Abstract:
A switch matrix is disclosed for keypads used in devices such as primary control points for automation systems in homes vehicles, or businesses. The switch matrix preferably includes a support frame for supporting a grid of key positioning members arranged in a series of rows and columns. The key positioning members each preferably include cantilevers which can be deflected by pressing the keys to activate switches associated with the keypad. The cantilevers preferably have knobs which are received in corresponding openings in the keys so that the keys can be removably attached to the cantilevers with a compression fit. This allows keys of different sizes and shapes to be easily attached to the keypad in various configurations without the need for different attaching devices for each situation.

Description:
[0001]    CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0002]    This application claims the benefit of U.S. Provisional Application No. 60/272,020, filed Feb. 28, 2001, which is hereby incorporated by reference herein in its entirety, including but not limited to those portions that specifically appear hereinafter. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0003]    1. The Field of the Invention  
           [0004]    The present invention relates generally to keypad devices, and more particularly, but not necessarily entirely, to a switch matrix which allows the use of variable key positions and key sizes on the keypad.  
           [0005]    2. Description of Related Art  
           [0006]    It is common practice to provide keypads consisting of one or more keys arranged for entry of data or performing functions such as activating switches. Keypads are used for various types of electronic devices such as user interfaces for home automation and security systems, calculators, telephones, etc. Keypads commonly include an assembly of various parts maintained in a housing.  
           [0007]    For example, FIG. 1 shows a keypad, generally indicated at  2 , known in the art for use as a primary control point for automation systems used in areas such as homes, businesses, boats, yachts, motor homes and busses. The keypad  2  includes a plurality of keys  8  which can be depressed to control systems such as lighting, security, audio visual and heating/cooling for example. The keys  8  are connected to electronic circuitry which is contained in a housing  4 . The keys  8  are fixed in place by an attaching plate  6  so as to be non-removable from the keypad  2 . The attaching plate  6  has apertures  7  through which the keys  8  protrude. The apertures  7  are sized and shaped to accommodate keys  8  of a particular size and shape. Therefore, a different attaching plate  6  is required for each size and shape of keys  8  used for the keypad  2 . Furthermore, the location of the keys  8  is confined to the locations of the apertures  7 . Therefore, a different attaching plate  6  must be used for different configurations of the keys  8 . Moreover, if any of the keys  8  become damaged or require replacement, the entire keypad  2  must be replaced or the attaching plate  6  must be removed. Removal of the attaching plate  6  is a difficult task which may require the services of a professional or use of specialized equipment since the attaching plate  6  is fixed to the housing  4  and is not designed to be easily removed without damaging the attaching plate  6  or the housing  4 .  
           [0008]    The prior art is thus characterized by several disadvantages that are addressed by the present invention. The present invention minimizes, and in some aspects eliminates, the above-mentioned failures, and other problems, by utilizing the methods and structural features described herein.  
           [0009]    In view of the foregoing state of the art, it would be an advancement in the art to provide a switch matrix which is capable of being used with keys of different sizes and shapes. It would be a further advancement in the art to provide a switch matrix which allows the keys to be arranged in different configurations using differing numbers of keys. It would also be an advancement in the art to provide a switch matrix which allows the keys to be easily installed and replaced without damaging the matrix.  
         BRIEF SUMMARY  
         [0010]    In view of the above described state of the art, the present invention seeks to realize one or more of the following objects and advantages.  
           [0011]    It is a primary object of the present invention to provide a switch matrix which is simple in design and manufacture.  
           [0012]    It is another object of the present invention to provide such a switch matrix which is capable of being used with keys of different sizes and shapes.  
           [0013]    It is a further object of the present invention, in accordance with one aspect thereof, to provide a switch matrix which allows the keys to be arranged in different configurations using differing numbers of keys.  
           [0014]    It is an additional object of the invention, in accordance with one aspect thereof, to provide a switch matrix which allows the keys to be easily installed and replaced without damaging the matrix.  
