Digitizer and position encoders and calibration system for same
First Claim
1. A position encoding system, comprisingmeans for encoding position coordinates of a point,a position reference medium containing reference marks,means for processing calibration data, said calibration data based on a value of encoded coordinates of the reference marks,operation means for correction of encoding errors in accordance with said calibration data, so as to improve accuracy and repeatability for said encoding of position coordinates.
0 Assignments
0 Petitions
Accused Products
Abstract
Digitizer incorporates two novel position encoders. One position encoder comprises means for periodic spatial calibration against an accurate pattern of reference marks, thereby improving accuracy to the limit of resolution. Optionally, it also includes temperature and humidity compensation. Superior accuracy is achieved without tight tolerance requirements for mechanical components. The same technique can be used for error detection in digital motion control.
The other position encoder, used primarily for menu data entry, is based on a discrete resistor array, combined with pulse position modulation of array columns. Its main advantage is simplicity and low cost.
The digitizer is ergonomically designed, so that the operator can digitize coordinates with the left hand while inputing from the menu with the right hand.
-
Citations
16 Claims
-
1. A position encoding system, comprising
means for encoding position coordinates of a point, a position reference medium containing reference marks, means for processing calibration data, said calibration data based on a value of encoded coordinates of the reference marks, operation means for correction of encoding errors in accordance with said calibration data, so as to improve accuracy and repeatability for said encoding of position coordinates.
-
9. A position encoder, comprising
an array of resistors, connected in series within separate columns of the array, differently modulated drivers energizing said resistor columns, electrodes in contact with terminals of said resistors, a stylus which on touching a specific electrode connects said electrode to an encoder electronic circuit, encoder electronic circuit which derives from an amplitude and modulation of a stylus signal an identity of the touched electrode and subsequently outputs a coded signal corresponding to said identity.
-
15. A graphic digitizer, comprising
a board, a first hollow longitudinal coordinate arm fixedly mounted to said board, a second hollow longitudinal coordinate arm orthogonally positioned with respect to said first coordinate arm and movable thereon, a drafting head mounted on said second coordinate arm so as to allow movement along the said second coordinate arm, said drafting head thereby positionable along two axes over said board, a cursor mounted on said drafting head, a first motion encoding element mounted on first coordinate arm, a first mechanical linkage strung along a length of the first coordinate arm and attached to the second coordinate arm for transferring a motion of the second coordinate arm with respect to the first coordinate arm, to said first motion encoding element, a second motion encoding element mounted on the second coordinate arm, a second mechanical linkage strung along a length of the second coordinate arm and attached to the drafting head for transferring a motion of said drafting head and the cursor attached thereto with respect to the second coordinate arm, means for converting an output of said motion encoding elements to position coordinates, a position reference surface with reference marks thereon, means for gathering calibration data based on encoded coordinate values of the reference marks, means for storing calibration data, means for using said stored calibration data to improve accuracy of digitizing a position of said cursor relative to said board.
Specification