WO2020238565A1 - 光学扫描单元及电子照相成像装置 - Google Patents

光学扫描单元及电子照相成像装置 Download PDF

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Publication number
WO2020238565A1
WO2020238565A1 PCT/CN2020/088756 CN2020088756W WO2020238565A1 WO 2020238565 A1 WO2020238565 A1 WO 2020238565A1 CN 2020088756 W CN2020088756 W CN 2020088756W WO 2020238565 A1 WO2020238565 A1 WO 2020238565A1
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Prior art keywords
unit
optical
optical unit
scanning
light source
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PCT/CN2020/088756
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English (en)
French (fr)
Inventor
李荣华
王超
王东宁
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珠海奔图电子有限公司
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Priority to EP20814228.1A priority Critical patent/EP3968078B1/en
Publication of WO2020238565A1 publication Critical patent/WO2020238565A1/zh
Priority to US17/526,900 priority patent/US11841498B2/en

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    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/435—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material
    • B41J2/44—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using single radiation source per colour, e.g. lighting beams or shutter arrangements
    • B41J2/442—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using single radiation source per colour, e.g. lighting beams or shutter arrangements using lasers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/435—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material
    • B41J2/47—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using the combination of scanning and modulation of light
    • B41J2/471—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using the combination of scanning and modulation of light using dot sequential main scanning by means of a light deflector, e.g. a rotating polygonal mirror
    • 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
    • G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
    • 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
    • G02B26/124—Details of the optical system between the light source and the polygonal mirror
    • 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
    • G02B26/125—Details of the optical system between the polygonal mirror and the image plane
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
    • G02B27/4205—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant
    • G02B27/4227—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant in image scanning systems
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
    • G02B27/4233—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive element [DOE] contributing to a non-imaging application
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
    • G02B27/4283—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive element with major temperature dependent properties
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/04—Apparatus for electrographic processes using a charge pattern for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material
    • G03G15/0409—Details of projection optics
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/04—Apparatus for electrographic processes using a charge pattern for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material
    • G03G15/043—Apparatus for electrographic processes using a charge pattern for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material with means for controlling illumination or exposure
    • G03G15/0435—Apparatus for electrographic processes using a charge pattern for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material with means for controlling illumination or exposure by introducing an optical element in the optical path, e.g. a filter

Definitions

  • the present invention relates to the field of laser printing technology, in particular to an optical scanning unit and an electrophotographic imaging device.
  • the current electrophotographic imaging device includes an optical scanning unit, which scans the light modulated by image information to the surface of the photoreceptor, and uses a deflection guide device to deflect and scan the light along the main scanning direction.
  • the light emitted by the light source is focused on the surface of the photoreceptor through a collimating lens, a cylindrical lens, and an F- ⁇ lens (flat field focusing lens).
  • the material of the collimating lens is usually plastic.
  • plastic due to the relatively large expansion coefficient of plastic, it is easy to cause the refractive index of the collimating lens to increase according to the internal temperature of the optical scanning unit in operation.
  • the temperature changes, which in turn causes the light emitted by the light source to focus on the surface of the photoreceptor to change the focal point.
  • the wavelength of the light emitted by the light source becomes longer, which also causes the position of the focal point of the light beam focused on the surface of the photoreceptor to change.
  • the focus position where the light emitted by the light source is focused on the surface of the photoreceptor changes, the light will be incorrectly focused on the photoreceptor, which will affect the final printing effect and reduce the quality of the printed image.
  • the purpose of the present invention is to provide an optical scanning unit and an electrophotographic imaging device, which can compensate the focal movement of the beam caused by the change in refractive index and wavelength caused by the temperature change of the optical scanning unit, thereby improving the quality of the printed image.
  • an optical scanning unit including a light source for diverging light beams; an optical deflector for deflecting light beams emitted by the light source; arranged between the light source and the optical deflector
  • the first optical unit, the first optical unit includes a refraction unit and a diffractive unit; a second optical unit arranged in the light exit direction of the optical deflector, used to make the light beam deflected by the optical deflector on the scanning target surface Imaging; wherein the range of the ratio of the refractive power ⁇ r to the diffractive power ⁇ d of the first optical unit in the main scanning direction is 0.3 ⁇ r / ⁇ d ⁇ 0.5; The range of the ratio of the refractive power ⁇ s to the diffractive power ⁇ n in the scanning direction is 0.7 ⁇ s / ⁇ n ⁇ 1.0.
  • the ratio of the refractive power in the main scanning direction of the first optical unit to the diffractive power ( ⁇ r / ⁇ d )m and the refractive power in the sub-scanning direction of the first optical unit is: 0.3 ⁇ ( ⁇ r / ⁇ d )m/( ⁇ s / ⁇ n )s ⁇ 0.5.
  • the change in the wavelength of the light source caused by the temperature change is d ⁇ /d T , where d ⁇ /d T ⁇ 0.25.
  • the first optical unit includes an anamorphic lens, or includes an independent collimating lens and a cylindrical lens.
  • the first optical unit is made of plastic material, and the refraction unit and the diffraction unit are integrally molded on the incident light side surface and the exit light side surface of the anamorphic lens by injection molding.
  • an aperture stop is provided between the light source and the first optical unit; or an aperture stop is provided between the first optical unit and the optical deflector.
  • an electrophotographic imaging device including the optical scanning unit described in any one of the above, and further including a photosensitive unit that forms a latent image on the scanning target surface, and the A developing unit that develops the latent image on the photosensitive unit into a toner image, a transfer device that transfers the toner image to a transfer medium, and a fixing that fixes the toner image on the transfer medium Device.
  • the optical scanning unit and the electrophotographic imaging device include a light source, an optical deflector, a first optical unit, and a second optical unit.
  • the first optical unit is arranged between the light source and the optical deflector, and the first optical unit includes a diffraction unit and a refraction unit.
  • the light emitted by the light source is refracted and diffracted by the refraction unit and the diffraction unit, respectively, so that the focal length of the light emitted by the first optical unit is relatively stable, and the influence of temperature changes is relatively small.
  • a second optical unit is also arranged in the light exit direction of the optical deflector, and the second optical unit focuses the light beam deflected by the optical deflector so that the light beam is imaged on the scanning target surface.
  • the refractive power of the first optical unit in the main scanning direction is ⁇ r
  • the diffractive power is ⁇ d
  • the ratio of ⁇ r to ⁇ d ranges from 0.3 to 0.5
  • the first optical unit is in the sub-scanning direction
  • the refractive power of the above is ⁇ s
  • the diffractive power is ⁇ n
  • the ratio of ⁇ s to ⁇ n ranges from 0.7 to 1.0; when the ratio of ⁇ r to ⁇ d , the ratio of ⁇ s to ⁇ n are respectively
  • the position change of the focal point of the optical scanning unit finally focused on the scanning target surface is less affected by temperature, thereby improving the imaging quality of the optical scanning unit on the scanning target surface.
  • Figure 1 is a schematic structural diagram of an electrophotographic imaging device provided by an embodiment of the present invention.
  • FIG. 2 is a schematic diagram of the optical path in the main scanning direction of the optical scanning unit according to an embodiment of the present invention
  • FIG. 3 is a schematic diagram of the optical path in the secondary scanning direction of the optical scanning unit provided by the embodiment of the present invention.
  • FIG. 4 is a schematic structural diagram of an optical scanning unit provided by an embodiment of the present invention.
  • FIG. 5 is a schematic diagram of a light beam passing through a first optical unit provided by an embodiment of the present invention.
