JP2003329954A - Optical scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the assembly and the attachment, and the adjusting accuracy of lenses by constituting the lenses so that the optical axis of a cylindrical lens being a composite anamorphic lens can be non-parallel with the optical axis of the collimator lens and a Y reference surface can be parallel with a BD optical axis, and preventing returning light generated in the cylindrical lens. <P>SOLUTION: The optical scanner is equipped with a light source means, a 1st optical system to change luminous flux emitted from a light source to nearly parallel beams, a 2nd optical system to form an image as a line image long in a main scanning direction with the luminous flux passing through the 1st optical system, a deflector functioning as a deflection means, and a 3rd optical system to detect a write starting position, and characterized in that the 2nd optical system is integrally formed with the 3rd optical element and has a positioning part where the optical axis of the 2nd optical system is non- parallel with the optical axis of the 1st optical system and parallel with the optical axis of the 3rd optical system. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laser printer,
The present invention relates to an optical scanning device used in an image forming apparatus such as a digital copying machine.

[0002]

2. Description of the Related Art Conventionally, an optical scanning device used in an image forming apparatus such as a laser beam printer or a digital copying machine guides a light beam emitted from a light source to a deflecting element by an incident optical means to deflect the light beam. The light beam deflected by the element is imaged in a spot shape on the surface of the photosensitive drum, which is the surface to be scanned, by the scanning optical means, and the light beam optically scans the surface of the photosensitive drum.

In such an optical scanning device, a light beam emitted from a light source is converted into a substantially parallel light beam by a collimator lens or the like, and a light beam converted into a substantially parallel light beam for correcting tilt is deflected by a cylindrical lens. A line image is formed in the vicinity. Further, in order to accurately control the writing position of the image on the photosensitive drum surface, a synchronization position detecting means (BD optical system) is provided immediately before writing the image signal to control the writing position for each scanning.

In FIG. 11, reference numeral 1 denotes a light source means, which is composed of, for example, a semiconductor laser. An aperture stop 2 shapes the light flux emitted from the light source means 1 into a desired and optimum beam shape. A collimator lens 3 converts the light flux that has passed through the aperture stop 2 into a substantially parallel light flux.
A cylindrical lens 4 has a predetermined refractive power only in the sub-scanning direction. Each element such as the aperture stop 2, the collimator lens 3, and the cylindrical lens 4 constitutes one element of the incident optical means 51.

Reference numeral 5 denotes an optical deflector as a deflecting element, which is composed of, for example, a rotary polygon mirror, and is rotated at a constant speed in the direction of arrow A in the figure by a driving means (not shown) such as a motor.
Reference numeral 11 denotes two fθ lenses having fθ characteristics, which are collapsed by forming a conjugate relationship between the vicinity of the deflection surface 5a of the optical deflector 5 and the vicinity of the photosensitive drum surface 12 as the surface to be scanned in the sub-scan section. It has a correction function.

Reference numeral 6 denotes an imaging lens (hereinafter referred to as "BD lens"), which is a light beam (B) for detecting a synchronization signal for adjusting the timing of the scanning start position on the photosensitive drum surface 12.
Both the D light flux) are imaged on the surface of the BD slit 8 described later in the main scanning section. Further, it has a so-called surface tilt correction function for correcting tilting of the deflecting surface of the deflector in the sub-scan section.

Reference numeral 7 is an optical sensor (hereinafter referred to as "BD sensor") as a synchronization detecting element. In the figure, a synchronization signal (BD signal) obtained by detecting an output signal from the BD sensor 7 is shown. ) Is used to adjust the timing of the scanning start position of image recording on the photosensitive drum surface 12.

The elements such as the BD lens 6, the BD slit 8 and the BD sensor 10 are synchronous position detecting means (BD
The optical system) constitutes one element.

[0009]

In the above optical scanning device, since the optical axis of the collimator lens and the optical axis of the cylindrical lens coincide with each other, the cylindrical lens is provided with an antireflection coating such as a plastic mold. If the optical element is configured with no optical element, there is a problem that the reflected light of the cylindrical lens increases, the surface reflected light returns to the vicinity of the light emitting point of the semiconductor laser that is the light source, and the laser oscillation becomes unstable.

In order to avoid this, Japanese Patent Laid-Open No. 11-14
The technology described in 9037 is known in which a cylindrical lens is tilted to prevent reflected light.

