WO2005116721A1 - Anamorphic laser scanning device - Google Patents

Anamorphic laser scanning device Download PDF

Info

Publication number
WO2005116721A1
WO2005116721A1 PCT/EP2004/005726 EP2004005726W WO2005116721A1 WO 2005116721 A1 WO2005116721 A1 WO 2005116721A1 EP 2004005726 W EP2004005726 W EP 2004005726W WO 2005116721 A1 WO2005116721 A1 WO 2005116721A1
Authority
WO
WIPO (PCT)
Prior art keywords
scanning device
laser scanning
anamorphic
speed
writing
Prior art date
Application number
PCT/EP2004/005726
Other languages
French (fr)
Inventor
Bart Wattyn
Original Assignee
Strobbe Graphics Nv
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Strobbe Graphics Nv filed Critical Strobbe Graphics Nv
Priority to PCT/EP2004/005726 priority Critical patent/WO2005116721A1/en
Publication of WO2005116721A1 publication Critical patent/WO2005116721A1/en

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/047—Detection, control or error compensation of scanning velocity or position
    • H04N1/053—Detection, control or error compensation of scanning velocity or position in main scanning direction, e.g. synchronisation of line start or picture elements in a line
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/10—Scanning systems
    • G02B26/12—Scanning systems using multifaceted mirrors
    • G02B26/127—Adaptive control of the scanning light beam, e.g. using the feedback from one or more detectors
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/113—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using oscillating or rotating mirrors
    • H04N1/1135—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using oscillating or rotating mirrors for the main-scan only
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
    • H04N2201/024—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted
    • H04N2201/02406—Arrangements for positioning elements within a head
    • H04N2201/02439—Positioning method
    • H04N2201/02443—Positioning method using adhesive
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
    • H04N2201/04—Scanning arrangements
    • H04N2201/047—Detection, control or error compensation of scanning velocity or position
    • H04N2201/04701—Detection of scanning velocity or position
    • H04N2201/0471—Detection of scanning velocity or position using dedicated detectors
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
    • H04N2201/04—Scanning arrangements
    • H04N2201/047—Detection, control or error compensation of scanning velocity or position
    • H04N2201/04701—Detection of scanning velocity or position
    • H04N2201/04734—Detecting at frequent intervals, e.g. once per line for sub-scan control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
    • H04N2201/04—Scanning arrangements
    • H04N2201/047—Detection, control or error compensation of scanning velocity or position
    • H04N2201/04701—Detection of scanning velocity or position
    • H04N2201/04744—Detection of scanning velocity or position by detecting the scanned beam or a reference beam
    • H04N2201/04746—Detection of scanning velocity or position by detecting the scanned beam or a reference beam after modulation by a grating, mask or the like
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
    • H04N2201/04—Scanning arrangements
    • H04N2201/047—Detection, control or error compensation of scanning velocity or position
    • H04N2201/04753—Control or error compensation of scanning position or velocity
    • H04N2201/04758—Control or error compensation of scanning position or velocity by controlling the position of the scanned image area
    • H04N2201/04767—Control or error compensation of scanning position or velocity by controlling the position of the scanned image area by controlling the timing of the signals, e.g. by controlling the frequency o phase of the pixel clock
    • H04N2201/04768—Controlling the frequency of the signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
    • H04N2201/04—Scanning arrangements
    • H04N2201/047—Detection, control or error compensation of scanning velocity or position
    • H04N2201/04753—Control or error compensation of scanning position or velocity
    • H04N2201/04794—Varying the control or compensation during the scan, e.g. using continuous feedback or from line to line
    • H04N2201/04798—Varying the main-scan control during the main-scan, e.g. facet tracking

