JP4350567B2 - Optical housing, optical writing apparatus and image forming apparatus - Google Patents

Description

  The present invention includes an optical writing device that irradiates a scanning surface of an image carrier with a light beam to write a latent image, and develops the latent image formed on the image carrier with a developer, and then sequentially transfers the transfer material. The present invention relates to an optical housing, an optical writing apparatus, and an image forming apparatus, such as a copying machine, a printer, a facsimile machine, and a plotter, which form a multicolor image transferred to and fixed by a fixing unit.

Conventionally, the cooling of the writing unit by the heat generated by the deflector and the cooling of the lens have been performed by adding a lid member to the upper part of the polygon motor, and cooling by a fan motor and a duct, as shown in Patent Document 1. Thereby, the extra cost of another member, a fan motor, and a duct generate | occur | produced and it was a cost increase.
Further, Patent Document 2 devises a configuration in which a through hole is provided between the deflector and the FΘ lens so that heat from the deflector is not transmitted to the FΘ lens by heat transfer of the housing member.
In this configuration, the strength of the housing is lowered due to the through hole. In order to compensate for this, a beam is provided in a part of the through hole. This is contrary to the fact that it is difficult to transmit the heat.

As shown in the cross-sectional view of the optical writing device in FIG. 1, the heat transfer path of the temperature change of the FΘ lens due to the heat generated by the deflector has the following flow.
Deflector board (motor driver, coil, etc.) → Deflector housing mounting part → Housing member → FΘ lens receiving part → FΘ lens itself The FΘ lens causes a temperature change through such a heat transfer path. The following two types of temperature changes occur as the temperature changes.
One is a change in which only the FΘ lens receiver is first locally warmed.
The other is a change that spreads this local warming and raises the temperature of the entire FΘ.
Due to these two types of temperature changes, the temperature unevenness in one of the FΘ lenses and the temperature change of the entire FΘ lens cause magnification deviation (same magnification in a certain section) and mismatch of the overall magnification, resulting in image degradation. There is a problem of causing.

JP-A-10-221633 JP 2001-264666 A

  The present invention has been made in view of the above circumstances, and provides an optical housing, an optical writing device, and an image forming apparatus that are configured to be less susceptible to heat caused by external factors inside the optical writing device and optical elements. The task is to do.

As means for solving the above problems, the present invention has the following features.
In the optical housing of the present invention, the light beam from the light source unit is deflected and scanned by a single light deflector, and the light beam is projected on the surface to be scanned of the image carrier through an optical system arranged around the light deflector. In the optical housing of the optical writing apparatus configured to guide and form an image, the optical housing has two FΘ lenses facing each other , and each of the FΘ lenses has three FΘ lens receiving portions protruding from the horizontal wall of the housing. In each of the two FΘ lenses, one through hole is provided between the three FΘ lens receiving portions and the optical deflector arrangement portion, the housing is formed by molding, and the outer periphery of the through hole is provided. Of the optical housing , the region formed by connecting the outer periphery on the optical deflector side, wherein the region excluding the optical deflector is formed of aluminum, It is characterized in that is provided with ribs the through-hole, the side face or near the hole.
The Opti Cal housing of the present invention, further, characterized in that rib-shaped forms part of the airflow path.
The optical housing of the present invention is further characterized in that the shape of the FΘ lens receiving portion is a spherical or conical apex.
In the optical writing apparatus of the present invention is characterized by comprising the Opti Cal housing.
In the image forming apparatus of the present invention is characterized by comprising the optical writing device.

As described above, by the means for solving the above, in the optical housing of the present invention, the heat transmitted to the vicinity of the through hole is radiated in this portion by providing the rib shape on the side surface of the through hole or in the vicinity thereof. It is possible to prevent the strength from being lowered due to the through hole being formed by adding the cross-sectional shape by adding the rib.
Furthermore, in the optical housing of the present invention, since the air flow passage is formed in the lower space of the polygon motor and the rib arranged in the vicinity of the through hole, the cooling effect is further enhanced and the temperature increase of the FΘ lens can be suppressed. It is possible to prevent image deterioration and slow down the progress.
Furthermore, in the optical housing of the present invention, the rib portion or the vicinity thereof is made of a material having higher thermal conductivity than the other portions of the optical housing, so that the heat dissipation and cooling effects are further enhanced, and the temperature increase of the FΘ lens is suppressed. Image deterioration can be prevented, and the progress can be further slowed down.
Furthermore, in the optical housing of the present invention, the contact area between the housing and the FΘ lens is reduced by reducing the shape of the FΘ lens receiving portion to a hemispherical or conical point receiving shape, and therefore the heat transfer is reduced. The rise can be suppressed, image deterioration can be prevented, and the progress can be further slowed down.
In the optical writing device and the image forming apparatus of the present invention, the temperature increase of the FΘ lens can be suppressed, and a good image can be provided.

