Classifications

• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
  • G06K15/00—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers
  • G06K15/02—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers using printers
  • G06K15/12—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers using printers by photographic printing, e.g. by laser printers
  • G06K15/1238—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers using printers by photographic printing, e.g. by laser printers simultaneously exposing more than one point
  • G06K15/1242—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers using printers by photographic printing, e.g. by laser printers simultaneously exposing more than one point on one main scanning line
  • G06K15/1252—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers using printers by photographic printing, e.g. by laser printers simultaneously exposing more than one point on one main scanning line using an array of light modulators, e.g. a linear array
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
  • G06K15/00—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers
  • G06K15/02—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers using printers
  • G06K15/12—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers using printers by photographic printing, e.g. by laser printers
  • G06K15/129—Colour printing

Definitions

• the subject of this invention is a method and apparatus for printing on sheet material such as w eb s o f t e x t i l e ma t e r i a l a n d s h e e t s o f p ap e r .
• one form of apparatus employing a Laser device includes a rotating mirror structure so arranged that the beam from a Laser directed on to the rotating mirror is caused to scan across a light sensitive printing drum while the output of the laser is controlled by a computer to produce sensitized points on the printing drum in the form of a line of dots.
• the laser is so switched that the spacing of the dots in each scanning line is determined to form a line of the desired pattern, the pattern being built up by the addition of subsequent scanning lines of dots on the printing drum so that the lines of dots come together on the printing drum to delineate the pattern to appear on the web.
• Toner i.e.
• a disadvantage of the known apparatus using liquid crystal shutters is that the pattern is created by a continuous operation of successive line formation. Since every line has a different spacing of dots from the dot spacing in the preceding line in the formation of most patterns the line of shutters has to be reset to a new configuration for each succeeding line of the pattern and even in forming repeat patterns each repeat is a completely fresh pattern-forming operation. As it is necessary in forming patterns of high quality to provide at least 120 dots per cm it will be understood the rate of emission of shutter control impulses by the controlling computer must be very high, at least 120 times the width of the web of material being printed in cm times the depth of the design in cm times the number of patterns to be reproduced per second.
• the rate at which the control impulses have to be applied by the control computer to the shutters for operation at commercial speeds of printing may thus be as high as 100 mHz for each printing colour. For colour printing at least found separate colour printing units are required, For high quality work even more colours are often required.
• the control computer must be able to operate at a speed of at least 400 mHz and often cons i de rab l y faster. A computer able to operate at this speed is extremely expensive, possibly so expensive as to r e n d e r the whole operation uneconomic.
• a method of printing paper or textile material by directing light on to a light sensitive printing surface through electronically operated light shutter units and applying printing medium to the light sensitive printing surface whereby the printing medium adheres to the portions of the printing surface on which the light has fallen and then bringing the printing surface into contact with the material to be printed is characterized by arranging the shutters in an array forming a two dimensional area disposed in proximity to the light sensitive surface and setting the shutters in a pre arranged pattern for passage or non-passage of light through the shutters of the array then applying light to whatever portion of the array is at any particular time adjacent to the light sensitive printing surface.
• the light sensitive printing surface may be a rotatable printing drum and the two-dimensional area constituting the array of shutters may be constituted by at least a portion of the surface of a second and hollow control drum the axis of which is p a r a l l e l to the axis of the printing drum the light being applied to that portion of the inner surface of said control drum which is for the time being adjacent to the printing drum, said printing drum and said control drum being arranged to rotate in opposite directions at the same peripheral speed.
• a machine for printing sheet material incorporating a rotatable light sensitive printing drum arranged to be sensitized to retain printing medium applied thereto at any point on the surface where a beam of light falls on that point on the surface, electronically operated shutter units operable to permit or block the passage of light therethrough to the printing drum, a light source arranged to apply light to the shutters and means for applying printing medium to the printing drum at a position where it can be retained at sensitized points is characterized in that the shutter units are arranged to form at least a portion of the wall of a second and hollow control drum disposed parallel to the printing drum and arranged to rotate in a direction opposite to that of the printing drum and at the same peripheral speed, the light projecting means being located within said control drum and being arranged to project light against the light shutter units forming that portion of the wall of .the control drum which is at that instant closest to the printing drum.
• 1, 2, 3 and 4 denote hollow drums the wall of at least a portion of each of which is constituted by an array of electrically operated light shutters 5, 6, 7 and 8 respectively.
• the hollow drums 1, 2, 3 and 4 contain within them light sources (not illustrated).
• 9, 10, 11 and 12 denote light sensitive printing drums each arranged with its axis parallel to the axis of the a s s o c i a t e d control drums 1, 2, 3 and 4, the light source inside the drums 1, 2, 3 and 4 being located to direct the light against the portion of the wall of the associated drum 1, 2, 3 or 4 closest to the associated drum
• Means (not shown) is provided for directing printing medium (toner) of the appropriate colour against each drum.
• a control computer (not shown) is operatively connected to the individual light shutters of the arrays 5, 6, 7 and 8 to set open o r closed each individual shutter according to the pattern to be printed.
• the light sources within the control drums 1, 2, 3 and 4 direct light continually towards the shutter devices adjacent to the printing drums 9, 10, 11 and 12.
• Each shutter device if open allows a dot of light to pass through to the associated light sensitive printing drum or prevents light from passing through at the point of that particular shutter device.
• a pattern is thus built up on each printing drum as it rotates along with the associated control drum so that each printing drum carries on its surface an electrical pattern of the entire presentation of the design in a particular colour. Toner of that particular colour applied to each printing drum adheres to the printing drum at the electrified points and as the printing drum rotates the toner is transferred to the sheet of material to be printed 13.
• the control computer sets up the entire pattern on each control drum 1, 2, 3, 4 by arranging for the shutters to be open or shut over the entire surface of the drum, the shutters being left in that position until that pattern is no longer required.
• Each control drum is then illuminated by the associated light source and as each portion of the array of light shutters is brought successively across the associated light sensitive printing drum that portion of the pattern appears on the light sensitive printing drum in the form of sensitized spots to which printing medium applied to the drum adheres for transfer to the sheet 13 as the drum rotates.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Optics & Photonics (AREA)
• General Engineering & Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Printing Methods (AREA)
• Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10628753

Family Applications (1)

Country Status (3)

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Family Cites Families (2)

• 1987
  • 1987-12-19 GB GB878729645A patent/GB8729645D0/en active Pending
• 1988
  • 1988-12-19 WO PCT/GB1988/001136 patent/WO1989005729A1/en not_active Ceased
  • 1988-12-19 EP EP19890901123 patent/EP0367801A1/de not_active Withdrawn

Non-Patent Citations (1)

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