Scanner with deflection element for scanning imaging surfaces

• US 5,923,461 A
• Filed: 07/31/1998
• Issued: 07/13/1999
• Est. Priority Date: 08/30/1996
• Status: Expired due to Term

• Current Assignee: Hanger Solutions, LLC (IP Investments Group LLC)
• Original Assignee: Agfa Corporation (Agfa-Gevaert N.V.)
• Inventors: Allen, Roy D., Scholten, Frank
• Primary Examiner(s): Ben, Loha
• Application Number:
  US09/127,611
• Time in Patent Office: 347 Days
• Field of Search: 359/305, 359/204, 359/209, 359/211, 359/220, 359/311, 359/312, 358/491, 358/493
• US Class Current: 359/305
• CPC Class Codes: B41B 19/00 Photoelectronic composing machines
• CPC Class Codes: B41J 2/473 using multiple light beams, wavelengths or colours
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: H04N 1/047 Detection, control or error compensation of scanning velocity or position H04N1/0402 and H04N1/17 take precedence
• CPC Class Codes: H04N 1/053 in main scanning direction, e.g. synchronisation of line start or picture elements in a line
• CPC Class Codes: H04N 1/0607 Scanning a concave surface, e.g. with internal drum type scanners H04N1/0657 takes precedence
• CPC Class Codes: H04N 1/0635 using oscillating or rotating mirrors
• CPC Class Codes: H04N 1/1911 Simultaneously or substantially simultaneously scanning picture elements on more than one main scanning line, e.g. scanning in swaths
• CPC Class Codes: H04N 2201/02439 Positioning method
• CPC Class Codes: H04N 2201/0471 using dedicated detectors
• CPC Class Codes: H04N 2201/04732 Detecting at infrequent intervals, e.g. once or twice per line for main-scan control
• CPC Class Codes: H04N 2201/04734 Detecting at frequent intervals, e.g. once per line for sub-scan control
• CPC Class Codes: H04N 2201/04744 by detecting the scanned beam or a reference beam
• CPC Class Codes: H04N 2201/0476 using an optical, electro-optical or acousto-optical element
• CPC Class Codes: H04N 2201/04765 using a solid-state deflector, e.g. an acousto-optic deflector
• CPC Class Codes: H04N 2201/04786 Controlling a start time, e.g. for output of a line of data H04N2201/04784 takes precedence
• CPC Class Codes: H04N 2201/04794 Varying the control or compensation during the scan, e.g. using continuous feedback or from line to line

Abstract

A multi-beam scanning system for scanning a curved imaging surface includes at least one radiation emitter which emits first and second beams of radiation. A spin deflector, rotatable about a spin axis, directs the first beam to form a first scan line and the second beam to form a second scan line on the imaging surface. A deflection element, disposed in the path of the first beam and upstream of the spin deflector, operates to deflect the first beam with respect to the rotation of the spin deflector. The spin deflector is impinged by beams of radiation only at a distance, other than zero, from the spin axis.

Claims

1. A multi-beam scanning system for scanning a curved imaging surface, comprising:

at least one radiation emitter configured to emit a first beam of radiation and a second beam of radiation;

a spin deflector, rotatable about a spin axis, configured to direct the first beam to form a first scan line and the second beam to form a second scan line on the imaging surface; and

a deflection element, disposed in the path of the first beam and upstream of the spin deflector, operable to deflect said first beam with respect to the spin axis of the spin deflector;

wherein the spin deflector is impinged by beams of radiation only at a distance, other than zero, from the spin axis.

2. The system of claim 1, wherein the deflection element is a multi-channel acousto-optic element.

3. The system of claim 1, further comprising:

a beam combiner, disposed in the path of the first and the second beams and upstream of the spin deflector, configured to combine the first beam and the second beam.

4. The system of claim 1, further comprising:

a pixel clock operable to issue a signal for timing the emitting of radiation from one of the at least one radiation emitter and the operation of the deflection element; and

a phase shifter operable to adjust the timing of the signal;

wherein the deflection element is operable to deflect the first beam to move linearly across the spin deflector; and

wherein the pixel clock and the phase shifter are operable in synchrony with the operation of the deflection element to phase shift the first beam.

5. The system of claim 4, wherein the phase shift is approximately tan (θ

/2), where θ

is an angle of rotation of the spin deflector.

6. The system of claim 1, further comprising:

a detector configured to detect a geometric relationship between the second beam and the first beam.

7. The system of claim 6, further comprising:

a controller configured to control the operation of the deflection element in accordance with the detected relationship.

