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Updated on:  Monday, September 17, 2007 02:22 PM

Imagineered Products & Services:  Examples of Imagineered Products & Services   
Introduction to Wind Energy Internet Business Ideas

This section describes some products and service ideas that have either come from my imagination as long as 40 years ago or are based on scientific research that hint at some new products. Some of the ideas listed have since become commercially available. 
In addition to the ideas listed below, I also have some more detailed discussions.

Imagineered Products and Services
Examples of Imagineered Products & Services
Updated on:  Monday, September 17, 2007 02:22 PM

Imagineered Products & Services:  Examples of Imagineered Products & Services   
Introduction to Wind EnergyInternet Business Ideas

OPTICALLY POWERED RFID TAGS
AND OPTICAL TAG READERS

OVERVIEW
A while back, I spent about two years doing research and product development in the RFID (Radio Frequency Identification Device) industry. During that time, I learned a lot about how these security systems work. In brief, the passive access control card or "tag" is read by holding it in front of a RFID card reader. The tag, which has same basic shape and size of a credit card, has a coil of wire connected to a microchip. The card is activated by a low frequency, typically 125KHz, magnetic field, generated by the reader. A small amount of the energy launched by the reader is collected by card's coil and is used to energize the card's microchip. Once the card's microchip is activated, it transmits a digital signal back to the reader. The encoded information sent from the card to the reader can be used to "identify" the card holder and can then therefore be used to unlock a door or gain access into a parking garage. Overall, the system if fairly simple. But, the magnetically coupled nature of the RFID communications system meant that the distance the cards could be read and the amount of information that could be sent was very limited if a passive (battery free) were used. I thought a lot about this problem and concluded that the system needed to change from a magnetic power transfer to a system that used an optical approach. The discussion below is a brief description how I think an optical method might work.
RFID LIMITATIONS
The existing low frequency (125KHz) RFID card reader systems have limited read ranges. Even when a large RFID tag antenna is used in conjunction with a powerful 125KHz exciter field, the maximum range may be limited to just a few feet. However, in some applications, such as doorways, vehicle IDs or asset management, a passive RFID system with a much longer read range may be desired. One possible method to achieve a long read range is to replace the electromagnetic techniques now being used with some optical approaches. Perhaps the optical RFID tag (maybe it would be called an OPID tag instead) would have a small flexible photovoltaic array that would serve both as the light signal receiver (extracting data and clock information from the reader) and a means to convert light into electrical power to operate the OPID digital IC chip. As in the existing RFID systems, the OPID tag would respond to a unique signal from the tag reader and when activated, would send information back to the reader, optically. The OPID tag might also have the ability to be reprogrammed without making contact with the device (wireless programming). The distances that such communications could be operate could be measured in 10s of feet or even miles. The only major handicap an optical OPID system would have is that a OPID tag would have to be visually exposed to the reader (line of sight) and could not be hidden behind some light blocking material.
LIGHT TO ELECTRICITY CONVERSION
At sea level, with the sun directly over head, every square foot of a sun illuminated area has about 100 watts of available solar power. For every square inch there is about 0.7 watts available. However, sunlight covers a broad spectrum of wavelengths and methods to convert sunlight power into electrical power are typically only about 10% efficient. The typical device used is a silicon photovoltaic (PV) cell. Such devices are most efficient at about 900 nanometers, which is in the near infrared spectrum. If a silicon PV cell is illuminated with 900nM light, instead of sunlight, a 40% conversion efficiency can be achieved. Most infrared light emitting diodes (LEDs) emit such a wavelength and could be used to send information as well as light power to a distant OPID device. Also, a focused incandescent lamp, such as a tungsten-halogen lamp, could easily produce a one sun condition in the infrared over a long range. Incandescent light is rich in near infrared wavelengths. Xenon and krypton discharge lamps also emit large amounts of near infrared light and can also be modulated at high rates. Standard fluorescent lamps can also be used to produce modulated light. I have been able push some small 5 watt fluorescent lamps into emitting about 10 watts of peak light, while being modulated at 10KHz.
PV CELL CALCULATIONS
