JP7159964B2 - Image forming apparatus, waste toner discharge method and waste toner discharge program - Google Patents

Description

The present invention relates to an image forming apparatus, a waste toner discharging method, and a waste toner discharging program, and more particularly to an image forming apparatus that forms an image using toner, a waste toner discharging method that is executed in the image forming apparatus, and a computer that uses the waste toner. The present invention relates to a waste toner discharge program for executing a toner discharge method.

An image forming apparatus typified by an MFP (Multi Function Peripheral) forms a toner image on a photoreceptor drum by agitating developer composed of toner and carrier in a developing device and applying electric charge to toner particles. The toner image formed on the photosensitive drum is transferred to the secondary transfer belt, and further transferred from the secondary transfer belt to a recording medium such as paper. When the toner images formed on the photosensitive drum and the secondary transfer belt are transferred, part of the toner constituting the toner image remains without being transferred. Therefore, the image forming apparatus has a function of collecting the toner remaining on the photosensitive drum or the secondary transfer belt. For example, Japanese Patent Application Laid-Open No. 2019-040017 includes a rotating photosensitive drum, a container body that opens toward the photosensitive drum, and a cleaning blade that contacts the surface of the photosensitive drum at its end. and a conveying screw that rotates to discharge the collected material inside the container toward the outside of the container.

In this image forming apparatus, the rotational speed of the conveying screw is set to a constant speed at which the amount of collected toner is smaller than the amount of discharged toner. On the other hand, in the image forming apparatus, if the rotation speed of the conveying screw is increased, the temperature rises due to the heat generated in the bearing, which causes problems such as welding and wear of the shaft. For this reason, it is preferable to set the rotation speed of the conveying screw to a value as small as possible so as not to cause any problems.

Since the toner is powder, the lower the air pressure, the lower the bulk density. Therefore, in the image forming apparatus, when the rotation speed of the conveying screw is set based on a certain atmospheric pressure, if the image forming apparatus is installed in a place with a lower atmospheric pressure than the reference atmospheric pressure, the toner will not be accommodated in the container body. In some cases, the liquid level of the toner on the surface of the toner rises, which may cause a problem that the image quality of the image formed by the image forming apparatus is degraded or the collecting device is broken down.

Specifically, in the image forming apparatus, when the liquid level of the toner stored in the container reaches or exceeds a predetermined value, the area where the cleaning blade comes into contact with the photosensitive drum has no place for the toner to escape. Toner accumulates in the In this case, since the powder pressure of the toner at the contact portion rises and overcomes the deterrent force of the cleaning blade, the toner slips through between the cleaning blade and the photoreceptor drum and remains on the photoreceptor drum. In this case, in the next image forming cycle, toner exists at a position other than the position where the toner image is formed, resulting in deterioration of image quality. Further, when the liquid surface of the toner reaches above the highest point of the conveying screw, the toner hardly moves because the conveying force of the conveying screw does not reach. In this state, if the temperature of the container becomes high, there may be a problem that the toner aggregates and cannot be conveyed.

JP 2019-040017 A

SUMMARY OF THE INVENTION One of the objects of the present invention is to provide an image forming apparatus which prevents degradation of image quality and reduces the probability of failure.

Another object of the present invention is to provide a waste toner discharging method which prevents deterioration of image quality and reduces the probability of failure.

A further object of the present invention is to provide a waste toner discharge program which prevents deterioration of image quality and reduces the probability of failure.

According to one aspect of the present invention, an image forming apparatus includes a recovery device for recovering toner remaining on an image carrier after a toner image formed by toner is transferred to the image carrier as waste toner, and a recovery device. a container having a discharge port for containing waste toner collected from the image carrier; a conveying screw having vanes for exerting a force on the conveying screw, the control means determining the work of the conveying screw based on the air pressure.

According to this aspect, since the amount of work of the conveying screw is determined based on the air pressure, the amount of waste toner discharged from the discharge port can be adjusted according to the volume of the waste toner that changes with changes in the air pressure. can. As a result, the amount of waste toner stored in the storage body is adjusted to an appropriate amount, so that it is possible to provide an image forming apparatus that prevents deterioration in image quality and reduces the probability of failure.

Preferably, the control means sets the work amount of the conveying screw to a larger value as the atmospheric pressure is lower.

According to this aspect, the lower the atmospheric pressure, the lower the bulk density of the waste toner. Therefore, the lower the atmospheric pressure, the larger the volume of waste toner can be discharged from the outlet.

Preferably, detection means for detecting air pressure is further provided.

According to this aspect, accurate air pressure can be easily obtained.

Preferably, the air pressure information acquiring means for externally acquiring information indicating the air pressure of the outside is further provided.

According to this aspect, the atmospheric pressure can be easily obtained.

Preferably, the control means determines the amount of work based on the volume of waste toner contained in the container.

According to this aspect, the waste toner is discharged based on the volume corresponding to the bulk density of the waste toner, which fluctuates with changes in air pressure, so the work load of the conveying screw can be determined at an appropriate timing.

Preferably, the control means sets the work amount to a value different from the default value in response to the amount of waste toner stored in the storage unit becoming equal to or greater than a threshold value.

According to this aspect, when the amount of waste toner contained in the container is smaller than the threshold value, the conveying screw is driven with the work load of the default value. can do.

Preferably, a sensor is disposed at a predetermined height of the container and detects waste toner, and the control means detects the amount of waste toner equal to or greater than a threshold in response to detection of waste toner by the sensor. To detect.

According to this aspect, it is possible to detect that the volume of waste toner contained in the container is larger than the threshold.

Preferably, the control means stores the toner in the container based on a collection amount calculated from a toner image formed on the image carrier in the past and the air pressure, and a discharge amount calculated from the rotation speed of the conveying screw and the air pressure. prediction means for predicting the amount of waste toner being generated, and the control means compares the predicted amount of waste toner with a threshold value.

