PCT WORLD INTELLECTUAL PROPERTY ORGANIZATION International Bureau

INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)

(51) International Patent Classification ~* (11) International Publication Number: WO 89/1 B41F 33/00 Al

(43) International Publication Date : 2 November 1989 (02.1

(21) International Application Number: PCT/GB89/00442 (81) Designated States: DE, FI.

(22) International Filing Date : 25 April 1989 (25.04.89)

Published

With international search report.

(30) Priority data: Before the expiration of the time limit for amendin

8809853.8 26 April 1988 (26.04.88) GB claims and to be republished in the event of the recei amendments.

(71) Applicant: ALLEN-BRADLEY INTERNATIONAL LI¬

MITED [GB/GB]; 45 Station Road, Henley-on-Thames, Oxon RG9 1LQ (GB).

(72) Inventors: COMERFORD, Ronald, Eric ; 50 Magpie Way,

Winslow, Bucks MK18 3JT (US). McKENZIE, Ian, Wil¬ liam ; 73 Winslow Road, Wingrave, Bucks HP22 4QB (US).

(74) Agents: HUSTWITT, Philip, Edward et al. ; Hustwitt & Co., St. George's House, 44 Hatton Garden, London EC1N 8ER (GB).

(54) Title: CONTROL APPARATUS

(57) Abstract

A control and visual display panel (1) for controlling the ink density applied to a zone of a page in a printing operati includes membranes (2) and (3) providing continuous pressure pads overlaying two similar series of side-by-side touch pa switches (11) and (12). Between the two membranes (2) and (3) is a series of LEDs providing a visual display (6), there being t LEDs corresponding to each individual touch panel switch. Electronic control means stores information defining eight zones a printed page for several different page widths. The operator can select a desired page width and selected indicator means in t visual display (6) are then energised to represent the boundaries of zones on the printed page of the selected width. When it is d sired to change the ink density fed to a particular zone of this page, either membrane (2) or membrane (3) is pressed to increase decrease the ink density in the particular zone, and the indicating means of the visual display (6) within the selected zone are e ergised to show the operator the zone in which the change is being made. There is also described control apparatus including a justing means for adjusting the ink supplied by respective ink feeding means in accordance with the change in ink density quired in a zone of a printed page of the selected width following operation of the control and visual display panel (1).

FOR THE PURPOSES OFINFORMAΗON ONLY

Codes used to identify States party to the PCT on the front pages of pamphlets publishing international appli¬ cations under the PCT.

AT Austria FR France ML Mali

AU Australia GA Gabon MR Mauritania

BB Barbados GB United Kingdom MW Malawi

BE Belgium HU Hungary NL Netherlands

BG Bulgaria IT Italy NO Norway

BJ Benin JP Japan RO Romania

BR Brazil KP Democratic People's Republic SD Sudan

CF Central African Republic of Korea SE Sweden

03 Congo KR Republic of Korea SN Senegal

CH Switzerland Γ Liechtenstein Sϋ Soviet Union

CM Cameroon LK Sri Lanka TD Chad

DE Germany, Federal Republic of U Luxembourg TG Togo

DK Denmark MC Monaco US United States of America

El Finland MG Madagascar

CONTROL APPARATUS

This invention relates to control apparatus, and will be described particularly in relation to the quality control of printing. However the control apparatus which will be described has two distinct and independent features, at least one of which may be used in the control of processes other than printing processes.

Printing presses for printing newspapers are generally designed to print on a paper web of the maximum width to be used for a sheet of newsprint. The control of the mechanical integers effecting the printing is conventionally done using electronic control means designed to control printing on a particular width of the paper web fed to the printing press.

However, in order to obtain the maximum benefit from an investment of millions of pounds in a modern printing press, the proprietors naturally desire to make the maximum use of this printing press, and in order to do this they need to employ the press to print other publications, which may be other newspapers of one or more different sheet sizes, or even a magazine of yet another different sheet size. Accordingly the printing press is required to be capable of handling several different widths of paper web, for example 4 or even 6 different web widths.

