JPH09127392A - Optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the deformation of a contact part, lessen expansion restraint in the length direction where linear expansion is large, and suppress deformation due to a restraining force received from a holding member at the time of linear expansion by decentralizing the load of the contact part on an optical element. SOLUTION: This device has a reflection type optical element 1 and a holding member 2 for the reflection type optical element 1 and the reflection type optical element 1 and holding member 2 are brought into linear, multipoint, or surface contact with each other. When the contact part is made linear, the contact part is nearly parallel to the length direction of the reflection type optical element 1. The contact part of the holding member 2 for the reflection type optical element 1 may have both arcuate end parts along the length of the reflection type optical element 1 and the contact part of the reflection type optical element for the holding member 2 may have both its end parts undercut from the holding member 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device using a reflection type optical element having an image forming characteristic, and more particularly to a mounting structure of the reflection type optical element, for example, a digital copying machine (DPPC), a laser printer (LP). ) Is applicable to the optical scanning device.

[0002]

2. Description of the Related Art In optical scanning devices used in digital copying machines and laser printers, reflective optical elements having image forming characteristics are used. FIG. 8 shows an example of a known optical scanning device using a reflection type optical element having an image forming characteristic. In FIG. 8, a laser beam 3 emitted from a semiconductor laser 5 as a light emitting device is linearly converged on a reflecting surface of a polygon mirror 6 as an optical scanning means by passing through a cylindrical lens 10. The polygon mirror 6 is rotationally driven at a constant speed, and the laser beam 3 is deflected by each reflection surface of the polygon mirror 6 within a constant angle range.

The laser beam deflected by the polygon mirror 6 is reflected by the reflecting surface 1a of the reflective optical element 1 having an image forming property toward the polygon mirror 6, but obliquely downward in the figure, and further by the plane mirror 7. It is folded back in the horizontal direction, and is formed as a minute spot on the surface of the drum-shaped photosensitive member 9 through the cylindrical lens (or barrel toroidal lens) 8. The minute spot is scanned in the main scanning direction on the surface of the photoconductor 9 by deflecting the laser beam 3 by the polygon mirror 6. A small mirror 11 for guiding the laser beam 3 deflected by the polygon mirror 6 to the synchronization detection unit 12 is arranged on the side of the reflection type optical element 1.

The polygon mirror 6 is driven to rotate counterclockwise in FIG. 8, and accordingly, the laser beam 3 scans the surface of the photosensitive member 9 from right to left in FIG. At the start of scanning line by line, the laser beam 3 deflected by the polygon mirror 6 is reflected by the mirror 11 and guided to the synchronization detector 12, and a synchronization signal is output. By inputting a writing signal to the semiconductor laser 5 in synchronization with this synchronizing signal, writing is performed line by line at a predetermined position on the surface of the photoconductor 9. Further, the sub-scanning is performed by rotating the photoconductor 9 by a predetermined minute angle each time writing is performed line by line. In this way, a latent image is formed on the surface of the photoconductor 9. The photoconductor 9 on which the latent image is formed is subjected to a predetermined electrophotographic process such as development with toner, transfer / separation to / from copy paper, cleaning, and charge removal.

In the above-mentioned optical scanning device, the role of the reflection type optical element 1 is simply to guide the light beam to the surface of the photoconductor 9 by geometrical optics, and about the photoconductor 9 by wave optics.
The image is formed on the surface of, and generally has the fθ characteristic in the main scanning direction. Since the mounting position accuracy of the reflective optical element 1 affects the performance of the formed image, various measures are taken in the mounting structure of the reflective optical element.

One of them is disclosed in Japanese Utility Model Application Laid-Open No. 57-63328, and a base, an optical component fixed on the base, and a plurality of detachable members on the base for positioning the optical component. A pin composed of a book, and the first surface of the optical component and the second surface intersecting with the first surface are respectively brought into contact with one or a plurality of pins, whereby The surface and the second surface are positioned.

