CA1130410A - Test method for evaluating faults on printed sheets and webs - Google Patents
Test method for evaluating faults on printed sheets and websInfo
- Publication number
- CA1130410A CA1130410A CA374,041A CA374041A CA1130410A CA 1130410 A CA1130410 A CA 1130410A CA 374041 A CA374041 A CA 374041A CA 1130410 A CA1130410 A CA 1130410A
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- screen
- test
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- field
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Abstract
ABSTRACT
The specification discloses a control strip printed upon a printed product for the purpose of detecting faults comprising a plurality of individual test fields characterized in that four test fields are combined into one test block where one of the test fields is a full tone field and the other three are line screen test fields with different screen angularity. The use of the present control strip allows evaluation of the screen tone value in a print deducting the influence of slip and mackle from the four reflected values or screen tone values in the three line screen test fields.
The specification discloses a control strip printed upon a printed product for the purpose of detecting faults comprising a plurality of individual test fields characterized in that four test fields are combined into one test block where one of the test fields is a full tone field and the other three are line screen test fields with different screen angularity. The use of the present control strip allows evaluation of the screen tone value in a print deducting the influence of slip and mackle from the four reflected values or screen tone values in the three line screen test fields.
Description
ll3~4~n -1 The invention relates to a method of evaluating faults on printed sheets and webs, more particularly slip and/or mackle, by means of a reflec-tance meter and of -test fields, and also to an apparatus for performing said method.
In the offset printing process, two parameters play a part, with others, in d~ciding the tone value reproduction;
one is the full tone ink density and the other is the screen -tone ink density. Of these, the screen tone ink density is the most significant fac-tor for the tone value reproduction of a screened picture. The variation in size of the screen dots in printing as a result of process influences, e.g., by variations in the ductili.ty of the printing ink, by variations in the printed material, in the printing plate copy, in the rubber blanket, in the pressure application, in the develop-ment and also by the mackle in the case of multi-colour offset printing, makes supervision by measuring the screen tone den-sity a necessity so as to make it possible to take steps to optimize the printing process on the basis of the test values measured.
The test and control strips printed on the printed product are an essential component of known cQntrol systems.
Because space on the printed product is strictly dimensioned and expensive, these test or control strips must on the one hand provide, on the smallest possible surface, the greatest possible number of measurable informations as to full tone ink density, screen tone values, development, ink acceptance etc. But on the other hand, the same test or control fields are also required to exhibit a minimum size because a certain test spot diameter is necessary in order to test the integral 7~--1 derlsi.ty of a screell test field by means of a densi-tometer and to obtain a represelltative test value.
Among the known test methods, in most cases only the screen -tone values and full tone ink density vàlues are - evaluated from the test or control strips. Statements as to the increase in the pri.nt due to slip and/or mackle are in most cases made only on the basis of visual assessment of corresponding line screen fields. In the case of the known test methods, no deductions as to percentage value and direc-tion of the slip and/or mackle are drawn from the test strips.
The underlying aim of the invention is to develop a test method whereby no-t only variations as regards the tone value reproduction, but al.so variations in the printed image due to slip and/or mackle are evaluated in magnitude and direction and can be used directly for corrections on.the press.
This aim is achieved by the metrological evaluation of the reflectance values of four test fields, one of which is a.full tone field and the other three are line screen test fields, the screen lines of which exhibit different screen angles, but equal screen width and equal screen tone values in the film, the mathematical evaluation of the screen tone value in the print, deducting the inEluence of slip and mackle, from the measured four reflectance values or from the screen tone values in the three line screen test fields evaluable there-from, and by the selective indication of said values.
By suchamethod according to the invention, both the screen tone values and slip and/or mackle faults can be evalua-ted rapidly for a minimum technical ou-tlay and can be corrected 1~3(~410 1 by an appropriate intervention in the printing process, with the result that a high incidence of mackle and additional press standstill times can be avoided and a high quality of print can be achieved throughout the entire edition.
