Image forming apparatus, image forming method, and image forming program

Abstract

To provide an image forming apparatus that can return a traveling position of a belt in a belt conveying device to a reference position without impairing image formation accuracy.SOLUTION: An image forming apparatus comprises: a belt conveying device that causes an endless belt to travel which is laid over a plurality of rollers; an image forming unit that forms an image on a recording medium conveyed by the belt conveying device; and a belt position control unit for correcting a traveling position of the belt in the belt conveying device. In an image forming period in which the image forming unit forms the image, the belt position control unit controls the drive of the belt conveying device with a control amount within a preset upper limit, and in a non-image forming period in which the image forming unit does not form the image, controls the drive of the belt conveying device with a control amount within an upper limit larger than the aforementioned upper limit.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus, an image forming method, and an image forming program. [Background technology]

[0002] The image forming apparatus includes a belt conveying device such as an intermediate transfer belt that carries a toner image and a secondary transfer belt that conveys a recording medium. The belt conveying device is configured with an endless belt stretched over a plurality of rollers. In the image forming apparatus, such a belt conveying device is controlled to prevent the endless belt from meandering and becoming biased in the width direction, and for example, a technique described in the following Patent Document 1 is disclosed. Patent Document 1 states that "the belt device comprises an intermediate transfer belt, a driven roller, a drive roller, drive means, position detection means for detecting the position of the intermediate transfer belt in the width direction, a roller position adjustment mechanism for correcting meandering of the intermediate transfer belt, and a control unit for controlling the roller position adjustment mechanism, and the control unit controls the roller position adjustment mechanism to correct the meandering of the intermediate transfer belt when the position of the intermediate transfer belt detected by the position detection means is within the correction range under normal circumstances, and controls the roller position adjustment mechanism to correct the meandering of the intermediate transfer belt when the position of the intermediate transfer belt detected by the position detection means is outside the correction range but within an acceptable range under abnormal circumstances, and controls the roller position adjustment mechanism to correct the meandering of the intermediate transfer belt and controls the drive means so that the rotation speed of the drive roller is faster than normal," and states that this "enables the meandering belt to be quickly returned to the target position." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-89312 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the technology disclosed in Patent Document 1, the rotation speed of the drive roller is faster than normal when the belt position is abnormal, regardless of whether an image is being transferred to the recording medium or not. This makes it easy for the image to be transferred out of alignment with the recording medium, making it difficult to ensure the accuracy of image formation.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide an image forming apparatus, an image forming method, and an image forming program that are capable of returning the running position of a belt in a belt transport device to a reference position without impairing the accuracy of image formation. [Means for solving the problem]

[0006] In order to achieve this object, the present application provides an image forming apparatus comprising a belt conveying device that runs an endless belt around a plurality of rollers, an image forming unit that forms an image on a recording medium transported by the belt conveying device, and a belt position control unit that corrects the running position of the belt in the belt conveying device, wherein the belt position control unit controls the drive of the belt conveying device with a control amount within a preset upper limit value during an image formation period by the image forming unit, and controls the drive of the belt conveying device with a control amount within an upper limit value greater than the upper limit value during a non-image formation period by the image forming unit. Effect of the Invention

[0007] According to the present invention, it is possible to provide an image forming apparatus, an image forming method, and an image forming program that are capable of returning the running position of the belt in the belt transport device to a reference position without impairing the image formation accuracy. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a configuration diagram showing a main part of an image forming apparatus according to an embodiment. [Diagram 2] FIG. 2 is a side view showing a main part of the image forming apparatus according to the embodiment. [Diagram 3]FIG. 3 is a flowchart showing an image forming method according to an embodiment. [Figure 4] FIG. 4 is a diagram showing divisions of the running position of the belt. [Diagram 5] FIG. 5 is a graph showing a control amount in the belt position control according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an image forming apparatus, an image forming method, and an image forming program according to the present invention will be described in detail with reference to the accompanying drawings.

