JP2004012550A - Optical scanner manufacturing method and optical scanner, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set the dimension of a positioning span in the subscanning direction of an incident mirror so as to effectively keep the accuracy of the rotating position of the incident mirror in the subscanning direction in accordance with the optical path length or the subscanning lateral magnification of an applied scanning optical system. <P>SOLUTION: The optical scanner is equipped with the incident mirror M for folding an optical path between a light source 6 and a polygon mirror 8 for deflecting emitted light from the light source 6 between the light source 6 and the polygon mirror 8, and an expression of LO/(L1+L2)>0.06 mm is satisfied, wherein LO means the positioning span in the subscanning direction of the incident mirror M, L1 means optical path length from the reflection point of the incident mirror M to the polygon mirror 8 and L2 means optical path length from the polygon mirror 8 to the final surface of a scanning optical device. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention manufactures an optical scanning device including an incident mirror for folding an optical path between a light source and an optical polarizing device between a light source and an optical deflecting device that deflects light emitted from the light source, and manufactures the optical scanning device. The present invention relates to a method and an image forming apparatus including the optical scanning device.
[0002]
[Prior art]
Such an optical scanning device is disclosed in, for example, JP-A-2000-180773 and JP-A-9-281419. First, FIGS. 14 and 15 show an example of an optical scanning device used in an image forming apparatus such as a printer, a copying machine, and a facsimile, which are often used in the related art. FIG. 14 is a plan view, and FIG. 15 is a sectional view. The optical scanning device 2 located inside the image forming apparatus 1 includes an optical housing 3 for mounting an optical element at a predetermined position, and a housing cover that shields the inside of the optical housing 3 from the outside and performs a dustproof and soundproof function. 4, a light deflecting device (hereinafter, polygon motor) 5 using a rotating polygon mirror 8, a laser oscillation unit 6, and a plurality of optical elements.
[0003]
The light beam emitted from the laser oscillation unit 6 passes through a cylinder lens 7 and is applied to a rotating polygon mirror (hereinafter, polygon mirror) 8. After that, the light beam reflected by the polygon mirror 8 passes through the fθ lens 9 and the long lens 10, passes through the dustproof glass 11, and reaches the photosensitive member 12. When the light beam scans the surface of the photoconductor 12 linearly with the rotation of the polygon mirror 8, an electrostatic latent image is formed on the photoconductor 12, and an image is formed through an image forming process.
[0004]
Here, the light incident on the polygon mirror 8 and the scanning lens system behind the polygon mirror 8 (the fθ lens 9 and the long lens 10 in this example) when viewed from the direction of the plan view shown in FIG. ) And the optical axis Ax is θ, approximately
40 ° <θ ≦ 90 °
It is often set to be. The reason is that, when the optical path is to be laid out in a plane, it is necessary to set so that the light incident on the polygon mirror 8 does not interfere with the external portion of the fθ lens 8 disposed after the polygon mirror 8 and its supporting portion. Also, there are restrictions on the layout in consideration of the maximum effective writing width in the main scanning direction, the size and arrangement of the laser oscillation unit 6, the exchangeability, and the like.
[0005]
If a relatively large θ is set, the change in the optical path length due to the rotation of the polygon mirror 8, that is, the asymmetry of the sag with respect to the optical axis Ax increases. This increases the inclination and curvature of the image plane in the main scanning, and adversely affects the uniformity of the beam diameter on the photoconductor 12. The same applies to the fθ characteristic, the lateral magnification error, and the magnification error deviation, and the unevenness of the image plane light amount distribution in the main scanning direction called shading tends to increase depending on the type of the optical system. Therefore, in the plan view shown in FIG. 14, θ is about 60 °, but the desired θ in the actual optical scanning device is approximately
θ <70 °
It is.
[0006]
[Problems to be solved by the invention]
In recent years, in an optical scanning device, a folding mirror (hereinafter, referred to as an incident mirror) for reflecting incident light and changing its direction between a light source (laser oscillation unit) 6 and a polygon mirror 8 in order to avoid the above various problems. ) Is increasing. A typical example will be described below. 1 and 2 show an example of an optical scanning device equipped with an incident mirror M. FIG. 1 is a plan view, and FIG. 2 is a sectional view. The feature of this example is that the light beam reaching the polygon mirror 8 is incident from substantially the optical axis direction of the scanning optical system.
