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

• US 8,245,838 B2
• Filed: 10/08/2008
• Issued: 08/21/2012
• Est. Priority Date: 10/10/2007
• Status: Active Grant

• Current Assignee: Sick AG (Sick)
• Original Assignee: Sick AG (Sick)
• Inventors: Reichenbach, Jürgen, Gehring, Roland, Nopper, Richard, Heizmann, Reinhard, Schöpflin, Uwe
• Primary Examiner(s): Singh, Kavel
• Application Number:
  US12/285,528
• Publication Number:
  US 20090095600A1
• Time in Patent Office: 1,413 Days
• Field of Search: None
• 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 for the recording of images of objects moved on a conveyor device, comprising:

a line sensor configured to scan objects line wise in a transverse direction to movement of the conveying device for the generation of image data of surfaces;

a speed determination device, configured to determine a speed of movement of the objects with respect to the line sensor; and

an evaluation unit configured to vary the recording frequency of the line sensor with the speed of movement,

wherein the speed determination device is a conveyor controller of the conveyor device, which is configured to set the speed profile of the conveyor device, and

wherein the conveyor controller is configured to send data on the speed profile to the evaluation unit, wherein

the data is selected from the group consisting of 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.

2. An apparatus in accordance with claim 1, wherein the evaluation unit is configured to vary the recording frequency such that the line sensor records image data of equidistant lines of the object.

3. An apparatus in accordance with claim 1,

wherein the line sensor is configured to be set to a base recording frequency with associated recording parameters corresponding to a maximum conveying speed of the conveyor device;

and

wherein the evaluation unit is configured to differentially set the adaptation of the recording frequency and/or of the recording parameters for the line sensor to a speed of movement varied with respect to the maximum conveying speed.

4. An apparatus in accordance with claim 1, wherein the speed determination device is selected from the group consisting of a displacement sensor, an incremental encoder, and a different sensor preceding the line sensor.

5. An apparatus in accordance with claim 1, wherein the conveyor controller is configured for a setting of a maximum conveying speed of 2 m/s, a lowered conveying speed of 0.5 m/s, and 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.

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

7. An apparatus in accordance with claim 1,

wherein the recording frequency varying over time for a set speed profile of an object is stored in a table within the evaluation unit as time intervals between two respective recordings, and

wherein the entries into the table describe a hyperbola.

8. An apparatus in accordance with claim 7, wherein

the evaluation unit is configured so that entries of the table are set or calculated on the basis of the set speed profile.

9. An apparatus in accordance with claim 8, wherein the entries of the table include one or more hyperbolas describing one or more of a maximum conveying speed, a lowered conveying speed, and a uniform acceleration phase therebetween specified by a start time, a finish time and/or an acceleration.

10. An apparatus in accordance with claim 7, wherein the evaluation unit is configured to use a table value for a plurality of times, to reflect longer acceleration phases and/or to initiate a recording stop of the line sensor when the speed of movement is zero.

11. An apparatus in accordance with claim 7, wherein a further table is provided in the evaluation unit which includes time intervals for the recording frequency when a reversal of acceleration occurs.

12. An apparatus in accordance with claim 1,

wherein the evaluation unit is at least partially implemented on a programmable logic component and

wherein the line sensor includes at least one input, and

wherein the logic component is configured to be instructed to start and execute the adaptation of the recording frequency via a set speed profile.

13. An apparatus in accordance with claim 1, wherein the line sensor is a camera.

14. An apparatus in accordance with claim 1, wherein the programmable logic component is an FPGA.

15. A method for recording images of objects moved on a conveyor device and decoding codes arranged on the objects, comprising the steps of:

generating image data by scanning objects line wise in a transverse direction to movement of the conveying device;

determining a speed of movement of the objects with respect to the line sensor;

varying a recording frequency of the line wise scanning with the speed of movement;

setting a speed profile for the conveyor device, the speed profile including 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

using the speed profile to vary the recording frequency.

16. A method in accordance with claim 15, further including the steps of:

using a table value a plurality of times to reproduce longer acceleration phases and/or;

initiating a recording stop when the speed of movement is zero; and

/or

providing a further table which includes time intervals for the recording frequency when a reversal of the acceleration occurs.

17. A method in accordance with claim 15, wherein scanning lines are distributed equidistantly over the objects.

18. The method of claim 15, further comprising the step of setting a maximum conveying speed of 2 m/s, a lowered conveying speed of 0.5 m/s, and 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.

19. A method for recording images of objects moved on a conveyor device and decoding codes arranged on the objects, comprising the steps of:

generating image data by scanning objects line wise in a transverse direction to movement of the conveying device;

determining a speed of movement of the objects with respect to the line sensor;

varying a recording frequency of the line wise scanning with the speed of movement;

setting a speed profile for the conveyor device, the speed profile including 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;

using the speed profile to vary the recording frequency;

varying the recording frequency over time for a set speed profile of an objects and

storing the change in a table as time intervals between two respective recordings,

wherein the entries in the table describe a hyperbola calculated from at least one of the group consisting of a maximum conveying speed, a lowered conveying speed, and a uniform acceleration phase therebetween specified by a start time, a finish time and/or an acceleration.