JP2005331630A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus with which malfunctions can be diagnosed, by deciding the image defects caused by an intermediate transfer belt from its speed characteristics and frequency characteristics. <P>SOLUTION: The image forming apparatus includes means of detecting and computing the speed change width of the drive roller of the intermediate transfer belt and the peak value of its frequency change; means of detecting and computing the speed change width of a follower roller and the peak value of its frequency change; a comparison means for comparing the speed change widths of the drive roller and follower roller and the peak values of their frequency changes; and a deciding means. When a difference between the peak values of their frequency changes is within a prescribed range and the result of the speed comparison exceeds a prescribed range, the deciding means judges that the abnormal state of the driving part of the drive roller is an accidental one caused by the type of recording paper. When the result of the speed comparison is within the prescribed range and the difference between the peak values of their frequency changes exceeds the prescribed range, the deciding means judges that the abnormal state of the driving part of the drive roller is caused by the malfunction of a driving part unit. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, or a printer, and more particularly to a failure diagnosis technique that can easily determine the cause of image loss or the like in an image forming apparatus using an intermediate transfer belt. .

  2. Description of the Related Art Conventionally, an image forming apparatus having an intermediate transfer belt has been put to practical use as an electrophotographic image forming apparatus that reproduces a document image on a recording medium such as paper. This is because an electrostatic latent image is formed on an image carrier such as a photosensitive drum, and a toner is selectively attached thereto to form a visible image, and then this toner image is once formed endlessly. The image forming apparatus performs primary transfer onto an intermediate transfer belt and then secondary transfer onto a recording medium such as paper to fix it.

  The method in which the toner image is once transferred onto the intermediate transfer belt is advantageous in that a plurality of color toner images are transferred and superimposed to form a composite color image, which can be transferred onto a recording medium in a batch. There is. According to this method, not only the color mixing of the toner stored in the developing device can be prevented, but also an image that can normally occur at the time of multiple transfer to the recording medium without considering the conveyance characteristics of the recording medium with respect to the image carrier. There is also an advantage that it is possible to effectively prevent the occurrence of color distortion and color misregistration.

However, the pressure from the transfer roller acts on the toner layer non-uniformly to cause partial transfer failure (density unevenness), or the image transfer may be lost or the transfer image may be disturbed due to the speed fluctuation of the intermediate transfer belt. There are also problems such as making them appear. In order to avoid these problems, in addition to a method of obtaining a high image quality by incorporating a speed control technique in the drive system of the belt itself to electrically stabilize the speed of the intermediate transfer belt, as shown in Patent Document 1, A method has been proposed in which belt tension is mechanically adjusted by using a separate roller to avoid fluctuations in the speed of the intermediate transfer belt.
JP2000-231277A

  By the way, various causes are conceivable for the speed fluctuation of the intermediate transfer belt which causes the image defect. For example, even if there is a local defect in the drive gear train of the belt, it appears as a periodic speed fluctuation, which causes image disturbance and image loss at the secondary transfer position.

  In recent years, color image forming apparatuses are often put on the POD (print on demand) market, and high image quality and high speed are required. Especially for paper types such as coated paper and printing paper. It has come to be used for a wide variety of things. For this reason, recording paper with different characteristics (such as non-specification thick paper) is inserted, and when the thick paper comes out of the registration roller, an abnormal force is applied to the intermediate transfer belt, and the image is temporarily affected by fluctuations in the transfer belt speed. It may cause defects. For example, in the case of a color machine, registration (color misregistration), in-page variation, and the like occur due to the effect of temporary fluctuations in the transfer belt speed due to the entry of recording paper.

  However, there is no conventional diagnostic technology that distinguishes and detects the temporary speed fluctuation due to the paper type and the speed fluctuation caused by the drive unit defect. It was not possible to automatically determine the type and subsequent response.

  The present invention has been made in view of such circumstances, and provides an image forming apparatus capable of diagnosing a failure by judging image defects caused by speed fluctuations of an intermediate transfer belt from the speed characteristics and frequency characteristics. It is intended to do.

