JP2003098457A - Optical scanner for image forming apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanner which does not cause the positional deviation of dots (deviation of scanning position) in a scanning direction without making accuracy of a plastic optical element extremely high. SOLUTION: The plastic optical element 4 is constituted of a first layer of the plastic optical element and a plastic optical element laminated in a subscanning direction on the first layer of plastic optical element, and a second and succeeding layers of plastic optical elements laminated in the subscanning direction are adjusted and fixed so that scanning time corresponding to the second and succeeding layers of plastic optical elements may be nearly equal to that of the first layer of plastic optical element by the positional adjustment of the second and succeeding layers of plastic optical elements in the scanning direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device of an image forming apparatus having an optical scanning system such as a laser type digital copying machine, a laser printer, a facsimile machine and the like, and an image forming apparatus equipped with the optical scanning device.

[0002]

2. Description of the Related Art An image forming apparatus for guiding each beam emitted from a plurality of laser beams onto a photoconductor through a deflecting means and an image forming means and forming an image on the photoconductor according to image information. There is an optical scanning device.

In recent years, in order to cope with higher speed and higher image quality of image forming apparatuses, four photoconductor drums are arranged in the conveying direction of output paper, and the beams corresponding to the respective photoconductor drums are simultaneously exposed to light. Different colors (yellow, magenta, cyan,
A digital copying machine or a laser printer, which sequentially transfers images developed by a (black) developing device and forms a color image by superposing them, has been put into practical use.

When performing optical scanning with such an image output machine,
Although a plurality of scanning means are used, a large space is required for arranging the scanning means, and the size of the entire apparatus becomes large. Therefore, as disclosed in Japanese Patent Application Laid-Open No. 4-127115, a plurality of scanning means are used. A method has been proposed in which a beam is incident on a single deflector to be scanned, and imaging lenses are stacked and arranged.

Further, in Japanese Patent Application Laid-Open No. 10-148777, in order to make up for the drawbacks of Japanese Patent Application Laid-Open No. 4-127115, a plurality of beams are made incident on a single deflector and scanned, and the respective corresponding photoconductors are scanned. A method has been proposed in which an image forming unit for forming an image is provided for each beam, and the optical elements forming the image forming unit are layered in the sub-scanning direction so as to be integrally formed.
By stacking the optical elements in layers in the sub-scanning direction to form an integral structure, the interval at which the deflecting means (polygon mirrors) are stacked can be shortened, or a single polygon mirror can also serve as a polygon mirror. The load of the motor for rotating can be reduced, and the size can be reduced.

[0006]

Means for integrally forming optical elements constituting the above-mentioned image forming means in a layered manner in the sub-scanning direction are a means for fixing the optical elements in a layered manner and a layered manner. There is a means for integrally forming the optical element laminated on the above with resin and fixing it to the housing.

When fixing optical elements by stacking them in layers, first of all, there are the following problems in terms of optical characteristics of the optical element itself: i) mounting reference pin of the optical element, or mounting error with respect to the housing caused by processing error of the reference surface, ii) Inconsistency in scanning time caused by deviation of the center of curvature of the entrance and exit sides in the scanning direction due to assembly error of the entrance and exit side mirror surface piece in the mold, and iii) processing error in the entrance and exit side mold mirror surface shape. There is a problem of uniformity.

In the case of stacking in layers, the non-uniform scanning time for each layer (single body) caused by the above i) to iii) causes non-uniform scanning time between the layers, and the optical elements of each layer have different colors (Y). , C, M, Bk), the image writing apparatus for each color usually uses the beam detector provided outside the image forming area and at one end on one side of the scanning line. The non-uniformity of the scanning time between the layers appears as an image defect called dot position shift (scan position shift) in the scanning direction between the colors.

Further, when the optical element is molded by a multi-cavity mold, the non-uniformity of the scanning time between the respective layers caused by the above i) to iii) is further increased by including the variation between the cavities. .

In addition to the same problems as when the optical elements laminated in layers are integrally molded with resin and fixed to the housing, as a problem at the time of molding, a thick optical element has a long cooling time at the time of molding. As a result, the production efficiency is lowered and the cooling time is lengthened, so that the convection time of the resin in the cylinder is increased and foreign matters are easily generated.

[0011] As a problem at the time of joining, production cost increases due to an increase in the irradiation power or irradiation time of ultraviolet rays when the case is ultraviolet-cured and adhered to the housing, and the optical element itself accompanying the increase in irradiation power or irradiation time of ultraviolet rays. Due to the rise in temperature, the shape and internal composition of the optical element change.

The above i) has not been a problem so far.
Problems related to (3) to (iii) are prominent problems in the recent trend toward colorization, speedup, and high image quality of image forming apparatuses, that is, optical scanning apparatuses.

Therefore, an object of the present invention is to provide an optical scanning device and an image forming apparatus which do not cause dot position deviation (scanning position deviation) in the scanning direction without extremely increasing the precision of the plastic optical element. It is in.

