Browse Prior Art Database

Precision Automatic Positioning Means

IP.com Disclosure Number: IPCOM000080998D
Original Publication Date: 1974-Mar-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 3 page(s) / 27K

Publishing Venue

IBM

Related People

Naylor, HE: AUTHOR [+2]

Abstract

Accurate positioning of a wide range of materials such as printed-circuit (PC) boards during component insertion, paper and document (sheet & roll feed) handling, integrated circuit (IC) chips during attachment to a package is described. Positioning accuracies of the order of +/-0.16 mil are achieved. Improved accuracies are possible by improving control electronics.

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Precision Automatic Positioning Means

Accurate positioning of a wide range of materials such as printed-circuit (PC) boards during component insertion, paper and document (sheet & roll feed) handling, integrated circuit (IC) chips during attachment to a package is described. Positioning accuracies of the order of +/-0.16 mil are achieved. Improved accuracies are possible by improving control electronics.

Another article in the IBM Technical Disclosure Bulletin, Vol. 16, No. 10, March 1974, pp. 3303 to 3305 entitled "Electrodynamic Velocity and Position Sensor and Emitter Wheel" describes a number of applications of a differential capacitive, i.e., noncontacting position sensing device. The sensor device is used as a means of obtaining velocity and linear and angular position information with moving mechanical parts and systems. By adding logic and analog electronics to this device, an automatic positioning system is provided. One such application is an automatic deflection control system, used to control height variations of ink droplets in an ink jet printer.

The basis of this system is the use of a line charge 1 located near two sensor plates 2 and 3 connected to a difference amplifier 4, as shown in the drawing.

Since the system is capacitive in nature some means of changing the input signal to the amplifier is required. Two ways are available.
1) If the line charge is always moving with respect to the

plates, then the signal changes as a result of the relative

velocity between the two. A DC or an AC line charge can be

used.
2) If the line charge is not always moving with respect to the

sensor plates, then the line charge must be AC in nature to

obtain a signal, and hence position information.

There are a number of desirable features associated with this scheme:
A. It operates using a differential measurement technique, hence

all common-mode noise is eliminated and the system is

relatively insensitive to ambient noise levels.
B. By adding a stage of electronic integration following the

difference amplifier, additional noise immunity is gained.
C. By using a number of sensors and a number of line charges

that are carefully placed with respect to one another,

improved signal-to-noise ratio is obtained. This technique

is further described in the above-mentioned article.

A sensing scheme of this nature can be used in a number of ways: IN PAPER HANDLING, a co...