Method and apparatus for reducing noise in an electrostatic digitizing table
First Claim
1. A digitizing panel comprising:
- means for determining a velocity of a stylus relative to the digitizing panel;
a filter for filtering said stylus position data, said filter having a bandwidth characteristic;
means for varying said bandwidth characteristic based on said velocity of said stylus; and
means for generating said stylus position data at a first predetermined rate,wherein said means for determining includes (i) means for sampling said stylus position data at a second predetermined rate to generate present position data and previous position data, and (ii) means for determining a distance between said presently sampled coordinate data and said previously sampled coordinate data.
9 Assignments
0 Petitions
Accused Products
Abstract
A digitizing panel responsive to a signal transmitted from a stylus for generating stylus position information is disclosed. The digitizing panel includes a coordinate generator for determining coordinate data indicative of a position of the stylus relative to the digitizing panel, a velocity calculator for determining a stylus velocity value based on the coordinate data, a mechanism for determining a filter bandwidth value based on the stylus velocity value, a filter for filtering the coordinate data wherein the filter has a predetermined bandwidth characteristic, and a mechanism for varying the predetermined bandwidth characteristic based on the filter bandwidth value. A method for filtering position data of a stylus associated with a digitizing panel is also disclosed.
-
Citations
23 Claims
-
1. A digitizing panel comprising:
-
means for determining a velocity of a stylus relative to the digitizing panel; a filter for filtering said stylus position data, said filter having a bandwidth characteristic; means for varying said bandwidth characteristic based on said velocity of said stylus; and means for generating said stylus position data at a first predetermined rate, wherein said means for determining includes (i) means for sampling said stylus position data at a second predetermined rate to generate present position data and previous position data, and (ii) means for determining a distance between said presently sampled coordinate data and said previously sampled coordinate data. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A method for filtering position data of a stylus associated with a panel, comprising the steps of:
-
filtering the position data through a filter; modifying bandwidth characteristics of the filter based on velocity of the stylus relative to the panel; sampling the position data at a predetermined sampling rate to generate present position data and previous position data; determining a distance between the present positioned data and the previous position data; and dividing the distance by a sampling time period to determine the velocity of the stylus. - View Dependent Claims (7, 8, 9)
-
-
10. A method for filtering position data of a stylus associated with a digitizing panel, comprising the steps of:
-
filtering the position data through a filter; increasing a bandwidth characteristic of the filter when a velocity of the stylus increases relative to the digitizing panel; decreasing the bandwidth characteristic of the filter when the velocity of the stylus decreases relative to the digitizing panel; sampling the position data at a predetermined sampling rate to generate present position data and previous position data; determining a distance between the present position data and the previous position data; and dividing the distance by a sampling time period to determine the velocity of the stylus. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
-
-
18. A digitizing panel responsive to a signal transmitted from a stylus for generating stylus position information, the digitizing panel comprising:
-
a coordinate generator for determining coordinate data indicative of a position of the stylus relative to the digitizing panel; a velocity calculator for determining a stylus velocity value based on said coordinate data; means for determining a filter bandwidth value based on said stylus velocity value; a filter for filtering said coordinate data, said filter having a predetermined bandwidth characteristic; and means for varying said predetermined bandwidth characteristic based on said filter bandwidth value, said means for varying including means for decreasing said bandwidth characteristic at a first rate when said stylus velocity value decreases at a second rate, wherein said first rate is slower than said second rate. - View Dependent Claims (19, 20, 21, 22)
-
-
23. A digitizing panel responsive to a signal transmitted from a stylus for generating stylus position information, the digitizing panel comprising:
-
a coordinate generator for determining coordinate data indicative of a position of the stylus relative to the digitizing panel; a velocity calculator for determining a stylus velocity value based on said coordinate data; means for determining a filter bandwidth value based on said stylus velocity value; a filter for filtering said coordinate data, said filter having a predetermined bandwidth characteristic; and means for varying said predetermined bandwidth characteristic based on said filter bandwidth value, wherein said filter has a transfer function of;
##EQU5##
-
Specification