REMOTE DOCUMENT SCANNER

• US 3,584,144 A
• Filed: 08/23/1968
• Issued: 06/08/1971
• Est. Priority Date: 08/23/1968
• Status: Expired due to Term

• Current Assignee: David H Shepard, Edward J. Gushue
• Original Assignee: David H Shepard, Edward J. Gushue
• Inventors: Shepard, David H., Gushue, Edward J.
• Application Number:
  US04/755,001
• Time in Patent Office: 1,019 Days
• US Class Current: 358/481
• CPC Class Codes: G06V 10/12 Details of acquisition arrangements; Constructional details thereof
• CPC Class Codes: H04N 1/028 for picture information pick-up
• CPC Class Codes: H04N 1/1135 for the main-scan only

Abstract

An optical scanning unit particularly adapted for use in remote optical character recognition systems or the like and including a document feed drum together with a rotating mirror arranged to sweep a narrow beam of light on a scan path across the drum while the latter is stationary between indexing steps, there being provided adjacent the scan path an elongate strip of semiconducting material of the PIN type arranged to produce electrical output signals in response to incident light reflected from the scanning sweep across the document, thereby to develop scan signals indicating the presence or absence of character elements along the scan path.

Claims

1. In a document scanner comprising means to support a document in position to be scanned, means to sweep a narrow beam of light along a scan path extending across the document, means to detect the amount of light reflected from the document as the beam scans thereacross, and means to produce electrical signals responsive to the amount of reflected light at points along the scan path;

that improvement, especially adapted for scanning wide documents, wherein the light detector means comprises a largearea section of light-sensitive semiconducting material aligned with the part of said document swept by said beam of light and located closely adjacent the document along the full extent of said scan path, so as to receive light reflected from the document substantially uniformly along the entire scan path, whatever its length.

2. Apparatus as claimed in claim 1, wherein said semiconductor material is in the form of a thin film which produces a flow of current in response to incident light.

3. Apparatus as claimed in claim 2, wherein said semiconductor comprises silicon with thin film coatings on both sides;

and power supply means providing a reverse bias for said semiconductor.

4. In a character reading system of the type including scanning apparatus for generating signals corresponding to data scanned from a document bearing graphic characters, the scanning apparatus comprising:

(1) drum means for advancing the document in discrete incremental steps;

(2) means operable between advancing steps to sweep a narrow beam of light across the document along a scan path parallel to the drum axis; and

(3) means to detect the amount of light reflected from the document as the beam scans thereacross;

That improvement wherein the light detector means comprises an elongate light-sensitive strip extending parallel to the drum axis closely adjacent the scan path across the document to receive the light reflected therefrom.

5. Apparatus as claimed in claim 4, including clock track means extending parallel to said drum axis and comprising an elongate light-sensitive strip;

and means to sweep a clock beam across said clock track in synchronism with said narrow beam of light.

6. Apparatus as claimed in claim 5, wherein both of said light sensitive strips comprise silicon junction devices serving as thin film photodiodes.

7. Apparatus as claimed in claim 4, wherein the light source for said narrow beam of light is a laser producing a beam which is polarized in a predetermined orientation;

and a polarizing filter positioned between the document and said light-sensitive strip to discriminate against light having said predetermined orientation of polarization.

8. In a character reading system of the type inclUding scanning apparatus for generating signals corresponding to data scanned from a document bearing graphic characters to be identified, the scanning apparatus comprising means to irradiate the document with light and means to detect the amount of light reflected from a scanning path on the document so as to produce corresponding electrical signals for character analysis;

That improvement wherein the irradiating light is polarized in a predetermined orientation; and

a polarizing filter is positioned between the document and the light detector means to discriminate against reflected light having a polarization of said predetermined orientation, whereby to reduce detection of light reflected from nonabsorptive character elements such as those formed of graphite.

9. A character reading system as claimed in claim 8, wherein the light is derived from a laser to produce a narrow beam which is swept across the surface of the document.

10. A system as claimed in claim 9, wherein the reflected light is detected by an elongate strip of semiconducting material closely adjacent the scan path across the document;

the polarizing filter comprising a strip parallel to said elongate strip.