CN101144904A - Laser scanning unit and image forming apparatus having the same - Google Patents

Abstract

A laser scanning unit includes a light source (110), a rotary polygon mirror (120) to deflect a laser beam emitted from the light source (110), an f-theta lens (130) to image the laser beam deflected from the rotary polygon mirror (120) on a photoconductor (150), and a flat plate (200) disposed between the light source (110) and the photoconductor (150) to correct a scanning line of the light source (110). The laser scanning unit can correct an inclination and/or a curvature of a scanning line caused by rotations of the rotary polygon mirror (120) and the photoconductor (150) and other working and assembling processes in order to minimize a deterioration in other performances, thereby allowing product quality to improve.

Description

Laser scan unit and have the imaging device of this laser scan unit

Technical field

General plotting of the present invention relates to a kind of imaging device, more particularly, relates to a kind of inclination that is used for the correct scan line and/or crooked laser scan unit and has the imaging device of this laser scan unit.

Background technology

Traditional electrophotographic image forming is provided with the laser scan unit that is used for forming electrostatic latent image on photoconductor.

Fig. 1 is schematically illustrated by using single polygonal rotating mirror to form the view of traditional laser scan unit of electrostatic latent image on a plurality of photoconductors.

As shown in Figure 1, laser scan unit comprises a plurality of light sources 1 and polygonal rotating mirror 2, thereby this laser scan unit forms electrostatic latent image on two different photoconductor 5a and 5b.Yet shown in many dotted lines among Fig. 1, the sweep trace of the laser beam of imaging tilts gradually with respect to the end of photoconductor 5a and 5b respectively on photoconductor 5a and 5b.Therefore, in order to form normal image, laser scan unit need be used for the device of the image of correct tilt.

Fig. 2 is the view of another traditional laser scan unit of schematically illustrated device with the inclination that is used for the correct scan line.As shown in Figure 2, inclining scanning line corrective lens (eye protection) 4 is arranged between f-θ lens 3 and the photoconductor 5a, moves forward and backward inclination with the correct scan line to allow inclining scanning line corrective lens (eye protection) 4 with respect to the direction of scanning.Therefore, when a plurality of light sources 1 were arranged in the laser scan unit of Fig. 2, the laser scan unit of Fig. 2 comprised that the laser scan unit with Fig. 1 has a pair of laser scan unit of identical construction.

Yet when by aforesaid when making described mirror 4 move forward and backward the inclination of correct scan line, laser beam may be moved the twice of the motion of mirror 4.Therefore, be not easy to, for example regulate the position of mirror or the inclination that reflection angle comes the correct scan line by such method.Therefore, the position of mirror or reflection angle are regulated the rectilinearity (linearity) of the laser beam that may cause passing f-θ lens 3, the changes such as diameter of laser beam, thereby make deterioration of image quality.

On the contrary, disclose for Japanese patent publication 2005-265904 and 2004-070108 number and used time scanning inclination to go into the tandem scanning optics of shooting method, this system is using catoptron to come separating light beam from the light path of polygonal rotating mirror laser light reflected bundle when reducing the thickness of polygonal rotating mirror, incides polygonal rotating mirror and will have predetermined angular from the described laser beam of rotating multisurface mirror reflection.In the tandem scanning optics, the bending of the sweep trace that is produced is symmetrical up and down based on the light path of inferior direction of scanning, and irrelevant with the quantity or the layout of imaging optical system.Usually the lens by being formed into image optical system according to asymmetrical shape or aspherical shape, some lens of making imaging optical system are arranged eccentrically or are rotated or make the catoptron that is arranged in the imaging optical system rear portion be out of shape the bending of proofreading and correct such sweep trace.

Can make the scanning curvature of a curve to the light path design of laser beam is 0, but the bending of sweep trace may be caused by rigging error in the product manufacturing or part tolerance.Therefore, need by the aforesaid other equipment or the bending of method correct scan line.

Yet, based on the light path of the maximum laser beam of the bending of sweep trace, the bending of other sweep trace on the light path of a plurality of other laser beam of correction.Therefore, be not easy to proofread and correct the bending of the sweep trace that forms by a plurality of other laser beam according to the different directions projection.

Summary of the invention

General plotting of the present invention provides a kind of imaging device of constructing the laser scan unit that has improved and having this laser scan unit, this laser scan unit is used for the inclination of correct scan line, and do not worsen other performance, rectilinearity of the diameter of the laser beam of imaging, laser beam etc. on photoconductor for example.

