Patent Application
20110267272
The present invention relates generally to input devices and, more specifically, to keyboards. More particularly, the present disclosure relates to panel-mounted keyboards that may be suitable for use in industrial environments.
Computer systems often receive user input through keyboard devices. In some systems, such as notebook computer systems, a keyboard is integrated into a chassis that includes some or all of the other components of the system, such as a central processing unit, memory, display, and/or peripheral control devices.
Computer keyboards can be susceptible to wear, damage, and deterioration, especially when used in industrial environments. For example, some keyboards are exposed to water, oils, or other liquids, dust, chemicals, and other contaminants that can damage the keyboard. In addition, keyboards often include mechanical components that may fail due to excessive wear, deterioration, or damage from external loads such as shock or vibration.
For all of the reasons described above, keyboards sometimes need to be removed from a computer system and replaced or repaired. Some computer systems include a removable panel mount keyboard that is attached to a chassis of the computer systems with conventional fasteners, such as screws. Replacing a panel-mounted keyboard in many existing systems can be time consuming For example, in some panel-mount keyboard systems, the keyboard is attached by fasteners that are driven from behind the face of keyboard. To gain access to the keyboard fasteners, several system components (such as hard drives, batteries, or circuit boards) and/or chassis elements (such as back or bottom covers on a chassis or case) may need to be removed and then later replaced.
Computer systems may be susceptible to electromagnetic interference. Electromagnetic interference may be generated by many sources inside or outside of a computer system, through mechanisms such as radiation, induction, and conduction. In some cases, electromagnetic interference is introduced into a computer system at or through a keyboard. For example, in some keyboards, a circuit board carrying key switches for the keyboard has numerous long traces and fingers on the surface of the circuit board. These traces and fingers provide conductive paths to the various keys. Long traces and fingers may, however, provide a coupling path for electromagnetic radiation from components such as semiconductor devices, electric motors, and power supply components. Electromagnetic interference resulting from such coupling may cause the keyboard or other components of a computer system to malfunction.
Keyboard systems and methods of making and using keyboard systems are described herein. In one embodiment, a keyboard system, and associated methods of making and using, includes a keypad and a printed circuit board assembly. The keypad includes one or more keys and one or more keypad conductive elements for at least one of the keys. The printed circuit board assembly is coupled to the keypad. The printed circuit board assembly includes a printed circuit board having at least one switch contact area for each of one or more keys on the keypad. The printed circuit board also includes, for at least one of the keys of the keypad, one or more first side vias in a switch contact area and one or more second side vias in the switch contact area. The first side vias are electrically coupled on a first side of a switch for the key. The second side vias are electrically coupled on a second side of the switch for the key. In some embodiments, as switch included one or more vias for each side of the switch. In some embodiments, a switch includes two or more vias for each side of the switch. The switch for the key closes when at least one of the keypad conductive elements bridges at least one first side via in the switch contact area and at least one second side via in the contact area. The printed circuit board for the keyboard comprises for at least one key, one or more first side vias in a switch contact area and for the at least one key, one or more second vias in the switch contact area. In some embodiments, at least one of the first side vias is configurable to couple with a first side of a switch circuit for the key, wherein at least one of the second side vias is configurable to couple with a second side of a switch circuit for the key, wherein a switch in the switch circuit is configurable to close when at least one of the first side vias in the contact area is bridged with at least one of the second side vias in the contact area.
In an embodiment, a keyboard system for panel-mounting in a chassis of a computer system includes a keyboard assembly and a bezel. The keyboard assembly includes a keypad and a printed circuit board coupled to the keypad. The bezel is used to mount the keyboard assembly in the chassis. The bezel holds the fasteners such that the fasteners can be coupled with the chassis. The fasteners for the keyboard assembly may be driven from the front of the keyboard assembly into the chassis. In some embodiments, a keyboard assembly is electrically coupled to a chassis ground through a bezel and an electrically conductive gasket between the bezel and the chassis. In some embodiments, the keyboard system, and/or the computer system in which the keyboard system is installed, is configured to meet a radiated susceptibility test standard under MIL-STD-461E, RS103, at a field strength level of 200 volts/meter. In some embodiments, the keyboard system has a low profile.