According to this aspect, since the amount of waste toner contained in the container is predicted from the toner image formed on the image carrier in the past, it is possible to detect that the volume of the waste toner contained in the container is larger than the threshold. can be detected.

Preferably, the control means calculates a coverage indicating a ratio of the toner image to the entire image based on the image data that is the basis of the toner image formed on the image carrier in the past, and accommodates the toner image in the container from the calculated coverage. The weight of the waste toner is calculated, and the collection amount is predicted based on the calculated weight of the toner and the atmospheric pressure.

According to this aspect, the recovery amount can be obtained.

Preferably, the control means determines the number of revolutions per unit time of the conveying screw.

According to this aspect, the work of the conveying screw can be easily determined.

Preferably, the control means determines the driving time of the conveying screw.

According to this aspect, the work of the conveying screw can be easily determined.

According to another aspect of the present invention, a method for discharging waste toner includes a collecting device for collecting, as waste toner, toner remaining on an image carrier after a toner image formed of toner is transferred onto the image carrier. In a waste toner discharging method executed in an image forming apparatus, a collecting device includes a container having a discharge port and containing waste toner collected from an image carrier; a conveying screw having vanes applying force against the discharge port, and determining the work of the conveying screw based on the air pressure.

According to this aspect, it is possible to provide a waste toner discharging method that prevents deterioration of image quality and reduces the probability of failure.

According to still another aspect of the present invention, a waste toner discharge program includes a collecting device for collecting, as waste toner, toner remaining on an image carrier after a toner image formed of toner is transferred onto the image carrier. a waste toner discharge program executed by a computer for controlling an image forming apparatus, wherein the collection device includes a container having a discharge port and containing waste toner collected from the image carrier; and a conveying screw having wings that apply force against the waste toner toward the outlet, and causing the computer to determine the amount of work done by the conveying screw based on the air pressure.

According to this aspect, it is possible to provide a waste toner discharge program that prevents deterioration of image quality and reduces the probability of failure.

1 is a perspective view showing the appearance of an MFP according to a first embodiment of the invention; FIG. 2 is a diagram showing an overview of the internal configuration of the MFP; FIG. FIG. 2 is a diagram showing an example of an image forming unit; FIG. FIG. 4 is a cross-sectional view of the recovery device shown in FIG. 3 taken along the line AA; 2 is a block diagram showing an overview of the hardware configuration of the MFP; FIG. 3 is a block diagram showing an example of functions of a CPU provided in the MFP; FIG. It is a figure which shows an example of a coefficient table. 5 is a flowchart showing an example of the flow of waste toner discharge processing; 1 is a cross-sectional view of a recovery device; FIG. FIG. 11 is a block diagram showing an example of functions of a CPU included in the MFP according to the second embodiment; FIG. 10 is a flow chart showing an example of the flow of waste toner discharge processing according to the second embodiment; 7 is a flowchart showing an example of the flow of toner amount determination processing;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are given the same reference numerals. Their names and functions are also the same. A detailed description thereof will therefore not be repeated.

<First embodiment>
FIG. 1 is a perspective view showing the appearance of the MFP according to the first embodiment of the invention. FIG. 2 is a diagram showing an overview of the internal configuration of the MFP. 1 and 2, MFP 100 functions as an image forming apparatus and forms an image on a recording medium based on image data. The MFP (Multi Function Peripheral) 100 is capable of forming an image on any of a plurality of types of recording media as recording media on which images are to be formed. The recording medium includes paper such as paper, OHP (overhead projector) sheet, cloth, and the like. Also, in the following description, unless otherwise specified, a case where paper is used as a recording medium will be described as an example.

The MFP 100 is an example of an image forming apparatus, and includes a document reading unit 130 that reads a document, an automatic document feeder 120 that conveys a document to the document reading unit 130, and an image forming unit that forms an image on a sheet based on image data. 140, a paper feed unit 150 that supplies paper to the image forming unit 140, and an operation panel 160 as a user interface.

Automatic document feeder 120 separates one or more documents placed on a document tray and conveys them to document reading unit 130 one by one. The document reading unit 130 exposes the image of the document set on the document glass 11 by the automatic document feeder 120 with the exposure lamp 13 attached to the slider 12 moving below. Reflected light from the document is guided to a lens 16 by a mirror 14 and two reflecting mirrors 15 and 15A, and forms an image on a CCD (Charge Coupled Devices) sensor 18 .

The reflected light imaged on the CCD sensor 18 is converted into image data as electrical signals within the CCD sensor 18 . The image data is converted into printing data of cyan (C), magenta (M), yellow (Y), and black (K) and output to image forming section 140 .

Image forming section 140 includes image forming units 20Y, 20M, 20C, and 20K for yellow, magenta, cyan, and black, respectively. Here, "Y", "M", "C" and "K" represent yellow, magenta, cyan and black respectively. An image is formed by driving at least one of the image forming units 20Y, 20M, 20C, and 20K. A full-color image is formed when all of the image forming units 20Y, 20M, 20C, and 20K are driven. Yellow, magenta, cyan and black printing data are input to the image forming units 20Y, 20M, 20C and 20K, respectively. Since the image forming units 20Y, 20M, 20C, and 20K differ only in the color of the toner they handle, the image forming unit 20Y for forming a yellow image will be described here.

The image forming unit 20Y includes an exposure device 21Y to which yellow print data is input, a photoreceptor drum 23Y as an image carrier, a charging roller 22Y for uniformly charging the surface of the photoreceptor drum 23Y, A developing device 24Y, a primary transfer roller 25Y for transferring the toner image formed on the photosensitive drum 23Y onto the intermediate transfer belt 30, which is an image carrier, by the action of electric field force, and a primary transfer roller 25Y on the photosensitive drum 23Y. A recovery device 27Y for removing transfer residual toner, a toner bottle 41Y, and a toner hopper 42Y are provided.