The particular aspect which gives rise to problems in a printing press required to be capable of handling several different web widths is the quality control of the printed page. Quality control is conce'rned with the quantities of ink fed to the various parts of the paper web so that the correct quantity of ink is applied to each longitudinal zone of the web as this is passed over the printing cylinder.

The printing press incorporates a number of ink feed means, generally ink screws, which are fixed in position and which each feed ink at a selected rate to a portion of the width of the paper web. Usually there are eight ink screws capable of feeding ink across a paper web of the maximum width for which the printing press is designed.

In effecting quality control the operator examines a printed page arranged in a position corresponding to the direction of advance of the paper web through the printing press, and assesses the quality in terms of zones extending longitudinally of the paper web from which the printed page is produced. Conventionally, there are eight such longitudinal zones, and in newspapers of large page size (i.e. broadsheet) these zones tend to correspond to eight columns of text across the printed page.

When the press is operating to print on a web of the maximum width for which the press is designed, the eight zones of the printed sheet in which the operator checks for quality of printing correspond to the areas of the paper web to which ink is fed by the eight individual ink screws. However, when a paper web of narrower width than the maximum is being printed, the eight zones which the operator is inspecting on the printed page no longer correspond to the areas fed by the eight ink screws. Accordingly a different quality control mechanism is required for each different width of paper web to be used on the printing press. It is a main object of the present invention to provide control apparatus which may be used in the quality control of printing on paper webs of a plurality of different widths.

In providing such control apparatus, two problems arise. One problem is to enable the operator to make the correct adjustment in a simple and reliable manner. The other problem is to ensure that any correction which the operator makes for a particular zone of the printed page is addressed to the correct ink screw, or screws .

Accordingly it is a further object of the present invention to provide a control means having an operator interface which is simple and easy to use. A control means in accordance with this aspect of the present invention is capable of being used in other processes than printing processes, for example in the shaping or stamping of articles from metal sheet, and the claims to this control apparatus are accordingly not limited to use in a printing press.

It is a still further object of the present invention to provide control means which automatically utilise an ink density change signal to adjust one or two ink feeding means, which may be ink screws, ink blades or ink jets, in a manner to effect a desired change in the quality of printing in a particular zone of the printed page, irrespective of the width of the paper web which is being printed. According to a first aspect of the present invention there is provided control apparatus comprising similar first and second series of switches, a series of energisable indicating means each of which corresponds to a switch in at least one of the said series of switches, and electronic control means including means for storing information defining a plurality of zones in an article or process to be controlled, means for energising selected indicator means such that the series of indicating means

represents the zones and the boundaries between the said zones, and means responsive to the actuation of a switch located between switches corresponding to zone boundaries for producing a signal for adjusting a function of the article or process within a selected zone.

Preferably the means responsive to the actuation of a switch also inverts the state of the indicating means within the selected zone as a means of visual operator feedback. However a separate visual or audible indication of a switch operation can be given.

Advantageously the electronic control means includes means for storing information defining a plurality of zones in a plurality of different articles or processes to be controlled, and means for selecting the information relative to a desired article or process for application to the series of indicator means and switches.

As already stated the present invention has particular application in the printing industry. More specifically in accordance with this aspect of the present invention, therefore, there is provided control apparatus for use by a printing press operator to control the ink density applied to a zone of a page in a printing operation, the apparatus comprising a first series of pressure operable switches for operation when the ink density is to be increased, a second series of pressure operable switches for operation when the ink density is to be decreased, a series of energisable indicating means each corresponding to a switch in at least one of the said series of pressure operable switches, and electronic control means including means for storing information defining a plurality of zones on a printed page, means for energising selected indicator means to represent the

boundaries of said zones, and means responsive to the actuation of a switch located between switches corresponding to zone boundaries for adjusting ink feeding means feeding ink to a selected zone and simultaneously energising the indicating means within the selected zone.

