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Velocity Test Character

IP.com Disclosure Number: IPCOM000086712D
Original Publication Date: 1976-Oct-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Short, P: AUTHOR

Abstract

A test procedure is utilized for providing a visual indication as to whether the velocity of an ink jet carrier exceeds a predetermined maximum value during the time allotted for printing the test characters.

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Velocity Test Character

A test procedure is utilized for providing a visual indication as to whether the velocity of an ink jet carrier exceeds a predetermined maximum value during the time allotted for printing the test characters.

Fig. 1 shows the printing of three consecutive test characters in a normal operation. Fig. 2 shows the printing of the same test characters in an overspeed operation.

In an ink jet printer, a minimum character is composed of four vertical scans. Each single scan corresponds to a spacing of 1/240th of an inch, and each group of four scans corresponds to a spacing of 1/60th of an inch. The ink-drop formation rate is fixed by the system clock frequency. Thus, the time available to print a vertical scan is inversely proportional to the carrier velocity.

By coding a test character pattern (Fig. 1) consisting of three groups 11, 13 and 15 of four scans and printing this with an escapement value of five groups 11, 13, 15, 17 and 19 of four scans (20 scans total), the printed result will show within approximately 1/20th of an inch, the location of the first overspeed condition anywhere along the printing line (Fig. 2).

The test pattern is coded using a particular placement drop algorithm such that the first group of four scans are coded to require less time than the maximum allotted to print. The second and third group of four scans are coded to require more than the allotted time to print, such that one scan time is lost during this interval...