[0014]

In order to achieve the above-mentioned object, the invention of claim 1 emits a plurality of laser light sources,
In an optical scanning device of an image forming apparatus for forming an image according to image information by scanning a beam condensed through an optical deflector and a plastic optical element laminated in the sub-scanning direction on each photoconductor. , The plastic optical element is a state in which the plastic optical element is abutted against an optical axis reference provided in advance in a housing, and a beam emitted from a corresponding laser light source and condensed through the optical deflector and the plastic optical element is a photoconductor. The first-layer plastic optical element is made to scan on a position, and is adjusted and fixed so that the scanning time on each of the left and right sides of the scanning line and in a specific range becomes substantially equal by position adjustment in the scanning direction of the plastic optical element. And a plastic optical element laminated on the first layer plastic optical element in the sub-scanning direction. For the plastic optical elements of the second and subsequent layers stacked on the first plastic layer, the scanning time corresponding to the plastic optical elements of the second and subsequent layers is adjusted by adjusting the position of the plastic optical elements of the second and subsequent layers in the scanning direction. An optical scanning device of an image forming apparatus, characterized in that the optical scanning device is adjusted and fixed so as to be substantially equal to the optical element.

According to a second aspect of the present invention, the optical scanning device of the image forming apparatus according to the first aspect is characterized in that the plastic optical elements are arranged to face each other with the optical deflector interposed therebetween. Is.

According to a third aspect of the present invention, an abutting reference in the scanning direction for abutting the plastic optical element of the first layer is provided in advance in the housing, and the plastic optical element of the first layer is placed in the scanning direction. The optical scanning of the image forming apparatus according to claim 1, wherein the scanning time of the plastic optical element of the first layer is fixed so as to be equal in a state of being abutted against an abutting reference. It is a device.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the fixing means of the plastic optical element is an adhesive fixing, and the adhesive is a photocurable adhesive. It is an optical scanning device.

According to a fifth aspect of the present invention, the optical scanning device of the image forming apparatus according to the fourth aspect is characterized in that all the plastic optical elements are preliminarily coated with an adhesive and are simultaneously adhered. .

The invention of claim 6 is an image forming apparatus comprising the optical scanning device of the image forming apparatus according to any one of claims 1 to 5.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic plan view of an optical scanning device according to a first embodiment of the present invention, and FIG. 2 is a schematic side view of the same.

As shown in FIG. 1, the optical scanning device according to the first embodiment includes a housing 1, a plurality of laser light sources 2 attached to the housing 1, and a beam emitted from the laser light source 2. The optical deflector 3 for deflecting the light and the plastic optical element 4 for condensing the beam deflected by the optical deflector 3 onto the photosensitive member position 7 via the folding mirror 6 are provided. In addition,
The light source unit, which is a laser light source in the present specification, may include a collimator lens and a cylindrical lens, in addition to the semiconductor laser serving as the laser emitting section.

As shown in FIG. 2, laser light sources 2a and 2b are provided.
Is composed of a plurality of layers in the sub-scanning direction (direction orthogonal to the paper surface in FIG. 1), and in the present embodiment, is composed of two layers including a first layer laser light source 2a and a second layer laser light source 2b. Further, the plastic optical element 4 has a plurality of layers corresponding to the respective laser light sources 2a and 2b, and in the present embodiment, the plastic optical element 4a of the first layer and the plastic optical element 4 of the second layer.
It is composed of two layers b.

In this optical scanning device, the beams emitted from a plurality of laser light sources 2 are deflected by an optical deflector 3 and plastic optical elements 4a and 4b are stacked corresponding to the respective laser light sources 2a and 2b. The respective photoconductors 12, 1
3 is an optical scanning device of an image forming apparatus that forms an image on the photoconductor 3 and scans on the photoconductors 12 and 13 to form an image according to image information.

FIG. 3 shows an optical scanning device 1 according to the first embodiment.
FIG. 4 is a schematic plan view showing position adjustment in the plastic optical element of the layer, and FIG. 4 is a schematic side view of the same. FIG. 5 is a diagram for explaining a scanning time of a beam condensed by the first and second layers of plastic optical elements of the optical scanning device according to the first embodiment.

In the optical scanning device as shown in FIGS. 1 and 2, the plastic optical element 4a of the first layer, which constitutes the laminated plastic optical element 4, has the casing 1
The beam emitted from the corresponding laser light source 2a in a state of abutting against the optical axis reference 5 provided in advance on the photoconductor position 7 is condensed through the optical deflector 3 and the plastic optical elements 4a and 4b. Scan.

As shown in FIGS. 3 and 4, the scanning time in the scanning direction β of the plastic optical element 4 is adjusted on the left and right sides of the scanning line measured by the beam detector 37 arranged at the photoconductor position and in the specific range. Is adjusted and fixed so as to be substantially even.