General plotting of the present invention also provides a kind of imaging device of constructing the laser scan unit that has improved and having this laser scan unit, and this laser scan unit is used to proofread and correct the bending of tiltedly inciding the sweep trace that a plurality of laser beam on the polygonal rotating mirror cause.

To be partly articulated other aspect of general plotting of the present invention and purposes in the following description, by describing, a part can become obviously, perhaps can understand by implementing general plotting of the present invention.

By providing a kind of laser scan unit that is used for the inclination of correct scan line can realize the above-mentioned and/or others and the purposes of general plotting of the present invention, this laser scan unit comprises: light source; Polygonal rotating mirror makes the laser-beam deflection of sending from light source; F-θ lens make the laser beam imaging on photoconductor from polygonal rotating mirror deflection; Flat board becomes predetermined angle theta to arrange obliquely with main scanning direction between f-θ lens and photoconductor, is used for the inclination of correct scan line.

Flat board can be with respect to scanning of a surface predetermined oblique angle θ _⊥, and can form by the transparent material with predetermined thickness t, predetermined refraction n.

When needed time representation of line of scanning is s on photoconductor, the mathematical formulae below dull and stereotyped predetermined angle theta satisfies:

By providing a kind of laser scan unit also can realize the above-mentioned and/or others and the purposes of general plotting of the present invention, this laser scan unit comprises: at least two light sources; Polygonal rotating mirror makes the laser beam of sending from described light source respectively towards at least two photoconductor deflections; At least two f-θ lens are arranged between described light source and the described photoconductor, are used to make the laser beam imaging on described photoconductor respectively from polygonal rotating mirror deflection; At least two flat boards are arranged with respect to main scanning direction predetermined oblique angle θ between described f-θ lens and described photoconductor, are used for the inclination of correct scan line respectively.

Flat board can be with respect to scanning of a surface predetermined oblique angle θ _⊥, and can be that t, predetermined refraction are that the transparent material of n forms by thickness.

By providing a kind of laser scan unit can realize the above-mentioned and/or others and the purposes of general plotting of the present invention, this laser scan unit comprises: light source; Polygonal rotating mirror makes the laser-beam deflection of sending from light source; F-θ lens make the laser beam imaging on photoconductor from polygonal rotating mirror deflection.F-θ lens can be arranged to relative main scanning direction and produce, with the inclination of correct scan line.

By above-mentioned and/or others and the purposes that provides a kind of imaging device also can realize general plotting of the present invention, this imaging device comprises photoconductor and the aforesaid laser scan unit that is used for forming electrostatic latent image on photoconductor.

Also can realize the above-mentioned and/or others and the purposes of general plotting of the present invention by the laser scan unit that a kind of bending that can the correct scan line is provided, this laser scan unit comprises: a plurality of light sources; Polygonal rotating mirror makes from the laser-beam deflection of described light source incline incident; F-θ lens make the laser beam imaging on photoconductor from polygonal rotating mirror deflection; Flat board is arranged between polygonal rotating mirror and the f-θ lens, is used for the bending of correct scan line.

Flat board can be with respect to scanning of a surface predetermined oblique angle θ ', and can be formed by the transparent material with predetermined thickness t, predetermined refraction n.

Dull and stereotyped predetermined angle theta ' satisfied following mathematical formulae:

$|0.8\·L\·\left(\frac{1}{\cos {\mathrm{\θ}}_s}\right)\·\tan {\mathrm{\θ}}^{\′}|\≤\left|\frac{t\·\cos {\mathrm{\θ}}^{\′}\·\sin {\mathrm{\θ}}^{\′}}{\sqrt{n^2-\sin {\mathrm{\θ}}^{\′}}\·\cos \left({\sin }^{-1}\frac{\sin {\mathrm{\θ}}_d}{n}\right)}\right|\≤|1.2\·L\·(\frac{1}{\cos {\mathrm{\θ}}_s}-1)\·\tan {\mathrm{\θ}}^{\′}|$

Wherein, be expressed as L and θ respectively from polygonal rotating mirror to dull and stereotyped distance with the image angle of passing dull and stereotyped both sides _s

By providing a kind of imaging device also can realize the above-mentioned and/or others and the purposes of general plotting of the present invention, this imaging device comprises photoconductor, a plurality of light sources and the aforesaid laser scan unit that is used for forming electrostatic latent image on photoconductor.

