JP4241136B2 - Image forming apparatus provided with encoder and method for assembling encoder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic image forming apparatus including an encoder used for a copying machine, a printer, a FAX, and the like, and an encoder assembling method.
[0002]
[Prior art]
Conventionally, an encoder has been used for driving measurement of a photosensitive member and an intermediate transfer member of an electrophotographic image forming apparatus such as a copying machine, a printer, and a FAX, in order to obtain a good image in the image forming apparatus. An encoder rotation control method (for example, refer to Patent Document 1) for realizing stable rotation of the photosensitive member, and a control method (for example, a high-quality image can be obtained with a simple configuration even if the photosensitive member speed fluctuates). Patent Document 2), and a method for ensuring mounting strength and sufficient position detection accuracy and simplifying the encoder mounting structure (see, for example, Patent Document 3) are disclosed. .
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-110347
[Patent Document 2]
Japanese Patent Laid-Open No. 11-34388
[Patent Document 3]
JP-A-7-260516 [0006]
[Problems to be solved by the invention]
However, in the assembly of such an encoder, the alignment adjustment in the gap between the sensor unit and the wheel unit and the complicated assembly lead to an increase in manufacturing cost. Alternatively, there is an example in which a positioning housing is provided in order to simplify the assembly, but the shape of the parts is complicated, and precision machining for positioning is difficult, leading to an increase in cost.
[0007]
The present invention solves the above problems, and provides an assembly method of an encoder that is inexpensive and does not require alignment adjustment in a gap, and an image forming apparatus including an encoder using the assembly method. The purpose is to do.
[0008]
[Means for Solving the Problems]
The above object is achieved by the following configurations.
[0009]
(1) In an image forming apparatus including an encoder that measures an angular velocity of a rotating body, the encoder includes a wheel section that rotates integrally with the rotating body, and a sensor section that measures a rotation angle across the wheel section. The sensor part is fixed to the positioning member in advance, and the positioning member integral with the sensor part is inserted from the radial direction of the central axis of the rotating body, and the outer ring of the bearing member that supports the central axis at the end of the positioning member And an image forming apparatus (first invention) including an encoder that regulates a positional relationship between the sensor unit and the wheel unit.
[0010]
(2) In an image forming apparatus including an encoder that measures an angular velocity of a rotating body, the encoder includes a wheel unit that rotates integrally with the rotating body, and a sensor unit that measures a rotation angle across the wheel unit, The sensor part is fixed to the positioning member in advance, and the positioning member integral with the sensor part is inserted from the radial direction of the central axis of the rotating body, and the outer ring of the bearing member that supports the central axis at the end of the positioning member A method of assembling the encoder (second invention), wherein the positional relationship between the sensor portion and the wheel portion is regulated.
(3) In an image forming apparatus including an encoder that measures an angular velocity of a rotating body, the encoder includes a wheel portion that rotates integrally with the rotating body and a sensor portion that measures a rotation angle of the wheel portion, and the sensor And a positioning member that is positioned by being abutted against an outer ring of a bearing member that supports the central portion of the rotating body, and the sensor unit is provided with a groove part into which the wheel part is inserted, and the wheel part Is an image forming apparatus (third invention) comprising an encoder, which is inserted so as not to contact the sensor part in the groove part .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. The description in this column does not limit the technical scope of the claims or the meaning of terms. In addition, the following assertive description in the embodiment of the present invention shows the best mode, and does not limit the meaning or technical scope of the terms of the present invention.
[0012]
An image forming process, each mechanism, and an assembling method of the encoder according to an embodiment of an image forming apparatus including an encoder according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view of a digital multifunction machine using an electrophotographic system showing an embodiment of an image recording apparatus provided with an encoder according to the present invention, and FIG. 2 is provided on the rotating body of FIG. FIG. 3 is a schematic sectional side view of the encoder, FIG. 3 is a sectional view taken along the line AA in FIG. 2 showing the encoder positioning method, and FIG. 4 is a rear view of the cover covering the encoder. FIG. 5 is a diagram showing the structure of the sensor section of the encoder. Note that the image forming apparatus of the present embodiment can record images on both sides of the transfer material, but the present invention is not limited to such a configuration.
[0013]
1 to 5, the image recording apparatus shown in FIG. 1 is an image recording apparatus having a composite function using a digital method, and an automatic document feeder ADF is provided on the upper part of the apparatus body, and image reading is performed. The image forming apparatus includes a section A, an image processing section B (not shown), an image forming section C, and a transfer material feeding section D.
[0014]
The automatic document feeder ADF is a device that is provided in the upper part of the apparatus main body, sends out the documents one by one, conveys them to the image reading position of the document, and discharges the document after the image reading.
[0015]
The image reading unit A is a unit that reads an image of a document and obtains image data, and is provided in the upper part of the apparatus main body.
[0016]
The image forming unit C forms an image on a transfer material conveyed at a predetermined process speed based on the image data obtained by the image reading unit A. The image forming unit C of the present embodiment forms an image using an electrophotographic process.
[0017]
In the image forming unit C, a charging unit 11 as a charging unit, a developing unit 13 as a developing unit, a transfer unit 14a as a transferring unit, and a separating unit are provided on the outer periphery of a photosensitive drum 10 as an image forming unit as an image forming unit. A separator 14b and a cleaning device 18 as a cleaning means are arranged in the order of operation. The photoconductor drum 10 is formed by coating a photoconductive compound on a drum base. For example, an organic photoconductor (OPC) is used, and the photoconductor drum 10 is driven and rotated in the clockwise direction shown in the drawing.
[0018]
The rotating photosensitive drum 10 is uniformly charged by the charger 11, and then the exposure optical system 12 performs image exposure (image writing) based on an image signal called from the memory of the image processing unit B. . The exposure optical system 12, which is an image writing means using a laser writing system, uses a laser diode (not shown) as a light emitting light source, a laser beam is modulated based on image information, and rotates, a polygon mirror 12a, an fθ lens (no symbol) The optical path is bent by a reflection mirror 12b through a cylindrical lens (not shown), and main scanning is performed. Image exposure (image writing) is performed at a predetermined position on the photosensitive drum 10, and the photosensitive drum 10 A latent image is formed by rotation (sub-scanning). In this embodiment, the character portion is exposed to form a reverse latent image.
[0019]
The reverse latent image on the photosensitive drum 10 is reversely developed by the developing unit 13, and a visible image is formed as a toner image on the photosensitive layer surface of the photosensitive drum 10.
[0020]
In the transfer material feeding unit D, paper feed units 4A, 4B, and 4C having paper feed cassettes 41a to 41c, which are transfer material storage means for storing recording paper P of different sizes, are provided below the image forming unit. Then, the recording paper P is sent out from any of the paper feed cassettes 41a to 41c by the feed rollers 42a to 42c and the separating rollers 43a to 43c, and passes through the intermediate transport rollers 44a to 44c and the guide roller 45, and is on the inlet side of the transport unit 40. To the registration roller 46.
[0021]
The recording paper P fed by each of the above methods is temporarily stopped by correcting the inclination and bias of the transfer material by the registration roller 46, and then synchronized with the toner image on the photosensitive drum 10 to obtain the registration roller. The paper is fed again from 46 and conveyed to the transfer area of the transfer device 14a via the pre-transfer roller 47.
[0022]
In the transfer area, the toner image on the photosensitive drum 10 is transferred onto the recording paper P by the transfer device 14a, and then is neutralized by the separator 14b and separated from the surface of the photosensitive drum 10, and is transferred to the fixing device 17 by the conveying belt 14c. Be transported.
[0023]
The fixing device 17 includes a fixing roller 17a and a pressure roller 17b. By passing the recording paper P between the fixing roller 17a and the pressure roller 17b, the toner image is recorded on the recording paper by heating and pressing. Melted and fixed on P.
[0024]
The transfer residual toner remaining on the peripheral surface of the photosensitive drum 10 after the transfer is cleaned by a cleaning device 18 which is a cleaning unit.
[0025]
After the fixing of the toner image on one side, the recording paper P is discharged in the state of a double-sided image or a single-sided image that forms a toner image on the other side according to the mode selection for double-sided image formation or single-sided image formation described below. It is discharged onto the tray 19.
[0026]
When the double-sided image forming mode is selected on the display panel (not shown), the recording paper P that has been subjected to the above-described surface image fixing is the reverse conveyance path 50 having the reverse switching member 52, the switchback path 50a, and the second reverse. The ADU mechanism composed of the conveyance path 50b descends along the reverse conveyance path 50, is once loaded into the switchback path 50a, and then unloaded to reverse the front and back surfaces. Then, the recording paper P is re-feeded along the conveying unit 40 by the guide roller 45 described above, and the recording paper P is temporarily stopped by the registration roller 46 that corrects the inclination and bias of the sheet material, and then is re-feeded. Then, the toner image of the back surface image formed again on the photosensitive drum 10 is transferred to the back surface of the recording paper P in the transfer area of the transfer device 14a, and then separated and conveyed to be fixed and discharged. It is discharged onto a tray 19.
[0027]
When the single-sided image forming mode is selected on the display panel, the recording paper P on which the front surface image has been fixed advances straight as it is and is discharged onto the paper discharge tray 19, or the upper and lower surfaces are reversed by the reverse switching member 52. Are discharged onto the paper discharge tray 19.
[0028]
Note that, in the above, image formation in which the toner image formed on the image forming body is transferred to a belt-like intermediate transfer body (intermediate transfer belt), and then the toner image on the intermediate transfer belt is retransferred to a transfer material. It is good also as a part.
[0029]
In the image forming apparatus, an image forming member or a belt-like intermediate transfer member is used as a rotating member. As shown in the figure, an encoder 2 (see FIG. 2) for measuring the angular velocity of the rotating body is provided at the rotational center of the photosensitive drum 10 as the rotating body, as will be described later.
[0030]
In FIG. 2, the encoder 2 includes an encoder wheel 21 that is a wheel portion that rotates integrally with the photosensitive drum 10 as a rotating body, a hollow shaft 23 to which the encoder wheel 21 is fixed by, for example, an adhesive, An angular velocity detection sensor 22 that is a sensor unit that measures a rotation angle with the encoder wheel 21 interposed therebetween, a positioning member 24 to which the angular velocity detection sensor 22 is attached, and the like.
[0031]
The encoder wheel 21 is made of a stainless steel plate having a thickness of about 0.5 mm and an outer diameter of about 42 mm, and approximately 600 radial slit holes 211 having a width of 0.1 mm are provided at equal intervals in the vicinity of the outer peripheral surface. It is a thing.
[0032]
The angular velocity detection sensor 2 2, groove width cross section of U-shaped for the encoder wheel 21 is inserted is about 1.7 mm (gap) W is provided, as shown in FIG. 5, for example, a light-emitting diode A light-receiving device 28 comprising a light-receiving device 281 and a condensing lens 282 is disposed opposite to a light-emitting device 27 comprising a light-emitting device 271 and a projection lens 272, and a slit hole 211 of the encoder wheel 21 is used. From the pulse value of the current detected by the light receiving element 281 by the light emitting device 27 and the light receiving device 28 that are activated when the light passes, the rotating body to be used (the photosensitive drum 10 in the present embodiment) is used. Measure angular velocity.
[0033]
In FIG. 3, the angular velocity detection sensor 22 has a positioning boss 221 for positioning the angular velocity detection sensor 22, and is fixed to the positioning member 24 with a screw 222 according to the groove 241 of the positioning member 24.
[0034]
Returning to FIG. 2, the positioning member 24 has a shape portion that is an arc-shaped end portion 242 (see FIG. 3) having the same curvature as an outer ring 313 of the bearing 31 described later, and the arc-shaped end portion 242 is In a state where the outer ring 313 is abutted against the outer ring 313, a bolt is placed at a predetermined position of the body drive unit frame 60 attached to a frame (not shown) of the image forming apparatus book, with a spacer 314 having the same thickness as the collar Tb. 26 is fixed in place.
[0035]
The bearing 31 as a bearing member inserted into the central shaft 30 is on one side, the inner ring 312 is an E-ring 311 fitted into the central shaft 30, and the outer ring 313 is provided on the same surface as the surface of the E-ring 311. The bearing holder 312 is fixed to the drive unit frame 60 by, for example, screwing. On the other side, the inner ring 312 is abutted and held by the hollow shaft 23 fixed to the central shaft 30 with a set screw 231. When the bearing 31 is fitted into the drive unit frame 60, the outer ring 313 abuts the flange Tb against the drive unit frame 60, and a disc-shaped spacer 314 having the same thickness as the flange Tb is provided on the outer periphery of the flange Tb. The positioning member 24 is held on the outer ring 313 by being abutted against the arc-shaped end portion 242 of the positioning member 24 and fixing the positioning member 24 to the drive unit frame 50 with the bolts 26 with the flange Tb interposed therebetween.
[0036]
The central shaft 30 is supported by a bearing 33 that is fitted in a cover 32 that covers the encoder 2. Although there is a support member for supporting the central shaft 30 (not shown) on the loading side S of the photosensitive drum 10, it is removed when the photosensitive drum is replaced, but the central shaft 33 has the bearing 33. It is supported stably.
[0037]
In attaching the angular velocity detection sensor 22 to the positioning member 24, as described above, the positioning boss 221 (see FIG. 3) provided in the angular velocity detection sensor 22 is provided with the guide groove 241 provided in the positioning member 24 (see FIG. 3). engages the, for example, be positioned by a screw 222, the angular velocity detection sensor 22, through the oval holes 223 of the left and right, fixed to the positioning member 24 in the shown to screws 22 2 in FIG. That is, the angular velocity detecting sensor 22 is previously fixed to the positioning member 24.
