Patent ID: 12210302

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention may be not limited to the disclosed embodiments.

FIG.1may be a diagram illustrating an overall configuration of an image forming apparatus1according to an embodiment.FIG.2may be a diagram illustrating a main part of a control system of the image forming apparatus1.

The image forming apparatus1illustrated inFIGS.1and2may be a color image forming apparatus of an intermediate transfer system using an electrophotographic process technology. The image forming apparatus1primarily transfers toner images of colors of yellow (Y), magenta (M), cyan (C), and black (K) formed on a photosensitive drum213to an intermediate transfer belt221, superimposes the toner images of four colors on the intermediate transfer belt221, and then secondarily transfers the toner images to a recording material to form an image.

In the present embodiment, the image forming apparatus1employs a vertical tandem system in which the photosensitive drums213corresponding to the four colors of CMYK are arranged in series in the traveling direction (vertical direction) of the intermediate transfer belt221, and toner images of the colors are sequentially transferred to the intermediate transfer belt221in one procedure.

As illustrated inFIG.1, the image forming apparatus1includes an image reading unit11, an operation display unit12, an image processing unit13, a sheet feeding unit14, a sheet ejection unit15, a recording material conveyance unit16, a power supply unit17, an image forming unit20, a controller30, and the like.

The controller30performs overall control of the image forming apparatus1by controlling the image reading unit11, the operation display unit12, the image processing unit13, the sheet feeding unit14, the sheet ejection unit15, the recording material conveyance unit16, the power supply unit17, and the image forming unit20according to their functions.

The controller30includes a central processing unit (CPU)31as an arithmetic/control device, a read only memory (ROM)32as a main storage device, a random-access memory (RAM)33, and the like. The ROM32stores a basic program and basic setting data. Furthermore, the ROM32stores a program for achieving image forming processing such as a lubricant application control program. The CPU31reads a program corresponding to the processing content from the ROM32, develops the program in the RAM33, and executes the developed program, thereby controlling the operation of each functional block of the image forming apparatus1.

Note that a part or the entire processing executed by the controller30may be executed by an electronic circuit such as a digital signal processor (DSP), an application specific integrated circuit (ASIC), or a programmable logic device (PLD) provided according to the processing.

In the present embodiment, the function of each functional block may be achieved by cooperation between each hardware forming the functional block and the controller30. Note that some or all of the functions of the functional blocks may be achieved by the controller30executing a program.

The image reading unit11includes an automatic document feeder111called an auto document feeder (ADF), a document image scanner112(scanner), and the like.

The automatic document feeder111conveys a document placed on a document tray by a conveying mechanism and sends the document to the document image scanner112. The automatic document feeder111may continuously read images (including both sides) of a large number of documents placed on the document tray.

The document image scanner112optically scans a document conveyed onto a contact glass from the automatic document feeder111or a document placed on the contact glass, forms an image of reflected light from the document on a light receiving surface of an imaging element (e.g., charge coupled device (CCD)), and reads a document image. The image reading unit11generates input image data on the basis of a reading result by the document image scanner112.

The input image data may be subjected to predetermined image processing in the image processing unit13.

The operation display unit12includes, for example, a flat panel display with a touch panel. As the flat panel display, a liquid crystal display, an organic EL display, or the like may be used. The operation display unit12includes a display unit121and an operation unit122.

The display unit121displays various operation screens, image states, operation situations of functions, and the like in accordance with a display control signal input from the controller30.

The operation unit122includes various operation keys such as a numeric keypad and a start key, receives various input operations by a user, and outputs an operation signal to the controller30. The user may operate the operation display unit12to perform settings related to image formation such as document setting, image quality setting, magnification setting, application setting, output setting, and recording material setting.

The image processing unit13includes a circuit or the like that performs digital image processing according to initial setting or user setting on the input image data. For example, the image processing unit13performs tone correction on the basis of tone correction data under the control of the controller30. Furthermore, the image processing unit13performs various types of correction processing such as color correction, shading correction, density correction, and the like on the input image data. The image forming unit20may be controlled on the basis of the image data subjected to the processing described above.

The image forming unit20includes an image former21, an intermediate transfer part22, and a fixer23. The image former21forms a toner image by each color toner of a Y component, an M component, a C component, and a K component on the basis of input image data. The intermediate transfer part22transfers the toner image formed by the image former21to a recording material. The fixer23fixes the transferred toner image to the recording material.

Specifically, the image former21includes four image formers21Y,21M,21C, and21K for a Y component, an M component, a C component, and a K component. Since the image formers21Y,21M,21C, and21K have similar configurations, for convenience of illustration and description, common components are denoted by the same reference numerals, and Y, M, C, and K are added to the reference numerals to distinguish the components. Note that inFIG.1, only the components of the image former21Y for the Y component are denoted by reference numerals, and the reference numerals of the components of the other image formers21M,21C, and21K are omitted.

