Image formation apparatus

Abstract

To enable excellent transfer by correcting the transfer voltage even for an unknown medium for which transfer conditions have not been determined.SOLUTION: An image formation apparatus according to the present disclosure comprises: an image carrier that carries a developer image formed by a developer; a transfer voltage application unit that applies a transfer voltage for transferring the developer image to a medium; a transfer unit that receives application of the transfer voltage from the transfer voltage application unit and transfers the developer image on the image carrier to the medium; and a transfer control unit that controls the transfer voltage of the transfer voltage application unit. The transfer control unit derives a transfer voltage value that enables excellent transfer to the medium for each medium width for each of a plurality of media having different medium widths, and derives a corrected transfer voltage corresponding to the medium width of the medium by using the transfer voltage value for each medium width.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus. [Background technology]

[0002] Patent Document 1 discloses that a transfer bias is corrected according to the humidity inside the image forming apparatus, the type of medium, and other factors before transfer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-286466 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when printing using an unknown medium for which transfer conditions are not defined, there is a problem in that it is difficult to set the transfer voltage.

[0005] Therefore, there is a demand for an image forming apparatus that can correct the transfer voltage and achieve good transfer even when using an unknown medium for which the transfer conditions are not defined. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the image forming apparatus disclosed in the first disclosure includes (1) an image carrier that carries a developer image formed by a developer, (2) a transfer voltage application unit that applies a transfer voltage to transfer the developer image to a medium, (3) a transfer unit that receives the transfer voltage from the transfer voltage application unit and transfers the developer image on the image carrier to the medium, and (4) a transfer control unit that controls the transfer voltage of the transfer voltage application unit, and is characterized in that the transfer control unit derives a transfer voltage value that achieves good transfer to the medium for each medium width for media with different medium widths, and derives a corrected transfer voltage according to the medium width of the medium using the transfer voltage value for each medium width.

[0007] The second disclosed image forming apparatus includes (1) an image carrier that carries a developer image formed by a developer; (2) a transfer voltage application unit that applies a transfer voltage to transfer the developer image to a medium; (3) a transfer unit that receives a transfer voltage from the transfer voltage application unit and transfers the developer image on the image carrier to the medium; and (4) a transfer control unit that controls the transfer voltage of the transfer voltage application unit, and is characterized in that the transfer control unit determines the transfer voltage for a medium of a third width different from both the first width and the second width based on a first transfer voltage corresponding to a medium of a first width and a second transfer voltage corresponding to a medium of a second width different from the first width.

[0008] The third image forming apparatus of the present disclosure comprises (1) an image carrier that carries a developer image formed by a developer; (2) a transfer voltage application unit that applies a transfer voltage to transfer the developer image to a medium; (3) a transfer unit that receives the transfer voltage from the transfer voltage application unit and transfers the developer image on the image carrier to the medium; and (4) a transfer control unit that controls the transfer voltage of the transfer voltage application unit, wherein the transfer control unit forms a first pattern on a medium of a first width by varying the transfer voltage, forms a second pattern on a medium of a second width different from the first width by varying the transfer voltage, and determines the transfer voltage for a medium of a third width different from both the first width and the second width based on the transfer voltage selected from the first pattern and the transfer voltage selected from the second pattern. [Effects of the Invention]

[0009] According to the present disclosure, even for unknown media for which transfer conditions are not defined, good transfer can be achieved by correcting the transfer voltage. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an overall configuration of an image forming apparatus according to an embodiment; [Figure 2] FIG. 2 is a diagram illustrating a configuration of a control system of the image forming apparatus according to the embodiment. [Figure 3]6 is a flowchart showing a method for determining the magnitude of a transfer voltage in the image forming apparatus according to the embodiment. [Figure 4] 4 is a table for deriving the value of the first voltage Vtr1 according to the embodiment. [Figure 5] FIG. 4 is an explanatory diagram illustrating a resistance variation measurement current according to the embodiment. [Figure 6] 10 is a table for determining table values ​​A and B for deriving a second voltage Vtr2 according to the embodiment. [Figure 7] FIG. 10 is an explanatory diagram illustrating a third voltage Vtr3 according to the embodiment. [Figure 8] 10 is a table for determining a table value C for deriving a third voltage Vtr3 according to the embodiment. [Figure 9] 10 is a flowchart illustrating a processing procedure in a print defect correction mode according to a user operation according to an embodiment. [Figure 10] FIG. 10 is a diagram showing a display screen for inputting medium information in the embodiment. [Figure 11] FIG. 2 is a diagram illustrating a configuration of a print defect correction pattern according to an embodiment. [Figure 12] FIG. 2 is an explanatory diagram illustrating the configuration of a chart according to the embodiment. [Figure 13] FIG. 10 is a diagram showing a display screen in which the presence or absence of a printing defect is selected by comparing it with a chart in the embodiment. [Figure 14] FIG. 10 is a diagram showing a display screen for selecting a correction amount by comparing it with a chart in the embodiment. [Figure 15] 10 is a display screen for selecting whether to continue print correction for other sizes of the same type of media in the embodiment. [Figure 16] 10 is a flowchart illustrating a process in a print defect correction mode in the image forming apparatus according to the embodiment. [Figure 17] 10A and 10B are diagrams illustrating the state of the transfer voltage before correction of the medium in the embodiment. [Figure 18] 10A and 10B are diagrams illustrating the state of transfer voltage after correction of a medium corrected in a print defect correction mode according to an embodiment. [Figure 19] FIG. 10 is a diagram showing the state of the transfer voltage when the transfer voltage is uniformly corrected. DETAILED DESCRIPTION OF THE INVENTION

[0011] (A) Main embodiment Hereinafter, an embodiment of an image forming apparatus according to the present disclosure will be described in detail with reference to the drawings.

[0012] Here, the image forming apparatus according to the present disclosure will be exemplified as an electrophotographic printer.

[0013] (A-1) Configuration of the embodiment FIG. 1 is a diagram showing the overall configuration of an image forming apparatus according to an embodiment.

