EP0255031A2 - Verfahren zur Kontrolle der Punktvergrösserung auf einem Probeabzug - Google Patents

Verfahren zur Kontrolle der Punktvergrösserung auf einem Probeabzug Download PDF

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Publication number
EP0255031A2
EP0255031A2 EP87110599A EP87110599A EP0255031A2 EP 0255031 A2 EP0255031 A2 EP 0255031A2 EP 87110599 A EP87110599 A EP 87110599A EP 87110599 A EP87110599 A EP 87110599A EP 0255031 A2 EP0255031 A2 EP 0255031A2
Authority
EP
European Patent Office
Prior art keywords
printing
dot gain
proof
velocity
press
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.)
Withdrawn
Application number
EP87110599A
Other languages
English (en)
French (fr)
Other versions
EP0255031A3 (de
Inventor
Hirokazu Tanioka
Yasunobu Awazu
Shigeo Ohnogi
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.)
Dainippon Screen Manufacturing Co Ltd
Original Assignee
Dainippon Screen Manufacturing Co Ltd
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 Dainippon Screen Manufacturing Co Ltd filed Critical Dainippon Screen Manufacturing Co Ltd
Publication of EP0255031A2 publication Critical patent/EP0255031A2/de
Publication of EP0255031A3 publication Critical patent/EP0255031A3/de
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F3/00—Cylinder presses, i.e. presses essentially comprising at least one cylinder co-operating with at least one flat type-bed
    • B41F3/18—Cylinder presses, i.e. presses essentially comprising at least one cylinder co-operating with at least one flat type-bed of special construction or for particular purposes
    • B41F3/28—Proof-print presses for relief printing, lithography or intaglio printing, i.e. presses for checking accuracy of printing surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F33/00—Indicating, counting, warning, control or safety devices
    • B41F33/0036—Devices for scanning or checking the printed matter for quality control

