Patent ID: 12192419

DESCRIPTION OF THE EMBODIMENTS

Now, embodiments of the present disclosure are described with reference to the accompanying drawings.

First Embodiment

FIG.1is a configuration view of an image forming apparatus100according to a first embodiment of the present disclosure.FIG.2is an explanatory diagram of a control unit9for controlling an operation of the image forming apparatus100. The control unit9is incorporated in the image forming apparatus100. The control unit9is an information processing device including a central processing unit (CPU)10, a read only memory (ROM)11, and a random access memory (RAM)12. The CPU10executes a computer program stored in the ROM11so as to control the operation of the image forming apparatus100. The RAM12provides a work area when the CPU10executes the computer program. The control unit9is connected to an operation unit13, a media sensor14, an image forming unit17, a fixing device170, and an image reading unit300.

The operation unit13is a user interface including an input interface. The input interface corresponds to key buttons for receiving user instruction information as input, or a touch panel for receiving the user instruction information as input. Further, the operation unit13may include an output interface in addition to the input interface. The output interface corresponds to a display, a speaker, or the like. The CPU10receives, from the operation unit13, for example, instructions on various settings and an operation start. The operation unit13is controlled by the CPU10so as to perform display of various screens such as a setting screen and an instruction screen on the display.

The image reading unit300includes a platen glass302and an image sensor301. On the platen glass302, an original to be read is placed with its surface to be read facing the platen glass302side. The image reading unit300is controlled by the CPU10so as to irradiate the original placed on the platen glass302with light to receive the reflected light by the image sensor301. The image sensor301generates image data indicating an image of the original based on the received reflected light. The image sensor301transmits the generated image data to the CPU10.

The image forming unit17includes image forming portions120a,120b,120c, and120d, laser scanners122a,122b,122c, and122d, an intermediate transfer belt130, primary transfer portions123a,123b,123c, and123d, a secondary transfer portion140, and the like. The image forming unit17is controlled by the CPU10so as to form an image on a medium. The fixing device170is controlled by the CPU10so as to fix the image to the medium.

The media on each of which the image is to be printed are stored in a plurality of sheet feeding cassettes220,221,222, and223. Types of the media to be stored in the respective sheet feeding cassettes220,221,222, and223may be the same or may be different from each other. On the sheet feeding cassettes220,221,222, and223, sheet feeding cassette opening/closing sensors180,181,182, and183for monitoring the opening or closing are provided, respectively.

The CPU10performs control of a drive source (not shown) for driving, for example, a conveyance roller to rotate in order to feed the media from the sheet feeding cassettes220,221,222, and223. The CPU10monitors the opening or closing of the sheet feeding cassettes220,221,222, and223based on detection results obtained by the sheet feeding cassette opening/closing sensors180,181,182, and183. The media sensor14is provided on a conveyance path15through which the media are fed. The CPU10detects a media characteristic such as a basis weight or a thickness of the conveyed medium based on a detection result obtained by the media sensor14. The media characteristic can also be said as a physical quantity of the media. The CPU10stores the detected media characteristic into the RAM12.

A basic image forming operation of the image forming apparatus100is described. The image forming apparatus100according to the first embodiment includes four sheet feeding cassettes220,221,222, and223. A description is given here of a case in which the media are fed from the sheet feeding cassette220.

The CPU10which has received a print start instruction from the operation unit13starts a feeding operation of feeding media from the sheet feeding cassette220. The sheet feeding cassettes220,221,222, and223include pick-up rollers151,152,153, and154, respectively. The pick-up rollers151,152,153, and154feed the media stored in the sheet feeding cassettes220,221,222, and223to the conveyance path. On the conveyance path extending from the sheet feeding cassettes220,221,222, and223to the secondary transfer portion140, there are arranged the media sensor14, conveyance rollers155, a pre-registration conveyance sensor160, and pre-registration conveyance rollers161in the stated order from the upstream of a conveying direction of the media.

The CPU10drives a motor serving as a drive source in response to the start of the feeding operation so as to rotate the pick-up roller151, to thereby feed the media one by one from the sheet feeding cassette220to the conveyance path. When the fed medium passes through a detection position of the media sensor14, an output value corresponding to the media characteristic (physical quantity) is output. The CPU10detects the type of media based on the output value (detection result) obtained by the media sensor14, and performs image formation in an image forming condition which is based on the detected type of media. For example, the CPU10controls an image forming speed or controls a target temperature of the fixing device170based on the type of media.

The image forming speed is a speed determined in advance in accordance with the type of media. The image formation and the media conveyance are performed at a speed corresponding to the image forming speed. The image forming speed is set to, for example, 300 mm/sec when the media are plain paper or thin paper, and is set to, for example, 150 mm/sec when the media are thick paper. The target temperature of the fixing device170is set in accordance with the type of media. The target temperature of the fixing device170is set to be relatively lower in the case of the thin paper as compared to the target temperature for the plain paper, and is set to be relatively higher in the case of the thick paper as compared to the target temperature for the plain paper.

The image forming portions120a,120b,120c, and120dstart the image forming operation so as to meet the timing at which the medium reaches the secondary transfer portion140. The image forming portion120aforms a yellow image. The image forming portion120bforms a magenta image. The image forming portion120cforms a cyan image. The image forming portion120dforms a black image. The image forming portions120a,120b,120c, and120dare cartridge devices which can be mounted to and removed from a main body of the image forming apparatus100by the user.

