Image forming apparatus

Abstract

An image forming apparatus is disclosed. The image forming apparatus includes an image bearing member, a transfer belt, a secondary transfer member, a voltage source, a current detection section, and a controller. The controller is operable in a first mode in which, when a recording material is not present in a secondary transfer section, a current flowing through the secondary transfer member is detected by the current detection section with a first test voltage applied, and then information about a current-voltage characteristic of the secondary transfer member is acquired, and a second mode in which a predetermined test image is transferred from the transfer belt onto a recording material with a second test voltage applied, and then a test chart for adjusting a transfer voltage set during transfer is output. Based on the information, the controller changes an interval of the second test voltage applied in the operation in the second mode.

Description

Technical Field

[0001] The present invention relates to image forming apparatus such as copiers, printers, fax machines, or multifunctional machines having multiple functions of these machines. Background Technology

[0002] In an image forming apparatus, a toner image is transferred from a photosensitive drum directly or via an intermediate transfer belt onto a recording material. For this reason, a transfer member is provided to form a transfer section for transferring the toner image between the recording material and the photosensitive drum or intermediate transfer belt. Furthermore, the type of transfer voltage applied to the transfer section during image forming is conventionally known.

[0003] For example, Japanese Patent Application Publication No. 2013-37185 discloses a type (adjustment mode of secondary transfer voltage) that outputs multiple pattern images transferred at different transfer voltages, and based on the pattern images, an optimal transfer voltage is selected and reflected in the transfer voltage during image formation.

[0004] Here, in the operation of the secondary transfer voltage adjustment mode, multiple pattern images (predetermined images) are transferred onto the recording material with different transfer voltages that provide a predetermined difference between them. However, due to changes in the resistance of the transfer component used, changes in the environment, etc., the change in current value at each transfer voltage varies. For example, when the resistance of the transfer component increases, the change in current value becomes smaller relative to the change in transfer voltage.

[0005] In this situation, the change in current value for each pattern image is small, making it difficult to distinguish differences in transfer properties and thus difficult to identify the optimal transfer voltage. On the other hand, as the number of pattern images to be output increases, the amount of recording material with transferred pattern images also increases. Summary of the Invention

[0006] The main objective of this invention is to provide an image forming apparatus that can improve the selection accuracy of the optimal transfer voltage while suppressing an increase in the amount of recording material (sheet) with a predetermined image transferred in the output.

[0007] According to one aspect of the present invention, an image forming apparatus is provided, comprising: an image carrier member configured to carry a toner image; a transfer belt onto which the toner image is transferred from the image carrier member to the transfer belt in a primary transfer; a secondary transfer member configured to transfer the toner image from the transfer belt to a recording material in a secondary transfer section; a voltage source configured to apply a transfer voltage to the secondary transfer member; a current detection unit capable of detecting the current flowing through the secondary transfer member from the voltage source; and a controller capable of controlling the voltage source, wherein the controller is capable of performing an operation in a first mode, in which the current detection unit detects the current when no recording material is present in the secondary transfer section. The current flowing through the secondary transfer member is measured when a first test voltage is applied to the secondary transfer member, and information about the current-voltage characteristics of the secondary transfer member is then acquired. The controller is capable of performing operations in a second mode, in which, when recording material is present in the secondary transfer section, a predetermined test image is transferred from the transfer belt to the recording material when multiple different second test voltages are applied to the secondary transfer member, and a test chart for adjusting the transfer voltage set during the transfer is then output. Furthermore, based on the information acquired during operation in the first mode, the controller changes the interval of the second test voltage applied in operation in the second mode.

[0008] Other features of the invention will become clear from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0009] Figure 1 This is a schematic structural cross-sectional view of the image forming apparatus according to the first embodiment.

[0010] Figure 2 This is a control block diagram of an image forming apparatus according to the first embodiment.

[0011] Figure 3 This is a flowchart of ATVC according to the first embodiment.

[0012] Figure 4 This is a schematic diagram illustrating an example of an adjustment image graph in operation of the secondary transfer voltage adjustment mode according to the first embodiment.

[0013] Figure 5 This is a schematic diagram illustrating another example of the adjustment image graph in the operation of the secondary transfer voltage adjustment mode according to the first embodiment.

[0014] Figure 6 It is a graph showing the relationship between transfer voltage and current in the initial stage of the external secondary transfer roller and in the state where the external secondary transfer roller is being pushed.

[0015] Figure 7 This is a flowchart of the operation in the secondary transfer voltage adjustment mode according to the first embodiment.

[0016] Figure 8 It is a graph used to illustrate the setting of the transfer voltage in the operation of the secondary transfer voltage adjustment mode according to the first embodiment.

[0017] Figure 9 This is a schematic diagram illustrating an example of an adjustment image graph in the operation of the secondary transfer voltage adjustment mode in the initial stage according to the first embodiment.

[0018] Figure 10 This is a flowchart of the operation in the secondary transfer voltage adjustment unit according to the second embodiment. Detailed Implementation

[0019] <First Embodiment>

[0020] Will use Figures 1 to 9 The first embodiment will be described. First, it will be used... Figure 1 and Figure 2 An image forming apparatus according to this embodiment is described.

[0021] [Image forming apparatus]

[0022] In this embodiment, as an example of the image forming apparatus 1, a tandem full-color printer using an intermediate transfer type will be described. The image forming apparatus 1 includes a main assembly 10, a recording material feed unit (not shown), an image forming unit 40, a recording material discharge unit (not shown), a controller 30, and an operation unit 70 (see [link to relevant documentation]). Figure 2 ).

[0023] Inside the main assembly 10 of the device, a temperature sensor 71 capable of detecting the temperature in the image forming apparatus 1 is provided (see [reference]). Figure 2 ) and a humidity sensor 72 capable of detecting humidity in the image forming apparatus 1 (see Figure 2 The image forming apparatus 1 can form a four-color panchromatic image on the recording material S based on image signals from the image reading unit 80, a host device such as a personal computer, or an external device such as a digital camera or smartphone. Incidentally, the recording material S is a material on which toner images are formed, and as specific examples, it can include sheet materials such as ordinary paper, synthetic resin sheets as alternatives to ordinary paper, thick paper, sheets used in overhead projectors, etc.

[0024] The image forming unit 40 is capable of forming an image on the recording material fed from the recording material feeding unit based on image information. The image forming unit 40 includes image forming units 50y, 50m, 50c and 50k, toner bottles 41y, 41m, 41c and 41k, exposure equipment 42y, 42m, 42c and 42k, intermediate transfer unit 44, secondary transfer equipment 45 and fixing unit 46.

[0025] The image forming apparatus 1 satisfies panchromatic image formation, and the multiple image forming units 50y, 50m, 50c, and 50k are each configured for four colors: yellow (y), magenta (w), cyan (c), and black (k), and are arranged separately. For this reason, in Figure 1 In this description, the constituent elements for the four colors are indicated by adding color identifiers to their reference numerals; however, in some cases, the constituent elements of the image forming unit 50y will be used as representatives in the following description. Incidentally, the image forming apparatus 1 is also capable of forming, for example, a monochrome image or a multicolor image using the image forming unit 50 for a desired single color or for some of the four colors respectively.

