WO2020183707A1 - 走査光学系及び走査レンズ - Google Patents

走査光学系及び走査レンズ Download PDF

Info

Publication number
WO2020183707A1
WO2020183707A1 PCT/JP2019/010570 JP2019010570W WO2020183707A1 WO 2020183707 A1 WO2020183707 A1 WO 2020183707A1 JP 2019010570 W JP2019010570 W JP 2019010570W WO 2020183707 A1 WO2020183707 A1 WO 2020183707A1
Authority
WO
WIPO (PCT)
Prior art keywords
scanning
axis
scanning lens
optical system
value
Prior art date
Application number
PCT/JP2019/010570
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
智仁 桑垣内
Original Assignee
ナルックス株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ナルックス株式会社 filed Critical ナルックス株式会社
Priority to CN201980037018.XA priority Critical patent/CN112236707B/zh
Priority to KR1020207034118A priority patent/KR102534548B1/ko
Priority to JP2021505458A priority patent/JP6986312B2/ja
Priority to PCT/JP2019/010570 priority patent/WO2020183707A1/ja
Publication of WO2020183707A1 publication Critical patent/WO2020183707A1/ja

Links

Images

Classifications

    • 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
    • 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
    • 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
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/18—Optical objectives specially designed for the purposes specified below with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/24—Optical objectives specially designed for the purposes specified below for reproducing or copying at short object distances
    • 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
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/0087—Simple or compound lenses with index gradient
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/113—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using oscillating or rotating mirrors
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B2003/0093—Simple or compound lenses characterised by the shape