In the preferred control apparatus in accordance with this first aspect of the present invention the electronic control means includes means for storing information defining a plurality of zones or columns in a plurality of newspaper pages of different widths, and means for selectively applying the information defining a newspaper page of a particular width to the series of indicator means. Advantageously each series of switches is covered by a smooth membrane pressure on which operates a switch located beneath the membrane.

Each switch in each of said first and second series may correspond to one or more indicator means in the series of energisable indicator means.

The control apparatus in accordance with this aspect of the present invention preferably further includes a pair of switches, each separate from but corresponding to one of the said first and second series, and each operable to effect an adjustment equivalent to a similar actuation of at least one switch in all of the zones defined in the corresponding series of switches.

The first and second series of switches are each continuous series of side-by-side switches so that the application at a position anywhere between the ends of the series of a pressure sufficient to operate a switch will result in at least one switch in the series being operated.

In summary and by way of example of a preferred embodiment in accordance with this first aspect of the invention, a linear touch panel for controlling the ink density in eight columns or zones of variable width on a printed newspaper page comprises two rows or tracks of push-button switches distributed along the length of the touch panel at a pitch of approximately 5 mms. One row of buttons forms an "Increase" pad, and the other row of buttons forms a "Decrease" pad, each approximately 450 mms long and containing 90 buttons per pad. An LED bar indicator runs between these two pads. The LED bar may comprise the same number of discrete LEDs as there are buttons in each of the pads, in which case the pitch of the LEDs is the same as that of the pushbuttons, or there may be a multiple, for example 2, of LEDs for each pushbutton, in which case the pitch of the LEDs is correspondingly reduced.

Visually the front surface of the touch panel presents a continuous pad for each of the two rows of buttons, as is shown in Figure 1 of the accompanying drawings, to which reference will be made in the detailed description which follows. In the newspaper ink density control application which will be described, the length of the touch panel runs across the control desk in front of the operator. Two touch panels are used in line to control the 16 ink screws associated with the columns or zones of two adjacent broadsheet pages. By means of software, the operational column boundaries are set and indicated by the row of LEDs. One or two "Increase" and one or two "Decrease" pushbuttons and the associated LED or LEDs are disabled between adjacent zones to give and indicate zones matching the newspaper columns or zones. The software then allows any of the "Increase" or "Decrease"

pushbuttons within a zone to initiate appropriate operation of the corresponding ink control. Touching the "Increase" pad within the zone increases ink density, touching the "Decrease" pad within the zone decreases ink density. Separate "Increase" and "Decrease" buttons at each end of the pad may be operated to increase or decrease the ink density across all the columns or zones simultaneously.

According to a second aspect of the present invention there is provided control apparatus for controlling the density of ink used in printing a zone of a printed page on a paper web fed to a printing press, comprising a plurality of ink feeding means for supplying ink to similar widths (w) of the paper web, and adjusting means for adjusting the ink supplied by respective feeding means in accordance with the proportion of a zone where an ink density change is required which is fed by the respective feeding means.

More specifically in accordance with this aspect of the present invention there is provided control means for controlling the density of ink used in printing a zone of a printed page on a paper web fed to a printing press, comprising a plurality of ink feeding means for supplying ink to similar widths (w) of the paper web, and adjusting means for adjusting the ink supplied by respective feeding means in accordance with the ink density required in a zone of a printed page which zone has a width (z) equal to or less than the width (w) of paper web supplied with ink by a single ink feeding means, the adjusting means receiving an ink density control signal (I) representative of the change in ink density required in the zone of width (z) of which a width (y) is supplied with ink by a first ink feeding means and a width (z - y) is supplied with ink by a second ink

feeding means, and adjusting the ink supplied by the first ink feeding means by an amount corresponding o — —_£ and the ink supplied by the second ink feeding

W T _._. /_ ___\ means by an amount corresponding to — w In the embodiment of this second aspect of the present invention which will be described control apparatus, for use in controlling the ink fed by a series of ink feeding means in a printing process in which the page to be printed may be of a width different from the total width to which ink may be fed by the total of the ink feeding means, comprises means for determining scan values representative of the amount of ink to be applied in each of a predetermined number of scan widths making up the width of the page fed by an individual ink feeding means, means for determining an average of the scan values for each individual ink feeding means and for setting the ink feeding means in accordance with the average value, means dividing the page into a number of similar zones each having the same number of scan widths, means for generating an ink density change signal for a selected zone on the page, means identifying the one or two ink feeding means which are feeding ink to the selected zone, means for deriving an adjustment for the setting of each of the said one or two ink feeding means from the ink density change signal for the selected zone by a method which includes deriving the product of the quotient of the ink density change signal divided by the number of scan widths fed by each ink feeding means multiplied by the number of scan widths within the selected zone which are fed by the respective ink feeding means.

