Preferred embodiment to LED light string

• US 6,461,019 B1
• Filed: 03/29/2001
• Issued: 10/08/2002
• Est. Priority Date: 08/28/1998
• Status: Expired due to Term

• Current Assignee: Fiber Optic Designs Incorporated
• Original Assignee: Fiber Optic Designs Incorporated
• Inventors: Allen, Mark R.
• Primary Examiner(s): HUSAR, STEPHEN F
• Application Number:
  US09/819,736
• Publication Number:
  US 20020149938A1
• Time in Patent Office: 558 Days
• Field of Search: 362/555, 362/800, 362/806, 362/568, 362/249, 362/252, 362/545, 362/226
• US Class Current: 362/249.06
• CPC Class Codes: F21S 4/10 with light sources attached to loose electric cables, e.g. Christmas tree lights
• CPC Class Codes: F21V 19/001 the light sources being semiconductors devices, e.g. LEDs
• CPC Class Codes: F21V 19/002 the fastening means engaging the encapsulation or the packaging of the semiconductor device
• CPC Class Codes: F21V 19/0025 the fastening means engaging the conductors of the light source, i.e. providing simultaneous fastening of the light sources and their electric connections
• CPC Class Codes: F21V 19/04 with provision for changing light source, e.g. turret auxiliary devices for cleaning, placing, or removing incandescent lamps H01K3/32, fluorescent lamps H01J9/006
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H05B 45/30 Driver circuits
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

An LED light string employs a plurality of LEDs wired in block series-parallel, where the one or more series blocks, each driven at the same input voltage as the source voltage (110 VAC or 220 VAC), are coupled in parallel. The LED light string interfaces to the source voltage using a common household plug; it may also include a corresponding common, household socket, coupled in electrical parallel, to enable multiple light strings to be connected to each other from end to end. In order to directly drive a network of diodes without current-limiting circuitry, the voltage of each series block of diodes must be matched to the input source voltage. This voltage matching requirement for direct AC drive places fundamental restrictions on the number of diodes on each diode series block, depending on the types of diodes used. For the voltage to be “matched,” in each series block, the peak input voltage must be less than or equal to the sum of the maximum diode voltages for each series block.

Claims

1. A method of determining a workable number of light emitting diodes directly coupled in series to an AC power source to provide a stable light source, said method comprising the following steps:

determining an RMS voltage rating (V_RMS) of said AC power source;

determining an AC voltage rating for a particular type of light emitting diodes by determining an average voltage drop (V_avg) across said particular type of light emitting diode when connected to said AC power source;

calculating said workable number (WN) of said light emitting diodes according to the following formula

2. A light string formed by a series of light emitting diodes adapted to be directly connected to an AC power source and providing a stable light source, said light string formed by the method of determining a workable number of light emitting diodes directly coupled in series to said AC power source to provide said stable light source, said method comprising the following steps:

determining an RMS voltage rating (V_RMS) of said AC power source;

determining an AC voltage rating for a particular type of light emitting diodes by determining an average voltage drop (V_avg) across said particular type of light emitting diode when connected to said AC power source;

calculating said workable number (WN) of said light emitting diodes according to the following formula

3. The light string of claim 2, further comprising a lamp holder having a keyed offset, the lamp holder fixedly attached to each LED, and a lamp base having a notch adapted to receive the keyed offset of the lamp holder, thereby mechanically orienting and aligning each LED by its polarity.