Method for reading a graphic pattern and acquiring its image

• US 20060175410A1
• Filed: 03/15/2006
• Published: 08/10/2006
• Est. Priority Date: 12/31/2002
• Status: Active Grant

• Current Assignee: Datalogic S.p.A.
• Original Assignee: Datalogic S.p.A.
• Inventors: Benedetti, Michele
• Granted Patent: US 7,264,165 B2
• Time in Patent Office: Days
• US Class Current: 235/454
• CPC Class Codes: G06K 7/10574 Multiple sources
• CPC Class Codes: G06K 7/10732 Light sources

Abstract

A method for reading a graphic pattern by illuminating the graphic pattern with at least two groups of light sources, each of the at least two groups of light sources having at least one light source operating according to an illumination cycle that comprises an illumination cycle-portion and a non-illumination cycle-portion. The light sources of one of the at least two groups of light sources are activated according to equal illumination cycles. The illumination cycles of the light sources belong to different ones of the at least two groups of light sources having a reciprocally different timing. Light is gathered from the light sources having been diffused by the graphic pattern on a sensor having a plurality of sensitive points. Light impinging on the plurality of sensitive points is converted, through a conversion cycle of the sensor, point by point into electric signals representative of single points of the graphic pattern, at a same time for all of the plurality of sensitive points.

Claims

1. A method for reading a graphic pattern, comprising the steps of:

illuminating said graphic pattern with at least two groups of light sources, each of said at least two groups of light sources having at least one light source operating according to an illumination cycle that comprises an illumination cycle-portion and a non-illumination cycle-portion;

wherein said light sources of one of said at least two groups of light sources are activated according to equal illumination cycles;

wherein said illumination cycles of said light sources belonging to different ones of said at least two groups of light sources having a reciprocally different timing;

gathering light from said light sources having been diffused by said graphic pattern on a sensor having a plurality of sensitive points; and

converting, through a conversion cycle of said sensor, said light impinging on said plurality of sensitive points, point by point, into electric signals representative of single points of said graphic pattern, at a same time for all of said plurality of sensitive points, said conversion cycle comprising at least an acquisition step;

wherein the acquisition step overlaps at least partially with the illumination step of the light sources of each of the groups of light sources;

wherein said illumination cycle portion of said illumination cycle of any of said groups of light sources has a temporal overlap with the acquisition step that is different from the temporal overlap of the illumination cycle portion of said illumination cycle of another of said groups of light sources with the same acquisition step.

2. The method according to claim 1 wherein said illumination cycles of all of said light sources are equal to one another, and wherein said illumination cycles of said light sources of one of said at least two groups of light sources are not timed with respect to said illumination cycles of said light sources of a different one of said at least two groups of light sources.

3. The method according to claim 1 wherein said illumination cycle of each light source and said conversion cycle have a same period.

4. The method according to claim 3 wherein each of said light sources is located a distance from a privileged illumination zone, said method further comprising the step of dividing said light sources into one of said at least two groups of light sources according to said distance.

5. The method according to claim 4 wherein, for each of said light sources of one of said at least two groups of light sources, said illumination cycle-portion overlaps said gathering step wherein a greater distance of said light sources of said one of said at least two groups of light sources from said privileged illumination zone corresponds to a longer overlap.

6. The method according to claim 3 wherein said conversion cycle comprises an acquisition step and a non-acquisition step regulated by a shutter, which, when activated, determines said non-acquisition step, and when not activated, determines said acquisition step.

7. The method according to claim 3 wherein said conversion cycle comprises an acquisition step and a non-acquisition step and wherein said sensor operates according to a succession of scanning steps having said same period, such scanning steps being alternately used and not used, so that said scanning steps used determine said acquisition steps, whereas said scanning steps not used determine said non-acquisition steps.

8. The method according to claim 1 wherein said at least two groups of light sources comprises two groups.

9. The method according to claim 8 wherein said illumination cycle-portion of said illumination cycle of one of said two groups of light sources temporally corresponds to said non-illumination portion of the other one of said two groups of light sources.

10. The method according to claim 1 wherein said illumination cycle-portion of said illumination cycle of one of said at least two groups of light sources temporally corresponds to said non-illumination cycle-portion of another of said at least two groups of light sources.

11. The method according to claim 1 wherein said illumination cycle-portion of said illumination cycle of one of said at least two groups of light sources temporally corresponds to said non-illumination cycle-portion of all the other ones of said at least two groups of light sources.

12. The method according to claim 1 wherein said reciprocally different timing is variable.

13. The method according to claim 1 wherein said conversion cycle comprises an acquisition step and a non-acquisition step, the non-acquisition step overlaps at least partially with the illumination step of the light sources of at least one of the groups of light sources.

14. A method for reading a graphic pattern, comprising the steps of:

illuminating said graphic pattern with at least two groups of light sources, each of said at least two groups of light sources having at least one light source operating according to an illumination cycle that comprises an illumination cycle-portion and a non-illumination cycle-portion;

wherein said light sources of one of said at least two groups of light sources are activated according to equal illumination cycles;

wherein said illumination cycles of said light sources belonging to different ones of said at least two groups of light sources having a reciprocally different timing;

gathering light from said light sources having been diffused by said graphic pattern on a sensor having a plurality of sensitive points; and

converting, through a conversion cycle of said sensor, said light impinging on said plurality of sensitive points, point by point, into electric signals representative of single points of said graphic pattern, at a same time for all of said plurality of sensitive points, said conversion cycle comprising at least an acquisition step;

wherein the acquisition step overlaps at least partially with the illumination step of the light sources of each of the groups of light sources.