[0007]
By causing the light to enter the polygon mirror 8 in this manner, it becomes optically substantially axially symmetric with respect to the optical axis Ax of the scanning optical system, so that it is convenient to avoid the various problems described above. For this purpose, the incident mirror M is arranged near the optical axis Ax of the scanning optical system. Therefore, the layout of the laser oscillation unit 6 and the cylinder lens 7 is designed to have a relatively high degree of freedom as compared with the examples shown in FIGS. It can be performed.
[0008]
However, comparing the cross-sectional view shown in FIG. 2 with that of FIG. 15, the layout is complicated because the optical path cannot be made flat in the sub-scanning cross-sectional direction, and design and optical evaluation are more difficult in this regard. In addition, there is a problem that the cost of parts such as the optical housing 3 and the fixing member of the optical element increases.
[0009]
As another example, an example in which an incident mirror is employed for another reason will be described below. 2. Description of the Related Art In recent years, with the colorization of image forming apparatuses, a type in which scanning light is incident on a plurality of photosensitive members typified by a quadruple tandem arrangement as in Japanese Patent No. 2725067 has been devised and commercialized. Japanese Patent No. 2725067 describes a scanning optical system corresponding to such a tandem type image forming unit. However, a polygon motor which is one of the most expensive parts is commonly used as much as possible, and The number of products designed and implemented to secure high reliability through cost reduction, compactness, and simplification is increasing.
[0010]
3 and 4 show an example of a color image forming apparatus having two photoconductors (12a and 12b in the figure). A color image is generally formed by superimposing four toner images of black, magenta, yellow, and cyan. In this example, two photoconductors 12a and 12b are provided, and there are two light paths corresponding to them. First, a first optical path reaching the photoconductor 12a will be described. A light beam emitted from the laser oscillation unit 6a is applied to the polygon mirror 8 through the cylinder lens 7a. In the second optical path reaching the photoreceptor 12b, a light beam emitted from the laser oscillation unit 6b passes through the cylinder lens 7b, is turned back by the incident mirror M, and is irradiated on the polygon mirror 8.
[0011]
Here, although not shown, these arrangements in the sub-scanning section direction are such that the first optical path from the laser oscillation unit 6a to the polygon mirror 8 is arranged so as to be inclined slightly downward from the horizontal. The second optical path from the oscillating unit 6b to the polygon mirror 8 is disposed so as to be slightly inclined upward from horizontal. The two optical paths substantially coincide at the reflection point of the polygon mirror 8, and are separated again in the sub-scanning direction behind the two optical paths. In the fθ lens 9, two optical paths pass. Thereafter, the light beam on the first optical path passes through the mirror 13a, the long lens 10a, the mirror 14, and the dustproof glass 11a, and reaches the photoconductor 12a on the left side. The light beam on the second optical path passes through the long lens 10b, the mirror 13b, and the dust-proof glass 11b, and reaches the photoconductor 12b on the right side.
[0012]
First, an electrostatic latent image is formed on the photoconductor 12a by the first light beam, and a toner image is formed by the black developing unit 15a. An electrostatic latent image is formed on the photoreceptor 12b by the second light beam at a predetermined interval, and a magenta toner image is formed by the magenta developing unit 15b. These two toner images are transferred onto the intermediate transfer belt 17 so as to be aligned. Next, a yellow electrostatic latent image is formed on the photoconductor 12a again by the first light beam, and a toner image is formed in the yellow developing unit 16a. Similarly, at a predetermined interval, a cyan toner image is formed on the photoconductor 12b by the cyan developing unit 16b with the second light beam. The intermediate transfer belt 17 makes one rotation after the previous process, and these two-color toner images are superimposed and transferred on the two colors previously transferred. The color image formed in this way is transferred to a transfer sheet at the secondary transfer unit 18, and a hard copy is obtained.
