Image forming device

Abstract

The present invention discloses an image forming device. The image forming device includes an image bearing member that can bear a toner image, a transfer member for transferring the toner image from the image bearing member to a recording material, and a reading device that reads density information of an image on the recording material disposed on a platen. The image forming device forms a first chart on a first recording material and a second chart on a second recording material by sequentially transferring a plurality of test images while applying a plurality of test voltages to the transfer member. The reading device reads the two charts and adjusts the transfer voltage based on the reading result.

Description

Technical Field

[0001] The present disclosure relates to an image forming apparatus using an electrophotographic system and an electrostatic recording system, such as a copying machine, a printer, or a facsimile apparatus. Background Art

[0002] An image forming apparatus using an electrophotographic system has conventionally included an intermediate transfer system image forming apparatus that primarily transfers a toner image formed on an image bearing member such as a photosensitive drum to an intermediate transfer member such as an intermediate transfer belt, and then secondarily transfers the toner image from the surface of the intermediate transfer member to a recording material. The primary transfer is performed by applying a primary transfer voltage to a primary transfer portion where the image bearing member and the intermediate transfer member are in contact. When the recording material passes through a secondary transfer portion where the intermediate transfer member and the secondary transfer member are in contact, the secondary transfer is performed by applying a secondary transfer voltage to the secondary transfer portion.

[0003] In order to obtain high-quality image products, it is necessary to set an appropriate value to the secondary transfer voltage to be applied when the toner image on the intermediate transfer member is electrostatically and secondarily transferred to the recording material. In the case where the secondary transfer voltage is insufficient for the charge amount of the toner on the intermediate transfer member, the desired image density is sometimes not obtained due to insufficient toner transfer to the recording material. In the case where the secondary transfer voltage is too high, discharge occurs at the secondary transfer portion, and the charged polarity of the toner on the intermediate transfer member is reversed due to the discharge. This sometimes causes a "white spot" in which the toner image on the intermediate transfer member is partially not transferred.

[0004] The amount of charge required for secondary transfer of the toner on the intermediate transfer member onto the recording material fluctuates differently depending on the size of the recording material and the area ratio of the toner image. Therefore, the secondary transfer voltage to be supplied to the secondary transfer portion is often applied as a constant voltage by outputting a fixed voltage corresponding to a predetermined current density. This is because, in this case, a transfer current corresponding to a predetermined voltage can be ensured in an important portion where the toner image is to be transferred, regardless of the current flowing outside the recording material or flowing in a portion where the toner image does not exist on the recording material.

[0005] The secondary transfer voltage can be determined based on the transfer portion partial voltage corresponding to the resistance of the secondary transfer portion detected in the preliminary rotation process performed before image formation and the recording material partial voltage corresponding to the preset type of recording material. With this configuration, an appropriate secondary transfer voltage can be set according to environmental changes, the use history of the transfer member and the type of recording material. However, because recording materials of various types and states are used for image formation, the preset default recording material partial voltage sometimes causes excess or deficiency of the secondary transfer voltage. In view of the foregoing, it is proposed that the image forming device is provided with an adjustment mode in which the setting voltage of the transfer voltage can be adjusted according to the recording material to be actually used in image formation.

[0006] Japanese Patent Application Laid-Open No. 2013-37185 discusses an image forming apparatus including an adjustment mode for adjusting a setting voltage of a secondary transfer voltage. In this adjustment mode, a chart including a plurality of color patches (test images) formed on a recording material is output while switching the secondary transfer voltage for each color patch. The chart is read by a reading device provided in the image forming apparatus, and the density of each color patch is detected. Then, an optimal secondary transfer voltage condition is selected according to the detection result.

[0007] In the case of using the above-mentioned chart, the size of the chart to be formed in one adjustment is sometimes desired to become larger in consideration of forming a sufficient number of color patches, the detection accuracy of the density of each color patch, and the ease of determination to be made by the operator. In addition, although only one chart is formed in the case of using a sheet having a large size such as A3 size, two charts are sometimes formed in the case of using a recording material having a small size such as A4 size or letter (LTR) size.

[0008] In the case of forming two charts, it is conventionally necessary for the operator to switch the chart placed on the reading device for each chart. Therefore, for example, in a platen type reading device, the operator needs to place the chart on the reading device twice. In the case of outputting a double-sided adjustment chart including color patches formed on both surfaces of a recording material, the operator needs to place the chart on the reading device four times. If the operator is required to perform the operation of placing the chart on the reading device an increasing number of times in this manner, usability may decrease. Summary of the invention

[0009] In view of the foregoing, an aspect of the present disclosure is to provide an image forming apparatus that can enhance usability by reducing the number of times a chart is placed on a reading device.

[0010] According to a representative configuration of the present disclosure, an image forming apparatus includes: an image bearing member configured to bear a toner image; a transfer member configured to transfer the toner image from the image bearing member to a recording material; an applying unit configured to apply a voltage to the transfer member; a discharging unit configured to discharge a recording material including an image formed by fixing the toner image transferred by the transfer member; a platen on which the recording material is disposed when the image on the recording material is to be read; a reading device configured to read concentration information of the image on the recording material disposed on the platen; and a control unit configured to The control unit is configured to execute an adjustment mode for adjusting a transfer voltage to be applied by the applying unit to the transfer member in a transfer process by discharging a first recording material and a second recording material from the discharging unit, the first recording material including a first chart formed by sequentially transferring a plurality of test images by applying a plurality of test voltages to the transfer member by the applying unit, and the second recording material including a second chart formed by sequentially transferring a plurality of test images by applying a plurality of test voltages to the transfer member by the applying unit, wherein the control unit is configured to adjust the transfer voltage based on a reading result obtained by the reading device reading the first recording material and the second recording material deployed together on the platen.

[0011] Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic cross-sectional view of an image forming apparatus.

[0013] Figure 2 is a block diagram illustrating a control system of the image forming apparatus.

[0014] Figure 3 is a flowchart schematically illustrating a control process of a secondary transfer voltage.

[0015] Figure 4 A graph indicating voltage and current characteristics obtained by controlling the secondary transfer voltage is illustrated.

[0016] Figure 5 is a schematic diagram illustrating an example of a table of partial pressures of recording materials.

[0017] Fig. 6A and 6B It is a schematic diagram of a chart used for large-size recording materials.

[0018] Fig. 7A ,7B , 7C and 7D are schematic diagrams of diagrams for small-size recording materials.

[0019] Figure 8 is a flowchart illustrating a procedure of an adjustment mode according to the first exemplary embodiment.

[0020] Fig. 9A , 9B 9C are diagrams of a setting screen of the adjustment mode.

[0021] Fig.10 is a flowchart illustrating the procedure of determination processing of an adjustment value according to the first exemplary embodiment.

[0022] Fig.11 A graph indicating an example of a relationship between an average value of luminance of a color patch and a test voltage is illustrated.

[0023] Fig. 12A and 12B A graph indicating an example of a relationship between a luminance average value of a color patch and a test voltage is illustrated.

[0024] Fig.13 is a flowchart illustrating the procedure of determination processing of an adjustment value according to the second exemplary embodiment.

[0025] Fig.14A and 14B is a schematic diagram of another example of a chart for a large-size recording material.

[0026] Fig.15A , 15B , 15C and 15D are schematic diagrams of another example of a chart for a small-size recording material.

[0027] Fig.16 This is a diagram illustrating the correspondence between the colors of the page determination color blocks and the page numbers.

[0028] Fig.17 is a flowchart of a process of optimizing the arrangement and order of read images according to the third exemplary embodiment.

[0029] Fig.18 is a diagram illustrating the effects according to the third exemplary embodiment. DETAILED DESCRIPTION

[0030] Hereinafter, an image forming apparatus according to an exemplary embodiment of the present disclosure will be described in more detail with reference to the accompanying drawings.

[0031] 1. Configuration and operation of image forming apparatus

[0032] Figure 11 is a schematic cross-sectional view of an image forming apparatus 1 according to a first exemplary embodiment. The image forming apparatus 1 according to the present exemplary embodiment is a tandem type multifunction peripheral (including the functions of a copier, printer, and facsimile apparatus) that adopts an intermediate transfer system and can form a full-color image using an electrophotographic system.

[0033] like Figure 1 As shown in FIG. 1 , the image forming apparatus 1 includes an apparatus body 10, a reading device 80, a feeding unit 90, an image forming unit 40, a discharge unit 48, a control unit 30, and an operation unit 70. A temperature sensor 71 ( Figure 2 ) and a humidity sensor 72 ( Figure 2 ) is provided inside the apparatus body 10. The image forming apparatus 1 can be configured to receive data from the reading device 80 or the external device (external device) 200 ( Figure 2 ) forms a full-color (four-color) image onto a recording material (sheet, transfer material, or recording medium) S using image information (image signals) of the external device 200. Examples of the external device 200 include a host device such as a personal computer, a digital camera, and a smart phone. The recording material S is a recording material on which a toner image is to be formed. Specific examples include plain paper, a synthetic resin sheet that replaces plain paper, thick paper, and an overhead projector sheet.

[0034] The image forming unit 40 can form an image onto the recording material S fed from the feeding unit (feeding device) 90 based on the image information. The image forming unit 40 includes image forming units 50y, 50m, 50c and 50k, toner bottles 41y, 41m, 41c and 41k, exposure devices 42y, 42m, 42c and 42k, an intermediate transfer unit 44, a secondary transfer device 45, and a fixing unit 46. The image forming units 50y, 50m, 50c and 50k form yellow (Y), magenta (M), cyan (C) and black (K) images, respectively. Components having the same or corresponding functions or configurations provided in association with these four image forming units 50y, 50m, 50c and 50k will sometimes be described collectively, omitting the letters y, m, c and k added to the end of the reference numerals to indicate the colors of the components. The image forming apparatus 1 can also form a monochrome image such as a black image or a multi-color image using a desired single image forming unit 50 or several image forming units 50 .

[0035] The image forming unit 50 includes the following components. First, the image forming unit 50 includes a photosensitive drum 51 used as an image bearing member, which is a drum-shaped (cylindrical) photosensitive member (electrophotographic photosensitive member). The image forming unit 50 also includes a charging roller 52 used as a charging unit, which is a roller-shaped charging member. The image forming unit 50 also includes a developing device 20 used as a developing unit. The image forming unit 50 also includes a pre-exposure device 54 used as a charge removal unit. The image forming unit 50 also includes a drum cleaning device 55 used as a photosensitive member cleaning unit. The image forming unit 50 forms a toner image onto the intermediate transfer belt 44b to be described below. The image forming unit 50 is integrally formed as a process cartridge and is detachably attached to the device body 10.

[0036] The photosensitive drum 51 can move (rotate) while carrying an electrostatic image (electrostatic latent image) or a toner image. In the present exemplary embodiment, the photosensitive drum 51 is a negatively charged organic photoconductor (OPC) having an outer diameter of 30 mm. The photosensitive drum 51 includes an aluminum cylinder serving as a base member and a surface layer formed on the surface of the aluminum cylinder. In the present exemplary embodiment, the photosensitive drum 51 includes three layers as the surface layer. The three layers include a primer layer, a photocharge generating layer, and a charge transporting layer sequentially coated and stacked on the base member. If the image forming operation starts, the photosensitive drum 51 rotates at a predetermined process speed (peripheral speed). Figure 1 The motor (not shown) serving as a driving unit is rotationally driven in the direction indicated by the center arrow (counterclockwise direction).

[0037] The surface of the rotating photosensitive drum 51 is uniformly charged to a predetermined potential of a predetermined polarity (negative polarity in the present exemplary embodiment) by the charging roller 52. In the present exemplary embodiment, the charging roller 52 is a rubber roller that contacts the surface of the photosensitive drum 51 and is driven to rotate according to the rotation of the photosensitive drum 51. The charging power source 73 ( Figure 2 ) is connected to the charging roller 52. The charging power source 73 applies a predetermined charging voltage (charging bias) to the charging roller 52 in a charging process.

[0038] The charged surface of the photosensitive drum 51 is subjected to scanning exposure performed by the exposure device 42 based on the image information, and an electrostatic image is formed on the photosensitive drum 51. In the present exemplary embodiment, the exposure device 42 is a laser scanner. The exposure device 42 emits laser light according to the image information of the decomposed colors output from the control unit 30, and performs scanning exposure of the surface (peripheral surface) of the photosensitive drum 51.

[0039] The electrostatic image formed on the photosensitive drum 51 is developed (visualized) by supplying toner from the developing device 20, and the toner image is formed on the photosensitive drum 51. In the present exemplary embodiment, the developing device 20 stores a two-component developer containing non-magnetic toner particles (toner) and magnetic carrier particles (carrier) as a developer. Toner is supplied to the developing device 20 from a toner bottle 41. The developing device 20 includes a developing sleeve 24. The developing sleeve 24 is formed of a non-magnetic material such as aluminum or non-magnetic stainless steel (aluminum in the present exemplary embodiment). A magnetic roller, which is a roller-shaped magnet, is fixedly arranged inside the developing sleeve 24 in such a manner that it does not rotate relative to the main body (developing container) of the developing device 20. The developing sleeve 24 carries the developer and conveys the developer to a developing area facing the photosensitive drum 51. A developing power source 74 ( Figure 2 ) is connected to the developing sleeve 24. The developing power source 74 applies a predetermined developing voltage (developing bias) to the developing sleeve 24 in the developing process. In the present exemplary embodiment, the toner charged to the same polarity as the charging polarity of the photosensitive drum 51 (negative polarity in the present exemplary embodiment) adheres to the exposed portion (image portion) of the photosensitive drum 51 where the absolute value of the potential decreases due to exposure after uniform charging (reversal development). In the present exemplary embodiment, the normal charging polarity of the toner as the charging polarity of the toner in development is negative polarity.

