Patent Application
20070236462
Users of mobile electronic devices often carry them throughout the day, while handling food and drinks, etc. Such use makes these devices more susceptible to damage from, for example, spills which penetrate housing openings adjacent to the keypad, etc. The housing openings also make the device susceptible to environmental contaminants, such as dust, moisture, etc.
As shown in
The present invention is directed to a device comprising a housing including an internal chamber and an external keypad mounting area and a primary printed circuit board comprising expensive circuitry and components mounted within the internal chamber in combination with a secondary, simple and inexpensive printed circuit board mounted in the external keypad mounting area, the secondary printed circuit board being electrically coupled to the primary printed circuit board and a plurality of switches corresponding to the keys of the key pad over the secondary printed circuit board and a key pad including a plurality of keys mounted in a predetermined alignment over the plurality of switches so that the secondary printed circuit board is between the key pad and a surface of the external key pad mounting area and the switches are between the second printed circuit board and the key pad. Those of skill in the art will understand that the present invention reduces the chance that the primary, expensive printed circuit board will be damaged.
a shows a front view of an external printed circuit board according to the present invention;
b shows a rear view of the external printed circuit board of
The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The present invention will be described with reference to mobile electronic devices (e.g., PDA's, palm sized personal computers, cellular telephones, global positioning systems (GPS), bar code scanners, digital imagers, radio frequency identification (RFID) devices, etc.). However, those skilled in the art will understand that the integrations according to the present invention are equally suited for any electronic device utilizing a keypad or other plurality of buttons, such as, for example, mobile and stationary electronic devices including telephones, printers, copy machines, etc.
The housing 30 according to this embodiment includes a first opening 32 which, in this case, is a cutout sized and shaped to present for access or observation by a user an active surface of a display 33 (e.g., a passive display or touchscreen) while the balance of the display 33 is received within the chamber 31 of the housing 30. An entire perimeter of this opening 32 is sealed in a conventional manner to protect the components within the chamber 31 of the housing 30 from any liquid or other potentially harmful substance with which the display 33 may come into contact. The housing 30 further includes a keypad receiving cavity 35 formed by a keypad supporting surface 34 and surrounding side walls 37. However, it will be understood by those of skill in the art that the keypad of the present invention may be positioned on any surface of the housing 30, whether or not a cavity such as the cavity 35 is included. Those skilled in the art will understand that the cavity 35 is preferably sized and shaped to accommodate a keypad arrangement 50 which includes, for example, an external circuit board 40, a keypad 52 comprising a plurality of keys 53 coupled to a flexible sheet 54, and a frame 56, as shown in
The housing 30 includes a second opening 36 extending through the keypad supporting surface 34 allowing electrical communication between components in the keypad receiving cavity 35 and the primary PCB 60 which is located within the housing 30, as shown in
The keypad 52 is placed over the secondary external circuit board 40 so that a plurality of keys 53 thereof, which may be depressed by a user to enter input to the mobile device, are in a desired alignment with the switches 42. In one embodiment of the present invention, the keys 53 are mechanically coupled to a flexible sheet (e.g., the keypad film 54) which may be composed of any of a number of materials, including but not limited to rubber, plastic, which can flex without breakage or fatigue when a key 53 is pressed. Accordingly, openings in the keypad film 54 are preferably minimized or, if possible, eliminated to protect the secondary external circuit board 40 from foreign substances with which the keypad 52 may come in contact. In one embodiment of the present invention, the keys 53 are coupled to the keypad film 54 by an adhesive, male/female mating, etc. According to another embodiment, the keys 53 are formed integrally with the keypad film 54.
As further shown in
As shown in
In one embodiment of the present invention, the connector 44 is a pin and socket connector including a plurality of data pins 46. However, it will be understood by those of skill in the art that any of a variety of connectors may be used. As shown, the connector 44 is sized to fit comfortably within the second opening 36 with a surface of the secondary external circuit board 40 lying flush against the keypad supporting surface 34 of the housing 30. In one exemplary embodiment, an adhesive membrane may seal the secondary external circuit board 40 to the housing 30. Thus, the port 36 is completely enclosed, and the possibility for liquid or other substances to pass therethrough is minimized.
