KR20000052148A - Laser scanning unit - Google Patents

Abstract

PURPOSE: An optical scanning unit is provided to significantly reduce time required for calculating value for correcting linearity and eliminate additional jig while measuring linearity of scanning line scanned to a photosensitive medium and feeding back the measured linearity to a laser driving unit so as to correct non-linearity. CONSTITUTION: An optical scanning unit comprises a driving source(11) for supplying a rotatory force, a deflection disk(13) provided with a plurality of sectors having a hologram pattern for diffractively deflecting incident light and which is installed to a rotational axis of the driving source(11) and rotates to form a scanning line, an optical source(15) positioned to face a surface of the deflection disk(13) so as to scan a light to a predetermined portion of the deflection disk, an optical path converting unit for converting proceeding path of the scanning line formed by the rotation of the deflection disk(13) such that the scanning line is directed to a first path directed to a photosensitive medium(10) or to a predetermined second path, a detection unit(30) installed in the second path so as to detect scanning speed of the scanning line, a circuit unit for transmitting linearity correction data in accordance with the detection value from the detection unit(30) to a driver unit for driving the optical scanning unit.

Description

Gwangju company unit {Laser scanning unit}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light scanning unit capable of deflecting scanning of incident light, and more particularly, to measuring a linearity of a scanning line scanned on a photosensitive medium and feeding it back to a light scanning unit driving unit for non-linearity. It relates to a linearity-correctable optical scanning unit that can correct).

Referring to FIG. 1, the optical scanning unit employing the deflection disk as a conventional beam deflector has a drive disk 11 for providing rotational force and a deflection disk 13 having a plurality of sectors 14 each having a hologram pattern 14a. ), A light source 15 disposed on one surface of the deflection disc 13 and irradiating light onto the deflection disc 13, and light scanned by the deflection disc 13 by the deflection disc 13 is subjected to the main scan of the photosensitive medium 10. And optical path changing means for changing the traveling direction so as to scan in the direction. Here, the optical path converting means includes a planar mirror (M) for converting the traveling path so as to secure a traveling path, a curved mirror (CM) for correcting bow and aberration, and reflected from the curved mirror (CM). It comprises a hologram element (HOE) for diffracting the scanning line toward the photosensitive medium (10).

The optical scanning unit forms scan lines corresponding to the number of sectors 14 on which the hologram pattern 14a is formed during one rotation of the deflection disk 13. When the hologram pattern 14a is formed as shown in Fig. 2, and the deflection disk 13 is rotated in the clockwise direction, the formed scan line is scanned starting at point P1 in the direction of arrow Ds and scanned to point P2. . The scanned light is scanned onto the photosensitive surface of the photosensitive medium 10 via the planar mirror M, the curved mirror CM, and the hologram element HOE.

On the other hand, the optical scanning unit configured as described above has a problem of forming an electrostatic latent image on the photosensitive medium 10 which is inconsistent with a desired image due to the difference in scanning speed of the scanning beam scanned along the arrow Ds. In this way, the degree of scanning speed difference of the scanning beam is referred to as linearity. This linearity problem has a greater effect on the image as the resolution of the desired image increases.

A conventional method for correcting the linearity is to use a separate jig to measure the gap between scanning light and store it in a memory, and then to store the linearity based on the stored correction data value when used in a set of an image forming apparatus. There is a method of controlling the scanning start timing.

On the other hand, in this case, if it causes an external shock of the optical fiber unit or a position change of the optical system due to repair, it is cumbersome to use a separate jig to detect correction data, and it takes a long time to obtain a linearity correction value. There is a problem.

Accordingly, the present invention has been made in view of the above-mentioned point, and measures the linearity of the scanning line scanned on the photosensitive medium and feeds it back to the laser driver so that the non-linearity can be corrected. The purpose of the present invention is to provide a linearity-correctable optical fiber unit.

1 is a schematic view showing the optical arrangement of the optical scanning unit using a conventional deflection disk.

FIG. 2 is a schematic front view of the deflection disk shown in FIG.

3 is a view showing an optical arrangement of a linearity correctable optical scanning unit according to a first embodiment of the present invention.

Figure 4 is a schematic exploded perspective view showing a hologram element and a hologram element driver according to an embodiment of the present invention.

