Personal navigation device with improved antenna mounting configuration

A personal navigation device includes a GPS receiver for receiving GPS signals from a plurality of GPS satellites; a processing system coupled with the GPS receiver for determining a location of the personal navigation device as a function of the GPS signals; a display coupled with the processing system for displaying information related to the location of the personal navigation device; a housing on which the display is mounted and in which the GPS receiver and processing system are housed; and an antenna coupled with the GPS receiver for assisting in reception of the GPS signals. The antenna is fixedly positioned along a plane that is generally parallel with a plane passing through the housing.

BACKGROUND

The present invention relates to portable electronic devices such as personal navigation devices and the like. More particularly, the invention relates to an improved antenna and antenna mounting configuration for personal navigation devices.

2. Description of the Related Art

Global Positioning System (GPS) enabled portable electronic devices such as personal navigation devices (PND), personal data assistants (PDA), mobile telephones, handheld GPS/radios, and the like, are typically equipped with antennas for receiving signals from satellites in a GPS system. These antennas are typically rigidly mounted to external surfaces of the devices or hingedly mounted so they can be extended while the devices are in use and retracted when not in use. Unfortunately, such antenna mounting configurations increase the overall size and detract from the appearance of the portable electronic devices.

SUMMARY

The present invention is directed to a portable electronic device such as a personal navigation device with an improved antenna and antenna mounting configuration. The personal navigation device includes a GPS receiver for receiving GPS signals from a plurality of GPS satellites. A processing system is coupled with the GPS receiver for determining a location of the personal navigation device as a function of the GPS signals. A display is coupled with the processing system for displaying information related to the location of the personal navigation device. A housing, on which the display is mounted, houses the GPS receiver and processing system. An antenna coupled with the GPS receiver for assisting in reception of the GPS signals. The antenna is fixedly positioned along a plane that is generally parallel with a plane passing through the housing. In exemplary embodiments, the personal navigation device includes a circuit board on which the GPS receiver and the processing system are mounted. The antenna is mounted to the circuit board and is entirely enclosed within the housing. In embodiments of the invention, the antenna is positioned entirely within an outer perimeter edge of the circuit board. A ground plane may be provided between the antenna and the circuit board. The antenna is mounted at least partially over the ground plane so that the antenna is positioned along a plane that is generally parallel with the circuit board. In a specific embodiment, a shield fence is attached to the circuit board. The ground plane is positioned at least partially over the shield fence. By mounting the antenna in accordance with the present invention, the housing of the personal navigation device can be made thinner without compromising signal receptivity.

DETAILED DESCRIPTION

Referring generally toFIGS. 1 through 10, a personal navigation device10in accordance with an exemplary embodiment of the present invention is described. As shown inFIGS. 1,2,9and10, the personal navigation device10includes a processing system12, a location determining component14, an antenna assembly16for the location determining component, a display18, one or more input devices20, a housing22which encloses and protects the other components from moisture, vibration, and impact, and other components described below. As explained in more detail herein, the antenna assembly16is configured and strategically mounted and positioned to optimize reception of external radio frequency signals while minimizing the overall size of the device10and eliminating protrusions from the housing22of the device10.

The processing system12may include any number of processors, controllers, or other processing systems and resident or external memory for storing data and other information accessed and/or generated by the device10. The processing system12implements one or more software programs which control the display of information on the display18and input of information via the one or more input devices20.

In exemplary embodiments, the location determining component14comprises a global positioning system (GPS) receiver or any other device which can determine locations of the marine vessel in which the device10is used. In general, the global positioning system (GPS) is a satellite-based radio navigation system capable of determining continuous position, velocity, time, and direction information for an unlimited number of users.FIG. 3shows one representative view of a GPS denoted generally by reference numeral23. A plurality of satellites24are in orbit about the Earth26. The orbit of each satellite is not necessarily synchronous with the orbits of other satellites and, in fact, is likely asynchronous. A GPS receiver device10such as the ones described in connection with preferred embodiments of the present invention is shown receiving spread spectrum GPS satellite signals from the various satellites24. The spread spectrum signals continuously transmitted from each satellite24utilize a highly accurate frequency standard accomplished with an extremely accurate atomic clock. Each satellite24, as part of its data signal transmission, transmits a data stream indicative of that particular satellite. The device10must acquire spread spectrum GPS satellite signals from at least three satellites for the GPS receiver device to calculate its two-dimensional position by triangulation.

The location determining component14is operable to receive navigational signals from the GPS satellites24to calculate a position of the device10as a function of the signals. The location determining component14is also operable to calculate a route to a desired location, provide instructions to navigate to the desired location, display maps and other information on the display screen, and to execute other functions described herein.