By providing a kind of laser scan unit also can realize the above-mentioned and/or others and the purposes of general plotting of the present invention, this laser scan unit comprises: light source, emission of lasering beam; Photoconductor, laser beam incident are to photoconductor, to form electrostatic latent image; Flat board is arranged between light source and the photoconductor according to predetermined angular, with the sweep trace of the distortion of calibration light source.

This laser scan unit also can comprise: polygonal rotating mirror makes the laser-beam deflection of sending from light source; F-θ lens make the laser beam imaging on photoconductor from polygonal rotating mirror deflection.

Dull and stereotyped can have preset thickness t and predetermined refractive index n, to produce the optical path difference of laser beam.

Optical path difference can produce the sweep trace of distortion.

The scalable flat board is with respect to the angle of scanning of a surface, to proofread and correct the sweep trace of distorting.

Also can realize the above-mentioned and/or others and the purposes of general plotting of the present invention by the method for scanning lines that a kind of laser beams is provided, the method of scanning lines of this laser beams may further comprise the steps: the emitted laser bundle is by dull and stereotyped, to incide on the photoconductor; Regulate dull and stereotyped angle with respect to scanning of a surface.

Dull and stereotyped angle can satisfy following mathematical formulae:

$|0.8\·L\·\left(\frac{1}{\text{cos}{\mathrm{\θ}}_{\text{s}}}\right)\·\text{tan}{\mathrm{\θ}}^{\′}|\≤\left|\frac{t\·\cos {\mathrm{\θ}}^{\′}\·\sin {\mathrm{\θ}}^{\′}}{\sqrt{n^2-\sin {\mathrm{\θ}}^{\′}}\·\cos \left({\sin }^{-1}\frac{\sin {\mathrm{\θ}}_d}{n}\right)}\right|\≤|1.2\·L\·(\frac{1}{\cos {\mathrm{\θ}}_s}-1)\·\text{tan}{\mathrm{\θ}}^{\′}|\mathrm{}$

Wherein, the size of dull and stereotyped angle, image angle with respect to scanning of a surface, from polygonal rotating mirror to dull and stereotyped distance, dull and stereotyped predetermined refraction and the image angle of passing dull and stereotyped both sides be expressed as θ ', θ respectively _d, L, n and θ _s

Dull and stereotyped angle can satisfy following mathematical formulae:

Wherein, dull and stereotyped angle with respect to scanning of a surface, first angle that forms with respect to beam axis with respect to the predetermined angular of main scanning direction, dull and stereotyped predetermined thickness, dull and stereotyped predetermined refraction, by the first of laser beam and be expressed as θ respectively with respect to second angle that beam axis forms by the second portion of laser beam _⊥, θ, t, n, θ ₁And θ ₂

Description of drawings

By the description of embodiment being carried out below in conjunction with accompanying drawing, these of general plotting of the present invention and/or others and purposes will become clear and be easier to and understand, wherein:

Fig. 1 is schematically illustrated view with traditional laser scan unit of two light sources;

Fig. 2 is the view of another traditional laser scan unit of schematically illustrated device with the inclination that is used for the correct scan line;

Fig. 3 be schematically illustrated according to the present invention the view of the laser scan unit of the flat board with the inclination that is used for the correct scan line of general plotting exemplary embodiment;

Fig. 4 is the vertical view of method of layout angle that the flat board of estimation Fig. 3 is shown;

Fig. 5 is the side view of the flat board of Fig. 3;

Fig. 6 be schematically illustrated according to the present invention the view of the laser scan unit of the flat board with the bending that is used for the correct scan line of another exemplary embodiment of general plotting;

Fig. 7 is the vertical view of method of layout angle that the flat board of estimation Fig. 6 is shown;

Fig. 8 illustrates the view that dull and stereotyped and f-θ lens are arranged such that the state that a plurality of laser beam are not interfering with each other;

Fig. 9 is the side view of the flat board of Fig. 6;

Figure 10 is the schematically illustrated view of the imaging device of the laser scan unit of the above-mentioned exemplary embodiment of general plotting of having used according to the present invention.

Embodiment

Now the embodiment to general plotting of the present invention is described in detail, its example shown in the accompanying drawings, wherein, identical label is represented similar elements all the time.Below with reference to the accompanying drawings embodiment is described to explain general plotting of the present invention.

