JP2017125877A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the removal of adhesion on a linear scale and to prevent the deterioration of a reflection rate of the linear scale by removing refuse such as toner or dust without fail.SOLUTION: A fan 33 (air flow generating means) is installed below a linear scale sensor 27, and an air flow from an upstream side to a downstream side is generated in a moving direction of an intermediate transfer belt 8. An air curtain is formed by the air flow, and toner adhered to the intermediate transfer belt 8 is prevented from falling onto a sensor reading portion 30. A destaticizing member 35 is attached on an upstream side of the linear scale sensor 27, and an electric charge of the intermediate transfer belt 8 is removed or reduced, thereby facilitating the removal of toner T or dust adhered to a linear scale 28. By an air flow generated by the fan 33, the adhered toner T and the like are removed, thereby preventing the deterioration of a reflection rate of the linear scale 28.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an image forming apparatus using an endless belt having a linear scale.

  Some image forming apparatuses such as copying machines, printers, and facsimiles use an endless belt as means for carrying a toner image or means for conveying a recording medium (recording material) onto which a toner image is transferred. For example, an intermediate transfer belt is known as an endless belt carrying a toner image. As an endless belt for conveying a recording medium, a transfer belt (transfer conveyance belt) is known.

  In such an image forming apparatus using an endless belt (hereinafter sometimes simply referred to as a belt), maintaining the belt speed accurately at a desired speed generates abnormal images such as banding and color misregistration. It is very important not to let it happen.

  As a method of accurately maintaining the belt speed at the desired speed, a linear scale is applied to the back side of the belt, the behavior of the linear scale is accurately measured by the linear scale sensor, and the speed is made constant by feeding back to the drive control. There is a method to keep.

  However, the linear scale is also charged when the belt is charged by the transfer operation during printing. This facilitates attracting toner in the air or inside the machine, promotes contamination of the linear scale sensor, and adheres to the toner. The output of the linear scale sensor may decrease due to a decrease in the reflectance of the linear scale itself.

  Japanese Patent Laid-Open No. 2005-181090 (Patent Document 1) discloses a fan that supplies a high-pressure fluid between a detection target and an optical sensor for the purpose of removing dirt such as toner and dust attached to the detection target. It is disclosed that by attaching a thing, dust such as toner and dust attached to a detection target is removed and reading error is reduced.

  However, the device described in Patent Document 1 has a problem that dust such as toner and dust attached to the detection target cannot be sufficiently removed when the linear scale is charged.

  Therefore, an object of the present invention is to facilitate removal of deposits on the linear scale, and to reliably remove dust such as toner and dust to prevent a decrease in the reflectance of the linear scale.

  An object of the present invention is to provide an endless belt for carrying a toner image or conveying a recording medium to which a toner image is transferred, a linear scale provided on the endless belt, and means for measuring a step interval of the linear scale. The image forming apparatus includes: a linear scale sensor including: a linear scale sensor; an airflow generating unit that generates an airflow between the linear scale sensor and the linear scale; and a charge eliminating member that removes charges from the linear scale.

  According to the present invention, it is possible to facilitate the removal of the adhered matter on the linear scale by including the airflow generating means for generating an airflow between the linear scale sensor and the linear scale and the static eliminating member for removing the charge of the linear scale. In addition, it is possible to reliably remove dust such as toner and dust and prevent the reflectance of the linear scale from decreasing.

1 is a cross-sectional view illustrating an embodiment of an image forming apparatus according to the present invention. FIG. 2 is a diagram schematically illustrating an intermediate transfer unit. It is a schematic diagram which shows the relationship between an intermediate transfer belt, a linear scale, and a linear scale sensor. It is sectional drawing which shows the structure of a linear scale sensor. It is a schematic diagram for demonstrating the stain | pollution | contamination of a linear scale. It is typical sectional drawing which shows the structural example to which this invention is applied. It is typical sectional drawing which shows the modification which provided the member which optimizes an airflow. FIG. 4 is a diagram illustrating a state of an intermediate transfer belt during monochrome printing. It is a figure which shows a mode that the installation angle of the fan was changed according to the change of printing mode. FIG. 3 is a schematic cross-sectional view illustrating a configuration example provided with a means for storing toner.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing a tandem type full-color image forming apparatus which is an embodiment of an image forming apparatus according to the present invention. First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG.