Definitions

  • the present invention relates generally to proofing with ink by a proof press, and particularly to a method of controlling so-called dot gain (this word means the undesirable printing of dots as larger areas than their actual size, which is also called “dot spread” or “dot enlargement) on a proof print produced by a proof press.
  • halftone dots are generally apt to spread undesirably as larger areas than their actual size on a printing plate, when a printing plate bearing an image of halftone dots thereon is used in a production press.
  • the amount of such dot gain is much smaller in highlight dots, but is larger in middle tones to deep tones.
  • a print produced by a production press should be produced so as to approach a proof print produced by a proof press, since the proof print is to be an original of printing on a production press.
  • the publication shows several methods for resolving such dot gain effects as follows.
  • a print produced by the proof press is produced so as to approach a print produced by the production press.
  • appropriate printing conditions on the production press must be determined before proof printing on the proof press is carried out.
  • Such printing conditions will be determined on the basis of a printing pressure, an ink viscosity, an atomospheric temperature, humidity and so on, by taking account of various factors peculiar to printing on the production press, e.g. trapping, dot gain, printing stability, image density and so on.
  • an object of the present invention is to provide a novel method of controlling dot gain on a proof print effectively and easily.
  • the aforementioned object is accomplished by the present invention, with a method of controlling dot gain on proof print which includes the steps of: previously printing an object to be proofed including a control patch at different velocities, to obtain proof prints; obtaining dot gain values in respective prints; inputting said dot gain values to a memory of a proof press to be used for proof printing; calculating on the basis of said dot gain values and the printing velocities at which the previous printing is carried out; obtaining at least one approximate expression representing the relationship between the printing velocity and the dot gain value; inputting a desired dot gain value; obtaining an actual printing velocity corresponding to said desired dot gain value on the basis of said approximate expression; and carrying out an actual proof printing of the object at the actual printing velocity.
  • the proof press generally comprises a horizontal base frame 1 and a carriage 3 movable horizontally along the base frame 1 by a motor 31 mechanically connected thereto.
  • the base frame 1 includes a plate bed 5 on which a . desired proof plate 9 is mounted and a paper bed 7 on which a sheet paper 11 to be printed is mounted.
  • a damping mechanism 13 is provided, which mechanism 13 includes a pair of damping rollers by which an appropriate amount of damping water is supplied to the surface of the proof plate 9.
  • an inking mechanism 15 including a plurality of inking rollers 29, by which an appropriate amount of a desired ink is supplied to the surface of the proof plate 9.
  • the carriage 3 comprises within a housing 17 a damping mechanism 19 including a plurality of damping rollers 21, art inking mechanism 23 including a plurality of inking rollers 25 and a blanket cylinder 27. All these mechanisms and the cylinder are movable vertically, and the damping mechanism 19 is engaged with the damping mechanism 13 provided on the base frame 1 when the carriage 3 is moved up to the left end position, whereby an appropriate amount of damping water is transferred to and held by the damping rollers 21 of the damping mechanism 19, then the damping water thus transferred and held is supplied to the entire surface of the proof plate 9 as the carriage 3 travels rightwards along the base frame 1.
  • the carriage 3 rests at the right end portion of the base frame 1, at which the inking rollers 29 are engaged with the rollers 25 of the inking mechanism 23.
  • a desired ink to be used for proof printing is supplied to the rollers 29 and is transferred to and kneaded by the inking mechanism 23 including rollers 25.
  • the ink thus transferred and kneaded is supplied to the entire surface of the proof plate 9 mounted on the plate bed 5 as the carriage 3 travels leftwards along the base frame 1.
  • the carriage 3 After that, the carriage 3 returns to travel rightwards, and the inking mechanism 23 is lifted not to contact with the proof plate 9 nor the paper sheet 11. Simultaneously, the blanket cylinder 27 is lowered to contact with and rotate on the proof plate 9, whereby ink of the image is transferred to the peripheral surface of the blanket 27, and is in turn transferred to the surface of the sheet paper 11 as the carriage 3 travels rightwards.
  • the carriage 3 reciprocates on the base frame 1 by means of the motor 31, by which a desired number of proof prints can be obtained.
  • the control circuit 41 comprises a central processing unit (CPU) 43 including a processing section 45 and a controlling section 47, a random access memory (RAM) 49, which is connected to the CPU 43, including a memory for measured data 51, a memory for designated data 53, a memory for approximate expressions 55 and a memory for printing velocity 57.
  • the controlling circuit 41 further comprises a read only memory (ROM) 59 connected to the CPU 47 and an input-output unit 61 connected also to the CPU 43 respectively.
  • ROM read only memory
  • ROM 59 there stored four kinds of standard velocity of the carriage 3 including the highest and lowest ones. Stored is also functional data, e.g. in the form of a simple equation:
  • the control circuit 41 is connected to a driving control unit 63 through a digital-analog convertor 59 and an ' amplifier 61, and the driving control unit 63 is in turn connected to the motor 31.
  • the driving unit 63 controls the rotation of the motor 31 on the basis of a signal outputted from the input-output unit 61.
  • a keyboard 67 is connected to the control circuit 41 through an interface 65. As shown by broken lines, it may be possible to connect a densitometer 69 to the interface 65 either directly or through keyboard 67 by an operator.
  • a proof print produced by the proof press is measured by the densitometer 69, and the density value measured by it is inputted to the input-output unit 61 either directly or through the keyboard 67 by an operator.
  • the highest velocity Vb is read out from the ROM 59, the carriage 3 is moved at the velocity Vb by means of the motor 31, whereby producing another proof print.
  • the density of the control strip of the proof print is measured by the densitometer 69 in the same manner as above, to obtain the dot gain value D b.
  • the measured value of dot gain Db is inputted to the memory 51 of the RAM 49 through the keyboard 67.
  • a point A denotes the measured value of dot gain when the proof printing is carried out at the lowest velocity Va
  • a point B denotes the measured value of dot gain when the proof printing is carried out at the highest velocity Vb.
  • the functional data is to connect both points A and B by an appropriate curve or line, which will be changed on the conditions under which proof printing is carried out.
  • the moving velocity of the carriage 3 was set at 0.3 m/sec. as the lowest printing velocity Va. Proof printing was made under the conditions that the solid ink density be maintained at 1.60, to obtain ten prints with that velocity.
  • the density area of a 50% screen patch of a control strip of respective prints was measured by the densitometer, to obtain density values. Then, respective density values were substituted to the Murray Davis' equation:
  • the moving velocity of the carriage 3 was set at 0.4 m/sec., 0.5 m/sec. and 0.6 m/sec. respectively, and the average dot gain values at the respective velocities were obtained, which are listed in Table 1.
  • the second example was also carried out under the same conditions as the first example.
  • the functional data stored in the ROM 59 was in the form of a cubic equation:
  • the relationship between the printing velocity and the dot gain value is represented as a curve shown in Fig. 6.
  • the approximate expression is stored in the memory 55.
  • the desired printing velocity is read out from the memory 57, which is outputted to the driving unit 63 through the digital-analog convertor 59 and the amplifier 61.
  • the motor 31 is driven under the control of the driving unit 63, and accordingly the carriage 3 moves at the corresponding velocity, whereby desired amount of dot gain can be obtained.
  • Example 1 the approximate expression is represented as a kinked line, it may be obtained by interpolation on the basis of the respective points of the highest and lowest velocities and intermediate points therebetween.
  • Example 1 the approximate expression is obtained on the basis of four kinds of printing velocities, it can be done on the basis of only the highest and lowest printing velocities velocity.
  • the amount of dot gain is obtained by measuring the halftone density of a control strip, but it may be applicable that, instead of measurement by the densitometer, the dot gain value is directly obtained by a dot-gain meter, or that comparative contrast value K expressed by the formula: . is used instead of the dot gain value.
  • any value convertable to the dot gain value can be available in the method according to the invention.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Quality & Reliability (AREA)
  • Inking, Control Or Cleaning Of Printing Machines (AREA)
  • Rotary Presses (AREA)
  • Facsimile Image Signal Circuits (AREA)
EP87110599A 1986-07-22 1987-07-22 Verfahren zur Kontrolle der Punktvergrösserung auf einem Probeabzug Withdrawn EP0255031A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP173467/86 1986-07-22
JP61173467A JPS6328649A (ja) 1986-07-22 1986-07-22 オフセツト校正機におけるドツトゲイン量の制御方法