Definitions

  • the present invention relates to a scanning optical system and a scanning lens.
  • a compact scanning optical system has been developed (Patent Document 1 and Patent Document 2).
  • the angle of incidence of the light flux on the surface is large at the end of the scanning path and its vicinity, and the depth is significantly shallower than that at the center of the path.
  • the depth means the size of the range in the optical axis direction in which the diameter of the luminous flux is equal to or less than the maximum allowable value.
  • Japanese Patent No. 3303558 Japanese Patent Laid-Open No. 08-76011 Japanese Unexamined Patent Publication No. 2016-194675
  • An object of the present invention is a scanning optical system which is a compact scanning optical system and can be easily configured so that the diameter of a light flux on a surface is equal to or less than a maximum allowable value, and a scanning lens for such a scanning optical system. Is to provide.
  • the scanning optical system of the first aspect of the present invention includes a light source, a deflector, and a single scanning lens, and a light beam from the light source is deflected by the deflector, passes through the scanning lens, and scans a surface. It is configured to do.
  • the scanning direction on the surface is the y-axis
  • the main ray of the light beam perpendicular to the surface is the z-axis
  • the reflection point of the deflector of the main ray is the origin
  • the distance from the origin to the surface is defined as the origin.
  • L the length of the scanning path along the y-axis on the surface be W, and the maximum and minimum values of the y-coordinate of the point where the main ray passes through the exit surface of the scanning lens be ymax and ymin, respectively.
  • c the curvature of the exit surface in the main scanning direction at that point
  • n the refractive index of the material of the scanning lens
  • the power ⁇ (1-n) ⁇ c in the main scanning direction at that point.
  • a compact optical system can be realized by setting the term of equation (1) to the upper limit or less. Further, by satisfying the equation (2), even when the emission surface of the scanning lens is eccentric in the y-axis direction, it is set to be equal to or less than the allowable maximum value that satisfies the luminous flux diameter with respect to the value in the entire range of the image height. A scanning optical system is obtained. Therefore, even in a compact scanning optical system having a shallow depth at and around the end of the scanning path on the surface and a small distance from the deflector to the surface compared to the length of the scanning path, the main scanning direction. The change in the light beam diameter is robust to the eccentricity of the exit surface in the y-axis direction, and a scanning optical system that is easy to manufacture can be obtained.
  • the maximum value of the y coordinate of the scanning path is set to Ymax, and the main ray reaching the position of Ymax of the scanning path travels after passing through the deflector.
  • equation (3) If the term of equation (3) exceeds the upper limit, it becomes difficult to correct the aberration. If the term of the equation (3) is less than the lower limit, it is advantageous for aberration correction, but it becomes difficult to secure the thickness of the end portion of the scanning lens. Therefore, it is desirable to satisfy the equation (3).
  • the distance from the deflector to the scanning lens along the z-axis is d1. 0.16 ⁇ d1 / L ⁇ 0.19... (4) Meet.
  • equation (4) If the term of equation (4) exceeds the upper limit, the size of the scanning lens will increase and the cost will increase. When the term of the equation (4) is less than the lower limit, the size of the scanning lens becomes smaller, but it becomes difficult to correct the aberration. Therefore, it is desirable to satisfy the equation (4).
  • the luminous flux incident on the deflector is a convergent luminous flux in the yz cross section, and the incident surface of the scanning lens is near the optical axis coincided with the z axis.
  • the exit surface is convex toward the object side, and the exit surface is concave toward the image side in the vicinity of the optical axis.
  • the scanning lens of the second aspect of the present invention is a scanning optical system including a light source, a deflector, and the scanning lens, and a light beam from the light source is deflected by the deflector, passes through the scanning lens, and passes through a surface. It is configured to scan, the scanning direction on the surface is the y-axis, the main ray of the light beam incident perpendicular to the surface is the z-axis, the reflection point of the deflector of the main ray is the origin, and the origin.
  • L be the distance from the surface to the surface
  • W be the length of the scanning path along the y-axis on the surface
  • ymax and ymin respectively, the partial curvature of the exit surface in the main scanning direction at that point be c
  • the refractive index of the material of the scanning lens be n
  • the power ⁇ (1-n) in the main scanning direction at that point.
  • the scanning optical system including the scanning lens of this embodiment becomes compact by setting the term of equation (1) to the upper limit or less. Further, by satisfying the equation (2), even when the emission surface of the scanning lens is eccentric in the y-axis direction, it is set to be equal to or less than the allowable maximum value that satisfies the luminous flux diameter with respect to the value in the entire range of the image height. A scanning lens is obtained. Therefore, even in a compact scanning optical system having a shallow depth at and around the end of the scanning path on the surface and a small distance from the deflector to the surface compared to the length of the scanning path, the main scanning direction. The change in the light beam diameter is robust to the eccentricity of the exit surface in the y-axis direction, and a scanning lens for a scanning optical system that is easy to manufacture can be obtained.
