GB2418082A

GB2418082A - Protection device for ac electronic dimmer

Info

Publication number: GB2418082A
Application number: GB0420358A
Authority: GB
Inventors: Wen-Hsin Chao
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-09-13
Filing date: 2004-09-13
Publication date: 2006-03-15
Anticipated expiration: 2024-09-13
Also published as: GB2418082B; GB0420358D0

Abstract

An electronic dimmer ac power supply protection device for the ac power supply inside an electronic dimmer has two current, driver, base pull-up resistors Re, Rf, two over current sensing, signal, filter capacitors Ca, Cb, and two MOSFETS, Q1, Q2. The base current of the sensor terminals in the IC is increased by the pull-up resistors Re, Rf so that the conducted current undergoes resistance sensing and returns to the IC current to drive the protection circuit. The MOSFETS Q1, Q2 are controlled with a trailing edge signal to reduce noise.

Description

241 8082 Title: ELECTRONIC DIMMER AC POWER SUPPLY PROTECTlOlS DEVICE The

invention herein relates to an electronic dimmer AC power supply protection device in which the alternating current power supply inside an electronic dimmer has two over current base resistors as well as two over current sensing resistors, enabling a small amount of current to drive the protection circuit to overcome and guard against rising temperature at the metal oxide semiconductor field effect transistors (MOSFET) during high wattage lamp operation and, furthermore, a trailing edge approach controls the said MOSFETs to reduce noise as well as stably control dimmer performance to thereby achieve a protective function.

Most conventional dimmers installed in lamps that vary luminosity from a bright to a soft glow utilize a TRIAC to control their circuits (as shown in FIG. I-A and FIG. l B); such dimmers are called leading edge dimmers and because they have a triggering component, dimmer adjustment generates considerable electromagnetic interference (EMI) to the extent that the lamp tube or the lamp tube controller may flicker and emit noise. At the same time, during the usage of high wattage light bulbs, the temperature of such dimmers elevates, resulting in circuit load incapacity, overheating, and damage.

In view of the above situation, the utilization of metal oxide semiconductor field effect transistors or MOSFETs enable the adjustment of alternating current electricity output to control lamp tube or lamp tube controller output efficiency in a protective circuit that protects the lamp tube or the lamp tube controller from excessive wattage output or other abnormalities, thereby averting dimmer damage and hazards. However, when the said controllers serve as the controlling components of the said dimmer, since the current flow of the said transistors must be monitored and sensing resistors are required at the power source of the said transistors to check for overly high resistance that increases temperature during transistor operation and thereby improves the rising operating temperature problem of the transistors, i.e. the sensing resistance becomes small, this results in the occurrence of another problem: an incapability to protect circuit driving. Furthermore, during the operation of the said transistors, the current of the sensing resistor signals must be regulated in order to start the driving of the protection circuit and thereby attain the operating voltage of the protection circuit in the IC, which would definitely result in the additional enlargement of the sensing resistance to accomplish and, as such, the re-occurrence of the rising operating temperature problem of the transistors.

In view of the preceding section, the applicant of the invention herein developed the content of the present invention to solve the existent technological problems.

The primary objective of the invention herein is to provide an electronic dimmer AC power supply protection device for the alternating current power supply inside electronic dimmers in which after two current, driver, base pull-up resistors as well as two over current sensing, signal, filter capacitors are interconnected with metal oxide semiconductor field effect transistors (MOSFET), the base current of the over current protection terminals in the IC is increased such that conducted current undergoes resistance sensing and returns back to the TC current and, furthermore, a small amount of current drives the protection circuit to overcome rising temperature at the said transistors during high wattage lamp operation, thereby achieving a protective function.

Another objective of the invention herein is to provide an electronic dimmer AC power supply protection device for the alternating current power supply inside electronic dimmers in which a trailing edge approach inputs a zero current detection waveform that serves as a starting control signal and utilizes a delay time adjustment switch off action signal for controlling the continuity and cutoff of the said MOSFETs to reduce noise as well as stably control the performance of said dimmer.

Figure 1-A is a schematic diagram of the prior art.

Figure 1-B is the prior art wave form.

Figure 2 is a schematic diagram of the invention herein.

Figure 3 is the wave form of the invention herein.

Referring to FIG. 2 and FIG. 3, the electronic dimmer AC power supply protection device of the invention herein is an alternating currentpowered electronic dimmer in a lamp comprised of an IC supported by four rectifier diodes D1, D2, D3, and D4; two metal oxide semiconductor field effect transistors (MOSFET) Q1 and Q2; two driver resistors R1 and R2; one DC base resistor R3; two zero voltage detection resistors R4 and R5; two dimming resistors R6 and VR1; two over current sensing resistors Ra and Rb; two over current base resistors Rc and Rd; and one Zener diode ZD1; and one filter capacitor C3, wherein the two over current protection terminals of the IC each have a respective current pull-up resistor Re and Rf and a current detection signal filter capacitor Ca and Cb.

As such, after the current pull-up resistor Re and Rf and a current checking signal filter capacitor Ca and Cb are respectively connected to the two over current protection terminals in the IC, the base current of the two over current protection terminals in the IC is increased such that conducted current undergoes resistance sensing and returns back to the IC current and, furthermore, only a small amount of current drives the protection circuit to overcome rising temperature at the said transistors Q1 and Q2 during high wattage lamp operation. At the same time, the invention herein by means of a trailing edge approach, i.e., without triggering components, checks for variations in inputted alternating current and inputs a zero current detection waveform that serves as a starting I S control signal and, furthermore, utilizes a delay time adjustment switch off action signal for controlling the continuity and cutoff of the said transistors Q1 and Q2 and thus reduces noise as well as stably controls the said dimmer and lamp tube to thereby achieve a protective function.

In summation of the preceding section, since the present invention possess practical utility and thus meets new patent application requirements, the invention herein is submitted to the patent bureau for review and the granting of the commensurate patent rights.

Claims

1. An electronic dimmer AC power supply protection device for the alternating current power supply inside electronic dimmers consisting of metal oxide semiconductor field effect transistors (MOSFET) interconnected with two over current base resistors as well as two over current sensing resistors which as a result raise the base current of the over current protection terminals in the dimmer IC such that conducted current undergoes resistance sensing and returns back to the IC current, a small amount of current drives the protection circuit to overcome rising temperature at the said MOSFETs during high wattage lamp operation, while a trailing edge approach inputs a zero current detection waveform that serves as a starting control signal and utilizes a delay time adjustment switch off action signal for controlling the continuity and cutoff of the said MOSFETs to reduce noise as well as stably control the performance of the said dimmer to thereby achieve a protective function.

2. An electronic dimmer AC power supply protection device substantially as described herein with reference to the drawings.