The present invention will be further understood from the following detailed description of a preferred embodiment thereof which is made, by way of example,

with reference to the accompanying drawings, in which:-

Figure 1 is a plan view of a linear touch panel which is an operator interface for use in quality control in the printing of a newspaper, Figure 2 is a view on an enlarged scale of a portion of the linear touch panel of Figure 1 with the cover removed to show a portion of each of the two series of touch panel switches,

Figures 3, 4 and 5 are enlarged views of similar portions of the linear touch panel of Figure 1, Figures

3 and 4 displaying different zone widths, and Figure

5 displaying an ink control change being effected in one zone of the Figure 4 embodiment,

Figure 6 _^ shows the juxtaposition of a printed newspaper page to the linear touch panel of Figure 1,

Figure 7 shows a programme for operating the linear touch panel of Figure 1,

Figure 8 shows a practical arrangement in which two similar linear touch panels in accordance with Figure 1 are arranged in side by side relation to check the quality of a full broadsheet double page of a newspaper,

Figure 9 shows a practical arrangement in which two similar linear touch panels in accordance with Figure 1 are arranged in side by side relation to check the quality of two double pages of a tabloid newspaper,

Figure 10 illustrates diagrammatically the positions of ink feeding means feeding a maximum width of paper web and a narrower paper web,

Figure 11 is a box schematic diagram of control apparatus in accordance with the present invention for effecting an adjustment to the ink density applied to a zone of a paper web,

Figure 12 shows a programme for use in operating the apparatus of Figure 11 and

Figure 13 is a greatly enlarged, exploded diagrammatical illustration showing in cross-section the construction of the pressure pads and series of side-by-side switches constituting the linear touch panel of Figures 1 and 2.

In the drawings the same or similar parts are designated by like reference numerals. Referring to Figure 1 of the accompanying drawings, there is indicated generally by the reference numeral 1 a control and visual display panel in accordance with the present invention for use by an operator to adjust the ink density used in a printing press which is printing newspapers.

The control and visual display panel 1, which is conveniently referred to as a linear touch panel, includes two membranes 2 and 3 overlaying two similar series of side-by-side touch panel switches. Each membrane 2 or 3 constitutes a continuous pressure pad.

The application to membrane 2, at any part of the membrane 2, of pressure sufficient to operate a touch panel switch in the first series will result in an increase in the ink density applied to a zone of the paper corresponding to the operated touch panel switch. Similarly the applciation to membrane 3 of pressure sufficient to operate a touch panel switch in the second series will result in a decrease in the ink density applied to the zone of the paper corresponding to the operated touch panel switch. Membranes 2 and 3 thus constitute separate pressure pads for initiating respectively increases and decreases in the quantity of ink applied. Located in line with the membranes 2 and 3 are

similar portions of membrane 4 and 5 overlaying further touch panel switches.

Application of pressure to membrane 4 sufficient to operate a touch panel switch beneath membrane 4 will cause an increase in ink density across the whole width of the page being printed. Similarly, actuation of a touch panel switch below membrane 5 by pressure applied to membrane 5 will result in a decrease of ink density applied across the full width of the page being printed.

Situated between membranes 2 and 3 is a series of individual light emitting diodes (LEDs) which provide a visual display within the area denoted by the reference 6. In Figure 2 of the accompanying drawings there is shown the arrangement of touch panel switches 11 and 12 which are respectively beneath the membranes 2 and 3 of Figure 1. The touch panel switches 11 and 12 are arranged in two series, one series of switches 11 and a second series of switches 12, at a pitch of one fifth of an inch (approximately 5mm).

