JP2020181098A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can optimize the transferability of a toner image to a sheet, while preventing an increase in toner consumption.SOLUTION: An image forming apparatus 100 has image carriers 122, developing units 121, a transfer unit 130, a setting unit 190, and a control unit 190. The setting unit 190 sets a target process state. The control unit 190 controls the process state of the image forming apparatus 100. The process state of the image forming apparatus 100 includes the state of deterioration of toner in the developing units 121, and when the process state of the image forming apparatus 100 is the state of deterioration of toner in the developing units 121, the control unit 190 controls the deterioration state to achieve the target process state.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image forming apparatus.

An image forming device capable of printing an image on a paper having an uneven surface such as embossed paper (hereinafter referred to as "concavo-convex paper") is required according to the user's request for image quality, productivity, texture, etc. Has been done. In image formation, an important property that affects the quality of an image is transferability when a toner image is transferred from an image carrier to paper. The transferability of the toner image to the paper may change depending on the degree of unevenness on the surface of the paper, the state of the developer, the environment, and the like. Therefore, when printing on uneven paper, there is a possibility that the variation in image quality becomes large due to the difference in transferability.

In general, optimization of transferability requires repeated test printing while fine-tuning the process state setting of the image forming apparatus to find a process state in which optimum transferability can be obtained, which is a very laborious task. Can be. Further, since the state of the developer may change in the process of repeatedly using the image forming apparatus, it may be necessary to set the process state again.

In connection with this, Patent Document 1 discloses a technique for reducing the amount of charge of toner in a developing apparatus in order to suppress transfer defects of a toner image on uneven paper.

Japanese Unexamined Patent Publication No. 2016-114718

In the technique of Patent Document 1, the amount of charge of the toner in the developing apparatus is reduced by replacing a part of the toner in the developing apparatus or increasing the toner concentration. However, by forming a solid image in the entire image area, a high-density image is formed and the amount of charge of the toner is reduced, so that the toner in the developing device is excessively refreshed with respect to the image quality required by the user. There is a possibility that a lot of waste such as an increase in toner consumption may occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image forming apparatus capable of appropriately performing image quality while suppressing an increase in toner consumption.

The above object of the present invention is achieved by the following means.

(1) The image carrier, the developing section for developing the electrostatic latent image formed on the image carrier with toner, and the toner image on the image carrier developed by the developing section are transferred to paper. An image forming apparatus including a transfer unit includes a setting unit for setting a target process state and a control unit for controlling the process state of the image forming apparatus, and the process state of the image forming apparatus includes a transfer unit. , The deteriorated state of the toner in the developing unit is included, and when the process state of the image forming apparatus is the deteriorated state of the toner in the developing unit, the control unit targets by controlling the deteriorated state. An image forming apparatus that is in a process state.

(2) The process state of the image forming apparatus includes the charge amount of the toner in the developing section, the deterioration state of the toner in the developing section, the transfer bias in the transfer section, and the durability state of each process member of the image forming apparatus. , The image forming apparatus according to (1) above.

(3) The control unit further has a calculation unit for calculating the average residence time of the toner in the development unit, and the control unit consumes the toner in the development unit and replenishes the consumed toner to obtain the average residence time. A recovery process for recovering the deterioration of the toner in the developing unit by shortening the length, or a deterioration processing for promoting the deterioration of the toner in the developing unit by increasing the average residence time by stirring without replenishing the toner is executed. The deterioration state of the toner in the development unit is controlled so that the deterioration state of the toner in the development unit becomes the average toner residence time corresponding to the deterioration state of the target toner, according to the above (1) or (2). ). The image forming apparatus.

(4) The image carrier, the developing unit for developing the electrostatic latent image formed on the image supporting body with toner, and the toner image on the image supporting body developed by the developing unit are transferred to paper. In an image forming apparatus including a transfer unit, a setting unit for setting a target toner deterioration state, a calculation unit for calculating the average residence time of toner in the development unit, and a toner in the development unit are consumed. The recovery process for recovering the deterioration of the toner in the developing unit by replenishing the consumed toner to shorten the average residence time, or the recovery treatment for increasing the average residence time by stirring without replenishing the toner. It has a control unit that executes a deterioration process that promotes deterioration of the toner in the developing unit, and the control unit has a toner average in which the deterioration state of the toner in the developing unit corresponds to the target toner deterioration state. An image forming apparatus that controls the deterioration state of toner in the developing unit so as to have a residence time.

(5) The control unit executes the recovery process when the deterioration state of the toner in the developing unit exceeds the upper limit threshold value of the deterioration state of the target toner, and determines the deterioration state of the target toner. The image forming apparatus according to (3) or (4) above, which executes the deterioration process when the value falls below the lower limit threshold value.

(6) Further having an operation panel that accepts user input, the setting unit acquires a deteriorated state of toner corresponding to a target image on the operation panel selected by user input from a storage unit. The image forming apparatus according to any one of (1) to (5) above, which sets the deterioration state to the deterioration state of the target toner.

(7) When continuous printing is performed, the setting unit sets the toner deterioration state in the developing unit at the time of starting printing to the target toner deterioration state (1) to (1). The image forming apparatus according to any one of 5).

(8) The image forming apparatus according to any one of (1) to (7) above, wherein the control unit controls a deterioration state of toner in the developing unit at a timing according to a user's instruction.

(9) The image forming apparatus according to (8) above, wherein the setting unit sets the deterioration state of the toner in the developing unit at the timing to the deterioration state of the target toner.

(10) The image forming apparatus according to any one of (1) to (9) above, wherein the setting unit sets a deterioration state of the target toner based on information on paper used for printing. ..

(11) As information about the paper, the setting unit describes the target toner deterioration state when the paper used for printing is embossed paper, as compared with the case where the paper is plain paper or glossy paper. The image forming apparatus according to (10) above, which narrows the range of the above.

(12) The control unit controls the deterioration state of the toner in the developing unit in any one of (1) to (11) above, which executes control of the deterioration state of the toner in the non-image region between the image regions in the image carrier. The image forming apparatus described.