The toner bottle 41Y contains yellow toner. Toner is non-magnetic. The toner bottle 41Y rotates using a toner bottle motor as a drive source, and discharges toner to the outside. The toner discharged from the toner bottle 41Y is supplied to the toner hopper 42Y. The toner hopper 42Y supplies toner to the developing device 24Y when the remaining amount of the developer contained in the developing device 24Y becomes equal to or less than a predetermined lower limit value. The developer contains toner and a magnetic carrier.

Around the photosensitive drum 23Y, a charging roller 22Y, an exposure device 21Y, a developing device 24Y, a primary transfer roller 25Y, and a collecting device 27Y are arranged in order along the rotation direction of the photosensitive drum 23Y.

After being charged by the charging roller 22Y, the photosensitive drum 23Y is irradiated with laser light emitted by the exposure device 21Y. The exposure device 21Y forms an electrostatic latent image by exposing the image corresponding portion on the surface of the photosensitive drum 23Y. Thereby, an electrostatic latent image is formed on the photosensitive drum 23Y. Subsequently, the developing device 24Y develops the electrostatic latent image formed on the photosensitive drum 23Y with charged toner. Specifically, a toner image is formed on the photoreceptor drum 23Y by placing toner on the electrostatic latent image formed on the photoreceptor drum 23Y by the action of the electric field force. The toner image formed on the photosensitive drum 23Y is transferred onto the intermediate transfer belt 30, which is an image carrier, by the action of the electric field force by the primary transfer roller 25Y. The toner remaining on the photoreceptor drum 23Y without being transferred is removed from the photoreceptor drum 23Y by the recovery device 27Y.

On the other hand, the intermediate transfer belt 30 is suspended by a driving roller 33 and a driven roller 34 so as not to loosen. When the driving roller 33 rotates counterclockwise in FIG. 3, the intermediate transfer belt 30 rotates counterclockwise in the figure at a predetermined speed. As the intermediate transfer belt 30 rotates, the driven roller 34 rotates counterclockwise.

As a result, the image forming units 20Y, 20M, 20C, and 20K transfer the toner images onto the intermediate transfer belt 30 in order. The timing at which each of the image forming units 20Y, 20M, 20C, and 20K transfers the toner image onto the intermediate transfer belt 30 is adjusted by detecting a reference mark attached to the intermediate transfer belt 30. FIG. As a result, yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 30 .

The toner image formed on the intermediate transfer belt 30 is transferred to the paper by the action of the electric field force by the secondary transfer roller 26 which is a transfer member. The paper is transported to the nip portion where the intermediate transfer belt 30 transported by the timing roller 31 and the secondary transfer roller 26 are in contact. The paper onto which the toner image has been transferred is conveyed to the fixing roller 32 and is heated and pressed by the fixing roller 32 . As a result, the toner is melted and fixed on the paper. After that, the paper is discharged to the paper discharge tray 39 .

A belt cleaning device 29 is provided on the intermediate transfer belt 30 upstream of the image forming unit 20Y. The belt cleaning device 29 removes toner remaining on the intermediate transfer belt 30 without being transferred to the paper. Toner removed from the intermediate transfer belt 30 by the belt cleaning device 29 is stored as waste toner in a waste toner box.

Sheets of different sizes are set in the sheet feed cassettes 35, 35A, and 35B. Sheets accommodated in paper feed cassettes 35, 35A, and 35B are supplied to the transport path by take-out rollers 36, 36A, and 36B attached to paper feed cassettes 35, 35A, and 35B, respectively. It is sent to timing roller 31 .

MFP 100 drives all of image forming units 20Y, 20M, 20C, and 20K when forming a full-color image. drive one. Also, two or more of the image forming units 20Y, 20M, 20C, and 20K can be combined to form an image. Here, an example will be described in which the MFP 100 employs a tandem system having image forming units 20Y, 20M, 20C, and 20K that form toners of four colors on paper. A 4-cycle method may be adopted in which the toner is sequentially transferred onto the paper.

FIG. 3 is a diagram showing an example of an image forming unit. Referring to FIG. 3, image forming unit 20Y includes exposure device 21Y to which yellow print data is input, photoreceptor drum 23Y as an image carrier, and uniformly charges the surface of photoreceptor drum 23Y. a charging roller 22Y, a developing device 24Y, and a primary transfer roller 25Y for transferring the toner image formed on the photosensitive drum 23Y onto the intermediate transfer belt 30, which is an image carrier, by the action of electric field force. , a collection device 27Y for removing transfer residual toner on the photosensitive drum 23Y, and a waste toner bottle 28Y.

Around the photosensitive drum 23Y, a charging roller 22Y, an exposure device 21Y, a developing device 24Y, a primary transfer roller 25Y, and a collecting device 27Y are arranged in order along the rotation direction of the photosensitive drum 23Y. The photoreceptor drum 23Y is made of, for example, an organic photoreceptor in which a photosensitive layer made of a resin containing an organic photoconductor is formed on the outer peripheral surface of a drum-shaped metal substrate. Examples of resins constituting the photosensitive layer include polycarbonate resins, silicone resins, polystyrene resins, acrylic resins, methacrylic resins, epoxy resins, polyurethane resins, vinyl chloride resins and melamine resins.

