Detection device for detecting state of toner image, image forming apparatus employing the same, and method of removing foreign substance from the detection device

A detection device detecting a state of a toner image, an image forming apparatus including a detection device and method of detection are provided. The detection device includes a detector having a light window where light passes through and detecting a state of a toner image formed on an image bearing member via the light window, and a cleaner removing a pollutant attached to a surface of the light window. The cleaner includes an adsorption unit formed of a conductive material and reciprocating while being in contact with the surface of the light window and a voltage applying unit applying a voltage for adsorbing the pollutant to the adsorption unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to, and claims priority to, Korean Patent Application No. 10-2012-134872, filed on Nov. 26, 2012, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

Embodiments of the present invention relate to a detection device for detecting a state of a toner image, an image forming apparatus employing the detection device, and a method of removing foreign substances from the detection device, and more particularly, to a detection device capable of reducing a detection error by preventing contamination of the detection device, an image forming apparatus employing the detection device, and a method of removing foreign substances from the detection device.

2. Description of the Related Art

An image forming apparatus forms an electrostatic latent image on a photosensitive body by an exposure operation, forms a toner image on the photosensitive body by supplying toner, transfers the toner image formed on the photosensitive body to a printing medium, and fixes the transferred toner image to the printing medium by using heat and pressure, thereby performing printing.

However, in a case of the toner image formed on the photosensitive body, a state of the toner image such as concentration and an aligned state of the toner image may deviate from predetermined standards due to environmental effects such as temperature and humidity while performing a transfer operation. To address such problems, a state of the toner image may be detected, a concentration may be adjusted according to a value obtained by detection, or the aligned state may be adjusted.

However, since a detection device detecting a state of a toner image may be disposed adjacent to an image bearing member with the toner image formed such as a photosensitive body to detect the toner image, the detection device may be contaminated contaminate by foreign substances such as scattered toner while forming the toner image. Such contamination of the detection device generates a detection error, which makes an adjustment operation according thereto indefinite.

SUMMARY

An exemplary embodiment of the present invention provides a detection device of an image forming apparatus, the detection device capable of reducing detection errors generated by a foreign substance attached to the detection device.

An exemplary embodiment of the present invention provides an image forming apparatus including a detection device and a method of removing a foreign substance from the detection device.

According to an aspect of the present invention, a detection device is provided. The detection device includes a detector having a light window where light passes through and detecting a state of a toner image formed on an image bearing member via the light window, and a cleaner removing a pollutant attached to a surface of the light window. The cleaner includes an adsorption unit formed of a conductive material and reciprocating while being in contact with the surface of the light window and a voltage applying unit applying a first voltage for adsorbing the pollutant to the adsorption unit.

The adsorption unit may be capable of being transferred to a first location for being in contact with the light window and a second location for releasing a contact with the light window.

The voltage applying unit may apply the first voltage for adsorbing the pollutant to the adsorption unit when the adsorption unit is located in the first location.

The first voltage may be a voltage having polarity opposite to the pollutant.

The polarity of the first voltage may be periodically converted.

The cleaner may include a pollutant collecting unit collecting the pollutant.

The pollutant collecting unit may include a contact projection projected crossing a transfer path of the adsorption unit and being in contact with the adsorption unit.

The voltage applying unit may apply a second voltage for separating the pollutant from the adsorption unit to the adsorption unit when the adsorption unit is located in the second location.

The second voltage may be one of a voltage having the same polarity as the pollutant and a ground voltage.

The voltage applying unit may apply a third voltage for collecting the pollutant into the pollutant collecting unit to the pollutant collecting unit when the adsorption unit is located in the second location.

The third voltage may be a voltage having polarity opposite to the pollutant.

The voltage applying unit may apply a fourth voltage for preventing the pollutant being attached to the light window to the adsorption unit.

The fourth voltage may be one of a voltage having the same polarity as the pollutant and a ground voltage.

The detection device may include a housing containing the detector, the housing with an opening between the light window and the image bearing member to allow light to pass through, and a shutter opening and closing the opening.