The image former21includes an exposure device211, a developing device212, the photosensitive drum213, a charging device214, a drum cleaning device215, and the like. Although not illustrated, the image former21may include a static eliminator for removing residual charge remaining on the surface of the photosensitive drum213after the primary transfer.

The photosensitive drum213is, for example, a negative charge type organic photoconductor (OPC) in which an under coat layer (UCL), a charge generation layer (CGL), and a charge transport layer (CTL) are sequentially laminated on a peripheral surface of an aluminum conductive cylindrical body (aluminum tube). The charge generation layer may be made of an organic semiconductor in which a charge generation material (e.g., phthalocyanine pigment) may be dispersed in a resin binder (e.g., polycarbonate), and generates a pair of positive charge and negative charge upon exposure by the exposure device211. The charge transport layer may be formed by dispersing a hole transport material (electron-donating nitrogen-containing compound) in a resin binder (e.g., polycarbonate resin), and transports positive charge generated in the charge generation layer to the surface of the charge transport layer.

The charging device214includes, for example, a corona discharge generator such as a scorotron charging device or a corotron charging device. The charging device214uniformly charges the surface of the photosensitive drum213to negative polarity by corona discharge.

The exposure device211includes, for example, an LED print head (LPH), and includes an LED array in which a plurality of light emitting diodes (LEDs) are linearly arranged, an LPH driving unit (driver IC) for driving each LED, a lens array for forming an image of light emitted from the LED array on the photosensitive drum213, and the like. One LED of the LED array corresponds to one dot of an image.

The exposure device211irradiates the photosensitive drum213with light corresponding to an image of each color component. The positive charge generated in the charge generation layer of the photosensitive drum213by receiving light irradiation may be transported to the surface of the charge transport layer, whereby the surface charge (negative charge) of the photosensitive drum213may be neutralized. As a result, an electrostatic latent image of each color component may be formed on the surface of the photosensitive drum213due to a potential difference from the surroundings.

The developing device212stores a developer (e.g., two-component developer containing toner and magnetic carrier) of each color component and attaches a toner of each color component to the surface of the photosensitive drum213to visualize the electrostatic latent image and form a toner image. Specifically, a developing bias voltage may be applied to a developer bearing member (e.g., developing roller (reference numeral omitted)), and an electric field may be formed between the photosensitive drum213and the developer bearing member. Then, due to the potential difference between the photosensitive drum213and the developer bearing member, the charged toner on the developer bearing member moves to and adheres to an exposed part on the surface of the photosensitive drum213. As a result, the electrostatic latent image on the photosensitive drum213may be visualized.

The drum cleaning device215removes transfer residual toner remaining on the surface of the photosensitive drum213after the primary transfer. A detailed configuration of the drum cleaning device215will be described later.

The intermediate transfer part22includes the intermediate transfer belt221, a primary transfer roller222, a plurality of support rollers223and224, a belt cleaning device225, a secondary transfer roller226, and the like.

The intermediate transfer belt221may be an image carrier that carries a toner image and may be a transfer object to which the toner image on the photosensitive drum213may be transferred. The intermediate transfer belt221includes an endless belt and may be stretched around the plurality of support rollers223in a loop shape. At least one of the plurality of support rollers223includes a driving roller, and the others include driven rollers. As the driving roller rotates, the intermediate transfer belt221travels at a constant speed.

The primary transfer roller222may be disposed on the inner peripheral surface side of the intermediate transfer belt221so as to face the photosensitive drum213of each color component. When the primary transfer roller222may be pressed against the photosensitive drum213with the intermediate transfer belt221interposed therebetween, a transfer nip N1(hereinafter referred to as “primary transfer part N1”) for transferring a toner image from the photosensitive drum213to the intermediate transfer belt221may be formed.

The support rollers223include the opposing roller224disposed opposite the secondary transfer roller226. The secondary transfer roller226may be disposed on the outer peripheral surface side of the intermediate transfer belt221and may be pressed against the opposing roller224with the intermediate transfer belt221interposed therebetween. As a result, a transfer nip N2(hereinafter referred to as “secondary transfer part N2”) for transferring the toner image from the intermediate transfer belt221to the recording material may be formed.

In the primary transfer part N1, the toner images on the photosensitive drums213are sequentially superimposed and primarily transferred onto the intermediate transfer belt221. Specifically, a primary transfer voltage may be applied to the primary transfer roller222, and a charge having a polarity opposite to that of the toner may be applied to the inner peripheral surface side of the intermediate transfer belt221(side in contact with primary transfer roller222), whereby the toner image may be electrostatically transferred from the photosensitive drum213to the intermediate transfer belt221.

Thereafter, when the recording material passes through the secondary transfer part N2, the toner image on the intermediate transfer belt221may be secondarily transferred to the recording material. Specifically, a secondary transfer voltage may be applied to the secondary transfer roller226, and a charge having a polarity opposite to that of the toner may be applied to the back surface side (side in contact with secondary transfer roller226) of the recording material, whereby the toner image may be electrostatically transferred from the intermediate transfer belt221to the recording material. The recording material to which the toner image has been transferred may be conveyed toward the fixer23.

