JPS62164016A - Manufacture of rotating polygon mirror driving device - Google Patents

Abstract

PURPOSE:To suppress the vibration and to improve the accuracy by giving an additional weight to an annular groove of a rotator and eliminating an imbalance for the rotating imbalance due to the rotation of an electric motor part. CONSTITUTION:The division at the side opposite to the fitting of the rotating mirror of 1/2 out of the whole length of a stator 4 has sufficient rigidity to a bending moment applied to a rotating polygon mirror 13 side of a rotating shaft 12 as the outer diameter three times or more of the outer diameter of a bearing. The electric motor is rotated, and a rotator 8 is constructed so that by the byte with a stator 4 side as a reference position, the surface vibration can be removed for the fitting surface of the polygon mirror 13 and the rotator 8 surface can be stably cut. Further, approximate to the outer circumference of the rotator 8 surface, a groove 84 is provided in a circular circumference, and the correcting weight to correct the imbalance of the rotation is inserted here. Thus, the imbalance of the rotation is eliminated, the rotating vibration can be prevented, and when rotation and cutting are executed, the flapping of the cutting surface and the deteriorating of the accuracy due to the vibration can be prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a rotary multi-surface driving device, and in particular to a structure of an electric motor that provides the driving force and a method for manufacturing the same. It is related to.

[Conventional technology]

The electric motor used in this type of drive device is formed by directly fixing a polygon mirror to its rotating part, but the part to which this polygon mirror is fixed has sufficient rotation precision, that is, the coaxiality and surface area of the rotating part. The flatness and excavation of the surface are greatly affected, and improving the accuracy of these factors was an essential requirement. However, the electric motor part is a combination of parts such as a stator, a bearing, and nine rotors, and there is a limit to the accuracy that can be obtained by simply combining these parts.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take into account the accuracy of individual parts even if they are manufactured to obtain the best results, so the accuracy after assembly is not considered.
Problems that arose when assembling the electric motor and attaching the polygon mirror to it could not be avoided.

An object of the present invention is to improve the accuracy of the assembled state of the electric motor, and to obtain good accuracy when a polygon mirror is attached to the electric motor. , the purpose is to eliminate the accumulation of errors in component parts.

[Means for solving the problem] The above purpose is to improve the accuracy after assembly of the electric motor, which is achieved by fixing the motor in a constant and immovable position with respect to the stator, which is the most important reference after assembly. This is done by cutting the rotor with a cutter, such as a cutting tool, to eliminate relative runout between the stator and rotor, but the important thing is to cut the rotor in a constant, fixed position with respect to the stator. By providing a cutting tool in the motor, this constant, immovable position can vary greatly depending on the rigidity of the motor itself. To do this, the bearing support on the stator side must be supported with rigidity, the bearing spacing must be as large as possible to prevent the shaft from wobbling, and the ball bearing used in the bearing must be It is necessary to have a bearing structure that prevents the rotor side from displacing with respect to the stator due to axial force, and furthermore, even if there is a rotational imbalance in the rotor, vibration will occur and precision cannot be maintained. Accuracy is also required to remove the misalignment, and by combining these, higher accuracy during rotation can be achieved.

[Effect]

First, in order to increase the rigidity of the bearing support part on the stator side,
The section on the opposite side of the rotary bell installation, which is 1/2 of the total length of the stator, has an outer diameter that is at least three times the outer diameter of the bearing to provide sufficient rigidity against the bending moment applied to the rotating polygon mirror side of the rotating shaft. It is something. Next, the electric motor is rotated, and the surface on which the polygon mirror is attached is cut using a cutting tool with the stator side as the reference position, so that the surface runout can be removed. A ball bearing that constitutes a bearing is subjected to a load through the cutting surface in the direction of
This will press the J ring, but it is necessary to apply a preload force so that the contact position between the outer ring, inner ring and balls of the ball bearing does not change.This allows stable cutting of the rotor surface. .