As another conventional example of a mounting structure for general optical elements, not limited to a reflection type optical element, Japanese Patent Laid-Open No. 62-756.
There is one disclosed in Japanese Patent No. 71. This is a configuration in which a convex portion, which is a positioning member, is provided at the center of the optical element in the longitudinal direction, and the convex portion is fitted into a concave portion provided in the optical unit housing to position the optical element. , By this, the influence of the thermal expansion of the optical element is dispersed symmetrically with respect to the optical axis, and compared with the method of fixing one end of the lens,
The image performance can be improved.

As another conventional example of a general optical element mounting structure, there is a rod-shaped optical element fixing device described in Japanese Utility Model Laid-Open No. 61-109413. This is a support member having a support surface for supporting one surface of a rod-shaped optical element, an annular elastic belt hooked by a protrusion fixed to the support member to press the optical element against the support surface, A first position adjusting screw that is screwed into a screw hole provided in the support member and that adjusts the position of the optical element with respect to the support surface; and a screw receiving portion that is fixed to the support member. A second position adjusting screw for adjusting the position of the optical element with respect to the screw receiving portion is provided.

The mounting structure of the optical element described in each of the above publications belongs to a special category, and the conventional general method for holding the reflection type optical element is shown in FIGS.
This is a method of holding with a spring material such as the leaf spring 2 as shown in FIG. 9 and 10, the base 20 of an optical device such as an optical scanning device has a horizontal holding portion 16 on which horizontal planes at both ends in the length direction of the reflection-type optical element 1 are mounted and a reflection-type optical element 1. It has vertical holding portions 4 that receive the vertical surfaces at both ends in the length direction. The base 20 is also provided with a pair of pedestals 15, and the leaf springs 2 are provided on the upper surface of each pedestal 15.
Is screwed. The leaf spring 2 is a reflective optical element 1.
Elastic arms 21 that press the upper surfaces of both ends in the length direction of
The reflective optical element 1 has elastic arms 22 that press the back surfaces of both ends in the length direction. Therefore, the reflection-type optical element 1 is pressed by the pair of elastic arms 21 and the horizontal surfaces at both ends in the lengthwise direction are brought into contact with the holding portion 16 to move in the vertical direction (hereinafter, this direction is referred to as “X direction”). ) Is determined and is pressed by the pair of elastic arms 22, and the vertical surfaces at both ends in the lengthwise direction are brought into contact with the holding portion 4 to move in the front-back direction (hereinafter, this direction is referred to as “Y direction”). The position of () is determined. In FIG. 9, reference numeral 13 indicates a contact portion between each of the elastic arms 21 and 22 and the reflective optical element 1.

[0010]

The reflection type optical element 1 is
In addition to having the reflecting surface 1a formed of an aspherical surface, it has a complicated shape, so that a material such as a resin that can be easily molded is used. Since resin and the like are weak in strength, it has been found that the following problems occur when the mounting structure using the leaf spring 2 as described above is adopted. As shown in FIG. 10B, when the state of the contact portion 13 between the reflective optical element 1 and the leaf spring 2 as a holding member was observed, part of the leaf spring 2 bites into the reflective optical element 1. It was in a state of being. FIG.
The symbol h in 0 (b) indicates the amount of bite of the leaf spring 2 with respect to the reflective optical element 1. Load P of leaf spring 2
However, if the load P of the leaf spring 2 is reduced, the load for holding the reflective optical element 1 becomes insufficient and the amount of bite becomes smaller than that of h. It is no longer able to withstand shock. Moreover, a part of the leaf spring 2 is h
When the reflective optical element 1 linearly expands due to heat received from the outside as shown in FIG. 3, there is a bite as shown by h, so that the linear expansion is restrained by the leaf spring 2. As a result, the reflective optical element 1 is buckled and abnormally deformed, so that the original imaging characteristics cannot be obtained.