Definitions

  • the invention relates to an anamorphic laser scanning device comprising a light source and means for generating a writing beam with a particular on/off frequency in function of particular data, e.g. text, photos, images.
  • the invention also relates to a method for writing data on a medium, using an anamorphic laser scanning device according the invention.
  • the anamorphic system substantially reduces the imaging system's sensitivity to cross scan errors of the scanning optic by compressing the beam in the cross scan direction onto the scanning optic.
  • the errors may be either fixed or random, such as wobble or pyramidal error. This technique is previously known in the art, as described in US patent number 3750189 (J.M. Fleischer) .
  • FIG. 1 illustrates a schematic view of a prior art laser scanning device
  • Such devices comprise a laser source (1) which produces a writing beam (2) and a polygon (5) which receives the laser beam.
  • the polygon (5) has a plurality of facets whereby only on is operative at a given time to reflect the writing beam (2) via an optical system (3; ; 5; 6; 7 ; 8 ; 9) towards an image plane (10) .
  • Each facet is operative to scan at least one line of the plane.
  • it In order for a laser scanning device to operate at high accuracy and resolution, it must accurately control the location of the writing beam (2) on the image plane (10) . Therefore it is known in current system on the market to work with two photocells (23; 24), whereby one photocell (23) detects the start of the scan and the other photocell (24) detects the end of the scan.
  • the two photocell signals are fed into an oscillator (17) whereby the oscillator (17) generates a clock signal (18) in phase of the two photocell signals.
  • the laser driver (19) switches the laser on or off in function of the clock signal (18) and the computer data (20).
  • Another known principle use the two photocells to detect the velocity of the scan line, this is used to modify a clock coming from a separate oscillator resident in the system electronics, which creates a pixel clock.
  • Fig. 2 illustrates the disadvantage of the prior art scanning devices
  • the two photocells (23; 24) measuring the total time between the start of the scan and the end of the scan (see Fig. 2b) .
  • a pixel clock is generated (see Fig. 2c) .
  • a polygon speed variation (as illustrate in Fig. 2a) occurs during the time from begin of scan and end of scan, than this polygon speed variation will only be detected by the end photocell at the end of scan.
  • the pixel clock will not been corrected during the scan and on the other hand the laser driver will send the data on the wrong time to the laser, as a result the pixels will be placed on the wrong position on the image plane (see Fig. 2d) .
  • an anamorphic laser scanning device comprising a light source and means for generating a writing beam with a particular on/off frequency, in function of particular data whereby the device comprises:
  • a reference laser source for generating a reference beam, provided to follow at least a part of the optical path of the writing beam;
  • the reference beam is folded into the optical system and travels virtually the same path as the writing beam. If any inaccuracies (speed variation, distortion, misalignments) occur during the scan, than this variation is the same for the writing beam as for the reference beam.
  • the difference between the path of the writing beam and the path of the reference beam occurs preferably after passing the final mirror.
  • said detecting means comprises a reference scale and means for generating a reference signal indicating the position and/or speed of the reference beam relative to said reference scale.
  • the detecting means comprises a number of light detectors provided along the reference scale in order to detect the position and/or speed of the reference beam relative to the reference scale.
  • the light detectors are preferable photo cells.
  • the reference scale is divided into non-transparent zones and transparent zones, and the said light detectors are provided for generating a reference signal if the reference beam travels through the transparent zone and reach said light detectors .
  • said controlling means comprises an oscillator provided for generating a clock signal based on the reference signal and a laser driver provided for controlling the on/off frequency in accordance with this clock signal.
  • the clock signal is preferable a pixel clock signal.
  • the laser driver is provided for switching the light source on or off in function of the clock signal and the data stored in a computer memory.
  • the light source is a red laser.
  • the advantage of a red laser is the fact that most media on the market is not sensitive for red laser light. As a result, any uncontrolled stray reference light will have no influence on the media. However, other laser colours can be used, if the eventually stray light is blocked from the media.
