Cleaning device and electrophotographic apparatus

Provided is a cleaning device including a brush roll that removes residual toner remaining on a surface of a toner image carrier provided in an electrophotographic apparatus, and a pressure detector that contacts the surface of the brush roll with preload, and outputs a detected pressure value to a determination unit that is provided in the electrophotographic apparatus to determine the adhesion state of toner to the brush roll.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2011-275202 filed Dec. 16, 2011.

BACKGROUND

(i) Technical Field

The present invention relates to a cleaning device that removes residual toner remaining on the surface of a toner image carrier provided in an electrophotographic apparatus, and an electrophotographic apparatus including the cleaning device.

(ii) Related Art

Electrophotographic apparatuses are, for example, apparatuses, such as a copying machine, a facsimile machine, a printer apparatus, and a composite machine having these functions together, which form an image by transferring a toner image carried on a carrier, such as a photoconductor drum, to a recording medium, such as paper.

Such an electrophotographic apparatus includes a cleaning device that removes the residual toner remaining on the surface of the toner image carrier, and the cleaning device cleans the surface of the carrier to which the toner image is transferred.

SUMMARY

According to an aspect of the invention, there is provided a cleaning device including a brush roll that removes residual toner remaining on a surface of a toner image carrier provided in an electrophotographic apparatus; and a pressure detector that contacts the surface of the brush roll with preload, and outputs a detected pressure value to a determination unit that is provided in the electrophotographic apparatus to determine the adhesion state of toner to the brush roll.

DETAILED DESCRIPTION

First, an example of an electrophotographic apparatus that carries out the invention will be described.

InFIG. 10, the structure of an image forming section in the electrophotographic apparatus of this example is illustrated.

The illustrated electrophotographic apparatus is generally an intermediate transfer type called a tandem type, and includes, as typical functional sections, plural image forming units1Y,1M,1C, and1K in which toner images of respective color components are formed using an electrophotographic method, a primary transfer section10that sequentially transfers (primarily transfers) the respective color component toner images formed by the respective image forming units1Y,1M,1C, and1K to an intermediate transfer belt15, a secondary transfer section20that collectively transfers (secondarily transfers) a superposed toner image transferred onto the intermediate transfer belt15to paper P (an example of a recording medium), and a fixing device34that fixes the image secondarily transferred onto the paper P.

Additionally, the image forming apparatus of this example includes a controller40that controls the operation of the respective sections, and a user interface (UI)41for presenting information to a user or receiving an instruction from the user.

The image forming units1Y,1M,1C, and1K have photoconductor drums11Y,11M,11C, and11K that rotate in the direction of an arrow in the drawing, respectively. Additionally, various kinds of electrophotographic devices, including a charger12that charges the photoconductor drum11, an exposure unit13that irradiates the photoconductor drum11with an exposure beam Bm to write an electrostatic latent image on the drum, a developer unit14that contains each color component toner, and makes the electrostatic latent image on each of the photoconductor drums11Y,11M,11C, and11K into a visual image with the toner to form a toner image, a primary transfer roll16that transfers the toner image of each color component formed on each of the photoconductor drums11Y,11M,11C, and11K onto the intermediate transfer belt15in a superposed manner in the primary transfer section10, and a drum cleaner17Y,17M,17C, or17K that removes the residual toner on each of the photoconductor drums11Y,11M,11C, and11K, are sequentially disposed around each of the photoconductor drums11Y,11M,11C, and11K.

The image forming units1Y,1M,1C, and1K are arranged in the shape of a substantially straight line in order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side of the intermediate transfer belt15, and is configured so as to able to come into contact with or separate from the intermediate transfer belt15.

Additionally, the illustrated electrophotographic apparatus, includes, as a paper transporting system, a paper feed mechanism section31that performs the paper feed operation of taking out paper P from a paper accommodating section and feeding the paper into the secondary transfer section20, a transporting belt32that transports the paper P, which has passed through the secondary transfer section20, to the fixing device34side, a fixing inlet guide33that guides the paper P to an inlet of the fixing device34, a paper discharge guide35that guides the paper P discharged from the fixing device34, and a paper discharge roll36that discharges the paper P guided by the paper discharge guide35to the outside of the apparatus.

That is, the paper P fed from the paper accommodating section to the secondary transfer section20by the paper feed mechanism section31is transported to the transporting belt32in a state where the paper is peeled from the intermediate transfer belt15after the toner images on the intermediate transfer belt15are electrostatically transferred in the secondary transfer section20. Then, the paper is transported to the fixing device34via the fixing inlet guide33in conformity with the operating speed of the fixing device34by the transporting belt32. An unfixed toner image on the paper P transported to the fixing device34is fixed on the paper P by receiving the fixing processing of applying heat and pressure using the fixing device34. Thereafter, the paper P on which the fixed image has been formed is transported to a discharged paper accommodating section (not shown) provided outside the apparatus, via the paper discharge guide35and the paper discharge roll36.

Additionally, a belt cleaner17A that removes the residual toner on an intermediate transfer belt15is disposed downstream of the secondary transfer section20.

Here, the photoconductor drums11Y,11M,11C, and11K and the intermediate transfer belt15that are illustrated above are equivalent to toner image carriers that carry toner images in the invention. In the following descriptions, for convenience, these toner image carriers are generically described as a toner image carrier11.

Additionally, the drum cleaners17Y,17M,17C, and17K and belt cleaner17A that are illustrated above are equivalent to cleaning devices that remove the residual toner remaining on the surface of the toner image carrier11in the invention. In the following descriptions, for convenience, these cleaning devices are generically described as a cleaning device17.

In addition, the residual toner that the cleaning device17has removed from the toner image carrier11is recovered by a toner recovery unit (not shown) provided in the electrophotographic apparatus.

The details of the cleaning device17related to one exemplary embodiment of the invention are shown inFIGS. 1 and 2, and the cleaning device17is the drum cleaners17Y,17M,17C, and17K and the belt cleaner17A that correspond to any of the photoconductor drums11Y,11M,11C, and11K and the intermediate transfer belt15, which are in the toner image carrier11.

A housing51of the cleaning device17is in the shape of a box formed with an opening that faces the toner image carrier11, a brush roll52that rotates around its shaft is provided within the housing51, and the brush roll52contacts the toner image carrier11through the opening of the housing51.

Accordingly, the brush roll52rotates with the toner image carrier11, and the residual toner remaining on the surface of the toner image carrier11adheres to brush bristles of the peripheral surface of the brush roll52, and is removed.

An edge plate53is provided as a toner removal part in contact with the surface of the brush roll52within the housing51of the cleaning device17, and the edge plate53is located closer to the downstream side in the rotational direction of the brush roll52than a position where the brush roll52contacts the toner image carrier11, and extends over the total length of the brush roll52.

Accordingly, the residual toner adhering to the brush bristles of the peripheral surface of the brush roll52is shaken by the edge plate53, and is recovered in the housing51.

In addition, the toner removal part is not limited to an example having such a plate shape, and various toner removal parts may be used if the residual toner adhering to the brush bristles of the peripheral surface of the brush roll52may be shaken off.

A pressure sensor54that is a pressure detector is provided downstream of the edge plate53in the rotational direction of the brush roll52, and at least a pressure-sensitive surface of the pressure sensor54contacts the surface of the brush roll52with preload.

This preload, as will be described below, is provided to prevent residual toner from being accumulated on the pressure-sensitive surface of the pressure sensor54, to prevent erroneous detection caused by the pressure sensor54. The pressure of the preload is set so that the residual toner does not enter the pressure-sensitive surface side of the pressure sensor54.

As the pressure sensor54, various pressure sensors, such as a strain gage resistance type, a semiconductor piezoresistance type, an electrostatic capacitance type, a silicon resonant type, an electromagnetic induction type, and a conductor dispersion film electric resistance change type, may be adopted if a force applied to a given area may be converted into an electrical signal. In addition, the conductor dispersion film electric resistance change type may be preferable, because an electric circuit related to control can be simply made.

The number or size of the pressure sensor54is not particularly limited, and pressure may be able to be detected from at least one surface portion of the brush roll52. A pressure sensor that may detect pressure over a wide range or total length of the brush roll52may be preferable. For example, providing plural pressure sensors in plural locations in the axial direction of the brush roll52, providing one pressure sensor having a wide pressure-sensitive surface in the axial direction of the brush roll52, and the like may be adopted. In addition, providing one pressure sensor may simplify control electronic circuits.

Additionally, in the cleaning device17of this example, the housing51is provided with the cleaning blade55that extends in the width direction of the toner image carrier11, and the tip end of the cleaning blade55faces the opening of the housing51and contacts the surface of the toner image carrier11.

Accordingly, the residual toner remaining on the surface of the toner image carrier11is also removed by the cleaning blade55.

Although providing the cleaning blade55may be preferable to enhance the removal performance of the residual toner from the toner image carrier11, it is not indispensable in the aspect of the invention.

