JP2005096910A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain suitable printing performance responding to the change of the transfer speed of a paper sheet caused by various factors without causing a defect in print image. <P>SOLUTION: The image forming device 1 is equipped with a resist roller drive means 23 rotating a resist roller 22. A carrying roller 21, a photoreceptor drum 41, a transfer roller 51 and a fixing roller 61 are respectively rotated with the drive means not shown in the figure, but the resist roller 22 is independently rotated from these rollers with the resist roller drive means 23. The image forming device is equipped with a paper size detection means 13 for the paper sheet P used in printing, a toner occupancy ratio means 31 detecting the toner occupancy ratio of a document image, and fixing roller temperature detection means 64. The image forming device is a control means 100 controlling the peripheral speed of the resist roller 22 by receiving information from these means or based on an accumulated drive time of the resist roller 22. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus represented by a copying machine, a printer, and the like.

  An image forming apparatus represented by a copying machine, a printer, or the like includes an image carrier, a registration roller that conveys paper in synchronization with toner image formation on the image carrier, a transfer roller that transfers a toner image to paper, Many roller-like rotating members such as a fixing roller for fixing an unfixed toner image on a sheet and a conveying roller arranged at a key point are arranged. Normally, these roller groups are controlled by a single driving device so that the paper transport speed is constant at any location.

The paper used for printing does not always have a constant physical property. In particular, the friction coefficient of the paper may change due to the influence of temperature and humidity, and the conveyance speed by the roller group may change. Further, the paper is wavy due to moisture absorption, and a toner image transfer failure occurs. Further, in the paper conveyance using the conveyance belt, the electrostatic adsorption force of the conveyance belt is reduced due to the influence of humidity, and there is a possibility that the paper is displaced. In order to solve such a problem, Patent Documents 1 to 3 propose a method of changing the sheet conveyance speed in consideration of the influence of temperature and humidity.
JP 11-125981 A (second page, FIG. 3) Japanese Patent Laid-Open No. 2002-244523 (second page, FIG. 3) Japanese Patent Laying-Open No. 2001-310865 (second page, FIG. 20)

  The sheet conveyance speed is not affected only by the temperature and humidity of the environment in which the image forming apparatus is used, and the sheet conveyance speed varies depending on various factors. For example, the roller slips due to dust generated from the paper, wear of a roller that transports the paper, toner occupancy of an image printed on the paper surface, and the paper transport speed may be slow. Further, the peripheral speed of the fixing roller is increased due to the thermal expansion of the fixing roller, and the sheet conveyance speed in the fixing unit may be increased. Changes in the paper transport speed are the same magnification failure where the image printed on the paper expands and contracts in the paper transport direction, the middle portion where the image in the center of the paper is white, the transfer displacement that causes the image to shift, Causes problems such as wrinkling.

  The present invention has been made in view of the above points, and is suitable not only for the influence of temperature and humidity but also for the change in the conveyance speed of the paper caused by various factors without causing defects in the printed image. An object of the present invention is to provide a high-performance image forming apparatus capable of obtaining a high printing performance.

  In order to solve the above-described problems, the present invention provides an image carrier, a registration roller that conveys paper in synchronization with toner image formation on the image carrier, a transfer roller that transfers a toner image to paper, In an image forming apparatus including a fixing roller for fixing a toner image on a sheet and a conveyance roller arranged at a key point, the registration roller is defined as the image carrier, the transfer roller, the fixing roller, and the conveyance roller. A drive unit that is driven independently and a control unit that controls the drive unit are provided, and the control unit controls the peripheral speed of the registration roller based on the cumulative driving time of the registration roller.

  Also, an image carrier, a registration roller that conveys the paper in synchronization with toner image formation on the image carrier, a transfer roller that transfers the toner image to the paper, and a fixing roller that fixes the unfixed toner image on the paper And a driving means for driving the registration roller independently of the image carrier, the transfer roller, the fixing roller, and the conveyance roller, and an original document. A toner occupancy rate detection unit that detects the toner occupancy rate of the image and a control unit that controls these units are provided, and the control unit controls the peripheral speed of the registration roller based on the toner occupancy rate.

  Also, an image carrier, a registration roller that conveys the paper in synchronization with toner image formation on the image carrier, a transfer roller that transfers the toner image to the paper, and a fixing roller that fixes the unfixed toner image on the paper And a driving means for driving the registration roller independently of the image carrier, the transfer roller, the fixing roller, and the transporting roller, and a fixing device. A temperature detecting means for detecting the temperature of the roller and a control means for controlling these means are provided, and the control means controls the peripheral speed of the registration roller based on the temperature of the fixing roller.

