JP2004151384A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent occurrence of positional deviation in color toner images during toner image transfer by precisely grasping the exchange period of a resist roller when the resist roller characteristics deteriorate. <P>SOLUTION: In an image forming device, a recording paper transported by a resist roller is transported to color image carrying bodies by transfer belts, and the toner images on the bodies are transferred onto the paper. A message urging to exchange the resist roller is displayed (S105) when the amount of correction on the rotational speed of a corrected resist roller reaches a certain amount from the initial setting value of the rotational speed of the resist roller (YES on S103) so that the transporting speed of the paper by the resist roller is slightly made faster than the running speed of the transfer belts while maintaining a prescribed speed difference. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a copier or a printer that forms an image by superimposing toner images of a plurality of colors.
[0002]
[Prior art]
Conventionally, there is an image forming apparatus such as a copying machine or a printer that forms an image by superimposing and transferring a toner image from an image carrier for each color, but in this image forming apparatus, a recording paper is conveyed to the image carrier. If there is a difference in the conveyance speed of the recording paper before and after the recording paper is carried into the transfer belt, the traveling speed of the transfer belt fluctuates due to the influence of the conveyance speed of the recording paper carried into the transfer belt. In some cases, the recording paper was not conveyed to the image carrier of each color at an appropriate speed, and a misregistration occurred in each color toner image when transferring each color toner image. Therefore, the recording paper transport speed by the registration rollers disposed on the upstream side of the transfer belt is set to a speed slightly higher than the recording paper transport speed by the transfer belt (for example, a speed that is approximately 0.5 to 1% faster in an experiment). And the registration roller is disposed at a position obliquely displaced vertically with respect to the transfer belt, so that the leading end of the recording paper and the suction belt disposed opposite to the transfer belt. Even if the paper is conveyed between the transfer rollers and the transfer belt, the transfer speed of the transfer belt by the transfer belt is slightly reduced. The difference was to be absorbed.
[0003]
[Problems to be solved by the invention]
However, the recording paper transport speed by the registration roller or the like is such that the diameter of the registration roller or the like changes depending on the environment, or the grip force is reduced due to abrasion with time or the adhesion of paper powder, and the like. Since the transport speed may change, it is difficult to maintain this speed difference even if a predetermined speed difference is set between the transfer belt traveling speed and the recording paper transport speed by the registration rollers as described above. .
[0004]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and in the case where the gripping force is reduced due to the aging of the registration roller or the like, the timing of replacing the registration roller can be accurately grasped. It is an object of the present invention to provide an image forming apparatus capable of preventing misregistration of each color toner image during image transfer.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a recording sheet conveyed by a registration roller is conveyed to an image carrier provided for each color by a transfer belt, and the toner on each image carrier is conveyed. An image forming apparatus for forming an image by transferring an image onto recording paper,
Transfer belt driving means for running the transfer belt,
Registration roller driving means for rotationally driving the registration roller,
Transfer belt speed detection means for detecting the traveling speed of the transfer belt,
Conveying speed detecting means for detecting a conveying speed of the recording paper conveyed from the registration roller to the transfer belt,
The registration roller drive is performed such that the conveyance speed of the recording paper detected by the conveyance speed detection unit is faster than the traveling speed of the transfer belt detected by the transfer belt speed detection unit while maintaining a predetermined speed difference. Control means for driving and controlling at least one of the means or the transfer belt driving means,
The control unit determines that it is time to replace the registration roller when the correction amount of the registration roller driving unit or the transfer belt driving unit reaches a certain amount from an initial setting value of the recording paper conveyance speed. Is what you do.
[0006]
According to this configuration, by controlling the difference between the transfer belt traveling speed and the conveyance speed of the recording paper by the registration roller to be kept substantially constant, the traveling speed of the transfer belt influences the influence of the recording paper carry-in speed. In addition to being able to reduce the fluctuations caused by the transfer, the displacement of each color toner image during the transfer of each color toner image can be prevented, and the correction amount of the recording paper transport speed is reduced from the initial setting value of the recording paper transport speed to a fixed amount. If it has reached, it is determined that it is time to replace the registration roller, so that it is possible to accurately detect, for example, that the registration roller performance has deteriorated due to aging. This makes it possible to reliably prevent the positional deviation of each color toner image during image transfer.
[0007]
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, when the control unit determines that it is time to replace the registration roller, a warning that warns replacement of the registration roller is issued. Means.
[0008]
According to this configuration, the warning from the warning unit allows the user to reliably recognize the time to replace the registration roller.
[0009]
According to a third aspect of the present invention, the recording paper conveyed by the registration rollers is conveyed to image carriers provided for each color by a transfer belt, and the toner image on each image carrier is recorded on the recording paper. An image forming apparatus for forming an image by transferring,
Transfer belt driving means for running the transfer belt,
Registration roller driving means for rotationally driving the registration roller,
Transfer belt speed detection means for detecting the traveling speed of the transfer belt,
Conveying speed detecting means for detecting a conveying speed of the recording paper conveyed from the registration roller to the transfer belt,
The registration roller drive is performed such that the conveyance speed of the recording paper detected by the conveyance speed detection unit is faster than the traveling speed of the transfer belt detected by the transfer belt speed detection unit while maintaining a predetermined speed difference. Temperature and humidity detecting means for detecting the temperature or humidity in the apparatus and a control means for driving and controlling at least one of the means or the transfer belt driving means,
The control unit controls the driving of the registration roller driving unit or the transfer belt driving unit when a change in the temperature or humidity detected by the temperature and humidity detection unit reaches a predetermined value.
[0010]
According to this configuration, when the amount of change in temperature or humidity in the apparatus reaches a predetermined value, the driving control of the registration roller driving unit or the transfer belt driving unit is performed so that the traveling speed of the transfer belt and the recording paper are controlled. Since the conveyance speed is corrected, the timing of the registration roller performance, such as the size of the registration roller, is likely to change due to changes in the temperature or humidity in the apparatus. Speed adjustment with the recording paper conveyance speed by the registration roller can be performed.