A toner recovery unit56is provided at the bottom within the housing51, and the toner recovery unit56sends the residual toner accumulating in the housing51to a recovery bottle (not shown) through the rotation of an auger screw.

FIG. 3conceptually shows an operation through which the pressure sensor54detects the pressure of the brush roll52. In this aspect of the invention, the cleaning blade55is omitted.

If residual toner T of the toner image carrier11adheres to the peripheral surface of the brush roll52and is carried through the rotation of the brush roll52, the residual toner is shaken by the edge plate53and removed from the brush roll52.

Then, a peripheral surface portion of the brush roll52from which the residual toner T is shaken by the edge plate53contacts the pressure-sensitive surface of the pressure sensor54.

Accordingly, the value of the pressure received from the peripheral surface of the brush roll52from which the residual toner T has been shaken off is detected.

Here, since the pressure sensor54contacts the peripheral surface of the brush roll52with preload, the pressure sensor54pushes away the residual toner T that remains without being shaken off from the peripheral surface of the brush roll52, to prevent the residual toner T from entering the pressure-sensitive surface of the pressure sensor54. This prevents the residual toner T from being accumulated and entering between the surface of the brush roll52and the pressure-sensitive surface of the pressure sensor54, to affect a pressure value detected by the pressure sensor54.

FIG. 4conceptually shows an operation through which the pressure sensor54detects the pressure of the brush roll52in a modification of the cleaning device17.

In this example, since the edge plate53is omitted, and an end portion of a device that constitutes the pressure sensor54is provided in a state where the end portion has entered the bristle tips of the brush roll52, residual toner T that has adhered to the brush roll52is shaken off by the edge of the pressure sensor device54in the rotational direction of the brush roll52.

Accordingly, even if the edge plate53is omitted, the peripheral surface portion of the brush roll52from which the residual toner T has been shaken off contacts the pressure-sensitive surface of the pressure sensor54, and along with the above action using preload, the residual toner T is prevented from entering between the surface of the brush roll52and the pressure-sensitive surface of the pressure sensor54.

In addition, as shown inFIG. 5, the edge plate53may be provided, and an end portion of the pressure sensor device54may be provided in a state where the end portion has entered the bristle tips of the brush roll52.

FIGS. 6A to 6Dshow examples of the preferable shape of the edge of the pressure sensor device54in which the end portion is provided in a state where the end portion has entered the bristle tips of the brush roll52.

A pressure sensor device54shown inFIG. 6Ahas a shape in which the corners of the end portion that enters the bristle tips of the brush roll52are rounded, and a pressure sensor device54shown inFIG. 6Bhas a shape in which the corners of the end portion that enters the bristle tips of the brush roll52are rounded, and the end face is curved. A pressure sensor device54shown inFIG. 6Chas a shape in which the end face of the end portion that enters the bristle tips of the brush roll52is chevron-shaped, and a pressure sensor device54shown inFIG. 6Dhas a shape in which the end face of the end portion that enters the bristle tips of the brush roll52is formed as included surface at an obtuse angle.

These shapes may prevent the bristle tips of the brush roll52from being damaged due to application of an excessive resistance. In addition, the invention is not limited to the above examples, and various shapes may be adopted.

Additionally, in a case where the pressure sensor device54is provided at an axial end portion of a brush roll52, it is preferable to provide a gap of, for example, 50 μm or more between the pressure sensor device54and the housing51so that the residual toner removed by the end portion of the pressure sensor device54may move.

Next, comparison experiment results of the configuration (Condition1) related to one example of the invention shown inFIG. 4and a configuration (Condition2) with a gap between the pressure sensor54and the brush roll52as shown inFIG. 7will be described.

In the comparison experiments, experiments are performed on Condition1and Condition2regarding a belt cleaner (cleaning device) of a belt transfer system, using a printer apparatus (Color 1000 made by FUJI Xerox Corp.) as the electrophotographic apparatus.

Additionally, a film-like pressure sensor made by Nitta, Inc. (A201-1) is used as the pressure detector54, and an exclusive amplifier box of the sensor is adjusted so as to output 1 V when a load of 1 g is applied to a whole sensing area with a diameter of 9.5 mm. Then, this amplifier output is read by a control PC via an A/D converter.

In Condition1(FIG. 4), a cleaning device that is a new article and to which toner does not adhere at all is prepared, and the film sensor54is pasted on the inside of the housing51, and the force with which the brush roll52pushes the pressure-sensitive surface of the film sensor54is set to 0.5 g.