Furthermore, a groove is provided in a circumferential manner close to the outer periphery of the rotor surface,
A correction weight is inserted here to correct rotational imbalance. This eliminates unbalanced rotation,
Since rotational vibration can be prevented, when rotating and cutting, it is possible to prevent the cutting surface from becoming wavy due to vibration and reducing accuracy.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

In the figure, 1 is a rotating polygon mirror drive device, and stator coil 2
A stator substrate 3 is provided, which is fixed to the stator body 4, and the coil 2 is formed into a three-phase coil as shown in FIG. 5 in the embodiment of the present invention. The current signal applies a driving force to the magnet 6 which is magnetized to a plurality of poles from the annular body provided apart from the stator substrate 3 and the narrow gap 5, and this driving force is applied to the yoke iron plate of the magnet 6. It is fixed to the rotor 8 via 7. Reference numeral 9 denotes an annular iron yoke plate for forming a magnetic path on the stator side, and is fixed to the stator main body 4. The stator body 4 has bearing support parts 41 and 42 in the center, and the upper bearing support part 41 is located in the center of the umbrella-shaped rotor 8 at a position surrounded by the magnet 6 and at the upper end of the stator body 4. provided in the department. On the other hand, by providing the lower bearing support part 42 at the lowest part of the stator main body 4, the spacing between the bearings is large, and the shaft 12 due to the error of the upper ball bearing 10 and lower ball bearing 11 mounted thereon. This is to minimize the slope of the curve. The outer rings of these pole bearings 10 and 11 are connected to the stepped portions 4 of the bearing portions 41 and 42 of the stator body 4.
3 and 44 regulate the distance between the υ bearings. On the other hand, the shaft 12 is fitted and fixed into a hole 81 provided at the center of the rotor 8, and a rotating polygon mirror 13 is fixed on the rotor 8, and a rotating polygon mirror (six-sided mirror in the embodiment) 13 is fixed on the top surface. The fitting protrusion 82 that engages with the rotary polygon mirror @ 13 serves as a reference position on the lower surface of the rotary polygon mirror drive device [1] of the present invention. An annular groove 84f for fixing the additional weight 14 for correcting the unbalance of the rotating portion is provided in the vicinity of the rotating portion. axis 1
2 is above.

The length is such that it passes through the inner rings of the lower ball bearings 10 and 11 and protrudes further downward from the lower ball bearing 11. Here, the inner circumferential side abuts the inner ring of the lower ball bearing 11, and the outer circumference of the shaft 12. A dish-shaped preload spring 15 is provided which is received by a preload adjuster 16 fixed to the end. This dish-shaped preload spring 15 eliminates the radial clearance between the upper and lower hook ball bearings 10 and 11, and the electric motor part 17 consisting of the rotary polygon mirror, the stator body 4 and the rotor 8 of the ringing device 1 due to the radial clearance. As shown in Fig. 3, the upper and lower ball bearings 10 and 11 are fitted in the direction of the arrow P'. The force is applied to each ball bearing's outer ring, inner ring,
The relationship between the balls is as shown. In this state, as shown in FIG. 4, even if a force in the P direction is applied to the rotor 8, no relative movement occurs between the IM stator body and the rotor 8. In such a state, when the motor part 17, that is, the rotor 8, rotates due to the electromagnetic force between the stator body 4 and the rotor 8 and reaches a predetermined rotation speed, the centrifugal force due to the rotor balance of the rotor 8 naturally causes the motor to rotate. Portion 17 will experience vibrations. This vibration is generated in the optical system of the laser printer 21 as shown in FIG. This deteriorates the scanning accuracy of the laser beam 24 focused on the photosensitive drum 23 by the fθ lens 22, which keeps the scanning speed constant, and deteriorates the image produced by the laser printer 21. Therefore, in the motor section 17, an annular groove 84 is used to add additional weight 14 thereto to eliminate rotational imbalance. This creates the first factor in obtaining high image quality.

Next, in a state where the unbalance of rotation has been sufficiently eliminated, the stator main body 4 of the motor section 17 is fixed to the fixed reference stand 18, and the rotor 8 is While rotating the upper surface 83a of the annular protrusion 83 provided in the upper surface by the self-generated rotational force of the electric motor section 17, the swinging portion of the upper surface is cut.