  • the incident surface of the scanning lens is convex toward the object in the vicinity of the optical axis corresponding to the z axis in the yz cross section, and the exit surface is the optical axis. It is concave on the image side in the vicinity of.
  • FIG. 1 is a diagram showing a scanning optical system according to an embodiment of the present invention (Example 1 described later).
  • the luminous flux emitted from the semiconductor laser light source 200 is converted into a convergent luminous flux by the incident optical element 300, passes through the aperture 400, is changed in the traveling direction by a deflector 500 such as a polygon mirror, passes through the scanning lens 100, and then passes through the scanning lens 100. It is focused on the surface 600.
  • the optical system from the light source 200 to the deflector 500 is called an incident optical system, and the optical system from the deflector 500 to the surface 600 is called an imaging optical system.
  • the direction perpendicular to the rotation axis of the deflector 500 and the optical axis of the imaging optical system is called the main scanning direction.
  • the main scanning direction is the direction in which the convergent luminous flux scans the surface 600.
  • the origin (0,0) is a reflection point on the surface of the deflector 500 of the main ray of the luminous flux perpendicularly incident on the surface 600, and the z-axis is defined in the direction in which the main ray is reflected at the origin and then travels.
  • the optical axis of the imaging optical system and the scanning lens 100 coincides with the z-axis.
  • the y-axis is set in the main scanning direction.
  • FIG. 1 shows a yz cross section of the scanning optical system.
  • the yz cross section is also referred to as a main scanning cross section.
  • the direction perpendicular to the yz cross section is called the sub-scanning direction.
  • the x-axis is set in the sub-scanning direction.
  • the xz cross section is also referred to as a sub-scanning cross section.
  • the distance from the origin along the z-axis to the scanning lens 100 is represented by d1
  • the distance from the origin along the z-axis to the surface 600 is represented by L.
  • the above-mentioned focused luminous flux scans the surface 600 at a substantially constant speed.
  • the y coordinate of the position of the luminous flux on the surface 600 is called an image height.
  • the maximum value of the image height is represented by Ymax, and the angle formed by the z-axis and the direction in which the main ray of the focused luminous flux corresponding to the maximum value of the image height is reflected by the surface of the deflector 500 is ⁇ .
  • the length (scanning width) of the scanning path on the surface 600 is represented by W.
  • the incident optical element 300 is an anamorphic optical element in which the focal length in the main scanning direction and the focal length in the sub-scanning direction are different.
  • the incident optical element 300 converts the luminous flux emitted from the laser light source 200 in the main scanning direction in the imaging optical system into convergent light, and condenses the light flux on the surface of the deflector 500 in the sub-scanning direction.
  • the luminous flux has a flat shape that is long in the main scanning direction on the surface of the deflector 500.
  • the focal length of the incident optical element 300 in the sub-scanning direction is shorter than the focal length of the incident optical element 300 in the main scanning direction.
  • the incident optical element 300 includes a diffraction grating on the lens surface in order to compensate for the performance change due to the temperature fluctuation.
  • the spreading angle of the light flux in the thickness direction of the cross section of the active region is larger than the spreading angle of the light flux in the width direction of the cross section of the active region.
  • the thickness direction and the width direction are made to correspond to the main scanning direction and the sub scanning direction, respectively.
  • the scanning lens 100 of the imaging optical system concentrates the focused light flux deflected by the deflector 500 on the surface 600 in the main scanning direction, and the light flux focused on the surface of the deflector 500 in the sub-scanning direction. Is focused on the surface 600. That is, in the sub-scanning direction, the focusing point on the surface of the deflector 500 and the focusing point on the surface 600 are in a conjugate relationship.
  • the scanning lens of the imaging optical system is preferably single from the viewpoint of cost.
  • FIG. 2 is a diagram showing the relationship between the z coordinate and the luminous flux diameter (beam diameter) in the main scanning direction in the scanning optical system of one embodiment of the present invention (Example 1 described later).
  • the horizontal axis of FIG. 2 represents the z coordinate.
  • the vertical axis of FIG. 2 represents the luminous flux diameter in the main scanning direction.
  • FIG. 2 shows the relationship between the z coordinate and the luminous flux diameter in the main scanning direction for the luminous flux having an image height Y of 108 mm, 54 mm, 0, ⁇ 54 mm, and ⁇ 108 mm.
  • the broken line parallel to the horizontal axis in FIG. 2 indicates the maximum allowable value of the luminous flux diameter.
  • the size of the range of z in which the luminous flux diameter is equal to or less than the maximum allowable value is called the depth.
