- a. High speed cable
- b. Satellite
- c. Dedicated phone
- d. High speed line (e.g., ISDN)
- e. Cellular or PCS
- f. Internet
- g. Radio/radio pulse transmission
- h. High speed optical fiber.
  A video converter/scaler function and a video controller function provided bymodule110 may be utilized in connection with thoseservers100 and associateddisplays30 that require them, according to data transmission practices well known in the art.

Verification that advertisements do, in fact, run at the intended time at the intended displays may be provided by an information storage module (not shown) linked to each display. Another form of verification may be achieved by a Digital Camera andTraffic Count Recorder120 that continuously records the content appearing at itsrespective display30 and digitally transmits video verification information to aVerification Archives module150.Recorder120 also provides traffic count information (for example, 225 vehicles passed the display while an advertisement ran) toverification archives module150.

Information fromverification archives module150 is utilized by ademographic analysis module160 and amarket analysis module170 to generate information for reports to be sent to customers after their advertisements run. To this end, analysis data from

modules

160 and170 is transmitted to a Billing andReport Generation module190 where reports are assembled showing, for example, the time of the advertisement, the content of the advertisement, the traffic count and residence/median income information about those who saw the advertisement. A representative, simplified report for an advertisement running on a single display is as follows:



	Customer: ABC Cola Co.

	Ad Content:	Ocean Scene with graphics
		(content code 1111)
	Location:	Atlanta, Georgia, Interstate
		75N, milepost 125 (site code
		XXXX)

	Time: 7:30 AM, June 30, 2000
	Vehicle Count: 225
	Viewer Count: 340
	Viewer Demographics:

		•	50% Resident Cobb
			County, GA
			Median household
			income: $60,000/yr.
		•	30% Resident DeKalb
			County, GA
			Median household
			income: $52,000/yr.
		•	20% Median household
			income $55,000/yr.

	Advertising Cost:	$X

For an advertisement that may have run at multiple displays, for example 100 displays, a representative report may appear as follows:



	Customer: ABC Cola Co.

	Ad Content:	Mountain Scene with
		graphics (content code 2222)
	Locations:	100 sites (site codes
		YYY . . . ZZZ>

	Time: 8:30 AM, July 10, 2000
	Total Vehicle Count: 21,500
	Total Viewer Count: 37,200

	Viewer Demographics:	Median household
		income, $49,500
	Advertising Cost: $Y

Module

190 also produces bills that may be transmitted by phone lines for a debit payment such as a direct bank draft, or other suitable payment mode.

Referring toFIG. 2, there is shown a pictorial view of one preferred form for the electronic displays30. In this embodiment,display30 takes the form of a 23 feet by 33½ feet seamless flat screen display including multiple flat panel display modules. The panels utilize advanced semiconductor technology to provide high resolution, full color images utilizing light emitting diodes (LED's) with very high optical power (1.5-10 milliwatts or greater) that are aligned in an integrated array with each pixel having a red, green and blue LED. It will be appreciated that multiple LED's of a given color may be used at pixels to produce the desired light output; for example, three 1.5 milliwatt blue LED's may be used to produce a 4.5 milliwatt blue light output. Each red, green and blue emitter is accessed with 24 bit resolution, providing 16.7 million colors for every pixel. An overall display of 23 feet by 33½ feet, so constructed, has a high spatial resolution defined by approximately 172,000 pixels at an optical power that is easily viewable in bright sunlight. Suitable display modules fordisplays30 are manufactured by Lighthouse Technologies of Hong Kong, China, under Model No. LV50 that utilize, for blue and green, InGaN LED's fabricated on single crystalline Al₂O₃(sapphire) substrates and, for red, superbright AlInGaP LED's fabricated on a suitable substrate such as GaP. These panels have a useful life in excess of 50,000 hours, for example, an expected life under the usage contemplated fornetwork20 of 150,000 to 200,000 hours and more. In preferred embodiments, the panels are cooled from the back of the displays, preferably via a refrigerant-based air conditioning system (not shown) such as a forced air system or a thermal convection or conduction system. Non refrigerant-based options may be used in locations where they produce satisfactory cooling. The displays preferably have a very wide viewing angle, for example, 160°.

While the Lighthouse Technologies displays utilize the InGaN on sapphire and AlInGaP on GaP LED's described above, other materials may be used for the LED's as follows:

- 1. (Blue/green) InGaN on SiC, preferably with a suitable buffer layer such as AlN
- 2. (Blue/green) InGaN on GaN
- 3. (Blue/green) InGaN on AlN, preferably with a suitable buffer layer such as AlN.
  It will be appreciated that the InGaN on sapphire and the other solid state LED's described above have substrates with high optical transmissivity and produce very high optical power. This is important for a number of reasons, including giving the electronic display designers the ability to create very wide viewing angles up to approximately 1600, and the resultant increase in visibility of the displays to viewers in oncoming traffic.