The present invention has been made in view of the above problems of the prior art, and (1) reduces the deformation of the contact portion by distributing the load of the contact portion, (2)
To reduce the expansion constraint in the longitudinal direction where the linear expansion is large,
(3) By holding at a position where the buckling in the longitudinal direction is strong, deformation due to the restraining force received from the holding member during linear expansion is suppressed. (4) Even when the contact portion is deformed, the holding member has an arc shape. By reducing the expansion constraint in the longitudinal direction of the reflective optical element,
(5) An object of the present invention is to provide an optical device capable of suppressing expansion restraint in the longitudinal direction by providing an escape shape on the reflective optical element side even when the contact portion is deformed.

[0012]

In order to achieve the above object, the invention according to claim 1 has a reflection type optical element and a holding member for holding the reflection type optical element in a holding portion. In the above optical device, the contact portion between the reflective optical element and the holding member is linear or plural points or surfaces in one direction.

When the contact portion is linear, the contact portion may be substantially parallel to the longitudinal direction of the reflective optical element as in the invention of claim 2. Furthermore, as in the third aspect of the present invention, the contact portion may be arranged in the same direction as the reflecting surface of the reflective optical element, or on the opposite side of the reflecting side from the reflecting surface. .

According to a fourth aspect of the present invention, the contact portion of the holding member with the reflective optical element may have arcuate end portions in the direction parallel to the longitudinal direction of the reflective optical element.
Further, as in the invention described in claim 5, the contact portion of the reflection type optical element with the holding member may have an escape shape from the holding member at both ends.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an optical device according to the present invention will be described below with reference to FIGS. The same components as those of the conventional example will be denoted by common reference numerals, and duplicated description will be avoided as much as possible.
The gist of an optical device according to the present invention is a holding structure for a reflective optical element (hereinafter, simply referred to as “reflective optical element”) 1 having an imaging characteristic as shown in FIG. In FIG. 1, a reflective optical element 1 has characteristics such as imaging similar to a transmissive optical element (mainly a lens), and is used in all optical devices. FIG. 8 described above is an example in which the reflective optical element 1 is used in an optical scanning device that constitutes a digital copying machine, a laser printer, or the like. The reflection-type optical element 1 is formed in an elongated shape so as to include the deflection range of the optical polarizer, has a reflection surface 1a composed of a spherical surface or an aspherical surface, and has both ends in the length direction of the base. It has a bottom surface 1b to be placed on a horizontal holding portion 16 (see FIG. 9) and a vertical surface 1c to abut the vertical holding portion 4 (see FIG. 9) of the base. Further, on the upper surface of the reflective optical element 1 near both ends,
There is a contact portion 13 with a holding member such as a leaf spring. FIG.
In (b), the arrow A indicates the longitudinal direction of the reflective optical element 1, and the contact portion 13 is present in parallel with the longitudinal direction of the reflective optical element 1 over the length a.

A holding member made of a leaf spring or the like comes into contact with the contact portion 13. However, the problem of the present invention is that the holding member 2 does not restrain the linear expansion of the reflective optical element 1 as described above. Other configurations, that is, how to reduce the h described with reference to FIG.
It is how to make linear expansion naturally and naturally even if restrained.

Therefore, in the present invention, the contact portion 13 between the holding member and the reflection type optical element 1 is not one point in one direction, so that the above-mentioned problems can be solved and put to practical use. Here, the one direction is a direction parallel to the longitudinal direction A of the reflective optical element 1 as shown in FIG. 1, but in the case of holding it two-dimensionally, it is the same as the longitudinal direction A of the reflective optical element 1. It means each direction orthogonal to. Various embodiments of the present invention will be described in detail below.