           [0015]    The above objects and others not specifically recited are realized in a specific illustrative embodiment of a switch matrix device. The device preferably includes a support frame including at least one longitudinal member and at least one lateral member substantially perpendicular to the longitudinal member. The switch matrix also preferably includes a grid of key positioning members disposed on the support frame in a series of rows and columns. The key positioning members each preferably include a first cantilever and a second cantilever. The second cantilever preferably includes a pair of arms. An attaching end of the first cantilever is preferably attached to a free end of the second cantilever such that the first cantilever extends parallel to the second cantilever between the pair of arms and towards the fixed end of the second cantilever. The first cantilever also preferably has a key attaching means for removably attaching a key to the key positioning member. The key attaching means preferably includes a knob which is adapted to be fitted into an opening in the keys with a corresponding shape to form a compression fit between the key and the attaching means. This allows the keys to be removably attached to the switch matrix so that keys of differing sizes and shapes may be utilized. The key positioning members are preferably configured to deflect when the key is depressed to activate a switch with a switch activating protrusion which is preferably disposed on the opposite side of the first cantilever from the key attaching means. The keys can preferably be selectively attached to the key positioning members in various configurations suited for a particular application.  
           [0016]    Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by the practice of the invention without undue experimentation. The objects and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    The above and other objects, features and advantages of the invention will become apparent from a consideration of the subsequent detailed description presented in connection with the accompanying drawings in which:  
         [0018]    [0018]FIG. 1 is a front view of a prior art keypad for an automation system;  
         [0019]    [0019]FIG. 2 is a side view of the prior art keypad of FIG. 1;  
         [0020]    [0020]FIG. 3 is an exploded perspective view of a keypad showing a preferred embodiment of the switch matrix of the present invention;  
         [0021]    [0021]FIG. 4 is a plan view of a preferred embodiment of the switch matrix of the present invention;  
         [0022]    [0022]FIG. 5 is a side view of the switch matrix of FIG. 4;  
         [0023]    [0023]FIG. 6 is an end view of the switch matrix of FIG. 4;  
         [0024]    [0024]FIG. 7 is a bottom perspective view of an exemplary embodiment of a key used in conjunction with the switch matrix of the present invention;  
         [0025]    [0025]FIG. 8 is a top perspective view of the exemplary embodiment of the key of FIG. 7;  
         [0026]    [0026]FIG. 9 is a plan view of an exemplary embodiment of one of many key configurations made possible by the switch matrix of the present invention;  
         [0027]    [0027]FIG. 10 is an exploded perspective view of an alternative embodiment of the switch matrix in a different keypad environment; and  
         [0028]    [0028]FIG. 11 is a break-away perspective bottom view of a cantilever system of the switch matrix of FIGS.  3 - 6 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]    For the purposes of promoting an understanding of the principles in accordance with the invention, reference will now be made to the preferred embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications of the inventive features illustrated herein, and any additional applications of the principles of the invention as illustrated herein, which would normally occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the invention claimed.  
         [0030]    Referring now to FIG. 3, an exploded perspective view of a keypad, generally indicated at  10 , is shown including a preferred embodiment of a switch matrix  20  of the present invention. The keypad  10  may be used as a user interface for home automation and security systems, for example. The keypad  10  preferably includes a plurality of keys  12  which can be depressed to control systems such as lighting, security, audio visual and heating/cooling for example. However, it will be appreciated by those skilled in the art that the keypad  10  may be used in other environments within the scope of the present invention. Other such environments include calculators, telephones, and office equipment, for example.  
