JPS62240913A - Holding structure for anamorphic optical element - Google Patents

Abstract

PURPOSE:To easily execute turning and movement by attaching a cylindrical lens barrel to a substrate freely turnably in the periphery of its center line, and so as to be freely movable in the direction of the center line, and fitting an eccentric pin which has been attached to the substrate freely rotatably, to an annular groove which has been formed on the peripheral surface. CONSTITUTION:A cylindrical lens 3 is held by a cylindrical holder 9, and the holder 9 is fitted into an eccentric fitting hole 10a of a cylindrical lens barrel freely turnably in the periphery of a center line P1 being parallel to an optical axis X of a laser beam B. This cylindrical lens barrel 10 is attached to a substrate 11 freely turnably in the periphery of its center line P2 being parallel to the optical axis X of the laser beam B. That is, by turning the lens barrel 10 against the substrate 11, the holder 9 which has been fitted into its eccentric fitting hole 10a turns in the periphery of the center line P2 of the lens barrel 10. In this way, the cylindrical lens 3 is orthogonal to the optical axis X, respectively, and also, moves in two directions being orthogonal to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a holding structure for an anamorphic optical element, which holds an anamorphic optical element such as a cylindrical lens so that its mounting position can be adjusted.

[Conventional technology]

As a holding structure for such an anamorphic optical element, for example, a holder that holds a cylindrical lens,
It is known that the mounting position of the cylindrical lens can be adjusted by moving the cylindrical lens in a direction perpendicular to the generatrix and optical axis of the cylindrical lens using a feed screw mechanism linked to an operating tool (for example, Japanese Patent Laid-Open No. Showa 57
(Refer to Publication No.-35825).

[Problem that the invention seeks to solve]

Anamorphic optical elements such as cylindrical lenses have various uses.

For example, a cylindrical lens is sometimes used for correcting a laser beam from a semiconductor laser in laser application equipment such as a laser beam printer. In this case,
If the direction of the generatrix of the cylindrical lens does not match the direction of the cemented surface of the semiconductor laser, the laser beam will not be sufficiently corrected. Therefore, a situation occurs in which the shape of the spot of the irradiated laser beam does not become a perfect circle.

Further, a cylindrical lens is sometimes used in an optical scanning device installed in a laser beam printer or the like to correct errors caused by tilting of each reflective surface of a polygon mirror for scanning a laser beam. In this case, the direction of the generating line of the cylindrical lens that converges the laser beam into a line on the reflective surface of the polygon mirror, and the direction of the generatrix of the cylindrical lens (sometimes a toroidal lens) that makes the laser beam parallel again after being reflected on the reflective surface If the direction of the generatrix of the laser beam (a lens is also used) is not completely aligned, the laser beam will be distorted and imaged on the object to be scanned, such as a photoreceptor. Therefore, when such a situation occurs, image deterioration may occur in a recording device such as a laser beam printer.

In other words, since the power of the anamorphic optical element has directionality, it is necessary to control the mounting direction around the optical axis. However, in the case of the conventional configuration described above, since the cylindrical lens, which is an anamorphic optical element, is not configured to rotate around its optical axis, the mounting member for the cylindrical lens must be made with high precision, and The installation around the optical axis had to be done with precision.

For example, when used to correct the inclination of the reflective surface of a polygon mirror in the laser beam printer mentioned above, in order to accurately image the laser beam on the reflective surface of the polygon mirror, an anamorphic optical element is required. It is necessary to position the lens in the optical axis direction, and similarly, manufacturing accuracy and mounting accuracy are required. Therefore, as a whole, there was a problem that it took time and effort to attach the parts and that the cost would increase in the future.

In view of the above-mentioned circumstances, an object of the present invention is to move an anamorphic optical element in a direction orthogonal to its generatrix and optical axis, rotate around the optical axis, and move in the optical axis direction.
The aim is to make all of these operations easy to operate.

[Means for solving problems]

The characteristic configuration of the holding structure for an anamorphic optical element according to the present invention is that a cylindrical holder for holding an anamorphic optical element is attached to an eccentric fitting part of a cylindrical lens barrel so as to be rotatable around its center line, and the cylindrical holder A shaped lens barrel is attached to a substrate so as to be freely rotatable around its center line and movable in the direction of the center line, and an annular groove formed on the circumferential surface of the cylindrical lens barrel is attached.
The problem lies in that an eccentric pin rotatably attached to the substrate is fitted.