As a result, the upper surface 83a of the annular protrusion 83 can suppress the shake to 0.5 μm, whereas the combination of the components of the motor portion 17 alone could suppress the shake to 20 μm. Furthermore, cutting the upper surface 83a of the annular protrusion 83 is performed using the power generated by the electric motor section 17, without borrowing mechanical power from other machines, in the same manner as cutting on a lathe. can be prevented. Furthermore, as explained in FIG. 3, the radial gap between the upper and lower ball bearings 10 and 11! ! is eliminated by a preload spring 15, so that even if a force P in the direction of the arrow in FIG. 4 is applied during cutting, the rotor 8 does not move in the direction of the arrow and can be stably cut to remove run-out. in this case,
The upper ball bearing 10 transfers the axial force P to the inner ring, balls,
When cutting the upper surface 83a of the annular protrusion 83 by receiving it at the upper part of the stator main body 4 in the order of the outer ring stepped portion 43, the axial load P is
Since it is separated by distance d from the center, a bending moment is applied to the roll 112, and the moment becomes maximum at the position of the lower ball bearing 11. For this reason, a bending moment is also applied to the bearing support portion 42 of the lower ball bearing 11, so it is necessary to provide this portion of the stator body 4 with great rigidity. As shown, this part is made thicker to increase the strength.

〔Effect of the invention〕

As described above, according to the present invention, vibration can be suppressed by first eliminating the unbalance of the rotor due to the rotation of the motor portion 17 by adding the additional weight 14 to the sub-shaped groove 84 of the rotor 8. can.

In particular, since the rotating polygon mirror 13 requires high-speed rotation on the order of io o o o o rya, removing the unbalance can have a great effect on improving image quality.

Next, the stator main body 4, which is a rotating part, excites the electric motor part 17 to self-rotate as an electric motor, and after removing the aforementioned unbalance, the upper surface 83a of the annular protrusion 83, which serves as a reference for attaching the rotating polygon mirror 13, is removed. Since the upper surface 83a is cut using the stator main body 4 as a reference, it is possible to machine the upper surface 83a until the runout is almost eliminated, and this surface is used as a reference when attaching the rotating polygon mirror 13.
It is possible to maintain high accuracy and obtain high-quality images without causing unnecessary displacement of the laser beam. In this case, the shape of the stator main body 4 is stable even against the axial load and bending moment received when cutting the upper surface 83a, which has the effect of further increasing precision.

[Brief explanation of drawings]

Fig. 1 is a front cross-sectional view of an embodiment of the rotating polygon mirror drive device of the present invention, Fig. 2 is a plan view, Fig. 3 is an explanatory diagram of the state of the ball bearing, and Fig. 4 is the rotation of the main part. FIG. 5 is an electrical system diagram for driving the motor portion, and FIG. 6 is an explanatory diagram of an example of a laser printer using the rotating polygon mirror drive device of the present invention. 1... Rotating polygon mirror m movement device, 2... Stator coil,
3... Stator board, 4... Stator body, 5... Slit, 6... Magnet), 7.9... Yoke iron plate, 8...
... Rotor, 10... Upper ball bearing, 11.
...Lower ball bearing, 12...shaft, 13...
Rotating polygon mirror, 14...Additional weight, 15...Preload spring, 16...Preload adjustment tool, 17...Electric motor part, 18
...Reference stand, 19...Bite, 21...v-1;
22...fθ lens, 23...photosensitive drum, 24...laser light beam, 41°42...
・Bearing support part, 43.44...step part, 81...hole,
82... Fitting protrusion, 83... Annular protrusion, 83a...
-Top surface, 84... annular groove.

Claims (1)

[Claims] 1. In the stator body (4), in which ball bearings (10) and (11) are fitted at both upper and lower ends with their outer ring intervals regulated, a magnet (6) is electrically biased to one side. Approximately 1/2 of the space for the stator coil (2) that provides rotational force is provided in the axial direction, and the other end is equipped with a ball bearing (
11) with a wall thickness three times or more thicker than the stator coil (2).
On the side opposite to the rotor (
8), the rotor (8) is shaped like an umbrella, and the inner surface is shaped to cover a bearing support part (41) having one ball bearing (10), and the outer surface to which the rotating polygon mirror (13) is fixed has a rotating polygon. The rotor (8) is formed by forming a fitting projection (82) for fitting the mirror (13), an annular projection (83) as a surface for supporting this, and an annular groove (84) for correcting rotational imbalance. A shaft (12) fitted and fixed in the center of the shaft passes through two ball bearings (10) and (11), and the inner ring of one ball bearing (11) is pressed by a preload spring (15) to rotate. The unbalance of the child (8) is corrected and the rotor (8)
and the stator body (4).
7) to rotate the rotor (8) and cut the upper surface (83a) of the annular protrusion (83) of the rotor (8) with reference to the stator body (4). A method for manufacturing a rotating polygon mirror drive device, characterized in that (13) is fixed to a rotor.