JP2022161752A - Image forming apparatus - Google Patents

Abstract

To allow execution of a first mode in which an image forming apparatus can form a toner image in multiple colors and a second mode in which the image forming apparatus forms a monochrome toner image, and to allow appropriate adjustment of transfer voltage in the first mode and the second mode through an adjustment mode.SOLUTION: An image forming apparatus has an image carrier, a plurality of image forming units, and a transfer member, and can execute a first mode in which the image forming apparatus can form a toner image with at least two image forming units to perform image formation and a second mode in which the image forming apparatus performs image formation with one image forming unit, and the image forming apparatus has: an execution unit that executes an output operation of outputting a chart for adjusting transfer voltage that is applied to the transfer member by an application unit during the image formation; a storage unit that stores first information on the amount of adjustment of the transfer voltage in the first mode and second information on the amount of adjustment of the transfer voltage in the second mode, which are set through the execution of the output operation; and a setting unit that sets the transfer voltage during the image formation based on the stored information.SELECTED DRAWING: Figure 8

Description

The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile machine using an electrophotographic method or an electrostatic recording method.

2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic method or the like, a toner image is electrostatically transferred from an image carrier onto a recording material such as paper. This transfer is often performed by applying a transfer voltage to a transfer member that forms a transfer portion in contact with the image bearing member. In an intermediate transfer type image forming apparatus, a toner image formed on a first image carrier such as a photosensitive drum is primarily transferred onto a second image carrier such as an intermediate transfer belt, and then transferred onto a recording material. Secondarily transcribed. In an intermediate transfer type color image forming apparatus, for example, toner images of four colors are primarily transferred onto a second image carrier so as to be superimposed, and then secondarily transferred onto a recording material. In the following, the secondary transfer in the intermediate transfer type image forming apparatus will be further described as an example.

In order to obtain a high-quality image product, it is important to set the secondary transfer voltage to an appropriate value when the toner image on the intermediate transfer member is electrostatically transferred onto the recording material. If the secondary transfer voltage is not sufficient for the charge amount of the toner on the intermediate transfer member, the toner image cannot be sufficiently transferred from the intermediate transfer member to the recording material, and the desired image density cannot be obtained. It may disappear. This image defect is sometimes referred to as "boso". Also, if the secondary transfer voltage is too high, a discharge occurs at the secondary transfer portion, and the discharge reverses the charging polarity of the toner on the intermediate transfer body, resulting in a toner image on the intermediate transfer body. A part of the image may not be transferred onto the recording material and the image may be partially whitened. This image defect is sometimes called "punch-through".

The secondary transfer voltage consists of a transfer partial charge voltage corresponding to the electric resistance of the secondary transfer portion detected in the pre-rotation process before image formation, and a recording material share voltage corresponding to the preset recording material type. , can be determined based on This makes it possible to set an appropriate secondary transfer voltage according to environmental fluctuations, use history of the transfer member, type of recording material, and the like. However, since there are various kinds and conditions of recording materials used for image formation, depending on the recording material, the preset default recording material apportionment voltage may cause an excess or deficiency in the secondary transfer voltage. Therefore, it has been proposed to provide an image forming apparatus with an adjustment mode that makes it possible to adjust the set value of the secondary transfer voltage according to the recording material actually used for image formation.

Japanese Unexamined Patent Application Publication No. 2002-200003 proposes an image forming apparatus having an adjustment mode for adjusting the set value of the secondary transfer voltage. In this adjustment mode, a chart (adjustment chart) obtained by transferring a plurality of patches (test images) onto one sheet of recording material while switching the secondary transfer voltage (test voltage) for each patch is output. This chart is read by a reading unit provided in the image forming apparatus, and the density of each patch is detected. Appropriate secondary transfer voltage conditions are selected according to the detection result. In addition, in this adjustment mode, control is performed so that the secondary transfer voltage is selected so that both the density of the single-color patch and the density of the multi-color patch are favorable.

JP 2013-37185 A

However, the above conventional adjustment mode has the following problems.

The image forming apparatus is configured to be capable of forming images in a full-color mode in which, for example, toner images of four colors are superimposed to form a full-color image, and in a monochrome mode in which a monochromatic image such as a black monochromatic image is formed. There is In such a configuration, there is a relatively large discrepancy between the set value of the secondary transfer voltage at which the density of the single-color patch is good and the set value of the secondary transfer voltage at which the density of the multi-color patch is good. There may be In this case, in the above-described conventional adjustment mode, the secondary transfer voltage is selected so that both the density of the single-color patch and the density of the multi-color patch are good. There is a possibility that it will not be the next transfer voltage.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a configuration capable of executing a first mode capable of forming a multi-color toner image and a second mode capable of forming a single-color toner image, in which the first mode is controlled by an adjustment mode. and the transfer voltage in the second mode can be appropriately adjusted.

