Inventor:

Bharat Anadure

RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 61/412,949, filed November 12, 2010 which is herein incorporated by reference in its entirety for all purposes.

FIELD OF THE INVENTION

[0002] The invention relates to electronic display systems, and more particularly, to on-vehicle electronic display systems.

BACKGROUND OF THE INVENTION

[0003] Vehicles are often used for displaying information of interest to the general public, since the mobility of a vehicle enables it to display information to a wider range of viewers than a sign or bulletin board that is fixed in location.

[0004] In particular, commercial vehicles are frequently used to display information to the general public, such as advertisements and public service announcements. Operators of commercial vehicles are typically glad to obtain an additional revenue stream, and in some cases commercial operators may also see an added advantage in drawing added attention to their vehicles.

[0005] As an alternative to printed signs, electronic displays are sometimes used to present information to the public. For example, building-mounted electronic displays and electronic highway billboards are becoming common, since they can display a plurality of messages to a passing motorist, as compared to a conventional printed sign or billboard which can typically present only a single message. [0006] Electronic displays are sometimes used to display advertisements and public service announcements on vehicles. This approach not only enables the display of a plurality of messages, but also provides opportunities which are unique to a moving platform, such as the ability to display location-relevant information. A bus, for example, might include an electronic display panel on its side which is controlled by a location-aware system (e.g. a system which includes a GPS), and might thereby be able to present advertisements for nearby

restaurants, the advertisements being automatically updated as the bus travels its route so as to always correspond to a restaurant which is nearby.

[0007] However, the implementation of electronic displays on vehicles is problematic, due to the energy required to operate the display, especially during daylight hours when the ambient light level is high. The vehicle electrical system can be used to power the display, but this increases the load on the vehicle's alternator, thereby reducing the energy efficiency of the vehicle and increasing its operating cost.

[0008] A battery can be used to supply power to an electronic display on a vehicle, the battery being charged while the vehicle is not in use. However, a very large battery is typically needed to supply the power requirements of a display mounted on a vehicle which is used for long periods of time, especially if the vehicle is operated during daylight hours. Such very large batteries are typically expensive, and the weight of such batteries can significantly reduce the efficiency of the vehicle and increase its operating cost.

[0009] Solar panels mounted on a vehicle can sometimes be used to supply energy to a vehicle-mounted electronic display. For a very large vehicle, such as a bus or train, it may be possible in some cases to locate sufficiently large solar panels on top of the vehicle to fully supply the electrical needs of a display during the day, while also re-charging a battery which can then be used to power the display at night. Also, a bus or a train may have so much mass that the addition of even a large battery has a negligible effect on the operating efficiency of the vehicle.

[0010] However, implementation of electronic displays on smaller vehicles such as taxi cabs is much more difficult. The weight of a large battery will impact the efficiency of a taxi much more significantly than a bus or a train, since a taxi is smaller and lighter. Also, the electrical system of a small vehicle such as a taxi cab typically has less capacity than the electrical system of a bus or a train.

Therefore, the added load of an electronic display will have a much greater impact on the fuel efficiency of a taxi cab than on a bus or a train. For example, a typical HD (1920 x 480 pixel resolution) LED display on a taxi including two panels each measuring about 40 inches by 20 inches, more than 500 Watts can be required to provide satisfactory brightness during daylight. Drawing this much power from the electrical system of a taxi can significantly increase its operating cost, and may push the electrical system beyond its operating limits, possibly even causing the alternator to fail.

[0011] Solar panels can be added to a small vehicle such as a taxi cab so as to provide some energy for an electronic display. However, there is less space available on a taxi for locating solar panels, as compared to a bus or a train, and so it is difficult for solar panels on a taxi to generate sufficient solar power to supply the needs of an electronic display of desirable size and brightness. And, of course, solar panels cannot provide energy at night.