         [0031]    A housing assembly  14  for the keypad  10  may be configured in various forms. The housing assembly  14  is shown in FIG. 3, as a combination of a front plate  14   a , a back plate  14   b  and a back box  14   c , which can be joined together in any suitable manner well known to those skilled in the art. The housing assembly  14  preferably receives electronic control devices such as electronic circuitry board  60  containing switches  62  which can be activated to perform a particular function. Any number of different types of electronic circuitry boards  60  can be utilized within the scope of the present invention and such electronic circuitry boards  60  can readily be arrived at by those skilled in the pertinent art. Switches  62  may be of any variety known in the art which are activated by a mechanical action such as a pressing force. For example, switches  62  may include resilient members which are deflected by a force to close a circuit, and upon release of the force, the resilient members rebound to open the circuit. The electronic circuitry board  60  may be attached to the housing assembly  14  in any suitable manner known in the art such as soldering, adhesives or fasteners, for example. The switch matrix  20  is preferably attached to the housing assembly  14 , as described more fully below, such that keys  12  may be attached to the switch matrix  20  to correspond to the location of the switches  62 . A face plate  70  preferably covers the switch matrix  20  to improve the appearance of the keypad  10  and to provide further protection of the contents of the housing assembly  14 . The face plate  70  may be attached to the housing assembly  14  in any manner known in the art such as magnets or fasteners, for example.  
         [0032]    Referring now to FIG. 4, a plan view of a preferred embodiment of the switch matrix  20  is shown. The switch matrix  20  preferably includes a support frame  22 . The support frame  22  preferably includes at least one longitudinal member  24  and at least one lateral member  26  which, in the illustrated embodiment, are substantially perpendicular to each other. More preferably, the support frame  22  includes two longitudinal members  24  and a plurality of lateral members  26  arranged to support a grid of key positioning members  28 .  
         [0033]    The key positioning members  28  preferably include a first cantilever  30  having an attached end  32 , shown most clearly in FIG. 11. The attached end  32  of the first cantilever  30  is preferably attached to a free end  38  of a second cantilever  34 . The second cantilever  34  is preferably disposed on the support frame  22  at a fixed end  36  and includes a pair of spaced apart arms  40  such that the first cantilever  30  may reside between the arms  40  and parallel to the arms  40 . The configuration of the first cantilever  30  and the second cantilever  34  allows for improved deflection and force transfer capabilities in that the key positioning member  28  allows for deflection in a substantially linear direction. For example, the first cantilever  30  preferably deflects in a curved path  31  with respect to the attached end  32 . Whereas the second cantilever  34  deflects in a oppositely curved path  33  with respect to the fixed end  36  of the second cantilever  34 . The opposite curvature of curved path  31  of the first cantilever  30  and the curved path  33  of the second cantilever  34 , tend to reduce the amount of curvature in travel path of the key positioning member  28  such that deflection of the key positioning member  28  takes place in a substantially linear direction.  
         [0034]    A switch activating protrusion  42 , shown in FIGS. 6 and 11, is preferably disposed on a bottom side of the first cantilever  30 . The switch activating protrusion  42  is configured to contact the switch  62  (see FIG. 3) as the first cantilever  30  is depressed. The upper side of the first cantilever  30  preferably includes a knob  44  which may be inserted into an opening  46  defined by a sidewall  47  of the key  12 , as shown in FIG. 7. The knob  44  and opening  46  are preferably sized to create a compression or friction fit between the key  12  and the knob  44  such that the key  12  is held tightly in place. However, the key  12  is not permanently fixed to the knob  44  such that the key  12  may be removed from the knob  44  if desired. The knob  44  is one preferred example of a key attaching means. Other means for removably attaching a key  12  to the switch matrix  20  may be used within the scope of the present invention. For example, the knob  44  may be located on the key  12  and the opening  46  may be located on the switch matrix  20 .  
         [0035]    It will be appreciated that the structure and apparatus disclosed herein is merely one example of a key attaching means for removably attaching a key to the switch matrix, and it should be appreciated that any structure, apparatus or system for removably attaching a key to the switch matrix which performs functions the same as, or equivalent to, those disclosed herein are intended to fall within the scope of a means for removably attaching a key to the switch matrix, including those structures, apparatus or systems for removably attaching a key to the switch matrix which are presently known, or which may become available in the future. Any structure which functions the same as, or equivalently to, the herein described means for removably attaching a key to the switch matrix falls within the scope of this element as set forth in the claims.  