  In order to achieve the above object, an image forming apparatus according to the first invention of the present application is stretched by an image carrier on which a toner image is formed on a surface by at least selectively transferred charged toner, and a plurality of rollers. And a transfer belt that has a peripheral surface that is driven in a circular motion, and a toner image on the image carrier is primarily transferred onto the peripheral surface. The plurality of rollers include a driving roller that drives the transfer belt upstream of the primary transfer position and a driven roller that is downstream of the primary transfer position and is driven according to the movement of the transfer belt. It consists of

  The image forming apparatus includes a first detecting unit that detects a speed fluctuation of the driving roller, a first speed calculating unit that calculates a speed fluctuation range of the driving roller from a speed characteristic detected by the first detecting unit, and a speed fluctuation of the driven roller. The second detection means for detecting the speed, the second speed calculation means for calculating the speed fluctuation width of the driven roller from the speed characteristic detected by the second detection means, the speed fluctuation width of the driving roller and the speed fluctuation width of the driven roller are compared. The speed width comparison means and the speed width comparison means are configured to include a determination means for notifying the abnormality of the drive unit of the drive roller when the comparison result exceeds a predetermined range.

  Similarly, the image forming apparatus according to the second invention of the present application is also driven in a circular manner by being stretched by a plurality of rollers and an image carrier on which a toner image is formed on a surface by at least selectively transferred charged toner. And a transfer belt having a peripheral surface on which a toner image on the image carrier is primarily transferred. The plurality of rollers include a driving roller that drives the transfer belt upstream of the primary transfer position and a driven roller that is downstream of the primary transfer position and is driven according to the movement of the transfer belt. It consists of

  The image forming apparatus includes: a first detection unit that detects a speed variation of the driving roller; a first frequency calculation unit that calculates a peak value of the frequency variation of the driving roller from the speed characteristic detected by the first detection unit; Second detecting means for detecting speed fluctuation, second frequency calculating means for calculating the peak value of frequency fluctuation of the driven roller from the speed characteristic detected by the second detecting means, peak value of frequency fluctuation of the driving roller and driven roller Frequency comparison means for comparing peak values of frequency fluctuations, and determination means for notifying abnormality of the drive section of the drive roller when the comparison result of the frequency comparison means exceeds a predetermined range.

  Similarly, the image forming apparatus according to the third invention of the present application is driven in a circular manner by being stretched by a plurality of rollers and an image carrier on which a toner image is formed on the surface by at least selectively transferred charged toner. And a transfer belt having a peripheral surface on which a toner image on the image carrier is primarily transferred. The plurality of rollers include a driving roller that drives the transfer belt upstream of the primary transfer position and a driven roller that is downstream of the primary transfer position and is driven according to the movement of the transfer belt. It consists of

  In this image forming apparatus, first detection means for detecting speed fluctuation of the driving roller, second detection means for detecting speed fluctuation of the driven roller, first speed calculation means for calculating the speed fluctuation width of the driving roller, First frequency calculating means for calculating the peak value of frequency fluctuation, second speed calculating means for calculating the speed fluctuation width of the driven roller, second frequency calculating means for calculating the peak value of frequency fluctuation of the driven roller, driving roller and driven A speed width comparing means for comparing the speed fluctuation widths of the rollers, a frequency comparing means for comparing peak values of frequency fluctuations of the driving roller and the driven roller, and a judging means are provided.

  When the difference between the peak values of the frequency fluctuations is within a predetermined range and the result of the speed comparison unit exceeds the predetermined range, the determination means detects an abnormality in the driving portion of the drive roller due to the type of recording paper. If the result of the speed comparison means is within a predetermined range and the difference between the peak values of each frequency fluctuation exceeds the predetermined range, the abnormality of the driving unit of the driving roller is It is configured to determine an abnormality based on a failure. According to the above configuration, the following operational effects can be obtained.

  In the image forming apparatus according to the first aspect of the present application, it is detected that the ratio of the speed fluctuation widths of the driving roller and the driven roller temporarily falls outside the predetermined range. This can be empirically determined that some external force other than the rotational driving force of the driving roller is temporarily applied to the driven roller, and it can be determined that the abnormal speed of the transfer belt is due to a sudden cause such as the insertion of cardboard. It becomes possible.