After being charged by the charging roller 22Y, the photosensitive drum 23Y is irradiated with laser light emitted by the exposure device 21Y. The exposure device 21Y forms an electrostatic latent image by exposing the image corresponding portion on the surface of the photosensitive drum 23Y. Thereby, an electrostatic latent image is formed on the photosensitive drum 23Y. Subsequently, the developing device 24Y develops the electrostatic latent image formed on the photosensitive drum 23Y with charged toner. Specifically, a toner image is formed on the photoreceptor drum 23Y by placing toner on the electrostatic latent image formed on the photoreceptor drum 23Y by the action of the electric field force. The toner image formed on the photosensitive drum 23Y is transferred onto the intermediate transfer belt 30, which is an image carrier, by the action of the electric field force by the primary transfer roller 25Y. The toner remaining on the photoreceptor drum 23Y without being transferred is removed from the photoreceptor drum 23Y by the recovery device 27Y.

The collecting device 27Y includes a case 203Y, a flat cleaning blade 201Y made of an elastic material, and a conveying screw 205Y. A waste toner bottle 28Y is arranged below the case 203Y.

The cleaning blade 201Y is arranged at a position in contact with the photosensitive drum 23Y. Therefore, the cleaning blade 201Y scrapes the surface of the photoreceptor drum 23Y as the photoreceptor drum 23Y rotates. As a result, the toner remaining on the photosensitive drum 23Y is scraped off by the cleaning blade 201Y. The toner scraped from the photosensitive drum 23Y by the cleaning blade 201Y is accommodated in the case 203Y. The toner contained in the case 203Y is conveyed to the outside of the case 203Y by the conveying screw 205Y and is contained in the waste toner bottle 28Y.

4 is a cross-sectional view of the recovery device shown in FIG. 3 taken along the line AA. The direction in which the conveying screw 205Y provided in the collection device 27Y extends is defined as the X-axis direction. A direction orthogonal to the X-axis direction and the vertical direction is defined as the Y-axis direction.

The case 203Y is a container extending in the X-axis direction, and stores toner scraped from the photosensitive drum 23Y by the cleaning blade 201Y. A discharge port 211Y is arranged at the end of the case 203Y on the positive side in the X-axis direction. The outlet 211Y communicates with the waste toner bottle 28Y.

The conveying screw 205Y has a shape in which helical blades are provided on the outer peripheral surface of a cylindrical rotating shaft extending in the X-axis direction. A rotating shaft of the conveying screw 205Y is supported by the case 203Y. The toner is conveyed toward the discharge port 211Y by rotating the conveying screw 205Y. The conveying screw 205Y is rotated by being driven by a motor serving as a drive source.

FIG. 5 is a block diagram outlining the hardware configuration of the MFP. Referring to FIG. 5, MFP 100 includes main circuit 110 . Main circuit 110 is connected to automatic document feeder 120, document reading section 130, image forming section 140, paper feeding section 150, and operation panel 160 as a user interface.

The main circuit 110 includes a CPU (central processing unit) 111 that controls the entire MFP 100, a communication interface (I/F) unit 112, a ROM (Read Only Memory) 113, a RAM (Random Access Memory) 114, It includes a hard disk drive (HDD) 115 as a mass storage device, a facsimile unit 116 , an air pressure sensor 117 and an external storage device 118 . The CPU 111 is an example of a computer that executes programs. CPU 111 is connected to automatic document feeder 120, document reading unit 130, image forming unit 140, paper feeding unit 150, and operation panel 160 by executing a program, and controls MFP 100 as a whole.

ROM 113 stores a program executed by CPU 111 or data necessary for executing the program. The RAM 114 is used as a work area when the CPU 111 executes programs. RAM 114 also temporarily stores image data continuously sent from document reading unit 130 .

Operation panel 160 is provided above MFP 100 . Operation panel 160 includes a display portion 161 and an operation portion 163 . The display unit 161 is, for example, a liquid crystal display (LCD), and displays an instruction menu for the user, information about acquired image data, and the like. Note that an organic EL (electroluminescence) display, for example, can be used instead of the LCD as long as it is a device that displays an image.

Operation portion 163 includes a touch panel 165 and a hard key portion 167 . The touch panel 165 is of a capacitive type. It should be noted that the touch panel 165 is not limited to the capacitive method, and other methods such as a resistive film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, and the like can be used. Hard key portion 167 includes a plurality of hard keys. A hard key is, for example, a contact switch.

Communication I/F unit 112 is an interface for connecting MFP 100 to a network. Communication I/F unit 112 communicates with other computers or data processing devices connected to a network using a communication protocol such as TCP (Transmission Control Protocol) or FTP (File Transfer Protocol). A network to which communication I/F unit 112 is connected is a local area network (LAN), and the form of connection may be wired or wireless. Also, the network is not limited to a LAN, and may be a wide area network (WAN), a public switched telephone network (PSTN), the Internet, or the like.

Facsimile unit 116 is connected to the public switched telephone network (PSTN) and transmits facsimile data to or receives facsimile data from the PSTN. Facsimile unit 116 stores the received facsimile data in HDD 115 , converts it into print data that can be printed by image forming unit 140 , and outputs the print data to image forming unit 140 . Accordingly, image forming section 140 forms an image of the facsimile data received by facsimile section 116 on paper. Further, facsimile section 116 converts data stored in HDD 115 into facsimile data and transmits the facsimile data to a facsimile machine connected to the PSTN.

Air pressure sensor 117 is arranged near image forming unit 140 . The atmospheric pressure sensor 117 measures atmospheric pressure and outputs atmospheric pressure information indicating the measured atmospheric pressure to the CPU 111 .

The external storage device 118 is controlled by the CPU 111 and is equipped with a CD-ROM (Compact Disk Read Only Memory) 118A or a semiconductor memory. In this embodiment, an example in which CPU 111 executes a program stored in ROM 113 will be described. , the read program may be stored in the RAM 114 and executed.

CPU 111 controls image forming unit 140 to form an image of image data on a recording medium such as paper. The image data output by CPU 111 to image forming portion 140 includes image data input from document reading portion 130 as well as image data such as print data received from the outside.