Fig. 3 be schematically illustrated according to the present invention the view of the laser scan unit 100 of general plotting exemplary embodiment.The laser scan unit 100 of general plotting exemplary embodiment comprises light source 110, polygonal rotating mirror 120, f-θ lens 130 and dull and stereotyped 200 according to the present invention.

Because light source 110, polygonal rotating mirror 120 and the structure of f-θ lens 130 and the traditional components that function is general plotting of the present invention, so, for clarity and conciseness for the purpose of, with the detailed description of omitting them.

Dull and stereotyped 200 are arranged between f-θ lens 130 and the photoconductor 150 inclination that is used to proofread and correct the sweep trace of the laser beam of imaging on photoconductor 150.As shown in Figure 4, dull and stereotyped 200 tiltedly arrange according to predetermined angle theta with respect to main scanning direction.

Below, explain the aforesaid tiltedly evaluation method of the predetermined angle theta of the flat board 200 of layout with reference to Fig. 4.

Structure imaging equipment in such a manner: according to the printing speed of imaging device, can determine the speed of rotation of polygonal rotating mirror 120, and, can determine the linear velocity of photoconductor 150 according to the speed of rotation of polygonal rotating mirror 120.Because polygonal rotating mirror 120 can rotate along the direction of scanning, and photoconductor 150 can be along the vertical direction rotation corresponding with the direction of scanning, so the laser beam of imaging can produce inclining scanning line on the surface of photoconductor 150.By between f-θ lens 130 and photoconductor 150 according to become predetermined angle theta tiltedly to arrange the inclination of the sweep trace that dull and stereotyped 200 recoverables are such with main scanning direction.The axle of the light beam that the beam axis L ' indication shown in Fig. 4 is vertical with main scanning direction.

As mentioned above, if flat board 200 arranges that tiltedly then laser beam can produce optical path difference by the angle θ according to dull and stereotyped 200 when passing flat board 200.Multiply each other by the thickness that makes refractive index and the medium that will be passed and to calculate light path.Therefore, the thickness t of refractive index n and flat board 200 produces the light path of the laser beam of passing dull and stereotyped 200 centers, and reaches n * t, passes the laser beam L1 ' at dull and stereotyped 200 two ends and the light path of L2 ' and reaches n * t respectively ₁And n * t ₂Because optical path difference shows as the inclination at the lip-deep sweep trace of photoconductor, so, if regulate dull and stereotyped 200 angle θ, the then inclination of recoverable sweep trace.

In addition, in order to prevent at the laser beam of imaging on photoconductor secondary reflection and form ghost image (ghost image) on the surface of photoconductor 150 again, as shown in Figure 5, dull and stereotyped 200 with respect to scanning of a surface S predetermined oblique angle θ _⊥State arrangement.The angle that is incident on the laser beam on dull and stereotyped 200 is θ _{0 ⊥}

Therefore, the mathematical formulae 1 below dull and stereotyped 200 angle (θ) satisfies, wherein, s is the needed time of line of scanning on photoconductor.

[mathematical formulae 1]

Can use top mathematical formulae 1 to calculate dull and stereotyped 200 angle (θ).For example, if the linear velocity of photoconductor 150 is 70mm/s, the time s that scanning a line needs is 43 μ s, incident angle θ _{0 ⊥}Be 0 °, dull and stereotyped 200 degree of tilt θ _⊥Be 10 °, dull and stereotyped 200 thickness t is 2mm, θ ₁And θ ₂Be 30 °, the inclination size of the sweep trace that the rotation by the linear velocity of photoconductor 150 and polygonal rotating mirror 120 that is then produced causes is about 30 μ m.

Therefore, when mathematical formulae 1 calculating above using is used to proofread and correct size that the linear velocity by photoconductor 150 causes and is about the angle (θ) of flat board 200 of inclination of sweep trace of 30 μ m, determine that its value is 0.6 °.Therefore, if flat board 200 tilts 0.6 °, then by top mathematical formulae 1, compare with original state, the inclination of the sweep trace that calculates is the value that has reduced about 30 μ m sizes, thus the inclination of having proofreaied and correct sweep trace.