[0013]
FIG. 5 shows a conventional method of supporting the incident mirror M which is often performed. Generally, in order to determine the attitude of the reflecting surface of the mirror in a three-dimensional manner, any three points may be brought into contact with the reflecting surface and biased. In this example, it is urged by the contact portions 21, 22, and 23 installed in the optical housing 3. The inclination β of the incident mirror M viewed from the sub-scanning cross section direction is determined by the positional accuracy of the contact portions 21 and 22 arranged vertically above and below as viewed in FIG. It is the positional accuracy of the contact portion 23 with respect to the contact portions 21 and 22 that determines the inclination α as viewed from the main scanning section direction.
[0014]
The vertical positioning of the entrance mirror M as seen in this figure is also achieved by abutting at two contact portions 25 provided on the optical housing 3 similarly to the contact portions 21, 22, and 23 described above. Done. However, this vertical positioning is performed with respect to the end face of the entrance mirror M, and in terms of required positional accuracy, compared with the case where the above-mentioned three points are brought into contact and the attitude of the reflecting surface of the mirror M is urged. It is possible to set a tolerance one order lower. Two urging members 24, such as leaf springs, which support and press the incident mirror M urged by the contact portions 21 to 23 and 25, are provided corresponding to the front and rear contact portions. Although omitted here, the positioning in the front-back direction may be performed as described above.
[0015]
Now, a problem regarding the inclination β of the incident mirror M in the sub-scanning direction in the scanning optical system using the incident mirror M will be described below. As shown in FIG. 6, it is assumed that the incidence mirror M is tilted by Δβ from the originally set posture, here, perpendicular. Then, the light flux reaching the polygon mirror 8 from the entrance mirror M is inclined by 2Δβ according to the law of reflection at the mirror. Assuming that the span of the contact portions 21 and 22 is L0 and their positional accuracy is Δ
Δβ = tan ＾ -1 (Δ / L0)
It becomes. In the following description, ＾ indicates a power.
[0016]
Here, L0 is often about 10 mm because of the cost of the entrance mirror M and the space for installation, and Δ is 0.03 mm at least estimated from the processing accuracy that enables mass production of the optical housing. Ability
Δβ ≧ tan ＾ -1 (0.03 / 10)
= 0.17 (degree) ··· (1)
It becomes.
[0017]
The effect of Δβ of the incident mirror M will be described with reference to FIGS. Assuming that the optical path length between the incident mirror M and the polygon mirror 8 is L1, the deviation h1 in the sub-scanning direction of the reflection point of the polygon mirror 8 due to the above Δβ is
h1 = L1 × tan (2Δβ)
It becomes. The light beam reflected by the polygon mirror 8 also has an inclination of 2Δβ, and the deviation in the sub-scanning direction becomes h2 when it reaches the second surface of the long lens 10. If the optical path length from the light deflecting device 5 to the final surface of the scanning lens 10 is L2,
h2 = h1 + L2 × tan (2Δβ)
= (L1 + L2) tan (2Δβ)
It is.
[0018]
By the way, it has been empirically and empirically known that various optical performances largely deviate from a target unless h2 is set to less than about 0.5 mm. So, substituting this number into the above equation
(L1 + L2) tan (2Δβ) <0.5
Would be convenient. Solving this for Δβ gives
Δβ <tan {-1} 1/2 (L1 + L2)}
When L1 = 60 mm and L2 = 160 mm are used as values of a scanning optical system actually designed.
1/2 (L1 + L2) = 1/2 (60 + 160)
= 2.27 × 10 ＾ -3
And
Δβ <tan ＾ -1 (2.27 × 10 ＾ -3)
= 0.13 (degree) ··· (2)
It becomes.
[0019]
Comparing Equations (1) and (2), it is difficult to suppress Δβ of the incident mirror M to a range where there is no problem when considering the actual mass production process. For this reason, it is necessary to set the position accuracy of Δ to a high accuracy that does not have a process capability of, for example, about 0.01 mm, and it is necessary to spend labor such as local dimensional management of the optical housing to secure optical performance. In addition, the fact that the optical performance is sensitively affected by Δβ is not preferable for environmental fluctuations, such as a temperature rise inside and outside the optical housing, and the scanning light optical characteristics due to thermal expansion and thermal deformation of the optical housing. Degradation can be a bigger problem.
