Transformerless LED driving circuit

• US 5,917,779 A
• Filed: 04/16/1997
• Issued: 06/29/1999
• Est. Priority Date: 04/16/1997
• Status: Expired due to Term

• Current Assignee: Sigmatron International Incorporated
• Original Assignee: Gabriel, Inc.
• Inventors: Ralson, James M., Ramsey, Gregory Jay
• Primary Examiner(s): MISKA, VIT W
• Application Number:
  US08/842,636
• Time in Patent Office: 804 Days
• Field of Search: 368/67, 368/82-84, 368/239-242, 315/194, 315/196, 315/200, 315/201, 315/206, 315/207, 315/227, 315/272, 315/273, 345/82, 345/608, 345/211
• US Class Current: 368/83
• CPC Class Codes: G04G 15/00 Time-pieces comprising means to be operated at preselected times or after preselected time intervals G04G11/00, G04G13/00 take precedence; electronic timers G04F1/005; pulse delay circuits H03K5/13; electronic time-delay switches H03K17/28; electronic time-programme switches which automatically terminate their operation after the programme is completed H03K17/296
• CPC Class Codes: G04G 3/00 Producing timing pulses driving circuits for stepping motors G04C3/14; producing preselected time intervals for use as timing standards G04F5/00; pulse technique in general H03K; control, synchronisation, or stabilisation of generators in general H03L

Abstract

A transformerless oven timer which uses a 20 pin microcontroller connected to light emitting diodes. The microcontroller has 2 Kbytes of 8 bit read only memory and has software etched therein. The microcontroller can transfer power and voltage to the light emitting diodes when the oven is connected to, and powered by, an electrical outlet. The software etched into the microcontroller detects whether a resistor is connected to the microcontroller and converts a pin on the microcontroller from an input into an output. The software also synchronizes the microcontroller with the frequency of the electrical outlet to provide that the microcontroller keeps track of time. The transformerless oven timer also includes electrical circuitry connected to the microcontroller, where the electrical circuitry reduces the voltage and current provided to the microcontroller and to the light emitting diodes without using a transformer. The electrical circuitry also provides real resistance to reject noise from the electrical outlet.

Claims

1. An electrical circuit for providing that an AC voltage power source can sequentially power at least three sets of light emitting elements without needing a transformer connected therebetween, said electrical circuit comprising:

a programmed microcontroller in driving connection with the at least three sets of light emitting elements such that said programmed microcontroller can sequentially drive the at least three sets of light emitting elements, wherein each set includes at least one light emitting element; and

reactive drop circuitry connected to said programmed microcontroller and connectable to the AC voltage power source, wherein said reactive drop circuitry reduces the voltage and current transferred from the AC voltage power source to the at least three sets of light emitting elements through said programmed microcontroller, wherein said reactive drop circuitry reduces the voltage and current without utilizing a transformer.

2. The electrical circuit as recited in claim 1, said reactive drop circuitry communicating a single pulse to said programmed microcontroller.

3. The electrical circuit as recited in claim 1, said programmed microcontroller sequentially driving said at least three sets of light emitting elements one at a time.

4. The electrical circuit as recited in claim 1, each of said light emitting elements comprising a light emitting diode.

5. The electrical circuit as recited in claim 1, further comprising a plurality of switches connected to each light emitting element and to said programmed microcontroller, said programmed microcontroller decoding which of said switches is actuated.

6. The electrical circuit as recited in claim 1, said programmed microcontroller driving said at least three sets of light emitting elements in a sequence defined by software etched into said programmed microcontroller, said sequence being generally independent in relation to half-cycles of the AC voltage power source.

7. The electrical circuit as recited in claim 1, said reactive drop circuitry communicating a single pulse to said programmed microcontroller, said programmed microcontroller sequentially driving said at least three sets of light emitting elements one at a time in a sequence defined by software etched into said programmed microcontroller, said sequence being generally independent in relation to half-cycles of the AC voltage power source.

8. A transformerless digital display circuit connectable to and powerable by a high voltage power source, said transformerless digital display circuit comprising:

at least three sets of light emitting elements;

a microcontroller connected to the at least three sets of light emitting elements, wherein said microcontroller can sequentially transfer power and voltage to said at least three sets of light emitting elements when the transformerless digital display circuit is connected to, and powered by, the high voltage power source;

electrical circuitry connected to said microcontroller, wherein said electrical circuitry reduces the voltage and current which is provided to said microcontroller and said sets of light emitting elements by the high voltage power source when the transformerless digital display circuit is connected to, and powered by, the high voltage power source, and wherein said electrical circuitry adequately reduces the voltage and current which is provided to said microcontroller and said sets of light emitting elements by the high voltage power source without utilizing a transformer.

9. The electrical circuit as recited in claim 8, said electrical circuitry communicating a single pulse to said microcontroller.