[0011]
According to a fourth aspect of the present invention, the recording paper conveyed by the registration rollers is conveyed to an image carrier provided for each color by a transfer belt, and a toner image on each image carrier is recorded on the recording paper. An image forming apparatus for forming an image by transferring,
Transfer belt driving means for running the transfer belt,
Registration roller driving means for rotationally driving the registration roller,
Transfer belt speed detection means for detecting the traveling speed of the transfer belt,
Conveying speed detecting means for detecting a conveying speed of the recording paper conveyed from the registration roller to the transfer belt,
The registration roller drive is performed such that the conveyance speed of the recording paper detected by the conveyance speed detection unit is faster than the traveling speed of the transfer belt detected by the transfer belt speed detection unit while maintaining a predetermined speed difference. Control means for controlling driving of at least one of the means or the transfer belt driving means, and a recording sheet conveyance number detection means for detecting the number of recording sheets conveyed to the transfer belt by the registration roller,
The control means controls the driving of the registration roller driving means or the transfer belt driving means when the number of recording papers detected by the recording paper conveyance number detecting means reaches a predetermined value.
[0012]
According to this configuration, when the number of recording sheets conveyed to the transfer belt by the registration roller reaches a predetermined value, drive control of the registration roller driving unit or the transfer belt driving unit is performed, so that the durability period of the registration roller is reduced. Precisely, it is possible to accurately adjust the traveling speed of the transfer belt and the recording paper transport speed by the registration roller before the diameter of the registration roller changes due to wear or the like.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating an example of a schematic configuration of an image forming apparatus according to the present invention. As shown in FIG. 1, in a printer (an example of an image forming apparatus) 1, a developing device 3 is provided in a printer main body 2 for each of cyan, magenta, yellow, and black. Each developing device 3 is provided with a photosensitive drum (image carrier) 4 made of a-Si (amorphous silicon) or the like, and is configured to rotate in the direction of the arrow in the figure. The photosensitive drum 4 is uniformly charged by the charging unit 5, and LED light based on document image data input from an external PC (personal computer) or the like is transmitted from the exposure unit (LED print head unit or the like) 6 to the photosensitive drum 4. The electrostatic latent image is formed by irradiating the electrostatic latent image on the surface, and toner adheres to the electrostatic latent image to form a toner image.
[0014]
The toner is supplied from toner supply containers 7C, 7M, 7Y and 7B, respectively. A transfer belt 8 that conveys a recording sheet is provided below the photosensitive drums 4 for the respective colors. The transfer belt 8 is pressed against each photosensitive drum 4 by a transfer roller 9, and is driven by a driving roller 10, which is driven to rotate by a motor (not shown), and driven rollers 11, 24, which rotate according to the transfer belt 8. The photosensitive drum 4 is rotated endlessly in the forward direction of the rotation direction.
[0015]
Then, the recording paper is conveyed from the paper feeding mechanism 12 to the transfer belt 8 via the recording paper conveyance path 13, and the image transfer operation by the respective photosensitive drums 4 and the transfer rollers 9 by the registration roller 17 and the paper feeding The timing with the operation is adjusted. After the adjustment of the timing, the recording paper is conveyed between the photosensitive drum 4 and the transfer belt 8 by the registration roller 17. While the recording paper is being conveyed between the photosensitive drums 4 and the transfer belt 8, the toner images of the respective colors on the surface of the photosensitive drums 4 are successively transferred to the recording paper by applying a transfer bias of the transfer roller 9. .
[0016]
The recording paper on which the toner images have been transferred by all the photosensitive drums 4 is conveyed to a fixing roller pair 14 where the toner images are fixed, and a color image is formed. The recording paper that has passed through the fixing roller pair 14 is sent to a recording paper transport path 15 and discharged from a discharge unit 16. Each of the photosensitive drums 4 is provided with a cleaning mechanism 21 for removing residual toner and the like on the photosensitive drum 4.
[0017]
Further, the image forming unit for each color (photosensitive drum 4, charging unit 5, exposing unit 6, developing device 3, transfer roller 9, etc.) is further upstream of the cyan image forming unit disposed on the most upstream side. On the side, a suction roller 18 for electrostatically attracting the recording paper to the transfer belt 8 is provided. The suction roller 18 is provided at a position facing the transfer belt 8 and the driven roller 11 so as to contact the driven roller 11 via the transfer belt 8. The suction roller 18 is driven to rotate along with the travel of the transfer belt 8.
[0018]
FIG. 2 is a block diagram illustrating an example of a schematic configuration of the printer 1. The printer 1 includes a control unit 110 that controls the entire printer 1. The control unit 110 is connected to a ROM 112 that stores an operation program and the like of the entire apparatus, and is connected to a RAM 113 that temporarily stores image data and the like and functions as a work area. Further, the image forming units 20B, 20Y, 20M, and 20C for each color are connected to the control unit 110, and the control unit 110 is provided with a charging unit provided in each of the image forming units 20B, 20Y, 20M, and 20C. 5, an exposure unit 6, a developing device 3, a transfer bias unit 114 for applying a transfer bias to a transfer roller 9 for transferring a toner image on the photosensitive drum 4 to recording paper, and a drive source for the photosensitive drum 4. Is controlled with the drum motor 115.
[0019]
The fixing motor 120 drives the fixing roller pair 14 to rotate, and is controlled by the control unit 110 via a driver 120a. A clock signal is sent from the control unit 110 to the driver 120a, and the fixing motor 120 rotates at a rotation speed according to the frequency of the clock signal. Therefore, the rotation speed of the fixing motor 120 can be controlled by changing the frequency of the clock signal sent to the driver 120a by the control unit 110. Further, the fixing heater 121 is provided in a heat roller constituting one of the fixing roller pairs 14, and is controlled on and off by the control unit 110. In FIG. 2, each image forming unit for yellow, magenta, and cyan is shown as one image forming unit. However, each image forming unit for each color is actually connected to the control unit 110 and controlled. ing.
[0020]
The transfer belt drive motor 125 is a drive source of the drive roller 10 that drives the transfer belt 8, and is controlled by the control unit 110 via a driver 125a. A clock signal is sent from the control unit 110 to the driver 125a, and the transfer belt drive motor 125 rotates at a rotation speed according to the frequency of the clock signal. Therefore, the rotation speed of the transfer belt drive motor 125 can be controlled by changing the frequency of the clock signal sent to the driver 125a by the control unit 110.
