JP2000131635A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the mounting accuracy of a laser beam scanner and to attain the improvement of a reproduced image by extremely eliminating the influence of vibration transmitted to the laser beam scanner. SOLUTION: A printer head 10 is attached at a mounting pedestal 30, and mounting members 31-34 are provided at four end parts of the mounting pedestal 30 and the mounting members 35 and 36 are respectively provided at the nearly center part of the mounting pedestal 30 in the direction of an arrow A. Also, supporting members 52-57 respectively supporting the mounting members 31-36 are provided at a front frame 50 and a rear frame 51. Then, a vibrationproof rubber 40 intervenes between the mounting members 31-34 and the supporting members 52-55. The mounting member 35 and the supporting member 56 and the mounting member 36 and the supporting member 57 are fixed by a screw S without having the vibrationproof rubber in between.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which scans a light beam with a light beam scanning device to draw an image on a drawing target such as a photosensitive drum. The present invention relates to an improvement in a technique of supporting a forming apparatus body frame.

[0002]

2. Description of the Related Art A laser beam scanning device used in an image forming apparatus such as a digital copier or a laser printer emits a laser beam by driving a laser diode in accordance with image data, and rotates the laser diode with a polygon mirror. The photosensitive drum is deflected to perform exposure scanning on the photosensitive drum.
By this exposure scanning, an electrostatic latent image is formed on the photosensitive drum, and this is developed to form an image.

FIG. 5 is a view showing a state in which a laser beam L emitted from a laser beam scanning device 80 performs exposure scanning on a photosensitive drum 90. The laser beam scanning device 80 is mounted on a mounting base 81 fixed to the front frame 70 and the rear frame 71 of the image forming apparatus with two screws S, respectively. However, according to this configuration, since the mounting pedestal 81 is fixed to the front frame 70 and the rear frame 71 by screwing, the driving device of the photosensitive drum 90 and the sheet feeding / conveying device ( Mechanical vibration (hereinafter, referred to as “external vibration”) generated from a power transmission system such as a power transmission system (not shown) is transmitted from the front frame 70 and the rear frame 71 to the laser beam scanning device 80 via the mounting base 81. As a result, the laser beam scanning device 80 vibrates, and the position of the scanning line 91 by the laser beam L fluctuates, resulting in a problem that the reproduced image is deteriorated.

Therefore, a method of reducing vibration of the mounting pedestal 81 generated by external vibration by using vibration isolating means has been adopted. FIG. 6 shows an example of this method,
FIG. 6 is a diagram when the mounting base 81 is viewed from the direction of arrow C in FIG. 5. As shown in the figure, supporting members 72 and 73 are provided on the front frame 70 and the rear frame 71, respectively, and a vibration isolating rubber 82 is interposed between the supporting members 72 and 73 and the mounting base 81, and these are screwed or the like. Fix it. This anti-vibration rubber 8
By virtue of 2, vibration transmitted to the mounting pedestal 81 is reduced to a level that does not lead to deterioration of the reproduced image, thereby suppressing deterioration of the reproduced image.

[0005]

However, the method of attaching the laser beam scanning device to the main body of the image forming apparatus via the above-described vibration isolating means has a problem that the attachment accuracy is poor. That is, when the vibration-proof rubber 82 is not high in its own dimensional accuracy, and when it is fixed by tightening with screws or the like, the thickness of the vibration-proof rubber 82 changes when it is compressed, so that the positioning adjustment takes time and effort. Even if it is positioned at the correct position, the weight of the laser beam scanning device 80 itself is increased, and it shrinks with time in the thickness direction,
The mounting height of the laser beam scanning device 80 varies.
In particular, when there is a difference in the way in which the respective vibration-proof rubbers 82 contract, the mounting base 81 is inclined. In such a case, the scanning line 91 is not parallel to the rotation axis of the photosensitive drum 90 and is inclined left and right, so that the image is significantly deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and improves the mounting accuracy of a laser beam scanning device and eliminates the influence of vibration transmitted to the laser beam scanning device as much as possible. Accordingly, an object of the present invention is to provide an image forming apparatus capable of improving the quality of a reproduced image.