The belt cleaning device225includes a belt cleaning blade (reference numeral omitted) that comes into sliding contact with the surface of the intermediate transfer belt221. The belt cleaning device225removes transfer residual toner remaining on the surface of the intermediate transfer belt221after the secondary transfer.

The fixer23includes, for example, an upper fixer231having a fixing surface side member disposed on a fixing surface (surface on which toner image may be formed) side of the recording material, a lower fixer232having a back surface side support member disposed on a back surface (surface opposite to fixing surface) side of the recording material, a heating source233that heats the fixing surface side member, a pressure contact/separation unit (not illustrated) that brings the back surface side support member into pressure contact with the fixing surface side member, and the like.

The recording material onto which the toner image has been secondarily transferred and which has been conveyed along a sheet passage may be heated and pressurized when passing through the fixer23. As a result, the toner image may be fixed to the recording material.

The sheet feeding unit14includes a sheet feeding tray141and a manual sheet feeder142. In the sheet feeding tray141, paper sheets (standard paper or special paper) identified on the basis of basis weight, size, and the like are stored for each preset paper type. A plurality of sheet feeding rollers (reference numerals omitted) are disposed in the sheet feeding tray141and the manual sheet feeder142. A large-capacity external sheet feeding device (not illustrated) may be connected to the manual sheet feeder142. The external sheet feeding device may be capable of feeding a continuous sheet such as a roll sheet, for example. The sheet feeding unit14sends the recording material fed from the sheet feeding tray141or the manual sheet feeder142to the recording material conveyance unit16.

The sheet ejection unit15includes a sheet ejection conveyance roller151and the like and ejects the recording material fed from the recording material conveyance unit16to the outside of the apparatus.

The recording material conveyance unit16includes a main conveyor161, a switchback conveyor162, a conveyor for back surface printing163, a sheet passage switching part (not illustrated), and the like. Apart of the recording material conveyance unit16may be incorporated into one unit together with the fixer23, for example, and may be detachably attached to the image forming apparatus1.

The main conveyor161includes a plurality of conveyance rollers (reference numerals omitted) including a loop roller part and a registration roller part as a recording material conveyance element that sandwiches and conveys a recording material. The main conveyor161conveys the recording material fed from the sheet feeding unit14to pass through the image forming unit20(intermediate transfer part22and fixer23) and conveys the recording material fed from the image forming unit20(fixer23) to the sheet ejection unit15or the switchback conveyor162.

The switchback conveyor162temporarily stops the recording material sent from the fixer23, reverses the conveyance direction, and conveys the recording material to the sheet ejection unit15or the conveyor for back surface printing163.

The conveyor for back surface printing163circularly conveys the recording material switched back by the switchback conveyor162to the main conveyor161. The recording material may be passed through the main conveyor161in a state where its back surface may be an image forming surface.

The sheet passage switching part (not illustrated) may be disposed on the downstream side of the fixer23in the recording material conveyance direction and switches the sheet passage depending on whether the recording material sent out from the fixer23may be discharged as it is, flipped and discharged, or conveyed to the conveyor for back surface printing163.

Specifically, the controller30controls the operation of the sheet passage switching part (not illustrated) on the basis of the processing content (single-sided/double-sided printing, face-up/face-down ejection, and the like) of the image forming processing.

The recording material fed from the sheet feeding unit14may be conveyed to the image forming unit20by the main conveyor161. Then, when the recording material passes through the secondary transfer part, the toner images on the intermediate transfer belt221are collectively transferred to a first surface (front surface) of the recording material, and fixing processing may be performed in the fixer23. The recording material on which an image may be formed may be ejected to the outside of the apparatus by the sheet ejection unit15. In a case of forming images on both surfaces of a recording material, the recording material on which an image may be formed on the first surface may be sent to the switchback conveyor162and may be flipped by returning to the main conveyor161through the conveyor for back surface printing163, and an image may be formed on a second surface (back surface).

The power supply unit17may be connected to a commercial AC power supply (not illustrated), converts AC power input from the commercial AC power supply into DC power, and supplies a necessary voltage to each unit.

FIG.3is a perspective view illustrating an example of the drum cleaning device215.FIG.4is a diagram schematically illustrating a configuration of the drum cleaning device215.

As illustrated inFIGS.3and4, the drum cleaning device215includes a cleaning unit90and a lubricant application unit80.FIG.3mainly illustrates a configuration of the lubricant application unit80and omits the cleaning unit90. Each component of the cleaning unit90and the lubricant application unit80may be attached to a storage case215ato be a frame body of the drum cleaning device215by an appropriate method. The drum cleaning device215may be integrally mounted on the image forming apparatus1as a photosensitive unit together with the photosensitive drum213, for example.

