JPH02189510A - Deflecting and scanning device - Google Patents

Abstract

PURPOSE:To use a motor which is tolerable for vibrations and a shock and to obtain invariably stable rotary driving with good balance by putting the center of gravity of a rotor part close to where dynamic pressure is generated and the rotor part is supported. CONSTITUTION:The center of gravity of the rotor part 2 which is driven to rotate is lowered, a recessed part is formed below the rotary mirror 1 of the rotor part 2, and a weight 19 for improving the balance is fitted. Therefore, the center of gravity of a rotary body (rotary polygon mirror 1, rotor 2, etc.) is lowered to improve the balance in rotation. Consequently, high-accuracy rotary driving which is tolerant to external vibrations and a shock, invariably stable is realized, the image distortion of an image recording device such as a laser beam printer is reduced, and the stop of rotation due to galling is not generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a deflection scanning device used in a laser beam printer or the like, and more particularly to a deflection scanning device using a dynamic pressure bearing.

[Conventional technology] Conventionally, ball bearings have been used as bearings in the deflection scanning motor that rotates the rotating mirror and deflects and scans the light beam emitted from the light source, but ball bearings generate vibration and noise. Not only is it difficult to rotate at high speed, but there is also play between the ball and the inner and outer rings that support it, which has the serious drawback of causing the mirror surface of the rotating mirror to fall over.

Dynamic pressure fluid bearings have been developed to solve these drawbacks. Therefore, Fig. 4 shows the configuration of a deflection scanning motor using a hydrodynamic bearing.
Fixed on top. The rotor 2 is equipped with a driving magnet 6 and an FG magnet 7, and a stator coil 8 and an FG pattern (not shown) are arranged on a printed circuit board 9 at opposing positions, respectively. Furthermore, the shaft 3 and the mirror attachment are fixed by press-fitting or shrink-fitting the flange 5, and a dynamic pressure generating groove 4 is formed on the outer circumferential surface of the shaft 3, and by fitting it with the sleeve 10, dynamic pressure can be generated. can occur. A thrust plate 11 provided with a shallow groove for generating thrust pressure is disposed at the bottom of the sleeve 10, and includes a motor case 12, forming a deflection scanning motor.

[Problem that the invention seeks to solve] However,
Even in the deflection scanning motor that uses the hydrodynamic bearing described above, in order to always rotate with high precision, the rotor part that is being rotated must be well balanced, and furthermore, it is necessary to prevent external vibrations, shocks, and vibrations.
It must be constructed to withstand wind pressure. If rotational unevenness occurs in the rotational drive, it will appear as image distortion in image recording devices such as laser beam printers, and if the shaft is susceptible to shocks, the gap between the shaft and the sleeve may be several μm.
Since it is ~ several tens of microns, it will get chewed up and become unable to rotate.

[Means for Solving the Problems] According to the present invention, the center of gravity of the rotating rotor is lowered, and a recess is provided in the rotor at the lower part of the rotating mirror to improve balance. By attaching a weight for this purpose, it is possible to provide a deflection scanning motor that is resistant to external vibrations and shocks and can always provide stable and highly accurate rotational drive.

[Example] The configuration of a deflection scanning motor according to the present invention will be explained with reference to FIG.

Reference numeral 1 denotes a rotating polygon mirror having a reflecting surface for deflecting and scanning a light beam emitted from a light source, and a mirror mount 5 is attached to a flange.

In image forming devices such as laser beam printers,
Since the tilting of each surface of the rotating polygon mirror causes unevenness in the pitch of the scanning light and has a negative effect on the image, the bottom surface of the rotating polygon mirror 1 and the reference surface 5a for attaching the mirror and the flange are cut or cut with high precision. It is ground so that the reflective surface does not fall.

Here, the rotating polygon mirror 1 is regulated from above by an elastic member 18 such as a spring, and the elastic member 18 further includes a mirror fixture 17 for generating a certain regulating force and a groove provided in the shaft 3. The mirror fixture 17 is firmly attached to the shaft 3 by a fixing member 16, such as a tension member, which fixes the elastic member 18 and the mirror fixture 17.

A shallow groove 4 for generating dynamic pressure is formed on the outer periphery of the shaft 3, and by fitting it with ten sleeves at intervals of several microns to several tens of microns, and rotating the shaft 3, ,
Dynamic pressure is generated and it has a vine configuration.

The mirror mounting flange 5 attached to the shaft 3 by press fit, shrink fit, etc. has a stepped shape that surrounds the sleeve 10. As a result, the reference plane 5a to which the rotating polygon mirror is attached is lowered, and the position of the rotating polygon mirror 1 can also be lowered. Further, below the flange 5, the rotor 2, which is provided with a drive magnet 6 and an FG magnet 7, is crimped and fixed, and the rotor 2 has a concave portion below the rotating polygon mirror 1. It has become.