  The image forming apparatus shown in FIG. 1 is an electrophotographic image forming apparatus using an intermediate transfer system, and uses an endless belt (intermediate transfer belt 8) as an intermediate transfer member. As shown in FIG. 1, around each photosensitive drum 1 (yellow, magenta, cyan, black), a charging device (corona charger) 2, a developing device 4, a cleaning unit (not shown), a charge eliminating unit, etc. Is arranged. Then, an image forming process is performed on each photosensitive drum 1, and an image of each color is formed on each photosensitive drum 1.

The photosensitive drum 1 as an image carrier is rotationally driven by a drive motor. Then, the surface of the photosensitive drum 1 is uniformly charged at the position of the charging device 2 (charging process).
Thereafter, the photosensitive drum 1 reaches the irradiation position of the laser beam emitted from the image writing device 3, and an electrostatic latent image corresponding to each color is formed by exposure scanning at this position (exposure process).

Thereafter, the surface of the photosensitive drum 1 reaches a position facing the developing device 4, and the electrostatic latent image is developed at this position to form a toner image of each color (developing process).
Thereafter, the surface of the photosensitive drum 1 reaches a position facing the endless intermediate transfer belt 8 and the transfer roller 14 of the primary transfer portion 5, and the toner image on the photosensitive drum 1 is transferred to the intermediate transfer belt 8 at this position. Transferred upward (primary transfer step). In this way, a color image is formed on the intermediate transfer belt 8.

  The untransferred toner remaining on the photosensitive drum 1 is collected by a cleaning unit (cleaning process), and reaches a position facing a neutralization unit (not shown), and the residual potential of the photosensitive drum 1 is reached at this position. Is removed.

  The intermediate transfer belt 8 onto which the toner images of the respective colors are transferred in a superimposed manner reaches the secondary transfer unit 9 in which the secondary transfer counter roller 16 is installed at a position facing the secondary transfer roller 15 with the intermediate transfer belt 8 interposed therebetween. . At this position, the toner image is transferred from the paper feeding device 7 to the surface of the paper P that is transported through the transport path 12 (secondary transfer process).

  Thereafter, the sheet P on which the toner image is transferred is fed into the fixing device 20 and passes through a nip portion between the heating roller (fixing roller) 21 and the pressure roller 22 whose surface is covered with an elastic body. As a result, heat and pressure are applied, and the toner image is fixed on the paper P and sent to the downstream conveyance path.

  A cooling device 10 is provided on the downstream side of the fixing device 20, and the paper P conveyed to the cooling device 10 is cooled to an appropriate temperature and discharged from the paper discharge port 11. It should be noted that the sheet from an additional sheet feeding device (not shown) can be similarly handled through the transport path 13.

  FIG. 2 is a diagram schematically illustrating the intermediate transfer unit. FIG. 3 is a schematic diagram showing the relationship between the intermediate transfer belt, the linear scale, and the linear scale sensor. The moving direction of the intermediate transfer belt 8 is the clockwise direction in FIG. 2, as indicated by the arrow S in the drawing.

  In the present embodiment, the intermediate transfer unit includes an intermediate transfer belt 8, a linear scale 28 for improving the running stability of the intermediate transfer belt 8, and a linear scale sensor 27 that observes the linear scale 28.

  The intermediate transfer belt 8 is an intermediate transfer body to which the linear scale 28 is applied (mounted). The intermediate transfer belt 8 includes a drive roller 17 provided upstream of the secondary transfer unit 9 (upstream in the rotation direction of the intermediate transfer belt), a driven roller 18 provided downstream of the secondary transfer unit 9, It is passed over the next transfer counter roller 16 and the like. Each roller and the like around which the intermediate transfer belt 8 is stretched are mounted on a casing of the intermediate transfer unit, and the intermediate transfer belt 8 is rotatably supported by the casing.

  A seal engraved with a linear scale 28 is attached to the back surface (the inner surface of the loop) of the intermediate transfer belt 8, and the intermediate transfer belt 8 is accurately read by reading the increment (scale) with the linear scale sensor 27. Therefore, the intermediate transfer belt 8 can be accurately controlled.

FIG. 4 is a cross-sectional view showing the basic configuration of the linear scale sensor.
The linear scale sensor 27 has two sensor reading units 30 arranged on the upstream side and the downstream side in the moving direction of the linear scale 28 to be detected. The two sensor reading units 30 read the linear scale 28 attached to the back surface of the intermediate transfer belt 8 to measure the speed of the intermediate transfer belt 8.