[0040] The intermediate transfer unit 44 is arranged to face the four photosensitive drums 51y, 51m, 51c and 51k. The intermediate transfer unit 44 includes an intermediate transfer belt 44b used as an intermediate transfer member, which is an endless belt. The intermediate transfer belt 44b is stretched with a predetermined tension by winding around a driving roller 44a, a driven roller 44d and a secondary transfer inner roller 45a used as a plurality of tension rollers (support rollers). The intermediate transfer belt 44b can move (rotate) while carrying a toner image. The driving roller 44a is rotationally driven by a motor (not shown) used as a driving unit. The driven roller 44d is a tension roller that controls the tension of the intermediate transfer belt 44b to be constant. The driven roller 44d adds a force for pushing the intermediate transfer belt 44b from the inner peripheral side to the outer peripheral side by the urging force of a tension spring (not shown) (which is a urging member) as a urging unit. By this force, a tension of about 2 to 5 kg is applied in the conveying direction of the intermediate transfer belt 44b. The secondary transfer inner roller 45a constitutes the secondary transfer device 45 as described below. By the driving roller 44a being rotationally driven, the driving force is input to the intermediate transfer belt 44b, and the intermediate transfer belt 44b is rotated at a predetermined peripheral speed corresponding to the peripheral speed of the photosensitive drum 51. Figure 1The intermediate transfer belt 44b rotates (revolves) in the direction indicated by the arrow (clockwise). On the inner peripheral side of the intermediate transfer belt 44b, primary transfer rollers 47y, 47m, 47c and 47k, each of which is a roller-shaped primary transfer member and serves as a primary transfer unit, are arranged to face the corresponding photosensitive drums 51y, 51m, 51c and 51k. The primary transfer roller 47 sandwiches the intermediate transfer belt 44b with the photosensitive drum 51. The primary transfer roller 47 thus contacts the photosensitive drum 51 via the intermediate transfer belt 44b, and forms a primary transfer portion (primary transfer sandwich portion) N1 where the photosensitive drum 51 and the intermediate transfer belt 44b contact.

[0041] The toner image formed on the photosensitive drum 51 is primarily transferred to the rotating intermediate transfer belt 44b at the primary transfer portion N1. Figure 2 ) is connected to the primary transfer roller 47. The primary transfer power source 75 applies a primary transfer voltage (primary transfer bias) to the primary transfer roller 47 in the primary transfer process, and the primary transfer voltage (primary transfer bias) is a DC voltage having a polarity opposite to the normal charging polarity of the toner (positive polarity in the present exemplary embodiment). For example, when a full-color image is to be formed, the yellow, magenta, cyan, and black toner images formed on the corresponding photosensitive drums 51y, 51m, 51c, and 51k are sequentially primary-transferred onto the intermediate transfer belt 44b in an overlapping manner. A voltage detection sensor 75a that detects an output voltage and a current detection sensor 75b that detects an output current are connected to the primary transfer power source 75 ( Figure 2 In the present exemplary embodiment, primary transfer power supplies 75y, 75m, 75c, and 75k are provided to the respective primary transfer rollers 47y, 47m, 47c, and 47k, and primary transfer voltages to be applied to the primary transfer rollers 47y, 47m, 47c, and 47k can be individually controlled.

[0042] In the present exemplary embodiment, the primary transfer roller 47 includes an elastic layer made of ion-conductive foam rubber (nitrile rubber (NBR)), and a metal core. The outer diameter of the primary transfer roller 47 is, for example, 15 to 20 mm. As the primary transfer roller 47, a material having a resistance value of 1×10 5 Up to 1×10 8Ω (measured in N / N (23°C, 50% RH), 2 kV applied) of the roller. In the present exemplary embodiment, the intermediate transfer belt 44b is an endless belt having a three-layer structure including a base layer, an elastic layer, and a surface layer in order from the inner peripheral side to the outer peripheral side. As a material for the base layer, a material obtained by mixing an appropriate amount of carbon black as an antistatic agent into a resin such as polyimide or polycarbonate or various types of rubber can be desirably used. The thickness of the base layer is, for example, 0.05 to 0.15 mm. As an elastic material for the elastic layer, a material obtained by mixing an appropriate amount of an ion conductor into various types of rubber such as polyurethane rubber or silicone rubber can be desirably used. The thickness of the elastic layer is, for example, 0.1 to 0.500 mm. As a material for the surface layer, a resin such as a fluororesin can be desirably used. The surface layer reduces the adhesion of toner to the surface of the intermediate transfer belt 44b, and allows the toner to be easily transferred to the recording material S at the secondary transfer portion N2 to be described below. The thickness of the surface layer is, for example, 0.0002 to 0.020 mm. In the present exemplary embodiment, the surface layer uses one type of resin material (such as polyurethane, polyester, or epoxy resin) or two or more types of materials among elastic materials (such as elastic rubber, elastomer, and butyl rubber) as a base material. Then, the surface layer is formed by dispersing one type or two or more types of powder or particles of fluororesin or the like, or particles with different particle sizes in the base material as a material for reducing surface energy and increasing lubricity. In the present exemplary embodiment, the volume resistivity of the intermediate transfer belt 44b is 5×10 8 Up to 1×10 14 Ω·cm (23°C, 50%RH), and the hardness is 60 to 85° (23°C, 50%RH) measured by MD1. In the present exemplary embodiment, the static friction coefficient of the intermediate transfer belt 44b is 0.15 to 0.6 (23°C, 50%RH, measured by type94i manufactured by HEIDON). In the present exemplary embodiment, the intermediate transfer belt 44b has a three-layer structure. For example, the intermediate transfer belt 44b may have a single-layer structure including, for example, a material equivalent to the material of the above-mentioned base layer.

[0043] On the outer peripheral side of the intermediate transfer belt 44b, a secondary transfer outer roller 45b serving as a secondary transfer unit, which constitutes the secondary transfer device 45 together with the secondary transfer inner roller 45a, is arranged, and the secondary transfer outer roller 45b is a roller-shaped secondary transfer member. The secondary transfer outer roller 45b sandwiches the intermediate transfer belt 44b with the secondary transfer inner roller 45a. The secondary transfer outer roller 45b thus contacts the secondary transfer inner roller 45a via the intermediate transfer belt 44b, and forms a secondary transfer portion (secondary transfer sandwiching portion) N2 where the intermediate transfer belt 44b and the secondary transfer outer roller 45b contact. At the secondary transfer portion N2, the toner image formed on the intermediate transfer belt 44b is secondarily transferred onto the recording material S conveyed while being sandwiched by the intermediate transfer belt 44b and the secondary transfer outer roller 45b. In the present exemplary embodiment, a secondary transfer voltage (secondary transfer bias) is applied to the secondary transfer outer roller 45b in the secondary transfer process.

[0044] In this manner, in the present exemplary embodiment, the secondary transfer device 45 includes a secondary transfer inner roller 45a serving as a facing member and a secondary transfer outer roller 45b serving as a secondary transfer member. The secondary transfer inner roller 45a is arranged to face the secondary transfer outer roller 45b via the intermediate transfer belt 44b. The secondary transfer power source 76 ( Figure 2 ) is connected to the secondary transfer outer roller 45b. The secondary transfer power source 76 applies a secondary transfer voltage (secondary transfer bias) which is a DC voltage having a polarity opposite to the normal charging polarity of the toner (positive polarity in the present exemplary embodiment) to the secondary transfer outer roller 45b in the secondary transfer process. A voltage detection sensor 76a that detects an output voltage and a current detection sensor 76b that detects an output current are connected to the secondary transfer power source 76 ( Figure 2). In the present exemplary embodiment, the metal core of the secondary transfer inner roller 45a is connected to the ground potential. In other words, in the present exemplary embodiment, the secondary transfer inner roller 45a is electrically grounded (connected to the ground). Then, when the recording material S is supplied to the secondary transfer portion N2, a secondary transfer voltage under constant voltage control and having a polarity opposite to the conventional charging polarity of the toner is applied to the secondary transfer outer roller 45b. In the present exemplary embodiment, for example, a secondary transfer voltage of 1 to 7 kV is applied, and a current of 40 to 120 μA flows, so that the toner image on the intermediate transfer belt 44b is secondarily transferred to the recording material S. In the present exemplary embodiment, a DC voltage is applied to the secondary transfer outer roller 45b by the secondary transfer power supply 76, and the secondary transfer voltage is applied to the secondary transfer portion N2, but the present disclosure is not limited to this configuration. For example, a DC voltage is applied to the secondary transfer inner roller 45a by the secondary transfer power supply 76, and the secondary transfer voltage can be applied to the secondary transfer portion N2. In this case, a DC voltage having the same polarity as the conventional charging polarity of the toner is applied to the secondary transfer inner roller 45a serving as the secondary transfer member, and the secondary transfer outer roller 45b serving as the counter member is electrically grounded. In the present exemplary embodiment, the secondary transfer outer roller 45b includes an elastic layer made of ion conductive foam rubber (NBR), and a metal core. The outer diameter of the secondary transfer outer roller 45b is, for example, 20 to 25 mm. As the secondary transfer outer roller 45b, a 1×10 5 Up to 1×10 8 Ω (measured in N / N (23°C, 50% RH), 2 kV applied) of the roller.

[0045] Concurrently with the above-mentioned toner image forming operation, the recording material S is fed from the feeding unit 90. More specifically, the recording material S is stacked and stored in a recording material box 91 serving as a recording material storage unit. The recording material S stored in the recording material box 91 is fed to a conveying path 93 by a feeding roller 92 serving as a feeding member. The recording material S fed to the conveying path 93 is conveyed to the registration roller pair 43 serving as a conveying member by a conveying roller pair 94 serving as a conveying member. The skew of the recording material S is corrected by the registration roller pair 43, and the recording material S is supplied to the secondary transfer portion N2 in synchronization with the toner image on the intermediate transfer belt 44b. The feeding unit 90 includes a recording material box 91, a feeding roller 92, a conveying path 93, and a conveying roller pair 94.

[0046] The recording material S on which the toner image is transferred is conveyed to a fixing unit (fixing device) 46. The fixing unit 46 includes a fixing roller 46a and a pressure roller 46b. The fixing roller 46a includes a built-in heater serving as a heating unit. The recording material S carrying the unfixed toner image is conveyed while being sandwiched between the fixing roller 46a and the pressure roller 46b. Heat and pressure are thereby applied to the recording material S. The toner image is thus fixed (melted, bonded) to the recording material S. The temperature (fixing temperature) of the fixing roller 46a is detected by a fixing temperature sensor 77 ( Figure 2 ) detection.

[0047] The recording material S to which the toner image is fixed is conveyed on the discharge path 48a by the discharge roller pair 48b serving as a conveying member, discharged (output) from the discharge port 48c, and stacked on the discharge tray 48d provided outside the apparatus body 10. The discharge unit (discharge device) 48 includes the discharge path 48a, the discharge roller pair 48b, the discharge port 48c, and the discharge tray 48d. In the present exemplary embodiment, the image forming apparatus 1 can perform double-sided image formation (double-sided printing, automatic double-sided printing) in which images are formed on both surfaces of the recording material S. A reverse conveying path 12 for reversing the recording material S to which the toner image has been fixed on the first surface and supplying the recording material S to the secondary transfer portion N2 again is provided between the fixing unit 46 and the discharge port 48c. In the double-sided image formation, the recording material S to which the toner image has been fixed on the first surface is guided to the reverse conveying path 12. The conveying direction of the recording material S is reversed by the turn roller pair 13 provided on the reverse conveying path 12, and the recording material S is guided to the double-sided conveying path 14. Then, the recording material S is fed to the conveying path 93 by the re-conveying roller pair 15 provided on the double-sided conveying path 14, is conveyed until the registration roller pair 43, and is supplied to the secondary transfer portion N2 by the registration roller pair 43. Thereafter, similarly to the toner image formed on the first surface, the toner image is secondarily transferred onto the second surface of the recording material S. After the transferred toner image is fixed, the recording material S is discharged to the discharge tray 48d. The double-sided conveying unit (double-sided conveying device) 11 includes a reverse conveying path 12, a steering roller pair 13, a double-sided conveying path 14, and a re-conveying roller pair 15. By the operation of the double-sided conveying unit 11, images can be formed on both surfaces of one recording material S.

[0048] The charge on the surface of the photosensitive drum 51 that has been subjected to the primary transfer is removed by the pre-exposure device 54. Adherents such as toner (primary transfer residual toner) that remain on the photosensitive drum 51 without being transferred to the intermediate transfer belt 44b in the primary transfer process are removed from the surface of the photosensitive drum 51 and collected by the drum cleaning device 55. The drum cleaning device 55 scrapes off the attached matter from the surface of the rotating photosensitive drum 51 using a cleaning blade serving as a cleaning member that contacts the surface of the photosensitive drum 51, and stores the attached matter in a cleaning container. The cleaning blade contacts the surface of the photosensitive drum 51 by a predetermined pressing force in such a manner that its leading end on the free end side is oriented in the opposing direction to face the upstream side in the rotation direction of the photosensitive drum 51. The intermediate transfer unit 44 includes a belt cleaning device 60 serving as an intermediate transfer member cleaning unit. Adherent matter such as toner (secondary transfer residual toner) that remains on the intermediate transfer belt 44 b without being transferred onto the recording material S in the secondary transfer process is removed from the surface of the intermediate transfer belt 44 b and collected by the belt cleaning device 60 .

[0049] A reading device 80 serving as a reading means (reading unit) is arranged in an upper portion of the apparatus body 10. The reading device 80 includes an automatic document transport device (automatic document feeder (ADF)) 81 serving as a document transport means (document transport unit), a platen glass 82, an optical system 84 including a light source 83, a reflection mirror 84a and an image forming lens 84b, and a reading element 85 such as a charge coupled device (CCD) image sensor.

[0050] In the present exemplary embodiment, the reading device 80 can sequentially read the image on the document (recording material S on which an image is formed) arranged on the platen glass 82 through the optical system 84 by the reading element 85 while performing scanning exposure using the movable light source 83. In this case, the reading device 80 sequentially illuminates the document arranged on the platen glass 82 with the light from the movable light source 83, and sequentially forms an optical image onto the reading element 85 via the optical system 84 based on the reflected light from the document. The reading element 85 can thereby read the image on the document at a predefined dot density. The platen glass 82 forms a reading surface that supports the recording material S in such a manner that the reading device 80 can read the recording material S.

[0051] In the present exemplary embodiment, the reading device 80 can sequentially read the image on the document conveyed by the automatic document conveying device 81 by the reading element 85 via the optical system 84 by sequentially exposing the document using the light source 83 according to the conveyance of the document. In this case, the reading device 80 sequentially illuminates the document passing through the predetermined reading position on the platen glass 82 using the light from the light source 83, and sequentially forms an optical image onto the reading element 85 via the optical system 84 based on the reflected light from the document. The reading element 85 can thereby read the image on the document at a predefined dot density. The automatic document conveying device 81 automatically conveys the documents one by one in a separated state in such a manner that the document passes through the above-mentioned reading position of the reading device 80. The automatic document conveying device 81 forms a conveying device that sequentially conveys the recording material S in such a manner that the reading device 80 can read the recording material S.