The adsorption unit may be installed on a surface of the shutter facing the detector, and the adsorption unit may remove the pollutant attached to the light window by a transfer of the shutter.

According to an aspect of the present general inventive concept, there is provided an image forming apparatus including the detection device.

The apparatus may include a housing containing the detector, the housing with an opening between the light window and the image bearing member to allow light to pass through, and a shutter opening and closing the opening.

The adsorption unit may be installed on a surface of the shutter facing the detector, and the adsorption unit may remove the pollutant attached to the light window by a transfer of the shutter.

According to an aspect of the present invention, there is provided a method of removing pollutant, performed by a detection device detecting a state of a toner image formed on an image bearing member. The method includes applying, to adsorb pollutant attached to a light window of a detector, a first voltage for adsorbing the pollutant to an adsorption unit reciprocating while being in contact with the light window, and allowing the pollutant to be adsorbed onto the adsorption unit by using electrical fundamental forces generated between the adsorption unit and the pollutant.

In the allowing the pollutant to be adsorbed onto the adsorption unit, the adsorption unit may be located in a location for being in contact with the light window.

The first voltage may be a voltage having polarity opposite to the pollutant.

The polarity of the first voltage may be periodically converted.

The method may include after the allowing the pollutant to be adsorbed onto the adsorption unit, separating the pollutant adsorbed onto the adsorption unit.

In the separating the pollutant, the adsorption unit may be located in a location for releasing a contact with the light window.

In the separating the pollutant, the adsorption unit may be transferred while being in contact with a contact projection formed on a pollutant collecting unit.

In the separating the pollutant, a second voltage for separating the pollutant adsorbed onto the adsorption unit may be applied the adsorption unit.

The second voltage may be one of a voltage having the same polarity as the pollutant and a ground voltage.

In the separating the pollutant, a third voltage for collecting the pollutant into the pollutant collecting unit may be applied to the pollutant collecting unit.

The third voltage may be a voltage having polarity opposite to the pollutant.

After the separating the pollutant, a fourth voltage for preventing the pollutant being attached to the light window may be applied to the adsorption unit.

The method may include determining an exposure of the detector via a transfer of a shutter arranged between the image bearing member and the detector.

The adsorption unit may be installed on a surface of the shutter facing the detector and removes the pollutant attached to the light window by using the transfer of the shutter.

The detection device, the image forming apparatus and the method of removing pollutant by using the detection device may improve efficiency of removing pollutant attached to the detection device by using mechanical friction and electrical fundamental forces to remove the pollutant. Also, detection errors are reduced and a state of a toner image is corrected without error according to a detected value, thereby improving quality of printed images.

DETAILED DESCRIPTION

Exemplary embodiments of the present invention are disclosed with reference to the accompanying drawings, in which exemplary embodiments of the present invention are illustrated.

FIG. 1illustrates an image forming apparatus according to an exemplary embodiment of the present invention. The image forming apparatus may include a development unit110, transfer units120aand120b, a fixing unit130, a power supply unit140, an adjustment unit150, and a detection device100. The transfer units120aand120bmay include additional transfer units.

According to an exemplary embodiment of the image forming apparatus, when image data is received from the outside, the development unit110develops an image. Exposure units111to114inject light to photosensitive bodies115to118, electrostatic latent images may be formed on the photosensitive bodies115to118, respectively, electrified toner may be supplied thereto, and toner particles may be attached to surfaces of the photosensitive bodies115to118, thereby forming toner images. To form the toner images, not illustrated inFIG. 1, the development unit110may include an electrification element in contact with the photosensitive bodies115to118to electrify the surfaces of the photosensitive bodies115to118, a developing element supplying toner to the photosensitive bodies115to118, and a cleaning element cleaning the surfaces of the photosensitive bodies115to118. Although four exposure units111to114and the four photosensitive bodies115to118are illustrated inFIG. 1, an exemplary image forming apparatus forming a color image and including photosensitive bodies and exposure units for four colors such as cyan, magenta, yellow, and black, respectively, is not limited thereto.