As shown in FIG. 5, for the second and subsequent layers stacked in the sub-scanning direction, the scanning time measured in the same manner is almost equal to that of the first layer by adjusting the position of the plastic optical element 4b in the scanning direction. Are sequentially adjusted and fixed so that This makes it possible to reduce the non-uniformity of the scanning time for each layer of the plastic optical element and between the layers, and by performing this adjustment, the dots in the scanning direction can be obtained without extremely increasing the accuracy of the plastic optical element. The positional deviation (scanning positional deviation) can be reduced, and in addition, this adjusting method is effective even when the wavelengths of the laser light sources 2a and 2b are different. Further, since the adjustment and fixing process is performed by mounting all the elements other than the plastic optical element, it is possible to guarantee the unit in consideration of the processing accuracy of all the elements.

Next, the case where an fθ lens is used as an example of the plastic optical element provided in the optical scanning device of the first embodiment will be described. FIG. 13 is a perspective view showing a one-layer fθ lens as an example of a plastic optical element.
FIG. 4 is a diagram showing the adhesion of the f.theta. Lens which is the first layer plastic optical element by the ultraviolet curing adhesive, and FIG. 15 is a diagram showing the adhesion of the f.theta. Lens which is the second layer plastic optical element by the ultraviolet curing adhesive. Is.

Next, an embodiment of an optical scanning device in which a single-layer fθ lens 44 (see FIG. 13), which is a component of an optical scanning device of a laser beam printer, is layered and coupled to a casing in layers will be described. First, as shown in FIGS. 3 and 4,
A laser light source 2, a light source unit such as a cylindrical lens, an optical deflector 3, etc., and a housing 1 on which all elements other than the fθ lens 44 are mounted are scanned on a photosensitive member position 7 (see FIG. 1) of the housing 1 and are scanned. A pair of beam detectors 37 is arranged on the left and right of the line, and the beam detectors 37 are set on a jig (not shown).

Next, as shown in FIG. 14, fθ of the first layer
The ultraviolet curable adhesive 45 is applied to the housing portion corresponding to the center of the lens 44a, and the fθ lens 44a is moved from the abutting direction α in the optical axis direction to the housing 1 with the adhesive surface facing downward.
The optical axis reference 5 (see FIG. 3). Next, a beam emitted from the corresponding laser light source 2a (see FIG. 4) and condensed through the optical deflector 3 (see FIGS. 3 and 4) and the fθ lens 44a is scanned on the photosensitive member position.

As shown in FIG. 3, right and left of the scanning line,
Scanning time (Δt1a → b, Δt1c →
The difference (= Δt1a → b−Δt1c → d) of d) is calculated,
The fθ lens 44a is positioned at a position in the scanning direction so that the amount thereof is minimized, and as shown in FIG.

When the fθ lens and the housing have different linear expansion coefficients, the central portion of the fθ lens is joined as shown in FIG. It is possible to prevent the generation of stress.
By the above steps, the nonuniformity of the scanning time of the f-th lens 44a of the first layer is reduced, and thereafter, the position adjustment is performed on the basis of this scanning time in all the laminated lenses.

With respect to the second-layer fθ lens 44b laminated in the sub-scanning direction, the ultraviolet curable adhesive 45 is applied to the first-layer fθ lens 44a, and the adhesive surface faces downward with the optical axis. The fθ lens 4 is stacked in layers while abutting against the reference 5 (see FIG. 3), similarly to the fθ lens 44a of the first layer.
The beam condensed by 4b is scanned on the photosensitive member position.

As shown in FIG. 5, right and left of the scanning line,
Scanning time (Δt2a → b, Δt2c →
Regarding the difference from the scanning time of the first layer in d), an absolute value is calculated and added (= | Δt1a → b−Δt2a → b | +
| Δt1c → d−Δt2c → d |), and the fθ lens 44b is positioned at a position in the scanning direction such that the amount thereof is minimized, and as shown in FIG.

By minimizing the difference, fθ of the first layer
The nonuniformity of the scanning time between the lens 44a and the fθ lens 44b of the second layer is reduced, and the image defect such as dot position shift in the scanning direction (scan position shift) can be reduced. Also, adjustments with all elements other than the fθ lens mounted,
In addition, since it is a fixing process, it is possible to guarantee the unit taking into consideration the processing accuracy of all elements. Here, for the lens adjustment of the n-th layer, the sum of absolute values of the difference in scanning time from the first layer (= | Δt1a → b−Δtna → b | + | Δt1c →
It is also noted that the calculation of d-Δtnc → d |) is performed.

By using a photo-curing adhesive, for example, an ultraviolet-curing adhesive in a series of steps, the timing of curing of the adhesive can be controlled. Therefore, after accurate positioning, the curing light, For example, it was possible to irradiate with ultraviolet rays and to superimpose them in a layered manner on the housing with higher placement accuracy and to join them.

FIG. 6 is a schematic plan view showing a modification of the position adjustment in the first-layer plastic optical element of the optical scanning device according to the first embodiment.