[0014] In FIG. 1, the image forming apparatus 1 according to the embodiment has a panel 24, a media storage cassette 18, a hopping roller 14, a registration roller 15, a pinch roller 16, a guide 19, a sensor 20, a sensor 21, a manual feed tray 29, a pickup roller 17, a conveying belt 11, a drive roller 12, a driven roller 13, a printing mechanism (also called an "image drum unit") 101-104, transfer rollers 1001-1004, a fixing mechanism 22, an ejection guide 23, and an ejection tray 28.

[0015] 1, panel 24 is a liquid crystal panel (operation panel) mounted on the outer wall of image forming apparatus 1, and displays various printing conditions, error messages, etc. Panel 24 is equipped with physical buttons and a touch panel, allowing the user to input information, such as selecting printing conditions such as media type, media weight, and media width before printing to set optimal transfer conditions, or executing the print defect correction mode described below.

[0016] The conveyor belt 11 is a seamless, endless, semi-conductive plastic film with high resistance. The drive roller 12 is connected to a belt motor (not shown), which rotates the drive roller 12 in the direction of arrow e. The driven roller 13 pulls the conveyor belt 11 in the direction of arrow f.

[0017] The upper surface of the conveyor belt 11 is stretched between the photosensitive drums 301 to 304 of the printing mechanisms 101 to 104 and the transfer rollers 1001 to 1004. The conveyor belt 11 electrostatically attracts and conveys paper fed from a paper feed mechanism (described later).

[0018] 1, a paper feed mechanism for feeding paper onto the conveyor belt 11 is located on the lower right side of the image forming apparatus 1. This paper feed mechanism has a hopping roller 14, a registration roller 15, a pinch roller 16, a medium storage cassette 18, a guide 19, and sensors 20 and 21. Paper stored in the medium storage cassette 18 is picked up one by one by the hopping roller 14, guided by the guide 19, and reaches the registration roller 15.

[0019] Here, if paper is fed skewed (the state in which paper is fed skewed is called skew), the skew of the paper is corrected by registration roller 15 and opposing pinch roller 16. To detect the position of the paper and jams, sensors 20 and 21 are placed before and after registration roller 15. Furthermore, paper can be fed from manual feed tray 29 in addition to media storage cassette 18, and paper set in manual feed tray 29 is fed by pickup roller 17.

[0020] Next, we will explain the printing mechanism in the image forming apparatus 1. Independent printing mechanisms (image drum units) 101 to 104 are arranged along a conveyance path from the paper feed side to the discharge side of the recording medium.

[0021] Although the printing mechanisms 101 to 104 use different toner (developer) colors, they basically have the same configuration. Below, the configuration of printing mechanism 101 will be described as a representative of the printing mechanisms 101 to 104, but the other printing mechanisms 102 to 104 also have the same configuration. Note that the last digit of each of the reference numerals for the components of printing mechanisms 101 to 104 is the same for all printing mechanisms 101 to 104.

[0022] Printing mechanism 101 is an electrophotographic LED printing mechanism for recording toner images.

[0023] For example, the printing mechanism 101 includes a charging roller 201, a photosensitive drum 301 as an image carrier, a developing roller 401 constituting a developing unit for forming a toner image, a developing blade 501, a supply roller 601, a de-electrifying light irradiation unit 701 for de-electrifying the surface of the photosensitive drum 301, and a toner cartridge 801.

[0024] The surface of the photosensitive drum 301 is uniformly charged by the charging roller 201, and carries a developer image formed by toner.

[0025] For example, black toner is accommodated in the toner cartridge 801. Toner cartridges 802 to 804 of the printing mechanisms 102 to 104 other than the printing mechanism 101 also accommodate toner of a predetermined color.

[0026] The supply roller 601 supplies toner from the toner cartridge 801 and moves it to the developing roller 401. As a result, the toner supplied from the toner cartridge 801 is transported to the developing roller 401 via the supply roller 601. After that, the toner reaches the developing blade 501 and is formed into a thin layer on the circumference of the developing roller 401.

[0027] The LED head 901 disposed above the photosensitive drum 301 of the printing mechanism 101 comprises an LED array, a drive IC (not shown) that drives the LED array, a circuit board (not shown) that is equipped with a group of registers that hold data, and a SELFOC (registered trademark) lens array that focuses the light from the LED array, and causes the LED array to emit light in response to image data signals input from the interface unit. The surface of the photosensitive drum 301 is exposed to light emitted by the LED head 901, forming an electrostatic latent image on the surface of the photosensitive drum 301. Toner on the outer circumferential surface of the developing roller 401 adheres to this electrostatic latent image by electrostatic force, forming an image.

[0028] A transfer voltage is applied to the transfer roller 1001 from a transfer voltage generating unit 45 (described later), and the toner image formed on the surface of the photosensitive drum 301 is transferred to the conveyed paper. After transfer, the paper is separated from the printing mechanism 101 and conveyed to the fixing mechanism 22.

[0029] The fixing mechanism 22 heats and melts the toner on the paper to fix the toner image on the paper. The printed paper passes through the fixing mechanism 22 and is ejected along an ejection guide 23.

[0030] FIG. 2 is a configuration diagram showing the configuration of a control system of the image forming apparatus 1 according to the embodiment.

[0031] In FIG. 2, the image forming apparatus 1 includes a thermistor 31, a host interface unit 32, a command / image processing unit 33, an LED head interface unit 34, a mechanism control unit 35, a high voltage control unit 41, a charging voltage generating unit 42, a developing voltage generating unit 43, a supply voltage generating unit 44, a transfer voltage generating unit 45, a memory means 3503, photosensitive drums 301-304, LED heads 901-904, printing mechanisms 101-104, and transfer rollers 1001-1004.

[0032] The host interface unit (hereinafter referred to as the host I / F unit) 32 is an interface that communicates with a host computer (not shown). The host interface unit 32 is an interface on the physical layer, and is made up of a connector and a communication chip.

[0033] The command / image processing unit 33 processes commands and print data (image formation data) from the host computer. For example, the command / image processing unit 33 interprets commands and converts image data included in the print data into a bitmap to generate processed image data.