A particular advantage of this apparatus lies in the fact that not only faults in the tone value reproduction, but also slip and/or mackle faults, can be evaluated in a simple and precise manner by means of a single reflectance meter.
A control strip printed upon a printed product for the purpose of detecting printing faults according to the present invention comprises a plurality of individual test fields characterized in that four test fields are combined into one test block with one of the test fields being a full tone field and the other three being line screen test fields with different screen angularity. By use of the control strip the screen tone value of the printing material may be evaluated.
An exemplary apparatus for performing the method according to the invention and the use of the control strip will be described more fully herein below with reference to an exemplary embodiment illustrated in the drawings, wherein;
Fig. 1 shows a schematic plan of an apparatus for performing the method according to the invention;
Fig. 2 shows a basic version of a test field block, Fig. 3 shows an extended version of the test field block according to Fig. 2; and Fig 4 shows a vectorial representation of the 113(~41~
1 increase in screen tone in the print by slip and/or mackle in the three line screen test fields.
According to Figure 1, a test field block 2 is printed at the start of print on a sheet 1. The test field block 2 is subdivided into four individual test fields, one of which is reali~ed as a full tone test field 3 and the other three as line screen test fields 4, 5 and 6. The screen lines of the line screen test field are aligned parallel to the sheet front edge of the sheet 1. The screen lines of the line screen test field are oriented at an angle of 60 degrees and the screen lines of the line screen test field 6 are oriented at an angle of 120 degrees, each with reference to the screen lines of the line screen test field 4.
Accordingly, the screen lines of the three line screen test fields 4, 5 and 6 exhibit equal angular differences among themselves of 120 degrees in each case. They also exhibit the minimum necessary dimensions for a densitometric measurement.
These test fields are of equal screen width and equal screen tone value in the film.
The line screen test fields 4, 5 and 6 have the disadvantage compared to the dot screen fields which are far more frequently in use, that the additional percentage fraction of a possible slip in the screen tone value increase in the print can be detected and calculated metrologically.
The choice of three such line screen fields 4, 5 and 6 with equal differences of angular inclination among themselves in each case also makes it possible to adopt particularly simple calcuation formulae.
By the arrangement of a further line screen field 41~ `-1 14 between t~e two line screen test fields 5 and 6 in an extended version of the test field block 2, the printer is given the possi-bility of an additional visual check of the printed product as regards slip of the print. The line screen field 1~ s re,al-ized with a smaller width than the remaining test fields 4 to 6, and its screen lines are aligned parallel to the sheet front edge like those of the line screen test field 4. For a visual check the line screen field 14 is used in conjunction with its two adjacent line screen~test fields 5, 6, whil.e the assessment as to whether slip of the print is present is made by a general observation of them and the impression~of any possib.le widening of lines in one or more of the three line screen (test) fields 5, 6, and 14 which is thereby received.
The test field block 2 is suitable for the evaluation of the following pàrameters:
1. Ink density in full tone DV
In the offset printing process, two parameters play a part, with others, in d~ciding the tone value reproduction;
one is the full tone ink density and the other is the screen -tone ink density. Of these, the screen tone ink density is the most significant fac-tor for the tone value reproduction of a screened picture. The variation in size of the screen dots in printing as a result of process influences, e.g., by variations in the ductili.ty of the printing ink, by variations in the printed material, in the printing plate copy, in the rubber blanket, in the pressure application, in the develop-ment and also by the mackle in the case of multi-colour offset printing, makes supervision by measuring the screen tone den-sity a necessity so as to make it possible to take steps to optimize the printing process on the basis of the test values measured.
The test and control strips printed on the printed product are an essential component of known cQntrol systems.
Because space on the printed product is strictly dimensioned and expensive, these test or control strips must on the one hand provide, on the smallest possible surface, the greatest possible number of measurable informations as to full tone ink density, screen tone values, development, ink acceptance etc. But on the other hand, the same test or control fields are also required to exhibit a minimum size because a certain test spot diameter is necessary in order to test the integral 7~--1 derlsi.ty of a screell test field by means of a densi-tometer and to obtain a represelltative test value.
