JP2012073433A - Optical scanner and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanner and an image forming apparatus provided therewith in which vibration of a first and a second mirror can be suppressed with no increase in cost and weight, and with a very simple structure.SOLUTION: An optical scanner at least includes optical scanning means for deflecting and scanning a light beam radiated from a light source, first mirrors for changing the direction of the light beam scanned by the optical scanning means, second mirrors for further reflecting the light beam reflected by the first mirrors, and photoreceptors irradiated with the light beam reflected by the second mirrors. One end side along the longitudinal direction of the respective first mirrors is contacted with or made close to one end side along the longitudinal direction of the respective second mirrors. Also, joining means joins a part or all of the mutual end side of each mirror which is contacted with or made close to each other.

Description

  The present invention relates to an optical scanning device and an image forming apparatus including the optical scanning device, and more particularly to an optical scanning device and an image forming apparatus that can improve the shape stability of an optical system and prevent image blurring. Is.

  Conventionally, two optical scanning means such as two polygon mirrors, two light sources provided corresponding to each of the optical scanning means, and the optical scanning means provided on opposite sides of the respective optical scanning means. An optical scanning device is known which comprises four primary mirrors that reflect light from each light source scanned by the means. The above optical scanning means is rotationally driven, and its rotational axis is set in parallel. As an example of such optical scanning means, the one shown in FIG. 1 or FIG. 5 of Patent Document 1 is known.

In such a known optical scanning device, two polygon mirrors (one example of optical scanning means) are provided in parallel and integrated, and a light source is provided on the opposite side of each polygon mirror to scan light radially. Therefore, an excellent apparatus can be provided in that the optical scanning apparatus can be remarkably reduced in size.
However, in the known optical scanning device, the surface including the polygon mirror and the primary mirror that reflects the light beam from the polygon mirror, the surface on which the final mirror that reflects the light is arranged on the photosensitive member, and the photosensitive member are further provided. Since the three surfaces arranged side by side are arranged in this order, there is a problem in that the size of the entire optical scanning device in the vertical direction (the rotation axis direction of the polygon mirror) increases.
Therefore, the applicant arranges a polygon mirror and a surface including a primary mirror that reflects light rays from the polygon mirror on one side of the surface on which the final mirror that reflects light is arranged side by side on the photoconductor, An optical scanning device capable of reducing the size of the entire optical scanning device in the vertical direction (the rotational axis direction of the polygon mirror) by arranging a surface on which the photosensitive members are arranged side by side, and an image including the same An application for a forming apparatus has already been filed (Japanese Patent Application No. 2010-038500).

FIG. 1 shows an outline of the optical system of the above-described optical scanning device.
As shown in FIG. 1, a polygon mirror PM as an example of optical scanning means, two light sources (not shown) corresponding to the polygon mirror PM, and opposite sides across the polygon mirror PM. The two first mirrors M11 and M12 that reflect the light from each light source scanned by the polygon mirror PM and the light sources scanned by the polygon mirror PM are imaged on the first mirror M11 and M12. The imaging lenses L11 and L12 are configured to be provided. L11 and L12 are fθ lenses, respectively. In this case, a case where two fθ lenses form one set is illustrated.
The first mirrors M11 and M12 are primary mirrors of the prior art.

  Each of D1 and D2 is a photoconductor, and a laser beam (hereinafter referred to as a light beam) emitted from each light source is scanned by a rotating polygon mirror PM, and passes through fθ lenses L11 and L12 to be a first mirror M11. , M12, and further reflected by the first mirrors M11, M12 by the second mirrors M21, M22 disposed at 90 degrees as viewed in the longitudinal section thereof, and then the third mirrors M31, M32 Then, the photosensitive members D1 and D2 are irradiated to form an electrostatic latent image.

