The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 01, 1990
Filed:
Jun. 08, 1989
Rikagaku Kenkyusho, Saitama, JP;
Abstract
An apparatus for detecting contamination on probe surface which comprises a sweep voltage generator for generating sweep voltage which is applied to a probe or probes in plasma, a probe current detection circuit for detecting probe current which flows in accordance with the sweep voltage applied, an amplitude discriminator for comparing the probe current with a predetermined threshold and generating an output signal when the probe current becomes equal to the predetermined threshold, a first sample-hold circuit for sampling and holding the sweep voltage upon reception of the output signal from the amplitude discriminator while the sweep voltage is increasing, a second sample-hold circuit for sampling and holding the sweep voltage upon reception of the output signal from the amplitude discriminator while the sweep voltage is decreasing, and a subtracter for providing a difference between the sweep voltages holded in the first and second sample-hold circuit. Degree of the contamination on the probe surface can be evaluated from the difference.