EP0157851B1 - A method and device for printing quality control - Google Patents

A method and device for printing quality control Download PDF

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Publication number
EP0157851B1
EP0157851B1 EP84903675A EP84903675A EP0157851B1 EP 0157851 B1 EP0157851 B1 EP 0157851B1 EP 84903675 A EP84903675 A EP 84903675A EP 84903675 A EP84903675 A EP 84903675A EP 0157851 B1 EP0157851 B1 EP 0157851B1
Authority
EP
European Patent Office
Prior art keywords
signal
dot
pattern
printed
character
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP84903675A
Other languages
German (de)
French (fr)
Other versions
EP0157851A1 (en
Inventor
Per Ivar Roland Falk
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ICL System AB
Original Assignee
Telefonaktiebolaget LM Ericsson AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Telefonaktiebolaget LM Ericsson AB filed Critical Telefonaktiebolaget LM Ericsson AB
Publication of EP0157851A1 publication Critical patent/EP0157851A1/en
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    • 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

  • the invention relates to a method and device for checking 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 continuous supervision. Examples of such printers are computer controlled printing apparatus operating at certain times of the day, and cash dispensers which print out details 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 each line of print.
  • the pattern is shaped as a row of dots at right angles 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 sensing 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 ⁇ m 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.

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

Abstract

A method and device for checking the printing quality of matrix or liquid jet printers (2). A character (3) is printed in the paper margin and is optically sensed in connection with line shift. The signal pattern from the symbol is compared with a predetermined pattern corresponding to a correct reproduction of the character. An alarm signal is sent if there is a difference between the signal patterns.

Description

    Technical Field
  • The invention relates to a method and device for checking the printing quality of preferably matrix or liquid jet printers with the aid of photo-sensitive sensing means.
    • Background Art
  • 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 continuous supervision. Examples of such printers are computer controlled printing apparatus operating at certain times of the day, and cash dispensers which print out details of transactions carried out.
  • Different methods exist for checking the printing quality of matrix printers. For example, in the PCT application US 81/01207 (International Publication Number: WO 82/01163) there is described a device for detecting every dot that is printed by means of optical sensors following the printing head. The result of the detection is compared in a computer with a signal pattern corresponding to the printed character. A fault signal is produced on deviation from the signal pattern. The device is also intended for use with ink jet writers. Since the two most important factors affecting printing quality of a matrix printer are the condition of the printing ribbon and the function of the printing elements, the device according to the mentioned patent is an unnecessarily sophisticated and expensive solution.
    • Disclosure of Invention
  • With the present invention there is obtained a simple and effective check on the printing quality of a matrix printer or an ink jet printer. This is done by each printing element simultaneously printing a dot pattern within an area of the paper where no normal printing takes place. In connection with line shift a photo-sensitive device reads the printed pattern. The signals thus generated are processed and compared with a predetermined signal pattern corresponding to correct printing quality. Difference between these patterns activates an alarm circuit. The characterizing features of the invention are disclosed in the accompanying claims.
    • Brief Description of Drawings
  • The invention will now be described in detail in with reference to the accompanying drawing where Figure 1 schematically illustrates the parts of a matrix printer which are of interest in connection with the invention, and Figure 2 illustrates the included electrical circuits.
    • Best Mode for Carrying Out the Invention
  • 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 each line of print. The pattern is shaped as a row of dots at right angles 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 sensing means 4 during line shifting.
  • Figure 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. On a line shift 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 µm are arranged at right angle to the direction of movement of the dot row 3. By means of the shift register, each diode is read out in turn with a speed determined by a control means 12 included in a computer 6. In this case 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, for example, 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.

Claims (6)