In an embodiment, an improved method of protecting from electromagnetic interference in a keyboard system comprises providing a keypad comprising two one or more keys and one or more keypad conductive elements for at least one of the keys; providing a printed circuit board assembly coupled to the keypad. The printed circuit board assembly comprises a printed circuit board comprising at least one switch contact areas for each of two one or more keys on the keypad. For at least one of the keys of the keypad, one or more first side vias in a switch contact area are electrically coupled on a first side of a switch for the key, and one or more second side vias in the switch contact area are electrically coupled on a second side of the switch for the key. The switch for the key is configurable to close when at least one of the keypad conductive elements bridges at least one first side via in the switch contact area and at least one second side via in the switch contact area.
While the invention is described herein by way of example for several embodiments and illustrative drawings, those skilled in the art will recognize that the invention is not limited to the embodiments or drawings described. It should be understood, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include”, “including”, and “includes” mean including, but not limited to.
As used herein, “bridge” includes electrically connecting one element with another. For example, electrical contacts on either of two sides of a switch may be bridged to one another.
As used herein, “chassis” refers to a structure or element that supports another element, or to which other elements can be mounted. For example, a chassis may support circuit boards, a keyboard assembly, disk drives, and other components in a laptop computer system. A chassis may have any shape or construction, including a frame, a plate, a box, or a combination thereof.
As used herein, “circuit board” refers to any circuit module that carries one or more other circuit modules or components. “Circuit board” includes, but is not limited to, a printed circuit board made of epoxy-glass and metal layers.
As used herein, “circuit module” refers to any module that includes or carries elements of an electrical circuit, electrical components (including, but not limited to, semiconductor devices or resistors), or conductors (e.g., wires, traces).
As used herein, “conductive keypad element” includes any conductive element in or on a keypad. In one embodiment, a conductive keypad element is a carbon pill.
As used herein, a “switch contact area” means an area of a circuit board in which contact can be made between two or more elements to close a switch.
As used herein, “panel-mounted” or “panel-mounting” refers to a mounting of a keyboard or other device in an opening, socket, recess, or cavity in a panel or chassis. For example, a chassis or case of a notebook computer system may include a top panel having an opening for mounting a keyboard. As another example, a cabinet for an industrial control system may include a control panel having an opening for mounting a keyboard.
As used herein, “via” refers to a conductive element, such as a metalized or plated hole, that can be used to interconnect two or more layers or sides of a circuit board. As used herein, a “blind via” means a via that is exposed on only one side of a circuit board. In some cases, a via includes plating at the surface of a circuit board. In some embodiments, a via includes a surface pad or surface ring. The surface pad or ring may have a larger diameter than the hole for the via. For example, a via in a hole of diameter 0.010 inches may include an annular ring at the surface of the circuit board having an outer diameter of 0.038 inches.
In some embodiments, a computer system includes a panel-mounted keyboard.
Keyboard assembly 104 may be electrically coupled to motherboard assembly 106 by way of connector 115. In some embodiments, mating halves of connector 115 automatically couple when keyboard assembly 104 is installed in chassis 102. Keyboard assembly 104 may serve as a user input device for computer system 100.
Keyboard assembly 104 is mountable to chassis 102. Keyboard assembly 104 includes keypad 116, keyboard PCB 118, and bezel 120. Bezel 120 may couple to chassis 102 in bezel seat 124 of chassis 102. Gasket 122 is provided between bezel 120 and chassis 102. In some embodiments, gasket 122 is compressed between bezel 120 and chassis 102. Gasket 122 may provide a seal between bezel 120 and chassis 102. In certain embodiments, gasket 122 is made of an electrically conductive material. In some embodiments, keyboard assembly 104 is electrically coupled to a chassis ground of chassis 102 through bezel 120 and gasket 122. In certain embodiments, a chassis ground may be established with electrically conductive adhesives between elements of a system.
Keypad 116 couples with keyboard PCB 118. Keypad 116 and keyboard PCB 118 are mounted in bezel 120 in keyboard seat 126.
Keypad 116 includes keys 130 and keypad base 131. In some embodiments, keypad 116 is made of a sheet of elastomeric material, such as rubber. In certain embodiments, the sheet is continuous over the entire keyboard. A keypad including a continuous sheet of material may seal fluids, dust, contaminants, and other elements in the environment out of the computer system. In the embodiment shown in
Keyboard PCB 118 may include switches and conductors for receiving input when the various keys 130 of keypad 116 are pressed by a user. In some embodiments, keyboard PCB 118 may include light emitting diodes (“LEDs”). The LEDs may backlight keys 130 when the keys are pressed.