[0010] Image forming device FIG. 1 is a configuration diagram showing the main parts of an image forming apparatus 1 according to an embodiment. FIG. 2 is a side view showing the main parts of the image forming apparatus according to an embodiment. The image forming apparatus 1 shown in these figures is an image forming apparatus having a belt conveying device 10, and here, as an example, is an electrophotographic type. This image forming apparatus 1 includes the belt conveying device 10, an image forming unit 20 (shown only in FIG. 2), an intermediate transfer belt device 30, a medium supply section 40, a position sensor 50, an environment sensor 60, and a control section 100 (shown only in FIG. 1). Each of these components is as follows:

[0011] <Belt conveyor device 10> The belt conveying device 10 is for conveying a recording medium [m]. The belt conveying device 10 is configured with an endless belt 12 stretched across a plurality of rollers 11. The rollers 11 are arranged with their axial directions parallel to each other. One of these rollers 11 is a driving roller 11a for driving the belt 12 in a predetermined direction. The other rollers 11 after the driving roller 11a are driven rollers.

[0012] Another one of the rollers 11 is a secondary transfer roller 11b, which nips the recording medium [m] between itself and a roller 31 constituting an intermediate transfer belt device 30 described below.

[0013] Another one of the rollers 11 is a steering roller 11c, which adjusts the running position of the belt 12 in the width direction [CD] perpendicular to the running direction [FD] of the belt 12. Such a steering roller 11c adjusts the running position of the belt 12 by controlling the steering amount. The steering amount is the magnitude of the angle between the axial direction of the steering roller 11c and the axial direction of the other rollers 11, and is the magnitude of the inclination of the axial direction of the steering roller 11c. Note that the rollers 11 may be provided as necessary in addition to the drive roller 11a, the secondary transfer roller 11b, and the steering roller 11c, but are not illustrated here.

[0014] <Image forming unit 20 (FIG. 2)> The image forming units 20 are image forming sections for forming toner images of each color. Although only one image forming unit 20 is illustrated in Fig. 2, an image forming unit 20 is provided corresponding to each color. Each image forming unit 20 includes a photoconductor drum 21 and an exposure unit 22, and also includes a charging unit, a developing unit, and other components that are not illustrated here.

[0015] Of these, the photoconductor drum 21 is one of the image carriers on which a toner image is formed, and is a drum-shaped object rotated by a drive motor, with the peripheral side surface of the drum-shaped object serving as an image carrying surface. The exposure unit 22 forms an electrostatic latent image by exposure scanning on the image carrying surface of the photoconductor drum 21 that has been charged by the charging unit. The development unit, not shown here, forms a toner image of each color on the image carrying surface of the photoconductor drum 21 by supplying charged toner to the image carrying surface of the photoconductor drum 21 on which the electrostatic latent image has been formed.

[0016] <Intermediate transfer belt device 30> The intermediate transfer belt device 30 is a transfer unit that nips the recording medium [m] between the belt conveying device 10. The intermediate transfer belt device 30, together with the image forming unit 20, constitutes an image forming section that forms an image on the recording medium [m]. The intermediate transfer belt device 30 is arranged in parallel with the image forming unit 20. The intermediate transfer belt device 30 is configured by stretching an endless intermediate transfer belt 32 over a plurality of rollers 31. The plurality of rollers 31 are arranged with their axial directions parallel to each other. One of these rollers 31 is a drive roller for running the intermediate transfer belt 32 in a predetermined direction. The other of these rollers 31 is a transfer roller 31a that is arranged opposite to the secondary transfer roller 11b of the belt conveying device 10, and nips the recording medium [m] between the secondary transfer roller 11b.

[0017] The intermediate transfer belt device 30 also includes a plurality of primary transfer sections 33 inscribed in the intermediate transfer belt 32. The primary transfer sections 33 are disposed at positions facing the photoconductor drums 21 of the image forming units 20 in a state in which the moving intermediate transfer belt 32 is sandwiched between the primary transfer sections 33 and the photoconductor drums 21. A voltage of the opposite polarity to that of the toner is applied to these primary transfer sections 33, whereby the toner of each color adhering to the photoconductor drums 21 is transferred sequentially onto the intermediate transfer belt 32 to form a color image.