[0020]
The present invention has been made in view of the above-described problems, and has been made in consideration of an optical path length and a sub-scanning lateral magnification of a scanning optical system to be applied. It is an object of the present invention to provide a manufacturing direction of an optical scanning device capable of setting dimensions of the optical scanning device, the scanning device, and an image forming apparatus.
[0021]
[Means for Solving the Problems]
The first means, in order to achieve the above object, between the light source and a light deflecting device that deflects the light emitted from the light source, the light source, with an incident mirror for folding the optical path between the light polarizing device, In a method for manufacturing an optical scanning device comprising one or more scanning optical elements between the light polarizing device and the medium to be scanned,
L0 is the positioning span of the incident mirror in the sub-scanning direction, L1 is the optical path length from the reflection point of the incident mirror to the optical deflector, and L2 is the optical path length from the optical deflector to the final surface of the scanning optical element. sometimes,
L0 / (L1 + L2)
Is defined based on the dimensional accuracy of the mass production limit.
[0022]
A second means is the first means, wherein the dimensional accuracy of the mass production limit is 0.03 mm.
[0023]
The third means includes, between a light source and a light deflecting device for deflecting the light emitted from the light source, an incident mirror for turning an optical path between the light source and the light polarizing device, and the light polarizing device and the scanning target. An optical scanning device comprising one or more scanning optical elements between media,
An optical scanning device characterized by satisfying the following expression.
[0024]
L0 / (L1 + L2)> 0.06 mm
here
L0: positioning span of the incident mirror in the sub-scanning direction
L1: optical path length from the reflection point of the incident mirror to the light deflector
L2: optical path length from the light deflecting device to the final surface of the scanning optical element
The fourth means, in order to achieve the above object, between the light source and a light deflecting device that deflects the light emitted from the light source, the light source, with an incident mirror for folding the optical path between the light polarizing device, An optical scanning device comprising one or more scanning optical elements between the light polarizing device and the medium to be scanned,
An optical scanning device characterized by satisfying the following expression.
[0025]
| 1 / m | × (L0 / L1)> 0.3 mm
here,
L0: positioning span of the incident mirror in the sub-scanning direction
L1: optical path length from the reflection point of the incident mirror to the light deflector
m: lateral magnification of the entire scanning optical system in the sub-scanning direction
The fifth means is characterized in that, in the first and second means, a light beam reaching the light deflector as viewed from the main scanning section direction is incident substantially from the optical axis direction of the scanning optical system.
[0026]
A sixth means is that, in the first and second means, the angle between the light incident on the light deflector and the optical axis of the scanning lens system behind the light deflector when viewed from the main scanning section direction is θ. And when
30 ° <θ <100 °
And
An optical path for emitting a plurality of scanning lights is provided in the housing, and the plurality of optical paths intersect at least once in the optical path when viewed in the sub-scanning cross-sectional direction.
[0027]
A seventh means is that, in the first and second means, the angle between the light incident on the optical deflector and the optical axis of the scanning lens system rearward from the optical deflector when viewed from the main scanning section direction is θ. And when
30 ° <θ <100 °
And
An optical path for emitting a plurality of scanning lights is provided in the housing, and the plurality of optical paths are stacked substantially parallel to each other when viewed in the sub-scanning section direction.
[0028]
Eighth means is the first to fifth means, further comprising a member for rotating the incident mirror for adjusting an angle of a light beam incident on the light deflector in the sub-scanning direction. .
[0029]
A ninth means is the light emitting device according to the eighth means, wherein the member for rotating the incident mirror is a stay member.
[0030]
According to a tenth aspect, in the seventh aspect, the stay member is configured so that a rotation axis substantially passes through the incident mirror reflection point.
[0031]
According to an eleventh aspect, in the eighth to the tenth aspects, the angle of the incident mirror in the sub-scanning direction is adjusted by adjusting the angle of the lever member.
