Mechanism for adjustable installation of plate-like member

Joints and connections – Interfitted members – Clamped members

Reexamination Certificate

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Details

C403S013000, C403S343000, C403SDIG008, C250S491100, C074S567000, C074S569000, C382S321000

Reexamination Certificate

active

06585446

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mechanism for adjustable installation of a plate-like member, particularly a plate-like member such as a reflector in order to make an effective surface of this member facing in a desired direction and more particularly to such mechanism suitable to adjust the direction in which the effective surface of an optical scanner's reflector faces.
2. Description of the Related Art
An optical scanner used in an image forming apparatus such as copying machine or printer is generally arranged so that a laser beam emitted from a laser source and containing image information is appropriately toned, then enters deflector means such as a polygon mirror and the laser beam thus deflected irradiates and scans an image carrier as an object to be scanned, for example, a photosensitive drum and forms an electrostatic latent image on this image carrier. This electrostatic latent image is developed with toner to form a toner image, which is then transferred to a transfer medium such as recording paper to form a visible image thereon. As color image forming apparatus, for example, color copying machine or color printer, the image forming apparatus of tandem type has been widely used. In the image forming apparatus of this type, a plurality of image carriers such as photosensitive drums are arranged side by side so that electrostatic latent images may be formed on the respective image carriers as the laser beams containing the image data colored in yellow (Y), magenta (M), cyan (C) and black (BK), respectively, irradiate and scan said respective image carriers. These electrostatic latent images are developed by respective particular kinds of toner to form respective toner images which are then successively transferred to the transfer medium such as recording paper travelling in the direction of the image carriers' side by side arrangement to form color images thereon.
Demand for pluralization of the light beam for scanning and the scanning unit has increased as high-speed copying machines and printers have come widely in use. Additionally, in order to ensure the formed image to be distinct, optical characteristics of these plural scanning light beams as well as the scanning characteristics of these plural scanning units must meet the predetermined requirements and the characteristics of these plural units must be uniform. To ensure the required optical characteristics and the scanning characteristics, installation precision of the optical members constituting the optical scanner must be sufficiently high to achieve the proper operative association one with another. Particularly, even a slight error in the reflecting direction of the reflector or variation in the installed state will deteriorate the optical characteristics as well as the scanning characteristics. To avoid such problems, the reflecting direction of the reflector should be adjusted to a high precision.
The mechanism for adjustable installation of a reflector is well known, in which the spacer as thin as possible, for example, a mica plate is disposed between the reflector and the bracket on which the reflector is mounted and thereby said reflector is adjustably tilted. As an example of such mechanism, so-called mirror adjusting mechanism is described in Japanese Utility Model Application Disclosure Gazette No. 1993-33108. This mirror adjusting mechanism of prior art comprises: a mirror frame; a supporting piece mounted on an end of said mirror frame so that said supporting piece may bear against a reflective surface of a mirror; an adjusting plate is rotatably mounted on said adjusting plate so that said adjusting plate may bear against said reflective surface of said mirror; an adjusting member mounted on said adjusting plate to adjust an angular position of said adjusting plate; and a biasing member adapted to bear against a rear surface of said mirror frame and thereby to bias said mirror. Said adjusting plate is adjustably rotated by said adjusting member to swing the mirror around its longitudinal axis and thereby to change a direction in which the reflective surface thereof faces.
These conventional adjusting mechanisms as have been described above are inevitably accompanied with problems. In the case of the mechanism adapted to tilt the reflector by interposition of the spacer, it is certainly possible to adjust a tilt of the reflector omni-directionally. However, the extremely thin spacer makes operation of adjustment troublesome. In addition, a clamping force of the set screw used to fix the reflector is not constant and consequently it is sometimes impossible to make the reflector face in the desired direction, in spite of interposition of said spacer. In other words, no quantitative adjustment is impossible and the adjusting effect may largely depend on working accuracy of the components such as the spacer, the reflector and the brackets.
The mirror adjusting mechanism described in said Japanese Utility Model Application Disclosure Gazette No. 1993-33108 is adapted to rotate the adjusting plate by screwing-in or out an adjusting screw and by adjusting a movement of the adjusting screw back and forth, no fine adjustment is possible since the adjustment largely depends on a pitch of the adjusting screw.
While it may be contemplated to use an eccentric pin as the adjusting member to perform such adjustment, a variation occurring in a tilt of the plate-like member every time the operation of adjustment is carried out is too large to meet the recently demanded requirements for the high precision of adjustment.
SUMMARY OF THE INVENTION
In view of the problems as have been described above, it is a principal object of the present invention to provide a mechanism for adjustable installation of a plate-like member particularly suitable for a reflector in an optical scanner improved so that not only the quantitative adjustment but also a fine adjustment can be achieved.
The object set forth above is achieved, according to an aspect of this invention, by a mechanism for adjustable installation of a plate-like member comprising a cam member located at one of longitudinally opposite ends of said plate-like member aside to one of transversely opposite ends of said plate-like member so that a cam curve of said cam member may be normally kept in contact with one surface of said plate-like member, said plate-like member is pivotally supported at the other of said transversely opposite ends, biasing means adapted to bias said other surface so that said one surface may be normally kept in contact with said cam curve and actuator means adapted to rotate said cam member and thereby to alter a position of the plate-like member at which said cam curve comes in contact with said one surface.
The position of the plate-like member at which the cam curve comes in contact with the plate-like member is changed as said cam member is rotatably driven by said actuator means, With a consequence, one of the transversely opposite side edges of said plate-like member has its position changed and the direction in which the effective surface of said plate-like member faces is also changed. Under the effect of the biasing means, the plate-like member is normally kept in contact with the cam curve and reliably moved by said cam curve. Movement of the plate-like member by the cam curve advantageously enables the adjustable installation of said plate-like member to be continuously and finely achieved so far as said cam curve is appropriately configured.
According to one preferred embodiment of this invention said cam member moves in the axial direction of its rotational shaft as said cam member rotates.
In the case of the cam curve configured so as to intersect a plane orthogonal to the rotational axis of the cam member, the position of the plate-like member at which the latter comes in contact with the cam curve inevitably varies as the cam member rotates. For such arrangement, there is an apprehension that a position variation for the adjustable installation of the pl

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