JP2013049532A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct rotation timing of a pickup roller so that the recording sheet interval is constant.SOLUTION: This image forming apparatus comprises: a sheet feed cassette 45 storing recording sheets P; a pickup roller 46 rotated at a predetermined time interval to take and feed the recording sheet P stored in the sheet feed cassette 45 one by one; a sheet feed sensor 49 detecting the recording sheet P conveyed from the sheet feed cassette 45 by the pickup roller 46; and an arithmetic control part 6 for rotating the pickup roller 46 at the predetermined time interval. The arithmetic control part 6 measures the time from when the pickup roller 46 is rotated for each recording sheet P to when the recording sheet P is detected by the sheet feed sensor 49, calculates a difference value between the measurement value and a center value, and corrects the rotation timing of the pickup roller 46 so that the recording sheet interval is constant on the basis of the average value of the difference values.

Description

  The present invention relates to an image forming apparatus.

  In the image forming apparatus, when the recording paper is continuously fed from the paper feeding cassette, the recording paper is fed at a time interval to ensure an interval from the preceding recording paper. However, it is very difficult to maintain a constant interval between recording sheets in the paper supply due to the influence of humidity and the like. For example, when the humidity decreases, the amount of moisture contained in the recording paper decreases, so that the recording paper and the pick-up roller become slippery, so that the recording paper interval is widened. When the recording paper interval is widened, the amount of recording paper transported per hour is reduced, which causes a reduction in image forming efficiency. In order to solve such a problem, Patent Document 1 below discloses an image forming apparatus that corrects the timing of feeding recording paper based on the detection result of a humidity sensor.

JP-A-8-262822

  By the way, in the above prior art, the timing of feeding the recording paper is corrected based on the detection result of the humidity sensor to cope with the widening of the recording paper interval. It is not possible to cope with a wide interval of recording paper due to aging. That is, the above-described conventional technology cannot cope with the widening of the recording paper interval that occurs when the recording paper and the pickup roller become slippery due to the type of the recording paper and wear of the pickup roller surface over time. For this reason, the conventional technique has a problem in that when the recording paper interval is widened due to factors other than humidity, it is impossible to prevent the reduction in image forming efficiency by suppressing the widening of the recording paper interval.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to prevent a decrease in image formation efficiency by keeping the recording paper interval constant regardless of the type of factors that increase the recording paper interval.

  In order to achieve the above object, according to the present invention, as a first solution means, a recording paper storing means for storing recording paper and a recording paper stored in the recording paper storing means by rotating at a predetermined time interval are provided. An image comprising a pickup roller that picks up and feeds out one sheet at a time, a paper feed sensor that detects recording paper conveyed by the pickup roller, and a control means that rotates the pickup roller at predetermined time intervals so that the recording paper interval is constant. In the forming apparatus, the control unit measures the time from when the pickup roller is rotated for each recording sheet to when the recording sheet is detected by the paper feed sensor, and calculates a deviation value between the measurement value and the reference value. Then, a means for correcting the rotation timing of the pickup roller so as to make the recording paper interval constant based on the average value of the deviation values is adopted. To.

  In the present invention, as the second solving means, in the first solving means, the control means calculates an average value by excluding a deviation value in which a difference between the measured value and the reference value is negative. adopt.

  In the present invention, as the third solving means, in the first or second solving means, the control means adopts a means for calculating an average value by excluding a deviation value exceeding a predetermined upper limit value.

  In the present invention, as the fourth solving means, in any one of the first to third solving means, the control means adopts a means that the arithmetic mean, geometric mean or harmonic mean is calculated as an average value. To do.

  According to the present invention, the time from when the pickup roller is rotated for each recording sheet to when the recording sheet is detected by the paper feed sensor is measured, and the deviation value between the measurement value and the reference value is calculated, Based on the average deviation value, the rotation timing of the pickup roller is corrected so that the recording sheet interval is constant. That is, according to the present invention, the rotation of the pickup roller based on the deviation value between the time from the rotation of the pickup roller until the recording paper is detected by the paper feed sensor and the reference value, that is, the delay time of conveyance of the recording paper. Correct the timing.