[0026] The image forming unit 50y includes a photosensitive drum 51y as a movable image carrier member when carrying a toner image, a charged roller 52y as a charged device, a developing device 20y, a pre-exposure device 54y, and a cleaning device equipped with a cleaning blade 55y. The image forming unit 50y is integrally assembled into a unit as a cartridge and is configured to be removable from the main assembly 10 of the apparatus. The image forming unit 50y forms a toner image on the intermediate transfer belt 44b, which will be described later.

[0027] The photosensitive drum 51y is rotatable and carries an electrostatic image for image formation. In this embodiment, the photosensitive drum 51y is formed into a cylindrical shape with an outer diameter of 30 mm and is an organic photosensitive component (OPC) capable of carrying a negative charge. Furthermore, the photosensitive drum 51y is driven to rotate in the direction of the arrow at a predetermined processing speed (circumferential speed). The photosensitive drum 51y uses a cylinder made of aluminum as the base material and includes a surface layer consisting of three layers—a base layer, a photocharge generation layer, and a charge transport layer—continuously stacked on the base material in a defined order.

[0028] The charged roller 52y contacts the surface of the photosensitive drum 51y, and a rubber roller that can rotate with the rotation of the photosensitive drum 51y is used to uniformly charge the surface of the photosensitive drum 51y. Charged bias source 73 (see...) Figure 2The circuit is connected to the charged roller 52y. The charged bias source 73 applies a charged bias voltage to the charged roller 52y, and charges the photosensitive drum 51y via the charged roller 52y. The exposure device 42y is a laser scanner, which forms an electrostatic image on the photosensitive drum 51y by emitting lasers according to the image information of separate colors output from the controller 30.

[0029] Under the applied developing bias voltage, the developing apparatus 20y develops the electrostatic image formed on the photosensitive drum 51y into a toner image using toner. The developing apparatus 20y includes a developing sleeve 24y that serves as a developer carrier. The developing apparatus 20y not only holds the developer supplied from the toner bottle 41y, but also develops the electrostatic image formed on the photosensitive drum 51y.

[0030] The developing sleeve 24y is made of a non-magnetic material such as aluminum or non-magnetic stainless steel, and in this embodiment, a developing sleeve 24y made of aluminum is used. Inside the developing sleeve 24y, a roller-shaped magnetic roller is fixed in a non-rotatable state relative to the developing container. The developing sleeve 24y carries a developer comprising a non-magnetic toner and a magnetic carrier, and feeds the developer to the developing area opposite the photosensitive drum 51y. The developing bias source 74 (see...) Figure 2 It is connected to the developing sleeve 24y. The developing bias source 74 applies a developing bias to the developing sleeve 24y and develops the electrostatic image formed on the photosensitive drum 51y.

[0031] The toner image formed on the photosensitive drum 51y by development is transferred in one pass to the intermediate transfer belt 44b of the intermediate transfer unit 44. After the first transfer, the photosensitive drum 51y is decharged on its surface by a pre-exposure device 54y. A cleaning blade 55y is an opposing blade type and contacts the photosensitive drum 51y with a predetermined pressure. After the first transfer, the toner remaining on the photosensitive drum 51y that was not transferred to the intermediate transfer belt 44b is removed by the cleaning blade 55y, which is set to contact the photosensitive drum 51y, and is ready for subsequent image forming steps.

[0032] The intermediate transfer unit 44 includes a drive roller 44a, a driven roller 44d, an internal secondary transfer roller 45a, an intermediate transfer belt 44b stretched by these rollers (tension rollers), and primary transfer rollers 47y, 47m, 47c, and 47k. The intermediate transfer belt 44b, serving as both an image-carrying component and an intermediate transfer component, forms primary transfer sections 48y, 48m, 48c, and 48k between itself and the photosensitive drums 51y, 51m, 51c, and 51k, respectively, and circulates and moves (i.e., rotates) while carrying the toner image. The driven roller 44d is a tension roller used to control the tension of the intermediate transfer belt 44b at a certain level. A force is applied to the driven roller 44d by the pushing force of a push spring (not shown), causing the intermediate transfer belt 44b to be pressed against the surface of the intermediate transfer belt 44b, so that a tension of about 2-5 kgf is applied to the intermediate transfer belt 44b in the (recording material) feeding direction of the intermediate transfer belt 44b by this force.

[0033] Primary transfer rollers 47y, 47m, 47c, and 47k are respectively deployed opposite to photosensitive drums 51y, 51m, 51c, and 51k via intermediate transfer belts 44b. The primary transfer roller 47y is positioned to sandwich the intermediate transfer belt 44b between itself and the photosensitive drum 51y, and by applying a primary transfer voltage, the toner image formed on the surface of the photosensitive drum 51y is transferred in one pass to the intermediate transfer belt 44b at the primary transfer section 48y. A primary transfer voltage source 75y is connected to the primary transfer roller 47k. A voltage detection sensor 75ay for detecting the output voltage and a current detection sensor 75by for detecting the output current are connected to the primary transfer voltage source 75y (see [link to documentation]). Figure 2 ).

[0034] Incidentally, primary transfer voltage sources 75y, 75m, 75c, and 75k are respectively set for primary transfer rollers 47y, 47m, 47c, and 47k, and the primary transfer voltage applied to primary transfer rollers 47y, 47m, 47c, and 47k can be controlled independently.

[0035] The outer diameter of the primary transfer roller 47y is, for example, 15mm-20mm, and the primary transfer roller 47y comprises an elastic layer of ion-conductive foam rubber (NBR rubber) and a core metal. As the primary transfer roller 47y, a resistance of 1×10⁻⁶ is used. 5 -1×10 8 The Ω (measured under N / N (23°C, 50% RH) conditions, when 2kV is applied) of the roller. Incidentally, the same applies to the other primary transfer rollers 47m, 47c, and 47k.

[0036] The intermediate transfer belt 44b is rotatable and rotates at a predetermined speed in the direction of the arrow. The intermediate transfer belt 44b contacts photosensitive drums 51y, 51m, 51c, and 51k, forming primary transfer sections 47y, 48m, 48c, and 48k respectively between itself and the photosensitive drums 51y, 51m, 51c, and 51k. Primary transfer voltages are supplied from primary transfer voltage sources 75y, 75m, 75c, and 75k respectively (see...). Figure 2 A toner image formed on photosensitive drums 51y, 51m, 51c, and 51k is transferred once at the primary transfer section 48. A positive primary transfer voltage is applied to the intermediate transfer belt 44y by the primary transfer rollers 47y, 47m, 47c, and 47k, thereby transferring a negative toner image from the photosensitive drums 51y, 51m, 51c, and 51k to the intermediate transfer belt 44b multiple times.

[0037] The intermediate transfer belt 44b is an annular belt, which comprises a three-layer structure from the back side, consisting of a base layer, an elastic layer, and a surface layer. As the resin material constituting the base layer, a material containing an appropriate amount of carbon black as an antistatic agent is used in resins such as polyimide or polycarbonate, or in various rubbers, and the thickness of the base layer is 0.05 mm to 0.15 mm. As the elastic material constituting the elastic layer, a material containing an appropriate amount of an ionic conductive agent is used in various rubbers such as polyurethane rubber and silicone rubber, and the thickness of the elastic layer is 0.1 mm to 0.500 mm.

