1. Field of the Invention
The present invention relates to an antenna structure of a miniature wireless receiver, and in particular, to an antenna structure of a miniature wireless receiver arranged to be connected to a computer and that is capable of receiving wireless control signals from an input device situated in either a horizontal or vertical direction, irrespective of whether the antenna itself is disposed in a vertical or horizontal orientation.
2. Description of the Prior Art
A wireless input device, such as but not limited to a mouse, keyboard, trackball, game controller, always sends wireless control signals to control the operation of a computer system. However, due to the unexpected shrinking in size, the wireless receiver needs to be carefully designed so as not to miss receiving any commands generated from the wireless input device.
Generally, the antenna of the input device or the wireless receiver is printed on a printed circuit board (PCB) horizontally, as can be observed from FIG. 2 of U.S. Pat. Nos. 5,854,621. Once the wireless receiver is horizontally plugged into a USB (universal serial bus) port of a computer, the horizontal antenna of the receiver will precisely receive the signals. However, when the wireless receiver is vertically plugged into a USB port of a computer, the vertically-plugged-antenna of the receiver will not function well to receive the signals, unless the distance between the receiver and the input device is rather close.
In order to overcome this problem, U.S. Pat. No. 6,356,243 discloses a three-dimensional antenna structure in which the antenna has a first portion printed on the PCB (printed circuit board), and a second portion projected into the space at the top of the first portion. However, U.S. Pat. No. 6,356,243 only focuses on how to increase the overall size of the antenna (col. 2, lines 10–50), and does not present any solution about how to precisely receive wireless signals in both vertical and horizontal dispositions on the computer. In addition, the antenna described in in U.S. Pat. No. 6,356,243 needs both a first portion and second portion extending into a space on top of the first portion, which raises the cost of the antenna. Further, the second portion of the antenna is located on the circuit board and may cause unexpected interference or noise if the second portion of antenna isn't carefully laid out.