  Further, according to the image forming apparatus of the second invention of the present application, it is detected that there is a difference of a predetermined range or more in the peak value of each frequency fluctuation indicated by the driving roller and the driven roller. This has been empirically established when some abnormality occurs in the drive part of the drive roller, and it is determined that the transfer belt speed abnormality is an abnormality based on the failure of the drive roller drive unit. can do.

  According to the image forming apparatus according to the third invention of the present application, the image forming apparatus according to the first and second inventions includes the detecting means, the calculating means, and the comparing means. Immediately check if the color misalignment or in-page variation in the device is caused by a paper type that is out of specification, such as cardboard, or if there is a local defect in the drive gear train of the drive roller. Therefore, it is possible to reduce unnecessary maintenance and inspection work and waste of paper due to miscopying.

  Hereinafter, an embodiment of the image forming apparatus 100 according to the present invention will be described with reference to FIG. The image forming apparatus 100 is called a tandem color image forming apparatus, and includes an endless belt-like intermediate transfer belt 7 that is stretched by a plurality of roller groups and supported so as to be able to be driven around. Four image forming units 10Y, 10M, 10C, and 10K that form toner images of yellow, magenta, cyan, and black are arranged in tandem along the outer peripheral surface of the intermediate transfer belt 7.

  The image forming units 10Y, 10M, 10C, and 10K have photoreceptors 1Y, 1M, 1C, and 1K (image carriers) on which latent images are formed, respectively, along the outer peripheral surface of each photoreceptor. In order of operation, charging devices 2Y, 2M, 2C, and 2K that charge the surfaces of the photoreceptors 1Y, 1M, 1C, and 1K almost uniformly, and an exposure device 3Y that writes an electrostatic latent image on each photoreceptor surface. , 3M, 3C, 3K, developing devices 4Y, 4M, 4C, 4K that transfer toner to each latent image formed on the surface of the photosensitive member to form a toner image, and transfer the toner image on the surface of the photosensitive member to an intermediate transfer belt 7, primary transfer devices 5Y, 5M, 5C, and 5K for transferring to the image forming apparatus 7 and cleaning devices 6Y, 6M, 6C, and 6K for cleaning the surface of the photoconductor after the transfer are arranged.

  The image reading unit 40 disposed on the upper part of the image forming apparatus 100 includes a scanning unit 41 including a light source and a mirror for illuminating a document, a scanning unit 42 having two roof mirrors, an imaging lens 43, an image sensor 44, and the like. The document placing unit 45 is configured. The image pickup device 44 is mainly composed of a CCD, and image signals collected on the image pickup device 44 (CCD) by scanning the light source of the scanning unit 41 are converted into image data for each color by an image processing unit (not shown). , Sent to the exposure devices 3Y, 3M, 3C, 3K.

  In the exposure apparatuses 3Y, 3M, 3C, and 3K, the semiconductor laser is electrically modulated based on each image data, and sub-scanning is performed by a polyhedral reflector (polygon mirror) and a lens group through a collimator lens. Further, the main scanning is performed by rotating the photoconductors 1Y, 1M, 1C, and 1K, and the electrostatic latent images are reproduced on the photoconductors 1Y, 1M, 1C, and 1K.

  Prior to exposure, a predetermined surface charge is applied to the photoreceptors 1Y, 1M, 1C, and 1K by corona discharge of the charging devices 2Y, 2M, 2C, and 2K. The electric charge is reduced according to the exposure amount, and as a result, electrostatic latent images corresponding to the image information data are formed on the surfaces of the respective photoreceptors 1Y, 1M, 1C, and 1K.

  The electrostatic latent image is visualized with toner of each color developer supplied from the developing devices 4Y, 4M, 4C, and 4K, and becomes a toner image. The developing devices 4Y, 4M, 4C and 4K have openings at portions facing the photoconductors 1Y, 1M, 1C and 1K. The openings are in contact with the photoconductors 1Y, 1M, 1C and 1K. Developing rollers 9Y, 9M, 9C, and 9K are provided for transferring the toner to the photoreceptors 1Y, 1M, 1C, and 1K. The developing devices 4Y, 4M, 4C, and 4K contain toners of the respective colors, and have a plurality of toner supply rollers that contact the developing rollers 9Y, 9M, 9C, and 9K and supply the toner to the rollers. doing.