  As described above, according to the present invention, the rotation timing of the pickup roller is corrected based on the recording paper conveyance delay time caused by factors such as the type of recording paper other than humidity and the secular change of the pickup roller. Regardless of the type, the recording paper interval can be kept constant. Therefore, according to the present invention, it is possible to keep the recording sheet interval constant, and thus it is possible to prevent a decrease in image forming efficiency.

1 is a diagram illustrating a schematic configuration of a multifunction peripheral A according to an embodiment of the present invention. 6 is a flowchart showing a characteristic operation of the multifunction peripheral A according to an embodiment of the present invention. It is a figure which shows distribution of the deviation value in one Embodiment of this invention. It is a figure which shows the timing which correct | amends the rotation of the pick-up roller 46 in one Embodiment of this invention, and the total range of the data used as the basis of correction | amendment.

Embodiments of the present invention will be described below with reference to the drawings.
The multifunction peripheral A according to the present embodiment is an image forming apparatus that forms an image based on an electrophotographic method. As illustrated in FIG. 1, an operation display unit 1, an image reading unit 2, an image data storage unit 3, an image A forming unit 4, a communication unit 5, and an arithmetic control unit 6 are provided.

  The operation display unit 1 includes operation keys and a touch panel, and functions as a man-machine interface that associates the user with the multifunction peripheral A. The operation display unit 1 outputs a user operation instruction for an operation key or an operation button displayed on the touch panel to the calculation control unit 6 as an operation signal, and various operations are performed on the touch panel based on a control signal input from the calculation control unit 6. Display information of.

  The image reading unit 2 is a surface image of a document automatically fed by an ADF (Automatic document feeder) or a document placed on a platen glass based on a control signal input from the arithmetic control unit 6. The (original image) is read by the line sensor and converted into original image data, and the original image data is output to the image data storage unit 3.

  The image data storage unit 3 is a semiconductor memory, a hard disk device, or the like. Based on a control signal input from the arithmetic control unit 6, original image data, print image data and communication received by the communication unit 5 from an external client computer The unit 5 stores facsimile image data received from an external facsimile machine, reads out the image data based on a control signal input from the arithmetic control unit 6, and outputs it to the image forming unit 4.

  The image forming unit 4 forms a toner image based on the image data read from the image data storage unit 3 on the recording paper P based on a control signal input from the arithmetic control unit 6. As shown in FIG. 1, the image forming unit 4 includes a belt roller 41, an intermediate transfer belt 42, and four image forming units 43Y, 43M, and 43C corresponding to toner colors (Y, M, C, and K). , 43K, primary transfer rollers 44Y, 44M, 44C, 44K, paper feed cassette 45, pickup roller 46, transport roller 47, retard roller 48, paper feed sensor 49, registration roller 50, secondary transfer roller 51, fixing roller 52 A paper discharge roller 53 and a paper discharge tray 54 are provided. The paper feed cassette 45 is a recording paper storage unit in the present embodiment.

  As shown in the figure, the belt roller 41 includes three rollers that are spaced apart from each other, that is, a driving roller 41a, a driven roller 41b, and a tension roller 41c. That is, the driving roller 41a and the driven roller 41b are arranged at a certain distance in the horizontal direction, and the tension roller 41c is arranged at a position slightly displaced upward between the driving roller 41a and the driven roller 41b. ing. The intermediate transfer belt 42 is an endless belt stretched around such a belt roller 41 (drive roller 41a, driven roller 41b, tension roller 41c), and travels in a direction indicated by an arrow by the drive roller 41a.

  That is, the intermediate transfer belt 42 runs in the horizontal direction between the driving roller 41a and the driven roller 41b. The driving roller 41a described above is a roller in which a motor that generates a driving force is axially coupled, and causes the intermediate transfer belt 42 to travel in the direction of the arrow by the power of the motor. The driven roller 41b is a free roller provided so as to freely rotate, and guides the intermediate transfer belt 42 according to the power of the drive roller 41a. Further, the tension roller 41c is a roller that is provided with a rotating shaft so as to be movable, and applies a certain tension (tension) to the intermediate transfer belt 42 by pressing the intermediate transfer belt 42 with a predetermined adjusting force.

  As shown in the figure, the image forming units 43Y, 43M, 43C, and 43K are provided at predetermined intervals in the horizontal running portion of the intermediate transfer belt 42 described above. Of these image forming units 43Y, 43M, 43C, and 43K, the image forming unit 43Y is a unit that forms a yellow (Y) toner image, and is provided at a position closest to the driven roller 41b. The image forming unit 43M is a unit for forming a magenta (M) toner image, and is provided at a position near the driven roller 41b next to the image forming unit 43Y. The image forming unit 43C is a unit that forms a cyan (C) toner image, and is provided at a position close to the driven roller 41b next to the image forming unit 43M. The image forming unit 43K is a unit that forms a black (K) toner image, and is provided at a position closest to the drive roller 41a.

  The image forming units 43Y, 43M, 43C, and 43K include a photosensitive drum 43a, a charging unit 43b, a laser scanning unit 43c, a developing unit 43d, and a cleaner 43e as illustrated in the drawing. Note that the image forming units 43Y, 43M, 43C, and 43K differ only in the color of the toner image, and the constituent elements are the same.

  The photosensitive drum 43a is a cylindrical member having a peripheral surface formed of a predetermined photosensitive material (for example, amorphous silicon). The charging unit 43b uniformly charges the peripheral surface (photosensitive surface) of the photosensitive drum 43a. The laser scanning unit 43c forms an electrostatic latent image on the photosensitive surface by irradiating the charged photosensitive surface with laser light. The developing unit 43d develops the electrostatic latent image formed on the photosensitive surface as a toner image by supplying toner to the photosensitive surface. The cleaner 43e scrapes and removes the toner (residual toner) remaining on the photosensitive surface after the toner image is transferred.

  As shown in the figure, four primary transfer rollers 44Y, 44M, 44C, and 44K are provided corresponding to the image forming units 43Y, 43M, 43C, and 43K, and each of the primary transfer rollers 44Y, 44M, 44C, and 44K has an intermediate transfer belt 42 interposed therebetween. The image forming units 43Y, 43M, 43C, and 43K are disposed to face the photosensitive drum 43a. Further, a primary transfer bias (high voltage) is applied to each primary transfer roller 44Y, 44M, 44C, 44K, and each primary transfer roller 44Y, 44M, 44C, 44K has this primary transfer bias. The toner images of the respective colors respectively formed on the photosensitive drums 43a of the image forming units 43Y, 43M, 43C, and 43K by the action are transferred (primary transfer) to the intermediate transfer belt 42.

  The paper feed cassette 45 is a container for storing a plurality of recording papers P having a predetermined shape such as A4 size and B5 size. The pickup roller 46 is provided in pressure contact with the recording paper P in the upper part of the paper feed cassette 45 and rotates at a predetermined time interval based on a rotation control signal input from the arithmetic control unit 6 to thereby feed the paper feed cassette. 45 is a roller that takes out the recording paper P in the sheet 45 one by one and sends it to the conveyance roller 47. The transport roller 47 is a roller that transports the recording paper P fed from the pickup roller 46 toward the registration roller 50. The retard roller 48 is arranged so as to face the lower side of the transport roller 47, and rotates in a direction opposite to the transport direction of the recording paper P, whereby a plurality of recording papers P which are transported in an overlapping manner by the pickup roller 46. It is a roller to separate.

  For example, when two overlapping recording papers P are transported to the transport roller 47 by the pickup roller 46, one of the recording papers P in contact with the transport roller 47 is transported toward the registration roller 50 and is fed to the retard roller 48. The other recording paper P in contact with the recording paper P is pushed back by the retard roller 48 so as to be separated from the transport roller 47. Then, after one recording sheet P is separated from the transport roller 47, the other recording sheet P with the leading end protruding from the paper feed cassette 45 is transported by the pickup roller 46, thereby continuing to the one recording sheet P. The other recording paper P comes into contact with the transport roller 47 and is transported toward the registration roller 50 by the transport roller 47.

  The paper feed sensor 49 is an optical sensor that detects the recording paper P transported from the paper feed cassette 45 to the transport roller 47 by the pickup roller 46, and is provided between the transport roller 47 and the registration roller 50. When the leading edge of the recording paper P that has passed through is detected, a paper detection signal is output to the arithmetic control unit 6. The registration roller 50 is a roller that supplies the recording paper P supplied from the transport roller 47 to the secondary transfer roller 51 at a predetermined timing. The secondary transfer roller 51 is a roller disposed opposite to the driving roller 41a with the intermediate transfer belt 42 interposed therebetween, and transfers the toner image on the intermediate transfer belt 42 to the recording paper P (secondary transfer). A secondary transfer bias (high voltage) is applied to the secondary transfer roller 51, and the secondary transfer roller 51 applies the toner image on the intermediate transfer belt 42 to the recording paper P by the action of the secondary transfer bias. (Secondary transfer).

  The fixing roller 52 includes a heating roller 52a provided with a heater therein, and a pressure roller 52b that presses the heating roller 52a. The fixing roller 52 heats and presses the recording paper P by sandwiching the recording paper P on which the toner image of each color is transferred by the heating roller 52a and the pressure roller 52b, and the toner image of each color is placed on the recording paper P. To settle. The paper discharge roller 53 is a roller that conveys the recording paper P supplied from the fixing roller 52 toward the paper discharge tray 54. The paper discharge tray 54 is a storage unit that stores and holds the recording paper P supplied from the paper discharge roller 53.

  The communication unit 5 communicates with an external multifunction peripheral or facsimile apparatus via a telephone line on the basis of a control signal input from the arithmetic control unit 6, and with a client computer or the like via a LAN (Local Area Network). It communicates. That is, the communication unit 5 has a communication function compliant with a facsimile standard such as G3 and a communication function compliant with a LAN standard such as Ethernet (registered trademark).

  The arithmetic control unit 6 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an interface circuit that transmits / receives various signals to / from each electrically connected unit. . The arithmetic control unit 6 performs various arithmetic processes based on the control program stored in the ROM and controls the overall operation of the multifunction peripheral A by communicating with each unit.

  As will be described in detail later, the arithmetic control unit 6 performs a correction process for the recording paper interval in image formation as part of the various arithmetic processes. That is, the arithmetic control unit 6 measures the time from when the pickup roller 46 is rotated to when the recording paper P is detected by the paper feed sensor 49, and the deviation value between the measured value and the center value (reference value). The rotation timing of the pickup roller 46 is corrected so that the recording paper interval is constant based on the average value of the deviation values. Note that such an arithmetic control unit 6 is a control unit in the present embodiment.

Next, the operation of the MFP A configured as described above will be described.
First, the overall operation of the multifunction machine A will be described. For example, when the user sets a document on the ADF and operates the operation display unit 1 to instruct copy (copy) of the document, an instruction signal related to the instruction is input from the operation display unit 1 to the arithmetic control unit 6. As a result, the arithmetic control unit 6 causes the image reading unit 2 to sequentially read the document image for each page of the document and stores the document image data of the document image in the image data storage unit 3. Then, the arithmetic control unit 6 generates bitmap image data corresponding to each toner color based on the document image data, and performs image forming processing of the document image on the image forming unit 4 based on the bitmap image data. Let it run.

  In other words, the arithmetic control unit 6 drives the pickup roller 46 to take out the recording paper P in the paper feed cassette 45 one by one and sends it to the transport roller 47 and drives the transport roller 47 to register the recording paper P. It is conveyed toward the roller 50. The arithmetic control unit 6 drives the driving roller 41a to bring the intermediate transfer belt 42 into a running state and drives the image forming units 43Y, 43M, 43C, and 43K, based on the above-described bitmap image data. Thus, the toner images of the respective colors are formed on the photosensitive surface (circumferential surface) of each photosensitive drum 43a. The arithmetic control unit 6 applies the primary transfer bias to the primary transfer rollers 44Y, 44M, 44C, and 44K, thereby causing the toner images on the photosensitive drums 43a to be primarily transferred onto the intermediate transfer belt 42. .

  The arithmetic control unit 6 drives the registration roller 50 in accordance with the image formation processing timing of each color in the image forming units 43Y, 43M, 43C, and 43K, and applies the secondary transfer bias to the secondary transfer roller 51. As a result, the toner image (original image) on the intermediate transfer belt 42 is secondarily transferred to a desired position on the recording paper P. The arithmetic control unit 6 drives the fixing roller 52 and the paper discharge roller 53 to fix the toner image on the recording paper P and discharge it to the paper discharge tray 54.

  Here, the arithmetic control unit 6 performs the following characteristic processing when the image forming unit 4 performs the image forming process. That is, the arithmetic control unit 6 outputs a rotation control signal to the pickup roller 46 at a predetermined time interval so that the interval of the recording paper P becomes constant during paper feeding. Then, as shown in the flowchart of FIG. 2, the arithmetic control unit 6 measures the time from when the recording roller P is detected by the paper feed sensor 49 after the pickup roller 46 is rotated for each recording paper P. (Step S1). That is, the arithmetic control unit 6 measures the time from when the rotation control signal instructing rotation is output to the pickup roller 46 to when the paper detection signal is input by the paper feed sensor 49.

  Then, the arithmetic control unit 6 calculates a deviation value (difference) between the measured value and the center value in step S1 and stores the deviation value in the internal RAM (step S2). It is determined whether or not the process has been executed for the number of recording sheets P (step S3). The center value is a standard value related to the time from the rotation of the pickup roller 46 until the recording paper P is detected by the paper feed sensor 49, and is stored in the arithmetic control unit 6 at the time of manufacturing the multifunction peripheral A.

  If the arithmetic control unit 6 determines that the processes in steps S1 and S2 have not been executed for a predetermined number of sheets (in the case of NO), it repeats the processes in steps S1 and S2. That is, the arithmetic control unit 6 executes the process in step S1 and the process in step S2 on a predetermined number of recording sheets P, for example, the first to 200th recording sheets P.

  On the other hand, when it is determined that the processes of steps S1 and S2 have been executed for a predetermined number of sheets (in the case of YES), the arithmetic control unit 6 determines the measured value and the center value from the deviation values calculated in step S2. A deviation value that is a negative difference and a deviation value that exceeds a predetermined upper limit value are excluded (step S4), and an average value of the deviation values for a predetermined number of recording sheets P is calculated (step S5).

  For example, when the distribution of the deviation values is the result shown in FIGS. 3A and 3B, the range surrounded by the dotted line in FIG. 3B is a deviation in which the difference between the measured value and the center value is negative. The value is shown. That is, the time from the rotation of the pickup roller 46 until the recording paper P is detected by the paper feed sensor 49 is a deviation value that is shorter than the center value.

  This occurs when a plurality of overlapping recording sheets P are conveyed by the pickup roller 46, and the like. That is, when two overlapping recording papers P are transported to the transport roller 47 by the pickup roller 46, one recording paper P in contact with the transport roller 47 is transported toward the registration roller 50 and is fed to the retard roller 48. The other recording paper P in contact with the recording paper P is pushed back by the retard roller 48 so as to be separated from the transport roller 47. Then, after the one recording sheet P is separated from the transport roller 47, the other recording sheet P in which the leading end protrudes from the sheet feeding cassette 45 is transported by the pickup roller 46 in the next sheet feeding process. The other recording paper P is in contact with the conveyance roller 47 following the recording paper P, and is conveyed toward the registration roller 50 by the conveyance roller 47. In this case, the time from when the pickup roller 46 rotates to convey the other recording paper P until the other recording paper P is detected by the paper feed sensor 49 is shorter than usual. The deviation value between the measured value and the center value is negative.

  Further, the range surrounded by the alternate long and short dash line in FIG. 3B depends on factors such as the deviation value used for calculating the average value in step S5, that is, the humidity, the type of the recording paper P, the secular change of the pickup roller 46, and the like. The deviation value when the interval between the recording sheets is widened is shown. The deviation value exceeding this range, that is, the deviation value on the right side of the range of the one-dot chain line in FIG. 3B (for example, the deviation value of the two-dot chain line range) is an average value as the deviation value exceeding the predetermined upper limit value in step S4. Is excluded from the calculation of. For example, when the conveyance of the recording paper P is significantly delayed due to JAM (recording paper jam) or the like, a deviation value exceeding the upper limit value is generated. The negative deviation value and the deviation value exceeding the upper limit value are excluded in step S4 when a plurality of recording papers P are transported in an overlapping manner or when the transportation of the recording papers P is delayed due to JAM or the like. This is because the average value is calculated only when the recording paper P is delayed due to factors such as humidity, the type of the recording paper P, and the secular change of the pickup roller 46.

