Title of Invention

"ELECTRONIC CIRCUIT TO PROTECT LOAD AND POWER SUPPLY FROM OVERLOAD"

Abstract The present invention provides an electronic circuit to protect load and the power supply from overload comprising: - a first and a second switching means having their one conducting terminal connected to one terminal of power supply; - control terminal of said first switching means connected to another terminal of power supply through a biasing means and second conducting terminal of said first switching means connected to another terminal of power supply through a load thus enabling said first switching means to drive said load, and; - said second switching means has its control terminal connected to the second conducting terminal of the first switching means through another biasing means and its second conducting terminal is connected to the control terminal of the first switching means so that when the load shorts said second switching means disables the said first switching means thus protecting power supply and the remaining part of the load.
Full Text Electronic Circuit for Protecting Power Supply From Overload
Field of Invention:
The present invention relates to an electronic circuit for protecting load and power supply from overload.
Background of the Invention
The electronic circuits have biasing supply that drives the load attached to the circuit. Often in case of a shorted load the power supply gets overloaded. The chances of such overloading are substantially high particularly when the load comprises of multiple parallel-connected components.
For example, the Light Emitting Diodes (LEDs), which are generally used for illuminating objects. The power supply must be protected in case of the short-circuiting of LEDs, which could result in overloading of the power supply. Further, the LEDs must also be protected from high voltage.
The LEDs (load) are commonly connected in series as shown in figure A or in parallel configuration as shown in figure B. Both of these configurations have different drawbacks. For example, in case of series (figure A) configuration if one of the LED shorts the other LEDs will have higher voltage across them. Whereas in case when one of the LEDs is open the current through other LEDs reduces thereby resulting in low illumination. Further, if one of the LEDs shorts in case of parallel configuration then the power supply gets overloaded and can damage the remaining LEDs.
Accordingly, there is a need to develop an electronic circuit to protect the load and power supply from overload.

Object and summary of the invention:
The object of this invention is to obviate aforesaid drawbacks and to provide an electronic circuit to protect the load and the power supply and also reduce the power consumption.
To achieve said objective the present invention provides an electronic circuit to protect load and the power supply from overload comprising:
- a first and a second switching means having their one conducting terminal connected to the power supply;
- control terminal of said first switching means connected to the ground through a biasing means and second conducting terminal of said first switching means connected to the ground through a load enabling said first switching means to drive said load, and;
- said second switching means has its control terminal connected to the second conducting terminal of the first switching means through another biasing means and its second conducting terminal is connected to the control terminal of the first switching means so that when the load shorts said second switching means disables the said first switching means thereby protecting power supply and other components/load and reducing the power consumption.
The first and second switching means are the first and second transistors. The transistors include bipolar junction transistors that is PNP or/and NPN transistors. The emitters and collectors of the PNP or/and NPN transistors are the first and second conducting terminals and the bases are the control terminals of the transistors. The control terminals are biased through biasing means that are resistors. The load in the said electronic circuit includes Light Emitting Diode (LED) circuits.

Brief Description of the Accompanying Drawings:
The invention will now be described with reference to the drawings accompanying provisional specification.
Figure A shows LEDs (load) connected in series configuration. Figure B shows LEDs (load) connected in parallel configuration. Figure C shows the electronic circuit in accordance with the present invention.
Detailed Description:
Figures A and B have already been described under the heading background of
the invention.
Figure C shows the electronic circuit according to the present invention. Ideally, the electronic circuit of present invention can be embedded in an integrated chip or can externally be provided with one or more LEDs (load).
The electronic circuit has two PNP transistors T1 and T2 as first and second switching means. The first conducting terminals that is the emitters of both these transistors are connected to the positive of the power supply. The base (control terminal) of transistor T1 is connected through a biasing resistor R1 to ground. The collector of the transistor T1 is connected to the ground of the power supply through a load that is in this case is parallel-connected LEDs. The base (control terminal) of the transistor T2 is connected to the collector of the transistor T1 through R2 and the collector of transistor T2 is connected to the base of the transistor T1 Now when the circuit is functioning normally, that is the load is not shorted, the transistor T1 is in active region and the collector (second conducting terminal) of transistor T1 and the base of transistor T2 is at high voltage which forces transistor T2 in cutoff region and the collector of the transistor T2 remain at low voltage.