  The developing devices 4Y, 4M, 4C, and 4K are supported so as to be movable on the guide rails so as to be movable toward and away from the respective photosensitive members 1Y, 1M, 1C, and 1K. , 1M, 1C, and 1K, and the developing rollers 9Y, 9M, 9C, and 9K can come into contact with the photoreceptors 1Y, 1M, 1C, and 1K during development. Thus, the developing rollers 9Y, 9M, 9C, and 9K can develop the electrostatic latent images formed on the surfaces of the photoreceptors 1Y, 1M, 1C, and 1K for each color.

  FIG. 2 is a schematic configuration diagram showing the intermediate transfer belt 7 (transfer belt) and its peripheral mechanisms. 2 and the subsequent drawings, the same reference numerals denote the same parts. The intermediate transfer belt 7 is stretched and driven around a plurality of rollers such as a driving roller 71, a driven roller 72, other tension rollers, and a guide roller. The driving roller 71 is positioned upstream of the photoconductors 1Y, 1M, 1C, and 1K to rotationally drive the intermediate transfer belt 7, and the driven roller 72 is positioned downstream of the photoconductors 1Y, 1M, 1C, and 1K and intermediate. The transfer belt 7 is supported.

  In the image forming units 10Y, 10M, 10C, and 10K of the image forming apparatus 100, the toner images for the respective colors formed on the surfaces of the photoreceptors 1Y, 1M, 1C, and 1K are primarily synchronized with the rotation of the intermediate transfer belt 7. Transfer is performed by the transfer devices 5Y, 5M, 5C, and 5K. That is, the photoreceptors 1Y, 1M, 1C, and 1K are arranged in a column facing the intermediate transfer belt 7 for each circumferential distance, and the toner images for the respective colors are superimposed on the same position on the intermediate transfer belt 7. A color toner image which is transferred and synthesized on the intermediate transfer belt 7 is formed.

  The driven roller 72 is paired with the transfer roller 73 to form a secondary transfer portion 7A. A transfer electric field is applied by niping the intermediate transfer belt 7 and the recording paper P, and the primary transfer is performed on the intermediate transfer belt 7. The color toner image is collectively transferred onto the recording paper P. A registration roller 23 is provided on the upstream side of the secondary transfer portion 7A in the recording paper conveyance path, and a fixing device 8 is provided on the downstream side. The recording paper P is subjected to skew correction and paper feed timing by the registration roller 23 and then sent to the secondary transfer unit 7A. The fixing device 8 heats and melts the color toner image transferred onto the recording paper P. Fix on the recording paper P.

  FIG. 3 is a block diagram showing a structure for diagnosing a drive unit and image defects of the intermediate transfer belt 7 forming the gist of the first invention of the present application. The driving roller 71 that drives the intermediate transfer belt 7 is connected to the driving unit 711 via a plurality of gear trains, and the driving force of the driving unit 711 is transmitted to the driving roller 71. The rotation center axis of the drive roller 71 is provided with an encoder 710 (first detection means) having the same axis, and fluctuations in the rotation speed of the drive roller 71 are detected as wave signals.

  Similarly, an encoder 720 (second detection means) is also provided on the rotation center axis of the driven roller 72, and fluctuations in the rotation speed of the driven roller 72 are also detected independently of the drive roller 71. . An output example of the encoder is shown in FIG. (A) is an output example of the encoder 710, and (b) is an output example of the encoder 720. Note that when the intermediate transfer belt 7 is stretched with a predetermined tension and is driven to rotate in accordance with the drive roller 71, the speed variation ratio between the two should be constant.

The output of the encoder 710 is sent to the first speed calculation means 712, and the maximum speed fluctuation width (V ₁ -V ₂ ) of the drive roller 71 is calculated. The output of the encoder 720 is sent to the second speed calculation means 722 to calculate the maximum speed fluctuation width (V ₄ -V ₅ ) of the driven roller 72. The respective calculation results are compared by the speed width comparing means 74, and the result is judged and displayed by the judging means 75.