[0021]
The attraction roller bias unit 126 applies a bias to the attraction roller 18 that is necessary to apply, to the recording paper, an electric charge for electrostatically attracting the recording paper to the transfer belt 8. The operation unit 127 includes an operation panel on which a print instruction or the like from a user is input and a display unit for displaying various messages. Further, the control unit 110 is connected to a PC (personal computer) 130 via an interface 129. The printer 1 forms an image based on the image data input from the PC 130.
[0022]
The registration motor 133 rotates the registration roller 17 (FIG. 1), and is controlled by the control unit 110 via a driver 133a. A clock signal is sent from the control unit 110 to the driver 133a, and the registration motor 133 rotates at a rotation speed according to the frequency of the clock signal. Therefore, the rotation speed of the registration motor 133 can be controlled by changing the frequency of the clock signal sent to the driver 125a by the control unit 110.
[0023]
The registration sensor 137 detects that the recording paper is at the position of the registration roller 17. The first sensor 135a and the second sensor 135b are optical sensors or the like arranged in parallel in the recording paper transport direction between the transfer belt 8 and the registration rollers 17 to detect the leading and trailing ends of the recording paper. The sensor 135a is disposed upstream of the second sensor 135b in the recording paper transport direction. The timer 136 measures various times. The registration sensor 137 detects a registration mark formed on the transfer belt 8 (for example, the registration mark may be outside the recording paper placement area or between recording papers placed).
[0024]
The fixing roller sensor 140 is disposed downstream of the fixing roller pair 14 and detects the leading and trailing ends of the recording paper nipped by the fixing roller pair 14. The suction roller sensor 141 is a sensor that detects that a recording sheet has been carried in between the suction roller 18 and the transfer belt 8, and is disposed near the suction roller 18.
[0025]
The attraction roller mark sensor 142 is a sensor for detecting a marking formed on the peripheral surface of the attraction roller 18. The recording paper counter 143 counts the number of recording papers conveyed by the registration rollers 17. The temperature and humidity sensor 145 detects the temperature and humidity inside the printer 1 (especially, near the registration roller 17). The driven roller sensor 146 is a sensor for detecting a marking formed on the peripheral surface of the driven roller 24.
[0026]
Next, a brief description will be given of the speed adjustment of the transfer belt traveling speed at the time of transfer of each color toner image by the respective color photosensitive drums 4 and the recording paper conveyance speed by the registration rollers 17. FIG. 3 is a flowchart showing the speed adjustment processing. The speed adjustment is caused by a speed difference between the recording paper conveyance speed by the registration roller 17 and the traveling speed of the transfer belt 8 when the recording paper is carried from the registration roller 17 between the transfer belt 8 and the suction roller 18. This is performed to prevent fluctuations in the traveling speed of the transfer belt 8 (the speed at which the recording sheet is conveyed by the transfer belt 8).
[0027]
First, the traveling speed of the transfer belt 8 and the recording paper transport speed by the registration rollers 17 are detected (S1, S2), and the recording paper transport speed by the registration rollers 17 is different from the traveling speed of the transfer belt 8 by a predetermined speed difference (for example, In the experiment, it is preferable that the conveying speed of the recording paper by the registration roller 17 be higher than the traveling speed of the transfer belt 8 by about 0.2%.) Is determined (S3). Here, if the predetermined speed difference is not maintained (NO in S3), the rotation of the registration motor 133 is adjusted so that the recording paper conveyance speed by the registration roller 17 and the traveling speed of the transfer belt 8 have the predetermined speed difference. The speed is corrected (S4). For example, when the recording paper conveyance speed by the registration rollers 17 is a high speed having a speed difference exceeding the predetermined speed difference with respect to the traveling speed of the transfer belt 8, the rotation speed of the registration motor 133 is reduced. If the recording paper conveyance speed by the registration rollers 17 is a low speed that does not have the above-mentioned predetermined speed difference with respect to the traveling speed of the transfer belt 8, the rotation speed of the registration motor 133 is set to be high. If the above speed difference is maintained (YES in S3), the process ends because there is no need to correct the rotation speed of the registration motor 133.
[0028]
An example of a process for detecting the traveling speed of the transfer belt 8 in the speed adjustment will be described. FIG. 4 is a flowchart showing the speed detection process, and FIG. 5 is a diagram showing a state of forming a registration mark on the transfer belt 8. First, the transfer belt drive motor 125 is driven to rotate to move the transfer belt 8 (S21). Then, the first registration mark is formed on the transfer belt 8 by one of the image forming units for each color (for example, the image forming unit for cyan at the most upstream side) (S22), and another image forming unit (for example, The formation of the second registration mark on the transfer belt 8 from the downstream black image forming unit) is performed simultaneously (S23). As a result, a certain interval (in the above example, the distance from the transfer position by the photosensitive drum 4 for cyan to the transfer position by the photosensitive drum 4 for black) is set on the transfer belt 8 from the first registration mark. A second registration mark will be formed at the position.
[0029]
When the first registration mark is detected by the registration sensor 137 (YES in S24), counting by the timer 136 is started (S25). When the second registration mark is detected by the registration sensor 137 (YES in S26), the counting by the timer 136 is stopped (S27). The count value of the timer 136 is obtained (S28), and the time from the detection of the first registration mark to the detection of the second registration mark is detected. The count value of the timer 136 (the time from the detection of the first registration mark to the detection of the second registration mark) and the interval between the first registration mark and the second registration mark (in the above example, the photosensitive drum 4 for cyan) (The distance from the transfer position to the transfer position by the photosensitive drum 4 for black) based on the transfer speed of the transfer belt 8 is calculated (S29).
[0030]
The formation of the first and second registration marks in S22 and S23 is performed, for example, after the first registration mark is formed by the photosensitive drum 4 for cyan and then the first registration mark is changed to the photosensitive drum 4 for black. After a predetermined time α has passed after passing through the transfer position, the second registration mark by the photosensitive drum 4 for black may be formed (the first registration mark by the photosensitive drum 4 for cyan is Assuming that the time required to reach the transfer position by the photosensitive drum 4 for black is T, the formation of the second registration mark by the photosensitive drum 4 for black is performed when the time T + α has elapsed from the formation of the first registration mark. Will be). In this case, based on the ratio between the actual measurement time (timer count value) from the first mark detection to the second mark detection by the registration sensor 137 and the fixed time α, the reference speed corresponding to the time α is calculated. The traveling speed of the transfer belt 8 is calculated.
