Patent Application
20050077865
The aforementioned U.S. Provisional Application No. 60/497,758 is hereby incorporated by reference in its entirety.
The present invention relates to portable computing devices with a peripheral employing a fuel cell to provide extended operation capability.
Portable electronic data collection and computing devices have become more and more popular for use in a variety of industries. These industries continually demand devices that are more lightweight and energy efficient. A major portion of the weight of portable devices is made up of the batteries that power them.
Three common objectives for the batteries employed in portable electronic devices are to reduce the weight of the batteries (thereby reducing overall product weight), to extend product operation for a given volume or weight of the batteries or other power source, and to provide increased performance and flexibility in recharging the batteries. Typically, batteries achieve increased product operational time by employing battery chemistries that provide higher power density in the same volume. Lithium-Ion chemistry is the current state of the art. Recharging batteries typically requires time (overnight) or expensive circuitry to monitor fast charging. Also, access to other power sources is necessary, usually charging stations powered from wall supplies (docking stations) or vehicular mounted docks. All of these charging devices are generally not directly associated with the product's use, but are a necessary function that is performed at a time least disruptive to the user's tasks. Also, all extra batteries (spares) have to be recharged during this time and usually require their own docking stations.
There are a number of varied battery operated portable products tailored to the needs of particular applications. As these products provide more and more performance, they also become more “power hungry.” There is continual demand for products that provide additional performance in a package that weighs less and lasts for an entire working day.
Fuel cell technology, such as a Direct Methanol Fuel Cell (DMFC), is lighter and has a much higher energy density than the Lithium-Ion chemistry. However, the current level of fuel cell technology does not allow the DMFC to deliver high current pulses on demand, and therefore cannot completely replace batteries in most portable applications.
There is a continuing need in the art to provide improvements in operation time and power density, and to reduce product weight, in portable computing devices.
The present invention is a peripheral device provided for a portable computing device that includes a rechargeable battery, operating circuitry powered by the rechargeable battery, and a fuel cell coupled to provide charging current to the rechargeable battery. Battery charging circuitry is operatively coupled to the rechargeable battery and the fuel cell to control charging of the rechargeable battery by the fuel cell.
Although fuel cell technology, such as a Direct Methanol Fuel Cell (DMFC), is not able to deliver the current necessary to fully operate most portable computing devices, the inventors have devised a system for employing fuel cell technology in portable computing devices that allows an increase in the overall energy density of the power system of the device. The inventive system is based on the fact that for many portable computing devices, certain peripherals or sub-systems employed with the device (or occasionally the device itself) require high peak current for short periods only, with rest time between those periods. Many of these types of products operate on a relatively light duty cycle, such as 10 minutes “ON” and 30 minutes “OFF.” These peripherals or sub-systems can use a much smaller battery to supply the high peak current if it can be recharged during those rest periods. A fuel cell is able to provide sufficient current for battery charging in this manner. The introduction of a small, lightweight fuel cell and reduced battery size allows the overall size of the portable device to be decreased. The need to carry spare batteries is greatly reduced, and recharging of the fuel cell is immediate by filling the cell with more methanol. The fuel cell itself requires essentially no recharging time. Its operation is similar to an automobile engine and its gas tank; the fuel cell can simply be filled with fuel and it is ready to operate. The methanol that runs the fuel cell is lighter and has much more energy per unit volume and weight than current battery technologies.
As shown in
In operation, portable computer terminal 12 is operated by a user for a particular application. In the course of this operation, peripheral device 10 is employed. Structurally, peripheral device 10 may take any number of forms. In an exemplary embodiment, peripheral device 10 is an RFID device configured as a handle, as shown in
Peripheral device 10 is powered by battery 32, which delivers operating current to DC/DC boost regulator 34 in order to provide power to status circuitry 36 and serial PC card 42. Conventionally, battery 32 is rechargeable by connecting device 10 to external charger/dock 50, which provides recharging current to charge circuit DC/DC buck regulator 30 in order to charge battery 32. However, in accordance with the present invention, battery 32 may instead or additionally be charged by a current delivered from fuel cell 20, which may be removably located internal to peripheral device 10 in an exemplary embodiment. Fuel cell 20 includes charging and processing circuitry (not shown) that allows it to properly operate to charge battery 32, and also to communicate with serial PC card 42 to provide status information and the like. This information may be displayed by status LEDs 46 or by the connected portable computer terminal 10 in an exemplary embodiment.
There are a number of advantages to providing on-board battery charging of peripheral device 10 with fuel cell 20. Peripheral device 10, for a given weight (which is affected by the size of battery 32), can be operated for a longer period of time. Charging time between uses is also dramatically reduced, since replentishment of fuel cell 20 can be done very quickly by adding more fuel to the cell. The need for spare battery packs, previously required because of the inability of the battery to provide power for a full shift of work, can be eliminated due to the ability of fuel cell 30 to charge battery 32 during the shift in real time, while the peripheral device is not actively drawing current. The elimination of spare battery packs further reduces the overall weight that needs to be carried by a user.
Peripheral device 10 has been shown as an RFID peripheral, because of this particular peripheral's need for its own battery to provide sufficient power for operation (the battery of portable computer terminal 12 cannot provide sufficient power without significantly degrading its battery life). In other embodiments, peripheral device 10 may perform other functions, such as optical scanning, radio frequency communication (such as by a Bluetooth or other type of transceiver), or any other of a number of desirable peripheral functions known in the art. Peripheral device 10 may also utilize fuel cell 20 to at least partially recharge the battery of portable computer terminal 12, through an appropriate physical interface (not shown in
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
This application claims the benefit of U.S. Provisional Application No. 60/497,758 filed Aug. 26, 2003 for “Extended Operation of Portable Battery Operated Intermittent Duty Cycle High Power Devices Using Fuel Cell Technology” by D. Durbin, T. Schuster and B. McDermott.
| Number | Date | Country | |
|---|---|---|---|
| 60497758 | Aug 2003 | US |