[0018] <Media supply section 40> The medium supply unit 40 is capable of storing a large amount of recording media [m], and sequentially supplies the stored recording media [m] to the belt conveying device 10. The recording media [m] supplied from the medium supply unit 40 is nipped between the secondary transfer roller 11b of the belt conveying device 10 and the transfer roller 31a of the intermediate transfer belt device 30. The recording media [m] supplied from the medium supply unit 40 is conveyed by the belt conveying device 10 in the conveying direction, which is the running direction [FD] of the belt 12. As a result, the image formed on the outer circumferential surface of the intermediate transfer belt 32 is sequentially transferred to the recording media [m].

[0019] <Position Sensor 50> The position sensor 50 measures the running position of the belt 12 in the belt conveyor 10. The running position of the belt 12 measured by the position sensor 50 is the position of the belt 12 in the width direction [CD] of the belt 12 perpendicular to the running direction [FD] of the belt 12.

[0020] The position sensor 50 is composed of an optical sensor 51 having light receiving elements arranged in the width direction [CD], for example, and an actuator 52. The actuator 52 has a measuring end that moves following the belt edge 12e in the width direction [CD]. Such a position sensor 50 indirectly measures the position of the belt edge 12e (i.e., the running position of the belt 12) by detecting the position of the measuring end of the actuator 52 with the optical sensor 51. The position sensor 50 transmits the measured running position to the control unit 100.

[0021] Such a position sensor 50 is preferably disposed in a portion where tension is applied to the belt 12 by the steering roller 11c. For this reason, as one example, it is preferable to dispose the position sensor 50 between the steering roller 11c and the drive roller 11a as shown in FIG.

[0022] <Environmental Sensor 60> The environmental sensor 60 is for measuring the environment within the image forming apparatus 1, and is, for example, a thermometer or a hygrometer. Such an environmental sensor 60 is disposed near the belt conveying device 10, measures the environment near the belt conveying device 10, and transmits the measured value to the control unit 100.

[0023] <Control unit 100 (FIG. 1)> The control unit 100 controls the formation of an image by the image forming apparatus 1. Such a control unit 100 is hardware used as a so-called computer, and includes a storage unit such as a CPU (Central Processing Unit) and a RAM (Random Access Memory), and a network interface. The control unit 100 controls the operation of each unit of the image forming apparatus 1 by the CPU executing a program stored in the storage unit. Such a control unit 100 includes an image formation control unit 100a that performs control for image formation, and a belt position control unit 100b. These are the following functional units.

[0024] [Image formation control unit 100a] The image formation control unit 100a performs control for forming an image on a recording medium [m]. The image formation control unit 100a forms an image by controlling the driving of the belt conveying device 10, the image forming unit 20 (shown only in FIG. 2), the intermediate transfer belt device 30, and the medium supply unit 40 according to input information from an input unit (not shown).

[0025] [Belt position control unit 100b] When the belt 12 of the belt conveying device 10 meanders, the belt position control unit 100b controls the belt conveying device 10 so that the belt 12 is held at a predetermined position in the width direction [CD]. The belt position control unit 100b includes a determination unit 101, a control amount calculation unit 102, and a drive control unit 103.

[0026] Among these, the determination unit 101 determines whether to perform belt position correction control or to stop driving the belt conveying device 10 based on information acquired from the position sensor 50. If it is determined that correction control is to be performed, the control amount calculation unit 102 calculates a control amount for the belt position correction control. The drive control unit 103 controls the drive of the belt conveying device 10 based on the control amount calculated by the control amount calculation unit 102. The control procedures by each unit in the belt position control unit 100b as described above will be described in detail in the following image forming method.