5 is a view showing a detector and a circuit unit according to an embodiment of the present invention.

6 is a view showing an optical arrangement of a linearity correctable optical scanning unit according to a second embodiment of the present invention.

7 is a view showing an optical arrangement of a linearity correctable multi-light scanning unit according to a third embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

10 ... photosensitive medium 11 ... drive 13 ... deflection disc

15 1st light source 20 ... hologram element 25 ... holder

27 ... guide protrusion 30 ... detector 33 ... photodetector

40 Drive part 41 Drive motor 43 Support member

45 Power transmission unit 50 Circuit unit 51 Output unit

55 Storage 60 LSU drive 100 Frame

M, M ₁₁ , M ₁₂ , M ₂₁ , M ₂₂ , M ₃₁ , M ₃₂ , M ₄₁ , M ₄₂ ...

CM ₁ to CM ₄ ... Bending mirror HOE ₁ to HOE ₄ ... Hologram element

In order to achieve the above object, the optical fiber unit according to the present invention includes a drive source for providing a rotational force; A deflection disk having a plurality of sectors having a hologram pattern for diffracting and deflecting incident light, said deflection disk being provided on a rotation axis of said drive source and forming a scanning line by rotation; A light source positioned opposite to one surface of the deflecting disk and irradiating light to a predetermined position of the deflecting disk; Optical path changing means for converting the traveling path so that the scanning line formed by the rotation of the deflection disk is directed to the first path or the second predetermined path toward the photosensitive medium; A detection unit provided in the second path and detecting a scanning speed of the scanning line; And a circuit unit which transmits linearity correction information to the optical scanning unit driver from the value detected by the detection unit.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 to 5, the optical scanning unit according to the first embodiment of the present invention is a drive source 11 for providing a rotational force, and a deflection disk 13 for forming a scanning line while being rotated by the drive source 11 And a light source 15 for irradiating light to a predetermined position of the deflection disc 13, optical path converting means for converting the traveling path of the incident scanning line, a detection unit 30 for detecting the scanning speed of the scanning line, and And a circuit unit 50 that calculates and stores the linearity correction value from the value detected through the detection unit 30.

As shown in FIG. 2 described above, the deflection disk 13 has a plurality of sectors 14 each having a hologram pattern 14a formed thereon, and is provided on a rotation shaft of the drive source 11. The light source 15 is disposed on one surface of the deflection disk 13 to irradiate light on the deflection disk 13. The optical path converting means converts the scan line deflected by the deflection disc 13 so that the scanning line is scanned in the main scanning direction of the photosensitive medium 10 and is directed toward the detection unit 30. That is, the optical path converting means converts the traveling path so that the incident scanning line is directed toward the first path I or the predetermined second path II directed to the photosensitive medium 10.

To this end, the optical path converting means drives the planar mirror M, the curved mirror CM, and the hologram element 20 and the hologram element 20 disposed from the deflection disc 13 toward the photosensitive medium 10. It comprises a drive unit (40 in Fig. 4) for.

The planar mirror M converts the traveling path of the light by reflecting the incident scanning line so as to secure the traveling path of the incident scanning line. The curved mirror CM focuses and reflects light incident through the planar mirror M to correct the bow and aberration. The hologram element 20 is rotatably disposed between the curved mirror CM and the photosensitive medium 10 to diffract and transmit the incident scanning line to travel to the first path I or the second path II. .

Referring to FIG. 4, both ends of the hologram element 20 are fixed by the holder 25. The holder 25 has a guide protrusion 27 which is connected by the driving unit 40 and rotatably installed in the installation hole 100a formed in the frame 100. The drive unit 40 is installed in the frame 100, the support member 43 for supporting the guide projection 27 to be rotatable, the drive motor 41 for providing a rotational force, and the drive It is configured to include a power transmission unit 45 for transmitting the power of the motor 41 to the guide projection (27). Here, the support member 43 preferably has a bearing structure in which the outer ring is fixed to the frame 100 through the bush and the inner ring is coupled to the guide protrusion 27.