As shown in FIG. 6, in the optical scanning device of the first embodiment, the plastic optical element 4 of the first layer is abutted against the optical axis reference 5a and the scanning direction reference 5b provided in advance in the housing 1. Therefore, the position adjustment in the scanning direction of the plastic optical element of the first layer is omitted, and for the second and subsequent layers, the scanning time measured by the same means as in the first layer is adjusted by the position adjustment in the scanning direction of the plastic optical element. You may make it adjust and fix sequentially so that it may become substantially equal to a 1st layer.

Also in this optical scanning device, it is possible to reduce the non-uniformity of the scanning time between the layers of the plastic optical element 4, and by adjusting the layers, the precision of the plastic optical element 4 is extremely increased. It is possible to reduce the dot position deviation (scanning position deviation) in the scanning direction without increasing. Further, since the adjustment and fixing process is performed by mounting all the elements other than the plastic optical element, it is possible to guarantee the unit in consideration of the processing accuracy of all the elements.

At the time of bonding, the use of a photo-curing adhesive makes it possible to control the timing of curing of the adhesive, which facilitates assembly and adjustment, and an extra adjustment mechanism and adjustment mechanism for each optical element. No adjusting means is required. However, in this case, of course, it is necessary to mold the transparent material. Furthermore, at the time of bonding, an adhesive is applied in advance to the bonding surface between the plastic optical element and the housing, and the bonding surface between the plastic optical elements. By adjusting and fixing it, the working time can be shortened.

FIG. 7 is a schematic plan view of an optical scanning device for forming an image according to the second embodiment of the present invention, and FIG. 8 is a schematic side view of the same. As shown in FIG. 7, the optical scanning device according to the second embodiment includes a housing 1, a plurality of laser light sources 15 and 16 attached to the housing 1, and a beam emitted from the laser light sources 15 and 16. Optical deflector 17 for deflecting light and optical deflector 1
Each of the beams deflected by 7 is folded back to a mirror 2
1 and 22, and plastic optical elements 18 and 19 for converging light onto the photoconductor positions 23 and 24, respectively.

As shown in FIG. 8, laser light sources 15 and 16 are provided.
Is composed of a plurality of layers in the sub-scanning direction (the direction orthogonal to the paper surface in FIG. 7), and in the present embodiment, is composed of two layers of the first layer laser light sources 15a and 16a and the second layer laser light sources 15b and 16b. . Further, the plastic optical element 18 corresponds to each of the laser light sources 15a and 15b, and the plastic optical element 18a and the second layer of the plastic optical elements 18a and 2b in the present embodiment are provided.
It is composed of two layers of the plastic optical element 18b of the first layer. Similarly, the plastic optical element 19
A plurality of layers, that is, the first layer plastic optical element 19 in the present embodiment, respectively corresponding to the respective laser light sources 16a and 16b.
It is composed of two layers consisting of a and the second layer plastic optical element 19b.

This optical scanning device includes a plurality of laser light sources 18
Beams emitted from (18a, 18b) and 19 (19a, 19b) are deflected by the same optical deflector 17, and are arranged in a form corresponding to each laser light source and facing each other with the optical deflector 17 interposed therebetween. Laminated plastic optical element 18 (18
a, 18b) and 19 (19a, 19b), the respective photoconductors 23 (23a, 23b), 24 (24a, 24)
b) form an image on the photoconductors 23 (23a, 23b), 2
4 (24a, 24b) is an optical scanning device of an image forming device that forms an image in accordance with image information by scanning.

FIG. 9 shows an optical scanning device 1 according to the second embodiment.
FIG. 10 is a schematic plan view showing position adjustment in the plastic optical element of the layer, and FIG. 10 is a schematic side view of the same. FIG. 11 is a diagram for explaining the scanning time of the beam focused by the plastic optical elements of the first and second layers of the optical scanning device according to the second embodiment.

In the optical scanning device as shown in FIGS. 7 and 8 for the purpose of forming an image, the plastic optical elements 18a and 19a of the first layer constituting the laminated plastic optical elements 18 and 19 are the casings. A beam emitted from a corresponding laser light source in a state of abutting against an optical axis reference 20 provided in advance on the body 1 and condensed through the optical deflector 17 and the plastic optical elements 18a and 19a is located at the photoconductor position 2.
Scan on 3, 24.

As shown in FIGS. 9 and 10, the scanning time on the right and left sides of the scanning line measured by the beam detectors 40 and 41 arranged at the photoconductor position and in the specific range is the scanning direction of the plastic optical elements 18a and 19a. It is adjusted and fixed so that it becomes substantially even by the position adjustment with respect to β.