[0031]
Another example of the process of detecting the traveling speed of the transfer belt 8 will be described. FIG. 6 is a flowchart showing the speed detection process. The detection of the traveling speed of the transfer belt 8 is to calculate the traveling speed of the transfer belt 8 based on the rotation speed of the driven roller 24 that rotates following the transfer belt 8.
[0032]
First, the transfer belt drive motor 125 is driven to rotate, and the transfer belt 8 runs (S31), and the driven roller 24 is rotated together with the transfer belt 8. Then, when one marking provided on the outer peripheral surface of the driven roller 24 is detected by the driven roller sensor 146 (YES in S32), counting by the timer 136 is started (S33). When the driven roller 24 makes one rotation and the above-mentioned marking is detected again by the driven roller sensor 146 (YES in S34), the counting by the timer 136 is stopped (S35). The count value of the timer 136 is obtained (S36), and the time from when the mark is first detected to when the mark is detected again (the time required for the driven roller 24 to make one revolution) is detected. The rotational speed of the driven roller 24 is calculated based on the calculated value (S37). Then, the traveling speed of the transfer belt 8 is calculated based on the rotation speed of the driven roller 24 and the outer peripheral length of the driven roller 24 (S38).
[0033]
Another example of the process of detecting the traveling speed of the transfer belt 8 will be described. FIG. 7 is a flowchart showing the speed detection process. The detection of the traveling speed of the transfer belt 8 is to calculate the traveling speed of the transfer belt 8 based on the rotation speed of the suction roller 18 that rotates following the transfer belt 8.
[0034]
First, the transfer belt drive motor 125 is driven to rotate to move the transfer belt 8 (S41), and the suction roller 18 is rotated together with the transfer belt 8. Then, when one marking provided on the outer peripheral surface of the suction roller 18 is detected by the suction roller sensor 141 (YES in S42), counting by the timer 136 is started (S43). Then, when the suction roller 18 makes one rotation and the marking is detected again by the suction roller sensor 141 (YES in S44), the counting by the timer 136 is stopped (S45). The count value t2 of the timer 136 is obtained (S46), and the time from when the mark is first detected to when the mark is detected again (the time required for the suction roller 18 to make one revolution) is detected. The rotation speed of the suction roller 18 is calculated based on the calculated value (S47). Then, the traveling speed of the transfer belt 8 is calculated based on the rotation speed of the suction roller 18 and the outer peripheral length of the suction roller 18 (S48).
[0035]
A process of detecting the recording paper conveyance speed by the registration roller 17 in the above speed adjustment will be described. FIG. 8 is a flowchart showing the recording paper conveyance speed detection processing. First, the registration motor 133 is driven to convey the recording paper toward the transfer belt 8 (S51), and the first sensor 135a disposed between the registration roller 17 and the transfer belt 8 detects the leading end of the recording paper. Then (YES in S52), counting by the timer 136 is started (S53), and when the leading edge of the recording paper is detected by the second sensor 135b downstream of the first sensor 135a (YES in S54), the timer 136 starts counting. The counting is stopped (S55). The count value t3 of the timer 136 is obtained (S56), the movement time of the leading edge of the recording paper between the first sensor 135a and the second sensor 135b is detected, and this time and the distance between the first sensor 135a and the second sensor 135b are detected. Is calculated based on the above (S57).
[0036]
Next, another example of the speed adjustment processing of the traveling speed of the transfer belt 8 and the recording paper conveyance speed by the registration rollers 17 at the time of transferring each color toner image will be described. FIG. 9 is a flowchart showing the speed adjustment process, and FIG. 10 is a schematic side view showing the first sensor and the second sensor provided between the transfer belt 8 and the registration roller 17. In the above speed adjustment process, the traveling speed of the transfer belt 8 and the recording paper transport speed by the registration rollers 17 are detected, and the rotation speed of the registration motor 133 is controlled so that the two speeds have a predetermined speed difference. However, the recording paper conveyance speed difference before and after the recording paper is carried in between the transfer belt 8 and the suction roller 18 is detected, and the rotation speed of the registration motor 133 is adjusted so that the speed difference has a predetermined speed difference. You may make it control.
[0037]
This speed adjustment process is performed when the leading edge of the recording paper has already passed through the registration roller 17 and the trailing edge of the recording paper has not passed through the registration roller 17 yet. The present invention is applied to the printer 1 having a structure to be carried in. The recording paper conveyance speed before the recording paper is conveyed between the transfer belt 8 and the suction roller 18 is detected based on the time when the leading end of the recording paper moves between the first sensor 135a and the second sensor 135b, and the transfer is performed. The recording paper conveyance speed after the recording paper is conveyed between the belt 8 and the suction roller 18 is detected based on the time during which the rear end of the recording paper moves between the first sensor 135a and the second sensor 135b.
[0038]
First, the registration motor 133 is driven to convey the recording paper toward the transfer belt 8 (S61), and when the first sensor 135a detects the leading end of the recording paper (YES in S62), counting by the timer 136 is started. (S63) When the second sensor 135b downstream of the first sensor 135a detects the leading end of the recording paper (YES in S64), the counting by the timer 136 is stopped (S65). By acquiring the count value t4 of the timer 136 (S66), the movement time of the leading edge of the recording paper between the first sensor 135a and the second sensor 135b is detected.
[0039]
Subsequently, when the first sensor 135a detects the trailing edge of the recording paper (YES in S67), counting by the timer 136 is started (S68), and when the leading edge of the recording paper is detected by the second sensor 135b (YES in S69). ), The counting by the timer 136 is stopped (S70). The count value t5 of the timer 136 is obtained (S71), and the movement time of the trailing edge of the recording paper between the first sensor 135a and the second sensor 135b is detected.
[0040]
The movement times (count values t4, t5) between the first sensor 135a and the second sensor 135b at the leading and trailing ends of the recording paper are compared (S72), and the difference between the count value t4 and the count value t5 is described later. If it is not the predetermined value (NO in S72), the rotation of the registration motor 133 is adjusted so that the recording paper conveyance speed by the registration roller 17 is higher than the traveling speed of the transfer belt 8 while maintaining the above-described predetermined speed difference. The speed is corrected (S73). That is, the difference between the count value t4 and the count value t5 is adjusted by adjusting the difference between the count value t4 and the count value t5 because the difference between the count value t4 and the count value t5 represents the speed difference between the recording paper conveyance speed by the registration roller 17 and the traveling speed of the transfer belt 8. This makes it possible to adjust the speed difference between the recording paper conveyance speed by the registration rollers 17 and the traveling speed of the transfer belt 8. Therefore, the above-described predetermined speed difference between the recording paper conveyance speed by the registration rollers 17 and the traveling speed of the transfer belt 8 (the conveyance speed of the recording paper by the registration rollers 17 exceeds the traveling speed of the transfer belt 8 by about 0.2%) The value of the difference between the count value t4 and the count value t5 corresponding to the above is held as a predetermined value, and the difference between the actually measured count value t4 and the count value t5 is set to the predetermined value. By controlling the rotation speed of the registration motor 133, it is possible to obtain a state in which the recording paper conveyance speed by the registration rollers 17 is higher than the traveling speed of the transfer belt 8 while maintaining the above-described predetermined speed difference.
[0041]
For example, if the value obtained by subtracting the count value t4 from the count value t5 exceeds the predetermined value, the rotation speed of the registration motor 133 is reduced, and the value obtained by subtracting the count value t4 from the count value t5 exceeds the predetermined value. If not, the rotation speed of the registration motor 133 is increased.
[0042]
If the difference between the count value t4 and the count value t5 is the above-described predetermined value (YES in S72), the process ends because there is no need to correct the rotation speed of the registration motor 133.
[0043]
Another example of the speed adjustment processing of the traveling speed of the transfer belt 8 and the recording paper conveyance speed by the registration roller 17 at the time of transferring each color toner image is described. FIG. 11 is a flowchart showing the speed adjustment processing. The speed adjustment process between the traveling speed of the transfer belt 8 and the recording paper conveyance speed by the registration roller 17 at the time of transferring each color toner image is performed by the suction roller 18 before and after the recording paper is carried in between the transfer belt 8 and the suction roller 18. May be detected, and the driving of the registration motor 133 may be controlled such that the rotational speed difference has a predetermined speed difference described later.
[0044]
First, the transfer belt drive motor 125 is driven (S81), and the suction roller 18 is rotated together with the transfer belt 8. The application of the suction roller bias and the transfer roller bias is stopped (S82). Then, in a state where the recording sheet is not conveyed between the transfer belt 8 and the attraction roller 18, when one marking provided on the outer peripheral surface of the attraction roller 18 is detected by the attraction roller mark sensor 142 (S83). YES), counting by the timer 136 is started (S84). When the suction roller 18 makes one revolution and the marking is detected again by the suction roller mark sensor 142 (YES in S85), the counting by the timer 136 is stopped (S86), and the count value t6 of the timer 136 is obtained. (S87).
[0045]
Thereafter, the registration motor 133 is driven (S88), the recording paper is conveyed between the transfer belt 8 and the attraction roller 18, and when the leading edge of the recording paper is detected by the attraction roller sensor 141 (YES at S89), the attraction roller is driven. The mark sensor 142 starts detecting the mark of one marking provided on the outer peripheral surface of the suction roller 18 (S90). When the marking of the attraction roller 18 is detected by the attraction roller mark sensor 142 (YES at S91), counting by the timer 136 is started (S92). When the driven roller 24 makes one revolution and the above-mentioned marking is detected again by the attraction roller mark sensor 142 (YES in S93), the counting by the timer 136 is stopped (S94), and the count value t7 of the timer 136 is obtained. Is performed (S95).
[0046]
Then, by comparing the count value t6 with the count value t7, the rotation speeds of the suction roller 18 before and after the conveyance of the recording sheet are compared (S96). If the difference between the count value t6 and the count value t7 is not the predetermined value described later (NO in S96), the recording paper conveyance speed by the registration rollers 17 maintains the above-mentioned predetermined speed difference from the traveling speed of the transfer belt 8. The rotation speed of the registration motor 133 is corrected so that the speed becomes high (S97).
[0047]
That is, in a state where there is no recording paper between the suction roller 18 and the transfer belt 8, the suction roller 18 is driven to rotate by the transfer belt 8, and the count value t6 measured in this state is the traveling speed of the transfer belt 8. In a state where the recording paper exists between the suction roller 18 and the transfer belt 8, the suction roller 18 is driven to rotate by the recording paper. Therefore, the count value t7 measured in this state is This corresponds to the recording paper conveyance speed by the registration roller 17.
[0048]
Therefore, the difference between the count value t6 and the count value t7 represents the speed difference between the traveling speed of the transfer belt 8 and the recording paper conveyance speed by the registration roller 17, and the difference between the count value t6 and the count value t7. By adjusting the speed, the speed difference between the recording paper conveyance speed by the registration roller 17 and the traveling speed of the transfer belt 8 can be adjusted. Accordingly, the above-described predetermined speed difference between the recording paper transport speed by the registration rollers 17 and the traveling speed of the transfer belt 8 (the transport speed of the recording paper by the registration rollers 17 exceeds the traveling speed of the transfer belt 8 by about 0.2%) The value of the difference between the count value t6 and the count value t7 corresponding to the predetermined value is held as a predetermined value, and the difference between the actually measured count value t6 and the count value t7 is set to the predetermined value. By controlling the rotation speed of the registration motor 133, it is possible to obtain a state in which the recording paper conveyance speed by the registration rollers 17 is higher than the traveling speed of the transfer belt 8 while maintaining the above-described predetermined speed difference.
[0049]
For example, when the value obtained by subtracting the count value t6 from the count value t7 exceeds the above-described predetermined value, the rotation speed of the registration motor 133 is decreased, and the value obtained by subtracting the count value t6 from the count value t7 exceeds the above-mentioned predetermined value. If not, the rotation speed of the registration motor 133 is increased.
[0050]
If the difference between the count value t6 and the count value t7 is the above-described predetermined value (YES in S96), the process ends because there is no need to correct the rotation speed of the registration motor 133.
[0051]
Next, a process of warning the replacement of the registration roller 17 according to the rotation speed correction amount of the registration motor 133 will be described. FIG. 12 is a flowchart showing the processing. In the process (FIGS. 4, 9 and 11) for making the traveling speed of the transfer belt 8 and the recording paper transport speed by the registration rollers 17 substantially equal, the rotation speed of the registration motor 133 is controlled ( If YES in S101, the rotational speed correction amount r of the registration motor 133 (that is, the correction amount of the recording paper conveyance speed by the registration roller 17) is confirmed (S102).