[0038] The surface layer is made of a resin material such as a fluorinated resin, and the deposition force of the toner on the surface of the intermediate transfer belt 44b is small, allowing the toner to be easily transferred to the recording material S at the secondary transfer section N. The thickness of the surface layer is 0.0002-0.020 mm. In this embodiment, regarding the surface layer, one resin material such as polyurethane, polyester, epoxy resin, or two or more elastic materials such as elastic rubber, elastomer, butyl rubber, etc., are used as the base material.

[0039] In addition, in this base material, as a material that enhances lubricity by reducing surface energy, one or more powders or particles of fluorinated resin are dispersed, or such powders or particles are dispersed at different particle sizes, thereby forming a surface layer.

[0040] In this embodiment, the volume resistivity of the intermediate transfer belt 44b is 5 × 10⁻⁶. 8 -1×10 14The Ω.cm (23°C, 50% RH) and MD1 hardness are 60-85° (23°C, 50% RH). Additionally, the static friction coefficient is 0.15-0.6 (23°C, 50% RH) measured using a 94i model manufactured by HZIDON (Shinto Scientific Co., Ltd.). In this embodiment, the intermediate transfer belt 44b has a three-layer structure, but it can also have a single-layer composition corresponding to the material of the aforementioned base layer.

[0041] The secondary transfer printing apparatus 45 includes an inner secondary transfer roller 45a as an inner roller and an outer secondary transfer roller 45b as an outer roller and transfer component. The inner secondary transfer roller 45a stretches the intermediate transfer belt 44b in contact with the inner surface of the intermediate transfer belt 44b, and is deployed opposite to the outer secondary transfer roller 45a via the intermediate transfer belt 44b. A secondary transfer voltage source 76 is connected to the outer secondary transfer roller 45b. A voltage detection sensor 76a for detecting the output voltage and a current detection sensor 76b, which serves as a current detection unit for detecting the output current, are connected to the secondary transfer voltage source 76 (see [link]). Figure 2 ).

[0042] The secondary transfer voltage source 76 applies a DC voltage as the secondary transfer voltage to the external secondary transfer roller 45b. The external secondary transfer roller 45b contacts the intermediate transfer belt 44b and forms a secondary transfer section N between itself and the intermediate transfer belt 44b. By applying a secondary transfer voltage with a polarity opposite to the charge polarity of the toner, the external secondary transfer roller 45b transfers the toner image, which has been transferred once and is carried on the intermediate transfer belt 44b, to the recording material S supplied to the secondary transfer section N.

[0043] Incidentally, the secondary transfer voltage source 76 can also be connected to the internal secondary transfer roller 45a. That is, the secondary transfer voltage source 76 applies a secondary transfer voltage to the internal secondary transfer roller 45a or the external secondary transfer roller 45b to transfer the toner image from the intermediate transfer belt 44b onto the recording material S.

[0044] In this embodiment, the core metal of the inner secondary transfer roller 45a is connected to ground potential. When the recording material S is supplied to the secondary transfer device 45 in this embodiment, a secondary transfer voltage controlled by a constant voltage with a polarity opposite to the charge polarity of the toner is applied to the outer secondary transfer roller 45b. For example, a secondary transfer voltage of 1-7kV is applied and a current of 40-120μA flows through the outer secondary transfer roller 45b, so that the toner image on the intermediate transfer belt 44b is transferred secondaryly onto the recording material S.

[0045] The outer secondary transfer roller 45b has an outer diameter of, for example, 20-25 mm, and includes an elastic layer of ion-conductive foam rubber (NBR rubber) and a core metal. As the outer secondary transfer roller 45b, a resistance of 1×10⁻⁶ is used. 5 -1×10 8 The Ω (measured under N / N (23°C, 50% RH) conditions when 2kV is applied) of the roller.

[0046] Furthermore, the intermediate transfer unit 44 includes a belt cleaning device 60. The belt cleaning device 60 removes deposits such as toners remaining on the intermediate transfer belt 44b after the secondary transfer step. Figure 1 In the example shown, the belt cleaning device 60 is configured with two cleaning sections 61 and 62, each with a voltage of different polarity. Each of the cleaning sections 61 and 62 is provided with a rotatable brush in contact with the intermediate transfer belt 44b and a collection roller for collecting toner deposited on the brush. By applying voltages of different polarities to the cleaning sections 61 and 62, residual toner on the intermediate transfer belt 44b is removed. Incidentally, the belt cleaning device 60 could also be a belt cleaning device equipped with a cleaning scraper for contacting the intermediate transfer belt 44b to remove residual toner, etc.

[0047] The fixing unit 46 includes a fixing roller 46a and a pressure roller 46b. Recording material S is held and fed between the fixing roller 46a and the pressure roller 46b, thereby heating and pressurizing the toner image transferred onto the recording material S, thus fixing it onto the recording material S. Incidentally, the temperature of the fixing roller 46a is detected by a fixing temperature sensor 77 (see [link to product description]). Figure 2 The recording material ejection section ejects the recording material S fed through the ejection channel via the ejection opening, and then stacks the recording material S on the ejection tray. Additionally, a reverse feed channel (not shown) is provided between the fixing section 46 and the ejection opening, in which the fixed recording material S is inverted and can pass through the secondary transfer device 45 again. Through the operation of the reverse feed channel, it is possible to form an image on both sides of a single recording material.

[0048] At the upper part of the main assembly 10, an automatic document feeder 81 is provided for automatically feeding recording material (original) with an image formed thereon toward the image reading unit 80, and an image reading unit 80 is provided for reading the image of the recording material fed by the automatic document feeder 81. The image reading unit 80 is configured such that the original deployed on the table glass 82 is illuminated by a light source (not shown) and the image on the original is read by an image reading element (not shown) at a predetermined dot density.

[0049] like Figure 2As shown, the controller 30, which serves as a control component, is configured as a computer and is capable of controlling the various constituent elements of the image forming apparatus 1. For example, the controller 30 includes a CPU 31, a ROM 32 for storing programs for controlling the various parts, a RAM 33 for temporarily storing data, and an input / output circuit (I / F) 34 for inputting signals from external parts and outputting signals to external parts. The CPU 31 is a microprocessor that manages all control of the image forming apparatus 1 and is the main body of the system controller. The CPU 31 is connected to the recording material feed unit, the image forming unit 40, the recording material discharge unit, and the operation unit 70 via the input / output circuit 34, and not only transmits signals between itself and the various parts, but also controls the operation of the various parts.

[0050] The ROM 32 stores image formation control sequences and the like for forming images on the recording material S.