  • FIG. 6 is a graph showing the relationship between focus change in the main scanning direction and ⁇ r / ⁇ d according to an embodiment of the present invention
  • FIG. 7 is a graph of the relationship between focus change in the main scanning direction and temperature according to an embodiment of the present invention.
  • FIG. 8 is a graph showing the relationship between focus change in the sub-scanning direction and ⁇ s / ⁇ n according to an embodiment of the present invention
  • FIG. 9 is a graph of the relationship between focus change in the sub-scanning direction and temperature according to an embodiment of the present invention.
  • the terms “center”, “upper”, “horizontal”, “inner”, etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or are customary when the product of the invention is used.
  • the placement or positional relationship is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a reference to the present invention. limits.
  • An optical scanning unit 100 provided by an embodiment of the present invention includes: a light source 10 for diverging light beams; an optical deflector 20 for deflecting light beams emitted by the light source 10; and a second light source disposed between the light source 10 and the optical deflector 20
  • An optical unit 30, the first optical unit 30 includes a refraction unit 31 and a diffractive unit 32; a second optical unit 40 arranged in the direction of the light exit of the optical deflector 20 is used to focus the light beam deflected by the optical deflector 20 on the scanning target surface Imaging.
  • the range of the ratio of the refractive power ⁇ r to the diffractive power ⁇ d of the first optical unit 30 in the main scanning direction is:
  • the range of the ratio of the refractive power ⁇ s to the diffractive power ⁇ n of the first optical unit 30 in the sub-scanning direction is:
  • the sub-scanning direction is the rotation direction of the scanning target surface, and the main scanning direction and the sub-scanning direction are perpendicular to each other.
  • the light source 10 diverges the light beam, and the light beam is collimated by the first optical unit 30 and then directed to the optical deflector 20.
  • the optical deflector 20 causes the light beam to be deflected and scanned in the main scanning direction.
  • the beam deflected by 20 passes through the second optical unit 40 and then is focused on the scanning target surface.
  • the optical deflector 20 usually includes a polygon mirror and a driving device.
  • the driving device is in a transmission connection with the polygon mirror.
  • the light beam emitted by the light source 10 passes through the first optical unit 30 and is directed to the polygon mirror of the optical deflector 20.
  • the rotating polygon mirror deflects the light beam to the second optical unit 40.
  • the polygon mirror rotates along its rotation axis under the driving of the driving device, so that the light beam reflected by the polygon mirror can be deflected and incident on the second optical unit 40 at different angles. So as to realize the beam scanning along the main scanning direction.
  • the specific form of the light source 10 is not limited.
  • the light source 10 is an LD (laser diode, laser) light source to emit a laser beam with a relatively small divergence angle.
  • the light source 10 can also be set as an LED (Light Emitting Diode, light emitting diode) light source or the like.
  • the light source 10 for diverging light beams can diverge the light beam at a certain exit angle.
  • the second optical unit 40 is set to Plan focusing lens (f-theta lens).
  • the light beam emitted by the light source 10 passes through the first optical unit 30, it passes through the refraction unit 31 and the diffractive unit 32 on the first optical unit 30 and then exits.
  • the optical power of the refraction unit 31 and the diffractive unit 32 will both change with changes in temperature.
  • the optical power of the refraction unit 31 changes according to the change in temperature, so the optical path of the light that has passed through the refraction unit 31 may be distorted.
  • the wavelength of the light emitted from the light source 10 also changes.
  • the optical path of the light that has passed through the refraction unit 31 changes.
  • the optical power of the diffraction unit 32 changes according to the change in the wavelength of the light, but the refraction unit 31 in contrast with the trend of the optical power of the temperature change of the optical power of the diffraction unit 32 with a change in temperature causes a change in wavelength, so when the refractive power of 30 ⁇ r and the diffraction power in the main scanning direction of the first optical unit
  • the range of the ratio of the degree ⁇ d is 0.3 ⁇ r / ⁇ d ⁇ 0.5
  • the range of the ratio of the refractive power ⁇ s to the diffractive power ⁇ n of the first optical unit 30 in the sub-scanning direction is 0.7 ⁇ s / ⁇
  • the optical power of the refraction unit 31 and the optical power of the diffractive unit 32 can better offset the changes in optical power caused by temperature changes, thereby reducing the focus and collimation effect of the temperature on the first optical unit 30 Impact.
  • An optical scanning unit 100 provided by an embodiment of the present invention includes a light source 10, an optical deflector 20, a first optical unit 30, and a second optical unit 40.
  • the first optical unit 30 is disposed between the light source 10 and the optical deflector 20, and the first optical unit 30 includes a refraction unit 31 and a diffraction unit 32.
  • the refraction unit 31 and the diffraction unit 32 respectively compensate for the light emitted by the light source 10 due to the change in refractive index and wavelength caused by the temperature change, which causes the focus of the light to move, thereby making the focal length of the light emitted by the first optical unit 30 relatively stable. It is relatively less affected by temperature changes.
  • a second optical unit 40 is also provided in the light exit direction of the optical deflector 20, and the second optical unit 40 focuses the light beam deflected by the optical deflector 20 so that the light beam is imaged on the scanning target surface.
  • the refractive power of the first optical unit 30 in the main scanning direction is ⁇ r
  • the diffractive power is ⁇ d
  • the ratio of ⁇ r to ⁇ d ranges from 0.3 to 0.5
  • the first optical unit 30 is in the auxiliary
  • the refractive power in the scanning direction is ⁇ s
  • the diffractive power is ⁇ n
  • the ratio of ⁇ s to ⁇ n ranges from 0.7 to 1.0.
  • the optical scanning unit 100 When the ratio of ⁇ r to ⁇ d , the ratio of ⁇ s to ⁇ n When the ratios are respectively set in the above ranges, the optical scanning unit 100 finally makes the light beam emitted by the light source 10 focus on the scanning target surface and the focus position change is less affected by temperature, thereby improving the optical scanning unit 100 on the scanning target surface. Image quality.
  • the ratio range of the refractive power ⁇ r to the diffractive power ⁇ d of the first optical unit 30 in the main scanning direction and the refractive power ⁇ s and the diffractive power of the first optical unit 30 in the sub-scanning direction.
  • the ratio range of degree ⁇ n Experimental tests show that the refractive power of the refraction unit 31 and the refractive power of the diffractive unit 32 satisfy the following relational expression, which can better compensate for changes in the focal position caused by changes in temperature.
  • the ratio of the refractive power and the diffracted power ( ⁇ r / ⁇ d ) m in the main scanning direction of the first optical unit 30 and the refractive power and diffracted light in the sub scanning direction of the first optical unit 30 The ratio range of the power ratio ( ⁇ s / ⁇ n )s is:
  • the change in the wavelength of the light source due to the change in temperature is d ⁇ /d T , where,
  • ⁇ represents the wavelength
  • d ⁇ represents the wavelength change
  • T represents the temperature
  • d T represents the temperature change
  • the first optical unit 30 includes an anamorphic lens, or includes an independent collimator lens and a cylindrical lens.
  • the first optical unit 30 includes a single anamorphic lens, and the first optical unit 30 performs the functions of both a collimating lens and a cylindrical lens.
  • the main optical axis of the first optical unit 30 is arranged corresponding to the light source 10 so that the divergent light beam from the light source 10 passes through the first optical unit 30, and the first optical unit 30 collimates the light emitted by the light source 10.