  In FIG. 4, an arrow S indicates the moving direction of the intermediate transfer belt 8, and an alternate long and short dash line arrow in the linear scale sensor 27 indicates sensor reading. The distance between the linear scale sensor 27 and the intermediate transfer belt 8 at the time of reading is controlled by being sandwiched between an upper press 29 provided at the upper part of the sensor and a bracket 31 of the linear scale sensor 27. In addition, fluttering of the intermediate transfer belt 8 and the linear scale 28 is suppressed. The upper presser 29 is a presser member that presses the intermediate transfer belt 8 toward the linear scale sensor.

FIG. 5 is a schematic diagram for explaining the contamination of the linear scale.
Here, as shown in FIG. 5, when the intermediate transfer belt 8 is driven to perform a printing operation, the scattered toner T adheres to the intermediate transfer belt 8. During the printing operation, the intermediate transfer belt 8 is charged by the transfer operation, so the linear scale 28 is also charged. The electric charge makes it easy for the linear scale 28 to attract the toner T in the atmosphere or inside the machine. The toner T is rubbed off by the sensor bracket 31 in the area of the linear scale sensor 27 and stains the sensor reading unit 30. If the contamination progresses, the sensor reading cannot be performed normally, resulting in an output abnormality. Further, when the toner T adheres to the linear scale 28, the reflectance of the linear scale itself decreases, and the sensor reading cannot be performed normally, resulting in an abnormal output.

  Further, in the configuration as shown in FIG. 4, the linear scale 28 and the sensor bracket 31 rub against each other, so that the linear scale 28 is inevitably damaged, leading to a decrease in the reflectance of the linear scale 28.

FIG. 6 is a schematic cross-sectional view showing a configuration example to which the present invention is applied.
In FIG. 6, a fan 33 (airflow generating means) is installed below the linear scale sensor 27 so as to create an air flow from the upstream side to the downstream side in the moving direction of the intermediate transfer belt 8. An air curtain is formed by this air flow, and it is possible to prevent the toner adhering to the intermediate transfer belt 8 from falling onto the sensor reading unit 30.

  Although it has been described here that the fan 33 is installed below the linear scale sensor 27, the position of the airflow generation means is assumed to be located behind the linear scale sensor 27 (on the opposite side of the intermediate transfer belt 8). Further, the airflow generation means is not limited to the fan.

  The distance between the intermediate transfer belt 8 and the linear scale sensor 27 is ensured by the intermediate transfer belt 8 being pressed against the upper press 29 by the air flow generated by the fan 33, thereby preventing the belt from flapping. Further, since the space between the intermediate transfer belt 8 and the linear scale sensor 27 is free, the friction with the sensor bracket 31 is eliminated, and the linear scale 28 can be prevented from being damaged.

  Further, by attaching the charge eliminating member 35 to the upstream side of the linear scale sensor 27, the charge of the intermediate transfer belt 8 is removed or reduced, and the toner T and dust adhering to the linear scale 28 are easily removed. The toner T and the like attached thereto are removed by the air flow generated by the fan 33, thereby preventing the reflectance of the linear scale 28 from being lowered.

  The air flow generated by the fan 33 can be changed in wind speed and air volume (wind speed and / or air volume) according to the linear speed (speed) of the intermediate transfer belt 8, and the wind speed and air volume are optimized in accordance with the linear speed. Can be changed. At that time, when the linear speed is high, the wind speed / air volume setting is increased to facilitate the flow of airflow, and when the linear speed is slow, the wind speed / air volume setting is decreased to reduce the airflow more than necessary. Not generating it is effective in reducing power consumption.

  In the embodiment, the linear speed of the intermediate transfer belt 8 is set according to the image forming process speed, and in the case of a model that can change (switch) the image forming process speed, What is necessary is just to control a wind speed and an air volume according to the linear speed change of the intermediate transfer belt 8 by switching.

  Further, since the amount of toner consumed varies depending on the image to be printed, the air speed and the amount of air of the fan 33 can be changed depending on the amount of consumption (toner amount of the formed image). Wind speed and volume can be changed to be optimal.

  Also, printing is not performed in the mode driven by a single belt, such as when the machine power is turned on, when the intermediate transfer belt is meandering, when the output of the linear scale sensor 27 is adjusted, or when the phase is adjusted. Therefore, the toner does not adhere to the belt. Therefore, by reducing or stopping the wind speed / air volume of the fan 33 at that time, efficient operation can be performed from the viewpoint of the life of the fan 33 and power consumption.

FIG. 7 is a schematic cross-sectional view showing a modified example in which a member for optimizing the airflow by the fan is provided.
In FIG. 7, an airflow guide member 34 for optimizing the airflow generated by the fan 33 is appropriately provided in the sensor bracket 31. In the illustrated example, a plurality of triangular airflow guide members 34 are attached to the sensor bracket 31. The shape, size, and number of airflow guide members 34 are appropriately set so that the airflow generated by the fan 33 is efficiently directed from the upstream side to the downstream side in the belt movement direction (linear scale movement direction).