[0052] In this manner, the reading device 80 optically reads an image on the recording material S placed on the platen glass 82 or conveyed by the automatic document conveying device 81 , and converts the read image into an electric signal.

[0053] In the present exemplary embodiment, the reading device 80 can arrange one recording material S having a large size such as A3 size, or two recording materials S having a small size such as A4 size side by side on the platen glass 82. In the present exemplary embodiment, the reading device 80 can continuously convey a plurality of recording materials S having, for example, A3 size or A4 size stacked on the document stacking portion of the automatic document conveying device 81 to the above-mentioned reading position. The automatic document conveying device 81 can automatically read images on both surfaces of the recording material S.

[0054] For example, in the case where the image forming apparatus 1 operates as a copier, the image on the document read by the reading device 80 is transmitted to the image processing unit of the control unit 30 as three-color image data corresponding to, for example, red (R), green (G), and blue (B) (8 bits for each color). In the image processing unit, predetermined image processing is performed on the image data of the document when necessary, and the image data is converted into image data of four colors including yellow, magenta, cyan, and black. Examples of the above-mentioned image processing include shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, and color / movement editing. The image data corresponding to the four colors including yellow, magenta, cyan, and black are sequentially transmitted to the corresponding exposure devices 42y, 42m, 42c, and 42k, and the above-mentioned image exposure is performed according to the image data. The reading device 80 is also used to read the color blocks on the chart (obtain density information (brightness information)) in the adjustment mode as described in detail below.

[0055] Figure 21 is a block diagram schematically illustrating a configuration of a control system of the image forming apparatus 1 according to the present exemplary embodiment. Figure 2 As shown in , the control unit 30 is formed by a computer. The control unit 30 includes, for example, a central processing unit (CPU) 31 used as a calculation control unit, a read-only memory (ROM) 32 used as a storage unit and storing a program for controlling each component, a random access memory (RAM) 33 used as a storage unit and temporarily storing data, and an input-output circuit (interface (I / F)) 34 for inputting signals from the outside and outputting signals to the outside. The CPU 31 is a microprocessor that manages the overall control of the image forming device 1, and mainly constitutes a system controller. The CPU 31 is connected to the feeding unit 90, the image forming unit 40, the discharge unit 48, and the operation unit 70 via the input-output circuit 34, and exchanges signals with these components and controls the operations of these components. The ROM 32 stores an image formation control sequence for forming an image onto the recording material S. A charging power source 73, a developing power source 74, a primary transfer power source 75, and a secondary transfer power source 76 are connected to the control unit 30, and these components are controlled according to signals from the control unit 30. A temperature sensor 71, a humidity sensor 72, a voltage detection sensor 75a and a current detection sensor 75b of a primary transfer power source 75, a voltage detection sensor 76a and a current detection sensor 76b of a secondary transfer power source 76, and a fixing temperature sensor 77 are also connected to the control unit 30. A signal detected by each sensor is input to the control unit 30.

[0056] The operation unit 70 includes an input unit such as an operation button used as an input unit, and a display unit 70a including a liquid crystal panel used as a display unit. In the present exemplary embodiment, the display unit 70a is formed as a touch panel, and also has a function as an input unit. By operating the operation unit 70, an operator such as a user or a service person can perform a job (to be described below). The control unit 30 operates various devices of the image forming apparatus 1 upon receiving a signal from the operation unit 70. The image forming apparatus 1 can also perform a job based on an image forming signal (image data, control command) from an external device 200 such as a personal computer.

[0057] In the present exemplary embodiment, the control unit 30 includes an image formation preliminary preparation processing unit 31a, an active transfer voltage control (ATVC) processing unit 31b, an image formation processing unit 31c, and an adjustment processing unit 31d. The control unit 30 also includes a primary transfer voltage storage unit / calculation unit 31e and a secondary transfer voltage storage unit / calculation unit 31f. These processing units and storage units / calculation units can be provided as a part of the CPU 31 or the RAM 33. For example, the control unit 30 (more specifically, the image formation processing unit 31c) can perform the operation as described above. In addition, the control unit 30 (more specifically, the ATVC processing unit 31b) can perform ATVC (setting mode) of the primary transfer part and the secondary transfer part. ATVC will be described in detail below. In addition, the control unit 30 (more specifically, the adjustment processing unit 31d) can perform an adjustment mode for adjusting the setting voltage of the secondary transfer voltage. The adjustment mode will be described in detail below.

[0058] The image forming device 1 performs a job (image output operation, print job) started according to a start instruction, and the job (image output operation, print job) is a series of operations of forming an image onto one or more recording materials S and outputting the recording materials S. The job generally includes an image forming process, a preliminary rotation process, a sheet-to-sheet interval process in the case of forming an image onto a plurality of recording materials S, and a post-rotation process. The image forming process corresponds to a period of time for forming an electrostatic image to form a toner image and performing a primary transfer and a secondary transfer of the toner image by forming an image to be actually outputted on the recording material S. The image forming state (image forming period) refers to this period. More specifically, the timing of the image forming state varies according to the position where these processes including the formation of an electrostatic image, the formation of a toner image, and the primary transfer and the secondary transfer of the toner image are performed. The preliminary rotation process corresponds to a period of time for performing a preparatory operation before the image forming process, and corresponds to a period of time from the input of the start instruction until the image formation actually starts. The sheet-to-sheet interval processing corresponds to a period corresponding to the interval between recording materials S and recording materials S in performing image formation on a plurality of recording materials S continuously (continuous image formation). The post-rotation processing corresponds to a period for performing an arrangement operation (preparation operation) after the image formation processing. The non-image forming state (non-image forming period) corresponds to a period other than the image forming state, and includes the above-mentioned preliminary rotation processing, the sheet-to-sheet interval processing, and the post-rotation processing. The non-image forming state also includes a preliminary multi-rotation processing, which is a preparation operation to be performed when the power of the image forming apparatus 1 is turned on or when the image forming apparatus 1 is restored from a sleep state.

[0059] 2. Control of secondary transfer voltage

[0060] Next, control of the secondary transfer voltage will be described. Figure 3 2 is a flowchart schematically illustrating a process of controlling a secondary transfer voltage according to the present exemplary embodiment. The control of the secondary transfer voltage generally includes constant voltage control and constant current control. In the present exemplary embodiment, constant voltage control is used.

[0061] First, in step S101, the control unit 30 (image formation preliminary preparation processing unit 31a) starts the operation of the job when acquiring the job information from the operation unit 70 or the external device 200. The job information includes image information specified by the operator and information about the recording material S. The information about the recording material S may include the size (width, length) of the recording material S on which the image is to be formed, information related to the thickness of the recording material S (thickness, grammage, etc.), and information related to the surface properties of the recording material S (such as information indicating whether the recording material S is coated paper). In particular, in the present exemplary embodiment, the information about the recording material S includes information about the size of the recording material S, and information about the category (so-called paper type category) of the recording material S (such as "thin paper, ordinary paper, thick paper, etc." related to the thickness of the recording material S). The information about the recording material S (recording material information) covers any information that can identify the recording material S, such as attributes based on general characteristics (so-called paper type categories) (including plain paper, high-quality paper, glazed paper, glossy paper, coated paper, embossed paper, thick paper, and thin paper), numerical values ​​or numerical ranges of grammage, thickness, size, and rigidity, or brands (including manufacturers, product names, product numbers). The recording material S can be classified by the type identified based on the information about the recording material S. The information about the recording material S may be included in the information about the print mode (such as "plain paper mode" and "thick paper mode") that specifies the operation settings of the image forming device 1, or may be replaced by the information about the print mode. In step S102, the control unit 30 writes the job information into the RAM 33.

[0062] Next, in step S103, the control unit 30 acquires environmental information detected by the temperature sensor 71 and the humidity sensor 72. The ROM 32 stores information indicating the correlation between the environmental information and the target current Itarget for transferring the toner image on the intermediate transfer belt 44b to the recording material S. Based on the environmental information read in step S103, the control unit 30 (secondary transfer voltage storage unit / calculation unit 31f) obtains the target current Itarget suitable for the environment from the above-mentioned information indicating the relationship between the environmental information and the target current Itarget. Then, in step S104, the control unit 30 writes the target current Itarget into the RAM 33 (or the secondary transfer voltage storage unit / calculation unit 31f). Because the charge amount of the toner varies depending on the environment, the target current Itarget varies according to the environmental information.

[0063] The above-mentioned information indicating the relationship between the environmental information and the target current Itarget is information preliminarily obtained through experiments.

[0064] Next, in step S105, the control unit 30 (ATVC processing unit 31b) acquires information about the resistance of the secondary transfer portion N2 by ATVC before the toner image on the intermediate transfer belt 44b and the recording material S on which the toner image is to be transferred arrive at the secondary transfer portion N2. In other words, a plurality of levels of predetermined voltages are supplied from the secondary transfer power supply 76 to the secondary transfer outer roller 45b in a state where the secondary transfer outer roller 45b and the intermediate transfer belt 44b are in contact. Then, the current value obtained when the predetermined voltage is supplied is detected by the current detection sensor 76b, and the information is acquired as follows. Figure 4 The control unit 30 writes information indicating the relationship between the voltage and the current into the RAM 33 (or the secondary transfer voltage storage unit / calculation unit 31f). The relationship between the voltage and the current changes according to the resistance of the secondary transfer portion N2. In the above-mentioned relationship between the voltage and the current in the configuration according to the present exemplary embodiment, the current changes as represented by a second-order or higher-order polynomial expression of the voltage (a quadratic expression in the present exemplary embodiment), and does not change linearly with respect to the voltage (in proportion to the voltage). Therefore, in the present exemplary embodiment, when obtaining information about the resistance of the secondary transfer portion N2, three or more levels of predetermined voltage or current are supplied in such a manner that the above-mentioned relationship between the voltage and the current can be represented by a polynomial expression.

[0065] Next, in step S106, the control unit 30 (secondary transfer voltage storage unit / calculation unit 31f) obtains the value of the voltage to be applied to the secondary transfer outer roller 45b from the secondary transfer power source 76. In other words, based on the target current Itarget written to the RAM 33 in step S104 and the relationship between the voltage and the current obtained in step S105, the control unit 30 obtains the value of the voltage Vb necessary to make the target current Itarget flow in a state where the recording material S is not present at the secondary transfer portion N2. The voltage Vb corresponds to the secondary transfer portion voltage division (the transfer voltage corresponding to the resistance of the secondary transfer portion N2). As shown in FIG. Figure 5 As shown in , ROM 32 stores information for obtaining the recording material partial pressure (transfer voltage corresponding to the resistance of the recording material S) Vp. In the present exemplary embodiment, the information is set to table data indicating the relationship between the moisture amount of the atmosphere for each group of grammage (corresponding to the paper type category) of the recording material S and the recording material partial pressure Vp. The control unit 30 can obtain the moisture amount of the atmosphere based on the environmental information (temperature and humidity) detected by the temperature sensor 71 and the humidity sensor 72. The control unit 30 (secondary transfer voltage storage unit / calculation unit 31f) obtains the recording material partial pressure Vp from the above table data based on the job information obtained in step S101 and the environmental information obtained in step S103. In the case of setting the adjustment value by the adjustment mode for adjusting the setting voltage of the secondary transfer voltage described below, the control unit 30 (secondary transfer voltage storage unit / calculation unit 31f) obtains the adjustment amount ΔV according to the adjustment value. As described below, in the case of setting the adjustment amount ΔV by the adjustment mode, the adjustment amount ΔV is stored in RAM 33 (or secondary transfer voltage storage unit / calculation unit 31f). The control unit 30 obtains a value Vb+Vp+ΔV as a secondary transfer voltage Vtr to be applied from the secondary transfer power source 76 to the secondary transfer outer roller 45b when the recording material S passes through the secondary transfer portion N2 by adding the above-mentioned voltages Vb and Vp and the adjustment amount ΔV. Then, the control unit 30 writes the secondary transfer voltage Vtr (=Vb+Vp+ΔV) into the RAM 33 (or the secondary transfer voltage storage unit / calculation unit 31f). Figure 5 The tabular data shown in for obtaining the recording material partial pressure Vp are data preliminarily obtained through experiments.

[0066] In some cases, in addition to the information related to the thickness of the recording material S (thickness, grammage, etc.), the recording material partial pressure Vp also changes according to the surface properties of the recording material S. Therefore, the above-mentioned table data may be set in such a manner that the recording material partial pressure Vp also changes according to the information related to the surface properties of the recording material S. In the present exemplary embodiment, the information related to the thickness of the recording material S (in addition, the information related to the surface properties of the recording material S) is included in the job information acquired in step S101. However, the image forming apparatus 1 may be provided with a measuring unit that detects the thickness of the recording material S or the surface properties of the recording material S, and the recording material partial pressure Vp may be obtained based on the information obtained by the measuring unit.

[0067] Next, in step S107, the control unit 30 (image forming processing unit 31c) causes image formation to be performed, and causes secondary transfer to be performed by feeding the recording material S to the secondary transfer portion N2 and applying the secondary transfer voltage Vtr determined as described above. Thereafter, in step S108, the control unit 30 (image forming processing unit 31c) repeats the processing in step S107 until all images of the job are transferred onto the recording material S and the output ends.

[0068] ATVC similar to the above-described control is performed on the primary transfer portion N1 during a period from the start of the job until the toner image is conveyed to the primary transfer portion N1 , but a detailed description will be omitted.

[0069] 3. Overview of adjustment mode

[0070] Next, an adjustment mode (simple adjustment mode) for adjusting the setting voltage of the secondary transfer voltage will be described.