[0034] Furthermore, the command / image processing unit 33 controls the entire processing in the image forming apparatus 1.

[0035] The LED head interface unit (hereinafter referred to as LED head I / F unit) 34 is an interface that processes the processed image data from the command / image processing unit 33 in accordance with the interface of the LED heads 901 to 904. The LED head interface unit 34 is composed of a semi-custom LSI, RAM, etc. (not shown).

[0036] The high voltage control unit 41 controls the charging voltage generation unit 42, the developing voltage generation unit 43, the supply voltage generation unit 44, and the transfer voltage generation unit 45, thereby controlling the charging voltage, developing voltage, supply voltage, and transfer voltage in the printing mechanism 101.

[0037] The charging voltage generating unit 42 applies or stops the application of charging voltage to the charging rollers 201-204.

[0038] The developing voltage generating unit 43 applies or stops the application of the developing voltage to the developing rollers 401-404.

[0039] The supply voltage generating unit 44 applies or stops the application of the supply voltage to the supply rollers 601 to 604.

[0040] Transfer voltage generating unit 45 is a transfer voltage applying unit that applies or stops the application of a transfer voltage for transferring a toner image from photosensitive drums 301 to 304 to a medium. The magnitude of the transfer voltage applied by transfer voltage generating unit 45 is determined by a calculation unit 3502 (described later) depending on the magnitude of the resistance of transfer rollers 1001 to 1004.

[0041] The charging voltage generator 42, the developing voltage generator 43, the supply voltage generator 44, and the transfer voltage generator 45 can be configured, for example, by a power supply circuit (not shown).

[0042] The magnitude of the resistance of the transfer rollers 1001-1004 is determined from the magnitude of the current flowing through the transfer rollers 1001-1004 and the magnitude of the voltage applied from the transfer voltage generating unit 45. Since the resistance is detected from the magnitude of the current in this way, this method of detecting the resistance is called current detection.

[0043] Specifically, fixed resistors are provided between the transfer voltage generating unit 45 and the transfer rollers 1001 to 1004, and the current flowing through the fixed resistors is calculated by the mechanism control unit 35. Here, the mechanism control unit 35 calculates the current from the voltage applied to the fixed resistors in accordance with Ohm's law.

[0044] The mechanism control unit 35 controls the printing mechanisms 101 to 104, the paper feed mechanism, the fixing mechanism 22, the various sensors 21 and 22, and the discharge guide 23, and controls printing (image formation) in the image forming apparatus 1.

[0045] For example, the mechanism control unit 35 controls the print mechanism 101. The mechanism control unit 35 also controls the various sensors 21 and 22, the thermistor 31, and the like.

[0046] Furthermore, the mechanism control unit 35 controls a hopping motor that drives the hopping roller 14, a conveying motor that drives the conveying roller group, a heater motor that drives the heat roller of the fixing mechanism 22, and drum motors that drive the photosensitive drums 301-304.

[0047] The mechanism control unit 35 includes a current detection execution determination unit 3501 and a calculation unit 3502 that functions as a transfer control unit.

[0048] The current detection execution determination unit 3501 identifies the medium type, medium width, medium thickness, and medium weight from the medium setting information contained in the print data sent from the host computer, and stores them in the memory means 3503.

[0049] The magnitude of the electrical resistance value of the transfer rollers 1001 to 1004 is affected by temperature and humidity. Therefore, based on the temperature and humidity information acquired by the thermistor 31, the transfer voltage generating unit 45 outputs a resistance detection voltage, and the calculation unit 3502 calculates the magnitude of the electrical resistance value from the value (magnitude) of the current flowing through the transfer rollers 1001 to 1004 via the output resistor.

[0050] The calculation unit 3502 derives a transfer voltage value that achieves good transfer to the medium for each medium width for media with different medium widths, and uses the transfer voltage value for each medium width to derive a corrected transfer voltage that corresponds to the medium width of the medium.

[0051] For example, the calculation unit 3502 derives the magnitude of the transfer voltage to be applied during transfer based on the medium type, medium width, medium thickness, medium weight, job duty information, and temperature and humidity information set by the user before the printing operation (image forming operation). The method of calculating the transfer voltage will be described later.

[0052] The storage means 3503 stores data and programs necessary for processing in the mechanism control unit 35. The storage means 3503 can be configured, for example, by a non-volatile memory.

[0053] (A-2) Operation of the embodiment Hereinafter, the operation of the transfer control process for controlling the transfer voltage in the image forming apparatus 1 according to the embodiment will be described with reference to the drawings.

[0054] (A-2-1) Method for deriving transfer voltage FIG. 3 is a flowchart showing a method for determining the magnitude of the transfer voltage in the image forming apparatus 1 according to the embodiment.

[0055] First, the magnitude of the transfer voltage Vtr applied to each of the transfer rollers 1001 to 1004 is determined by the sum of the values ​​of three voltages Vtri (i = any one of 1 to 3). That is, the calculation unit 3502 derives the transfer voltage Vtr according to equation (1).

[0056] The three voltages that determine the transfer voltage Vtr are also referred to as a first voltage Vtr1, a second voltage Vtr2, and a third voltage Vtr3.

number

[0057] [S101] The calculation unit 3502 acquires the medium information {medium type X, medium weight R} stored in the storage unit 3503, and also acquires the temperature and humidity pair (Ti, Hj) observed by the thermistor 31. Then, the calculation unit 3502 determines the first voltage Vtr1 based on the medium information {medium type X, medium weight R} and the temperature and humidity (Ti, Hj) (S101).

number

[0058] Here, the first voltage Vtr1 can be derived by the calculation unit 3502 by referring to the table shown in FIG.

[0059] 4 is a table for deriving the value of the first voltage Vtr1 according to the embodiment. For example, in the table illustrated in FIG. 4, voltage values ​​for each piece of medium information {medium type X, medium weight R} are set in advance. Furthermore, the voltage values ​​for each piece of medium information {medium type X, medium weight R} are set in advance for each temperature and humidity in accordance with the differences between the temperature and humidity.

