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:
Oct. 24, 2000
Filed:
Jun. 30, 1995
Mamoru Nakanishi, Yokkaichi, JP;
Morihiko Toyozumi, Yokkaichi, JP;
Abstract
To prevent an erroneous operation of a buzzer upon fall of a source voltage, a buzzer driving device connectable with a direct current source (1) comprises a charging/discharging circuit (3) which is connected with the direct-current source (1) via a switch (2) and performs the charging and discharging at a predetermined time constant (CR) when the switch (2) is turned on and off, respectively, a hysteresis circuit (25) to which an output voltage of the charging/discharging circuit (3) is input and which operates until the output voltage rises to or above an operation threshold value (V.sub.T) after the start of the charging of the charging/discharging circuit (3) and thereafter remains inoperative unless the output voltage falls to or below a stop threshold value (V.sub.S) which is smaller than the operation threshold value (V.sub.T) due to the discharging of the charging/discharging circuit (3), and a driving circuit (14) for outputting a drive signal for a buzzer (15) in response to the operation of the hysteresis circuit (25).