The recording medium for storing programs to be executed by the CPU 111 is not limited to the CD-ROM 118A, and may be a flexible disk, a cassette tape, an optical disk (MO (Magnetic Optical Disc)/MD (Mini Disc)/DVD (Digital Versatile Disc). )), an IC card, an optical card, a mask ROM, a semiconductor memory such as an EPROM (Erasable Programmable ROM), or the like. Furthermore, the CPU 111 downloads a program from a computer connected to the network and stores it in the HDD 115, or the computer connected to the network writes the program to the HDD 115, and loads the program stored in the HDD 115 into the RAM 114. and executed by the CPU 111. The programs here include not only programs directly executable by the CPU 111, but also source programs, compressed programs, encrypted programs, and the like.

FIG. 6 is a block diagram showing an example of functions of a CPU provided in the MFP. The functions shown in FIG. 6 are realized by CPU 111 of MFP 100 by executing a waste toner discharge program stored in ROM 113, HDD 115, or CD-ROM 118A. Referring to FIG. 6 , CPU 111 includes an atmospheric pressure information acquiring portion 51 and an image forming control portion 53 that controls image forming portion 140 .

The atmospheric pressure information acquisition unit 51 acquires atmospheric pressure information output by the atmospheric pressure sensor 117 that measures the atmospheric pressure. The atmospheric pressure information is information indicating atmospheric pressure. The atmospheric pressure information acquiring portion 51 outputs the acquired atmospheric pressure information to the image forming control portion 53 . Here, an example of obtaining the current atmospheric pressure is shown, but the average atmospheric pressure over a predetermined period may be obtained using the atmospheric pressure information output by the atmospheric pressure sensor 117 during a predetermined period. Information indicating the atmospheric pressure in the area where MFP 100 is installed may be obtained from an external server. Alternatively, an operator who manages MFP 100 may set an altitude in MFP 100, and the atmospheric pressure may be acquired using a table that defines the relationship between altitude and atmospheric pressure.

Image formation control section 53 controls image formation section 140 to form an image on a recording medium. Further, the image forming control portion 53 receives the atmospheric pressure information from the atmospheric pressure information obtaining portion 51 . The image forming control unit 53 determines the work amount of the conveying screw 205Y based on the air pressure specified by the air pressure information. The image formation control unit 53 sets the work amount of the conveying screw 205Y to a larger value as the atmospheric pressure is lower. The image forming control unit 53 changes the amount of work by changing the rotation speed, which is the number of rotations per unit time, of the conveying screw 205Y. Specifically, the image formation control unit 53 refers to a coefficient table that defines the relationship between the atmospheric pressure and the amount of work, and determines the amount of work with respect to the atmospheric pressure. In this embodiment, the rotation time of the conveying screw 205Y is the same as the rotation time of the photosensitive drum 23Y. Therefore, the image formation control unit 53 determines the rotation speed of the conveying screw 205Y with respect to the air pressure, and rotates the conveying screw 205Y at the determined rotation speed.

FIG. 7 is a diagram showing an example of a coefficient table. Referring to FIG. 7, coefficients are defined for air pressure. Here, 1 atmosphere is 1013.25 hPa. A factor of 1 is determined for 1 atmosphere or more, a factor of 1.05 is determined for 0.95 atmosphere or more and less than 1.0 atmosphere, and a factor of 1.10 is determined for 0.90 atmosphere or more and less than 0.95 atmosphere. A coefficient of 1.15 is determined for 0.85 atmospheres or more and less than 0.90 atmospheres. In this embodiment, the rotation speed of the conveying screw 205Y is set by default, and the rotation time is the same as the rotation time of the photosensitive drum 23Y. Therefore, the coefficient table shows the scaling factor for the default rotation speed of the conveying screw 205Y.

FIG. 8 is a flowchart showing an example of the flow of waste toner discharge processing. The waste toner discharge process is a process executed by CPU 111 of MFP 100 by executing a waste toner discharge program stored in ROM 113, HDD 115, or CD-ROM 118A. Referring to FIG. 8, CPU 111 determines whether or not a print command has been received (step S01). A print command is accepted when a user inputs it to operation portion 163 or when communication I/F portion 112 receives print data from the outside. The process waits until a print command is accepted (NO in step S01), and if the print command is accepted (YES in step S01), the process proceeds to step S02.

In step S02, atmospheric pressure information is acquired. The CPU 111 controls the atmospheric pressure sensor 117 to measure the atmospheric pressure, and obtains the atmospheric pressure information output by the atmospheric pressure sensor 117 . Then, the coefficient table is referenced to determine the rotational speed of the conveying screw 205Y (step S03), and the process proceeds to step S04.

In step S04, printing is started and the process ends. During printing, while the photosensitive drum 23Y is rotating, the conveying screw 205Y is rotated at the rotational speed determined in step S03.

Since the rotating speed of the conveying screw 205Y increases so that the amount of work increases as the air pressure decreases, the volume of the toner accommodated in the case 203Y that is conveyed toward the discharge port 211Y increases. Therefore, the lower the atmospheric pressure, the larger the volume of toner stored in the case 203Y. It can be less than or equal to a predetermined value.

In addition, since the conveying screw 205Y rotates at a number of revolutions corresponding to the air pressure, the number of revolutions of the conveying screw 205Y can be reduced as much as possible. can be done.

<Second Embodiment>
The MFP 100 according to the second embodiment differs from the MFP 100 according to the first embodiment in that the amount of waste toner stored in the collecting device 27Y is detected. In the following, the points of MFP 100 according to the second embodiment that are different from MFP 100 according to the first embodiment will be described.

