated so as to provide a number of additional examples of the disclosure. In addition, the proportion and the relative scale of the elements provided in the figures are intended to illustrate the examples of the disclosure, and should not be taken in a limiting sense. Further, as used herein, “a number of” an element and/or feature can refer to one or more of such elements and/or features. Further still, while some elements are designated as a “top” view those of ordinary skill in the art will recognize that such orientations may correspond to a “bottom” view in some applications in order to practice the examples of this disclosure.