Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
1999-05-28
2001-03-06
Phan, James (Department: 2872)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S200700, C359S216100
Reexamination Certificate
active
06198561
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a light beam deflection apparatus which incorporates a polygon mirror and is employed for, e.g., a laser printer, a bar-code reader, a laser copier, etc.
In the conventional light beam deflection apparatus, the polygon mirror rotates at a high rate, by means of a rotating disk linked to the polygon mirror. The rotating disk includes permanent magnets arranged on it and is driven by driving coils fixed on a base plate. The rotational torque of the polygon mirror is generated by the magnetic forces between the permanent magnets and the driving coils.
In the abovementioned apparatus, however, since the rotating disk, on which the permanent magnets and the polygon mirror are mounted, is joined to a rotatable axis, the reference surface on which the polygon mirror is attached is liable to be distorted when the permanent magnets are mounted on the rotating disk. Owing to this shortcoming, the distortion and/or an inclination of the polygon mirror surface has been relatively high.
To prevent the distortion of the polygon mirror, it is required to employ an adhesive which causes little distortion of the polygon mirror when the permanent magnets are adhered onto the rotating disk. Generally speaking, however, an adhesive causing little distortion is liable to be lower in the reliability of its adhesion, due to the weakness of its adhesive force.
SUMMARY OF THE INVENTION
The present invention is attained in view of the above-described situations, and the object of the present invention is to provide a light beam deflection apparatus in which the distortion of the polygon mirror is reduced at a minimum level by preventing propagation of the distortion caused by the adhesive process of the permanent magnets, and in which the mounting accuracy of the polygon mirror is improved by strengthening the joint to the rotating axis.
To overcome the cited shortcomings, the abovementioned object of the present invention can be attained by a light beam deflection apparatus, comprising:
a base plate;
a coil being stationary relative to the base plate; and
a mirror unit being rotatable with respect to the base plate, wherein the mirror unit is comprised of
a polygon mirror,
a rotating disk to mount the polygon mirror,
a rotating yoke fixed to the rotating disk,
a magnet attached to the rotating yoke and located opposite the coil and
a buffer member inserted into a gap between the polygon mirror and the rotating yoke.
Further, in order to solve the above-described problems and to attain the abovementioned object, the following features of light beam deflection apparatus are desirable embodiments of the present invention.
(1) A light beam deflection apparatus in which,
permanent magnets fixed on the rotating yoke are arranged opposite the coil fixed on the base plate to generate torque for rotating the polygon mirror, and
the polygon mirror is attached to the rotating disk so that an end surface of the polygon mirror contacts the reference surface of the rotating disk, and
a buffer member is inserted between the other end surface of the polygon mirror and the rotating yoke, fixed to the rotating disk, so that the polygon mirror is rotatable with the rotating disk.
Since the polygon mirror is attached to the rotating disk by contacting an end surface of the polygon mirror to the reference surface of the rotating disk and inserting a buffer member between the other end surface of the polygon mirror and the rotating yoke, it is possible to prevent the propagation of the distortion, caused by adhesion of the magnets, not only during the initial period after assembly, but also in the high temperature atmosphere generated during the actual operation. Further, since the magnets are not directly adhered to the rotating disk having the reference surface for attaching the polygon mirror, distortion caused by adhesion of the magnets does not occur in the rotating disk. Therefore, it becomes possible to employ an adhesive having a strong adhesive force and suitable adhesive conditions without considering the distortions caused by adhesion of the magnets.
(2) The light beam deflection apparatus of item (1) in which,
the buffer member is an elastic material.
According to the above, the elastic material can surely prevent distortion caused by adhesion of the magnets from transmitting to the polygon mirror.
(3) The light beam deflection apparatus of item (2) in which,
the buffer member is either a leaf spring or a rubber.
According to the above, a leaf spring can be surely prevent distortion caused by adhesion of the magnets, from transmitting to the polygon mirror, without being influenced by the high heat generated during actual operation. In case of employing a rubber, the propagation of the distortion would be surely prevented as well, since the rubber would equally absorb the distortion caused by adhesion of the magnets.
(4) The light beam deflection apparatus of item (1) in which,
the rotating yoke is fastened to the rotating disk by means of fastening members.
According to the above, it becomes possible to firmly fix the polygon mirror onto the rotating disk in a simple structure using only the fastening members.
(5) The light beam deflection apparatus in which,
permanent magnets fixed on the rotating yoke are arranged opposite the coil fixed on the base plate to generate torque for rotating the polygon mirror, and
the polygon mirror is attached to the rotating disk so that an end surface of the polygon mirror contacts the reference surface of the rotating disk, and
the buffer member is inserted between another end surface of the polygon mirror and the rotating yoke, fixed to the rotating disk, so that the polygon mirror is rotatable with the rotating disk, and
the rotating disk is jointed to the rotating axis.
Since the polygon mirror is attached to the rotating disk by contact to the reference surface of the rotating disk which is jointed to the rotating axis and by inserting the buffer member between the polygon mirror and the rotating yoke, it is possible to improve the inclination angle of the polygon mirror.
(6) The light beam deflection apparatus of item (5) in which,
A shrinkage fitting method is employed for joining the rotating disk to the rotating axis.
Since the rotating disk is jointed to the rotating axis by a shrinkage fitting process, it becomes possible to surely improve the accuracy of inclination angle of the polygon mirror.
(7) The light beam deflection apparatus of item (5) in which,
an adhesion method is employed for joining the rotating disk to the rotating axis.
Since the rotating disk is joined to the rotating axis by an adhesion process, it becomes possible to improve the accuracy of the inclination angle of the polygon mirror in a rather simple way.
(8) The light beam deflection apparatus of item (5) in which,
a method of adhesion after the shrinkage fitting is employed for joining the rotating disk to the rotating axis.
Since the rotating disk is joined to the rotating axis by adhesion after the shrinkage fitting process, it becomes possible to surely improve the accuracy of the inclination angle of the polygon mirror.
(9) The light beam deflection apparatus of items (5) through (8) in which,
the reference surface for attaching the polygon mirror is formed by a cutting process.
Since the reference surface for attaching the polygon mirror is formed by a cutting process after the joining process, any distortion of the rotating disk caused by the joining process does not influence the accuracy of the reference surface.
(10) The light beam deflection apparatus in which,
permanent magnets fixed on the rotating yoke are arranged opposite the coil fixed on the base plate to generate torque for rotating the polygon mirror, and
the polygon mirror is attached to the rotating disk so that an end surface of the polygon mirror contacts the reference surface of the rotating disk, and
the buffer member is inserted between the other end surface of the polygon mirror and the rotating yoke, which is fixed to the rotating disk, so that the pol
Horiai Hiroyuki
Kamimura Naoji
Kobayashi Hiroshi
Matsui Susumu
Bierman Jordan B.
Bierman, Muserlian and Lucas
Konica Corporation
Phan James
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