  • the maximum or minimum value of the image height and its vicinity that is, the end of the scanning path and its vicinity to the surface 600.
  • the incident angle of the luminous flux becomes large, and the depth becomes remarkably shallow as compared with the case where the image height is 0.
  • the F value of the off-axis luminous flux is generally smaller than the F value of the axial luminous flux, the depth at the end of the scanning path and its vicinity becomes shallow. Further, as L becomes shorter, the F value of the off-axis luminous flux tends to become smaller, so that the depth at the end of the scanning path and its vicinity becomes significantly shallower.
  • FIG. 3 is a diagram for explaining the features of the scanning lens 100.
  • FIG. 3 shows a yz cross section of the scanning lens 100.
  • the y coordinate of the point where the main ray of the luminous flux reaching the maximum image height passes through the exit surface 103 of the scanning lens 100 is ymax, and the main ray of the luminous flux reaching the minimum image height is Let y min be the y coordinate of the point passing through the exit surface 103 of the scanning lens 100.
  • y-coordinate is referred to as an inner region of the exit surface 103 of the scanning lens 100 regions to 0.6Y max from 0.6y min, from the region and 0.6Y max from y min to 0.6Y min to y max The region is referred to as a region outside the emission surface 103 of the scanning lens 100.
  • ⁇ (1-n) ⁇ c... (5)
  • n the refractive index of the material of the scanning lens 100
  • c the partial curvature of the exit surface 103 at the above points in the main scanning direction.
  • the shapes of the entrance surface and the exit surface of the scanning lens of the embodiment can be expressed by the following equations.
  • the shapes of the entrance surface and the exit surface of the scanning lens of the present invention are not limited to those represented by the following equations.
  • the position of the apex of the lens on the z-axis is set as the origin
  • the x-axis is set in the sub-scanning direction
  • the y-axis is set in the main scanning direction.
  • the symbols representing the variables, constants and coefficients of the equation (6) are as follows.
  • Example 1 is a table showing data of the optical arrangement and optical elements of the scanning optical system of Example 1.
  • Table 2 is a table showing the constants and coefficients of the equation (4) representing the surface shape of the scanning lens of the first embodiment.
  • R x in Table 2 represents r x (0) in Eq. (7).
  • FIG. 4A is a diagram showing the amount of change in curvature of field when the emission surface of the scanning lens of Example 1 is eccentric by +50 micrometers in the y-axis direction.
  • the horizontal axis of FIG. 4A indicates the image height.
  • the image height of 0 corresponds to the z-axis, that is, the position of the intersection of the optical axis of the scanning lens 300 and the surface 600.
  • the vertical axis of FIG. 4A shows the amount of change in curvature of field.
  • the amount of change in curvature of field is the value obtained by subtracting the value of curvature of field in the state without eccentricity from the value of curvature of field in the eccentric state.
  • the absolute value of the amount of change in curvature of field is relatively large at an image height of around ⁇ 30 mm, and the absolute value of the amount of change in curvature of field near the maximum and minimum values of image height is relatively large. Is relatively small.
  • the incident angle of the luminous flux on the surface 600 becomes large at and near the maximum or minimum value of the image height, and the image height is 0.
  • the depth is significantly shallower in comparison, in this embodiment, the maximum value, the minimum value, and the vicinity thereof, that is, the amount of change in the curvature of field due to the eccentricity of the exit surface at the end of the scanning path and its vicinity.
  • the absolute value of is relatively small, the luminous flux diameter in the main scanning direction is equal to or less than the maximum allowable value.
  • the absolute value of the amount of change in curvature of field is relatively large at an image height of around ⁇ 30 mm, but according to FIG. 2, the depth is deep at an image height of around ⁇ 30 mm, so the exit surface. Even if the curvature of field changes significantly due to the eccentricity of, the luminous flux diameter in the main scanning direction remains below the maximum allowable value.
  • the luminous flux diameter in the main scanning direction with respect to the value in the entire range of the image height. Can be less than or equal to the maximum allowable value.
  • the imaging position in the main scanning cross section is affected by the power ⁇ in the main scanning direction of the exit surface of the scanning lens. Therefore, it is considered that the magnitude of the change in curvature of field when the emission surface of the scanning lens is eccentric in the y-axis direction is closely related to the differential value of the power ⁇ in the main scanning direction of the emission surface in the y direction. ..
  • FIG. 4B is a diagram showing the relationship between the y coordinate of the emission surface of the scanning lens of Example 1 and the differential value of the power ⁇ in the main scanning direction of the emission surface in the y direction.
  • the horizontal axis of FIG. 4B shows the y-coordinate of the exit surface, and the vertical axis of FIG. 4B shows the differential value of the power ⁇ in the main scanning direction of the exit surface in the y-direction.