According to the present invention, by controlling the deterioration state of the toner in the developing apparatus, the deterioration state of the toner corresponding to the transferability desired by the user is obtained, so that the increase in the toner consumption is suppressed and the toner is transferred to the paper. The image quality of the toner image can be adjusted appropriately.

It is schematic cross-sectional view which illustrates the structure of the image forming apparatus which concerns on 1st Embodiment. It is a schematic block diagram which illustrates the structure of the image forming apparatus shown in FIG. It is a flowchart which illustrates the processing procedure of the control method of the image forming apparatus which concerns on 1st Embodiment. It is a schematic diagram which illustrates the transferability of the toner image to the embossed paper when the deterioration state of the toner is different. It is a schematic diagram conceptually exemplifying a table for a user to select transferability. It is a schematic diagram which illustrates the range of the deterioration state of the toner corresponding to the table shown in FIG. It is a graph which conceptually illustrates the control of the deterioration state of toner. It is a graph which shows the transition of the average residence time of toner for each print coverage. In the second embodiment, it is a schematic diagram conceptually illustrating a table for a user to select transferability. It is a schematic diagram which illustrates the range of the deterioration state of the toner corresponding to the table shown in FIG. It is a schematic diagram for demonstrating the setting of the deterioration state of the target toner in 3rd Embodiment. FIG. 5 is a schematic diagram illustrating a case where a recovery process is executed according to a user's instruction in the fourth embodiment. It is a graph which illustrates the result of having controlled the toner state. As a comparative example, it is a graph which illustrates the process of the conventional refresh mode which refreshes the toner in a developing apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted.

(First Embodiment)
FIG. 1 is a schematic cross-sectional view illustrating the configuration of the image forming apparatus according to the first embodiment, and FIG. 2 is a schematic block diagram illustrating the configuration of the image forming apparatus shown in FIG.

The image forming apparatus 100 shown in FIG. 1 is an image forming apparatus using an electrophotographic process, and is a so-called tandem type in which a color image is formed by arranging a plurality of photoconductor drums facing each other on an intermediate transfer belt. It is a color image forming apparatus.

The image forming apparatus 100 is used to form (print) an image on a paper which is a recording medium by using the scanned original image data. The image forming apparatus 100 can be, for example, an MFP (Multi-Function Peripheral) having a copy function, a printer function, and a scanning function.

<Structure of image forming apparatus 100>
The image forming apparatus 100 includes an image reading unit 110, an image forming unit 120, a transfer unit 130, a paper feeding unit 150, a paper conveying unit 160, a fixing unit 170, an operation display unit 180, and a control unit 190.

The image scanning unit 110 irradiates light from a light source on a document set at a predetermined scanning position on the platen or a document transported to a predetermined scanning position by an ADF (Auto Document Feeder) and reflects the light. An electric signal is generated by photoelectrically converting light with a light receiving element such as a CCD image sensor or a CMOS image sensor. The generated electric signal is subjected to A / D conversion, shading correction, filter processing, image compression processing, and the like, and is input to the image forming unit 120.

The image forming unit 120 is used to form an image on the paper 10 which is a recording medium by utilizing an electrophotographic process. The image forming unit 120 includes an image forming unit 12A for forming a yellow (Y) color image, an image forming unit 12B for forming a magenta (M) color image, and an image forming unit 12C for forming a cyan (C) color image. , Has an image forming unit 12D that forms a black (K) color image.

Each unit of the image forming unit 120 has a developing device 121, a photoconductor drum 122, a charging unit 123, and an optical writing unit 124, respectively.

The developing device 121 functions as a developing unit, and by adhering toner to the surface of the photoconductor drum 122, the electrostatic latent image is visualized by the toner to form a toner image. That is, monochrome toner images corresponding to yellow, magenta, cyan, and black are formed on the photoconductor drums 122 of the image forming units 12A, 12B, 12C, and 12D, respectively.

Each developing device 121 of the image forming units 12A to 12D contains a two-component developer composed of toner and a carrier having small particle sizes of different colors of yellow, magenta, cyan and black, respectively. As the two-component developer, a carrier having ferrite as the core and an insulating resin coated around it, a colorant such as carbon black as the main material, a charge control agent, and an external additive such as silica and titanium oxide were added. It consists of toner. The carrier has a particle size of 15 to 100 μm, the saturation magnetization is 10 to 80 emu / g, the toner has a particle size of 3 to 15 μm, the charging characteristic of the toner is a negative charging characteristic, and the average charge amount is -20 to -60 μC / g. As the two-component developer, a mixture of these carriers and toner so as to have a toner concentration of 4 to 10% by mass is used. In this embodiment, the toner is negatively charged.

The toner supply unit 125 conveys toner from a tank (not shown) that stores toner corresponding to each color, and supplies the toner to the developing apparatus 121.

The photoconductor drum 122 is an image carrier having a photosensitive layer made of a resin such as polycarbonate containing an organic photoconductor (OPC), and is configured to rotate at a predetermined speed.

The charging unit 123 is composed of a corona emission electrode arranged around the photoconductor drum 122, and charges the surface of the photoconductor drum 122 with the generated ions.

The optical writing unit 124 incorporates a scanning optical device, and exposes the charged photoconductor drum 122 based on the image data input from the image reading unit 110 to expose the potential of the exposed portion. To form a charge pattern (electrostatic latent image) corresponding to the image data.

The transfer unit 130 transfers the toner image on the photoconductor drum 122 developed by the developing device 121 to the paper 10. The transfer unit 130 includes an intermediate transfer belt 131, a primary transfer unit 132, a secondary transfer unit 140, and the like.

The intermediate transfer belt 131 is endless, is arranged on the side of the image forming units 12A to 12D, and is positioned so as to be in contact with the photoconductor drum 122. The intermediate transfer belt 131 is made of, for example, a polyimide film.

Monochrome toner images of each color formed in the image forming units 12A to 12D are sequentially transferred onto the intermediate transfer belt 131, and a toner image of a color in which yellow, magenta, cyan, and black layers are superimposed is formed. Will be done. The secondary transfer unit 140 is used to transfer the color toner image formed on the intermediate transfer belt 131 to the conveyed paper 10.