[0012] What is needed, therefore, is a system for supplying energy to an on- vehicle electronic display on a smaller vehicle such as a taxi cab, whereby the display can be operated with satisfactory brightness and resolution during all ambient light conditions without unduly increasing the operating cost of the vehicle, and without overtaxing the electrical system of the vehicle. SUMMARY OF THE INVENTION

[0013] A solar-assisted on-vehicle electronic display system which is suitable for use on a small vehicle such as a taxi cab includes a power and brightness controller which automatically adjusts the brightness of the display according to the ambient light level and the available solar power, thereby ensuring that an acceptable brightness is provided under all ambient light conditions while the energy load on the vehicle electrical system remains within acceptable limits. The power and brightness controller combines energy from the vehicle electrical system with energy from vehicle-mounted solar panels so as to provide increased display brightness during daylight hours, when solar energy is available and maximum brightness is required, while automatically dimming the display to an acceptable brightness for nighttime use, when solar energy is not available.

[0014] In certain embodiments, the power supplied by the vehicle electrical system is limited to no more than 300 Watts, which is sufficient for night illumination of a display which includes two HD 1080p (1920 x 480 pixel) resolution Led panels with dimensions of about approximately 43 inches by 28 inches. In some of these embodiments, solar panels having a total area of about approximately 50 inches by 30 inches provide additional power up to about approximately 300 Watts, which is sufficient for daytime illumination of the display. In various embodiments, a fixed amount of power, such as 300 Watts, is drawn from the vehicle electrical system under all ambient light conditions, and electrical power from the solar panels is added to this amount when and to the degree that it is available, thereby automatically increasing the brightness of the display as the ambient light level increases and the power output of the solar panels is proportionately increased.

[0015] In some embodiments, a rechargeable battery is included for storing unused or surplus solar energy for later use. For example, some embodiments intended for use by a taxi which operates mainly at night include a battery which can be charged during the day when the taxi and the vehicle are not in operation, and then used to reduce the amount of power supplied by the vehicle electrical system during nighttime hours of operation. In some of these embodiments, the rechargeable battery can also be recharged from a conventional power source such as a wall outlet when the vehicle is not in operation.

[0016] The present invention includes a vehicle-mounted electronic display, at least one vehicle-mounted solar panel, a display controller, and a power and brightness controller. Various embodiments include a rechargeable display battery. In some embodiments, the display controller is in wireless

communication with a content controller that supplies and updates the information to be displayed. In some embodiments, the display controller is location aware, due to an included GPS or by other means known in the art, and is able to cause the electronic display to present information which is location relevant.

[0017] One general aspect of the present invention is a solar-assisted on- vehicle electronic display system that includes an electronic display which is mountable to an exterior of a vehicle, at least one solar panel which is mountable to the exterior of the vehicle, a display controller at least in electronic

communication with the electronic display, and a power and brightness controller in power communication with the electronic display, with the at least one solar panel, and with a vehicle electrical system, where the power and brightness controller are able to determine an ambient light level and a desired display brightness, and the power and brightness controller are able to combine power supplied by the at least one solar panel and by the vehicle electrical system so as to provide to the electronic display sufficient power to achieve a brightness which is as close as possible to the desired display brightness without requiring the vehicle electrical system to supply more than a maximum vehicle power Vmax, where Vmax is selected so as to ensure that the vehicle electrical system does not exceed its maximum capacity.

[0018] Various embodiments further include a rechargeable display battery in power communication with the power and brightness controller, the power and brightness controller being able to combine power supplied by the display battery with power supplied by the at least one solar panel and power supplied by the vehicle electrical system. In some of these embodiments the rechargeable display battery can be recharged using power derived from the at least one solar panel. In other of these embodiments the rechargeable display battery can be recharged using power from a conventional power outlet.

[0019] In certain embodiments the power and brightness controller is able to estimate the ambient light level from an amount of power supplied by the at least one solar panel.

[0020] Various embodiments further include an ambient light sensor in communication with the power and brightness controller, the ambient light sensor being able to sense the ambient light level.