[0052]
If the rotation speed correction amount r has reached a certain amount (for example, about + 1%) from the rotation speed initial value (preset fixed value) of the registration motor 133 (YES in S103), the registration roller 17 After a message prompting replacement is displayed on the display unit of the operation unit 127 (FIG. 2) (S105), the rotation speed of the registration motor 133 is corrected (S104). If the rotation speed correction amount r has not reached a predetermined amount from the rotation speed initial value of the registration motor 133 (the initial value of the recording paper conveyance speed by the registration roller 17) (NO in S103), a message prompting replacement of the registration roller 17 Is displayed, the rotation speed of the registration motor 133 is corrected (S104). When the rotation speed correction amount r reaches a certain amount from the rotation speed initial value of the registration motor 133 and a message prompting replacement of the registration roller 17 is displayed, the rotation speed of the registration motor 133 is not corrected. A process for inhibiting the image forming operation may be performed until the registration roller 17 is replaced.
[0053]
Next, a description will be given of a process of determining whether or not to adjust the speed of the transfer belt at the time of transfer of each color toner image and the speed of conveyance of the recording paper by the registration roller 17 in accordance with the surrounding environment. FIG. 13 is a flowchart showing the process. When the count value of the recording paper counter 143 is acquired (S111), and the count value has reached a predetermined value, for example, the total counter value becomes (1) every 5000 (sheets) count, (2) the time of the previous adjustment. At the time of counting from 1 to 1000 (sheets) (YES in S112), the adjustment of the traveling speed of the transfer belt 8 and the recording paper conveyance speed by the registration rollers 17 is executed (S115).
[0054]
Subsequently, the temperature and humidity are detected by the temperature / humidity sensor 145 (S113), and when the detected amount of change in temperature or humidity has reached a predetermined value, for example, the amount of change in temperature is about 8 times that of the previous correction. When the temperature has changed by ° C. or when the amount of change in humidity has changed by about 20% from the time of the previous correction (YES in S114), the adjustment of the traveling speed of the transfer belt 8 and the recording paper conveyance speed by the registration rollers 17 is executed. (S115). If neither the counter value (the number of recording paper conveyed sheets) nor the amount of change in temperature and humidity has reached each of the predetermined values (NO in S112, NO in S114), the traveling speed of the transfer belt 8 and the registration roller The process ends without the adjustment of the recording paper conveyance speed by 17.
[0055]
The timing for adjusting the recording paper transport speed is not limited to the case where the count by the recording paper counter 143 has reached a predetermined value, and may be the time when the power of the printer 1 is turned on.
[0056]
Next, an outline of speed adjustment between the traveling speed of the transfer belt 8 and the recording paper transport speed by the fixing roller pair 14 when the respective color toner images are transferred by the respective color photosensitive drums 4 will be described. FIG. 14 is a flowchart showing the speed adjustment processing. The speed adjustment is performed when the recording paper is conveyed from the transfer belt 8 to the nip portion of the fixing roller pair 14 by the traveling speed of the transfer belt 8 (recording paper conveyance speed by the transfer belt 8) and the recording paper conveyance by the fixing roller pair 14. This is performed to prevent fluctuations in the traveling speed of the transfer belt 8 (recording paper transport speed by the transfer belt 8) due to a speed difference from the speed.
[0057]
First, the traveling speed of the transfer belt 8 and the recording paper transport speed by the fixing roller pair 14 are detected (S121, S122), and the recording paper transport speed by the transfer belt 8 is a predetermined speed higher than the recording paper transport speed by the fixing roller pair 14. It is possible to maintain a relationship in which the speed is slightly increased while maintaining the difference (for example, in the experiment, the traveling speed of the transfer belt 8 is preferably about 0.2% higher than the recording paper conveyance speed by the fixing roller pair 14). Is determined (S123). Here, if the predetermined speed difference is not maintained (NO in S123), the fixing motor is moved so that the recording paper conveyance speed by the transfer belt 8 and the recording paper conveyance speed by the fixing roller pair 14 have the predetermined speed difference. 120 is corrected (S124). In other words, when the traveling speed of the transfer belt 8 (recording paper transport speed by the transfer belt 8) is a high speed having a speed difference exceeding the predetermined speed difference with respect to the recording paper transport speed by the fixing roller pair 14, The rotation speed of the fixing motor 120 is increased. If the traveling speed of the transfer belt 8 (recording paper conveyance speed by the transfer belt 8) is lower than the predetermined speed difference with respect to the recording paper conveyance speed by the fixing roller pair 14, the rotation of the fixing motor 120 is performed. Set a lower speed. If the above speed difference is maintained (YES in S123), the process ends because there is no need to correct the rotation speed of fixing motor 120. The detection of the traveling speed of the transfer belt 8 is performed in the same manner as in FIGS. The detection of the recording paper conveyance speed by the fixing roller pair 14 is performed as follows.
[0058]
FIG. 15 is a flowchart showing a process for detecting the recording paper conveyance speed by the fixing roller pair 14, and FIG. 16 is a schematic side view showing a fixing roller sensor disposed near the fixing roller pair 14. When the fixing roller sensor 140 detects the leading edge of the recording sheet (YES in S131), the timer 136 starts counting (S132). When the fixing roller sensor 140 detects the trailing edge of the recording sheet (YES in S133), the counting of the timer 136 is stopped (S134), and the count value t8 of the timer 136 is obtained (S135). Subsequently, the recording size information is obtained (S136), and the length of the recording paper being transported in the transport direction is confirmed. Then, the recording paper transport speed by the fixing roller pair 14 is calculated based on the timer count value t8 and the recording paper size information (the recording paper length in the transport direction) (S137).
[0059]
The determination as to whether or not to adjust the traveling speed of the transfer belt 8 and the recording paper conveyance speed by the fixing roller pair 14 may be made based on the same processing as the processing shown in FIG. Good.