[0027] ≪Image forming method≫ Next, an image forming method performed in the image forming apparatus 1 described above will be described. FIG. 3 is a flowchart showing the image forming method according to the embodiment. The procedure shown in this flowchart is performed by an image forming program possessed by the belt position control unit 100b of the image forming apparatus 1 shown in FIG. 1, and is repeatedly performed during the execution of an image forming job. Below, the image forming method according to the embodiment will be described according to the procedure shown in FIG. 3, with reference to the above-mentioned FIGS. 1 and 2 and other necessary drawings.

[0028] <Step S101> In step S101, the determination unit 101 of the belt position control unit 100b acquires the running position of the belt 12 in the belt conveying device 10 from the position sensor 50.

[0029] <Step S102> In step S102, the determination unit 101 determines whether the running position of the belt 12 acquired in step S101 is within an allowable range. Here, the allowable range is a range in which the belt 12 and the running of the belt 12 do not cause mechanical damage.

[0030] FIG. 4 is a diagram showing the division of the belt running position in the belt conveying device, and is a diagram in which the belt running position in the width direction [CD] is divided into regions. The belt running position is the position of the belt edge 12e of the belt 12 shown in FIG. 1. In this case, the normal range [A1] centered on the reference position [p0] is a region that has little effect on image formation. Moreover, the non-normal ranges [A2] and [A-2] outside the normal range [A1] are ranges that have an effect on image formation. Moreover, the outer range [A3] beyond the non-normal ranges [A2] and [A-2] is an unacceptable range [A3] in which the belt 12 may be mechanically damaged by its running if the belt 12 running position enters this range. The normal range [A1] and the non-normal ranges [A2] and [A-2] are the allowable range [A0] in which the belt 12 and the belt 12 will not be mechanically damaged by its running. These ranges are preset ranges.

[0031] If the determination unit 101 determines that the running position of the belt 12 acquired in step S101 is within the allowable range [A0] (YES), the process proceeds to step S103, and if the determination unit 101 determines that the running position of the belt 12 acquired in step S101 is not within the allowable range [A0] (NO), the process proceeds to step S103a. If the determination unit 101 proceeds to step S103a, the running position of the belt 12 is within the non-allowable range [A3].

[0032] <Step S103a> In step S103a, the determination unit 101 instructs the image formation control unit 100a to stop the job. As a result, the image formation control unit 100a stops the job by controlling each unit of the image forming apparatus 1, and ends the process.

[0033] <Step S103> On the other hand, in step S103, the judgment unit 101 judges whether or not the running position of the belt 12 acquired in step S101 is in the normal range [A1] (see FIG. 4). If the judgment unit 101 judges that it is in the normal range [A1] (YES), the process proceeds to step S104, and if the judgment unit 101 judges that it is not in the normal range [A1] (NO), the process proceeds to step S105. If the process proceeds to step S105, the running position of the belt 12 is in the non-normal range [A2], [A-2].

[0034] Although the judgment here is based only on the running position of the belt, the judgment here may be based on the running position of the belt and the displacement speed of the running position of the belt. The displacement speed is obtained by monitoring the running position of the belt 12 acquired from the position sensor 50. In this case, even if the running position of the belt is within the normal range [A1], if the displacement speed exceeds a predetermined threshold, the judgment unit 101 proceeds to step S105.

[0035] <Step S104> In step 104, the control amount calculation unit 102 calculates a control amount within the range of the upper limit value [max] applied to the normal range [A1]. The control amount calculated here is the steering amount of the steering roller 11c, but the running speed of the belt may also be calculated as one of the control amounts. Upper limit values ​​[max] are set for each of the steering amount and the running speed. These upper limit values ​​[max] are values ​​that have been confirmed to not cause transfer defects by image formation performed on a trial basis.

[0036] The control amount calculation unit 102 calculates a control amount that can return the running position of the belt 12 to the reference position [p0] within the normal range [A1] with good controllability within the range of these upper limit values ​​[max] based on the running position of the belt 12 acquired from the position sensor 50. If the control amount calculated here is a steering amount, the value becomes larger as the running position of the belt 12 moves away from the reference position [p0]. Similarly, if the control amount calculated here is a running speed, the value becomes faster as the running position of the belt 12 moves away from the reference position [p0].

[0037] The control amount calculation unit 102 may hold a data table in which control amounts set in advance within the range of the upper limit value [max] are registered for each of the divided ranges [A11], [A12], ... obtained by dividing the normal range [A1] into a plurality of ranges. In this case, the control amount calculation unit 102 may extract an optimal control amount from the data table depending on which divided area the running position of the belt 12 obtained from the position sensor 50 is located in.

[0038] The control amount calculation unit 102 may be configured to calculate the control amount based on the traveling position of the belt 12 as well as the displacement speed of the traveling position of the belt 12. In this case, the faster the displacement speed of the traveling position is, the larger the steering amount is, and the faster the traveling speed is. By setting the control amount in consideration of the displacement speed, it is possible to bring the traveling position of the belt 12 closer to the reference position [p0] more quickly, and it is possible to prevent, for example, correction control from being performed too late.

[0039] In addition, the control amount calculation unit 102 may be configured to calculate the control amount by taking into consideration the running position of the belt 12 as well as a distortion specific to the belt conveying device 10 of the image forming apparatus 1. This distortion is information specific to each device, such as the parallelism between the rollers 11 constituting the belt conveying device 10 and the variation in the width direction [CD] of the nip pressure between the secondary transfer roller 11b and the transfer roller 31a. Such distortion may affect the movement amount (sensitivity) of the belt 12 with respect to the steering amount in the width direction [CD], for example. Therefore, the control amount calculation unit 102 calculates the steering amount by taking into consideration the variation in sensitivity based on the distortion information acquired at the time of shipment of the device. As an example, if the sensitivity is higher on the front side than on the back side in the width direction [CD], the control amount calculation unit 102 calculates the steering amount with respect to the running position of the belt 12 so that the sensitivity is larger on the front side than on the back side.

[0040] Furthermore, the control amount calculation unit 102 may be configured to calculate the control amount by taking into consideration the running position of the belt 12 as well as environmental information inside the device acquired by the environmental sensor 60. For example, when the temperature inside the device is low, the belt 12 becomes hard, and the responsiveness to steering decreases. For this reason, the steering amount is calculated to be a larger value as the temperature inside the device decreases.

[0041] <Step S105> On the other hand, in step S105, the judgment unit 101 judges whether or not the current job status is in a non-transfer period [T1] of an image to the recording medium [m] based on information from the image formation control unit 100a. The non-transfer period [T1] is a period during which the recording medium [m] is not placed in the nip portion between the secondary transfer roller 11b of the belt conveying device 10 and the transfer roller 31a of the intermediate transfer belt device 30. Such a non-transfer period [T1] is a period during which an image is not formed on the recording medium [m].

[0042] If the decision unit 101 determines that it is the non-transfer period [T1] (YES), the process proceeds to step S106, and if it determines that it is not the non-transfer period [T1] (NO), the process proceeds to step S104.

[0043] Here, the non-transfer period [T1] (NO) refers to the transfer period [T] in which the recording medium [m] is placed in the nip between the secondary transfer roller 11b of the belt conveying device 10 and the transfer roller 31a of the intermediate transfer belt device 30. The transfer period [T] is a period during which an image is formed on the recording medium [m]. In step S104, which is reached after determining that the non-transfer period [T1] (NO) is not present in step S105, the control amount is calculated within the range of the upper limit value [max] set to a value at which no transfer failure occurs, as described above.

[0044] <Step S106> In step S106, the control amount calculation unit 102 calculates the control amount within the range of the upper limit value [max1] (>[max]) set for the non-transfer period [T1]. The control amount calculated here is the same as the control amount calculated in step S105, but the upper limit value [max1] is different.

[0045] FIG. 5 is a graph showing the control amount in the belt position control according to the embodiment. The upper limit value [max1] of the control amount set for the non-transfer period [T1] is larger than the upper limit value [max] of the control amount set for the transfer period [T]. The non-transfer period [T1] is a period during which no image formation is performed by transfer onto the recording medium [m], so there is no need to consider transfer failure. Therefore, the upper limit value [max1] corresponding to the non-transfer period [T1] can be set larger than the upper limit value [max] of normal control corresponding to the transfer period [T]. Such a large upper limit value [max1] may be set within a range in which, for example, the steering amount and the running speed can be accurately controlled.