  • the first optical unit 30 can be used as a whole, which reduces assembly errors, facilitates processing, and has a small amount of deformation affected by temperature.
  • the first optical unit 30 can also be used in combination with a collimator lens and a cylindrical lens. At the same time, it can compensate the focus movement of the light beam affected by temperature, which is beneficial to improve the printing quality.
  • the first optical unit 30 is made of plastic material, and the refraction unit 31 and the diffraction unit 32 are integrally molded on the surface of the incident light side and the exit light side of the anamorphic lens by injection molding.
  • the diffraction surface of the diffraction unit 32 may be sawtooth-shaped or step-shaped, preferably step-shaped, and the diffraction unit 32 may be represented by the phase polynomial of Expression 5.
  • ⁇ represents the phase of the diffraction element 32 in the diffraction zone where the diffraction element 32 is formed, that is, the phase of the diffraction element 32 in a region at a distance r from the center of the diffraction surface of the diffraction element 32
  • m represents the diffraction
  • ⁇ represents the wavelength of the light beam emitted by the light source 10
  • C 1 , C 2 , C 3 , and C 4 represent the relative coefficients.
  • the first optical unit 30 can be made of plastic material, and can be manufactured by direct injection molding or die-casting, which is beneficial to reducing the production cost of the first optical unit 30.
  • the refraction unit 31 and the diffraction unit 32 are respectively arranged on both sides of the first optical unit 30.
  • the structure of the refraction unit 31 and the diffraction unit 32 can be directly formed on both sides of the first optical unit 30, thereby facilitating reduction
  • the volume of the entire optical scanning unit 100 reduces assembly steps, reduces production costs, and improves production efficiency.
  • the refraction unit 31 and the diffraction unit 32 can also compensate for the deviation of the focus position caused by the temperature change, which is beneficial to improve the printing quality.
  • the optical scanning unit 100 further includes a supporting unit 50 for supporting the first optical unit 30, wherein the focal length of the first optical unit 30 is f 1 , the focal length of the second optical unit 40 is f 2 ,
  • the thermal expansion coefficient of an optical unit 30 is K 1
  • the wavelength of the light emitted from the light source 10 is 790.2 nm.
  • the thermal expansion coefficient K 1 of the first optical unit 30 is 0.000055, the thermal expansion coefficient K 2 of the supporting unit 50 is 0.000035, the focal length of the first optical unit 30 in the main scanning direction is 20 mm, and the focal length of the first optical unit 30 in the sub-scanning direction
  • the focal length of the second optical unit 40 in the main scanning direction is 197.575 mm, and the focal length of the second optical unit 40 in the sub-scanning direction is 24.611 mm.
  • the distance between the light source 10 and the first optical unit 30 is L 1
  • the distance between the first optical unit 30 and the optical deflector 20 is L 2
  • the distance between the units 40 is L 3
  • the distance between the second optical unit 40 and the photosensitive unit 210 is L 4 .
  • the refraction unit 31 in the main scanning direction can satisfy the above-mentioned relational expression (6).
  • the process of substituting various values of the sub-scanning unit of the refraction unit 31 can be referred to the substituting process of the sub-scanning unit of the refraction unit 31, the result of which can be verified by those skilled in the art, and the description is not repeated here.
  • the focal length f 1 of the first optical unit 30 is set to be 7.88 mm, 14.238 mm, 20 mm, 28.98 mm, 35.22 mm, 42.32 mm, respectively.
  • Table 3 includes the ratio of the refractive power to the diffracted power of the optical scanning unit 100 in the main scanning direction ⁇ r / ⁇ d and the focal position The relationship between changes.
  • the focal length f 1 of the first optical unit 30 designed in the main scanning direction of the optical scanning unit 100 is 20 mm.
  • the smaller the focal length the greater the change in the focus position, and the greater the compensation required to obtain satisfactory imaging quality.
  • it is necessary to set a larger focal length which will increase the volume of the imaging device. Therefore, in order to reduce the cost and volume, without affecting the print quality, comprehensively considering the manufacturing cost, the design will shorten the focal length of the first optical unit 30 and the second optical unit 40 as much as possible, so as to reduce the optical scanning unit 100 and the volume of the electrophotographic imaging device.
  • the position of the focal point changes accordingly.
  • the wavelength of the light emitted by the light source 10 is 790.2 nm
  • the thermal expansion coefficient of the first optical lens is 0.000055
  • the support frame The coefficient of thermal expansion is 0.000035
  • the focal length f 1 of the first optical unit 30 is 20 mm.
  • the relationship between the change in the focus position in the main scanning direction and the temperature and focal length can be drawn as shown in Figure 7. It can be seen from FIG. 7 that as the temperature changes, the relationship 0.3 ⁇ r / ⁇ d ⁇ 0.5(1) is satisfied, and when the focal length f 1 of the first optical unit 30 designed in the main scanning direction is 20 mm , When (1-(f 1 /f 2 )) ⁇ 0.18 ⁇ f 1 ⁇ r ⁇ K 2 /K 1 ⁇ (1+(f 1 /f 2 )) ⁇ 0.25, the change in focus position is small It can be seen that the variation of the focal length of the first optical unit 30 can be well compensated.
  • the focal length f 1 of the first optical unit 30 is set to be 7.88 mm, 14.238 mm, 20 mm, 28.98 mm, 35.22 mm, 42.32 mm, respectively.
  • Table 5 The relationship between the ratio of the refractive power and the diffractive power of the optical scanning unit 100 in the sub-scanning direction ⁇ s / ⁇ n and the focal position is shown in Table 5.
  • the focal length f 1 of the first optical unit 30 designed in the sub-scanning direction of the optical scanning unit 100 is 14.238 mm.
  • the smaller the focal length the greater the change in the focus position, and the greater the compensation required to obtain satisfactory imaging quality.
  • it is necessary to set a larger focal length which will increase the volume of the imaging device. Therefore, in order to reduce the cost and volume, without affecting the print quality, comprehensively considering the manufacturing cost, the design will shorten the focal length of the first optical unit 30 and the second optical unit 40 as much as possible, so as to reduce the optical scanning unit 100 and the volume of the electrophotographic imaging device.
  • the position of the focal point changes accordingly.
  • the change of the focus position in the sub-scanning direction is based on the temperature change inside the optical scanning unit 100.
  • the relationship between the measured focus position change and ⁇ r / ⁇ d can be seen in Table 6 for details.
  • the relationship between the change in the focus position in the sub-scanning direction and the temperature and focal length can be drawn as shown in Figure 9. It can be seen from Fig. 9 that as the temperature changes, the relationship 0.7 ⁇ s / ⁇ n ⁇ 1 is satisfied, and when the focal length f 1 of the first optical unit 30 in the sub-scanning direction is 14.238mm, it satisfies (1 -(f 1 /f 2 )) ⁇ 0.18 ⁇ f 1 ⁇ r ⁇ K 2 /K 1 ⁇ (1+(f 1 /f 2 )) ⁇ 0.25, the change in focus position is small, and the first The focal length change of the optical unit 30 can be well compensated.
  • the focal lengths of the first optical unit 30 and the second optical unit 40 need to be shortened as much as possible to achieve the purpose of reducing the volume of the optical scanning unit 100 and the electrophotographic imaging device 200.
  • the focal length f 1 of the first optical unit 30 is preferably set to be 20mm in the main scanning direction and 14.238mm in the sub-scanning direction.
  • the change in temperature of the first optical unit 30 can be well compensated for the change in the focal length of the first optical unit 30, which can improve the quality of the printed image, and can realize the miniaturization of the optical scanning unit 100.