  Also, an image carrier, a registration roller that conveys the paper in synchronization with toner image formation on the image carrier, a transfer roller that transfers the toner image to the paper, and a fixing roller that fixes the unfixed toner image on the paper An image forming apparatus including a conveying roller disposed at a key point, a driving unit that drives the registration roller independently of the image carrier, the transfer roller, the fixing roller, and the conveying roller, and printing. The paper size detecting means for detecting the size of the paper used for the printing and the control means for controlling these means are provided, and the control means controls the peripheral speed of the registration roller based on the paper size.

  According to the configuration of the present invention, in the image forming apparatus, the driving unit that drives the registration roller independently of the image carrier, the transfer roller, the fixing roller, and the conveying roller, and the control unit that controls the driving unit, Therefore, in the process of transferring and fixing the toner image onto the paper, it is possible to directly control the driving of the registration roller, which is an important factor for determining the paper conveyance speed. Therefore, by finely adjusting the peripheral speed of the registration roller, it is possible to cope with a change in the sheet conveyance speed caused by various factors.

  Since the control means controls the peripheral speed of the registration roller based on the cumulative driving time of the registration roller, the dust generated from the paper accumulates on the registration roller as the cumulative driving time becomes longer. Thus, it is possible to cope with a change in the conveyance speed of the paper due to wear of the rollers. Therefore, even if the cumulative driving time is increased, it is possible to obtain a suitable printing performance without the paper conveyance speed being affected by the above-described problems.

  In addition, since the toner occupancy rate detecting unit for detecting the toner occupancy rate of the document image is provided, and the control unit controls the peripheral speed of the registration roller based on the toner occupancy rate, the toner occupancy rate of the sheet is increased. As the height increases, it is possible to cope with a decrease in the sheet conveyance speed caused by the transfer roller becoming slippery. Therefore, even when the toner occupancy ratio of the paper becomes high, it is possible to increase the paper conveyance speed and obtain a suitable printing performance.

  Further, since the temperature detecting means for detecting the temperature of the fixing roller is provided, and the control means controls the peripheral speed of the registration roller based on the temperature of the fixing roller, the temperature of the fixing roller is increased. This can cope with the thermal expansion of the fixing roller and the peripheral speed of the fixing roller becoming faster than the peripheral speed of the registration roller. Accordingly, it is possible to prevent a difference from the peripheral speed of the registration roller due to an increase in the peripheral speed of the fixing roller, and to obtain suitable printing performance.

  Since the registration roller is supported at both ends, the central portion may be bent. The present invention includes paper size detection means for detecting the size of the paper used for printing, and the control means controls the peripheral speed of the registration roller based on the paper size. Even if the conveyance performance of a small-size sheet is reduced due to the deflection of the sheet, this can be dealt with. Therefore, even if a small-size sheet is used for printing, it is possible to increase the sheet conveyance speed and obtain suitable printing performance.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. First, the image output operation of the image forming apparatus of the present invention will be described while explaining the outline of the structure with reference to FIG. FIG. 1 is a schematic vertical sectional view showing an image forming apparatus according to an embodiment of the present invention.

  In FIG. 1, the image forming apparatus 1 includes a paper feed unit 10, a paper transport unit 20, an optical unit 30, an image forming unit 40, a transfer unit 50, a fixing unit 60, and a discharge / reverse unit 70. It is provided. A solid line arrow in the figure indicates a sheet conveyance path, and a one-dot chain line arrow L indicates a laser beam.

  Sheets such as cut paper before printing are stacked and stored in the sheet feeding device 10, and the sheets are separated from each other and sent out. The fed sheet is conveyed vertically along the side surface of the main body of the image forming apparatus 1 by the sheet conveying unit 20 and reaches the transfer unit 50.

  Image data such as characters, figures, and patterns drawn on a document is read by the optical unit 30 and irradiated with a laser beam L controlled based on the image data. An electrostatic latent image is created. A toner image is formed from the electrostatic latent image, and the toner image is transferred by the transfer unit 50 to the pre-printed paper sent in synchronization by the paper transport unit 20.

  Thereafter, the sheet carrying the unfixed toner image is sent to the fixing unit 60, and the toner image is fixed by the fixing roller. The sheet discharged from the fixing unit 60 is discharged from the discharge / reversing unit 70 to a sheet receiving tray provided in the cylinder of the image forming apparatus 1. When duplex printing is performed, the sheet discharged from the fixing unit 70 is switched to the sheet feeding direction by the discharge / reversing unit 70 and is sent to the transfer unit 50 again.