[0051] A charged bias source 73, a developing bias source 74, primary transfer voltage sources 75y, 75m, 75c, and 75k, and a secondary transfer voltage source 76 are connected to the controller 30 and are controlled by signals from the controller 30. Additionally, a temperature sensor 71, a humidity sensor 72, a voltage detection sensor 76a and a current detection sensor 76b for the secondary transfer voltage source 76, and a fixing temperature sensor 77 are connected to the controller 30. Furthermore, voltage detection sensors 75ay, 75am, 75ac, and 75ak for the primary transfer voltage sources 75y, 75m, 75c, and 75k, and current detection sensors 75by, 75bm, 75bc, and 75bk are connected to the controller 30. Signals detected by each sensor are input to the controller 30. Incidentally, the environmental detection unit 78 can detect values ​​related to temperature and humidity via the temperature sensor 71 and the humidity sensor 72.

[0052] The operation unit 70 includes a display unit 70a consisting of operation buttons, a liquid crystal panel, etc. The user can perform image forming operations by operating the operation unit 70, and the controller 30 receives signals from the operation unit 70 and operates various devices of the image forming apparatus 1. An image forming operation refers to a series of operations performed based on instructions from the operation unit 70 or external devices connected to the image forming apparatus 1 to form an image on recording material.

[0053] In this embodiment, the controller 30 includes an image forming pre-processing unit 31a, an ATVC processing unit 31b, and an image forming processing unit 31c. Additionally, the controller 30 includes a primary transfer voltage storage / calculation unit 31d, a cleaning voltage storage / calculation unit 31e, a secondary transfer voltage storage / calculation unit 31f, an image forming counter storage / calculation unit 31g, and a timer storage / calculation unit 31h. Incidentally, each processing unit and storage / calculation unit can also be provided as part of a CPU 31 or RAM 33. The controller 30 is capable of performing operations in a switching manner in multicolor mode and monochrome mode. In multicolor mode operation, an image with multiple colors is formed by applying a primary transfer voltage to multiple primary transfer units 48y, 48m, 48c, and 48k. In monochrome mode operation, an image with a single color is formed by applying a primary transfer voltage to only one of the multiple primary transfer units 48y, 48m, 48c, and 48k (e.g., 48k).

[0054] Next, the image forming operation in the image forming apparatus 1 constructed accordingly will be described.

[0055] When the image forming unit is activated, firstly, the photosensitive drum 51 rotates, and its surface is charged by the charged roller 52y. Then, the exposure device 42y emits a laser beam to the photosensitive drum 51y based on the image information, thereby forming an electrostatic latent image on the surface of the photosensitive drum 51y.

[0056] The electrostatic latent image is developed with toner using a developing device 20y, and is thus visualized as a toner image.

[0057] Then, the toner image on the photosensitive drum 51y is transferred onto the intermediate transfer belt 44b in one step. This operation is also performed at the image forming section for other colors, so that toner images of multiple colors are superimposed and transferred onto the intermediate transfer belt 44b in one step.

[0058] On the other hand, the recording material S is supplied in parallel with the toner image formation operation, so that the recording material S is conveyed to the secondary transfer device 45 by timing with the toner image on the intermediate transfer belt 44b.

[0059] Then, in the secondary transfer section N, the toner image is transferred from the intermediate transfer belt 44b onto the recording material S. The recording material S with the toner image transferred is conveyed to the fixing section 46, where the unfixed toner image is heated and pressurized, thus fixing it onto the surface of the recording material S, and then discharged from the main assembly 10 of the device.

[0060] [ATVC]

[0061] In this embodiment, during image formation, the secondary transfer voltage applied to the secondary transfer unit N is set using ATVC (Active Transfer Voltage Control), which operates in a first mode. ATVC operates in the following mode: multiple different primary transfer voltages (first test voltages) are applied to the secondary transfer unit N, and the current is detected at each transfer voltage using a current detection sensor 76b, thus obtaining the relationship between the transfer voltage and current. Specifically, in ATVC (operation), with the recording material S not passing through the secondary transfer unit N, constant voltages at multiple levels are applied to the external secondary transfer roller 45b, and the current flowing through the external secondary transfer roller 45b at that time is measured. Then, the voltage-current characteristic is obtained, and based on this, a voltage corresponding to the target current value required for the transfer of the toner image during image formation is calculated by interpolation. Furthermore, the voltage value obtained by adding the voltage shared by the recording material to the obtained voltage is set as the transfer voltage value used during image formation. Based on pre-set table data depending on the temperature and humidity of the environment in which the image forming apparatus is placed, the target transfer current value and the voltage sharing of the recording material are set.

[0062] Will use Figure 3 The process of this ATVC is described in detail. When the controller 30 obtains job information from the operation unit 70 or an external device (not shown), the job operation begins (S1). The controller 30 writes job information, such as image information or recording material information, into the RAM 33 (S2). Then, the controller 30 obtains environmental information detected by the temperature sensor 71 and the humidity sensor 72 (S3). In addition, the ROM 32, which serves as a storage unit, stores information indicating the correlation between the environmental information and the target transfer current Itarget used to transfer the toner image from the intermediate transfer belt 44b to the recording material S.

[0063] The controller 30 obtains the target transfer current Itarget corresponding to the environment from data indicating the relationship between the environmental information read in S3 and the target transfer current Itarget, and writes this (target transfer current Itarget) into RAM 33 (S4). Incidentally, the target transfer current Itarget changes because the amount of toner charge changes depending on the environment.

[0064] Then, before the toner image on the intermediate transfer belt 44b and the recording material P to be transferred with the toner image reach the secondary transfer section N, the controller 30 acquires information about the resistance of the secondary transfer section N via ATVC (S5). That is, with the external secondary transfer roller 45b and the intermediate transfer belt 44b in contact with each other, a predetermined voltage of multiple levels is supplied from the secondary transfer voltage source 76 to the external secondary transfer roller 45b. Then, the current value when the predetermined voltage is supplied is detected by the current detection sensor 76b, thereby acquiring the relationship between voltage and current (i.e., voltage-current characteristic). This voltage-current characteristic changes depending on the resistance of the secondary transfer section N.

[0065] Next, the controller 30 acquires the value of the voltage to be applied from the secondary transfer voltage source 76 to the external secondary transfer roller 45b (S6). That is, based on the target transfer current Itarget written into the RAM 33 in S4 and the relationship between voltage and current acquired in S5, the controller 30 acquires the voltage value Vb required to make the target transfer current Itarget flow through the secondary transfer section N in the state where there is no recording material S in the secondary transfer section N.

[0066] Additionally, ROM 32 stores information for acquiring the recording material sharing voltage Vp. This information is maintained as tabular data showing the relationship between the ambient moisture content and the recording material sharing voltage Vp for each portion of the pre-set basis weight of the recording material S. Incidentally, controller 30 can acquire the ambient moisture content based on environmental information (information about temperature and humidity) detected by temperature sensor 71 and humidity sensor 72. Controller 30 acquires the recording material sharing voltage Vp from the aforementioned tabular data based on the operational information acquired in S1 and the environmental information acquired in S3.

[0067] Furthermore, when setting the adjustment value through the operation in the secondary transfer voltage adjustment mode described later, the adjustment amount ΔV is obtained. Then, the controller 30 obtains the voltage applied from the secondary transfer voltage source 76 to the external secondary transfer roller 45b as the secondary transfer voltage Vtr when the recording material S passes through the secondary transfer section N. This voltage is obtained as the secondary transfer voltage Vtr, which is the sum of Vb, Vp, and ΔV, namely Vb+Vp+ΔV, and is written into the RAM 33. Incidentally, tabular data for obtaining the voltage Vp shared by the recording material is obtained in advance through experiments, etc.