[0007]

According to the present invention, there is provided an image forming apparatus which scans a light beam with a light beam scanning device to draw an image on an object to be drawn.
The mounting pedestal of the light beam scanning device is supported by the apparatus main body frame without a vibration isolating means at a first position substantially at the center in a direction toward the object to be drawn, and at a position other than the first position. In the second position, it is supported by the apparatus main body frame via a vibration isolator.

The second position is at least one of both ends of the mounting pedestal in a direction toward the object to be drawn. Further, the mounting base is rotatably supported by the apparatus body frame at the first position so as to be rotatable around an axis orthogonal to a direction toward the object to be drawn.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described by taking as an example a case where the present invention is applied to a monochrome laser printer (hereinafter simply referred to as "printer"). FIG. 1 is a diagram showing a schematic configuration of the entire printer. This printer reproduces an image on a recording sheet based on image data input from an external device such as a personal computer. When image data is input from an external device, the control unit 1 converts the image data into a drive signal of a laser diode, and drives a laser diode 12 (FIG. 2) inside a printer head 10 which is a light beam scanning device. The laser beam L emitted from the laser diode 12 is deflected by the folding mirror 2, and then exposes the surface of the photosensitive drum 4 in the main scanning direction.

Around the photosensitive drum 4, a drum cleaner 5, an eraser lamp 6, a charging charger 7, a developing device 8
And a transfer charger 9. Photoconductor drum 4
Before the exposure with the laser beam L, the residual toner is removed by the drum cleaner 5, irradiated with the eraser lamp 6, and then uniformly charged by the charging charger 7. When the charged surface of the photosensitive drum 4 is exposed, an electrostatic latent image is formed, and this electrostatic latent image is visualized as a toner image by the developing device 8.

On the other hand, a recording sheet is fed from a sheet feeding cassette 20 by a pickup roller 21 and a timing roller 22. This recording sheet is a transfer belt 2
By 3, the sheet is conveyed to a transfer position immediately below the photosensitive drum 4. At the transfer position, the toner image on the photosensitive drum 4 is transferred to the recording sheet by the operation of the transfer charger 9. The recording sheet onto which the toner image has been transferred is further conveyed by a transfer belt 23 and a conveyance belt 24, and after the toner is fixed by a fixing device 25, the discharge tray 2
It is discharged to 6.

FIG. 2 is a schematic structural view of the inside of the printer head 10 as viewed from above. Printer head 10
Is constructed by housing a laser diode 12, a collimator lens 13, a cylindrical lens 14, a polygon mirror 15, a toroidal lens 16, an fθ lens 17, and the like in a casing 11. In the above configuration, the laser beam L emitted from the laser diode 12 becomes parallel light by the collimator lens 13, is condensed in the sub-scanning direction by the cylindrical lens 14, and is rotated at a constant speed by a polygon motor (not shown). The light is deflected by the mirror 15. Thereafter, the light passes through the toroidal lens 16 and the fθ lens 17 and reaches the folding mirror 2 as described above.

FIG. 3 is a perspective view showing an example of a method of supporting the printer head 10, and a part of the front frame 50 is cut away for convenience of explanation. As shown in the figure, the printer head 10 is attached to a mounting base 30, and the mounting base 30 is suspended between a front frame 50 and a rear frame 51 of the printer main body. Then, a substantially center position (hereinafter, referred to as an arrow A direction) of the mounting base 30 on the front frame 50 side (a direction toward the photosensitive drum 4).
Simply referred to as "center position". ) And mounting members 35, 31, 32 are provided at two places at both ends. On the rear frame 51 side of the mounting base 30, the mounting members 36, 33, 34 are located at the same positions in the direction of arrow A.
Are respectively provided. On the other hand, the front frame 50 and the rear frame 51 are provided with support members 52 to 57 for supporting the attachment members 31 to 36, respectively. In the figure, a part of the front frame 50 is cut away,
The support members 52, 53, 56 are indicated by broken lines.