There are 90 touch panel switches 11 or 12 in each of the series of switches which are arranged respectively below membranes 2 and 3.

The physical construction of the linear touch panel is illustrated diagrammatically in Figure 13 in cross-section through membrane 2 and touch panel switches 11. A facia surface 72 which is flexible and resistant to chemical and mechanical damage constitutes the membrane 2 and covers an upper switch membrane 73. The upper switch membrane is effectively a flexible printed circuit board having conducting upper switch contacts 74 for the side-by-side switches

11 and associated electrical connections carried on a flexible insulating sheet -75, for example of polyester, polypropylene or polyurethane. A lower switch membrane 76 is formed by a similar flexible

printed circuit board comprising an insulating sheet 77 and lower switch contacts 78. The lower switch membrance 76 is supported on a metal plate 79, and the upper and lower switch membranes 73 and 76 are separated by a spacer 80 which is an insulating sheet having apertures 81 enabling contact to be made between the upper contact 74 and lower contact 78 of a switch 11 to which an operating pressure is applied. The construction of the touch panel switches 12 beneath membrane 3 are similar.

Also shown in Figure 2 is an array 13 of LEDs 14 which provide the visual display which appears in the area 6 of Figure 1. As shown in Figure 2 there are two LEDs 14 for each touch panel switch 11 or 12. However the arrangement may be such that there is a single individual LED or other indicating means, for example a liquid crystal, for each touch panel switch in both the first and second series of touch panel switches 11 and 12. Together with the control and visual display panel 1, the operator has a keyboard (which is known in itself and will not be described or illustrated herein) enabling him to enter into the control panel data for any desired width of newspaper page. The keyboard also enables him to call up the ink controls for any page being printed anywhere in the printing press. The facility to call up any page of a multi- section, multi-page newspaper on a control panel is also well known and will not be described here. There will now be described with reference to Figures 3 to 5 the visual display which is given to an operator using the control and visual display panel 1 to control the ink density applied to different zones on a newspaper page. Figures 3 to 5 are enlarged views of a portion of the control and visual display panel 1 such that individual LEDs 14 are shown.

In Figures 3 and 4 there are shown two visual displays representing different zone widths corresponding to different widths of a newspaper page. The boundaries between eight zones across the web or ultimate page of the newspaper are shown by the illuminated LEDs 14 which are represented as black rectangles between the white unilluminated LEDs 14. In Figure 3 there are ten unilluminated LEDs 14 denoting one zone between the illuminated boundary LEDs 14. The touch panel switches 11 and 12 corresponding to illuminated LEDs 14 are disabled while the corresponding boundary LEDs are illuminated.

By simply pressing a key on the keyboard • to change the web width data, which, as will be described later, includes a web width and a margin width, the operator obtains the visual display shown in Figure 4. The boundary LEDs 14 which are illuminated are separated by eight unilluminated LEDs 14 indicating the narrower zones on a newspaper page of narrower width. In each of Figures 3 and 4 a first boundary, or margin on the printed page, is indicated by an arrow 15 which is in a similar position on both Figures 3 and 4. The boundaries between adjacent zones across the wider web represented in Figure 3 are shown by arrows 16, 17 and 18. However, immediately upon pressing a key to change the web width data, these second, third and fourth boundary indications move to the positions of the arrows 19, 20 and 21 in Figure 4. In fact the reduction in web width, and consequentially in zone width, is such that the section of control and display panel which is shown in both Figures 3 and 4 includes in Figure 4 an additional boundary denoted by the arrow 22 and two additional illuminated LEDs 14. It will further be noted that specific LEDs denoted by X, which in Figure 3 were in the third zone of the newspaper page, are in the fourth zone of the narrower newspaper page illustrated

in Figure 4.