[0038]
2 and 3, as shown in FIGS. 2 and 3, the angle detection sensor 22 fixed to the positioning member 24 in advance is attached to the central shaft 30 as indicated by the arrow V. The encoder wheel 21 is slid along the surface of the spacer 314 from the radial direction through the notch 36 of the cover 32 and inserted so that the encoder wheel 21 is sandwiched in the U-shaped gap W of the angle detection sensor 22. The arc-shaped end portion 242 is abutted against the outer ring 313 (other than the flange portion Tb) of the bearing 31, the positioning member 24 is aligned with a predetermined position of the drive unit frame 60, and the attachment / removal hole 35 provided in the cover 32. Then, the positioning member 24 is fixed to the drive unit frame 60 with bolts 26 using a box driver or the like.
[0039]
The distance L from the surface of the positioning member 24 to the encoder wheel 21 is easily set with an accuracy such that the encoder wheel does not contact the angular velocity detection sensor 22 in the narrow groove portion of the gap W.
[0040]
Accordingly, when the angle detection sensor 22 is assembled, the arc-shaped end portion 242 of the positioning member 24 is abutted against the outer ring of the bearing 31 so as to be aligned with a predetermined positioning hole, and adjustment with the gap W is not necessary. Assembling is possible only by stopping, and when the sensor part is replaced due to a failure or the like, the time spent for assembly and adjustment can be greatly reduced.
[0041]
When the distance L between the positioning member 24 of the angular velocity detection sensor 22 which is a sensor portion of the encoder 2 and the encoder wheel 21 is 5 mm ± 0.2 mm, the encoder wheel 21 having a thickness of about 0.5 mm is the angular velocity detection sensor 22 described above. Can be easily inserted without contacting the angular velocity detection sensor 22 in a narrow groove having a width W of about 1.7 mm.
[0042]
In FIG. 2 to FIG. 4, the angular velocity detection sensors 22 are provided one by one at the positions facing each other, but are arranged for correcting eccentricity of the rotating body, and the structure and assembling method are as follows. The same as described above.
[0043]
【The invention's effect】
According to claim 1, 2, 5, it is unnecessary to align adjustment in the gap with an inexpensive configuration, and easily provide an image forming apparatus including an encoder to be assembled is enabled.
[0044]
According to the third or fourth aspect, it is possible to provide an encoder assembling method that is inexpensive and does not require alignment adjustment in the gap and can be easily assembled.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a digital multi-function peripheral using an electrophotographic system showing an embodiment of an image recording apparatus provided with an encoder.
FIG. 2 is a side sectional view of a schematic configuration of an encoder provided in the rotating body of FIG. 1;
3 is a cross-sectional view taken along arrow AA in FIG. 2 showing a method for positioning the encoder.
FIG. 4 is a rear view of a cover that covers the encoder.
FIG. 5 is a diagram illustrating a structure of a sensor unit of an encoder.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Photosensitive drum 12 Exposure optical system 2 Encoder 21 Encoder wheel 22 Angular velocity detection sensor 23 Hollow shaft 24 Positioning member 30 Center shaft 31 Bearing 313 Outer ring 312 Inner ring 60 Drive part frame

Claims (5)

  In an image forming apparatus including an encoder that measures an angular velocity of a rotating body, the encoder includes a wheel unit that rotates integrally with the rotating body, and a sensor unit that measures a rotation angle across the wheel unit. The positioning member that is fixed to the positioning member in advance and that is integral with the sensor unit from the radial direction of the central axis of the rotating body is inserted, and the end of the positioning member is abutted against the outer ring of the bearing member that supports the central axis An image forming apparatus comprising an encoder that regulates a positional relationship between the sensor unit and the wheel unit.   The image forming apparatus including the encoder according to claim 1, wherein a hole for attaching or removing the positioning member is provided in a cover that covers the encoder.   In an image forming apparatus including an encoder that measures an angular velocity of a rotating body, the encoder includes a wheel unit that rotates integrally with the rotating body, and a sensor unit that measures a rotation angle across the wheel unit. The positioning member that is fixed to the positioning member in advance and that is integral with the sensor unit from the radial direction of the central axis of the rotating body is inserted, and the end of the positioning member is abutted against the outer ring of the bearing member that supports the central axis A method for assembling an encoder, wherein the positional relationship between the sensor unit and the wheel unit is regulated.   The method for assembling an encoder according to claim 3, wherein a hole for attaching or removing the positioning member is provided in a cover covering the encoder. In an image forming apparatus including an encoder that measures an angular velocity of a rotating body, the encoder includes a wheel unit that rotates integrally with the rotating body and a sensor unit that measures a rotation angle of the wheel unit, and the sensor unit is fixed. And a positioning member that is positioned by being abutted against an outer ring of a bearing member that supports the central portion of the rotating body,
An image forming apparatus including an encoder , wherein the sensor unit includes a groove part into which a wheel part is inserted, and the wheel part is inserted in the groove part so as not to contact the sensor part .

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