The image forming portions120a,120b,120c, and120dhave the same configuration. Each of the image forming portions120a,120b,120c, and120dincludes a photosensitive member, a charging roller, and a developing device. The photosensitive members are uniformly charged by the charging rollers, and then electrostatic latent images are formed on the photosensitive members by laser light radiated from the laser scanners122a,122b,122c, and122d, respectively. The developing devices develop the electrostatic latent images by toner (developer). In this manner, toner images are formed on the photosensitive members, respectively. The toner images formed in the image forming portions120a,120b,120c, and120dare transferred onto the intermediate transfer belt130through application of a primary transfer voltage to the primary transfer portions123a,123b,123c, and123d. The intermediate transfer belt130is rotated, and the toner images are transferred from the photosensitive members of the respective image forming portions120a,120b,120c, and120dat timings corresponding to a rotation speed. Accordingly, the toner images of the respective colors are transferred in a superimposed manner onto the intermediate transfer belt130so that the intermediate transfer belt130bears a full-color toner image. The intermediate transfer belt130is rotated so that the borne toner image is conveyed to the secondary transfer portion140.

The CPU10causes the conveyance rollers155to convey the medium fed from the sheet feeding cassette220to the secondary transfer portion140. At this time, the CPU10detects a position of the medium based on the detection result obtained by the pre-registration conveyance sensor160. The CPU10controls the conveyance of the medium so that, based on the detected position of the medium and the position of the toner image on the intermediate transfer belt130, a leading edge of the medium and a leading edge of the toner image match each other at the secondary transfer portion140. For example, when the medium is detected by the pre-registration conveyance sensor160at a timing at which the medium reaches the secondary transfer portion140earlier than the toner image, the CPU10stops the medium for a predetermined time period at the pre-registration conveyance rollers161. The CPU10restarts the conveyance of the medium by the pre-registration conveyance rollers161after the predetermined time period has elapsed, and controls a transfer position of the toner image onto the medium.

The secondary transfer portion140is applied with a secondary transfer voltage so that the toner image is transferred from the intermediate transfer belt130onto the medium. The medium having the toner image transferred thereon is conveyed to the fixing device170. The fixing device170applies heat and pressure to the toner image so that the toner image is fixed to the medium. The CPU10conveys the medium having the image fixed thereto by the fixing device170to the downstream. A sheet conveyance sensor171is arranged on the downstream side of the fixing device170. On the downstream side of the sheet conveyance sensor171, the conveyance path is divided into a conveyance path230and a conveyance path231. Thus, a flapper172is provided. The user gives in advance, from the operation unit13, an instruction on to which of the conveyance path230or the conveyance path231the medium is conveyed.

When the CPU10detects that the medium has reached the detection position of the sheet conveyance sensor171based on the detection result obtained by the sheet conveyance sensor171, the CPU10determines to which of the conveyance path230or the conveyance path231the medium is conveyed. The CPU10operates the flapper172based on the determination result, and conveys the medium to any of the conveyance path230or the conveyance path231. For example, when an instruction on duplex printing is given through the operation unit13, the CPU10conveys the medium to the conveyance path230when printing on a first surface of the medium is ended. When printing on both surfaces of the medium is ended in the duplex printing, or when an instruction on simplex printing is given, the CPU10conveys the medium to the conveyance path231.

The medium conveyed to the conveyance path231is conveyed to further downstream by conveyance rollers232of the conveyance path231, and is discharged as a printed product onto a sheet discharge tray196. The conveyance path230includes reversing conveyance rollers162, a flapper173, and a reversing portion A. The medium conveyed to the conveyance path230is conveyed to the reversing portion A by the reversing conveyance rollers162. When the medium is drawn into the reversing portion A, the flapper173is switched. Further, the reversing conveyance rollers162are rotated backward so that the medium is switched back. In this manner, the medium is conveyed toward the secondary transfer portion140. In this case, the surface of the medium is inverted so that image formation is allowed to a second surface different from the first surface. After that, an image is formed on the second surface of the medium similarly to the first surface, and the medium is discharged as a printed product onto the sheet discharge tray196. A length of the medium in the conveying direction is required to be shorter than a length L of the reversing portion A.

The CPU10monitors the detection result obtained by the sheet feeding cassette opening/closing sensor180so as to detect the opening or closing of the sheet feeding cassette220. In this manner, the CPU10can also perform control so as to prevent the media feeding operation from being started when the sheet feeding cassette220is open. The same holds true also when the media are fed from the sheet feeding cassette221,222, or223.

<Fixing Device>

FIG.3is an explanatory view of a configuration of the fixing device170. The fixing device170includes an assembly and a pressure roller205. The assembly includes a heater holder207, a fixing heater204, and a fixing film203serving as an elastic layer. The heater holder207is a U-shaped member extending in a depth direction ofFIG.3. The fixing heater204is fixed and arranged on a lower surface of the heater holder207along a longitudinal direction of the heater holder207. The pressure roller205includes a core metal extending in the longitudinal direction of the heater holder207. In the pressure roller205, both end portions of the core metal are arranged between side plates of the fixing device170so as to be freely rotatable by bearings. The fixing heater204is arranged on the pressure roller205side inside of the fixing film203so as to be parallel to the pressure roller205. The fixing heater204and the fixing film203are urged by a predetermined pressing force toward the pressure roller205side.

The fixing heater204is brought into pressure-contact with the pressure roller205across the fixing film203so that a fixing nip portion206having a predetermined width is formed. The pressure roller205is driven to rotate by a drive mechanism (not shown) at a predetermined circumferential speed in a counterclockwise direction. The fixing film203is rotated in a clockwise direction in association with the rotation of the pressure roller205. The medium is applied with pressure and heat at the fixing nip portion206so that the toner image is fixed, and is conveyed from the fixing device170to the downstream side due to the rotation of the pressure roller205.