Assuming now that the operator utilising the control and visual display panel 1 to control the ink density applied to the narrower page of Figure 4 observes that a change in the ink density is required in the third zone between the boundary LEDs 14 denoted by the arrows 20 and 21, the operator then presses either membrane 2 if an increase in ink density in this third zone is required or membrane 3 if a decrease in ink density is required. Actuation of any touch panel switch between the touch panel switches corresponding to the boundary LEDs 14 at the arrows 20 to 21 will cause all the LEDs 14 related to the third zone to invert so that the operator will get the visual display shown in Figure 5. The boundary LEDs at the arrows 20 and 21 will cut out, while all the LEDs 14 between the boundary LEDs at the arrows 20 and 21 will illuminate showing the operator that a change in ink density control is being made in that third zone in which he has applied pressure to one or the other of the membranes 2 and 3.

As shown diagrammatically in Figure 6 the control and display panel 1 is arranged on a desk in such a position that the printed page of a newspaper which is being checked is placed immediately above it. Accordingly the operator can see where a change in ink density is required, for example by a fainter patch at 25 on a page 26, and the operator then actuates the increase membrane 2 at a position 27 aligned with the fainter patch 25 and in the third zone. The linear touch panel 1 of Figure 6 is the mirror image of linear touch panel 1 of Figure 1, because in Figure 6, the right hand page of a broadsheet double page is being examined. As will be seen from Figure 8, the linear touch panel 1 of Figure 1 is used to examine a left

hand page of a broadsheet double page.

The basic instructions concerning the operation of the hardware described above are effected in accordance with a basic programme set out in Figure 7. The control and visual display panel 1 is being continuously operated in accordance with the programme of Figure 7.

From the width data stored in electronic memory for a particular paper web to be used as newsprint, there is first selected the data regarding the margin to the printed page, and the position of the LEDs 14 denoting the margin is calculated and stored in an LED array.

The stored parameters for a web width are the margin width, which is determined in increments of 0.2 inches (approximately 5mm), whereas the zone widths are stored in terms of hundredths of an inch. In consequence the first calculation by the computer programme of the position of the LEDs 14 denoting the margin is directly related to the spacing of the LEDs 14. However the calculation of the zone widths has to include a division of the hundredths by 20 in order to convert to the same increment used for the margin. This may result in a remainder which is stored and added on to the next width parameter for the calculation of the next zone. In this way adjacent zones may be denoted by different numbers of LEDs 14, for example there may be nine LEDs in one zone and ten in an adjacent zone. When the computer programme has performed the steps of calculating the margin LED position and storing it in the LED array, and has then calculated the eight boundary positions and similarly stored the boundary positions in the LED array, there will be stored in

the memory the data for the eight zones corresponding to the true physical width of eight zones on a page of a newspaper printed on the appropriate width of web. These are the steps denoted by 30, 31, 32 and 33 in Figure 7.

Once this data has all been stored in the LED array, this stored information is written into the LEDs 14 in the control and visual display unit 1 so that the operator has a display showing eight zones corresponding to the true physical width of a newspaper page for the examination and ink density adjustment to be made as described above with reference to Figure 6.

The control programme now reads the positions of all the touch panel switches 11 and 12. This is step 35 in Figure 7.

If no touch panel switches have been operated, no further action is taken. However, if either linear membrane 2 or 3 has been pressed and some touch panel switches are consequently operated, the programme checks which zones these switches are in and sets the zone increase or decrease bits to the ink density controller for that zone. These are steps 36A and 36B. Simultaneously the programme inverts the status of all LEDs in any zone or zones, and the boundaries to the zone or zones where an ink density change signal is being generated. This is step 37 and results in the visual indication to the operator that a change is being made which has been described with reference to Figure 5.

As stated, the programme of Figure 7 is continuously repeated, so that any selection by the operator of a different page width results in a different margin LED position and different zone

boundary positions being stored in the LED array and then written from the LED array into the series of LEDs to give the operator immediately the changed visual indication for the different page width. Figure 8 of the accompanying drawings, shows the practical arrangement in which a centre line 27 of a broadsheet double page 26,26 of a newspaper is aligned with a pair of linear touch panels 1 for the operator to inspect and make ink density control changes to get the necessary quality control.

