Identification of text

• US 20070164882A1
• Filed: 01/13/2006
• Published: 07/19/2007
• Est. Priority Date: 01/13/2006
• Status: Active Grant

• Current Assignee: Mineral Lassen LLC (Intellectual Ventures LLC)
• Original Assignee: Essex PA LLC (Intellectual Ventures LLC)
• Inventors: Monro, Donald
• Granted Patent: US 8,674,855 B2
• Time in Patent Office: Days
• US Class Current: 341/51
• CPC Class Codes: G06F 16/90344 by using string matching techniques
• CPC Class Codes: G06F 16/93 Document management systems

Abstract

A method of generating a code representative of a passage of text uses in the preferred embodiment the character spacing between respective occurrences of a selected key symbol string within the text. The string may be fixed, or may encompass a variety of different forms. By comparing the known code of a target text passage with the code generated from a sample text passage, it is easy to determine whether the target text has been used within the sample. The method may be integrated within a copying device such as a photocopier, allowing the device report automatically whenever a user attempts to copy a document bearing one of a predefined list of sensitive or controlled text passages.

Claims

1. A method of generating a code representative of a passage of text comprising the steps of identifying within the passage positions at which a key symbol string occurs, determining distances between selected occurrences of the key symbol string, and generating a code including said distances.

2. A method as claimed in claim 1 in which the code includes a plurality of distances corresponding to respective distances between adjacent key symbol strings within the passage.

3. A method as claimed in claim 1 in which said distances are determined according to the number of characters between said occurrences.

4. A method as claimed in claim 1 in which said distances are determined according to the number of characters between said occurrences and also according to the number of lines of text between said occurrences.

5. A method as claimed in claim 1 in which the key symbol string comprises a single fixed string of one or more characters.

6. A method as claimed in claim 1 in which the key symbol string is variable, and may comprise any one of a plurality of pre-defined fixed strings of one or more characters.

7. A method as claimed in claim 1 in which the key symbol string comprises a first selected string spaced apart from a second selected string.

8. A method as claimed in claim 1 in which the said spacing is fixed.

9. A method as claimed in claim 1 in which the said spacing is variable or computed.

10. A method as claimed in claim 1 in which the key symbol string comprises a first selected string spaced apart from a second selected string and having, between them, a selected number of occurrences of one or more further strings.

11. A method as claimed in claim 1 in which said code includes the key symbol string or a definition of how the key symbol string is constructed.

12. A method of determining whether a target passage of text occurs within a sample passage, the method comprising the steps of:

(a) generating by using a submethod a target code representative of the target passage and a sample code representative of the sample passage, the submethod including the steps of identifying within the passage positions at which a key symbol string occurs, determining distances between selected occurrences of the key symbol string, and generating a code including said distances;

(b) comparing the target code with portions of the sample code; and

,

(c) if the target code and a portion of the sample code match, according to required matching criteria, determining that the target passage of text does occur within the sample passage.

13. A copying device for making physical or electronic copies of a physical document bearing text, the device comprising:

(a) an imager for generating an image of the physical document;

(b) an OCR engine for converting said text into sample text in electronic form;

(c) an analyser for generating from said sample text a sample code, said code including distances between selected occurrences within the sample text of a key symbol string;

said analyser receiving a plurality of pre-computed target codes representative of target text passages of interest, comparing the target codes with portions of the sample code, and if the target code and a portion of the sample code match according to required matching criteria, generating a signal indicating the matching target text passage; and

,

(d) a controller for receiving said signal and for taking action in dependence upon said signal.

14. A copying device as claimed in claim 13 in which the controller controls operation of the device.

15. A copying device as claimed in claim 13 in which the controller passes a message to a computer network.