  • This patent application also relates to a method for writing data on a medium, using an anamorphic laser scanning device whereby :
  • a writing beam is generated in accordance with particular data and with a particular on/off frequency;
  • a reference beam is generated such that is follows at least a part of the optical path of the writing beam;
  • the position and/or speed of the reference beam is detected;
  • the on/off frequency of the writing beam is controlled in function of the detected position or speed of the reference beam.
  • FIG. 1 is a schematic view of a prior art laser scanning device
  • FIG. 2 illustrates the disadvantage of the prior art scanning devices
  • Fig. 2a is a graphical representation of the polygon speed
  • Fig. 2b is a graphical representation of the start and end photo cell
  • Fig. 2c is a graphical representation of the pixel clock signal
  • Fig. 2d is a graphical representation of the pixels on the image plane
  • FIG. 5 illustrates the effect of the invention on the image plan when for example a speed variation occur during the scan
  • Fig. 5a is a graphical representation of the polygon speed
  • Fig. 5b is a graphical representation of the reference signal
  • Fig. 5c is a graphical representation of the pixel clock signal
  • Fig. 5d is a graphical representation of the pixels on the image plane.
  • the device (25) according to the invention can be applied to expose one or several photosensitive plates over their entire width.
  • the laser scanning device (25) consists of a light source (1) , preferably a red laser, and means for generating a writing beam (2) with a particular on/off frequency, in function of particular data (20) .
  • the data (20) can be for example text, kanji characters, photographs or drawings and is stored in a computer memory (21) .
  • the laser emanate a writing beam (2) with a wavelength of e.g. 405, 532 nm. onto a cylindrical lens (3) after which the writing beam (2) become an anamorphic beam (2b) .
  • the writing beam (2b) After being reflected by a mirror (4), the writing beam (2b) passes via a rotating scanning optic, e.g. a polygon (5), to a lens system (6). After passing the lens system ( ⁇ ) the writing beam (2b) reflects on a first folding mirror (7) to the final folding mirror (8). After reflecting the final folding mirror (8), the writing beam (2b) proceeds via a third mirror (9) to the image plane (10) .
  • the anamorphic laser scanning device (25) further comprises a reference laser source (11), e.g. 635 nm red, for generating a reference beam (12) .
  • the reference beam (12) is folded into the optical system and travels virtually the same path as the writing beam (2b) , obtaining all the same inaccuracies that the writing beam (2b) obtains. Instead of proceeding to the image plane (10), the reference beam (12) will travel, after reflecting on the final folding mirror (8), towards detecting means (13) for detecting the position and/or speed of the reference beam (12) .
  • the detecting means (13) comprises a reference scale (14) and means (15) for generating a reference signal (16) indicating the position and/or speed of the reference beam (12) relative to said reference scale (14).
  • the detecting means (13) comprises a number of light detectors (15) , preferably photocells, provided along the reference scale (14) in order to detect the position and/or speed of the reference beam (12) relative to the reference scale (14) .
  • the reference scale (14) is divided into non-transparent zones (26) and transparent zones (27) . When the reference beam (12) passes through the reference scale (14) and is detected by the photocells (15) , the photocells (15) will generate a reference signal (16) .
  • the anamorphic laser scanning device further comprise means for controlling (17, 18, 19) said on/off frequency of the writing beam (2b) in function of the detected position and/or speed of the reference beam (12) .
  • the controlling means comprises an oscillator (17) for generating a clock signal (18), preferably a pixel clock signal, based on the reference signal (16) and a laser driver (19) provided for controlling the on/off frequency.
  • the reference signal (16) is fed into the oscillator (17), the oscillator (17) will generate the clock signal (18) and the laser driver (19) switches the laser (1) on or off in function of the clock signal (18) and the computer data (20) .
  • the advantage of the anamorphic laser scanning device according to the invention is that if any inaccuracies for example speed variation of the polygon (5) , distortion, misalignments, ... occurs during the scan, than this variation is the same for the writing beam (2b) as for the reference beam (12) .
  • reference scale (14) could easily be placed near the image plane (10) so that the reference (12) and writing beams (2b) do not have to separate before the final mirror (8) .