If a tabloid newspaper is being printed, then two tabloid double pages 28,28 each having a centre line 29 are checked by a pair of linear touch panels 1 as shown in Figure 9 of the accompanying drawings. In this case each zone which is being checked by the operator and the boundaries of which are denoted by illuminated LEDs in the linear touch panels 1 are zones extending laterally across the tabloid pages.

The description thus far shows how an ink density change signal is produced. This signal has then to be fed to the appropriate ink density controller or controllers for adjusting the setting or ^' settings of the ink screws which are feeding ink to the zone for which the ink density change signal has been produced.

The manner in which the ink screws relate to different widths of paper web fed to the printing press is indicated diagrammatically in Figure 10 where a centre line (41) indicates the centre line of the press. For a paper web (42) of maximum width from which four broadsheet pages may be printed, the ink screws are arranged in batches of eight ink screws so that there are a total of 32 ink screw widths (w) , and, with each broadsheet page divided into eight

zones, there will be 32 zone widths (z) so that a zone width corresponds exactly to an ink screw width.

The ink screws are arranged symmetrically with two batches of eight ink screws on either side of the centre line (41) of the press. The positions of each batch of eight ink screw widths are denoted by the reference 8w in Figure 10.

Also shown in Figure 10 is a paper web (43) of a width substantially less than the maximum web width so that the eight zone widths of each printed page are equivalent to only six screw widths.

As already indicated the full broadsheet page width is fed ink by eight ink screws. The area, i.e. longitudinal strip of the paper web, fed by each screw is divided into eight scan widths which are scanned individually to give eight scan width values which may fall anywhere in a range from 0 to 99. The eight scan width values for each ink screw are then totalled and averaged, and that ink screw j.s set to the number obtained by this averaging process.

As will have been appreciated from the earlier description, the actuation of any touch panel switch 11 or 12 within a zone produces an ink density change signal from that touch panel switch and all the other touch panel switches 11 or 12 wh.ich lie within that zone. Thus the same INK DENSITY INCREASE signal is produced from all the touch panel switches 11 within the zone if the membrane 2 is pressed, and the same INK DENSITY DECREASE signal is produced by all the touch panel switches 12 within the zone if the membrane 3 is pressed.

However it is only in the case when a full width of paper web is being printed so that each zone corresponds to an area fed by an ink screw, that the

INK DENSITY INCREASE or INK DENSITY DECREASE signal can be applied, without modification to a single ink screw. Consequently there is further provided, in accordance with the present invention, control apparatus for relating the zones for different paper widths to different ink screws and for modifying the INK DENSITY INCREASE and INK DENSITY DECREASE signals and applying the modified signals to the relevant ink screws. It has already been stated that in the present example, there are eight scan widths for each ink screw. This figure is stored. A series of numbers each representing the ink density in one scan area is also stored. Another number is equal to the number of scan widths which correspond to a zone width. The computer programme for modifying and applying INK DENSITY INCREASE or DECREASE signals includes means for examining the INK DENSITY INCREASE or DECREASE signals and recognising the ink screws to which they relate. In applying these signals the control apparatus has to derive a figure for the amount of the change to be applied to any ink screw dependent upon the relationship between the zone where the ink density is to be changed and the areas which are fed by the ink screws. This is done by checking the number of scan widths for each screw falling within the zone where the change is to be made and then applying this figure, as a proportion of the total number of scan widths per screw, to the ink density change signal.

Consequently, in this simplest case, where a full width web is being printed and the eight zones on the printed page correspond to the areas fed by the ink screws, the number of scan widths in the zone which are fed by any screw will be the total number

of scan widths -and the whole signal will be applied to vary the number at which that particular ink screw is set. In other words, an INK DENSITY INCREASE signal of ten points for the zone will be applied as a ten-point increase to the relevant ink screw setting.

In another simple example, when there are eight scan widths for each ink screw width and four scan widths within each zone width on the printed page, each screw is feeding two zones. In the case where only one of these zones needs a change of ink density, the INK DENSITY INCREASE or INK DENSITY DECREASE signal which is fed from the linear touch panel to the ink screw is halved as a result of multiplication by 4 and division by 8.

