Patent Application
20100123550
Many modern mobile devices use radio-frequency identification (“RFID”) transceivers for wireless communication for various purposes. Like other types of wireless transceivers, RFID transceivers are typically connected to an antenna for transmitting and receiving signals. For optimal performance, the cable used to connect an RFID transceiver to its corresponding antenna should be as short as possible.
The present invention relates to a device comprises an RFID transceiver disposed on a first side of a printed circuit board; an antenna disposed on a second side of the printed circuit board; and a cable passing through the printed circuit board, a first end of the cable being connected to the RFID transceiver, a second end of the cable being connected to the antenna.
The exemplary embodiments of the present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The exemplary embodiments describe mobile devices that minimize cable length and improve transceiver performance by routing a cable through a printed circuit board.
RFID is used by many mobile devices for various purposes, including identification, short-range communication, security/authentication, tracking/location, etc. An RFID subsystem may include an RFID transceiver (also referred to as a “tag”), an antenna to transmit and receive signals, a power source (e.g., a battery) for providing power to the transceiver, and a cable or series of cables for connecting the transceiver to the antenna. The cable may be, for example, a coaxial cable.
Mobile devices that employ RFID communication and include the above components, like most electronic devices, are typically built using one or more printed circuit boards (“PCB”). A PCB is used to support and electrically connect various components using conductive pathways etched into a non-conductive substrate. The PCB may be fixed with respect to a casing of a device, and other components may be fixed with respect to the PCB.
Because space is limited in mobile devices, components of a certain size or type may need to be located in a particular position within the device. For example, an antenna may be located near the exterior of a device in order to improve performance. Further, because of these space concerns, components that must be electrically coupled to one another may not necessarily be able to be located in close physical proximity to one another. In some situations, these spatial concerns may lead to electrically connected components being disposed on opposite sides of a PCB from one another. Commonly, these components may be the RFID transceiver and its corresponding antenna, as discussed above. Despite such placement remotely from one another, the cable used to connect a transceiver and its corresponding antenna is preferably as short as possible in order to prevent signal degradation.
Previously, such components have been electrically coupled to one another in one of two ways. In the first, a hole may be placed in the PCB and the cable may be routed through the hole. Alternately, the cable may be wrapped around the edge of the PCB. However, both of these methods have disadvantages. First, in either case, the cable must be tied down and contained with precision. If the cable position varies from one product to the next, the performance may vary correspondingly, such as due to interference from nearby components; such variability is undesirable. Second, placing a hole in the PCB adds complexity to the manufacturing process. Third, wrapping the cable around the PCB requires a longer cable, which is undesirable as described above.
The exemplary embodiments described herein thus avoid these issues by using a connection to send the signal through the PCB.
The device 100 includes a power source 130 (e.g., a disposable or rechargeable battery, line power, etc.) supplying power to the RFID transceiver 120 and other components of the device 100. The power source 130 may be physically mounted to the PCB 110 or located elsewhere, but electrical connections to the power source 130 are typically accomplished via the PCB 110. The device 100 further includes a signal source 140 (e.g., a processor, etc.) that may handle data communications with the RFID transceiver 120; those of skill in the art will understand that the signal source 140 may also perform other tasks. As for the power source 130, the signal source 140 may be attached to the PCB 110 or located elsewhere, but its electrical connections are accomplished via the PCB 110.
The RFID transceiver 120 accomplishes its wireless communication by means of an antenna 150. The antenna 150 may be of any type suitable for performing this communication. The RFID transceiver 120 is connected to the antenna 150 by means of an antenna cable assembly 160, which will be discussed in more detail below. The antenna cable assembly 160 is typically a coaxial cable including an inner conductor for carrying a signal and an outer conductor for providing electromagnetic shielding, separated from one another by an insulating layer. With the exception of the antenna 150, all components of the device 100 are typically located within a housing 170; the antenna may optionally be located outside the housing, partially within and partially without, or be integrated with the housing.
The center pin 162 is shielded by an outer shell 164 in the manner described above with reference to the outer conductor of a typical coaxial cable. The outer shell 164 is mounted in a plated hole in the PCB 110, preferably by soldering, and is thus grounded and shields the signal in the center pin 162. In one exemplary embodiment, the outer shell 164 may be a MIL-STD-348A plug; in another, it may be a 50 ohm U.FL connector. The center lead 161 and the center pin 162 are separated from the outer shell by insulators 165 and 166, which may be made from plastic or any other suitable insulating material. In other embodiments, insulators 165 and 166 may be formed as a single part. The insulator 166 joins the insulator (not shown) of the coaxial cable assembly 163, insuring full signal isolation. It should be noted that the illustration of the coaxial cable assembly 163 in
Thus, in the above-described exemplary embodiments, the antenna cable is restrained in a fixed position in order to achieve constant, predictable performance. Further, the length of cable required to connect a transceiver on one side of a PCB to an antenna on the other side may be minimized. Additionally, the cable may be shielded from interference while it passes through the PCB.
It will be apparent to those skilled in the art that various modifications may be made in the present invention, without departing from the spirit or the scope of the invention. Thus, it is intended that the present invention cover modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
