Printing apparatus and methods for compensating synchronization errors

Claim 3

A methd for compensating synchronization errors in the transport of a record carrier of a non-impact matrix printer in which stored information of a line of print is formed by picture lines which are successively recorded with a given spacing, an actual spacing of the picture lines being dependent upon an actual transport speed of the record carrier and a recording frequency of the picture lines, characterized in that the method comprises deriving a control value from a difference between the actual transport speed of the record carrier and a predetermined transport speed of the record carrier, the control value causing a shift of the recording of a picture line in a predetermined recording zone on the record carrier without changing the recording frequency of the picture lines, each picture line being recorded a number of times with a same informational content, the shifting of the recording of a picture line being performed only after recording the number of picture lines with the same content, which number is determined by the control value so that when the actual transport speed deviates from the predetermined transport speed in one direction, the picture line last recorded is recorded (n+1) times, while when the actual transport speed deviates from the predetermined transport speed in another direction, the picture line to be recorded next is recorded (n-1) times.

Claim 4

A methd for compensating synchronization errors in the transport of a record carrier of a non-impact matrix printer in which stored information of a line of print is formed by picture lines which are successively recorded with a given spacing, an actual spacing of the picture lines being dependent upon an actual transport speed of the record carrier and a recording frequency of the picture lines, characterized in that the method comprises deriving a control value from a difference between the actual transport speed of the record carrier and a predetermined transport speed of the record carrier, the control value causing a shift of the recording of a picture line in a predetermined recording zone on the record carrier without changing the recording frequency of the picture lines, each picture line being recorded a number of times with a same informational content, the shifting of the recording of a picture line being performed only after recording the number of picture lines with the same content, which number is determined by the control value so that when the actual transport speed deviates from the predetermined transport speed in one direction, the picture line last recorded is recorded (n+1) times, while when the actual transport speed deviates from the predetermined transport speed in another direction, the picture line to be recorded next is recorded (n-1) times.

Claim 5

A circuit arrangement for compensating synchronization errors in an actual transport speed of a rotating cylindrical record carrier in a non-impact matrix printer in which a line of print is formed by picture lines which are successively recorded on the record carrier in a horizontal direction parallel to the longitudinal axis of the record carrier, each picture line being recorded by a recording beam being deflected in said horizontal direction at a deflection frequency, a preferred spacing between a picture line having a first informational content and a successive picture line having a second informational content being predetermined, an actual spacing between a picture line and a successive picture line being dependent upon said horizontal deflection frequency of the recording beam and the actual transport speed of the record carrier, the circuit arrangement comprising: means for generating data based upon actual transport speed; means for producing picture line trigger pulses; a memory electrically connected to the producing means and storing said data based upon actual transport speed; a digital-to-analog converter electrically coupled to the memory and producing an output signal based upon said actual transport speed; a cathode ray tube having a coil for vertically deflecting the recording beam, and an amplifier electrically connected to the digital-to-analog converter output and driving the coil, the memory being switched to activate the coil responsive to negative pulse edges of the picture line trigger pulses, said coil deflecting the recording beam by a fraction of the picture line spacing.

Claim 6

A circuit arrangement for compensating synchronization errors in an actual transport speed of a rotating cylindrical record carrier in a non-impact matrix printer in which a line of print is formed by picture lines which are successively recorded on the record carrier in a horizontal direction parallel to the longitudinal axis of the record carrier, each picture line being recorded by a recording beam being deflected in said horizontal direction at a deflection frequency, a preferred spacing between a picture line having a first informational content and a successive picture line having a second informational content being predetermined, an actual spacing between a picture line and a successive picture line being dependent upon said horizontal deflection frequency of the recording beam and the actual transport speed of the record carrier, the circuit arrangement comprising: means for generating data based upon actual transport speed; means for producing picture line trigger pulses; a memory electrically connected to the producing means and storing said data based upon actual transport speed; a digital-to-analog converter electrically coupled to the memory and producing an output signal based upon said actual transport speed; a cathode ray tube having a coil for vertically deflecting the recording beam, and an amplifier electrically connected to the digital-to-analog converter output and driving the coil, the memory being switched to activate the coil responsive to negative pulse edges of the picture line trigger pulses, said coil deflecting the recording beam by a fraction of the picture line spacing.

Claim 7

A circuit arrangement as claimed in claim 3, wherein said means for generating data includes: means for deriving a first pulse series from the speed of revolution of the record carrier; a dual counter electrically connected to the deriving means and to the memory, the dual counter having an output at which a second pulse series is present responsive to the first pulse series, the second pulse series having pulses of a width which is larger than a pulse width of the picture line trigger pulses, and a phase comparator electrically connected to the output of the dual counter and to the producing means.