The location determining component14may include one or more processors, controllers, or other processing systems and memory or may utilize the components of the processing system12. The memory of the processing system12and/or the location determining component14may store cartographic data and routing used by or generated by the location determining component14. The memory may be integral with the location determining component14, integral with the processing system12, stand-alone memory, or a combination of both. The memory may include, for example, removable and non-removable memory elements such as RAM, ROM, flash (including microSD cards or the like), magnetic, optical, USB memory devices, and/or other conventional memory elements.

The processing system12and the location determining component14may be mounted to a printed circuit board28in a conventional manner as depicted inFIGS. 4 through 7. In the embodiment illustrated, the circuit board is made of conventional materials and is sized to support all the components of the processing system12, location determining component14, and other electronics of the device10.

The display18is coupled with the processing system12and the location determining component14for displaying data and information as described herein. The display18may comprise an LCD (Liquid Crystal Diode), TFT (Thin Film Transistor) LCD, CRT (Cathode Ray Tube), LEP (Light Emitting Polymer or PLED (Polymer Light Emitting Diode), or the like, capable of displaying both text and graphical information. The display may be backlit such that it may be viewed in the dark or other low-light environments. As illustrated inFIGS. 1,9and10, the display18is preferably positioned on a front face of the housing22for ease of viewing.

The input devices20may also be positioned on the front surface of the housing22such that they may be easily accessed. The input devices20may include descriptive markings that identify their function. The inputs may be buttons, switches, keys, an electronic touch-screen associated with the display, voice recognition circuitry, or any other elements capable of controlling the processing system and location determining component.

The housing22may be constructed from a suitable lightweight and impact-resistant material such as, for example, plastic, nylon, aluminum, or any combination thereof. The housing may include a front portion22aand a rear portion22band may include one or more appropriate gaskets or seals to make it substantially waterproof or resistant. The housing22may also include a location for a rechargeable battery or other power source. The housing may take any suitable shape or size, and the particular size, weight and configuration of the housing may be changed without departing from the scope of the present invention.

As best illustrated inFIGS. 4 through 8and10, the antenna assembly16includes an antenna30and a ground plane32, and may include one or more shield fences (two shield fences34aand34bare illustrated), mounted to the circuit board28. In exemplary embodiments, the antenna30may be a patch-type antenna such as those made by Inpaq Technology Co., Ltd. The patch antenna may be approximately square in shape and generally planar in construction having a thickness less than its length or width. In one specific embodiment, the patch antenna30is approximately 25 mm×25 mm square and 4 mm thick, but it may be formed in other sizes and shapes without departing from the scope of the present invention. Ideally, however, the patch antenna30is no thicker than about 8 mm. The patch antenna30may include a small diameter hole36near its center. One embodiment of the patch antenna has an output impedance of approximately 50 ohm and a center frequency of 1575.42 MHz.

The ground plane32comprises a generally flat metal surface surrounding the antenna30for deflecting errant signals (i.e., multipath) reflected from the ground and other near-by objects. In exemplary embodiment, the ground plane32may be formed of approximately 0.2 mm to 0.3 mm thick cold rolled steel with a tin pre-plated coating and is approximately 50 mm×50 mm square. However, the ground plane32may be made of other materials and formed in the other sizes and shapes without departing from the scope of the present invention. In the embodiment illustrated, the ground plane32is formed with several perimeter notches.

The shield fences34aand34bhelp to shield the antenna30and ground plane32from the circuit board28from electromagnetic fields. In one embodiment, the shield fences34aand34bare also made of approximately 0.2 mm to 0.3 mm thick cold rolled steel with a tin pre-plated coating. In the specific embodiment illustrated inFIGS. 4 and 5, one of the shield fences34bis approximately 20 mm×15 mm and approximately 1.75 mm tall, while the other34ais approximately 29×34 mm and approximately 1.75 mm tall. However, the shield fences34aand34bmay be made of other materials and formed in other sizes and shapes without departing from the scope of the present invention. Moreover, only one shield fence or three or more shield fences may be used rather than two. Further, in exemplary embodiments, the shield fences34aand34bmay be eliminated altogether.