The fixing heater204has a configuration in which a resistance heating element is formed on a ceramic substrate. A temperature sensor208is provided in abutment against the fixing heater204. The CPU10detects a temperature of the fixing heater204based on a detection result obtained by the temperature sensor208. The CPU10controls, based on the detected temperature of the fixing heater204, power to be supplied to the fixing heater204so that the fixing heater204reaches a predetermined target temperature. The CPU10performs feedback control on the temperature of the fixing heater204as described above.

The target temperature of the fixing heater204is determined based on the type of media to be passed, an environment temperature, and the like. The CPU10determines the target temperature based on the type of media set through the operation unit13or on the media characteristic detected by the media sensor14. When the media are thin paper thinner than plain paper, the target temperature of the fixing heater204is determined to be lower than the target temperature for the plain paper, and when the media are thick paper thicker than the plain paper, the target temperature of the fixing heater204is determined to be higher than the target temperature for the plain paper. When a sensor for measuring the environment temperature is provided to the image forming apparatus100, the CPU10determines the target temperature in consideration of also the environment temperature in addition to the type of media (or the media characteristic).

<Media Sensor>

FIG.4is an explanatory view of a configuration of the media sensor14. The media sensor14is an optical sensor including a light emitting diode (LED)481, a photodiode480, and a guide member483. The LED481serves as a light emitting portion. The photodiode480serves as a light receiving portion. The guide member483guides the supply of a medium S. The LED481irradiates the medium S with light. The photodiode480receives the reflected light reflected by the medium S. The photodiode480outputs an electrical signal corresponding to the received reflected light.

The CPU10obtains the electrical signal output from the photodiode480as the output value of the media sensor14. The output value is a value corresponding to the media characteristic. The CPU10detects the media characteristic of the media being passed (material, thickness, or the like of the medium S) based on the output value, and distinguishes the type of the medium S. The CPU10adjusts the image forming condition based on the distinguished type of the medium S. For example, the CPU10controls the image forming speed to an optimum speed and determines the target temperature of the fixing device170.

When the media sensor14is used, the user is not required to set the type of media through use of the operation unit13. Accordingly, in the image forming apparatus100according to the first embodiment, a media automatic detection mode of automatically distinguishing the type of media by the media sensor14is set as the default operation mode. Depending on the type of media, the media sensor14may erroneously detect the media, and the quality of the printed product may be reduced. Accordingly, as the operation mode, the user can set a user instruction mode of manually setting the type of media. In order to distinguish the type of media by the media sensor14, it is required that one or more sheets be caused to pass through the detection position of the media sensor14.

The configuration of the media sensor14is not limited to that ofFIG.4. For example, the media sensor14may be formed by combining the optical sensor including the light emitting portion and the light receiving portion and an ultrasonic sensor using a piezoelectric device or the like. The ultrasonic sensor allows detection of the basis weight of the media, and thus the detection accuracy of the media characteristic (type) is improved. Further, a sensor for detecting another media characteristic may be combined with the media sensor14.

<Tone Correction>

Tone correction refers to calibration for adjusting the density of the image to be formed by the image forming apparatus100. When the tone correction is executed, a plurality of image forming conditions affecting the density (color) of the image are updated. In this case, transfer efficiency at the time of transferring the toner image onto the medium and a change in color balance of the image at the time of performing fixing by the fixing device170are corrected. The image forming condition has an optimum value which varies depending on the media characteristic such as the basis weight or the surface property of the media. Accordingly, it is required to perform the calibration for each media characteristic (each type of media).

In order to perform the tone correction, an adjustment chart is created by printing a test image on a medium. The color of the adjustment chart is measured by the image reading unit300. The medium to be used for the adjustment chart is the medium having the media characteristic (type) selected when the tone correction is executed. For example, at the time of the tone correction of plain paper, the test image is printed on the plain paper, and at the time of the tone correction of thick paper or coated paper, the test image is printed on the thick paper or the coated paper.

The CPU10derives a correction parameter (correction value) for eliminating a difference between a color measurement result obtained by the image reading unit300and a target value stored in advance in the ROM11, and stores the correction parameter (correction value) into the RAM12. The correction parameter is read out at the time of the subsequent print job in accordance with the media characteristic of the media to be used, and is applied to the adjustment of the image forming condition.

In the first embodiment, the color of the test image is measured through use of the image reading unit300mounted to the image forming apparatus100, but the color may be measured through use of an external color measurement device and a print server. Further, there may be employed a configuration in which the color of the test image is measured by providing a color measurement device on the conveyance path (for example, on the conveyance path231) through which the media are conveyed of the image forming apparatus100.

In the first embodiment, the detection result obtained by the media sensor14is stored into the RAM12for each sheet feeding cassette. At the time of the tone correction, the user selects the sheet feeding cassette. Accordingly, a selection screen for selecting a sheet feeding cassette is displayed on the display of the operation unit13. In the selection screen, a selectable sheet feeding cassette and a non-selectable sheet feeding cassette are displayed in a distinguishable manner based on the detection result.

FIG.5AtoFIG.5CandFIG.6are exemplary views of the selection screen for selecting the sheet feeding cassette in which the media to be used in the tone correction have been stored.FIG.5Ashows an example of a media selection screen. Though the media selection screen, the media characteristic (type of media) to be used in the image formation is selected. In the media selection screen ofFIG.5A, any of a selection button501for “plain paper,” a selection button502for “thick paper,” or a selection button503for “coated paper” can be selected. When any of the selection button501,502, or503is selected and an “OK” button504is pressed, in the related art, a sheet feeding cassette selection screen exemplified inFIG.5BorFIG.5Cis displayed. A description is given here of a case in which the “plain paper” is selected.