Among the known test methods, in most cases only the screen -tone values and full tone ink density vàlues are - evaluated from the test or control strips. Statements as to the increase in the pri.nt due to slip and/or mackle are in most cases made only on the basis of visual assessment of corresponding line screen fields. In the case of the known test methods, no deductions as to percentage value and direc-tion of the slip and/or mackle are drawn from the test strips.
The underlying aim of the invention is to develop a test method whereby no-t only variations as regards the tone value reproduction, but al.so variations in the printed image due to slip and/or mackle are evaluated in magnitude and direction and can be used directly for corrections on.the press.
This aim is achieved by the metrological evaluation of the reflectance values of four test fields, one of which is a.full tone field and the other three are line screen test fields, the screen lines of which exhibit different screen angles, but equal screen width and equal screen tone values in the film, the mathematical evaluation of the screen tone value in the print, deducting the inEluence of slip and mackle, from the measured four reflectance values or from the screen tone values in the three line screen test fields evaluable there-from, and by the selective indication of said values.
By suchamethod according to the invention, both the screen tone values and slip and/or mackle faults can be evalua-ted rapidly for a minimum technical ou-tlay and can be corrected 1~3(~410 1 by an appropriate intervention in the printing process, with the result that a high incidence of mackle and additional press standstill times can be avoided and a high quality of print can be achieved throughout the entire edition.
A particular advantage of this apparatus lies in the fact that not only faults in the tone value reproduction, but also slip and/or mackle faults, can be evaluated in a simple and precise manner by means of a single reflectance meter.
A control strip printed upon a printed product for the purpose of detecting printing faults according to the present invention comprises a plurality of individual test fields characterized in that four test fields are combined into one test block with one of the test fields being a full tone field and the other three being line screen test fields with different screen angularity. By use of the control strip the screen tone value of the printing material may be evaluated.
An exemplary apparatus for performing the method according to the invention and the use of the control strip will be described more fully herein below with reference to an exemplary embodiment illustrated in the drawings, wherein;
Fig. 1 shows a schematic plan of an apparatus for performing the method according to the invention;
Fig. 2 shows a basic version of a test field block, Fig. 3 shows an extended version of the test field block according to Fig. 2; and Fig 4 shows a vectorial representation of the 113(~41~
1 increase in screen tone in the print by slip and/or mackle in the three line screen test fields.
According to Figure 1, a test field block 2 is printed at the start of print on a sheet 1. The test field block 2 is subdivided into four individual test fields, one of which is reali~ed as a full tone test field 3 and the other three as line screen test fields 4, 5 and 6. The screen lines of the line screen test field are aligned parallel to the sheet front edge of the sheet 1. The screen lines of the line screen test field are oriented at an angle of 60 degrees and the screen lines of the line screen test field 6 are oriented at an angle of 120 degrees, each with reference to the screen lines of the line screen test field 4.
Accordingly, the screen lines of the three line screen test fields 4, 5 and 6 exhibit equal angular differences among themselves of 120 degrees in each case. They also exhibit the minimum necessary dimensions for a densitometric measurement.
These test fields are of equal screen width and equal screen tone value in the film.
The line screen test fields 4, 5 and 6 have the disadvantage compared to the dot screen fields which are far more frequently in use, that the additional percentage fraction of a possible slip in the screen tone value increase in the print can be detected and calculated metrologically.
The choice of three such line screen fields 4, 5 and 6 with equal differences of angular inclination among themselves in each case also makes it possible to adopt particularly simple calcuation formulae.
By the arrangement of a further line screen field 41~ `-1 14 between t~e two line screen test fields 5 and 6 in an extended version of the test field block 2, the printer is given the possi-bility of an additional visual check of the printed product as regards slip of the print. The line screen field 1~ s re,al-ized with a smaller width than the remaining test fields 4 to 6, and its screen lines are aligned parallel to the sheet front edge like those of the line screen test field 4. For a visual check the line screen field 14 is used in conjunction with its two adjacent line screen~test fields 5, 6, whil.e the assessment as to whether slip of the print is present is made by a general observation of them and the impression~of any possib.le widening of lines in one or more of the three line screen (test) fields 5, 6, and 14 which is thereby received.