If we assume the OPID tag uses a silicon PV array with a small 1/10 inch square area (0.1" X 1.0") and has a 10% conversation efficiency, it would be able to produce about 7 milliwatts of electrical power (3v at 2.3ma), if it were exposed to a one sun light condition. But, a one sun light level may be impractical for some long range OPID systems. If we assume the same PV array were illuminated with light that was equivalent to only 1/50 of one sun, then the available power would be reduced to about 140 microwatts (3v at 50 microamps DC). Still, even with such a weak light power source, 140 microwatts of electrical power could be used to operate a digital OPID IC. For comparison, a typical RFID chip requires about 100 microwatts RMS to operate (2v at 50uA DC).
TAG RETURN SIGNAL GENERATION USING A LIGHT SOURCE
To return a signal from the OPID tag to the tag reader, a modulated light signal could be produced by turning on and off a small infrared LED using short current pulses. One microsecond pulses would be very easy to achieve for most infrared LEDs. The pulses could define the edges of Manchester encoded serial data. Perhaps the data rate could be dependent on the available light power so high data rates would be possible when enough power was available. If we define the minimum data rate at 1000 bits per second, then the pulse rate would be about 2000 pulses per second. The duty cycle (LED on time vs off time) would then be about 1:500 or 0.2%. For a 0.2% duty cycle and an average current of only 20 microamps, the peak LED current could be set at about 10mA. A quality infrared LED would produce about 1mW at such a current. If the tag reader was equipped with a good light collecting device (mirror or lens) such a light power level from the OPID should be detectable over a 10 or 20 foot distance. The LED would emit the light in a cone shaped pattern with a 45 degree half-angle.
TAG RETURN SIGNAL GENERATION USING A LIGHT REFLECTOR
Another method would not emit light at all but would instead use a light shutter to modulate the light striking the OPID device. Some ferroelectric devices, which require low power and behave like liquid crystal displays, could be placed in front of a plastic corner cube type reflective surface. A corner cube reflector has the unique property that it will send light back to the source in a parallel path. Such reflectors are often used on street signs, bicycle reflectors and on reflective clothing. When the ferroelectric device is turned on, light would be allowed to pass through the device and would then bounce off the reflective material, sending the light back to the source. When the ferroelectric device is turned off, light would not reach the reflective material and would therefore be adsorbed. Some ferroelectric devices have been used for high speed video displays so they could allow high data rates. Texas Instruments also has perfected arrays of tiny mirrors that can be moved using electrostatic methods to produce a light modulator. The beauty of the optical reflective method is that the level of light reflected back to a reader would be proportional to the amount of light striking the OPID tag. The approach might allow the tag read range to be extend to 100s of feet or perhaps even several miles.
OPID PROGRAMMING METHODS
To provide a programming (writing) feature from the reader to the tag, a small PIN photo diode could be added to the tag assembly. The PIN photo diode is a faster version of a photovoltaic cell and would convert a modulated light signal into an AC voltage signal. Such devices are used in most TV and VCR remote control receivers. With some optical and electrical filtering, the light detector could be made immune to ambient light changes. Another low speed method may use the photovoltaic array as a modulated light detector to extract clock and data information. Typically, the data rates needed for programming the tag can be much lower than the rates for reading the tag information.
OPID MICRODOTS
When the optical RFID concept is taken to the extreme using a custom IC, it may be possible to produce a tiny passive device that could communicate to the outside world without any antenna, wires, pads or even a package. Covered by a tiny drop of clear epoxy, that provides protection and acts as a lens, the device could be placed on an object and be read by a special OPID reader over a long distance. Perhaps the read head would resemble a light pen type bar code reader. Using light from an infrared laser (a visible red laser might also be used to aid in pointing the light), the reader could supply power to the distant IC and communicate with it. Depending on the size of the OPID's memory, data exchanges ranging from a few hundred bytes to perhaps several megabytes could be possible.
OPTICAL AND RF HYBRID SYSTEMS
Hybrid systems may also work. Modulated infrared light could be used to provide power and information to a tag while the could tag would send information back to the reader using RF techniques. Conversely, it may also be possible to use magnetic excitation to power a tag, but have the tag send information back optically.
FCC REGULATIONS
It should be mentioned that regulating agencies such as the FCC have not yet generated any restrictions for lightwave communications. As long as the devices do not emit harmful light levels, one can pick any wavelength or modulation frequency.

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