8. The system of claim 1, wherein the deflection element is operable to deflect the first beam in a first direction, and further comprising:

a translating element operable to deflect the first beam in a second direction; and

the deflection of the first beam in the first and the second directions causes the first beam to move in synchrony with the rotation of the spin deflector about the spin axis such that the first scan line and the second scan line are non-intersecting.

9. A beam positioning device for moving a beam emitted by an emitter across a spin deflector of a multi-beam scanning system, comprising:

a deflection element, disposed in the path of the beam and upstream of said spin deflector, operable to deflect the beam so as to impinge upon the spin deflector at a particular location;

a pixel clock operable to issue a signal for timing one of the emitting of radiation from the emitter and the operation of the deflection element; and

a phase shifter operable to adjust the timing of the signal;

wherein the pixel clock and the phase shifter are operable in synchrony with the operation of the deflection element to phase shift the beam.

10. The device of claim 9, further comprising:

a detector configured to detect a geometric relationship between the beam and at least one other beam of the multi-beam scanning system;

wherein the operation of the deflection element is controlled in accordance with the detected relationship.

11. The device of claim 9, wherein the deflection element is a multi-channel acousto-optic element.

12. A multi-beam scanning system for scanning a curved imaging surface, comprising:

at least one radiation emitter configured to emit a first beam of radiation and a second beam of radiation;

a spin deflector, rotatable about a spin axis, configured to direct the first beam to form a first scan line and the second beam to form a second scan line on said imaging surface; and

a multi-channel acousto-optic element, disposed in the path of the first beam and the path of the second beam and upstream of said spin deflector, operable to deflect said first beam and the second beam with respect to the spin axis of the spin deflector.

13. The system of claim 12, further comprising:

a pixel clock operable to issue a signal for timing one of the emitting of radiation from one of the at least one emitter and the operation of the deflection element; and

a phase shifter operable to adjust the timing of the signal;

wherein the acouto-optic element is operable to deflect the first beam and the second beam to move linearly across the spin deflector, and the pixel clock and the phase shifter are operable in synchrony with the operation of the deflection element to phase shift the first beam and the second beam.

14. The system of claim 13, wherein the phase shift is approximately tan (θ

/2), where θ

is an angle of rotation of the spin deflector.

15. The system of claim 12, further comprising:

a detector configured to detect a geometric relationship between the second beam and the first beam.

16. The system of claim 15, further comprising:

a controller configured to control the deflection element in accordance with the detected relationship.

17. The system of claim 12, wherein the deflection element is operable to deflect the first beam in a first direction, and further comprising:

a translating element operable to deflect the first beam in a second direction;

wherein the deflection of the first beam in the first and the second directions causes the first beam to move in synchrony with the rotation of the spin deflector about the spin axis such that the first scan line and the second scan line are non-intersecting.

18. A method of scanning a curved imaging surface with multiple beams, comprising the steps of:

emitting a first beam of radiation and a second beam of radiation;

rotating a spin deflector about a spin axis to direct the first beam to form a first scan line and the second beam to form a second scan line on the imaging surface; and

acousto-optically deflecting at least one of the first and the second beams with respect to the spin axis of the spin deflector;

wherein the spin deflector is impinged by radiation beams only at a distance, other than zero, from the spin axis.

19. The method of claim 18, further comprising the step of:

timing the emitting of at least one of the first and the second beams;

wherein the acousto-optic deflection of the at least one of the first and the second beams deflects the at least one of the first and the second beams in a first direction; and

the timing of the emitting of the at least one of the first and the second beams is synchronized with the acousto-optic deflecting of the at least one of the first and the second beams to phase shift the at least one of the first and the second beams to deflect the at least one of the first and the second beams in a second direction orthogonal to the first direction.

20. The method of claim 19, wherein the phase shift is approximately tan (θ

/2), where θ

is an angle of rotation of the spin deflector.

21. A method for scanning a curved imaging surface with multiple beams, comprising the steps of:

emitting a first beam of radiation and a second beam of radiation;

deflecting at least one of the first beam and the second beam to impinge upon a spin deflector at a particular location; and

issuing a signal for timing one of the emitting and the deflecting;

wherein the signal is issued in synchrony with the deflecting to phase shift the at least one of the first and the second beams at approximately tan (θ

/2), where θ

is an angle of rotation of the spin deflector.

22. The method of claim 21, further comprising the step of:

detecting a geometric relationship between the first beam and the second beam;

controlling the deflecting is in accordance with the detected relationship.