Information
-
Patent Grant
-
6489729
-
Patent Number
6,489,729
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Date Filed
Monday, June 11, 200123 years ago
-
Date Issued
Tuesday, December 3, 200221 years ago
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Inventors
-
Original Assignees
-
Examiners
-
CPC
-
US Classifications
Field of Search
US
- 315 209 R
- 315 291
- 315 307
- 315 224
- 315 194
- 315 88
- 315 91
- 315 92
- 362 20
- 362 11
- 362 13
- 314 1
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International Classifications
-
Abstract
An auxiliary lighting system for a high-intensity discharge lamp. In one embodiment, the auxiliary lighting system has an auxiliary light source, an HID lamp status circuit having an input for connection to a status signal representative of the operational state of a high-intensity discharge lamp wherein the HID lamp status circuit determines whether the status signal meets predetermined signal criteria, a switch circuit having a first state that effects application of a voltage source to the auxiliary light source, and a second state that isolates the voltage source from the auxiliary light source, and a control circuit responsive to the HID lamp status circuit for controlling the switch circuit. The control circuit has a first state when the HID lamp status circuit determines that the status signal meets the predetermined signal criteria and a second state when the HID lamp status circuit determines that the status signal does not meet the predetermined signal criteria. When the control circuit is in the first state, the control circuit outputs a control signal for input into the switch circuit that configures the switch circuit into the first state. When the control circuit is in the second state, the control circuit outputs a control signal for input into the switch circuit that configures the switch circuit into the second state.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to an electronic auxiliary lighting system for a high intensity discharge lamp.
2. Description of Related Art
Generally, high-intensity discharge (“HID”) lamps will extinguish when power to the HID lamp is interrupted. Power interruptions of even a very short duration, e.g. milliseconds, will often extinguish the HID lamp. As is well known in the art, generally, an extinguished HID lamp will not immediately re-ignite upon the restoration of power to the HID lamp because gases within the HID lamp must be cooled before the HID lamp will re-ignite. Furthermore, when the HID lamp is re-ignited, its lumen output is usually only a fraction of the normal lumen output and gradually increases until the HID lamp is at full brightness. Typically, it may take several minutes after restoration of power to the HID lamp before the HID lamp actually attains full brightness. Accordingly, auxiliary lighting control circuitry has been used for automatically lighting an auxiliary light source, such as an incandescent lamp, following a brief power interruption of an HID lamp.
Many standard magnetic HID ballasts provide an auxiliary tap to power an auxiliary light source if the HID lamp extinguishes. The auxiliary light source is controlled by the auxiliary lighting control circuitry that is external to the ballast. Typically, the primary winding of a current transformer is connected in series with the HID lamp. The auxiliary lighting control circuitry senses the ON/OFF condition of the HID lamp by sensing the HID lamp current available at the auxiliary tap. During normal operation of such an auxiliary lighting system, the HID lamp is ON (i.e. energized) and the auxiliary light source is OFF (i.e. de-energized). However, such external auxiliary lighting control circuitry increases the per-unit cost of the HID ballast system. Furthermore, external circuitry may cause additional problems pertaining to packaging and limited available space.
What is needed is an auxiliary lamp system that does not require an auxiliary tap or external circuitry.
SUMMARY OF THE INVENTION
The present invention is directed to, in one aspect, an auxiliary lighting system for a HID lamp, comprising an auxiliary light source, a switch circuit for controlling the application of a voltage source to the auxiliary light source, the switch circuit having a first state that effects application of the voltage source to the auxiliary light source, and a second state that isolates the voltage source from the auxiliary light source, and a control circuit having an input for receiving and being responsive to a signal that indicates the operational state of a HID lamp, the control circuit controlling the duration of time in which the switch circuit is configured in the first state and in the second state wherein the duration of time depends upon the operational state of the HID lamp.
In a related aspect, the present invention is directed to a method of operating an auxiliary lighting system for use with a HID lamp, comprising the steps of providing an auxiliary lighting system comprising an auxiliary light source, and a switch circuit having a first state for effecting application of a voltage source to the auxiliary light source and a second state for isolating the voltage source from the auxiliary light source, providing a status signal that indicates the state of energization of a HID lamp, and controlling the duration of time in which the switch circuit is configured in the first state and the second state wherein the duration of time depends upon the state of energization of the HID lamp.
In another aspect, the present invention is directed to an auxiliary lighting system for a high-intensity discharge lamp. The auxiliary lighting system has an auxiliary light source, an HID lamp status circuit having an input for connection to a status signal representative of the operational state of a high-intensity discharge lamp wherein the HID lamp status circuit determines whether the status signal meets predetermined signal criteria, a switch circuit for controlling the application of a voltage source to the auxiliary light source wherein the switch circuit has a first state that effects application of the voltage source to the auxiliary light source, and a second state that isolates the voltage source from the auxiliary light source, and a control circuit responsive to the HID lamp status circuit for controlling the switch circuit. The control circuit has a first state when the HID lamp status circuit determines that the status signal meets the predetermined signal criteria and a second state when the HID lamp status circuit determines that the status signal does not meet the predetermined signal criteria. When the control circuit is in the first state, the control circuit outputs a control signal for input into the switch circuit that configures the switch circuit into the first state. When the control circuit is in the second state, the control circuit outputs a control signal for input into the switch circuit that configures the switch circuit into the second state.