  It can also be set by adjusting the direction of the fan 33 so that the airflow goes from the upstream side to the downstream side. In this case, the direction of the airflow guide member 34 and the fan 33 may be combined, or the direction of the fan 33 may be set without providing the airflow guide member 34.

  The direction of the air flow generated by the fan 33 may be any of upstream to downstream in the linear scale movement direction, downstream to upstream in the movement direction, and belt width direction, but upstream in the linear scale movement direction. More preferably, the downstream side. By flowing the air flow from the upstream side to the downstream side in the moving direction of the scale, it is possible to prevent the toner blown off by the fan from reattaching to the linear scale as compared with the case of flowing the air flow from the downstream side to the upstream side. Further, it is possible to prevent the area on the near side and the far side of the belt in the width direction of the belt from being contaminated with toner as compared with the case where an air flow is made to flow in the width direction of the belt.

  By the way, the image forming apparatus of this embodiment includes four photosensitive drums 1 (yellow, magenta, cyan, and black). When performing full-color printing, as shown in FIG. 2, the intermediate transfer belt 8 is configured to be horizontal with respect to each photosensitive drum 1. When performing monochrome printing using only black toner, the intermediate transfer belt 8 is in contact with only the black photosensitive drum 1Bk and not with the other photosensitive drums 1Y, 1M, and 1C. Can be driven slightly lower. The state of the intermediate transfer belt 8 during monochrome printing is shown in FIG.

  Thus, when the position or angle of the intermediate transfer belt 8 fluctuates due to the difference in the printing mode of the image forming apparatus, the linear scale sensor 27 is also used to accurately measure the linear scale with the linear scale sensor. It is necessary to change the position or angle in accordance with the change of 8. At this time, it is preferable that the position or angle of the fan 33 can be changed so that the fan 33 is also in an optimum state.

  FIG. 9 shows the fan 33 when the intermediate transfer belt 8 is changed according to the change of the print mode (here, the inclination angle is changed) and the installation angle of the linear scale sensor 27 is changed accordingly. It is a schematic diagram which shows a mode that the installation angle of was changed. The fan 33 is provided so that the installation angle can be changed, and the installation angle can be automatically changed using a driving means such as a stepping motor 36. Thereby, even when the installation angle of the linear scale sensor 27 is changed due to the change of the printing mode, the direction of the airflow generated by the fan 33 can be optimized.

  For example, when the upstream side of the linear scale sensor 27 is lowered during monochrome printing, the air flow is caused to flow downstream by rotating the installation angle of the fan 33 clockwise in FIG. 9 (clockwise from the state during full color printing). Make it easier. When changing the mode from monochrome printing to full-color printing, conversely, by rotating the installation angle of the fan 33 counterclockwise in FIG. 9 (counterclockwise from the state during monochrome printing), airflow is generated downstream. Easy to flow.

  The change in the installation angle of the fan 33 needs to be changed according to the printing mode (specified) at that time. Therefore, the installation angle can be automatically changed by an appropriate configuration using a stepping motor or the like.

FIG. 10 is a schematic cross-sectional view showing a configuration example provided with means for storing toner.
In FIG. 10, a storage member 37 is attached to the downstream side of the linear scale sensor 27 to store dust such as toner and dust (particles flowed by the air flow of the fan 33). By providing the accumulating member 37, the toner or the like that is blown off by the airflow generated by the fan 33 is prevented from splashing on the downstream side of the linear scale sensor 27. In addition, the storage member 37 can be attached to and detached from the side surface of the linear scale sensor 27, and it is desirable that the storage member 37 has a simple configuration because it can be removed and cleaned during regular maintenance.

  In the above-described embodiment, the intermediate transfer belt 8 that carries the toner image on the surface is described as a specific example of the endless belt. However, the present invention is not limited to this. As the endless belt, a conveyance belt provided to face the image carrier such as a photosensitive drum or an intermediate transfer belt may be used. The conveying belt conveys the sheet sent from the registration roller while adsorbing the sheet to the surface thereof. The paper is transported to a transfer position facing the image carrier by a transport belt. The toner image on the image carrier is transferred onto the sheet at a transfer position between the image carrier and the conveyor belt.