However, in recent optical scanning devices, a part of the BD optical system and a cylindrical lens are integrally formed, and the size and cost of the device are reduced. In such an optical scanning device, in order to prevent the surface reflected light of the cylindrical lens from returning to the semiconductor laser, which is the light source, Japanese Patent Laid-Open No. 11-149.
It is impossible to prevent the reflected light by inclining only the cylindrical lens by the technique described in 037. This is because if the lens formed by integrating the cylindrical lens and the BD optical system is tilted, the optical axis of the BD optical system is also tilted, so after the light flux crosses the BD slit, the image writing position on the photosensitive drum surface is reached. This is because there is a problem that the image on the surface of the photosensitive drum is misaligned due to the change of the time.

According to the present invention, in a small and inexpensive optical scanning device in which a cylindrical lens and a BD lens are integrally formed, the surface reflected light of the cylindrical lens is prevented and the amount of light emitted from the light source is stabilized. At the same time, it is an object of the present invention to provide an optical scanning device capable of preventing a scanning start position shift on a surface to be scanned and obtaining a high-definition image.

[0013]

[1-1] A light source means and a first optical system for converting a light beam emitted from a light source into substantially parallel light and a light beam passing through the first optical system is long in a main scanning direction. In an optical scanning device including a second optical system for forming a line image, a deflector as a deflection unit, and a third optical system for detecting a writing start position, the second optical system is It is formed integrally with the third optical element, the optical axis of the second optical system is tilted with respect to the optical axis of the first optical system, and is positioned parallel to the optical axis of the third optical system. It is characterized by having a section.

(2-1) The light source means and the first optical system for converting the light beam emitted from the light source into substantially parallel light and the light beam passing through the first optical system are formed as a long line image in the main scanning direction. A second optical system, a deflector as a deflecting unit, a third optical system for detecting a writing position, and a detecting unit for detecting the writing position, and the second optical system and the In an optical scanning device including an optical element integrally formed with a third optical system, the optical scanning device passes through a point between front and rear principal points in the main scanning direction of the third optical system, and the third optical system and the third optical system. The third optical system is rotated about an axis that is perpendicular to a plane including the optical axis of the second optical system, and the third optical system is rotated with respect to an axis connecting the detection unit and a point between the front and rear principal points in the main scanning direction. The optical axis of the third optical system is tilted, and the optical axis of the first optical system and the second optical system The optical axis is arranged so as to be inclined in the main scanning direction, and (2-2) the inclination angle θ formed by the optical axis of the second optical system and the optical axis of the first optical system is 0. .8>2fθ> 0.08 f: The second optical system focal length is satisfied, and the optical scanning device according to claim 1 or claim 2.

(2-3) The second and third optical systems are molded lenses, and (2-4) the optical axes of the first and second optical systems. The center of rotation when tilting is characterized in that it is between the main scanning direction front and rear principal points of the third optical system, and (2-5) the second and third optical systems, The scanning optical device according to any one of claims 1 to 7, wherein the scanning optical device is configured to be movable in parallel with an optical axis of the third optical system. A photosensitive member disposed on the surface to be scanned, a developing device for developing an electrostatic latent image formed on the photosensitive member as a toner image by a light beam scanned by the scanning optical device, and the developed toner An image forming apparatus including a transfer device that transfers an image to a transfer material, and a fixing device that fixes the transferred toner image to the transfer material.

(2-7) A scanning optical device according to any one of claims 1 to 7, and a printer controller for converting code data input from an external device into an image signal and inputting it into the scanning optical device. An image forming apparatus provided with.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) FIG. 1 is a sectional view in the main scanning direction according to Embodiment 1 of the present invention, and FIG. 2 is a perspective view of an incident optical system 51 and a BD optical system 71 in FIG. Is a sectional view (main scanning sectional view) of an essential part of the incident optical system 51 and the BD optical system 71 in FIG.
Is.

In this specification, the surface formed by the optical axis of the scanning lens and the light beam deflected by the optical deflector is the main scanning cross section, and the surface including the optical axis of the scanning lens and orthogonal to the main scanning cross section is the sub scanning cross section. It is defined as

In the figure, reference numeral 1 denotes a light source means, which is composed of, for example, a semiconductor laser which emits a single light beam. Reference numeral 2 denotes a collimator lens, which converts the light beam from the light source 1 into a substantially parallel light beam. A cylindrical lens 3 has a predetermined refractive power only in the sub-scanning direction. Reference numeral 4 denotes an aperture stop, which determines the spot diameter on the surface 7 to be scanned. Collimator lens 2 and cylindrical lens
Each of the elements such as 3 and the aperture stop 4 constitutes one element of the incident optical means 51.