  Subsequently, after the processing in step S5, the arithmetic control unit 6 corrects the set value indicating the rotation timing of the pickup roller 46 so that the recording paper interval is constant based on the average value of the deviation values (step S6). . Then, the arithmetic control unit 6 rotates the pickup roller 46 based on the set value. For example, when the average value exceeds the center value, that is, when the conveyance of the recording paper P is delayed, the arithmetic control unit 6 causes the rotation timing of the pickup roller 46 to be advanced by the difference between the average value and the center value. Correct the set value. Thereby, since the rotation timing of the pickup roller 46 is advanced, it is possible to correct the delay of the conveyance of the recording paper P, that is, the spread of the recording paper interval. However, a fixed upper limit is set for the correction amount in step S6. This is to prevent the recording sheets P from approaching each other even when a plurality of overlapping recording sheets P are conveyed by the pickup roller 46.

  In this way, by calculating the average value of the deviation values for a predetermined number of recording sheets P and correcting the rotation timing of the pickup roller 46 based on the average value, the recording sheet interval is corrected at the timing shown in FIG. 4, for example. Is done. That is, after the 200 sheets, 1200 sheets, and 2200 sheets of recording paper P are conveyed, the rotation timing of the pickup roller 46 is corrected. For example, when correction is performed after the 200th recording sheet P is conveyed, an average value of the deviation values from the first sheet to the 200th sheet is calculated, and correction is performed based on the average value. When correction is performed after the 1200th recording sheet P is conveyed, an average value of deviation values from the 201st sheet to the 1200th sheet is calculated, and correction is performed based on the average value. When correction is performed after the 2200th recording sheet P is conveyed, an average value of the deviation values for the 1201st to 2200th recording sheets P is calculated, and correction is performed based on the average value. That is, the arithmetic control unit 6 corrects the rotation timing of the pickup roller 46 based on the average value calculated from the above deviation value for the most recent predetermined number of recording sheets P.

 According to the present embodiment, the time from when the pickup roller 46 is rotated for each sheet of recording paper P until the recording paper P is detected by the paper feed sensor 49 is measured, and the measured value and the center are measured. A deviation value from the value is calculated, and the rotation timing of the pickup roller 46 is corrected so that the recording paper interval is constant based on the average value of the deviation values. In other words, according to the present embodiment, based on the deviation value between the time from the rotation of the pickup roller 46 until the recording paper P is detected by the paper feed sensor 49 and the center value, that is, the delay time of conveyance of the recording paper P. Then, the rotation timing of the pickup roller 46 is corrected.

  As described above, according to the present embodiment, the rotation timing of the pickup roller 46 is determined based on the delay time of the conveyance of the recording sheet P caused by factors such as the type of the recording sheet P other than humidity and the secular change of the pickup roller 46. Since the correction is performed, the recording sheet interval can be kept constant regardless of the type of factor. Therefore, according to the present embodiment, since the recording paper interval can be kept constant, it is possible to prevent a decrease in image forming efficiency.

 In addition, according to the present embodiment, the rotation timing of the pickup roller 46 is corrected based on the average value calculated from the above-mentioned deviation value with respect to the most recent predetermined number of recording papers P. can do. For example, the average value of the shift values from the first sheet to the 2200th sheet is less affected by the latest humidity change than the average value of the shift values from the 1201st sheet to the 2200th sheet. In other words, since the average value of the deviation values collected over a long period of time is less affected by the latest humidity change, it is difficult to appropriately cope with the latest humidity change by correction using the average value. However, according to the present embodiment, since the rotation timing of the pickup roller 46 is corrected based on the average value of the deviation values for the most recent predetermined number of sheets, even when the humidity changes suddenly, the change is accommodated. Thus, the recording paper interval can be corrected.

