Optical pseudo trackball controls the operation of an appliance or machine

Most appliances and machines have controls by which the appliance is operated by a user. The usual case, and especially so before the advent of microprocessor control, was for some mechanically moveable element, such a pivoted lever or journaled shaft, to be moved by the operator. Something (e.g., a valve or a brake pad) connected to the mechanically moveable element directly affected the operation of the appliance. Even in the case of electrical and electronic appliances, the contacts of switches, wipers of potentiometers, rotors of capacitors and slugs of inductors were moved by the power of the human hand (or perhaps a foot). We have nothing against hands (or feet), and merely wish to point out that, even including power amplification servo systems, the movement of the hand operated control was accompanied by a corresponding alteration in the condition of some circuit, which is to say, a fundamental shift in value of some circuit component was produced by the mechanical motion. Consider, for example, an older radio for the consumer market. If one wanted to increase the volume, she rotated the shaft of a pot used as a variable ratio voltage divider in an audio amplifier circuit. Likewise, to change the station the value of a reactive component was directly altered by mechanical motion provided by the user. An optical fingertip tracker, which may be a pseudo trackball, responds to the motion of the texture on one of the user's digits pressed against an image input aperture to produce motion signals processed within an appliance to be controlled. The appliance may have a minimal GUI, such as an LCD display having only a modest number of low resolution pixel locations and/or preestablished characters or icons. An appliance control parameter is set or adjusted in response to translation of the fingertip along a particular axis. E.g., to enter a parameter value (volume) a changing bar graph can be displayed. The display might even be omitted; to set the tone control of an audio appliance it can be sufficient to simply adjust the tone until the result is as desired. A numeric display of control parameter digits may be desirable, as when moving the fingertip tunes a receiver. There can be several particular axes along which fingertip movement changes an associated appliance control parameter. Other appliances can include character recognition of input characters traced by the fingertip. A pressure sensitive switch coupled to the fingertip tracker can serve as a