Keyboard assembly 104 includes pointer device 141. Pointer device 141 includes sensor 143 and arrow keys 145. Sensor 143 may sense user input. In one embodiment, sensor 143 has an “eraser head” type input. In certain embodiments, the keypad portions of pointer device 141 are similar in structure and arrangement similar to that described above with respect to keys 130.
In some embodiments, a keyboard is installed on a computer system from the front of the keyboard. In one embodiment, a keyboard is installed with fasteners driven from the front of the keyboard. As used herein, “front” means the face of a keyboard on which the keys are exposed and/or operated. For example, in the embodiment shown in
Bezel 120 includes holes 146. Each of holes 146 may be a through-hole that receives one of fasteners 144. Fasteners 144 may couple keyboard assembly 104 to chassis 102. In one embodiment, fasteners 144 are screws. In other embodiments, various other suitable fasteners may be used to secure a keyboard assembly to a computer system, such as cam-lock fasteners, pins, or clips. In certain embodiments, fasteners 144 are captive fasteners. Chassis 102 may include tapped holes for receiving fasteners.
In some embodiments, a keyboard system including a bezel-mounted keypad/keyboard PCB assembly, such as described above relative to
Keypad 116 is supported on keyboard PCB 118. Keypad base 131 may be directly above keyboard PCB 118. Raised pads 134 may be suspended on webs 136 above keyboard PCB 118. Keypad 116 includes keypad conductive elements 132. Keypad conductive elements 132 may be, for example, carbon “pills” or discs on the bottom of raised pads 134. Keypad conductive elements 132 may be electrically conductive. When one of keys 130 is pressed by a user, one or more of keypad conductive elements 132 on the key may contact switch elements on the surface of keyboard PCB 118 to close a switch for that key. The closing of the switch for the key may be used as a signal that the key has been pressed.
Keypad 116 and keyboard PCB 118 may mount in pocket 152 in bezel 120. Pocket 152 of bezel 120 includes seat 126. Keypad 116 includes ridge 156. Ridge 156 of keypad 116 may extend into groove 158 in seat 126 of bezel 120. As illustrated in
In some embodiments, a bezel includes one or more cross members. The cross members may provide support and/or structural reinforcement for a keyboard PCB. Referring again to
In some embodiments, a bezel may couple with conductive elements on a keyboard PCB, such as a ground plane.
As discussed above, keypad conductive elements on a key may contact switch elements on the surface of keyboard PCB to close a switch associated with a key. In some embodiments, each keypad conductive element on a keypad may correspond to a contact area on a PCB. The contact area corresponding to a keypad may have multiple PCB conductive elements. In embodiments, the PCB conductive elements are vias in the printed circuit board.
Key 130 is provided on keypad 116. Key 130 includes raised pad 134. Conductive keypad elements 132 are provided on bottom of raised pad 134. Under each of conductive keypad elements 132, a contact area 166 is provided on keyboard PCB 118.
In the embodiment illustrated in
Vias 168a may be electrically coupled on one another. Vias 168a may form one side of a switch for key 164. Vias 168b may be electrically coupled on one another. Vias 168b may form a second side of a switch for key 164. When key 164 is pressed by a user, one or more of conductive keypad elements may bridge at least one of vias 168a on the first side of the switch for the key to at least one of vias 168b on the second side of the switch.
As described above with respect to
In
For illustrative purposes, the key loading variations, key displacements, and combinations of vias that are bridged in
Via 168 includes barrel 212 and surface ring 214. In some embodiments, barrel 212 is a plated through hole. As illustrated in
In some embodiments, ground plane layer 204 is a dedicated chassis ground plane. In certain embodiments, a ground plane layer may partially extend under a portion of a conductive surface of one or more vias. For example, as illustrated in
The number of keypad conductive elements for each key may vary from embodiment to embodiment and, within any embodiment, from key to key. The number of contact areas on a circuit board for a particular key may also vary. In some embodiments, the number of conductive elements and contact areas for a key varies depending on the size of a key. Larger keys may have more keypad conductive elements, PCB contact areas, and vias, for example, than smaller keys. Keypad conductive elements may be distributed over the area of a raised pad for a key. In some embodiments, keypad conductive elements for a key are placed near the outside edges of a raised pad for the key. In some embodiments, keypad conductive elements for a key are placed near the corners of the raised pad for the key. Keypad conductive elements may be any shape, including round, ovate, square, rectangular, or irregular.
