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:
Sep. 06, 1988
Filed:
Apr. 02, 1987
Applicant:
Inventor:
Toshiharu Aihara, Tokyo, JP;
Assignee:
Casio Computer Co., Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
379361 ; 379418 ;
Abstract
A dialing tone generator employs a low-frequency oscillator as a reference signal oscillator. The reference signal is frequency-divided into first and second frequency-divided signals. The first frequency-divided signal is used to produce a low-frequency tone signal, whereas the second frequency-divided signal is used to produce a high-frequency tone signal. These tone signals are rectangular waveforms. The rectangular waveforms are filtered in corresponding low-pass filters to output first and second sine-wave signals. Then, these sine-wave signals are synthesized with each other to produce a desired dialing tone.