[0021] In some embodiments the display controller is in wireless

communication with a content manager which supplies content to be displayed on the electronic display.

[0022] In certain embodiments the display controller is location aware, and is able to select content to be displayed by the electronic display according to a current location of the vehicle. And some of these embodiments further include a global positioning system (GPS), the GPS being accessible by the display controller so as to determine the current location of the vehicle.

[0023] In various embodiments the display resolution is full HD 1080p (1920 by 480 pixels). In some embodiments the display includes two LED panels, each having dimensions of about approximately 43 inches by 18 inches.

[0024] In other embodiments Vmax is 300 Watts. In certain embodiments the total surface dimensions of the at least one solar panel are about approximately 50 inches by 30 inches. And in some embodiments the at least one solar panel has a total maximum power output capacity of between 250 Watts and 300 Watts. [0025] Another general aspect of the present invention is a method for automatically controlling a brightness of an electronic display mounted on a vehicle, and for combining power from at least one solar panel with power from an electrical system of the vehicle so as to provide power to the electronic display, while ensuring that the power drawn from the vehicle electrical system does not exceed an acceptable maximum Vmax. The method includes estimating an ambient light level, determining a desired display brightness according to the ambient light level, determining a desired display power required to provide the desired display brightness, combining available solar power with power from the vehicle electrical system so as to obtain a total power which is as close as possible to the desired display power without allowing the power from the vehicle electrical system to exceed Vmax, and supplying the total power to the display.

[0026] The features and advantages described herein are not all-inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims.

Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and not to limit the scope of the inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1A is a side view of a taxi cab equipped with an embodiment of the present invention;

[0028] Figure I B is a top view of the taxi cab and embodiment of Figure 1A;

[0029] Figure 2 is a block diagram of an embodiment of the present invention;

[0030] Figure 3 is a flow diagram which illustrates the operation of a power and brightness controller of an embodiment of the invention;

[0031] Figure 4 is a side view of the taxi cab of Figure 1A operating at night with reduced display brightness; [0032] Figure 5 is a side view of the taxi cab of Figure 1A operating during the day with increased display brightness; and

[0033] Figure 6 is a side view of a taxi cab equipped with an embodiment of the present invention which includes a rechargeable display battery, the taxi cab being shown during recharging of the battery from a conventional wall electrical outlet while the taxi is not in use.

DETAILED DESCRIPTION

[0034] With reference to Figure 1A, the present invention is a solar-assisted on-vehicle electronic display system which is suitable for use on a small vehicle such as a taxi cab 100. The invention includes a power and brightness controller which combines energy from the vehicle electrical system with energy from vehicle-mounted solar panels 102 so as to provide increased display brightness during daylight hours, when solar energy is available and maximum brightness is required, while automatically dimming the display 104 to an acceptable brightness for nighttime use, when solar energy is not available. The present invention thereby ensures that an acceptable display brightness is provided under all ambient light conditions, while the energy load on the vehicle electrical system remains within acceptable limits. Figure IB is a top view of the embodiment of Figure 1A.

[0035] In the embodiment of Figure 1A and Figure IB, the display 104 includes two full HD 1080p (1920 by 480 pixel) resolution panels with dimensions of about approximately 43 inches by 18 inches each. Power drawn from the vehicle electrical system is limited to no more than 300 Watts, while additional power is obtained as needed from solar panels 102 which supply power in proportion to the ambient light level, the solar panels 102 having a total surface area of

approximately 50 inches by 30 inches and being able to supply up to 250 to 300 Watts in full daylight conditions.

[0036] Figure 2 is a block diagram of an embodiment of the present invention. The embodiment includes a power and brightness controller 200 to which power is supplied by both the vehicle electrical system 202 (typically a vehicle alternator and battery) and by solar panels 102 mounted typically on the roof of the vehicle 100. The power and brightness controller includes power control logic which enables it to select a combination of solar and vehicle electrical system power that will provide acceptable brightness of the display 204 under all ambient light conditions while drawing an amount of power from the vehicle electrical system 202 that will not exceed the capacity of the vehicle electrical system 202 and will not unduly increase the cost of operating the vehicle 100.