  • the ratio of the refractive power ⁇ r of the first optical unit 30 in the main scanning direction to the diffractive power ⁇ d satisfies the inequality 0.35 ⁇ r / ⁇ d ⁇ 0.45
  • the ratio of the refractive power ⁇ s to the diffractive power ⁇ n of the first optical unit 30 in the sub-scanning direction satisfies the inequality 0.98 ⁇ s / ⁇ n ⁇ 1.
  • the ratio of the refractive power ⁇ r to the diffractive power ⁇ d of the first optical unit 30 in the main scanning direction, and the corresponding first optical power The ratio of the refractive power ⁇ s to the diffractive power ⁇ n of the unit 30 in the sub-scanning direction, and the ratio of the refractive power to the diffractive power in the main scanning direction of the first optical unit 30 ( ⁇ r / ⁇ d )
  • the ratio of m to the ratio of the refractive power and the diffractive power ( ⁇ s / ⁇ n ) s in the sub-scanning direction of the first optical unit 30 For specific design example values, see Table 7.
  • an aperture stop 33 is provided between the first optical unit 30 and the light source 10, or, as shown in FIG. 3, an aperture stop 33 is provided between the first optical unit 30 and the deflection device 20 Aperture stop 33.
  • each component can be fixedly installed on the support unit 50, so that the aperture stop 33 can be a hole structure machined in the direction of the light path corresponding to the support unit 50, and the aperture stop 33 can block the edge light so as to The light beam emitted by the light source 10 is formed into a predetermined spot shape through the aperture stop 33.
  • the aperture stop 33 can be set as a circular aperture stop, an elliptical aperture stop, or a square aperture stop. Special restrictions are made, and those skilled in the art can make appropriate adjustments according to actual conditions.
  • the aperture stop 33 may be provided between the first optical unit 30 and the light source 10 to constrain the light beam emitted by the light source 10, or, as shown in FIG.
  • An aperture stop 33 is provided between an optical unit 30 and the deflection device 20.
  • the light beam that will enter the deflection device 20 after being modulated by the first optical unit 30 can also be constrained.
  • the light beam emitted by the light source 10 may not be restricted. To be restricted, that is, the aperture stop 33 may also be omitted.
  • an electrophotographic imaging device 200 which includes the above-mentioned optical scanning unit 100, and further includes a photosensitive unit 210 that forms a latent image on the surface of the scanning target, and develops the latent image on the photosensitive drum into The toner image developing unit 220, the transfer device 230 that transfers the toner image to the transfer medium, and the fixing device 240 that fixes the toner image on the transfer medium.
  • the light scanning unit emits a light beam to scan onto the photosensitive unit 210, which is an example of a photoreceptor.
  • the photosensitive unit 210 includes a cylindrical metal tube with an outer circumference, and a photosensitive layer with a predetermined thickness is formed on the outer circumference.
  • the charging roller 250 rotates and contacts the photosensitive unit 210, and charges the surface of the photosensitive unit 210 to a uniform potential.
  • the light scanning unit scans the light beam modulated according to the image information in the main scanning direction, thereby forming an electrostatic latent image on the imaging surface of the photosensitive unit 210.