In a related aspect, the present invention is directed a ballast system, comprising a high-intensity discharge lamp, power feedback circuitry that provides a status signal that represents the state of energization of the high-intensity discharge lamp, an auxiliary light source, a voltage source for energizing the high-intensity discharge lamp and the auxiliary light source, a HID lamp status circuit having an input for receiving the status signal and determining whether the status signal meets the predetermined signal criteria, a switch circuit for controlling the application of the voltage source to the auxiliary light source wherein the switch circuit has a first state that effects application of the voltage source to the auxiliary light source, and a second state that isolates the voltage source from the auxiliary light source, and a control circuit responsive to the HID lamp status circuit for controlling the switch circuit. The control circuit has a first state when the HID lamp status circuit determines that the status signal meets the predetermined signal criteria and a second state when the HID lamp status circuit determines that the status signal does not meet the predetermined signal criteria. When the control voltage is in the first state, the control circuit outputs a control signal for input into the switch circuit that configures the switch circuit into the first state. When the control circuit is in the second state, the control circuit outputs a control signal for input into the switch circuit that configures the switch circuit into the second state.
In a further aspect, the present invention is directed to a method of operating an auxiliary lighting system for a high-intensity discharge lamp, comprising the steps of providing an auxiliary lighting system comprising an auxiliary light source, a HID lamp status circuit, and a switch circuit for controlling the application of a voltage source to the auxiliary light source, inputting into the HID lamp status circuit a status signal representative of the operational state of a high intensity discharge lamp, determining whether the status signal meets predetermined signal criteria, and controlling the switch circuit to apply a voltage source to the auxiliary light source if the status signal meets the predetermined signal criteria.
In yet a further aspect, the present invention is directed to a method of operating a ballast system comprising the steps of providing a ballast system comprising a high intensity discharge lamp, a voltage source for powering the high-intensity discharge lamp, circuitry for controlling the application of power to the high-intensity discharge lamp and providing a status signal that represents the operational state of the high-intensity discharge lamp, an auxiliary lighting system having an auxiliary light source, an HID lamp status circuit for determining whether the status signal meets predetermined signal criteria, a switch circuit for controlling the application of the voltage source to the auxiliary light source, and a control circuit for controlling the switch circuit. The method further comprises the steps of determining whether the status signal meets the predetermined signal criteria, controlling the switch circuit to apply the voltage source to the auxiliary light source if the status signal meets the predetermined signal criteria, and controlling the switch circuit to isolate the voltage source to the auxiliary light source if the status signal does not meet predetermined signal criteria.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the invention are believed to be novel and the elements characteristic of the invention are set forth with particularity in the appended claims. The invention itself, both as to organization and method of operation, may best be understood by reference to the detailed description which follows taken in conjunction with the accompanying drawings in which:
FIG. 1
is a block diagram of the auxiliary lighting system of the present invention; and
FIG. 2
is a circuit diagram of one embodiment of the auxiliary lighting system of FIG.
1
.
FIGS. 3A-8
are block diagrams of other embodiments of the auxiliary lighting system of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to
FIG. 1
, there is shown auxiliary lighting system
10
of the present invention. System
10
generally comprises control circuit
12
, HID lamp status circuit
14
, switch circuit
16
and auxiliary light source
18
. In one embodiment, auxiliary light source
18
is an incandescent lamp having a pair of input leads.
“HID lamp status circuit
14
has an input for connection to status signal
20
produced by the ballast system. Status signal
20
is representative of the operational state or status of a high-intensity discharge (“HID”) lamp of the ballast system. Status signal
20
indicates whether a HID lamp
30
is “ON”, “OFF” or in the run-up phase. In one embodiment, status signal
20
is an error signal provided by the feedback power circuitry of the ballast system. However, it is to be understood that status signal
20
can be any type of signal that has particular characteristics that can be evaluated by HID lamp status circuit
14
. For example, status signal
20
can be a DC signal having a first predetermined amplitude when the HID lamp
30
is “OFF”, and a second predetermined amplitude when the HID lamp
30
is “ON”. In another example, status signal
20
can be a digital signal that has a logic HIGH level when the HID lamp
30
is energized, and a logic LOW level when the HID lamp
30
is not energized. In a further example, status signal
20
can be in the form of a DC (Direct Current) voltage when the HID lamp
30
is OFF, and an AC (Alternating Current) signal when the HID lamp
30
is ON. HID lamp status circuit
14
determines whether status signal
20
meets predetermined signal criteria. If status signal
20
outputted by the ballast is an error voltage, the predetermined signal criteria is a reference voltage. However, the predetermined signal criteria can have other forms depending upon the form of status signal
20
. HID lamp status circuit
14
provides control signal
24
for input into control circuit
12
for controlling the output of control circuit
12
. The characteristics of control signal
24
depend upon whether HID lamp status circuit
14
determines that status signal
20
meets the predetermined signal criteria.”
“Switch circuit
16
controls the application of voltage source V
1
to the auxiliary light source
18
. The voltage source V
1
is generated by the ballast system within which auxiliary lighting system
10
is located. Typically, the voltage source V
1
comprises
480
volts DC. Switch circuit
16
has a first state that effects application of the voltage source V
1
to the auxiliary light source
18
, and a second state that isolates the voltage source V
1
from the auxiliary light source
18
.”
Control circuit
12
is responsive to signal
24
provided by HID lamp status circuit
14
. Control circuit
12
has a first state when HID lamp status circuit
14
determines that status signal
20
meets the predetermined signal criteria and a second state when HID lamp status circuit
14
determines status signal
20
does not meet the predetermined signal criteria. When control circuit
12
is in the first state, control circuit
12
outputs control signal
22
for input into switch circuit
16
that configures switch circuit
16
into the first state. When control circuit
12
is in the second state, control circuit
12
outputs control signal
22
that configures switch circuit
16
into the second state.