10. The electrical circuit as recited in claim 8, said microcontroller sequentially driving said at least three sets of light emitting elements one at a time.

11. The electrical circuit as recited in claim 8, each of said light emitting elements comprising a light emitting diode.

12. The electrical circuit as recited in claim 8, further comprising a plurality of switches connected to each light emitting element and to said microcontroller, said microcontroller decoding which of said switches is actuated.

13. The electrical circuit as recited in claim 8, said microcontroller driving said at least three sets of light emitting elements in a sequence defined by software etched into said microcontroller, said sequence being generally independent in relation to half-cycles of the power source.

14. The electrical circuit as recited in claim 8, said electrical circuitry communicating a single pulse to said microcontroller, said microcontroller sequentially driving said at least three sets of light emitting elements one at a time in a sequence defined by software etched into said microcontroller, said sequence being generally independent in relation to half-cycles of the power source.

15. An electrical circuit for allowing a 120 Volt AC power source to provide a current of about 100 milliamps at a voltage of about 5 Volts to digital display circuitry without having to utilize a transformer within the electrical circuit to reduce the voltage received by the digital display circuitry from the 120 Volt AC power source, said electrical circuit comprising:

at least three sets of light emitting elements forming a digital display;

a microcontroller in driving connection with said at least three sets of light emitting elements such that said microcontroller can sequentially drive the at least three sets of light emitting elements, wherein each set includes at least one light emitting element; and

a reactive element connected between the power source and said microcontroller, wherein said reactive element reduces the voltage transferred from said power source to said microcontroller by 95 Volts.

16. An electrical circuit connectable to a 120 Volt AC power source, said electrical circuit comprising:

a programmed microcontroller;

at least three sets of light emitting elements connected to, and driven by, said programmed microcontroller such that said programmed microcontroller can sequentially drive the at least three sets of light emitting elements, wherein each set includes at least one light emitting element;

current and voltage dropping circuitry, wherein said current and voltage dropping circuitry provides a reactive voltage drop from the 120 Volt AC power source when the electrical circuit is connected thereto, wherein said reactive voltage drop provides that the 120 Volt AC power source can power said light emitting elements without having to provide a transformer between the 120 Volt AC power source and said light emitting elements.

17. A transformerless digital display circuit connectable to and powerable by a 120 Volt AC power source, said transformerless digital display circuit comprising:

at least three sets of light emitting elements;

a 20 pin microcontroller connected to said at least three sets of light emitting elements such that said microcontroller sequentially drives the at least three sets of light emitting elements, wherein each set includes at least one light emitting element, said microcontroller having 2 Kbytes of 8 bit read only memory, said microcontroller having software etched therein, wherein said microcontroller can sequentially transfer power and voltage to said sets of light emitting elements when the transformerless digital display circuit is connected to, and powered by, the high voltage power source, and wherein said software detects whether a resistor is connected to said microcontroller and converts a pin on the microcontroller from an input into said microcontroller from said 120 Volt AC power source to an output from said microcontroller to at least one light emitting element; and

electrical circuitry connected to said microcontroller, wherein said electrical circuitry reduces the voltage and current which is provided to said microcontroller and said light emitting elements by the high voltage power source when the transformerless digital display circuit is connected to, and powered by, the high voltage power source, and wherein said electrical circuitry adequately reduces the voltage and current which is provided to said microcontroller and said light emitting elements by the high voltage power source without utilizing a transformer.

18. The transformerless digital display circuit as defined in claim 17, wherein said software synchronizes with the frequency of the 120 Volt AC power source to provide that the microcontroller keeps track of time.

19. A transformerless digital oven timer on an oven connectable to and powerable by an electrical outlet providing 120 Volts of AC power, said transformerless digital oven timer comprising:

at least three sets of light emitting elements;

a 20 pin microcontroller connected to said light emitting elements such that said microcontroller sequentially drives the at least three sets of light emitting elements, wherein each set includes at least one light emitting element, said microcontroller having 2 Kbytes of 8 bit read only memory, said microcontroller having software etched therein, wherein said microcontroller can sequentially transfer power and voltage to said light emitting elements when the oven is connected to, and powered by, the electrical outlet, wherein said software detects whether a resistor is connected to said microcontroller and converts a pin on the microcontroller from an input into said microcontroller to an output from said microcontroller, and wherein said software synchronizes the microcontroller with the frequency of the power provided by the electrical outlet to provide that the microcontroller keeps track of time; and

electrical circuitry connected to said microcontroller, wherein said electrical circuitry reduces the voltage and current which is provided to said microcontroller and to said light emitting elements by the electrical outlet when the oven is connected to, and powered by, the electrical outlet, wherein said electrical circuitry adequately reduces the voltage and current which is provided to said microcontroller and to said light emitting elements by the electrical outlet without utilizing a transformer, and wherein said electrical circuitry provides real resistance to reject noise from the electrical outlet.