The above objects are achieved by an image forming apparatus according to the present invention. In summary, the present invention comprises an image carrier that carries a toner image, a plurality of image forming units that form a toner image on the image carrier with toner, and a toner image that is transferred from the image carrier to a recording material. and an applying unit for applying a voltage to the transfer member. At least two image forming units out of the plurality of image forming units superimpose toner on the image carrier. a first mode in which the toner image thus formed is transferred onto a recording material by the transfer unit to form an image; and a second mode of forming an image by transferring the toner image formed in the transfer section onto a recording material, wherein a test image is formed on the image carrier with toner, The applying unit applies a test voltage to the transfer member to transfer the test image onto a recording material, and outputs a chart for adjusting the transfer voltage applied to the transfer member by the applying unit during image formation. an execution unit that executes an output operation to perform the output operation, first information regarding an adjustment amount of the transfer voltage in the first mode, which is set by executing the output operation, and an adjustment amount of the transfer voltage in the second mode; and a setting unit for setting the transfer voltage during image formation based on the information stored in the storage unit. It is an image forming apparatus.

According to the present invention, in a configuration capable of executing a first mode capable of forming a multi-color toner image and a second mode capable of forming a single-color toner image, the first mode and the second mode are selected according to the adjustment mode. mode can be appropriately adjusted.

1 is a schematic cross-sectional view of an image forming apparatus; FIG. 3 is a block diagram showing a control system of the image forming apparatus; FIG. FIG. 5 is a flow chart diagram showing an outline of a procedure for controlling a secondary transfer voltage; FIG. 5 is a graph showing voltage-current characteristics obtained by controlling the secondary transfer voltage; 3 is a schematic diagram showing an example of a table of recording material allotted voltages; FIG. FIG. 4 is a schematic diagram of a chart output in adjustment mode; FIG. 4 is a schematic diagram of a chart output in adjustment mode; It is a flowchart figure which shows an example of the procedure of adjustment mode. FIG. 5 is a schematic diagram showing an example of a recording material setting screen; 8A and 8B are schematic diagrams showing examples of (a) a secondary transfer voltage adjustment screen (before chart output) and (b) a secondary transfer voltage adjustment screen (after chart output). FIG. 10 is a graph showing an example of the relationship between the average luminance value of patches and the adjustment value of the secondary transfer voltage obtained in the adjustment mode; FIG. 5 is a schematic diagram for explaining an example of a storage mode of an adjustment value of a secondary transfer voltage; and FIG. 11 is a schematic cross-sectional view of another example of an image forming apparatus. FIG. 10 is a schematic diagram showing an example of a storage unit setting screen for recording materials; 8A and 8B are schematic diagrams showing other examples of (a) a secondary transfer voltage adjustment screen (before chart output) and (b) a secondary transfer voltage adjustment screen (after chart output). FIG. 10 is a schematic diagram for explaining another example of the storage mode of the adjustment value of the secondary transfer voltage; FIG. 10 is a flow chart diagram showing another example of the procedure of the adjustment mode;

Hereinafter, the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

[Example 1]
1. 1. Configuration and Operation of Image Forming Apparatus FIG. 1 is a schematic cross-sectional view of an image forming apparatus 1 of this embodiment. The image forming apparatus 1 of this embodiment has the functions of a tandem-type multifunction machine (copier, printer, and facsimile machine) employing an intermediate transfer system capable of forming a full-color image using an electrophotographic system. ).

As shown in FIG. 1, the image forming apparatus 1 includes an apparatus main body 10, a reading section 80, a feeding section 90, a printer section 40, a discharge section 48, a control section 30, an operation section 70, and the like. Further, inside the apparatus body 10, there are provided a temperature sensor 71 (FIG. 2) capable of detecting the temperature inside the apparatus, a humidity sensor 72 (FIG. 2) capable of detecting the humidity inside the apparatus, and the like. The image forming apparatus 1 forms a four-color full-color image on a recording material (sheet, transfer material, recording medium, medium) according to image information (image signals) from the reading unit 80 or the external device 200 (FIG. 2). be able to. Examples of the external device 200 include a host device such as a personal computer, a digital camera, a smart phone, and the like. The recording material S is a material on which a toner image is formed, and specific examples thereof include plain paper, a synthetic resin sheet that is a substitute for plain paper, cardboard, and an overhead projector sheet.

