U.S. patent application number 10/261030 was filed with the patent office on 2004-04-01 for high-intensity discharge lamp ballast with live relamping feature.
Invention is credited to Prasad, Himamshu V..
Application Number | 20040061454 10/261030 |
Document ID | / |
Family ID | 31946514 |
Filed Date | 2004-04-01 |
United States Patent
Application |
20040061454 |
Kind Code |
A1 |
Prasad, Himamshu V. |
April 1, 2004 |
HIGH-INTENSITY DISCHARGE LAMP BALLAST WITH LIVE RELAMPING
FEATURE
Abstract
A dimming ballast (100) for a high-intensity discharge lamp (10)
includes an ignitor (120), a control circuit (140), and a dimming
interface (160) for connection to an external dimming controller
(30). Following lamp replacement (10), external dimming controller
(30) receives a user relamp command and, in response, sends a
special relamp signal to dimming interface (160). In response to
the special relamp signal, dimming interface (160) communicates
with control circuit (140), which directs ignitor (120) to provide
high voltage pulses for igniting the replaced lamp. In an
alternative embodiment, an external control device such as a triac
dimmer (40) receives a user relamp command following lamp
replacement and, in response, sends a special relamp signal to a
control circuit (240), which directs ignitor (220) to provide high
voltage pulses for igniting the replaced lamp.
Inventors: |
Prasad, Himamshu V.;
(Rolling Meadows, IL) |
Correspondence
Address: |
Kenneth D. Labudda
Osram Sylvania, Inc.
800 N. Church St.
Lake Zurich
IL
60047
US
|
Family ID: |
31946514 |
Appl. No.: |
10/261030 |
Filed: |
September 30, 2002 |
Current U.S.
Class: |
315/291 ;
315/224; 315/DIG.4 |
Current CPC
Class: |
H05B 41/042 20130101;
Y10S 315/04 20130101; H05B 41/2881 20130101; H05B 41/382 20130101;
Y02B 20/204 20130101; H05B 41/288 20130101; Y02B 20/00
20130101 |
Class at
Publication: |
315/291 ;
315/224; 315/DIG.004 |
International
Class: |
H05B 039/04 |
Claims
What is claimed is:
1. A ballast for powering at least one high-intensity discharge
lamp, comprising: a pair of input connections adapted to receive a
conventional source of alternating current (AC) voltage; a pair of
output connections for connection to the lamp; a pair of dimming
control inputs for connection to an external dimming controller,
the external dimming controller being operable to receive a user
relamp command and, in response, provide a special relamp signal at
the dimming control inputs; an ignitor coupled to the output
connections and operable to provide high voltage pulses for
igniting the lamp; a control circuit coupled to the ignitor and
operable to direct the ignitor to provide high voltage pulses; and
a dimming interface coupled to the dimming control inputs and the
control circuit, the dimming interface being operable, in response
to the special relamp signal from the external dimming controller
following replacement of the lamp, to command the control circuit
to direct the ignitor to provide high voltage pulses for igniting
the lamp.
2. The ballast of claim 1, wherein the external dimming controller
includes a rotatable knob, and the user relamp command consists
essentially of rotating the knob fully clockwise and then rotating
the knob fully counterclockwise.
3. The ballast of claim 1, wherein the special relamp signal
consists essentially of a waveform having a positive transition
from about zero volts to about ten volts, and a negative transition
from about ten volts to about zero volts.
4. The ballast of claim 2, wherein the special relamp signal
consists essentially of a waveform having a positive transition
from about zero volts to about ten volts, and a negative transition
from about ten volts to about zero volts.
5. The ballast of claim 1, wherein the external dimming controller
includes a dedicated relamp switch, and the user relamp command
consists essentially of depressing and releasing the relamp
switch.
6. The ballast of claim 4, wherein the special relamp signal
consists essentially of a waveform having a positive transition
from about zero volts to about ten volts, and a negative transition
from about ten volts to about zero volts.
7. A ballast for powering at least one high-intensity discharge
lamp, comprising: first and second input connections adapted to
receive a conventional source of alternating current (AC) voltage,
wherein the first input connection is coupled to a hot lead of the
source of AC voltage via an external control device, and the second
input connection is coupled to a neutral lead of the source of AC
voltage, the external control device being operable to receive a
user relamp command following replacement of the lamp and, in
response, to provide a special relamp signal at the first input
connection; a pair of output connections for connection to the
lamp; an ignitor coupled to the output connections and operable to
provide high voltage pulses for igniting the lamp; and a control
circuit coupled to the first input connection and the ignitor, the
control circuit being operable to receive the special relamp signal
from the external control device following replacement of the lamp
and, in response, to direct the ignitor to provide high voltage
pulses for igniting the lamp.