Reference numeral 5 denotes an optical deflector as a deflecting element, which is composed of, for example, a polygon mirror (rotary polygon mirror), and is rotated at a constant speed in the direction of arrow A in the figure by a driving means (not shown) such as a motor.

Reference numeral 6 denotes a scanning lens (fθ lens) having an fθ characteristic, which is a deflection surface 5a of the optical deflector 5 or its vicinity and a photosensitive drum surface 7 as a surface to be scanned in the sub-scan section.
Alternatively, it has a surface tilt correction function of the optical deflector by forming a substantially conjugate relationship with the vicinity thereof.

Reference numeral 8 denotes an image forming lens (hereinafter referred to as "BD lens"), which is a luminous flux (BD) for detecting a synchronizing signal for adjusting the timing of the scanning start position on the photosensitive drum surface 7.
The light beam) is substantially imaged on the surface of the BD slit 9 described later in both the main scanning section and the sub scanning section.

Reference numeral 9 denotes a slit (hereinafter referred to as "BD slit"), which is arranged at the image forming position of the BD lens 8 or in the vicinity thereof. The BD slit 9 has a knife-edge shape at its end and is scanned in the main scanning direction.
The position where the spot substantially imaged by the D lens 8 is incident on the surface of the BD sensor 10 is determined.

The BD lens 8 is manufactured integrally with the cylindrical lens 3 (hereinafter, compound anamorphic lens).
61), which is composed of anamorphic lenses having different powers in the main scanning direction and the sub-scanning direction, and is manufactured by plastic molding.

Reference numeral 10 denotes an optical sensor (hereinafter referred to as "BD sensor") as a synchronization detecting element. In this embodiment, a synchronization signal (BD signal) obtained by detecting an output signal from the BD sensor 10. Is used to adjust the timing of the scanning start position of image recording on the photosensitive drum surface 7.

The BD lens 8, the BD slit 9, the BD sensor 10 and other elements are synchronous position detecting means (BD
The optical system) constitutes one element.

In the present embodiment, the light beam which is optically modulated and emitted from the light source means 1 in accordance with the image information is converted into a substantially parallel light beam by the collimator lens 2, enters the cylindrical lens 3, and the cross section of the light beam is converted by the aperture stop 4. The size is determined. The light flux that has entered the cylindrical lens 3 exits as it is in the main scanning cross section. Further, in the sub-scanning cross section, they converge and form a substantially linear image (a linear image elongated in the main scanning direction) on the deflection surface 5a of the optical deflector 5. The light beam reflected and deflected by the deflecting surface 5a of the optical deflector 5 is imaged in a spot shape on the photosensitive drum surface 7 by the two scanning lenses 6, and the optical deflector 5 is rotated in the direction of arrow A. , Arrow B on the photosensitive drum surface 7
Optical scanning is performed at a constant speed in the direction (main scanning direction). As a result, an image is recorded on the photosensitive drum surface 7, which is the recording medium.

At this time, in order to adjust the timing of the scanning start position on the photosensitive drum surface 7 before optically scanning the photosensitive drum surface 7, a part of the light beam reflected and deflected by the optical deflector 5 is BD lens. After being condensed on the surface of the BD slit 9 via 8, the light is guided to the BD sensor 10. Then, the timing of the scanning start position of image recording on the photosensitive drum surface 7 is adjusted using the synchronization signal (BD signal) obtained by detecting the output signal from the BD sensor 10.

2 and 3 show a perspective view and a sectional view of the composite anamorphic lens 61 in the present embodiment.

The composite anamorphic lens 61 is made of a plastic material in which the cylindrical lens 3 and the BD lens 8 are integrated, and achieves downsizing and cost reduction. The cylindrical lens 3 has a refracting power in the sub-scanning direction, and is composed of a refracting surface and a diffracting surface. This is to compensate for a change in the focal line image forming position due to a change in the environment.

The BD lens 8 is composed of an anamorphic lens having different refracting powers in the main scanning direction and the sub-scanning direction, and slits the light beam deflected by the deflecting surface in the main scanning direction.
Imaged in the vicinity of 9.