The test field block 2 is suitable for the evaluation of the following pàrameters:
1. Ink density in full tone DV
2. Screen tone value in the print including slip and/or mackle F (~)
3. Screen tone value in the print including slip and/
or mackle FD (%)
or mackle FD (%)
4. Screen tone value increase~in the print without slip and/or mackle ZD (%)
5. Screen tone value increase in the print due to slip and/or mackle Z5 (%)
6. Slip and/or mackle direction angle ~ according to Figure 4.
In order to measure the test fields 3 to 6 of the 28 test field block 2 by means of a reflectance meter, the sheet 1 113C4~0 ., 1 of the exemplary embodiment is placed upon a test bench 7.
As reflectance meter for this purpose, any freely movable densitometer 8 may be used which may be positioned selective-ly at any desired point of the sheet 1. In the exemplary embodiment the densitometer 8 is arranged slidably across the entire width of the sheet 1 in a test beam 9. The test beam 9 is in turn slidable above the sheet 1 along the entire length of the test bench 7 on two lateral slideways 10, so that any desired point of the sheet 1 can be measured with the densitometer 8.
Obviously, the test beam 9n~ayalso be equipped with a larger number of densitometers 8 for a simultaneous measure-ment of the test fields 3 to 6 of a plurality of test field blocks 2. The densitometers may be arranged stationarily or movably.
In the exemplary embodiment, a computer 11 for associating the measured re:Electance values is provided with a feed-in and read-out keyboard 12 and with an indicator instrument 13 on the left-hand side of the test bench 7.
Because, as is known, one full tone measurement and one screen tone measurement are required in order to form a screen tone value, in a first step of the method in order to evaluate the test field block 2, the reflectance values of the full tone test field 3 and of the three line screen test fields 4, 5 and 6 are measured by means of the densitometer 8.
By this means, three screen tone values are obtained in addi-tion to the full tone density.
Two possible modes of mathematical evaluation, o:E
113~41G~
1di~ferent degrees of complexity, are now available according to choice. According to a first possible mode of evaluation, the screen tone value increase in the print due to slip and/
or mackle ZS and the direction angle ~ are not calculated, but only the screen tone value in the print FD (slip and/or mackle eliminated) is calculated.
The exact ~ethod of determining the screen tone value in the print FD then proceeds as follows.
10The screen tone value in the print FD (slip and/or mackle eliminated) is equal to the sum of the measured screen tone values F (with slip and/or mackle) of those two fields having the lower values, less the measured screen tone value F (with slip and/or mackle) oE the third field, i.e., that with the hlghest value.
In a second possible mode of evaluation, in addition to the above-mentioned screen tone value in the print FD (slip and/or mackle eliminated) the screen tone value increase in the print due to slip and/or mackle ZS is calculated additionally by means of the computer 11 and communicated to the operator through the indicator instrument 13 of the computer 11.
l~hether slip and/or mackle is present emerges from a comparison of the three screen tone values in the print F
calculated. The slip and/or mackle directions in the three rangesC~ = O to 60, 60 to 120 and 120 to 180, and al.so the special casecX = 0, 30, 60, 90, 120, and 150, can be indicated.
By a method of approximation the screen tone value ~ 1~3~41~
, 1 increase due to slip and/or mackle ZS is approximately equal to the calculated screen tone value F of th`at field with the hi.yllest value less the alreacly calculatecl screell tone value FD (slip and mackle eliminated) in the print.
The screen tone value increase due to slip and/or mackle ZS ~ ZS and ZS is a function of the respective slip angle in the individual line screen tes-t fields 4, 5 and 6;
this however was disregarded in the above-stated method of approximation Accordingly, the slip angle must also be evalu-ated and included in the calculation for a precise determina-tion of the screen tone value increase due to slip and/or mackle ZS
Figure 4 illust~ates vectorially the screen tone value increase in the print due to slip and/or mackle ZS ' Z5 and ZS in the three line screen test fields 4, 5 and 6.