In one embodiment, control circuit
12
is configured as a fixed duty-cycle square wave oscillator. In such an embodiment, when control circuit
12
is in the first state, control circuit
12
outputs signal
22
as a square-wave signal having a fixed duty-cycle and a predetermined amplitude. In a preferred embodiment, the frequency of the square-wave signal is above 20 kHz. However, it is to be understood that other frequencies can be used as well. In one embodiment, the duty cycle of the square wave is about 25%. However, control circuit
12
can be configured to output a square wave signal having a duty cycle that is greater or less than 25%. When control circuit
12
is in the second state, control circuit
12
outputs signal
22
as a relatively very low-amplitude DC voltage signal.
It is to be understood that although control circuit
12
is described herein as an oscillator circuit, control circuit
12
can be configured as any other suitable chopper circuit that can provide a regulated voltage to auxiliary light source
18
. For example, thyristor choppers and other suitable transistor choppers can be used. Furthermore, other voltage regulation schemes can be used to supply the voltage to auxiliary light source
18
, e.g. pulse width modulation, phase control, etc.
Switch circuit
16
is configured in the first state when signal
22
comprises the square wave signal described in the foregoing description. When in the first state, switch circuit
16
effects application of voltage source V
1
to auxiliary light source
18
. As described in the foregoing description, voltage source V
1
is typically about 480 volts DC. Since signal
20
comprises a square-wave signal during this mode of operation, the voltage applied to auxiliary light source
18
is in the form of a square-wave having a peak amplitude of V
1
, i.e. 480 volts DC. Switch circuit
16
is configured in the second state when signal
22
comprises the relatively very low amplitude DC voltage signal described in the foregoing description. When in the second state, switch circuit
16
isolates voltage source V
1
from auxiliary light source
18
.
“In one embodiment of the invention, status signal
20
is an error voltage signal produced by the feedback power circuitry (not shown) of a ballast system (not shown) and HID lamp status circuit
14
is configured to evaluate the amplitude of the error signal. In such an embodiment, HID lamp status circuit
14
has an input coupled to error signal
20
. When the HID lamp
30
in the ballast system is extinguished, the amplitude of signal
20
is less than a predetermined threshold voltage. When the HID lamp
30
is ignited, the amplitude of error signal
20
increases to an amplitude that is greater than the predetermined threshold voltage. As shown in
FIG. 1
, HID lamp status circuit
14
provides signal
24
that is inputted into control circuit
12
. When the amplitude of error signal
20
is less than a predetermined threshold, HID lamp status circuit
14
provides signal
24
with a first predetermined amplitude that configures control circuit
12
in the first state. As a result, switch circuit
16
is configured in the first state and voltage source V
1
is applied to auxiliary light source
18
. When the amplitude of error signal
20
is greater than a predetermined threshold voltage, HID lamp status circuit
14
provides signal
24
with a second predetermined amplitude that configures control circuit
12
in the second state. As a result, switch circuit
16
is configured in the second state and voltage source V
1
is isolated from auxiliary light source
18
.”
Referring to
FIG. 2
, there is shown a schematic diagram of one embodiment of auxiliary lighting system
10
of the present invention. Control circuit
12
comprises resistor divider network comprising resistors R
1
and R
2
. One end of resistor R
1
is connected to positive supply voltage +Vcc and the other end of resistor R
1
is connected to one end of resistor R
2
. The other end of resistor R
2
is connected to circuit ground. Control circuit
12
further comprises voltage comparator
102
. In a preferred embodiment, comparator
102
is configured as a precision voltage comparator such as the commercially available LM393 voltage comparator manufactured by National Semiconductor. The non-inverting (+) input of comparator
102
is connected to the junction of resistors R
1
and R
2
. Resistors R
3
is connected between the non-inverting (+) input of comparator
102
and the output of comparator
102
. Resistor R
4
is connected between the inverting (−) input of comparator
102
and the output of comparator
102
. Resistor R
5
is connected between the output of comparator
102
and +Vcc. Capacitor C
1
is connected between the inverting (−) input of comparator
102
and circuit ground and functions as a decoupling capacitor.
In one embodiment, resistors R
1
, R
2
, R
3
, R
4
and R
5
have resistance values of about 100 KΩ, 5.6Ω, 220 KΩ, 100 KΩ, and 22 KΩ, respectively. In one embodiment, capacitor C
1
has a capacitance of about 0.001 uF. Control circuit
12
further includes transistors T
1
and T
2
. Transistor T
1
is an NPN transistor and transistor T
2
is a PNP transistor. Transistor T
1
comprises base
104
, collector
106
and emitter
108
. Similarly, transistor T
2
comprises base
110
, collector
112
and emitter
114
. Bases
104
and
110
of transistors T
1
and T
2
, respectively, are connected to the output of comparator
102
. Collector
106
of transistor T
1
is connected to +Vcc. Emitter
108
of transistor T
1
is connected to emitter
114
of transistor T
2
. Collector
112
of transistor T
2
is connected to circuit ground. The junction of emitters
108
and
114
provides output signal
22
. In one embodiment, transistor T
1
is a 2N4401 transistor and transistor T
2
is a 2N4403 transistor.
Referring to
FIG. 2
, switch circuit
16
comprises power transistor T
3
. In one embodiment, transistor T
3
is a FET power transistor having gate
116
that is connected to output signal
22
, drain
118
that is connected to one end of light source
18
, and source
120
that is connected to circuit ground. In one embodiment, transistor T
3
is a commercially available 7N60 power FET.