The present embodiment adopts a downstream application system in which the lubricant application unit80may be disposed downstream of the cleaning unit90in the rotation direction of the photosensitive drum213. The lubricant application method may be an upstream application system in which the lubricant application unit80may be disposed upstream of the cleaning unit90in the rotation direction of the photosensitive drum213.

The cleaning unit90includes a drum cleaning blade91that abuts on the surface of the photosensitive drum213. The drum cleaning blade91may be an elastic member formed by molding urethane rubber or the like into a flat plate shape and has a width substantially equal to the longitudinal width of the photosensitive drum213(main scanning direction). For example, the drum cleaning blade91may be disposed so as to be in sliding contact with the photosensitive drum213at a predetermined contact angle (such as 15°) from a counter direction (direction in which edge part may be stretched when photosensitive drum213rotates).

The drum cleaning blade91scrapes transfer residual toner remaining on the surface of the photosensitive drum213as the photosensitive drum213rotates during image formation. The scraped transfer residual toner may be sent to a waste toner collection container (not illustrated) by a toner collection screw92.

The lubricant application unit80includes a lubricant application brush81(lubricant application member), a solid lubricant82, a lubricant pressing part83, a fixing blade84, and the like. The lubricant application unit80scrapes off the solid lubricant82with the lubricant application brush81and applies the powdery lubricant to the surface of the photosensitive drum213. Note that instead of the lubricant application brush81, a lubricant application member made of foam may be applied.

The lubricant application brush81is, for example, a roller-like brush in which a base fabric in which fibers such as polyester are implanted may be wound around a core metal and has a width substantially equal to the axial width of photosensitive drum213. The lubricant application brush81may be fixed such that the surface of photosensitive drum213bites into the tip of the brush by a predetermined amount (e.g., biting amount: 0.5 mm to 1.5 mm). A drive motor85may be connected to the lubricant application brush81via a gear transmission mechanism86.

When the controller30controls the drive motor85, the lubricant application brush81rotates in a direction opposite to the rotation of photosensitive drum213(counter direction). The rotation speed of the drive motor85may be variable and may be controlled by the controller30.

The solid lubricant82may be obtained by solidifying a lubricant into a rod shape, and has a predetermined hardness (e.g., pencil hardness: equivalent to F to HB). In the present embodiment, the solid lubricant82may be formed in a rectangular parallelepiped shape and may be fixed to a lubricant holder87. As the lubricant, for example, zinc stearate (ZnSt) may be applied. The color of the surface of the solid lubricant82may be white.

The lubricant pressing part83includes, for example, a biasing member such as a compression spring. The lubricant pressing part83presses the solid lubricant82fixed to one end side of the biasing member toward the lubricant application brush81with a predetermined pressure. The pressing force by the lubricant pressing part83may be variably controlled.

The fixing blade84may be a flat plate-like member having a width substantially equal to the longitudinal width of the photosensitive drum213. A part of the fixing blade84in sliding contact with the photosensitive drum213includes an elastic body such as urethane rubber. The fixing blade84may be disposed on the downstream side of the lubricant application brush81in the rotation direction of the photosensitive drum213. The fixing blade84may be disposed so as to be in sliding contact with the photosensitive drum213at a predetermined contact angle (such as 50°) from a trailing direction (direction in an edge part may be dragged when photosensitive drum213rotates).

At the time of image formation, the lubricant may be scraped off from the surface of the solid lubricant82by rotation of the lubricant application brush81, and the scraped lubricant may be applied to the photosensitive drum213at a contact part with the photosensitive drum213. The applied lubricant may be leveled by the fixing blade84so as to have a uniform thickness. As consumption of the solid lubricant82progresses with durability, the height of the solid lubricant82decreases, and the lubricant holder87to which the solid lubricant82may be fixed rises (seeFIGS.12A to12C).

The amount (hereinafter referred to as “lubricant application amount”) of the solid lubricant82scraped off by the lubricant application brush81may be controlled by a lubricant application condition. The “lubricant application condition” includes, for example, the rotation speed of the lubricant application brush81(rotation speed of drive motor85) and the pressing force by the lubricant pressing part83. In the present embodiment, the lubricant application amount may be controlled by controlling the rotation speed of the lubricant application brush81. The rotation speed of the lubricant application brush81may be represented by, for example, a peripheral speed ratio (called lubricant θ) with respect to the photosensitive drum213.

At the initial stage of durability after the use of the drum cleaning device215may be started, no lubricant, toner, or the like adheres to the lubricant application brush81, and no deterioration occurs. Therefore, for example, the operation (e.g., rotation speed) of the lubricant application brush81may be controlled according to the ease of scraping of the solid lubricant82. The ease of scraping of the solid lubricant82may be represented by, for example, the hardness of the solid lubricant82.

The hardness of the solid lubricant82may be determined on the basis of the object color of the solid lubricant82. As a result of various studies on the characteristics (In particular, hardness of solid lubricant82) of the solid lubricant82, the present inventors have found that there may be a difference in the color of the solid lubricant82when quantified by a colorimeter even if the color may be the same white with the naked eye, and there may be a correlation between the hardness (ease of scraping) of the solid lubricant82and the object color of the solid lubricant82. The present inventors have conceived the main technical features of the present disclosure on the basis of such findings.