[0060] Therefore, the calculation unit 3502 can refer to the table in Figure 4, read the voltage value for each corresponding piece of media information {media type X, media weight R} based on the media information {media type X, media weight R} and the temperature and humidity values ​​observed by the thermistor 31, and use this voltage value as the first voltage Vtr1.

[0061] The first voltage Vtr1 derived by the calculation unit 3502 is stored in the storage means 3503.

[0062] [S102] The calculation unit 3502 derives the second voltage Vtr2 based on the resistance variation measurement current Is and the table values ​​A and B determined by the temperature and humidity pair (Ti, Hj) (S102).

number

[0063] Here, the second voltage Vtr2 is a voltage value that takes into account the resistance value that varies depending on the environment in which the image forming apparatus 1 is placed. Also, the resistance variation measurement current Is is the amount of current that flows through the transfer roller 1001 when the resistance variation measurement voltage Vs is applied.

[0064] 5 is an explanatory diagram illustrating the resistance variation measurement current Is according to the embodiment, and shows the state of the transfer nip portion 300 between the photosensitive drum 301 and the transfer roller 1001 via the conveyor belt 11.

[0065] In the transfer nip portion 300, the photosensitive drum 301 includes a photosensitive drum 301 as a surface layer of a photosensitive body, and a photosensitive drum shaft 311 as a conductive shaft. The transfer roller 100 includes a transfer roller 1001 as a surface layer of an elastic body, and a transfer roller shaft 1011 as a conductive shaft. In the transfer nip portion 300, the photosensitive drum 301 as a surface layer and the transfer roller 1001 as a surface layer are in contact with each other.

[0066] 5, when the applied voltage Vtr=Vs is applied, a resistance variation measurement current Is flows between the transfer roller shaft and the photosensitive drum shaft. At that time, a current detection execution determination unit 3501 detects the magnitude of the resistance variation measurement current Is.

[0067] Current detection by the current detection execution determination unit 3501 is performed as appropriate, and the magnitude of the resistance variation measurement current Is measured most recently is stored in the storage means 3503.

[0068] FIG. 6 is a table for determining table values ​​A and B for deriving the second voltage Vtr2 according to the embodiment.

[0069] The calculation unit 3502 refers to FIG. 6 based on the temperature and humidity pair (Ti, Hj) observed by the thermistor 31, and acquires the corresponding table values ​​A and B. Furthermore, the calculation unit 3502 derives the second voltage Vtr2 using the table values ​​A and B and the resistance variation measurement current Is in equation (3). The calculation unit 3502 stores the derived second voltage Vtr2 in the storage means 3503.

[0070] [S103] The calculation unit 3502 derives the third voltage Vtr3 based on the temperature and humidity pair (Ti, Hj) from the thermistor 31, the medium type X, and the medium width W (S103).

number

[0071] FIG. 7 is an explanatory diagram illustrating the third voltage Vtr3 according to the embodiment.

[0072] The third voltage Vtr3 is a voltage value that corrects the amount of change in apparent resistance due to the load on the medium when the medium is nipped between the photosensitive drum 301 and the conveying belt 11 during transfer, and the amount of charge carried by discharge that occurs in the gap between the photosensitive drum 301 and the transfer roller 1001, which are separated by the thickness of the medium in the outer region of the transfer nip length, until they come into contact again.

[0073] Note that the longitudinal direction of the transfer nip portion is the longitudinal direction of the portion where the photosensitive drum 301 and the conveyance belt 11 are in contact, and is a direction orthogonal to the rotation direction of the conveyance belt 11 (the media conveyance direction).

[0074] As illustrated in FIG. 7, during transfer, since a media exists between the photosensitive drum 301 and the conveyance belt 11, a gap is generated between the photosensitive drum 301 and the transfer roller 120 due to the thickness of the media. Due to the generation of this gap, the transfer voltage changes.

[0075] Note that the "in-media region" refers to the region where the media exists between the photosensitive drum 301 and the conveyance belt 11 during transfer. The "gap" refers to the region where the photosensitive drum 301 and the conveyance belt 11 are not in contact, which is generated due to the thickness of the media during transfer.

[0076] The "out-of-media region" refers to the region where the photosensitive drum 301 and the conveyance belt 11 are in contact during transfer.

[0077] FIG. 8 is a table for determining the table value C related to the derivation of the third voltage Vtr3 according to the embodiment.

[0078] Based on the combination of temperature and humidity (T1, Hj) and the media information {media type X, media weight R}, the calculation unit 3502 determines the corresponding table value C by referring to FIG. 8.

[0079] The table value C is a value that changes according to the moisture content contained in the media. For example, in the case of low temperature and low humidity, since the moisture content contained in the media is small, when reducing the transfer voltage, the table value C is increased. Conversely, in the case of high temperature and high humidity, since the moisture content contained in the media is large, when increasing the transfer voltage, the table value C is decreased.

[0080] Then, the calculation unit 3502 uses the value of the difference (L - W) between the longitudinal direction L of the transfer portion and the media width W (0 < W < L) and the table value C in equation (4) to derive the third voltage Vtr3. The calculation unit 3502 stores the derived third voltage Vtr3 in the storage means 3503.

[0081] [S104] The calculation unit 3502 derives the transfer voltage Vtr from the sum of the first voltage Vtr1, the second voltage Vtr2, and the third voltage Vtr3 stored in the storage unit 3503 (S104).

[0082] In this way, calculation unit 3502 derives transfer voltage Vtr, high voltage control unit 41 causes transfer voltage generation unit 45 to generate transfer voltage Vtr, and transfer voltage generation unit 45 applies transfer voltage Vtr to transfer rollers 1001-1004.

[0083] (A-2-2) Print Defect Correction Mode (User Procedure) If the transfer voltage Vtr is excessive or insufficient during transfer, dust or blurring may occur, resulting in poor printing.

[0084] Generally, there are many brands and media sizes on the market, so there is a need for a means to adjust the transfer voltage to prevent print defects such as dust and smearing, thereby improving usability.

[0085] Hereinafter, the means for manually adjusting the transfer voltage to make it excessive or insufficient will be referred to as the "print defect correction mode," and the execution procedure of the print defect correction mode by user operation will be described with reference to FIG.