“Referring to
FIG. 2
, in one embodiment, HID lamp status circuit
14
comprises an input circuit that comprises resistor R
6
and capacitor C
2
. Resistor R
6
has one end thereof connected to error signal
20
and another end connected to one of capacitor C
2
. The other end of capacitor C
2
is connected to circuit ground. HID lamp status circuit
14
further includes comparator
122
. In one embodiment, comparator
122
is configured as the LM393 precision voltage comparator described in the foregoing description. HID lamp status circuit
14
further includes Zener diode D
1
that is connected between the inverting (−) input of comparator
122
and circuit ground. Zener diode D
1
provides a reference voltage. In one embodiment, the Zener voltage of Zener diode D
1
is about 5.6. volts. Resistor R
7
is connected between the inverting (−) input of comparator
122
and +Vcc. Resistor R
8
is connected between the output of comparator
122
and +Vcc. In one embodiment, resistors R
7
and R
8
have resistances of about 22 KΩ. Resistors R
7
and R
8
form a voltage divider network. HID lamp status circuit
14
further includes transistor T
4
. Transistor T
4
includes base
124
connected to the output of comparator
122
, collector
126
that is connected to the bases
104
and
110
of transistors T
1
and T
2
, respectively, and emitter
128
that is connected to circuit ground. Signal
24
is provided by collector
126
. In one embodiment, transistor T
4
is a 2N4401 transistor.”
“Referring to
FIG. 2
, HID lamp status circuit
14
provides signal
24
that is inputted into control circuit
12
and connected to the bases
104
and
110
of transistors T
1
and T
2
, respectively. When the HID lamp
30
in the ballast system is extinguished, the amplitude of signal
20
is less than the predetermined threshold voltage set by Zener diode D
1
. In response, comparator
122
outputs a low-amplitude DC signal that turns “OFF” transistor T
4
thereby providing signal
24
with a first predetermined amplitude that results in transistors T
1
and T
2
being turned “ON”. As a result, control circuit
12
is configured in the first state and outputs control signal
22
as a square-wave signal. In response, transistor T
3
of switch circuit is
16
is turned “ON” and thus, switch circuit
16
is configured in the first state and voltage source V
1
is applied to auxiliary light source
18
. When the amplitude of error signal
20
is greater than a predetermined threshold voltage, HID lamp status circuit
14
outputs a relatively higher amplitude signal that turns “ON” transistor T
4
thereby providing signal
24
with a voltage level that causes transistors T
1
and T
2
to be turned “OFF”. As a result, control circuit
12
is configured in the second state and outputs signal
22
with an amplitude that turns “OFF” transistor T
3
of switch circuit
16
thereby configuring switch circuit
16
in the second state so as to isolate voltage source V
1
from auxiliary light source
18
.”
“Although the foregoing description is in terms of signal
20
comprising an error signal produced by the feedback power circuitry of the ballast, it is to be understood that status signal
20
can be configured to have other suitable forms or characteristics that can indicate the operational state or status of the HID lamp
30
, and that HID lamp status circuit
14
can be appropriately modified to evaluate such a status signal.”
Referring to
FIG. 3A
, there is shown another embodiment of the auxiliary lighting system of the present invention wherein control circuit
12
is configured as a pulse width modulator (“PWM”) circuit. System
100
generally comprises HID lamp status circuit
102
, PWM circuit
104
, switch circuit
106
and auxiliary light source
108
. HID lamp status circuit
102
functions in the same manner as HID lamp status circuit
14
described in the foregoing description. In one embodiment, switch circuit
106
and auxiliary light source
108
have the same configurations as switch circuit
16
and auxiliary light source
18
, respectively, described in the foregoing description. Circuit
102
receives status signal
20
, which was described in the foregoing description, and outputs signal
110
that enables or disables PWM circuit
104
. When circuit
102
determines that status signal
20
meets predetermined signal characteristics, signal
110
enables PWM circuit
104
to output control signal
112
to switch circuit
106
. Control signal
112
comprises a pulse train wherein each pulse has a width. In response, switch circuit
106
is configured to effect application of voltage source V
2
to auxiliary light source
108
. When circuit
102
determines that status signal
20
does not meet predetermined signal characteristics, signal
110
disables PWM circuit
104
so that that signal
112
configures switch circuit
106
to isolate voltage source V
2
from auxiliary light source
108
. In a preferred embodiment, voltage source V
2
is a fixed or constant DC rail voltage such as 480 volts or 240 volts. In a preferred embodiment, PWM circuit
104
is configured as a constant duty cycle PWM circuit for use with a regulated DC voltage source or a single input rectified AC voltage.
Referring to
FIG. 3B
, there is shown another embodiment of the auxiliary lighting system of the present invention. System
200
generally comprises HID lamp status circuit
202
, PWM circuit
204
, switch circuit
206
, and auxiliary light source
208
. PWM circuit
204
, switch circuit
206
and auxiliary light source
206
are generally the same in configuration and function as PWM circuit
104
, switch circuit
106
and auxiliary light source, respectively, described in the foregoing description. System
200
further includes AND gate
210
, the purpose of which is discussed in the ensuing description. PWM circuit
204
outputs constant duty cycle control signal
212
that is inputted into AND gate
212
. HID lamp status circuit
202
receives status signal
20
and determines whether signal
20
meets predetermined signal criteria. If signal
20
meets the predetermined signal criteria, circuit
202
outputs enabling signal
213
for input into AND gate
210
thereby causing AND gate
210
to output signal
214
that conforms to signal
212
. Signal
214
configures switch circuit
206
so as to effect application of voltage source V
2
to auxiliary light source
208
. If signal
20
meets the predetermined signal criteria, circuit
202
outputs signal
213
with disabling characteristics (e.g. logic “LOW” level) thereby preventing signal
212
from being recreated at the output of AND gate
210
. As a result, AND gate
210
outputs signal
214
with characteristics that configure switch circuit
206
so as to isolate voltage source V
2
from to auxiliary light source
208
.
