Electric lamp and discharge devices: systems – With automatic shunt and/or cutout
Reexamination Certificate
2000-07-28
2001-10-16
Vu, David (Department: 2821)
Electric lamp and discharge devices: systems
With automatic shunt and/or cutout
C417S044100, C392S361000, C318S016000
Reexamination Certificate
active
06304037
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a light control for use with a ceiling fan and lamp assembly to control the light intensity of the lamp of the ceiling fan and lamp assembly, and more particularly to such a light control, which has protection circuit means that automatically cut off power supply from the lamp upon an overload or short-circuit.
Varieties of ceiling fan and lamp assemblies have been disclosed, and have appeared on the market. A ceiling fan and lamp assembly is generally equipped with a light control for controlling the light intensity of the lamp.
FIG. 1
shows a prior art light control for this purpose. This structure of light control
10
comprises a TRIAC
11
, a transistor
12
, and a CPU (central processing unit)
20
. The transistor
12
is connected between the CPU
20
and the gate of the TRIAC
11
. The other two terminals of the TRIAC
11
are respectively connected to the lamp
30
and the hot wire for controlling the phase of the lamp
30
. When an input pulse width Tr is connected to the TRIAC
11
, the gate current is produced at the gate of the TRIAC
11
, causing the TRIAC
11
to change its connected phase angle, so as to further switch on/off the lamp
30
, or regulate the light intensity of the lamp
30
. This design is functional, however the TRIAC
11
may be damaged or caused to burn when an overload or short-circuit occurs.
SUMMARY OF THE INVENTION
The invention has been accomplished to provide a light control, which eliminates the aforesaid problem. It is therefore the main object of the present invention to provide a light control for a ceiling fan and lamp assembly, which automatically cuts off power supply from the lamp of the ceiling fan and lamp assembly upon an overload or short-circuit. According to the present invention, the light control comprises a CPU (central processing unit having an input contact and an output contact, a TRIAC, a transistor, an amplifier, and a comparator. The TRIAC has a gate connected to the output contact of the CPU through the transistor, a second terminal connected to the lamp means of the ceiling fan and lamp assembly, and a third terminal connected to the amplifier. The amplifier has an output terminal connected to the comparator. The comparator has a feedback circuit outputted to the input contact of the CPU. When an overload or short-circuit occurs, a potential difference is obtained and compared with the rated value, and the comparison result is fed back to the CPU, causing the CPU to cut off power supply from the TRIAC.
REFERENCES:
patent: 4818920 (1989-04-01), Jacob
patent: 5668920 (1997-09-01), Pelonis
patent: 5738496 (1998-04-01), Mehta
Lee Wilson
Pro-Techtor Inter-national Services
Vu David
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