Hereinafter, the configuration, operation and action of the image forming apparatus according to the present invention will be described in detail based on the illustrated embodiments.
FIG. 2 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention, and FIG. 3 is a diagram showing an example of an optical writing device provided in the image forming apparatus shown in FIG. It is a top view which shows the structure by the side of the base | substrate upper surface of an insertion device.
The image forming apparatus shown in FIG. 2 is a full-color image forming apparatus in which a plurality of drum-shaped photoconductive photoreceptors (hereinafter referred to as photoreceptor drums) 1, 2, 3, and 4 are juxtaposed as a plurality of image carriers. These four photosensitive drums 1, 2, 3, 4 are, for example, images corresponding to the respective colors of black (Bk), cyan (C), magenta (M), and yellow (Y) in order from the left with respect to FIG. (The order of colors is not limited to this, and can be arbitrarily set). Around each of the four photosensitive drums 1, 2, 3, 4 is a charging unit (charging roller, charging brush, charging charger, etc.) 6, 7, 8, for image formation by an electrophotographic process. 9, exposure units of light beams L 1, L 2, L 3, and L 4 from the optical writing device 5, development units (development units of Bk, C, M, and Y colors) 10, 11, 12, and 13, and transfer A transfer belt 22 including transfer belt 22a and transfer means (transfer rollers, transfer brushes, etc.) 14, 15, 16, 17 disposed on the back surface thereof; and cleaning units (cleaning blades, cleaning brushes, etc.) 18, 19, 20, 21, etc. are arranged, and image formation of each color can be performed on each of the photosensitive drums 1, 2, 3, 4.

  More specifically, in FIG. 2, when the Z direction in the drawing is a vertically upward direction and the X and Y directions are horizontal directions, the parallel arrangement direction of the four photosensitive drums 1, 2, 3, 4 is relative to the horizontal plane. The transfer / conveying device 22 is substantially parallel to the direction in which the four photosensitive drums 1, 2, 3, and 4 are juxtaposed. The transfer material is fed from the lower side in the inclined direction and is transferred to the upper side by the transfer conveyance belt 22a and transferred to the four photosensitive drums 1, 2, 3, 4 The fixing device 26 is disposed on the downstream side in the conveyance direction of the transfer material and on the upper side in the inclination direction. The optical writing device 5 is disposed obliquely above an image forming unit in which four photosensitive drums 1, 2, 3, and 4 are arranged in parallel, and the housing 50 of the optical writing device 5 includes four photosensitive drums. Inclined frames 29, 30 of the image forming apparatus main body are arranged to be inclined with respect to a horizontal plane (X direction in the figure) so as to be substantially parallel to the direction in which the body drums 1, 2, 3, 4 are arranged in parallel. It is fixed to.

  Here, the optical writing device 5 includes four light source units 52, 53, 54, 55 and light beams L1, L2, An optical deflector 62 that deflects and scans L3 and L4 in two symmetrical directions, and a plurality of light beams that are symmetrically arranged in the two directions around the optical deflector 62 and deflected and scanned by the optical deflector 62 An optical system (imaging lenses 63, 64, 69, 70, 71, 72, and L1, L2, L3, L4) that guides L1, L2, L3, and L4 onto the scanned surfaces of the corresponding photosensitive drums 1, 2, 3, and 4, respectively. Optical path folding mirrors 65, 66, 67, 68, 73, 74, 75, 76, 77, 78, 79, 80, etc.). It is stored.

  More specifically, the housing 50 includes a base 50A on which the optical deflector 62 and the optical system are disposed, and a frame-like side wall 50B surrounding the base 50A, and the base 50A is substantially at the center of the side wall 50B. The four light source units 52, 53, 55, 55 are arranged on the side wall 50 B of the housing 50 and are arranged in the same direction as that of the photoconductors. The optical deflector 62 is disposed at a substantially central portion of the base 50A of the housing 50, and includes optical members (imaging lenses 63, 64, 69, 70, 71, 72, an optical path folding mirror 65, an optical system). 66, 67, 68, 73, 74, 75, 76, 77, 78, 79, 80, etc.) are arranged separately on both surfaces (upper surface side and lower surface side) of the base 50A. Covers 87 and 88 are provided at the upper and lower portions of the housing 50, and an opening through which the light beam passes is provided in the lower cover 87, and the dustproof glasses 83, 84, 85, and 86 are provided in the openings. Is attached.

  In the optical writing device 5, color-separated image data input from a document reading device (scanner) or an image data output device (personal computer, word processor, facsimile receiver, etc.) (not shown) is used as a light source driving signal. According to the conversion, the light source (semiconductor laser (LD)) in each light source unit 52, 53, 54, 55 is driven to emit a light beam. The light beams emitted from the respective light source units 52, 53, 54, and 55 pass through cylindrical lenses 56, 57, 58, and 59 for surface tilt correction and reach the optical deflector 62 directly or via the mirrors 60 and 61. Deflection scanning is performed in two symmetrical directions by two-stage polygon mirrors 62a and 62b rotated at a constant speed by a polygon motor 62c.

2, 3, 4, and 6, the polygon mirror is divided into two upper and lower stages for the L2 and L3 light beams and for the L1 and L4 light beams. A configuration in which deflection scanning is performed by a polygon mirror may be employed.
The light beams deflected and scanned in two directions by the polygon mirrors 62a and 62b of the optical deflector 62 in two directions pass through the imaging lenses 63 and 64 made up of, for example, FΘ lenses having two upper and lower layers, respectively. After being folded by the folding mirrors 65, 66, 67, 68 and passing through the opening of the base 51, the second imaging lenses 69, 70, 71, 72 made of, for example, a long toroidal lens are passed through, 2 Folding mirrors 73, 75, 77, 79, third folding mirrors 74, 76, 78, 80, dust-proof glass 83, 84, 85, 86, and photosensitive drums 1, 2, 3, 4 for each color. An electrostatic latent image is written on the scanning surface.

Next, as shown in FIG. 2, a transfer conveyance belt 22a stretched around a driving roller and a plurality of driven rollers is disposed under the four photosensitive drums 1, 2, 3, 4 arranged in parallel. It is conveyed by the driving roller in the direction indicated by the arrow in the figure. In addition, a plurality of paper feeding units 23 and 24 that store transfer materials such as recording paper are installed at the lower part of the main body of the image forming apparatus, and the transfer materials stored in the paper feeding units 23 and 24 feed paper. The paper is fed to the transfer / conveyance belt 22a via the rollers, the conveyance rollers, and the registration rollers 25, and is carried and conveyed by the transfer / conveyance belt 22a.
The latent images formed on the photoconductors 1, 2, 3, and 4 by the optical writing device 5 are developed with toners of Bk, C, M, and Y colors of the developing units 10, 11, 12, and 13, respectively. The developed toner images of Bk, C, M, and Y colors are carried on the transfer conveyance belt 22 a by the transfer units 14, 15, 16, and 17 of the transfer conveyance device 22. The images are sequentially superimposed on the transferred material. The transfer material onto which the four color images have been transferred is conveyed to the fixing device 26, where the image is fixed by the fixing device 26, and then discharged onto the paper discharge tray 28 by the paper discharge roller 27.

Incidentally, in the image forming apparatus having a configuration as shown in FIG. 1, the heat from the deflectors transmitted to FΘ lens through a path shown by the cross-sectional surface.
First, the motor driver, the stator coil, and the motor bearing arranged on the substrate of the deflector generate heat, and the heat is transmitted to the deflector housing attachment portions (four locations) in part A of FIG. It is transmitted to the horizontal wall of the housing of the B part, and from there to the FΘ lens by the FΘ lens receiving part of the C part of FIG.
On the other hand, in the FΘ lens, the vicinity of the lens receiving portion is first heated, and then heat is gradually transferred to the entire lens. Due to temperature non-uniformity and temperature change in one of the FΘ lenses, magnification deviation (equal magnification in a certain section) and overall magnification mismatch cause image deterioration.

For example, in the configuration as shown in FIG. 3, a through hole such as a hatched portion having substantially the same size as the FΘ lens is provided between the FΘ lens placement portion and the deflector placement portion.
In this case, the heat transferred from the motor, which is a heat generation source, to the FΘ lens through the housing is once blocked by a through hole in a linear heat transfer path as indicated by a dotted line. The degree of progress of the above-described image deterioration is slowed by the gentle transfer of heat and a low degree of change. In addition, when the polygon motor rotates for a long time, heat is transferred from the connecting part of the housing through the circuitous path as shown by the arrow in the figure. The temperature is transmitted more slowly than it is transmitted.

In the present invention, as shown in the cross-sectional view of FIG. 5, a rib shape is provided on the side surface of the through hole portion or in the vicinity thereof. With this rib, the heat transmitted to the vicinity of the through-hole portion can be radiated at this portion, so that the heat transmitted to the FΘ lens can be further reduced. Moreover, the trouble by providing the beam pointed out by the prior art can be prevented, preventing the strength fall by a through-hole by adding cross-sectional shape by rib addition.
In the present invention, when the FΘ lens is received at three points as will be described later, one through hole is provided between the FΘ lens receiving portion and the deflector arrangement portion as shown in FIG. Thus, while preventing the strength from being lowered, the effect of the longer path can be obtained in the same manner as described above.

  In the present invention, the cooling air flows from the front side of the machine to the rear side by the writing cooling fan shown in FIGS. FIG. 6 shows the cross-sectional view, but an air flow path is formed in the rib arranged in the vicinity of the through hole and the polygon motor lower space. As shown by the two-dot chain line in FIG. 4, the air flow channel is formed in the entire region in the vertical direction below the housing horizontal wall of the writing unit (the rib and the polygon motor lower space). For this reason, the cooling effect is further increased and the temperature increase of the FΘ lens can be suppressed.

  If the material of the housing is a mold, for example, aluminum generally has a higher thermal conductivity than the mold, and heat is more easily transmitted. In the present invention, the heat radiation and cooling effect can be further enhanced by manufacturing the housing shown in FIG. 7 with a mold and using aluminum as the material of the region indicated by the dotted line. FIG. 8 shows a cross-sectional shape of a portion indicated by a dotted line in FIG. When the rib shown in FIG. 8 forms the air flow channel, the cooling effect is further enhanced and the temperature increase of the FΘ lens can be suppressed.

  Further, in the present invention, as shown in FIG. 9, the FΘ lens receiving portion (three points in this embodiment) of the housing protrudes from the horizontal wall of the housing in a hemispherical shape so as to receive the FΘ lens. In the case of this configuration, the contact area between the FΘ lens and the housing is reduced compared to a columnar shape or the like, and heat transfer is reduced. Therefore, compared with the case where the FΘ lens is received in a cylindrical shape, the time for raising the temperature to the same temperature is delayed, and the progress of image degradation can be delayed.

FIG. 2 is a diagram illustrating an example of an optical writing device included in an image forming apparatus, and shows a heat transfer path from a deflector of the optical writing device to an FΘ lens in a cross-sectional view. 1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention. It is a figure which shows an example of the optical writing apparatus with which an image forming apparatus is equipped, Comprising: The through-hole position and heat-transfer path | route of an optical housing are shown. 1 is a schematic configuration diagram of an optical writing device according to an embodiment of the present invention, and shows an arrangement position of a writing cooling fan for flowing cooling air from the front of the machine to the rear. It is sectional drawing of the optical housing which provided the rib shape in the through-hole part side surface or the vicinity which shows one Example of this invention. It is sectional drawing of the optical writing apparatus which shows the arrangement | positioning position of a writing cooling fan, and an airflow flow path. It is the structure schematic of the optical writing device which shows the part which uses aluminum for the material of an optical housing. FIG. 9 is a cross-sectional view of the aluminum housing portion of FIG. 8. It is a figure which shows the shape of the F (theta) lens receiving part of an optical housing.

Explanation of symbols

1, 2, 3, 4 Photosensitive member 5 Optical writing device 6, 7, 8, 9 Charging unit 10, 11, 12, 13 Developing unit 14, 15, 16, 17 Transfer unit 18, 19, 20, 21 Cleaning unit 22 Transfer conveyance device 22a Transfer conveyance belt 23, 24 Paper feed unit 25 Registration roller 26 Fixing device 27 Paper discharge roller 28 Paper discharge tray 29, 30 Main body frame 50 Housing 50A Base 50B Side walls 52, 53, 54, 55 Light source unit 56, 57, 58, 59 Cylindrical lens 60, 61 Mirror 62 Optical polarizer 62a, 62b Polygon mirror 63, 64 Imaging lens 65, 66, 67, 68 First folding mirror 69, 70, 71, 72 For second imaging Lenses 73, 75, 77, 79 Second folding mirrors 74, 76, 78, 80 Third folding mirrors 83, 84, 85, 86 Dust-proof glass 87, 88 Cover L1, L2, L3, L4 Light beam

Claims (5)

The light beam from the light source unit is deflected and scanned by one optical deflector,
In an optical housing of an optical writing apparatus having a configuration in which a light beam is guided onto a scanned surface of an image carrier through an optical system disposed around an optical deflector, and imaged .
The optical housing has two opposing FΘ lenses,
Each of the FΘ lenses is received by three FΘ lens receiving portions protruding from the horizontal wall of the housing,
Each of the two FΘ lenses is provided with one through hole between the three FΘ lens receiving portions and the optical deflector arrangement portion,
Forming the housing with a mold;
Of the outer periphery of the through hole, the region formed by connecting the outer periphery on the optical deflector side, the region excluding the optical deflector is formed of aluminum,
The Opti Cal housing, Opti Cal housing, characterized in that is provided with ribs the through-hole, the side face or near the hole. The optical housing according to claim 1,
The optical housing is characterized in that the rib shape forms a part of the air flow path.
An optical housing characterized by that. The optical housing according to claim 1 or 2,
The optical housing is characterized in that the FΘ lens receiving portion has a spherical or conical apex . An optical writing device comprising the optical housing according to claim 1. An image forming apparatus comprising the optical writing device according to claim 4 .

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