8. The ballast of claim 7, wherein the external control device is a
conventional triac dimmer.
9. The ballast of claim 7, wherein the special relamp signal
consists essentially of a sinusoidal voltage wherein at least one
half-cycle of the sinusoidal voltage has a truncated portion.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the general subject of
circuits for powering discharge lamps. More particularly, the
present invention relates to a ballast for high intensity discharge
lamps that accommodates lamp replacement and ignition while power
is applied to the ballast.
BACKGROUND OF THE INVENTION
[0002] Electronic ballasts for powering high-intensity discharge
(FID) lamps usually have a timed ignition period of about 20 to 30
minutes, during which time high voltage pulses (e.g., of 3000 volts
or more) are provided in order to ignite the lamp. For reasons of
safety and reliability, if the lamp does not ignite within the
timed ignition period, the ballast stops providing the ignition
pulses.
[0003] When a HID lamp reaches the end of its useful operating
life, the lamp either self-extinguishes or is extinguished by
end-of-life protection circuitry in the ballast. If the lamp is
replaced, the fact that a new lamp has been installed is not easily
sensed because, unlike fluorescent lamps, HID lamps do not have
filaments. Thus, in order to restart the timed ignition period and
provide high voltage pulses for igniting the lamp, the input power
to the ballast needs to be toggled in order to reset the ignition
timer circuitry within the ballast. While toggling of the input
power will work fine in applications where only one ballast is
coupled to an electrical branch circuit, it is not a practical
solution in typical installations where multiple ballasts and lamps
are powered from the same branch circuit. In the latter case,
toggling of the input power will extinguish the other operating
lamps, and the hot reignition of the extinguished lamps may take up
to 10 minutes or more.
[0004] Currently, no manufacturer appears to offer an electronic
HID ballast with a live relamping feature. Moreover, although there
are a number of possible approaches that may be used to address
this problem, each has significant disadvantages.
[0005] In one possible approach, the ballast may be designed such
that ignition pulses are turned on and off at a predetermined rate.
For example, after the lamp has extinguished (due to end-of-life),
the ignition pulses could be turned on (e.g., for a few minutes)
and turned off (e.g., for a few hours). This will ensure that a
replaced lamp will eventually light up when the ignition pulses are
turned on. The disadvantages of this approach include safety and
reliability concerns due to the periodic (though not continuous)
application of ignition pulses, as well as the fact that ignition
of the replaced lamp may not occur for as long as several hours
following replacement. With regard to the latter disadvantage, it
should be appreciated that prompt ignition of a replaced lamp is
highly desirable.
[0006] Another possible approach involves providing a mechanical
switch or reset button on the ballast, wherein the switch or button
is momentarily depressed by a user (i.e., the person who changed
the lamp) following lamp replacement in order to direct the ballast
to provide ignition pulses. An obvious disadvantage of this
approach is that the switch or button would have to be made
accessible to the user, which is not practical in most
installations.
[0007] A third approach would be to equip the ballast with a
wireless receiver, wherein a user may send a signal to the ballast
via a wireless remote control in order to direct the ballast to
provide ignition pulses following lamp replacement. Because of the
additional circuitry that would be required, this approach is quite
complex and expensive.
[0008] Thus, a need exists for an electronic HRD ballast that
accommodates live relamping in an efficient and cost-effective
manner, and without negatively affecting other ballasts and lamps
that are operating at the same time. Such a ballast would represent
a considerable advance over the prior art.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 describes a ballast for high intensity discharge
lamps that implements a live relamping feature via an external
dimming controller, in accordance with a first preferred embodiment
of the present invention.
[0010] FIG. 2 describes a ballast for high intensity discharge
lamps that implements a live relamping feature via a triac dimmer,
in accordance with a second preferred embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] A first preferred embodiment of the present invention is
described with reference to FIG. 1. Ballast 100 includes a pair of
input connections 102, 104 adapted to receive a source of
conventional alternating current (AC) voltage 20, a pair of output
connections 106, 108 for connection to at least one high-intensity
discharge (FD) lamp 10, and a pair of dimming control inputs 110,
112 for connection to an external dimming controller (30). Ballast
100 is an electronic HID dimming ballast that includes an ignitor
120, a control circuit 140, and a dimming interface 160. Ignitor
120 is coupled to output connections 106, 108. Control circuit 140
is coupled to ignitor 120. Dimming interface 160 is coupled to
control circuit 140 and to dimming control inputs 110, 112.
[0012] It should of course be understood that ballast 100
preferably includes other circuits, such as an inverter for
providing steady-state power to lamp 10 and a suitable front-end
for providing current-limiting and/or power factor correction,
which are not shown or described in detail herein.