As shown in FIG. 11, with respect to the second and subsequent layers laminated in the sub-scanning direction and the plastic optical element arranged to face the optical deflector 17, the scanning time measured in the same manner is measured by the plastic optical element. By adjusting the positions of the elements 18b and 19b in the scanning direction, the elements 18b and 19b are sequentially adjusted and fixed so as to be substantially equal to the first layer. This makes it possible to reduce the non-uniformity of the scanning time for each layer of the plastic optical element and between the layers. By performing this adjustment, the precision of the plastic optical element is not extremely increased, and the non-uniformity of the image forming apparatus is improved. Dot position shift in the scanning direction between each color (scan position shift), which is a problem on the image
In addition, this adjustment method is effective even when the wavelengths of the laser light sources 2a and 2b are different.
Further, since the adjustment and fixing process is performed by mounting all the elements other than the plastic optical element, it is possible to guarantee the unit in consideration of the processing accuracy of all the elements.

Next, a single-layer fθ lens (FIG. 13) which is a component of the optical scanning device of the color laser beam printer.
An embodiment relating to an optical scanning device in which the components are stacked and coupled to the housing will be described.

First, as shown in FIG. 9 and FIG. 10, a case in which all elements other than the fθ lens, such as laser light sources 15 and 16, a light source unit such as a cylindrical lens, an optical deflector 17 and the like are mounted, The jig is set on the photosensitive member position, and a pair of beam detectors is arranged on the left and right of the scanning line.

Next, as shown in FIG. 14, an ultraviolet-curable adhesive is applied to the housing portion corresponding to the central portion of the lens of the first layer, and the lens is housing with the adhesive surface facing downward. The beam is made to strike the optical axis reference of the body, emitted from the corresponding laser light source, and condensed through the optical deflector and the fθ lens to scan on the photoconductor position.

As shown in FIG. 9, right and left of the scanning line,
Scanning time (Δt1a → b, Δt1c →
The difference (= Δt1a → b−Δt1c → d) of d) is calculated,
The lens is positioned at a position in the scanning direction so that the amount thereof is minimized, and as shown in FIG.

When the fθ lens and the housing have different linear expansion coefficients, as in the first embodiment, as shown in FIG.
By joining the central portion of the fθ lens, it is possible to prevent the occurrence of stress between the lens and the housing due to a change in ambient temperature. The non-uniformity of the scanning time of the lens of the first layer is reduced by the above steps, and thereafter, the position adjustment is performed on the basis of this scanning time in all the laminated lenses.

With respect to the second-layer fθ lens laminated in the sub-scanning direction, an ultraviolet curable adhesive is applied to the first-layer fθ lens 44a, and the adhesive surface faces downward with the optical axis reference 20. (See FIG. 9) The layers are stacked in layers while abutting against each other (see FIG. 9), and the beam condensed by the fθ lens of the second layer is scanned on the photoconductor in the same manner as the fθ lens of the first layer.

As shown in FIG. 11, the scanning time (Δt2a → b, Δt2) on the left and right of the scanning line, respectively.
The absolute value of the difference between c → d) and the first layer is calculated and added (= | Δt1a → b−Δt2a → b | + | Δt1
c → d−Δt2c → d |), the lens is positioned at a position in the scanning direction such that the amount thereof is minimized, and ultraviolet rays are irradiated to bond the lenses as shown in FIG.

By minimizing the difference, the nonuniformity of the scanning time of the first layer and the second layer is reduced, and in particular, the optical element of each layer corresponds to each color (Y, C, M, Bk). In the image forming apparatus, since the timing for writing the image of each color is normally set by the beam detector provided outside the image forming area and at one end on one side of the scanning line, the nonuniformity of the scanning time between the layers is reduced. By doing so, it is possible to reduce an image defect such as a dot position shift (scanning position shift) in the scanning direction between the colors.

Further, since the adjustment and fixing process is performed by mounting all the elements other than the fθ lens, it is possible to guarantee the unit in consideration of the processing accuracy of all the elements. Here, regarding the lens adjustment of the n-th layer, the sum of absolute values of the difference in scanning time from the first layer (= | Δt1a → b−Δtna → b |
It is also noted that + | Δt1c → d−Δtnc → d |) is calculated.

Similarly, with respect to the lens disposed so as to face the optical deflector, a UV curable adhesive is applied to the housing and the adhesive surface faces downward so that the lens faces the optical deflector. While striking the optical axis reference placed in, layered,
The beam condensed by the lens is scanned on the photoconductor through the same means as the first layer, and the scanning time (ΔT1a → b, ΔT1c →
Regarding the difference from the first layer in d), an absolute value is calculated and added (= | Δt1a → b−ΔT1a → b | + | Δt1c →
d-ΔT1c → d |) (FIG. 11), the lens is positioned at a position in the scanning direction such that the amount thereof is minimized, and ultraviolet rays are irradiated to bond the lenses.