The toner images formed on the photosensitive bodies115to118may be transferred from the first transfer unit120ato an intermediate transfer belt127. To the intermediate transfer belt127rotated by intermediate transfer rollers125and126, images corresponding to respective colors of cyan, magenta, yellow, and black, respectively, may be sequentially transferred, thereby forming a color toner image. The toner images formed on the intermediate transfer belt127may be transferred from the second transfer unit120bto a printing medium102. AlthoughFIG. 1illustrates the toner images are transferred from the photosensitive bodies115to118to the intermediate transfer belt127and then transferred from the intermediate transfer belt127to the printing medium102, which is an example of an indirect transfer method, it is possible to directly transfer images from the photosensitive bodies115to118to a printing medium. The photosensitive bodies115to118or the intermediate transfer belt127, on which toner images are formed, may be designated as image bearing members.

The printing medium102with an image transferred may be transferred along a transfer path106for the printing medium102to the fixing unit130to be heated and pressurized by fixing rollers131and132. Accordingly, the image may be fixed to the printing medium102, thereby completing an image forming process. The printing medium102may be contained in a feeding unit101.

A transfer process, in the image forming process, performed by the transfer units120aand120bis disclosed. The power supply unit140supplies transfer voltages to the first transfer unit120aand the second transfer unit120b. To transfer images formed on the photosensitive bodies115to118to the intermediate transfer belt127, the power supply unit140applies first transfer voltages to first transfer rollers121to124. The first transfer voltages have polarity opposite to that of the toner images on the surfaces of the photosensitive bodies115to118. The toner images on the surfaces of the photosensitive bodies115to118may be transferred to the intermediate transfer belt127by an electrostatic force provided by the first transfer voltages. When a second transfer voltage is supplied to a second transfer roller128by the power supply unit140, the toner images may be transferred from the intermediate transfer belt127to a surface of the printing medium102transferred along the transfer path106for the printing medium102.

The concentration of the transferred toner image may be affected by a transfer voltage. Due to various environmental factors such as a temperature and humidity, a desired concentration may deviate from a concentration of an actually outputted image. Accordingly, to output an image with a desired concentration, a concentration adjustment may be performed. An exemplary method of performing a concentration adjustment by using the detection device100is disclosed.

The detection device100detects a state of the toner image formed on the intermediate transfer belt127, for example, the concentration of the toner image. According to a result of comparing a concentration value of the toner image detected by the detection device100with a preset reference concentration value, the adjustment unit150controls the power supply unit140to control the transfer voltages supplied to the transfer units120aand120b.

While the detection device100is detecting the concentration of the toner image of the intermediate transfer belt127that is an image bearing member, a foreign substance such as scattered toner may stick to the surface of the detection device100and may contaminate the detection device100. Such contamination of the detection device100may cause a detection error, thereby preventing accurate concentration adjustment. Accordingly, to perform an accurate concentration adjustment, it may be necessary to prevent the contamination of the detection device100. A cleaner20(as illustrated inFIG. 2) for the detection device100may bean element for removing a pollutant attached to a detector10(see, for example,FIG. 2).

FIG. 2illustrates an exemplary detection device100included in the image forming apparatus ofFIG. 1according to an embodiment of the present invention.FIGS. 3 and 4illustrate a detector10that is an element of the detection device100.

Referring toFIG. 2, the detection device100may include the detector10detecting a state of a toner image I such as a concentration thereof and the cleaner20removing the pollutant P attached to the detector10.

The detector10detects the state of the toner image I such as concentration thereof. However, as described above, the detector10may be contaminated by the pollutant P while detecting the state of the toner image I. Referring toFIGS. 3 and 4, an exemplary occurrence of a detection error caused by the contaminated detection device100is disclosed.