In FIG. 2, the compound anamorphic lens 6
The optical axis 3a of the cylindrical lens 3 of 1 is made non-parallel to the optical axis 2a of the collimator lens, and prevents the light quantity of the light source from changing due to surface reflection. further,
The compound anamorphic lens 61 is a cylindrical lens.
In order to adjust the manufacturing error of 3 and the position shift of the focal line due to the wavelength variation of the light source 1, there is a positioning part 100 parallel to the BD lens optical axis 8a, and this positioning part 100 is formed in the optical box. The compound anamorphic lens 61 is movable in the direction of arrow AA ′ along the guide 200 parallel to the BD lens optical axis 8a. When the compound anamorphic lens 61 is moved in parallel with the BD lens optical axis 8a, the luminous flux incident on the cylindrical lens 3 is at the intersection 1 of the cylindrical lenses.
Although moving from 1 to 12, since the cylindrical lens has no power in the main scanning direction, the light ray does not exit the cylindrical lens with the angle of view.

Positioning part of compound anamorphic lens 61
100 and the guide part 200 of the optical box are configured to be parallel to the cylindrical lens optical axis 3a and moved, as described above, the optical axis 8a of the BD lens becomes the optical axis of the BD optical system (slit 9 in the main scanning section). And (orthogonal / matches 8a in FIG. 3), which is not preferable because the write start position on the non-scanning surface shifts. In other words, when moving the cylindrical lens 3 in the optical axis direction, the compound anamorphic lens 61
It is preferable to move the BD lens parallel to the reference portion 100 which is parallel to the optical axis 8a.

In this embodiment, the angle α between the collimator lens optical axis and the cylindrical lens optical axis is α = 30 ′, and the collimator focal length f = 17 mm. In general, when the focal length of the collimator lens is f and the tilt angle is θ, it is preferable to configure 0.8>2fθ> 0.08. The angle formed by the optical axis of the collimator lens and the optical axis of the BD lens is 10 °.

Although the optical axis of the collimator lens and the optical axis of the cylindrical lens are tilted in the main scanning direction in this embodiment, the same effect can be obtained by tilting in the sub scanning direction. As described above, in the present embodiment, in the scanning optical device using the composite anamorphic lens as described above, by providing the reference portion parallel to the optical axis of the BD lens, the cylindrical lens is moved in the optical axis direction so that the image writing position does not change. By adjusting the optical axis of the collimator lens and the optical axis of the cylindrical lens to be tilted, it is possible to prevent the reflected light from the surface of the cylindrical lens from returning to the vicinity of the laser emission point, and to prevent uneven density. It is possible to obtain a high-quality and small-sized optical scanning device that does not have any problem.

(Embodiment 2) FIG. 4 shows a main-scan sectional view of Embodiment 2 of the present invention. In the present embodiment, the conventional compound anamorphic lens 45 shown in FIG. 5 is rotated counterclockwise by an angle β with an axis passing through the midpoint 33 of the front and rear principal points of the BD lens 48 in the main scanning direction and being perpendicular to the paper surface. The same effect as that of the first embodiment is obtained by arranging and rotating.

The composite anamorphic lens 25 has a reference surface 26 parallel to the optical axis 34a of the BD lens 25, and is brought into contact with the guide 27 by an elastic member (not shown). The guide 27 is integrally formed with an optical box (not shown) so as to be parallel to the reference plane 26, and the compound anamorphic lens 25 can move along the guide 27 in the arrow AA ′ direction.

The angle formed by the collimator lens optical axis 22a and the cylindrical lens optical axis 23a is β = 20 '(=
0.006 radian), and the collimator focal length of the collimator lens 22 is f = 30 mm, which satisfies 0.8 mm>2fθmm> 0.08 mm as in the first embodiment.

FIG. 6 is a main-scan sectional view showing a comparative example with the second embodiment, in which the conventional compound anamorphic lens 45 shown in FIG. It is arranged by rotating it counterclockwise.
At this time, the midpoint 36 of the front and rear principal points of the BD lens 37 in the main scanning direction does not coincide with the optical axis 37a of the BD optical system, and the distance δ
Only located far away. Therefore, the timing at which the light is guided to the BD sensor 38 is shifted by a time substantially proportional to the tilt angle β, and the writing position of the scanning line on the image is shifted.