FIG. 9 is a cross-sectional view of the recovery device. Referring to FIG. 9, collection device 27Y includes a toner amount sensor 207Y that detects the amount of developer in case 203Y. The toner amount sensor 207Y is a photoelectric sensor arranged at a predetermined height of the case 203Y. The toner amount sensor 207 is arranged below the highest point of the conveying screw 205Y. The toner amount sensor 207Y includes a light-emitting portion that emits light and a light-receiving portion that receives light, and the light-receiving portion receives the light emitted from the light-emitting portion. When the liquid surface of the toner accommodated in the case 203Y reaches a predetermined height, the light emitted from the light emitting section is blocked by the toner and cannot be received by the light receiving section. Therefore, the toner amount sensor 207Y detects that the amount of toner contained in the case 203Y has reached or exceeded a predetermined amount.

FIG. 10 is a block diagram showing an example of functions of a CPU included in the MFP according to the second embodiment. 10, the functions different from those shown in FIG. 6 are that a waste toner amount determination unit 55 is added and the image formation control unit 53 is changed to an image formation control unit 53A. Since other functions are the same as those shown in FIG. 6, the description will not be repeated here.

The waste toner amount determining unit 55 determines the amount of toner to be stored in the case 203Y of the collecting device 27Y. The waste toner amount determination unit 55 detects that the amount of toner contained in the case 203Y has reached or exceeded a predetermined amount in response to detection of toner by the toner amount sensor 207Y.

When the waste toner amount determination unit 55 detects that the amount of toner contained in the case 203Y has exceeded a predetermined amount, the image formation control unit 53A adjusts the conveying screw based on the atmospheric pressure specified by the atmospheric pressure information. Determine the amount of work for 205Y. Before the waste toner amount determination unit 55 detects that the amount of toner contained in the case 203Y has exceeded a predetermined amount, the image formation control unit 53A determines the work amount of the conveying screw 205Y to be a default value. Further, after the waste toner amount determination unit 55 detects that the amount of toner stored in the case 203Y exceeds a predetermined amount, the image formation control unit 53A causes the waste toner amount determination unit 55 to store the toner in the case 203Y. When it is no longer detected that the amount of toner has exceeded a predetermined amount, the amount of work of the conveying screw 205Y is set to a default value. The image formation control unit 53A minimizes the time during which the rotation speed of the conveying screw 205Y is different from the default rotation speed.

Specifically, the image formation control unit 53A sets the rotational speed of the conveying screw 205Y to the default while the waste toner amount determination unit 55 does not detect that the amount of toner contained in the case 203Y has exceeded a predetermined amount. is determined, and the conveying screw 205Y is rotated at the determined rotational speed. The image formation control unit 53A refers to the coefficient table shown in FIG. A rotation speed of the screw 205Y is determined, and the conveying screw 205Y is rotated at the determined rotation speed.

FIG. 11 is a flow chart showing an example of the flow of waste toner discharge processing according to the second embodiment. Referring to FIG. 11, a difference from the waste toner discharging process in the first embodiment shown in FIG. 8 is that steps S21 and S22 are added. Since other processing is the same as the processing shown in FIG. 8, description here will not be repeated.

When the CPU 111 determines in step S01 that the print command has been received, in step S21, the CPU 111 determines whether or not the toner amount is equal to or greater than the threshold value TH1. If the toner amount sensor 207Y detects toner, the CPU 111 determines that the toner amount is equal to or greater than the threshold TH1. If the toner amount is equal to or greater than the threshold TH1, the process proceeds to step S02; otherwise, the process proceeds to step S22.

In step S22, the rotational speed of conveying screw 205Y is determined as a default value, and the process proceeds to step S04. In step S04, printing is started. When step S03 is executed, the conveying screw 205Y is rotated at a rotation speed determined based on the air pressure. The conveying screw 205Y is rotated at the rotational speed.

Therefore, in the MFP 100 according to the second embodiment, in addition to the effects of the MFP 100 according to the first embodiment, when the amount of toner stored in the collection device 27Y reaches or exceeds the threshold TH1, the air pressure increases. The rotation speed of the conveying screw 205Y increases so that the lower the value, the greater the amount of work. Therefore, when the amount of toner contained in the collecting device 27Y is less than the threshold TH1, the conveying screw 205Y rotates at the default rotational speed, so the rotational speed of the conveying screw 205Y is faster than the default rotational speed. It is possible to shorten the time during which the rotation speed is high as much as possible, reduce the heat generated by the conveying screw 205Y as much as possible, and lengthen the service life as much as possible.

<First modification>
A storage amount indicating the volume of the entire toner stored in the recovery device 27Y may be obtained from the weight of the entire toner recovered by the recovery device 27Y and the volume of the toner discharged from the recovery device 27Y. In this case, the toner amount sensor 207Y is unnecessary.

Specifically, image formation control unit 53A determines the weight of the toner collected by collection device 27Y based on the coverage of the image formed in image forming unit 140 and the number of times image forming unit 140 has formed an image. Predict. The coverage indicates the ratio of the toner image formed on the photosensitive drum 23Y to the paper. Here, based on the image data, the image formation control unit 53A calculates, as the coverage, the ratio of the area where the toner image is formed to the area of the image determined by the image data. For example, the image formation control unit 53A calculates the ratio of the number of pixels forming the toner image to the number of pixels of the image data as the coverage. The image formation control unit 53A obtains the amount of toner carried by the photosensitive drum 23Y from the image data and the coverage, and converts the amount of toner into weight.

Further, the image forming control unit 53A calculates the weight of toner collected by the collecting device 27Y each time an image is formed by the image forming unit 140 from the toner weight and residual rate. The residual ratio indicates the ratio of the toner remaining on the photosensitive drum 23Y after the secondary transfer, and is a predetermined value obtained through experiments or the like. The image forming control unit 53A calculates the weight of the toner collected by the collecting device 27Y every time the image forming unit 140 forms an image, and the toner is collected by the collecting device 27Y from the calculated weight of the toner and the bulk density determined by the air pressure. A collected amount indicating the volume of the collected toner is calculated.

