Apparatus and method for the recording of images of objects moved on a conveyor device

• US 20090095600A1
• Filed: 10/08/2008
• Published: 04/16/2009
• Est. Priority Date: 10/10/2007
• Status: Active Grant

• Current Assignee: Sick AG (Sick)
• Original Assignee: Sick AG (Sick)
• Inventors: Reichenbach, Jurgen, Gehring, Roland, Nopper, Richard, Schopflin, Uwe, Heizman, Reinhard
• Granted Patent: US 8,245,838 B2
• Time in Patent Office: Days
• US Class Current: 198/810.01
• CPC Class Codes: B07C 3/14 using light-responsive detecting means for information carriers G06K7/14
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10792 Special measures in relation to the object to be scanned

Abstract

An apparatus, in particular a code reader, for the recording of images of objects (14) moved on a conveyor device (12), wherein the apparatus includes a line sensor (10), in particular a line camera, which can scan objects line wise for the generation of image data of the surfaces, as well as a speed determination device (26; 30), which can determine the speed of movement of the objects (14) with respect to the line sensor (10) or their conveyed distance. At the same time an evaluation unit (26) is provided, which is adapted to match the recording frequency of the line sensor (10) to the speed of movement.

Claims

1. An apparatus, in particular a code reader, for the recording of images of objects (14) moved on a conveyor device (12), wherein the apparatus includes a line sensor (10), in particular a line camera, which can scan objects line wise for the generation of image data of the surfaces, as well as a speed determination device (26;

30), which can determine the speed of movement of the objects (14) with respect to the line sensor (10) or their conveyed distance, characterized in that an evaluation unit (26) is provided, which is adapted to match the recording frequency of the line sensor (10) to the speed of movement.

2. An apparatus in accordance with claim 1, wherein the evaluation unit (26) is adapted to match the recording frequency in such a way that the line sensor (10) records image data of equidistant lines of the object (14).

3. An apparatus in accordance with claim 1, wherein the line sensor (10) is adapted to be set to a base recording frequency with associated recording parameters which in particular correspond to a maximum conveying speed of the conveyor device (12) and wherein the evaluation unit (26) is adapted to differentially set the adaptation of the recording frequency and/or of the recording parameters for the line sensor (10) to a speed of movement changed with respect to the maximum conveying speed.

4. An apparatus in accordance with claim 1, wherein the speed determination device (26;

30) is, either a displacement sensor, an incremental encoder or a different sensor preceding the line sensor (10).

5. An apparatus in accordance with claim 1, wherein the speed determination device (30) is a conveyor controller of the conveyor device (12), which in particular sets the speed profile of the conveyor device (12) and wherein the conveyor controller (30) can send data on the speed profile to the evaluation unit (26), which in particular include a current speed, a duration of a subsequent acceleration phase, a start of the acceleration phase and/or an end speed after the completion of the acceleration phase.

6. An apparatus in accordance with claim 5, wherein the conveyor controller (30) is adapted for a setting of a maximum conveying speed of 2 m/s, of a lowered conveying speed of 0.5 m/s as well as of an acceleration phase of 500 ms at an acceleration of 3 m/s² from the maximum conveying speed to a lowered speed and vice versa.

7. An apparatus in accordance with claim 1, wherein the conveyor device (12) is a tray conveyor or its infeed belt.

8. An apparatus in accordance with claim 1, wherein the recording frequency changing over time for a set speed profile of an object (14) is stored in a table, within the evaluation unit (26), as time intervals between two respective recordings, wherein the entries into the table in particular describe a hyperbola.

9. An apparatus in accordance with claim 8, wherein the evaluation unit (26) is adapted so that entries of the table are set, in particular by inputting or reading in, or are calculated on the basis of a set speed profile, in particular as hyperbolas of a maximum conveying speed, a lowered conveying speed as well as a uniform acceleration phase therebetween, which is specified by a start time, a finish time and/or an acceleration.

10. An apparatus in accordance with claim 8, wherein the evaluation unit (26) is adapted to use a table value a plurality of times, to reflect longer acceleration phases and/or to initiate a recording stop of the line sensor (10), if the speed of movement is zero, i.e. the conveyor device is stopped.

11. An apparatus in accordance with claim 8, wherein a further table is provided in the evaluation unit (26), which includes time intervals for the recording frequency for the case that the sign changes in an acceleration phase, i.e. a reversal of the acceleration occurs, to ensure a smooth transition of the time intervals.

12. An apparatus in accordance with claim 1, wherein the evaluation unit (26) is at least partially implemented on a programmable logic component, in particular an FPGA, of the line sensor (10) and wherein the line sensor (10) includes at least one input, with which the logic component can be instructed to start and execute the adaptation of the recording frequency via a set speed profile.

13. A method for the recording of images of objects (14) moved on a conveyor device (12) and for the decoding of codes (20) arranged on the objects (14), wherein the objects (14) are scanned line wise for the generation of image data and wherein the speed of movement of the objects (14) with respect to the line sensor (10) or their conveyed distance is determined, characterized in that the recording frequency of the line wise scanning is matched to the speed of movement, in particular in such a way that the scanning lines lie distributed equidistantly over the object (14).

14. A method in accordance with claim 13, wherein a speed profile is set for the conveyor device (12), and in particular includes a current speed, a duration of a subsequent acceleration phase, a start of the acceleration phase and/or an end speed after the completion of the acceleration phase and wherein the speed profile is used for the adaptation of the recording frequency and wherein in particular a maximum conveying speed of 2 m/s, a lowered conveying speed of 0.5 m/s as well as an acceleration phase of 500 ms at an acceleration of 3 m/s² from the maximum conveying speed to a lowered speed and vice versa is provided.

15. A method in accordance with claim 13, wherein the recording frequency changing over time for a set speed profile of an object (14) is stored in a table as time intervals between two respective recordings, wherein the entries in the table in particular describe a hyperbola and are calculated from a maximum conveying speed, from a lowered conveying speed as well as from a uniform acceleration phase therebetween, which is specified by a start time, a finish time and/or an acceleration.

16. A method in accordance with claim 13, wherein a table value is used a plurality of times to reproduce longer acceleration phases and/or wherein a recording stop is initiated when the speed of movement is zero, i.e. the conveyor device (12) is stopped, and/or wherein a further table is provided which includes time intervals for the recording frequency for the case that the sign changes in the acceleration phase, i.e. a reversal of the acceleration occurs, to ensure a smooth transition of the time intervals.