[0071] Depending on the type or state of the recording material S to be used in image formation, the moisture content or resistance value of the recording material S is sometimes significantly different from the moisture content or resistance value of the standard recording material S. In this case, the setting voltage of the secondary transfer voltage set by using the preset default recording material partial pressure Vp as described above sometimes fails to perform optimal transfer. In other words, the secondary transfer voltage will initially be set to the voltage required to transfer the colorant on the intermediate transfer belt 44b to the recording material S. In addition, the secondary transfer voltage will be suppressed to a voltage at which abnormal discharge does not occur. However, depending on the type or state of the recording material S to be actually used in image formation, the resistance is sometimes higher than the value expected as the standard value. In this case, as the voltage required for transferring the colorant on the intermediate transfer belt 44b to the recording material S, the setting voltage of the secondary transfer voltage set using the preset default recording material partial pressure Vp sometimes becomes insufficient. Therefore, in this case, it is necessary to increase the setting voltage of the secondary transfer voltage by increasing the recording material partial pressure Vp. On the contrary, depending on the type or state of the recording material S to be actually used in image formation, due to the increase in the moisture content of the recording material S, the resistance is sometimes lower than the value desired as the standard value, and discharge sometimes easily occurs. In this case, the setting voltage of the secondary transfer voltage set using the preset default recording material partial voltage Vp sometimes causes image defects due to abnormal discharge. Therefore, in this case, it is necessary to reduce the setting voltage of the secondary transfer voltage by reducing the recording material partial voltage Vp.

[0072] Therefore, it is sometimes necessary for an operator such as a user or a service person to adjust (change) the set voltage of the secondary transfer voltage in job execution to an optimal value by adjusting (changing) the recording material partial pressure Vp according to the recording material S to be actually used in image formation. In other words, it is sometimes necessary to select an optimal recording material partial pressure Vp+ΔV (adjustment amount) suitable for the recording material S to be actually used in image formation. It is also considered to perform adjustment by the following method.

[0073] More specifically, for example, this method is a method of determining the setting voltage of the optimum secondary transfer voltage (more specifically, the recording material partial voltage Vp+ΔV) by the operator outputting an image desired to be output, switching the secondary transfer voltage for one recording material S at the same time, and checking the output image. However, in this method, since the image output and the adjustment of the setting voltage of the secondary transfer voltage are repeated, in some cases, the amount of the wasted recording material S increases, and the adjustment takes time.

[0074] In view of the foregoing, the image forming apparatus 1 according to the present exemplary embodiment includes an adjustment mode for adjusting the setting voltage of the secondary transfer voltage. In this adjustment mode, the image forming apparatus 1 outputs a chart including a plurality of color patches (test images) of representative colors formed on a recording material S to be actually used in image formation, while switching the setting voltage of the secondary transfer voltage for each color patch. Then, based on the reading result of the output chart obtained by the reading device 80, the setting voltage of the optimal secondary transfer voltage (more specifically, the recording material partial voltage Vp+ΔV) can be determined. In the present exemplary embodiment, in the adjustment mode, information about the recommended adjustment amount ΔV of the setting voltage of the secondary transfer voltage is presented based on the density information (brightness information) of the color patches (usually pure image color patches) on the chart. With this configuration, it becomes possible to more appropriately adjust the setting of the secondary transfer voltage while reducing the operator's operating burden by reducing the necessity for the operator to visually check the image on the chart.

[0075] 4. Charts

[0076] Next, a chart (adjustment image, test page) to be output in the adjustment mode according to the present exemplary embodiment will be described. Fig. 6A and 6B as well as Fig. 7A , 7B 7C and 7D are schematic diagrams of the graph 100 according to the present exemplary embodiment.

[0077] In this exemplary embodiment, the graph is roughly divided into Fig. 6A and 6B ,as well as Fig. 7A , 7B , 7C and 7D, and in the adjustment mode, the two types of charts 100 are output according to the size of the recording material S to be used. Fig. 6A and 6B A chart 100 to be output in a case where the length in the conveying direction of the recording material S is 420 to 487 mm is illustrated. Fig. 7A , 7B 7C and 7D illustrate a chart 100 to be output in a case where the length in the conveying direction of the recording material S is 210 to 419 mm. In the present exemplary embodiment, the chart can also be output on both surfaces of the recording material S in the adjustment mode in such a manner that the secondary transfer voltages to be applied to the front surface (first surface) and the rear surface (second surface) in the secondary transfer in double-sided image formation can be adjusted individually. Fig. 6A and 6B as well as Fig. 7A , 7B7C and 7D illustrate a chart to be formed on one surface of the recording material S (hereinafter, also referred to as a "single-sided chart"), and a chart to be formed on both surfaces of the recording material S (hereinafter, also referred to as a "double-sided chart"). The double-sided chart is formed by double-sided image formation using the above-mentioned double-sided conveying unit 11.

[0078] The size of the recording material S is indicated by a recording material width (length in the main scanning direction)×a recording material length (length in the sub-scanning direction). The recording material width is the length in a direction substantially orthogonal to the conveyance direction of the recording material S when passing through the secondary transfer portion N2 (width direction). The recording material length is the length in a direction substantially parallel to the conveyance direction of the recording material S when passing through the secondary transfer portion N2.

[0079] Fig. 6A and 6B The diagram illustrates a chart for large-size recording material (hereinafter, also referred to as a "large chart") 100L (100La and 100Lb) to be output when using a recording material S having a large size, such as A3 size (297 mm×420 mm) or Ledger (approximately 280 mm×432 mm). Fig. 6A The large chart 100La is illustrated as being output as a single-sided chart or as the first surface of a double-sided chart. Figure 6B A large chart 100Lb output as the second surface of a double-sided chart is illustrated.

[0080] Fig. 7A , 7B , 7C and 7D illustrate charts (hereinafter also referred to as "small charts") 100S (100Sa and 100Sb) for small-size recording materials to be output when using a recording material S having a small size, such as A4 landscape (297mm×210mm) or letter landscape (approximately 280mm×216mm). Fig. 7A and 7B The small graph 100Sa output as the first surface of the first single-sided graph or the first double-sided graph, and the small graph 100Sa output as the first surface of the second single-sided graph or the second double-sided graph are respectively illustrated. Figure 7C and 7D The small graph 100Sb output as the second surface of the first double-sided graph and the small graph 100Sb output as the second surface of the second double-sided graph are respectively illustrated.

[0081] Considering the visual inspection to be performed by the operator, it is advantageous that it becomes easier to check image defects if the size of the color block on the chart to be output in the adjustment mode becomes larger. However, if the size of the color block is large, the number of color blocks that can be formed on one recording material S is reduced. A square shape can be adopted as the shape of the color block. The color of the color block can be determined based on the image defects expected to be inspected and the ease of inspection. For example, in the case where the secondary transfer voltage is increased from a low value, the lower limit value of the secondary transfer voltage can be determined based on the voltage value at which the color blocks of secondary colors (such as red, green and blue) can be properly transferred. In the case where the operator visually inspects the color blocks, in the case where the secondary transfer voltage is further increased, the upper limit value of the secondary transfer voltage can be determined based on the voltage value at which image defects occur in the halftone color blocks due to the high secondary transfer voltage.

[0082] The chart 100 includes a set of color patches, each of which includes a blue solid color patch 101, a black solid color patch 102, and two halftone color patches 103 arranged side by side in the width direction. Fig. 6A and 6B In the large chart 100L in FIG. 1 , eleven color patch sets each including color patches 101 to 103 arranged in the width direction are arranged in the conveying direction. Fig. 7A , 7B , 7C and 7D, ten color block sets each including color blocks 101 to 103 arranged in the width direction are arranged in the conveying direction. In the present exemplary embodiment, the halftone color block 103 is a gray (black halftone) color block. A pure image is an image with the highest density level. In the present exemplary embodiment, a blue pure image is obtained by overlapping magenta (M) toner = 100% and cyan (C) toner = 100%, and the toner application amount of the blue pure image is 200%. A black pure image is an image with black (K) toner = 100%. For example, when the toner application amount of the pure image is 100%, the halftone image is an image with a toner application amount of 10% to 80%. In the present exemplary embodiment, in the chart 100, color block identification information 104 for identifying the setting of the secondary transfer voltage applied to each color block set is provided in association with the corresponding set of color blocks 101 to 103. The color patch identification information 104 may be a value corresponding to an adjustment value of a secondary transfer voltage to be described below. Fig. 6A and 6B In the large graph 100L shown in FIG. 1 , eleven pieces (eleven pieces corresponding to −5 to 0 to +5 in the present exemplary embodiment) of patch identification information 104 corresponding to settings of eleven levels of secondary transfer voltage are arranged. Fig. 7A , 7BIn the small chart 100S shown in 7C and 7D, ten pieces (in the present exemplary embodiment, five pieces corresponding to -4 to 0 on the first chart and five pieces corresponding to +1 to +5 on the second chart) of patch identification information 104 corresponding to settings of ten levels of secondary transfer voltage are arranged. In the chart 100, front / rear identification information 105 indicating at least one of the front surface (first surface) or the rear surface (second surface) of the recording material S may be provided on at least one of the front surface (first surface) or the rear surface (second surface) of the recording material S.

[0083] The color patch desirably has a size that enables an operator to easily determine the presence or absence of an image defect. If the size of the color patch is small, it tends to become difficult to determine the transferability of the blue solid color patch 101 and the black solid color patch 102. Therefore, the size of the color patch is desirably set to a size equal to or larger than a size of 10 mm×10 mm, and more desirably set to a size equal to or larger than a size of 25 mm×25 mm.

[0084] Image defects in the halftone color block 103 caused by discharge occurring when the secondary transfer voltage is increased often become image defects like white spots. Compared with the transferability of a pure image, image defects tend to be easily determined even in a small image. However, for the sake of visualization, it is best to avoid too small an image. Therefore, in the present exemplary embodiment, the width of the halftone color block 103 in the conveying direction is set to be the same width as the width of the blue solid color block 101 and the black solid color block 102 in the conveying direction. It is only necessary to set the interval between the color block sets each including the color blocks 101 to 103 arranged in the conveying direction in such a manner that the secondary transfer voltage can be switched. In the present exemplary embodiment, the blue solid color block 101 and the black solid color block 102 are squares each having a size of 25.7 mm×25.7 mm (one side is substantially parallel to the width direction). In the present exemplary embodiment, the halftone color blocks 103 at both ends in the width direction each have a width of 25.7 mm in the conveying direction and extend all the way to the end of the chart 100 in the width direction. In the present exemplary embodiment, the interval in the conveying direction between the color block sets each including the color blocks 101 to 103 is set to 9.5 mm. At the timing when the portion corresponding to the interval on the chart 100 passes through the secondary transfer portion N2, the secondary transfer voltage is switched. In the present exemplary embodiment, using a plurality of secondary transfer voltages (test voltages) that change to have successively increasing absolute values, the color block sets each including the color blocks 101 to 103 formed on the chart 100 are sequentially transferred from the upstream side toward the downstream side in the conveying direction of the recording material S when the chart 100 is formed. However, the present disclosure is not limited to this configuration. Using a plurality of secondary transfer voltages (test voltages) that change to have successively decreasing absolute values, the color block sets each including the color blocks 101 to 103 formed on the chart 100 are sequentially transferred from the upstream side toward the downstream side in the conveying direction of the recording material S when the chart 100 is formed.

[0085] For the following reasons, it is desirable that color patches are not formed near the front end and the rear end in the conveying direction of the recording material S (for example, a range of about 20 to 30 mm inward from the edge end). More specifically, in the end portion in the conveying direction of the recording material S, image defects sometimes occur only at the front end or the rear end in the conveying direction, and not at the end portion in the width direction. In this case, it sometimes becomes difficult to determine whether or not the image defect has occurred due to the assigned secondary transfer voltage.

[0086] The maximum size of the recording material S that can be used in the image forming apparatus 1 according to the present exemplary embodiment is a size of 13 inches (approximately 330 mm)×19.2 inches (approximately 487 mm). Fig. 6A and 6BThe large chart 100L shown in FIG. 1 corresponds to the recording material S having the largest size. In the case where the size of the recording material S is equal to or smaller than 13 inches×19.2 inches and equal to or larger than the A3 size (297 mm×420 mm), Fig. 6A 6B, a chart corresponding to the image data extracted from the image data of the large chart 100L is output. At this time, in the present exemplary embodiment, the image data is extracted according to the size of the recording material S with reference to the leading end center. More specifically, the leading end in the conveying direction of the recording material S and the leading end in the conveying direction of the large chart 100L ( Fig. 6A and 6B The image data is extracted in a state where the center of the width direction of the recording material S and the center of the width direction of the large chart 100L are aligned. In the present exemplary embodiment, the image data is extracted in a manner that a margin of 2.5 mm is provided at the end portions (in the present exemplary embodiment, both ends in the width direction and both ends in the conveying direction). For example, in the case where the large chart 100L is output onto the recording material S having the A3 size (297 mm×420 mm), image data corresponding to a range of 292 mm×415 mm is extracted while a margin of 2.5 mm is provided at each end. Then, the large chart 100L corresponding to the image data is output onto the recording material S having the A3 size (297 mm×420 mm) with respect to the front end center. In the case of using a recording material S having a width of less than 13 inches, the size of the halftone patch 103 in the width direction at the end portions in the width direction becomes smaller. In the case of using a recording material S having a length of less than 19.2 inches, the margin at the rear end in the conveying direction becomes smaller. As described above, eleven patch sets corresponding to -5 to 0 to +5 are arranged on the large chart 100L. On the large chart 100L, the eleven patch sets each including the patches 101 to 103 are arranged within a range of 387 mm in length in the conveying direction in such a manner as to fall within a length of 415 mm in the conveying direction, which is set when the size of the recording material S is the A3 size.

[0087] In the present exemplary embodiment, in the case of using a recording material S having a size smaller than A3 size (297 mm×420 mm), Fig. 7A , 7B , 7C and 7D shown in the small chart 100S is output. Fig. 7A , 7B, 7C and 7D correspond to sizes from A5 size (vertical feeding) to sizes smaller than A3 size (297 mm × 420 mm) (i.e., a length of 210 to 419 mm in the conveying direction). As described above, a total of ten color patch sets are arranged on the small chart 100S, including five sets corresponding to -4 to 0 on the first chart and five sets corresponding to +1 to +5 on the second chart. The size of the image data of the small chart 100S is 13 inches × 210 mm. The size in the width direction is adjusted by reducing the size of the halftone color patch 103 in the width direction according to the size of the recording material S. The size in the conveying direction is set in such a way that five color patch sets fall within the length of 167 mm in the conveying direction, and the page margin at the rear end becomes longer according to the length of 210 to 419 mm in the conveying direction of the recording material S. In the case where the length of the recording material S in the conveying direction is 210 to 419 mm, only five color patch sets can be formed in the conveying direction on one chart. Therefore, in order to increase the number of color patches, a total of ten color patch sets are formed on two separate graphs, including five sets corresponding to -4 to 0 and five sets corresponding to +1 to +5. On the small graph 100S, the color patch set corresponding to -5 on the large graph 100L is omitted.

