Function-oriented Knowledge Base \ Optical Mouse Cord
Acoustic signals transmit cursor control signals to computer
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Introduction According to conventional practice, a computer
mouse is connected to a computer via a connection cord. This
causes the following problem. The cord of the corded mouse
often gets in the way, which annoys the user. Also, it can
be broken or operate in an unstable manner. Because the cord
is a necessary element, this limits the operational area of
the mouse. A method of providing a mouse or other pointing
device without a corded connection to the computer is needed.
Description To transmit cursor control signals to the computer,
the use of acoustic signals is proposed. The user's hand moves
a cursor-pointing device (e.g., a hand-held stylus or a cordless
mouse) along any suitable flat surface. The cursor-pointing
device is comprised of an ultrasonic transducer. The ultrasonic
transducer periodically emits acoustic signals. The acoustic
signals propagate in the air and reach acoustic receivers
installed on a tracking means. The ultrasonic transducer is
separated from each receiver by various distances. At the
constant speed of sound in air, the delay time of the acoustic
signal is proportional to the distance between the ultrasonic
transducer and the acoustic receiver. Therefore, the acoustic
receivers receive acoustic signals with various delay times.
At the known speed of sound in air, the measured values of
the delay times in each channel of the tracking means allow
the microprocessor to calculate the position and the movement
of the ultrasonic transducer relative to the tracking means.
The received digital data are then communicated to the host
computer through a standard cursor control cable. Thus, acoustic
signals transmit cursor control signals to the computer.
Additional information For self-calibration purpose, the tracking means
can also emit acoustic waves between themselves to measure
the speed of sound in air.
