Method and instrument for determining the distortion angles in textile fabrics or similar, whether fixed or in movement

• US 6,920,235 B2
• Filed: 07/25/2001
• Issued: 07/19/2005
• Est. Priority Date: 07/26/2000
• Status: Active Grant

• Current Assignee: Ehrardt Piu Leimer S.R.L.
• Original Assignee: Ehrardt Piu Leimer S.R.L.
• Inventors: Biazzi, Pier Silvano
• Primary Examiner(s): Mehta, Bhavesh M.
• Assistant Examiner(s): Choobin, Barry
• Application Number:
  US09/912,760
• Publication Number:
  US 20020015152A1
• Time in Patent Office: 1,455 Days
• Field of Search: 382/111, 382/108, 382/289, 382/280, 382/315, 356/238.1, 356/429, 356/432, 26/70, 731/59, 700/130, 700/135, 700/140, 700/143, 223/40
• US Class Current: 382/111
• CPC Class Codes: D06H 3/125 Detecting errors in the position of weft threads
• CPC Class Codes: G01N 21/8983 for testing textile webs, i.e. woven material

Abstract

A method for determining the angles of oblique and arched distortion in a textile fabric, with the use of at least one optical detector with axes of symmetry orienated with respect to the fabric, includes illuminating an area of the fabric with a light source. A real image of the area of the fabric is acquired in digital form, irrespectively of the orientation of the optical detector with regard to the fabric, wherein the fabric is illuminated for just the time necessary to acquire the image. The image is rotated and compensated for the orientation of the axes of the symmetry of the optical detector with regard to the fabric. Algorithms useful for the increasing the reliability of the results of subsequent processing are applied to the image, followed by a Fourier transformation. An angle of local distortion is calculated by analyzing the spectrum of the Fourier transformation and the angles of oblique and arched distortion are calculated starting from the angle of local distortion.

Claims

1. A method for determining angles of oblique and arched distortion of a textile fabric, with the use of at least one optical detector with axes of symmetry orientated with respect to the fabric, the method comprising:

illuminating an area of the fabric with a light source;

acquiring, in digital form, a real image of the area of the fabric, irrespectively of the orientation of the optical detector with respect to the fabric, wherein the fabric is illuminated for just the time necessary to acquire the image;

rotating the image and compensating for the orientation of the axes of symmetry of the optical detector with respect to the fabric;

applying to the image algorithms useful for increasing the reliability of the results of subsequent processing;

applying a two-dimensional Fourier transformation to the image;

calculating an angle of local distortion by analyzing the spectrum of the Fourier transformation; and

calculating the angles of oblique and arched distortion, starting from the angle of local distortion.

2. The method according to claim 1, wherein the value of the local angle is generated only on a request from a central supervision and control system.

3. The method according to claim 1, wherein the illuminating of the fabric is carried out with single impulses and the acquiring of the images is synchronized with the impulses.

4. The method according to claim 1, wherein the fabric is fixed.

5. The method according to claim 1, wherein the fabric is moving.

6. A sensor for determining the angles of oblique and arched distortion of a fabric according to the method of claim 1, the sensor including within a single functional unit:

focusing optics;

an illuminator control circuit for controlling the duration of the illuminating; and

an integrated acquisition, processing and communication unit.

7. The sensor according to claim 6, wherein the integrated acquisition, processing and communication unit includes a static matrix photosensitive device.

8. A faller device for treatment of textile fabric, the faller device comprising actuators for controlling correction of distortion angles, at least one sensor according to claim 6 for detecting local distortions, and a supervision and control system for acquiring and processing the values of the local distortions, and for controlling the actuators of the faller machine.

9. A machine for controlling and certifying defects in textile fabrics, the machine being configured to implement the method of claim 1.

10. The method according to claim 2, wherein the illuminating of the fabric is carried out with single impulses and the acquiring of the images is synchronized with the impulses.

11. The method according to claim 2, wherein the fabric is moving.

12. The method according to claim 3, wherein the fabric is moving.

13. A faller device for treatment of textile fabric, the faller device comprising actuators for controlling correction of the distortion angles, at least one sensor according to claim 7 for detecting local distortions, and a supervision and control system for acquiring and processing the values of the local distortions, and for controlling the actuators of the faller machine.

14. A machine for controlling and certifying defects in textile fabrics, the machine being configured to implement method of claim 2.

15. A machine for controlling and certifying defects in textile fabrics, the machine being configured to implement the method of claim 3.

16. A machine for controlling and certifying defects in textile fabrics, the machine being configured to implement the method of claim 4.

17. A machine for controlling and certifying defects in textile fabrics, the machine being configured to implement the method of claim 5.

18. A machine for controlling and certifying defects in textile fabrics, the machine being configured to implement the method of claim 6.

19. A machine for controlling and certifying defects in textile fabrics, the machine being configured to implement the method of claim 7.

20. A machine for controlling and certifying defects in textile fabrics, the machine being configured to implement the method of claim 8.