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mechanical Optical Scanning Systems (AREA)
  • Facsimile Scanning Arrangements (AREA)

Abstract

The invention relates to an anamorphic laser scanning device (25) comprising a light source (1) and means for generating a writing beam (2) with a particular on/off frequency, in function of particular data (20) whereby the device comprises: a reference laser source (11) for generating a reference beam (12), provided to follow at least a part of the optical path of the writing beam (2); means (13) for detecting the position and/or speed of the reference beam (12); and means (17, 18, 19) for controlling said frequency in function of the detected position and/or speed of the reference beam (12).

Description

Anamorphic laser scanning device
The invention relates to an anamorphic laser scanning device comprising a light source and means for generating a writing beam with a particular on/off frequency in function of particular data, e.g. text, photos, images. The invention also relates to a method for writing data on a medium, using an anamorphic laser scanning device according the invention.
The anamorphic system substantially reduces the imaging system's sensitivity to cross scan errors of the scanning optic by compressing the beam in the cross scan direction onto the scanning optic. The errors may be either fixed or random, such as wobble or pyramidal error. This technique is previously known in the art, as described in US patent number 3750189 (J.M. Fleischer) .
Anamorphic system laser scanning devices are known in the state of the art, as shown in Figure 1 and to now reference is made (Fig. 1 illustrates a schematic view of a prior art laser scanning device) . Such devices comprise a laser source (1) which produces a writing beam (2) and a polygon (5) which receives the laser beam.
The polygon (5) has a plurality of facets whereby only on is operative at a given time to reflect the writing beam (2) via an optical system (3; ; 5; 6; 7 ; 8 ; 9) towards an image plane (10) . Each facet is operative to scan at least one line of the plane. In order for a laser scanning device to operate at high accuracy and resolution, it must accurately control the location of the writing beam (2) on the image plane (10) . Therefore it is known in current system on the market to work with two photocells (23; 24), whereby one photocell (23) detects the start of the scan and the other photocell (24) detects the end of the scan. The two photocell signals are fed into an oscillator (17) whereby the oscillator (17) generates a clock signal (18) in phase of the two photocell signals. The laser driver (19) switches the laser on or off in function of the clock signal (18) and the computer data (20).
Another known principle use the two photocells to detect the velocity of the scan line, this is used to modify a clock coming from a separate oscillator resident in the system electronics, which creates a pixel clock.
In a third known principle only one photocell is used at the start of the scan. This oscillator triggers a separate oscillator, which creates a pixel clock.
The disadvantage of the current systems, as shown in Figure 2 to which now reference is made (Fig. 2 illustrates the disadvantage of the prior art scanning devices) is that the two photocells (23; 24) measuring the total time between the start of the scan and the end of the scan (see Fig. 2b) . Out of this total time, a pixel clock is generated (see Fig. 2c) . However, if a polygon speed variation (as illustrate in Fig. 2a) occurs during the time from begin of scan and end of scan, than this polygon speed variation will only be detected by the end photocell at the end of scan. Because on the one hand the pixel clock will not been corrected during the scan and on the other hand the laser driver will send the data on the wrong time to the laser, as a result the pixels will be placed on the wrong position on the image plane (see Fig. 2d) .
Also the systems described above cannot generally compensate for residual inaccuracies in the system design (image distortion) or for inaccuracies due to misalignment of the system optics.
Some of the current systems apply a fixed "curve" to create a non-linear pixel clock, so these systems can compensate for fixed errors (i.e. image distortion), but they can't still correct for changing inaccuracies, such as those due to speed variations, thermal misalignments or misalignments due to mechanical shock and vibration. Therefore it is the purpose of this invention to provide an anamorphic laser scanning device which is independent from speed variations in the polygon speed.
This purpose is achieved by an anamorphic laser scanning device comprising a light source and means for generating a writing beam with a particular on/off frequency, in function of particular data whereby the device comprises:
- a reference laser source for generating a reference beam, provided to follow at least a part of the optical path of the writing beam; - means for detecting the position and/or speed of the reference beam;
- and means for controlling said frequency in function of the detected position and/or speed of the reference beam.
The reference beam is folded into the optical system and travels virtually the same path as the writing beam. If any inaccuracies (speed variation, distortion, misalignments) occur during the scan, than this variation is the same for the writing beam as for the reference beam. The difference between the path of the writing beam and the path of the reference beam occurs preferably after passing the final mirror.
In a preferred embodiment of the invention said detecting means comprises a reference scale and means for generating a reference signal indicating the position and/or speed of the reference beam relative to said reference scale.
According to a more preferred embodiment of the laser scanning device, the detecting means comprises a number of light detectors provided along the reference scale in order to detect the position and/or speed of the reference beam relative to the reference scale. The light detectors are preferable photo cells. The reference scale is divided into non-transparent zones and transparent zones, and the said light detectors are provided for generating a reference signal if the reference beam travels through the transparent zone and reach said light detectors .
According to a specific embodiment said controlling means comprises an oscillator provided for generating a clock signal based on the reference signal and a laser driver provided for controlling the on/off frequency in accordance with this clock signal. The clock signal is preferable a pixel clock signal.
