Scanner that scans to film

• US 8,149,481 B2
• Filed: 10/04/2007
• Issued: 04/03/2012
• Est. Priority Date: 10/04/2006
• Status: Active Grant

• Current Assignee: IDEMIA Identity and Security France SAS (Advent International Corporation)
• Original Assignee: Sagem Scurite
• Inventors: Dufresne du Virel, Francois
• Primary Examiner(s): Lee, Cheukfan
• Application Number:
  US11/906,834
• Publication Number:
  US 20080088890A1
• Time in Patent Office: 1,643 Days
• Field of Search: 358/514, 358/512, 358/513, 358/483, 358/482, 358/450, 358/496, 358/498, 358/497, 358/494, 358/505, 358/474, 250/208.1, 359/639, 359/618, 359/489.07
• US Class Current: 358/514
• CPC Class Codes: H04N 1/03 with photodetectors arranged in a substantially linear array
• CPC Class Codes: H04N 1/0305 with multiple folds of the optical path
• CPC Class Codes: H04N 1/12 using the sheet-feed movement or the medium-advance or the drum-rotation movement as the slow scanning component, e.g. arrangements for the main-scanningsheet-feed movement by translatory movement of a flat picture-bearing surface H04N1/1008; main-scanning using oscillating or rotating mirrors H04N1/113; using multi-element arrays H04N1/19
• CPC Class Codes: H04N 1/193 using electrically scanned linear arrays , e.g. linear CCD arrays
• CPC Class Codes: H04N 1/486 with separate detectors, each detector being used for one specific colour component
• CPC Class Codes: H04N 2201/02493 Additional optical elements not otherwise provided for, e.g. filters, polarising plates, masks or apertures

Abstract

The invention relates to a sheet-fed scanner (300) comprising:

• • an illumination device for emitting a luminous flux covering several spectral bands which is intended to illuminate a sheet (204) to be scanned,
  • a focussing device (150), and
  • a detection module (360) comprising a sensor (164) which comprises a plurality of rows (166, 168, 170) of sensitive elements, each sensitive element being provided to deliver an electrical energy that is proportional to the intensity of the luminous flux received, and each row being provided to have its sensitivity peak for one of said spectral bands,
  • the focussing device being provided to focus, onto each of the rows, part of the luminous flux reflected by said sheet,
  • the sheet-fed scanner (300) being characterised in that the detection module (360) comprises a non-prismatic spectral shift device (305) for shifting each part of the luminous flux thus focussed, parallel to said rows (166, 168, 170), the shift being different for each row (166, 168, 170).

Claims

1. A sheet-fed scanner (300) comprising:

an illumination device (102) for emitting a luminous flux covering several spectral bands (λ

₁, λ

₂, λ

₃) which is intended to illuminate a sheet (204) to be scanned,

a focussing device (150), and

a detection module (360) comprising a sensor (164) which comprises a plurality of rows (166, 168, 170) of sensitive elements, each sensitive element being provided to deliver an electrical energy that is proportional to the intensity of the luminous flux received, and each row being provided to have its sensitivity peak for one of said spectral bands,

the focussing device being provided to focus, onto each of the rows, part of the luminous flux reflected by said sheet,

the sheet-fed scanner (300) being characterised in that the detection module (360) comprises a non-prismatic spectral shift device (305, 705) for shifting each part of the luminous flux thus focussed, parallel to said rows (166, 168, 170), the shift (δ

₁, δ

₂) being different for each row (166, 168, 170).

2. The sheet-fed scanner (300) of claim 1, wherein the shift generated between two consecutive rows by the spectral shift device (305, 1205) is close to the ratio of the width of one sensitive element to the number of rows (166, 168, 170).

3. The sheet-fed scanner (300) of claim 1, wherein the sensor comprises three rows (166, 168, 170) and, relative to the first shifted flux (302a), the second shifted flux (302b) is shifted by approximately one-third of a sensitive element and the third shifted flux (302c) is shifted by approximately two-thirds of a sensitive element.

4. The sheet-fed scanner (300) of claim 1, characterised in that it comprises a band-pass filter for said spectral bands.

5. The sheet-fed scanner (300) of claim 1, wherein the spectral shift device consists of an optical wave plate (305) which is inclined (α

) with respect to the plane of the sensor (164).

6. The sheet-fed scanner (300) of claim 1, wherein the spectral shift device consists of an optical wave plate (705), on one of the faces of which a succession of microprisms is formed.

7. The sheet-fed scanner (300) of claim 6, wherein the other face of the optical wave plate (705) carrying the succession of microprisms is in contact with the sensor (164).

8. The sheet-fed scanner (300) of claim 6, wherein each microprism is arranged above an integer number of sensitive elements and only above entire sensitive elements.

9. The sheet-fed scanner (300) of claim 1, wherein the spectral shift device consists of a diffractive element placed at a distance from the sensor (164).

10. A detection module (360) comprising:

a sensor (164) which comprises a plurality of rows (166, 168, 170) of sensitive elements, each row (166, 168, 170) being provided to receive a luminous flux, and

a non-prismatic spectral shift device (305, 705) for shifting each flux parallel to said rows (166, 168, 170), the shift (δ

₁, δ

₂) being different for each row (166, 168, 170).

11. The detection module (360) of claim 10, wherein the spectral shift device consists of an optical wave plate (305) which is inclined (α

) with respect to the plane of the sensor (164).

12. The detection module (360) of claim 10, wherein the spectral shift device consists of an optical wave plate (705), on one of the faces of which a succession of microprisms is formed.

13. The detection module (360) of claim 12, wherein the other face of the optical wave plate carrying the succession of microprisms is in contact with the sensor (164).

14. The detection module (360) of claim 12, wherein each microprism is arranged above an integer number of sensitive elements and only above entire sensitive elements.

15. The detection module (360) of claim 10, wherein the spectral shift device consists of a diffractive element placed at a distance from the sensor (164).