An example of the comparison method of the speed width comparison means 74 in the present invention will be described with reference to FIG. In this embodiment, the maximum amplitude (V ₁ -V ₂ ) of the output of the encoder 710 and the maximum amplitude (V ₄ -V ₅ ) of the output of the encoder 720 are calculated and compared, and the ratio between the two is within a predetermined range. Judging whether or not it has been exceeded. That is, if (V ₄ −V ₅ ) / (V ₁ −V ₂ )> K, the determination unit 75 determines that there is an abnormality in the drive unit of the drive roller 71 and displays the result. However, the present invention is not limited to this method, and it is possible to make a judgment based on the difference between the two.

  FIG. 4 is a block diagram showing a drive unit of the intermediate transfer belt 7 forming the gist of the second invention of the present application and a configuration for diagnosing image defects. Since the belt driving mechanism is the same as that of the first invention, the description thereof is omitted, but the outputs of the encoders 710 and 720 are connected to the first frequency calculating means 713 and the second frequency calculating means 723, respectively. Is different.

  In the embodiment shown in FIG. 4, the output of the encoder 710 is sent to the first frequency calculation means 713 to calculate the peak value of the frequency fluctuation of the drive roller 71. Further, the output of the encoder 720 is sent to the second frequency calculating means 723, and the peak value of the frequency fluctuation of the driven roller 72 is calculated. Each calculation result is compared by the frequency comparison means 76, and the result is judged and displayed by the judgment means 77.

An example of the comparison method of the frequency comparison means 76 in the present invention will be described with reference to FIG. FIG. 7 is a spectrum diagram showing an output example of the frequency calculation means. In this embodiment of calculating the peak value f ₁ frequency to the frequency analysis in the first frequency calculating means 713 for output of the encoder 710. Further, the output of the encoder 720 by the frequency analysis in the second frequency calculating means 723 for calculating a peak value f ₂ frequency. Thereafter, the difference between the two is calculated by the frequency comparison means 76, and it is determined whether or not the difference exceeds a predetermined range. That is, the determination unit 77 determines that there is an abnormality in the drive unit of the drive roller 71 if | f ₁ −f ₂ |> M (a constant value), and displays the result. However, the present invention is not limited to this method, and it is possible to make a judgment based on the ratio between the two.

  FIG. 5 is a block diagram showing a configuration for diagnosing a drive portion of the intermediate transfer belt 7 and an image defect forming the gist of the third invention of the present application. Since the belt drive mechanism is the same as that of the first invention and the second invention, the description thereof is omitted, but in this embodiment, the output of the encoder 710 is the first speed calculation means 712 and the first frequency. The difference is that it is connected to both of the calculation means 713 and the output of the encoder 720 is connected to both the second speed calculation means 722 and the second frequency calculation means 723.

In the embodiment shown in FIG. 5, the output of the encoder 710 is conveyed to the first speed calculation means 712 to calculate the maximum speed fluctuation width of the drive roller 71 (maximum amplitude (V ₁ -V ₂ ) in FIG. 6). At the same time, it is conveyed to the first frequency calculating means 713 to calculate the peak value f _{1 of the} frequency. Further, the output of the encoder 720 is conveyed to the second speed calculation means 722 to calculate the maximum speed fluctuation width (maximum amplitude (V ₄ -V _{5 in} FIG. 6) of the drive roller 71 and simultaneously the second frequency calculation means 723. and transported to computing the peak value f ₂ frequency.

  The speed fluctuation widths of the outputs of the encoders 710 and 720 are compared by the speed width comparison means 74 and the result is sent to the determination means 78. The frequency peak values of the outputs of the encoders 710 and 720 are compared by the frequency comparison unit 76, and the comparison result is sent to the determination unit 78.

The determination means 78 in the embodiment of FIG. 5 makes the following determination from both comparison results. That is, the speed fluctuation range indicated by the encoders 710 and 720 is in the relationship of (V ₄ −V ₅ ) / (V ₁ −V ₂ )> K (predetermined value), and the peak value of the fluctuating frequency is in the relationship of f1 = f2. If this is the case, it can be determined from experience that there is no abnormality in the mechanism of the driving unit, and that some external force other than the rotational driving force of the driving roller 71 is temporarily applied to the driven roller 72. As a result, it is determined that the speed abnormality of the transfer belt is due to a sudden cause due to the insertion of cardboard or the like.

On the other hand, the speed fluctuation range indicated by the encoders 710 and 720 has a relationship of (V ₄ −V ₅ ) / (V ₁ −V ₂ ) ≈K (predetermined value), and the peak value of the fluctuating frequency is | f ₁ −f If there is a relationship of ₂ |> M (predetermined value), it can be empirically determined that some abnormality has occurred in the drive unit of the drive roller 71. As a result, it is determined that the speed abnormality of the transfer belt is an abnormality based on the failure of the drive unit of the drive roller. The determination result is displayed on the display unit of the image forming apparatus 100. These criteria are based on empirical rules.

  Hereinafter, the operation of the image forming apparatus 100 including the image defect detection unit according to the present invention will be described. When a document copy command is input, predetermined surface charges are applied to the surfaces of the photoreceptors 1Y, 1M, 1C, and 1K by corona discharge of the charging devices 2Y, 2M, 2C, and 2K. By irradiating the laser beam read by the image reading unit 40 and modulated by the image information data separated for each color, the charge of the exposed portion of each photoconductor is reduced according to the exposure amount. As a result, electrostatic latent images corresponding to the image information data are formed on the respective photoreceptors 1Y, 1M, 1C, and 1K.

  The toner images of the respective colors formed on the photoreceptors 1Y, 1M, 1C, and 1K are intermediately rotated by the primary transfer devices 5Y, 5M, 5C, and 5K if the intermediate transfer belt 7 is controlled to rotate at a constant speed. The images are sequentially transferred to the same position on the transfer belt 7 to form a combined color image. However, when image loss, color misregistration, image unevenness, or the like occurs, the image defect detection means immediately determines and displays whether there is a sudden abnormality due to out-of-specification paper or an abnormality occurring in the drive unit of the intermediate transfer belt 7. . As a result, the necessity of maintenance can be determined, and unnecessary costs can be reduced.

  The toner image formed on the intermediate transfer belt 7 is fixed on the recording paper P by the following process. A plurality of paper trays 20 are provided below the image forming apparatus 100. A movable plate 26 that is lifted upward by lifting means is disposed at the bottom of the plurality of paper trays 20 that accommodate the recording paper P. The movable plate 26 on which the recording paper P is placed receives the paper feed start signal and lifts the recording paper P to the upper limit position limited by the upper limit sensor. At the same time, the pickup roller 21 falls, and the uppermost recording paper P placed thereon is configured to contact the pickup roller 21.

  The recording paper P in contact with the pickup roller 21 is taken out from the paper tray 20 by the contact pressure, separated one by one, and fed. The fed recording paper P is guided to a plurality of intermediate rollers 22A, 22B, 22C, 22D and conveyed to the registration roller 23. The transported recording paper P is fed to the secondary transfer position by the registration roller 23 and fed to the secondary transfer position, and the combined color image on the intermediate transfer belt 7 is collectively transferred onto the recording paper P.

  The recording paper P onto which the color image has been transferred is conveyed to the fixing device 8 while being guided by the conveyance guide plate 27. The color image on the recording paper P is heated and fixed by the fixing device 8. The recording paper P heated for melting the developer image is cooled by a cooling fan (not shown) for fixing the developer image, and is sandwiched between paper discharge rollers 24 and placed on a paper discharge tray 25 outside the apparatus. The

  The image forming apparatus 100 described above shows an optimum embodiment, and the image forming apparatus 100 according to the present invention is not limited to the above embodiment. Of course, various modifications can be made without departing from the scope of the present invention.