The paper feed unit 150 includes a plurality of paper feed trays 151 and 152 for accommodating the paper 10. Paper such as plain paper, coated paper, and embossed paper are stored in the paper feed trays 151 and 152 for each paper type or paper size. The paper 10 is fed to the paper transport unit 160 one by one.

The embossed paper is, for example, a paper in which the surface of art paper or coated paper is embossed to give fine irregularities such as satin finish, cloth grain, and silk grain. There are many uses that make use of the texture, such as unevenness that reproduces the texture of leather such as "Rezac 66" and unevenness of small flowers such as "Edo Kozome Hana". Embossed paper can be mainly used for book covers, covers, tickets, packages, wallpapers and the like.

The paper transport unit 160 transports the paper 10 in the image forming apparatus 100. The paper transport unit 160 has a paper transport path 161 for transporting the paper 10 and a plurality of transport rollers 162.

The paper 10 fed from the paper feed unit 150 is rotationally driven by a plurality of transport rollers 162 by a drive unit (motor (not shown)), and is conveyed along the paper transport path 161. The paper 10 is conveyed to the secondary transfer unit 140 via the resist roller 16R, and after the toner image is transferred by the secondary transfer unit 140, it is conveyed to the fixing unit 170.

The fixing unit 170 is used for fixing the toner image transferred to the paper 10, and has a heating roller 171 and a pressure roller 172. When the paper 10 passes between the heating roller 171 and the pressure roller 172, pressure and heat are applied to melt the toner, so that the toner image is fixed. The paper 10 on which the image is fixed is discharged from the paper ejection portion to the outside of the image forming apparatus 100.

The operation display unit 180 receives a user's instruction and displays a message or the like to the user on the screen. The operation display unit 180 has a keyboard and an operation panel. The user inputs an instruction to the image forming apparatus 100 by operating the keyboard or the operation panel. In addition, input information, various setting information, warning messages, etc. are displayed on the screen.

The control unit 190 integrally controls each unit of the image reading unit 110, the image forming unit 120, the transfer unit 130, the paper feeding unit 150, the paper conveying unit 160, the fixing unit 170, and the operation display unit 180 to form an image. The function of the device 100 is realized.

The control unit 190 has a CPU (Central Processing Unit) 191, an auxiliary storage unit 192, a RAM (Random Access Memory) 193, and a ROM 194 (Read Only Memory), and these components are connected to each other by an internal bus. There is.

The auxiliary storage unit 192 stores an operating system, various application programs, a control program for controlling each part of the image forming apparatus 100, and the like.

The RAM 193 temporarily stores print image data and the like as a result of arithmetic processing by the CPU 191. Further, in the present embodiment, the RAM 193 functions as a storage unit and is used to store the target process state of the user. The details of the process state will be described later.

The ROM 194 stores various parameters and the like used by the CPU 191 in arithmetic processing and the like.

Further, the control unit 190 has an interface (not shown) for communicating with a device such as a client terminal connected to the network, receives a print job from the client terminal, and transmits the print job to the image forming unit 120.

The CPU 191 realizes various functions of the image forming apparatus 100 by executing a control program. For example, the image forming apparatus 100 discharges (discards) a part of the toner (developer) to the outside of the developing apparatus 121 and replenishes new toner in order to replace the toner accumulated in the developing apparatus 121. It has a function (referred to as "refresh mode") of refreshing the toner in the developing apparatus 121. This is because, for example, when printing images having low print coverage (printing rate) continuously, the amount of toner consumed in the developing apparatus 121 is reduced, so that the average residence time of the toner in the developing apparatus 121 becomes long. With toner having a long residence time, the toner deteriorates due to friction between the developing agents due to stirring and with the members of the developing apparatus 121. Specifically, when the toner additive is peeled off from the toner or buried in the surface, the toner deteriorates and its charge amount and adhesive force (release property) change, and the toner image on the paper is displayed. It affects the transferability (hereinafter, also simply referred to as "transcription property"). The refresh mode is for dealing with this and the like, and corresponds to the recovery process described later. In the refresh mode, the toner supply unit 125 replenishes the developing device 121 with toner corresponding to the amount consumed so as to maintain the toner concentration of the developing agent in the developing device 121 at a predetermined value. The replenished toner is mixed and stirred with the carrier by the stirring screw inside the developing device 121, so that a predetermined amount of electric charge is applied to the toner.

However, it may not be possible to realize or maintain the image quality (transferability) required by the user when the printing paper is uneven paper only by executing the above-mentioned refresh mode. Therefore, the image forming apparatus 100 of the present embodiment is configured so that the deterioration state of the toner in the developing apparatus 121 can be controlled from the viewpoint of realizing or maintaining the transferability desired by the user.

More specifically, the control unit 190 controls the process state of the image forming apparatus 100, and controls the deterioration state of the toner in the developing device 121 when the process state is the deterioration state of the toner in the developing device 121. By doing so, the target toner is in a deteriorated state. The process state includes, for example, the amount of toner charged in the developing device 121, the transfer bias in the transfer unit 130, the durability state of each process member, and the like, in addition to the deterioration state of the toner in the developing device 121.

The control unit 190 can calculate the toner charge amount based on, for example, the developing current and the toner adhesion amount. The developing current is a current flowing between the developing roller (not shown) and the photoconductor drum 122 during development. The developing current is proportional to the total charge of the transferred toner per unit time. The control unit 190 calculates the total charge amount of the developed toner from the developing current measured by the ammeter, and based on the density value detected by the density sensor (not shown) arranged on the intermediate transfer belt 131, the control unit 190 calculates the total charge amount of the developed toner. Calculate the amount of toner adhered. The control unit 190 calculates the toner charge amount based on the total toner charge amount and the toner adhesion amount.

