Tynax ~ Patent Library

Patent for Sale:

Triac-Based AC Dimmer suitable for LED modules    

The Patent offers a solution to dimming the new generation of LED modules. The industry says the modules are "dimmable", street knowledge say otherwise, and users are frustrated and slower to adopt


The Technology offers a solution to the problem of dimming the new generation of LED modules -- perhaps the fastest growing new products in consumer and industrial markets (practically all new lighting installations are LED). "Legacy" 120 vac dimmers were designed for incandescent and cannot be easily updated -- hence the flicker and flashing. Meanwhile the industry points the finger of blame everywhere but at themselves. Bottom Line: Users have come to expect the performance and convenience of legacy ... don't get it ... hence a conundrum.

Operating from the secondary side of a standard transformer, the Technology has been in production for about 10 years and about 10,000 units are in everyday use. A recent update within the confines of the Patent allows flawless dimming of the new LED modules in 12 vac and 24 vac configurations. Costing, performance, reliability, size, and ability to retrofit to existing wiring systems (which made legacy a perennial favorite) remain about the same.

The Patent offers a real solution to a pressing problem in a very active technology area. This Patent has 64 forward citations and went through rigious prosecution. The title is clean and ready to assign.

Primary Application of the Technology

Primary uses for the Technology are in traditional applications already using low-voltage (12 vac, 24 vac) for power, including landscape, patio, swimming pool, display, etc. The outdoor lighting market accounts for about 10 percent of the overall power used for illumination.

The Technology is readily adaptable to the larger interior lighting market with the addition of a standard magnetic transformer -- wet area including bathroom, kitchen, and laundry. Here low voltage would actually better serve by providing improved "close in" capability such as illumination within a shower enclosure or directly over a sink or counter. While a 120-12 vac step down transformer would be required, transformers are older technology with high efficiency and reliability, plus a surprisingly low cost.

Because LED's provides equal illumination with far less power, low voltage LED lighting is also retofittable to dining, living, bedroom areas over existing wiring systems. For example 250 watts (20 amps) of 12 vac LED lighting provides an equal amount of illumination as 1000 watts of incandescent or 500 watts of fluorescent -- adequate for a large residential room or a commercial office.

How the Technology Solves the Problem

A triac is the preferred semiconductor device for use in AC dimming because it is low-cost and reliable, and the associated driver circuitry is likewise. Nothing else even comes close. The triac of course switches on and off in rapid succession giving the dimmed light the appearance of steady illumination.

Once a triac switches off, however, a small amount of current flow is necessary for it to switch back on (about 100 mA). This trickle of current is never a problem with incandescent lighting because the filament is inherently a low-value resistor. However with the new generation of LED's, once the triac switches off current flow abruptly ceases such that the triac cannot easily turn back on and does so (if at all) with a series of flashes and flickers.

The obvious solution is to shunt a resistor of appropriate value across the LED module to achieve a minimal current flow. With the 120 vac legacy dimmer, a "dummy" load consisting of a 15 watt resistor or a 15 watt incandescent light bulb is sufficient to restore satisfactory dimming performance. This remedy is obviously impractical.

However at 12 (or 24) vac with the Technology, only about one watt of dissipation is required to restore dimming performance such that a small fixed resistor can be inconspicuous included on the dimmer board = problem eloquently solved for about ten cents.

Competitive Advantage

The first generation of LED lighting used the LED lamp familiar as an "on" indicator in combination with a dropping resistor -- all configured in series and parallel strings to achieve some desired level of illumination. The new generation of LED lighting is built on a substantial semiconductor substrate and includes additional circuitry to perform some combination of transforming voltage to a lower level, regulating voltage, preventing thermal and voltage overloads, and so forth. The new generation is seemingly a roaring success in all ways except being readily dimmable.

Remember that the enormous consumer and commercial markets are oriented toward best size, easy installation and refit, reliability, safety, and above all low cost. These same markets are referenced to the legacy triac ac dimmer and incandescent lighting combination, and expecting the same with LED. The lighting industry is obviously overpromising when they label the new LED's modules "dimmable". I believe that the industry is frantically searching for an acceptable solution, though having limited success.

Therefore the competitive advantage of the technology is that it works very well rather than spotty, is proven in active use, and is available right now.

Comments on Deal Structure, Potential Terms and Restrictions

The owner prefers an outright sale as he is retiring and going sailing. During negotiations they're may be short periods (two weeks?) when communications may be limited to narrow-band email (SSB, text only). Title to the Technology is clean for a first-time-through assignment. My patent attorney has agreed to be on tap for a smooth and delay-free transaction.

Frequently Asked Questions

Again remember that the public is feeling a bit jaded because those new LED bulbs they just bought at Home Depot and installed over the kitchen table flicker and flash when driven by a legacy dimmer thereby driving everyone nuts. Calling the LED manufacturer for resolution is useless because they only blame the problem on the dimmer manufacturer, and likewise.

Some government contracts even mandate that dimming be included on new lighting installations, yet compliance can be difficult or impossible. The best engineering talent in the business have tried to solve this problem though with questionable results. The market is expecting a cheap and effective solution.

So most users have probably given up on even asking "does your Technology actually work"? The answer is yes, very well though with some minor qualifications: The dimming range is about 5:1 = within the most used illumination levels and some LED's are a little better than others in this regard. An adjustment potentiometer included on the product allows the user to set a stable and satisfactory minimum brightness.

Perhaps 1.2 volts is dropped by the triac at the "full" setting, though the slightly decreased maximum brightness probably goes unnoticed and actually contributes to the longevity of LED devices, which can't tolerate overvoltage very well and probably have a short life when this happens.

As a few final notes, LED's are inherently a bit quirky in regards to dimming, while their high efficiency more than compensates. For example only one dimmer can be installed on a typical transformer or else some interaction is possible with inactive LED's such as a dull glow. At present, maximum power delivery for a single low voltage dimmer using standard components is about 500 watts.

Patent Summary

U.S. Patent Classes & Classifications Covered in this listing:

Class 315: Electric Lamp And Discharge Devices: Systems

Electric lamp and electric space discharge device systems: structural combinations with circuit elements; structural combinations with heating and/or cooling means; cathode-ray tubes; lamps and/or discharge devices as sole load devices; lamps; electric space discharge devices gas or vapor discharge devices; high vacuum-type discharge devices, and gas or vapor-type discharge devices claimed broadly; plural load device systems; art uses and combinations with art devices; testing electric lamps and discharge devices; and operating a lamp or a gas or vapor discharge device.

Subclass 276: Transformer in the supply circuit
Subclass 299: Plural regulators