[0060]
As described above, according to the printer 1, the driving of the registration motor 133 is controlled such that the recording paper conveyance speed by the registration roller 17 is slightly higher than the traveling speed of the transfer belt 8 while maintaining a predetermined speed difference. The difference between the traveling speed of the transfer belt 8 and the recording paper transport speed by the registration roller 17 is kept substantially constant, and when the recording paper is carried into the transfer belt 8 from the registration roller 17, the recording paper transport speed by the registration roller 17 is used. The fluctuation of the traveling speed of the transfer belt 8 due to the influence of the above is reduced. In addition, since the difference between the traveling speed of the transfer belt 8 and the speed at which the recording paper is conveyed by the registration rollers 17 is kept substantially constant, the transfer belt 8 and the registration rollers 17 Between the running speed of the transfer belt 8 and the speed of loading the recording paper by the registration rollers 17 to absorb the speed difference even if the amount of bending of the recording paper is small. Becomes possible. As a result, regardless of the distance between the transfer belt 8 and the registration roller 17 and the quality of the recording paper, the recording paper is conveyed by the transfer belt 8 to the photosensitive drums 4 of each color at a stable speed. Is prevented from being displaced during the superposition of the toner images of the respective colors.
[0061]
Note that the present invention is not limited to the configuration of the above embodiment, and various modifications are possible. For example, in the above-described embodiment, the speed adjustment between the traveling speed of the transfer belt 8 and the recording paper transport speed by the registration roller 17 at the time of transferring each color toner image, and the transport speed of the transfer belt 8 and the recording paper transport by the fixing roller pair 14 are performed. The speed adjustment with the speed is performed when the recording paper counter 143 reaches a predetermined value or when the amount of change in temperature and humidity in the printer 1 reaches a predetermined value. The process may be performed each time the color misregistration correction process is performed, or each time when the recording sheet is conveyed from the registration roller 17 to the transfer belt 8 when the image is formed.
[0062]
In addition, by controlling the driving of the registration motor 133 in the above-described embodiment so that the rotational speed difference of the suction roller 18 before and after the recording paper is carried into the transfer belt 8 and the suction roller 18 is eliminated, the transfer belt 8 In the process of adjusting the speed between the running speed and the recording paper transport speed by the registration roller 17 (FIG. 11), the rotation speed of the suction roller 18 is detected with the application of the suction roller bias and the transfer roller bias stopped. However, when the application of the suction roller bias and the transfer roller bias is reduced, or when the application of either the suction roller bias or the transfer roller bias is stopped, the rotation speed of the suction roller 18 is reduced. It may be detected.
[0063]
In the above embodiment, when the traveling speed of the transfer belt 8 at the time of transferring each color toner image and the speed of recording paper conveyance by the registration rollers 17 are adjusted, the rotation speed of the registration motor 133 is controlled. The recording paper conveyance speed by the registration roller 17 is set to be slightly higher than the traveling speed of the transfer belt 8 while maintaining a predetermined speed difference. However, by controlling the rotation speed of the transfer belt drive motor 125, the speed adjustment is performed. May be performed.
[0064]
In the above embodiment, when the traveling speed of the transfer belt 8 at the time of transferring each color toner image and the speed of recording paper conveyance by the fixing roller pair 14 are adjusted, the rotation speed of the fixing motor 120 is controlled. Although the traveling speed of the transfer belt 8 is set to be slightly higher than the recording paper conveyance speed of the fixing roller pair 14 while maintaining a predetermined speed difference, the rotation speed of the transfer belt drive motor 125 is controlled to control the speed. Speed adjustment may be performed.
[0065]
In addition, a guide member that suppresses the recording paper being conveyed from swaying up and down or left and right is provided at a position where the first sensor 135a and the second sensor 135b for detecting the leading and trailing ends of the recording paper are provided. The first sensor 135a and the second sensor 135b may be provided to regulate the posture of the recording sheet during conveyance so that the leading and trailing ends of the recording sheet are accurately detected.
[0066]
In the above embodiment, the driving of the registration motor 133 or the transfer belt drive motor 125 is controlled such that the recording paper conveyance speed by the registration roller 17 is slightly higher than the traveling speed of the transfer belt 8 while maintaining a predetermined speed difference. In this drive control, the time required for the recording paper conveyed by the registration roller 17 to move a predetermined distance and the time required for the transfer belt 8 to move a predetermined distance are determined. It also includes driving control of the registration motor 133 or the transfer belt drive motor 125 so as to have a time difference.
[0067]
In the above-described embodiment, the transfer belt driving motor 125 or the fixing motor 120 is controlled so that the traveling speed of the transfer belt 8 is slightly higher than the recording paper conveyance speed of the fixing roller pair 14 while maintaining a predetermined speed difference. The drive control is performed. The drive control includes a time required for the recording paper conveyed by the fixing roller pair 14 to move a fixed distance and a time required for the transfer belt 8 to move a fixed distance. Drive control of the fixing motor 120 or the transfer belt drive motor 125 such that the predetermined time difference is obtained.
[0068]
【The invention's effect】
As described above, according to the first aspect of the invention, the traveling speed of the transfer belt is controlled by controlling the difference between the traveling speed of the transfer belt and the conveyance speed of the recording paper by the registration roller to be substantially constant. Can be prevented from fluctuating under the influence of the recording paper carrying speed, and the positional deviation of each color toner image at the time of transfer of each color toner image can be prevented. If the speed reaches a certain amount from the initial set value, it is determined that it is time to replace the registration roller, so that it is possible to accurately detect that the performance of the registration roller has decreased due to aging. This makes it possible to reliably prevent the positional deviation of each color toner image during image transfer.
[0069]
According to the second aspect of the present invention, when the control unit determines that it is time to replace the registration roller, the warning unit warns the user of the replacement of the registration roller. Can be surely recognized.
[0070]
According to the third aspect of the present invention, when the amount of change in temperature or humidity in the apparatus reaches a predetermined value, the driving of the registration roller driving unit or the transfer belt driving unit is controlled to move the transfer belt. Since the speed and the transport speed of the recording paper are adjusted, the transfer belt can be accurately detected by detecting when the performance of the registration roller, such as the size of the registration roller, is likely to change due to changes in the temperature or humidity inside the device. Speed and the recording paper conveyance speed by the registration roller can be adjusted.
[0071]
According to the present invention, when the number of recording sheets conveyed to the transfer belt by the registration roller reaches a predetermined value, the drive control of the registration roller driving unit or the transfer belt driving unit is performed. It is possible to accurately predict the endurance period of the registration roller and accurately adjust the traveling speed of the transfer belt and the recording paper transport speed by the registration roller before the diameter of the registration roller changes due to wear or the like. it can.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an example of a schematic configuration of an image forming apparatus according to the present invention.
