Communications: electrical – Visual indication
Utility Patent
1999-09-30
2001-01-02
Lieu, Julie (Department: 2736)
Communications: electrical
Visual indication
C340S635000
Utility Patent
active
06169491
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a multi-port power monitor for indicating whether power is being provided to one or more ports through which power is provided to external devices connected to the ports. More particularly, the present invention is directed to a power monitor comprising a plurality of controllable switches for providing power to one or more of a plurality of indicators when power is provided to one or more of a plurality of ports.
BACKGROUND OF THE INVENTION
Multi-port units are used in machine controls to provide power to controllable devices on an assembly line. In particular, a controller transmits a control signal to provide power through a power port to an external controllable device. Typically, a monitor circuit is connected in parallel with the power port in order to indicate whether power is being properly supplied to the power port to which the external device is connected. As shown in
FIG. 1
, a conventional monitor circuit
10
for indicating whether power is being provided through a power port (not shown) to an external device (not shown) comprises a light emitting diode (LED)
1
, a diode
2
, an alternating current (AC) power source
3
, a capacitor
4
and a resistor
5
. However, the capacitor occupies a large amount of valuable space. Further, in the case of multiple ports, a separate monitor circuit is required for each port with the respective LEDs indicating the power supply status for each port connected in parallel. As a result, a large aggregate current is required in order to simultaneously illuminate the LEDs. For example, in the case of eight ports with eight corresponding monitor circuits, resulting a total of eight LEDs each requiring 5 mA for illumination, a total current of 40 mA is required to simultaneously illuminate an eight LEDs.
Accordingly, it is an object of the present invention to provide a multi-port monitor with reduced power and space requirements.
SUMMARY OF THE INVENTION
According to the present invention, a multi-port power monitor is provided which indicates whether power is being supplied to one or more of a plurality of ports connected to external devices. The multi-port power monitor comprises a plurality of serially connected indicators and a plurality of controllable switches which supply power to the individual indicators when one or more of the corresponding ports are active. Because the indicators are connected in series, rather than in parallel, the same current passes through each illuminated indicator thereby avoiding the need for a large power resistor or a large AC capacitor for each individual port.
REFERENCES:
patent: 4194181 (1980-03-01), Brundage
patent: 4354182 (1982-10-01), Frey
patent: 5109200 (1992-04-01), Dushane et al.
Brad Harrison, Designer's Guide, pp. 86 and 130.
NEC, High Isolation Voltage AC Input, Darlington Transitor Type Multi Photocoupler Series, pp. 1-42 and 1-43.
Application of AC Input Compatible Photocoupler, pp. 5-33 and 5-34.
'Hubbell Incorporated
Goodman Alfred N.
Holmes John E.
Lieu Julie
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