Method and an apparatus for illuminating points on a medium

• US 5,579,240 A
• Filed: 11/28/1994
• Issued: 11/26/1996
• Est. Priority Date: 05/26/1992
• Status: Expired due to Term

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: Dicon A/S
• Inventors: Buus, Niels
• Primary Examiner(s): Trammell, James P.
• Application Number:
  US08/343,479
• Time in Patent Office: 729 Days
• Field of Search: 364/525, 355/53, 355/67, 355/43, 369/112, 369/122, 369/109, 369/44.23, 369/110, 369/120, 369/44.24, 362/257, 250/200, 250/372, 353/122, 359/197.11, 359/559, 356/345, 356/355, 356/354, 356/21
• US Class Current: 355/67
• CPC Class Codes: B65H 2220/01 indicating an entity as a function of which control, adjustment or change is performed, i.e. input
• CPC Class Codes: B65H 2220/02 indicating an entity which is controlled, adjusted or changed by a control process, i.e. output
• CPC Class Codes: B65H 2220/03 indicating an entity which is measured, estimated, evaluated, calculated or determined but which does not constitute an entity which is adjusted or changed by the control process per se
• CPC Class Codes: B65H 23/24 by fluid action, e.g. to retard the running web
• CPC Class Codes: B65H 2301/4452 Regulating space between separated articles
• CPC Class Codes: B65H 2511/20 Location in space
• CPC Class Codes: B65H 2511/22 Distance
• CPC Class Codes: B65H 2511/512 Marks, e.g. invisible to the human eye; Patterns
• CPC Class Codes: B65H 2515/20 Volume; Volume flow
• CPC Class Codes: B65H 2515/34 Pressure, e.g. fluid pressure
• CPC Class Codes: B65H 2515/60 Optical characteristics, e.g. colour, light
• CPC Class Codes: B65H 2553/41 Photoelectric detectors
• CPC Class Codes: B65H 2553/416 Array arrangement, i.e. row of emitters or detectors
• CPC Class Codes: B65H 5/062 between rollers or balls
• CPC Class Codes: B65H 5/228 by air-blast devices
• CPC Class Codes: B65H 7/14 by photoelectric feelers or detectors
• CPC Class Codes: G03F 7/2002 with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image
• CPC Class Codes: G03F 7/2045 using originals with apertures, e.g. stencil exposure masks
• CPC Class Codes: G03F 7/7035 Proximity or contact printers
• CPC Class Codes: G03F 7/70716 Stages
• CPC Class Codes: H04N 1/036 : for optical reproduction
• CPC Class Codes: H04N 1/08 : Mechanisms for mounting or holding the sheet around the drum

Abstract

A method and apparatus for the illumination of points on a medium by illuminating a plurality of perforations that are arranged parallel to the medium with light having a center wavelength λ. The perforations have a cross-section so as to provide for each perforation a diverging bundle of rays formed by defracting the light. The medium is positioned from the perforations at substantially the transition of the diverging bundle of rays between the Fresnel region and the Fraunhofer region.

Claims

1. A method for the illumination of points on a medium (16), said illumination being performed by illuminating a plurality of perforations (14) with optical energy having a center wavelength (λ

), said optical energy passing through the perforations (14) and illuminating the medium (16) arranged at a distance (L) therefrom, said perforations (14) having a cross-section so as to provide, for each perforation (14), a diverging bundle of rays (28) created by diffraction, characterized by arranging the medium (16) to be illuminated at a distance (L) from the perforations (14) so that the medium (16) is substantially located in the transition of the diverging bundles of rays (28) between the Fresnel region (27) and the Fraunhofer region (26).

2. An apparatus for the illumination of points on a medium (16) and comprising perforations (14) which are arranged substantially in parallel with the medium (16) and which are illuminated with optical energy at a center wavelength (λ

), said optical energy passing through the perforations (14) and illuminating the medium (16) arranged at a distance (L) therefrom, said perforations (14) having a cross-section so as to provide, for each perforation (14), a diverging bundle of rays (28) created by diffraction, characterized in that the distance (L) of the medium (16) from the perforations (14) is selected such that the medium (16) is substantially located in an area around the transition between the Fresnel region (27) and the Fraunhofer region (26) of the bundles of rays (28).

3. An apparatus according to claim 2, wherein the perforations (14) have a largest transverse dimension (2 R), characterized in that the distance (L) is within the range.

4. An apparatus according to claim 2, characterized in that the perforations (14) are evenly distributed along a substantially straight line (FIG. 3, 40-44) and have a substantially constant mutual distance (A).

5. An apparatus according to claim 4, characterized by several rows (40-44) of perforations which extend in parallel and are mutually offset with respect to each other by an offset (Δ

).

6. An apparatus according to claim 5, characterized in that the number (N) of rows (40-44) of perforations corresponds to the ratio of the distance (A) to the offset (Δ

).

7. An apparatus according to claim 2, adapted for selective illumination of points on the surface of a medium (16), and comprising a central control unit (126) storing information on a desired illumination pattern on the medium (16), wherein each perforation (14) is provided by means of an illumination channel (FIG. 2), characterized by a unit (FIG. 9;

122) having a plurality of illumination channels through which a point on the medium is illuminated,

a light source (58) providing a plurality of illumination channels with optical energy,

said unit (122) for each illumination channel comprising;

an optical lens element (20) for intensifying the optical energy received from the light source (58),

a selectively controlled optical valve (24) permitting or preventing optical energy from propagating through the channel,

and an outlet aperture serving as a perforation (14) and defining the size of the point formed by the channel,

said central control unit (126) being electrically connected to each of the selectively controlled optical valves (24) for selective control of the energy transmission of each channel.

8. An apparatus according to claim 7, characterized in that the optical valve (24) is controlled by an electric field formed over the valve.