As in the case of stacking in layers, by minimizing the difference, the nonuniformity of the scanning time of the lenses arranged so as to face the first layer and the optical deflector is reduced, and in particular, In an image forming apparatus in which the optical element of each layer corresponds to each color (Y, C, M, Bk), usually, the timing of writing the image of each color is provided outside the image forming area and at one end on one side of the scanning line. Since the above-described beam detector is used, it is possible to reduce non-uniformity of the scanning time between the respective layers, and thus it is possible to reduce an image defect such as a dot position deviation (scanning position deviation) in the scanning direction between the colors. Also,
Since the adjustment and fixing process is performed by mounting all elements other than the lens, it is possible to guarantee the unit in consideration of the processing accuracy of all the elements.

Similar to the optical scanning device of the first embodiment, by using an ultraviolet curing adhesive in a series of steps, the curing timing of the adhesive can be controlled, so that accurate positioning is performed. After that, it was possible to irradiate with ultraviolet rays and to superimpose them on the housing in a layered manner with higher placement accuracy. It is considered that the above-described fixing method with higher placement accuracy provides a higher precision optical scanning device and contributes to colorization, speedup, and high image quality of the laser beam printer.

FIG. 12 is a schematic plan view showing a modification of the position adjustment in the first-layer plastic optical element of the optical scanning device according to the second embodiment.

As shown in FIG. 12, in the optical scanning device according to the second embodiment, the first layer is abutted against the optical axis reference and the reference in the scanning direction which are provided in advance in the housing, so that the first layer of plastic optical Omitting the position adjustment in the scanning direction of the element,
For the second and subsequent layers and for the plastic optical element that is arranged so as to face the optical deflector, the scanning time measured by the same means as the first layer is adjusted by adjusting the position of the plastic optical element in the scanning direction. Also in an optical scanning device (claim 4), which is sequentially adjusted and fixed so as to be substantially equal to the eyes, it is possible to reduce the non-uniformity of the scanning time between the layers of the plastic optical element. By adjusting these layers, the dot position deviation (scanning position deviation) in the scanning direction between the colors, which is a problem on the image in the image forming apparatus, can be achieved without extremely increasing the precision of the plastic optical element. It can be reduced. Further, since the adjustment and fixing process is performed by mounting all the elements other than the plastic optical element, it is possible to guarantee the unit in consideration of the processing accuracy of all the elements.

At the time of bonding, by using a photo-curing adhesive, the timing of curing the adhesive can be controlled, which facilitates assembly adjustment, and an extra adjustment mechanism and adjustment mechanism for each optical element. No adjusting means is required. However, in this case, of course, it is necessary to mold the transparent material.

Further, at the time of joining, an adhesive agent is applied in advance to the joining surface between the plastic optical element and the housing and the joining surface between the plastic optical elements, and after being layered,
By adjusting the optical axes of all plastic optical elements at the same time and fixing them, the working time can be shortened.

As described above, the beams emitted from the plurality of laser light sources and condensed through the optical deflector and the plastic optical elements layered in the sub-scanning direction are scanned on the respective photoconductors. As a result, in the optical scanning device of the image forming apparatus that forms an image according to the image information, the plastic optical element of the first layer constituting the plastic optical element is abutted against the optical axis reference provided in advance in the housing. In this state, the beam emitted from the corresponding laser light source and condensed through the optical deflector and the plastic optical element is scanned on the photosensitive member position, and the scanning time in each of the left and right scanning lines and in a specific range is By adjusting the position of the plastic optical element in the scanning direction, the plastic optical element is adjusted and fixed so as to be substantially even, and laminated in the sub-scanning direction. For the layers onward, the scanning time measured by the same means as described above was sequentially adjusted and fixed so that the scanning time of the plastic optical element was adjusted to be substantially equal to that of the first layer. Since it is an optical scanning device, it is possible to reduce the non-uniformity of the scanning time for each layer of the plastic optical element and between the layers. By performing this adjustment, the precision of the plastic optical element can be extremely increased. Therefore, the dot position deviation in the scanning direction (scan position deviation) can be reduced. Also,
Since the adjustment and fixing process is performed by mounting all the elements other than the plastic optical element, it is possible to guarantee the unit in consideration of the processing accuracy of all the elements.

In addition, a plurality of laser light sources are emitted from the plurality of laser light sources, and the plastic optical elements are stacked in layers in the optical deflector and the sub-scanning direction, or arranged so as to face the optical deflector and stacked in layers. In an optical scanning device of an image forming apparatus that forms an image according to image information by scanning a focused beam on each photoconductor, the first layer plastic optical element that constitutes the plastic optical element Is a state in which the beam is emitted from the corresponding laser light source and is focused through the optical deflector and the plastic optical element in a state in which the beam is abutted against the optical axis reference previously provided in the housing, and the beam is scanned on the photosensitive member position. , The scanning time on each of the left and right sides of the scanning line and in a specific range is substantially equalized by adjusting the position of the plastic optical element in the scanning direction. For a plastic optical element which is adjusted and fixed to the second optical layer and which is laminated in the sub-scanning direction and arranged facing the optical deflector, the scanning time measured by the same means as described above is used. The optical scanning device is characterized in that it is sequentially adjusted and fixed so as to be substantially equal to the first layer by adjusting the position of the device in the scanning direction. It is possible to reduce the non-uniformity of the scanning time, and by performing this adjustment, the dot position in the scanning direction between the colors, which is a problem on the image in the image forming apparatus, does not significantly increase the accuracy of the plastic optical element. The occurrence of misalignment (scan position misalignment) can be reduced. Further, since the adjustment and fixing process is performed by mounting all the elements other than the plastic optical element, it is possible to guarantee the unit in consideration of the processing accuracy of all the elements.