The printer section 40 can form an image on the recording material S fed from the feeding section (feeding device) 90 based on image information. The printer section 40 has four image forming units 50y, 50m, 50c and 50k as a plurality of image forming sections, and four toner bottles 41y, 41m, 41c and 41k. The printer section 40 also has an intermediate transfer unit 44 , a secondary transfer device 45 , and a fixing section 46 . The image forming units 50y, 50m, 50c, and 50k form yellow (Y), magenta (M), cyan (C), and black (K) images, respectively. For elements having the same or corresponding functions or configurations provided corresponding to each color, y, m, c, k at the end of the code indicating that it is an element for any color may be explained. Note that the image forming apparatus 1 can also use a desired single or several image forming units 50 to form a single-color image such as a black single-color image or a multi-color image.

The image forming unit 50 has the following units. First, it has a photosensitive drum 51 which is a drum-shaped (cylindrical) photosensitive member (electrophotographic photosensitive member) as a first image carrier. It also has a charging roller 52 which is a roller-type charging member as charging means. It also has an exposure device 42 as exposure means. It also has a developing device 20 as developing means. It also has a pre-exposure device 54 as a static eliminating means. It also has a drum cleaning device 55 as a photoreceptor cleaning means. The image forming unit 50 forms a toner image on an intermediate transfer belt 44b, which will be described later. In the image forming unit 50, the photosensitive drum 51, the charging roller 52 acting on the photosensitive drum 51, the developing device 20, and the drum cleaning device 55 are integrally unitized and detachable from the apparatus main body 10. Constructs a process cartridge.

The photosensitive drum 51 is movable (rotatable) while carrying an electrostatic image (electrostatic latent image) or a toner image. The photosensitive drum 51 is a negatively charged organic photoconductor (OPC) having an outer diameter of 30 mm in this embodiment. The photosensitive drum 51 has an aluminum cylinder as a base and a surface layer formed on the surface thereof. In this embodiment, the surface layer has three layers, an undercoat layer, a photocharge generation layer, and a charge transport layer, which are coated and laminated on the substrate in the following order. When the image forming operation is started, the photosensitive drum 51 is rotationally driven in the arrow direction (counterclockwise direction) at a predetermined process speed (peripheral speed) by a motor (not shown) as driving means. be.

The surface of the rotating photosensitive drum 51 is uniformly charged to a predetermined potential with a predetermined polarity (negative polarity in this embodiment) by the charging roller 52 . In this embodiment, the charging roller 52 is a rubber roller that contacts the surface of the photosensitive drum 51 and rotates following the rotation of the photosensitive drum 51 . A charging power supply 73 (FIG. 2) is connected to the charging roller 52 . The charging power supply 73 applies a predetermined charging voltage (charging bias) to the charging roller 52 during the charging process.

The charged surface of the photosensitive drum 51 is scanned and exposed by the exposure device 42 based on image information, and an electrostatic image is formed on the photosensitive drum 51 . In this embodiment, the exposure device 42 is a laser scanner. The exposure device 42 emits a laser beam in accordance with the separated color image information output from the control unit 30 to scan and expose the surface (outer peripheral surface) of the photosensitive drum 51 .

The electrostatic image formed on the photosensitive drum 51 is developed (visualized) by supplying toner from the developing device 20 to form a toner image on the photosensitive drum 51 . In this embodiment, the developing device 20 contains a two-component developer comprising non-magnetic toner particles (toner) and magnetic carrier particles (carrier) as the developer. Toner is supplied from a toner bottle 41 to the developing device 20 . The developing device 20 has a developing sleeve 24 . The developing sleeve 24 is made of a non-magnetic material such as aluminum or non-magnetic stainless steel (aluminum in this embodiment). A magnet roller, which is a roller-shaped magnet, is arranged inside the developing sleeve 24 so as not to rotate with respect to the main body (developing container) of the developing device 20 . The developing sleeve 24 carries developer and conveys it to a developing area facing the photosensitive drum 51 . A developing power supply 74 (FIG. 2) is connected to the developing sleeve 24 . The development power supply 74 applies a predetermined development voltage (development bias) to the development sleeve 24 during the development process. In this embodiment, the exposure portion (image portion) on the photosensitive drum 51, in which the absolute value of the potential is lowered by being exposed after being uniformly charged, is provided with the same polarity as the charging polarity of the photosensitive drum 51 (this embodiment). In the example, negatively charged toner adheres (reversal development). In this embodiment, the normal charge polarity of the toner, which is the charge polarity of the toner during development, is negative.