In a more specific embodiment of the scanning device according to the invention, the laser driver is provided for switching the light source on or off in function of the clock signal and the data stored in a computer memory.
In a most preferred embodiment the light source is a red laser. The advantage of a red laser is the fact that most media on the market is not sensitive for red laser light. As a result, any uncontrolled stray reference light will have no influence on the media. However, other laser colours can be used, if the eventually stray light is blocked from the media.
This patent application also relates to a method for writing data on a medium, using an anamorphic laser scanning device whereby :
- a writing beam is generated in accordance with particular data and with a particular on/off frequency; - a reference beam is generated such that is follows at least a part of the optical path of the writing beam; - the position and/or speed of the reference beam is detected;
- the on/off frequency of the writing beam is controlled in function of the detected position or speed of the reference beam.
The characteristics and further advantages of the invention will be further explained on the basis of non- restricting exemplifying embodiments represented in the attached drawings and in the following detailed description. In this description reference is made to the following drawings in which :
- Figure 1 is a schematic view of a prior art laser scanning device;
- Figure 2 illustrates the disadvantage of the prior art scanning devices; Fig. 2a is a graphical representation of the polygon speed; Fig. 2b is a graphical representation of the start and end photo cell; Fig. 2c is a graphical representation of the pixel clock signal; Fig. 2d is a graphical representation of the pixels on the image plane;
- Figure 3 the anamorphic laser scanning device according an embodiment of the invention;
- Figure 4 is a detailed view of the reference means;
- Figure 5 illustrates the effect of the invention on the image plan when for example a speed variation occur during the scan; Fig. 5a is a graphical representation of the polygon speed; Fig. 5b is a graphical representation of the reference signal; Fig. 5c is a graphical representation of the pixel clock signal; Fig. 5d is a graphical representation of the pixels on the image plane.
The device (25) according to the invention can be applied to expose one or several photosensitive plates over their entire width.
As represented in figure 3, the laser scanning device (25) consists of a light source (1) , preferably a red laser, and means for generating a writing beam (2) with a particular on/off frequency, in function of particular data (20) . The data (20) can be for example text, kanji characters, photographs or drawings and is stored in a computer memory (21) .
The laser emanate a writing beam (2) with a wavelength of e.g. 405, 532 nm. onto a cylindrical lens (3) after which the writing beam (2) become an anamorphic beam (2b) .
After being reflected by a mirror (4), the writing beam (2b) passes via a rotating scanning optic, e.g. a polygon (5), to a lens system (6). After passing the lens system (β) the writing beam (2b) reflects on a first folding mirror (7) to the final folding mirror (8). After reflecting the final folding mirror (8), the writing beam (2b) proceeds via a third mirror (9) to the image plane (10) . The anamorphic laser scanning device (25) further comprises a reference laser source (11), e.g. 635 nm red, for generating a reference beam (12) . As shown in figure 3 the reference beam (12) is folded into the optical system and travels virtually the same path as the writing beam (2b) , obtaining all the same inaccuracies that the writing beam (2b) obtains. Instead of proceeding to the image plane (10), the reference beam (12) will travel, after reflecting on the final folding mirror (8), towards detecting means (13) for detecting the position and/or speed of the reference beam (12) .
The detecting means (13) comprises a reference scale (14) and means (15) for generating a reference signal (16) indicating the position and/or speed of the reference beam (12) relative to said reference scale (14). As shown in figure 4 the detecting means (13) comprises a number of light detectors (15) , preferably photocells, provided along the reference scale (14) in order to detect the position and/or speed of the reference beam (12) relative to the reference scale (14) . The reference scale (14) is divided into non-transparent zones (26) and transparent zones (27) . When the reference beam (12) passes through the reference scale (14) and is detected by the photocells (15) , the photocells (15) will generate a reference signal (16) .
The anamorphic laser scanning device further comprise means for controlling (17, 18, 19) said on/off frequency of the writing beam (2b) in function of the detected position and/or speed of the reference beam (12) . The controlling means comprises an oscillator (17) for generating a clock signal (18), preferably a pixel clock signal, based on the reference signal (16) and a laser driver (19) provided for controlling the on/off frequency. The reference signal (16) is fed into the oscillator (17), the oscillator (17) will generate the clock signal (18) and the laser driver (19) switches the laser (1) on or off in function of the clock signal (18) and the computer data (20) .
The advantage of the anamorphic laser scanning device according to the invention is that if any inaccuracies for example speed variation of the polygon (5) , distortion, misalignments, ... occurs during the scan, than this variation is the same for the writing beam (2b) as for the reference beam (12) .
For example (see figure 5), if a speed increase (fig. 5a) occurs, the reference beam (12) moves faster over the reference scale (14). This generates a faster reference signal (16) (fig. 5b) into the oscillator (17) . The oscillator generates consequently a faster pixel clock (18) (fig. 5c) . This causes the laser driver (19) to write the pixels faster onto the image plane (10) (fig. 5d) . As a result, the pixels are positioned on a perfect distance from each other, regardless of the inaccuracies present .
It is also understood that the reference scale (14) could easily be placed near the image plane (10) so that the reference (12) and writing beams (2b) do not have to separate before the final mirror (8) .

