JP5267850B2 - Production method of optical scanning device - Google Patents

Description

The present invention relates to a method for manufacturing an optical scanning device, and more particularly to a method for manufacturing an optical scanning device that scans a surface to be scanned with a light beam.

  In recent years, image forming apparatuses such as laser printers and digital copying machines have been desired to improve printing speed (high speed) and write density (high image quality). As a method for achieving these requirements, a method of scanning a surface to be scanned with a plurality of light beams using a multi-beam light source capable of emitting a plurality of light beams has been considered. Along with this, various proposals have been made on scanning optical systems compatible with multi-beams.

  For example, in Patent Document 1, the curvature in the sub-scanning direction of both lens surfaces of a single lens is continuously changed from on-axis to off-axis, so that the sub-scanning direction depends on the image height of the light beam incident on the surface to be scanned. There is disclosed a multi-beam scanning optical apparatus that suppresses a change in the F number.

  Further, Patent Document 2 includes at least two special surfaces that are composed of two or more balls and whose sub-scanning curvature changes from the optical axis to the periphery in the main scanning direction, and at least one of the special surfaces. One surface discloses an optical scanning device using a scanning imaging lens in which the change in the sub-scanning curvature is asymmetric in the main scanning direction and the sub-scanning curvature has a plurality of extreme values.

  Further, in Patent Document 3, the curvature of the two lens surfaces in the sub-scanning direction is continuously changed from on-axis to the off-axis so that the main plane position in the sub-scanning direction on the axis in the optical axis direction is the axis. An optical scanning device that sets the outer main plane position in the sub-scanning direction closer to the surface to be scanned, thereby suppressing the change in the F-number in the sub-scanning direction due to the image height of the light beam incident on the surface to be scanned. It is disclosed.

  Further, Patent Document 4 discloses a light source having a two-dimensional array of light emitting elements that scans scanning lines having the same or different light emitting points, and a deflection unit that collectively scans a plurality of beams from the light source in the main scanning direction. An optical scanning device that rotates and adjusts the light source around the optical axis so that the exposure energy distribution in the sub-scanning line direction formed by the beams in the same scan is substantially equal to the desired exposure energy distribution is disclosed. Has been.

Japanese Patent No. 3445050 Japanese Patent No. 3768734 JP 2005-338865 A JP 2002-287055 A

  By the way, for example, a light source in which a plurality of light emitting units are two-dimensionally arranged at high density, such as a so-called surface emitting laser array, is advantageous in performing high density writing. However, in a light source in which a plurality of light emitting units are arranged one-dimensionally, the light emitting unit interval in the sub-scanning direction can be adjusted simultaneously by rotating the light source around its optical axis direction (so-called γ rotation). Yes, while the scanning line interval on the surface to be scanned can be made uniform, in a light source in which a plurality of light emitting units are arranged two-dimensionally, the change in the interval between the light emitting units when γ rotation is performed Therefore (see FIG. 12), it is very difficult to uniformly adjust the scanning line interval on the surface to be scanned with high accuracy that will be required in the future for high image quality by γ rotation. In the present specification, the “light emitting portion interval” refers to the distance between the centers of two light emitting portions.

The present invention has been made under such circumstances, purpose of that is to provide a method of producing an optical scanning apparatus capable of performing without accurately scanning by a plurality of light beams can lead to high cost It is in.

From a first viewpoint, the present invention is a method for producing an optical scanning device that scans a surface to be scanned in a main scanning direction with a plurality of light beams, and the optical scanning device includes a plurality of light emitting units arranged two-dimensionally. A pre-deflector optical system disposed on an optical path of a light beam from the light source, and a pre-deflector optical system including a light source, a first optical element having a positive power, and a second optical element having a negative power. A deflector for deflecting the light beam through the system, and a scanning optical system for condensing the light beam deflected by the deflector on the surface to be scanned, and the absolute value of the power of the first optical element is A step of outputting a plurality of light fluxes from the light source and irradiating the evaluation image plane corresponding to the scanned surface; the beam pitch on the evaluation image plane being larger than the absolute value of the power of the second optical element ; An interval between the first optical element and the second optical element is set so that a desired value is obtained. Adjusting the first optical element and the second optical element so that a plurality of light beams from the light source are collected on the evaluation image plane, while maintaining the adjusted distance. And a step of moving the optical element and the second optical element in the optical axis direction.