  As described so far, according to the present invention, by including the airflow generating means for generating an airflow between the linear scale sensor and the linear scale, and the charge eliminating member for removing the charge of the linear scale, It is possible to easily remove the deposits and reliably remove dusts such as toner and dust, thereby preventing a decrease in the reflectance of the linear scale.

  Moreover, dust such as toner and dust can be more reliably removed by generating an air flow that flows from the upstream side to the downstream side of the linear scale sensor in the linear scale moving direction.

Further, since the airflow generation means is disposed below the linear scale sensor, it is possible to prevent toner, dust, and the like from falling on the linear scale sensor.
In addition, by having a pressing member that presses the endless belt toward the linear scale sensor, it is possible to suppress the fluttering of the belt, to ensure the correct distance between the sensor and the belt, and to prevent scratching by suppressing the rubbing of the linear scale. .

  In addition, since the wind speed or / and the air volume of the air flow generating means can be changed according to the speed of the endless belt, the air speed or / and the air volume can be optimally controlled, and the effect of preventing sensor contamination and suppressing the flapping of the belt. Can be increased.

  In addition, since the direction of the airflow of the airflow generating means can be changed according to the printing mode, it is possible to control the air speed and / or the air volume suitable for the behavior of the endless belt that changes depending on the printing mode, and to prevent the sensor from becoming dirty. The effect of suppressing fluttering can be enhanced.

  In addition, by providing a storage member that accumulates the particles flown by the airflow of the airflow generation means, the toner blown by the airflow of the airflow generation means is prevented from scattering, preventing in-machine contamination and affecting other parts. Can be prevented.

  Further, the air speed or / and the air volume of the air flow generating means can be changed according to the toner amount of the image to be formed, so that the air speed or / and the air volume optimal for the toner amount of the image can be controlled, and the stain prevention effect can be achieved. Can be increased.

  In addition, when the endless belt is driven alone, the air speed or / and the air volume of the air flow generating means is reduced or stopped, so that efficient operation can be performed in terms of the life of the air flow generating means and the power consumption.

Although the present invention has been described based on the illustrated examples, the present invention is not limited to this and can be appropriately changed within the scope of the present invention.
As the image forming apparatus, any configuration can be adopted as long as the present invention is applicable. The image forming apparatus is not limited to a copying machine or a printer, but may be a facsimile machine or a multifunction machine having a plurality of functions.

1 Photosensitive drum 1
3 Image writing device 8 Intermediate transfer belt 8 (endless belt)
9 Secondary transfer unit 20 Fixing device 27 Linear scale sensor 28 Linear scale 29 Upper presser (pressing member)
30 Sensor Reading Unit 31 Sensor Bracket 33 Fan (Air Flow Generation Unit)
34 Airflow guide member 35 Static elimination member 37 Storage member P Paper (recording medium)
S Intermediate transfer belt moving direction T Toner

JP 2005-181090 A

Claims (11)

An endless belt carrying a toner image or conveying a recording medium onto which the toner image is transferred;
A linear scale provided on the endless belt;
A linear scale sensor having means for measuring a step interval of the linear scale;
An airflow generating means for generating an airflow between the linear scale sensor and the linear scale;
An image forming apparatus comprising: a charge eliminating member that removes electric charges of the linear scale.   The image forming apparatus according to claim 1, wherein the airflow generation unit generates an airflow that flows from an upstream side to a downstream side of the linear scale sensor in the linear scale movement direction.   The image forming apparatus according to claim 1, further comprising an airflow guide member that guides an airflow from the airflow generation unit from an upstream side to a downstream side of the linear scale sensor in the linear scale movement direction. .   The image forming apparatus according to claim 1, wherein the airflow generation unit is disposed below the linear scale sensor.   The image forming apparatus according to claim 1, further comprising a pressing member that presses the endless belt toward the linear scale sensor.   The image forming apparatus according to claim 1, further comprising a housing that rotatably supports the endless belt.   The image forming apparatus according to claim 1, wherein a wind speed and / or an air volume of the airflow generation unit can be changed according to a speed of the endless belt.   The image forming apparatus according to claim 1, wherein the direction of the airflow of the airflow generation unit can be changed according to a printing mode of the image forming apparatus.   The image forming apparatus according to claim 1, further comprising an accumulation member that accumulates particles carried by the airflow of the airflow generation unit.   The image forming apparatus according to claim 1, wherein the air velocity or / and the air volume of the air flow generation unit can be changed according to a toner amount of an image to be formed. 11. The image according to claim 1, further comprising: a mode in which the endless belt is driven alone, wherein the air velocity or / and the air volume of the air flow generation unit is reduced or stopped in the mode. Forming equipment.

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