         [0036]    The knob  44  (FIG. 6) may have a diamond shape, for example, which corresponds to the opening  46  also having a diamond shaped and provided in the key  12 . As those skilled in the art will appreciate, knobs  44  and openings  46  of other shapes, and other structures to removably attach the key  12  to the switch matrix  20 , may be used within the scope of the present invention. Furthermore, the size and shape of the key  12  is not dependant upon the means for removably attaching the key  12  to the switch matrix  20 . In the prior art system shown in FIG. 1, the apertures  7  of the attaching plate have a size and shape configured for specific keys, whereas the switch matrix  20  of the present invention advantageously allows keys  12  of various sizes and shapes to be attached. Those skilled in the art will appreciate that advantages which the present invention provides by allowing different number of keys and different sizes and shapes of keys to be utilized.  
         [0037]    The switch matrix  20  may also include abutments  43  on opposing sides of the support frame  22 , as shown most clearly in FIGS.  4 - 6 . The abutments  43  may project from the switch matrix  20  to contact the face plate  70  to prevent the face plate  70  from flexing into the knobs  44 . The abutments  43  may therefore prevent activation of the switches  62  due to forces applied to the face plate  70 .  
         [0038]    [0038]FIGS. 7 and 8 show an exemplary embodiment of the key  12 . Many different variations of key  12  may be formed utilizing various sizes and shapes in addition to those shown in the figures. For example, the keys  12  may be round, triangular, oval, polygonal, or in the shape of objects such as arrows, waves or light bulbs or any other shape. Preferably, keys  12  include a key body  48  and a light pipe  50 . The key body  48  provides a surface area which can be depressed by a human user to activate the switch  62  (see FIG. 3). The key body  48  may also be engraved or labeled to provide an indication of the function of the key  12 . The key  12  may further include one or more stops  49  to prevent the key  12  from passing through the face plate  70 . The stops  49  may be segmented or continuous around a bottom edge  51  of the key  12 .  
         [0039]    The light pipe  50  is preferably made of a translucent material which directs light from a light source  63  (see FIG. 3) located below the key  12  to the upper surface  56  of the key  12 . Thus the light pipe  50  allows the transmission of light from the electronic circuitry board  60  to the upper surface  56  of the key  12  to provide visual signals to the user. The light pipe  50  is preferably attached to the key body  48  without the use of adhesive or tools. For example, the light pipe  50  may have a projection (not shown) which may be inserted into a cavity (not shown) in the key body  48  such that the light pipe  50  is held to the key body  48  through friction. The key body  48  may be configured with cut-out portions, such as depicted at  53  in FIG. 7, to reduce the amount of material required to manufacture the key body  48  where possible.  
         [0040]    The light source  63  is preferably located on the electronic circuitry board  60  in close proximity to the switches  62  as shown in FIG. 3. The light source  63  may include one or more light emitting diodes, for example. The light source  63  may utilize a single or multiple colors, and may be programmed to blink, change colors, or vary in illumination intensity to indicate the status of the keypad  10 . It will be appreciated that other devices for generating light may be used within the scope of the present invention.  
         [0041]    The switch matrix  20  also preferably includes aligning posts  58 , as shown in FIGS. 5 and 6, which extend from an undersurface of the switch matrix  20  to register with recesses  65  on the electronic circuitry board  60  (FIG. 3). The aligning posts  58  align the switch matrix  20  so that the switch activating protrusions  42  register properly with the switches  62 . It will be appreciated that other structures may be used within the scope of the present invention to align the switch matrix  20  with the electronic circuitry board  60 .  
         [0042]    The switch matrix  20  also preferably includes grooves  64  disposed in the support frame  22 . The grooves  64  are preferably configured to receive tabs  15  (see FIG. 3) located on the housing assembly  14  to hold the switch matrix  20  in place with respect to the housing assembly  14 . It will be appreciated by those skilled in the art that other structures besides the grooves  64  and the tabs  15  may be used within the scope of the present invention to hold the switch matrix  20  in place with respect to the housing assembly  14 .  