[0088] Furthermore, regardless of the size of the recording material S, the blue solid color patches 101 and the black solid color patches 102 on the front surface (first surface) and the rear surface (second surface) of the double-sided chart are arranged so as not to overlap each other on the front surface and the rear surface of the recording material S. In the present exemplary embodiment, the patch interval in the width direction is set to 5.4 mm. This is to suppress changes in the detection results of the patch density on the second surface due to the influence of the patch density on the first surface, and to more accurately adjust the secondary transfer voltage on the second surface.

[0089] In the present exemplary embodiment, in addition to standardized sizes, the chart 100 can be output using the recording material S having an arbitrary size (free size) by the operator specifying the size by inputting the size from, for example, the operation unit 70 or the external device 200 .

[0090] 5. Operations in adjustment mode

[0091] Next, the operation in the adjustment mode according to the present exemplary embodiment will be described. Figure 8 is a flowchart schematically illustrating a process in the adjustment mode according to the present exemplary embodiment. Fig. 9A , 9B9C are schematic diagrams illustrating an example of a setting screen of the adjustment mode. A description will be given of an example case where the operator executes the adjustment mode by inputting an instruction from the operation unit 70 of the image forming apparatus 1. A description will be given of an example case where density information (luminance information) of color patches is read in a state where the operator places a recording material S including a formed chart 100 on the platen glass 82 (original platen glass) of the reading device 80. For simplicity, the recording material on which the chart is formed will sometimes be simply referred to as a "chart".

[0092] The setting screen of the adjustment mode will be described. In the present exemplary embodiment, the control unit 30 (adjustment processing unit 31d) displays the following on the display unit 70a of the operation unit 70: Fig. 9A . The setting screen 300 includes a voltage setting unit 301 for setting adjustment values ​​of the secondary transfer voltages of the front surface (first surface) and the rear surface (second surface) of the recording material S. The setting screen 300 also includes an output surface selection unit 302 for selecting whether the chart 100 is to be output onto one surface or both surfaces of the recording material S. The setting screen 300 also includes an output instruction unit (chart output button) 303 for issuing an output instruction of the chart 100. The setting screen 300 also includes a determination unit (confirmation button) 304 for determining the setting and a cancel button 305 for canceling the change of the setting. The setting screen 300 also includes a message display unit 306 for displaying various messages about the adjustment mode. In the present exemplary embodiment, the start button 307 provided in the operation unit 70 adjacent to the display unit 70a serves as an input unit for inputting a read start instruction of the chart 100 to the reading device 80. Alternatively, a display (button) serving as an input unit may be provided on the above-mentioned setting screen 300 displayed on the display unit 70a.

[0093] In the case where an adjustment value "0" is selected in the voltage setting unit 301, the secondary transfer voltage (more specifically, the recording material partial voltage Vp) is set to a specified value (tabular value) preset for the currently selected recording material S. In this case, the secondary transfer voltage can be set to the value currently set for the currently selected recording material S. In this case, the center voltage value of the secondary transfer voltage when the chart 100 is output (the value corresponding to the color block set of 0 on the chart 100) is set to this value. In the case where an adjustment value other than "0" is selected, in the present exemplary embodiment, the secondary transfer voltage is adjusted by adjusting the amount ΔV of 150V for each level of the adjustment value. In this case, the center voltage value of the secondary transfer voltage when the chart 100 is output is set to this value. By operating the chart output button 303 after selecting the adjustment value, the chart 100 is output with the selected center voltage value. By operating the confirmation button 304 after selecting the adjustment value, the adjustment value of the secondary transfer voltage is determined. The control unit 30 acquires information about settings such as the center voltage value that have been input in the operation unit 70 via the setting screen 300 and stores the information into the storage unit (RAM 33, secondary transfer voltage storage unit / calculation unit 31f, etc.) as necessary.

[0094] The process in the adjustment mode will be described. First, if the operator inputs information (paper type category, size, etc.) about the recording material S to be used in the adjustment mode, the control unit 30 displays the setting screen 300 of the adjustment mode on the display unit 70a in step S201.

[0095] At this time, the control unit 30 displays the setting screen 300 on the display unit 70a. The control unit 30 acquires the information on the recording material S that has been input by the operator on the input screen, and adjusts the secondary transfer voltage in association with the information on the recording material S. The information on the recording material S can be acquired in the following manner. If a recording material cartridge 91 storing the recording material S to be used in the adjustment mode is selected, information preset in association with the recording material cartridge 91 can be acquired.

[0096] Next, in step S202, the control unit 30 acquires the setting of the center voltage value of the secondary transfer voltage when outputting the chart 100, which has been input by the operator on the setting screen 300, and the setting indicating whether a single-sided chart or a double-sided chart is to be output. Next, in step S203, the control unit 30 acquires a signal indicating that the operator has operated the chart output button 303 on the setting screen 300. Thereafter, in step S204, before the output of the chart 100, the control unit 30 acquires a second-order or higher-order polynomial expression (a quadratic expression in the present exemplary embodiment) of the relationship between the voltage and the current corresponding to the resistance of the secondary transfer portion N2 by an operation similar to the above-mentioned ATVC. Then, in step S205, the control unit 30 sets the secondary transfer voltage (test voltage) based on the acquired information about the relationship between the voltage and the current and the information about the center voltage value set on the setting screen 300, and performs control of outputting the chart 100. At this time, the control unit 30 performs control of outputting a predetermined chart 100 suitable for the size of the recording material S by adjusting the image data of the chart 100 as described above and changing the secondary transfer voltage every 150V. As described above, in the case of using the recording material S corresponding to the large chart 100L, a large chart 100L obtained by transferring eleven patch sets onto the recording material S while switching the secondary transfer voltage and fixing the patch sets is output. As described above, in the case of using the recording material S corresponding to the small chart 100S, two small charts 100S each obtained by transferring five patch sets onto the recording material S while switching the secondary transfer voltage and fixing the patch sets are output.

[0097] Next, in step S206, the control unit 30 determines whether the reading device 80 can read the chart 100 based on whether the size of the recording material S used to output the chart 100 is a size that can be read by the reading device 80. In the case where the control unit 30 determines in step S206 that reading cannot be performed ("No" in step S206), the process proceeds to step S220. At this time, the control unit 30 may, for example, Fig. 9B The message display unit 306 ( Fig. 9A ) is displayed in the screen 300 to prompt the operator to manually adjust the secondary transfer voltage. In the case where the size of the recording material S used to output the chart 100 is a size that cannot be read by the reading device 80, in step S220, the voltage setting unit 301 ( Fig. 9A) to manually adjust the secondary transfer voltage. In the case where the control unit 30 determines in step S206 that reading can be performed ("Yes" in step S206), the process proceeds to step S207. Then, in step S207, the control unit 30 waits for a reading start instruction of the chart 100 to be input by the operator operating the start button 307 in the operation unit 70. At this time, the control unit 30 may, for example, Fig. 9C The message display unit 306 ( Fig. 9A ) displays a message prompting the operator to set the chart 100 on the reading device 80. Fig. 9C An example case where the small chart 100S is output is illustrated. In the case where the size of the recording material S is a size readable by the reading device 80, in step S219, the control unit 30 can present candidates for a desired setting of the secondary transfer voltage based on the reading result of the chart 100 obtained by the reading device 80. In the case where the adjustment value of the secondary transfer voltage is manually changed on the setting screen 300 while waiting for an input reading start instruction of the chart 100, the control unit 30 advances the process to step S220.

[0098] Next, in step S207, if the control unit 30 acquires a read start signal for issuing a read start instruction of the chart 100 from the operation unit 70, the process proceeds to step S208. In step S208, the control unit 30 determines whether the size of the recording material S for outputting the chart 100 is a large size. In the case where the control unit 30 determines in step S208 that the size of the recording material S is a large size such as A3 size (297 mm×420 mm) or Ledger (approximately 280 mm×432 mm) (“Yes” in step S208), the process proceeds to step S209. Then, in step S209, the control unit 30 determines whether a single-sided chart has been output or a double-sided chart has been output. In the case where the control unit 30 determines in step S209 that a single-sided chart has been output (“Yes” in step S209), the process proceeds to step S210. In step S210, the reading device 80 reads only one surface of the recording material S. In the case where the control unit 30 determines in step S209 that a double-sided chart has been output (No in step S209), the process proceeds to step S211. In step S211, first, the reading device 80 reads the front surface (first surface) of the recording material S. Thereafter, if the control unit 30 acquires a read start signal from the operation unit 70 again, then in step S212, the rear surface (second surface) of the recording material S is read. In this way, in the case of using a recording material S having a large size, one large chart 100L on which eleven color patch sets corresponding to -5 to 0 to +5 are formed, which has been set on the reading device 80, is read according to one read start signal.

[0099] On the other hand, in the case where the control unit 30 determines in step S208 that the size of the recording material S is a small size such as A4 horizontal (297 mm×210 mm) or letter horizontal (approximately 280 mm×216 mm), the processing proceeds to step S213. Then, in step S213, the control unit 30 determines whether a single-sided chart has been output or a double-sided chart has been output. In the case where the control unit 30 determines in step S213 that a single-sided chart has been output (“Yes” in step S213), the processing proceeds to step S214. In step S214, the reading device 80 reads only one surface of the two recording materials S at the same time. In the case where the control unit 30 determines in step S213 that a double-sided chart has been output (“No” in step S213), the processing proceeds to step S215. In step S215, first, the reading device 80 reads the front surfaces (first surfaces) of the two recording materials S at the same time. Thereafter, if the control unit 30 acquires the read start signal from the operation unit 70 again, then in step S216, the rear surfaces (second surfaces) of the two recording materials S are read simultaneously. In this way, in the case of using the recording material S having a small size, the first small chart 100S on which five color block sets corresponding to -4 to 0 are formed and the second small chart 100S on which five color block sets corresponding to +1 to +5 are formed, which have been simultaneously set on the reading device 80, are read according to one read start signal. In the present exemplary embodiment, the above-mentioned one read start signal is input to the control unit 30 by the operator operating the start button 307 serving as an input unit. However, the present disclosure is not limited to such a configuration. For example, the reading device 80 may include a sensor that detects that a document is arranged on the reading surface or detects that a document is placed on the document stacking portion of the automatic document conveying device 81, and automatically starts reading the document according to the detection result obtained by the sensor. In the case of such a configuration, the above-mentioned one read start signal may be input to the control unit 30 from the above-mentioned sensor serving as an input unit.

[0100] Next, in step S217, the control unit 30 determines a read error for determining whether the chart 100 has not been correctly read by the reading device 80. A description is given of an example case of reading the chart 100 placed on the platen glass 82. Alternatively, for example, in the event of any problem occurring in the transmission of the chart 100 performed by the automatic document transmission device 81, a read error may be determined. In the case where the control unit 30 determines in step S217 that a read error has not been detected ("No" in step S217), the processing proceeds to step S218. In step S218, the control unit 30 performs a process for determining an adjustment value for the secondary transfer voltage. The process for determining the adjustment value for the secondary transfer voltage will be described below. On the other hand, in the case where the control unit 30 determines in step S217 that a read error has been detected ("Yes" in step S217), the processing returns to step S207, and the control unit 30 determines again whether to use the reading device 80.

[0101] Next, in step S219, the control unit 30 displays the adjustment value determined in step S218 in the voltage setting unit 301 of the setting screen 300. The adjustment value indicates a candidate for the desired setting of the secondary transfer voltage. By visually checking the chart 100, the operator can determine whether the adjustment value displayed on the setting screen 300 is appropriate. In the case where the operator does not change the adjustment value displayed on the setting screen 300, the operator operates the confirmation button 304 on the setting screen 300 without making any changes. On the other hand, in the case where the operator changes (manually adjusts) the adjustment value displayed on the setting screen 300, the operator inputs the adjustment value desired to be set into the voltage setting unit 301 of the setting screen 300, and operates the confirmation button 304 on the setting screen 300. In step S220, the control unit 30 determines whether the adjustment value has been changed. Then, in the case where the control unit 30 obtains a signal indicating that the confirmation button 304 has been operated when the adjustment value has not been changed ("No" in step S220), the process proceeds to step S221. In step S221, the control unit 30 stores the adjustment value determined in step S218 in the RAM 33 (or the secondary transfer voltage storage unit / calculation unit 31f). On the other hand, in the case where the control unit 30 acquires a signal indicating that the confirmation button 304 has been operated after the adjustment value has been changed ("Yes" in step S220), the process proceeds to step S222. In step S222, the control unit 30 stores the adjustment value input by the operator in the RAM 33 (or the secondary transfer voltage storage unit / calculation unit 31f). In the above manner, the adjustment mode ends.

[0102] When a subsequent job is performed using the recording material S for which the secondary transfer voltage has been set in the adjustment mode, the control unit 30 (secondary transfer voltage storage unit / calculation unit 31f) sets the secondary transfer voltage according to the adjustment value stored as described above until the next adjustment mode is performed. More specifically, the control unit 30 (secondary transfer voltage storage unit / calculation unit 31f) calculates the adjustment amount ΔV as ΔV=adjustment value×150V using the adjustment value stored as described above, and calculates the adjusted recording material partial voltage Vp+ΔV using the calculated adjustment amount ΔV. Then, using the adjusted recording material partial voltage Vp+ΔV, the control unit 30 (secondary transfer voltage storage unit / calculation unit 31f) calculates the secondary transfer voltage Vtr (=Vb+Vp+ΔV).

[0103] Next, we will describe Figure 8 The process of determining the adjustment value of the secondary transfer voltage in step S218. Fig.10 100S as a single-sided chart. A description will be given of an example case where the luminance data of the blue solid color patch 101 is used as the density information (luminance information) of the color patch for determining the adjustment value of the secondary transfer voltage. For the sake of convenience, the description will be given assuming that the above-mentioned adjustment values ​​-4 to 0 to +5 correspond to the color patch numbers 1 to 10, respectively.