Referring toFIG. 3, in a process of detecting the concentration of the toner image I on the intermediate transfer belt127performed by the detector10, a light emitting unit11emits light to the toner image I formed on the intermediate transfer belt127. As an example of the light emitting unit11, a light emitting diode (LED) or a semiconductor laser diode may be used. A light receiving unit13receives reflected light that is the light emitted from the light emitting unit11to the toner image I and reflected therefrom and detects the concentration of the toner image I from a variance of a light strength of the reflected light. A casing15contains the light emitting unit11and the light receiving unit13and a light window17formed of a transmission (or transparent) material is located on a part of the casing15. The light emitted from the light emitting unit11and the reflected light from the toner image I penetrate the light window17. The light window17may prevent penetration of the pollutant P outside the casing15into the casing15.

While the toner image I is being transferred onto the intermediate transfer belt127, the pollutant P such as scattered toner float around the detector10and a part thereof is attached to a surface of the light window17as illustrated inFIG. 4. When the pollutant P are attached to the surface of the light window17, the light emitted from the light emitting unit11or the reflected light from the toner image I are reflected from the pollutant P or refracts in such a way that the reflected light may not reach the light receiving unit13or a light strength of the reflected light reaching the light receiving unit13may not accurately reflect on the concentration of the toner image I.

Referring toFIG. 2, the cleaner20may reciprocate being in contact with the surface of the light window17. While the cleaner20is reciprocating, mechanical friction may be applied onto the pollutant P in contact with the cleaner20, thereby removing a part of the pollutant P attached to the light window17. However, by only using such mechanical friction, the pollutant P attached to the light window17may not be completely removed. Pollutant P detached from the light window17may be scattered and attached to the light window17. When the light window17is formed of a material to allow an occurrence of an electrostatic force due to the friction, such as a transparent polycarbonate, the pollutant P may be easily attached to the light window17.

According to an exemplary embodiment, the cleaner20of the detection device100may be formed to remove the pollutant P attached to the light window17by applying electrical fundamental forces or repulsive forces in addition to the mechanical friction to the pollutant P attached to the light window17. The cleaner20may include an adsorption unit21, a driving unit22transferring the adsorption unit21, a voltage applying unit23applying a voltage to the adsorption unit21, and a control unit24controlling the driving unit22and the voltage applying unit23.

The adsorption unit21may be in contact with the surface of the light window17and have a conductive material. For example, the material of the adsorption unit21may be conductive fibers. However, the material of the adsorption unit21is not limited thereto and may be various conductive materials. Since having the conductive material, the adsorption unit21may be electrified as a certain polarity by the voltage applying unit23. The adsorption unit21may be in the shape of a brush. The conductive material may indicate a material capable of being electrified as a certain voltage by a voltage applied by the voltage applying unit23. The adsorption unit21may include an antistatic material capable of preventing an occurrence of static electricity.

The driving unit22transfers the adsorption unit21in contact with the surface of the light window17to allow the adsorption unit21formed in the shape of a brush to wipe the surface of the light window17. The driving unit22transfers the adsorption unit21in a direction crossing a light emitting direction of the detector10, thereby removing the part of the pollutant P attached to the light window17by using mechanical friction.

The voltage applying unit23applies a voltage with certain polarity to the adsorption unit21having the conductive material. For example, the voltage applying unit23applies a first voltage having polarity opposite to that of the pollutant P, thereby electrifying the adsorption unit21with the polarity opposite to the pollutant P. Accordingly, electrical fundamental forces occur between the adsorption unit21and the pollutant P in such a way that the pollutant P are adsorbed to the adsorption unit21.

The control unit24controls whether the voltage applying unit23applies a voltage and the polarity of the voltage and controls whether the driving unit22drives and a driving direction.

FIGS. 5 and 7illustrate exemplary locations of the adsorption unit21of the detection device100.

