Light scanning device, optical device, and scanning method of optical device

• US 6,172,788 B1
• Filed: 01/24/2000
• Issued: 01/09/2001
• Est. Priority Date: 12/16/1996
• Status: Expired due to Fees

• Current Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Original Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Inventors: Suzuki, Takayoshi, Toda, Tsuneo, Sekikawa, Yoshihito
• Primary Examiner(s): Phan, James
• Application Number:
  US09/490,077
• Time in Patent Office: 351 Days
• Field of Search: 359/204, 359/216-219, 347/232-235, 347/237, 347/241-243, 250/234-236, 358/474, 358/481, 358/494
• US Class Current: 359/204.1
• CPC Class Codes: G02B 26/123 Multibeam scanners, e.g. using multiple light sources or beam splitters
• 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 1/0473 in subscanning direction, e.g. picture start or line-to-line synchronisation
• CPC Class Codes: H04N 1/1135 for the main-scan only
• 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 1/192 Simultaneously or substantially simultaneously scanning picture elements on one main scanning line
• CPC Class Codes: H04N 2201/03158 Heat radiator
• CPC Class Codes: H04N 2201/03162 Original guide plate
• CPC Class Codes: H04N 2201/0471 using dedicated detectors
• CPC Class Codes: H04N 2201/04712 using unbroken arrays of detectors, i.e. detectors mounted on the same substrate
• CPC Class Codes: H04N 2201/04729 in the main-scan direction
• CPC Class Codes: H04N 2201/04731 in the sub-scan direction
• 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 2201/04767 by controlling the timing of the signals, e.g. by controlling the frequency o phase of the pixel clock
• CPC Class Codes: H04N 2201/04787 by changing or controlling the addresses or values of pixels, e.g. in an array, in a memory, by interpolation
• CPC Class Codes: H04N 2201/04789 in the main-scan direction
• CPC Class Codes: H04N 2201/04791 in the sub-scan direction

Abstract

A light scanning device deflects a plurality of light beams by a deflecting means performs divided scanning on a single scanning line on a photoconductor with the plurality of deflected light beams. When the scanning line is scanned, a detecting means detects a light beam passing through a predetermined position in front of a position where the light beam first strikes an image forming range on the photoconductor. An oscillating means oscillates a specified number of clocks in a time interval from when the light beam is detected by the detecting means until it is detected thereby again. An adjusting means makes adjustments so as to irradiate a plurality of light beams based on clocks oscillated by the oscillating means. In a time interval after the light beam is detected by the detecting means until it is detected thereby again, a plurality of light beams are irradiated based on the specified number of clocks. Therefore, even if unevenness occurs in the deflecting speed of the deflecting means, dots can be formed at the same intervals in scanning a plurality of scanning lines. Thus, it is possible to prevent discontinuous joints occurring in each of the images formed with a plurality of light beams.

Claims

1. A light scanning device wherein a plurality of light beams are irradiated, the plurality of irradiated light beams are deflected by a deflecting means and divided scanning is performed on each scanning line of a photoconductor by the deflected plurality of light beams,

said light scanning device comprising:

a detection means for detecting light beams passing through at least one of either a predetermined position in front of a position where the light beam first strikes the image forming range of said photoconductor, or another predetermined position behind a position where the light beam last strikes the image forming range of said photoconductor, when said scanning line is scanned;

an oscillating means for oscillating a specified number of clocks in an interval of time from when the light beam is detected by said detecting means until the light beam is detected again; and

an adjusting means for adjusting the plurality of light beams so as to be irradiated according to the clocks oscillated by said oscillating means.

8. A light scanning device according to claim 1 wherein the length of a beam diameter of said deflecting means, striking said deflecting face for deflecting said plurality of light beams in said scanning direction, is larger than the length of said deflecting face in said scanning direction.