[0086] FIG. 9 is a flowchart showing a processing procedure in the print defect correction mode by user operation according to the embodiment.

[0087] First, when a print defect occurs, the flow starts with a process for executing the print defect correction mode.

[0088] An operation screen for the print defect correction mode is displayed on the panel 24, and the user operates the panel 24 in accordance with the display screen.

[0089] [S201] When a user wishes to resolve a printing defect, the user inputs the medium type, medium weight, and medium size of the medium on which the printing defect occurred (S201).

[0090] For example, the user inputs the medium width Wa as the first width and the medium length La in the transport direction from the panel 24. Furthermore, the medium weight can be derived by inputting the medium type, medium width, medium length in the transport direction, and medium thickness, for example, from the specific gravity (weight per unit volume) of each medium type that is stored in advance.

[0091] [S202] Next, the display screen shown in FIG. 10 is displayed on the panel 24, and the user follows the instructions on the display screen to set N sheets of media each having a width Wa and a length La on the manual feed tray 29 (S202).

[0092] Here, an example is shown in which the medium is set on the manual feed tray 29, but the medium may also be set on the medium storage cassette 18. The number of prints N is derived from equation (5) described below, which will be explained later.

[0093] [S203] When it is confirmed that the medium has been set on the manual feed tray 29, the image forming apparatus 1 executes a printing operation, prints a print defect correction pattern on the medium, and ejects the printed medium (S203).

[0094] FIG. 11 is a diagram showing the configuration of the print defect correction pattern according to the embodiment.

[0095] As shown in FIG. 11, the print defect correction pattern is printed by switching the transfer voltage and printing correction patterns at each transfer voltage value.

[0096] Of the four patterns, the topmost pattern is when the transfer voltage value is Vtr, the second pattern is when it is (Vtr-200), the third pattern is when it is (Vtr-400), and the fourth pattern is when it is (Vtr-600).

[0097] 11, the first pattern has a margin of m [mm] for the medium header, and each of the four patterns is formed with a dL [mm] interval between them. The distance m is the time it takes to set the transfer voltage to Vtr, and the distance dL corresponds to the time it takes to switch the transfer voltage, i.e., the time it takes for the state of the photosensitive drum 301 to stabilize. Each pattern will be described in detail later.

[0098] [S204] The user compares the print result of the print defect correction pattern with the chart (also called the "print defect correction operation chart") to determine whether there is a print defect (S204).

[0099] Here, the "chart (printing defect correction operation chart)" visually shows the degree of printing defect at multiple levels. The user judges the degree of printing defect by comparing the multiple levels of printing defect shown on the chart with the print result of the printing defect correction pattern. In other words, the "chart" is a list that allows the user to visually determine whether or not a printing defect has occurred.

[0100] Fig. 12 is an explanatory diagram illustrating the configuration of a chart according to an embodiment. Fig. 13 is a diagram illustrating a display screen for selecting whether or not there is a printing defect by comparing with the chart according to an embodiment. Fig. 14 is a diagram illustrating a display screen for selecting a correction amount by comparing with the chart according to an embodiment.

[0101] The chart in FIG. 12 is included with the image forming apparatus 1 at the time of purchase and is available for download from the website so that the print results of the image forming apparatus 1 can be properly evaluated.

[0102] As shown in Figure 12, the chart shows examples of print results that appear to require either "small correction amount," "medium correction amount," or "large correction amount." The print result for "small correction amount" shows print results that appear to require no correction or a small amount of correction, the print result for "large correction amount" shows print results that appear to require a large amount of correction, and the print result for "medium correction amount" shows print results that are somewhere between "small correction amount" and "large correction amount."

[0103] The user compares the print result with the chart to determine whether the print defect is a dust spot or a blur, and inputs the result of the determination into the panel 24.

[0104] For example, if the user determines that there are dust particles, he or she selects "Printing defect = dust particles" on the display screen of Fig. 13. If either dust particles or faint particles are selected, the process proceeds to S205.

[0105] Also, for example, if no printing defects are found, the user selects "Printing defects = None" on the display screen of FIG. 13, and the process proceeds to S206.

[0106] In this example, three print results (three levels) are shown on the chart, but two print results (two levels) or four or more print results (four or more levels) may be shown. Also, the chart shows two print defects, dust and smudges, but three or more may be shown.

[0107] [S205] If dust or faint print defects are selected, the user selects the amount of correction (S205).

[0108] The user compares the print result with the chart, determines which of the three print results (three levels) shown on the chart the print result is closest to, and selects the amount of correction.

[0109] Print defects such as dust and blurring caused by voltage overload or underload worsen as the voltage deviates from the appropriate level. The chart shows images of print defects at three levels of deterioration, and the user can rate the level that most closely matches the level of print defect. For example, if the print result is extremely poor, the user may determine that it is equivalent to a "large correction amount" and select "large correction amount" on the display screen in Figure 14.

[0110] [S206] When handling multiple sizes of the same type of media, the user corrects the size of the other media (S206).

[0111] In other words, correction for printing defects can be performed even for media of the same type but different media sizes.

[0112] FIG. 15 shows a display screen for selecting whether or not to continue print correction for other sizes of the same type of media in this embodiment.

[0113] If the user wishes to perform print defect correction on other sizes of the same media, the user selects "Continue print correction mode" in Fig. 15 and the process proceeds to S207. On the other hand, if the user does not wish to do so, the user selects "End print correction mode" in Fig. 15 and the process ends.

[0114] For example, the range of "minimum width to maximum width" of the medium width used by the user for printing is expressed as (minimum, maximum). It is expressed as (Wa, Wb) or (Wb, Wa). The minimum width Wa is also called the "first medium width" or "first width," and the maximum width Wb is also called the "second medium width" or "second width."

[0115] In this example, the user performed print defect correction for a medium with a medium width Wa in steps S201 to S205. Therefore, if the user also wants to perform print defect correction for a medium with a medium width Wb, the user can select "Continue print correction mode" in Figure 15 and continue print correction for the medium width Wb. In particular, it is desirable to perform print defect correction for both the minimum and maximum medium widths.