[0104] In step S301, the control unit 30 acquires the RGB luminance data (8 bits) of each blue pure color block read from the two small charts 100S set on the reading device 80 by the operator and stored in the RAM 33. Next, in step S302, the control unit 30 calculates the luminance average value Lave_B(N) (N=1 to 10) of each color block using the luminance data acquired in step S301. By the processing in step S302, for example, the luminance data indicating the luminance of each color block are acquired. Fig.11) and the luminance average value of the color patch. Next, in step S303, the control unit 30 calculates the standard deviation Lave_stdev(n) (n=1 to 7) of the luminance average value of every four color patch numbers (N to N+3) in sequence from the color patch with a small color patch number to the color patch with a large color patch number. Next, in step S304, the control unit 30 extracts the color patch numbers N to N+3 (luminance stable area) where the standard deviation Lave_stdev(n) of the luminance average value is the smallest. Next, in step S305, the control unit 30 selects the largest color patch number among the color patch numbers having a recording material partial pressure Vp+ΔV (absolute value) determined from the adjustment value corresponding to each color patch number extracted in step S304 and equal to or less than a predetermined upper limit value. In other words, the control unit 30 selects the adjustment value at which the luminance average value (maximum density) of the blue solid color patch 101 is the smallest when the recording material partial pressure Vp+ΔV does not exceed the upper limit value. For example, from the perspective of preventing image defects caused by too high a secondary transfer voltage, the above upper limit value is preset according to the paper type category of the recording material S. Then, in step S306, the control unit 30 determines the adjustment value corresponding to the patch number selected in step S305 as a candidate for the desired setting of the secondary transfer voltage, and stores the adjustment value in the RAM 33. By such processing, for example, Fig.11 The adjustment value corresponding to patch number 4 where the decrease in the average luminance value (increase in density) stops is determined as a candidate.

[0105] The process of determining the adjustment values ​​of the first surface and the second surface of the recording material S based on the reading results of the first surface and the second surface of each of the two small charts 100S as double-sided charts is similar to the above-described process. The process of determining the adjustment values ​​based on the reading results of one large chart 100L (a single-sided chart or both surfaces of a double-sided chart) is also similar to the above-described process except that the number of patch sets is different.

[0106] The color of the color patch whose luminance data is to be acquired is not limited to blue. In addition to the blue color patch, a red color patch or a green color patch may be used, or a single color pure color patch of Y, M, C or K may be used. Alternatively, halftone luminance data may be acquired.

[0107] In the present exemplary embodiment, the adjustment amount of the secondary transfer voltage is determined based on the color patches in the luminance stable region extracted by sequentially obtaining the standard deviation of the color patch luminance data of each group of a plurality of color patch numbers. However, the method of determining the adjustment amount of the secondary transfer voltage is not limited to this method. For example, the adjustment amount of the secondary transfer voltage may be determined by sequentially obtaining the luminance difference between color patches having adjacent color patch numbers and extracting the color patches in the luminance stable region where the luminance difference is equal to or less than a predetermined value.

[0108] 6. Effect

[0109] As described above, the image forming apparatus 1 according to the present exemplary embodiment includes the image bearing member 51 that carries the colorant image, the intermediate transfer member 44b to which the colorant image is primarily transferred from the image bearing member 51, the transfer member 45b that forms the transfer portion N2 on the recording material S where the colorant image is secondarily transferred from the intermediate transfer member 44b, the applying unit 76 that applies a voltage to the transfer member 45b, the discharge unit 48 that discharges the recording material S including the image formed by fixing the transferred colorant image at the transfer portion N2, the reading device 80 that can read the concentration information of the image on the recording material set by the operator, and the control unit 30 that can execute a mode for adjusting the secondary transfer voltage to be applied to the transfer member 45b by the applying unit 76 in the secondary transfer by discharging from the discharge unit 48 the recording material S on which a chart is formed by sequentially transferring a plurality of test images by applying a plurality of test voltages to the transfer member 45b. Then, in the present exemplary embodiment, in the adjustment mode, the control unit 30 may discharge the first recording material on which the first chart is formed and the second recording material on which the second chart is formed from the discharge unit 48, read density information of the test images on the first and second recording materials simultaneously set on the reading device 80 by the operator using the reading device 80, and output information on the adjustment amount of the secondary transfer voltage based on the density information of the test images on the first and second charts acquired from the reading result obtained from the reading device 80. The reading device 80 may include a reading surface 82 that supports the first and second recording materials simultaneously set in such a manner that the reading device 80 can perform reading. The reading device 80 may also include a conveying device 81 that sequentially conveys the first and second recording materials simultaneously set in such a manner that the reading device 80 can perform reading.

[0110] The image forming apparatus 1 may include a duplex conveying unit 11 that conveys the recording material S to the transfer portion N2 in order to transfer the toner image to the second surface of the recording material S having the first surface including the fixed toner image when forming the image on both surfaces of the recording material S. In this case, in the adjustment mode, the first recording material having the first surface including the formed first chart and the second surface including the formed third chart, and the second recording material having the first surface including the formed second chart and the second surface including the formed fourth chart may be discharged from the discharge unit 48. Then, in the case of using the above-mentioned reading surface 82 of the reading device 80, the density information of the test image on one surface of each of the first and second recording materials simultaneously set on the reading device 80 set by the operator may be read by the reading device 80, and the density information of the test image on different surfaces of each of the first and second recording materials simultaneously set on the reading device 80 set by the operator may be read by the reading device 80. Alternatively, in the case of using the above-mentioned conveying device 81 of the reading device 80, the density information of the test images on one surface and the different surfaces of each of the first and second recording materials set simultaneously on the reading device 80 by the operator may be read by the reading device 80. Then, the control unit 30 may output information on the adjustment amount of the secondary transfer voltage to be applied when an image is to be formed on the first surface of the recording material S based on the density information of the test images on the first and second charts acquired from the reading result acquired by the reading device 80, and output information on the adjustment amount of the secondary transfer voltage to be applied when an image is to be formed on the second surface of the recording material S based on the density information of the test images on the third and fourth charts acquired from the reading result acquired by the reading device 80.

[0111] The first chart may include a plurality of test images that are sequentially transferred from the upstream side toward the downstream side in the conveyance direction of the first recording material when forming the first chart using a plurality of test voltages whose absolute values ​​are changed to increase sequentially, and the second chart may include a plurality of test images that are sequentially transferred from the upstream side toward the downstream side in the conveyance direction of the second recording material when forming the second chart using a plurality of test voltages whose absolute values ​​are changed to increase sequentially from an absolute value larger than a maximum absolute value among the absolute values ​​of the plurality of test voltages used when forming the first chart.

[0112] Alternatively, the first chart may include a plurality of test images sequentially transferred from the upstream side toward the downstream side in the conveying direction of the first recording material when forming the first chart using a plurality of test voltages whose absolute values ​​change to decrease sequentially, and the second chart includes a plurality of test images sequentially transferred from the upstream side toward the downstream side in the conveying direction of the second recording material when forming the second chart using a plurality of test voltages whose absolute values ​​change to decrease sequentially from an absolute value smaller than a minimum absolute value among the absolute values ​​of the plurality of test voltages used when forming the first chart. The control unit 30 may output the above-mentioned information on the adjustment amount to a display unit 70a provided in the image forming apparatus 1 or a display unit of an external device 200 connected to the image forming apparatus 1, and display the information on the adjustment amount on the display unit. The control unit 30 may output the above-mentioned information on the adjustment amount to a storage unit 33 provided in the image forming apparatus 1, and store the information on the adjustment amount in the storage unit 33. In this exemplary embodiment, in the adjustment mode, the control unit 30 can discharge from the discharge unit 48 a recording material having a size larger than the corresponding sizes of the above-mentioned first and second recording materials and including a chart formed by transferring multiple test images, and adjust the secondary transfer voltage based on the reading result of the concentration information of the test image on the one recording material obtained by the reading device 80.

[0113] Furthermore, according to the present exemplary embodiment, in the case where the adjustment mode is executed using the recording material S having a small size such as A4 size or LTR size, usability can also be enhanced by reducing the number of times the chart 100 is placed on the reading device 80 .

[0114] Next, a second exemplary embodiment of the present disclosure will be described. The basic configuration and operation of the image forming apparatus according to the present exemplary embodiment are the same as those of the image forming apparatus according to the first exemplary embodiment. Therefore, in the image forming apparatus according to the present exemplary embodiment, components having the same or corresponding functions or configurations as those of the image forming apparatus according to the first exemplary embodiment are given the same reference numerals as those in the first exemplary embodiment, and detailed descriptions will be omitted.

[0115] In the adjustment mode, considering the reduction and stability of the adjustment time, it is desirable to output the chart 100 to which the color patch is transferred while sequentially switching the secondary transfer voltage (test voltage) from a small absolute value to a large absolute value or from a large absolute value to a small absolute value. Then, assuming that the color patches are arranged in a predetermined order from the front end side toward the rear end side in the scanning direction of the chart 100, for example, a process of obtaining the adjustment amount of the secondary transfer voltage by associating the density information of the color patches read in this order with the information about the secondary transfer voltage (test voltage) is performed. Specifically, for example, as described in the first exemplary embodiment, the standard deviation of the luminance average value corresponding to each color patch number assumed to be acquired according to the predetermined switching order of the secondary transfer voltage (test voltage) is obtained. Therefore, if the arrangement order of the plurality of charts 100 (two small charts 100S in the present exemplary embodiment) on the reading device 80 or the conveying order (reading order) of the charts 100 in the automatic document conveying device 81 is different from the preset predetermined order, the processing result becomes inappropriate.

[0116] In view of the foregoing, in the present exemplary embodiment, the association between the density information of at least one color block of each of the two small charts 100S read by the reading device 80 and the information on the secondary transfer voltage (test voltage) corresponding to each color block is optimized. Hereinafter, a more detailed description will be given.

[0117] and Fig.11 similar, Fig. 12A The diagram shows the relationship between the patch number (voltage level, adjustment value) of the blue solid color patch 101 and the average brightness value of the patch obtained when two small charts 100S as single-sided charts are read by the reading device 80. For convenience, the description will be given assuming that the above adjustment values ​​-4 to 0 to +5 correspond to the patch numbers 1 to 10, respectively.

[0118] In the case where the size of the recording material S used to output the chart 100 is a small size such as A4 landscape (297 mm × 210 mm) or letter landscape (approximately 280 mm × 216 mm), color blocks with color block numbers 1 to 5 are formed on the first small chart 100S, and color blocks with color block numbers 6 to 10 are formed on the second small chart 100S.

[0119] In the case where two small charts 100S are set on the reading device 80 by the operator through a predefined predetermined method, the control unit 30 can obtain information about Fig. 12A, and the luminance average value. The predetermined method is, for example, a predetermined arrangement order of two small charts 100S on the platen glass 82 of the reading device 80 (for example, the first chart is arranged on the left and the second chart is arranged on the right in a manner similar to the arrangement of a plurality of color patches in the large chart 100L). Alternatively, the predetermined method is, for example, an overlapping order of two small charts 100S on a document stacking portion of the automatic document conveying device 81 (for example, the first chart is overlapped on the second chart). In other words, the predetermined method is a conveyance order of two small charts 100S in the automatic document conveying device 81 (for example, the first chart is conveyed first, followed by the second chart later).

[0120] On the other hand, in the case where the operator fails to correctly set the two small charts 100S on the reading device 80 by the above-mentioned predetermined method, the following state is caused. For example, in the case where the arrangement order of the two small charts 100S on the platen glass 82 of the reading device 80 is opposite to the order in the case of the above-mentioned predetermined method, or in the case where the transfer order of the two small charts 100S in the automatic document transfer device 81 is opposite to the order in the case of the above-mentioned predetermined method, the control unit 30 obtains information about the following state: Fig. 12B Information on the relationship between the color patch number and the luminance average value shown in .

[0121] In this case, a luminance difference that could not be generated otherwise occurs between the luminance average values ​​of the color patches with color patch numbers 5 and 6. Therefore, in the case of, for example, the first exemplary embodiment ( Fig.10 ) in the method of determining the adjustment value of the secondary transfer voltage, it becomes impossible to correctly obtain a desired adjustment value.

[0122] In view of the foregoing, in the present exemplary embodiment, in the case where the luminance difference (difference between luminance average values) between the color patches having the color patch number 5 and the color patch number 6 is equal to or greater than the predetermined threshold value, the control unit 30 determines that the method of setting the two small charts 100S on the reading device 80 is incorrect. Then, the control unit 30 performs a process of replacing a set of luminance data of the color patch numbers 1 to 5 and a set of luminance data of the color patch numbers 6 to 10 acquired from the reading device 80 and stored in the RAM 33.

[0123] Next, a process of determining an adjustment value of a secondary transfer voltage according to the present exemplary embodiment will be described. Fig.13 is a flowchart schematically illustrating an example of a procedure of a process. Fig.13 The processing shown in Figure 8The processing in step S218 in the process of the adjustment mode shown in and already described in the first exemplary embodiment is performed. A description will be given of an example case where a single-sided chart is read. As a case where the chart 100 is not correctly set on the reading device 80 by a predetermined method, a description will be given of an example case where the arrangement order of two small charts 100S as single-sided charts on the reading device 80 is reversed or the conveyance order of two small charts 100S in the automatic document conveying device 81 is reversed. A description will be given of an example case where the luminance data of the blue solid color block 101 is used as the density information (luminance information) of the color block for determining the adjustment value of the secondary transfer voltage.

[0124] In step S401, the control unit 30 (adjustment processing unit 31d) acquires the RGB luminance data (8 bits) of each blue pure color block read from the two small charts 100S set by the operator on the reading device 80 and stored in the RAM 33. At this time, the control unit 30 acquires the luminance data of each color block assuming that the color blocks are arranged in a predetermined order from the front end side to the rear end side in the scanning direction of the reading device 80. Then, in step S402, the control unit 30 calculates the luminance average value Lave_B (N) (N = 1 to 10) of each color block using the luminance data acquired in step S401, and stores the luminance average value in the RAM 33.