According to a second aspect of the present invention, there is provided a method for producing an optical scanning device that scans a surface to be scanned in a main scanning direction with a plurality of light beams. The optical scanning device includes a plurality of light emitting units arranged two-dimensionally. A pre-deflector optical system disposed on an optical path of a light beam from the light source, and a pre-deflector optical system including a light source, a first optical element having a positive power, and a second optical element having a negative power. A deflector for deflecting the light beam through the system, and a scanning optical system for condensing the light beam deflected by the deflector on the surface to be scanned, and the absolute value of the power of the first optical element is larger than the absolute value of the power of the second optical element, and outputs a plurality of light beams from the light source, process and irradiating the evaluation image plane corresponding to the surface to be scanned; a plurality of light beams the evaluation image from the light source A step of moving the first optical element in the optical axis direction so as to collect light on the surface; ; Such that the beam pitch on the evaluation image plane becomes a desired value, process and moving the second optical element in the optical axis direction; a method of producing an optical scanning apparatus including a.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a laser printer 1000 as an image forming apparatus according to an embodiment of the present invention.

  The laser printer 1000 includes an optical scanning device 1010, a photosensitive drum 1030, a charging charger 1031, a developing roller 1032, a transfer charger 1033, a static elimination unit 1034, a cleaning blade 1035, a toner cartridge 1036, a paper supply roller 1037, a paper supply tray 1038, A registration roller pair 1039, a fixing roller 1041, a paper discharge roller 1042, a paper discharge tray 1043, and the like are provided.

  A photosensitive layer is formed on the surface of the photosensitive drum 1030. That is, the surface of the photoconductor drum 1030 is a scanned surface. Here, the photosensitive drum 1030 rotates in the direction of the arrow in FIG.

  The charging charger 1031, the developing roller 1032, the transfer charger 1033, the charge removal unit 1034, and the cleaning blade 1035 are each arranged in the vicinity of the surface of the photosensitive drum 1030. Then, with respect to the rotation direction of the photosensitive drum 1030, the charging charger 1031 → the developing roller 1032 → the transfer charger 1033 → the charge eliminating unit 1034 → the cleaning blade 1035 are arranged in this order.

  The charging charger 1031 uniformly charges the surface of the photosensitive drum 1030.

  The optical scanning device 1010 irradiates the surface of the photosensitive drum 1030 charged by the charging charger 1031 with a light beam modulated based on image information from a host device (for example, a personal computer). As a result, a latent image corresponding to the image information is formed on the surface of the photosensitive drum 1030 on the surface of the photosensitive drum 1030. The latent image formed here moves in the direction of the developing roller 1032 as the photosensitive drum 1030 rotates. The configuration of the optical scanning device 1010 will be described later.

  The toner cartridge 1036 stores toner, and the toner is supplied to the developing roller 1032.

  The developing roller 1032 causes the toner supplied from the toner cartridge 1036 to adhere to the latent image formed on the surface of the photosensitive drum 1030 to visualize the image information. Here, the latent image to which the toner is attached (hereinafter also referred to as “toner image” for the sake of convenience) moves in the direction of the transfer charger 1033 as the photosensitive drum 1030 rotates.

  Recording paper 1040 is stored in the paper feed tray 1038. A paper feed roller 1037 is disposed in the vicinity of the paper feed tray 1038, and the paper feed roller 1037 takes out the recording paper 1040 one by one from the paper feed tray 1038 and conveys it to the registration roller pair 1039. The registration roller pair 1039 temporarily holds the recording paper 1040 taken out by the paper supply roller 1037, and in the gap between the photosensitive drum 1030 and the transfer charger 1033 according to the rotation of the photosensitive drum 1030. Send it out.

  A voltage having a polarity opposite to that of the toner is applied to the transfer charger 1033 in order to electrically attract the toner on the surface of the photosensitive drum 1030 to the recording paper 1040. With this voltage, the toner image on the surface of the photosensitive drum 1030 is transferred to the recording paper 1040. The recording sheet 1040 transferred here is sent to the fixing roller 1041.