In the control of the toner deterioration state, a recovery process or a deterioration process can be executed depending on the comparison result between the target process state and the current process state of the image forming apparatus 100. The recovery process is a process of recovering the deterioration of the toner in the developing device 121 by discharging a part of the toner from the developing device 121 and supplying the toner from the toner supply unit 125 to the developing device 121. Further, the deterioration treatment is a treatment for accelerating the deterioration of the toner in the developing device 121 by stirring the toner in the developing device 121 without discharging the toner and replenishing the toner.

The recovery process and the deterioration process may be executed by instructing the user through the operation display unit 180, and as will be described later, it is automatically determined that the paper to be printed is uneven paper such as embossed paper. It may be executed when it is detected and the paper is uneven paper such as embossed paper.

<Control method>
Hereinafter, the processing procedure of the control method of the image forming apparatus 100 will be described with reference to FIGS. 3 to 8. FIG. 3 is a flowchart illustrating the processing procedure of the control method of the image forming apparatus 100 according to the present embodiment. The processing of the flowchart of FIG. 3 is realized by the CPU 191 of the control unit 190 executing the control program. Further, FIG. 4 is a schematic diagram illustrating the transferability of the toner image to the embossed paper when the deterioration state of the toner is different. Further, FIG. 5 is a schematic diagram conceptually illustrating a table for the user to select transferability, and FIG. 6 is a schematic diagram illustrating a range of toner deterioration states corresponding to the table shown in FIG. .. Further, FIG. 7 is a graph that conceptually illustrates the control of the deterioration state of the toner. In FIG. 7, the vertical axis of the graph is the deterioration state of toner, and the horizontal axis is the number of printed sheets. Further, FIG. 8 is a graph showing the transition of the average residence time of the toner for each print coverage.

As shown in FIG. 3, first, the target process state is set (step S101). The process state is, for example, an individual or a combination of a plurality of charge amounts of toner in the developing device 121, deterioration state of toner in the developing device 121, transfer bias in the transfer unit 130, durability state of each process member, and the like. Can be set with. The control unit 190 functions as a setting unit and stores the target process state in the RAM 193.

In the present embodiment, as the process state of the image forming apparatus 100, paying particular attention to the toner state in the developing apparatus 121, the toner deterioration state is controlled based on the target toner deterioration state and the current toner deterioration state. Will be described. The deterioration state of the toner is represented by, for example, the average residence time [sec] (described later) of the toner that is agitated without being consumed in the developing apparatus 121.

Deterioration of the toner in the developing apparatus 121 may affect the transferability. Generally, when the deterioration of the toner is small, the transferability is high, and when the deterioration of the toner is large, the transferability is low. In the present embodiment, the control unit 190 determines an appropriate deterioration state of the toner in the developing device 121 according to the transferability required by the user.

The transferability can be changed depending on, for example, the type of paper, particularly the degree of unevenness (surface roughness) on the surface of the paper. For example, when printing is performed on a glossy paper having a substantially smooth surface roughness such as an OK top coat and an embossed paper having an unevenness of about 100 [μm] such as Rezac 66, the deterioration state of the toner is about the same. However, there may be a large difference in transferability between the two. Further, even if the toner is deteriorated so that there is no problem with glossy paper, the transferability may be poor (non-uniform) with respect to embossed paper.

For example, even when the deterioration state of the toner is in a range that does not make a difference in transferability with respect to glossy paper, for example, as shown in FIG. 4, when a difference in transferability is made with respect to embossed paper. There can be. State 1, which is an example of a halftone image, represents the transferability when the deterioration of the toner is the largest. In state 1, there are many recesses W (white portions) to which toner has not adhered. Further, the state 2 represents the transferability when the deterioration state of the toner is moderate. In the state 2, there is a portion G (gray portion) where the toner is less adhered and a recess W (white portion) where the toner is not adhered. Further, the state 3 represents the transferability when the deterioration state of the toner is the smallest. In the state 3, the portion G (gray portion) where the toner is less adhered is generally large, but the recess W (white portion) where the toner is not adhered is small. Therefore, the transferability is lowest in state 1, moderate in state 2, and highest in state 3. The solid image states 1 to 3 are the same as in the halftone image.

Usually, in a paper having a smooth surface such as glossy paper, the quality in a uniformly transferred state (for example, equal to or higher than the state 3 in the case of the embossed paper of FIG. 4) is required. However, with special paper such as embossed paper, the quality of the uniformly transferred state is not always required, and sometimes, when the texture is emphasized, the quality is uniformly transferred as in the state 1 or the state 2 of FIG. Quality in the unfinished state may be required.

In the present embodiment, the user selects the image quality (transferability) from the operation panel, and the target toner deterioration state corresponding to the selected image quality is set. For example, as shown in FIG. 5, the operation display unit 180 displays a plurality of patch images (target images) for selecting transferability on the operation panel, and the user can display numbers 1 to 4 corresponding to the patch images. , Select the transferability by operating the operation panel. FIG. 5 illustrates a table in which transferability can be selected from four options from Nos. 1 to 4, and patch images of halftone images and solid images are exemplified for each of the four transferability.

The first option has a strong meaning of "emphasis on texture" and has low transferability. That is, the toner image is not uniformly transferred. No. 1 can be used, for example, when it is desired to print on embossed paper (for example, Rezac 66) while leaving the texture of leather. On the other hand, option No. 4 has a strong meaning of "emphasis on uniformity", and the toner image is transferred uniformly. No. 4 is used when it is desired to improve the image quality by allowing the toner to get on the recesses. The options No. 2 and No. 3 have an intermediate meaning between No. 1 and No. 4, and the transferability is also medium.

As shown in FIG. 6, the range of the deteriorated state of the toner is associated with the transferability selected in FIG. For convenience of explanation, a curve 201 showing the deterioration state of the toner in the developing device 121 with respect to the number of printed sheets is shown in normal printing when printing is continued without executing the refresh mode. In the example shown in FIG. 6, N1 sheets have already been printed before the start of printing this time, and the deterioration state of the toner at the start of printing is L1. As the number of printed sheets increases, the deterioration of the toner progresses. This is because the external additive adhering to the toner surface is desorbed or buried, and the amount of charge is reduced. Its progress gradually slows down and approaches Ls.