Referring toFIG. 5, the adsorption unit21may be transferred to a first location21A for being in contact with the light window17and second locations21B-1and21B-2for releasing a contact with the light window17. The exemplary second locations21B-1and21B-2, as illustrated in the drawing, may include other locations when the adsorption unit21is transferred between to the left and right of the detector10. The control unit24controls the driving unit22to transfer the adsorption unit21to one of the first location21A and the second locations21B-1and21B-2. The control unit24determines whether the voltage applying unit23applies a voltage and the polarity of the voltage according to a location of the adsorption unit21. For example, when the adsorption unit21is located in the first location21A, the control unit24controls the voltage applying unit23to apply the first voltage to the adsorption unit21to adsorb the pollutant P. The first voltage, for example, may be a voltage with a polarity opposite to that of the pollutant P. Through this, a part of the pollutant P attached to the light window17may be removed by the mechanical friction with the adsorption unit21and a part thereof may be adsorbed onto the adsorption unit21due to the electrical fundamental forces of the adsorption unit21.

Referring toFIG. 6, when the adsorption unit21is located at one of the second locations21B-1and21B-2, the control unit24may control a separation of the pollutant P adsorbed onto the adsorption unit21. While the pollutant P adsorbed onto the adsorption unit21is not being eliminated or separated from the adsorption unit21, when the adsorption unit21is transferred to the first location21A, not only an adsorption efficiency may decrease but also the pollutant P adsorbed onto the adsorption unit21may contaminate more of the light window17. However, in accordance with an exemplary embodiment of the present invention, the pollutant P adsorbed onto the adsorption unit21is eliminated in one of the second locations21B-1and21B-2for releasing a contact with the light window17, thereby protecting the adsorption unit21from being contaminated by the pollutant P and allowing the adsorption unit21to be repetitively used.

The pollutant P adsorbed onto the adsorption unit21may be collected by pollutant collecting units25-1and25-2. The pollutant collecting units25-1and25-2may be arranged separately from the detector10. The pollutant collecting units25-1and25-2may include contact projections26-1and26-2projected in a direction crossing a transfer path of the adsorption unit21. For example, the adsorption unit21is in contact with contact projections26-1and26-2while being transferred from the first location2A to one of the second locations21B-1and21B-2or from one of the second locations21B-1and21B-2to the first location2A. Due to mechanical friction between the adsorption unit21and the contact projections26-1and26-2of the pollutant collecting units25-1and25-2, a part of the pollutant P adsorbed onto the adsorption unit21may be dropped onto the pollutant collecting units25-1and25-2.

A residual pollutant P may not be separated from the adsorption unit21despite the mechanical friction with the contact projections26-1and26-2due to electrical fundamental forces or repulsive forces. The voltage applying unit23may apply a second voltage for separating the pollutant P from the adsorption unit21to the adsorption unit21when the adsorption unit21is located in one of the second locations21B-1and21B-2. The voltage applying unit23may apply a third voltage for collecting the pollutant P attached to the adsorption unit21into the pollutant collecting units25-1and25-2to the pollutant collecting units25-1and25-2. As an example, the voltage applying unit23may apply a voltage with the same polarity as that of the pollutant P to the adsorption unit21located in one of the second locations21B-1and21-2, thereby generating electrical repulsive forces between the adsorption unit21and the pollutant P adsorbed onto the adsorption unit21. Due to such electrical repulsive forces, the pollutant P may be separated from the adsorption unit21and may be collected into the pollutant collecting units25-1and25-2. To allow the pollutant P to be efficiently collected into the pollutant collecting units25-1and25-2, the voltage applying unit23may apply a voltage with polarity opposite to the pollutant P to the pollutant collecting units25-1and25-2. Via this, electrical repulsive forces act between the adsorption unit21and the pollutant P, thereby collecting the pollutant P separated from the adsorption unit21into the pollutant collecting units25-1and25-2. As an example, the voltage applying unit23may apply a ground voltage, that is, 0 V to the adsorption unit21and apply a voltage with polarity opposite to the pollutant P to the pollutant collecting units25-1and25-2. Via this, the electrical repulsive forces between the adsorption unit21and the pollutant P are released and electrical repulsive forces are generated between the pollutant collecting units25-1and25-2. Due to the electrical repulsive forces acting between the pollutant collecting units25-1and25-2and the pollutant P, the pollutant P may be separated from the adsorption unit21and collected into the pollutant collecting units25-1and25-2. A voltage level of the voltage applying unit23and whether to apply a voltage may be controlled by the control unit24.