[0046] The calculation of the control amount by the control amount calculation unit 102 is performed in the same manner as the procedure described in step S104. The control amount becomes larger as the traveling position of the belt 12 moves away from the reference position [p0]. Therefore, the control amount calculated in step S106 within the range of the upper limit value [max1] (>[max]) becomes larger than the control amount calculated in step S104.

[0047] In addition, when calculating both the steering amount and the traveling speed as the control amount, the control amount calculation unit 102 calculates at least one of the steering amount and the traveling speed by setting the upper limit value <max1>As a result, in step S106, at least one of the steering amount and the traveling speed becomes larger than the value calculated in step S104.

[0048] <Step S107> In step S107, the drive control unit 103 instructs the medium supply unit 40 to set the supply interval of the recording medium [m] to a predetermined interval wider than the normal interval. As a result, the medium supply unit 40 widens the supply interval of the recording medium [m] to a predetermined interval wider than the normal interval. Note that this step S107 does not necessarily have to be performed, and by performing it, it is possible to bring the running position of the belt 12 closer to the position [p0] during the non-transfer period [T1]. In addition, the supply interval widened to the predetermined interval in this step S107 is returned to the normal interval when it is determined in step S103 of the flow that the running position of the belt is in the normal range [A1] (YES) next time.

[0049] <Step S108> In step S108, the drive control unit 103 controls the steering amount of the steering roller 11c so as to achieve the control amount calculated in step S104 or step S106. If the travel speed of the belt 12 is calculated as the control amount, the drive control unit 103 controls the drive roller 11a so as to achieve the calculated travel speed.

[0050] <Effects of the embodiment> According to the embodiment described above, in the transfer period [T1], the running position of the belt 12 is controlled within a range in which no transfer shift occurs, and in the non-transfer period [T1], the running position of the belt 12 is controlled with a larger control amount than in the transfer period [T]. This makes it possible to quickly return the running position of the belt 12 in the belt conveying device 10 to the reference position [p0] without impairing the image formation accuracy due to the occurrence of transfer shift.

[0051] Moreover, when the running position of the belt 12 falls within the non-normal range [A2], [A-2], the running position is corrected with a large control amount during the non-transfer period [T1] without stopping the belt conveying device 10. Therefore, there is no interruption of image formation due to stopping the belt conveying device 10, and it is possible to improve the productivity in image formation. Furthermore, since it is possible to prevent the occurrence of transfer misalignment, it is possible to prevent the occurrence of loss in image formation, which also makes it possible to improve the productivity in image formation.

[0052] The present invention is not limited to the above-described embodiment, and further includes various modified examples. For example, the present invention may not require step S103 in the above-described embodiment. In this case, the process may proceed to step S105 if it is determined in step S102 that the belt running position is within the allowable range [A0] (YES). As a result, the upper limit value of the control amount may be selected in step S105 only depending on whether or not it is in the non-transfer period [T1]. [Explanation of symbols]

[0053] 1...Image forming device 10...Belt conveyor 11. Roller 11a...Drive roller 11b...Secondary transfer roller 11c…Steering roller 12...Belt 20...Image forming unit (image forming section) 30...Intermediate transfer belt device (transfer unit, image forming section) 40…Media supply device 50...Position sensor 60…Environmental sensor 100b...Belt position control section [A2], [A-2]…Non-normal range (pre-set range) [m]…Recording medium [max]...Upper limit [max1]...Largest upper limit [T]: Transfer period (image formation period) [T1]: Non-transfer period (non-image formation period)

Claims

1. A belt conveying device that runs an endless belt around a plurality of rollers; an image forming unit that forms an image on the recording medium transported by the belt transport device; a belt position control unit for correcting a running position of the belt in the belt conveying device, The belt position control unit is During an image forming period by the image forming unit, driving of the belt conveying device is controlled with a control amount within a preset upper limit value. During a non-image forming period by the image forming unit, driving of the belt conveying device is controlled with a control amount within an upper limit value that is larger than the upper limit value. Image forming device.