In the present embodiment, the toner deteriorated states L1 to Ls are divided into four ranges (L1 to L2, L2 to L3, L3 to L4, L4 to Ls) having the same width and not overlapping each other. It is associated with each of the transferability 4-1 shown in FIG. For example, when the user selects the second transferability in FIG. 5 (displayed in gray), the target toner deterioration state range is in the second range (L3 to L4) as shown in FIG. Correspond.

In the above example, the case where the user selects the transferability by selecting the patch image and determines the target toner deterioration state corresponding to the transferability has been described, but is limited to such a case. Not done. For example, the user may operate the operation panel to directly input the deterioration state of the target toner.

For each transferability, the range of toner deterioration can be adjusted in consideration of the type of paper to be printed and the like. More specifically, the control unit 190 acquires information such as the paper type of the paper to be printed from the paper type information selected by the user when setting the tray information, and the range of the toner deterioration state based on this information. Can be adjusted.

For example, when the set paper type is glossy paper or the like, the degree of unevenness on the surface is small, so that the fluctuation range of transferability is small. Therefore, the range of the deteriorated state of the toner can be expanded as compared with the uneven paper. On the other hand, when the set paper type is embossed paper, the range of the target toner deterioration state is narrowed as compared with the case where the paper type is glossy paper.

In addition, the deterioration state of the target toner is recorded in the paper profile in which the paper settings frequently used by the user are registered in advance, and the paper profile is always the optimum target toner deterioration state for the user. May be updated.

In addition, since it is often the case that the roughness cannot be determined even if the paper type information is acquired, the surface of the paper of the set paper type is automatically read to determine the roughness, and if necessary, the target is set. The range of the deterioration state of the toner may be adjusted. As an automatic discrimination method, a reflective measuring device that detects the surface condition of the paper is installed in the tray, or a contact-type surface roughness measuring device is installed in the paper passing path to obtain the surface roughness. Can be determined.

The range of toner deterioration states set for each transferability is stored in the RAM 193.

Returning to FIG. 3 again, the target process state and the current process state are compared (step S102). The control unit 190 functions as a setting unit and acquires a target toner deterioration state as a target process state from the RAM 193. Further, the control unit 190 acquires, for example, the deterioration state of the toner in the developing device 121 as the current process state. The deterioration state of the toner in the developing apparatus 121 is expressed using, for example, the following average toner residence time (also referred to as “toner average age” or “deterioration index”).

Toner average residence time [sec] = (pre-process average residence time [sec] + developing device drive time [sec]) x (developing device toner amount [g] x coefficient-toner consumption [g]) / (development Toner amount [g] x coefficient of the device). Here, the average pre-process residence time is the average toner residence time [sec] before the start of the printing operation. The control unit 190 functions as a calculation unit and calculates the average toner residence time.

The control unit 190 determines whether or not the deterioration state of the toner in the developing device 121 is within the range of the deterioration state of the target toner. For example, when the user selects the second transferability in FIG. 5, it is determined whether or not the target toner deterioration state range is in the range of L3 to L4.

Next, the toner deterioration state in the developing apparatus 121 is controlled (step S103). Based on the determination result in step S102, the control unit 190 controls the toner deterioration in the developing apparatus 121 so that the current toner deterioration state falls within the target toner deterioration state. More specifically, the control unit 190 determines the deterioration state of the toner in the developing device 121 so that the deterioration state of the toner in the developing device 121 becomes the average toner residence time corresponding to the deterioration state of the target toner. To control.

For example, as shown in FIG. 7, the curve 202 represents the deterioration state of the toner with respect to the number of printed sheets when printing is continued until the number of printed sheets reaches N in a predetermined print coverage. The toner in the developing apparatus 121 deteriorates as the number of printed sheets increases until the number of printed sheets reaches N. Further, the transferability decreases as the deterioration of the toner in the developing apparatus 121 progresses.

In the present embodiment, for example, the control unit 190 alternately performs recovery processing and deterioration processing after the number of printed sheets reaches a predetermined number M, so that the deterioration state of the toner in the developing device 121 is the target. Control so that it falls within the range of deterioration. More specifically, the control unit 190 executes a recovery process when the current toner deterioration state exceeds the target toner deterioration state range, and executes a deterioration process when the current toner deterioration state falls below the above range. .. In the recovery process, the deterioration of the toner in the developing device 121 is recovered by consuming the toner in the developing device 121 and replenishing the consumed toner to shorten the average residence time. Further, in the deterioration treatment, deterioration of the toner in the developing apparatus 121 is promoted by prolonging the average residence time by stirring without replenishing the toner.

Further, the upper limit threshold value 301 and the lower limit threshold value 302 correspond to the deterioration states L4 and L3 of the toner, respectively. The control unit 190 executes a recovery process when the deterioration of the toner in the developing device 121 exceeds the upper limit threshold value 301 (L4), and executes a deterioration process when the deterioration is lower than the lower limit threshold value 302 (L3).

Reference numerals 203 and 204 represent changes in the deterioration state of the toner with respect to the number of printed sheets during the recovery process and the deterioration process, respectively. In the example shown in FIG. 7, the recovery process is performed in the non-image areas between the image areas on the photoconductor drum 122. The control unit 190 calculates the amount of toner replacement required to maintain control that keeps the current toner deterioration state within the range of the target toner deterioration state. Subsequently, the control unit 190 calculates the toner shortage from the print coverage amount during printing and the toner replacement amount.

Based on the calculation result of the toner shortage, the control unit 190 controls, for example, to discharge the toner in the developing device 121 for each paper and replenish the toner in the developing device 121. Alternatively, the control unit 190 may control to accumulate the shortage of toner, pause printing at a timing exceeding a predetermined threshold value, and collectively discharge and replenish the toner.

In FIG. 8, for example, when it is desired to maintain the quality at the level of the broken line 303, the quality of the image is satisfied by always discharging and supplying the print coverage so as to be 3%.