Toner forming the toner image I on the intermediate transfer belt127has one polarity such as negative, but the pollutants P such as toner scattered while forming the toner image I may have a positive polarity in addition to the negative polarity due to other environmental factors. When the pollutants P have both negative and positive polarities, adsorbing the pollutants P by the adsorption unit21may be performed several times. For example, the voltage applying unit23may periodically convert and apply a voltage with positive or negative polarity opposite to that of the pollutant P.

As an example, to allow the adsorption unit21to adsorb the pollutant P with negative polarity, the voltage applying unit23applies a voltage with positive polarity to the adsorption unit21located in the first location21A. When adsorbing the pollutant P with negative polarity by the adsorption unit21is finished, the adsorption unit21is transferred to the 2-1 location21B-1and a voltage with negative polarity is applied to the adsorption unit21in such a way that the pollutant P with negative polarity adsorbed onto the adsorption unit21are dropped onto the pollutant collecting unit25-1. The adsorption unit21from which the pollutant P with negative polarity are separated and removed is transferred to the first location21A. To allow the adsorption unit21to adsorb the pollutant P with positive polarity, the voltage applying unit23applies a voltage with negative polarity to the adsorption unit21. When adsorbing the pollutant P with positive polarity by the adsorption unit21is finished, the adsorption unit21is transferred to the 2-2 location21B-2and a voltage with positive polarity is applied to the adsorption unit21in such a way that the pollutant P with positive polarity adsorbed onto the adsorption unit21are dropped onto the pollutant collecting unit25-2. In other words, to allow the adsorption unit21to adsorb and remove the pollutant with positive and negative polarities attached to the light window17, the voltage applying unit23converts the polarity of a voltage applied to the adsorption unit21, depending on the location of the adsorption unit21and whether the pollutant P are adsorbed onto the adsorption unit21.

According to an exemplary embodiment, when the pollutant P have a plurality of polarities, the adsorption unit21reciprocates between the two pollutant collecting units25-1and25-2arranged interposing the detector10therebetween. However, it is not limited thereto and the adsorption unit21may reciprocate between the detector10and a single collecting unit25located on one side of the detector10and may remove the pollutant P with a plurality of polarities, as illustrated inFIG. 8. When the pollutants P substantially have one polarity, for example, a negative polarity, the adsorption unit21may reciprocate between the detector10and the single collecting unit25located on one side of the detector10and may remove the pollutant P with negative polarity.

Referring toFIG. 7, after the pollutant P adsorbed onto the adsorption unit21is dropped onto the second locations21B-1and21B-2as illustrated inFIG. 6, that is, separating the pollutant P from the adsorption unit21is finished, the voltage applying unit23may apply a fourth voltage to the adsorption unit21to prevent the pollutant P being attached to the light window17. The voltage applying unit23may electrify the light window17via the adsorption unit21. The pollutant P attached to the surface of the light window17is removed while adsorption and separation processes of the adsorption unit21are being performed as illustrated inFIGS. 5 and 6. However, as illustrated inFIG. 5, while adsorbing the pollutant P, due to friction with the adsorption unit21to which a voltage with polarity opposite to that of the pollutant P is applied, the surface of the light window17may be inadvertently electrified with a polarity opposite to that of the pollutant P. Due to this, the surface of the light window17may be in a state in which the pollutant P are attached thereto. Accordingly, the voltage applying unit23may electrify the surface of the light window17by applying the fourth voltage to the adsorption unit21to prevent attachment of the pollutant P to the surface of the light window17. As an example, the light window17may be electrified as a ground state. For this, the voltage applying unit23may apply a ground voltage to the adsorption unit21. When the light window17is electrified as the ground state, the pollutant P being attached to the light window17may be prevented though the pollutant P have both positive and negative polarities. As an example, the light window17may be electrified as the same polarity as the pollutant P. The voltage applying unit23may apply a voltage with the same polarity as the pollutant P to the adsorption unit21. When the pollutant P substantially have one polarity such as negative polarity, the surface of the light window17is electrified as the negative polarity same as the pollutant P, thereby preventing the pollutant P being attached to the surface of the light window17due to electrical repulsive forces.