Above content also can be applicable to use more than two light sources and single polygonal rotating mirror so that the laser scan unit of laser beam imaging on more than two photoconductors, described in the description of Fig. 1.With reference to Fig. 3, dull and stereotyped 200 also can tiltedly be arranged between photoconductor and the f-θ lens, thereby form optical path difference, with the inclination of correct scan line.Because the structure of dull and stereotyped 200 structure and layout and the top laser scan unit of describing with reference to Fig. 2 100 and arrange identically, it is clear and for simplicity that institute thinks, with the detailed description of omission to them.

In addition, though it is not shown, but replace tiltedly being arranged between f-θ lens 130 and the photoconductor 150 as independent parts with dull and stereotyped 200, also f-θ lens 130 itself or collimation lens (not shown) or cylindrical lens (not shown) tiltedly can be arranged, with flat board 200 inclination of correct scan line similarly of aforesaid laser scan unit.

As mentioned above, when each parts that the laser beam of sending from light source 110 is passed any one tiltedly arranged according to predetermined angular with respect to main scanning direction, the inclination that all can proofread and correct the sweep trace of the laser beam of imaging on photoconductor 150.

Fig. 6 be schematically illustrated according to the present invention another exemplary embodiment of general plotting laser scan unit 100 ' view.The laser scan unit 100 of another exemplary embodiment of general plotting according to the present invention ' comprise light source 110, polygonal rotating mirror 120, f-θ lens 130 and dull and stereotyped 200 '.

Because the structure and the function of light source 110, polygonal rotating mirror 120 and f-θ lens 130 are known parts, so, for clarity and conciseness for the purpose of, with the detailed description of omitting them.

Flat board 200 ' be arranged between polygonal rotating mirror 120 and the f-θ lens 130 bending that is used to proofread and correct the sweep trace of the laser beam of imaging on photoconductor 150.As shown in Figure 9, dull and stereotyped 200 ' with respect to direction of scanning predetermined oblique angle (θ ').

Below, with reference to Fig. 7 to Fig. 9 explain the flat board 200 that tilts as mentioned above ' the evaluation method of predetermined angular (θ ').

Structure imaging equipment in such a manner: according to the printing speed of imaging device, can determine the speed of rotation of polygonal rotating mirror 120, and, can determine the linear velocity of photoconductor 150 according to the speed of rotation of polygonal rotating mirror 120.If be provided with a plurality of light sources, as shown in Figure 8, then imaging device can be constructed such that the laser beam of sending from each light source is incident on the polygonal rotating mirror 120 according to predetermined angular and from polygonal rotating mirror 120 reflections, incides then on a plurality of photoconductor (not shown), and do not interfere with each other.

When the angle that incides the laser beam on the polygonal rotating mirror 120 obliquely, image angle and from polygonal rotating mirror 120 to dull and stereotyped 200 ' distance be expressed as θ ' respectively _⊥(see figure 9), θ _d(+direction is θ ' ₁,-direction is θ ' ₂) and during L, centrifugal (decenter) amount that is produced is $\left(\frac{L}{\cos {\mathrm{\θ}}_d}\right)\·{\mathrm{\θ}}_{\⊥}^{\′}.$

Centrifugal is the variation of the center of the optical axis of laser beam incident on it focus when moving.If image angle θ _dSize change, then the displacement of laser beam changes, thus centrifugal size changes.As a result, different at the height of incidence of dull and stereotyped both sides laser beam with the height of incidence of the laser beam at dull and stereotyped center.Simultaneously, the height of incidence difference of the laser beam between dull and stereotyped center and dull and stereotyped both sides is corresponding with the length of the bending of sweep trace.

When the laser beam of the sweep trace with aforesaid bending is passed 200 ' time of flat board of predetermined oblique angle, by because the bending of the sweep trace of the optical path difference laser beams of the flat board 200 ' generation of predetermined oblique angle, and laser beam incident is on the optical system that comprises f-θ lens 130.Can obtain the size of centrifugal amount by anglec of rotation θ ', refractive index n and the dull and stereotyped thickness t of following mathematical formulae 2 flat boards on the xz plane.

[mathematical formulae 2]

Therefore, if be set as identical value by the length of the bending of inciding the sweep trace that laser beam produced on the polygonal rotating mirror 120 obliquely, and direction with dull and stereotyped 200 ' vergence direction opposite, then the bending of sweep trace can be corrected.