“The embodiments described in
FIGS. 3A and 3B
can be configured without the HID lamp status circuits. In a such a configuration, status signal
20
has a first logic level when the HID lamp
30
is extinguished, a second logic level when the HID lamp
30
is “ON” and is inputted directly into PWM circuit
104
so as to either disable or enable PWM circuit
104
, depending upon the logic level of signal
20
. Similarly, signal
20
can be used to drive AND gate
210
directly.”
“Referring to
FIG. 4
, there is shown another embodiment of the auxiliary lighting system of the present invention. System
300
is configured for use with a single input AC voltage source V
3
. The AC voltage can be either half-wave or full-wave rectified depending on the magnitude of the AC voltage. System
300
generally comprises HID lamp status circuit
302
, phase control circuit
304
, triac
306
and auxiliary light source
308
. Triac
306
functions as a switch that, when “ON”, causes AC voltage source to be applied to light source
308
and when “OFF”, causes the AC voltage source V
3
to be isolated from light source
308
. HID lamp status circuit
302
receives status signal
20
and has generally the same configuration as the HID lamp status circuits described in the previous embodiments. Circuit
302
outputs signal
310
that either enables or disables phase control circuit
304
. If circuit
302
determines that status signal
20
meets predetermined signal criteria (i.e. the HID lamp is “ON”), signal
310
enables phase control circuit
304
to output signal
312
to the gate of triac
306
so as to turn “ON” triac
306
. Triac
306
, when “ON”, is on only for a constant portion of each AC half cycle resulting in a proportional output. If circuit
302
determines that status signal
20
does not meet predetermined signal criteria (i.e. the HID lamp
30
is extinguished), signal
310
enables phase control circuit
304
to output signal
312
to the gate of triac
306
so as to turn “OFF” triac
306
thereby isolating light source
308
from voltage source V
3
. Thus, system
300
provides constant phase control for a single input voltage.”
“It is to be understood that the embodiment described in
FIG. 4
can be configured without the HID lamp status circuit. In a such a configuration, status signal
20
has a first logic level when the HID lamp
30
is extinguished, a second logic level when the HID lamp
30
is “ON” and is inputted directly into phase control circuit
304
and either disables or enables phase control circuit
304
, depending upon the logic level of signal
20
.”
“Referring to
FIG. 5
, there is shown another embodiment of the auxiliary lighting system of the present invention. Auxiliary lighting system
400
is configured to operate with a variable DC voltage or a rectified input voltage source V
4
. System
400
generally comprises HID lamp status circuit
402
, pulse width modulator (“PWM”) circuit
404
, switch circuit
406
, and auxiliary light source
408
which have generally the same configuration and function in the same manner as HID lamp status circuit
102
, pulse width modulator circuit
104
, switch circuit
106
, and auxiliary light source
108
, respectively, shown in FIG.
3
A. PWM circuit
404
outputs signal
405
for input into switch circuit
406
. System
400
further includes amplifiers
410
and
412
. Amplifier
410
is configured as a differential amplifier and amplifies the voltage drop across light source
408
. The output of amplifier
410
is coupled to an input of amplifier
412
. Reference voltage V
R1
is coupled another input of amplifier
412
. Amplifier
412
is configured as an error amplifier and outputs error signal
414
. Error signal
414
is inputted into PWM circuit
404
wherein the magnitude of error signal
414
varies the pulse width of the pulses of signal
405
and thus, the duty cycle of signal
405
. Thus, the voltage across light source
408
is monitored and is used to vary the pulse width of signal
405
in order to maintain the voltage applied to light source
408
at a constant level. System
400
allows the output voltage across light source
408
to be accurately controlled regardless of the fluctuations in voltage source V
4
. System
400
is most suitable if a constant DC or rectified AC source are not available.”
In an alternate embodiment, system
400
is configured without HID lamp status circuit
402
. In such a configuration, status signal
20
is inputted directly into PWM circuit
404
and has a first level or magnitude that enables PWM circuit
404
to output signal
405
that will turn “ON” switch circuit
406
and a second level or magnitude that disables PWM circuit
404
so as to turn “OFF” switch circuit
406
. In a further embodiment, system
400
utilizes and an AND gate (not shown) that receives status signal
20
and signal
405
and wherein the output of the AND gate drives switch circuit
406
.
“Referring to
FIG. 6
, there is shown another embodiment of the auxiliary lighting system of the present invention. Auxiliary lighting system
500
is configured for use with a single input AC voltage source V
5
. The AC voltage can be either half-wave or full-wave rectified depending on the magnitude of the AC voltage. Auxiliary lighting system
500
generally comprises the system shown in
FIG. 4
with the addition of feedback components. Thus, system
500
generally comprises HID lamp status circuit
502
, phase control circuit
504
, triac
506
and auxiliary light source
508
which have generally the same configuration and function in the same manner as HID lamp status circuit
302
, phase control circuit
304
, triac
306
, and auxiliary light source
308
, respectively, shown in FIG.