On the other hand, in the example shown in FIG. 7, the deterioration process is performed in the image region of the photoconductor drum 122. That is, in this case, the deterioration treatment is carried out by the deterioration of the toner progressing in the normal image formation.

Further, the deterioration treatment may be performed in a non-image region between image regions in the photoconductor drum 122. In this case, image formation is not performed by the developing device 121, and the toner in the developing device 121 is agitated without discharging the toner and supplying the toner, so that deterioration of the toner in the developing device 121 is promoted.

In this way, the control unit 190 compares the deterioration state of the target toner with the deterioration state of the current toner, and controls the deterioration state of the toner in the developing device 121 according to the comparison result. The desired transferability can be continuously achieved.

In addition, although FIG. 6 illustrates the case where the range of the deteriorated state of each toner has a uniform width, the width of the range may be different depending on the transferability. For example, when both the transferability of No. 2 and No. 3 are acceptable, the upper limit threshold value and the lower limit threshold value are set within the range including the range of the deterioration state of the toner corresponding to the transferability of No. 2 and No. 3. May be good. As a result, the range that the user can tolerate is widened, the frequency of execution of the recovery process is reduced, and the decrease in productivity can be suppressed.

Returning to FIG. 3 again, it is determined whether or not printing is completed (step S104). The processes of steps S102 and S103 are repeated until printing is completed, for example, when the number of printed sheets reaches a predetermined number. When printing is completed (step S104: YES), the process ends (end). On the other hand, when the printing process is not completed (step S104: NO), the process returns to the process of step S102.

The image forming apparatus 100 of the first embodiment described above has the following effects.

By controlling the deterioration state of the toner in the developing apparatus 121, the deterioration state of the toner corresponding to the transferability desired by the user can be obtained, so that the transferability can be optimized while suppressing the increase in the toner consumption.

(Second Embodiment)
In the first embodiment, the case where transferability is selected from the viewpoint of texture and uniformity has been described. In the second embodiment, the case where transferability is selected from the viewpoint of quality stability and productivity will be described. In order to avoid duplication of description, detailed description of the same configuration as that of the first embodiment will be omitted.

FIG. 9 is a schematic diagram conceptually illustrating a table for the user to select transferability in the second embodiment, and FIG. 10 illustrates a range of toner deterioration states corresponding to the table shown in FIG. It is a schematic diagram.

FIG. 9 illustrates a table in which transferability can be selected from four options A to D from the viewpoint of quality stability and productivity. As shown in FIG. 10, the range of the deteriorated state of the toner is associated with the transferability selected in FIG. In the present embodiment, the deteriorated states L1 to L8 of the toner overlap each other and are divided into four ranges (L4 to L5, L3 to L6, L2 to L7, L1 to L8) having different widths, and are shown in FIG. It is associated with each of the transferability A to D.

Option A has a strong meaning of "priority for quality stability" and has the smallest transferability fluctuation range. Therefore, while A can maintain stable transferability, it is necessary to frequently perform a recovery process. On the other hand, option D has a strong meaning of "productivity priority" and has the largest transferability fluctuation range. Therefore, although the transferability varies, the number of times the recovery process is executed can be suppressed to a small number. The options B and C have an intermediate meaning between A and D, and the transferability fluctuation range is also medium.

For example, when the user selects the transferability of B in FIG. 9 (displayed in gray), the range of the target toner deterioration state corresponds to the range of B (L3 to L6) as shown in FIG. .. The control unit 190 controls so that the current deterioration state of the toner falls within the range of B.

In this way, the user can select the range of the deterioration state of the toner by using the stability of quality and the productivity as indicators.

The image forming apparatus 100 of the second embodiment described above exerts the following effects in addition to the effects of the first embodiment.

Since transferability can be selected from the viewpoints of "quality stability priority" and "productivity priority", it is possible to expand the choices regarding transferability to the user.

In the first embodiment, it is explained that transferability is selected from the viewpoints of "texture-oriented" and "uniformity-oriented", and in the second embodiment, "quality stability is prioritized" and "productivity is emphasized". Although it has been explained that the transferability is selected from the viewpoint of "priority", the transferability may be selected in consideration of two viewpoints, or the transferability may be selected based on one of the viewpoints.

For example, for users whose quality requirements often change for each print job, transferability is selected from the viewpoints of "texture-oriented" and "uniformity-oriented" for each print job, and the selected transferability is maintained. It is considered suitable. Further, when the user has a certain fixed requirement for the quality of the image, the level of stability and productivity may be changed with respect to the required image quality. It can be configured to select the most suitable selection method for transferability according to the image quality required by the user.

(Third Embodiment)
In the first and second embodiments, a case where the transferability is selected by the user and the target toner deterioration state is set based on the selected transferability has been described. In the third embodiment, a case where the deterioration state of the toner at the start of printing is set as the target deterioration state of the toner will be described. In order to avoid duplication of description, detailed description of the same configuration as that of the first embodiment will be omitted.

FIG. 11 is a schematic diagram for explaining the setting of the deterioration state of the target toner in the third embodiment.

Normally, as the printing is repeatedly executed, the deterioration of the toner in the developing apparatus 121 and each process member of the image forming apparatus 100 progresses. Therefore, the deteriorated state of the toner in the developing device 121 is considered to be the most desirable state at the time when the printing job is started, and the quality of the image formed in the deteriorated state of the toner is considered to be the quality acceptable to the user. Be done. Therefore, it is desirable that the deteriorated state of the toner in the developing apparatus 121 is maintained at the state at the time when printing is started when continuous printing is performed. Also, one print job preferably maintains the same level of quality in all printed matter.

Therefore, as shown in FIG. 11, in the present embodiment, the control unit 190 stores the toner deterioration state at the start of printing as the target toner deterioration state (quality standard 304) in the RAM 193, and stores the current toner. The deterioration state of the toner is controlled so as to approach the deterioration state of the target toner and maintain the deterioration state.

The image forming apparatus 100 of the third embodiment described above exerts the following effects in addition to the effects of the first and second embodiments.

Even if the target toner deterioration state is not set by the user input, the image quality desired by the user can be continuously provided.