  Next, a detailed configuration of a portion from the paper feeding unit 10 to the fixing unit 60 of the image forming apparatus 1 will be described with reference to FIGS. 2 is a schematic vertical sectional view showing a schematic structure of a portion from a paper feeding unit to a fixing unit, and a schematic diagram of a control circuit. FIG. 3 is a table showing a correction amount of a printing paper conveyance speed with respect to a toner occupation ratio of a document. Is a table showing the sheet conveyance speed correction amount with respect to the sheet width of the printing sheet.

  The paper supply unit 10 is provided with a tray 11 on which sheets are stacked. The tray 11 is configured by a flat box having an open upper surface, and stacks and stores sheets P before printing from the upper surface direction.

  A cursor 12 is provided on the bottom surface in the tray 11. The cursor 12 is a side wall that contacts the side surface of the sheet bundle, and moves along a movement groove (not shown) provided on the tray 11 in accordance with the sheet width in a direction perpendicular to the sheet supply direction. It is possible to make it. The cursor 12 regulates the movement of the paper P in the width direction so that the paper P stacked on the tray 11 remains at a predetermined position.

  In addition, the tray 11 is provided with a paper size detecting means 13. The paper size detection means 13 includes an optical sensor (not shown). The optical sensor is composed of a photo interrupter or the like, and is arranged at a position on the tray 11 corresponding to the paper width of a predetermined paper size. This optical sensor detects the position of the cursor 12 moving in the paper width direction and identifies the paper size.

  Further, a lift plate 14 is provided on the bottom surface in the tray 11, and the paper P is stacked on the lift plate 14. The lift plate 14 is rotatably connected to the tray 11 with an upstream end in the paper supply direction (see FIG. 1). Then, the downstream end of the lift plate 14 in the paper supply direction is lifted by the force of the spring 15 which is an urging means provided between the tray 11 and the lift plate 14. Thereby, the upper surface of the uppermost layer of the paper P comes into contact with a forward feed roller 17 of the paper feeding device 16 described later.

  The paper feeding device 16 is disposed above the downstream portion of the tray 11 in the paper supply direction. The paper feed mechanism 16 includes a forward feed roller 17, a paper feed roller 18, and a separation roller 19. As described above, one end of the downstream end of the tray 11 in the sheet supply direction is lifted, so that the uppermost sheet P of the sheets P stacked on the tray 11 comes into contact with the forward feed roller 17. Then, the paper feed P is sent to the paper feed roller 18 and sent to the outside of the paper feed unit 1 by rotating the forward feed roller 17 by a driving means including a motor (not shown). The separation roller 19 is used to prevent the problem of double feeding that the sheets P are overlapped and fed.

  The paper transport unit 20 includes a transport roller 21 and a registration roller 22. The conveyance roller 21 and the registration roller 22 are configured by a pair of rollers that are in contact with each other. The transport roller 21 is rotated by a driving unit configured by a motor or the like (not shown), and transports the paper P fed by the paper feeding device 16 of the paper feeding unit 10 toward the registration roller 22. The registration roller 22 sends out the paper P in synchronism with the toner image formation toward the transfer unit 50 that transfers the toner image onto the paper P. The conveying roller 21, the photosensitive drum 41, which is an image carrier, which will be described later, the transfer roller 51, and the fixing roller 61 are rotated by a common driving unit (not shown), but the registration roller 22 is independent of these rollers. And rotated by the registration roller driving means 23.

  The image forming unit 40 is provided with a photosensitive drum 41 as an image carrier, and a main charging device 42, a developing device 43, and a cleaning device 44 are arranged in order along the rotation direction of the photosensitive drum 41. Has been.

  The photosensitive drum 41 is rotated by a driving unit (not shown) so that the peripheral speed thereof is the same as the paper conveyance speed. The surface of the photosensitive drum 41 is uniformly charged with a predetermined polarity and potential by the main charging device 42.

  The developing device 43 is provided with a developing roller 43 a that contacts the photosensitive drum 41. A bias having the same polarity as the charging polarity of the photosensitive drum 41 is applied to the developing roller 43a. The developing roller 43a charges the toner, which is a developer, and supplies the toner to the surface of the photosensitive drum 41 to develop the electrostatic latent image. After the toner image is transferred to the paper P, the cleaning device 44 scrapes and collects the toner remaining on the surface of the photosensitive drum 41.