Now consider the case when one of the LEDs shorts, in such situation the base (control terminal) of the transistor T2 will be directly connected to the ground of the supply through R2 thus pushing the transistor T2 in active region allowing current to flow through its emitter and collector. This will cause the collector of transistor T2 at a high voltage and hence base (control terminal) of the transistor Ti at high voltage bringing the transistor Ti in the cutoff region thus disabling the circuit and protecting the power supply and remaining parts of the load.
A person skilled in the art will appreciate that, this circuit can be used for large number of LEDs (load), by connecting to small groups of LEDs so that in the event any LED shorts, only the small group will switch off and the remaining LEDs (load) will continue to glow. The circuit can be made as either a component or an IC or hybrid circuit to control one or more LEDs in combination. Also a person skilled in the art will understand that the invention described herein is illustrative only and other embodiment of the invention are also possible without deviating from the concept described above. Any such embodiment will fall under the scope of the present invention.






I Claim:
1. An electronic circuit to protect load and the power supply from overload
comprising:
- a first and a second switching means having their one conducting terminal connected to one terminal of power supply;
- control terminal of said first switching means connected to another terminal of power supply through a biasing means and second conducting terminal of said first switching means connected to another terminal of power supply through a load thus enabling said first switching means to drive said load, and;
- said second switching means has its control terminal connected to the second conducting terminal of the first switching means through another biasing means and its second conducting terminal is connected to the control terminal of the first switching means so that when the load shorts said second switching means disables the said first switching means thus protecting power supply and the remaining part of the load.

2. An electronic circuit as claimed in claim 1 wherein said first and second switching means are bipolar junction transistors.
3. An electronic circuit as claimed in claim 2 wherein said bipolar junction transistors are PNP/NPN transistors.
4. An electronic circuit as claimed in claim 3 wherein said PNP/NPN
transistors have a first conducting terminals as emitter and a second
conducting terminals as collector.

5. An electronic circuit as claimed in claim 1 wherein said control terminals of the switching means are the bases of the said PNP / NPN transistors.
6. An electronic circuit as claimed in claim 1 wherein said biasing means are resistors.
7. An electronic circuit as claimed in claim 1 wherein said load includes Light Emitting Diode (LED) circuits.
8. An electronic circuit to protect load and the power supply from overload substantially as herein described with reference to figure C of the accompanying drawings.

Documents:

1222-del-2002-abstract.pdf

1222-del-2002-claims.pdf

1222-del-2002-complete specification (granted).pdf

1222-DEL-2002-Correspondence Others-(09-11-2011).pdf

1222-del-2002-correspondence-others.pdf

1222-del-2002-correspondence-po.pdf

1222-del-2002-description (complete).pdf

1222-del-2002-description (provisional).pdf

1222-del-2002-drawings.pdf

1222-DEL-2002-Form-1-(09-11-2011).pdf

1222-del-2002-form-1.pdf

1222-DEL-2002-Form-13-(09-11-2011).pdf

1222-del-2002-form-13.pdf

1222-del-2002-form-19.pdf

1222-del-2002-form-2.pdf

1222-del-2002-form-5.pdf

1222-DEL-2002-GPA-(09-11-2011).pdf

1222-del-2002-gpa.pdf

1222-DEL-2002-Petition-137-(09-11-2011).pdf


Patent Number 241691
Indian Patent Application Number 1222/DEL/2002
PG Journal Number 30/2010
Publication Date 23-Jul-2010
Grant Date 20-Jul-2010
Date of Filing 09-Dec-2002
Name of Patentee VAISH HIMANGSHU RAI
Applicant Address S-19, PANCHSHILA PARK, NEW DELHI-110 017, INDIA
Inventors:
# Inventor's Name Inventor's Address
1 VAISH HIMANGSHU RAI S-19, PANCHSHILA PARK, NEW DELHI-110 017, INDIA
PCT International Classification Number H02H 3/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA