JP2007264310A - Rotating body driving apparatus and image forming apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotating body driving apparatus that supplies the rotational force of a rotational driving source to a rotating body through a gear, in which fluctuation in rotational speed due to a gear tooth pitch error can be corrected. <P>SOLUTION: A motor 31 is rotated at fixed speed, and the angular data and pitch data of the tooth from the gear 32 located in the HP (home position) are stored in a memory 45. In correction of the rotational speed, the rotational speed of the motor 31 is adjusted by reading the angular data and the pitch data of the tooth out of the memory 45, and then adjusting the output pulse of a rotational driving apparatus pulse generation part 44 so as to eliminate a difference from an ideal value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a rotating body driving device that rotationally drives a rotating body by supplying a rotating force of a rotating drive source to the rotating body via a gear, and more specifically, a gear tooth pitch error. The present invention relates to a technique for correcting the speed fluctuation of a rotating body generated by the above.

  For example, in an electrophotographic image forming apparatus in which a toner image is formed on the surface of a photosensitive drum and transferred onto a recording sheet to form an image, the toner image formed on the surface of the photosensitive drum is faithfully recorded. In order to transfer onto the sheet, it is necessary to accurately match the peripheral speed of the photosensitive drum and the conveyance speed of the recording sheet.

  When the photosensitive drum is rotationally driven by, for example, a DC motor, the motor is usually rotated at a relatively high speed for the purpose of stabilizing the rotational speed and ensuring the driving torque, and this rotational speed is reduced to a gear type speed reducer. The photosensitive drum is driven by being decelerated by a decelerating means such as. However, in this case, even if the motor that is the rotational drive source is rotated at a stable speed, the photosensitive force is caused by processing accuracy errors (cumulative pitch error, eccentricity of the rotating shaft, etc.) of the rotational force transmission mechanism including the gears. Periodic fluctuations occur in the rotational speed of the body drum, and the reproduced image may be deteriorated.

  Therefore, as shown in FIG. 13, when the photosensitive drum 101 is assembled by fixing the flange portion 137 to which the gear 137a is integrally attached to the cylindrical portion 136 of the photosensitive drum 101, as shown in FIG. The rotational speed fluctuation (rotational unevenness) of the cylindrical portion 136 of the photosensitive drum 101 and the rotational speed fluctuation of the flange portion 137 of the photosensitive drum 101 are measured in advance and stored in the memory so that their phases match. An image forming apparatus that has been assembled has been proposed (see Patent Document 1).

  In this image forming apparatus, the speed fluctuation of the photosensitive drum 101 is corrected by applying a known speed fluctuation correction technique to the photosensitive drum 101 assembled as described above. That is, the motor is rotated at a constant speed in advance, and the rotational force is supplied to the photosensitive drum 101 via the rotational force transmission mechanism, and the cyclic fluctuation component of the rotational speed of the photosensitive drum 101 is measured and stored in the memory. When the image is formed, the periodic fluctuation component is read from the memory, and the speed of the photosensitive drum 101 is corrected as shown in FIG. 15 by correcting the reverse phase speed so as to cancel the periodic fluctuation component. Fluctuation is reduced.

  However, there is a problem that correction of the tooth pitch unit cannot be performed for the rotational speed fluctuation caused by the tooth tooth pitch error of the rotational force transmission mechanism.

JP 2000-330448 A

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a pitch error of gear teeth in a rotating body drive device in which the rotational force of a rotational drive source is supplied to the rotating body by a gear. It is possible to correct the tooth pitch unit with respect to the rotational speed fluctuation caused by.

According to a first aspect of the present invention, there is provided a rotational drive source, a circumferential reference position identifying member, a gear that can be attached to and detached from the rotational drive source, and the identification member of the gear that is rotated by the rotational drive source. Rotation comprising: a reference position detecting means for detecting the circumferential reference position by detection; and a circumferential position detecting means for detecting a circumferential position of the tooth with respect to the circumferential reference position. It is a body drive device.
According to a second aspect of the present invention, there is provided the rotating body drive device according to the first aspect, further comprising means for calculating a pitch of the teeth based on a difference between detected values of circumferential positions of adjacent teeth. .
According to a third aspect of the present invention, in the rotating body drive device according to the first or second aspect, a storage medium for storing data indicating a circumferential position or pitch of the teeth is provided.
According to a fourth aspect of the present invention, in the rotating body drive device according to the third aspect, the storage medium is provided in the gear.
According to a fifth aspect of the present invention, in the rotating body drive device according to any one of the first to fourth aspects, error calculation means for calculating an error in the circumferential position or pitch of the teeth, and the rotation so as to cancel the error Rotational speed control means for correcting the rotational speed of the drive source is provided.
According to a sixth aspect of the present invention, in the rotating body drive device according to the fifth aspect, the rotational speed control means generates rotational speed correction data for each of a plurality of teeth.
According to a seventh aspect of the present invention, in the rotating body drive device according to any of the first to sixth aspects, the gear includes a plurality of gears engaged with each other.
According to an eighth aspect of the present invention, there is provided a photosensitive drum driven by the rotating body driving device according to any one of the first to seventh aspects.

(Function)
According to the first aspect of the present invention, the circumferential reference position of the gear is detected by detecting the identification member provided on the gear rotated by the rotational drive source, and the circumferential direction of the tooth with respect to the circumferential reference position Detect position.
According to the invention of claim 2, the tooth pitch is calculated based on the difference between the detected values of the circumferential positions of the adjacent teeth of the gear.
According to the invention of claim 3, data indicating the circumferential position or pitch of the gear teeth is stored in the storage medium.
According to the invention of claim 4, data indicating the circumferential position or pitch of the gear teeth is stored in the storage medium provided in the gear.
According to the invention of claim 5, the error in the circumferential position or pitch of the gear teeth is calculated, and the rotational speed of the rotary drive source is corrected so as to cancel the error.
According to the sixth aspect of the present invention, correction data for canceling an error in the circumferential position or pitch of the teeth is generated for each of the plurality of teeth of the gear.
According to the invention of claim 7, the circumferential position or pitch of each tooth of the plurality of gears engaged with each other is calculated, their error is calculated, and the rotational speed of the rotary drive source is adjusted so as to cancel the error. Control.

  According to the present invention, in the rotating body drive device that supplies the rotational force of the rotation drive source to the rotating body via the gear, the tooth pitch unit is used for the rotational speed fluctuation caused by the gear tooth pitch error. Can be corrected.

Embodiments of the present invention will be described below with reference to the drawings.
First, an image forming apparatus to which the present invention is applied will be described. As shown in FIG. 1, this image forming apparatus is a color copying machine having four image forming sections of cyan (C), yellow (Y), magenta (M), and black (K), and is exposed. The scanner unit 2 that photoelectrically converts the reflected light from the copied original and processes the image data of the read original image, and the laser light from the laser light source that is modulated by the image data and controlled to emit light, A writing unit 2 that irradiates the photosensitive surface, and a photosensitive drum 1 on which the photosensitive surface is irradiated with laser light from the writing unit 2 and an electrostatic latent image is formed.

  Around the photosensitive drum 1, the charging unit 4 that uniformly charges the photosensitive surface, the developing unit 5 that attaches toner to the photosensitive drum 1 on which the latent image is formed, and the photosensitive drum 1 are attached. And a transfer unit 6 for transferring the toner image onto the transfer paper (performed via an intermediate transfer belt). Since the tandem method is used here, the development and image formation around the photosensitive drum 1 can be performed independently for each color component of cyan (C), yellow (Y), magenta (M), and black (K). In addition, each color component is combined in the transfer process.

  Further, the main body unit 7 and the paper supply bank 8 are provided with a paper feed tray, and a manual paper feed tray 9 is provided on the main body unit. Further, the image forming apparatus includes a belt fixing unit 11, a fixing roller 12, and a pressure roller 13 that apply temperature and pressure to the image-formed transfer paper and fuse the toner onto the paper.

FIG. 2 shows a main configuration of the image forming engine in FIG.
Around the photosensitive drums 1C, 1Y, 1M, and 1K, charging units 4C, 4Y, 4M, and 4K, developing units 5C, 5Y, 5M, and 5K, and cleaning units 15C, 15Y, 15M, and 15K (photosensitive members), respectively. And image forming units 21C, 21Y, 21M, and 21K, which clean the untransferred toner on the drum). Here, the image forming units 21C, 21Y, 21M, and 21K are configured as a process cartridge that integrally includes the photosensitive drum 1C, the charging unit 4C, the developing unit 5K, and the cleaning unit 15K, and are detachably attached to the apparatus main body. Has been.

  In addition, the toner image formed on each photosensitive drum is temporarily transferred (primary transfer) to the intermediate transfer belt 19, and then the image on the intermediate transfer belt 19 is further transferred (secondary transfer) to the transfer paper twice. The image is formed on the transfer paper by the transfer. Further, since image formation is performed by one sheet passing, the intermediate transfer belt 19 passes through the photosensitive drums 1C, 1Y, 1M, and 1K arranged at predetermined intervals from the upstream side to the downstream side of the moving intermediate transfer belt 19. The image transferred above is superimposed on the belt, formed as a color image, and then transferred to transfer paper. That is, the toner images on the photosensitive drums 1C, 1Y, 1M, and 1K formed by the image forming units for four colors are sequentially applied onto the intermediate transfer belt 19 by the primary transfer rollers 16C, 16Y, 16M, and 16K. Primary transfer is performed. Further, the color-combined toner image on the intermediate transfer belt 19 that has been primarily transferred is secondarily transferred onto a transfer sheet by a secondary transfer roller 17 and a secondary transfer opposing roller 18 facing the secondary transfer roller 17. The toner remaining as untransferred toner on the intermediate transfer belt 19 is removed by the belt cleaning unit 20.

  Next, rotation drive control of the photosensitive drums 1C, 1M, 1Y, and 1K will be described. In the color image forming apparatus shown in FIG. 1, a DC brushless motor is used as a motor for driving the photosensitive drums 1C, 1M, 1Y, and 1K for each color, and the rotation of the motor is reduced by a reduction means such as a gear type reduction gear. To the photosensitive drum 1. When driving each photosensitive drum 1C, 1M, 1Y, and 1K with such a motor, even if the motor that is the driving source is rotated at a stable speed, the processing accuracy error of the rotational force transmission mechanism including the gear ( Due to gear tooth cumulative pitch error, rotational shaft eccentricity, etc., the rotational speed of the photosensitive drum may periodically vary, and the reproduced image may be deteriorated.

[First Embodiment]
Therefore, in the first embodiment of the present invention, the rotation of the photosensitive drum as the rotating body is rotated by the rotating body driving device shown in FIG. 3 to reduce periodic fluctuations in the rotational speed of the photosensitive drum.

  This rotating body drive device includes a motor 31, a gear 32 that is detachably connected to the motor 31, and has a circumferential direction reference position (home position: hereinafter referred to as HP) identification member 41 on the surface, and a gear 32. A sensor 33 for detecting the peripheral edge of the tooth to be driven, a drive circuit control unit 34 for outputting a pulse for rotating the motor 31 at a predetermined speed, together with an output signal of the sensor 33, and a drive circuit control unit And a rotation drive device (driver) 35 for supplying a drive current to the motor 31 based on 34 output pulses.

  As shown in FIG. 4, the identification member 41 is attached to one surface of a tooth constituting the gear 32 and is made of a material having a reflectance different from that of the tooth surface. The sensor 33 is composed of a light emitting element and a light receiving element arranged side by side on the one side of the gear 32. The light emitted from the light emitting element is reflected from the identification member 41 and reflected light from portions other than the identification member 41. The identification member 41 is detected based on the difference in the level of the received light signal. In addition, when the sensor 33 is facing between the teeth of the gear 32, the light emitted from the light emitting element is not reflected on the surface of the gear 32, so the reflected light is not detected by the light receiving element. When the sensor 33 faces the surface of the gear 32, the light emitted from the light emitting element is reflected by the surface of the gear 32, so that the reflected light is detected by the light receiving element. Therefore, it is possible to detect both edges of the teeth in the circumferential direction of the tooth based on the presence or absence of the detection signal of the light receiving element. Of course, this is only an example, and it goes without saying that other detection means such as a transmissive photoelectric sensor may be used.

The drive circuit control unit 34 includes a position detection circuit 42, an arithmetic processing unit 43, a rotation drive device pulse generation unit 44, and a memory 45. The position detection circuit 42 takes in an analog output signal of the sensor 33 and detects both edges of the gear 32 in the circumferential direction of the gear 32 and the HP of the gear 32. The arithmetic processing unit 43 sets the middle of both edges in the circumferential direction of each tooth as the circumferential position of the tooth, and the angle from the HP to the circumferential position of each tooth (θ ₁ , θ ₂ , θ ₃ ,... Θ _n ) Is calculated. The output signal of the position detection circuit 42 and the calculated value of the arithmetic processing unit 43 are stored in the memory 45. The memory 45 stores in advance ideal values of angles from HP to various teeth of various gears including the gear 31. The rotation drive device pulse generator 44 detects the HP of the gear 32 and both edges of the gear 32 in the circumferential direction of the gear 32 based on the signal of the sensor 33, and rotates the motor 32 at a constant speed. When a pulse is generated to correct the rotational speed fluctuation of the photosensitive drum 1, a pulse for rotating the motor 32 is generated so as to cancel the manufacturing error in the circumferential position of the tooth of the gear 32.

The operation of the rotating body drive device having the above configuration will be described.
First, the procedure for writing the tooth data for one rotation of the gear 32 in the memory 45 will be described with reference to the flowchart of FIG. Here, the motor 31 itself is configured not to be eccentric, and the gear 32 is attached to the rotation shaft thereof. The gear 32 can be detached from the motor 31 and attached to another motor after acquisition of data for one round is completed.

  As described above, the constant speed operation of the motor 31 to which the gear 32 is attached is started (step S1). When it is detected that the motor 31 has rotated at a constant speed (YES in step S2), the HP of the gear 32 is detected. Start (step S3). Here, it is determined based on a rotation detection signal (not shown) of the motor 31 that the motor 31 has rotated at a constant speed.

If HP is detected (YES in step S4), until the next HP is detected (YES in step S6), that is, until the gear 32 rotates once, both ends in the circumferential direction of the teeth of the gear 32 from the HP are moved. Detect and write to memory 45 (step S7). The memory 45, calculated in the arithmetic processing unit 43, an angle from HP until the tooth _{(θ 1, θ 2, θ} 3, ··· θ n) is also written. In this way, tooth data for one rotation of the gear 32 is stored in the memory 45 in association with the identification data of the gear 32. The identification data of the gear 32 may be input by a user from an operation panel (not shown), or may be recorded as a barcode on the surface of the gear 32 and read by a barcode reader.

Next, the procedure for correcting the rotational speed fluctuation caused by the tooth pitch error of the gear 32 will be described with reference to the flowchart shown in FIG.
First, gear identification data is read from the memory 45 (step S11), and it is determined whether there is one gear (step S12). If there is one, the angle data from the gear tooth HP and the ideal value of the tooth angle are read from the memory 45 and the calculation processing unit 43 calculates the variation that is the difference between them. (Step S13), a correction value corresponding to it is calculated and determined (Step S14). Next, the motor 31 is rotated (step S15). If the gear HP is detected (YES in step S16), then the gear HP is detected (YES in step S18). Using the correction value, the period of the pulse generated by the rotational drive pulse generator 44 is adjusted so as to cancel out the difference from the ideal value (step S17).

  As a result of this adjustment, the period is finely adjusted so as to cancel the difference from the ideal value of the gear tooth angle as shown in FIG. 7B with respect to the state where the motor 31 rotates at a constant period as shown in FIG. 7A. The fine adjustment data is stored in the memory 45 (step S19), read out, and used for fine adjustment after the second round of the gear (step S20). As a result, it is not necessary to create a correction value for each rotation of the gear, so the number of steps in the control program can be reduced.

  When the number of gears is not one (NO in step 12), that is, for example, when two gears 32a and 32b are provided as shown in FIG. 8, the variation of the tooth angle of each gear is calculated. (Step S21), then, the sum is calculated (Step S22), and the correction value is determined according to the sum (Step S23). Here, when calculating the sum, it is added while identifying the tooth number of each gear from the HP. The processing after determining the correction value is the same as that when there is one gear (steps S15 to S20).

  As described above, according to the image forming apparatus to which the present embodiment is applied, the angle of the tooth from the HP of the gear 31 that transmits the rotational force of the motor 31 to the photosensitive drum 1 is calculated, and the difference from the ideal value is calculated. Since the rotational speed of the motor 31 is adjusted so as to eliminate the above-mentioned, the speed fluctuation of the photosensitive drum 1 due to the pitch error of the gear 31 can be corrected. Thereby, the photosensitive drums 1C, 1Y, 1M, and 1K for the respective colors can be rotated at a constant speed, so that color misregistration can be reduced. Further, by applying the rotating body driving device of the present embodiment to the motor that drives the intermediate transfer belt 19 of the image forming apparatus, image expansion and contraction and color misregistration can be reduced. Furthermore, by applying it to a motor that drives the opposing roller 18 of the secondary transfer unit, the expansion and contraction of the image can be reduced.

  The tooth pitch is obtained by calculating the angle difference from the HP of adjacent teeth, stored in the memory 45, and the tooth pitch fluctuation (difference from the ideal pitch value) is calculated during correction. However, the correction value may be determined according to the variation. Further, the variation of the tooth angle or the variation of the pitch may be stored in the memory 45 before correction. Furthermore, the correction of the rotation speed may be performed not for each tooth (every pitch) but for every two or more constant teeth (every pitch), and the control interval may be widened. As the correction value in this case, for example, an average value of correction values of a plurality of teeth is used.

[Second Embodiment]
FIG. 9 is a block diagram showing the configuration of the rotating body drive device according to the second embodiment of the present invention. In this figure, the same or corresponding components as those in FIG. 3 are denoted by the reference numerals used in FIG.

  The rotating body drive device according to the present embodiment is such that the gear 32 includes the IC tag 46 and that the IC tag reader can read and write tooth angle data and pitch data from the HP of the gear 32. The difference from the first embodiment is that the / writer 47 is provided. In this IC tag 46, identification data of the gear 32 is written in advance. When the gear 32 includes two gears, each of the two gears 32a and 32b has IC tags 46a and 46b as shown in FIG.

  The operation of the rotating body drive device of the present embodiment having the above configuration will be described using the flowcharts shown in FIGS. Here, FIG. 11 is a procedure for writing the data for one rotation of the gear 32 in the memory 45 and the IC tag 46, and FIG. 12 is a procedure for correcting the rotational speed fluctuation caused by the tooth pitch error. In FIG. 11 and FIG. 12, the same steps as those in FIG. 5 and FIG. 6 are given the reference numerals (step numbers) used in FIG. 5 and FIG.

  As shown in FIG. 11, the procedure for writing the data for one revolution of the gear 32 to the memory 45 and the IC tag 46 is the same as that shown in FIG. 5 until the data for one revolution of the gear 32 is written to the memory 45 (step S7). This is the same, and in the present embodiment, a process of writing data for one round of teeth to the IC tag 46 provided on the gear 32 by the IC tag reader / writer 47 is added next.

  As shown in FIG. 12, in the procedure for correcting the rotational speed fluctuation caused by the tooth pitch error of the gear 32, the correction data for one rotation of the gear 32 is provided for the gear 32 with respect to the procedure of the first embodiment shown in FIG. A process of writing to 32 IC tags 46 (step S24) is added. Here, the identification data reading process of the gear 32 (step S11) and the tooth angle data reading process of the gear 32 (step S12) may be performed from the IC tag 46 instead of from the memory 45. Good.

  As described above, according to the present embodiment, the tooth angle data, pitch data, and correction data are stored in the gear 32 itself. Therefore, once these data are stored, the rotating body driving device shown in FIG. When the gear 32 is removed from the motor and used as a gear of another rotating body drive device, the process of acquiring and storing the data again is not necessary. The data may be stored in the gear 32 in the form of a barcode.

1 is a diagram illustrating a configuration of an image forming apparatus to which the present invention is applied. FIG. 2 is a diagram illustrating a configuration of a process cartridge in an image forming apparatus to which the present invention is applied. It is a figure which shows the structure of the rotary body drive device of the 1st Embodiment of this invention. It is a figure which shows the structure of the gearwheel in the 1st Embodiment of this invention. It is a figure which shows the procedure which writes the data of the tooth | gear for one round of a gearwheel in the memory in the 1st Embodiment of this invention. It is a figure which shows the procedure which correct | amends the rotational speed fluctuation | variation resulting from the pitch error of the gear tooth in the 1st Embodiment of this invention. It is a figure which shows the rotational speed of the motor before and behind correction | amendment of the rotational speed of the rotary body in the 1st Embodiment of this invention. It is a figure which shows the structure in the case of having two gearwheels in the 1st Embodiment of this invention. It is a figure which shows the structure of the 2nd rotary body drive device of this invention. In the 2nd Embodiment of this invention, it is a figure which shows a structure in case it has two gearwheels. It is a figure which shows the procedure which writes the data of the tooth | gear for one round of a gear in a memory and an IC tag in the 2nd Embodiment of this invention. It is a figure which shows the procedure which correct | amends the rotational speed fluctuation | variation resulting from the gear tooth pitch error in the 2nd Embodiment of this invention. It is a figure which shows the structure of the photosensitive drum of the conventional image forming apparatus. It is a figure which shows the rotational speed fluctuation | variation of the flange part and cylindrical part of the conventional photoconductor drum. It is a figure which shows the correction | amendment principle of the periodic fluctuation | variation of the rotational speed of the conventional rotary body drive device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 31 ... Motor, 32 ... Gear, 33 ... Sensor, 34 ... Drive circuit control part, 41 ... Identification member, 42 ... Position detection circuit, 43... Arithmetic processing unit, 44... Rotary drive device pulse generation unit, 46... IC tag, 47... IC tag reader / writer.

Claims (8)

  By detecting a rotational drive source, a circumferential reference position identification member, a gear that can be attached to and detached from the rotational drive source, and the identification member of the gear that is rotated by the rotational drive source, A rotating body drive device comprising: reference position detection means for detecting a direction reference position; and circumferential position detection means for detecting a circumferential position of the teeth with respect to the circumferential reference position. The rotating body drive device according to claim 1,
A rotating body drive device comprising means for calculating a pitch of the teeth based on a difference between detected values of circumferential positions of adjacent teeth. In the rotating body drive device according to claim 1 or 2,
A rotating body drive device comprising a storage medium for storing data indicating a circumferential position or pitch of the teeth. In the rotating body drive device according to claim 3,
The rotating body drive device, wherein the storage medium is provided in the gear. In the rotary body drive device in any one of Claims 1-4,
A rotating body drive comprising: an error calculating means for calculating an error in the circumferential position or pitch of the teeth; and a rotational speed control means for correcting the rotational speed of the rotational drive source so as to cancel the error. apparatus. In the rotating body drive device according to claim 5,
The rotational speed control means generates rotational speed correction data for each of a plurality of teeth. In the rotary body drive device in any one of Claims 1-6,
The rotating body drive device according to claim 1, wherein the gear includes a plurality of gears engaged with each other.   An image forming apparatus comprising a photosensitive drum driven by the rotating body driving device according to claim 1.

Images