2. The control amount is at least one of a steering amount of a steering roller among the plurality of rollers and a running speed of the belt. The image forming apparatus according to claim 1 .

3. A position sensor is provided for detecting a running position of the belt, The belt position control unit controls the driving of the belt conveying device with the control amount based on the running position of the belt acquired from the position sensor. The image forming apparatus according to claim 1 .

4. The belt position control unit controls driving of the belt conveying device with the control amount based on a running position of the belt and a displacement speed of the running position of the belt. The image forming apparatus according to claim 3 .

5. The belt position control unit controls the driving of the belt conveying device with a control amount within the large upper limit value range when the running position of the belt falls within a preset range. The image forming apparatus according to claim 3 .

6. a medium supplying device that supplies a recording medium to the belt conveying device, The belt position control unit increases an interval at which the recording medium is supplied to the belt transport device when the running position of the belt is within a preset range. The image forming apparatus according to claim 3 .

7. The belt position control unit controls the driving of the belt conveying device with a control amount within the large upper limit value range when the running position of the belt falls within a preset range or when the displacement speed of the running position of the belt reaches a preset threshold value. The image forming apparatus according to claim 3 .

8. The belt position control unit stops driving the belt conveying device when the running position of the belt exceeds a preset range. The image forming apparatus according to claim 3 .

9. The belt position control section controls the driving of the belt conveying device with a larger control amount during the non-image forming period than during the image forming period. The image forming apparatus according to claim 1 .

10. The belt position control unit controls the driving of the belt conveying device within a control amount within a range that has been confirmed not to affect image formation on the recording medium during the image formation period. The image forming apparatus according to claim 1 .

11. the image forming period is a period during which an image is transferred onto the recording medium, The non-image forming period is a period during which an image is not transferred to the recording medium. The image forming apparatus according to claim 1 .

12. An environmental sensor is provided for measuring an environment within the device; The belt position control unit controls the driving of the belt conveying device with the control amount taking into consideration the environment inside the device acquired from the environmental sensor. The image forming apparatus according to claim 1 .

13. The belt position control unit controls the driving of the belt conveying device with the control amount taking into consideration the parallelism of the plurality of rollers. The image forming apparatus according to claim 1 .

14. a transfer unit that nips the recording medium between itself and the belt conveying device, The belt position control unit controls the driving of the belt conveying device with the control amount taking into consideration variations in nip pressure at a nip portion that nips the recording medium. The image forming apparatus according to claim 1 .

15. The running position of the belt is a position perpendicular to the running direction of the belt by the belt conveying device. The image forming apparatus according to claim 1 .

16. An image forming method using an image forming apparatus including a belt conveying device that loops an endless belt around a plurality of rollers and runs the belt, an image forming unit that forms an image on a recording medium that is conveyed by the belt conveying device, and a belt position control unit that corrects a running position of the belt in the belt conveying device, comprising: The belt position control unit includes: During an image forming period by the image forming unit, driving of the belt conveying device is controlled with a control amount within a preset upper limit value. During a non-image forming period by the image forming unit, driving of the belt conveying device is controlled with a control amount within an upper limit value that is larger than the upper limit value. Image forming method.

17. An image forming apparatus including a belt conveying device that causes an endless belt to run around a plurality of rollers, and an image forming unit that forms an image on a recording medium conveyed by the belt conveying device, comprising: an image forming program for causing a computer to execute control for correcting a running position of a belt in the belt conveying device, the image forming program comprising: driving the belt conveying device at a control amount within a preset upper limit during an image forming period by the image forming unit; During a non-image forming period by the image forming unit, the belt conveying device is driven at a control amount within an upper limit value that is larger than the upper limit value. Image formation program.

Images