Their dependence upon the slip angle ~ can also be seen clearly.
The poin-t of departure for the precise evaluation of the screen tone value increase in the print due to slip and/or mackle ZS is that the screen tone value of a screen -test field - 20 is composed of the sum of the known screen tone value in the film FF, the scrèen tone value increase ~in the print without slip and/or mackle ZD and the screen tone value increase in the print due to slip and/or mackle ZS whilst both the screen tone value increase ln the print without slip and/or mackle ZD and the screen tone value increase in the print due to slip and/or mackle ZS areul~kllowlland ZS is also a function of the slip direction (~. Thus in order to determine the three unknowns Zn ~ Zs and (1, three equations are required, which also in 29 turn presuppose three screen tone test values F (including il3~41(~
1 slip and/or mackle) which are ascertained analogously from the three line screen test fields 4, 5 and 6.
According to -the trigonometrical relationships between S' S4' ZS5 and ZS in figure 4, it is accordingly true of the line screen test field 4:
Also, as hereinbefore described:
F = FF + ZD S and FD F D , thereLore also F = FD + S , therefore ~eferred to the line screen test field 4 F4 = FD + ZS
The formulae for the other two line screen test fields 5 and 6 can be constructed analogously with the above.
The slip angle oCof the vector ZS shown in figure 4 can lié between 0 and 360, depending upon whether the im-pression slips and/or mackles forwards or backwards with re-ference to the direction of travel of the printed material or precisely parallel thereto. But since the densitometer 8 can make no statement as to whether the screen tone value increase due to slip and/or mackle ZS lies to the front or to the rear, to right or to left, but can only indicate absolute values independellt of direction, three regions of calculat~on for wllich dif~erent equations are valid are obtained analogously to the three line screen test fields. Accordingly a statement can be made only as to the angle of the line of application 1 of slip and/or mackle, for which the initial equations, after appropriate conversion, are fed into the computer 11 as a computing programme.
If the highes-t screen tone value F is measured e.g., in the line screen test field 6, then the angle of the Iine of application of the slip and/or mackle definitely lies betweenOC~0 and o~ ~ 60. sy trigonometrical conversion of the above-described equations a precise value is obtained for ~ = arc tan F - F
+ 0;5 F - F
The precise increase due to slip and/or mackle Z evaluated wi-th the aid of the slip angle ~ is then calculated from Z
S sin ~
The equations for the regions two and three are obtained analogously to this first region.
The values for the screen tone value increase in the print due to slip and/or mackle ZS~ of the sllp angle a and of the screen tone values in the print FD`(slip and/or mackle eliminated) which are calculated by the computer 11 in this manner can be made visible in the indicator instrument 13 upon command through the feed-in and read-out keyboard 12 or through an illdication programme of -the computer 11 ! 50 that an immediate corrective intervéntion in the printing process is thereby made possible. Naturally, thls method should be applied individually to tlle different colours of a multiple-colour printing process.
In order to measure the test fields 3 to 6 of the 28 test field block 2 by means of a reflectance meter, the sheet 1 113C4~0 ., 1 of the exemplary embodiment is placed upon a test bench 7.
As reflectance meter for this purpose, any freely movable densitometer 8 may be used which may be positioned selective-ly at any desired point of the sheet 1. In the exemplary embodiment the densitometer 8 is arranged slidably across the entire width of the sheet 1 in a test beam 9. The test beam 9 is in turn slidable above the sheet 1 along the entire length of the test bench 7 on two lateral slideways 10, so that any desired point of the sheet 1 can be measured with the densitometer 8.
Obviously, the test beam 9n~ayalso be equipped with a larger number of densitometers 8 for a simultaneous measure-ment of the test fields 3 to 6 of a plurality of test field blocks 2. The densitometers may be arranged stationarily or movably.