In the case where such an optical scanning device X1 is a normal color image forming device, one polygon mirror PM is allocated to two light sources in order to support four colors of YMCK. Two sets are provided. Of course, as in the above-mentioned Patent Document 1, there are cases where the polygon mirrors PM are stacked in two upper and lower stages, but in either case, one polygon mirror PM is assigned to two light sources. It has the advantage of reducing the manufacturing cost in that the number of polygon mirrors can be reduced. Further, as described above, in the configuration shown in FIG. 1, as shown in FIG. 1, on the one side of the surface (first surface) on which the final mirror that reflects light is arranged side by side on the photosensitive member. The surface (second surface) including the polygon mirror and the primary mirror that reflects light rays from the polygon mirror is disposed, and the surface (third surface) on which the photoconductors are disposed side by side is disposed on the other side. As a result, the size of the entire optical scanning device in the vertical direction (the rotation direction of the polygon mirror) is reduced.

However, in the optical scanning device X1 shown in FIG. 1, the first mirror M11 and the second mirror M21 (or the first mirror M12 and the second mirror M22) are respectively shown in FIG. The mirrors are supported at both ends in the longitudinal direction, but these mirrors have a considerably elongated shape (elongated in the direction perpendicular to the paper surface of FIG. 1), and are only supported by the housing at both ends. Therefore, the structure is easy to vibrate in the direction of the arrow shown in the figure. In particular, these mirrors are placed near the polygon mirror PM that rotates at high speed, and the polygon mirror and the polygon motor that drives the mirror rotate at high speed, causing vibration during operation and adversely affecting the trajectory of the light beam. Is likely to be disturbed.
In order to prevent this, it is conceivable that the first and second mirrors are made of thick glass or a reinforcing member is applied. However, thick glass increases the weight of the device and makes it difficult to reinforce. If this is done, the number of components will increase and it will become expensive.
Therefore, the present invention has been made to solve the above-described problems in the prior art, and the vibrations of the first and second mirrors, which are easy to vibrate because of the long length constituting the optical scanning unit, are as follows. An object of the present invention is to provide an optical scanning device that can be suppressed with a very simple configuration without increasing costs and without increasing the weight, or an image forming apparatus including such an optical scanning device.

To achieve the above object, an optical scanning device according to the present invention includes an optical scanning unit that deflects and scans a light beam emitted from a light source, and a first mirror that changes the direction of the light beam scanned by the optical scanning unit. And an optical scanning device comprising at least a second mirror for further reflecting the light beam reflected by the first mirror, and a photosensitive member irradiated with the light beam reflected by the second mirror, One end side along the longitudinal direction of the first mirror and one end side along the longitudinal direction of the second mirror are in contact with or close to each other, and part or all of the one end sides of the mirrors in contact with or in close proximity are It is configured as an optical scanning device that is bonded to each other by a bonding means.
Since the first and second mirrors as described above have a long and narrow shape as described above, the rigidity is low in the mirror thickness direction but extremely high in the mirror plane direction. Therefore, if the two mirrors are joined at one end along the longitudinal direction as described above, if both mirrors have an angle, the mutual rigidity will be enhanced. Can be reduced.
Further, in such an optical scanning device, the rigidity can be enhanced most when the first and second mirrors are arranged at 90 degrees in a sectional view in the longitudinal direction.
Each of the first and second mirrors is supported by a casing or the like at the end in the longitudinal direction, and joined by the joining means at the middle in the longitudinal direction as one structure. Conceivable.
The optical scanning device of the present invention is an optical scanning device comprising at least two optical scanning means whose rotation axes are parallel and two light sources provided corresponding to each of the optical scanning means, The first mirror can be applied to an optical scanning device that is provided on the opposite side of each optical scanning unit and reflects four rays from each light source scanned by each optical scanning unit. It is.
The optical scanning device of the present invention can be used for an image forming apparatus.

  As described above, the optical scanning device according to the present invention includes the optical scanning unit that deflects and scans the light beam emitted from the light source, the first mirror that changes the direction of the light beam scanned by the optical scanning unit, and the first mirror. An optical scanning device comprising at least a second mirror for further reflecting the light beam reflected by the first mirror and a photosensitive member to which the light beam reflected by the second mirror is irradiated. The one end side along the longitudinal direction of the mirror and the one end side along the longitudinal direction of the second mirror are in contact with or close to each other, and a part or all of the one end sides of each of the contacted or adjacent mirrors are joined to each other. Therefore, the entire assembly of the first and second mirrors can be secured with extremely high rigidity, and image distortion and distortion can be prevented.

Sectional drawing of the conventional optical scanning device. 1 is a cross-sectional view of an optical scanning device according to an embodiment of the present invention. The figure which shows an example of the attachment structure of the mirror used for the optical scanning device concerning one Embodiment of this invention. 1 is a conceptual diagram of an entire image forming apparatus according to an embodiment of the present invention. 1 is a block diagram showing a control system of an image forming apparatus according to an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.

First, the overall configuration of the image forming apparatus Y according to the embodiment of the present invention will be described using the cross-sectional view shown in FIG. 4 and the control block diagram shown in FIG.
The image forming apparatus Y is a printer that is an example of a tandem type image forming apparatus that uses toner of four colors of black (BK), magenta (M), yellow (Y), and cyan (C).
The image forming apparatus Y includes an image forming unit α1, which forms a toner image, and forms an image on a recording sheet, a paper feeding unit α2, which supplies the recording sheet to the image forming unit α1, and a recording sheet on which the image is formed. Is discharged.
Image information (print job) received from a communication unit (not shown) from an external device such as a personal computer is black (BK), magenta (M), yellow (Y), cyan (C) by an image processing unit 12 to be described later. Are converted into pixel gradations which are grayscale information for each pixel for each of the four colors.

The image forming unit α1 uniformly forms the surface of each of the four photosensitive members 1 (1BK for black, 1M for magenta, 1Y for yellow, and 1C for cyan) carrying the images of the four colors. The charging device 3 (3BK, 3M, 3Y, 3C) to be charged, and the surface of each of the photoreceptors 1 charged in advance by the charging device 4 has an exposure amount corresponding to the pixel gradation determined by the image processing unit 12. An exposure source 2 (2BK, 2M, 2Y, 2C) for writing an electrostatic latent image on the photosensitive member 1 by irradiating (exposing) light to each pixel, and supplying toner to the electrostatic latent image Developing device 5 (5BK, 5M, 5Y, 5C) for developing as an image, intermediate transfer belt 7 for sequentially transferring the toner image formed on the surface of each of photoreceptor 1 and transferring the toner image to a recording paper, recording Transport paper Feed roller 8, fixing device 9 for heating and fixing the toner image transferred on the recording paper, and static eliminating device 4 (4 BK, 4 M, 4 Y, 4 C) for eliminating the charge on the surface of the photoreceptor 1 after the toner image is transferred to the recording paper. Etc. are schematically configured.
Optical scanning according to the present invention is performed in order to expose and scan the light beams of the respective colors emitted from the exposure source 2 (2BK, 2M, 2Y, 2C) onto the photoreceptor 1 (1BK, 1M, 1Y, 1C), respectively. Device X1 is used. Details of the optical scanning device X1 will be described later.

The photoconductor 1 is, for example, an a-Si photoconductor that is excellent in durability because of its high hardness and stable properties, and on the other hand, in addition to sensitivity unevenness, charging unevenness is likely to appear relatively remarkably.
The charging device 3 uniformly charges the surface of the photoconductor 1 along its axial direction. If the photoconductor 1 is unevenly charged, after charging by the charging device 3 (before exposure) ) Distribution (initial potential).
The exposure source 2 shown in FIG. 4 is constituted by an LED array in which a plurality of LEDs are arranged for each pixel in the axial direction (main scanning direction) of the photoreceptor 1 (1BK, 1M, 1Y, 1C). An example is shown. In addition, the exposure source 2 may be constituted by a laser scanning device or the like that scans laser light in the axial direction of the photoreceptor 1.
The developing device 5 includes a developing roller for supplying toner to the photosensitive member 1, and the developing device 5 has the potential (developing bias potential) applied to the developing roller and a potential gap between the surface of the photosensitive member 1 and the developing roller 5. The toner on the developing roller is attracted onto the surface of the photoreceptor 1 and the electrostatic latent image is visualized as a toner image.
The paper feeding unit α2 is roughly configured to include a paper feeding cassette 20, a paper feeding roller 6, and the like. The recording paper previously stored in the paper feed cassette 20 is conveyed to the image forming unit α1 when the paper feed roller 6 is driven to rotate.
The recording paper delivered from the paper feeding unit α2 is transferred by the transfer roller 8 and the toner image is transferred from the intermediate transfer belt 7. Then, the recording paper on which the toner image has been transferred is conveyed to the fixing device 9, and is heated and fixed on the recording paper by, for example, a heating roller, and then conveyed to the paper discharge unit α3 and discharged.

Next, the structure of the optical scanning device X1 according to an embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 2, the optical scanning device X1 according to this embodiment includes a polygon mirror PM as an example of optical scanning means, as in the conventional optical scanning device. When the image forming apparatus handles four colors, the polygon mirror PM is a set of two (PM1, PM2). The two polygon mirrors PM1 and PM2 have parallel rotation axes. Two light sources composed of laser light sources such as light emitting diodes are provided for each polygon mirror PM, corresponding to the polygon mirrors PM1 and PM2. These light sources are not shown, but are well known and will not be described.
Two first mirrors M11 and M12 for reflecting light rays from the respective light sources scanned by the respective polygon mirrors PM are provided on opposite sides of the respective polygon mirrors PM.
In this embodiment, two fθ lenses L11 are provided between the polygon mirror PM1 and the first mirror M11, and an fθ lens L12 is provided between the polygon mirror PM1 and the first mirror M12. Yes.
The light beam reflected by the second mirrors 21 and 22 is then reflected by the third mirror M3 and applied to the photoreceptor D.

The first mirrors M11 and M12 are provided with an inclination of 45 degrees with respect to the horizontal plane in order to reflect the irradiated light rays downward. The first mirrors M11 and M12 are respectively provided below the first mirrors M11 and M12. The mirrors M21 and M22 are installed with an inclination of 45 degrees with respect to the horizontal plane in order to reflect the light received from the first mirrors M11 and M12 in the horizontal direction. Accordingly, the first mirror M11 and the second mirror M21, and the first mirror M12 and the second mirror M22 are arranged at an angle of 90 degrees.
Further, the first mirror M11, M12 and the second mirror M21, 22 are arranged along one end side N1 along the longitudinal direction of the first mirror M11, M12 and along the longitudinal direction of the second mirror M21, 22. In addition, it is installed at a position where the one end side N2 comes into contact with or is close to. A part or all of one end sides N1 and N2 of the mirrors in contact with or close to each other are joined to each other by joining members S1 and S2.

The joining members S1 and S2 may respectively join the first mirror M11 and the second mirror M21, and the first mirror M21 and the second mirror M22 by bonding, or The mirrors may be fitted into the fitting grooves provided in the joining members S1 and S2 and joined, or may be joined by another structure such as a clip.
Even if the mirror is joined as described above, it is possible to join not only the mirror itself but also a frame holding the mirror.
As described above, the first mirrors M11 and M12 and the second mirrors M21 and M22 are arranged at 90 degrees in a longitudinal sectional view, and the direction of each vibration is as shown by an arrow in the figure. Orthogonal. Since each mirror has a rectangular cross section, it has a very high rigidity and hardly vibrates in the direction of 90 degrees with respect to each of the vibration directions.
Therefore, when the one end sides N1 and N2 of each mirror are joined to each other by the joining members S1 and S2 as described above, the vibration of the first mirror M11 causes the second mirror M21 that is long in a direction perpendicular to the first mirror M11. On the contrary, the vibration of the second mirror M21 is suppressed by the first mirror M11 that is long in the direction perpendicular to the second mirror M21.
The same applies to the relationship between the first mirror M12 and the second mirror M22. Since both the mirrors are joined by the joining member S2, the vibration of the first mirror M21 is long in the direction perpendicular thereto. A relationship is established in which the vibration of the second mirror M22 is suppressed by the second mirror M22, and conversely, the vibration of the second mirror M22 is suppressed by the first mirror M21 that is long in the direction perpendicular thereto.