Further, the image forming control portion 53A detects the amount of rotation of the conveying screw 205Y while the image forming portion 140 is forming an image. The image formation control unit 53A calculates a discharge amount indicating the volume of toner discharged from the recovery device 27Y from the amount of rotation and the volume of toner discharged per unit amount of rotation of the conveying screw 205Y.

The image formation control unit 53A adds a value obtained by subtracting the discharge amount from the collection amount to the storage amount calculated during the previous image formation, thereby newly determining the storage amount to be stored in the collection device 27Y. If the discharge amount differs depending on the storage amount, the discharge amount may be obtained from the storage amount and the rotation speed of the conveying screw 205Y.

FIG. 12 is a flowchart showing an example of the flow of toner amount determination processing. The toner amount determination process is a process executed by CPU 111 of MFP 100 by executing a waste toner discharge program stored in ROM 113, HDD 115, or CD-ROM 118A. The toner amount determination process is executed each time an image is formed by image forming unit 140 .

Referring to FIG. 12, CPU 111 predicts the weight of toner carried by photosensitive drum 23Y from the image data coverage (step S31), and advances the process to step S32. In step S32, the weight of the toner collected by the collecting device 27Y is predicted from the predicted weight and residual rate, and the process proceeds to step S33. In step S33, the bulk density is determined from the atmospheric pressure, and the process proceeds to step S34. The bulk density is determined by referring to a table that associates the atmospheric pressure with the toner bulk density. In step S34, the collection amount is determined, and the process proceeds to step S35. The collection amount is determined from the weight and bulk density of the toner determined in step S32.

In step S35, the discharge amount is determined, and the process proceeds to step S36. The discharge amount is calculated from the amount of rotation of the conveying screw 205Y and the volume of toner discharged per unit amount of rotation of the conveying screw 205Y.

In step S36, the capacity is determined and the process ends. A new accommodation amount is determined by adding the collection amount calculated in step S31 to the accommodation amount calculated in the previous image formation and subtracting the discharge amount calculated in step S32.

<Second modification>
In the first and second embodiments, the MFP 100 determines the rotation speed of the conveying screw 205Y in order to determine the amount of work of the conveying screw 205Y provided in the collecting device 27Y to a value corresponding to the atmospheric pressure. The MFP 100 in the second modification determines the driving time of the conveying screw 205Y in order to determine the amount of work of the conveying screw 205Y provided in the recovery device 27Y to a value according to the atmospheric pressure. By setting the driving time to a value different from the default value while maintaining the rotation speed of the conveying screw 205Y at the default value, the work amount of the conveying screw 205Y can be changed. As the air pressure becomes lower, the amount of work of the conveying screw 205Y becomes larger than the default value by increasing the driving time of the conveying screw 205Y.

In the MFP 100 of the present embodiment, the recovery devices 27Y, 27M, 27C, and 27K corresponding to the photosensitive drums 23Y, 23M, 23C, and 23K have been described, but the belt cleaning device 29 corresponding to the intermediate transfer belt 30 The same is true for In addition, although an example in which the collection devices 27Y, 27M, 27C, and 27K each include the waste toner bottles 28Y, 28M, 28C, and 28K has been described, the collection devices 27Y, 27M, 27C, and 27K each have a common single waste toner bottle. You may prepare. Furthermore, the belt cleaning device 29 may share a waste toner bottle common to the collection devices 27Y, 27M, 27C, and 27K.

As described above, the MFP 100 according to the first and second embodiments removes the toner remaining on the photoreceptor drum 23Y after the toner image formed on the photoreceptor drum 23Y with toner is transferred to the intermediate transfer belt 30. A collection device 27Y for collecting waste toner and a CPU 111 for controlling the collection device 27Y are provided. The collecting device 27Y includes a case 203Y that has a discharge port 211 and stores toner, and a conveying screw 205Y that is provided in the case 203Y and has wings that apply force to the toner toward the discharge port 211Y. . The CPU 111 determines the amount of work of the conveying screw 205Y based on the atmospheric pressure. Therefore, since the amount of work of the conveying screw 205Y is determined based on the air pressure, the amount of toner discharged from the discharge port 211Y can be adjusted according to the volume of toner that changes with changes in air pressure. As a result, the amount of toner contained in the case 203Y is adjusted to an appropriate amount, and the liquid level of the toner contained in the case 203Y can be reduced to a predetermined value or less. This prevents the image quality of the image formed by the MFP 100 from deteriorating, and also prevents the recovery device 27Y from breaking down.

Further, the CPU 111 determines a larger value for the work amount of the conveying screw 205Y as the atmospheric pressure is lower. Since the lower the atmospheric pressure, the lower the bulk density of the toner, the lower the atmospheric pressure, the larger volume of toner can be discharged from the discharge port 211Y.

MFP 100 may also include an air pressure sensor 117 that detects air pressure. In this case, the atmospheric pressure sensor 117 can easily obtain an accurate atmospheric pressure.

Further, MFP 100 may acquire information indicating the atmospheric pressure of the outside from the outside. In this case, there is no need to provide the atmospheric pressure sensor 117, and the atmospheric pressure can be easily obtained.

Further, the CPU 111 determines the amount of work based on the volume of toner accommodated in the case 203Y. Therefore, since the toner is discharged based on the volume corresponding to the bulk density of the toner, which fluctuates due to changes in air pressure, the amount of work of the conveying screw 205Y can be determined at an appropriate timing.