[0068] Next, the recording material S is sent to the secondary transfer unit N, where an image is formed while a secondary transfer voltage Vtr is applied (S7). Thereafter, the controller 30 repeats S7 until all images in the job are completely transferred and output to the recording material S (S8).

[0069] Incidentally, this embodiment illustrates ATVC by applying multiple different first transfer voltages (first test voltages), i.e., by applying multiple test biases at multiple levels, but the invention is not limited thereto. For example, ATVC can also be performed by detecting the voltage applied while the voltage is under constant current control to provide a target transfer current Itarget. That is, ATVC can also be performed with a single level of test bias.

[0070] [Adjustment mode for secondary transfer voltage]

[0071] Next, the operation in the adjustment mode of the secondary transfer voltage, which is the second mode, will be described. For example, depending on the type of recording material used by the user, the resistance value of the recording material is different from the resistance value of the recording material held as the table data as described above. Therefore, in some cases, optimal transfer cannot be performed when using the recording material sharing voltage Vp in the table data.

[0072] Specifically, to prevent defective images from appearing when the toner image on the intermediate transfer belt 44b is transferred to the recording material, an optimal secondary transfer voltage Vtr needs to be applied. However, when the resistance value of the recording material used by the user is higher than the resistance value of the recording material used to hold the table data, there is a tendency for the current required to transfer the toner image to become insufficient, thus resulting in defective transferred images (void images). For this reason, in certain situations, the secondary transfer voltage Vtr needs to be set to a high value.

[0073] In addition, when the water content of the recording material decreases and discharge phenomena tend to occur, image defects such as void images may occur due to abnormal discharge, which may require a reduction in the secondary transfer voltage Vtr.

[0074] Therefore, the operation performed in the mode to obtain the adjustment amount required for the optimal secondary transfer voltage Vtr that provides an image without existing defects is the operation in the adjustment mode. In the operation in the adjustment mode, a predetermined image is transferred from the intermediate transfer belt 44b to the recording material at multiple different transfer voltages (test voltage, second test voltage), and then the recording material is output. That is, the operation in the adjustment mode is the operation in the mode that outputs a test chart for adjusting the transfer voltage set during image formation by transferring the predetermined image from the intermediate transfer belt 44b to the recording material at multiple different test voltages.

[0075] Specifically, the output is formed as follows Figure 4 The document shows the adjusted image chart. (About) Figure 4The image chart shown in the figure is used to create pattern images, each comprising a solid density image (solid black area) and a halftone density area (shaded area). Furthermore, by switching the output value of the secondary transfer voltage Vtr for each pattern image, the corresponding pattern image is formed while altering the transfer properties.

[0076] Then, based on multiple predetermined images on the output recording material, the transfer voltage during image formation is adjusted by using a transfer voltage selected from multiple different transfer voltages. For example, the user selects the transfer voltage corresponding to the image identified as the optimal image from multiple predetermined images on the output recording material, and then the user adjusts the secondary transfer voltage Vtr used during subsequent image formation by using the selected transfer voltage. That is, the user selects a pattern image that provides optimal transfer properties from an image adjustment chart, and the controller 30 obtains the adjustment amount ΔV of the secondary transfer voltage Vtr.

[0077] By performing this operation in the adjustment mode, it is not necessary to perform any operation, such as when the user changes the secondary transfer voltage to output the expected image one by one on the sheet, and then determine the adjustment amount ΔV while checking the transfer properties, so that the amount of recording material used for inspection can be reduced and the adjustment time can be reduced.

[0078] Will use Figure 4 and Figure 5 Specifically, the adjustment of the image chart is described. In the operation of the secondary transfer voltage adjustment mode in this embodiment, an image chart including a pattern image is used, wherein an image chart is arranged as shown in the figure. Figure 4 The image shown is suitable for distinguishing solid-density images of blue secondary color, solid-density images of black (monochrome), and halftone images of black in terms of transfer properties. Incidentally, when the size is small, it is difficult to distinguish; therefore, the image size is preferably 10 square millimeters or larger, more preferably 25 square millimeters or larger.

[0079] On one side of each pattern image, a value corresponding to the adjustment amount ΔV of the secondary transfer voltage Vtr applied to the pattern image is indicated. That is, on the recording material output during operation in adjustment mode, values ​​related to multiple different transfer voltages are also printed corresponding to multiple predetermined images. To the pattern image with a value of 0, a voltage value of Vb+Vp+ΔV of the secondary transfer voltage Vtr, where the adjustment amount ΔV set in the aforementioned ATVC is 0V, is applied. Furthermore, in this embodiment, the adjustment amount is calculated such that 100V is considered "1", and for example, in the case where the adjustment amount ΔV is +300V, the adjustment amount is indicated as "+3", and a secondary transfer voltage Vtr of Vb+Vp+300V is applied to the pattern image.

[0080] The maximum size of recording material that can be used in the image forming apparatus is 13 inches × 19.2 inches. However, even when forming an adjustment image chart on a recording material smaller than the largest size, the adjustment image chart is output with the front-end center aligned with the recording material. For example, for A3 size, the adjustment image chart is output by cutting an area with dimensions of 292 × 415 mm. In this embodiment, as an example, an adjustment image chart with 11 patterned images is used, but the invention is not limited to this.

[0081] The dimensions of each pattern image are such that each of the blue secondary color and black (monochrome) solid density images is 25.7 square millimeters, and the grayscale halftone density image extends from the portion adjacent to the associated (blue or black) solid density image to the associated end in a width direction perpendicular to the feed direction, with a length of 25.7 mm relative to the feed direction. The adjacent pattern images are spaced 9.5 mm apart relative to the feed direction, and the secondary transfer voltage Vtr is switched within this interval. The 11 pattern images arranged in the feed direction cover a range of 387 mm to fall within an A3 dimension of 415 mm relative to the feed direction.

[0082] There is a possibility that another defective image may appear in the front and back parts, which may only appear in the front and back parts. Therefore, pattern image formation is not performed.

[0083] When using recording material whose length relative to the feed direction is shorter than A3 size recording material, use as follows: Figure 5 The adjustment image chart shown is 13 inches × 210 mm in size, allowing it to accommodate recording material fed in A5 short-side feed mode to sizes smaller than A3. The width of the halftone image is shortened to match the length of the recording material relative to its width, and the output length of the five pattern images relative to the feed direction is 167 mm, resulting in a longer rear margin corresponding to the length of the recording material. Only five pattern images can be printed on a single sheet, so to increase the number of pattern images, they are output on two sheets.