FIG. 9illustrates a detection device1008according to an embodiment of the present invention. Referring toFIG. 9, the detection device100B may include the detector10, the cleaner20, a housing30, and a shutter31.

The housing30may contain the detector10and be installed in the image forming apparatus. The housing30may include an opening30abetween the light window17and the intermediate transfer belt127that is an image bearing member, to allow light to pass through.

The shutter31is for determining an exposure of the detector10and may open or close the opening30a. The shutter31protects the detector10from being exposed to and contaminated by the pollutant P such as toner by closing the opening30awhen the detector10does not operate. The shutter31allows light to pass through between the light window17and the intermediate transfer belt127by opening the opening30awhen the detector10operates.

The adsorption unit21may be installed on the shutter31. For example, the adsorption unit21may be installed on a surface of the shutter31facing the detector10. As the shutter31is transferred, the adsorption unit21installed on the shutter31may remove the pollutant P attached to the light window17. In other words, when the shutter31closes the opening30a, the adsorption unit21is in contact with a top of the light window17and adsorbs the pollutant P. When the shutter31opens the opening30a, the adsorption unit21is separated from the light window17and the pollutant P adsorbed onto the adsorption unit21may be dropped.

FIGS. 10A to 10Eillustrate exemplary operations of a detecting device, e.g., the detecting device100ofFIG. 2.FIG. 11is an exemplary a timing chart illustrating a direction of controlling the driving unit22, a sequence of turning on/off the driving unit22, and a voltage applying state of the voltage applying unit23according to the sequence ofFIGS. 10A to 10E.

Referring toFIG. 10Aand section1100inFIG. 11, the voltage applying unit23applies a positive voltage to the adsorption unit21and the driving unit22controls the adsorption unit21to reciprocate left and right while being in contact with the light window17. Due to the reciprocation of the adsorption unit21, friction is applied to the pollutant P attached to the light window17, and as a result thereof, the pollutant P attached to the light window17is separated from the light window17. A pollutant P with negative polarity separated from the light window17due to the reciprocation of the adsorption unit21and a pollutant P with negative polarity attached to the light window17are adsorbed onto the adsorption unit21due to electrical fundamental forces with the adsorption unit21with positive polarity.

Referring toFIGS. 10B and 1101inFIG. 11, the adsorption unit21adsorbing the pollutant P with negative polarity is transferred to the right side of the detector10and arrives at the first pollutant collecting unit25-1located on the right side of the detector10. While arriving at the first pollutant collecting unit25-1, the adsorption unit21is in contact with the contact projection26-1of the first pollutant collecting unit25-1and a part of the pollutant P adsorbed onto the adsorption unit21is preliminary dropped due to friction between the adsorption unit21and the contact projection26-1. While the adsorption unit21is transferred left toward the detector10, the adsorption unit21is in contact with the contact projection26-1of the first pollutant collecting unit25-1and a part of the pollutant P adsorbed onto the adsorption unit21is secondarily dropped due to friction between the adsorption unit21and the contact projection26-1. A residual part of the pollutant P, despite the friction with the contact projection26-1, may be dropped onto the first pollutant collecting unit25-1due to electrical fundamental forces or repulsive forces. As an example, in the second locations21B-1and21B-2, where the adsorption unit21arrives at the first pollutant collecting unit25-1as the section b illustrated inFIG. 11, a negative voltage opposite to the first location21A may be applied to the adsorption unit21, thereby generating electrical repulsive forces between the adsorption unit21and the pollutant P. Due to such electrical repulsive forces, the pollutant P with negative polarity may be separated from the adsorption unit21. As another example, though there is not shown in the drawings, a voltage applied to the adsorption unit21may be blocked or a ground voltage may be applied thereto and a positive voltage is applied to the first pollutant collecting unit25-1, thereby collecting the pollutant P into the first pollutant collecting unit25-1due to electrical fundamental forces generated between the pollutant P with negative polarity and the first pollutant collecting unit25-1.