The vibration suppressing effect as described above is always established between mirrors that are close to or in contact with each other with a right-angle direction. Therefore, the effect of suppressing vibration is not established only for the first mirror and the second mirror as described above. In other words, the present invention can be applied to any mirrors that are close to or in contact with each other at right angles.
If the mirrors that are close to or in contact with each other are joined together, the mutual vibration suppression effect as described above is most strongly exhibited. However, such a joined part is a part of the mirror in the longitudinal direction. Even if it is joined at, it is fully demonstrated.

For example, in the example shown in FIG. 3A, the first mirror M1 and the second mirror M2 are respectively supported by the casing at their longitudinal ends, and the first mirror M1 and A joining member S that joins only the central portion in the longitudinal direction of the second mirror M2 is provided, and the two mirrors M1 and M2 are joined to each other only at one place.
When the vibration due to the polygon mirror PM or the like is small, the vibration of the two mirrors M1 and M2 is sufficiently suppressed with such a simple joining structure. For the joining, a member different from the mirror such as the joining member S may be used. For example, as shown in FIG. 3B, the mirrors M1 and M2 are entirely brought into contact with each other, and a part thereof is UV-bonded. It is also possible to join by bonding by other methods.
Of course, the joining member S or the bonding portion may be provided at a plurality of locations in the longitudinal direction of the mirror, and in that case, the vibration suppressing function is further improved.
The above-mentioned joining member S and the bonding location are examples of the joining means in the present invention.
When the vibration is large, the two mirrors M1 and M2 may be joined over the entire length. FIG. 3 (c) corresponds to such a case, and the first mirror M1 and the second mirror M2 are in contact with each other at one end side N1, N2 over the entire length, and are bonded at that portion. This is an example. Since the first mirror M1 and the second mirror M2 are integrated by such adhesion over the entire length and become a very strong member, vibrations in both mirrors are highly suppressed.

  The optical scanning device X1 described above includes at least two polygon mirrors PM whose rotation axes are parallel and two light sources provided corresponding to each polygon mirror PM. As described in Patent Document 1, the mirror M1 is four mirrors that are provided on opposite sides of the polygon mirrors PM and reflect light rays from the light sources scanned by the polygon mirrors PM. Needless to say, this also applies to the optical scanning device.

  The optical scanning device according to the present invention can be applied not only to a document reading device such as a scanner, but also to a copying machine equipped with such a document reading device, an image forming device such as a facsimile, or their function and scanner function. The present invention can be applied to an image forming apparatus as a multifunction machine including

X1... Optical scanning device Y... Image forming apparatus 1 (1BK, 1M, 1Y, 1C)... Photoconductor PM1, PM2.
M11, M12, M21, M22 ... primary mirrors W11, W12, W21, W22 ... optical paths M1, M11, M12 ... first mirrors M2, M21, M22 ... second mirror S ... joining members N1, N2 ... one end side

Claims (5)

An optical scanning means for deflecting and scanning a light beam emitted from a light source;
A first mirror that changes the direction of the light beam scanned by the optical scanning means, and a second mirror that further reflects the light beam reflected by the first mirror;
An optical scanning device comprising at least a photosensitive member irradiated with light rays reflected by the second mirror,
One end side along the longitudinal direction of the first mirror and one end side along the longitudinal direction of the second mirror are in contact with or close to each other, and part or all of the end sides of each of the mirrors in contact with or close to each other An optical scanning device in which the two are joined together by a joining means.   The optical scanning device according to claim 1, wherein the first and second mirrors are arranged at 90 degrees in a cross-sectional view in the longitudinal direction.   The first and second mirrors are respectively supported at their longitudinal ends, and are joined by the joining means at their longitudinal intermediate portions. Optical scanning device. The optical scanning device is an optical scanning device including at least two optical scanning units having parallel rotation axes, and two light sources provided corresponding to the respective optical scanning units,
4. The four mirrors according to claim 1, wherein the first mirrors are four mirrors that are provided on opposite sides of the optical scanning units and reflect light beams from the light sources scanned by the optical scanning units. The optical scanning device according to any one of the above.   An image forming apparatus comprising the optical scanning device according to claim 1.

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