These members fixed to the shaft 3 and driven to rotate are collectively referred to as a rotor section, and the details of the function of this rotor section will be described later.

There is a printed circuit board 9 on which a stator coil 8 and an FG pattern (not shown) are arranged, respectively, facing the drive magnet 6 and the FG magnet 7, and a drive circuit and a Hall element (not shown) are mounted on this board. A control circuit including the following elements is formed, and highly accurate rotational drive can be obtained.

Furthermore, in FIG. 1, reference numeral 13 denotes a fixed plate to which a thrust plate 11 provided with a shallow groove for generating thrust pressure is fixed by press-fitting or the like. In this way, the sleeve 10 is assembled in such a manner that it is sandwiched between the motor case 12 holding the printed circuit board 9 and this fixing plate 13, and is fixed with 15 fixing screws or the like. Note that 14 indicates a mechanical seal member used to prevent leakage when there is lubricating oil or the like between the shaft 3 and the sleeve IO.

The deflection scanner, which is constructed using hydrodynamic bearings, rotates with high precision, but it was also designed to be more stable and resistant to external vibrations, shocks, wind pressure, etc. The function of the rotor section will be explained in detail below.

When attaching the mirror, the flange 5 is shaped to surround the sleeve 10, and the position of the rotating polygon mirror 1 is also lowered, thereby lowering the center of gravity of the rotor section. If the center of gravity of the rotor is high, even if it is being rotated with high precision,
When subjected to external vibrations or shocks, the upper part of the motor tends to shake, resulting in unstable rotation similar to miso-suri motion.

Therefore, by lowering the center of gravity and bringing it closer to the periphery that is supported by dynamic pressure, the rotor is configured to suppress shaking even when subjected to vibrations or shocks.

In the case of the rotor 28 as shown in FIG. 1, a weight 19 for balancing the rotor can be attached to the corner of the recess.

Since the motor is rotating at a fairly high speed, the weight is 19.
Although it is possible that the weight may be scattered due to centrifugal force, since the wall 2a prevents the weight from scattering, there is no loss of balance caused by the weight scattering while the motor is in use. Furthermore, a concave portion of the rotor is formed inside the inscribed circle of the rotating polygon mirror, and a convex portion 2b of the rotor is provided in close proximity to the rotating polygon mirror 1, as shown in FIG. Therefore, it is possible to reliably prevent the weight 19 from scattering,
Furthermore, we have taken measures to prevent the airflow from flowing below the rotating polygon mirror, causing turbulence and causing the rotor to become unbalanced.

If the rotor loses its balance or undergoes a grinding motion due to external vibrations or shocks, it will appear as the pitch unevenness mentioned above, as well as uneven rotation of the drive motor. By adopting the configuration of the invention, in other words, the center of gravity of the rotating body (rotating polygon mirror, rotor, etc.) is lowered to improve the balance during rotation, and the rotor 2
By devising the shape of the rotor, and by making it possible to properly attach weights to adjust the balance of the rotating body, this kind of movement becomes less likely to occur, and even if it does occur, Since the position of the rotating polygon mirror is lowered, the amplitude of unstable motion is reduced and the influence on the image is reduced.

[Other Embodiments] = Fig. 2 shows another embodiment of the deflection scanning motor, in which the rotating polygon lt1 and the mirror are mounted on the flange 5, and the rotor 2 and the like are mounted on the sleeve 10 to form the rotor section. are doing. The shaft 3 is attached to the motor case 12, and shallow grooves 4a and 4b for generating dynamic pressure are formed on the outer periphery of the shaft 3, as in the previous embodiment.
It is the sleeve side of No. 10 that rotates with high precision due to dynamic pressure.

In FIG. 2 as well, the rotor 2 forms a recess with the end face of the flange 5 or itself below the rotating polygon mirror 1, particularly inside the inscribed circle of the rotating polygon mirror 1,
The convex part is close to the rotating polygon mirror. This configuration is the same as that described in the previous embodiment in that the weight 19 does not scatter or the balance is not lost due to turbulence.