[0116] The processes of S207 to S210 correspond to the processes of S202 to S205.

[0117] [S207] If the user desires to perform print defect correction on a medium having a medium width Wb as the second width, the user sets a medium having a medium width Wb (Wb≠Wa, Lb) on the tray (S207).

[0118] [S208] When it is confirmed that the medium has been set on the manual feed tray 29, the image forming apparatus 1 executes a printing operation, prints the print defect correction pattern on the medium, and ejects the printed medium (S208).

[0119] [S209] The user compares the print result of the print defect correction pattern with the chart to determine whether there is a print defect (S209).

[0120] [S210] If dust or faint print defects are selected, the user selects the amount of correction (S210).

[0121] As described above, according to the procedure shown in FIG. 9, it is possible to supply an appropriate transfer voltage for at least one medium width.

[0122] Furthermore, for two or more media of the same type with different media widths such as Wa < Wb, etc., printing defect correction can be performed for each of the two media widths. As a result, an appropriate transfer voltage can be supplied for media of the same type with any media width Wx (Wa ≤ Wx ≤ Wb) within the range of media widths Wa and Wb.

[0123] In other words, the arithmetic unit 3502 forms a first pattern in which the transfer voltage is variable for media with a media width (first width) Wa, and forms a second pattern in which the transfer voltage is variable for media with a media width Wb (second width). Then, based on the transfer voltage selected by the user from the first pattern and the transfer voltage selected by the user from the second pattern, the transfer voltage for media with a media width (third width) Wx is determined.

[0124] (A-2-3) Printing Defect Correction Mode (Program Procedure) In the above description, the explanation was centered around user operations. Subsequently, the process of printing defect correction in the image forming apparatus 1 will be described.

[0125] FIG. 16 is a flowchart showing the process of the printing defect correction mode in the image forming apparatus 1 according to the embodiment.

[0126] [S301] The arithmetic unit 3502 of the mechanism control unit 35 stores the media type, media weight, and media size (Wa, La) selected by the user in S201 in the storage means �503 (S301).

[0127] [S302] The arithmetic unit 3502 derives the number of sheets N required for printing according to the media width and displays it on the panel 24 (S302).

[0128] Here, a method for deriving the number of prints N will be explained. For example, let us consider the case where the print defect correction pattern of FIG. 11 is printed. That is, the margin is m [mm], the length of the pattern in the paper feed direction is Lptn [mm], and the spacing between patterns is dL [mm]. Furthermore, let the number of voltage levels be K. The number of levels K is the number corresponding to the number of correction amount options that the user can select. The value of the number of voltage levels K and the value of the length Lptn of the pattern in the paper feed direction are experimentally determined values.

[0129] The calculation unit 3502 then substitutes the values ​​of m, Lptn, dL, and K into equation (5) to derive the number of prints N. Note that equation (5) is a function that rounds up decimal points.

number

[0130] [S303] The calculation unit 3502 stores information indicating the presence or absence of printing defects selected by the user in S204 in the storage unit 3503 (S303).

[0131] In S204, the user compares the chart with the print result of the print defect correction pattern and selects a print defect on the display screen of Fig. 13, for example. The calculation unit 3502 stores information regarding the presence or absence of a print defect selected by the user on the display screen of Fig. 13 in the storage unit 3503.

[0132] At this time, for example, if "printing defect = dust" is selected, the calculation unit 3502 stores the value "-1," if "printing defect = blurred" is selected, the value "+1," and if "printing defect = none" is selected, the value "+0" as information regarding the presence or absence of printing defect.

[0133] [S304] The calculation unit 3502 stores the correction amount δ1 determined by the user in accordance with the chart in S205 in the storage means 3503 (S304).

[0134] For example, if "Correction amount = large" is selected, "600" is stored; if "Correction amount = medium" is selected, "400" is stored; and if "Correction amount = small" is selected, "200" is stored.

[0135] [S305] The calculation unit 3502 derives the transfer voltage based on the value as information relating to the printing defect stored in the storage unit 3503, and prints patterns for the number of levels (K+1) while changing the transfer voltage (S305).

[0136] For example, if the value of the information about the printing defect is "-1" and K=3, the number of patterns printed in the printing defect correction pattern is set to four (see Figure 11). In addition, the transfer voltages of the four patterns are set to "Vtr", "Vtr-200", "Vtr-400", and "Vtr-600" from the top of the medium.

[0137] [S306] The calculation unit 3502 updates the table value C from the values ​​stored in the storage unit 3503 in S301 to S305 to a table value C'=(C|W=Wa) conditioned by the medium width Wa (S306).

[0138] In other words, the calculation unit 3502 updates the table value C to the table value C' based on the media type, media weight, and media size selected by the user in S201 and the values ​​stored in the memory means 3503 by the calculation unit 3502 based on the information regarding printing defects selected by the user in S204 and S205.

[0139] A method for updating the table value C' will be described below. For example, the calculation unit 3502 uses the corrected transfer voltage Vtr' to obtain the table value C' conditioned by the medium width Wa.

[0140] Here, for example, the transfer voltage Vtr' is derived by the calculation unit 3502 using equation (6).

number

[0141] However, for each of the values ​​{-1,0,1} and {200,400,600} included in the curly brackets, one of the values ​​is uniquely selected by the user.

[0142] Applying equation (3) to Vtr3 in equation (6) and rearranging for "C" gives the table value C' conditioned by the medium width Wa.

number

[0143] The calculation unit 3502 stores the value obtained by equation (7) as a table value C'=(C|W=Wa) in the storage means 3503. However, the part after the pipe represents the realized value of the parameter W.

[0144] [S307] If the user desires to correct print defects for media of the same type but different sizes, the calculation unit 3502 stores media widths other than the medium width Wa in the storage unit 3503 (S307).

[0145] For example, if "Continue print correction mode" is selected on the display screen of Fig. 15 in S206, the calculation unit 3502 stores a medium width other than the medium width Wa (for example, the medium width Wb) in the storage unit 3503. In this case, the calculation unit 3502 performs the processes of S302 to S306 for the medium width Wb.