The mounting members 31 to 34 and the supporting member 5
A well-known anti-vibration rubber 40 is interposed between 2 and 55. The contact surface between the vibration isolating rubber 40 and each plate is adhered with an adhesive so that external vibrations can be reliably absorbed. Further, between the mounting member 35 and the supporting member 56 and between the mounting member 36 and the supporting member 57 are fixed by screws S without interposing the anti-vibration rubber 40.

In the above configuration, the mounting base 30 is connected to the front frame 50 and the rear frame 51 via the rubber cushion 40.
The front frame 5 is directly supported by the screws S.
0, since the printer head 10 is fixed to the rear frame 51, first, most of the printer head 10 is screwed to the front frame 50,
Since it is directly supported by the rear frame 51, the weight applied to the vibration isolating rubber 40 is extremely small. For this reason, the shrinkage due to long-term use of the vibration-proof rubber 40 is not as large as that of the conventional configuration using only the vibration-proof rubber, and the posture of the printer head 10 is maintained in a constant posture for a long time. On the other hand, in the above configuration, the previous frame 50,
Assuming that the external vibration has propagated to the rear frame 51, the vibration tends to propagate to the mounting base 30 via the vibration isolating rubber 40 and the screw S. In this case, the vibration isolating rubber 40 , The propagation of the external vibration to the mounting base 30 through the vibration isolating rubber 40 is as follows.
It is surely blocked.

On the other hand, since the screw S is connected and fixed between the mounting member 35 and the supporting member 56 and between the mounting member 36 and the supporting member 57, propagation of external vibration to the mounting base 30 cannot be prevented. Will propagate to the mounting base 30 as it is. However, the mounting member 3 serving as the vibration propagation path
Since the reference numerals 5 and 36 are provided at substantially the center position of the mounting base 30, the vibration of the mounting base 30 is suppressed to the lightest vibration form for the printer head 10. That is, the mounting members 35 and 36 are attached to the mounting base 3.
0 means that the mounting base 30 is located at the center of gravity of the front frame 50,
It means that it is supported by the rear frame 51, and the external vibration propagates to the mounting base 30 through the position of the center of gravity.

By the way, the position of the center of gravity is on the mounting base 30,
Since it is the most balanced position, even if external vibration propagates to the position, it does not generate a rotational moment on the mounting pedestal 30, but simply moves the mounting pedestal 30 in the vibration direction by the amount of vibration of the external vibration. It only translates. The printer head 1 mounted on the mounting base 30
0 also does not rotate or swing due to external vibrations, but only translates similarly. This means that the laser beam L emitted from the printer head 10 and irradiating the photosensitive drum 4 simply moves in parallel without changing the irradiation angle. Since the amplitude of the external vibration is generally small, the amount of parallel movement of the laser beam L is also a small value corresponding to the amplitude of the external vibration, and it can be said that the image hardly affects the image quality.

It is needless to say that the present invention is not limited to the above embodiment, and the following modified examples can be considered. (1) In the above-described embodiment, the printer is screwed and fixed to the front frame 50 and the rear frame 51 of the printer main body at substantially the center position of the mounting pedestal 30. However, bonding is performed by fixing means other than screws, such as an adhesive. You may make it. Alternatively, the center position may be supported without being fixed.