[0032]
A twelfth means is the light emitting device according to the eighth to eleventh means, wherein the incident mirror has a reflecting surface supported by two fulcrums and is rotatable around the two fulcrums.
[0033]
A thirteenth means is characterized in that, in the twelfth means, a rotation axis connecting the two fulcrums substantially passes through the incident mirror reflection point.
[0034]
A fourteenth means is characterized in that the image forming apparatus comprises the optical scanning device according to the third to thirteenth means, and an image forming means for visualizing a latent image written by the optical scanning device. I do.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, FIG. 1 and FIG. 2, FIG. 3, FIG. 4 and FIG. 8 show the optical scanning device according to the present invention, but since the configuration has already been described, detailed description will be omitted here.
[0036]
A first embodiment will be described. The two equations derived above,
Δβ = tan ＾ -1 (Δ / L0)
Δβ <tan {-1} 1/2 (L1 + L2)}
Is removed from, and tan is applied to both sides,
Δ / L0 <1/2 (L1 + L2)
It becomes.
[0037]
When deformed
L0 / (L1 + L2)> 2Δ
Here, 0.03 mm, which is the dimensional accuracy of the mass production limit described above, is substituted into Δ.
L0 / (L1 + L2)> 0.06 (mm) (3)
By setting the span L0 of the contact portions 21 and 22 so as to apply to the formula (3), the object of the present invention can be satisfied. As an example, when L1 = 60 mm and L2 = 160 mm are put into the equation (3) as the numbers used above,
L0> 13.2 (mm)
The result comes out. In the optical system of this example, L0 is 14 mm, and the width of the incident mirror M in the sub-scanning direction is considered to be sufficient if it is 16 mm, assuming that the contact position is 1 mm inside each of the upper and lower ends.
[0038]
Another embodiment will be described with reference to FIGS. Here, first, attention is paid to the sub-scanning lateral magnification m of the scanning optical system.
[0039]
L: optical path length from the polygon mirror 8 to the image plane of the photoconductor
a: optical path length from the polygon mirror 8 to the scanning optical system sub-scanning principal point position
b: optical path length from the sub-scanning principal point position of the scanning optical system to the image plane of the photoconductor
Then, L = a + b and the sub-scanning lateral magnification m is
m = -b / a
Is defined as The displacement of the light beam in the sub-scanning direction on the image plane is denoted by h. In FIG. 9, the displacement h1 of the polygon mirror reflection point in the sub-scanning direction is as described in the previous embodiment.
h1 = L1 × tan (2Δβ)
Because
h = h1 × | m |
= L1 × tan (2Δβ) × |
≒ L1 × (2Δ / L0) × ||
Transform the above formula /
| 1 / m | × (L0 / L1) = 2Δ / h
Here, 0.03 mm, which is the dimensional accuracy of the mass production limit described above, is substituted for Δ, and 0.2 mm is substituted from the experience of the conventional scanning optical system as the maximum value allowed for h.
| 1 / m | × (L0 / L1)> 0.3 (mm) ··· 4
By setting the span L0 of the contact portions 21 and 22 so as to apply to the formula (4), the problem in the present invention can be satisfied. As an example, when m = 1.0 and L1 = 60 mm are put into the equation (3) as the numbers used above,
L0> 18 (mm)
The result comes out. In the optical system of this example, L0 is 19 mm, and the width of the incident mirror M in the sub-scanning direction is considered to be sufficient if it is 21 mm, assuming that the contact position is 1 mm inward from both upper and lower ends.
[0040]
Contrary to the above two embodiments, when sufficient L0 cannot be secured due to cost and space, it is necessary to perform the rotation adjustment in the β direction. Some specific methods in that case are described below. FIG. 10 shows an example of a rotation adjustment method of the incident mirror M in the β direction. In this example, the incident mirror M rotates in the β direction around the rotation axis Ax1 passing through the contact portions 22 and 23 provided in the optical housing 3. Rotation adjustment is performed by moving an upper position of the entrance mirror M by turning an adjustment screw 26 having the other one of the reflection surface contact portions at its tip. Two urging members 24, such as leaf springs, which support and press the incident mirror M urged by these contact portions 22, 23, are installed corresponding to the front and rear contact portions 22, 23. This is similar to the example of FIG.