The rotational angle of the hologram element 20 is determined by the rotational force provided from the driving motor 41, and the scanning line incident according to the rotational angle is scanned in the first path I or the second path II. do. Here, the drive motor is controlled in accordance with the start / end of the linearity measurement mode.

4 and 5, the detector 30 is disposed on the second path II to detect the scanning speed of the scan line scanned through the second path II. To this end, the detection unit 30 is preferably arranged in a linear array structure 31 so as to measure the scanning speed of the incident scanning line, and each includes a plurality of photodetectors 33 independently photoelectric conversion.

The circuit unit 50 calculates the linearity correction value by calculating the value detected by the detection unit 30, and stores the calculated value. To this end, the circuit unit 50 includes a calculation unit 51 for calculating the linearity correction value from the value input through the detection unit 30, and a storage unit 55 for storing the correction value calculated by the calculation unit 51. And a clock generator 57 for generating a clock based on the stored correction value. Therefore, the linearity correction value stored in the storage unit 55 is transmitted to the optical scanning unit drive unit 60 which drives the light source 11 and the deflection disk 13 to correspond to the input image signal. The light source and the deflection disc are driven with linearity corrected. The clock generator 57 may be driven independently of each sector of the deflection disk 13 to overcome an error due to a difference in characteristic values of each sector.

Referring to FIG. 6, the optical scanning unit according to the second embodiment of the present invention includes a driving source 11 providing a rotational force, a deflection disk 13 forming a scanning line while being rotated by the driving source 11, and A light source 15 for irradiating light to a predetermined position of the deflection disc 13, optical path converting means for converting the advancing path of the incident scan line, a detector 30 for detecting the scanning speed of the scan line, and the detector 30 And a circuit unit (60 in FIG. 5) for calculating and storing the linearity correction value from the value detected through). The present embodiment is characterized in that the structure of the optical path changing means is changed from the above-described first embodiment, and the driving source 11, the deflection disk 13, the light source 15, the detecting unit 30 and the circuit unit ( 60 is substantially the same as the member using the same reference numerals described above with reference to FIGS. 2 to 5 in the first embodiment, and thus detailed description thereof is omitted.

The optical path changing means includes a planar mirror (M), a curved mirror (CM), a hologram element (HOE), a movable mirror (70), and a movable mirror (70) disposed from the deflection disk (13) toward the photosensitive medium (10). It is configured to include a driving unit (not shown) for driving the.

The planar mirror M converts the traveling path of the light by reflecting the incident scanning line so as to secure the traveling path of the incident scanning line. The curved mirror CM focuses and reflects light incident through the planar mirror M to correct the bow and aberration. The hologram element HOE diffracts and transmits the incident scanning line toward the photosensitive medium 10. The movable mirror 70 is selectively disposed between the hologram element HOE and the photosensitive medium 10 so that the incident scanning line is selectively directed to the first path I or the second path II. . The driving unit is a structure that is capable of reciprocating rotational driving or sliding driving of the movable mirror 70, and a detailed description thereof will be omitted.

Here, the movable mirror is controlled according to the start / end of the linearity measuring mode, and the scan line passing through the hologram element HOE is the first path I or the second path II according to the position of the movable mirror. Is injected.

Referring to FIG. 7, the optical fiber unit according to the third embodiment of the present invention will be described in detail. The photowangsa unit according to the present embodiment is a multi-jumbo optical unit suitable for a color image forming apparatus.

The optical scanning unit includes a deflection disk 115 having a driving source 111, a plurality of sectors each having a hologram pattern formed thereon, and one surface of the deflection disk 115 for irradiating light to the deflection disk 115. A detection unit for detecting the linearity of the scanning line by receiving a light selected from the light source 120, the optical path converting means for converting the deflection-scanned light from the deflection disk 115, and the light passing through the optical path converting means ( 140) and a circuit unit (not shown) for calculating the linearity correction value from the detected values and storing the calculated values.

The light source 120 is provided in plural to correspond to the color image. The light source 120 includes four first to fourth light sources 121, 123, 125, and 127 to be suitable for, for example, yellow (Y), magenta (M), cyan (C), and black (K) colors. It can be composed of). In this case, each of the light emitted from the first to fourth light sources 121, 123, 125, and 127 and incident on the deflection disk 115 is incident on a predetermined position of the deflection disk 115.