In the exemplary embodiment, a computer 11 for associating the measured re:Electance values is provided with a feed-in and read-out keyboard 12 and with an indicator instrument 13 on the left-hand side of the test bench 7.
Because, as is known, one full tone measurement and one screen tone measurement are required in order to form a screen tone value, in a first step of the method in order to evaluate the test field block 2, the reflectance values of the full tone test field 3 and of the three line screen test fields 4, 5 and 6 are measured by means of the densitometer 8.
By this means, three screen tone values are obtained in addi-tion to the full tone density.
Two possible modes of mathematical evaluation, o:E
113~41G~
1di~ferent degrees of complexity, are now available according to choice. According to a first possible mode of evaluation, the screen tone value increase in the print due to slip and/
or mackle ZS and the direction angle ~ are not calculated, but only the screen tone value in the print FD (slip and/or mackle eliminated) is calculated.
The exact ~ethod of determining the screen tone value in the print FD then proceeds as follows.
10The screen tone value in the print FD (slip and/or mackle eliminated) is equal to the sum of the measured screen tone values F (with slip and/or mackle) of those two fields having the lower values, less the measured screen tone value F (with slip and/or mackle) oE the third field, i.e., that with the hlghest value.
In a second possible mode of evaluation, in addition to the above-mentioned screen tone value in the print FD (slip and/or mackle eliminated) the screen tone value increase in the print due to slip and/or mackle ZS is calculated additionally by means of the computer 11 and communicated to the operator through the indicator instrument 13 of the computer 11.
l~hether slip and/or mackle is present emerges from a comparison of the three screen tone values in the print F
calculated. The slip and/or mackle directions in the three rangesC~ = O to 60, 60 to 120 and 120 to 180, and al.so the special casecX = 0, 30, 60, 90, 120, and 150, can be indicated.
By a method of approximation the screen tone value ~ 1~3~41~
, 1 increase due to slip and/or mackle ZS is approximately equal to the calculated screen tone value F of th`at field with the hi.yllest value less the alreacly calculatecl screell tone value FD (slip and mackle eliminated) in the print.
The screen tone value increase due to slip and/or mackle ZS ~ ZS and ZS is a function of the respective slip angle in the individual line screen tes-t fields 4, 5 and 6;
this however was disregarded in the above-stated method of approximation Accordingly, the slip angle must also be evalu-ated and included in the calculation for a precise determina-tion of the screen tone value increase due to slip and/or mackle ZS
Figure 4 illust~ates vectorially the screen tone value increase in the print due to slip and/or mackle ZS ' Z5 and ZS in the three line screen test fields 4, 5 and 6.
Their dependence upon the slip angle ~ can also be seen clearly.
The poin-t of departure for the precise evaluation of the screen tone value increase in the print due to slip and/or mackle ZS is that the screen tone value of a screen -test field - 20 is composed of the sum of the known screen tone value in the film FF, the scrèen tone value increase ~in the print without slip and/or mackle ZD and the screen tone value increase in the print due to slip and/or mackle ZS whilst both the screen tone value increase ln the print without slip and/or mackle ZD and the screen tone value increase in the print due to slip and/or mackle ZS areul~kllowlland ZS is also a function of the slip direction (~. Thus in order to determine the three unknowns Zn ~ Zs and (1, three equations are required, which also in 29 turn presuppose three screen tone test values F (including il3~41(~
1 slip and/or mackle) which are ascertained analogously from the three line screen test fields 4, 5 and 6.
According to -the trigonometrical relationships between S' S4' ZS5 and ZS in figure 4, it is accordingly true of the line screen test field 4:
Also, as hereinbefore described:
F = FF + ZD S and FD F D , thereLore also F = FD + S , therefore ~eferred to the line screen test field 4 F4 = FD + ZS
The formulae for the other two line screen test fields 5 and 6 can be constructed analogously with the above.