  The transfer unit 50 is provided with a transfer roller 51 as a transfer member. The transfer roller 51 is in contact with the photosensitive drum 41 to form a transfer nip through which the paper P is inserted. The transfer roller 51 is rotated by a driving unit (not shown) so that the peripheral speed thereof is the same as the peripheral speed of the photosensitive drum 41. Further, a transfer bias and a cleaning bias are applied to the transfer roller 51 as necessary.

  The fixing unit 60 includes a fixing roller 61. The fixing roller 61 is rotated by a driving unit (not shown) so that the peripheral speed thereof is the same as the paper transport speed. Inside the fixing roller 61, a halogen heater 62 as a heat source is disposed. The pressure roller 63 is in contact with the fixing roller 61 to form a nip through which the paper P is inserted. The pressure roller 63 is rotated in accordance with the rotation of the fixing roller 61 by contacting the fixing roller 61. Further, a fixing roller temperature detecting means 64 for detecting the surface temperature of the fixing roller 61 is provided.

  Further, the image forming apparatus 1 includes a control unit 100. The control unit 100 controls the driving unit such as the photosensitive drum 41 and the registration roller driving unit 23 based on a preset sheet conveyance speed. In addition, the control unit 100 receives information from the paper size detection unit 13, the toner occupancy rate detection unit 31, and the fixing roller temperature detection unit 64, and controls the registration roller driving unit 23 to control the circumference of the registration roller 22. Change the speed.

  The control unit 100 is provided with a toner occupancy rate detection unit 31. The toner occupancy rate detection means 31 calculates the ratio of the toner amount occupying the paper in the original image read by the optical unit 30. Further, the control means 100 is provided with a storage device (not shown) that stores the cumulative driving time of the registration rollers 23.

  In this manner, the driving means 23 for driving the registration roller 22 independently of the photosensitive drum 41, the transfer roller 51, the fixing roller 61, and the conveying roller 21, which are image carriers, and the driving means are controlled. In the process of transferring and fixing the toner image onto the paper P, it is possible to directly control the driving of the registration roller 22 which is an important factor for determining the transport speed of the paper P. . Therefore, by finely adjusting the peripheral speed of the registration roller 22, it is possible to cope with a change in the conveyance speed of the paper P caused by various factors.

  Next, a driving method corresponding to a change in the use environment of the image forming apparatus 1 as described above will be described.

  When the cumulative driving time of the registration roller 22 reaches a predetermined time, the control unit 100 increases the peripheral speed of the registration roller 22. As an example of the peripheral speed increasing method, when the cumulative driving time reaches 200 hours, the peripheral speed of the registration roller 22 is increased by 0.25%. As a result, as the cumulative driving time becomes longer, it is possible to cope with the change in the conveyance speed of the paper P caused by the dust generated from the paper P being accumulated on the registration roller 22 or the registration roller 22 being worn. it can. Therefore, even if the cumulative driving time is increased, it is possible to obtain a suitable printing performance without the conveyance speed of the paper P being affected by the above-described problems.

  The toner occupancy ratio of the original image to the paper corresponds as shown in the table of FIG. That is, when the toner occupancy rate of the original image detected by the toner occupancy rate detection unit 31 is 0 to 30%, the control unit 100 sets the conveyance speed of the printing paper to the toner occupancy rate of 30 to 60% as initially set. In this case, the conveyance speed is increased by 0.25%, and when the toner occupation ratio is 60% or more, the conveyance speed is increased by 0.50%. Accordingly, it is possible to cope with a decrease in the conveyance speed of the paper P caused by the transfer roller 51 being easily slipped as the toner occupation ratio of the printing paper P increases. Therefore, even when the toner occupancy of the paper P becomes high, it is possible to increase the conveyance speed of the paper P and obtain suitable printing performance.

  When the surface temperature of the fixing roller 61 detected by the fixing roller temperature detecting unit 64 reaches a predetermined temperature, the control unit 100 increases the peripheral speed of the registration roller 22. As an example of the peripheral speed increasing method, when the surface temperature of the fixing roller 61 reaches 200 ° C., the peripheral speed of the registration roller 22 is increased by 0.25%. Accordingly, it is possible to cope with the fact that the fixing roller 61 is thermally expanded as the fixing roller 61 becomes high temperature, and the peripheral speed of the fixing roller 61 becomes higher than the peripheral speed of the registration roller 22. Accordingly, it is possible to prevent a difference from the peripheral speed of the registration roller 22 due to an increase in the peripheral speed of the fixing roller 61 and to obtain a suitable printing performance.