[0041]
FIG. 11 shows another example of the rotation adjustment method of the incident mirror M in the β direction. In this example, the entrance mirror M is held and urged by a stay member 27 formed of sheet metal. The stay member 27 is bent in a U-shape in horizontal section, and a total of three contact portions 27a are formed on both side surfaces to urge the incident mirror M. The holding and fixing are performed by an urging member 28 formed of a leaf spring or the like that applies a force so as to press the rear surfaces at both ends of the incident mirror M.
[0042]
The stay member 27 is provided at both ends with shafts 27b that can rotate around the rotation axis Ax2, and bearings 29 that hold them are installed in the optical housing 3 so that the β direction of the entrance mirror M can be adjusted. It has become. A lever member 30 is formed at one end of the stay member 27, and the adjusting screw 26 is assembled to a hole at the tip of the lever member 30. The adjusting screw 26 is screwed into a screw boss 32 provided on the optical housing 3, and an initial stress in the axial direction is applied to the lever member 30 by the coil spring 33. By rotating the adjusting screw 26, the tip of the lever member 30 is moved up and down, and the rotation of the incident mirror M held by the stay member 27 in the β direction is adjusted.
[0043]
In this example, by changing the length of the lever member 30, the ratio of the degree of adjustment between the rotation of the adjusting screw 26 and the rotation of the entrance mirror M in the β direction can be set freely. Therefore, it is possible to easily set the lever ratio so that fine adjustment can be easily performed. In addition, since the installation posture of the adjusting screw 26 can be made vertical, the adjustment work becomes easier. In this example, setting the rotation axis Ax2 so as to pass through the reflection point of the incident mirror as shown in FIG. 10 is advantageous because the optical path length does not change when the rotation adjustment in the β direction is performed.
[0044]
FIGS. 12 and 13 show another example of the rotation adjustment method of the incident mirror M in the β direction. In this example, the incident mirror M rotates in the β direction around the rotation axis Ax3 passing through the fulcrums 22a and 23a at the tips of the contact portions 22 and 23 installed in the optical housing 3. On the back surface of the entrance mirror M, an L-shaped lever member 34 is provided. It is the same as the example of FIG. 11 in that it is configured by the elements of the adjusting screw 26, the screw boss 32, and the coil spring 33 so that the rotation can be adjusted. At both ends of the entrance mirror M, biasing members 35 are installed corresponding to the contact portions 22 and 23.
[0045]
FIG. 13 shows a side view of FIG. 12, in which the urging member 35 is supported and pressed from the back of the entrance mirror M and from above and below. Of course, also in this example, if the rotation axis Ax3 is set so as to pass through the reflection point of the incident mirror, there is no change in the optical path length when the rotation in the β direction is adjusted, which is advantageous. In this example, since the rotation adjustment in the β direction is realized with a relatively simple configuration in the examples described so far, and the optical path length does not change, a low-cost and reliable adjustment method can be provided.
[0046]
Needless to say, the invention so far can be applied to an optical scanning device using an incident mirror M as shown in FIGS. 1, 2, 3 and 4, and a plurality of scanning lights are emitted into another optical scanning device. Is effective even in a configuration in which a plurality of optical paths are stacked substantially in parallel in the sub-scanning section direction as described in Japanese Patent Publication No. 2725067. Of course. The present invention is effective for all optical scanning devices using the entrance mirror M.
[0047]
In this embodiment, although not particularly shown, these optical scanning devices are used as image data input means of an electrophotographic image forming apparatus. That is, optical writing is performed on the photosensitive member (not shown) by the optical scanning device, a latent image is written in monochrome, color, or full color on the photosensitive member, developed with toner, and visualized. For example, it is transferred to paper and output as an image. Since the image forming apparatus of this type is known, a detailed description thereof will be omitted.
[0048]
【The invention's effect】
As described above, according to the first to third aspects of the present invention, the sub-scanning of the incident mirror which effectively keeps the rotational position accuracy of the incident mirror in the sub-scanning direction according to the optical path length of the scanning optical system to be applied. The dimension of the direction positioning span can be set, and rotation in the sub-scanning direction, which causes deterioration of various optical performances, can be prevented.
