Irregularly spacing linear portions of media sheet for optical scanning thereof

• US 20060164697A1
• Filed: 01/26/2005
• Published: 07/27/2006
• Est. Priority Date: 01/26/2005
• Status: Abandoned Application

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Larson, David R.
• Application Number:
  US11/043,514
• Publication Number:
  US 20060164697A1
• Time in Patent Office: Days
• US Class Current: 358/509
• CPC Class Codes: H04N 1/4078 using gradational references, e.g. grey-scale test pattern analysis

Abstract

A method and apparatus for optically scanning a media sheet effectively advances the media sheet relative to a light source. The media sheet is logically divisible into linear portions. Each linear portion has a number of positions. The linear portions are irregularly spaced relative to one another. As the light source becomes incident to each position of each linear portion of the media sheet, the light reflected by the position is optically detected to optically scan the position.

Claims

1. A method for optically scanning a media sheet comprising:

effectively advancing the media sheet relative to a light source, such that the media sheet is logically divided into a plurality of linear portions, each linear portion having a plurality of positions, and the linear portions irregularly spaced relative to one another; and

,

as the light source becomes incident to each position of each linear portion of the media sheet, optically detecting light reflected by the position to optically scan the position.

2. The method of claim 1, wherein the linear portions are irregularly spaced relative to one another in that distances between immediately adjacent linear portions of the media sheet are not necessarily equal to one another.

3. The method of claim 1, wherein effectively advancing the media sheet relative to the light source comprises effectively advancing the media sheet by a variable amount between immediately adjacent linear portions thereof, so that distances between immediately adjacent linear portions of the media sheet are irregular.

4. The method of claim 3, further comprising determining the variable amount each time the media sheet is effectively advanced by adding a random value to a target amount, the random value having a lower negative limit and an upper positive limit.

5. The method of claim 3, further comprising determining the variable amount each time the media sheet is effectively advanced by looking up the variable amount within a predefined table of advancement amounts.

6. The method of claim 3, further comprising determining the variable amount each time the media sheet is effectively advanced by performing a mathematical function to yield the variable amount.

7. The method of claim 1, wherein effectively advancing the media sheet relative to the light source comprises effectively advancing the media sheet relative to the light source at a constant speed, where a timing at which the positions of each linear portion of the media sheet are optically scanned as the media sheet is effectively advanced at the constant speed is variable, so that distances between immediately adjacent linear portions of the media sheet are irregular.

8. The method of claim 7, further comprising determining the timing at which the positions of each linear portion of the media sheet are optically scanned by adding a random value to a target timing value, the random value having a lower value having a lower negative limit and an upper positive limit.

9. The method of claim 7, further comprising determining the timing at which the positions of each linear portion of the media sheet are optically scanned by looking up the timing within a predefined table of variable timings.

10. The method of claim 7, further comprising determining the timing at which the positions of each linear portion of the media sheet are optically scanned by performing a mathematical function to yield a variable timing.

11. A method for optically scanning a media sheet comprising:

effectively advancing a media sheet by a variable amount so that a linear portion of the media sheet is incident to a light source;

optically detecting reflected light by the linear portion of the media sheet; and

,

repeating effectively advancing the media sheet by the variable amount and optically detecting the reflected light until the media sheet has been completely optically scanned.

12. The method of claim 11, further comprising determining the variable amount each time the media sheet is to be effectively advanced, by one of:

adding a random value to a target amount, the random value having a lower negative limit and an upper positive limit;

looking up the variable amount within a predefined table of advancement amounts; and

,

performing a mathematical function to yield the variable amount.

13. The method of claim 11, wherein an average of the variable amount by which the media sheet is effectively advanced over all times the media sheet has been effectively advanced in optically scanning the media sheet is at least substantially equal to a predetermined target value.

14. A method for optically scanning a media sheet comprising:

effectively advancing a media sheet relative to a light source;

waiting for a variable length of time;

optically detecting reflected light by a linear portion of the media sheet currently incident to the light source; and

,

repeating waiting for the variable length of time and optically detecting the reflected light until the media sheet has been completely optically scanned.

15. The method of claim 14, further comprising determining the variable length of time each time the variable length of time is to be waited for, by one of:

adding a random value to a target value, the random value having a lower value having a lower negative limit and an upper positive limit;

looking up the variable length of time within a predefined table of variable lengths of time; and

,

performing a mathematical function to yield the variable length of time.

16. The method of claim 14, wherein an average of the variable length of time waited over all times the variable length of time has been waited in optically scanning the media sheet is at least substantially equal to a predetermined target value.

17. An optical scanning device comprising:

a light source to illuminate each of a plurality of linear portions of a media sheet as each linear portion becomes incident to the light source;

a light-detecting mechanism to detect light from the light source as reflected by at least one of a plurality of positions of each linear portion of the media sheet as the positions of each linear portion of the media sheet become incident to the light source; and

,

an advancement mechanism to effectively advance the media sheet relative to the light source and the light-detecting mechanism,

wherein the light-detecting mechanism and the advancement mechanism functionally cooperate so that the linear portions of the media sheet are irregularly spaced relative to one another.

18. The optical scanning device of claim 17, wherein the linear portions are irregularly spaced relative to one another in that distances between immediately adjacent linear portions of the media sheet are not necessarily equal to one another.

19. The optical scanning device of claim 17, wherein irregular spacing of the linear portions of the media sheet is achieved by the advancement mechanism effectively advancing the media sheet by variable amounts and the light-detecting mechanism detecting the light as reflected by one of the linear portions of the media sheet after each time the media sheet has been effectively advanced by one of the variable amounts.

20. The optical scanning device of claim 17, wherein irregular spacing of the linear portions of the media sheet is achieved by the advancement mechanism effectively advancing the media sheet at a constant velocity and the light-detecting mechanism repeatingly detecting the light as reflected by one of the linear portions of the media sheet after waiting for a variable length of time.

21. An optical scanning device comprising:

means for illuminating each of a plurality of irregularly spaced linear portions of a media sheet;

means for detecting light from the light source as reflected by each irregularly spaced linear portion of the media sheet; and

,

means for effectively advancing the media sheet.

22. The optical scanning device of claim 21, wherein the irregularly spaced linear portions are irregularly spaced relative to one another such that distances between immediately adjacent linear portions of the media sheet are not necessarily equal to one another.

23. An optical scanning device comprising:

a light source to illuminate each of a plurality of linear portions of a media sheet as each linear portion becomes incident to the light source;

a light-detecting mechanism to detect light from the light source as reflected by at least one of a plurality of positions of each linear portion of the media sheet as the positions of each linear portion of the media sheet become incident to the light source; and

,

an advancement mechanism to effectively advance the media sheet relative to the light source and the light-detecting mechanism,

wherein the light-detecting mechanism and the advancement mechanism have a first mode of operation in which the linear portions of the media sheet are irregularly spaced relative to one another and a second mode of operation in which the linear portions of the media sheet are regularly spaced relative to one another.

24. The optical scanning device of claim 23, wherein the linear portions are irregularly spaced relative to one another in the first mode of operation such that distances between immediately adjacent linear portions of the media sheet are not necessarily equal to one another.

25. The optical scanning device of claim 23, wherein the optical scanning device is to recommend to a user thereof to select the first mode of operation when the media sheet to be scanned contains half-toned graphical images, and to otherwise select the second mode of operation.