FIG.5Bshows an example of the sheet feeding cassette selection screen in a case in which the image forming apparatus100has no media sensor14mounted thereon. This sheet feeding cassette selection screen displays that the type of media required for the tone correction is the plain paper, and also displays the size and the media characteristic (type of media) of the media stored in each of the sheet feeding cassettes220to223at present. “Sheet feeding cassette” buttons505and507for the sheet feeding cassettes in which the plain paper to be used in the tone correction is stored are selectable. “Sheet feeding cassette” buttons506and508for the sheet feeding cassettes in which media other than the plain paper to be used in the tone correction are stored are grayed out so as not to be selectable. Accordingly, the user can select one of the selectable sheet feeding cassettes to be used in the tone correction. When the user selects the sheet feeding cassette, the medium is fed from the selected sheet feeding cassette, and the test image for the tone correction is printed thereon.

FIG.5Cshows an example of the related-art sheet feeding cassette selection screen in a case in which the image forming apparatus100has the media sensor14mounted thereon. Similarly toFIG.5B, this sheet feeding cassette selection screen displays that the type of media required for the tone correction is the plain paper, and also displays the size of the media stored in each of the sheet feeding cassettes220to223. However, the media characteristics (types of media) of the media stored in the respective sheet feeding cassettes220to223are all displayed as “automatic.” In the image forming apparatus100having the media sensor14mounted thereon, the setting of “automatic” for detecting the media characteristic by the media sensor14is prepared. Through use of this setting, the user can use the image forming apparatus100without being conscious of the media characteristic of the media stored in the sheet feeding cassette. However, the user cannot recognize the media characteristic, and hence the sheet feeding cassette in which the plain paper is stored is unknown as illustrated inFIG.5C. Accordingly, the user cannot select one of the “sheet feeding cassette” buttons509to512for the sheet feeding cassette in which the media for use in performing the tone correction have been stored.

In the first embodiment, when the type of media is selected in the media selection screen ofFIG.5A, the sheet feeding cassette selection screen exemplified inFIG.6is displayed. A description is given here of a case in which the “plain paper” is selected from the media selection screen. Similarly toFIG.5C, the sheet feeding cassette selection screen ofFIG.6displays that the type of media required for the tone correction is the plain paper, and also displays the size of media stored in each of the sheet feeding cassettes220to223. The media characteristic (types of media) of the media stored in the sheet feeding cassette222is displayed as “PLAIN PAPER”. Further, the media characteristics (types of media) of the media stored in the respective sheet feeding cassette220,221,223are all displayed as “automatic.”. However, grayed-out and non-selectable “sheet feeding cassette” buttons514and516and selectable “sheet feeding cassette” buttons513and515are present.

The grayed-out “sheet feeding cassette” buttons514and516are buttons for sheet feeding cassettes for which the detection result obtained by the media sensor14and stored in the RAM12indicates media other than the plain paper. Accordingly, those media cannot be used in the tone correction of this time, and thus the “sheet feeding cassette” buttons514and516are not selectable. The “sheet feeding cassette” button515for the sheet feeding cassette for which the user has set the media characteristic and the “sheet feeding cassette” button513for the sheet feeding cassette for which the detection result obtained by the media sensor14has been the plain paper are selectable because the media can be used in the tone correction of this time. That is, the button for the sheet feeding cassette for which it is confirmed that the media usable in the tone correction are stored is selectable.

FIG.7is a flow chart for illustrating print processing accompanied by the tone correction. The sequence of this processing is stored in the ROM11as a computer program, and is executed by the CPU10. A description is given here of the tone correction as an example, but similar processing can be performed even for other correction of the image forming condition, for example, color misregistration.

When the image forming apparatus100is powered on, the CPU10obtains media information on the media stored in each of the sheet feeding cassettes220to223, which is stored in the RAM12(Step S101).FIG.8is an exemplary table of the media information. The media information includes the size of media, the media characteristic, and the detection result obtained by the media sensor14. The media characteristic indicates the type of media, but when the media characteristic is “automatic,” there is employed a setting in which the detection result obtained by the media sensor14is used. In the first embodiment, “automatic” is set as the default value of the media characteristic.

Symbol “-” is set as the detection result obtained by the media sensor14of the third sheet feeding cassette. This symbol indicates that the media characteristic is not “automatic,” and hence there is no detection result obtained by the media sensor14. A word “unknown” is set as the detection result obtained by the media sensor14of the fourth sheet feeding cassette. This word indicates that no medium has yet to be fed from the corresponding sheet feeding cassette, and hence there is no detection result obtained by the media sensor14. The section of the detection result obtained by the media sensor14is set when one or more media is fed so that the media sensor14detects the one or more media.

The CPU10determines whether or not a media type setting screen has been invoked through the operation unit13(Step S102). When the media type setting screen has been invoked (Step S102: Y), the CPU10displays the media type setting screen on the operation unit13, and performs the setting of the media type (Step S106). Details of the setting of the media type are described later. When the media type setting screen has not been invoked (Step S102: N), or after the setting of the media type is finished, the CPU10determines the presence or absence of a tone correction execution requirement (Step S103). The tone correction execution requirement is input by the user through use of the operation unit13. When the tone correction execution requirement is input, for example, the media selection screen ofFIG.5Ais displayed.

When the tone correction execution requirement is present (Step S103: Y), the CPU10executes the tone correction to be described later (Step S107). When the tone correction execution requirement is absent (Step S103: N), or after the tone correction is executed, the CPU10determines whether or not the print job has been input (Step S104). When the print job has been input (Step S104: Y), the CPU10executes the print job to be described later (Step S105). When no print job has been input (Step S104: N), or after the print job is ended, the CPU10ends the processing. After the processing is ended, the CPU10may return to the process step of Step S102so as to determine whether or not the media type setting screen has been invoked through the operation unit13.