That is, in the present embodiment, the object color of the solid lubricant82in which the ease of scraping of the solid lubricant82may be directly reflected may be colorimetrically measured, and the operation of the lubricant application brush81may be controlled on the basis of the colorimetric result. In controlling the operation of the lubricant application brush81, it may be not necessary to consider external factors such as deterioration of the lubricant application brush81, and the operation of the lubricant application brush81may be accurately and appropriately controlled. The colorimetry of the object color of the solid lubricant82may be performed, for example, after the end of a print job when no image may be being formed.

Specifically, a colorimeter60may be disposed so as to face the solid lubricant82and receives reflected light (including correctly reflected light and diffusely reflected light) from the surface of the solid lubricant82. The colorimeter60determines the object color of the solid lubricant82on the basis of the reflectance (amount of light) of each wavelength component of the received reflected light. A colorimetric result in the colorimeter60may be transmitted to the controller30. The controller30controls the rotation speed of lubricant application brush81on the basis of the colorimetric result. Since the hardness (difficulty in scraping) of the solid lubricant82may be reflected in the colorimetric result of the colorimeter60, the controller30controls the rotation speed of the lubricant application brush81according to the hardness of the solid lubricant82. Note that a known colorimeter may be applied to the colorimeter60.

The colorimeter60may be provided at a position where the object color of the solid lubricant82may be measured in the lubricant application unit80. The colorimeter60may have a slit that limits the colorimetry region in the height direction of the solid lubricant82. Preferably, the colorimeter60may be disposed so as to partially perform colorimetry in the vicinity of a sliding contact part with the lubricant application brush81in the height direction of the solid lubricant82. As a result, since the ease of scraping of the solid lubricant82at present may be reflected in the colorimetric result, the rotation speed of the lubricant application brush81may be controlled to an appropriate value according to the ease of scraping of the solid lubricant82.

For example, as illustrated inFIG.5, the colorimeter60includes a light source61that irradiates the solid lubricant82with light L1, and a light receiver62that receives reflected light L2reflected by the surface of the solid lubricant82.

The light source61includes, for example, a light emitting diode. The light source61may include a light emitting diode and a condensing optical system such as a condensing lens. Furthermore, the light source61may include a light diffusion sheet or may include a line type light source in order to uniformly emit light in the width direction of the solid lubricant82. Note that the wavelength of the light emitting diode may be not particularly limited, but preferably includes a red wavelength component (such as 680 nm) in order to identify ease of scraping of the solid lubricant82.

The light receiver62includes, for example, a photodiode having sensitivity to a wavelength component of a specific color (e.g., red). The light receiver62may include, in addition to the photodiode, a spectroscopic optical system such as a diffraction grating or a prism and an optical filter that selectively transmits the wavelength of the reflected light L2.

Here, the “wavelength component of a specific color” may be preferably a wavelength component in which a significant difference appears depending on the hardness of the solid lubricant82, and is, for example, a red wavelength component. Note that a color other than red may be used as the specific color.

By providing the light source61and the light receiver62in the colorimeter60, colorimetry may be performed under the same illumination condition, so that the calculation load for determining the color of the solid lubricant82may be reduced, and the colorimetry accuracy may be stabilized.

Preferably, the colorimeter60may be disposed so as to face an end surface in the longitudinal direction of the solid lubricant82. That is, the end surface in the longitudinal direction of the solid lubricant82may be a colorimetric surface to be colorimetrically measured by the colorimeter60. As a result, the lubricant scraped off by the lubricant application brush81may be less likely to scatter to the colorimeter60, so that the lubricant may be prevented from adhering to the light source61or the light receiver62, and a normal colorimetry result may be obtained.

Furthermore, as illustrated inFIG.6, a shielding member63that physically shields scattering of the lubricant may be disposed between a colorimetric surface82aof the solid lubricant82and the colorimeter60. As the shielding member63, for example, an openable and closable shutter member that may be in an open state at the time of color measurement and in a closed state at the time of non-color measurement during image formation may be applied. Furthermore, for example, the shielding member63may be a transparent fixing plate capable of transmitting light. As a result, it may be possible to reliably prevent the lubricant from adhering to the light source61or the light receiver62of the colorimeter60.

FIG.7is a diagram illustrating an example of a relationship between the amount (R value) of the wavelength component of the specific color included in the colorimetric result and the ease of scraping (hardness) of the solid lubricant82. As illustrated inFIG.7, there may be a correlation between the amount (R value) of the wavelength component of the specific color included in the colorimetric result and the ease of scraping (hardness) of the solid lubricant82.FIG.7indicates that the solid lubricant82may be harder and less likely to be scraped as the amount of the wavelength component of the specific color may be smaller.