In a lithographic printing process, however, the ink tends towards the zone where it is required so that the ink density averages out over the full width of the web. In a further example each ink screw feeds ink to the ten scan areas and the printed page is divided into eight zones of a width equal to seven scan widths. Consider a zone where an INK DENSITY INCREASE signal of 10 points is generated by the operator of the linear touch panel, and where five of the scan widths within the zone fall within the area fed by one ink screw and the other two of the scan widths within the zone fall within the area fed by a second ink screw.

In this example the control apparatus will generate MODIFIED INK DENSITY INCREASE signals for the two ink screws as follows:-

First ink screw 10 points x 5 * 10 - 5 points. Second ink screw 10 points x 2 * 10 = 2 points.

Accordingly the setting of the first ink screw

is adjusted by 5 points, while the setting of the second ink screw is adjusted by only 2 points.

Calculations for the changes to be applied to individual screws have been discussed above in terms of scan widths. However, this is only one convenient and simple way in which calculations can be done and the basic calculation is based on the actual width (w) fed by each ink screw and the actual width (z) of a zone being scanned. Of the width (z) a portion (y) may be fed ink from one ink screw while the remaining width of the zone (z - y) is fed ink from an adjacent ink screw. w, z and y may be a number value measured to any number of decimal places. When an ink density change signal (I) for a particular zone is received, this signal will be modified for application to an ink screw by multiplying by y/w or (z - y)/w for the general situation. Application of the particular numbers which have been given in the numerical examples preceding this more general discussion, to these formulae, will give the results mentioned in those numerical examples.

In Figure 11 there is illustrated in block diagram form apparatus for controlling an ink density change for a zone on a printed page.

An operator interface 51 for adjusting the zone set or zone boundary values may be the linear touch panel 1 described above as the first aspect of the present invention. However, other means for adjusting zone set values may be used as the operator interface 51, for example a keyboard where the operator simply selects a numerical figure representing the width of a particular zone.

The adjusted zone set values are fed to electronic

calculating means 52 which calculates, from the zone set values and the physical arrangement of the ink screws at the printing press, the relationship between the individual zones on the paper web and the individual ink screws. There are thus derived in calculating means 52 the proportioning values to be applied to an INK DENSITY CHANGE signal for each ink screw, and the proportioned signal is utilised in ink density controller 53 which controls the ink fed by the individual ink screws 54. The basic steps carried out in the electronic calculating means 52 are set out in the form of a computer programme in Figure 12. The programme of Figure 12 is continuously repeated.

All the calculations are related to the centre of the paper web and in the initial step 61 the zone positions and the screw positions are all preset relative to the paper web.

In step 62 the setting for one ink screw is calculated in accordance with the portion of the screw widths residing in a particular zone width.

Step 63 determines whether the zone width is either less than the ink screw width or at least equal to the ink screw width. In the latter case, the next ink screw width is selected in step 64, in the former case the remainder of the ink screw width to be used for the next zone is determined in step 66.

Step 65 determines whether the full zone width has been used and either selects the next zone width

(step 67) or calculates the remainder of the zone width to be applied to the next ink screw width

(step 68) .

Step 69 checks whether all the stored zone values

have been utilised, and, if not, the cycle of steps 62 to 69 is repeated, until the position is reached at which all the stored zone values have been converted into ink screw stored memory values. In the case where a paper web of a width narrower than the maximum is used, there may be ink screws which will not be used, and their stored memory values are left at zero as indicated at step 70. For the example of a paper web 43 of narrower width illustrated in Figure 10, four ink screws at each end of the web will not be used, and their values will be left at zero.

By the use of control apparatus as hereinbefore described in the quality control of newspapers, it is found that the time required to get the printing press printing newspapers of saleable quality is substantially reduced. For printing black and white newspapers, the time required may be reduced by several minutes, which represents a very substantial saving when the press may be producing a thousand or more newspapers each minute.