Claims

C L A I M S
1. Anamorphic laser scanning device (25) comprising a light source (1) and means (3; 4; 5; 6; 7 ; 8 ; 9) for generating a writing beam (2) with a particular on/off frequency, in function of particular data (20) characterised in that the device (25) comprises : - a reference laser source (11) for generating a reference beam (12), provided to follow at least a part of the optical path of the writing beam (2) , - means for detecting (13) the position and/or speed of the reference beam (12); and means for controlling (17; 18; 19) said frequency in function of the detected position and/or speed of the reference beam (12).
2. Anamorphic laser scanning device (25) according to claim 1, characterised in that said detecting means (13) comprises a reference scale (14) and means (15) for generating a reference signal (16) indicating the position and/or speed of the reference beam (12) relative to said reference scale (14) .
3. Anamorphic laser scanning device (25) according to claim 1 or 2 characterised in that the detecting means (13) comprises a number of light detectors (15) provided along the reference scale (14) in order to detect the position and/or speed of the reference beam (12) relative to the reference scale (14).
4. Anamorphic laser scanning device (25) according to claim 4, characterised in that the reference scale (14) is divided into non-transparent zones (26) and transparent zones (27), that the said light detectors (15) are provided for generating a reference signal (16) if the reference beam (12) travels through the transparent zone (27) and reach said light detectors (15) .
5. Anamorphic laser scanning device (25) according to any one of the preceding claims, characterised in that said controlling means (17; 19) comprises : an oscillator (17) provided for generating a clock signal (18) based on the reference signal (16); - a laser driver (19) provided for controlling the on/off frequency in accordance with this clock signal (18) .
6. Anamorphic laser scanning device (25) according to claim 5, characterised in that said clock signal (18) is a pixel clock signal.
7. Anamorphic laser scanning device (25) according to claim 5 or 6, characterised in that the laser driver (19) is provided for switching the light source (1) on or off in function of the clock signal (18) and the data (20) stored in a computer memory (21) .
8. Anamorphic laser scanning device (25) according to any one of the preceding claims, characterised in that the light source (1) is a red laser.
9. Method for writing data on a medium (10), using an anamorphic laser scanning device (25) characterised in that - a writing beam (2) is generated in accordance with particular data (20) and with a particular on/off frequency; a reference beam (12) is generated such that is follows at least a part of the optical path of the writing beam (2); the position and/or speed of the reference beam (12) is detected; the on/off frequency of the writing beam (20) is controlled in function of the detected position or speed of the reference beam (12) .
PCT/EP2004/005726 2004-05-25 2004-05-25 Anamorphic laser scanning device WO2005116721A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2004/005726 WO2005116721A1 (en) 2004-05-25 2004-05-25 Anamorphic laser scanning device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2004/005726 WO2005116721A1 (en) 2004-05-25 2004-05-25 Anamorphic laser scanning device

Publications (1)

Publication Number Publication Date
WO2005116721A1 true WO2005116721A1 (en) 2005-12-08

Family

ID=34957750

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2004/005726 WO2005116721A1 (en) 2004-05-25 2004-05-25 Anamorphic laser scanning device

Country Status (1)

Country Link
WO (1) WO2005116721A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2168115A1 (en) * 2007-06-27 2010-03-31 Spudnik, Inc. Servo feedback control based on designated scanning servo beam in scanning beam display systems with light-emitting screens
JP2015022041A (en) * 2013-07-17 2015-02-02 国立大学法人信州大学 Method and mechanism of detecting scanning speed of optical beam

