JPH10253914A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical scanning that has no deviation of scanning position, is good in image forming characteristic, and that can optically scan with a minute spot diameter, by attaching a cylindrical lens to an optical axis adjusting device moving the lens in a direction vertical to an optical axis and the generatix of the lens. SOLUTION: The light beam emitted from a light source 1 is made parallel beams by a collimating lens 2 to pass through the cylindrical lens 3 inserted for a plane tilt compensation to be deflectingly scanned with a rotary polygon mirror 4 and the beams are converged on a photosensitive body 6 with an f-theta lens 5. The variation between the height of the generatrix of the lens 3 and the height of optical axes of light beams due to the manufacturing error of the lens 3 and the manufacturing error of its holding base is adjusted by moving the lens 3 in the vertical direction with an optical axis adjusting device 17. Thus, the height of the generatrix of the lens 3 and the height of the light beams become the same and since the light beams advance toward the center part of the lens 5, a beam spot in which the deviation of scanning position is not present and the curvature of scanning line is not present also and whose diameter is minute and which is stabilized is obtained.

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 used for a laser beam printer, a copying machine, and the like, and more particularly to an optical axis adjustment of a cylinder lens and an F.theta. Lens of the optical scanning device.

[0002]

2. Description of the Related Art A schematic view of a conventional laser beam printer is shown in FIG. Light is generated from a light source 1 such as a semiconductor laser, and the light is collimated by a collimator lens 2. Thereafter, the light passes through the cylinder lens 3 inserted for correcting the tilt of the rotary polygon mirror, and is deflected and scanned by the rotary polygon mirror 4.
Thereafter, the light passes through the Fθ lens 5 and is narrowed down on the photoconductor 6. Adjustment with the conventional optical scanning device includes adjusting the collimator lens 2 in the optical axis direction, the cylinder lens 3 in the optical axis direction, the cylinder lens 3 in a rotation direction about the optical axis, and the Fθ lens 5 in the optical axis direction. Had to move.

[0003]

The above prior art has the following drawbacks.

The distance between the generatrix of the cylinder lens 3 and the bottom surface, that is,
When the value of “a” shown in FIG.
If the distance between the holding surface of the cylinder lens 3 and the bottom surface of the lens holder, ie, the value of c shown in FIG. 3, varies due to the manufacturing error of the above, the distance between the generatrix of the cylinder lens 3 and the bottom surface of the lens holder, ie, FIG. Will vary. In addition, the height of the light beam 8 shown in FIG. 4 may vary due to an arrangement error of the light source 1 and the collimator lens 2. As described above, if the arrangement of the cylinder lens 3 and the position of the light incident thereon vary, a problem arises in that the height of the optical axis and the height of the generatrix of the cylinder lens 3 are different.

FIG. 4 is an optical path diagram of the optical scanning device, and FIG. 5 is a diagram showing a state where the arrangement of the cylinder lens 3 is shifted. As shown in FIG. 5, when the light emitted from the cylinder lens 3 is bent, the light does not pass through the center of the Fθ lens 5, causing a problem that the scanning position on the photoconductor 6 is shifted. Further, when the imaging magnification is different between the central scanning portion and the peripheral scanning portion of the Fθ lens 5, there is a problem that the scanning line is curved. In addition to these, since light does not pass through the center of the Fθ lens, it is more susceptible to lens aberrations and the like, deteriorating imaging characteristics, and making it impossible to reduce the spot diameter to an appropriate size. I do.

[0006] Even if there is an error in the arrangement and manufacturing of the Fθ lens 5, the same problem as described above will occur. FIG. 6 is a view of the state in which the Fθ lens 5 is on the lens holder 9 as viewed from the rotary polygon mirror 4 side. F
If the distance between the Fθ lens and the bottom surface, that is, the size of d or e in FIG.
0 and the center line 11 of the Fθ lens 5 are shifted. Similarly, the distance between the lens holding surface and the bottom surface of the lens holding table 9, that is, f and g in FIG. I will.

The center line 11 of the Fθ lens 5 and the light scanning surface 10
The same problem as that in the case where the cylinder lens 3 is displaced occurs when the displacement is parallel or oblique.

[0008]

In order to solve the above problem, in an optical scanning device, a cylinder lens is mounted on an optical axis adjusting device for moving the cylinder lens in a direction perpendicular to an optical axis and a generatrix of the cylinder lens. .