  Further, according to the present embodiment, the average value is calculated by excluding the deviation value in which the difference between the measured value and the center value is negative and the deviation value exceeding the upper limit value, and the pickup roller 46 is based on the average body. Since the rotation timing is corrected, the humidity, the type of recording paper, and the age of the pickup roller 46 are excluded except when a plurality of overlapping recording papers P are transported or when the transport of the recording paper P is delayed by JAM. The recording paper interval can be corrected with respect to the conveyance delay of the recording paper P caused by the change or the like, that is, the widening of the recording paper interval.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the above embodiment, correction is performed at the timing when 200 sheets, 1200 sheets, and 2200 sheets of recording paper P are conveyed, that is, correction is performed at regular intervals, but the present invention is not limited to this.
For example, the rotation timing of the pickup roller 46 may be corrected when a sudden environmental change occurs, that is, when the deviation value changes abruptly. In other words, the arithmetic control unit 6 monitors the rate of change of the deviation value, and when the rate of deviation value deviation exceeds a predetermined threshold, the pickup roller is based on the average value of the deviation values for the most recent predetermined number of sheets. The rotation timing of 46 may be corrected.

(2) In the above embodiment, the recording paper interval when the recording paper P accommodated in the paper feed cassette 45 is conveyed by the pickup roller 46 is made constant, but the present invention is not limited to this. For example, when a manual paper feed tray is provided, the interval between the recording papers when transporting the recording paper P accommodated on the paper feed tray may be made constant.

(3) In the above embodiment, the time from when the pickup roller 46 is rotated for each sheet of the recording paper P until the recording paper P is detected by the paper feed sensor 49 is measured, and the deviation value of the measured value is calculated. The rotation timing of the pickup roller 46 is corrected based on the average value of the deviation values, but the present invention is not limited to this. For example, the arithmetic control unit 6 measures the time for every several sheets (for example, every 10 sheets) instead of every sheet of the recording paper P, calculates a deviation value of the measurement values, and averages the deviation values. The rotation timing of the pickup roller 46 may be corrected based on the above.

(4) Although the said embodiment calculated the arithmetic mean of the deviation value as an average value, this invention is not limited to this. For example, a geometric average or a harmonic average of deviation values may be used as the average value.

DESCRIPTION OF SYMBOLS A ... MFP, 1 ... Operation display part, 2 ... Image reading part, 3 ... Image data storage part, 4 ... Image formation part, 5 ... Communication part, 6 ... Calculation control part (control means), 41 ... Belt roller, 42 ... Intermediate transfer belt, 43Y, 43M, 43C, 43K ... Image forming unit, 44Y, 44M, 44C, 44K ... Primary transfer roller, 45 ... Paper feed cassette, 46 ... Pickup roller, 47 ... Conveyance roller, 48 ... Retard Roller, 49 ... Paper feed sensor, 50 ... Registration roller, 51 ... Secondary transfer roller, 52 ... Fixing roller, 53 ... Paper discharge roller, 54 ... Paper discharge tray, 41a ... Drive roller, 41b ... Drive roller, 41c ... Tension Roller, 43a ... photosensitive drum, 43b ... charge unit, 43c ... laser scanning unit, 43d ... developing unit, 43e ... clear Trainer, 52a ... heating roller, 52 b ... pressing roller, P ... paper

Claims (4)

A recording paper storing means for storing the recording paper; a pickup roller for taking out and feeding the recording paper stored in the recording paper storing means one by one by rotating at a predetermined time interval; and the recording paper storing means by the pickup roller An image forming apparatus comprising: a paper feed sensor that detects the recording paper conveyed from the printer; and a control unit that rotates the pickup roller at predetermined time intervals.
The control means measures a time from when the pickup roller is rotated until the recording paper is detected by the paper feed sensor, calculates a deviation value between the measurement value and the reference value, and calculates an average value of the deviation values. The image forming apparatus is characterized in that the rotation timing of the pickup roller is corrected so that the recording paper interval is constant based on the above.   The image forming apparatus according to claim 1, wherein the control unit calculates the average value by excluding the deviation value in which a difference between the measured value and the reference value is negative.   The image forming apparatus according to claim 1, wherein the control unit calculates the average value by excluding the deviation value exceeding a predetermined upper limit value. The image forming apparatus according to claim 1, wherein the control unit calculates an arithmetic average, a geometric average, or a harmonic average as the average value.

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