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Function-oriented Knowledge Base \ Optical Mouse Cord

Acoustic signals transmit cursor control signals to computer

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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.
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.
US Patent 4654648; Link >>
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