FIG. 2 shows an example of a holding member applicable to the present invention. The holding member 2 is a leaf spring and has two elastic arms 21 and 22. Each elastic arm 21, 2
2 is bent at an appropriate angle in the middle of the length direction, and the ridgeline formed by the bending serves as a contact portion 13 for the reflective optical element 1. The elastic arm 21 contacts the upper surface of the reflective optical element 1 and presses it downward, that is, in the X direction. The elastic arm 22 contacts the rear surface of the reflective optical element 1 and presses it forward, that is, the Y direction. is there. Due to these pressing forces, the reflective optical element 1 comes into contact with the horizontal holding portion 16 and the vertical holding portion 4 of the base, respectively, as described with reference to FIG. 9, and is attached to the base in a positioned state. .

If the holding member 2 shown in FIG. 2 is used, the reflective optical element 1 will be attached according to the technical idea of the present invention in both the X and Y directions. That is, since the ridge line formed by bending the elastic arms 21 and 22 of the holding member 2 is the contact portion 13 with the reflective optical element 1, the contact portion 13 is not a single point but a line contact state. ing. Thereby, when a load is applied from the holding member 2 to the reflective optical element 1 due to its elastic force, the load is linearly dispersed. That is, referring to FIG. 10, it is possible to reduce the amount of biting h of the holding member 2 into the reflective optical element 1, and it is possible to eliminate the above-mentioned various problems caused by the amount of biting h being large.

In the embodiment shown in FIG. 3, a protrusion 23 is formed at the tip of the elastic arm 21 of the holding member 2 to serve as a contact portion with the reflective optical element 1, and the elastic arm 22 is bent to form a ridge line. To form a contact portion 13 with the reflective optical element 1. The protrusion 23 of the holding member 2 contacts the upper surface of the reflective optical element 1 at one point, and the contact portion 13 linearly contacts the back surface of the reflective optical element 1.
Therefore, in the Y direction, the reflective optical element 1 is attached according to the technical idea of the present invention, but in the X direction, the holding member 2 and the reflective optical element 1 are in contact with each other at one point in one direction. Therefore, the technical idea of the present invention is not adopted.

In the embodiment shown in FIG. 4, a plurality of protrusions 24 (two in the example shown in the drawing) are arranged in the direction parallel to the longitudinal direction of the reflective optical element 1 at the tip of the elastic arm 21 of the holding member 2. It is formed to serve as a contact portion with the reflective optical element 1, and one protrusion 25 is formed at the tip of the elastic arm 22 to serve as a contact portion with the reflective optical element 1. The plurality of protrusions 24 of the holding member 2 contact the upper surface of the reflective optical element 1 at a plurality of points, and the other protrusion 25 contacts the back surface of the reflective optical element 1 at a single point. Therefore, in the X direction, the holding member 2 and the reflective optical element 1 are in contact with each other at two points in one direction, which means that the technical idea of the present invention is adopted, but there is one point in the Y direction. However, the technical idea of the present invention is not adopted.

In the embodiment shown in FIG. 5, a protrusion 26 is formed at the tip of the elastic arm 21 of the holding member 2 to serve as a contact portion with the reflective optical element 1, and the elastic arm 22 is bent to form a ridge line. To form a contact portion 13 with the reflective optical element 1. The protrusion 26 of the holding member 2 is formed long in a direction parallel to the longitudinal direction of the reflective optical element 1 and serves as a contact portion 13 that linearly contacts the upper surface of the reflective optical element 1. On the other hand, the contact portion 13 on the elastic arm 22 side also linearly contacts the back surface of the reflective optical element 1. Therefore, in this embodiment, the technical idea of the present invention is adopted in both the X and Y directions.