Further, the beams emitted from a plurality of laser light sources and condensed through the optical deflector and the laminated plastic optical element are scanned on the respective photoconductors to form an image according to the image information. In the optical scanning device of the image forming apparatus, the plastic optical element of the first layer forming the plastic optical element is corresponded in a state of being abutted against the optical axis reference and the scanning direction reference provided in advance in the housing. The beam emitted from the laser light source and scanned through the beam deflector and the plastic optical element onto the photosensitive member position is scanned, and the scanning line left and right respectively, and after measuring the scanning time in a specific range, is fixed, For the second and subsequent layers stacked in the sub-scanning direction, the scanning time measured by the same means as described above is set in the state of being abutted only on the optical axis reference. Since the optical scanning device is characterized in that the optical scanning device is sequentially adjusted and fixed so as to be substantially equal to the first layer by adjusting the position of the stick optical element in the scanning direction, the scanning time between the layers of the plastic optical element is adjusted. Can be reduced, and by adjusting the layers, the dot position deviation (scanning position deviation) in the scanning direction can be reduced without significantly increasing the precision of the plastic optical element. Further, since the adjustment and fixing process is performed by mounting all the elements other than the plastic optical element, it is possible to guarantee the unit in consideration of the processing accuracy of all the elements.

In addition, a plurality of laser light sources are emitted, and the optical deflector and the plastic optical elements stacked in layers in the sub-scanning direction or arranged so as to face the optical deflector and stacked in layers are interposed. In an optical scanning device of an image forming apparatus that forms an image according to image information by scanning a focused beam on each photoconductor, the first layer plastic optical element that constitutes the plastic optical element Is a photoconductor, which is a beam emitted from a corresponding laser light source and condensed through the optical deflector and the plastic optical element in a state of abutting against an optical axis reference and a scanning direction reference provided in the housing in advance. After scanning the position and measuring the scanning time in a specific range on each of the left and right sides of the scanning line, the second and subsequent layers are fixed and are stacked in the sub-scanning direction. While the plastic optical element arranged opposite to the light deflector which abuts only the optical axis reference, the scanning time measured by the same means,
The optical scanning device is characterized in that the plastic optical element is sequentially adjusted and fixed so as to be substantially equal to the first layer by position adjustment in the scanning direction,
It is possible to reduce the non-uniformity of the scanning time between the respective layers of the plastic optical element, and by adjusting the respective layers, it is possible to improve the accuracy of the plastic optical element without significantly increasing the accuracy of the image forming apparatus. It is possible to reduce the dot position deviation (scan position deviation) in the scanning direction between the respective colors. Further, since the adjustment and fixing process is performed by mounting all the elements other than the plastic optical element, it is possible to guarantee the unit in consideration of the processing accuracy of all the elements.

In addition, by using a photo-curable adhesive at the time of bonding, the timing of curing of the adhesive can be controlled, which facilitates the assembly adjustment and also makes an extra adjustment for each optical element. The mechanism and adjusting means are unnecessary.

At the time of joining, an adhesive is applied in advance to the joining surface between the plastic optical element and the housing and the joining surface between the plastic optical elements, and the layers are stacked on top of each other. At the same time, the work time can be shortened by adjusting and fixing the optical axis.

In the above embodiments, the case where two layers of plastic optical elements are laminated has been described.
It is not limited to layers. That is, the essence of the present invention is to layer the optical scanning device in layers so as not to cause a scanning position shift without extremely increasing the precision of the plastic optical element. Therefore, even if the number of layers of the plastic optical element is increased. , The superiority is not lost because the layers can be joined together. That is, various modifications can be made without departing from the gist of the present invention.

[0071]

As described above, according to the present invention,
Without extremely increasing the precision of the plastic optical element,
It is possible to provide an optical scanning device and an image forming apparatus that do not cause a dot position shift (scanning position shift) in the scanning direction. Further, since the adjustment and fixing process is performed by mounting all the elements other than the plastic optical element, it is possible to guarantee the unit in consideration of the processing accuracy of all the elements.

Furthermore, by using a photo-curing adhesive at the time of bonding, the timing of curing of the adhesive can be controlled, which facilitates the assembly adjustment and the extra adjustment for each optical element. The mechanism and adjusting means are unnecessary.