  In the fixing roller 1041, heat and pressure are applied to the recording paper 1040, whereby the toner is fixed on the recording paper 1040. The recording paper 1040 fixed here is sent to the paper discharge tray 1043 via the paper discharge roller 1042 and is sequentially stacked on the paper discharge tray 1043.

  The neutralization unit 1034 neutralizes the surface of the photosensitive drum 1030.

  The cleaning blade 1035 removes toner (residual toner) remaining on the surface of the photosensitive drum 1030. The removed residual toner is used again. The surface of the photosensitive drum 1030 from which the residual toner has been removed returns to the position of the charging charger 1031 again.

  Next, the configuration of the optical scanning device 1010 will be described.

  As shown in FIG. 2 as an example, the optical scanning device 1010 includes a light source 14, a coupling optical system 15, an aperture plate 16, a cylindrical lens 17, a reflection mirror 18, a polygon mirror 13, and a non-rotating unit for rotating the polygon mirror 13. The illustrated polygon motor, deflector side scanning lens 11a, image plane side scanning lens 11b, scanning control device (not shown), and a substantially rectangular parallelepiped housing (not shown) for housing the above components are provided. In this specification, in the XYZ three-dimensional orthogonal coordinate system, the direction along the longitudinal direction of the photosensitive drum 1030 is defined as the Y-axis direction, and the direction along the optical axis of each scanning lens (11a, 11b) is defined as the X-axis direction. explain.

  As shown in FIG. 3 as an example, the light source 14 has 40 light emitting units formed on the same substrate. Each light emitting unit is a vertical cavity surface emitting laser (VCSEL) having an oscillation wavelength of 780 nm. Here, it is assumed that each light emitting unit emits a light beam in the X-axis direction. The VCSEL has a feature that the temperature variation of the oscillation wavelength is small, and in principle, a discontinuous change in wavelength (so-called wavelength jump) does not occur.

  Returning to FIG. 2, the coupling optical system 15 converts the light beam from the light source 14 into a substantially parallel light beam.

  Here, the coupling optical system 15 includes a first lens 15a and a second lens 15b as shown in FIG. 4 as an example.

  The first lens 15a is made of glass and has a positive power. Specifically, the radius of curvature of the −X side surface (first surface) of the first lens 15a is ∞ (infinity), and the radius of curvature of the + X side surface (second surface) is −22.4 mm. It is. The refractive index of the first lens 15a is 1.5111. Further, the thickness (reference numeral D1 in FIG. 4) of the center portion of the first lens 15a is 2.6 mm.

  The second lens 15b is made of resin and has a negative power. Specifically, the radius of curvature of the −X side surface (third surface) of the second lens 15b is −150 mm, and the radius of curvature of the + X side surface (fourth surface) is ∞ (infinite). . The refractive index of the second lens 15b is 1.5239. Further, the thickness (reference numeral D3 in FIG. 4) of the center portion of the second lens 15b is 3 mm.

The absolute value of the power of the first lens 15a is 2.28 × 10 ⁻² , which is larger than the absolute value of the power of the second lens 15b, 3.5 × 10 ⁻³ .

  The light source 14 and the coupling optical system 15 are accommodated in a predetermined housing and are handled as the light source unit LU.

“Adjustment of coupling optics”
(1) The light source unit LU is set at a predetermined position with respect to the light source unit evaluation device AD1 (see FIG. 5).

(2) The first lens 15a is moved in the X-axis direction so that the light beams are emitted from the light emitting units of the light source 14 and are condensed on the evaluation image plane of the light source unit evaluation apparatus AD1 (FIG. 5). reference). The focal length of the optical system of the light source unit evaluation apparatus AD1 is 50 mm. Thereby, the state of the light beam output from the light source unit LU becomes an appropriate state, and when used in the optical scanning device, the imaging accuracy on the surface to be scanned can be improved. That is, the error of the focal position of the entire optical system is below a desired level.

(3) The light source unit LU is set at a predetermined position with respect to the light source unit evaluation device AD2 (see FIG. 6).