  • the photosensitive unit 210 rotates, the imaging surface moves in the sub-scanning direction, and the light scanning unit synchronizes with the horizontal synchronization signal to scan the light beam onto the imaging surface in the main scanning direction. Therefore, the two-dimensional electrostatic The latent image is formed on the imaging surface of the surface of the photosensitive unit 210.
  • the developing unit 220 contacts the photosensitive unit 210 and transfers the toner medium to the surface of the photosensitive unit 210, thereby forming a printed image.
  • the transfer roller has a certain deflection voltage, so that the medium image on the surface of the photosensitive unit 210 is more easily adsorbed onto the recording medium 270, and the remaining medium on the surface of the photosensitive unit 210 will be removed by the cleaning unit 260 after the transfer.
  • the toner medium image transferred to the recording medium 270 is fixed to the recording medium 270 by heating and pressing by the fixing unit, thereby completing the printing operation.
  • optical scanning unit 100 includes the same structure and beneficial effects as the optical scanning unit 100 in the foregoing embodiment.
  • the structure and beneficial effects of the optical scanning unit 100 have been described in detail in the foregoing embodiments, and will not be repeated here.

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Abstract

本发明提供一种光学扫描单元及电子照相成像装置，涉及激光打印技术领域，能够补偿光学扫描单元由于温度的变化引起折射率和波长的变化导致光束的焦点运动，进而提升打印图像的质量。包括：光源，用于发散光束。光学偏转器，用于偏转光源出射的光束。设置在光源与光学偏转器之间的第一光学单元，第一光学单元包括折射单元和衍射单元。设置在光学偏转器出光方向的第二光学单元，用于使光学偏转器偏转的光束在扫描目标表面上成像。其中，第一光学单元在主扫描方向的折射光焦度Φ r与衍射光焦度Φ d的比值范围为0.3＜Φ r/Φ d＜0.5。第一光学单元在副扫描方向的折射光焦度Φ s与衍射光焦度Φ n的比值范围为0.7＜Φ s/Φ n＜1.0。

Description

光学扫描单元及电子照相成像装置
本申请要求于2019年05月30日提交中国专利局、申请号为201910468141.9、申请名称为“光学扫描单元及电子照相成像装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及激光打印技术领域，具体而言，涉及一种光学扫描单元及电子照相成像装置。
背景技术
目前电子照相成像装置包括有光学扫描单元，光学扫描单元将图像信息调制成的光扫描到感光体表面，并使用偏转导向装置使光沿着主扫描方向偏转扫描。光源发射出来的光通过准直透镜、柱面透镜、F-θ透镜(平场聚焦透镜)，聚焦到感光体的表面。
为了能够降低光学扫描单元的成本，通常准直透镜的材料为塑料，但是由于塑料的膨胀系数相对较大，容易造成当工作中的光学扫描单元内部温度升高之后，准直透镜的折射率根据温度的变化而变化，进而会导致光源发射出的光聚焦到感光体的表面的焦点的位置发生变化。并且，光源由于温度上升，光源发射的光的波长变长，也会导致聚焦到感光体表面的光束焦点的位置发生变化。光源发射的光聚焦到感光体表面的焦点的位置发生变化，则光会不正确地聚焦到感光体上，对最终的打印效果会造成影响，降低打印图像的质量。
发明内容
本发明的目的在于提供一种光学扫描单元及电子照相成像装置，能够补偿光学扫描单元由于温度的变化引起折射率和波长的变化导致光束的焦点运动，进而提升打印图像的质量。
本发明的实施例是这样实现的：
本发明实施例的一方面，提供一种光学扫描单元，包括光源，用于发散光束；光学偏转器，用于偏转所述光源出射的光束；设置在所述光源与所述光学偏转器之间的第一光学单元，所述第一光学单元包括折射单元和衍射单元；设置在所述光学偏转器出光方向的第二光学单元，用于使所述光学偏转器偏转的光束在扫描目标表面上成像；其中，所述第一光学单元在主扫描方向的折射光焦度Φ r与衍射光焦度Φ d的比值范围为0.3＜Φ r/Φ d＜0.5；所述第一光学单元在副扫描方向的折射光焦度Φ s与衍射光焦度Φ n的比值范围为0.7＜Φ s/Φ n＜1.0。
可选地，所述第一光学单元的主扫描方向的折射光焦度与衍射光焦度之比(Φ r/Φ d)m与所述第一光学单元的副扫描方向的折射光焦度与衍射光焦度之比(Φ s/Φ n)s的比值范围为：0.3＜(Φ r/Φ d)m/(Φ s/Φ n)s＜0.5。
可选地，由于温度变化而引起光源的波长的变化为d λ/d T，其中，d λ/d T＜0.25。
可选地，所述第一光学单元包括变形透镜，或者包括独立的准直透镜和圆柱透镜。
可选地，所述第一光学单元为塑胶材质，所述折射单元以及所述衍射单元通过注塑一体成型于所述变形透镜的入射光侧表面和出射光侧表面。
可选地，在所述光源与所述第一光学单元之间设置有孔径光阑；或者，在所述第一光学单元与所述光学偏转器之间设置有孔径光阑。
可选地，0.35＜Φ r/Φ d＜0.45，0.98＜Φ s/Φ n＜1。
可选地，0.35＜(Φ r/Φ d)m/(Φ s/Φ n)s＜0.45。
本发明实施例的另一个方面，提供一种电子照相成像装置，包括如上所述任一项所述的光学扫描单元，还包括在所述扫描目标表面上形成潜像的感光单元，将所述感光单元上的所述潜像显影为碳粉图像的显影单元，将所述碳粉图像转印到转印介质上的转印装置，以及将所述转印介质上的碳粉图像定影的定影装置。
本发明实施例的有益效果包括：
本发明实施例提供的光学扫描单元及电子照相成像装置，包括光源、光学偏转器、第一光学单元以及第二光学单元。其中，第一光学单元设置在光源和光学偏转器之间，且第一光学单元包括有衍射单元和折射单元。通过折 射单元和衍射单元分别对光源发射出的光进行折射和衍射，从而使由第一光学单元出射的光的焦距相对稳定，受到温度变化的影响相对较小。在光学偏转器的出光方向还设置有第二光学单元，通过第二光学单元对经过光学偏转器偏转后的光束聚焦使光束在扫描目标表面上成像。上述第一光学单元在主扫描方向上的折射光焦度为Φ r、衍射光焦度为Φ d，Φ r与Φ d的比值范围为0.3到0.5之间；第一光学单元在副扫描方向上的折射光焦度为Φ s、衍射光焦度为Φ n，Φ s与Φ n的比值范围为0.7到1.0之间；当Φ r与Φ d的比值、Φ s与Φ n的比值分别设置在上述范围时，该光学扫描单元最终聚焦在扫描目标表面的焦点的位置变化受到温度影响较小，从而提高该光学扫描单元在扫描目标表面上的成像质量。
附图说明
为了更清楚地说明本发明实施例的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，应当理解，以下附图仅示出了本发明的某些实施例，因此不应被看作是对范围的限定，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他相关的附图。
图1为本发明实施例提供的电子照相成像装置结构示意图；