FIG.9is a flow chart for illustrating the media type setting processing of Step S106.FIG.10is an exemplary view of the media type setting screen. In the media type setting processing, as exemplified inFIG.10, the media characteristic of the media stored in each of the sheet feeding cassettes220to223is set. The image forming apparatus100according to the first embodiment includes four sheet feeding cassettes220to223, and the media characteristic of the media stored in each of the sheet feeding cassettes220to223can be set. When the user recognizes the media characteristic such as the plain paper or the thick paper, the user sets the type of media stored in the sheet feeding cassette from the setting screen. Further, “automatic” indicating the media automatic detection mode to be performed by the media sensor14included in the image forming apparatus100is also selectable through the media type setting screen.

When “automatic” is selected from the media type setting screen (Step S201: Y), the CPU10sets the media characteristic to “automatic,” and sets the detection result obtained by the media sensor14of the media information (FIG.8) to “unknown” (Step S202). When an item other than “automatic” is selected from the media type setting screen (Step S201: N), the CPU10registers the selected type of media as the media characteristic (Step S203). As described above, the type of media (media characteristic) is set through use of the media type setting screen ofFIG.10.

FIG.11is a flow chart for illustrating the processing to be performed when the print job is executed in Step S105.

When the print job is input, the CPU10refers to the media information (FIG.8) stored in the RAM12to determine whether or not the media characteristic is set to “automatic” (Step S301). When the media characteristic is “automatic” (Step S301: Y), the CPU10automatically detects the media characteristic by the media automatic detection mode performed by the media sensor14(Step S302). The CPU10writes a detection result of the media characteristic obtained by the media sensor14into the media information of the RAM12(Step S303). The CPU10sets the image forming condition based on the detection result of the media characteristic obtained by the media sensor14(Step S304). When the media characteristic is not set to “automatic” (Step S301: N), the CPU10sets the image forming condition based on the media characteristic set in the media information (Step S305).

The CPU10which has set the image forming condition forms an image on the medium in accordance with the print job (Step S306). The CPU10repeatedly performs the process steps of from Step S301to Step S306until the final sheet of the print job (Step S307: N). After the CPU10ends the image forming processing until the final sheet of the print job (Step S307: Y), the CPU10ends the processing corresponding to the print job.

FIG.12is a flow chart for illustrating the tone correction processing of Step S107. The tone correction is started when the type of media is selected from the media selection screen ofFIG.5A.

The CPU10which has started the tone correction selects the media characteristic required for the tone correction in accordance with the type of media selected from the media selection screen (Step S401). The CPU10reads out, from the media information, the media detection result and the media characteristic of the media stored in each of the sheet feeding cassettes220to223(Step S402). The CPU10compares the media characteristic selected in the process step of Step S401with the media characteristic read out in Step S402, and displays, as exemplified inFIG.6, the sheet feeding cassette selection screen in which the selectable sheet feeding cassette and the non-selectable sheet feeding cassette are distinguished from each other (Step S403).

The user gives, through the operation unit13, an instruction on the sheet feeding cassette in which the media to be used in the tone correction are stored from the sheet feeding cassette selection screen. The CPU10obtains, from the operation unit13, the instruction on the sheet feeding cassette in which the media to be used in the tone correction are stored, and determines the sheet feeding cassette to be used (Step S404: Y). The CPU10starts the feeding of the medium from the determined sheet feeding cassette so as to execute the tone correction (Step S405). The CPU10prints the test image on the medium so as to create the adjustment chart. The color of the adjustment chart is measured by the image reading unit300. The CPU10performs the tone correction based on the color measurement result of the adjustment chart obtained by the image reading unit300.

As described above, the image forming apparatus100allows the user to select an appropriate sheet feeding cassette even in the media automatic detection mode of performing the setting for detecting the media characteristic by the media sensor14. Accordingly, the image forming apparatus100can form the test image on an appropriate type of medium, and can adjust the image forming condition. Thus, the image forming apparatus100can prevent the quality of the printed product from being reduced.

The instruction on the media automatic detection mode or the like can also be set from, other than the operation unit13, an external device such as a personal computer including a printer driver. Further, even when the image forming apparatus100has a configuration in which the media are fed not only from the sheet feeding cassette but also from a manual feed tray, the first embodiment can be applied thereto so that a similar effect can be obtained. Moreover, as long as the image forming apparatus100is configured to perform, other than the tone correction, calibration of printing the test image on the medium, the first embodiment can be applied thereto so that a similar effect can be obtained.

Second Embodiment

Configurations of the image forming apparatus100and the control unit9in a second embodiment of the present disclosure are similar to those of the first embodiment, and hence description thereof is omitted. The image forming apparatus100according to the second embodiment displays, when the sheet feeding cassette to be used is selected, the detection result obtained by the media sensor14on the sheet feeding cassette selection screen. Accordingly, the user can refer to the detection result obtained by the media sensor14so as to recognize the usable sheet feeding cassette, and can determine the sheet feeding cassette to be used.

When a predetermined medium (in this case, the “plain paper”) is selected from the media selection screen ofFIG.5A, the CPU10displays the sheet feeding cassette selection screen exemplified inFIG.13on the operation unit13. Similarly toFIG.6, the sheet feeding cassette selection screen displays that the type of media required for the tone correction is the plain paper, and also displays the size of media stored in each of the sheet feeding cassettes220to223. The media characteristic (types of media) of the media stored in the sheet feeding cassette222is displayed as “PLAIN PAPER”. Further, the media characteristics (types of media) of the media stored in the respective sheet feeding cassettes220,221,223are all displayed as “automatic.” The detection result obtained by the media sensor14is displayed adjacent to the selection button for the sheet feeding cassette.

The user can refer to the detection result on the selection screen and select the sheet feeding cassette in which the media to be used in the tone correction are stored. The sheet feeding cassette from which no sheet has been caused to pass is displayed as <unknown> because no medium has been detected by the media sensor14.

