US-12625446-B2 - Image forming apparatus controlling conveyance speed

US12625446B2US 12625446 B2US12625446 B2US 12625446B2US-12625446-B2

Abstract

An image forming apparatus may include a conveyor conveying continuous paper. The apparatus may also include a speed detector that contacts the continuous paper conveyed by the conveyor to detect a conveyance speed of the continuous paper. The apparatus may also include a hardware processor that controls the conveyor based on a detection result detected by the speed detector so that the conveyance speed of the continuous paper reaches a target value. The hardware processor may adjust the target value based on at least one of information about the continuous paper and information about a job.

Inventors

Nobuhiko Okano

Assignees

Konica Minolta, Inc.

Dates

Publication Date: 20260512
Application Date: 20231109
Priority Date: 20221114

Claims (14)

1 . An image forming apparatus comprising: a conveyor that conveys continuous paper, a speed detector that contacts the continuous paper conveyed by the conveyor to detect a conveyance speed of the continuous paper, and a hardware processor that controls the conveyor based on a detection result detected by the speed detector so that the conveyance speed of the continuous paper reaches a target value, wherein the hardware processor adjusts the target value based on at least one of information about the continuous paper and information about a job; wherein the conveyor conveys the continuous paper at the adjusted target value.
2 . The image forming apparatus according to claim 1 , wherein the hardware processor is capable of setting the conveyance speed of the continuous paper to be higher than 23.4 m/min.
3 . The image forming apparatus of claim 1 , wherein after the hardware processor adjusts the target value, image forming occurs.
4 . The image forming apparatus according to claim 1 , wherein either of the information about the continuous paper or the information about the job includes any one of a paper type of the continuous paper, a thickness of the continuous paper, a basis weight of the continuous paper, and potential for slippage of the continuous paper.
5 . The image forming apparatus according to claim 4 , wherein the hardware processor adjusts the target value such that the target value decreases gradually or stepwise as the thickness of the continuous paper increases.
6 . The image forming apparatus according to claim 4 , further comprising a transfer device that transfers a toner image carried on an image carrier to the continuous paper, wherein the potential for slippage is potential for slippage of the continuous paper at a transfer position where the transfer device meets the image carrier.
7 . The image forming apparatus according to claim 6 , wherein the potential for slippage is a friction coefficient of a surface of the continuous paper on the image carrier.
8 . The image forming apparatus according to claim 7 , wherein the hardware processor adjusts the target value such that the target value when the friction coefficient is larger than a first threshold value is lower than the target value when the friction coefficient is equal to or smaller than the first threshold value.
9 . The image forming apparatus according to claim 8 , further comprising a driver that drives the image carrier, wherein the hardware processor determines whether the friction coefficient is larger than the first threshold or not based on a driving torque of the driver when the continuous paper is pressed on the image carrier to be conveyed.
10 . The image forming apparatus according to claim 6 , wherein the hardware processor adjusts the target value based on the potential for slippage which is based on a coverage of an image formed on the continuous paper.
11 . The image forming apparatus according to claim 10 , wherein the hardware processor adjusts the target value such that the target value when the coverage is equal to or smaller than a second threshold is higher than the target value when the coverage is larger than the second threshold value.
12 . The image forming apparatus according to claim 11 , further comprising a coverage detector that detects the coverage during an image forming job, wherein the hardware processor adjusts the target value based on the coverage detected by the coverage detector.
13 . The image forming apparatus according to claim 6 , wherein the transfer device includes a transfer member that presses the continuous paper on the image carrier, wherein the hardware processor adjusts the target value such that the target value when a pressing force by the transfer member is smaller than a third threshold value is lower than the target value when the pressing force is equal to or larger than the third threshold value.