In the embodiment illustrated, the antenna assembly16is mounted to the circuit board28by first attaching the two shield fences34aand34bto one face of the circuit board28as best illustrated inFIGS. 7,8and10. The shield fences34aand34bmay be attached to the circuit board28using a suitable fastening technique, such as by adhesives, soldering, or the like. The ground plane32is then snapped onto the shield fences34aand34bor otherwise secured using a suitable fastening technique, such as by adhesives, soldering, or the like. In embodiments wherein no shield fences34aand34bare provided, the ground plane32may be mounted to the circuit board28, antenna30, housing22, or like component of the personal navigation device10

The patch antenna30is secured to the exterior face of the ground plane32as illustrated. In exemplary embodiments, one face of the patch antenna30may be provided with a self-adhesive backing with a release layer. The release layer may be removed to expose the adhesive to secure the patch antenna30to the ground plane32. A conductive post or pin38may then be inserted into the small diameter hole36in the patch antenna30and pushed through the circuit board28so that its distal end40extends from the face of the circuit board opposite the antenna assembly. The distal end40of the post or pin38may then be coupled with the GPS receiver or other location determining component of the device to transfer signals there between.

As best illustrated inFIGS. 1,4,5,9and10, the patch antenna30is entirely enclosed within the housing22. In a specific embodiment, best illustrated inFIGS. 4,5and6, the antenna30is positioned entirely within the outer perimeter edge of the circuit board28(i.e., so that the antenna30does not extend beyond an outer perimeter edge of the circuit board28in any direction). Likewise, the ground plane32is positioned entirely within the outer perimeter edge of the circuit board28(i.e., so that the ground plane32does not extend beyond an outer perimeter edge of the circuit board28in any direction). Thus, no part of the patch antenna30or the antenna assembly16extends beyond the outer confines of the housing.

As also illustrated, the patch antenna30is positioned along a plane identified by P1inFIGS. 4 and 5. More specifically, the patch antenna30is positioned so that its surfaces are generally parallel to or co-planar with plane P1and its edges are generally perpendicular to plane P1. Similarly, the housing22and the display18are positioned along a second plane identified by P2. Thus, as illustrated, plane P2may be generally parallel to or coplanar with a front surface of the housing and/or the surface of the display18and generally perpendicular to the side or edge surfaces of the housing22(in embodiments of the device10where the edge surfaces of the housing22are generally perpendicular to the from or rear surfaces of the housing). In specific embodiments, the plane P2may further/or alternatively be parallel with the rear surface of the housing22. Likewise, the circuit board28is positioned along a third plane identified by P3so that one or both surfaces of the circuit board28are parallel to or coplanar with plane P3.

In one embodiment, the plane P1along which the antenna30is positioned is generally parallel to the plane P2which passes through the housing22. In another embodiment, the plane P1is generally parallel to the plane P3along which the circuit board is positioned. In a specific embodiment, the plane P1is parallel to both the planes P2and P3. Thus, in exemplary embodiments, the antenna30may be positioned so that its surfaces are generally parallel to the circuit board, the front and/or rear surfaces of the housing22, and/or the surface of the display. As used herein, “generally parallel” and “generally perpendicular” are understood to encompass some deviations from parallel or perpendicular caused by manufacturing tolerances, normal shifting and re-positioning of components during use, and other similar causes.

By configuring and mounting the antenna assembly16as described herein, reception of GPS signals is optimized while minimizing the overall size of the device10and eliminating protrusions from the housing22. For example, by mounting the antenna30to a circuit board28which is positioned entirely within the housing, the personal navigation device10has no antenna protruding from its housing22. In this manner, the housing may be made more esthetically pleasing (e.g., thinner, sleeker, etc.) than prior art devices which have antennas mounted on exterior surfaces of their housings. Also, by mounting the antenna30so that it is generally parallel with the housing22, the display18, and the circuit board28, the housing22can be made thinner than known personal navigation devices in which the antennas are positioned generally perpendicular to their housings when the devices are in use, thus necessitating thicker housings and/or flip-type antennas.

In an exemplary embodiment illustrated, the invention is implemented with a personal navigation device10such as the one illustrated inFIG. 1. However, embodiments of the present invention can be implemented in various portable electronic devices. The personal navigation device10and its components illustrated and described herein are merely examples of a device and components that may be used to implement the embodiments of the present invention and may be replaced with other devices and components without departing from the scope of the invention.

The device10may also include other components not specifically described but necessary or desirable for its function. For example, the device10may include a speaker for providing audible instructions and feedback, a microphone for receiving voice commands, an infrared port for wirelessly receiving and transmitting data and other information from and to nearby electronics, and other information, and even a cellular or other radio transceiver for wirelessly receiving and transmitting data from and to remote devices. For example, the radio transceiver may permit the device10to communicate with a remote server. The device10may further include a number of I/O ports that permit data and other information to be transferred to and from the processing system12and the location determining component14. The I/O ports may include a memory card slot for receiving removable memory cards and a USB port for coupling with a USB cable connected to another processing system such as a personal computer. Navigational software, cartographic maps and other data and information may be loaded in the device10via the I/O ports, the wireless transceivers, or the infrared port.