At the time of joining, an adhesive agent is applied in advance to the joining surfaces of the plastic optical element and the housing and the joining surfaces of the plastic optical elements, and all the plastic optical elements are stacked on top of each other. At the same time, the work time can be shortened by adjusting and fixing the optical axis.

[Brief description of drawings]

FIG. 1 is a schematic plan view of an optical scanning device according to a first embodiment of the present invention.

FIG. 2 is a schematic side view of the same.

FIG. 3 is a schematic plan view showing position adjustment in the first-layer plastic optical element of the optical scanning device according to the first embodiment.

FIG. 4 is a schematic side view of the same.

FIG. 5 is a first layer and a second layer of the optical scanning device according to the first embodiment.
It is a figure for demonstrating the scanning time of the beam condensed by the plastic optical element of the layer.

FIG. 6 is a schematic plan view showing a modified example of position adjustment in the first-layer plastic optical element of the optical scanning device according to the first embodiment.

FIG. 7 is a schematic plan view of an optical scanning device that forms an image according to a second embodiment of the present invention.

FIG. 8 is a schematic side view of the same.

FIG. 9 is a schematic plan view showing position adjustment in the first-layer plastic optical element of the optical scanning device according to the second embodiment.

FIG. 10 is a schematic side view of the same.

FIG. 11 is a diagram for explaining a scanning time of a beam condensed by the first-layer and second-layer plastic optical elements of the optical scanning device according to the second embodiment.

FIG. 12 is a schematic plan view showing a modified example of position adjustment in the first-layer plastic optical element of the optical scanning device according to the second embodiment.

FIG. 13 is a perspective view showing an example of a single-layer fθ lens.

FIG. 14 is a diagram showing adhesion of a first-layer plastic optical element with an ultraviolet curable adhesive.

FIG. 15 is a diagram showing adhesion of a second-layer plastic optical element with an ultraviolet curable adhesive.

[Explanation of symbols]

1 case 2, 15, 16 laser light source 3, 17 optical deflector 4, 18, 19 plastic optical element 5, 5a, 20, 20a optical axis reference 5b, 20b reference in main scanning direction 7, 23, 24 photoconductor position 12, 13, 23a, 23b, 24a, 24b Photosensitive members 37, 37a to 37d, 39, 39a to 39d, 40,
40a-40d, 41, 41a-41d, 42, 42a
˜42d, 43, 43a˜43d Beam detector 44 1-layer fθ lens 45 UV curable adhesive 46 Light source

Front page continued (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/113 H04N 1/04 104A F term (reference) 2C362 AA43 AA45 AA48 BA52 BA58 BA86 BA90 CA22 CA39 DA02 DA03 2H045 AA01 BA22 BA32 CA63 CA92 5C051 AA02 CA07 DB22 DB30 DC07 DD02 DE21 EA01 FA01 5C072 AA03 BA04 HA02 HA06 HA09 HA12 QA14 XA01 XA05

Claims (6)

[Claims] 1. Image information is obtained by scanning a beam emitted from a plurality of laser light sources and condensed on each photoconductor through an optical deflector and a plastic optical element stacked in the sub-scanning direction. Accordingly, in the optical scanning device of the image forming apparatus for forming an image, the plastic optical element is emitted from a corresponding laser light source in a state of abutting against an optical axis reference provided in advance in the housing, and the optical deflector and the The beam condensed through the plastic optical element is scanned on the photosensitive member position, and the scanning time in each of the left and right scanning lines and in a specific range is adjusted to be substantially equal by the position adjustment in the scanning direction of the plastic optical element. And the fixed first-layer plastic optical element and the first-layer plastic optical element laminated in the sub-scanning direction. The plastic optical element of the second layer or later, which is composed of a plastic optical element and is laminated in the sub-scanning direction, has the same scanning time as the plastic optical element of the second layer or later corresponding to the plastic optical element of the second layer or later. An optical scanning device of an image forming apparatus, wherein the optical scanning device is adjusted and fixed so as to be substantially equal to the plastic optical element of the first layer by position adjustment in the scanning direction. 2. The optical scanning device of the image forming apparatus according to claim 1, wherein the plastic optical elements are arranged to face each other with the optical deflector interposed therebetween. 3. An abutting reference in the scanning direction for abutting the first-layer plastic optical element is provided in advance in the housing, and the aforesaid first-layer plastic optical element is abutted for the abutting reference in the scanning direction. 3. The optical scanning device of the image forming apparatus according to claim 1, wherein the plastic optical element of the first layer is fixed so that the scanning time becomes even in this state. 4. The optical scanning device for an image forming apparatus according to claim 1, wherein the fixing means of the plastic optical element is an adhesive fixing, and the adhesive is a photo-curing adhesive. 5. The optical scanning device for an image forming apparatus according to claim 4, wherein an adhesive is applied to all the plastic optical elements in advance, and the plastic optical elements are adhered at the same time. 6. An image forming apparatus comprising the optical scanning device of the image forming apparatus according to claim 1.