As image angle θ by dull and stereotyped 200 ' center _cVery near 0, and the image angle of passing dull and stereotyped 200 ' both sides is θ _sThe time, tilt quantity, that is, and the anglec of rotation or tilt angle theta ' and dull and stereotyped 200 ' the mathematical formulae 3 of thickness t below satisfying.

[mathematical formulae 3]

$|0.8\·L\·\left(\frac{1}{\cos {\mathrm{\θ}}_s}\right)\·\tan {\mathrm{\θ}}^{\′}|\≤\left|\frac{t\·\cos {\mathrm{\θ}}^{\′}\·\sin {\mathrm{\θ}}^{\′}}{\sqrt{n^2-\sin {\mathrm{\θ}}^{\′}}\·\cos \left({\sin }^{-1}\frac{\sin {\mathrm{\θ}}_d}{n}\right)}\right|\≤|1.2\·L\·(\frac{1}{\cos {\mathrm{\θ}}_s}-1)\·\tan {\mathrm{\θ}}^{\′}|$

Aforesaid structure can be applicable to employed tandem laser scan unit in the imaging device described in the background technology, for example, according to four kinds of colors, use different laser scan units to form the color laser printer of coloured image as cyan, magenta, yellow and black.

As shown in figure 10, using as mentioned above, the imaging device of the laser scan unit of structure comprises: medium feeding unit 10; Developing cell 20 has photoconductor 150; Laser scan unit 100 is used for forming electrostatic latent image on photoconductor 150; Fixation unit 30 and media discharge unit 40.

Because medium feeding unit 10, developing cell 20, fixation unit 30 and media discharge unit 40 are traditional assemblies, so for clarity and conciseness, with the detailed description of omitting them.

It is dull and stereotyped 200 that laser scan unit 100 is provided with, and is used to proofread and correct the aforesaid inclination of the sweep trace of the laser beam of imaging on photoconductor 150.

With reference to Fig. 3, use the size that to estimate the inclination of sweep trace according to the speed of printing definite polygonal rotating mirror 120 of speed and photoconductor 150.Therefore, if the inclination of the sweep trace of compensation estimation then can tiltedly be arranged between f-θ lens 130 and the photoconductor 150, with the inclination of correct scan line according to the predetermined angle theta of being calculated by top mathematical formulae 1 by the flat board 200 that transparent material forms.

Another kind of mode is, the imaging device of Figure 10 can comprise being provided with of Fig. 6 dull and stereotyped 200 ' laser scan unit 100 ', to proofread and correct the aforesaid bending of the sweep trace of the laser beam of imaging on photoconductor 150.

That is to say, can estimate the length of the bending of sweep trace by the degree of tilt that incides the laser beam on the polygonal rotating mirror 120.Therefore, if the flat board 200 that will form by transparent material ' according to the predetermined angle theta of calculating by top mathematical formulae 3 ' tiltedly be arranged between polygonal rotating mirror 120 and the f-θ lens 130, with the amount of the bending that produces the sweep trace opposite with the amount of the bending of the sweep trace of estimating, bending that then can the correct scan line.

Be clear that from top description, the exemplary embodiment of general plotting according to the present invention, the inclination and/or the bending of the sweep trace that laser scan unit and imaging device recoverable with this laser scan unit are caused by the rotation of polygonal rotating mirror and photoconductor and other work and assembling process, to minimize mis-behave, the rectilinearity variation of for example diameter of laser beam change, laser beam etc., thus product quality is improved.

Though represented and described some embodiment of general plotting of the present invention, but those skilled in the art should understand that, under the situation of principle that does not break away from general plotting of the present invention and spirit, can change these embodiment, the scope of general plotting of the present invention is limited by claim and equivalent thereof.

Claims (30)

1. laser scan unit comprises:

Light source;

Polygonal rotating mirror makes the laser-beam deflection of sending from light source;

F-θ lens make the laser beam imaging on photoconductor from polygonal rotating mirror deflection;

Flat board is arranged between light source and the photoconductor, is used for the sweep trace of calibration light source.

2. laser scan unit as claimed in claim 1, wherein, dull and stereotyped between f-θ lens and photoconductor with respect to main scanning direction predetermined oblique angle θ, with the inclination of correct scan line.

3. laser scan unit as claimed in claim 2, wherein, dull and stereotyped with respect to scanning of a surface predetermined oblique angle θ _⊥

4. laser scan unit as claimed in claim 3, wherein, flat board is formed by the transparent material with predetermined thickness t, predetermined refraction n.