On the other hand, the optimum rotation speed of the lubricant application brush81may be determined in advance according to the ease of scraping (hardness) of the solid lubricant82. For example, the rotation speed of the lubricant application brush81may be set to be larger as the solid lubricant82may be less likely to be scraped. Therefore, the relationship as illustrated inFIG.8is obtained between the amount (R value) of the wavelength component of the specific color included in the colorimetric result and the optimum rotation speed of lubricant application brush81. The controller30sets the rotation speed of the lubricant application brush81with reference to the relationship illustrated inFIG.8.

As described above, at the initial stage of durability, the rotation speed of the lubricant application brush81may be controlled on the basis of the amount of the wavelength component of the specific color included in the colorimetric result, that is, the ease of scraping (hardness) of the solid lubricant82. On the other hand, for example, after the middle of durability in which the state of the lubricant application brush81(e.g., brush degradation (including adhesion of lubricant or toner)) and the decrease in pressing force by the lubricant pressing part83affect the lubricant application amount, the rotation speed of the lubricant application brush81may be controlled such that the actual consumption speed (lubricant scraping speed) of the solid lubricant82falls within an appropriate range.

In the present embodiment, the colorimetric surface82aof the solid lubricant82may be subjected to predetermined surface treatment, and the consumption speed of the solid lubricant82may be determined using the colorimetric result of the solid lubricant82. Specifically, the colorimetric surface of the solid lubricant82may be subjected to surface treatment such that the colorimetric result continuously changes with consumption of the solid lubricant82.

FIG.9is a diagram illustrating an example of surface treatment applied to the colorimetric surface82aof the solid lubricant82.

In the example illustrated inFIG.9, the colorimetric surface82aof the solid lubricant82may be partitioned into lubricant regions821to827divided into seven equal parts in the thickness direction of the solid lubricant82(consumption direction of solid lubricant82). The lubricant region821side may be the side that comes into contact with the lubricant application brush81.

No special surface treatment may be applied to the lubricant regions821to823. When the colorimetric region to be colorimetrically measured by the colorimeter60may be the lubricant region821to823, the colorimetric result may be dominated by the wavelength component based on the object color of the solid lubricant82.

On the other hand, in the lubricant regions824to827, a determination reference mark82M of an isosceles triangle filled with a specific color (e.g., red) may be formed. When the colorimetric region to be colorimetrically measured by the colorimeter60may be the lubricant region824to827, the colorimetric result may be dominated by the wavelength component based on the color of the determination reference mark82M included in the colorimetric region.

That is, in the colorimetric result of the colorimeter60, the amount of the wavelength component of the specific color may be clearly larger in the lubricant regions824to827than in the lubricant regions821to823. Therefore, on the basis of the amount of the wavelength component of the specific color included in the colorimetric result, whether the colorimetric region may be the lubricant region821to823in which the determination reference mark82M may be not formed or the lubricant region824to827in which the determination reference mark82M may be formed may be easily determined, for example, by comparing with a predetermined threshold.

Furthermore, in the lubricant region824to827, the area where the determination reference mark82M may be formed, that is, the area filled with a specific color increases as it goes farther away from the side close to the lubricant application brush81, and the colorimetric result continuously changes as the consumption of the solid lubricant82progresses. Therefore, which of the lubricant regions824to827may be the colorimetric region may be determined on the basis of the amount of the wavelength component of the specific color included in the colorimetric result.

Furthermore, by performing colorimetry of the solid lubricant82before and after executing a print job, the consumption speed of the solid lubricant82may be calculated on the basis of the displacement amount of the colorimetric region and the sliding distance of the lubricant application brush81during the print job. The controller30controls the rotation speed of lubricant application brush81such that the calculated lubricant consumption speed falls within an appropriate range.

Moreover, the colorimetric region directly represents the remaining amount of the solid lubricant82. That is, as illustrated inFIG.10, the amount (R value) of the wavelength component of the specific color included in the colorimetric result may be associated with the remaining amount of lubricant.FIG.10indicates that the R value increases and the remaining amount of lubricant decreases as the colorimetric region changes from the lubricant region821toward the lubricant region827. When the colorimetric region may be the lubricant region827and the remaining amount of lubricant may be small, it may be also possible to display on the display unit121or the like to notify that it may be time to replace the solid lubricant82, for example.

FIG.11is a flowchart illustrating an example of lubricant application control processing. This processing may be achieved, for example, by the CPU31executing a predetermined program stored in the ROM32as a print job ends in the image forming apparatus1.

In step S101ofFIG.11, the controller30controls the operation of the colorimeter60to perform colorimetry of the solid lubricant82. A colorimetric result corresponding to the colorimetric region in the solid lubricant82may be obtained.

For example, in the initial stage of durability, as illustrated inFIG.12A, since the lubricant region where the determination reference mark82M may be not formed may be the colorimetric region CR, a colorimetric result reflecting the hardness of the solid lubricant82may be obtained.