Further, in MFP 100 according to the second embodiment, CPU 111 sets the work amount to a value different from the default value in response to the amount of toner contained in case 203Y becoming equal to or greater than the threshold value. Therefore, when the amount of toner contained in the case 203Y is smaller than the threshold value, the conveying screw is driven with the work amount of the default value. can.

Further, MFP 100 in the second embodiment includes toner amount sensor 207Y that is arranged at a predetermined height in case 203 and that detects toner. to detect the amount of toner equal to or greater than the threshold. Therefore, it can be detected that the volume of toner contained in the case 203Y is larger than the threshold.

Further, in the MFP 100 according to the first modification, the CPU 111 controls the collection amount calculated from the air pressure and the toner image formed in the past on the photosensitive drum 23Y, and the discharge amount calculated from the rotation speed of the conveying screw 205Y and the air pressure. The amount of toner contained in the case 203Y is predicted based on the amount and the amount of toner, and the predicted amount of toner is compared with a threshold value. Therefore, it can be detected that the volume of toner contained in the case 203Y is larger than the threshold.

Further, in the MFP 100 according to the first modified example, the CPU 111 calculates the coverage indicating the ratio of the toner image to the entire image based on the image data that is the basis of the toner image formed on the photosensitive drum 23Y in the past. The weight of the toner contained in the case 203Y is calculated from the calculated coverage, and the collection amount is predicted based on the calculated weight of the toner and the atmospheric pressure. Therefore, the recovery amount can be obtained accurately.

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

<Appendix>
(1) Preferably, regarding the relationship between air pressure and toner bulk density, the lower the air pressure, the lower the bulk density.
(2) Preferably, the apparatus further comprises developing means for forming a toner image made of toner on the image carrier by developing the electrostatic latent image formed on the image carrier.

100 MFP, 20Y, 20M, 20C, 20K image forming unit, 21Y, 21M, 21C, 21K exposure device, 22Y, 22M, 22C, 22K charging roller, 23Y, 23M, 23C, 23K photosensitive drum, 24Y, 24M, 24C , 24K developing device, 25Y, 25M, 25C, 25K primary transfer roller, 26 secondary transfer roller, 27Y, 27M, 27C, 27K collecting device, 28Y, 28M, 28C, 28K waste toner bottle, 29 belt cleaning device, 30 Intermediate transfer belt 41Y Toner bottle 42Y Toner hopper 51 Air pressure information acquisition unit 53, 53A Image formation control unit 55 Waste toner amount determination unit 111 CPU 117 Air pressure sensor 140 Image forming unit 201Y Cleaning blade 203Y Case, 205Y Conveying screw, 207 Toner amount sensor, 207Y Toner amount sensor, 211Y Discharge port.

Claims (13)

a collecting device for collecting the toner remaining on the image carrier as waste toner after the toner image formed by the toner is transferred to the image carrier;
and a control means for controlling the recovery device,
the collecting device has an outlet and contains the waste toner collected from the image carrier;
a conveying screw provided in the container and having wings that apply force to the waste toner toward the discharge port;
The image forming apparatus, wherein the control means determines the amount of work of the conveying screw based on atmospheric pressure. 2. The image forming apparatus according to claim 1, wherein said controller sets said work amount of said conveying screw to a larger value as the atmospheric pressure is lower. 3. The image forming apparatus according to claim 1, further comprising detecting means for detecting atmospheric pressure. 3. The image forming apparatus according to claim 1, further comprising atmospheric pressure information obtaining means for obtaining information indicating external atmospheric pressure from the outside. 5. The image forming apparatus according to claim 1, wherein said control means determines said amount of work based on the volume of said waste toner contained in said container. 6. The image forming apparatus according to claim 5, wherein said control means sets said work amount to a value different from a default value in response to the amount of said waste toner contained in said container being greater than or equal to a threshold value. Device. further comprising a sensor arranged at a predetermined height of the container and detecting the waste toner;
7. The image forming apparatus according to claim 6, wherein said controller detects the amount of waste toner equal to or greater than said threshold in response to detection of said waste toner by said sensor. The control means controls the container based on a recovery amount calculated from the air pressure and the toner image formed in the past on the image carrier and a discharge amount calculated from the rotation speed of the conveying screw and the air pressure. including prediction means for predicting the amount of waste toner stored in
7. The image forming apparatus according to claim 6, wherein said control means compares the estimated amount of waste toner with said threshold value. The control means calculates a coverage indicating a ratio of the toner image to the entire image based on image data that is the basis of the toner image formed in the past on the image carrier, and calculates the coverage on the container from the calculated coverage. 9. The image forming apparatus according to claim 8, wherein the weight of the waste toner contained in the waste toner is calculated, and the collected amount is predicted based on the calculated weight of the toner and the atmospheric pressure. 10. The image forming apparatus according to claim 1, wherein said control means determines the number of revolutions per unit time of said conveying screw. 10. The image forming apparatus according to claim 1, wherein said control means determines a driving time of said conveying screw. 1. A waste toner discharging method executed in an image forming apparatus having a collecting device for collecting, as waste toner, toner remaining on an image carrier after a toner image formed by toner is transferred onto the image carrier. ,
the collecting device has an outlet and contains the waste toner collected from the image carrier;
a conveying screw provided in the container and having wings that apply force to the waste toner toward the discharge port;
A method for discharging waste toner, comprising the step of determining a work amount of the conveying screw based on air pressure. Waste toner discharge executed by a computer that controls an image forming apparatus equipped with a collecting device that collects the toner remaining on the image carrier as waste toner after the toner image formed by the toner is transferred to the image carrier. a program,
the collecting device has an outlet and contains the waste toner collected from the image carrier;
a conveying screw provided in the container and having wings that apply force to the waste toner toward the discharge port;
A waste toner discharging program for causing the computer to execute a step of determining the amount of work of the conveying screw based on air pressure.

Images