5. laser scan unit as claimed in claim 4, wherein, the mathematical formulae below dull and stereotyped predetermined angle theta satisfies:

Wherein, scanning needed time of line, first angle that forms with respect to beam axis by the first of laser beam and be expressed as s, θ respectively with respect to second angle that beam axis forms on photoconductor by the second portion of laser beam ₁And θ ₂

6. laser scan unit as claimed in claim 1, wherein, tablet arrangement is between polygonal rotating mirror and f-θ lens, with the bending of correct scan line.

7. laser scan unit as claimed in claim 6, wherein, dull and stereotyped with respect to scanning of a surface predetermined oblique angle θ '.

8. laser scan unit as claimed in claim 7, wherein, flat board is formed by the transparent material with predetermined thickness t, predetermined refraction n.

9. laser scan unit as claimed in claim 7, wherein, dull and stereotyped predetermined angle theta ' satisfied following mathematical formulae:

$|0.8\·L\·\left(\frac{1}{\cos {\mathrm{\θ}}_s}\right)\·\tan {\mathrm{\θ}}^{\′}|\≤\left|\frac{t\·{\cos \mathrm{\θ}}^{\′}\·{\sin \mathrm{\θ}}^{\′}}{\sqrt{n^2-{\sin \mathrm{\θ}}^{\′}}\·\cos \left({\sin }^{-1}\frac{{\sin \mathrm{\θ}}_d}{n}\right)}\right|\≤|1.2\·L\·(\frac{1}{{\cos \mathrm{\θ}}_s}-1)\·{\tan \mathrm{\θ}}^{\′}|$

Wherein, the size of image angle, from polygonal rotating mirror to dull and stereotyped distance and the image angle of passing dull and stereotyped both sides be expressed as θ respectively _d, L and θ _s

10. laser scan unit comprises:

At least two light sources;

Polygonal rotating mirror makes the laser beam of sending from described light source respectively towards at least two photoconductor deflections;

At least two f-θ lens are arranged between described light source and the described photoconductor, are used to make the laser beam imaging on described photoconductor respectively from polygonal rotating mirror deflection;

At least two flat boards are arranged according to predetermined angle theta obliquely with respect to main scanning direction between described f-θ lens and described photoconductor, are used for the inclination of correct scan line respectively.

11. laser scan unit as claimed in claim 10 is wherein, dull and stereotyped with respect to scanning of a surface predetermined oblique angle θ _⊥

12. laser scan unit as claimed in claim 11, wherein, flat board is formed by the transparent material with predetermined thickness t, predetermined refraction n.

13. laser scan unit as claimed in claim 12, wherein, the mathematical formulae below each dull and stereotyped predetermined angle theta satisfies:

Wherein, scanning needed time of line, first angle that forms with respect to beam axis by the first of laser beam and be expressed as s, θ respectively with respect to second angle that beam axis forms on described photoconductor by the second portion of laser beam ₁And θ ₂

14. a laser scan unit comprises:

Light source;

Polygonal rotating mirror makes the laser-beam deflection of sending from light source;

The f-lens make the laser beam imaging on photoconductor from polygonal rotating mirror deflection,

Wherein, f-θ lens are arranged to relative main scanning direction and produce, with the inclination of correct scan line.

15. an imaging device comprises:

Photoconductor;

Light source;

Polygonal rotating mirror makes the laser-beam deflection of sending from light source;

F-θ lens make the laser beam imaging on photoconductor from polygonal rotating mirror deflection;

Flat board between f-θ lens and photoconductor, with respect to main scanning direction predetermined oblique angle θ, is used for the inclination of correct scan line.

16. imaging device as claimed in claim 15, wherein, dull and stereotyped with respect to scanning of a surface according to predetermined angle theta _⊥Arrange.

17. imaging device as claimed in claim 16, wherein, flat board is formed by the transparent material with predetermined thickness t, predetermined refraction n.

