Browse Prior Art Database

Electrodynamic Velocity and Position Sensor and Emitter Wheel

IP.com Disclosure Number: IPCOM000080999D
Original Publication Date: 1974-Mar-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 3 page(s) / 48K

Publishing Venue

IBM

Related People

Naylor, HE: AUTHOR [+2]

Abstract

A sensing technique for measuring linear and angular velocity and position is described. See also the related article in the IBM Technical Disclosure Bulletin, Vol. 16, No. 10, March 1974, pp. 3300 to 3302 entitled "Precision Automatic Positioning Means .

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 54% of the total text.

Page 1 of 3

Electrodynamic Velocity and Position Sensor and Emitter Wheel

A sensing technique for measuring linear and angular velocity and position is described. See also the related article in the IBM Technical Disclosure Bulletin, Vol. 16, No. 10, March 1974, pp. 3300 to 3302 entitled "Precision Automatic Positioning Means .

Using the sensor shown in Figs. 1a and 1b it is possible to resolve ink droplet deflection variations of +/-1.6 mils (+/-2/3 of a drop diameter). If the charged ink stream 1 is removed and replaced by an equally charged (DC voltage) conductor, then similar results can be expected. That is, the output of differential amplifier 2 can be expected to null when the charged conductor is centered over the gap between the planar plate sensing element 3, comprising portions 3a and 3b. Figs. 1a and 1b represents measurement of the deflection of charged ink droplets. With ten 2.2 mil diameter ink drops approximately 5 mils apart, each carrying a charge of 6 x 10/-13/ coulombs, the sensor located 20 mils from the stream can resolve height changes of +/-1.6 mils.

If, instead of a single-charged conductor, a linear array 5 of charged conductors is used, all are tied to the same DC potential 6 as shown in Fig. 2. If array 5 is fixed in a machine and sensor 7 is mounted on a moving carriage, then the signals induced on the sensor by the charged conductors of the linear array, due to relative motion, produces a series of amplifier nulls. The frequency of these nulls are then proportional to velocity. By mounting a second sensor 8 on the carrier, and adjusting its gap with respect to the gap of the first sensor 7, it is possible to get two series of nulls, 90 degrees apart. With this configuration both velocity and direction of motion can be determined. If the linear array of conductors shown in Fig. 2 is driven by an AC signal, such as 100KHz or some other suitable frequency, then the amplifiers 12 and 13 can sense nulls while moving or while stopped. Thus, if an extra wide conductor is located near the left margin of an ink jet printer to provide a reference, then this configuration can serve instead of an optical grating.

In addition to the linear device of Fig. 2, it is also possible to utilize a wheel with radiating 'spoke' conductors 10, as shown in Fig. 3. An extra wide spoke 10a is used as a marker or reference. Assuming rotation is only in one direction, marker spoke 10a allows a single sensor to provide both velocity and position information.

There are a number of characteristics of position and velocity sensing devices that are...