Lighting system

Details Lighting system Lighting system

2001-12-28

2003-06-10

Wong, Don (Department: 2821)

Electric lamp and discharge devices: systems

Pulsating or a.c. supply

Induction-type discharge device load

C315S039000

Reexamination Certificate

active

06577074

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to electrodeless lighting systems and more particularly, to electrodeless lighting system utilizing rotating bulbs.
2. Description of the Prior Art
The use of electrodeless bulbs which are excited by radio frequency (RF) sources for curing applications is well known. In many electrodeless bulb curing systems, a motor is utilized to rotate the bulb during excitation by the RF energy for various well-known advantages.
FIG. 1
illustrates a prior art system of the type in which the Assignee's ultraviolet (UV) electrodeless bulbs are utilized. The system
10
includes an irradiator
12
which is comprised of a bulb
60
and a magnetron
70
from which microwaves are coupled through waveguide
80
. The irradiator outputs UV light
14
inside of a customer supplied light shield
16
through which customer product flows on a conveyor system
18
as indicated by the directional arrow. The curved arrows indicate cooling air flow from blower
20
. The RF detector
26
detects when unacceptably high RF leakage is present and when unacceptable high leakage is detected, the system is shut down by the RF detector. The magnetron
70
contained within the irradiator
12
may be air cooled as illustrated by a source of air from blower
20
, which is blown into the irradiator through line
22
. The air from the blower
20
serves to cool both the rotating bulb
60
and the magnetron
70
. Alternatively, the magnetron
70
may be water cooled. The magnetron
70
contains an electrical filament heater which, when energized with an AC potential, such as 3.4 or 4.1 volts, produces a source of electrons which, upon the application of high voltage, such as 4 KV, causes electrical oscillation to produce high frequency RF energy, such as, for example, of 2450 MHz. which is coupled to rotating bulb
60
which is rotated by motor
50
.
A power supply
32
provides electrical power to the blower
20
and to the control circuit
24
. The power supply also produces the aforementioned high voltage for the magnetron. The control circuit
24
functions to produce a regulated output for powering a filament heater transformer (not illustrated). The filament transformer steps down the voltage to a lower potential that is appropriate for the magnetron filament heater. The control circuit
24
may apply at least two electrical potentials or a continuously variable voltage to the filament heater. The variation of the voltage applied by the control circuit
24
to the filament heater of the magnetron
60
is chosen dependent upon the power level of the RF energy being outputted by the magnetron
70
and further, whether or not the magnetron is being operated. The applied potential to the filament heater typically is higher when it is preheated when the magnetron is not operating than when the magnetron is operating. A typical voltage applied to the filament heater during non-operation of the magnetron is 4.1 volts and a typical voltage applied to the filament heater during operation is 3.4 volts. The filament heater voltage is produced by the aforementioned step down transformer which is powered from single phase alternating current provided by single phase power source
34
which is represented by electrical power produced by the electrical power mains. Additionally, a customer interface
36
provides on/off control for the power supply
32
and therefore, the operation of the overall lighting system.
As illustrated, the motor
50
within the irradiator
12
which rotates the electrodeless bulb
60
therein, is powered by a separate power source and cable (not illustrated). The separate power source does not have voltage regulation. The electrical cable
40
between the control circuit
24
and the irradiator
12
has a standard number of conductors to enable it to be used with different model numbers of the Assignee's UV light products. It is further desirable to reduce the number of electrical wires in the electrical cable
40
to as small of a number as possible. The cable
40
does not contain an electrical conductor for providing for electrical power therein for driving the bulb rotation motor
50
.
Applications for UV lighting systems, as described in
FIG. 1
, are required to accept input voltages from the single phase power source
34
varying between 180 volts and 264 volts with frequencies of both 50 and 60 Hz. The overall design of powering a magnetron
70
and bulb rotation motor
50
in these applications can be expensive and difficult with it being necessary for the control circuit
24
to provide the aforementioned characteristics.
The life of the bulb rotation motor
50
is dependent upon operation within a narrow voltage range and further being energized for as little time as possible with the minimum time being during only operation of the electrodeless bulb
60
.
SUMMARY OF THE INVENTION
The present invention solves the problems of the prior art of
FIG. 1
by electrically powering the bulb rotation motor for rotating an electrodeless bulb and the heater for the RF source for exciting the electrodeless bulb, such as in a magnetron, in parallel under the control of a control circuit. With the invention, the single phase power is applied to the control circuit which provides regulated output voltage to the heater and the bulb rotation motor. The application of regulated voltage to the filament heater and the motor insures that proper electrical potential is applied to the heater to insure controlled operation of the RF energy source in accordance with the prior art and further, a controlled voltage to the bulb rotation motor which insures long life thereof and further permits a limited number of electrical conductors to be used to connect the control circuit to the irradiator which contains the electrodeless bulb and the motor for rotating the bulb.
In accordance with one embodiment of the invention, the motor for rotating the bulb, a transformer for stepping down the voltage applied to the heater, the control circuit for controlling the application of voltage to the heater and motor, and the RF energy source in the form of a magnetron are selected to be compatible. For example, without limitation, a 5 watt, 120 Volt AC synchronous motor may be chosen to provide a fixed rotational velocity for the electrodeless bulb dependent upon the frequency of the electrical power. The motor draws minimal current, both from an operating and starting standpoint, which does not disrupt the operation of the control circuit. The motor is designed to operate at a constant rotational velocity over a wide range of voltage inputted from the electrical power supply.
The step-down transformer reduces the voltage applied to the heater and may have a primary winding with an input voltage in a voltage range which is within the operating range for the AC motor. The secondary of the step-down transformer may be designed to provide 3.4 volts for heating a magnetron filament such as a 1,000 watt magnetron. During standby operation, the filament heater may be designed to operate at a slightly higher potential, such as 4.1 volts as a result of there being no heat generated by operation of the magnetron. The control circuit adjusts the phase angle firing point of a triac to control the AC voltage to the transformer primary and the motor to a fixed potential such as 120 volts.
The control circuit senses the input voltage and adjusts the phase angle firing point of the triac to maintain the AC voltage to the motor and transformer substantially constant depending on the electrodeless bulb operating mode. For example, a substantially constant output is produced by the control circuit, may be plus or minus 1% of a nominal rated output voltage even though the input voltage from the power mains is possible to vary with a substantially higher voltage range greater than plus or minus 1%.
Additionally, a photosensitive switch may be connected in series with the bulb rotating motor which disconnects the electrical power produced by the control circuit from

Affiliated with

Also associated with

Rating

Lighting system does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Lighting system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lighting system will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3103387