         [0043]    The switch matrix  20  is preferably formed as a single piece from molded plastic. However, as those skilled in the art will appreciate, other materials may be used to form the switch matrix  20  within the scope of the present invention.  
         [0044]    In use, keys  12  are attached to any or all of the key positioning members  28  to correspond with the position of the switches  62  on the electronic circuitry board  60 . An exemplary configuration of the keys  12  on the switch matrix  20  is shown in FIG. 9. It will be appreciated that numerous different configurations of keys  12  are possible in addition to that shown in FIG. 9. A key  12  may be so large as to cover multiple key positioning members  28 , or small enough such that a key  12  may be attached to all key positioning members  28 . Furthermore, the switch matrix  20  may be constructed to contain any different number of key positioning members  28  such that the number of possible key configurations is very large. The keys  12  may be attached to the switch matrix  20  in a desired configuration without the need for making modifications to the switch matrix  20 . Therefore, the switch matrix  20  can be more easily installed at a location in the field where the switch matrix  20  is being installed since the need for specialized tools or equipment, as required by the prior art, is eliminated. Furthermore, the switch matrix  20  is adapted for numerous different key configurations so a single switch matrix  20  can be used in the place of multiple attaching plates  6  as required by the prior art for different key configurations.  
         [0045]    If the need arises to repair or replace a key  12 , the key  12  may simply be detached from the switch matrix  20  by pulling on the key  12  with sufficient force to overcome the compression fit between the knob  44  and the opening  46 . This can be done without removing the switch matrix  20  from the housing assembly  14 , and without damaging the switch matrix  20 . The ease with which the keys  12  may be replaced allows users to maintain and repair the keys  12  without the need for purchasing a new keypad  10 , obtaining specialized tools or hiring a technician to perform the work.  
         [0046]    Reference will now to made to FIG. 10 to describe a second presently preferred embodiment of the present invention. As previously discussed, the presently preferred embodiments of the invention illustrated herein are merely exemplary of the possible embodiments of the invention, including that illustrated in FIG. 10.  
         [0047]    It will be appreciated that the second embodiment of the invention illustrated in FIG. 10 contains many of the same structures represented in FIGS.  1 - 9  and only the new or different structures will be explained to most succinctly explain the additional advantages which come with the embodiment of the invention illustrated in FIG. 10. The second embodiment of the inventive switch matrix  120  is shown in a different keypad environment  110 . The second embodiment of the switch matrix  120  preferably includes legs  166  to support and align the switch matrix  120  within the keypad  110 . The switch matrix  120  also preferably includes clips  168  to attach the switch matrix  120  to other components of the keypad  110 . Other components of the keypad  110  may include a back box  114   c , a back plate  114   b , an additional printed circuit board  116 , a first insulator  117 , a bracket  118  and a second insulator  119 . The keypad  110  may also include an optional input unit  172 . The optional input unit  172  may include a built in infrared receiver which may allow a user to transmit commands to the keypad  110  from a remote location. The keypad  110  may also have a service switch lever  174  for performing functions such as cutting the flow of electricity in the keypad  110 . It will be appreciated that numerous other configurations of components of the keypad  110  may be used within the scope of the present invention. The components of the keypad  110  illustrated in FIG. 10 are merely exemplary of the numerous environments in which the switch matrix  120  may be utilized.  
         [0048]    In view of the foregoing, it will be appreciated that the present invention provides a switch matrix which is capable of being used with keys of different sizes and shapes. The present invention also provides a switch matrix which allows the keys to be arranged in different configurations using differing numbers of keys. The present invention further provides a switch matrix which allows the keys to be easily installed and replaced without damaging the matrix.  
         [0049]    It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present invention and the appended claims are intended to cover such modifications and arrangements. Thus, while the present invention have been shown in the drawings and fully described above with particularity and detail in connection with what is presently deemed to be the most practical and preferred embodiments of the invention, it will be apparent to those of ordinary skill in the art that numerous modifications, including, but not limited to, variations in size, materials, shape, form, function and manner of operation, assembly and use may be made without departing from the principles and concepts set forth herein.