Browse Prior Art Database

Position Detection in Printers

IP.com Disclosure Number: IPCOM000045173D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Dunn, JM: AUTHOR [+2]

Abstract

Current methods of determining the position of a printhead require calibration to a known position and then receiving impulses while the printhead is moved. By keeping track of the impulses, the position can be determined.

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Position Detection in Printers

Current methods of determining the position of a printhead require calibration to a known position and then receiving impulses while the printhead is moved. By keeping track of the impulses, the position can be determined.

A better way to determine printhead position utilizes a linear voltage to determine absolute position at any time. Referring to the figure, a wire 10 carrying an oscillating current is mounted in the print frame and a pickup sensor 12 is mounted on the printhead 14 capable of sensing the oscillating current in wire 10. It is thus possible to determine the printhead 14 position as it moves across platen 16 at any point in time. For instance, if a frequency of 5 MHz having a wavelength of 60 meters is used as the oscillating frequency, then anywhere along the 60-meter length it is possible to determine the position of a sensor by comparing the phase of the oscillating signal at the start of the cable to the phase of the signal at the sensed point. By using a phase comparator to produce an analog voltage proportional to the phase difference, absolute position is known. A digital to analog converter can then convert this phase difference to a digital signal which can be read directly by the printer controller.

In actual practice, oscillator 18 provides a signal having the frequency equal to 3x10/8/4Lambda over wire 10. This frequency is required to be measured along the fixed length object path of wire 10. The output...