[0084] [Transfer voltage setting in adjustment mode]

[0085] Next, the transfer voltage setting in the operation of the secondary transfer voltage adjustment mode in this embodiment will be described. As a transfer member for transferring toner images from the intermediate transfer belt 44b to the recording material or from the photosensitive drum to the recording material, conductive members such as transfer rollers, which are made by forming a film using foam rubber with ion-conductive materials, are often used. Transfer members using ion-conductive materials have the characteristic that their resistance increases when a certain voltage is continuously applied. Figure 6 This is a graph showing the relationship between voltage and current during the passage of material through the secondary transfer section N, both in the initial stage of using the external secondary transfer roller and after its endurance period, in the case where the external secondary transfer roller 45b, using an ion-conductive material, is used to illustrate an example of increased resistance. In other words, the voltage-current characteristic, representing the relationship between the voltage applied by the secondary transfer voltage source 76 and the current detected by the current detection sensor 76b, is shown below. Figure 6 As shown. As from Figure 6 As understood, the resistance of the external secondary transfer roller 45b increases with use, causing a change in the voltage-current characteristics.

[0086] In other words, when the resistance of the external secondary transfer roller 45b increases due to use, the change in current becomes less than the change in transfer voltage. Then, even when as described above... Figure 4 and Figure 5 When multiple pattern images are output as shown, the change in current value for each pattern image is small, and it is not easy to distinguish the differences in transfer properties, making it difficult to determine the optimal transfer voltage. For example, even after the durability of the external secondary transfer roller 45b, when multiple pattern images are output by changing the transfer voltage by a similar amount as in the initial stage, the differences in transfer properties are not easily distinguishable compared to the image charts output in the initial stage. On the other hand, in order to properly distinguish the transfer properties even after the durability, an increase in the number of pattern images to be output is considered. However, in this case, the number of output sheets of recording material to be transferred pattern images increases.

[0087] Therefore, in this embodiment, during operation in the secondary transfer voltage adjustment mode, the secondary transfer voltage Vtr applied simultaneously with each pattern image change in the adjusted image graph is set based on the voltage-current characteristics of the transfer member obtained in the ATVC, rather than a fixed value. In other words, multiple different transfer voltages are set during operation in the adjustment mode based on the relationship between transfer voltage and current obtained in the ATVC. Accordingly, even when the resistance value of the transfer member fluctuates, and even after the durability period, differences in transfer properties can be easily distinguished, making it possible to appropriately adjust the secondary transfer voltage.

[0088] Below, we will use Figure 7 The flowchart below describes the operation in the secondary transfer voltage adjustment mode of this embodiment. Incidentally, in Figure 9 In the middle, it is shown that the use of... Figure 7 The diagram illustrates the calculation method of the secondary transfer voltage Vtr applied to the pattern image in the adjustment image chart in the operation process of the secondary transfer voltage adjustment mode.

[0089] The user selects the type and size of the recording material for which the secondary transfer voltage is to be adjusted, and whether the printing is single-sided or double-sided, via the operation unit 70 (S101). Here, the output of a basis weight of 150g / m³ via single-sided printing will be described. 2 The A3-sized recording material is then used. Subsequently, when the user selects the test page output button via the operation unit 70 (S102), the image forming apparatus begins the image forming operation of the test page and performs ATVC during the pre-rotation period of this image forming operation, thereby acquiring the voltage-current characteristics of the secondary transfer unit (S103). Incidentally, pre-rotation refers to the period before the image forming operation, during which the photosensitive drum begins to rotate as a preparatory operation and various voltages are continuously increased and adjusted. Furthermore, the test page refers to a page containing an adjustment image chart including the aforementioned multiple pattern images.

[0090] Next, the secondary transfer voltage Vtr to be applied to the pattern image in the adjusted image graph is calculated (S104). This will be done using... Figure 8 The explanatory diagram below serves as an example to specifically describe the calculation method. Incidentally, (1) to (4) below correspond to... Figure 8 (1) to (4).

[0091] (1) First, using an approximate expression for the voltage-current characteristics of the secondary transfer section obtained by ATVC, the voltage value Vb required to make the target transfer current Itarget (e.g., 37 μA) flow through the secondary transfer section depends on the conditions selected in S101. Additionally, the recording material sharing voltage Vp (e.g., 1500 V) is obtained by referring to table data.

[0092] (2) The adjustment amount (value) ΔV is set to 0V, and then the secondary transfer voltage Vtr (e.g., 4200V) is obtained as Vp+Vb+ΔV, and the secondary transfer voltage Vtr at this time is used as the center value Vtr(def). In addition, on one side of the pattern image with the center value Vtr(def), 0 is indicated as the value corresponding to the adjustment amount ΔV.

[0093] (3) Calculate the amount of current ΔIn (e.g., 4μA) and the voltage value ΔVn (e.g., Δ300V) corresponding to the change of ΔIn for each pattern image from a pre-set approximate expression of the voltage-current characteristics obtained by ATVC.

[0094] (4) The secondary transfer voltage Vtr to be applied to the associated pattern image is set by adding the voltage value ΔVn for the associated pattern image to the center value Vtr(def) of the secondary transfer voltage Vtr in (2) above.

[0095] In (4) above, for example, the transfer voltage is set to a secondary transfer voltage Vtr for the pattern image by increasing the center value Vtr(def) by one level as follows. That is, 300V, which is the voltage value ΔVn corresponding to the current value ΔIn corresponding to one level, is used as the adjustment value ΔV, so that 4500V is obtained by adding 300V to 4200V, which is the center value Vtr(def).

[0096] On one side of the associated pattern image, in this case, "+3" is indicated by treating 100V as "1".

[0097] Additionally, for other pattern images, the secondary transfer voltage Vtr is set in a similar manner. Subsequently, while switching the output value for each pattern image, the output is as follows: Figure 4 The image chart shown is for adjustment (S105).

[0098] The user selects a pattern image that provides optimal transfer properties from the output adjustment image chart (S106), and the indicated value is input as recording material information to a predetermined portion of the display screen of the operation unit 70, and thus recorded in the image forming apparatus (S107). Thereafter, when the user uses the recording material, the adjustment amount ΔV is reflected, enabling optimal transfer performance to be obtained.

[0099] exist Figure 9 The image shown is an adjustment graph output during operation in the adjustment mode of the secondary transfer voltage in this embodiment, when using the external secondary transfer roller 45b in the initial stage. In the initial stage, with... Figure 4Compared to the durability period shown, the resistance value of the external secondary transfer roller 45b is lower, and the voltage value ΔVn to be changed is smaller, thus indicating a smaller value on one side of the associated pattern image.

[0100] In other words, in this embodiment, during the operation of the secondary transfer voltage adjustment mode, the difference (voltage value ΔVn) between multiple different secondary transfer voltages (between test voltages) is a first difference when the cumulative number of recording materials passing through the secondary transfer section N is a first number of sheets (e.g., in the initial stage). On the other hand, the voltage value ΔVn is a second difference that is larger than the first difference when the cumulative number of recording materials passing through the secondary transfer section N is a second number of sheets greater than the first number of sheets (e.g., after the durability period). In other words, the voltage value ΔVn is small when the cumulative number of sheets is small—that is, in the initial stage or near the initial stage—and large when the cumulative number of sheets is large—that is, after the durability period.