The slip angle oCof the vector ZS shown in figure 4 can lié between 0 and 360, depending upon whether the im-pression slips and/or mackles forwards or backwards with re-ference to the direction of travel of the printed material or precisely parallel thereto. But since the densitometer 8 can make no statement as to whether the screen tone value increase due to slip and/or mackle ZS lies to the front or to the rear, to right or to left, but can only indicate absolute values independellt of direction, three regions of calculat~on for wllich dif~erent equations are valid are obtained analogously to the three line screen test fields. Accordingly a statement can be made only as to the angle of the line of application 1 of slip and/or mackle, for which the initial equations, after appropriate conversion, are fed into the computer 11 as a computing programme.
If the highes-t screen tone value F is measured e.g., in the line screen test field 6, then the angle of the Iine of application of the slip and/or mackle definitely lies betweenOC~0 and o~ ~ 60. sy trigonometrical conversion of the above-described equations a precise value is obtained for ~ = arc tan F - F
+ 0;5 F - F
The precise increase due to slip and/or mackle Z evaluated wi-th the aid of the slip angle ~ is then calculated from Z
S sin ~
The equations for the regions two and three are obtained analogously to this first region.
The values for the screen tone value increase in the print due to slip and/or mackle ZS~ of the sllp angle a and of the screen tone values in the print FD`(slip and/or mackle eliminated) which are calculated by the computer 11 in this manner can be made visible in the indicator instrument 13 upon command through the feed-in and read-out keyboard 12 or through an illdication programme of -the computer 11 ! 50 that an immediate corrective intervéntion in the printing process is thereby made possible. Naturally, thls method should be applied individually to tlle different colours of a multiple-colour printing process.
Claims (7)
- THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
l. A control strip printed upon a printed product for the purpose of detecting printing faults, the said control strip comprising a plurality of individual test fields, characterized in that four test fields are combined into one test block, one of the said test fields being a full tone field and the other three being line screen test fields with different screen angularity, whereby said control strip allows the evaluation of the screen tone value in the printed product deducting the influence of slip and mackle from the four reflected values or screen tone values in the three line screen test fields. - 2. A printing control strip according to claim 1, character-ized in that the line screen test fields are of equal screen width and equal film screen tone value, but of different screen line angle.
- 3. A printing control strip according to claim 1, character-ized in that the screen line angle of the first line screen test field is rotated through 60 degrees in relation to the second line screen test field while the screen line angle of the third line screen test field is rotated through a further 60 degrees in relation to the said first line screen test field.
- 4. A printing control strip according to claims l or 2, characterized in that the screen angle of the three line screen tect fields have equal angular differences of 120 degrees from each other.
- 5. A printing control strip according to claims 1, 2, or 3, characterized in that the lines of one of the three line screen test fields run parallel with the front edge of the printed product.
- 6. A printing control strip according to claims 1, 2 or 3, characterized in that both the full tone field and the line screen fields may be evaluated densitometrically.
- 7. A printing control strip according to claims 1, 2 or 3, characterized in that the test field block is also equipped with a further line screen field designed exclusively as a visual control field which is narrower in width than the line screen test fields and located between two of said screen test fields.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA374,041A CA1130410A (en) | 1977-07-14 | 1981-03-27 | Test method for evaluating faults on printed sheets and webs |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2731842.9 | 1977-07-14 | ||
| DE2731842A DE2731842C3 (en) | 1977-07-14 | 1977-07-14 | Method for determining changes in the halftone value of a color of printed sheets or webs caused by shifting and / or doubling |
| CA307,455A CA1111279A (en) | 1977-07-14 | 1978-07-14 | Test method for evaluating faults on printed sheets and webs |
| CA374,041A CA1130410A (en) | 1977-07-14 | 1981-03-27 | Test method for evaluating faults on printed sheets and webs |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1130410A true CA1130410A (en) | 1982-08-24 |
Family
ID=27165751
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA374,041A Expired CA1130410A (en) | 1977-07-14 | 1981-03-27 | Test method for evaluating faults on printed sheets and webs |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1130410A (en) |
-
1981
- 1981-03-27 CA CA374,041A patent/CA1130410A/en not_active Expired
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| MKEX | Expiry |