In addition to the particular solid state LED's mentioned above, the discrete sources of blue, green and red light at each pixel may take other forms such as composite devices including an ultraviolet LED that is utilized to excite a phosphor that, in turn, produces light of a selected spectrum. The ultraviolet LED may be a GaN on sapphire or GaN on SiC device, preferably with a suitable buffer layer. In one embodiment, ultraviolet LED's are incorporated into three different composite devices, each with a different phosphor for producing blue, green and red, respectively. In another embodiment, a phosphor is selected to produce white light and a desired color is produced by passing the white light through a narrow band pass filter. According to this white-light embodiment, filters of blue, green and red may be used to create discrete composite devices that produce blue, green and red light at each pixel. The use of white light with appropriate narrow band pass filters has the advantage of producing a colored light with an excellent wave length distribution that will not change appreciably over time, a desirable property for color balancing. On the other hand, the use of three different phosphors to directly produce blue, green and red without a filter has the advantage of higher efficiency because light is not filtered out. Both approaches have the advantage of excellent persistence which, as known in the art, is a desirable feature that is especially important in video applications.

It will be appreciated that energy sources other than ultraviolet LED's may be used to excite the phosphors of the composite devices discussed immediately above.

The provision of one or more high resolution, highly aligned digital cameras at each display site, for example the camera or cameras utilized in digital camera andtraffic counter120, or other specifically dedicated cameras, provides a means permitting diagnostics and calibration of the displays. As known in the art, certain digital cameras have a resolution of over 7,000,000 pixels—as compared to approximately 172,000 pixels on the above-described 23×33½ ft. display. Thus, by directing a digital camera at a display, or directing multiple digital cameras at different discrete portions of a display, a correspondence may be attained where a portion of each digital camera's image corresponds to a single pixel in the display. At selected times set aside for diagnostics and calibration, such as a five minute period each night, the entire display may be run red, then green, then blue, followed by white, all at multiple power levels. In the most basic diagnostic operation carried out when the display is run red/green/blue, the camera(s), mounted at a selected distance from the display such as sixty feet away, are capable of detecting nonfunctioning or excessively degraded LED's for replacement.

Beyond replacing defective LED's, each night the system may automatically re-calibrate all LED's in the display. To this end, the display is run red/green/blue at several iterative power levels (e.g., 20%/40%/60%/80%/100%) and the optical power output of each LED is sensed for each power level, with the goal being to calibrate the system so that each red, green or blue LED has the same optical power output at each power level as do the other LED's of the same color. Calibration is achieved by diode recalibration scaler software that may be associated with the video converter/scaler at110 (FIG. 1). The diode recalibration scaler receives information from the diagnostic equipment indicating the optical power output of each LED at the various power levels and, through an associated automatic calibration LED look-up table, accounts for daily variance in LED output (degradation or increase) by adjusting the power curve by which the LED will be driven the next day.

As an alternative to using digital cameras for the diagnostic function, in other embodiments miniature photodector chips, with or without filters, may be located in close proximity to each LED in the display for measuring LED light output during diagnostic/calibration operations.

When the diagnostic operation operates with an all white display, the three LED's at each pixel may be evaluated individually and collectively to assure that the pixel is contributing the proper spectrum and amount of white light. Through a diagnostic/calibration software package that interrelates output and peak wave length response for each red/green/blue LED at a pixel to the desired white light response, an iterative calibration may be undertaken at each pixel to correctly bias the drivers and thereby assure correct output.

It will be appreciated that split screen images may be displayed at thedisplays30. In the simplest application, a still image advertisement may be one half corporate logo and one half scenery. Beyond this simple application, split screen capability may be used to present a portion of the image as a corporate logo, or the like, and the remainder either real time (or near real time) video or still frame. For example, a previously qualified customer with acceptable internal content review procedures may have direct access to a display or displays for the purpose of displaying a real time (or near real time) sports event, news event, or the like, in conjunction with the customer's corporate logo. This display may be achieved by utilizinghigh speed servers100 or by bypassing the servers altogether. High speed still image or video transfer may be facilitated by compression techniques such as JPEG and MPEG II, known in the art.

While advertising scheduling and purchasing may take place as described above where customers directly purchase time from available slots according to a fixed fee schedule, it will be appreciated that alternative modes may be used. For example, an auction system such as introduced by eBay Corporation may be used where all available slots are auctioned (a “total” auction). Additionally, a limited auction may be utilized where time may be purchased and booked for a set price, but all time not purchased at the set price becomes available throughauction20 at a fixed time before the run time, for example, one month before run time. As another alternative for a portion of the available time slots, a high usage customer may establish a monthly advertising budget with the system operator that authorizes the operator to select the time slots for display of the customer's advertisements at “best available rate” pricing, taking advantage of last minute availability of time slots and other time slot placement techniques that enable the operator to more completely utilize the network. This or similar time slot placement practices when used for a portion of the available time slots may be implemented by a software package that takes into account the needs of both the customer and the system operator.

It will be appreciated that advertising content information may be transmitted to the electronic display locations by physically delivering an information storage device such as CD ROM, zip drive or DVD RAM to the location in those cases where the location may be remote, or for other reasons.

While the present invention has been described with reference to specific embodiments, it will be appreciated that modifications may be made without departing from the true spirit and scope, of the invention.