图2为本发明实施例提供的光学扫描单元主扫描方向的光路示意图；
图3为本发明实施例提供的光学扫描单元副扫描方向的光路示意图；
图4为本发明实施例提供的光学扫描单元的结构示意图；
图5为本发明实施例提供的光束通过第一光学单元的示意图；
图6为本发明实施例提供的主扫描方向焦点变化与Φ r/Φ d的关系曲线图；
图7为本发明实施例提供的主扫描方向焦点变化与温度的关系曲线图；
图8为本发明实施例提供的副扫描方向焦点变化与Φ s/Φ n的关系曲线图；
图9为本发明实施例提供的副扫描方向焦点变化与温度的关系曲线图。
附图标记：
100-光学扫描单元；10-光源；20-光学偏转器；30-第一光学单元；31-折射单元；32-衍射单元；33-孔径光阑；40-第二光学单元；50-支撑单元； 200-电子照相成像装置；210-感光单元；220-显影单元；230-转印装置；240-定影装置；250-充电辊；260-清洁单元；270-记录介质。
具体实施方式
为使本发明实施例的目的、技术方案和优点更加清楚，下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本发明一部分实施例，而不是全部的实施例。通常在此处附图中描述和示出的本发明实施例的组件可以以各种不同的配置来布置和设计。
因此，以下对在附图中提供的本发明的实施例的详细描述并非旨在限制要求保护的本发明的范围，而是仅仅表示本发明的选定实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
在本发明的描述中，术语“中心”、“上”、“水平”、“内”等指示的方位或位置关系为基于附图所示的方位或位置关系，或者是该发明产品使用时惯常摆放的方位或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。
本发明实施例提供的一种光学扫描单元100，包括：光源10，用于发散光束；光学偏转器20，用于偏转光源10出射的光束；设置在光源10与光学偏转器20之间的第一光学单元30，第一光学单元30包括折射单元31和衍射单元32；设置在光学偏转器20出光方向的第二光学单元40，用于使光学偏转器20偏转的光束聚焦在扫描目标表面上成像。
第一光学单元30在主扫描方向的折射光焦度Φ r与衍射光焦度Φ d的比值范围为：
0.3＜Φ r/Φ d＜0.5    (1)
第一光学单元30在副扫描方向的折射光焦度Φ s与衍射光焦度Φ n的比值范围为：
0.7＜Φ s/Φ n＜1.0    (2)
其中，副扫描方向为扫描目标表面的旋转运动方向，主扫描方向与副扫 描方向相互垂直。
该光学扫描单元100正常工作时，光源10发散光束，光束经过第一光学单元30准直之后射向光学偏转器20，通过光学偏转器20使光束沿主扫描方向进行偏转扫描，由光学偏转器20偏转出射的光束透过第二光学单元40后聚焦至扫描目标表面上。
需要说明的是，第一，通常光学偏转器20包括多面镜和驱动装置，驱动装置与多面镜传动连接，光源10发射的光束经过第一光学单元30之后射向光学偏转器20的多面镜，旋转的多面镜将光束偏转至第二光学单元40，多面镜在驱动装置的驱动下沿其旋转轴旋转，使经过多面镜反射的光束发生偏转能够以不同的角度入射至第二光学单元40，从而实现光束沿主扫描方向扫描。
第二，在本发明实施例中，对于光源10的具体形式不做限定。示例地，光源10为LD(laser diode，激光)光源，以发射出发散角相对较小的激光光束。当然，在某种状态下，光源10还可以设置为LED(Light Emitting Diode，发光二极管)光源等。用于发散光束的光源10能够以一定的出射角度发散出射光束即可。
第三，通常为了使经过光学偏转器20偏转的光束以不同角度入射至第二光学单元40后聚焦的出射光的焦点均能相对稳定的位于扫描目标的表面上，第二光学单元40设置为平场聚焦透镜(f-θ透镜)。
第四，通常由光源10发射的光束经过第一光学单元30时，依次通过第一光学单元30上的折射单元31和衍射单元32后出射。折射单元31和衍射单元32的光焦度随着温度的变化均会发生变化，折射单元31的光焦度根据温度的改变而变化，从而已经通过折射单元31的光的光路可能发生扭曲，当环境温度变化时，从光源10发射的光的波长也会发生变化，已经通过折射单元31的光的光路变化，衍射单元32的光焦度会根据光的波长的变化而变化，但是折射单元31的光焦度随温度的变化与衍射单元32的光焦度随温度的变化引起波长的变化的趋势相反，因此当第一光学单元30在主扫描方向的折射光焦度Φ r与衍射光焦度Φ d的比值范围为0.3＜Φ r/Φ d＜0.5，第一光学单元30在副扫描方向的折射光焦度Φ s与衍射光焦度Φ n的比值范围为0.7＜Φ s/Φ n＜1.0时，折射单元31的光焦度和衍射单元32的光焦度能够较好的相互抵消由 于温度变化造成的光焦度变化，从而减小温度对第一光学单元30聚焦准直效果的影响。
本发明实施例提供的一种光学扫描单元100，包括光源10、光学偏转器20、第一光学单元30以及第二光学单元40。其中，第一光学单元30设置在光源10和光学偏转器20之间，且第一光学单元30包括有折射单元31和衍射单元32。通过折射单元31和衍射单元32分别对光源10发射出的光补偿由于温度的变化引起折射率和波长的变化导致光的焦点运动，从而使由第一光学单元30出射的光的焦距相对稳定，受到温度变化的影响相对较小。在光学偏转器20的出光方向还设置有第二光学单元40，通过第二光学单元40对经过光学偏转器20偏转后的光束聚焦使光束在扫描目标表面上成像。上述第一光学单元30在主扫描方向上的折射光焦度为Φ r、衍射光焦度为Φ d，Φ r与Φ d的比值范围为0.3到0.5之间，第一光学单元30在副扫描方向上的折射光焦度为Φ s、衍射光焦度为Φ n，Φ s与Φ n的比值范围为0.7到1.0之间，当Φ r与Φ d的比值、Φ s与Φ n的比值分别设置在上述范围时，该光学扫描单元100最终使得光源10发出的光束聚焦在扫描目标表面上的焦点的位置变化受到温度影响较小，从而提高该光学扫描单元100在扫描目标表面上的成像质量。
针对上述第一光学单元30在主扫描方向的折射光焦度Φ r与衍射光焦度Φ d的比值范围，以及第一光学单元30在副扫描方向的折射光焦度Φ s与衍射光焦度Φ n的比值范围。通过实验测试表明，折射单元31的光焦度与衍射单元32的光焦度满足如下关系式，能够更好的补偿由于温度的变化引起的焦点位置的变化。即第一光学单元30的主扫描方向的折射光焦度与衍射光焦度之比(Φ r/Φ d)m与所述第一光学单元30的副扫描方向的折射光焦度与衍射光焦度之比(Φ s/Φ n)s的比值范围为：
0.3＜(Φ r/Φ d)m/(Φ s/Φ n)s＜0.5    (3)
满足(3)式，由于温度的变化，可获得更好的打印补偿效果。
此外，由于温度的变化而引起光源的波长的变化为d λ/d T，其中，
d λ/d T＜0.25    (4)
需要说明的是，λ表示波长，d λ表示波长变化量，T表示温度，d T表示温度变化量。
具体的，光源的波长与温度的关系见表1：
表1
温度(℃) 波长(nm)
25 788
35 790.2
45 792.4
55 794.6
60 795.7
由上述公式(4)可知，温度的变化会导致光源的波长随之发生变化。
例如，如表1所示：温度在25℃时，波长λ为788nm；温度在60℃时，波长λ为795.7nm。将温度为25℃以及60℃所对应的波长λ值代入公式(4)，计算差值可知，d λ/d T＝7.7/35＝0.22，满足公式(4)，即可得证在上述表1中所示的温度变化范围内，本发明实施例的光学扫描单元可易于获得较好的打印补偿效果。
可选地，如图2所示，第一光学单元30包括变形透镜，或者包括独立的准直透镜和圆柱透镜。
具体的，第一光学单元30包括单个变形透镜，第一光学单元30执行准直透镜和圆柱透镜二者的功能。第一光学单元30的主光轴与光源10对应设置，以使光源10发散的光束通过第一光学单元30，第一光学单元30对光源10发射的光进行准直。第一光学单元30可作为一个整体使用，减小装配误差，且方便加工，受温度影响的形变量较小。而在常规的光学扫描单元中，第一光学单元30也可以采用准直透镜和圆柱透镜结合使用。同时，可以补偿受温度影响的光束的焦点运动，有利于提升打印品质。
可选地，第一光学单元30为塑胶材质，折射单元31以及衍射单元32通过注塑一体成型于变形透镜的入射光侧和出射光侧的表面。
另外，衍射单元32的衍射表面可以是锯齿状或者是阶梯状，优选阶梯状，衍射单元32可以由表达式5的相多项式表示：
ψ(r)＝2π/mλ(C 1r 2+C 2r 4+C 3r 6+C 4r 8)    (5)