In each of the embodiments described above,
The contact portion between the holding member 2 and the reflective optical element 1 is not a single point in one direction but a line contact or a plurality of points. Therefore, the load of the contact portion can be dispersed to reduce the deformation of the contact portion, and the influence of the deformation of the reflective optical element 1 on the imaging characteristics can be reduced. Further, in terms of the ease of processing the holding member 2, it is preferable that the contact portion 13 be in a linear state. Further, the contact portion 13 is a linear contact portion, and the linear contact portion 13 is substantially parallel to the longitudinal direction of the reflective optical element 1, so that the holding member 2 becomes a reflective optical element. In addition to dispersing the load applied to 1, the resistance that restrains the reflective optical element 1 in the largest linear expansion direction of the reflective optical element 1 becomes small, and the deformation of the reflective optical element 1 due to linear expansion occurs. The prevention effect will be increased.

The shape of the reflection type optical element is generally the shape shown in FIG. 1 which has already been described in order to meet the demand for molding. In addition to this shape, the holding member 2 is further provided.
In order to reduce the deformation of the reflection-type optical element 1 due to the linear expansion due to the constraint due to the above, as shown in FIG. 1C, the reflection surface 1a of the reflection-type optical element 1 is in the same direction or opposite to the reflection side. The contact portion 1 at a position that is not the same as the reflection surface 1a on the side.
It is desirable to arrange three. In FIG. 1C, 1
The dotted chain line A indicates the same direction as the reflecting surface 1a, and the area behind the one-dot chain line A, which is hatched and indicated by the arrow B, is on the opposite side to the reflecting side and is not the same as the reflecting surface 1a. The position is shown.

FIG. 6 shows another embodiment of the present invention. 6, in the holding member 2, similarly to the example shown in FIG. 5, a protrusion 26 is formed at the tip of the elastic arm 21 of the holding member 2 and is used as a contact portion with the reflective optical element 1, and the elastic arm is provided. A ridge line is formed at 22 by bending, and this is used as a contact portion 13 with the reflective optical element 1. The protrusion 26 of the holding member 2 is formed long in the direction parallel to the longitudinal direction of the reflective optical element 1,
Is a contact portion 13 that linearly contacts the upper surface of the. This example differs from the example shown in FIG. 5 in that the shape of both ends of the protrusion 26 along the longitudinal direction of the reflective optical element 1 is different from that shown in FIG.
That is, it has an arc shape as indicated by a symbol R in FIG. By doing so, even if the biting amount h shown in FIG. 10 (b) cannot be completely removed, the arcuate end portion slides with respect to the reflective optical element 1,
The constraint on the linear expansion of the reflective optical element 1 can be reduced, and the deformation of the reflective optical element 1 can be reduced.

As another example, as shown in FIG. 7, the elastic arm 21 of the holding member 2 is bent to form a contact portion 13 with the reflective optical element 1, and the reflective optical element 1 is provided with a contact portion 13. Holes 14 and 14 are formed at both ends of the position where the contact portion 13 should come into contact, and the holes 14 and 14 are formed in the contact portion 1.
It may be an escape for 3. According to this example, when the holding member 2 and the reflective optical element 1 relatively move due to the linear expansion of the reflective optical element 1, both sides of the contact portion 13 move on the holes 14 and 14, and the hole 14 , 14 do not bite into the reflective optical element 1, so that it is more effective to reduce the constraint on the linear expansion of the reflective optical element 1 and the deformation of the reflective optical element 1.

In FIGS. 6 and 7, the reflection type optical element 1 is used.
Both ends of the protrusion 26 of the elastic arm 21 that presses in the X direction are formed in an arc shape, or the contact portion 13 of the elastic arm 21 is on the reflective optical element 1 side with which the contact portion 13 should contact. The holes 14 and 14 are formed at both ends of the contact position of 1. to reduce the constraint on the linear expansion of the reflective optical element 1, but the reflective optical element 1 is pressed in the Y direction. The elastic arm 22 may be provided with a projection and both ends thereof may be formed in an arc shape, or holes may be formed at both ends of the reflective optical element 1 side at a contact position with the contact portion of the elastic arm 22. It may be formed to have an escape shape from the holding member 2.

The contact portion between the reflective optical element and the holding member may be surface contact.

