Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
  • B41J29/00—Details of, or accessories for, typewriters or selective printing mechanisms not otherwise provided for
  • B41J29/38—Drives, motors, controls or automatic cut-off devices for the entire printing mechanism
  • B41J29/393—Devices for controlling or analysing the entire machine ; Controlling or analysing mechanical parameters involving printing of test patterns

Definitions

• a method and device for printing quality control is provided.
• the invention relates to a method and device for chec ning the printing quality of preferably matrix or liquid jet printers with the aid of photo-sensitive sensing means.
• printers In printing with a matrix printer, the readability is dependent, inter alia, on the condition of the printing ribbon, and that all the printing elements of the printing head are functioning. Particularly obvious problems with control of these functions are present where printers are used without their being given continuous supervision. Examples of such printers are computer controlled printing apparatus operating at certain times during the day, and cash dispensers which print out dtails of transactions carried out.
• Figure 1 schematically illustrates the parts of a matrix printer which are of interest in connection with the invention
• Figure 2 illustrates the included electrical circuits.
• Figure 1 schematically illustrates a writing paper 1 with characters which are printed with the aid of a printing head 2 of the matrix printer type.
• the printing head has also printed a dot pattern 3 in the left hand margin of the paper for ech line of print.
• the pattern is shaped as a row of dots at right angle to the direction of movement of the printing head and has been produced by all the writing elements of the printing head.
• An optical sensing means 4 is disposed such that the dot pattern 3 passes under the sending means 4 during line shifting.
• FIG. 2 illustrates in more detail a device in accordance with the present invention.
• the optical sensing means 4 includes a light emitting diode 7 illuminating the writing paper under a row of photo diodes 8 provided with a shift register, e.g. of the type EG & G Reticon RL128G.
• a shift register e.g. of the type EG & G Reticon RL128G.
• the dot row 3 passes in the direction of the arrow P past the photo diode row 8, where the diodes at a spacing of 25 um are arranged at right angle to the direction of movement of the dot row 3.
• each diode is read out in turn with a speed determined by a control means 12 included in a computer 6.
• the clock frequency of the control means has been selected to 50 KHz and the sampling frequency to 300 Hz, which gives a scanning time of 2,56 ms and about 12 scans per dot of the dot pattern 3.
• the signal from each photo diode is transferred to a comparator means 5 where it is amplified in a DC amplifier F and compared with the voltage from a reference voltage source R in a differential amplifier D. To signals with higher amplitude than the reference voltage are assigned a "one" is allotted in the differential amplifier, while to signals with lower amplitude is allotted a "zero".
• the digitalized signals are read by the computer 6, where a counter 9 adds all the "ones" according to given conditions.
• One condition may be that at least four consecutive "ones" are required for the counter to add them. After three scans of all diodes without the above-mentioned condition being filled, the counter is read, subsequent to which it is set to zero. A condition for a dot to be registered at the passage of the dot pattern 3 past the sensing means is that the counter 9 adds 40 "ones", for example. The number of registered dots is compared in a register 10 with the number of printing elements in the printing head 2. If there is a difference between these numbers a signal circuit 11 is actuated to give an alarm signal.

Landscapes

• Accessory Devices And Overall Control Thereof (AREA)
• Ink Jet (AREA)
• Particle Formation And Scattering Control In Inkjet Printers (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20352776

Family Applications (1)

Country Status (10)

Cited By (10)

Families Citing this family (1)

Citations (2)

• 1983
  • 1983-10-05 SE SE8305478A patent/SE439132B/sv not_active IP Right Cessation
• 1984
  • 1984-09-28 DE DE8484903675T patent/DE3468371D1/de not_active Expired
  • 1984-09-28 JP JP59503648A patent/JPH0653426B2/ja not_active Expired - Lifetime
  • 1984-09-28 WO PCT/SE1984/000321 patent/WO1985001476A1/en active IP Right Grant
  • 1984-09-28 EP EP84903675A patent/EP0157851B1/en not_active Expired
  • 1984-10-03 CA CA000464672A patent/CA1266710A/en not_active Expired
  • 1984-10-04 ES ES536508A patent/ES8601018A1/es not_active Expired
  • 1984-10-05 IT IT23040/84A patent/IT1176886B/it active
• 1985
  • 1985-05-13 FI FI851883A patent/FI81303C/sv not_active IP Right Cessation
  • 1985-06-03 DK DK249985A patent/DK163648C/da not_active IP Right Cessation

Patent Citations (2)

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