FIG. 4A shows that the mounting base 30 which is pivotally supported at the center position is moved from the direction of arrow B in FIG.
4 (b) is a plan view of the mounting base 30, showing only the front frame 50 side. From both figures, a shaft 37 is provided at a substantially central position of the mounting base 30 toward the front frame 50, and the shaft 37 is connected to the front frame 50 via a bearing 38.
Are supported by a support member 58 provided at the bottom. Here, the contact surface between the support member 58 and the bearing 38 is bonded by an adhesive. The method of supporting the left and right ends is the same as in the above embodiment. Although not shown, the rear frame 51 has the same configuration. In the present modified example, with such a configuration, the mounting base 30 is rotatable around the shaft 37 as a fulcrum. Therefore, even if the external vibration transmitted from the front frame 50 and the rear frame 51 via the shaft 37 includes a component that rotates the mounting pedestal 30, the external vibration is transmitted through the bearing 38. Since the rotation component is not transmitted to the mounting pedestal 30, there is an effect that operations such as rotation and swing of the printer head 10 can be prevented. The means for supporting the mounting pedestal 30 is not limited to a method using a contact type bearing such as the bearing 38, but may use a non-contact type magnetic bearing, for example.

(2) In the above embodiment, the vibration isolating rubber 40 is used as the vibration isolating means, but another vibration isolating member, for example, a damper may be used. (3) In the above embodiment, the printer head 10 and the mounting pedestal 30 are separate members. However, the same applies when the casing 11 of the printer head 10 is supported by the front frame 50 and the rear frame 51 as the mounting pedestal 30. The effect of is obtained.

(4) In the above embodiment, the vibration isolating rubber 40
Are provided at four positions at the end of the mounting base 30,
Either end, for example, the attachment member 31 and the support member 5
Almost the same effect can be obtained by providing only between the two members and between the mounting member 33 and the support member 54. Also,
It is not necessary to limit the position where the anti-vibration rubber 40 is interposed and supported to the end portion, and it may not be a plurality of positions. For example,
Even if only one position other than the center position is supported with the vibration isolating rubber 40 interposed, a certain effect can be obtained. This is because, even with such a configuration, the printer head 10 is unlikely to rotate or swing as described above.

(5) In the above embodiment, a mono-color printer has been described, but the present invention is not limited to this.
The present invention can be generally applied to an image forming apparatus such as a full-color laser beam printer or a digital copying machine having a light beam scanning device for scanning a light beam as an image writing unit.

[0023]

As described above, according to the present invention, the mounting pedestal of the light beam scanning device is provided at the first position substantially at the center in the direction toward the object to be drawn without using the vibration isolating means. In addition to being supported by the apparatus body frame, at a second position other than the first position, it is supported by the apparatus body frame via a vibration isolating means. This makes it possible to maintain the light beam scanning device in a fixed posture while maintaining the anti-vibration effect of the anti-vibration means, so that the mounting accuracy is improved and the quality of a reproduced image can be improved as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an overall configuration of a printer according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of the inside of a printer head of the printer as viewed from above.

FIG. 3 is a perspective view illustrating an example of a method of supporting a printer head.

FIG. 4A is a front view showing an example of another method of supporting a printer head, and FIG. 4B is a plan view.

FIG. 5 is a perspective view showing an example of a conventional method of supporting a laser beam scanning device.

FIG. 6 is a diagram showing an example of another conventional method of supporting a laser beam scanning device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Printer head 30 Mounting pedestal 31, 32, 33, 34, 35, 36 Mounting member 37 Shaft 38 Bearing 40 Anti-vibration rubber 50 Front frame 51 Rear frame 52, 53, 54, 55, 56, 57, 58 Support member

Claims (3)

[Claims] 1. An image forming apparatus that scans a light beam with a light beam scanning device to draw an image on a drawing target, wherein a mounting base of the light beam scanning device is substantially in a direction toward the drawing target. At a first position at the center, it is supported by the apparatus body frame without the vibration isolating means, and is supported by the apparatus body frame via the vibration isolating means at a second position other than the first position. An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein the second position is at least one of both ends of the mounting pedestal in a direction toward a drawing target. 3. The apparatus according to claim 1, wherein the mounting pedestal is rotatably supported by the apparatus body frame at the first position so as to be rotatable around an axis orthogonal to a direction toward the object to be drawn. Item 3. The image forming apparatus according to item 1 or 2.