Thus, the keypad supporting surface 34 contains only a single opening (second opening 36) to accommodate all of the electrical connections between a plurality of keys 53 and the primary PCB 60 and a seal 48 extends around the entire perimeter of the second opening 36 so that any liquid spilled on the keypad arrangement 50 is prevented from passing through the keypad supporting surface 34. This seal 48 is more effective than the seals in the conventional keypads as there is no relative movement between the seal 48 and the components passing through the second opening 36. The second opening 36 may be any size and shape, although it is preferable for the second opening 36 to be as small as possible while accommodating the desired connection arrangement. For example, according to an embodiment of the present invention, the second opening 36 is approximately 50 mm2. The second opening 36 according to this embodiment is substantially rectangular as this facilitates manufacturing the housing 30 and sealing the second opening 36. Specifically, the second opening 36 is preferably lined with a sealant (e.g., latex, urethane, silicone, fibrin, etc.) to prevent any substance from passing therethrough.
a shows a front view of the secondary external circuit board 40 which preferably handles only those functions necessary to transfer data between the keypad 52 and the primary PCB 60. Thus, if liquid spilled on the keypad 52 penetrates past the keypad film 54, the secondary external circuit board 40 may be shorted out. However, the liquid will be prevented from passing across past the keypad supporting surface 34 to the primary PCB 60. Thus, spills will be prevented from damaging the major components of the device 28 and, if liquid does pass through the keypad film 54 shorting out the secondary external circuit board 40, the device 28 may be repaired by simply replacing this component. According to the present invention, the secondary external circuit board 40 is separate and distinct from the primary PCB 60 while electrically coupled thereto. The secondary external circuit board 40 may reside on an outer surface of the housing 30, such as on the keypad supporting surface 34. As described above, a plurality of switches 42 are formed on the secondary external circuit board 40 to operate in conjunction with keys.
In step 84, the primary PCB 60 is positioned within the housing 30 and, in step 86, the secondary external circuit board 40 is positioned on the housing 30 with the connector 44 aligned with the second opening 36 and corresponding circuitry 62 (e.g., the complementing connector) of the primary PCB 60 for electrical connection to the primary PCB 60 (step 88).
In step 90, the keypad 52 is positioned in a desired alignment on the secondary external circuit board 40 as described above and, in step 92, the frame 56 is positioned on the keypad 52 and secured to the housing 30 by, for example, screws, adhesive, fasteners, etc. If necessary, an overlay 58 is positioned over the frame 56 to increase an aesthetic value of the keypad assembly.
An advantage of the keypad assembly of the present invention is that it saves a considerable amount of space. For example, because the secondary external circuit board 40 is separate from the primary PCB 60, the primary PCB 60 may be made smaller allowing size of the chamber 31 and the size of the housing 30 to be reduced. Alternatively or additionally, additional circuitry may be placed on the primary PCB 60, enabling the mobile device 38 to perform an increased number of functions without increasing the size of the primary PCB 60 and the chamber 31. Also, a greater number of keys 53 may be included in the keypad arrangement, because there is more space available for the larger switches 42 or for an increased number of switches 42. For example, in some smaller conventional keypad assemblies each key represents a number of letters and/or numbers requiring the user to press keys numerous times when entering a single character. Embodiments of the present invention may allow certain of these keypads to be expanded with separate keys for a larger number of characters. In addition, the present invention may reduce a number of configurations of the primary PCB 60.
From the above description of the exemplary embodiments, those of skill in the art will understand that the present invention may reduce space needed for bosses on the keypad area of a mobile device, allowing for the greater number and/or larger keys 53. The mobile device is designed with the knowledge that space is needed for fastening components of the device, e.g., halves of the housing 30, the keypad, etc. According to the present invention, fasteners (e.g., screws) may secure the keypad to the cavity 35 and an upper half of the housing 30.
It will be apparent to those skilled in the art that various modifications and variations can be made in the structure and the methodology of the present invention, without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