2. A light scanning device wherein a plurality of light beams are irradiated, the plurality of irradiated light beams are deflected by a deflecting means and divided scanning is performed on each scanning line of a photoconductor by the deflected plurality of light beams,

said light scanning device further comprising:

an adjusting means for adjusting the irradiation timing of at least one of either a predetermined light beam or another light beam so that the shortest distance becomes a predetermined value according to information on said shortest distance in a scanning line direction between the foremost dot of an image forming range and the rearmost dot of another image forming range, the image forming ranges being formed by scanning said scanning line once with a predetermined light beam from the plurality of light beams and said other light beam adjacent to the predetermined light beam.

3. A light scanning device according to claim 2 further comprising:

a detection means for detecting a light beam passing through a predetermined first position in front of a position where the light beam first strikes an image forming range of said photoconductor and another predetermined second position behind a position where the light beam last strikes an image forming range of said photoconductor when said scanning line is scanned once;

an oscillating means for oscillating a specified number of clocks in an interval of time from when a light beam passing through at least any one of either said first position or said second position is detected, until the light beam passing through at least one of either said first position or said second position is detected again, when said scanning line is scanned once; and

a counting means for counting the clocks oscillated in an interval of time from when a light beam passing through said first position is detected, until the light beam passing through said second position is detected, when said scanning line is scanned once

wherein said adjusting means compares said counted clocks with a predetermined number thereof and according to the result of the comparison, adjusts the irradiation timing of at least one of either said predetermined light beam or said other light beam so that said shortest distance becomes a predetermined value.

4. A light scanning device wherein a plurality of light beams are irradiated, the plurality of irradiated light beams are deflected by a deflecting means and divided scanning is performed on each scanning line of a photoconductor by the deflected plurality of light beams,

said light scanning device further comprising:

a storage means for storing image data for a plurality of scanning lines, corresponding to each of the image forming ranges formed by scanning said scanning line with said plurality of light beams; and

an adjusting means in which when the distance between a scanning line scanned by a predetermined light beam of said plurality of light beams and another scanning line scanned by another light beam adjacent to the predetermined light beam is larger than a predetermined value, when said scanning line is scanned once, said image data of said predetermined light beam and said image data of said other light beam are selectively read from said storage means so that said distance is within said predetermined value and further when said scanning line is scanned, adjustment is carried out so that said predetermined light beam and said another light beam are each irradiated based on their respective read image data.

6. A light scanning device according to claim 4 further comprising:

a light receiving means for receiving a light beam passing through a predetermined position in front of a position where the light beam first strikes the image forming range of said photoconductor and a predetermined position behind a position where the light beam last strikes the image forming range of said photoconductor when said photoconductor is scanned with said plurality of light beams,

wherein said adjusting means determines whether or not said interval is more than the predetermined value based on the light receiving condition of said light receiving means after said scanning line is scanned once.

5. A light scanning device wherein a plurality of light beams are irradiated, the plurality of irradiated light beams are deflected by a deflecting means and divided scanning is performed on each scanning line of a photoconductor by the deflected plurality of light beams,

said light scanning device further comprising:

an adjusting means in which when the distance between a scanning line scanned by a predetermined light beam of said plurality of light beams and another scanning line scanned by another light beam adjacent to the predetermined light beam is less than a predetermined value, as a result of scanning said scanning line once, an image forming range in which the scans by said predetermined light beam and said other light beam overlap is provided for scanning said scanning line, and further adjustment is carried out so that the total incident light volume for each dot of said predetermined light beam striking the image forming range which is scanned overlappingly, and said other light beam, is substantially equal to the incident light volume for each dot of said predetermined light beam striking the image forming range other than the image forming range which is scanned overlappingly, and said other light beam.

7. A light scanning device according to claim 5 further comprising:

a light receiving means for receiving a light beam passing through a predetermined position in front of a position where the light beam first strikes the image forming range of said photoconductor and a predetermined position behind a position where the light beam last strikes the image forming range of said photoconductor when said photoconductor is scanned with said plurality of light beams,

wherein said adjusting means determines whether or not said interval is more than the predetermined value based on the light receiving condition of said light receiving means after said scanning line is scanned once.