其中，ψ表示在形成有衍射单元32的衍射区中衍射单元32的相(phase)， 即，在距离衍射单元32的衍射表面的中心距离r的区域中的衍射单元32的相，m表示衍射级(diffraction order)，λ表示光源10发射的光束的波长，及C 1、C 2、C 3、和C 4表示相多项系数。
具体的，第一光学单元30可采用塑胶材质，可以通过直接注塑成型或者压铸成型的方式制作，有利于降低第一光学单元30的生产成本。折射单元31和衍射单元32分别设置在第一光学单元30的两侧，示例的，可以将折射单元31和衍射单元32的结构直接形成于第一光学单元30的两侧，从而有利于减小整个光学扫描单元100的体积，减少装配步骤，降低生产成本，提升生产效率。同时，折射单元31和衍射单元32还能够补偿由于温度变化引起的焦点位置偏差，有利于提升打印质量。
在本实施例中，光学扫描单元100还包括用于支撑第一光学单元30的支撑单元50，其中，第一光学单元30的焦距为f 1，第二光学单元40的焦距为f 2，第一光学单元30的热膨胀系数为K 1，支撑单元50的热膨胀系数为K 2，K 1＝0.000055，K 2＝0.000035。
当第一光学单元30的焦距、第二光学单元40的焦距、第一光学单元30的热膨胀系数以及支撑单元50的热膨胀系数满足如下关系式(6)时，可获得质量满意的打印补偿效果：
(1-(f 1/f 2))×0.18<f 1×Φ r×K 2/K 1<(1+(f 1/f 2))×0.25    (6)
作为本发明的一个实施例，从光源10发射出来的光的波长为790.2nm。其中第一光学单元30的热膨胀系数K 1为0.000055，支撑单元50的热膨胀系数K 2为0.000035，第一光学单元30的主扫描方向的焦距为20mm，第一光学单元30的副扫描方向的焦距为14.238mm，第二光学单元40的主扫描方向的焦距197.575mm，第二光学单元40的副扫描方向的焦距为24.611mm。
请参考表2和图2，光源10与第一光学单元30之间的距离为L 1，第一光学单元30与光学偏转器20之间的距离为L 2，光学偏转器20与第二光学单元40之间的距离为L 3，第二光学单元40与感光单元210之间的距离为L 4。
表2
Figure PCTCN2020088756-appb-000001
Figure PCTCN2020088756-appb-000002
在表2的上述示例中，第一光学单元30的焦距、第二光学单元40的焦距、第一光学单元30的热膨胀系数以及支撑单元50的热膨胀系数，在主扫描方向折射单元31上，代入各个相应的数值，则可以得出以下结果：
(1-(f 1/f 2))×0.18＝0.1617791<f 1×Φ r×K 2/K 1＝0.183272727<(1+(f 1/f 2))×0.25＝0.2753068
可见，在主扫描方向上的折射单元31是可以满足上述关系式(6)的。在这里，折射单元31的副扫描单元的各个数值的代入过程可参见折射单元31的副扫描单元的代入过程，其结果本领域技术人员可自行验证，在此不再重复说明。
在表达式(5)的方程中，假设r＝x 2+y 2，光轴和第一光学单元30之间的交点是原点时，x和y分别是主扫描方向X和副扫描方向Y的坐标值，如果C2至C4都等于0，则衍射单元32的光焦度Φ d可表达为Φ d＝-2×C1。
作为本发明的一个实施例，光源10辐射光的波长为790.2nm时，设定第一光学单元30的焦距f 1数值分别为7.88mm、14.238mm、20mm、28.98mm、35.22mm、42.32mm。当温度发生变化时，可得出表3所示关系值，表3包括 了光学扫描单元100在主扫描方向上的折射光焦度与衍射光焦度之比Φ r/Φ d与焦点的位置变化之间的关系。
表3
Figure PCTCN2020088756-appb-000003
从表3可以得出，第一光学单元30在主扫描方向的折射光焦度Φ r与衍射光焦度Φ d的比值满足关系式：0.3<Φ r/Φ d<0.5，第一光学单元30的焦距f 1数值分别为14.238mm、20mm、28.98mm、35.22mm时，满足关系式(1-(f 1/f 2))×0.18<f 1×Φ r×K 2/K 1<(1+(f 1/f 2))×0.25。依据表3所示的示例值，如图6所示，可以绘制出主扫描方向上焦点的变化与Φ r/Φ d的关系曲线图。
优选地，在光学扫描单元100的主扫描方向中设计的第一光学单元30的焦距f 1为20mm。在实际光学扫描单元100的设计中，焦距越小，焦点位置变化越大，则需要越大的补偿才能够获得满意的成像质量。反之，要使得焦点位置变化较小，就需要设置较大的焦距，这样则会增加成像装置的体积。因此，为了降低成本，缩小体积，在不影响打印质量的前提下，综合考虑制造成本，会尽可能的设计缩短第一光学单元30和第二光学单元40的焦距，以达到减小光学扫描单元100和电子照相成像装置的体积。
作为本发明的一个实施例，在打印机工作温度内，当温度变化时，焦点的位置相应发生变化，光源10发射出来的光的波长为790.2nm，第一光学透镜的热膨胀系数0.000055，支撑框架的热膨胀系数为0.000035，第一光学单 元30的焦距f 1为20mm。温度变化时，在主扫描方向上焦点的位置变化是基于光学扫描单元100内部的温度变化而变化，其测量焦点位置变化与Φ r/Φ d的关系可详细参见表4所示。
表4
Figure PCTCN2020088756-appb-000004
依据表4所示的设计示例值，可以绘制出主扫描方向焦点位置的变化与温度以及焦距之间的关系曲线图如图7所示。从图7可以看出，随着温度变化，在满足关系式0.3<Φ r/Φ d<0.5(1)，同时当设计的第一光学单元30在主扫描方向上的焦距f 1为20mm时，满足(1-(f 1/f 2))×0.18<f 1×Φ r×K 2/K 1<(1+(f 1/f 2))×0.25的情况下，焦点位置的变化小，可见第一光学单元30的焦距变动能够得到很好的补偿。
作为本发明的一个实施例，光源10辐射光的波长为790.2nm时，设定第一光学单元30的焦距f 1数值分别为7.88mm、14.238mm、20mm、28.98mm、35.22mm、42.32mm。光学扫描单元100上在副扫描方向上的折射光焦度与衍射光焦度之比Φ s/Φ n与焦点位置关系参见表5所示。
表5
Figure PCTCN2020088756-appb-000005
Figure PCTCN2020088756-appb-000006
从表5可以看出，Φ s/Φ n满足关系式0.7<Φ s/Φ n<1，第一光学单元30的焦距f 1数值分别为14.238mm、20mm时，满足关系式(1-(f 1/f 2))×0.18<f 1×Φ s×K 2/K 1<(1+(f 1/f 2))×0.25。其中，副扫描方向焦点变化与Φ s/Φ n的关系曲线图可具体参见图8所示。
优选地，在光学扫描单元100副扫描方向中设计的第一光学单元30的焦距f 1为14.238mm。在实际光学扫描单元100的设计中，焦距越小，焦点位置变化越大，则需要越大的补偿才能够获得满意的成像质量。反之，要使得焦点位置变化较小，就需要设置较大的焦距，这样则会增加成像装置的体积。因此，为了降低成本，缩小体积，在不影响打印质量的前提下，综合考虑制造成本，会尽可能的设计缩短第一光学单元30和第二光学单元40的焦距，以达到减小光学扫描单元100和电子照相成像装置的体积。
作为本发明的一个实施例，当温度变化时焦点的位置相应发生变化。温度变化时，在副扫描方向上焦点的位置的变化是基于光学扫描单元100内部的温度变化而变化，其测量焦点位置变化与Φ r/Φ d的关系可详细参见表6所示。
表6
Figure PCTCN2020088756-appb-000007
依据表6所示的设计示例值，可以绘制出副扫描方向焦点位置的变化与温度以及焦距之间的关系曲线图如图9所示。从图9可以看出，随着温度变化，在满足关系式0.7<Φ s/Φ n<1，同时当设计的第一光学单元30在副扫描方向上的焦距f 1为14.238mm满足(1-(f 1/f 2))×0.18<f 1×Φ r×K 2/K 1<(1+(f 1/f 2)) ×0.25的情况下，焦点位置的变化小，可见第一光学单元30的焦距变化能够得到很好的补偿。
另外，在实际光学扫描单元100的设计中，需要尽可能的缩短第一光学单元30和第二光学单元40的焦距，达到减少光学扫描单元100和电子照相成像装置200的体积的目的。通过测量第一光学单元30的焦距f 1及折射单元31的光焦度Φ r和衍射单元32的光焦度Φ d的值，从测量的结果分析得出，光束落在扫描目标表面上的焦点位置的变化随着设计的不同的焦距f 1而变化，并且，焦距f 1设计值越小，焦点就越容易波动，焦距f 1设计值越大，焦点的波动越不明显，但是焦距f 1设计值越大就会导致光学扫描单元100的体积增大，经测量分析第一光学单元30的焦距f 1优选取主扫描方向的值为20mm，副扫描方向的值为14.238mm，随着温度的变化第一光学单元30的焦距变化能够得到很好的补偿，能提高打印图像质量，且能实现光学扫描单元100的装置小型化。