Further, for example, in the case of the middle to end of durability, as illustrated inFIGS.12B and12C, since the lubricant region where the determination reference mark82M may be formed may be a colorimetric region CR, a colorimetric result corresponding to the area of the determination reference mark82M included in the colorimetric region CR may be obtained.

In step S102, the controller30extracts a wavelength component of a specific color (e.g., red) from the colorimetric result acquired in step S101.

In step S103, the controller30determines whether the amount (R value) of the wavelength component of the specific color extracted in step S102may be equal to or less than a threshold value. When the R value may be equal to or less than the predetermined value (“YES” in step S103), the processing proceeds to step S104. When the R value may be not equal to or less than the predetermined value (“NO” in step S103), the processing proceeds to step S105.

The threshold value serving as the determination reference may be a value for determining whether the lubricant region821to823in which the determination reference mark82M may be not formed may be the lubricant region or the lubricant region824to827in which the determination reference mark82M may be formed may be the lubricant region and may be experimentally set in advance. For example, the threshold may be appropriately set by comparing the amount of the wavelength component of the specific color included in the colorimetric result when the colorimetric region CR may be the lubricant region821to823with the amount of the wavelength component of the specific color included in the colorimetric result when the colorimetric region CR may be the lubricant region824to827.

In step S104, the controller30sets the rotation speed of the lubricant application brush81on the basis of the colorimetric result. The controller30sets the rotation speed of the lubricant application brush81with reference to, for example, the relationship between the amount (R value) of the wavelength component of the specific color and the rotation speed (lubricant θ) of the lubricant application brush81illustrated inFIG.8.

According toFIG.8, as the wavelength component of the specific color included in the colorimetric result may be larger, the solid lubricant82may be more likely to be scraped, and the rotation speed of the lubricant application brush81may be set to be smaller. Conversely, as the wavelength component of the specific color included in the colorimetric result may be smaller, the solid lubricant82may be less likely to be scraped, and the rotation speed of the lubricant application brush81may be set to be larger.

As described above, when the colorimetric region may be the lubricant region821to823and the durability may be in the initial stage, the rotation speed of the lubricant application brush81may be set according to the ease of scraping of the solid lubricant82by the processing in steps S101to S104.

On the other hand, in the processing of step S104, when the amount of the wavelength component of the specific color may be not equal to or less than the predetermined value, that is, when the colorimetric region CR may be the lubricant region824to827and may be in the middle to end of durability, the processing of steps S105to S109are executed.

In step S105, the controller30estimates the lubricant consumption speed. The lubricant consumption speed may be calculated, for example, on the basis of the displacement amount of the colorimetric region CR from the previous time and the sliding distance of the lubricant application brush81during a print job (see following formula (1)).
Lubricant consumption speed=displacement amount of colorimetric region/sliding distance of lubricant application brush  (1)

The position of the current colorimetric region CR may be estimated on the basis of the amount (R value) of the wavelength component of the specific color included in the colorimetric result. In formula (1), the displacement amount of the colorimetric region may be represented by a difference between the position of the previous colorimetric region CR and the position of the current colorimetric region. Note that it may be also possible to, instead of calculating the position of the colorimetric region CR, obtain the displacement amount of the colorimetric region according to a difference between the previous R value and the current R value.

In step S106, the controller30determines whether the lubricant consumption speed estimated in step S105may be within an appropriate range. When the lubricant consumption speed may be within the appropriate range (“YES” in step S106), the processing proceeds to step S108. When the lubricant consumption speed may be outside the appropriate range (“NO” in step S106), the processing proceeds to step S107.

In step S107, the controller30adjusts the rotation speed of the lubricant application brush81such that the lubricant consumption speed falls within a predetermined range. For example, the controller30increases the rotation speed of the lubricant application brush81when the lubricant consumption speed estimated in step S105may be lower than the appropriate range and decreases the rotation speed of the lubricant application brush81when the lubricant consumption speed may be higher than the appropriate range.

In step S108, the controller30determines whether the remaining amount of lubricant may be equal to or more than a predetermined amount. When the remaining amount of lubricant may be equal to or more than the predetermined amount (“YES” in step S108), the series of lubricant application control processing may be ended. When the remaining amount of lubricant may be not equal to or more than the predetermined amount (“NO” in step S108), the processing proceeds to step S109.

In step S109, for example, the controller30displays a message prompting the replacement of the solid lubricant82on the display unit121and notifies that it may be time to replace the solid lubricant82.

As described above, in a case where the colorimetric region may be the lubricant region824to827and it may be the middle to end of durability, the rotation speed of the lubricant application brush81may be set according to the lubricant consumption speed to be performed by the processing of steps S101to S103and S105to S109.

As described above, the image forming apparatus1according to the present embodiment includes the following features singly or in appropriate combination.

That is, the image forming apparatus1includes the photosensitive drum213(image carrier), the solid lubricant82, the lubricant application brush81(lubricant application member) that scrapes off the solid lubricant82and applies the scraped solid lubricant82to the surface of the photosensitive drum213, the colorimeter60that performs colorimetry of the colorimetric surface82aof the solid lubricant82, and the controller30that sets A lubricant application condition (e.g., rotation speed of lubricant application brush81) so as to obtain a predetermined lubricant application amount on the basis of a colorimetric result obtained by the colorimeter60.