[0101] Furthermore, in this embodiment, during operation in the secondary transfer voltage adjustment mode, the difference (voltage value ΔVn) between multiple different secondary transfer voltages (between test voltages) is a first difference when the resistance value of the external secondary transfer roller 45b is a first resistance value. On the other hand, the voltage value ΔVn is a second difference that is larger than the first difference when the resistance value of the external secondary transfer roller 45b is a second resistance value that is larger than the first resistance value.

[0102] As mentioned above Figure 6 As shown on the left, in the initial stage, the change in current is greater than the change in voltage, therefore, as Figure 9 As shown, even when the voltage value ΔVn is small, the change in current value for each pattern image is large, making the differences in transfer properties distinguishable. On the other hand, when multiple pattern images are formed after the durability period with the same voltage value ΔVn as in the initial stage, as... Figure 6 As shown on the right, the change in current relative to the change in voltage is small. Therefore, the change in current value for each pattern image is small, making the transfer properties difficult to distinguish.

[0103] Therefore, in this embodiment, the voltage value ΔVn is set using the voltage-current characteristics of the secondary transfer section obtained by ATVC. Accordingly, after the durability period, the resistance value of the external secondary transfer roller 45b increases and the voltage-current characteristics are at a certain level. Figure 6 In the right-hand state, the voltage value ΔVn increases. Therefore, the change in current value for each pattern image can be large, making the transfer properties distinguishable. Furthermore, to distinguish the transfer properties, it is not necessary to increase the number of pattern images by increasing the number of output sheets for adjusting the image graphs.

[0104] Therefore, in this embodiment, the selection accuracy of the optimal transfer voltage can be improved while suppressing an increase in the number of output sheets of recording material with a pattern image as a predetermined image transferred. In other words, in this embodiment, an optimal adjustment image chart can be output depending on the resistance value of the external secondary transfer roller 45b. For this reason, even when the resistance value of the external secondary transfer roller 45b fluctuates, in the operation of the secondary transfer voltage adjustment mode, the selection accuracy of the optimal transfer setting value can be improved by reducing the adjustment time without increasing the number of output sheets with the adjustment image chart.

[0105] This embodiment describes obtaining the voltage value ΔVn corresponding to a current value ΔIn at a given level based on the voltage-current characteristics obtained from the ATVC, but the invention is not limited thereto. For example, the invention is also applicable to the case where a test voltage of one level is applied in the ATVC. In this case, the voltage value ΔVn corresponding to a current value ΔVn at a given level can also be obtained based on the current when a test voltage of one level is applied. Although the accuracy is reduced compared to the case where two or more test voltages are applied in the ATVC, the voltage value ΔVn corresponding to a current value ΔIn at a given level can vary depending on the resistance value of the external secondary transfer roller.

[0106] <Second Embodiment>

[0107] Will be in reference Figure 1 and Figure 2 Simultaneous use Figure 10 The second embodiment is described below. In the first embodiment described above, the secondary transfer voltage for each pattern image is set in the operation of the secondary transfer voltage adjustment mode using the voltage-current characteristics of the secondary transfer unit obtained by the ATVC. On the other hand, in this embodiment, in the operation of the secondary transfer voltage adjustment mode, the secondary transfer voltage for each pattern image is set depending on the environment of the image forming apparatus and the number of accumulated sheets without obtaining the voltage-current characteristics of the secondary transfer unit obtained by the ATVC. Other configurations and functions are similar to those of the first embodiment described above. Therefore, configuration elements similar to those of the first embodiment are indicated by the same reference numerals or symbols and will be omitted from the description and illustrations or will be briefly described. Hereinafter, the differences from the first embodiment will be mainly described.

[0108] Here, the resistance value of the external secondary transfer roller 45b, which serves as the transfer component, varies depending on the amount of sheet material used in the image forming apparatus (i.e., the cumulative amount of recording material sheet material passing through the secondary transfer section N) and the environment of the image forming apparatus. For this reason, in this embodiment, the secondary transfer voltage Vtr applied to the pattern image of the image adjustment chart is set based on the environment of the image forming apparatus and the cumulative amount of recording material sheet material. Accordingly, similar to the first embodiment, even if the resistance value of the external secondary transfer roller 45b fluctuates with use, the current amount can be changed within the image adjustment chart.

[0109] The image forming apparatus of this embodiment is configured such that, in order to set the secondary transfer voltage for each pattern image of the adjusted image chart, the voltage-current characteristics of the secondary transfer section are not acquired via ATVC. For this reason, compared to the configuration of the first embodiment, the current detection sensor 76b for the secondary transfer voltage source (… Figure 2 The ATVC processing unit 31b can also be omitted.

[0110] On the other hand, the image forming apparatus of this embodiment also enables the controller 30 ( Figure 2 As a counting unit, it counts the cumulative number of sheets that have passed through the secondary transfer unit N as a value related to the use of the external secondary transfer roller 45b. Alternatively, the value related to the use of the external secondary transfer roller 45b can also be the number of rotations of the external secondary transfer roller 45b, and the controller 30 can also count this number of rotations. Furthermore, in this embodiment, the environmental detection unit 78, capable of detecting values ​​related to temperature and humidity, consists of a temperature sensor 71 and a humidity sensor 72. Figure 2 ) constitutes. Additionally, in the ROM 32 (which serves as the storage unit) Figure 2 In this context, the stored values ​​depend on the use of the external secondary transfer roller 45b (in this embodiment, the cumulative number of sheets) and the relationship between the secondary transfer voltage and current, which depends on temperature and humidity.

[0111] Furthermore, in this embodiment, multiple different secondary transfer voltages are stored in the operation of the adjustment mode, and the secondary transfer voltage is set based on the relationship between the secondary transfer voltage and the current, which depends on the value counted by the controller 30 (cumulative sheet quantity) and the value detected by the environmental detection unit 78. Hereinafter, we will use... Figure 10 Describe this setting in detail.

[0112] exist Figure 10The diagram shows a flowchart of the operation in the secondary transfer voltage adjustment mode of this embodiment. The user selects the type and size of the recording material for which the secondary transfer voltage is to be adjusted, and whether the printing is single-sided or double-sided, via the operation unit 70 (S201). Then, the user selects the test page output button via the operation unit 70 (S202). Then, the secondary transfer voltage Vtr is applied to each pattern image in the adjustment image chart (S204).

[0113] The calculation method for the secondary transfer voltage Vtr is as follows. In this embodiment, the voltage Vtr is obtained in advance through experiments. Figure 1 The data of ΔVn (the difference between multiple different secondary transfer voltages in operation in the secondary transfer voltage adjustment mode) corresponding to the predetermined ΔIn in the actual image forming apparatus shown in the figure is stored as a database in ROM 32. When outputting an adjusted image chart, ΔVn corresponding to the predetermined ΔIn is read from the database in ROM 32, and the secondary transfer voltage Vtr applied to the pattern image is set.

[0114] Furthermore, in this embodiment, similar to the situation described in the first embodiment, the voltage value ΔVn decreases when the cumulative sheet quantity is small—that is, in the initial stage or near the initial stage—and increases when the cumulative sheet quantity is large—that is, after the durability period. Additionally, the ambient moisture content (moisture content in the air within the image forming apparatus) is calculated based on the temperature and humidity detected by the environmental detection unit 78. When the calculated moisture content is low, the resistance value of the external secondary transfer roller 45b becomes greater than when the moisture content is high. Therefore, when the moisture content is low, the voltage value ΔVn becomes greater than when the moisture content is high. In other words, when the environment within the image forming apparatus is a first environment, the voltage value ΔVn is a first difference, and when the environment within the image forming apparatus is a second environment where the moisture content in the air is lower than in the first environment, the voltage value ΔVn is a second difference greater than the first difference.