FIG. 2 is a block diagram illustrating an example of a schematic configuration of an image forming apparatus according to the present invention.
FIG. 3 is a flowchart of a speed adjustment process of a transfer belt traveling speed at the time of transferring each color toner image and a recording paper conveyance speed by a registration roller.
FIG. 4 is a flowchart of a process for detecting a traveling speed of the transfer belt in speed adjustment of a traveling speed of the transfer belt and a recording paper conveyance speed by a registration roller.
FIG. 5 is a diagram illustrating how registration marks are formed on the transfer belt when the transfer belt traveling speed is detected.
FIG. 6 is a flowchart illustrating another example of a process of detecting a transfer belt traveling speed.
FIG. 7 is a flowchart illustrating still another example of a process of detecting a transfer belt traveling speed.
FIG. 8 is a flowchart illustrating a process of detecting a transport speed of a recording sheet by a registration roller in speed adjustment of a transfer belt traveling speed and a recording paper transport speed by a registration roller.
FIG. 9 is a flowchart illustrating another example of the speed adjustment processing of the traveling speed of the transfer belt and the recording paper conveyance speed by the registration rollers during the transfer of each color toner image.
FIG. 10 is a schematic side view showing a first sensor and a second sensor disposed between a transfer belt and a registration roller.
FIG. 11 is a flowchart illustrating still another example of the speed adjustment processing of the traveling speed of the transfer belt and the recording paper conveyance speed by the registration rollers when transferring the toner images of each color.
FIG. 12 is a flowchart illustrating a process for warning a replacement of a registration roller in accordance with a rotation speed correction amount of a registration motor.
FIG. 13 is a flowchart showing a process for determining whether or not to adjust the speed of the transfer belt at the time of transfer of each color toner image and the speed of conveyance of the recording paper by the registration roller in accordance with the surrounding environment.
FIG. 14 is a flowchart of a speed adjustment process of a traveling speed of a transfer belt and a recording paper transport speed by a pair of fixing rollers when transferring a toner image of each color.
FIG. 15 is a flowchart illustrating a process of detecting a recording paper conveyance speed by a fixing roller pair in speed adjustment between a traveling speed of a transfer belt and a recording paper conveyance speed by a fixing roller pair.
FIG. 16 is a schematic side view showing a fixing roller sensor disposed near a fixing roller pair.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 printer 4 photoreceptor drum 8 transfer belt 9 transfer roller 24 driven roller 14 fixing roller pair 17 registration roller 18 suction rollers 20B, 20Y, 20M, 20C image forming unit 110 control unit 114 transfer bias unit 120 fixing motor 120a driver 123 registration motor 125 Transfer belt drive motor 125a Driver 126 Suction roller bias unit 127 Operation unit 133 Registration motor 133a Driver 135a First sensor 135b Second sensor 136 Timer 137 Registration sensor 140 Fixing roller sensor 141 Suction roller sensor 142 Suction roller mark sensor 143 Recording paper counter 145 temperature and humidity sensor 146 driven roller sensor

Claims (4)

An image forming apparatus that conveys the recording paper conveyed by the registration rollers to an image carrier provided for each color by a transfer belt and transfers the toner image on each image carrier onto the recording paper to form an image. So,
Transfer belt driving means for running the transfer belt,
Registration roller driving means for rotationally driving the registration roller,
Transfer belt speed detection means for detecting the traveling speed of the transfer belt,
Conveying speed detecting means for detecting a conveying speed of the recording paper conveyed from the registration roller to the transfer belt,
The registration roller drive is performed such that the conveyance speed of the recording paper detected by the conveyance speed detection unit is faster than the traveling speed of the transfer belt detected by the transfer belt speed detection unit while maintaining a predetermined speed difference. Control means for driving and controlling at least one of the means or the transfer belt driving means,
The control unit determines that it is time to replace the registration roller when the correction amount of the registration roller driving unit or the transfer belt driving unit reaches a certain amount from an initial setting value of the recording paper conveyance speed. An image forming apparatus, comprising: 2. The image forming apparatus according to claim 1, further comprising a warning unit that warns the user to replace the registration roller when the control unit determines that it is time to replace the registration roller. An image forming apparatus that conveys the recording paper conveyed by the registration rollers to an image carrier provided for each color by a transfer belt and transfers the toner image on each image carrier onto the recording paper to form an image. So,
Transfer belt driving means for running the transfer belt,
Registration roller driving means for rotationally driving the registration roller,
Transfer belt speed detection means for detecting the traveling speed of the transfer belt,
Conveying speed detecting means for detecting a conveying speed of the recording paper conveyed from the registration roller to the transfer belt,
The registration roller drive is performed such that the conveyance speed of the recording paper detected by the conveyance speed detection unit is faster than the traveling speed of the transfer belt detected by the transfer belt speed detection unit while maintaining a predetermined speed difference. Temperature and humidity detecting means for detecting the temperature or humidity in the apparatus and a control means for driving and controlling at least one of the means or the transfer belt driving means,
The control means performs drive control of the registration roller driving means or the transfer belt driving means when a change in temperature or humidity detected by the temperature and humidity detection means reaches a predetermined value. Image forming device. An image forming apparatus that conveys the recording paper conveyed by the registration rollers to an image carrier provided for each color by a transfer belt and transfers the toner image on each image carrier onto the recording paper to form an image. So,
Transfer belt driving means for running the transfer belt,
Registration roller driving means for rotationally driving the registration roller,
Transfer belt speed detection means for detecting the traveling speed of the transfer belt,
Conveying speed detecting means for detecting a conveying speed of the recording paper conveyed from the registration roller to the transfer belt,
The registration roller drive is performed such that the conveyance speed of the recording paper detected by the conveyance speed detection unit is faster than the traveling speed of the transfer belt detected by the transfer belt speed detection unit while maintaining a predetermined speed difference. Control means for controlling driving of at least one of the means or the transfer belt driving means, and a recording sheet conveyance number detection means for detecting the number of recording sheets conveyed to the transfer belt by the registration roller,
The controller controls the driving of the registration roller driving unit or the transfer belt driving unit when the number of recording papers detected by the recording paper conveyance number detecting unit reaches a predetermined value. Image forming device.

Images