4
. Phase control circuit
504
outputs signal
505
for input into the gate of triac
506
. System
500
further includes rectifier circuit
510
and amplifier
512
. Rectifier circuit
510
is configured as an active rectifier circuit and converts the AC voltage drop across light source
508
into a DC voltage. Rectifier circuit
510
outputs the DC voltage signal
514
for input into amplifier
512
. Reference voltage V
R2
is coupled to another input of amplifier
512
. Amplifier
512
is configured as an error amplifier and outputs error signal
516
which represents the difference between the magnitude of signal
514
and reference voltage VR
2
. Error signal
516
is inputted into phase control circuit
504
. The magnitude of error signal
516
varies the phase of signal
505
. Thus, the voltage across light source
508
is monitored and is used to control triac
506
in order to maintain the voltage applied to light source
508
at a constant level. System
500
allows the output voltage across light source
508
to be accurately controlled regardless of the fluctuations in voltage source V
5
. System
500
is most suitable if a constant DC or rectified AC source are not available. In an alternate embodiment, system
500
is configured without HID lamp status circuit
502
. In such a configuration, status signal
20
is inputted directly into phase control circuit
504
in a manner similar to that described in the foregoing description pertaining to the embodiment shown in FIG.
4
.”
“Referring to
FIG. 7
, there is shown a further embodiment of the auxiliary lighting system of the present invention. System
600
is configured for use with a variable input AC voltage source V
6
. The AC voltage can be either half-wave or full-wave rectified depending on the magnitude of the AC voltage. System
600
generally comprises HID lamp status circuit
602
, phase control circuit
604
, triac
606
and auxiliary light source
608
. Triac
606
functions as a switch that, when “ON”, causes AC voltage source V
6
to be applied to light source
608
and when “OFF”, causes the AC voltage source V
6
to be isolated from light source
608
. HID lamp status circuit
602
receives status signal
20
and has generally the same configuration as the HID lamp status circuits described in the previous embodiments. Circuit
602
outputs signal
610
that either enables or disables phase control circuit
604
. If circuit
602
determines that status signal
20
meets predetermined signal criteria (i.e. the HID lamp
30
is “ON”), signal
610
enables phase control circuit
604
to output signal
612
to the gate of triac
606
so as to turn “ON” triac
606
. Triac
606
, when “ON”, is on only for a constant portion of each AC half cycle resulting in a proportional output. If circuit
602
determines that status signal
20
does not meet predetermined signal criteria (i.e. the HID lamp
30
is extinguished), signal
610
enables phase control circuit
604
to output signal
612
to the gate of triac
606
so as to turn
“OFF” triac
606
thereby isolating light source
608
from voltage source V
6
. System
600
further includes feed forward control circuit
614
that is connected between the voltage applied to light source
608
and phase control circuit
604
. Feed forward control circuit
614
outputs control signal
616
that controls phase control circuit
604
so as to vary the phase of signal
612
. As a result, triac
606
responds to the varying phase of signal
612
thereby varying the AC voltage applied to light source
608
. Feed forward control circuit
614
compensates for known changes in the input voltage source V
6
. It is to be understood that the embodiment described in
FIG. 7
can be configured without the HID lamp status circuit as described in the foregoing description. In a such a configuration, status signal
20
has a first logic level when the HID lamp
30
is extinguished, a second logic level when the HID lamp
30
is “ON” and is inputted directly into phase control circuit
604
so as to either disable or enable phase control circuit
604
, depending upon the logic level of signal
20
.”
“Referring to
FIG. 8
, there is shown another embodiment of the auxiliary lighting system of the present invention. Auxiliary lighting system
700
is suitable for use with a variable DC voltage source or a rectified AC voltage source V
7
. Auxiliary lighting system
700
generally comprises HID lamp status circuit
702
, pulse width modulation (“PWM”) circuit
704
, switch circuit
706
, and auxiliary light source
708
which have the same configuration and function in the same manner as HID lamp status circuit
202
, pulse width modulation (“PWM”) circuit
204
, switch circuit
206
and auxiliary light source
208
, respectively, of system
200
that was described in the foregoing description. PWM circuit
704
outputs signal
710
that controls switch circuit
706
so as to either effect application of voltage source V
7
to light source
708
or isolate light source
708
from voltage source V
8
. System
700
further includes feed forward control circuit
712
that is connected between the voltage applied to light source
708
and PWM circuit
704
. Feed forward control circuit
712
outputs control signal
714
that controls PWM circuit
704
so as to vary the pulse width of signal
710
. As a result, switch circuit
706
is affected by the varying pulse width of signal
710
and therefore varies the voltage applied to light source
708
. Feed forward control circuit
712
compensates for known changes in the input voltage source V
7
. System
700
is suitable for situations wherein the variations in voltage source V
7
are well defined. The pulse width of signal
710
is adjusted as a function of voltage source V
7
in order to maintain the voltage that is applied to light source
708
at a constant level. For example, if voltage source V
7
comprises a DC voltage source, system
700
operates in such a manner that the pulse width of signal
710
is inversely proportional to the supply voltage thereby providing a substantially constant output voltage.”
“It is to be understood that the embodiment described in
FIG. 8
can be configured without the HID lamp status circuit as described in the foregoing description. In a such a configuration, status signal
20
has a first logic level when the HID lamp
30
is extinguished, a second logic level when the HID lamp
30
is “ON” and is inputted directly into PWM circuit
704
so as to either disable or enable phase control circuit
704
, depending upon the logic level of signal
20
. In another embodiment, system
700
is configured to utilize an AND gate that receives status signal
20
and signal
710
in a manner similar to the configuration shown in FIG.
3
B.”
The auxiliary lighting system of the present invention can be inexpensively integrated with conventional electronic HID ballast systems thereby eliminating the problems associated with external auxiliary lighting control circuitry. Furthermore, the auxiliary lighting system of the present invention can be inexpensively manufactured with commercially available components.