FIG. 7 shows a state in which the compound anamorphic lens 25 is moved along the guide 27 from the state shown in FIG. 4 by η in the direction of the optical axis 34a of the BD lens 28 (direction of arrow A). . In FIG. 7, the moving amount of the compound anamorphic lens is exaggerated for easy understanding. The actual movement amount is η = 0.2 mm or less. The outer shape of the composite anamorphic lens after the movement is omitted in the figure. With the movement of the compound anamorphic lens 25, the midpoint 33 of the front and rear principal points of the BD lens 28 in the main scanning direction moves to the point 40, and a deviation of a distance λ occurs between the point 40 and the optical axis 28a of the BD optical system. However, in the case of the present embodiment, since λ = 0.5 μm or less, the deviation amount of the writing start position is minute and can be ignored.

According to the second embodiment, since the collimator optical axis and the cylindrical lens optical axis are arranged to be inclined,
The same effect as that of the first embodiment can be obtained.

The compound anamorphic lens is a BD
In order not to change the angle of the light beam entering the slit, B
Since the center of the front and rear principal points of the D lens in the main scanning direction is rotated about the rotation axis, the BD is rotated before and after the rotation.
There is no timing deviation when light is guided to the sensor. Therefore, the writing start position does not shift. This is because, in paraxial theory, the imaging position does not change even if the optical system is tilted with the center of the principal point as the center of rotation. For example, it is effective in the following cases. If you want to arrange the light source means at any position on the optical axis of the collimator, you can easily prevent the reflected light from the surface of the cylindrical lens from returning to the vicinity of the laser emission point by simply rotating the compound anamorphic lens at the optimum angle. The degree of freedom is increased, the optical scanning device can be downsized, and the mass productivity of the composite anamorphic lens can be improved.

(Embodiment 3) FIG. 8 shows a main-scan sectional view of Embodiment 3 of the present invention. In this embodiment, as in the second embodiment, the compound anamorphic lens is rotated counterclockwise by an angle β with the axis passing through the midpoint 55 of the front and rear principal points of the BD lens in the main scanning direction and perpendicular to the paper surface as the rotation axis. They are arranged so as to satisfy 0.8 mm>2fθmm> 0.08 mm. The guide 51 is integrally formed with an optical box (not shown) so as to be parallel to the optical axis 53a of the BD optical system.
The compound anamorphic lens 50 has a reference surface 52 and is brought into contact with the guide 51 by an elastic member (not shown). The compound anamorphic lens 50 is movable along the guide 51 in the arrow AA ′ direction.

When the compound anamorphic lens 50 moves in the direction of arrow A, the BD lens 53 moves to 54, and the midpoint 55 of the front and rear principal points of the BD lens 53 in the main scanning direction moves to 56. According to the third embodiment, since the collimator optical axis and the cylindrical lens optical axis are arranged so as to be inclined, it is possible to obtain the same effects as those of the first and second embodiments.

Further, since the compound anamorphic lens is rotated about the axis passing through the midpoint of the front and rear principal points of the BD lens in the main scanning direction and perpendicular to the plane of the drawing, the same effect as that of the second embodiment can be obtained. it can.

In this embodiment, since the compound anamorphic lens is moved in parallel to the optical axis of the BD optical system, the midpoint between the front and rear principal points of the BD lens in the main scanning direction moves on the optical axis of the BD optical system. Therefore, even if the cylindrical lens is adjusted in the optical axis direction, it is possible to provide an optical scanning device in which the writing start position does not shift at all, and it is effective when a large rotation angle β of the compound anamorphic lens 25 is set in the second embodiment. Is.

(Embodiment 4) FIG. 9 is a main-scan sectional view of Embodiment 4 of the present invention. In the figure, the same elements as those shown in FIG. 1 are designated by the same reference numerals. Further, FIG. 10 is a main-scan sectional view of the composite anamorphic lens of Embodiment 4.

The present embodiment differs from the first embodiment described above in that the compound anamorphic lens is composed of two cylindrical lenses and one BD lens. Other configurations and optical actions are substantially the same as those of the first embodiment, and similar effects are obtained.

That is, as shown in FIG. 9, light from two different light sources is made incident on the same composite anamorphic lens, and scanning is performed using different deflecting surfaces. Also in the present embodiment, when the optical axis of the collimator lens and the optical axis of the cylindrical lens are parallel to each other, the surface reflected light of the cylindrical lens returns to the light source and the amount of light becomes unstable. Therefore, the optical axis of the cylindrical lens is arranged so as to be inclined in a V shape as shown in FIG. 10 so that the surface reflected light does not return to the light source.