[0146] On the other hand, if "End print correction mode" is selected on the display screen of FIG. 15 in S206, the process proceeds to S313, and the calculation unit 3502 ends the print defect correction mode.

[0147] [S308] The calculation unit 3502 calculates the number of sheets N' required for printing based on the medium width Wb, and displays it on the panel 24 (S308).

[0148] The number of prints N' can be derived using the same method as in S302. Since the same medium is used, the medium type and medium weight can be determined using information stored in the storage unit 3503.

[0149] [S309] The calculation unit 3502 stores information indicating the presence or absence of printing defects selected by the user in S209 in the storage unit 3503 (S309).

[0150] As in S303, for example, if "printing defect = dust" is selected, the calculation unit 3502 stores the value "-1," if "printing defect = blurred" is selected, the value "+1," and if "printing defect = none" is selected, the value "+0" as information regarding the presence or absence of printing defects.

[0151] [S310] The calculation unit 3502 stores the correction amount δ2 determined by the user in accordance with the chart in S205 in the storage means 3503 (S310).

[0152] For example, if "Correction amount = large" is selected, "600" is stored; if "Correction amount = medium" is selected, "400" is stored; and if "Correction amount = small" is selected, "200" is stored.

[0153] [S311] The calculation unit 3502 derives the transfer voltage based on the value as information relating to the printing defect stored in the storage unit 3503, and prints patterns for the number of levels (K+1) while changing the transfer voltage (S311).

[0154] For example, if the value of the information about the printing defect is "-1" and K=3, the number of patterns printed in the printing defect correction pattern is set to four (see Figure 11). In addition, the transfer voltages of the four patterns are set to "Vtr", "Vtr-200", "Vtr-400", and "Vtr-600" from the top of the medium.

[0155] [S312] The calculation unit 3502 updates the table value C from the values ​​stored in the storage unit 3503 in steps S308 to S312 to a table value C'=(C|W=Wb) conditioned by the medium width Wb (S312).

[0156] [S313] The calculation unit 3502 determines whether or not two or more conditioned table values ​​C' exist in the storage means 3503 (S313).

[0157] If two or more conditioned table values ​​C' exist (S313 / Y), the process proceeds to S315. On the other hand, if two or more conditioned table values ​​C' do not exist (S313 / N), the process proceeds to S314.

[0158] [S314] If two or more conditioned table values ​​C' do not exist, the calculation unit 3502 updates the table value C to the table value C' using equation (8) (S314). At this time, the calculation unit 3502 derives (C|W=Wa) using equation (7). Thereafter, the print defect correction mode is terminated.

number

[0159] [S315] If there are two or more conditioned table values ​​C', the calculation unit 3502 updates the table value C to the table value C' using equation (9) (S315).

[0160] For the table value C, the calculation unit 3502 selects from the two or more existing table values ​​C' those that are the minimum and maximum values ​​of the medium width (Wa, Wb), and then updates them using the following equation, which solves the simultaneous equations so that the medium width Wa and the medium width Wb become a common table value C'.

number

[0161] By updating the table value C using equation (9), not only is it possible to avoid print defects at a specific media width, but it is also possible to achieve voltage control that prevents print defects from occurring in the section (Wa, Wb).

[0162] When calculating Vtr3 using equation (9), if the table value C before the update is negative, the table value C' is calculated as "-C'", and if it is positive, it is calculated as "C'" as is.

[0163] (A-2-4) Example of adjusting the transfer voltage value Next, the transfer voltage Vtr corrected in the above-described print defect correction mode will be described.

[0164] Here, the case where the medium is waterproof paper is taken as an example, and the transfer voltage when using waterproof paper has not yet been evaluated. A case where the transfer voltage for waterproof paper is derived in the above-mentioned print error correction mode will be described.

[0165] Some types of waterproof paper have a plastic base material, and in this example, the transfer voltage for medium P is corrected assuming this type of medium.

[0166] The temperature and humidity environment is 10°C, humidity 20%, and the media width is (140 (=Wa), 210 (=Wb)), and the transfer voltages Vtr before correction are applied as "4.14 [kV]" and "3.84 [kV]", respectively.

[0167] Fig. 17 is a diagram showing the state of the transfer voltage of medium P before correction in the embodiment. Fig. 18 is a diagram showing the state of the transfer voltage of medium P after correction in the print defect correction mode according to the embodiment. Fig. 19 is a diagram showing the state of the transfer voltage when the transfer voltage is corrected uniformly. The vertical axis represents the transfer voltage, and the horizontal axis represents the medium width.

[0168] 17, the solid line represents the transfer voltage before correction. A blurred area can occur when the transfer voltage is low, and a dusty area can occur when the transfer voltage is high.

[0169] In this example, the transfer voltage before correction is in the blur-occurring region for both medium widths (140, 210). In other words, with the current table values, medium P is in a state where blur-occurring occurs for both medium widths.

[0170] Next, the above-described print defect correction mode is executed to correct the transfer voltage.

[0171] For example, if you select "medium correction amount" for a 140 mm width and "small correction amount" for a 210 mm width, the table value C is updated to table value C' based on the results. For example, the current table value C = 1.50 is updated to C' = 3.96.

[0172] As a result, the applied Vtr was 4.54 kV and 4.04 kV, respectively. Transfer was good for both media widths.

[0173] Even if the medium is the same type, differences in medium width change the transfer nip area between the photosensitive drum 301 and the conveyor belt 11. This changes the load on the medium during transfer, and the transfer voltage due to the effect of discharge also changes.

[0174] Therefore, in this embodiment, the transfer voltage is corrected for media of the same type and two different media widths.

[0175] For example, as shown in FIG. 19, when the transfer voltage in FIG. 17 is uniformly translated across the medium width, the transfer voltage may end up being included in the dust generation area depending on the medium width.

[0176] As a result, the behavior of the voltage relative to the original media width is shifted up, and good transfer is not achieved for all media widths.