1. A method of checking the typing quality of matrix or ink jet printers and the like, by means of a photo sensitive circuit (4), characterized in that the printer prints a dot pattern of a predetermined character in a predetermined area in relation to a line of print, in that each dot of the character is read by means of the photo sensitive circuit in connection with line shifting, in that all the signal
dots from the photo-sensitive circuit are compared together with a dot signal pattern corresponding to correct reproduction of the printed character, and that an error signal is generated if there is a difference between the two signal patterns.
2. Device for the method of checking the printing quality of matrix or liquid jet printers and the like, by means of a photo-sensitive sensing means (4), according to claim 1, characterized in that the photo-sensitive sensing means of the device is disposed such that in connection with line shift, a dot pattern (3) of a predetermined character printed by the printer in an area determined in relation to a printed line passes under the sensing means (4), electrical signals thus being generated by each dot of the pattern printed, the amplitude of which are dependent on the colour contrast of the dot against the printing agent (1), and circuits for comparison between all the signals together and a predetermined signal pattern, a signal being produced in response to difference between the pattern generated by the sensing means (4) and the predetermined signal pattern.
3. Device as claimed in claim 2, characterized in that the printed character forms a row of dots produced by all the printing elements simultaneously and running in the direction of paper feeding.
4. Device as claimed in claim 2, characterized in that for alternate lines the printed character originates from printing elements with odd numbers and for the other rows from printing elements with even numbers.
5. Device as claimed in claim 2, characterized in that the signal produced in response to difference between the two signal patterns controls an alarm circuit.
EP84903675A 1983-10-05 1984-09-28 A method and device for printing quality control Expired EP0157851B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8305478 1983-10-05
SE8305478A SE439132B (en) 1983-10-05 1983-10-05 PRINT QUALITY CONTROL SET AND DEVICE

Publications (2)

Publication Number Publication Date
EP0157851A1 EP0157851A1 (en) 1985-10-16
EP0157851B1 true EP0157851B1 (en) 1988-01-07

Family

ID=20352776

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84903675A Expired EP0157851B1 (en) 1983-10-05 1984-09-28 A method and device for printing quality control

Country Status (10)

Country Link
EP (1) EP0157851B1 (en)
JP (1) JPH0653426B2 (en)
CA (1) CA1266710A (en)
DE (1) DE3468371D1 (en)
DK (1) DK163648C (en)
ES (1) ES536508A0 (en)
FI (1) FI81303C (en)
IT (1) IT1176886B (en)
SE (1) SE439132B (en)
WO (1) WO1985001476A1 (en)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8621335D0 (en) * 1986-09-04 1986-10-15 Roneo Alcatel Ltd Printing devices
US5173850A (en) * 1988-02-12 1992-12-22 Hitachi, Ltd. Apparatus and method for checking print quality of turnaround medium
JP3049663B2 (en) * 1991-02-20 2000-06-05 キヤノン株式会社 Recording device and recording method
DE69214508T2 (en) * 1991-05-14 1997-03-13 Canon Kk Pressure estimation method and apparatus
JP3229431B2 (en) * 1992-05-28 2001-11-19 キヤノン株式会社 Patent application title: RECORDING DEVICE AND METHOD OF JUDGING RECORDING STATE OF RECORDING DEVICE
US5397192A (en) * 1993-11-01 1995-03-14 Hewlett-Packard Company Shuttle-type printers and methods for operating same
JPH08127139A (en) * 1994-10-31 1996-05-21 Nec Field Service Ltd Dot impact serial printer
AUPN232795A0 (en) * 1995-04-12 1995-05-04 Eastman Kodak Company Detection of faulty nozzles in printing heads
US6542622B1 (en) * 1999-08-30 2003-04-01 Eastman Kodak Company Methods and articles for determining invisible ink print quality
US9333783B1 (en) * 2015-07-13 2016-05-10 Toshiba Tec Kabushiki Kaisha Printer apparatus
US20230286308A1 (en) * 2020-07-21 2023-09-14 Hewlett-Packard Development Company, L.P. Print control

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5910311B2 (en) * 1977-04-19 1984-03-08 沖電気工業株式会社 dot printer
US4339208A (en) * 1980-09-25 1982-07-13 Ncr Corporation Optical sensing of wire matrix printers

Also Published As

Publication number Publication date
DK249985A (en) 1985-06-03
EP0157851A1 (en) 1985-10-16
FI81303C (en) 1990-10-10
JPH0653426B2 (en) 1994-07-20
ES8601018A1 (en) 1985-10-16
IT1176886B (en) 1987-08-18
DK163648C (en) 1992-08-17
FI81303B (en) 1990-06-29
IT8423040A0 (en) 1984-10-05
FI851883A0 (en) 1985-05-13
IT8423040A1 (en) 1986-04-05
SE8305478L (en) 1985-04-06
DK249985D0 (en) 1985-06-03
DK163648B (en) 1992-03-23
WO1985001476A1 (en) 1985-04-11
CA1266710A (en) 1990-03-13
JPS61500110A (en) 1986-01-23
FI851883L (en) 1985-05-13
ES536508A0 (en) 1985-10-16
SE439132B (en) 1985-06-03
SE8305478D0 (en) 1983-10-05
DE3468371D1 (en) 1988-02-11

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