When the user selects, from the selection screen, a sheet feeding cassette in which media that cannot be used in the tone correction have been stored, or when the user selects a sheet feeding cassette displayed as <unknown>, the CPU10displays a message indicating that the media in the sheet feeding cassette cannot be used. Further, the CPU10issues a notification of a determination method for a usable sheet feeding cassette.FIG.14is an exemplary view of a notification screen to be used for such a notification.

<Tone Correction>

In the second embodiment, the print processing accompanied by the tone correction itself is similar to that of the first embodiment, but the tone correction processing of Step S107(seeFIG.7) is different.FIG.15is a flow chart for illustrating the tone correction processing of Step S107in the second embodiment. Similarly to the first embodiment, the tone correction processing is started when the type of media is selected from the media selection screen ofFIG.5A.

The CPU10which has started the tone correction selects the media characteristic required for the tone correction in accordance with the type of media selected from the media selection screen (Step S501). The CPU10reads out, from the media information, the media detection result and the media characteristic of the media stored in each of the sheet feeding cassettes220to223(Step S502). The CPU10displays the sheet feeding cassette selection screen (FIG.13) indicating the read-out media detection result on the operation unit13(Step S503). At this time, the detection result obtained by the media sensor14is displayed for the sheet feeding cassette for which the detection result obtained by the media sensor14is present, and a display indicating that there is no detection result obtained by the media sensor14is performed for the sheet feeding cassette for which the detection result obtained by the media sensor14is absent. In the second embodiment, as illustrated inFIG.13, <unknown> is displayed for the sheet feeding cassette for which the detection result obtained by the media sensor14is absent.

The user refers to the detection result obtained by the media sensor14through the sheet feeding cassette selection screen so as to select the sheet feeding cassette in which the media to be used in the tone correction have been stored, and transmits the selection content to the CPU10through the operation unit13. The CPU10compares the media characteristic of the media stored in the sheet feeding cassette selected by the user through the operation unit13with the media characteristic selected in the process step of Step S501. In this manner, the CPU10determines whether or not the media stored in the sheet feeding cassette selected by the user are usable in the tone correction (Step S504). When the media are usable (Step S504: Y), the CPU10starts feeding of the medium from the sheet feeding cassette designated by the user so as to execute the tone correction (Step S505). A case in which the media are usable refers to a case in which, for example, the media characteristic of the media stored in the sheet feeding cassette selected by the user and the media characteristic selected in the process step of Step S501match each other. The CPU10prints the test image on the medium so as to create the adjustment chart. The color of the adjustment chart is measured by the image reading unit300. The CPU10performs the tone correction based on the color measurement result of the adjustment chart obtained by the image reading unit300.

When the media are unusable (Step S504: N), the CPU10issues an unavailable notification indicating that the media stored in the sheet feeding cassette selected by the user cannot be used in the tone correction (Step S506). A case in which the media are unusable refers to a case in which, for example, the media characteristic of the media stored in the sheet feeding cassette selected by the user and the media characteristic selected in the process step of Step S501do not match each other. Further, the media are determined as unusable also in a case in which the detection result obtained by the media sensor14of the media stored in the sheet feeding cassette selected by the user is <unknown>. The CPU10issues the unavailable notification by, for example, displaying the notification screen ofFIG.14on the operation unit13. Through the unavailable notification, the user is urged to re-select the sheet feeding cassette to be used in the tone correction. In the notification screen, the determination method for the usable sheet feeding cassette is also given. When the user re-selects the sheet feeding cassette to be used in the tone correction, the process steps of Step S504and thereafter are performed again.

The unavailable notification may be issued through a notification screen exemplified inFIG.16. In the notification screen ofFIG.16, the usable media are presented more specifically, and an instruction to select the sheet feeding cassette in which the usable media are stored is given.

The image forming apparatus100according to the second embodiment described above can prevent, when the tone correction is performed in accordance with the media characteristic, the user from selecting the sheet feeding cassette in which the media inappropriate for the tone correction have been stored. Accordingly, the image forming apparatus100can form the test image on an appropriate type of media, and can adjust the image forming condition. Thus, the image forming apparatus100can prevent the quality of the printed product from being reduced.

Third Embodiment

Configurations of the image forming apparatus100and the control unit9in a third embodiment of the present disclosure are similar to those of the first embodiment, and hence description thereof is omitted.

The toner image transferred onto the medium is applied with heat and pressure at the fixing nip portion206of the fixing device170so that the toner image is fixed to the medium. When the toner image is fixed at the fixing nip portion206, some toner adheres to the surface of the fixing film203without being fixed to the medium. Such toner is referred to as “offset toner.” The offset toner returns to the fixing nip portion206due to the rotation of the fixing film203, and sometimes adheres to a subsequent medium at the time of the fixing of the subsequent medium, to thereby cause an image defect. Accordingly, it is required to regularly clean the fixing device170.

<Cleaning of Fixing Device170>

Fixing cleaning for removing the offset toner is performed by causing a cleaning sheet created by printing a cleaning image on a medium to pass through the fixing device170. A toner image of the cleaning image is heated at the fixing nip portion206so as to be melted and have tackiness. Through use of this tackiness, the offset toner adhering to the surface of the fixing film203is collected. It is required to print the cleaning image on a sheet and cause the sheet to pass through the fixing device170, and hence parameters such as the image forming condition and the fixing temperature are determined in advance. Accordingly, the media characteristic (type) of the media usable in the fixing cleaning is also limited.

The fixing cleaning is performed in response to an instruction given by the user through the operation unit13.FIG.17is an exemplary view of a fixing cleaning instruction screen. In this instruction screen, a sheet feeding cassette in which media to be used for the cleaning sheet are stored is selected. In the instruction screen, selection buttons517and519for the sheet feeding cassette for which the plain paper has been set by the user and the sheet feeding cassette for which the detection result obtained by the media sensor14has been set to the plain paper are displayed as selectable candidates. Selection buttons518and520for the sheet feeding cassettes in which the media unusable in the fixing cleaning are stored are grayed out so as not to be selectable.