[0049]
According to the fourth aspect of the present invention, the incident mirror is positioned in the sub-scanning direction such that the rotational position accuracy of the incident mirror in the sub-scanning direction is effectively maintained in accordance with the optical path length of the scanning optical system and the sub-scanning lateral magnification. It is possible to set the dimension of the span, and it is possible to prevent the sub-scanning direction, which causes deterioration of various optical performances, beforehand.
[0050]
According to the fifth aspect of the present invention, when the optical scanning device mounted thereon has a light beam reaching the polygon mirror viewed from the main scanning cross-sectional direction which is often seen in a recent optical scanning device, the light beam is substantially equivalent to a scanning optical system. Since the light is incident from the direction of the optical axis, the effects of the present invention work very effectively and good optical performance can be obtained.
[0051]
According to the sixth aspect of the present invention, the optical scanning device to be mounted is a type in which the plurality of optical paths cross each other at least once in the middle of the optical path when viewed in the sub-scanning sectional direction. Therefore, the inventions of the present invention each work very effectively, and good optical performance can be obtained. Therefore, a high-quality color image can be provided.
[0052]
According to the invention described in claim 7, the mounted optical scanning device is an optical scanning device in which a plurality of optical paths are stacked substantially in parallel when viewed in the sub-scanning cross-sectional direction. It works very effectively and can obtain good optical performance. Therefore, a high-quality color image can be provided.
[0053]
According to the eighth and ninth aspects of the invention, since the angle of the sub-scanning position of the light beam incident on the light deflector can be adjusted, the position of the incident mirror in the sub-scanning direction cannot be long due to cost and space. It is possible to adjust the rotation in the sub-scanning direction and to prevent various optical performances from deteriorating.
[0054]
According to the tenth aspect of the present invention, since the rotation axis of the stay member is configured to substantially pass through the reflection point of the incident mirror, the optical path length does not change when the rotational adjustment in the sub-scanning direction is performed. It is convenient.
[0055]
According to the eleventh aspect, by adjusting the installation angle of the lever member, the incident mirror rotates and the sub-scanning position of the light beam incident on the polygon mirror can be moved, so that the length of the lever is changed. As a result, the ratio of the degree of adjustment of the rotation of the adjusting screw to the degree of rotation of the incident mirror in the sub-scanning direction can be freely set, and fine adjustment can be easily performed. In addition, since the setting posture of the adjustment screw can be made vertical, the adjustment work becomes easier.
[0056]
According to the twelfth aspect of the present invention, the reflecting mirror is supported by the two fulcrums, and the incident mirror has a mechanism capable of rotating around the two fulcrums. Rotation adjustment can be realized.
[0057]
According to the thirteenth aspect of the present invention, the rotation axis connecting the two fulcrums is configured to substantially pass through the reflection point of the incident mirror. Therefore, when the rotation adjustment in the sub-scanning direction is performed, the change in the optical path length is reduced. This is convenient because it does not occur.
[0058]
According to the fourteenth aspect, it is possible to provide an image forming apparatus having the effects of the third to thirteenth aspects.
[Brief description of the drawings]
FIG. 1 is a plan view showing an embodiment of an optical scanning device according to the present invention.
FIG. 2 is a side sectional view showing the optical scanning device of FIG. 1;
FIG. 3 is a plan view showing another embodiment of the optical scanning device according to the present invention.
FIG. 4 is a side sectional view showing the optical scanning device of FIG. 3;
FIG. 5 is a perspective view showing a conventional incident mirror holding member.
FIG. 6 is an explanatory diagram showing a deviation of a reflection angle of the incident mirror of FIG. 5;
FIG. 7 is an explanatory diagram showing an influence of a rotation shift of an incident mirror.
FIG. 8 is an explanatory diagram showing an optical scanning device according to the present invention.
FIG. 9 is an explanatory diagram showing an influence of a rotation shift of the incident mirror in FIG. 8;
FIG. 10 is a perspective view showing an example of an incident mirror holding member according to the present invention.
