Method and apparatus for recording an image of an edge of a moving object

Abstract

An image is recorded of the edge of a moving object, in particular a sheet, in a machine processing printing material. The illumination is carried out with an illuminating device, and an image is recorded of at least one part of the edge with an image recording device. The use of the illuminating device and/or the image recording device is substantially synchronous with the movement of the object and substantially parallel to the direction of movement of the object. A preferred illuminating device has a row or array of light sources which in each case are switched on and off synchronously with the movement of the object. The constant shadow or shadow strip produced by the illumination moves with the object and ensures adequate contrast between the brightly illuminated object and the dark background, so that the object can be segmented reliably, at least in the region of the edge, and its position, orientation and movement can be determined.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic side elevation of a sheet-fed rotary printing press according to the invention;

FIGS. 2A-2B are schematic views of an apparatus according to the prior art;

FIGS. 3A-3D show a schematic view of a preferred exemplary embodiment of an apparatus according to the invention;

FIGS. 4A-4B show a schematic view of a further preferred exemplary embodiment of an apparatus according to the invention;

FIGS. 5A-5B show a schematic view of a further preferred exemplary embodiment of an apparatus according to the invention; and

FIG. 6 is a flow chart illustrating a preferred exemplary embodiment of a method according to the invention.

Claims

1. A method for recording an image of an edge of a moving object in machines processing printing material, the method which comprises: illuminating with an illuminating device; andrecording an image of at least one section of the edge with an image recording device; andilluminating with the illuminating device and/or recording with the image recording device substantially synchronously with a movement of the moving object and substantially parallel to a direction of movement of the moving object.

2. The method according to claim 1, which comprises activating the illuminating device and/or the image recording device substantially synchronously with the movement of the object and substantially parallel to the direction of movement of the object.

3. The method according to claim 1, wherein the illuminating device comprises a row of light sources and the method comprises switching the light sources on and off, individually or in groups, substantially synchronously with the movement of the object and substantially parallel to the direction of movement of the object.

4. The method according to claim 1, which comprises moving the illuminating device and/or the image recording device substantially synchronously with the movement of the object and along a direction substantially parallel to the direction of movement of the object.

5. The method according to claim 1, which comprises illuminating the moving object with the illuminating device such that the moving object throws a concomitantly moving shadow of substantially constant size.

6. An apparatus for recording an image of an edge of an object moving in a machine for processing printing material, the apparatus comprising: an illuminating device disposed to illuminate the object;an image recording device; anda control unit connected to and controlling at least one of said illuminating device and said image recording device, said control unit controlling said illuminating device and/or said image recording device substantially synchronously with a movement of the object and substantially parallel to a direction of movement of the object.

7. The apparatus according to claim 6, wherein said illuminating device and/or said image recording device are displaceably mounted for movement substantially synchronously with the movement of the object and substantially parallel to the direction of movement of the object.

8. The apparatus according to claim 6, wherein said illuminating device comprises n light sources disposed in a row oriented substantially parallel to the direction of movement of the object.

9. The apparatus according to claim 6, wherein said illuminating device comprises an array of n times m light sources oriented substantially parallel and perpendicular to the direction of movement of the object.

10. A machine for processing printing material, comprising at least one apparatus according to claim 6.

11. A printing press, comprising at least one apparatus according to claim 6.

12. A sheet-fed rotary printing press for lithographic offset printing, comprising at least one apparatus according to claim 6.

13. A machine for after-print processing of sheet material, comprising at least one apparatus according to claim 6.