(4) A light beam is emitted from each light emitting unit of the light source 14, and the second lens 15b is moved in the X-axis direction so that the beam pitch on the evaluation image plane of the light source unit evaluation apparatus AD2 becomes a desired value. (See FIG. 6). The focal length of the optical system of the light source unit evaluation apparatus AD2 is 98.4 mm. Further, the lateral magnification in the desired sub-scanning direction in the optical scanning device 1010 is twice. Therefore, for example, the second lens 15b is set so that the light beams emitted from the two light emitting units located at 393 μm apart in the Z-axis direction have a beam pitch of 786 μm on the evaluation image plane of the light source unit evaluation apparatus AD2. Is moved in the X-axis direction. As a result, even if there is a certain degree of error (for example, manufacturing error) in the radii of curvature of the first lens 15a and the second lens 15b, the combined focal length of the coupling optical system 15 is set to a desired value (here, 49). .2 mm), and when used in an optical scanning device, it is possible to reduce the error of the scanning line spacing on the surface to be scanned. That is, the lateral magnification error in the direction corresponding to the sub-scanning direction of the entire optical system can be reduced to a desired level or less.

  When adjusting the position of the second lens 15b, there is a concern that the focal position of the entire optical system may change. However, the absolute value of the power of the first lens 15a is the power of the second lens 15b. Since it is larger than the absolute value, the change of the focal position is extremely small.

(5) The first lens 15a and the second lens 15b are fixed to a holding member (not shown) with an adhesive.

  Note that, for example, an ultraviolet curable resin is applied in advance to the bonding surfaces of the first lens 15a and the second lens 15b, and after the position is determined, the ultraviolet curable resin is irradiated with ultraviolet rays to thereby form the first lens 15a. The second lens 15b may be fixed to the holding member. In this case, high positional accuracy can be obtained even if the process is simplified.

  Here, the distance (symbol D0 in FIG. 4) between the light source 14 and the first lens 15a was 51.1 mm. The distance between the first lens 15a and the second lens 15b (symbol D2 in FIG. 4) was 12.4 mm.

  The light source unit LU adjusted in this way is set at a predetermined position in a housing (not shown) of the optical scanning device 1010.

  Here, the holding member in which the first lens 15 a and the second lens 15 b are held in a predetermined positional relationship is integrated with the holding member that holds the light source 14. That is, the light source 14, the first lens 15a, and the second lens 15b are held in a predetermined positional relationship with each other by the integrated holding member.

  Returning to FIG. 2, the aperture plate 16 has an aperture and defines the beam diameter of the light beam via the coupling optical system 15.

  The cylindrical lens 17 forms an image of the light beam that has passed through the opening of the aperture plate 16 in the direction corresponding to the sub-scanning direction (here, the Z-axis direction) in the vicinity of the deflection reflection surface of the polygon mirror 13 via the reflection mirror 18. To do.

  Further, a soundproof glass 21 is disposed between the cylindrical lens 17 and the polygon mirror 13 and between the polygon mirror 13 and the deflector-side scanning lens 11a.

  The optical system arranged on the optical path between the light source 14 and the polygon mirror 13 is also called a pre-deflector optical system. In this embodiment, the pre-deflector optical system includes a coupling optical system 15, an aperture plate 16, a cylindrical lens 17, and a reflection mirror 18.

  The polygon mirror 13 has a four-sided mirror, and each mirror serves as a deflection reflection surface. The polygon mirror 13 rotates at a constant speed around an axis parallel to a direction corresponding to the sub-scanning direction (here, the Z-axis direction), and deflects the light beam from the cylindrical lens 17.

  The deflector-side scanning lens 11 a is disposed on the optical path of the light beam deflected by the polygon mirror 13.

  The image plane side scanning lens 11b is disposed on the optical path of the light beam via the deflector side scanning lens 11a. Then, the light passing through the image surface side scanning lens 11b is irradiated on the surface of the photosensitive drum 1030, and a light spot is formed. This light spot moves in the longitudinal direction of the photosensitive drum 1030 as the polygon mirror 13 rotates. That is, the photoconductor drum 1030 is scanned. The moving direction of the light spot at this time is the “main scanning direction”.

  The optical system arranged on the optical path between the polygon mirror 13 and the photosensitive drum 1030 is also called a scanning optical system. In the present embodiment, the scanning optical system includes a deflector side scanning lens 11a and an image plane side scanning lens 11b.