The user selects, from the instruction screen, the sheet feeding cassette in which the media usable in the fixing cleaning are stored. The image forming apparatus100feeds the medium from the selected sheet feeding cassette so as to create the cleaning sheet. The cleaning sheet is caused to pass through the fixing device170so that the fixing device170is cleaned.

In the image forming apparatus100according to the third embodiment described above, when the fixing cleaning is performed, the user can select without hesitation the sheet feeding cassette in which the media suitable for the fixing cleaning are stored. Accordingly, reduction in usability can be prevented. Further, the image forming apparatus100can perform the fixing cleaning with an appropriate type of media. Thus, the image forming apparatus100can prevent the quality of the printed product from being reduced.

The image forming apparatus100may display, on the instruction screen, the detection result of the media characteristic obtained by the media sensor14as illustrated inFIG.13instead of displaying the candidates of the sheet feeding cassette in which the media suitable for the fixing cleaning are stored. In this case, the user refers to the detection result so as to determine the sheet feeding cassette.

Fourth Embodiment

Configurations of the image forming apparatus100and the control unit9in a fourth embodiment of the present disclosure are similar to those of the first embodiment, and hence description thereof is omitted. The image forming apparatus100according to the fourth embodiment presents the user with the sheet feeding cassette for storing the media usable in the tone correction instead of causing the user to select the media to be used in the tone correction from the sheet feeding cassette selection screen exemplified inFIG.6. The user stores the media having the media characteristic usable in the tone correction into the presented sheet feeding cassette, and transmits the instruction on the tone correction to the image forming apparatus100.

When the plain paper is selected in the media selection screen ofFIG.5A, instead of the sheet feeding cassette selection screen, a sheet feeding cassette instruction screen exemplified inFIG.18is displayed on the operation unit13. Through the sheet feeding cassette instruction screen, an instruction on the sheet feeding cassette for storing the media to be used in the tone correction is given. The sheet feeding cassette instruction screen displays that the medium to be used when the tone correction is performed is the plain paper, and also displays the usable size and the sheet feeding cassette in which the media are stored.

The user stores the media having the media characteristic designated in the sheet feeding cassette instruction screen into the designated sheet feeding cassette. When media are already stored in the designated sheet feeding cassette, the user removes the media and then stores the designated media. After that, the user presses an “OK” button in the sheet feeding cassette instruction screen.

<Tone Correction>

In the fourth embodiment, the print processing accompanied by the tone correction itself is similar to that of the first embodiment, but the tone correction processing of Step S107(seeFIG.7) is different.FIG.19is a flow chart for illustrating the tone correction processing of Step S107in the fourth embodiment. Similarly to the first embodiment, the tone correction processing is started when the type of media is selected from the media selection screen ofFIG.5A.

The CPU10which has started the tone correction selects the media characteristic required for the tone correction in accordance with the type of media selected from the media selection screen (Step S601). The CPU10displays the sheet feeding cassette instruction screen exemplified inFIG.18on the operation unit13(Step S602). In this manner, an instruction on the type of media (media characteristic) to be used in the tone correction and the sheet feeding cassette for storing the media is given to the user. In the fourth embodiment, as illustrated inFIG.18, the user is urged to store the media to be used in the tone correction into the first sheet feeding cassette (sheet feeding cassette1).

After the user stores the designated media into the first sheet feeding cassette (sheet feeding cassette1), the user presses the “OK” button. In this manner, the CPU10determines that the media have been stored in the designated sheet feeding cassette (Step S603: Y). The CPU10starts the feeding of the medium from the sheet feeding cassette designated in the sheet feeding cassette instruction screen so as to execute the tone correction (Step S604). The CPU10prints the test image on the medium so as to create the adjustment chart. The color of the adjustment chart is measured by the image reading unit300. The CPU10performs the tone correction based on the color measurement result of the adjustment chart obtained by the image reading unit300.

Even when the image forming apparatus100has a configuration in which the media are fed not only from the sheet feeding cassette but also from the manual feed tray, the fourth embodiment can be applied thereto so that a similar effect can be obtained. That is, the sheet feeding cassette instruction screen may give an instruction to place the media on the manual feed tray instead of the sheet feeding cassette.

The image forming apparatus100according to the fourth embodiment described above can form the test image on an appropriate type of media, and can adjust the image forming condition. Thus, the image forming apparatus100can prevent the quality of the printed product from being reduced. Further, even in a configuration in which, other than the tone correction, calibration of printing the test image on the medium is performed and in the fixing cleaning as described in the third embodiment, the fourth embodiment can be applied thereto so that a similar effect can be obtained.

Fifth Embodiment

Configurations of the image forming apparatus100and the control unit9in a fifth embodiment of the present disclosure are similar to those of the first embodiment, and hence description thereof is omitted. The image forming apparatus100according to the fifth embodiment gives, when there is no sheet feeding cassette in which the media to be used in the tone correction have been stored, to the user, an instruction on the media having the media characteristic to be used and the sheet feeding cassette for storing the media. The instruction in given through, for example, screen display onto the operation unit13. The user stores the designated media having the media characteristic into the designated sheet feeding cassette, and instructs the image forming apparatus100to execute the tone correction. In response to this instruction, the image forming apparatus100executes the tone correction.