The principals, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. The invention which is intended to be protected herein should not, however, be construed as limited to the particular forms disclosed, as these are to be regarded as illustrative rather than restrictive. Variations in changes may be made by those skilled in the art without departing from the spirit of the invention. Accordingly, the foregoing detailed description should be considered exemplary in nature and not limited to the scope and spirit of the invention as set forth in the attached claims.
Claims
- 1. An auxiliary lighting system for a HID lamp, comprising:an auxiliary light source; a switch circuit for controlling the application of a voltage source to the auxiliary light source, the switch circuit having a first state that effects application of the voltage source to the auxiliary light source, and a second state that isolates the voltage source from the auxiliary light source; a control circuit having an input for receiving and being responsive to a signal that indicates the operational state of a HID lamp, the control circuit controlling the duration of time in which the switch circuit is configured in the first state and in the second state wherein the duration of time depends upon the operational state of the HID lamp, the control circuit including a pulse width modulation circuit that output a control signal comprising a pulse train that controls the switch circuit; and a feedback circuit for comparing the voltage applied to the auxiliary light source to a reference voltage and outputting an error signal having a magnitude that is based upon the difference between the voltage applied to the auxiliary light source and the reference voltage, the pulse width modulation circuit being responsive to the error signal such that the pulse width of the pulses of the pulse train is varied in accordance with the magnitude of the error signal.
- 2. An auxiliary lighting system for a HID lamp, comprising:an auxiliary light source; a switch circuit for controlling the application of a voltage source to the auxiliary light source, the switch circuit having a first state that effects application of the voltage source to the auxiliary light source, and a second state that isolates the voltage source from the auxiliary light source; a control circuit having an input for receiving and being responsive to a signal that indicates the operational state of a HID lamp, the control circuit controlling the duration of time in which the switch circuit is configured in the first state and in the second state wherein the duration of time depends upon the operational state of the HID lamp, the control circuit including comprises a phase control circuit for outputting a control signal to the switch circuit; and a feedback circuit for comparing the voltage applied to the auxiliary light source to a reference voltage and outputting an error signal having a magnitude that is based upon the difference between the voltage applied to the auxiliary light source and the reference voltage, the phase control circuit being responsive to the error signal such that the phase of the control signal is varied in accordance with the magnitude of the error signal.
- 3. The auxiliary lighting system according to claim 2 wherein voltage source is an AC voltage source and the feedback circuit further comprises a rectifier circuit for converting the AC voltage applied to the auxiliary light source to a DC voltage, and an error amplifier for comparing the DC voltage to a reference voltage and outputting an error signal having a magnitude for input into the phase control circuit wherein the phase of the control signal is varied according to the magnitude of the error signal.
- 4. A method of operating an auxiliary lighting system for use with a HID lamp, comprising the steps of:providing an auxiliary lighting system comprising an auxiliary light source, a switch circuit having a first state for effecting application of a voltage source to the auxiliary light source and a second state for isolating the voltage source from the auxiliary light source, and a control circuit that is responsive to the status signal, the control circuit outputting a control signal to control the switch circuit so as to configure the switch circuit in either the first state or the second state depending upon the state of energization of the HID lamp, the control circuit comprising a phase control circuit; providing a status signal that indicates the state of energization of a HID lamp; controlling the duration of time in which the switch circuit is configured in the first state and the second state wherein the duration of time depends upon the state of energization of the HID lamp; determining the voltage applied to the auxiliary light source; comparing the determined voltage to a predetermined reference voltage to produce an error signal having a magnitude; and adjusting the phase of the control signal in accordance with the magnitude of the error signal.
- 5. The method according to claim 4 wherein the voltage source is an AC voltage and the determining step comprises the step of converting the AC voltage applied to the auxiliary light source to DC voltage, the DC voltage defining the determined voltage.
- 6. An auxiliary lighting system for a HID lamp, comprising:an auxiliary light source; a switch circuit for controlling the application of a voltage source to the auxiliary light source, the switch circuit having a first state that effects application of the voltage source to the auxiliary light source, and a second state that isolates the voltage source from the auxiliary light source; and a control circuit having an input for receiving and being responsive to a signal that indicates the operational state of a HID lamp, the control circuit controlling the duration of time in which the switch circuit is configured in the first state and in the second state wherein the duration of time depends upon the operational state of the HID lamp.
- 7. The auxiliary lighting system according to claim 6 further comprising an HID lamp status circuit having an input for connection to an HID lamp status signal that represents the operational state of a high-intensity discharge lamp, the HID lamp status circuit determining whether the HID lamp status signal meets predetermined signal criteria and outputting the signal to which the control circuit is responsive, the control circuit controlling the duration of time in which the switch circuit is configured in the first state and in the second state wherein said duration of time depends upon whether the HID lamp status signal meets the predetermined signal criteria.
- 8. The auxiliary lighting system according to claim 7 wherein the predetermined signal criteria comprises a predetermined threshold voltage and the HID lamp status circuit compares the magnitude of the HID lamp status signal to the predetermined threshold voltage wherein HID lamp status signal meets the predetermined signal criteria when the magnitude of the HID lamp status signal is less than the predetermined threshold voltage and wherein the HID lamp status signal does not meet the predetermined signal criteria when the magnitude of the HID lamp status signal is greater than the predetermined threshold voltage, the duration of time in which the control circuit configures the switch circuit into first state being generally the same as the duration of time in which the magnitude of the HID lamp status signal is less than the predetermined threshold voltage, the duration of time in which the control circuit configures the switch circuit into the second state being generally the same as the duration of time in which the magnitude of the HID lamp status signal is greater than the predetermined threshold voltage.
- 9. The auxiliary lighting system according to claim 6 wherein the control circuit comprises a chopper circuit.
