Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
2005-04-05
2005-04-05
Luu, Thanh X. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C340S407100, C398S140000, C341S031000
Reexamination Certificate
active
06875977
ABSTRACT:
An optoelectronic keypad and a method for controlling an optoelectronic keypad for a measuring instrument, require a transparent touch screen, at least two touch-sensitive control buttons, at least two light emitters and at least two photodetectors, where said control buttons are located next to each other on one side of the surface of the touch-screen, the light emitters and the photodetectors are situated next to each other on the other side of the touch screen and each one control button, light emitter and photodetector are functionally associated with one another in a way as to constitute one action key, whereby pressing the control button of an action key causes the light emanating from the light emitter of that action key to be reflected at the actuated key and to impinge on the photodetector of that key. A central control and processing unit is also provided, the light emitters being connected to said central control and processing unit and the light emitters being time-controlled by the central control and processing unit in such fashion that at any one time only one of the juxtaposed light emitters is in the active state. This substantially reduces the risk of a detection error relative to the actuation of a key.
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European Search Report, Oct. 22, 2004.
Ludwig Detlef
Stelz Wolfgang
Wolter Jurgen
Cesari and McKenna LLP
Krohne Messtechnik GmbH & Co. KG
McKenna John F.
Yam Stephen
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