In Condition2(FIG. 7), a cleaning device that is a new article and to which toner does not adhere at all is prepared, and the film sensor54is pasted on the inside of the housing51, and the force with which the brush roll52pushes the pressure-sensitive surface of the film sensor54is set to 0 g so that there is a gap between the film sensor54and the brush roll52.

In each of Conditions1and2, printing is performed on 200,000 sheets of A3 paper such that a printable region becomes a black solid over the entire surface.

The results based on Condition1are as follows. Minute black spots observable by a magnifying glass begin to be generated on a printed image from about the 50,000th sheet, and black spots that grow in the shape of a comet at about the 100,000th sheet begin to appear, and a black streaky image defect is seen on the whole surface at about the 150,000th sheet.

Changes in the force with which the brush roll52pushes the pressure-sensitive surface of the film sensor54on this Condition1are as shown inFIG. 8A. That is, although the initial value of the force is 0.5 g that is the same until about the 50,000th sheet in which abnormalities are not observed, the force continues rising gently after this, and becomes about 0.6 g, becomes 1 g at about the 100,000th sheet, and becomes 2 g at about the 150,000th sheet.

That is, it is recognized that there is a relationship according to the number of printed sheets (the amount of operation) between the state of defects appeared on a printed image and the force (that is, a pressure value detected) applied to the film sensor54. For example, if an alarm is issued before the 100,000th sheet that is brought into a state where an image defect is clear as viewed with eyes, occurrence of such an image defect may be prevented in advance.

One of the factors that cause such an image defect is that the residual toner adhering to the brush bristles of the brush roll53may anchor, the brush bristles may lose flexibility, and the residual toner to be removed by the brush roll52may be transferred to a printed image.

Since the force (pressure) of pushing the pressure-sensitive surface of the film sensor54rises if the flexibility of the brush bristles is impaired in this way, the adhesion state of the residual toner to the brush roll52, and thus the occurrence situation of an image defect may be known depending on changes in the pressure value that the film sensor54detects.

On the other hand, in Condition2, changes in the force that the pressure-sensitive surface of the film sensor54receives is shown inFIG. 8B. That is, the force with which the pressure-sensitive surface of the film sensor54is pushed rises rapidly immediately after the start of operation, and exceeds a measuring range before about the 50,000th sheet from which an abnormality begins to occur.

This may be said that residual toner may enter and accumulate between the pressure-sensitive surface of the film sensor54and the peripheral surface of the brush roll52, and thereby, the detection pressure value of the film sensor54may have risen at one time.

Accordingly, in Condition2, changes in the pressure value according to the adhesion state of the residual toner to the brush roll52may not be detected like in Condition1. Thus, the above alarm may not be issued.

FIG. 9shows a configuration for issuing an alarm using the pressure value detected by the pressure sensor54as mentioned above.

That is, the above configuration includes a determination unit61to which the pressure value detected by the pressure sensor54is input, a reference value holding unit62that holds a preset reference value as the pressure value to issue an alarm, and an output unit63that outputs an alarm.

The determination unit61and the reference value holding unit62may be constructed in the controller40provided in the electrophotographic apparatus, and the output unit63is constructed in a UI41provided in the electrophotographic apparatus.

Accordingly, if the pressure value detected by the pressure sensor54is input to the determination unit61with the operation of the electrophotographic apparatus, the determination unit61determines whether or not the input pressure value has reached the reference value held by the holding unit62. When the reference value is reached, an alarm is output from the output unit63to notify that maintenance is necessary, such as replacement of the brush roll or cleaning of the cleaning device, or occurrence of an image defect to a user.

Here, the setting value of the reference value may be arbitrarily set if necessary. To make a description using the example shown inFIG. 8A, for example, if the reference value is set to 0.6 g, an alarm indicating that an image defect will occur when about 50,000 sheets are printed afterwards may be issued in advance, and if the reference value is set to 1 g, an alarm indicating that an image defect will occur soon may be issued.

In the above example, an alarm is notified to a user. However, for example, an alarm may be output to a remote management device with the output unit as a network interface so as to notify an administrator of the electrophotographic apparatus.

Additionally, although the electrophotographic apparatus that performs development with four colors of toner, such as yellow (Y), magenta (M), cyan (C), and black (K), has been described as an example, the invention is not particularly limited by the kinds or number of toners, the types of electrophotographic apparatuses, or the like if electrophotographic apparatus image forming apparatuses that perform toner development, are provided, such as an image forming apparatus that performs development with five colors of toners in which a transparent toner is added to the above colors, and an image forming apparatus that performs development with one color of toner of black (K).