Title:
VISUAL DOORPHONE DEVICE
Document Type and Number:
Japanese Patent JPH0530513
Kind Code:
A
Abstract:
PURPOSE: To obtain a visual doorphone device capable of preventing power supply voltage for driving a television(TV) camera from being dropped even when a communication cable is extended.
CONSTITUTION: An AC signal from an AC signal generating circuit in a doorphone master set 101 is outputted to a transformer 115 in a doorphone slave set 102 through a mixer 104, an amplifier circuit 107, a transformer 108, and a communication cable L. An output signal from the transformer 115 is rectified by a rectifying diode bridge circuit 116, smoothed by a filter circuit 117 and then supplied to the TV camera 120 as AC power supply.
Inventors:
NAGAYAMA MUNEHITO
IMAI YUKIO
IMAI YUKIO
Application Number:
JP18263791A
Publication Date:
February 05, 1993
Filing Date:
July 23, 1991
Export Citation:
Assignee:
AIPHONE CO LTD
International Classes:
H04M9/00; H04N7/18; (IPC1-7): H04M9/00; H04N7/18
Domestic Patent References:
| JPH01311668A | 1989-12-15 |
Attorney, Agent or Firm:
Moriya Kazuo
Next Patent: JPH0530514