Pointing device and receiving unit with UWB signal
A small-sized and lightweight pointing device and receiving unit reduce power consumption. The receiving unit transmits UWB (Ultra Wide Band) signals simultaneously from an antenna thereof. The pointing device receives the transmitted UWB signals with three antennas thereof. The respective timings when the transmitted UWB signals are received with the three antennas depend on the distances between the transmitting antenna and the three receiving antennas. With this principle, propagation distances from the transmitting antenna to the three receiving antennas are real distances between the transmitting antenna and the three receiving antennas. By applying the principle of triangular surveying to the distances, position coordinates of the pointing device to the receiving unit can be specified. Amount of movement made by the pointing device is calculated based on a change in the position coordinates.
1. A handheld pointing device, comprising:
a first unit that communicates with a receiving unit by Ultra Wide Band signals;
a plurality of antennas that receive Ultra Wide Band signals regularly transmitted from the receiving unit;
a second unit that is within a main body of the pointing device and that specifies reception timings of the Ultra Wide Band signals on an antenna basis;
a third unit that specifies transmission timings of the Ultra Wide Band signals;
a fourth unit that calculates propagation distances of the Ultra Wide Band signals, based on the reception timings and the transmission timings;
a fifth unit that calculates position coordinates of the pointing device relative to the receiving unit with the propagation distances, based on a principle of triangular surveying; and
a sixth unit that calculates an amount of movement of the pointing device, based on a difference between the position coordinates calculated at a last time and the position coordinates calculated at a current time.
2. The pointing device as claimed in claim 1 , wherein the pointing device is a mouse.
3. The pointing device as claimed in claim 1 , wherein the pointing device is a pen-like coordinate input device.