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:
Mar. 17, 1992
Filed:
Jan. 23, 1991
Michihiro Shoji, Tokyo, JP;
Nitto Kohki Co., Ltd., Tokyo, JP;
Abstract
A drill apparatus with an electromagnet base, which has an electric drill directed downwards, is provided with an electromagnet base having an electromagnet for attaching the apparatus to a to-be-worked object by magnetic force. The electric drill is rotated by a drill motor and moved by a feed motor towards the object. A Hall element is situated on the electromagnet base. Two comparators detects whether or not a Hall voltage output from the Hall element falls in a predetermined range of voltage values. When the Hall voltage does not fall in this range, a transistor is turned on. Consequently, a relay is operated, a contact is opened, and power supply to the drill motor and the feed motor is stopped.