结合参照图6与图7，从图7中可以看出焦距越长，主扫描方向上焦点位置变化越小，并且从图6中可以看出Φ r/Φ d无限趋近于0.5，主扫描方向上焦点位置变化越小。相反的，焦距越小，焦点位置变化越大，需要越大的补偿。为了降低成本，缩小体积，就需要把焦距做小，如果焦距做的足够小，对应第一光学单元30的制作成本越高，所以在实际设计中，需要考虑在光学扫描单元100与第一光学单元30成本之间取得平衡。
结合参照图8与图9，从图9中可以看出焦距越长，副扫描方向上焦点位置变化越小，并且从图8中可以看出，当Φ s/Φ n无限趋近于1，副扫描方向上焦点位置变化越小。相反的，焦距越小，焦点位置变化越大，需要越大的补偿。为了降低成本，缩小体积，就需要把焦距做小，如果焦距做的足够小，这对应第一光学单元30的制作成本相应的也就越高，所以在实际设计中，需要考虑在光学扫描单元100与第一光学单元30成本之间取的平衡。
综上，为了尽可能的降低成本，缩小体积，在本实施例中，第一光学单元30在主扫描方向的折射光焦度Φ r与衍射光焦度Φ d的比值满足不等式0.35＜Φ r/Φ d＜0.45，第一光学单元30在副扫描方向的折射光焦度Φ s与衍射光焦度Φ n的比值满足不等式0.98＜Φ s/Φ n＜1。
进一步地，在本实施例中，结合图7与图9可得出第一光学单元30在主 扫描方向的折射光焦度Φ r与衍射光焦度Φ d的比值、相对应的第一光学单元30在副扫描方向的折射光焦度Φ s与衍射光焦度Φ n的比值、以及第一光学单元30的主扫描方向的折射光焦度与衍射光焦度之比(Φ r/Φ d)m与第一光学单元30的副扫描方向的折射光焦度与衍射光焦度之比(Φ s/Φ n)s的比值，具体设计示例值可参见表7。
表7
Φ r/Φ d Φ s/Φ n (Φ r/Φ d)m/(Φ s/Φ n)s
0.32456 0.712333 0.45563
0.351245 0.9836 0.357115
0.39452055 0.985465 0.400339
0.433256 0.988562 0.407922
0.4732546 0.988912 0.417888
通过分析对比表7可知，第一光学单元30的主扫描方向的折射光焦度与衍射光焦度之比(Φ r/Φ d)m与所述第一光学单元30的副扫描方向的折射光焦度与衍射光焦度之比(Φ s/Φ n)s的比值范围满足关系式(3)。
且由表7所示的数值可以看出第一光学单元30的主扫描方向的折射光焦度与衍射光焦度之比(Φ r/Φ d)m与所述第一光学单元30的副扫描方向的折射光焦度与衍射光焦度之比(Φ s/Φ n)s的比值满足不等式0.35＜(Φ r/Φ d)m/(Φ s/Φ n)s＜0.45，综合考虑最佳。
可选地，如图5所示，在第一光学单元30与光源10之间设置有孔径光阑33，或者，如图3所示，在第一光学单元30与偏转装置20之间设置有孔径光阑33。
需要说明的是，第一，各部件可固定安装在支撑单元50上，这样孔径光阑33即可为加工在支撑单元50对应光路方向上的孔结构，孔径光阑33可阻挡边缘光线，以使光源10发射的光束经孔径光阑33成预设光斑的形状，示例的，孔径光阑33可以设置为圆形孔径光阑、椭圆形孔径光阑或者方形孔径光阑等，其具体形状不做特别限制，本领域技术人员可以根据实际情况做适当调整。
第二，如图5所示，孔径光阑33可以设置于第一光学单元30与光源10之间，用于对光源10出射的光束进行约束，或者，如图3所示，也可以在第一光学单元30与偏转装置20之间设置孔径光阑33，对应的，也可以对经过 第一光学单元30调制后将要入射偏转装置20的光束进行约束，当然，也可以不对光源10出射的光束进行约束，即孔径光阑33也可以省略。
本发明实施例的另一方面，提供一种电子照相成像装置200，包括上述的光学扫描单元100，还包括在扫描目标表面上形成潜像的感光单元210，将感光鼓上的潜像显影为碳粉图像的显影单元220，将碳粉图像转印到转印介质上的转印装置230，以及将转印介质上的碳粉图像定影的定影装置240。
为了打印成像，光扫描单元发出光束扫描到感光单元210上，感光单元210是光感受器的实例，感光单元210包括具有外圆周的圆柱形金属管，以及具有预定厚度的光敏层形成在外圆周上。充电辊250旋转并接触感光单元210，并且使感光单元210表面充电到均匀电势。光扫描单元在主扫描方向上扫描根据图像信息调制的光束，从而在感光单元210表面的成像面上形成静电潜像。在此情况下，随着感光单元210的旋转，成像面在副扫描方向上移动，光扫描单元与水平同步信号同步以在主扫描方向上将光束扫描到成像面上，因此，二维的静电潜像形成在感光单元210表面的成像面上。
显影单元220与感光单元210接触并将调色介质转移至感光单元210表面，从而形成打印图像。随着感光单元210的旋转，感光单元210表面的调色介质图像被偏转至纪录介质上。转印辊是具有一定的偏转电压，使感光单元210表面上的介质图像更容易地被吸附到记录介质270上，在转印之后感光单元210表面的残留的介质会被清洁单元260去除。转移至记录介质270上的调色介质图像经过定影单元的加热加压而被定影至记录介质270上，由此完成印刷操作。
由于光学扫描单元100包含与前述实施例中的光学扫描单元100相同的结构和有益效果。光学扫描单元100的结构和有益效果已经在前述实施例中进行了详细描述，在此不再赘述。
以上所述仅为本发明的优选实施例而已，并不用于限制本发明，对于本领域的技术人员来说，本发明可以有各种更改和变化。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (9)

  1. 一种光学扫描单元，其特征在于，包括：
    光源，用于发散光束；
    光学偏转器，用于偏转所述光源出射的光束；
    设置在所述光源与所述光学偏转器之间的第一光学单元，所述第一光学单元包括折射单元和衍射单元；
    设置在所述光学偏转器出光方向的第二光学单元，用于使所述光学偏转器偏转的光束在扫描目标表面上成像；
    其中，所述第一光学单元在主扫描方向的折射光焦度Φ r与衍射光焦度Φ d的比值范围为0.3＜Φ r/Φ d＜0.5；
    所述第一光学单元在副扫描方向的折射光焦度Φ s与衍射光焦度Φ n的比值范围为0.7＜Φ s/Φ n＜1.0。
  2. 根据权利要求1所述的光学扫描单元，其特征在于，所述第一光学单元的主扫描方向的折射光焦度与衍射光焦度之比(Φ r/Φ d)m与所述第一光学单元的副扫描方向的折射光焦度与衍射光焦度之比(Φ s/Φ n)s的比值范围为：
    0.3＜(Φ r/Φ d)m/(Φ s/Φ n)s＜0.5。
  3. 根据权利要求1或2所述的光学扫描单元，其特征在于，由于温度变化而引起光源的波长的变化为d λ/d T，其中，d λ/d T＜0.25。
  4. 根据权利要求1所述的光学扫描单元，其特征在于，所述第一光学单元包括变形透镜，或者包括独立的准直透镜和圆柱透镜。
  5. 根据权利要求4所述的光学扫描单元，其特征在于，所述第一光学单元为塑胶材质，所述折射单元以及所述衍射单元通过注塑一体成型于所述变形透镜的入射光侧表面和出射光侧表面。
  6. 根据权利要求5所述的光学扫描单元，其特征在于，在所述光源与所述第一光学单元之间设置有孔径光阑；
    或者，在所述第一光学单元与所述光学偏转器之间设置有孔径光阑。
  7. 根据权利要求1所述的光学扫描单元，其特征在于，
    0.35＜Φ r/Φ d＜0.45，0.98＜Φ s/Φ n＜1。
  8. 根据权利要求2所述的光学扫描单元，其特征在于，
    0.35＜(Φ r/Φ d)m/(Φ s/Φ n)s＜0.45。
  9. 一种电子照相成像装置，其特征在于，包括如权利要求1-8任一项所述的光学扫描单元，还包括在扫描目标表面上形成潜像的感光单元，将所述感光单元上的所述潜像显影为碳粉图像的显影单元，将所述碳粉图像转印到转印介质上的转印装置，以及将所述转印介质上的碳粉图像定影的定影装置。
PCT/CN2020/088756 2019-05-30 2020-05-06 光学扫描单元及电子照相成像装置 WO2020238565A1 (zh)

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