FIG. 11 is a perspective view showing another example of the incident mirror holding member according to the present invention.
FIG. 12 is a perspective view showing still another example of the incident mirror holding member according to the present invention.
FIG. 13 is a side view showing the incident mirror holding member of FIG.
FIG. 14 is a plan view showing a conventional optical scanning device.
FIG. 15 is a side sectional view showing the optical scanning device of FIG. 14;
[Explanation of symbols]
6. Light source (laser oscillation unit)
8 Polygon mirror
M Incident mirror

Claims (14)

An incident mirror for folding an optical path between the light source and the light polarizing device is provided between the light source and the light deflecting device for deflecting the light emitted from the light source. In the method of manufacturing an optical scanning device including the above scanning optical element,
L0 is the positioning span of the incident mirror in the sub-scanning direction, L1 is the optical path length from the reflection point of the incident mirror to the optical deflector, and L2 is the optical path length from the optical deflector to the final surface of the scanning optical element. sometimes,
L0 / (L1 + L2)
And manufacturing the optical scanning device from the dimensional accuracy of the mass production limit. 2. The method according to claim 1, wherein the dimensional accuracy of the mass production limit is 0.03 mm. An incident mirror for folding an optical path between the light source and the light polarizing device is provided between the light source and the light deflecting device for deflecting the light emitted from the light source. In an optical scanning device including the above scanning optical element,
An optical scanning device characterized by satisfying the following expression.
L0 / (L1 + L2)> 0.06 mm
Here, L0: positioning span of the incident mirror in the sub-scanning direction L1: optical path length from the reflection point of the incident mirror to the light deflector L2: optical path length from the light deflector to the final surface of the scanning optical element An incident mirror for folding an optical path between the light source and the light polarizing device is provided between the light source and the light deflecting device for deflecting the light emitted from the light source. In an optical scanning device including the above scanning optical element,
An optical scanning device characterized by satisfying the following expression.
| 1 / m | × (L0 / L1)> 0.3 mm
here,
L0: Positioning span of the incident mirror in the sub-scanning direction L1: Optical path length from the reflection point of the incident mirror to the light deflector m: Lateral magnification of the entire scanning optical system in the sub-scanning direction 5. The optical scanning device according to claim 3, wherein a light beam that reaches the optical deflector as viewed from a main scanning cross-sectional direction is incident substantially in an optical axis direction of a scanning optical system. 6. When the angle between the incident light on the optical deflector and the optical axis of the scanning lens system behind the optical deflector as viewed from the main scanning section direction is θ,
30 ° <θ <100 °
And
An optical path for emitting a plurality of scanning lights is provided in the housing, and the plurality of optical paths intersect at least once in the middle of the optical path when viewed in the sub-scanning sectional direction. Or the optical scanning device according to 4. When the angle between the incident light on the optical deflector and the optical axis of the scanning lens system behind the optical deflector as viewed from the main scanning section direction is θ,
30 ° <θ <100 °
And
The optical path for emitting a plurality of scanning lights is provided in the housing, and the plurality of optical paths are stacked substantially parallel as viewed in the sub-scanning section direction. An optical scanning device according to claim 1. 8. The optical scanning device according to claim 3, further comprising a member that rotates the incident mirror to adjust an angle of a light beam incident on the light deflector in the sub-scanning direction. apparatus. The optical scanning device according to claim 8, wherein the member that rotates the incident mirror is a stay member. The optical scanning device according to claim 9, wherein the stay member is configured such that a rotation axis substantially passes through the reflection point of the incident mirror. 11. The optical scanning device according to claim 8, wherein an angle of the incident mirror in the sub-scanning direction is adjusted by adjusting an angle of a lever member. The optical scanning device according to claim 8, wherein the incident mirror has a reflection surface supported by two fulcrums, and is rotatable around the two fulcrums. 13. The optical scanning device according to claim 12, wherein a rotation axis connecting the two fulcrums substantially passes through the incident mirror reflection point. An optical scanning device according to any one of claims 3 to 13,
Image forming means for visualizing the latent image written by the optical scanning device,
An image forming apparatus comprising:

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