  A dustproof glass 22 is disposed between the image side scanning lens 11b and the photosensitive drum 1030.

  As apparent from the above description, in the optical scanning device 1010 according to the present embodiment, the coupling optical system 15 causes the lateral magnification error and the focus position error in the direction corresponding to the sub-scanning direction of the entire optical system to be Both are adjusted to be small.

  Further, the adjustment method of the present invention is implemented in the above-mentioned “adjustment of coupling optical system”.

  As described above, according to the optical scanning device 1010 according to the present embodiment, the light source 14 in which a plurality of light emitting units are two-dimensionally arranged and the coupling optical system 15 arranged on the optical path of the light beam from the light source 14 are provided. A pre-deflector optical system, a polygon mirror 13 for deflecting the light beam from the pre-deflector optical system, and a scanning optical system for condensing the light beam from the polygon mirror 13 on the surface of the photosensitive drum 1030. .

  Then, the coupling optical system 15 is adjusted so that the lateral magnification error in the direction corresponding to the sub-scanning direction of the entire optical system of the optical scanning device 1010 is reduced.

  Accordingly, the scanning line interval on the surface of the photosensitive drum 1030 can be made uniform with high accuracy without using an expensive optical element, and as a result, scanning with a plurality of light beams can be performed without increasing the cost. It becomes possible to carry out with high accuracy.

  In addition, since the first lens 15a of the coupling optical system 15 is made of glass and the second lens 15b is made of resin, as shown in FIG. 7 as an example, both are made of glass. The change in the focal position of the entire optical system due to the temperature change can be reduced.

  Further, since the light source 14, the first lens 15a, and the second lens 15b are held in a predetermined positional relationship with each other by the integrated holding member, their positional relationship due to an assembly error or a temperature change. Can be suppressed. As a result, it is possible to further reduce optical characteristics (especially changes in focal position) and beam spacing.

  In addition, the laser printer 1000 according to the present embodiment includes the optical scanning device 1010 that can accurately perform scanning with a plurality of light beams without incurring an increase in cost, and as a result, increase in cost. A high-quality image can be formed without inviting.

  In the “adjustment of the coupling optical system” of the above embodiment, as shown in FIG. 8 as an example, the light beam output from the light source unit LU is divided into two by a half mirror or the like, and one of them is a light source unit evaluation apparatus AD1. May be input to the light source unit evaluation apparatus AD2.

  Further, in the “adjustment of the coupling optical system” in the above embodiment, the case where the lateral magnification in the direction corresponding to the sub-scanning direction is adjusted after adjusting the focal position is described, but the present invention is not limited to this. For example, as shown in FIG. 9A, the distance between the first lens 15a and the second lens 15b (as shown in FIG. 9A) so that the beam pitch on the evaluation image plane of the light source unit evaluation apparatus AD2 becomes a desired value. After adjusting the symbol D2) in FIG. 4, the first lens 15a and the second lens 15a and the second lens are converged as shown in FIG. 9B so that each light beam is condensed on the evaluation image plane of the light source unit evaluation apparatus AD1. The coupling optical system 15 may be moved in the X-axis direction while keeping the distance D2 of the lens 15b at the adjusted distance.

  Note that when moving the coupling optical system 15, there is a concern about a change in lateral magnification in a direction corresponding to the sub-scanning direction. Since it is larger than the absolute value, the change in lateral magnification in the direction corresponding to the sub-scanning direction is extremely small.

  Moreover, although the said embodiment demonstrated the case where the 1st lens 15a was arrange | positioned in the position near the light source 14 rather than the 2nd lens 15b in the coupling optical system 15, it is limited to this. Instead, the second lens 15b may be disposed closer to the light source 14 than the first lens 15a, as shown in FIG. 10 as an example.

  Moreover, although the said embodiment demonstrated the case where the number of the light emission parts of a light source was 40, this invention is not limited to this. In short, it is sufficient that a plurality of light emitting units are two-dimensionally arranged.

  In the above embodiment, the case of the laser printer 1000 as the image forming apparatus has been described. However, the present invention is not limited to this. In short, an image forming apparatus provided with the optical scanning device 1010 can form a high-quality image.

