US 4,229,749 A · Ink drop compensation based on print-data blocks

Abstract

The invention relates to an ink jet printer and in particular to correcting the flight path of drops from the printer to reduce print position error on the print media. It has been found that drops as far as 30 drop positions ahead of a drop in the ink stream can have an effect on the flight path of that drop to the print media. Using a memory to store 2.sup.30 compensation values to correct the flight of the drop for all possible combinations of drop patterns in the ink stream is not practical. Disclosed herein is a method and apparatus for using a smaller number of compensation values to correct the flight path for all possible combinations. This is accomplished by grouping the drops remote in position from the drop being compensated into blocks of drops and treating the entire block of drops as contributing one effect on the flight of the drop. Accordingly, drops close to the compensated drop are treated as having an individual effect on the flight path while drops remote from the compensated drop are grouped into one of more blocks and each block is treated as having a single effect on the compensated drop.

Claims17

Dependent claims

In an ink jet printer having a charge electrode and a deflection electrode to control the flight of a reference ink drop to a print media in accordance with print data for the drop, apparatus for correcting the flight path of the ink drop to reduce print position error comprising:

print data buffering means for storing the print data pattern of drops in the ink stream with the reference drop;
memory means for storing a compensation value for each of a plurality of print data patterns in the ink stream, said compensation value, when applied to said printer, compensating the flight path of the reference ink drop based upon the data pattern of the ink drops in the ink stream with the reference drops;
logic means responsive to said buffering means for grouping a portion of the print data into a portion of the address for said memory means;
addressing means responsive to said buffering means and to said logic means for addressing said memory means based upon a portion of the print data directly and the remaining portion of the print data indirectly as grouped by said logic means;
said memory means in response to said addressing means reading the compensation value to said ink jet printer so that said printer can correct the flight path of the reference ink drop.

2 more elements

Compensation apparatus for correcting the flight path of ink drops in a binary ink jet printer having a charge electrode and a deflection electrode to control the flight path of the ink drops whereby, if the drop is a print drop, a print data bit controls the charge on the charge electrode and, if the drop is a no-print or gutter drop, a gutter data bit controls the charge on the charge electrode, said compensation apparatus comprising:

first storage means for storing a charge compensation value for the drop being charged, said compensation value being a function of the data bit pattern for ink drops in the ink stream with the drop being charged;
temporary storage means for storing the data bit pattern corresponding to the stream of ink drops currently being controlled by the ink jet printer;
analyzing means for analyzing a block of data bits in the data bit pattern in said temporary storage means and generating a partial address for said first storage means;
address means for forming the address for said first storage means with the temporarily stored data bits outside the analyzed block of data bits and with the partial address from said analyzing means;
said first storage means responsive to the address formed by said address means for reading out to the printer the compensation value for the data but pattern for the ink stream so that said printer can adjust the charge on the charge electrode to correct the flight path of the ink drop being charged.

2 more elements

Dependencies are inferred from the claim text.

Ink drop compensation based on print-data blocks

Life of this patent

Ink drop compensation based on print-data blocks

Life of this patent

Abstract

Claims17