  The size of the paper P used for printing corresponds as shown in the table of FIG. That is, the control means 100 increases the paper conveyance speed by 0.50% when the width of the paper P detected by the paper size detection means 13 is equal to or shorter than the A5 short side, and the width of the paper P is B5 short side to A4 short side. In this case, the speed is increased by 0.25%, and when the width of the paper P is shorter than the B4 short side, the speed is set as the initial setting. Thereby, even if the conveyance performance of the small-size paper P is deteriorated due to the deflection of the central portion of the registration roller 22, this can be dealt with. Therefore, even if a small-size paper P is used for printing, it is possible to increase the conveyance speed of the paper P and obtain a suitable printing performance.

  As in this embodiment, if the registration roller 22 is configured to be rotated independently from the rollers of the conveyance roller 21, the photosensitive drum 41, the transfer roller 51, and the fixing roller 61, the conveyance roller 21. Even if the driving means for rotating the photosensitive drum 41, the transfer roller 51, and the fixing roller 61 are not common, the same operation and effect as described above can be obtained.

  Although the embodiment of the present invention has been described above, various modifications can be made without departing from the spirit of the present invention.

  The present invention can be used in all apparatuses for conveying articles such as paper.

1 is a schematic vertical sectional view showing an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic vertical sectional view and a schematic diagram of a control circuit showing a schematic structure of a portion from a paper feeding unit to a fixing unit of the image forming apparatus shown in FIG. 1. FIG. 4 is a table showing print sheet conveyance speed correction amounts with respect to the toner occupancy rate of a document. 4 is a table showing the sheet conveyance speed correction amount with respect to the sheet width of the printing sheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Paper feed part 12 Cursor 13 Paper size detection means 20 Paper conveyance part 21 Conveyance roller 22 Registration roller 23 Registration roller drive means 30 Optical part 31 Toner occupation rate detection means 40 Image formation part 41 Photosensitive drum (image carrier) body)
DESCRIPTION OF SYMBOLS 50 Transfer part 51 Transfer roller 60 Fixing part 61 Fixing roller 64 Fixing roller temperature detection means 100 Control means

Claims (4)

An image carrier, a registration roller that conveys the paper in synchronism with toner image formation on the image carrier, a transfer roller that transfers the toner image to the paper, a fixing roller that fixes the unfixed toner image on the paper, In an image forming apparatus provided with conveyance rollers arranged at important points,
Drive means for driving the registration roller independently of the image carrier, transfer roller, fixing roller, and transport roller, and control means for controlling the drive means, the control means for accumulating registration rollers An image forming apparatus that controls a peripheral speed of a registration roller based on a driving time. An image carrier, a registration roller that conveys the paper in synchronism with toner image formation on the image carrier, a transfer roller that transfers the toner image to the paper, a fixing roller that fixes the unfixed toner image on the paper, In an image forming apparatus provided with conveyance rollers arranged at important points,
A driving unit that drives the registration roller independently of the image carrier, the transfer roller, the fixing roller, and the conveyance roller; a toner occupancy rate detection unit that detects a toner occupancy rate of a document image; and An image forming apparatus comprising: a control unit that controls the peripheral speed of the registration roller based on a toner occupancy rate. An image carrier, a registration roller that conveys the paper in synchronism with toner image formation on the image carrier, a transfer roller that transfers the toner image to the paper, a fixing roller that fixes the unfixed toner image on the paper, In an image forming apparatus provided with conveyance rollers arranged at important points,
Driving means for driving the registration roller independently of the image carrier, transfer roller, fixing roller, and conveying roller, temperature detecting means for detecting the temperature of the fixing roller, and control means for controlling these means And the control means controls the peripheral speed of the registration roller based on the temperature of the fixing roller. An image carrier, a registration roller that conveys the paper in synchronism with toner image formation on the image carrier, a transfer roller that transfers the toner image to the paper, a fixing roller that fixes the unfixed toner image on the paper, In an image forming apparatus provided with conveyance rollers arranged at important points,
A driving unit that drives the registration roller independently of the image carrier, the transfer roller, the fixing roller, and the conveying roller; a sheet size detecting unit that detects a size of a sheet used for printing; and these units An image forming apparatus comprising: a control unit configured to control the peripheral speed of the registration roller based on a paper size;

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