  • the shape of the graph in FIG. 4A and the shape of the graph in FIG. 4B are similar. Therefore, the amount of change in curvature of field when the emission surface of the scanning lens is eccentric in the y-axis direction is large because of the relationship between the y coordinate of the emission surface and the differential value of the power ⁇ in the main scanning direction of the emission surface in the y direction. It is thought that the coordinates can be predicted.
  • FIG. 4C is a diagram showing the relationship between the y coordinate of the emission surface of the scanning lens of the first embodiment and the absolute value of the differential value of the power ⁇ in the main scanning direction of the emission surface in the y direction.
  • the horizontal axis of FIG. 4C indicates the y coordinate of the exit surface.
  • the vertical axis of FIG. 4C is the absolute value of the differential value of the power ⁇ in the main scanning direction of the exit surface in the y direction.
  • the maximum value of the absolute value of the differential value of the power ⁇ in the main scanning direction of the exit surface in the outer region in the y direction is
  • the level of the maximum absolute value of the absolute value of the differential value in the y direction of the power ⁇ in the main scanning direction of the exit surface in the inner region in the inner region is shown by a dotted line, and the emission surface in the inner region in the outer region.
  • the level of 0.5 times the maximum absolute value of the differential value of the power ⁇ in the main scanning direction in the y direction is shown by the dotted line. Because the graph is below the dotted level in the outer area
  • the absolute value of the amount of change in image plane curvature is relative to the end of the scanning path and its vicinity when the emission surface of the scanning lens is eccentric in the y-axis direction. Can be made smaller.
  • Example 2 is a table showing data of the optical arrangement and optical elements of the scanning optical system of Example 2.
  • Table 4 is a table showing the constants and coefficients of the equation (4) representing the surface shape of the scanning lens of the second embodiment.
  • R x in Table 4 represents r x (0) in Eq. (7).
  • FIG. 5A is a diagram showing the amount of change in curvature of field when the emission surface of the scanning lens of Example 2 is eccentric by +50 micrometers in the y-axis direction.
  • the horizontal axis of FIG. 5A indicates the image height.
  • the image height of 0 corresponds to the z-axis, that is, the position of the intersection of the optical axis of the scanning lens 300 and the surface 600.
  • the vertical axis of FIG. 5A shows the amount of change in curvature of field.
  • the amount of change in curvature of field is the value obtained by subtracting the value of curvature of field in the state without eccentricity from the value of curvature of field in the eccentric state.
  • the absolute value of the amount of change in curvature of field is large at an image height of around ⁇ 30 millimeters, and the absolute value of the amount of change in curvature of field is small at the maximum and minimum values of image height and its vicinity.
  • the relationship between the z coordinate and the luminous flux diameter in the main scanning direction in the scanning optical system of this embodiment is the same as that shown in FIG. Therefore, as in the case of the first embodiment, in the scanning optical system of the present embodiment, the value in the entire range of the image height is obtained even when the emission surface of the scanning lens is eccentric by +50 micrometers in the y-axis direction.
  • the luminous flux diameter in the main scanning direction can be equal to or less than the maximum allowable value.
  • FIG. 5B is a diagram showing the relationship between the y-coordinate of the emission surface of the scanning lens of the second embodiment and the differential value of the power ⁇ in the main scanning direction of the emission surface in the y-direction.
  • the horizontal axis of FIG. 5B shows the y-coordinate of the exit surface
  • the vertical axis of FIG. 5B shows the differential value of the power ⁇ in the main scanning direction of the exit surface in the y-direction.
  • FIG. 5C is a diagram showing the relationship between the y coordinate of the emission surface of the scanning lens of the second embodiment and the absolute value of the differential value of the power ⁇ in the main scanning direction of the emission surface in the y direction.
  • the horizontal axis of FIG. 5C indicates the y coordinate of the exit surface.
  • the vertical axis of FIG. 5C is the absolute value of the differential value of the power ⁇ in the main scanning direction of the exit surface in the y direction.
  • the maximum value of the absolute value of the differential value of the power ⁇ in the main scanning direction of the exit surface in the outer region in the y direction is
  • the level of the maximum absolute value of the absolute value of the differential value in the y direction of the power ⁇ in the main scanning direction of the exit surface in the inner region in the inner region is shown by a dotted line, and the emission surface in the inner region in the outer region.
  • the level of 0.5 times the maximum absolute value of the differential value of the power ⁇ in the main scanning direction in the y direction is shown by the dotted line. Because the graph is below the dotted level in the outer area
  • the maximum value of the absolute value of the differential value of the power ⁇ in the main scanning direction of the exit surface in the outer region in the y direction and the differential value of the power ⁇ in the main scanning direction of the exit surface in the inner region in the y direction By reducing the ratio of the absolute value to the maximum value, the absolute change in the image plane curvature at the maximum and minimum values of the image height and its vicinity when the emission surface of the scanning lens is eccentric in the y-axis direction. The value can be relatively small.