Also in this embodiment, the angle θ between the optical axis of the collimator lens and the optical axis of the cylindrical lens is 30 = 30 ', and the focal length of the collimator is f = 20 mm. Generally, when the focal length of the collimator lens is f and the angle of tilt is θ, 0.8>2fθ> 0.08 is satisfied.

When the distance between the two light sources is short, the compound anamorphic lens can be configured by one BD lens and one cylindrical lens to have the same configuration as that of the first embodiment, but the distance between the light sources is reduced. If they are far apart, the focal point image formation positions will differ between the left and right light sources due to the movement of the compound anamorphic lens, so it is better to have two cylindrical lenses. Further, for example, the same effect can be obtained in a composite anamorphic lens having two or more cylindrical lenses in which two light sources are further arranged in the vertical direction and four cylindrical lenses are arranged in two steps.

As described above, in the scanning optical device using the compound anamorphic lens having a plurality of cylindrical lenses, the compound anamorphic lens is rotated so that the image writing position does not change, and the compound anamorphic lens is used as the optical axis of the BD lens. It is possible to obtain a high-quality and compact optical scanning device in which the writing start position does not shift even when the optical scanning device is moved in the direction.

(Image Forming Apparatus) FIG. 10 is a sectional view of the main part in the sub-scanning direction showing an embodiment of the image forming apparatus of the present invention.
In the figure, reference numeral 104 indicates an image forming apparatus. Code data Dc is input to the image forming apparatus 104 from an external device 117 such as a personal computer. This code data Dc is the printer controller 11 in the device.
By 1, the image data (dot data) Di is converted. This image data Di is input to the optical scanning unit 100 having the configurations shown in the embodiments 1 to. Then, from the optical scanning unit 100, the image data Di
A light beam 103 modulated in accordance with is emitted, and the light beam 103 scans the photosensitive surface of the photosensitive drum 101 in the main scanning direction.

The photosensitive drum 101, which is an electrostatic latent image carrier (photoconductor), is rotated clockwise by a motor 115. Then, along with this rotation, the photosensitive drum 101
Of the light beam 103 moves in the sub-scanning direction orthogonal to the main scanning direction with respect to the light beam 103. A charging roller 102 for uniformly charging the surface of the photosensitive drum 101 is provided above the photosensitive drum 101 so as to contact the surface.
Then, the surface of the photosensitive drum 101 charged by the charging roller 102 is irradiated with the light beam 103 scanned by the optical scanning unit 100.

As explained above, the light beam 103 is
The light beam 103 is modulated based on the image data Di, and an electrostatic latent image is formed on the surface of the photosensitive drum 101 by irradiating the light beam 103. This electrostatic latent image is more sensitive to the photosensitive drum 101 than the irradiation position of the light beam 103.
Is developed as a toner image by the developing device 107 arranged so as to come into contact with the photosensitive drum 101 on the downstream side in the rotation direction of.

The toner image developed by the developing device 107 is transferred below the photosensitive drum 101 onto a sheet 112 as a transfer material by a transfer roller 108 arranged so as to face the photosensitive drum 101. The sheet 112 is stored in the sheet cassette 109 in front of the photosensitive drum 101 (on the right side in FIG. 3), but can be manually fed. At the end of the paper cassette 109, the paper feed roller 11
0 is arranged, and the paper 11 in the paper cassette 109 is
2 is sent to the transport path.

As described above, the sheet 112 to which the unfixed toner image is transferred is further conveyed to the fixing device behind the photosensitive drum 101 (on the left side in the drawing). The fixing device is composed of a fixing roller 113 having a fixing heater (not shown) inside and a pressure roller 114 arranged so as to be in pressure contact with the fixing roller 113, and the sheet conveyed from the transfer section. 112 is a fixing roller 113 and a pressure roller 114
The paper 11 is heated by applying pressure at the pressure contact portion of the paper 11.
The unfixed toner image on 2 is fixed. Further, a paper discharge roller 116 is disposed behind the fixing roller 113,
The fixed paper 112 is ejected outside the image forming apparatus.

Although not shown in the figure, the print controller 111 not only converts the explanation data first, but also includes the motor 115 and other parts in the image forming apparatus and a polygon motor in an optical scanning unit described later. Take control.