[For production]

That is, by rotating the cylindrical lens barrel with respect to the substrate, the cylindrical holder attached to the eccentric fitting part rotates around the center line of the cylindrical lens barrel. This allows the anamorphic optical element held in this holder to
It moves in a direction perpendicular to both the generatrix and the optical axis. At this time, the anamorphic optical element also moves in the direction of its generatrix, but there is no need to adjust it in this direction because the power in the direction perpendicular to the generatrix is the same at any position.

After aligning the optical axis with the generatrix of the anamorphic optical element through the above operation, the anamorphic optical element is rotated around the optical axis by rotating the cylindrical holder relative to the eccentric fitting part. . Further, by rotating the eccentric pin with respect to the substrate, a force in the optical axis direction is applied to either side of the annular groove into which the eccentric pin fits. As a result, the cylindrical lens barrel moves in the optical axis direction, and the anamorphic optical element also moves in the optical axis direction.

〔Example〕

The present invention will be described in detail below based on the drawings.

FIG. 1 shows a schematic configuration of a scanning device of a laser beam printer. The laser beam (B) modulated based on input image information and oscillated from the semiconductor laser (1) is
A polygon mirror (4) that is collimated by a collimator lens (2), converged into a line along its generatrix direction by a cylindrical lens (3), and rotates at high speed.
is reflected by the reflective surface. As the polygon mirror (4) rotates, the inclination of its reflecting surface with respect to the laser beam (B) changes, and accordingly, the reflected laser beam (B) is transferred to the photoreceptor drum (5), which is an example of a photoreceptor. ) (this direction is the main scanning direction).

This laser beam (B) passes through a toroidal lens (6), is focused by an fθ lens (7), and forms an image on the uniformly charged photoreceptor drum (5) to increase the charging potential at that position. reduce By repeating this scanning as the photoreceptor drum (5) rotates at a constant speed, an electrostatic latent image is formed on the photoreceptor drum (5). Note that (8) in the figure is a laser beam detection optical sensor for aligning each scanning start position with respect to the rotation direction of the photosensitive drum (5) (this direction is the sub-scanning direction).

Thereafter, although not shown, toner, which is a colored pigment, is selectively attached to this electrostatic latent image area and developed, and output paper is adhered to the toner image surface to transfer the toner image onto the paper surface. The heat melts the toner and fixes it on the paper, creating an output image.

In this scanning device, a cylindrical lens (3) and a toroidal lens (6) are provided to correct inclination errors of the reflective surface of the polygon mirror (4). That is, each reflective surface of the polygon mirror (4) has a slight tilt error with respect to its center of rotation due to manufacturing errors, mounting errors, or vibrations accompanying its rotation. and,
Due to this tilt error, the reflected laser beam (B)
A phenomenon occurs in which the image is shifted in the sub-scanning direction, which may cause image deterioration in the future.

Therefore, the laser beam (B) made parallel by the collimator lens (2) is once converged in the thickness direction of the polygon mirror (4) by the cylindrical lens (3), and then the laser beam (B) is made parallel by the collimator lens (2). By configuring the reflected laser beam (B) to be returned to its original state by the toroidal lens (6), the laser beam (B) can be It is configured so that the same line is always scanned on the photosensitive drum (5).

In this scanning device, the cylindrical lens (3) is aligned with the optical axis (X) so that the laser beam (B) is accurately imaged by the cylindrical lens (3) on the reflective surface of the polygon mirror (4). It is provided so that the position can be adjusted in the direction.

In addition, by matching the direction of the generatrix of the cylindrical lens (3) and the direction of the generatrix of the toroidal lens (6), it is possible to prevent the shape of the spot on the photoreceptor (5) from becoming distorted. , the cylindrical lens (3) is provided so that its position around the optical axis (X) can be adjusted.

Next, the mounting structure of this cylindrical lens (3) will be explained.

As shown in Fig. 1, a cylindrical lens (3), which is an example of an anamorphic optical element, is attached to a cylindrical holder (
9) is maintained. And this holder (9) is
The center line of the laser beam (B) parallel to the optical axis (X)
Pl) is fitted into an eccentric fitting hole (10a) of a cylindrical lens barrel (10) so as to be rotatable around Pl. This cylindrical lens barrel (10) is connected to the optical axis (X) of the laser beam (B).
It is attached to the base plate (11) so as to be rotatable around its center line (P2) parallel to .

