US 5,312,193 A · Control device for a matrix printer

Abstract

A control device for a matrix printer in which the mechanical printing elements of the matrix printer are selectively triggered by the control device a certain time before they reach the desired printing spot on the information carrier in order to compensate for the fact that the printing head will move further over a certain distance between the triggering moment and the moment that the printing element actually hits the information carrier. This distance depends on the speed of the printing element. If the print signal, however, is always generated a constant distance before the printing element reaches the desired printing spot, this signal must be delayed as a function of the speed of the printing element if the printing head is to print accurately also during its run-up and slow-down. To this end, a delay device is provided which delays the print signal for the relevant printing element by a time interval which depends on the printing head speed. A preferred embodiment of the delay device uses a counter, which is also used for determining the energizing time of the magnet and an interval time. Furthermore a correction device for determining the delay time in dependence on the speed is provided. This device works with two adjustable counters, in which one counter counts a constant pulse frequency and the other counter counts position pulses which depend on the movement of the printing element. The constant needle stroke time thus is converted into a speed-dependent path by which the lead distance of the print signal is corrected.

Claims18

Dependent claims

A control device for selectively controlling the mechanical printing elements of a matrix printer, which elements are arranged in a printing head moving along a print line to generate the characters to be printed by means of print dots, which dots are arranged in at least one predetermined printing raster, said control device comprising:

a control unit which generates a print signal for each printing element individually when said printing element reaches a position which lies a certain printing path before an envisaged printing location on an information carrier, characterized in that at least those printing elements whose arrangement in the printing head corresponds to a column of the printing raster are connected to a delay device which is controlled by the print signal to start a control signal for the direct mechanical triggering of the associated printing element after a delay time which is dependent on the speed of the printing head, wherein the delay device comprises a shift register and the print signal writes a first binary value into a stage of the shift register and which is derived from a correction value dependent on the printing head speed, the contents of the shift register are then shifted further by means of shift pulses and the arrival of the first binary value at a given stage in the shift register starts the control signal, and wherein the shift pulses are derived from position pulses generated during the movement of the printing head and the delay time is independent of which printing element is selected.

a control unit which generates a print signal for each printing element individually when said printing element reaches a position which lies a certain printing path before an envisaged printing location on an information carrier, characterized in that at least those printing elements whose arrangement in the printing head corresponds to a column of the printing raster are connected to a delay device which is controlled by the print signal to start a control signal for the direct mechanical triggering of the associated printing element after a delay time which is dependent on the speed of the printing head, and wherein the delay device comprises a counter and the print signal sets the counter to a correction value which depends on the printing head speed and the counter then counts to a first end value by means of count pulses of a first frequency provided via a count pulse input, whereby the control signal is started when said first end value is reached.

A control device for controlling operation of the mechanical printing elements arranged in a printing head of a matrix printer, said control device comprising:

a first input for receiving signal pulses indicative of the speed of the printing head and generated in response to movement of the printing head,
means responsive at least to said signal pulses for deriving a print signal at a predetermined distance before the printing elements reach a desired printing spot on an information carrier,
a correction device responsive to said signal pulses and to a pulse signal of constant frequency to derive at its output a correction signal determined by the speed of the printing head, and
a delay device responsive to said print signal and to said correction signal for deriving at its output a control signal for triggering the printing elements after a delay time determined by the correction signal and thus by the speed of the printing head.

1 more element

Dependencies are inferred from the claim text.

Control device for a matrix printer

Life of this patent

Control device for a matrix printer

Life of this patent

Abstract

Claims18