  • Example 3 is a table showing data of the optical arrangement and optical elements of the scanning optical system of Example 3.
  • Table 6 is a table showing the constants and coefficients of the equation (4) representing the surface shape of the scanning lens of the third embodiment.
  • R x in Table 6 represents r x (0) in Eq. (7).
  • FIG. 6A is a diagram showing the amount of change in curvature of field when the emission surface of the scanning lens of Example 3 is eccentric by +50 micrometers in the y-axis direction.
  • the horizontal axis of FIG. 6A indicates the image height.
  • the image height of 0 corresponds to the z-axis, that is, the position of the intersection of the optical axis of the scanning lens 300 and the surface 600.
  • the vertical axis of FIG. 6A shows the amount of change in curvature of field.
  • the amount of change in curvature of field is the value obtained by subtracting the value of curvature of field in the state without eccentricity from the value of curvature of field in the eccentric state.
  • the absolute value of the amount of change in curvature of field is large at an image height of around ⁇ 40 millimeters, and the absolute value of the amount of change in curvature of field is small at the maximum and minimum values of image height and its vicinity.
  • the relationship between the z coordinate and the luminous flux diameter in the main scanning direction in the scanning optical system of this embodiment is the same as that shown in FIG. Therefore, as in the case of the first embodiment, in the scanning optical system of the present embodiment, the value in the entire range of the image height is obtained even when the emission surface of the scanning lens is eccentric by +50 micrometers in the y-axis direction.
  • the luminous flux diameter in the main scanning direction can be equal to or less than the maximum allowable value.
  • FIG. 6B is a diagram showing the relationship between the y coordinate of the emission surface of the scanning lens of Example 3 and the differential value of the power ⁇ in the main scanning direction of the emission surface in the y direction.
  • the horizontal axis of FIG. 6B shows the y-coordinate of the exit surface, and the vertical axis of FIG. 6B shows the differential value of the power ⁇ in the main scanning direction of the exit surface in the y-direction.
  • FIG. 6C is a diagram showing the relationship between the y coordinate of the emission surface of the scanning lens of Example 3 and the absolute value of the differential value of the power ⁇ in the main scanning direction of the emission surface in the y direction.
  • the horizontal axis of FIG. 6C indicates the y coordinate of the exit surface.
  • the vertical axis of FIG. 6C is the absolute value of the differential value of the power ⁇ in the main scanning direction of the exit surface in the y direction.
  • the maximum value of the absolute value of the differential value of the power ⁇ in the main scanning direction of the exit surface in the outer region in the y direction is
  • the level of the maximum absolute value of the absolute value of the differential value in the y direction of the power ⁇ in the main scanning direction of the exit surface in the inner region in the inner region is shown by a dotted line, and the emission surface in the inner region in the outer region.
  • the level of 0.5 times the maximum absolute value of the differential value of the power ⁇ in the main scanning direction in the y direction is shown by the dotted line. Because the graph is below the dotted level in the outer area
  • the maximum value of the absolute value of the differential value of the power ⁇ in the main scanning direction of the exit surface in the outer region in the y direction and the differential value of the power ⁇ in the main scanning direction of the exit surface in the inner region in the y direction By reducing the ratio of the absolute value to the maximum value, the absolute change in the image plane curvature at the maximum and minimum values of the image height and its vicinity when the emission surface of the scanning lens is eccentric in the y-axis direction. The value can be relatively small.
  • Example 1 of Japanese Patent No. 3303558 Japanese Patent Laid-Open No. 08-76011 is referred to as Conventional Example 1.
  • FIG. 7A is a diagram showing the amount of change in curvature of field when the emission surface of the scanning lens of Conventional Example 1 is eccentric by +50 micrometer in the y-axis direction.
  • the horizontal axis of FIG. 7A indicates the image height.
  • the image height of 0 corresponds to the z-axis, that is, the position of the intersection of the optical axis of the scanning lens 300 and the surface 600.
  • the vertical axis of FIG. 7A shows the amount of change in curvature of field.
  • the amount of change in curvature of field is the value obtained by subtracting the value of curvature of field in the state without eccentricity from the value of curvature of field in the eccentric state.
  • the absolute value of the amount of change in curvature of field is relatively large at and near the maximum and minimum values of the image height.
  • FIG. 7B is a diagram showing the relationship between the y coordinate of the emission surface of the scanning lens of Conventional Example 1 and the differential value of the power ⁇ in the main scanning direction of the emission surface in the y direction.
  • the horizontal axis of FIG. 7B shows the y-coordinate of the exit surface, and the vertical axis of FIG. 7B shows the differential value of the power ⁇ in the main scanning direction of the exit surface in the y-direction.
  • the shape of the graph in FIG. 7A and the shape of the graph in FIG. 7B are similar.