[0115] For example, when the cumulative number of sheets is the same, the voltage value Vtr is larger when the moisture content detected by the environmental detection unit 78 is low than when the moisture content is high. Similarly, when the moisture content is the same, the voltage value Vtr is larger when the cumulative number of sheets is high compared to when the cumulative number of sheets is low. The ROM 32 stores the relationship between ΔIn and ΔVn, which depends on the cumulative number of sheets and environmental information (e.g., moisture content). Therefore, the controller 30 sets the secondary transfer voltage Vtr applied to the pattern image by referring to this relationship.

[0116] The secondary transfer voltage Vtr is set, and then, while switching the output value for each pattern image, an adjustment image chart is output (S205). The user selects a pattern image for optimal transfer properties from the output adjustment image chart (S206), and the indicated value is input as recording material information to a predetermined portion on the operation unit 70, and thus recorded in the image forming apparatus (S207).

[0117] Therefore, in this embodiment, the set value of the secondary transfer voltage Vtr is calculated based on the voltage-current characteristics obtained in advance through experiments, which depend on values ​​related to the use of the external secondary transfer roller 45b (i.e., the cumulative number of sheets and the environment in this embodiment). Accordingly, for example, the structure related to ATVC is omitted. Furthermore, even when such a structure is omitted and an image forming apparatus with low-cost and simple controls is used, effects similar to those of the first embodiment can be obtained. That is, when the resistance value of the external secondary transfer roller 45b fluctuates, the selection accuracy of the optimal transfer set value can be improved by reducing the adjustment time without increasing the number of sheets output from the adjustment image chart used to adjust the secondary transfer voltage.

[0118] <Other Embodiments>

[0119] In the above embodiments, in the intermediate transfer type configuration using an intermediate transfer belt, the adjustment of the secondary transfer voltage in the secondary transfer section was described. However, the present invention is not limited to this, and can also be applied to configurations employing a direct transfer type where the toner image is directly transferred from the photosensitive drum to the recording material, and using, for example, a primary transfer roller made of an ion-conductive material as the transfer member. That is, the primary transfer roller forms a primary transfer section between itself and the photosensitive drum for transferring the toner image from the photosensitive drum to the recording material. Then, by applying a primary transfer voltage to the primary transfer roller, the toner image is transferred from the photosensitive drum to the recording material. Similarly, in such a primary transfer section, similar to the secondary transfer section described above, the resistance value of the primary transfer roller changes during the initial stage and after the durability period. For this reason, an adjustment similar to the adjustment of the transfer voltage in the above embodiments is applied to the adjustment of the primary transfer voltage.

[0120] Furthermore, the present invention is not limited to the cascaded image forming apparatus 1 using the intermediate transfer type, but may also be another type of image forming apparatus. Moreover, the image forming apparatus is not limited to a full-color image forming apparatus, but may also be a monochromatic image forming apparatus or a single-color image forming apparatus. Alternatively, the present invention can be made for various purposes such as printers, various printing machines, copiers, fax machines, and multifunction printers.

[0121] According to the present invention, the selection accuracy of the optimal transfer voltage can be improved, while suppressing the increase in the number of output sheets of recording material with a predetermined image transferred.

[0122] While the invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be given the broadest interpretation to include all such modifications and equivalent structures and functions.

Claims

1. An image forming apparatus, comprising: An image carrier component, the image carrier component being configured to carry a toner image; The toner image is transferred from the image carrier member to the transfer belt in one step. A secondary transfer component is configured to transfer a toner image from the transfer belt onto the recording material in a secondary transfer section. A voltage source configured to apply a transfer voltage to the secondary transfer member; A current detection unit is provided, which is capable of detecting the current flowing from the voltage source through the secondary transfer member; as well as The controller is capable of controlling the voltage source. The controller is capable of performing operations in the first mode, in which, when there is no recording material in the secondary transfer section, the current detection unit detects the current flowing through the secondary transfer member when a voltage is applied to the secondary transfer member. The controller is capable of performing operations in a second mode, in which test charts for adjusting the transfer voltage are printed. These test charts include multiple test images transferred from the transfer tape to the recording material under multiple different test voltages applied to the secondary transfer component. The plurality of test images includes a first test image and a second test image, wherein the second test image is adjacent to the first test image in the direction of movement of the transfer belt. Specifically, a first test image is transferred by applying a first test voltage to the secondary transfer component, and a second test image is transferred by applying a second test voltage to the secondary transfer component. The controller is configured to change the difference between the first test voltage and the second test voltage based on the current detected during operation in the first mode.

2. The image forming apparatus according to claim 1, wherein, When the controller performs the operation in the second mode on the predetermined recording material, When the voltage required to make a predetermined current flow through the secondary transfer member, based on the current detected by the current detection unit during operation in the first mode, is a first voltage, the difference is a first difference, and When the voltage required to make the predetermined current flow through the secondary transfer member based on the current detected by the current detection unit in the first mode operation is a second voltage that is higher than the first voltage, the difference is a second difference that is larger than the first difference.

3. The image forming apparatus according to claim 1, wherein, The controller executes the operation in the first mode after receiving the instruction to execute the operation in the second mode and before executing the operation in the second mode.

4. The image forming apparatus according to claim 1, wherein, During operation in the first mode, the controller causes the current sensing unit to detect the current flowing through the secondary transfer component when multiple different test voltages are applied to the secondary transfer component, and acquires information about the current-voltage characteristics of the secondary transfer component. Based on the information, the controller is configured to change the difference between the first test voltage and the second test voltage.

5. An image forming apparatus, comprising: An image carrier component, the image carrier component being configured to carry a toner image; The toner image is transferred from the image carrier member to the transfer belt in one step. A secondary transfer component is configured to transfer a toner image from the transfer belt onto the recording material in a secondary transfer section. A voltage source configured to apply a transfer voltage to the secondary transfer member; A voltage detection unit configured to detect voltage from the voltage source; as well as A controller, configured to control the voltage source. The controller is configured to perform the operation in the first mode, in which, when there is no recording material in the secondary transfer section, the voltage detection unit detects the voltage output by the voltage source when current flows through the secondary transfer member. The controller is configured to perform operations in a second mode, in which test charts for adjusting the transfer voltage are printed. These test charts include multiple test images transferred from the transfer tape to the recording material under multiple different test voltages applied to the secondary transfer member. The plurality of test images includes a first test image and a second test image, wherein the second test image is adjacent to the first test image in the direction of movement of the transfer belt. Specifically, a first test image is transferred by applying a first test voltage to the secondary transfer component, and a second test image is transferred by applying a second test voltage to the secondary transfer component. The controller is configured to change the difference between the first test voltage and the second test voltage based on the voltage detected during operation in the first mode.

Images