[0013] During operation, ignitor 120 provides high voltage ignition
pulses between output connections 106, 108 for igniting lamp 10.
Control circuit 140, which is coupled to ignitor 120, controls when
and how ignitor 120 provides ignition pulses. Dimming interface
160, which is coupled to dimming control inputs 110, 112 as well as
control circuit 140, receives a dimming voltage signal (V.sub.DIM)
from external dimming controller 30. In response to V.sub.DIM,
dimming interface 160 directs other circuitry in ballast 100 (e.g.,
an inverter circuit, not shown) to correspondingly adjust the
amount of current supplied to lamp 10.
[0014] For the aforementioned normal operating purposes, ignitor
120, control circuit 140, dimming interface 160, and external
dimming controller 30 may all be realized by circuits that are
well-known to those skilled in the art. For example, dimming
interface 160 may realized according to the teachings of U.S. Pat.
No. 5,457,360, the pertinent disclosure of which is incorporated
herein by reference. Similarly, ignitor 120 and control circuit 140
are realizable by any of a number of suitable circuits known in the
art.
[0015] In addition to its aforementioned functionality with regard
to effecting adjustment of the amount of current provided to lamp
10, dimming interface 160 is configured to receive a special
relamping signal from external dimming controller 30. The special
relamping signal may consist of any of a large number of possible
signals. As but one example, the special relamping signal may
consist of a squarewave or trapezoidal signal having a positive
transition from about zero volts to about ten volts, followed by a
negative transition from about ten volts to about zero volts. Such
a signal can be provided by having the user provide a user relamp
command by rotating the adjustment knob of external dimming
controller 30 fully clockwise (i.e., zero to 10 volts) and then
fully counterclockwise (i.e., 10 volts to zero volts). In the case
of an external dimming controller that has a slide adjustment
rather than a rotatable knob, the same signal can be achieved by
moving the slide adjustment to one extreme and then the other.
Alternatively, the special relamping signal may be generated via a
dedicated "relamp" pushbutton switch on external dimming controller
30 that, when depressed and released by the user, provides the same
type of transitions as previously described.
[0016] Upon receipt of the special relamping signal, dimming
interface 160 communicates with control circuit 140, which directs
ignitor 120 to immediately provide high voltage ignition pulses for
igniting lamp 10. In this way, ballast 100 uses its preexisting
dimming interface 160 to provide for prompt ignition of a replaced
lamp without requiring cycling of the AC input power.
[0017] The live relamping approach just described with reference to
FIG. 1 is well-suited for installations that include dimming
ballasts because external dimming controller 30, as well as the low
voltage control wiring by which external dimming controller 30
interacts with dimming interface 160, is already present. An
alternative preferred approach that is well suited for
installations that do not include dimming ballasts is described in
FIG. 2.
[0018] Referring now to FIG. 2, a ballast 200 for powering at least
one HID lamp comprises first and second input connections 202, 204,
a pair of output connections 206, 208, an ignitor 220, and a
control circuit 240. Input connections 202, 204 are adapted to
receive a conventional source of alternating current (AC) voltage
20, such as 120 volts (rms) at 60 hertz. More specifically, first
input connection 202 is coupled to a hot lead 22 of AC source 20
via an external control device 40 that can be implemented, for
example, by a triac dimmer; second input connection 204 is coupled
to a neutral lead 24 of AC source 20. Output connections 206, 208
are adapted for connection to HID lamp 10. Control circuit 240 is
coupled between first input connection 202 and ignitor 220. Ignitor
220 is coupled to control circuit 240 and output connections 206,
208.
[0019] Following a replacement of lamp 10, the user (i.e., the
person who just replaced the lamp) provides a user relamp command
to triac dimmer 40 to indicate that lamp 10 has been replaced. In
response to the user relamp command, triac dimmer generates a
special relamp signal. For example, a user can manipulate triac
dimmer 40 so that triac dimmer 40 momentarily "chops" (i.e.,
truncates at least a portion of one half-cycle of) the sinusoidal
AC voltage provided to input connections 202, 204. Control circuit
240 detects this momentary "chop" in the AC voltage and
correspondingly directs ignitor 220 to immediately provide high
voltage pulses for igniting lamp 10. In this way, ballast 200 works
in conjunction with a triac dimmer (or other suitable control
device placed in series with the AC line) to provide for prompt
ignition of a replaced lamp without requiring cycling of the AC
input power.
[0020] Although the present invention has been described with
reference to certain preferred embodiments, numerous modifications
and variations can be made by those skilled in the art without
departing from the novel spirit and scope of this invention.
* * * * *