GB2445186A

GB2445186A - High intensity discharge lamp control and protection circuit

Info

Publication number: GB2445186A
Application number: GB0626011A
Authority: GB
Inventors: Wen-Hsin Chao
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-12-29
Filing date: 2006-12-29
Publication date: 2008-07-02
Also published as: GB0626011D0

Abstract

A high intensity discharge (HID) lamp output control and protection circuit comprises four comparators CA1-CA4, a timer T and a pulse width modulation IC controller P. Comparator CA1 detects blocking oscillation conditions; comparator CA2 detects whether the HID lamp is lit, comparator CA3 detects too low voltage and short circuit of the lamp; comparator CA4 detects too high voltage of the HID lamp; the timer T protects the lamp at zero load and when it is unlit; and the pulse width modulation IC controller P controls the lamp output power, starts the lamp and has a soft-start function. The circuit provides fast response, power saving, and high stability protecting functions for abnormal lamp conditions such as an aged lamp, without requiring connection to both ends of the lamp.

Description

Title: LAMP OUTPUT CONTROL AND PROTECTION CIRCUIT OFAN

ELECTRONIC CONTROLLER FOR A HIGH INTENSITY DISCHARGE

LAMP

This invention relates to a lamp output control and protection circuit of the S electronic controller for High Intensity Discharge Lamp; it is composed by four sets of comparator, timer and pulse width modulation 1C controller to make its protecting functions for blocking oscillation and overload, short circuit, overvoltage. Moreover, timer proceeds protecting functions for zero load and unlighted lamp; pulse width modulation IC controller controls lamp output power, proceeds protecting functions for abnormal situations, and starts the lamp. Hence, the purposes of fast response, power-saving, high stability, and low manufacture cost can be procured.

HID has high luminance efficiency and good color rendering index, and could become a key lighting tool in the future. However, the element of traditional controller for driving HID (ballast) is silicon steel shim. The traditional ballast for HID is low efficiency and has no protecting function for lamp under abnormal output.

Hence, electronic controller has been developed in recent years. Electronic controller has advantage of high efficiency, miniaturization and free of noise. However, design of protection circuit for abnormal lamp or the condition of zero load or short circuit at output end is the crucial problem. The reason is HID is started by high voltage, 4KV -5KV lamp voltage at the instant time of starting, but only ten some volts lamp voltage at the instant time of lightening. In addition, there is inaccuracy between different lamp shapes and different brands; moreover, many failure situations will be happened on lamps. Therefore, the present electronic controllers for HID have problems of either having incomplete protecting functions or too complicated circuit.

It is not easy to promptly control actions of output starting or circuit work stopping at the time of proceeding processes control movement. Micro-controller may be applied to tackle the processes. Micro-controller has powerful routinizaton control ability, but processing speed is slow; in addition, its protecting effect is not good for some lamp abnormal situations, and its cost is more expensive. Furthermore, when detect lamp condition, detect process must be proceeded at the position of both ends of the lamp or series connection lamps. Judgment is easy to he a fault because of big inaccuracy of lamp and high miscellaneous signals.

The objective of this invention is to provide a lamp output control and protection circuit of the electronic controller for high intensity discharge lamp; it is composed by four sets of comparator, timer and pulse width modulation IC controller.

Comparator makes its protecting functions for blocking oscillation and overload, short circuit, overvoltage; moreover, timer proceeds protecting functions for zero load and unlighted lamp; pulse width modulation IC controller controls lamp output power, proceeds protecting fUnctions for abnormal situations, and starts the lamp.

Hence, the purposes of fasi response, power-saving, high stability, and low manufacture cost can be procured.

Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments, with reference to the accompanying drawings, in which: Fig. 1 is a schematic view of the invention preferred embodiments.

Fig. 2 is a schematic view of the circuit (I) of the invention preferred embodiments.

Fig. 3 is a schematic view of the circuit (2) of the invention preferred embodiments. -In the detailed description of the preferred embodiments, it should be noted that like elements are indicated by the same reference numerals throughout the disclosure.

Please refer to detailed description of fig.l, 2 and3. This invention relates to a lamp output control and protection circuit of the electronic controller for high intensity discharge lamp, the circuit board I it is composed by four sets of differential motion cnlarged comparator CAI,CA2,CA3,CA4, limer T and pulse width modulation IC controller P. The first set of comparator CA I is for detecting blocking oscillation; the second set of comparator CA2 is for detecting HID lamp is lightening or not; the third set of comparator CA3 will become a protecting function for detecting HID lamp if under the situation of too low voltage or short circuit; the fourth set of comparator CA4 will become a protecting function for detecting HID lamp under the situation of too high voltage. The flg.3 connection point al to a7 connects to fig.2 connection point hi to b7 respectively. Timer I proceeds protecting functions for zero load and unlighted lamp; pulse width modulation IC controller P controls lamp output power, proceeds protecting functions for abnormal situations, and starts the lamp, and it also has soft-start function. The position for detecting lamp abnormal situation of the invention is not at both cnds of the lamp or series connection lamps, hence misjudgment caused by lamp starting miscellaneous signals or operation miscellaneous signals will become less. Signals for detecting too high lamp voltage are negative variation, low voltage motion. Current passed MOSFET will be applied to be signals for detecting too low lamp voltage. The lower lamp voltage is, and the current passed MOSFET will be bigger. This signal will be delivered to every comparator for judgment; misjudgment on low voltage situation after instant starting and high lamp voltage situation at normal operation of old lamp could be avoided. Detecting signals clearly match high speed motion of every comparator and stable operation of timer T, and when turn on power, making use of effects of circuit B for controlling electromagnetic interference and rectification circuit, fixed high voltage output will be created at a point (400V) via active power calibrating circuit, outputting one to two seconds and stopping 15 to 25 seconds; at the time, blocking oscillation circuit CAl which is composed of comparator will be started instantly. Pulse width modulation IC controller P will output high frequency instantly and power control circuit will be turned on to lower b point to close to 0 V. Vab is about 400V, and lamp has not yet been started at the time. Every IC of the controller for High Intensity Discharge Lamp will output low frequency to start touch-off circuit, and both ends of the lamp will create about 4-5 KV high voltage pulse to start the lamp. When the lamp lightens comparator CA2, signal will be sent to notify CA I to stop blocking oscillation, and this signal will also stop timer's timing; since when power is turned an but lamp is not lightened, timer T will send out signal to stop all system's output. However, when lamp is aged and lamp voltage is high, detecting process will be proceeded by CA3; when overload, too low lamp voltage or output short circuit, detecting process will be proceeded by CA4.

Hence, the invention has advantages of fast response, power-saving, high stability, and low manufacture cost, and will be able to procure all necessary protecting jobs.

While the present invention has been described in connection with what is considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various S arrangements included within the spirit and scope of the broadest interpretations and equivalent arrangements.

Claims

1. A lamp output control and protection circuit of an electronic controller for a high intensity discharge lamp; said circuit comprising four sets of comparators, a timer and a pulse width modulation 1C controller; the first comparator is for detecting blocking oscillation; the second comparator is for detecting the lighting situation of the IlID lamp; the third comparator will become a protecting function for detecting the HID lamp under the situation of too low voltage or short circuit; the fourth comparator will become a protecting function for detecting the HID lamp under the situation of too high voltage; the timer has protecting functions for zero load and unlit lamp; the pulse width modulation IC controller controls lamp output power, has protecting functions for abnormal situations, and starts the lamp and it also has a soft-start function.

2. A lamp output control and protection circuit substantially as described herein with reference to the drawings.