[0125] Next, in step S403, the control unit 30 calculates the luminance difference between the color patches having adjacent color patch numbers (the difference between the luminance average values) based on the luminance average values ​​stored in the RAM 33 in step S402. Next, in step S404, the control unit 30 determines whether the recording material S for outputting the chart 100 is a small size. In the case where the control unit 30 determines in step S404 that the size of the recording material S for outputting the chart 100 is a small size such as A4 landscape (297 mm×210 mm) or letter landscape (approximately 280 mm×216 mm) (“Yes” in step S404), the process proceeds to step S405.

[0126] Then, in step S405, the control unit 30 determines whether the luminance difference between the color blocks having color block number 5 and color block number 6 calculated in step S403 is less than a predetermined threshold value. The predetermined threshold value is preset to a value corresponding to a measured change value of the luminance value obtained by the reading device 80 when the two small charts 100S are correctly set on the reading device 80, for example, by a predetermined method, and is stored in the ROM 32. Then, in a case where the control unit 30 determines in step S405 that the luminance difference is less than the predetermined threshold value ("Yes" in step S405), the processing proceeds to step S406. In step S406, the control unit 30 determines an adjustment value of the secondary transfer voltage using the luminance average value of each color block stored in the RAM 33 in step S402. The processing in step S406 may be, for example, the same as that described in the first exemplary embodiment. Fig.10 The processing in steps S303 to S306 is the same.

[0127] On the other hand, in a case where the control unit 30 determines in step S405 that the luminance difference is not less than the predetermined threshold value (ie, equal to or greater than the predetermined threshold value) (NO in step S405 ), the processing proceeds to step S407 .

[0128] In this case, it can be determined that the arrangement order or transfer order (reading order) of the first small chart 100S and the second small chart 100S is incorrect. In this case, in step S407, the control unit 30 replaces the data corresponding to the color block numbers 1 to 5 on the first small chart 100S and the data corresponding to the color block numbers 6 to 10 on the second small chart 100S in the data of the luminance average value of each color block that has been stored in the RAM 33 in step S402. At this time, the association between the luminance data acquired in step S401 and the color block number can be optimized, and the luminance average value can be calculated using the optimized luminance data. In other words, the association between the color block number and the luminance data is optimized by correcting the arrangement order of the luminance data in such a way that each color block number correctly corresponds to the secondary transfer voltage (test voltage). Thereafter, in step S406, the control unit 30 determines the adjustment value of the secondary transfer voltage using the luminance average value of each color block whose association with the color block number has been optimized in step S407. As described above, the processing in step S406 can be, for example, the same as that described in the first exemplary embodiment. Fig.10 The processing in steps S303 to S306 is the same.

[0129] When the control unit 30 determines in step S404 that the size of the recording material S for outputting the chart 100 is a large size such as A3 size (297 mm×420 mm) or Ledger (approximately 280 mm×432 mm) (NO in step S404 ), the processing proceeds to step S406 .

[0130] The color of the color patch whose luminance data is to be acquired is not limited to blue. In addition to the blue color patch, a red color patch or a green color patch may be used, or a single color pure color patch of Y, M, C or K may be used. Alternatively, halftone luminance data may be acquired.

[0131] As a case where the chart 100 is not correctly set on the reading device 80 by a predetermined method, a description of an example case where the arrangement order or the transmission order of the two small charts 100S as a single-sided chart is reversed has been given. However, the case is not limited to this. The case where the chart 100 is not correctly set on the reading device 80 by a predetermined method includes the following cases. The case includes a case where the arrangement order or the reading order of at least one of the multiple charts 100 is incorrect, a case where the arrangement orientation of at least one of the multiple charts 100 is incorrect, a case where the placement surface of at least one of the multiple charts 100 is incorrect, or a combination of these. The case generally includes the following cases. The case includes a case where the arrangement order or the reading order of the first and second charts 100 is reversed (corresponding to the above example), a case where the arrangement orientation of at least one of the first and second charts 100 is reversed, a case where the placement surface (the arrangement order or the reading order of the first surface and the second surface) of at least one of the first and second charts 100 is reversed, or a combination of these. By presetting a threshold value corresponding to each of these cases as the above-mentioned predetermined threshold value, in any case, the association between the color block number and the luminance data can be optimized by correcting the arrangement order of the luminance data.

[0132] In the above description, whether the method of setting the chart 100 on the reading device 80 is correct is determined using the density information of the most downstream color patch in the conveying direction of the first chart 100 and the most upstream color patch in the conveying direction of the second chart 100. However, the determination method is not limited thereto. Whether the method of setting the chart 100 on the reading device 80 is correct may be determined based on the density information of at least one arbitrary color patch of each of the plurality of charts 100.

[0133] For example, it is possible to determine whether the setting method is correct using the density information of the most upstream color patch in the conveying direction of the first chart 100 and the most downstream color patch in the conveying direction of the second chart 100. Fig. 12B In the above example, when the difference between the density information of the most downstream color patch of the first chart and the density information of the most upstream color patch of the second chart is equal to or greater than the predetermined threshold, it is determined that the setting method is incorrect. Fig. 12BIn the case where the difference between the density information of the most upstream color block of the first chart and the density information of the most downstream color block of the second chart is less than a predetermined threshold, it can also be determined that the setting method is incorrect. It is only necessary to use the density information of the color block that is easier to determine whether the setting method is correct in each of the above-mentioned cases where the setting method is incorrect. The determination is not limited to the determination based on the difference in density information between the color blocks, and can also be determined by any comparison method (such as the difference in density information including comparison for determining greater density information, or the ratio between each piece of density information). Multiple pieces of density information of multiple color blocks in each of the multiple charts 100 can be used.

[0134] Whether the arrangement method of each chart 100 is correct (such as whether the arrangement direction of at least one of the plurality of charts 100 is reversed) can be determined based on the density information of at least one color block in the corresponding chart 100. Fig. 12A , when the arrangement direction of the first diagram is reversed, the average brightness increases as the color block number increases, which is different from Fig. 12A Such a transition of the luminance average value can be obtained from, for example, multiple pieces of density information of multiple color blocks in each chart 100 (for example, the standard deviation or difference of the density information is obtained in sequence, or obtained from the difference of the density information between the most upstream and most downstream color blocks). Then, it can be determined whether the arrangement orientation of each chart 100 is correct based on the result.

[0135] As described above, in the present exemplary embodiment, the control unit 30 determines which of the first and second graphs the result read by the reading device 80 corresponds to based on the reading result obtained by the reading device 80, and outputs information about the adjustment amount of the secondary transfer voltage based on the reading result obtained by the reading device 80 and the obtained determination result. In the present exemplary embodiment, the control unit 30 performs a process for outputting the information about the adjustment amount of the secondary transfer voltage by associating the density information of the plurality of test images acquired from the reading device 80 with the information indicating the plurality of test voltages in such a manner that the density information of each test image corresponds to the test voltage applied when the corresponding test image is transferred. In the present exemplary embodiment, the control unit 30 may perform a process for optimizing the association between the density information of the plurality of test images acquired from the reading device 80 and the plurality of test voltages in such a manner that the density information of each test image corresponds to the test voltage applied when the corresponding test image is transferred, based on the density information of at least one test image among the plurality of test images read from one recording material S of the first and second recording materials and the density information of at least one test image among the plurality of test images read from the different recording material S of the first and second recording materials. Particularly in the present exemplary embodiment, the control unit 30 performs the above-mentioned optimization processing based on the first density information acquired from the reading device 80 when the operator sets the first and second recording materials on the reading device 80 by the above-mentioned predetermined method, and based on the second density information acquired from the reading device 80 when the operator sets the first and second recording materials on the reading device 80 by the predetermined method, the first density information being the density information of the most downstream test image in the conveying direction of the first recording material when the first chart is formed, and the second density information being the density information of the most upstream test image in the conveying direction of the second recording material when the second chart is formed. In the present exemplary embodiment, the control unit 30 performs the above-mentioned optimization processing when the difference between the density indicated by the first density information and the density indicated by the second density information is equal to or greater than a predetermined threshold value. The optimization processing may include a process of replacing the density information acquired from the reading device 80 as the density information of the test image of the first chart and the density information acquired from the reading device 80 as the density information of the test image of the second chart. Identification information indicating at least one of the first surface or the second surface is formed on the first and second recording materials, and the control unit 30 can determine whether the concentration information of the test image acquired from the reading device 80 is the concentration information of the test image on the first surface of the recording material or the concentration information of the test image on the second surface of the recording material based on the identification information read by the reading device 80.

[0136] Then, according to the present exemplary embodiment, effects similar to those of the first exemplary embodiment can be obtained, and problems caused by errors in the arrangement order or reading order of the chart 100, which are made when the adjustment mode is performed using the recording material S having a small size, can be prevented.

[0137] Next, a third exemplary embodiment of the present disclosure will be described. The basic configuration and operation of the image forming apparatus according to the present exemplary embodiment are the same as those of the image forming apparatus according to the first exemplary embodiment. Therefore, in the image forming apparatus according to the present exemplary embodiment, components having the same or corresponding functions or configurations as those of the image forming apparatus according to the first exemplary embodiment are given the same reference numerals as those in the first exemplary embodiment, and detailed description will be omitted.

[0138] In the second exemplary embodiment, the reading order (pages) of the chart and the arrangement (orientation) of the chart are determined based on the density information of the color patches. However, in the case where the change in density between the color patches is small, the processing result may become inappropriate. Because it is difficult to determine the first surface or the second surface of a double-sided chart based only on the density information of the color patches, the processing result may become inappropriate, or the instruction to the user may become complicated.

[0139] In view of the foregoing, in the present exemplary embodiment, the arrangement of the charts and the reading order of the charts are optimized based on the identification information of the charts read by the reading device 80. Hereinafter, a more detailed description will be given.

[0140] Fig.14A and 14B as well as Fig.15A , 15B 15C and 15D are schematic diagrams of the chart 100 according to the present exemplary embodiment. In the present exemplary embodiment, a rear end identification patch 501 for determining the arrangement of the chart 100 and a page determination patch 502 for determining the reading order of the chart 100 are formed on the chart 100.

[0141] Fig.14A and 14B A large chart 100L is illustrated on which a backend identification patch 501 and a page determination patch 502 are formed. Fig.14A A large chart 100La is illustrated which is output as a single-sided chart or as the first surface of a double-sided chart, and Fig. 14B The diagram shows a large chart 100Lb output as the second surface of a double-sided chart. Fig.15A , 15B , 15C and 15D illustrate a small chart 100S on which a back-end identification patch 501 and a page determination patch 502 are formed. Fig.15AA small chart 100Sa output as a first surface of a first single-sided chart or a first double-sided chart is illustrated. Fig. 15B A small chart 100Sa output as a first surface of a second single-sided chart or a second double-sided chart is illustrated. Fig. 15C A small chart 100Sb output as the second surface of the first double-sided chart is illustrated. Fig.15D A small chart 100Sb output as the second surface of the second double-sided chart is illustrated.

[0142] In all the charts 100, a black band, which is a band-shaped image formed using black toner and extending in the main scanning direction, is formed as a rear end identification patch 501 at the rear end in the conveying direction of the recording material S when the chart 100 is formed. With this configuration, the orientation (arrangement) of the chart 100 can be corrected based on the position of the rear end identification patch 501 in the image read by the reading device 80. In all the charts 100, a page determination patch 502 arranged adjacent to the rear end identification patch 501 in the main scanning direction is formed.

[0143] In the present exemplary embodiment, the pages (reading order) of the chart 100 determine the identification of the color of the color block 502 by page. Fig.14A and 14B as well as Fig.15A , 15B , 15C, and 15D, are formed with page determination color blocks 502 of different colors on the respective pages of the charts shown in FIG. Fig.16 The correspondence relationship between the color of the page determination color block 502 and each page (page number) of the chart 100 according to the present exemplary embodiment is illustrated.

[0144] Next, a description will be given of a process of optimizing the arrangement of the chart 100 and the reading order of the chart 100 according to the present exemplary embodiment. This process is performed after the reading process of the chart 100 is performed by the reading device 80 and before the process of determining the recommended adjustment value of the secondary transfer voltage in the case of outputting one double-sided large chart, two single-sided small charts, or two double-sided small charts.

[0145] In step S601, the control unit 30 stores the input image read from the chart 100 set on the reading device 80 by the operator into the RAM 33. In step S602, the control unit 30 determines whether the rear end identification patch 501 is included in the lower part of the read input image. In the case where the chart 100 is set on the reading device 80 in the normal orientation, the lower part of the input image is a position corresponding to the rear end in the conveying direction of the recording material S when the chart 100 is formed.

[0146] In the case where the control unit 30 determines that the rear end identification color patch 501 is included in the lower part of the input image ("Yes" in step S602), the processing proceeds to step S605. On the other hand, in the case where the control unit 30 determines that the rear end identification color patch 501 is not included in the lower part of the input image ("No" in step S602), the processing proceeds to step S603. In step S603, the control unit 30 determines whether the rear end identification color patch 501 is included in the upper part of the input image. In the case where the chart 100 is set on the reading device 80 in the orientation opposite to the normal orientation, the upper part of the input image is a position corresponding to the rear end in the conveying direction of the recording material S when the chart 100 is formed.

[0147] In the case where the control unit 30 determines that the rear end identification color patch 501 is included in the upper part of the input image ("Yes" in step S603), the processing proceeds to step S604. In step S604, the control unit 30 rotates the input image by 180 degrees, and stores the rotated image in the RAM 33. Then, the processing proceeds to step S605. In other words, the control unit 30 optimizes the orientation of the input image stored in the RAM 33 in such a manner as to be the orientation of the chart 100 read in the normal orientation. On the other hand, in the case where the control unit 30 determines that the rear end identification color patch 501 is not included in the upper part of the input image ("No" in step S603), the control unit 30 determines that the chart 100 set on the reading device 80 is not the chart 100 for adjusting the secondary transfer voltage, and the processing proceeds to step S608. In step S608, the control unit 30 displays information indicating that an error has occurred on the display unit of the operation unit 70 or the external device 200, and ends the adjustment mode.

