Of many techniques developed for entering data into computers, calculators and other, similar devices, one of the most common is through the use of a keyboard. In the most general sense, a keyboard is a data entry device in communication with a parent data storage or processing apparatus which comprises a plurality of key type switches, each assigned a distinct and independent value. When depressed, each key switch has its distinct, independent value entered into the parent apparatus. When released, the key resets, returning to its normal position.
Keyboard mechanisms vary greatly, with two of the most common types being the Capacitance or Serial type in which polyurethane foam pads press against aluminum foil interleaves to complete a circuit, and the Plunger or Hall Effect type in which a small electrical current is produced by moving a magnet through a coil, the origin of this current indicating to the parent device which key has been depressed.
Among the most common materials employed for plunger-type keyboard structures are ABS (acrylonitrile butadiene styrene) and modified phenylene oxide plastics. These are used not only in the case and key cap assemblies, but additionally in the housings and actuators for the key switches. The key mechanism also includes a spring assembly to provide upward pressure on the key switch, thereby allowing it to return to its resting position once depressed. Due to the minimal space available for each key switch; the housing, actuator and spring assembly must operate within very close tolerances.
Keyboards used in both work and home environments are subject to various contaminants ranging from dust and smoke particles to residue from spilled coffee and soft-drinks. Consequently, a periodic refurbishment and cleaning of the keyboard is often necessary. Additionally, residue left by the manufacturing process may make it desirable to clean the keyboard prior to packaging.
Due to the complicated surface geometry, the solvent sensitive plastic materials used in keyboard actuators and housings and the fragile nature of the keyboard, cleaning has proven to be an arduous and time consuming task. Currently, keyboards are cleaned by removing them from their protective covers, spraying on a mild detergent solution, scrubbing them with toothbrushes and similar tools, and then wiping them off. There are no rinse operations or other techniques employed to remove the resulting detergent film. Consequently, the film remains in the voids and hollows inside each key and causes problems such as sticking keys, poor electrical contact, etc. Furthermore, as the problem may not be immediately apparent or detectable by routine testing, a service call is often necessary when a cleaning induced failure occurs once the keyboard has been sent out into the field.
While it would seem desirable to find other methods of keyboard cleaning, none previously have been found that are both effective and harmless. Various chemical baths have been used to clean printed circuit boards and other components, however, keyboard manufacturers have recommended against using these techniques due to the undesirable effects of the currently-used harsh chemicals on the solvent-sensitive keyboard plastics. As a result, slow and problem-causing scrubbing continues to be used.
USPTO Backgrounds
USPTO Backgrounds