In other words, by rotating this lens barrel (10) with respect to the substrate (11), the holder (9) fitted into the eccentric fitting hole (10a) can be moved along the center line of the lens barrel (10) ( P2) Rotate around. As a result, the cylindrical lenses (3) are arranged in two directions, each of which is perpendicular to the optical axis (X) and which is orthogonal to each other.
It will move in one direction.

With this operation, the generatrix (L) of the cylindrical lens (3)
One point on the top can be located on the optical axis (X).

Furthermore, in this state, the holder (9) is inserted into the eccentric fitting hole (10).
By rotating with respect to a), the cylindrical lens (3) can be rotated around the optical axis (X).

That is, by the above-mentioned series of operations, the cylindrical lens (3
), its generatrix (L) and the optical axis (X
), positional adjustment in the direction perpendicular to the optical axis (X) and positional adjustment around the optical axis (X) are performed. At this time, the cylindrical lens (3) will also move in the direction of its generatrix (L), but in this direction, there is no difference in power in the direction perpendicular to the generatrix (L) at any position. , no need to adjust.

Furthermore, the outer peripheral surface (fob) of the cylindrical lens barrel (10) has an annular shape. ! (10c) is formed, and this annular groove (
10c) is fitted with an eccentric pin (12) rotatably attached to the substrate (11). This eccentric bin (12
), this eccentric bottle (12) rotates eccentrically around the center of attachment to the substrate (11), and the lens barrel is attached to the side surface of the groove (10c) of the lens barrel (10). A force in the direction of the center line (P2) of (10) acts, and the lens barrel (10) moves in this direction.

That is, by rotating the eccentric bin (12), the optical axis (X
) direction is adjusted. Then, the above-mentioned two positional adjustments of the cylindrical lens (3) are performed, namely, the positional adjustment in the direction orthogonal to its generatrix (L) and the optical axis (X) of the laser beam (B), and the positional adjustment around the optical axis (X). After performing a total of three positional adjustments: the positional adjustment at , and the positional adjustment in the optical axis (X) direction described above, by tightening the fixing screw (13) that is screwed onto the board (11), The position of the cylindrical lens (3) is fixed.

Note that the cylindrical holder (9) holding the cylindrical lens (3) may be fitted externally into the eccentric cylindrical protrusion instead of fitting internally into the eccentric fitting hole (10a). Offset from the center line (P2) of the lens barrel (10), the holder (
9) is connected to the eccentric fitting part (10a
).

Furthermore, the anamorphic optical element holding structure according to the present invention can be used not only in the optical system for correcting the tilting error of the polygon mirror (4) in the laser beam printer described in the previous embodiment, but also in laser beam printers and various laser application devices. It is possible to apply the present invention to an optical system that shapes a laser beam from a semiconductor laser, and further to an optical system of an anamorphic variable magnification copying device that performs copying with different vertical and horizontal magnifications.

〔Effect of the invention〕

As described above, the anamorphic optical element holding structure according to the present invention can move the anamorphic optical element in a direction perpendicular to its generatrix and optical axis, rotate around the optical axis, and Movement in any direction can be performed with simple operations, and the WI can be easily adjusted after installing each component without requiring high manufacturing or installation accuracy. Because it is possible to do so, it requires less effort during installation, and it has also become possible to reduce the cost of the product.

[Brief explanation of drawings]

The drawings show an embodiment of a holding structure for an anamorphic optical element according to the present invention, FIG. 1 is a perspective view showing a mounting structure for a cylindrical lens, and FIG. 2 is a schematic configuration diagram of a scanning device of a laser beam printer. (3)...Anamorphic optical element, (9)...
...Holder, (10) ... Lens barrel, (10
a)...Eccentric fitting part, (10c)...
Annular groove, (11)...Substrate, (12)...
... Eccentric bottle, (Pl) ... Center line of holder,
(P2)... Center line of the lens barrel.

Claims (1)

[Claims] A cylindrical holder that holds an anamorphic optical element.
The cylindrical lens barrel is attached to the eccentric fitting part of the cylindrical lens barrel so as to be rotatable around its center line, and the cylindrical lens barrel is attached to the substrate so as to be rotatable around the center line and movable in the direction of the center line. A holding structure for an anamorphic optical element, wherein an eccentric pin rotatably attached to the substrate is fitted into an annular groove formed on the circumferential surface of a cylindrical lens barrel.