[0009]

FIG. 1 shows an embodiment of the present invention. Light is generated from a light source 1, and the light is collimated by a collimator lens 2. Thereafter, the light passes through a cylinder lens 3 inserted for correcting surface tilt, and is deflected and scanned by a rotating polygon mirror 4. After that, the aperture is narrowed down on the photoconductor 6 by the Fθ lens 5. Due to the manufacturing error of the cylinder lens 3 and the manufacturing error of the holding table, the height of the generating line of the cylinder lens 3
Even if the height of the optical axis 8 of the light fluctuates, the height can be adjusted by moving the cylinder lens 3 in the vertical direction with the optical axis adjusting device 17. In the same manner, since light travels to the center of the Fθ lens 5, there is no scanning position deviation, no scanning line bending, and a minute stable beam spot can be obtained. FIG. 7 shows an example of the optical axis adjusting device 17. Pedestal 25
The male screw part 22 is rotated by the motor 20 fixed to. This is a structure in which the pin 23 is moved in and out by moving in and out of the fixed female screw portion 21, and the lens holder 24 moves up and down.

Next, the case of the Fθ lens 5 will be described. The optical axis adjusting device for moving the Fθ lens 5 perpendicular to the optical scanning surface and the Fθ lens 5 in the direction perpendicular to the optical scanning surface is as shown in FIG. 8, and is realized by the same configuration as the optical axis adjusting device for the cylinder lens 3. It is possible. Reference numeral 17 in FIG. 8 denotes an optical axis adjustment device.

An optical axis adjusting device for rotating the Fθ lens 5 about the optical axis is as shown in FIG.
Are arranged at both ends of the Fθ lens 5, and one of the optical axis adjusting devices 17 is moved upward and the other is moved downward, so that the rotation of the Fθ lens 5 about the optical axis is adjusted.

In this embodiment, a motor is used.

[0013]

As described above, according to the present invention, the optical axis adjusting device for the cylinder lens 3 or the Fθ lens 5 is provided even if there is a manufacturing error or an arrangement error of the Fθ lens 5 or the cylinder lens 3. Since the optical axis and the lens generatrix can be made to coincide with each other with high accuracy, it is possible to realize optical scanning with a small spot diameter having no scanning position deviation and good imaging characteristics.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing a conventional example of an optical scanning device.

FIG. 3 is a schematic view of a cylinder lens.

FIG. 4 is a schematic diagram showing a good state of a conventional optical scanning device.

FIG. 5 is a schematic diagram showing a bad state of a conventional optical scanning device.

FIG. 6 is an explanatory diagram of an arrangement error of an Fθ lens.

FIG. 7 is a schematic view showing an optical axis adjusting device.

FIG. 8 is a perspective view showing another embodiment of the present invention.

FIG. 9 is a perspective view showing another embodiment of the present invention.

[Explanation of symbols]

1 is a light source such as a laser, 2 is a collimator lens, 3 is a cylinder lens, 4 is a rotating polygon mirror, 5 is an Fθ lens, 6
Is a photoreceptor, 7 is a lens holder, 8 is an optical axis, 9 is a lens holder, 10 is an optical scanning surface, 11 is a center line of the Fθ lens, 1
7 is an optical axis adjusting device, 20 is a motor, 21 is a female screw, 22
The figure shows a male screw, 23 pins, a 24 lens holder, and 25 pedestals.

Claims (3)

[Claims] 1. A light source, a rotary polygon mirror for deflecting and scanning light from the light source onto a photoreceptor, a collimator lens between the light source and the rotary polygon mirror for collimating the light from the light source, and a facet of the rotary polygon mirror An optical scanning device comprising: a cylinder lens for performing correction; and an Fθ lens which is located between the rotating polygon mirror and the photoconductor and narrows down the light from the light source to the entire printing area of the photoconductor with a uniform diameter. An optical scanning device, wherein the optical scanning device is mounted on an optical axis adjustment device that moves a cylinder lens in a direction perpendicular to a cylinder line and a generatrix of the cylinder lens. 2. A light source, a rotary polygon mirror for deflecting and scanning light from the light source on a photoreceptor, a collimator lens between the light source and the rotary polygon mirror for collimating the light from the light source, and a facet of the rotary polygon mirror In an optical scanning device comprising a cylinder lens for performing correction and an Fθ lens which is located between the rotary polygon mirror and the photoreceptor and narrows down the light from the light source to the entire printing area of the photoreceptor with a uniform diameter, the Fθ lens is optically scanned. An optical scanning device mounted on an optical axis adjustment device that moves an Fθ lens in a direction perpendicular to a surface. 3. A light source, a rotary polygon mirror for deflecting and scanning light from the light source onto a photoreceptor, a collimator lens between the light source and the rotary polygon mirror for collimating the light from the light source, and a facet of the rotary polygon mirror An optical scanning device comprising: a cylinder lens for performing correction; and an Fθ lens which is located between the rotary polygon mirror and the photoconductor and narrows down the light from the light source to the entire printing area of the photoconductor with a uniform diameter. An optical scanning device, wherein the optical scanning device is mounted on an optical axis adjustment device that rotates an Fθ lens around the center.