[0177] In contrast to this, when the transfer voltage is corrected in the print defect correction mode of this embodiment, it is possible to determine a transfer voltage that avoids print defects in the dust-generating area and the blur-generating area, as shown in FIG.

[0178] In other words, in Figure 18, the line passing through two points: the transfer voltage value (value of the first transfer voltage) when the medium width is Wa as the first width, and the transfer voltage value (value of the second transfer voltage) when the medium width is Wb as the second width, is the ``corrected transfer voltage'' corrected by the print defect correction mode.

[0179] Therefore, even if the medium width Wx is a third width other than the medium widths Wa and Wb measured in the print defect correction mode, a good transfer voltage value for the medium width Wx can be derived based on the first transfer voltage and the second transfer voltage, resulting in good printing.

[0180] When printing using unknown media for which the transfer conditions are not defined, it is difficult to adjust the transfer voltage to a suitable level. However, if there are multiple media widths for the unknown media, the print defect correction mode can be used to derive the transfer voltage value for each media width, allowing the "corrected transfer voltage" to be derived according to the media width.

[0181] As a result, even with the unknown medium described above, by using the corrective transfer voltage, it is possible to perform good transfer regardless of the medium width.

[0182] (A-3) Effects of the embodiment As described above, according to this embodiment, by updating the table value C taking into account the load on the medium during transfer and the impact of discharge outside the medium, the user can manually control the appropriate transfer voltage even for unevaluated media.

[0183] In particular, if the table value C is updated for at least two media widths, it can be expected that good transfer will be achieved for any media width that falls within the evaluated media widths without updating.

[0184] (B) Other embodiments Although various modified embodiments have been mentioned in the above-described embodiment, the present disclosure can also apply the following modified embodiments.

[0185] (B-1) In the above-described embodiment, the transfer voltage is corrected for the same type of medium with two medium widths. However, the medium width is not limited to two, and may be three or more.

[0186] (B-2) In the above embodiment, an example was explained in which the invention was applied to an electrophotographic printer, but it can also be applied to a printer with a scanner. [Explanation of symbols]

[0187] 1: image forming apparatus, 11: conveyor belt, 12: drive roller, 13: driven roller, 14: hopping roller, 15: registration roller, 16: pinch roller, 17: pickup roller, 18: media storage cassette, 19: guide, 20: sensor, 21: sensor, 22: fixing mechanism, 23: discharge guide, 24: panel, 28: paper discharge tray, 29: manual feed tray, 31: Thermistor, 32: Host interface unit, 33: Image processing unit, 34: LED head interface unit, 35: Mechanism control unit, 41: High voltage control unit, 42: Charging voltage generation unit, 43: Development voltage generation unit, 44: Supply voltage generation unit, 45: Transfer voltage generation unit, 100: Transfer roller, 101 to 104: Printing mechanism, 120: Transfer roller, 201 to 204: Charging roller, 300: Transfer nip unit, 301 to 304: photosensitive drum, 311: photosensitive drum shaft, 401 to 404: developing roller, 501: developing blade, 601 to 604: supply roller, 701: static elimination light irradiation unit, 801 to 804: toner cartridge, 901 to 904: LED head, 1001 to 1004: transfer roller, 1011: transfer roller shaft, 3501: current detection execution judgment unit, 3502: calculation unit, 3503: storage means.

Claims

1. an image carrier that carries a developer image formed by the developer; a transfer voltage applying section that applies a transfer voltage for transferring the developer image onto a medium; a transfer unit that receives the transfer voltage from the transfer voltage application unit and transfers the developer image on the image carrier to the medium; a transfer control unit that controls the transfer voltage of the transfer voltage application unit; Equipped with The image forming apparatus is characterized in that the transfer control unit derives a transfer voltage value that achieves good transfer to the medium for each medium width for media with different medium widths, and uses the transfer voltage value for each medium width to derive a corrected transfer voltage according to the medium width of the medium.

2. Equipped with an operation panel, the transfer control unit prints a plurality of transfer patterns transferred onto the medium by changing the transfer voltage value for each medium width; a good transfer pattern is selected from the plurality of transfer patterns for each medium width via the operation panel; The transfer control unit corrects the currently set transfer voltage value for each medium width to the transfer voltage value at which the selected transfer pattern was formed.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. By comparing the plurality of transfer patterns with a sample chart prepared in advance that indicates the degree of printing defects in multiple stages, the presence or absence of printing defects is selected through the operation panel; The correction amount for the currently set transfer voltage value is selected through the operation panel.

3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

4. The corrected transfer voltage corresponding to the medium width of the medium is derived based on the transfer voltage values ​​for the first medium width and the second medium width of the medium, which have different medium widths; When printing on a medium having a different medium width from the first medium width and the second medium width, The transfer control unit transfers the toner image at a transfer voltage value corresponding to the different medium width based on the corrected transfer voltage corresponding to the different medium width.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

5. an image carrier that carries a developer image formed by the developer; a transfer voltage applying section that applies a transfer voltage for transferring the developer image onto a medium; a transfer unit that receives the transfer voltage from the transfer voltage application unit and transfers the developer image on the image carrier to the medium; a transfer control unit that controls the transfer voltage of the transfer voltage application unit; Equipped with The transfer control unit determines a transfer voltage for a medium having a third width different from both the first width and the second width based on a first transfer voltage corresponding to a medium having a first width and a second transfer voltage corresponding to a medium having a second width different from the first width. An image forming apparatus characterized by:

6. an image carrier that carries a developer image formed by the developer; a transfer voltage applying section that applies a transfer voltage for transferring the developer image onto a medium; a transfer unit that receives the transfer voltage from the transfer voltage application unit and transfers the developer image on the image carrier to the medium; a transfer control unit that controls the transfer voltage of the transfer voltage application unit; Equipped with the transfer control unit forms a first pattern by varying the transfer voltage on a medium having a first width, and forms a second pattern by varying the transfer voltage on a medium having a second width different from the first width, A transfer voltage for a medium having a third width different from both the first width and the second width is determined based on the transfer voltage selected from the first pattern and the transfer voltage selected from the second pattern. An image forming apparatus characterized by:

Images