Title:
VIDEO DOORPHONE SYSTEM
Document Type and Number:
Japanese Patent JP3497003
Kind Code:
B2
Abstract:
PURPOSE: To loudly speak a slave unit side voice on the side of a master unit by activating a loud speaker circuit by superimposing a calling button operate signal on the blanking part of a video signal and detecting that signal on the side of the monitor base unit by continuously pushing a calling button when transmitting the picture of a video doorphone.
CONSTITUTION: At a camera slave unit 1, a blanking superimposing circuit 5 is provided between a calling circuit 3 and a camera unit 6 and while a calling button 4 is continuously pushed, the blanking part of the video signal is dropped to O[V]. At a monitor master unit 2 connected with the slave unit 1 through two wires, that signal is detected by a blanking detection circuit 16 and converted to a pulse signal. The number of those pulse signals is counted by a loud speaking activating circuit 25 and after the lapse of fixed time, the speech path of a speaking circuit 18 is opened. Then, the gain of an amplifier 19 is increased and the voice of a visitor is outputted from a speaker 20 with a high output.
Inventors:
Ishizuka
Application Number:
JP7887695A
Publication Date:
February 16, 2004
Filing Date:
April 04, 1995
Export Citation:
Assignee:
Matsushita Electric Industrial Co., Ltd
International Classes:
H04N7/18; H04M9/00; (IPC1-7): H04N7/18; H04M9/00
Domestic Patent References:
| JP766881A | ||||
| JP5284240A | ||||
| JP3117954A | ||||
| JP6141324A |
Attorney, Agent or Firm:
Teruo Aoki