[0148] In step S605, the control unit 30 performs pixel scanning of the image including the lower rear end identification color block 501 stored in the RAM 33 from the position of the detected rear end identification color block 501, and detects the page determination color block 502. In step S606, the control unit 30 determines the page of the input image based on the luminance information (i.e., the determination result of the color) of the detected page determination color block 502, and corrects the order of the input images when necessary. In other words, the control unit 30 optimizes the association between each input image stored in the RAM 33 and the reading order in such a manner as to provide a relationship between each chart 100 and the reading order as set in the case where the charts 100 are read in the regular order. In the case where the order of the input images is the regular order, there is no need to correct the order. Thereafter, in step S607, the control unit 30 advances the processing to the step already described in the first exemplary embodiment (refer to Fig.10 ) is a process for determining a recommended adjustment value of a secondary transfer voltage.

[0149] Fig.18 is an explanatory diagram illustrating the effects of the present exemplary embodiment. Fig.18 An example case where two double-sided small charts are output and read by the reading device 80 is illustrated. Fig.18 The input image listed in (a) is an input image obtained by rearranging the chart 100 in such a manner that the arrangement (orientation) of the chart 100 and the reading order (pages) of the chart 100 become different from the conventional arrangement and reading order, and reading the chart 100 by the reading device 80. Fig.18 The input images listed in (b) are input images obtained by correcting the arrangement of the charts 100 and the reading order of the charts 100 according to the present exemplary embodiment. Fig.18 As shown in , the orientation of the chart 100 and the reading order of the chart 100 can be optimized based on the back-end identification patch 501 and the page determination patch 502 formed on the chart 100 and used as identification information.

[0150] In the present exemplary embodiment, the identification information 501 indicating the conventional arrangement (orientation) of the chart 100 is formed at the rear end in the conveying direction of the recording material S when the chart 100 is formed, but the present disclosure is not limited to this configuration. The identification information 501 indicating the conventional arrangement (orientation) of the chart 100 may be formed, for example, at the front end in the conveying direction of the recording material S when the chart 100 is formed, or at the end in the direction intersecting the conveying direction. In the present exemplary embodiment, the identification information 502 indicating the conventional reading order (page) of the chart 100 is formed at a position different from the position of the identification information 501 indicating the conventional arrangement (orientation) of the chart 100 in the main scanning direction and at least partially overlapping with the identification information 501 in the sub-scanning direction. In other words, in the present exemplary embodiment, the page determination color block 502 and the rear end identification color block 501 are formed side by side in the main scanning direction. With this configuration, the space on the surface of the recording material S on which the chart 100 is formed can be more effectively utilized to form a test image for density detection. However, the present disclosure is not limited to this configuration. Identification information 502 indicating the normal reading order (pages) of chart 100 may be formed, for example, at a position different from that of identification information 501 indicating the normal arrangement (orientation) of chart 100 in the sub-scanning direction (at least partially overlapping or different position in the main scanning direction).

[0151] In the present exemplary embodiment, identification information 501 indicating the conventional arrangement (orientation) of the chart 100 and identification information 502 indicating the conventional reading order (page) of the chart 100 are provided separately. However, the present disclosure is not limited to this configuration. The identification information 501 indicating the conventional arrangement (orientation) of the chart 100 and the identification information 502 indicating the conventional reading order (page) of the chart 100 can be formed integrally. For example, similar to the page determination color block 502 in the present exemplary embodiment, a strip image similar to the rear end identification color block 501 in the present exemplary embodiment can be formed in a different color for each chart. Any one of the identification information 501 indicating the conventional arrangement (orientation) of the chart 100 and the identification information 502 indicating the conventional reading order (page) of the chart 100 can be provided. In this case as well, at least one of the conventional arrangement (orientation) of the chart 100 or the conventional reading order (page) of the chart 100 can be determined, and an equivalent effect can be obtained.

[0152] As described above, in the present exemplary embodiment, in the adjustment mode, the control unit 30 may form the chart 100 on both surfaces of one recording material S as the plurality of surfaces of the recording material S and discharge the recording material S from the discharge unit 48, or form the chart 100 on one surface or both surfaces of a plurality of recording materials S as the plurality of surfaces of the recording material S and discharge the plurality of recording materials S from the discharge unit 48, read density information of the test images of the chart 100 on the above-mentioned plurality of surfaces of the recording material S simultaneously set on the reading device 80 by the operator using the reading device 80, and output information on the adjustment amount of the secondary transfer voltage based on the reading result obtained by the reading device 80. In the present exemplary embodiment, the identification information 501 or 502 indicating at least one of the normal orientation of the chart 100 on each of the above-mentioned plurality of surfaces or the normal reading order in the reading device 80 of the chart 100 formed on the above-mentioned plurality of surfaces is formed on each of the above-mentioned plurality of surfaces. Then, the control unit 30 outputs information about the adjustment amount of the secondary transfer voltage based on the reading results of the density information of the test image on the chart 100 on the above multiple surfaces obtained by the reading device 80 and the reading results of the identification information 501 or 502 on the above multiple surfaces obtained by the reading device 80.

[0153] Thus, according to the present exemplary embodiment, effects similar to those of the first exemplary embodiment can be obtained, and problems caused by errors in the arrangement of the charts 100 or the reading order of the charts 100 can be prevented.

[0154] [other]

[0155] Heretofore, specific exemplary embodiments of the present disclosure have been described, but the present disclosure is not limited to the above-mentioned exemplary embodiments.

[0156] In the above exemplary embodiments, the secondary transfer voltage is adjusted using an adjustment value corresponding to a predetermined adjustment amount. For example, the adjustment amount may be directly set via a setting screen.

[0157] In the above exemplary embodiments, a configuration in which constant voltage control of the secondary transfer voltage is performed has been described, but constant current control of the secondary transfer voltage may be performed. In the above exemplary embodiments, in the configuration in which constant voltage control of the secondary transfer voltage is performed, the secondary transfer voltage is adjusted by adjusting the target voltage when the secondary transfer voltage is applied in the adjustment mode. In the configuration in which constant current control of the secondary transfer voltage is performed, the secondary transfer voltage may be adjusted by adjusting the target current when the secondary transfer voltage is applied in the adjustment mode.

[0158] In the above exemplary embodiments, a description has been given of a case where a chart is output by forming on two recording materials in a case where the size of the recording material is a small size. The present disclosure can also be applied to a case where a chart is output by forming on three or more recording materials. The first chart and the second chart in the present disclosure include charts formed on any two recording materials (first and second recording materials) in a case where a chart is output by forming on three or more recording materials.

[0159] The present disclosure is not limited to a tandem image forming apparatus, and may also be applied to an image forming apparatus of another system. The image forming apparatus is not limited to a full-color image forming apparatus, and may be a monochrome or single-color image forming apparatus. The present disclosure may be applied to various intended uses, such as printers, various printing machines, copiers, fax machines, and multi-function peripherals.

[0160] According to an exemplary embodiment of the present disclosure, usability can be enhanced by reducing the number of times a chart is placed on a reading device.

[0161] While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the present disclosure is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An image forming device, comprising: an image bearing member configured to bear a toner image; a transfer member configured to transfer the toner image from the image bearing member to a recording material; an applying unit configured to apply a voltage to the transfer member; a platen on which a recording material is disposed when an image on the recording material is to be read; a reading device configured to read an image on a recording material disposed on the platen; as well as a control unit configured to execute an adjustment mode for adjusting a transfer voltage to be applied to the transfer member, wherein, in the adjustment mode, the control unit outputs a first chart formed by applying a plurality of first test voltages to the transfer member to transfer a plurality of first test images to a first recording material, and a second chart formed by applying a plurality of second test voltages to the transfer member to transfer a plurality of second test images to a second recording material, and the control unit is configured to adjust the transfer voltage applied to the transfer member based on a reading result of the reading device when the reading device reads the first recording material and the second recording material set together on the platen, wherein first identification information is formed on the surface on which the first test image is formed, and second identification information is formed on the surface on which the second test image is formed, the first identification information is used to identify the orientation of the first chart, the second identification information is used to identify the orientation of the second chart, and The control unit is configured to adjust the transfer voltage based on a reading result of the first test image, the second test image, the first identification information, and the second identification information obtained by the reading device.

2. An image forming device, comprising: an image bearing member configured to bear a toner image; a transfer member configured to transfer the toner image from the image bearing member to a recording material; an applying unit configured to apply a voltage to the transfer member; a platen on which a recording material is disposed when an image on the recording material is to be read; a reading device configured to read an image on a recording material disposed on the platen; as well as a control unit configured to execute an adjustment mode for adjusting a transfer voltage to be applied to the transfer member, wherein, in the adjustment mode, the control unit outputs a first chart formed by applying a plurality of first test voltages to the transfer member to transfer a plurality of first test images to a first recording material, and a second chart formed by applying a plurality of second test voltages to the transfer member to transfer a plurality of second test images to a second recording material, and the control unit is configured to adjust the transfer voltage applied to the transfer member based on a reading result of the reading device when the reading device reads the first recording material and the second recording material set together on the platen, wherein first identification information is formed on the surface on which the first test image is formed, and second identification information is formed on the surface on which the second test image is formed, the first identification information is used to identify page information of the first chart, the second identification information is used to identify page information of the second chart, and The control unit is configured to adjust the transfer voltage based on a reading result of the first test image, the second test image, the first identification information, and the second identification information obtained by the reading device. 3 . The image forming apparatus according to claim 1 , further comprising a display unit configured to display information in the adjustment mode, the information prompting an operator to set the discharged first recording material and second recording material together on the platen.

4. An image forming device, comprising: an image bearing member configured to bear a toner image; a transfer member configured to transfer the toner image from the image bearing member to a recording material; an applying unit configured to apply a voltage to the transfer member; a reading device configured to read density information of an image on a recording material; as well as a control unit configured to execute an adjustment mode for adjusting a transfer voltage to be applied to the transfer member, wherein, in the adjustment mode, the control unit outputs a first chart and a second chart, the first chart being formed by applying a plurality of first test voltages to the transfer member to transfer a plurality of first test images to a first recording material, the second chart being formed by applying a plurality of second test voltages to the transfer member to transfer a plurality of second test images to a second recording material, and the control unit forms first identification information on a surface on which the first test images are formed, and forms second identification information on a surface on which the second test images are formed, the first identification information being used to identify an orientation of the first chart, and the second identification information being used to identify an orientation of the second chart, Wherein, regardless of the orientation of the first recording material and the orientation of the second recording material when the reading device reads the first recording material and the second recording material, the control unit is configured to adjust the transfer voltage based on the reading results of the first test image, the second test image, the first identification information, and the second identification information obtained by the reading device.

5. The image forming apparatus according to claim 4, wherein third identification information is formed on the surface on which the first test image is formed, and fourth identification information is formed on the surface on which the second test image is formed, the third identification information being used to identify a page of the first chart, the fourth identification information being used to identify a page of the second chart, and wherein the control unit is configured to adjust the transfer voltage based on a reading result of the third identification information and the fourth identification information obtained by the reading device.

6. An image forming device according to claim 4, wherein the reading device includes a platen on which a recording material is deployed, and in the adjustment mode, the control unit is configured to adjust the transfer voltage applied to the transfer member based on a reading result when the reading device reads the first recording material and the second recording material set together on the platen.

7. An image forming device according to claim 4, wherein the reading device includes a conveying part and a reading part, the conveying part is configured to sequentially and automatically convey the first recording material and the second recording material to the reading part, the reading part is configured to read the image on the recording material sequentially and automatically conveyed by the conveying part, and in the adjustment mode, the control unit is configured to adjust the transfer voltage applied to the transfer member based on the reading result when the reading part reads the first recording material and the second recording material sequentially and automatically conveyed by the conveying part. 8 . The image forming apparatus according to claim 4 , wherein the first identification information and the second identification information are band-shaped patch images formed using black toner. 9 . The image forming apparatus according to claim 5 , wherein the third identification information and the fourth identification information are patch images formed using toners of different colors. 10 . The image forming apparatus according to claim 5 , wherein the first identification information and the third identification information are formed at different positions.

11. The image forming apparatus according to claim 10, wherein: The first identification information and the third identification information are arranged in a width direction orthogonal to an arrangement direction of the plurality of test images.

12. The image forming apparatus according to claim 6, wherein: In the adjustment mode, regardless of whether the first recording material is set on the platen in a first direction or the first recording material is set on the platen in a second direction opposite to the first direction, the control unit is configured to adjust the transfer voltage based on the first test image, the second test image, the first identification information, and the reading results of the second identification information obtained by the reading device.

13. An image forming device comprising: an image bearing member configured to bear a toner image; a transfer member configured to transfer the toner image from the image bearing member to a recording material; an applying unit configured to apply a voltage to the transfer member; a reading device configured to read an image on a recording material; as well as a control unit configured to execute an adjustment mode for adjusting a transfer voltage to be applied to the transfer member, wherein, in the adjustment mode, the control unit outputs a first chart and a second chart, the first chart being formed by applying a plurality of first test voltages to the transfer member to transfer a plurality of first test images to a first recording material, the second chart being formed by applying a plurality of second test voltages to the transfer member to transfer a plurality of second test images to a second recording material, and the control unit forms first identification information on a surface on which the first test images are formed, and forms second identification information on a surface on which the second test images are formed, the first identification information being used to identify a page of the first chart, and the second identification information being used to identify a page of the second chart, and Wherein, regardless of the reading order in which the reading device reads the first recording material and the second recording material, the control unit is configured to adjust the transfer voltage based on the reading results of the first test image and the second test image, and the first identification information and the second identification information obtained by the reading device.

14. An image forming device according to claim 13, wherein the reading device includes a platen on which a recording material is deployed, and in the adjustment mode, the control unit is configured to adjust the transfer voltage applied to the transfer member based on a reading result when the reading device reads the first recording material and the second recording material set together on the platen.

15. An image forming device according to claim 13, wherein the reading device includes a conveying part and a reading part, the conveying part is configured to sequentially and automatically convey the first recording material and the second recording material to the reading part, the reading part is configured to read the image on the recording material sequentially and automatically conveyed by the conveying part, and in the adjustment mode, the control unit is configured to adjust the transfer voltage applied to the transfer member based on the reading result when the reading part reads the first recording material and the second recording material sequentially and automatically conveyed by the conveying part.

16. The image forming apparatus according to claim 14, wherein: In a case where the first recording material or the second recording material is arranged in an order different from a normal page order, the control unit is configured to adjust the transfer voltage based on a reading result of the first test image, the second test image, the first identification information, and the second identification information obtained by the reading device.

Images