- 10. The auxiliary lighting system according to claim 9 wherein the chopper circuit comprises a square-wave oscillator that outputs a square wave signal that controls the switch circuit.
- 11. The auxiliary lighting system according to claim 9 wherein the chopper circuit comprises a pulse width modulation circuit that outputs a control signal comprising a pulse train that controls the switch circuit.
- 12. The auxiliary lighting system according to claim 11 further comprising a feedback circuit for comparing the voltage applied to the auxiliary light source to a reference voltage and outputting an error signal having a magnitude that is based upon the difference between the voltage applied to the auxiliary light source and the reference voltage, the pulse width modulation circuit being responsive to the error signal such that the pulse width of the pulses of the pulse train is varied in accordance with the magnitude of the error signal.
- 13. The auxiliary lighting system according to claim 11 further comprising a feed forward control circuit for monitoring the voltage source and outputting a signal for input into the pulse width modulation circuit for varying the pulse width of the pulses of the pulse train in accordance with the variations in the voltage supply.
- 14. The auxiliary lighting system according to claim 9 wherein the voltage source is an AC voltage source and the control circuit comprises a phase control circuit for outputting a control signal to the switch circuit.
- 15. The auxiliary lighting system according to claim 14 further comprising a feedback circuit for comparing the voltage applied to the auxiliary light source to a reference voltage and outputting an error signal having a magnitude that is based upon the difference between the voltage applied to the auxiliary light source and the reference voltage, the phase control circuit being responsive to the error signal such that the phase of the control signal is varied in accordance with the magnitude of the error signal.
- 16. The auxiliary lighting system according to claim 15 wherein voltage source is an AC voltage source and the feedback circuit further comprises a rectifier circuit for converting the AC voltage applied to the auxiliary light source to a DC voltage, and an error amplifier for comparing the DC voltage to a reference voltage and outputting an error signal having a magnitude for input into the phase control circuit wherein the phase of the control signal is varied according to the magnitude of the error signal.
- 17. The auxiliary lighting system according to claim 14 further comprising a feed forward control circuit for monitoring the voltage source and outputting a signal for input into the phase control circuit for varying the phase of the control signal outputted by the phase control circuit in response to variations in the voltage supply.
- 18. A method of operating an auxiliary lighting system for use with a HID lamp, comprising the steps of:providing an auxiliary lighting system comprising an auxiliary light source, and a switch circuit having a first state for effecting application of a voltage source to the auxiliary light source and a second state for isolating the voltage source from the auxiliary light source; providing a status signal that indicates the state of energization of a HID lamp; and controlling the duration of time in which the switch circuit is configured in the first state and the second state wherein the duration of time depends upon the state of energization of the HID lamp.
- 19. The method according to claim 18 wherein the auxiliary lighting system further comprises a control circuit that is responsive to the status signal, the control circuit outputting a control signal to control the switch circuit so as to configure the switch circuit in either the first state or the second state depending upon the state of energization of the HID lamp, the control circuit comprising a pulse width modulator circuit and wherein the control signal comprises a pulse train having a plurality of pulses, each pulse having a pulse width, the method further comprising the steps of:determining the voltage applied to the auxiliary light source; comparing the determined voltage to a predetermined reference voltage to produce an error signal having a magnitude; and adjusting the width of the pulses of the pulse train in accordance with the magnitude of the error signal.
- 20. The method according to claim 18 wherein the auxiliary lighting system further comprises a control circuit that is responsive to the status signal, the control circuit outputting a control signal to control the switch circuit so as to configure the switch circuit in either the first state or the second state depending upon the state of energization of the HID lamp, the control circuit comprising a pulse width modulator circuit and wherein the control signal comprises a pulse train having a plurality of pulses, each pulse having a pulse width, the method further comprising the steps of:monitoring variations in the voltage supply; and adjusting the width of the pulses of the pulse train in accordance with the variations in the voltage supply.
- 21. The method according to claim 18 wherein the auxiliary lighting system further comprises an HID lamp status circuit having an input for connection to an electrical signal that represents the state of energization of the HID lamp and determining whether the electrical signal meets predetermined signal criteria and outputting a signal that defines the status signal, the controlling step comprising the step of configuring the switch circuit in the first state for a duration of time that is generally the same as the duration of time in which the status signal meets the predetermined signal criteria.
- 22. The method according to claim 21 wherein the controlling step further comprises of configuring the switch circuit in the second state for a duration of time that is generally the same as the duration of time in which the status signal does not meet the predetermined signal criteria.
- 23. The method according to claim 22 wherein the auxiliary lighting system further comprises a control circuit that is responsive to the status signal, the control circuit outputting a control signal to control the switch circuit so as to configure the switch circuit in either the first state or the second state depending upon the state of energization of the HID lamp, the control circuit comprising a phase control circuit, the method further comprising the steps of:determining the voltage applied to the auxiliary light source; comparing the determined voltage to a predetermined reference voltage to produce an error signal having a magnitude; and adjusting the phase of the control signal in accordance with the magnitude of the error signal.
- 24. The method according to claim 23 wherein the voltage source is an AC voltage and the determining step comprises the step of converting the AC voltage applied to the auxiliary light source to DC voltage, the DC voltage defining the determined voltage.
- 25. The method according to claim 22 wherein the auxiliary lighting system further comprises a control circuit that is responsive to the status signal, the control circuit outputting a control signal to control the switch circuit so as to configure the switch circuit in either the first state or the second state depending upon the state of energization of the HID lamp, the control circuit comprising a phase control circuit, the method further comprising the steps of:monitoring variations in the voltage supply; and adjusting the phase of the control signal in accordance with the variations in the voltage supply.
US Referenced Citations (12)