Here, the optical path converting means may include a plurality of plane mirrors M ₁₁ , M ₁₂ , M ₂₁ , M ₂₂ , M ₃₁ , M ₃₂ , M ₄₁ , M ₄₂ and a plurality of plane mirrors M other than the plane mirrors described above. ), Curved mirrors (CM ₁ , CM ₂ , CM ₃ , CM ₄ ) and hologram elements (HOE ₁ , HOE ₂ , HOE ₃ , HOE ₄ ).

Each of the curved mirrors CM ₁ to CM ₄ focuses and reflects the scan lines incident on the plurality of optical paths through the planar mirrors M to maintain parallel scan lines. Further, the bow, which is a warpage phenomenon of the scan line caused by the diffraction of the incident light by the hologram pattern and the rotation of the deflection disk 115, is formed.

The hologram elements HOE ₁ to HOE ₄ diffractively transmit the incident scanning lines by a predetermined angle so that the scanning lines are directed in a direction substantially perpendicular to the photosensitive medium 10.

In addition, by rotating at least one of the plurality of hologram elements (HOE ₁ , HOE ₂ , HOE ₃ , HOE ₄ ), the first path (I) and the detection unit 140 toward the photosensitive medium 10 are rotated. Can be converted to the second path (II). In the present embodiment, the hologram element 130 is driven to rotate.

Therefore, in the linearity measurement and correction mode, the hologram element 130 is rotated so that the incident scan line is directed to the second path II, and the linearity degree can be detected using the detector 140. Here, the rotational driving and detection method of the hologram element 130 is as described with reference to Figures 3 to 5, so a detailed description thereof will be omitted.

The present invention may employ a movable mirror (not shown) for converting an optical path between the hologram element 130 and the photosensitive medium 10 instead of the rotational driving of the hologram element 130.

The optical scanning unit according to the present invention configured as described above includes means for measuring and correcting the linearity of the incident scanning line, thereby correcting the non-linearity, thereby greatly reducing the time required for calculating the linearity correction value. It can be, and there is an advantage that a separate jig or the like is unnecessary.

Claims (6)

A drive source for providing a rotational force; A deflection disc having a plurality of sectors having a hologram pattern for diffracting deflection of incident light, the deflection disc being provided on a rotation axis of the drive source to form a scan line by rotation; A light source positioned opposite to one surface of the deflecting disk and irradiating light to a predetermined position of the deflecting disk; Optical path changing means for converting the traveling path so that the scanning line formed by the rotation of the deflection disk is directed to the first path or the second predetermined path toward the photosensitive medium; A detection unit provided in the second path and detecting a scanning speed of the scanning line; And a circuit unit which transmits linearity correction information to the optical scanning unit driver from the value detected by the detection unit. The method of claim 1, wherein the optical path conversion means, A plane mirror which reflects the light scanned by the deflection disk and secures a traveling path of the light; A curved mirror which focuses and reflects the light incident through the plane mirror; A hologram element rotatably disposed between the curved mirror and the photosensitive medium, the hologram element diffraction-transmitting the incident scanning line to travel in a first path or a second path; And a driving unit for rotating the hologram device. The method of claim 1, wherein the optical path conversion means, A plane mirror which reflects the light scanned by the deflection disk and secures a traveling path of the light; A curved mirror which focuses and reflects the light incident through the plane mirror; A hologram element diffraction-transmitting the scanning line focused by the curved mirror; A movable mirror selectively disposed between the hologram element and the photosensitive medium such that the incident scanning line is selectively directed to the first path or the second path; And a driving unit for driving the movable mirror. The detector according to any one of claims 1 to 3, wherein And a photodetector arranged in a linear array structure so as to measure the scanning speed of the scanning line incident through the second path, each photoelectric conversion independently. The circuit part according to any one of claims 1 to 3, wherein A calculator for calculating a linearity correction value from a value input through the detector; A storage unit for storing the correction value calculated by the calculation unit; And a clock generator for generating a clock based on the stored correction value, wherein the light source and the deflection disk can be driven with linearity corrected with respect to an input image signal. 6. The optical scanning unit of claim 5, wherein the clock generator generates a clock independently for each sector of the deflection disk.