Referring toFIG. 100and section1102ofFIG. 11, the adsorption unit21is transferred to the first location21A for being in contact with the light window17. A negative voltage is applied to the adsorption unit21and the adsorption unit21is controlled to reciprocate left and right while being in contact with the light window17. Due to friction with the adsorption unit21, the pollutant P attached to the light window17is separated. On the other hand, the pollutant P with positive polarity not adsorbed in the process illustrated inFIG. 10Amay be adsorbed onto the adsorption unit21to which the negative voltage is applied, due to electrical fundamental forces.

Referring toFIG. 10Dand section1103ofFIG. 11, while adsorbing the pollutant P with positive polarity, the adsorption unit21is transferred to the left side of the detector10and arrives at the second pollutant collecting unit25-2located on the left side of the detector10. While arriving at the second pollutant collecting unit25-2, the adsorption unit21is in contact with the contact projection26-2of the second pollutant collecting unit25-2and a part of the pollutant P adsorbed onto the adsorption unit21is preliminary dropped due to friction between the adsorption unit21and the contact projection26-2. While the adsorption unit21is transferred right toward the detector10, the adsorption unit21is in contact with the contact projection26-2of the second pollutant collecting unit25-2and an part of the pollutant P adsorbed onto the adsorption unit21is secondarily dropped due to friction between the adsorption unit21and the contact projection26-2. A residual part of the pollutant P despite the friction with the contact projection26-2may be dropped onto the second pollutant collecting unit25-2due to electrical fundamental forces or repulsive forces.

With exemplary processes illustrated inFIGS. 10A to 10D, the adsorption unit21has removed the pollutant P attached to the light window17. However, the light window17may inadvertently have a certain polarity due to a contact with the adsorption unit21. In this case, the light window17may be in a state in which the pollutant are firmly attached thereto. Accordingly, as illustrated inFIG. 10E, after the process of separating the pollutant P adsorbed onto the adsorption unit21, the polarity of the light window17is removed, thereby preventing the pollutant P with a polarity being attached to the light window17. As an example, the voltage applying unit23may apply a ground voltage to the adsorption unit21. As an example, when the pollutants P substantially have one polarity, the voltage applying unit23may apply a voltage with the same polarity as the pollutants P to the adsorption unit21.

On the other hand, pollutant removing operations of the detection device100may be performed in a certain condition. For example, when a detected calibration value of the detector10is changed, the cleaner20may be operated. Calibration may be defined an operation of adjusting a current of the light emitting portion11to allow the detector10to uniformly maintain a light-receiving value with respect to a certain reflector (not shown). Accordingly, when the calibration value is different from a certain reference value, since it can be expected that the light window17is contaminated, the cleaner20may be operated to remove the pollutant P attached to the light window17.

As an example, when there is no printing operation for more than a certain amount of time, the cleaner20may be operated. Due to characteristics of toner, when the toner is left as it is and there is no printing operation for more than a certain amount of time, the polarity of the toner inside the developing unit110is deteriorated, thereby decreasing transfer ability of the toner with respect to the photosensitive bodies111to115or the intermediate transfer belt127. According thereto, a large amount of toner may be scattered, which may contaminate the light window17of the detector10. Accordingly, when there is no operation for more than a certain amount of time, to remove the pollutant P attached to the light window17, the cleaner20may be operated.

Exemplary embodiments have been described with reference to the drawings. For example, in the described embodiments, the detector detecting concentration of the toner image has been described as the detector10but is not limited thereto. The detector may be optically detect a state of the toner image, for example, a detector for auto color registration detects toners with a plurality of colors are properly aligned on an image bearing member. According to an exemplary embodiment, an image forming apparatus forming a color image by using toners with colors of cyan, magenta, yellow, and black has been described but is not limited thereto. The image forming apparatus according to an exemplary embodiment may be applied to image forming apparatuses forming an image on a recording medium by using various methods such as image forming apparatuses using toner with a single color.