Page identification by detection of optical characteristics

• US 5,900,943 A
• Filed: 08/29/1997
• Issued: 05/04/1999
• Est. Priority Date: 08/29/1997
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Owen, Geraint
• Primary Examiner(s): Evans, F. L.
• Application Number:
  US08/921,396
• Time in Patent Office: 613 Days
• Field of Search: 356/402, 356/406, 356/407, 356/425, 250/226
• US Class Current: 356/406
• CPC Class Codes: G06V 30/10 Character recognition
• CPC Class Codes: G06V 30/1444 Selective acquisition, locating or processing of specific regions, e.g. highlighted text, fiducial marks or predetermined fields

Abstract

This disclosure relates to a page identification system for multiple page processing systems which operates by measuring color. Detected color is compared to a look-up table that stores color characteristics for at least one known page. If a match is detected, within a tolerance selected in response to expected measurement variance, then the system produces a page identification code used in page processing. Preferably, the system is embodied in a clipboard device that automatically associates electronic data with a corresponding one of multiple pages. A stylus can be used to write on each page, and each time the stylus is used, the system automatically optically scans the page, produces a page identification code, and associates electronic data with the current page. If no match is detected in the lookup table, then the system enters a learn mode corresponding to presumed detection of a new page. Background light variations are compensated for, in part, by intensity modulating a light source at different frequencies for each of red, green and blue components, and by normalizing the detected components to adjust for total detected light. The system is expected to have utility in a wide range of paper processing systems.

Claims

1. In a page handling system that receives and distinguishes different pages, at least one page having a particular color associated therewith and adapted for having printed material thereon, a page identification system adapted to identify one page from amongst multiple pages according to the associated color, comprising:

a light source adapted to direct light onto at least one of the multiple pages;

a light detector adapted to sense light from the at least one of the multiple pages, the light detector producing an electronic output representing detected light;

a look-up table adapted to store color characteristics of at least one known page;

a processor that compares detected light as represented by the electronic output with the color characteristics, to detect a match between the detected light and the color characteristics of a known page, and if a match is detected, that provides an electronic output identifying that the match has occurred; and

means for learning new pages if a match is not detected, and for storing color characteristics of the new page in the look-up table such that the new page can be subsequently identified as a known page;

wherein the page processing system may thereby distinguish and subsequently track at least one of the multiple pages based on color.

2. A page identification system according to claim 1, wherein the light source produces light in at least two different wavelengths.

3. A page identification system according to claim 1, wherein the light source produces light in at least three different wavelengths.

4. A page identification system according to claim 1, further comprising means for accommodating variation in measurement distance between the multiple pages and at least one of the light source and the light detector.

5. A page identification system according to claim 1, wherein the light from the light source is shone onto a predetermined side of the multiple pages and wherein the light detector receives light which has been reflected from the predetermined side.

6. A page identification system according to claim 5, further comprising means for accommodating variation in incidence angle of light which has been reflected from the predetermined side.

7. A page identification system according to claim 5, wherein the light source is a modulated light source that provides light having intensity modulated according to a predetermined pattern.

8. A page identification system according to claim 7, wherein the light source produces light of multiple wavelengths, each wavelength being intensity modulated at a different pattern.

9. A page identification system according to claim 1, wherein:

said page identification system further comprises at least one a defined tolerance region;

the processor is controlled by one of software and firmware to detect a match based upon difference between detected color and color characteristics stored in the look-up table which falls within the tolerance region.

10. A page identification system according to claim 1, further comprising means for normalizing light intensity in a measured wavelength according to total light.

11. A page identification system according to claim 1, further comprising one of firmware and software that implements a learn function, such that if no match is detected between detected light and color characteristics of the multiple pages, then color characteristics corresponding to the detected light are stored in the look-up table as a new entry.

12. A page identification system according to claim 1, wherein the page handling system associates with at least one particular page electronic data representing printed material unique to that particular page, said page handling system further comprising means for electronically associating the electronic data with a color unique to the particular page.