1 is an overall configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a schematic configuration diagram illustrating an intermediate transfer belt and its peripheral mechanisms. FIG. 3 is a block diagram showing a configuration for diagnosing an image defect and an intermediate transfer belt driving unit forming the gist of the first invention. FIG. 10 is a block diagram showing a configuration for diagnosing an image defect and a driving portion of an intermediate transfer belt forming the gist of the second invention. FIG. 10 is a block diagram showing a structure for diagnosing an image defect and an intermediate transfer belt driving unit forming the gist of the third invention. It is a wave form diagram which shows the example of an output of an encoder. It is a spectrum figure which shows the example of an output of a frequency calculating means.

Explanation of symbols

1Y, 1M, 1C, 1K Photoconductor 7 Intermediate transfer belt 8 Fixing device 10Y, 10M, 10C, 10K Image forming unit 23 Registration roller 40 Image reading unit 71 Driving roller 72 Driven roller 74 Speed width comparison means 75, 77, 78 Determination Means 76 Frequency comparison means 100 Image forming apparatus 710, 720 Encoder (first and second detection means)
712 First speed calculation means 713 First frequency calculation means 722 Second speed calculation means 723 Second frequency calculation means P Recording paper

Claims (3)

An image carrier on which a toner image is formed on a surface by selectively transferred charged toner, and a circumferential surface that is stretched and driven by a plurality of rollers, and the toner image on the image carrier is An image forming apparatus having a transfer belt primarily transferred onto the peripheral surface;
The plurality of rollers are upstream of the primary transfer position, drive rollers that drive the transfer belt, and downstream of the primary transfer position, and are driven according to the movement of the transfer belt. Have a roller,
First detection means for detecting speed fluctuations of the drive roller;
First speed calculation means for calculating the speed fluctuation width of the drive roller from the speed characteristics detected by the first detection means;
Second detection means for detecting a speed fluctuation of the driven roller;
Second speed calculation means for calculating the speed fluctuation width of the driven roller from the speed characteristics detected by the second detection means;
Speed width comparing means for comparing the speed fluctuation width of the driving roller and the speed fluctuation width of the driven roller;
An image forming apparatus comprising: a determination unit that notifies an abnormality of the drive unit of the drive roller when the result of the speed width comparison unit exceeds a predetermined range. An image carrier on which a toner image is formed on a surface by selectively transferred charged toner, and a circumferential surface that is stretched and driven by a plurality of rollers, and the toner image on the image carrier is An image forming apparatus having a transfer belt primarily transferred onto the peripheral surface;
The plurality of rollers are upstream of the primary transfer position, drive rollers that drive the transfer belt, and downstream of the primary transfer position, and are driven according to the movement of the transfer belt. Have a roller,
First detection means for detecting speed fluctuations of the drive roller;
First frequency calculation means for calculating a peak value of frequency fluctuations of the drive roller from the speed characteristics detected by the first detection means;
Second detection means for detecting a speed fluctuation of the driven roller;
Second frequency calculation means for calculating the peak value of the frequency fluctuation of the driven roller from the speed characteristic detected by the second detection means;
Frequency comparison means for comparing the peak value of the frequency fluctuation of the driving roller and the peak value of the frequency fluctuation of the driven roller;
An image forming apparatus comprising: a determination unit that notifies an abnormality of the driving unit of the driving roller when a difference between peak values of the frequency fluctuations exceeds a predetermined range. First frequency calculation means for calculating a peak value of the frequency fluctuation of the drive roller from the speed characteristic detected by the first detection means;
Second frequency calculation means for calculating the peak value of the frequency fluctuation of the driven roller from the speed characteristic detected by the second detection means;
The image forming apparatus according to claim 1, further comprising: a frequency comparison unit that compares a peak value of the frequency fluctuation of the driving roller with a peak value of the frequency fluctuation of the driven roller.
The determination means for notifying the abnormality of the drive section of the drive roller has a difference between the peak values of the frequency fluctuations within a predetermined range, and if the result of the speed width comparison means exceeds the predetermined range, When it is determined that the abnormality is a sudden abnormality due to the type, the result of the speed width comparison means is within a predetermined range, and if the difference between the peak values of the frequency fluctuations exceeds a predetermined range, the drive unit unit may fail. An image forming apparatus that determines an abnormality based on the image forming apparatus.

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