(Fourth Embodiment)
In the first to third embodiments, when the current toner deterioration state is out of the target toner deterioration state, the control unit 190 determines to start execution of the recovery process or the deterioration process. The case was explained. In the fourth embodiment, the case where the execution of the recovery process or the deterioration process is started according to the instruction of the user will be described. In order to avoid duplication of description, detailed description of the same configuration as that of the first embodiment will be omitted.

FIG. 12 is a schematic diagram illustrating a case where the recovery process is executed according to the instruction of the user in the fourth embodiment.

For example, even if the deterioration state of the toner in the developing apparatus 121 at the start of printing is set as the deterioration state of the target toner, the user can see the deterioration state of the toner due to the use of the image forming apparatus 100 and the deterioration state of each process member. Deterioration is difficult to predict. Therefore, while the user uses the image forming apparatus 100, the quality of the printed image may be unexpected.

Therefore, as shown in FIG. 12, in the present embodiment, when the user sees the image printed on the paper and determines that the quality is unacceptable during the printing of one print job, the printing is interrupted. Then, it is possible to execute the recovery process at the timing Tr1 specified by the user.

In this case, the range of the target toner deterioration state can be updated at the timing Tr1. For example, as the range of the deterioration state of the target toner as a new target, the range of the deterioration state of the target toner described in the first and second embodiments described above can be applied. The set range of the target toner deterioration state is stored in the RAM 193.

Further, the quality standard described in the third embodiment may be set instead of the range of the deteriorated state of the toner. Further, instead of setting a new range, a predetermined refresh amount may be used.

Further, in addition to the recovery process, the user may set the timing of the deterioration process for promoting the deterioration of the toner at an arbitrary timing.

The timing of the recovery process and the deterioration process may be set a plurality of times as needed. Further, the timing of the recovery process and the deterioration process can be determined by user input through the operation display unit 180, respectively.

Further, it is assumed that the quality standard 305 and the upper limit threshold value 306 are set, and the deterioration state of the toner at the start of printing is set in the quality standard 305. For example, if the user determines that the quality of the image is unacceptable during printing and executes the recovery process at the timing Tr1, the control unit 190 determines that the transferability is not sufficient, and starts from the upper limit threshold value 306. The upper limit threshold value 307, which is closer to the quality standard 305, is changed to improve the transferability. As a result, the quality of the image desired by the user can be brought closer to the subsequent printing.

Although not shown, when a quality standard and a lower limit threshold value are set and the user instructs deterioration processing, it is determined that the transferability is too high. Therefore, the control unit 190 uses the lower limit threshold value as the quality standard. Change to get closer.

The image forming apparatus 100 of the fourth embodiment described above exerts the following effects in addition to the effects of the first to third embodiments.

Since the execution of the recovery process or the deterioration process can be started at an arbitrary timing Tr1 specified by the user, the transferability desired by the user can be approached at an early stage. Therefore, the quality of the image printed on the paper 10 can be brought close to the quality desired by the user at an early stage.

<Example>
FIG. 13 is a graph illustrating the result of controlling the toner deterioration state. In this embodiment, 11,000 sheets (11 Kp) of OK top-coated paper were printed, and then the paper was switched to embossed paper for printing. The print coverage was 1%. The basis weight of the OK top coated paper was 128 [gsm], and the basis weight of the embossed paper (Rezac 66) was 151 [gsm]. Although not shown in FIG. 13, in the OK top-coated paper, the transferability maintained the highest rank (R5) regardless of the average toner residence time. The level of transferability is indicated by rank (R1 to R5 (R1 to R3.5 are not described)). R1 is the lowest and R5 is the highest.

On the other hand, the transferability of the embossed paper decreased to R4 when the number of printed sheets was 11 Kp. Therefore, in this embodiment, the current toner deterioration state (toner average residence time is about about) is set in R4.5 to R5 (the region between the upper limit threshold value 309 and the lower limit threshold value 308) as the transferability rank desired by the user. A recovery process was performed from 5500 [sec]) to the target toner deterioration state (for example, the toner average residence time in the range of 1000 to 3000 [sec]). More specifically, as a recovery process, the control unit 190 discharges the toner corresponding to the refresh amount and controls the developing device 121 so as to replenish the same amount. As a result, the average toner residence time recovers to 1000 [sec]. did. The refresh amount (that is, the amount of toner supplied to the developing device 121) is defined by the following mathematical formula.

Refresh amount [g] = (toner average residence time [sec] -threshold [sec]) × developer toner amount [g] × coefficient / toner average residence time [sec]. Here, the threshold value may be either an upper limit threshold value or a lower limit threshold value. It is also possible to use the average value of the upper limit threshold value and the lower limit threshold value. For example, when the target toner deterioration state is in the range of the toner average residence time of 1000 to 3000 [sec], the value of the upper limit threshold value 309 is 3000, the value of the lower limit threshold value 308 is 1000, and the average value of the upper limit and lower limit threshold values (3000 + 1000). Either ÷ 2 = 2000 can be used. In this way, the refresh amount is calculated based on the target toner deterioration state range (threshold value).

Subsequently, after the toner average residence time was recovered to 1000 [sec], printing was continued by switching to embossed paper (Rezac 66) while maintaining the print coverage at 1%. As a result, the deterioration of the toner was accelerated, and the average toner residence time then reached the upper limit threshold value 309 when the number of printed sheets was about 15 kp. Then, when the upper limit threshold value 309 was exceeded, the recovery process to the target process state was performed.

Further, after that, since the user instructed the recovery process at the timing Tr2 in which the number of printed sheets was about 20 kp, the recovery process was executed.

By alternately repeating the recovery treatment and the deterioration treatment in this way, the transferability could always be maintained within the range of the predetermined width a. As a result, the image quality could always be maintained within a predetermined range.

In the above-mentioned example, the case where the average toner residence time reaches the upper limit threshold value 309 during the deterioration treatment has been described. However, for example, when printing is performed with high coverage, the lower limit of the average toner residence time is due to the recovery treatment. It can occur that the threshold 308 is interrupted.

