Trigger system for data reading device

• US 8,107,675 B2
• Filed: 12/29/2006
• Issued: 01/31/2012
• Est. Priority Date: 12/29/2006
• Status: Active Grant

• Current Assignee: Cognex Corporation
• Original Assignee: Cognex Corporation
• Inventors: Reuter, Richard
• Primary Examiner(s): KOZIOL, STEPHEN R
• Application Number:
  US11/648,170
• Publication Number:
  US 20080158365A1
• Time in Patent Office: 1,859 Days
• Field of Search: 382/103, 382/141, 348/207.1, 348/E5.024, 348/E5.02
• US Class Current: 382/103
• CPC Class Codes: G06V 10/10 Image acquisition document image scanning and transmission H04N1/00; control of digital cameras H04N23/60
• CPC Class Codes: H04N 25/42 by switching between different modes of operation using different resolutions or aspect ratios, e.g. switching between interlaced and non-interlaced mode
• CPC Class Codes: H04N 25/44 by partially reading an SSIS array
• CPC Class Codes: H04N 25/447 by preserving the colour pattern with or without loss of information

Abstract

A data reader comprises a camera that has an adjustable resolution and acquisition speed. The camera is maintained at a low level resolution and fast speed and is periodically actuated to acquire images. When an acquired image indicates that an object is present, the resolution of the camera is increased, and a higher resolution image is acquired and decoded. The imaging system of the camera is therefore used to trigger data acquisitions, thereby eliminating the need for external triggers and sensor devices.

Claims

1. A method for triggering image acquisition in a data reading system comprising a camera and a light source, the method comprising the following steps:

(a) lowering a resolution of the camera;

(b) periodically acquiring images with the camera at the lowered resolution;

(c) evaluating the acquired images to determine whether the image contains an object;

(d) repeating steps (b) and (c) until the acquired image contains the object;

(e) increasing the resolution of the camera to a high resolution higher than the lowered resolution;

(f) acquiring an image of the object with the camera at the high resolution; and

(g) returning to step (a).

2. The method as recited in claim 1, further comprising the step of decoding a symbol in the acquired image of the object.

3. The method as recited in claim 1, further comprising the step of identifying a path for moving a plurality of objects and positioning the camera adjacent the path.

4. The method as recited in claim 1, further comprising the step of activating the light source prior to acquiring the image and deactivating the light source after acquiring the image.

5. The method as recited in claim 1, wherein step (a) comprises increasing a frame rate of the camera.

6. The method as recited in claim 1, wherein step (e) comprises the step of reducing a frame rate of the camera.

7. The method as recited in claim 1, further comprising the step of processing the image.

8. The method as recited in claim 1, further comprising the step of providing a reflector opposite the camera.

9. The method as recited in claim 8, wherein step (c) comprises the step of evaluating the image to determine if the image includes a reflection of the light source from the reflector.

10. A data reading system comprising:

a reader including;

a light source; and

a camera having an adjustable resolution;

a controller for controlling image acquisition in the camera, the controller being adapted to;

(a) periodically acquire an image at a selected initial resolution;

(b) evaluate the acquired image to determine if the image includes an object

(c) increase the resolution of the camera when the image includes an object to acquire an image data set capable of analysis;

(d) acquire an additional image at the increased resolution; and

(e) reset the resolution to the initial resolution and return to step (a).

11. The data reading system as recited in claim 10, wherein the processor is further adapted to activate the light source prior to acquiring the image and deactivate the light source after acquiring the image.

12. The data reading system as recited in claim 10, wherein the processor is further adapted to process the additional image.

13. The data reading system as recited in claim 10, wherein the additional image includes a symbol and the controller is further adapted to decode the symbol.

14. The data reading system as recited in claim 10 further comprising a conveyor for moving a plurality of objects in front of the camera.

15. The data reading system as recited in claim 10, further comprising a reflector, the reflector being positioned opposite the camera to reflect light emitted by the light source back to the camera.

16. The data reading system as recited in claim 10, wherein the controller is adapted to evaluate the acquired image by determining if the image is of light reflected from the light source.

17. The data reading system as recited in claim 10, further comprising a conveyor, and wherein the camera is coupled to the conveyor.

18. The data reading system as recited in claim 10, wherein changing the resolution of the camera increases or decreases the frame rate of the camera.

19. The data reading system of claim 10, wherein the camera comprises an imaging sensor and an optical element for focusing light.

20. A data reading system comprising:

a reader including;

a light source; and

a camera having an adjustable acquisition speed;

a controller for controlling image acquisition in the camera, the controller being adapted to;

(a) periodically acquire an image at a high rate of speed;

(b) evaluate the acquired image to determine if the image includes an object;

(c) decrease the acquisition rate of the camera to a reduced rate of speed lower than the high rate of speed when the image includes an object to acquire an image data set capable of analysis;

(d) acquire an additional image at the reduced rate of speed; and

(e) reset the acquisition rate to the high rate of speed and return to step (a).