18. imaging device as claimed in claim 17, wherein, the mathematical formulae below dull and stereotyped predetermined angle theta satisfies:

Wherein, scanning needed time of line, first angle that forms with respect to beam axis by the first of laser beam and be expressed as s, θ respectively with respect to second angle that beam axis forms on photoconductor by the second portion of laser beam ₁And θ ₂

19. an imaging device comprises:

Photoconductor;

A plurality of light sources;

Polygonal rotating mirror makes from the laser-beam deflection of described light source incline incident;

F-θ lens make the laser beam imaging on photoconductor from polygonal rotating mirror deflection;

Flat board is arranged between polygonal rotating mirror and the f-θ lens, is used for the bending of correct scan line.

20. imaging device as claimed in claim 19 is wherein, dull and stereotyped with respect to scanning of a surface predetermined oblique angle θ '.

21. imaging device as claimed in claim 20, wherein, flat board is formed by the transparent material with predetermined thickness t, predetermined refraction n.

22. imaging device as claimed in claim 21, wherein, dull and stereotyped predetermined angle theta ' satisfied following mathematical formulae:

$|0.8\·L\·\left(\frac{1}{\cos {\mathrm{\θ}}_s}\right)\·\tan {\mathrm{\θ}}^{\′}|\≤\left|\frac{t\·{\cos \mathrm{\θ}}^{\′}\·{\sin \mathrm{\θ}}^{\′}}{\sqrt{n^2-{\sin \mathrm{\θ}}^{\′}}\·\cos \left({\sin }^{-1}\frac{{\sin \mathrm{\θ}}_d}{n}\right)}\right|\≤|1.2\·L\·(\frac{1}{{\cos \mathrm{\θ}}_s}-1)\·{\tan \mathrm{\θ}}^{\′}|$

Wherein, the size of image angle, from polygonal rotating mirror to dull and stereotyped distance and the image angle of passing dull and stereotyped both sides be expressed as θ respectively _d, L and θ _s

23. a laser scan unit comprises:

Light source, emission of lasering beam;

Photoconductor, laser beam incident are to photoconductor, to form electrostatic latent image;

Flat board is arranged between light source and the photoconductor according to predetermined angular, is used for the sweep trace of the distortion of calibration light source.

24. laser scan unit as claimed in claim 23 also comprises:

Polygonal rotating mirror makes the laser-beam deflection of sending from light source;

F-θ lens make the laser beam imaging on photoconductor from polygonal rotating mirror deflection.

25. laser scan unit as claimed in claim 23, wherein, flat board has preset thickness t and predetermined refractive index n, to produce the optical path difference of laser beam.

26. laser scan unit as claimed in claim 25, wherein, optical path difference produces the sweep trace of distorting.

27. laser scan unit as claimed in claim 26 wherein, is regulated dull and stereotyped angle with respect to scanning of a surface, to proofread and correct the sweep trace of distorting.

28. the method for scanning lines of a laser beams, this method may further comprise the steps:

The emitted laser bundle is by dull and stereotyped, to incide on the photoconductor;

Regulate dull and stereotyped angle with respect to scanning of a surface.

29. method as claimed in claim 28, wherein, the mathematical formulae below dull and stereotyped described angle satisfies:

$|0.8\·L\·\left(\frac{1}{\cos {\mathrm{\θ}}_s}\right)\·\tan {\mathrm{\θ}}^{\′}|\≤\left|\frac{t\·{\cos \mathrm{\θ}}^{\′}\·{\sin \mathrm{\θ}}^{\′}}{\sqrt{n^2-{\sin \mathrm{\θ}}^{\′}}\·\cos \left({\sin }^{-1}\frac{{\sin \mathrm{\θ}}_d}{n}\right)}\right|\≤|1.2\·L\·(\frac{1}{{\cos \mathrm{\θ}}_s}-1)\·{\tan \mathrm{\θ}}^{\′}|$

Wherein, the size of dull and stereotyped angle, image angle with respect to scanning of a surface, from polygonal rotating mirror to dull and stereotyped distance, dull and stereotyped predetermined refraction and the image angle of passing dull and stereotyped both sides be expressed as θ ', θ respectively _d, L, n and θ _s

30. method as claimed in claim 28, wherein, the mathematical formulae below dull and stereotyped described angle satisfies:

Wherein, dull and stereotyped angle with respect to scanning of a surface, first angle that forms with respect to beam axis with respect to the predetermined angular of main scanning direction, dull and stereotyped predetermined thickness, dull and stereotyped predetermined refraction, by the first of laser beam and be expressed as θ respectively with respect to second angle that beam axis forms by the second portion of laser beam _⊥, θ, t, n, θ ₁And θ ₂

Images