[0059]

According to the present invention, as described above, in the optical scanning device using the composite anamorphic lens in which the cylindrical lens and the BD lens are integrally formed, the optical axis of the collimator lens and the optical axis of the cylindrical lens are made non-parallel. In addition to preventing surface reflected light, the composite anamorphic lens is adjustable in the optical axis direction of the BD lens to achieve a high-quality, compact optical scanning device with no density unevenness and no change in the writing position. can do.

Further, according to the present invention, it is possible to reduce color unevenness and color shift which occur in a color image forming apparatus having a plurality of optical scanning devices.

[Brief description of drawings]

FIG. 1 is a main scanning sectional view of an optical scanning device according to a first embodiment.

FIG. 2 is a perspective view of the composite anamorphic lens of the first embodiment.

FIG. 3 is a layout diagram of a composite anamorphic lens according to the first embodiment.

FIG. 4 is a layout view of a composite anamorphic lens according to the second embodiment.

FIG. 5: Layout of a conventional composite anamorphic lens

FIG. 6 is a view of a conventional compound anamorphic lens tilted.

FIG. 7 is a layout drawing after moving the compound anamorphic lens of the second embodiment.

FIG. 8 is a layout view of a composite anamorphic lens according to the third embodiment.

FIG. 9 is a main-scan sectional view of the fourth embodiment.

FIG. 10 is a layout diagram of a composite anamorphic lens according to a fourth embodiment.

FIG. 11 Conventional optical scanning device

FIG. 12 is an image forming apparatus of the present invention.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C362 AA43 AA49 BA04 BA84 BA86                       BA89 DA28                 2H045 CA03 CA89 CB24 CB63 DA02                 5C051 AA02 CA07 DB22 DB30                 5C072 AA03 DA02 DA21 HA02 HA09                       HA13 HB08 XA05

Claims (8)

[Claims] 1. A light source means and a first optical system for converting a light beam emitted from the light source into substantially parallel light and a light beam passing through the first optical system as a long line image in the main scanning direction. In an optical scanning device including an optical system, a deflector as a deflecting unit, and a third optical system for detecting a writing position, the second optical system is formed integrally with a third optical element. The optical axis of the second optical system is inclined with respect to the optical axis of the first optical system, and has a positioning portion parallel to the optical axis of the third optical system. Scanning device. 2. A light source means, a first optical system for converting a light beam emitted from the light source into substantially parallel light, and a light beam passing through the first optical system as a long line image in the main scanning direction. Optical system, a deflector as a deflecting unit, a third optical system for detecting the writing position, and a detecting unit for detecting the writing position, and the second optical system and the third optical system. In an optical scanning device including an optical element integrally formed with an optical system, the optical system passes through a point between the front and rear principal points in the main scanning direction of the third optical system, and the third optical system and the second optical system. The third optical system is rotated about an axis perpendicular to a plane including the optical axis of the system, and the third optical system is rotated with respect to an axis connecting a point between the front and rear principal points in the main scanning direction and the detecting means. The optical axis of the optical system is tilted, and the optical axis of the first optical system and the optical axis of the second optical system Optical scanning apparatus characterized that the shaft is arranged to be inclined in the main scanning direction. 3. An inclination angle θ between the optical axis of the second optical system and the optical axis of the first optical system is 0.8>2fθ> 0.08 f: The focal length of the second optical system The optical scanning device according to claim 1 or 2, wherein the condition is satisfied. 4. The first and second optical systems according to claim 1, wherein the second and third optical systems are configured to be movable in parallel with an optical axis of the third optical system. Optical scanning device. 5. The second and third optical systems are configured to be movable parallel to an axis connecting a point between the front and rear principal points in the main scanning direction and the detection means. The optical scanning device according to claim 1 or claim 2. 6. The optical scanning device according to claim 1, wherein the second and third optical systems are molded lenses. 7. The scanning optical device according to claim 1, a photoconductor disposed on the surface to be scanned, and a light beam scanned by the scanning optical device onto the photoconductor. A developing device for developing the formed electrostatic latent image as a toner image, a transfer device for transferring the developed toner image onto a transfer material, and a fixing device for fixing the transferred toner image on the transfer material. Image forming apparatus equipped. 8. A scanning optical device according to any one of claims 1 to 7, and a printer controller for converting code data input from an external device into an image signal and inputting the image signal into the scanning optical device. Image forming apparatus.