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4667099A (en) * 1984-10-19 1987-05-19 Fuji Photo Film Co., Ltd. Optical linear encoder
US4853535A (en) * 1987-01-14 1989-08-01 Fuji Photo Film Co., Ltd. Light beam scanning device generating a stable synchronizing signal
US5015846A (en) * 1988-07-15 1991-05-14 Asahi Kogaku Kogyo K.K. Light beam control apparatus and linear scale device suitable for use therein
US5247373A (en) * 1989-09-14 1993-09-21 Asahi Kogaku Kogyo Kabushiki Kaisha Scanning optical system
US5852293A (en) * 1996-08-20 1998-12-22 Asahi Kogaku Kogyo Kabushiki Kaisha Raster data drawing apparatus for correcting image starting position
US6326609B1 (en) * 1998-10-12 2001-12-04 Asahi Kogaku Kogyo Kabushiki Kaisha Scanning drawing apparatus

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4667099A (en) * 1984-10-19 1987-05-19 Fuji Photo Film Co., Ltd. Optical linear encoder
US4853535A (en) * 1987-01-14 1989-08-01 Fuji Photo Film Co., Ltd. Light beam scanning device generating a stable synchronizing signal
US5015846A (en) * 1988-07-15 1991-05-14 Asahi Kogaku Kogyo K.K. Light beam control apparatus and linear scale device suitable for use therein
US5247373A (en) * 1989-09-14 1993-09-21 Asahi Kogaku Kogyo Kabushiki Kaisha Scanning optical system
US5852293A (en) * 1996-08-20 1998-12-22 Asahi Kogaku Kogyo Kabushiki Kaisha Raster data drawing apparatus for correcting image starting position
US6326609B1 (en) * 1998-10-12 2001-12-04 Asahi Kogaku Kogyo Kabushiki Kaisha Scanning drawing apparatus

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2168115A1 (en) * 2007-06-27 2010-03-31 Spudnik, Inc. Servo feedback control based on designated scanning servo beam in scanning beam display systems with light-emitting screens
EP2168115A4 (en) * 2007-06-27 2012-08-01 Prysm Inc Servo feedback control based on designated scanning servo beam in scanning beam display systems with light-emitting screens
JP2014112233A (en) * 2007-06-27 2014-06-19 Prysm Inc Scanning beam system and method for controlling scanning beam system
JP2015022041A (en) * 2013-07-17 2015-02-02 国立大学法人信州大学 Method and mechanism of detecting scanning speed of optical beam

Similar Documents

Publication Publication Date Title
CA1145170A (en) Apparatus and method for correcting imperfection in a polygon used for laser scanning
JP2584111B2 (en) How to Modify Pixel Position
US4422099A (en) Optical communication on variable power beam
JPH05278900A (en) Medium sheet position judging device
US4310757A (en) Apparatus for correcting scanning speed in a polygon used for laser scanning
KR100477495B1 (en) Light-scanning optical system and image-forming apparatus comprising the same
US4931637A (en) Scanner utilizing a particular light guide
JPH03162973A (en) Correcting picture element position
US4432598A (en) Image reading and recording apparatus and photodeflector therefor
JP3363235B2 (en) Light beam shift detecting device of image forming apparatus
US5889545A (en) Method and apparatus for image registration in a single pass ROS printer using a rotatable output window with no optical power
US5821971A (en) Image registration for a raster output scanner (ROS) color printer
JP4197556B2 (en) Beam light scanning device
WO2005116721A1 (en) Anamorphic laser scanning device
US3812371A (en) Scanning beam position indicator
KR0132366B1 (en) The laser printing apparatus and method
US20050200929A1 (en) Out of plane start of scan
JP3004407B2 (en) Rotation detection mechanism of rotating polygon mirror
JPH07253552A (en) Image forming device
KR100419219B1 (en) Printer and scanning unit thereof
JPH01105970A (en) Electrophotographic reader/printer
JPH01105271A (en) Electrophotographic reader and printer
JP3141597B2 (en) Optical scanning device
KR101043391B1 (en) Laser scanning unit for image forming apparatus
JP3532359B2 (en) Optical scanning device

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NA NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GM KE LS MW MZ NA SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LU MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: DE

WWW Wipo information: withdrawn in national office

Country of ref document: DE

122 Ep: pct application non-entry in european phase