[0037] The present invention recognizes that the required brightness for an on- vehicle electronic display 104 varies according to the ambient light level, such that the display 104 must be brighter under bright (e.g. daylight) conditions, and can be dimmer under darker (e.g. nighttime) conditions. The invention further recognizes that the power available from a solar panel 102 also varies according to the ambient light level, so that this additional power source is available exactly when and to the extent that it is needed.

[0038] The amount of power supplied by the solar panels 102 is a direct indication of the ambient light level, and is used by the power and brightness controller 200 in some embodiments to determine the acceptable brightness level, and hence the required power to be delivered to the display 104. In other embodiments, a separate ambient light sensor 204 is included for determining the ambient light level, and hence the required brightness and display power.

[0039] The embodiment of Figure 2 further includes a display controller 206 that supplies the information which is to be displayed by the on-vehicle electronic display 104. In the embodiment of Figure 2, the display controller 206 is in wireless communication with a content controller (not shown) which supplies and updates the information to be presented by the electronic display 104. The embodiment of Figure 2 also includes a GPS (208) which enables the display controller 206 to be location aware. The display controller 206 can be wirelessly pre-loaded with a plurality of advertisements and/or other messages having relevance to various locations, and can be programmed to display only location relevant information as the taxi 100 travels from one location to another. For example, if advertisements for restaurants are to be displayed, the display controller 206 can be programmed to display only advertisements for restaurants that are located within five miles of the current location of the taxi 100.

[0040] The embodiment of Figure 2 also includes a rechargeable display battery 210 that can be charged when excess solar energy is available, for example when the taxi 100 is exposed to sunlight and the display 104 is not in use. The battery 210 can also be charged by connection to a standard electrical outlet, for example while the taxi 100 is parked in a garage or at another location with access to an electrical outlet (see Figure 5, discussed in more detail below).

[0041] Figure 3 is a flow diagram that illustrates the operation of power and brightness controllers 200 in embodiments of the present invention. The power and brightness manager 200 senses the ambient light level 300, either by directly monitoring the power output of the solar panels 102 or by using a separate light sensor 204. If the ambient light is very strong 302, then it may be possible to achieve maximum brightness Bmax of the display 104 by using mainly solar power, and only a small amount of power (if any) from the vehicle electrical system 304. It may even be possible to use excess solar power to charge the display battery 210.

[0042] On the other hand, if the ambient light is weak, for example at night 306, then less display brightness will be needed, and the power and brightness controller 200 will dim the display at least until the power supplied by the vehicle electrical system is below a maximum value Vmax 308. In some embodiments, Vmax = 300 Watts. If neither extreme is present, then the power control logic of the power and brightness controller 200 will determine an appropriate level of display brightness, and will provide a corresponding amount of combined solar and vehicle power to the display 104. In some embodiments, the full amount of available solar power is supplied, and only enough vehicle system power is added to achieve the desired brightness level of the display 104. In other embodiments, a fixed amount of power, such as 300 Watts, is supplied by the vehicle electrical system, and any available solar power is simply added to this fixed amount so as to automatically increase the brightness of the display 102 as the ambient light level increases.

Figure 4A illustrates an embodiment of the present invention operating at night, with a relatively dimly illuminated display powered only by the vehicle electrical system, the power being nevertheless sufficient for the display to be easily seen in the low ambient light environment. Figure 4B illustrates the embodiment of Figure 4A operating during the day, with a much more brightly illuminated display powered by both the vehicle electrical display and by the solar panels 102 mounted on the roof of the taxi 100.

Figure 5 illustrates an embodiment of the present invention that includes a rechargeable display battery (210 in Figure 2). The taxi 100 is parked in its garage during a period of non-use, and the display battery is being charged using power supplied by a power cord 500 connected to a conventional wall electrical outlet 502.

[0043] The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of this disclosure. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.