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Satellite and Faulty Drop Sensor Detection in Velocity Control System of an Ink Jet Printer

IP.com Disclosure Number: IPCOM000087705D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 4 page(s) / 124K

Publishing Venue

IBM

Related People

Arnold, RW: AUTHOR [+3]

Abstract

Gross errors in velocity of a continuous stream of ink drops of an ink jet printer can cause the wrong number of ink drops. A velocity control system is described on pages 3697-3702 of this issue, which determines the direction of the gross velocity error and then makes one or more coarse increment corrections to the pressure of the ink supply pump until a reversal in the error direction is detected through operation of a pair of ink drop sensors spaced one drop length apart. The system thereafter is switched to a fine mode of operation such that fine adjustment to the pump pressure will result in correct ink drop velocity with the correct number of drops. The successful operation of the system depends on the condition of zero satellites in the drop stream.

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Satellite and Faulty Drop Sensor Detection in Velocity Control System of an Ink Jet Printer

Gross errors in velocity of a continuous stream of ink drops of an ink jet printer can cause the wrong number of ink drops.

A velocity control system is described on pages 3697-3702 of this issue, which determines the direction of the gross velocity error and then makes one or more coarse increment corrections to the pressure of the ink supply pump until a reversal in the error direction is detected through operation of a pair of ink drop sensors spaced one drop length apart. The system thereafter is switched to a fine mode of operation such that fine adjustment to the pump pressure will result in correct ink drop velocity with the correct number of drops.

The successful operation of the system depends on the condition of zero satellites in the drop stream. If satellites are present, the velocity error control loop will converge in the wrong direction, thereby locking in on the wrong pressure.

This system is designed to prevent the velocity control loop from locking in on the wrong pressure when satellites are present. Basically, the system provides a means for counting the time interval for a fixed number of drops to be detected by the #1 ink drop sensor and comparing it with the actual number of drops counted to generate a control signal which disables the control loop.

This satellite detect circuit (Fig. 1) comprises time counter 10, time count decode 11 which operates time latch 12 when a 9.3-drop time count is reached by pulses from a 5 MHz oscillator 13. Drop counter 14 counts drop sense pulses from sensor #1 gated through AND circuit 15 while the Q of time latch 12 is up. When time decode 11 decodes a 9.3-drop time condition of time counter 10, the Q output goes down and drop pulses from sensor #1 are blocked from reaching drop counter 14. If drop decode 16 decodes 9 drops when time counter 10 rea...