When the plain paper is selected in the media selection screen ofFIG.5A, instead of the sheet feeding cassette selection screen, a sheet feeding cassette instruction screen exemplified inFIG.20is displayed on the operation unit13. Through the sheet feeding cassette instruction screen, an instruction on the sheet feeding cassette for storing the media to be used in the tone correction is given. The sheet feeding cassette instruction screen displays that the medium to be used when the tone correction is performed is the plain paper, and also displays the usable size and the sheet feeding cassette in which the media are stored. Further, the sheet feeding cassette instruction screen displays that there is no sheet feeding cassette in which the usable media have been stored.

The user stores the media having the media characteristic designated in the sheet feeding cassette instruction screen into the designated sheet feeding cassette. After that, the user presses the “OK” button in the sheet feeding cassette instruction screen. In this manner, the image forming apparatus100performs the tone correction.

<Tone Correction>

In the fifth embodiment, the print processing accompanied by the tone correction itself is similar to that of the first embodiment, but the tone correction processing of Step S107(seeFIG.7) is different.FIG.21is a flow chart for illustrating the tone correction processing of Step S107in the fifth embodiment. Similarly to the first embodiment, the tone correction processing is started when the type of media is selected from the media selection screen ofFIG.5A.

The CPU10which has started the tone correction selects the media characteristic required for the tone correction in accordance with the type of media selected from the media selection screen (Step S701). The CPU10reads out, from the media information, the media detection result and the media characteristic of the media stored in each of the sheet feeding cassettes220to223(Step S702). The CPU10compares the media characteristic selected in the process step of Step S701with the media characteristic read out in Step S702, and determines the presence or absence of the usable sheet feeding cassette (Step S703).

When the usable sheet feeding cassette is present (Step S703: Y), the CPU10displays, as exemplified inFIG.6, the sheet feeding cassette selection screen in which the selectable sheet feeding cassette and the non-selectable sheet feeding cassette are distinguished from each other (Step S704). The user gives, through the operation unit13, an instruction on the sheet feeding cassette in which the media to be used in the tone correction are stored from the sheet feeding cassette selection screen. The CPU10obtains, from the operation unit13, the instruction on the sheet feeding cassette in which the media to be used in the tone correction are stored, and determines the sheet feeding cassette to be used (Step S705: Y). The CPU10starts the feeding of the medium from the determined sheet feeding cassette so as to execute the tone correction (Step S706). The CPU10prints the test image on the medium so as to create the adjustment chart. The color of the adjustment chart is measured by the image reading unit300. The CPU10performs the tone correction based on the color measurement result of the adjustment chart obtained by the image reading unit300.

When the usable sheet feeding cassette is absent (Step S703: N), the CPU10displays the sheet feeding cassette instruction screen as exemplified inFIG.20(Step S707). Through the sheet feeding cassette instruction screen, the CPU10urges the user to store the media into a predetermined sheet feeding cassette. The user stores the media into the sheet feeding cassette in accordance with the instruction of the sheet feeding cassette instruction screen, and then presses the “OK” button through the operation unit13. In this manner, the CPU10is notified that the media have been stored in the predetermined sheet feeding cassette. The CPU10determines that the media have been stored based on this notification (Step S708). The CPU10starts the feeding of the medium from the sheet feeding cassette in which the medium has been stored so as to execute the tone correction (Step S706). The CPU10prints the test image on the medium so as to create the adjustment chart. The color of the adjustment chart is measured by the image reading unit300. The CPU10performs the tone correction based on the color measurement result of the adjustment chart obtained by the image reading unit300.

Even when the image forming apparatus100has a configuration in which the media are fed not only from the sheet feeding cassette but also from the manual feed tray, the fifth embodiment can be applied thereto so that a similar effect can be obtained. That is, the sheet feeding cassette instruction screen may give an instruction to place the media on the manual feed tray instead of the sheet feeding cassette.

The image forming apparatus100according to the fifth embodiment described above causes, when the sheet feeding cassette in which the media usable at the time of the tone correction are stored cannot be selected, the user to store the media usable in the tone correction into a predetermined sheet feeding cassette. Thus, the image forming apparatus100can form the test image on an appropriate type of media, and can adjust the image forming condition. Thus, the image forming apparatus100can prevent the quality of the printed product from being reduced. Further, even in a configuration in which, other than the tone correction, calibration of printing the test image on the medium is performed and in the fixing cleaning as described in the third embodiment, the fifth embodiment can be applied thereto so that a similar effect can be obtained.

As described above with reference to the first to fifth embodiments, when the image forming apparatus100performs predetermined processing to be performed through use of media, such as the fixing cleaning or the adjustment of the image forming condition, for example, the tone correction, the image forming apparatus100causes the user to select the sheet feeding cassette in which the usable media are stored. At this time, the image forming apparatus100displays the selection screen so that the user can visually easily determine the selectable sheet feeding cassette. The image forming apparatus100includes the media sensor14, and the media characteristic (type of media) usable in the predetermined processing is determined based on the detection result of the media characteristic obtained by the media sensor14. The predetermined processing refers to processing using the media, such as image forming condition correction processing like the tone correction, or cleaning of the image forming unit17(for example, fixing cleaning).

That is, the sheet feeding cassette selectable by the user and the sheet feeding cassette not selectable by the user are determined based on the detection result obtained by the media sensor14. The selectable sheet feeding cassette stores media having a media characteristic usable in the processing. The non-selectable sheet feeding cassette stores media having a media characteristic unusable in the processing. The user selects the sheet feeding cassette to be used from the selectable sheet feeding cassette. That is, the user can select the sheet feeding cassette in which the media appropriate for the predetermined processing are stored. In this manner, the processing using the media inappropriate for the predetermined processing can be prevented from being executed. Accordingly, correct processing can be executed, and, as a result, the quality of the printed product can be prevented from being reduced.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No. 2021-068517, filed Apr. 14, 2021, which is hereby incorporated by reference herein in its entirety.