  For example, an image forming apparatus that includes the optical scanning device 1010 and that directly irradiates laser light onto a medium (for example, paper) that develops color with laser light may be used.

  Further, an image forming apparatus using a silver salt film as the image carrier may be used. In this case, a latent image is formed on the silver salt film by optical scanning, and this latent image can be visualized by a process equivalent to a developing process in a normal silver salt photographic process. Then, it can be transferred to photographic paper by a process equivalent to a printing process in a normal silver salt photographic process. Such an image forming apparatus can be implemented as an optical plate making apparatus or an optical drawing apparatus that draws a CT scan image or the like.

  Further, even an image forming apparatus that forms a multi-color image can form a high-definition image by using an optical scanning device that supports color images.

  For example, as shown in FIG. 11, a tandem color machine 1500 corresponding to a color image and including a plurality of photosensitive drums may be used. The tandem color machine 1500 includes a black (K) photosensitive drum K1, a charger K2, a developing unit K4, a cleaning unit K5, a transfer charging unit K6, a cyan (C) photosensitive drum C1, a charging unit. A developing unit C2, a developing unit C4, a cleaning unit C5, a transfer charging unit C6, a magenta (M) photosensitive drum M1, a charging unit M2, a developing unit M4, a cleaning unit M5, and a transfer charging unit M6; A yellow (Y) photosensitive drum Y1, a charger Y2, a developing device Y4, a cleaning unit Y5, a transfer charging unit Y6, an optical scanning device 1010A, a transfer belt 1580, a fixing unit 1530, and the like are provided. .

  The optical scanning device 1010A includes a light source for black, a light source for cyan, a light source for magenta, and a light source for yellow. The optical scanning device 1010A has a pre-deflector optical system and a scanning optical system equivalent to the optical scanning device 1010 corresponding to each light source. The light beam from the black light source is applied to the photosensitive drum K1 via the black pre-deflector optical system and the scanning optical system, and the light beam from the cyan light source is applied to the cyan pre-deflector optical system and the scanning optical system. The light beam from the light source for magenta is irradiated to the photosensitive drum C1 through the system, and the light beam from the light source for yellow is irradiated to the photosensitive drum M1 through the pre-deflector optical system and the scanning optical system for magenta. Is irradiated to the photosensitive drum Y1 via the yellow pre-deflector optical system and the scanning optical system.

  Each photosensitive drum rotates in the direction of the arrow in FIG. 11, and a charger, a developer, a transfer charging unit, and a cleaning unit are arranged in the order of rotation. Each charger uniformly charges the surface of the corresponding photosensitive drum. The surface of the photosensitive drum charged by the charger is irradiated with light by the optical scanning device 1010A, and an electrostatic latent image is formed on the photosensitive drum. Then, a toner image is formed on the surface of the photosensitive drum by the corresponding developing device. Further, the toner images of the respective colors are transferred onto the recording paper by the corresponding transfer charging means, and finally the image is fixed on the recording paper by the fixing means 1530.

  The optical scanning device 1010A has a pre-deflector optical system equivalent to the optical scanning device 1010 corresponding to each light source. Therefore, the optical scanning device 1010A can be used on the surface of each photosensitive drum without using an expensive optical element. The scanning line interval can be made uniform with high accuracy, and as a result, it is possible to perform scanning with a plurality of light beams with high accuracy without increasing the cost.

  In addition, the tandem color machine 1500 includes the optical scanning device 1010A that can perform scanning with a plurality of light beams with high accuracy without incurring high costs, and as a result, without increasing costs, A quality image can be formed.

  In this tandem color machine 1500, instead of the optical scanning device 1010A, a black optical scanning device, a cyan optical scanning device, a magenta optical scanning device, and a yellow optical scanning device may be used. In short, each optical scanning device only needs to have a pre-deflector optical system equivalent to the optical scanning device 1010.

The method for producing an optical scanning device of the present invention is suitable for producing an optical scanning device capable of performing scanning with a plurality of light beams with high accuracy without incurring an increase in cost .