  • FIG. 7C is a diagram showing the relationship between the y coordinate of the emission surface of the scanning lens of Conventional Example 1 and the absolute value of the differential value of the power ⁇ in the main scanning direction of the emission surface in the y direction.
  • the horizontal axis of FIG. 7C indicates the y coordinate of the exit surface.
  • the vertical axis of FIG. 7C is the absolute value of the differential value of the power ⁇ in the main scanning direction of the exit surface in the y direction.
  • FIG. 7C the level of the maximum absolute value of the absolute value of the differential value in the y direction of the power ⁇ in the main scanning direction of the exit surface in the inner region in the inner region is shown by a dotted line, and the emission surface in the inner region in the outer region.
  • the level of 0.5 times the maximum absolute value of the differential value of the power ⁇ in the main scanning direction in the y direction is shown by the dotted line. According to FIG. 7C, the equation (2) described later is not satisfied.
  • FIG. 8A is a diagram showing the amount of change in curvature of field when the emission surface of the scanning lens of Conventional Example 2 is eccentric by +50 micrometer in the y-axis direction.
  • the horizontal axis of FIG. 8A indicates the image height.
  • the image height of 0 corresponds to the z-axis, that is, the position of the intersection of the optical axis of the scanning lens 300 and the surface 600.
  • the vertical axis of FIG. 8A shows the amount of change in curvature of field.
  • the amount of change in curvature of field is the value obtained by subtracting the value of curvature of field in the state without eccentricity from the value of curvature of field in the eccentric state.
  • the absolute value of the amount of change in curvature of field is relatively large at and near the maximum and minimum values of the image height.
  • FIG. 8B is a diagram showing the relationship between the y coordinate of the emission surface of the scanning lens of Conventional Example 2 and the differential value of the power ⁇ in the main scanning direction of the emission surface in the y direction.
  • the horizontal axis of FIG. 8B shows the y-coordinate of the exit surface
  • the vertical axis of FIG. 8B shows the differential value of the power ⁇ in the main scanning direction of the exit surface in the y-direction.
  • the shape of the graph in FIG. 8A and the shape of the graph in FIG. 8B are similar.
  • FIG. 8C is a diagram showing the relationship between the y coordinate of the emission surface of the scanning lens of Conventional Example 2 and the absolute value of the differential value of the power ⁇ in the main scanning direction of the emission surface in the y direction.
  • the horizontal axis of FIG. 8C indicates the y coordinate of the exit surface.
  • the vertical axis of FIG. 8C is the absolute value of the differential value of the power ⁇ in the main scanning direction of the exit surface in the y direction.
  • FIG. 8C the level of the maximum absolute value of the absolute value of the differential value in the y direction of the power ⁇ in the main scanning direction of the exit surface in the inner region in the inner region is shown by a dotted line, and the emission surface in the inner region in the outer region.
  • the level of 0.5 times the maximum absolute value of the differential value of the power ⁇ in the main scanning direction in the y direction is shown by the dotted line. According to FIG. 8C, the equation (2) described later is not satisfied.
  • Example 1-3 satisfies the following equation. 0.54 ⁇ L / W ⁇ 0.64... (1)
  • a compact optical system can be realized by setting the term of equation (1) to the upper limit or less. If the term of equation (1) is less than the lower limit, it is difficult to correct curvature of field and scanning characteristics, and the depth of the edge of the image plane is further shortened, so that stable production cannot be expected.
  • the luminous flux diameter is satisfied with respect to the value in the entire range of the image height even when the emission surface of the scanning lens is eccentric in the y-axis direction.
  • a scanning optical system having a maximum allowable value or less can be obtained. Therefore, even in a compact scanning optical system having a shallow depth at and around the end of the scanning path on the surface and a small distance from the deflector to the surface compared to the length of the scanning path, the main scanning direction.
  • the change in the light beam diameter is robust to the eccentricity of the exit surface in the y-axis direction, so that a scanning optical system and a scanning lens that are easy to manufacture can be obtained.
  • equation (3) exceeds the upper limit, it becomes difficult to correct the aberration. If the term of the equation (3) is less than the lower limit, it is advantageous for aberration correction, but it becomes difficult to secure the thickness of the end portion of the scanning lens.
  • equation (4) If the term of equation (4) exceeds the upper limit, the size of the scanning lens will increase and the cost will increase. When the term of the equation (4) is less than the lower limit, the size of the scanning lens becomes smaller, but it becomes difficult to correct the aberration.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Mechanical Optical Scanning Systems (AREA)
  • Lenses (AREA)
  • Laser Beam Printer (AREA)
  • Facsimile Scanning Arrangements (AREA)
PCT/JP2019/010570 2019-03-14 2019-03-14 走査光学系及び走査レンズ WO2020183707A1 (ja)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CN201980037018.XA CN112236707B (zh) 2019-03-14 2019-03-14 扫描光学系统和扫描透镜
KR1020207034118A KR102534548B1 (ko) 2019-03-14 2019-03-14 주사 광학계 및 주사 렌즈
JP2021505458A JP6986312B2 (ja) 2019-03-14 2019-03-14 走査光学系及び走査レンズ
PCT/JP2019/010570 WO2020183707A1 (ja) 2019-03-14 2019-03-14 走査光学系及び走査レンズ