In that case, it is also possible to adjust in the direction of adding the average toner residence time by calculating the developer drive time using a mathematical formula for calculating the average toner residence time.

<Comparison example>
FIG. 14 is a graph illustrating, as a comparative example, the processing of the conventional refresh mode for refreshing the toner in the developing apparatus 121.

The curve of reference numeral 201 represents the deterioration state of the toner with respect to the number of printed sheets when printing is continued with a predetermined print coverage. In the conventional refresh mode, a target value 310 is set so that sufficient transferability can be obtained for any kind of paper with respect to the deterioration state of the toner. The target value 310 is, for example, a value of the deterioration state of the toner, which is aimed at being able to transfer the toner to the uneven paper in a state where the toner is uniformly applied to all the irregularities on the surface. When the current deterioration state of the toner reaches the target value 310, the control unit 190 discharges (discards) a part of the toner to the outside of the developing apparatus 121 and replenishes new toner. As a result, the deterioration of the toner in the developing apparatus 121 is recovered.

However, in the case of uneven paper, it may not be necessary to transfer the toner uniformly to all the unevenness because the texture of the paper is left depending on the user. The transferability 311 required by the user is shown by a broken line. Therefore, there is a discrepancy between the target value 310 and the transferability 311 required by the user. As a result, the quality of the image printed on the uneven paper may be unsatisfactory for the user. In addition, repeated test printing may require extra adjustment time, which may increase the amount of toner used, spoiled paper, replacement of consumables, and the like.

As described above, the image forming apparatus 100 has been described in the embodiment. However, it goes without saying that the present invention can be appropriately added, modified, and omitted by those skilled in the art within the scope of the technical idea.

100 image forming device,
110 image reader,
120 image forming part,
121 developing equipment,
122 Photoreceptor drum,
123 charged part,
124 Optical writing unit,
125 Toner Supply Unit,
130 Transcription section,
131 Intermediate transfer belt,
132 Primary transfer unit,
140 Secondary transfer unit,
150 paper feed section,
160 Paper carrier,
161 Paper transport path,
162 transport roller,
170 Fixing part,
180 Operation display,
190 Control unit,
191 CPU,
192 Auxiliary storage,
193 RAM,
194 ROM.

Claims (12)

Image carrier and
A developing unit that develops an electrostatic latent image formed on the image carrier with toner, and
In an image forming apparatus including a transfer unit for transferring a toner image on the image carrier developed by the developing unit to paper.
A setting unit that sets the target process state,
It has a control unit that controls the process state of the image forming apparatus.
The process state of the image forming apparatus includes a deteriorated state of toner in the developing unit.
The control unit
When the process state of the image forming apparatus is the deteriorated state of the toner in the developing unit, the image forming apparatus sets the target process state by controlling the deteriorated state. The process state of the image forming apparatus is
The image forming apparatus according to claim 1, which includes a charge amount of toner in the developing section, a deteriorated state of toner in the developing section, a transfer bias in the transfer section, and a durability state of each process member of the image forming apparatus. Further, it has a calculation unit for calculating the average residence time of toner in the developing unit.
The control unit
A recovery process that recovers the deterioration of the toner in the developing unit by shortening the average residence time by consuming the toner in the developing unit and replenishing the consumed toner, or by stirring without replenishing the toner. Deterioration treatment that promotes deterioration of the toner in the developing unit by lengthening the average residence time is executed.
The first or second aspect of the present invention, wherein the deterioration state of the toner in the developing unit is controlled so that the deterioration state of the toner in the developing unit becomes the average toner residence time corresponding to the deterioration state of the target toner. Image forming device. Image carrier and
A developing unit that develops an electrostatic latent image formed on the image carrier with toner, and
In an image forming apparatus including a transfer unit for transferring a toner image on the image carrier developed by the developing unit to paper.
A setting unit that sets the target toner deterioration state, and
A calculation unit that calculates the average residence time of toner in the developing unit,
A recovery process that recovers the deterioration of the toner in the developing unit by shortening the average residence time by consuming the toner in the developing unit and replenishing the consumed amount of toner, or by stirring without replenishing the toner. It has a control unit that executes a deterioration process that promotes deterioration of the toner in the developing unit by increasing the average residence time.
The control unit
An image forming apparatus that controls the deterioration state of the toner in the developing unit so that the deterioration state of the toner in the developing unit becomes the average toner residence time corresponding to the deterioration state of the target toner. The control unit
When the deterioration state of the toner in the developing unit exceeds the upper limit threshold value of the deterioration state of the target toner, the recovery process is executed, and when the deterioration state of the toner in the development unit falls below the lower limit threshold value of the deterioration state of the target toner. The image forming apparatus according to claim 3 or 4, which executes deterioration processing. It also has an operation panel that accepts user input.
The setting unit
1. The deterioration state of the toner corresponding to the target image on the operation panel selected by the user input is acquired from the storage unit, and the deterioration state is set to the deterioration state of the target toner. 5. The image forming apparatus according to any one of 5. The setting unit
The image according to any one of claims 1 to 5, which sets the toner deterioration state in the developing unit at the time when printing is started to the target toner deterioration state in the case of continuous printing. Forming device. The control unit
The image forming apparatus according to any one of claims 1 to 7, which controls the deterioration state of toner in the developing unit at a timing according to a user's instruction. The setting unit
The image forming apparatus according to claim 8, wherein the deterioration state of the toner in the developing unit at the timing is set to the deterioration state of the target toner. The setting unit
The image forming apparatus according to any one of claims 1 to 9, wherein a deterioration state of the target toner is set based on information about a paper used for printing. The setting unit can be used as information about the paper.
When the paper used for printing is embossed paper, compared with the case where the paper is plain paper or glossy paper,
The image forming apparatus according to claim 10, wherein the range of the deteriorated state of the target toner is narrowed. The control unit
The image forming apparatus according to any one of claims 1 to 11, wherein the control of the deterioration state of the toner in the developing unit is executed in a non-image region between image regions in the image carrier.