13. A page identification system adapted to identify one page from amongst multiple pages according to page color, comprising:

a light source adapted to direct light onto at least one of the multiple pages;

a light detector adapted to sense light from the at least one of the multiple pages, the light detector producing an electronic output representing detected light;

a look-up table adapted to store color characteristics of at least one known page; and

a processor that compares detected light as represented by the electronic output with the color characteristics, to detect a match between the detected light and the color characteristics of a known page, and if a match is detected, that provide an electronic output identifying that the match has occurred;

a wand adapted for manual scanning of a page surface by a user;

a base unit that houses the light source and the light detector;

at least one optical fiber for coupling light between the base unit and the wand.

14. A page identification system according to claim 13, wherein:

the wand includes a writing tip adapted to contact a page surface and a tip-down switch that provides an electronic indication when the writing tip is in contact with the page surface; and

said page identification system is responsive to the electronic indication to sample color from the page surface.

15. A page identification system according to claim 14, wherein:

the wand includes an optical port, the optical port oriented so as to receive reflected light from the page surface in a substantially normal direction from the page surface in response to a normal writing inclination angle.

16. A page identification system according to claim 13, wherein:

the wand produces a stream electronic stylus data;

the processor, in response to the match, produces a form identification code and inserts the code into the stream of electronic stylus data.

17. A page identification system adapted to identify one page from amongst multiple pages according to page color, comprising:

a light source adapted to direct light onto at least one of the multiple pages;

a light detector adapted to sense light from the at least one of the multiple pages, the light detector producing an electronic output representing detected light;

a look-up table adapted to store color characteristics of at least one known page;

a processor that compares detected light as represented by the electronic output with the color characteristics, to detect a match between the detected light and the color characteristics of a known page, and if a match is detected, that provide an electronic output identifying that the match has occurred; and

a tolerance region which is substantially circular or polygonal in a color plane;

wherein the processor is controlled by one of software and firmware to detect a match based upon difference between detected color and color characteristics stored in the look-up table which falls within the tolerance region.

18. A system, comprising:

an electronic clipboard having a digitizer section and a stylus which is tethered to the digitizer section, the digitizer section adapted to support multiple pages and the stylus and digitizer adapted to generate a data stream corresponding to stylus strokes upon the multiple pages;

a page identification system for distinguishing between the multiple pages and associating data within the data stream individual ones of the multiple pages, the page identification system including

a light source adapted to direct light onto at least one of the multiple pages,

a light detector adapted to sense light from the at least one of the multiple pages, the light detector producing an electronic output representing detected light,

a look-up table adapted to store color characteristics of the multiple pages, and

a processor that compares detected light as represented by the electronic output with the color characteristics, to detect a match between the detected light and the color characteristics of one page, and if a match is detected, that provide an electronic output identifying that the match has occurred; and

a mechanism associated with the clipboard and responsive to the electronic output for inserting a page identification code into the data stream, such that a subset of data within the data stream is automatically associated with an intended one of the multiple pages, notwithstanding that the user switches between writing upon different ones of the multiple pages.

19. In a processing system that handles different physical pages, wherein each page is made of a material having a particular color and has associated electronic data, a page identification system adapted to identify one page from amongst multiple pages according to page color without, comprising:

a light source adapted to direct light onto at least one of the multiple pages;

a light detector adapted to sense light from the at least one of the multiple pages, the light detector producing an electronic output representing detected light;

a look-up table adapted to store color characteristics of at least one known page;

a processor that compares detected light as represented by the electronic output with the color characteristics, to detect a match between the detected light and the color characteristics of a known page, and that

provides, if a match is detected, an electronic output identifying that the match has occurred, and

learns new pages if a match is not detected, by storing color characteristics of the new page in the look-up table such that the new page can be subsequently identified as a known page;

wherein the electronic output responsively causes association of at least some electronic data with the processing system may thereby distinguish and treat the different pages based on color.