Publications (2)

Publication Number Publication Date
EP0255031A2 true EP0255031A2 (de) 1988-02-03
EP0255031A3 EP0255031A3 (de) 1989-05-10

Family

ID=15961018

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87110599A Withdrawn EP0255031A3 (de) 1986-07-22 1987-07-22 Verfahren zur Kontrolle der Punktvergrösserung auf einem Probeabzug

Country Status (2)

Country Link
EP (1) EP0255031A3 (de)
JP (1) JPS6328649A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0490093A1 (de) * 1990-12-13 1992-06-17 MAN Roland Druckmaschinen AG Verfahren zur Steuerung der Farbgebung von Druckerzeugnissen
EP0518559A1 (de) * 1991-06-11 1992-12-16 Scitex Corporation Ltd. Verfahren und Vorrichtung zur Erzeugung eines Kontrollstreifens

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4015524A (en) * 1975-09-17 1977-04-05 Pantone, Inc. Proofing press
FR2425939A1 (fr) * 1978-05-16 1979-12-14 Dainippon Screen Mfg Presse a epreuves lithographiques
EP0136542A2 (de) * 1983-09-20 1985-04-10 Kollmorgen Corporation Verfahren zum Steuerung des Farbendruckes, mit Verwendung von Halbton-Kontrollflächen

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4015524A (en) * 1975-09-17 1977-04-05 Pantone, Inc. Proofing press
FR2425939A1 (fr) * 1978-05-16 1979-12-14 Dainippon Screen Mfg Presse a epreuves lithographiques
EP0136542A2 (de) * 1983-09-20 1985-04-10 Kollmorgen Corporation Verfahren zum Steuerung des Farbendruckes, mit Verwendung von Halbton-Kontrollflächen

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0490093A1 (de) * 1990-12-13 1992-06-17 MAN Roland Druckmaschinen AG Verfahren zur Steuerung der Farbgebung von Druckerzeugnissen
EP0518559A1 (de) * 1991-06-11 1992-12-16 Scitex Corporation Ltd. Verfahren und Vorrichtung zur Erzeugung eines Kontrollstreifens
US5636330A (en) * 1991-06-11 1997-06-03 Scitex Corporation Ltd. Method and apparatus for creating a control strip

Also Published As

Publication number Publication date
EP0255031A3 (de) 1989-05-10
JPS6328649A (ja) 1988-02-06

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