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US 5,309,132 AGranted
Technique for trimming photoresistors and trimmed photoresistors
AssigneeCompaq Computer Corporation
InventorsNathan A. Mitchell, Philip J. McKenzie
Life of this patent
Estimating the term…
Abstract
A technique for trimming photoresistors to change relatively high tolerance parts to relatively low tolerance parts by blocking out a portion of the photoactive area, and the so-trimmed photoresistors. The blocking out can be performed by placing ink over the photo-active area. This ink placement step can be easily added in the photoresistor assembly line after the initial calibration location.
Claims14
A technique for trimming photoresistors comprising:
- determining a target resistance by exposing a plurality of photoresistors to a calibrated level and color temperature of light;
- and
- blocking out a portion of a photo-active area of each of a plurality of photoresistors so that each trimmed photoresistor has a measured resistance within a predetermined tolerance of the target resistance when exposed to the calibrated level and color temperature of light, the predetermined tolerance being less than an untrimmed parts tolerance.
Trimmed photoresistors comprising:
- a plurality of photoresistors, each photoresistor having a portion of its photo-active area blocked out such that each photoresistor measures a resistance within a predetermined tolerance of a target resistance when each photoresistor is exposed to a calibrated level and color temperature of light, the predetermined tolerance being less than an untrimmed parts tolerance.
Dependencies are inferred from the claim text.