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.

Date of Patent:
May. 21, 2013

Filed:

Jun. 11, 2010
Applicants:

Hiroyuki Takahashi, Tokyo, JP;

Yoshiyuki Usuki, Ibaraki, JP;

Kei Kamada, Ibaraki, JP;

Inventors:

Hiroyuki Takahashi, Tokyo, JP;

Yoshiyuki Usuki, Ibaraki, JP;

Kei Kamada, Ibaraki, JP;

Assignees:
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G01T 1/20 (2006.01);
U.S. Cl.
CPC ...
Abstract

An electric signal produced by a photo-electric conversion element () is input to a comparator (). The comparator () judges whether the electric signal output from the amplifier () exceeds a reference voltage or not, and outputs a HIGH signal if 'exceeds'. A reference voltage modifier unit () elevates the reference voltage, after a predetermined time period elapses since the comparator () judged that the electric signal reached or exceeded the reference voltage. The signal processor calculates an incidence time which represents a time when the signal light starts to enter the photo-electric converter unit (), by correcting a rise-up time of the electric signal when it reaches or exceeds the reference voltage, based on a pulse width which represents a time period from when the electric signal exceeds the reference voltage, up to when the electric signal falls below the reference voltage.


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