Furthermore, this embodiment is a sleeve rotation type deflection scanning motor, and by adopting such a structure, the position of the rotating polygon mirror 1 can be brought between the dynamic pressure generating grooves 4a and 4b. This is relatively easy compared to
In other words, it is also possible to provide the flange 5 at such a position on the outer peripheral side surface of the sleeve 10 for mirror attachment. Furthermore, it is desirable that the center of gravity of the rotor section be horizontal 4a,
4b is the structure that is most resistant to vibration and abrasion, so this embodiment is a more preferable structure for a motor that obtains more stable and highly accurate rotational drive. Specifically speaking, the vicinity of the dynamic pressure generating groove mentioned here is not a place where the groove is divided into 4a and 4b as in this embodiment, but if there is a single groove, The point where the floating blade has the highest rigidity when dynamic pressure is generated, or in this example, or if there are more than one groove generating dynamic pressure, the center of gravity is located near the position between the grooves at both ends. Although it is preferable to adopt this configuration, in reality, a sufficient effect can be obtained even if the center of gravity is positioned below the upper end of the dynamic pressure generating groove provided in the shaft. Furthermore, here,
Regarding the axial direction of the shaft 3, the end where the member 12 is located is the lower end,
16 is expressed as the upper end.

In another embodiment shown in FIG. 3 above, a member 20 for mounting a balancing weight 19 is mounted on the rotor 2 as a separate member.

This configuration not only has the effects described in the embodiment of FIG. 1, but also has the following effects.

In the embodiment shown in FIG. 1, the rotor 2 must be balanced before the rotating polygon mirror I is attached for assembly purposes, but by adopting the configuration shown in FIG. Since the balance of the entire rotor section can be adjusted after the fixing members are attached, the effect is that a more balanced and stable rotational drive can be obtained.

Further, instead of attaching the weight 19, the balance can be achieved by cutting the member 20.

Furthermore, in another embodiment, the flange portion 5 and the rotor 2 may be formed integrally, and a driving magnet 6 or the like may be attached to this member to obtain the same effect.

[Effects of the Invention] As explained above, by moving the rotor close to the center of gravity where dynamic pressure is generated and supported, the motor can be made resistant to vibrations and shocks.

Further, by making the rotor portion concave below the rotating polygon mirror and arranging the rotor portion to be close to the rotating polygon mirror in the periphery thereof, there is an effect that stable and well-balanced rotational drive can always be obtained.

[Brief explanation of the drawing]

1 to 3 are diagrams showing the configuration of a deflection scanning motor according to an embodiment of the present invention, and FIG. 4 is a diagram showing the configuration of a deflection scanning motor using a conventional hydrodynamic bearing. 1 is a rotating polygon mirror, 2 is a rotor, 3 is a shaft, 4 is a shallow groove for generating dynamic pressure, 5 is a flange for attaching the mirror, 10 is a sleeve, and 19 is a balance weight. Figure 4 Procedural Procedures Authorized Letter (Spontaneous) November 29, 1999 Director General of the Japan Patent Office Yoshi 1) Tsuyoshi Moon Patent Application No. 10363 of 1999 2 Name of the invention Deflection scanning device 3 Address of the person making the amendment Relationship with the name case Patent applicant 3-3O-2 Shimomaruko, Ota-ku, Tokyo (100) Canon Co., Ltd. Representative Keizo Yamaji 44, Agent address: 3-30-25 Shimomaruko, Ota-ku, Tokyo 146, Amendment. Subject specification 6, content of amendment (1) Page 9, line 18 of the specification “...with improvements”
should be corrected to "and improve". (2) On page 11, line 17 of the specification, "not in such circumstances" is corrected to "not in such circumstances." (3) On page 11, line 18 of the specification, "rigidity of floating blade" is corrected to "dynamic pressure". (4) Correct position aJ in line 20 of page 11 of the specification to "center position".

Claims (3)

[Claims] (1) A rotating body having a rotor portion having a fixed flange portion for attaching a rotating mirror to the rotating shaft, and a rotor portion having a magnet in the flange portion or a member engaged with the flange portion; a sleeve having a dynamic pressure generating groove that generates dynamic pressure when the sleeve is fitted together with the rotary member, and a rotated body having a stator portion having a coil disposed at a position facing the magnet; In the deflection scanning device, the rotating mirror is rotated to drive the rotating mirror to scan the light beam emitted from the light source, characterized in that the center of gravity of the rotating body is provided near the dynamic pressure generating groove of the sleeve. Deflection scanning device. (2) A rotating shaft, a flange portion for attaching a rotating mirror to a sleeve that is fitted with the rotating shaft and generates dynamic pressure, and a member engaged with the flange portion has a magnet. By means of a deflection scanning motor that has a rotor part and a stator part in which a coil is arranged in a position facing this magnet,
In a deflection device that drives a rotating mirror to scan a light beam emitted from a light source, the flange part of the deflection scanning motor and the rotating mirror are arranged around a dynamic pressure generating part, and the rotor part is arranged below the rotating mirror. A deflection scanning device characterized by having a concave shape. (3) The deflection scanning device according to claim 4, wherein the concave shape of the rotor portion is located inside the inscribed circle of the rotating mirror.