It is a figure for demonstrating schematic structure of the laser printer which concerns on one Embodiment of this invention. It is a figure which shows schematic structure of the optical scanning device in FIG. It is a figure for demonstrating the light source in FIG. It is a figure for demonstrating the coupling optical system in FIG. It is FIG. (1) for demonstrating the adjustment method of a coupling optical system. It is FIG. (2) for demonstrating the adjustment method of a coupling optical system. It is a figure for demonstrating correction | amendment of the curvature-of-field change resulting from a temperature change. It is a figure for demonstrating the modification 1 of the adjustment method of a coupling optical system. FIG. 9A and FIG. 9B are diagrams for explaining a modification example 2 of the adjustment method of the coupling optical system. It is a figure for demonstrating the modification of a coupling optical system. It is a figure for demonstrating schematic structure of a tandem color machine. It is a figure for demonstrating the adjustment by (gamma) rotation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11a ... Deflector side scanning lens (a part of scanning optical system), 11b ... Image surface side scanning lens (a part of scanning optical system), 14 ... Light source, 15 ... Coupling optical system (one optical system before deflector) Part), 15a ... first lens (first optical element), 15b ... second lens (second optical element), 17 ... cylindrical lens (part of optical system before deflector), 1000 ... laser printer (image) Forming device), 1010... Optical scanning device, 1010A... Optical scanning device, 1030... Photosensitive drum (image carrier), 1500 .. tandem color machine (image forming device), K1, C1, M1, Y1. Image carrier).

Claims (8)

A method of producing an optical scanning device that scans a scanned surface in a main scanning direction with a plurality of light beams,
The optical scanning device includes a light source in which a plurality of light emitting units are two-dimensionally arranged , a first optical element having a positive power, and a second optical element having a negative power, on an optical path of a light beam from the light source. A pre-deflector optical system disposed; a deflector that deflects the light beam that has passed through the pre-deflector optical system; and a scanning optical system that condenses the light beam deflected by the deflector on the surface to be scanned. The absolute value of the power of the first optical element is greater than the absolute value of the power of the second optical element,
Outputting a plurality of light fluxes from the light source and irradiating the evaluation image surface corresponding to the scanned surface;
Adjusting the distance between the first optical element and the second optical element so that the beam pitch on the evaluation image plane has a desired value;
The first optical element and the second optical element are kept at the adjusted distance so that a plurality of light beams from the light source are condensed on the evaluation image plane. And a step of moving two optical elements in the direction of the optical axis. A method of producing an optical scanning device that scans a scanned surface in a main scanning direction with a plurality of light beams,
The optical scanning device includes a light source in which a plurality of light emitting units are two-dimensionally arranged , a first optical element having a positive power, and a second optical element having a negative power, on an optical path of a light beam from the light source. A pre-deflector optical system disposed; a deflector that deflects the light beam that has passed through the pre-deflector optical system; and a scanning optical system that condenses the light beam deflected by the deflector on the surface to be scanned. The absolute value of the power of the first optical element is greater than the absolute value of the power of the second optical element,
Outputting a plurality of light fluxes from the light source and irradiating the evaluation image surface corresponding to the scanned surface;
Moving the first optical element in the direction of the optical axis so that a plurality of light beams from the light source are collected on the evaluation image plane;
And a step of moving the second optical element in the optical axis direction so that a beam pitch on the evaluation image plane becomes a desired value.   The method for producing an optical scanning device according to claim 1, wherein the plurality of light emitting units are two-dimensionally arranged.   The method of manufacturing an optical scanning device according to claim 3, wherein the plurality of light emitting units are 40 or more light emitting units.   5. The method of producing an optical scanning device according to claim 1, wherein the light beams emitted from the first optical element and the second optical element are parallel light beams. 6.   6. The light source, the first optical element, and the second optical element are held by an integrated holding member in a predetermined positional relationship with each other. A production method of the optical scanning device described. The material of the first optical element and the material of the second optical element are different from each other.
The change in the focal position of the entire optical system due to a temperature change is further suppressed by the first optical element and the second optical element, according to any one of claims 1 to 6. A production method of the optical scanning device described.   The method for producing an optical scanning device according to claim 1, wherein the absolute value of the power of the first optical element is larger than the absolute value of the power of the second optical element.

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