In some embodiments, each keypad conductive element for a key has a corresponding contact area on a keyboard. In certain embodiments, however, there need not be a one-to-one correspondence between keypad conductive elements and contact areas. For example, one keypad conductive element may cover one or more contact areas. Conversely, one or more keypad conductive elements may be provided over a single contact area. A keypad conductive element may be larger or smaller than a corresponding contact area. In certain embodiments, a key has only one keypad conductive element. In one embodiment, an entire raised pad of a key is electrically conductive. In one embodiment, an entire keypad is electrically conductive.
Vias 168 may be through vias, blind vias, or a combination thereof. In some embodiments, a keyboard PCB includes blind vias in portion of the PCB where the bottom layer of the board includes a ground plane (such as the ground plane around the bottom edge of keyboard PCB 118 shown in
As discussed above, the number of contact areas and vias associated with a particular key may vary depending on the size and function of the key. For some keys, the pattern of vias may be the same in all of the contact areas for the key. For other keys, different contact areas for the key may have a different pattern of vias than other contact areas.
Although in
In certain embodiments, the number of vias may be selected to control a sensitivity of a key. For example, as shown in
As discussed above, different vias within a contact area for a key may be coupled on one side or the other of a switch for the key.
The arrangement of vias 168a and vias 168b may be selected to increase the likelihood of closing a switch for a key when the key is pressed by a user. In some embodiments, a pattern of vias 168a and vias 168b is selected so that at least one of the vias is immediately adjacent to one or more vias on the other side of the switch. In some patterns, the vias on either side of the switch may be alternated over at least a portion of the pattern. In certain embodiments, a contact area for a key includes an equal number of vias on each side of the switch. In certain embodiments, a contact area for a key includes one or more vias for each side of the switch. In certain embodiments, the arrangement of vias of the two sides of a key switch within a contact area are arranged to achieve a desired sensitivity range for a key.
In one embodiment, vias 168a and 168b have a hole diameter of about 0.010 inches. Surface ring 214 may be circular and have an outer diameter of about 0.038 inches. Surface ring 214 may be an exposed ground. The spacing between horizontal and vertical centers of the vias for each row or column may be about 0.042 inches. In some embodiments, a 0.030 inch minimum spacing is maintained between vias 168a and 168b and a keep away zone, such as keep away zone 228 described above relative to
In some embodiments, a keyboard PCB having multiple vias for key switch elements may eliminate a need for long traces on the surface of a keyboard PCB for the switch. Eliminating traces in a keyboard PCB may reduce susceptibility of the keyboard PCB and/or the computer system to electromagnetic interference. In some embodiments, a system with keyboard including key switch vias meets a radiated susceptibility test standard under MIL-STD-461E, RS103, at a field strength level of 200 volts/meter.
Vias for a key switch, such as vias 168a and vias 168b shown in
Although in the embodiments described above, all of the vias are on one side or the other of a single switch for the key, in some embodiments, may be grouped or paired into one or more switches for a key. For example, a given key or contact area may include sets of vias 168a, vias 168b, vias 168c, and 168d. Vias 168a and vias 168b may form opposing sides of one switch, while vias 168c and 168d form opposing sides of a second switch. In certain embodiments, individual vias in a contact area may be paired to form a switch.
Switch circuit 250 includes capacitors 262a and 262b. Capacitors 262a are between line 258a (which may correspond to a row side of switch 252) and ground. In one embodiment, capacitors 262a and 262b are 0.01 microfarads. Capacitors 262b are between line 258b (which may correspond to a column side of switch 252) and ground. In some embodiments, capacitors 262a and 262b are located on the corners of a key area. For example, referring to
In some embodiments, a panel-mount keyboard assembly includes keyboard PCB and keypad stacked on a bezel. The bezel may couple with a panel in the chassis of a computer system.
As is illustrated in
Further modifications and alternative embodiments of various aspects of the invention may be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Methods may be implemented manually, in software, in hardware, or a combination thereof. The order of any method may be changed, and various elements may be added, reordered, combined, omitted, modified, etc. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.
This application claims benefit of U.S. Provisional Application No. 61/330,110 filed on Apr. 30, 2010.
| Number | Date | Country | |
|---|---|---|---|
| 61330110 | Apr 2010 | US |