[0029]

According to the first aspect of the present invention, there is provided an optical device comprising a reflection type optical element and a holding member for holding the reflection type optical element in a holding portion, wherein the reflection type optical element is used. Since the contact portion between the element and the holding member is linear or plural points or surfaces in one direction, the load applied to the contact portion can be dispersed, and the deformation of the contact portion and further the deformation of the entire reflective optical element can be reduced. Therefore, the original imaging performance of the reflective optical element can be maintained.

According to the second aspect of the present invention, since the linear contact portion is substantially parallel to the longitudinal direction of the reflective optical element, the expansion constraint in the longitudinal direction of the reflective optical element having large linear expansion is reduced. can do.

According to the third aspect of the invention, the contact portion is
Since it is arranged in the same direction as the reflection surface of the reflection type optical element, or on the opposite side to the reflection side and not at the same position as the reflection surface,
It is possible to suppress the deformation of the reflective optical element due to the expansion constraint force received from the holding member during linear expansion.

According to the fourth aspect of the present invention, in the contact portion of the holding member with the reflective optical element, both end portions in the direction parallel to the longitudinal direction of the reflective optical element are arcuate. Therefore, the thermal expansion of the reflective optical element facilitates relative movement between the reflective optical element and the reflective optical element of the holding member, and expansion constraint in the longitudinal direction of the reflective optical element can be reduced.

According to the fifth aspect of the present invention, since the contact portion of the reflective optical element with the holding member has a shape that escapes from the holding member at both ends, the thermal expansion of the reflective optical element. At the same time, relative movement of the holding member with the reflective optical element is facilitated, and expansion constraint in the longitudinal direction of the reflective optical element can be suppressed.

[Brief description of the drawings]

FIG. 1A is a perspective view, FIG. 1B is a plan view, and FIG. 1C is a plan view showing the positional relationship of contact portions, showing an example of a reflective optical element used in the present invention.

2A is a perspective view and FIG. 2B is a side view showing an example of a holding member used in the present invention.

3A is a perspective view and FIG. 3B is a side view showing another example of a holding member used in the present invention.

FIG. 4A is a perspective view, FIG. 4B is a front view, and FIG. 4C is a side view showing yet another example of a holding member used in the present invention.

5A is a perspective view, FIG. 5B is a plan view, FIG. 5C is a side view, and FIG. 5D is a front view.

FIG. 6A is a perspective view and FIG. 6B is a front view showing a main part of an embodiment of an optical device according to the present invention.

FIG. 7A is a perspective view and FIG. 7B is a front view showing a main part of another embodiment of an optical device according to the present invention.

FIG. 8 is a perspective view showing an example of an optical scanning device which is an example of an optical device.

FIG. 9A is a perspective view showing an example of a conventional optical device;
(B) is a side view.

10 (a) is a perspective view and FIG. 10 (b) is a side view showing an essential part of a conventional optical device.

[Explanation of reference numerals] 1 reflective optical element 1a reflective surface 2 holding member 13 contact portion 14 hole for escape

Claims (5)

[Claims] 1. An optical device using a reflective optical element having an imaging property, comprising the reflective optical element and a holding member for holding the reflective optical element in a holding portion, An optical device, wherein a contact portion between the reflective optical element and the holding member is linear or a plurality of points or surfaces in one direction. 2. The optical device according to claim 1, wherein the linear contact portion is substantially parallel to the longitudinal direction of the reflective optical element. 3. The contact portion is arranged in the same direction as the reflecting surface of the reflective optical element, or on the opposite side to the reflecting surface and at a position where the contact portion and the reflecting surface are separate from each other. Or the optical device according to 2. 4. A contact portion of the holding member with the reflective optical element, wherein both end portions in a direction parallel to the longitudinal direction of the reflective optical element have an arc shape.
Or the optical device according to item 3. 5. The optical device according to claim 1, wherein the contact portion of the reflective optical element with the holding member has an escape shape from the holding member at both ends. .