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2019/010570 WO2020183707A1 (ja) 2019-03-14 2019-03-14 走査光学系及び走査レンズ

Publications (1)

Publication Number Publication Date
WO2020183707A1 true WO2020183707A1 (ja) 2020-09-17

Family

ID=72426654

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2019/010570 WO2020183707A1 (ja) 2019-03-14 2019-03-14 走査光学系及び走査レンズ

Country Status (4)

Country Link
JP (1) JP6986312B2 (ko)
KR (1) KR102534548B1 (ko)
CN (1) CN112236707B (ko)
WO (1) WO2020183707A1 (ko)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002006211A (ja) * 2000-06-23 2002-01-09 Canon Inc 温度補償レンズ及びそれを用いた光学装置
JP2003215444A (ja) * 2002-01-18 2003-07-30 Hitachi Printing Solutions Ltd 透過型光学素子
EP1995623A2 (en) * 2007-05-25 2008-11-26 Samsung Electronics Co., Ltd. Optical scanning unit and electro-photographic image forming apparatus including the same
JP2016194675A (ja) * 2015-03-31 2016-11-17 キヤノン株式会社 光走査装置

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3075056B2 (ja) * 1993-12-21 2000-08-07 ミノルタ株式会社 走査光学系
JP3303558B2 (ja) 1994-09-06 2002-07-22 キヤノン株式会社 走査光学装置
KR101236388B1 (ko) * 2006-11-07 2013-02-22 삼성전자주식회사 광주사유니트 및 이를 이용한 화상형성장치

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002006211A (ja) * 2000-06-23 2002-01-09 Canon Inc 温度補償レンズ及びそれを用いた光学装置
JP2003215444A (ja) * 2002-01-18 2003-07-30 Hitachi Printing Solutions Ltd 透過型光学素子
EP1995623A2 (en) * 2007-05-25 2008-11-26 Samsung Electronics Co., Ltd. Optical scanning unit and electro-photographic image forming apparatus including the same
JP2016194675A (ja) * 2015-03-31 2016-11-17 キヤノン株式会社 光走査装置

Also Published As

Publication number Publication date
JP6986312B2 (ja) 2021-12-22
JPWO2020183707A1 (ja) 2021-09-13
CN112236707B (zh) 2022-06-21
CN112236707A (zh) 2021-01-15
KR20210005181A (ko) 2021-01-13
KR102534548B1 (ko) 2023-05-18

Similar Documents

Publication Publication Date Title
JP3072061B2 (ja) 光走査装置
US8472099B2 (en) Scanning optical apparatus
JPH0627904B2 (ja) レーザービームの走査光学系
JP3222498B2 (ja) 走査光学系
JP3620767B2 (ja) 反射型走査光学系
JP2007140418A (ja) 走査装置及び走査光学系
JPH07113950A (ja) 光ビーム走査装置及び結像レンズ
JP6986312B2 (ja) 走査光学系及び走査レンズ
JP3486508B2 (ja) 光走査光学装置
JP4297062B2 (ja) レーザー走査装置
JPH04229819A (ja) 光走査装置
JP4345856B2 (ja) レーザー走査装置
JPH08240768A (ja) 走査光学系
JP3392984B2 (ja) 走査レンズ
JP3627781B2 (ja) レーザー走査装置
US20030184834A1 (en) Laser scanning apparatus
JPH08248308A (ja) 走査レンズ及び光走査装置
JPH08122635A (ja) 光走査光学系
JP6829514B1 (ja) 走査光学系の製造方法
JP4297072B2 (ja) レーザー走査装置
WO2021038949A1 (ja) 走査光学系の製造方法
WO2024070881A1 (ja) 走査光学系
US6178030B1 (en) Light-scanning optical system having wobble-correcting function and light-scanning apparatus using the same
JP3804886B2 (ja) 光走査装置用結像光学系
JP3341121B2 (ja) 走査光学系

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 19918551

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 20207034118

Country of ref document: KR

Kind code of ref document: A

ENP Entry into the national phase

Ref document number: 2021505458

Country of ref document: JP

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 19918551

Country of ref document: EP

Kind code of ref document: A1