US 4,495,597 A · Microprocessor-controlled adapter circuit for real-time controls, in particular for print hammer controls

Abstract

Microprocessor-controlled adapter circuit for real-time controls, in particular for print hammer controls in line printers with revolving type carrier with two asynchronously driven FIFO buffers (FIRST IN, FIRST OUT). The first FIFO buffer contains time values (e.g., firing times for the print hammers) and the second FIFO buffer control information associated with these time values (e.g., print hammer address, control commands for the print hammer). By a request circuit (e.g., counters), the time values are successively read from the first FIFO buffer and fed to a gate circuit for switching the control information, associated with these time values, from the second FIFO buffer for controlling the output values. A method of determining the firing times of the print hammers uses a reduced table in which for each character in each print position the positions (time values), in which the character is to be printed, are stored only for some displacement values of the revolving type carrier relative to the printer frame. For the remaining displacement values, the time values for character printing can be determined by division, using the table data. Mechanical or electrical tolerances influencing the firing times of the print hammers are compensated for by accommodating in the table additional correction delay values for the print hammers, thus eliminating adjustments.

Claims11

Dependent claims

A microprocessor-controlled adapter circuit for real time controls of output values, characterized in

that two asynchronously driven FIFO buffers (FIFO=FIRST IN, FIRST OUT) are provided, one of which can be loaded with time values from the microprocessor, at which a control process is to be effected, and the other one of which can be loaded from the microprocessor with control information associated with these time values (such as address of an element to be controlled, type of control process), and that a request circuit is provided, by means of which the time values are successively read from the first FIFO buffer and are fed to a gate circuit for switching the control information associated with these time values from the second FIFO buffer for controlling the output values.

A method of determining the firing times for the print hammers of line printers with a revolving character carrier,

wherein the print hammers and the characters have different pitches and the character position on the character carrier is determined by the distance of the characters from a reference mark HPB on the character carrier, and the displacement x of the revolving character carrier relative to a fixed reference point on the printer frame can be determined as the distance of the reference mark HPB on the character carrier from a reference mark HPF on the printer frame, characterized in
that for each character in each print position a table entry of the following kind is made in the memory of a computer controlling the character output:
for successive equidistant integral displacement values, whose difference is >1, the distances D of the character, which may exist on the character carrier several times, from the reference mark HPB on the character carrier are continuously entered into the table;
these entries D are associated with a continuous table index I, and the table is associated with a divisor where said divisor is chosen so that the rounded result of the division of an arbitrary integral displacement value x-.DELTA.H by the divisor yields a table index I-K for a distance value D-K of the character associated therewith and that for x<D-K the distance value D-K is the desired distance value and for x>D-K the distance value D-K+1 is the desired distance value, and that the character is fired after it has travelled this distance relative to the reference mark HPF plus the value .DELTA.H,
where .DELTA.H is the displacement value of a character for a proposed print position relative to the first possible print position which is identical with the reference mark HPF.

2 more elements

Dependencies are inferred from the claim text.

Microprocessor-controlled adapter circuit for real-time controls, in particular for print hammer controls

Life of this patent

Microprocessor-controlled adapter circuit for real-time controls, in particular for print hammer controls

Life of this patent

Abstract

Claims11