According to the image forming apparatus1, the ease of scraping (hardness) of the solid lubricant82and the lubricant consumption speed may be estimated accurately on the basis of the colorimetric result of the solid lubricant82, and an appropriate lubricant application condition may be set, so that an appropriate amount of lubricant may be applied to the photosensitive drum213without excess or deficiency. Furthermore, it may be possible to prolong the life of the photosensitive unit while maintaining constant image quality.

Furthermore, in the image forming apparatus1, the colorimetric surface82amay be an end surface in the longitudinal direction of the solid lubricant82. As a result, the lubricant scraped off by the lubricant application brush81may be less likely to scatter to the colorimeter60, so that the lubricant may be prevented from adhering to the colorimeter60, and a normal colorimetry result may be obtained.

Furthermore, in the image forming apparatus1, the colorimetric surface82amay be subjected to surface treatment such that the colorimetric result continuously changes with consumption of the solid lubricant82. As a result, the consumption situation of the solid lubricant82may be grasped on the basis of the colorimetric result, and, for example, an appropriate lubricant application condition may be set according to the lubricant consumption speed.

Furthermore, in the image forming apparatus1, the colorimeter60includes the light source61that irradiates the solid lubricant82with light, and the light receiver62that receives reflected light from the solid lubricant82. As a result, since the colorimetry may be performed under the same illumination condition, the calculation load for determining the color of the solid lubricant82may be reduced, and the colorimetric accuracy may be stabilized.

Furthermore, in the image forming apparatus1, the controller30sets the lubricant application condition in accordance with the ease of scraping of the solid lubricant82reflected in the colorimetric result. As a result, even when the hardness of the solid lubricant82changes as the consumption of the solid lubricant82progresses, an appropriate lubricant application condition may be set, so that an appropriate amount of lubricant may be applied to the photosensitive drum213.

Furthermore, in the image forming apparatus1, the controller30estimates the lubricant consumption speed on the basis of the colorimetric result and sets the lubricant application condition according to the estimated lubricant consumption speed. As a result, it may be possible to set an appropriate lubricant application condition according to the actual lubricant application situation.

Furthermore, in the image forming apparatus1, the lubricant application member may be the lubricant application brush81that rotates in sliding contact with the photosensitive drum213(image carrier), and the controller30sets the rotation speed of the lubricant application brush81. As a result, the lubricant application amount may be controlled easily.

Furthermore, in the image forming apparatus1, the controller30sets the lubricant application condition on the basis of the wavelength component of the specific color (e.g., red) included in the colorimetric result. As a result, it may be possible to easily recognize the difference in ease of scraping (hardness) of the solid lubricant82, and the calculation load therefor may be also reduced.

Furthermore, the image forming apparatus1includes the shielding member63that acts as a spatial shield between the solid lubricant82and the colorimeter60. Specifically, the shielding member63may be openable and closable, and may be in an open state at the time of colorimetry of the colorimetric surface82aby the colorimeter60and may be in a closed state at the time of non-colorimetry. As a result, adhesion of the lubricant to the colorimeter60may be prevented reliably, and a normal colorimetry result may be obtained.

Furthermore, the image forming apparatus1includes the controller30(remaining amount notifier) that estimates the remaining amount of the solid lubricant82on the basis of the colorimetric result and gives notification about the estimated remaining amount of lubricant. As a result, since an appropriate replacement time of the solid lubricant82may be known, it may be possible to prevent deterioration in image quality due to exhaustion of the solid lubricant82.

Although the invention made by the present inventors has been specifically described above on the basis of the embodiment, the present invention may be not limited to the above embodiment and may be modified without departing from the gist of the invention.

For example, an imaging device such as a CCD camera that images the surface of the solid lubricant82may be applied as the colorimeter60, and the colorimetry of the solid lubricant82may be performed by analyzing the image of the surface of the solid lubricant82captured by the imaging device.

Furthermore, the determination reference mark82M formed on the solid lubricant82may be any mark as long as the amount of wavelength components of a specific color included in the colorimetric result continuously changes with consumption of the solid lubricant82, and the shape and color are not particularly limited. For example, in the determination reference mark82M illustrated inFIG.9, the vertex of the isosceles triangle may be located on the side of the initial stage of durability (e.g., boundary between lubricant region821and lubricant region822).

Alternatively, in place of the determination reference mark82M having coloring, the colorimetric surface82amay be subjected to rough surface processing so that the amount of the wavelength component of the specific color continuously changes.

Although embodiments of the present invention have been described and illustrated in detail, the disclosed embodiments are made for purposes of illustration and example only and not limitation. The scope of the present invention should be interpreted not by the above description but by terms of the appended claims and may be intended to include all modifications within the meaning and scope equivalent to the claims.