14 . The image forming apparatus according to claim 13 , further comprising a driver that drives the image carrier, wherein the hardware processor determines whether the pressing force is smaller than the third threshold or not based on a driving torque of the driver when the continuous paper is pressed on the image carrier to be conveyed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Japanese Patent Application No. 2022-181476 filed on Nov. 14, 2022, the entire disclosure of which is incorporated herein by reference. BACKGROUND Technical Field The present disclosure relates to the image forming apparatus and recording medium. Description of the Related Art The image forming apparatus according to electrophotographic process executes a print job for printing toner images on conveyed paper. The printing is performed as follows. That is, a toner image is formed on an image carrier such as a rotating photoreceptor or an intermediate transfer belt. Then, the toner image on the image carrier is transferred onto paper passing between the image carrier and the transfer member opposite thereto at a transfer position on the image carrier. Then, the paper after the transfer is conveyed while being nipped by a pair of fixing members which are disposed so as to face each other at a fixing position in a fixer, for example, a fixing roller on a driving side and a pressing roller on a driven side, and thus the toner image on the paper is heated and pressurized to be fixed on the paper. When a toner image is printed on continuous paper in an image forming apparatus as described above, the paper is loosened between the transfer position and the fixer if a conveyance speed of the paper is low to a surface speed of the image carrier. As a result, a defect such as a fixing wrinkle occurs. On the other hand, if the conveyance speed of paper is too high to the surface speed of the image carrier, a defect such as a transfer deviation or a color shift (deterioration in color resist performance) occurs when the toner image is transferred onto the paper. With respect to this issue, JP 4696626 A and JP 2017-009651 A describe control such that a conveyance speed of paper is increased by a predetermined value to a surface speed of an image carrier. Further, JP-A-2020-122859 describes that speed variation due to a fixing roller is corrected and a conveyance speed of paper is controlled to be constant. SUMMARY However, a surface speed of an image carrier and a conveyance speed of paper may differ by more than a predetermined value due to component variations in components related to control of the surface speed of the image carrier and the conveyance speed of the paper (for example, an outer diameter of a drive roller of a transfer member or the image carrier, and a thickness of the image carrier or the transfer member). As an example, a variation of an outer diameter of a speed detection roller 381 that detects a conveyance speed of paper P as shown in FIG. 3 will be described. The paper P is conveyed while being wound around a speed detection roller 381. At this time, the speed detection roller 381 rotates following the conveyance of the paper P, and the conveyance speed of the paper P is detected based on the rotation speed of the rotation following the conveyance of the paper P. Here, if there is a variation in the outer diameter of the speed detection roller 381, an error corresponding to the difference in the outer diameter also occurs in the speed detected by the speed detection roller 381. In addition, when a thickness T of the paper P is relatively large, an error occurs in the speed detected by the speed detection roller 381. This is because, as shown in FIG. 3, when the thickness T of the paper P is relatively thick, a difference between a conveyance speed V2 of the paper P detected by the speed detection roller 381 and a conveyance speed V1 (actual speed) at the speed center line of the paper P is relatively large. Here, the conveyance speed V2 of the paper P detected by the speed detection roller 381 is lower than the conveyance speed V1 (actual speed) at the speed center line of the paper P. The conveyance speed of the paper in the image forming apparatus is controlled based on the speed detected by the speed detection roller 381. Therefore, if an error occurs in the speed detected by the speed detection roller 381, there is a possibility that the conveyance speed of the paper is not controlled at an appropriate speed. Therefore, a difference of a predetermined value or more occurs between the surface speed of the image carrier and the conveyance speed of the paper, and a defect such as a fixing wrinkle or a transfer misalignment may occur. In U.S. Pat. No. 4,696,626, JP 2017-009651 and JP 2020-122859, the above problem is not considered. An object of the present disclosure is to provide an image forming apparatus capable of suppressing a defect due to paper conveyance. To achieve at least one of the abovementioned objects, according to an aspect of the present invention, an image forming apparatus reflecting one aspect of the present invention includes: a conveyor that conveys continuous paper, a speed detector that contacts the continuous paper conveyed by the conveyor to detect a conveyance speed of the continuous paper, and a