An intermediate transfer unit 44 is arranged to face the four photosensitive drums 51y, 51m, 51c, and 51k. The intermediate transfer unit 44 has an intermediate transfer belt 44b, which is an intermediate transfer member formed of an endless belt as a second image bearing member. The intermediate transfer belt 44b is wound around a driving roller 44a, a driven roller 44d, and a secondary transfer inner roller 45a as a plurality of tension rollers (support rollers), and is stretched with a predetermined tension. The intermediate transfer belt 44b carries a toner image and is movable (rotatable). The driving roller 44a is rotationally driven by a motor (not shown) as driving means. 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 is applied with a force that pushes the intermediate transfer belt 44b from the inner peripheral surface side to the outer peripheral surface side by the urging force of a tension spring (not shown) that is an urging member as an urging means. . This force applies a tension of about 2 to 5 kg in the conveying direction of the intermediate transfer belt 44b. The inner secondary transfer roller 45a constitutes a secondary transfer device 45 as described later. The driving roller 44a is rotationally driven to input a driving force to the intermediate transfer belt 44b, and the intermediate transfer belt 44b rotates in the arrow direction (clockwise direction) at a predetermined peripheral speed corresponding to the peripheral speed of the photosensitive drum 51 ( move around). Primary transfer rollers 47y, 47m, and 47c, which are roller-type primary transfer members as primary transfer means, are provided on the inner peripheral surface side of the intermediate transfer belt 44b corresponding to the respective photosensitive drums 51y, 51m, 51c, and 51k. , 47k are arranged. The primary transfer roller 47 sandwiches the intermediate transfer belt 44 b between itself and the photosensitive drum 51 . As a result, the primary transfer roller 47 contacts the photosensitive drum 51 via the intermediate transfer belt 44b, forming a primary transfer portion (primary transfer nip) N1 where the photosensitive drum 51 and the intermediate transfer belt 44b contact.

The toner image formed on the photosensitive drum 51 is primarily transferred onto the rotating intermediate transfer belt 44b at the primary transfer portion N1. A primary transfer power supply 75 (FIG. 2) is connected to the primary transfer roller 47 . During the primary transfer process, the primary transfer power supply 75 applies a primary transfer voltage (primary transfer bias), which is a DC voltage having a polarity (positive polarity in this embodiment) opposite to the normal charge polarity of the toner, to the primary transfer roller 47 . . For example, when forming a full-color image, yellow, magenta, cyan, and black toner images formed on the photosensitive drums 51y, 51m, 51c, and 51k are superimposed on the intermediate transfer belt 44b in sequence. Primary transfer. A voltage detection sensor 75a for detecting an output voltage and a current detection sensor 75b for detecting an output current are connected to the primary transfer power source 75 (FIG. 2). In this embodiment, the primary transfer power sources 75y, 75m, 75c, and 75k are provided for the primary transfer rollers 47y, 47m, 47c, and 47k, respectively, and are applied to the primary transfer rollers 47y, 47m, 47c, and 47k. Each primary transfer voltage can be individually controlled.

Here, in this embodiment, the primary transfer roller 47 has an elastic layer of ion conductive foamed rubber (NBR rubber) and a core metal. The outer diameter of the primary transfer roller 47 is, for example, 15-20 mm. Further, as the primary transfer roller 47, a roller having an electrical resistance value of 1×10 ⁵ to 1×10 ⁸ Ω (N/N (23° C., 50% RH) measurement, 2 kV applied) can be preferably used. . Further, in this 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 the following order from the inner peripheral surface side to the outer peripheral surface side. be. As a material constituting the base layer, a material obtained by adding an appropriate amount of carbon black as an antistatic agent to a resin such as polyimide or polycarbonate or various rubbers can be suitably used. The thickness of the base layer is, for example, 0.05-0.15 mm. As the elastic material constituting the elastic layer, a material obtained by adding an appropriate amount of an ionic conductive agent to various rubbers such as urethane rubber and silicone rubber can be suitably used. The thickness of the elastic layer is, for example, 0.1-0.500 mm. A resin such as a fluororesin can be suitably used as the material forming the surface layer. The surface layer reduces the adhesive force of the toner to the surface of the intermediate transfer belt 44b, thereby facilitating the transfer of the toner onto the recording material S at the secondary transfer portion N2, which will be described later. The thickness of the surface layer is, for example, 0.0002-0.020 mm. In this embodiment, the surface layer is made of, for example, one type of resin material such as polyurethane, polyester, or epoxy resin, or two or more types of elastic materials such as elastic material rubber, elastomer, or butyl rubber. . Then, one or two or more kinds of powders or particles such as fluororesin are dispersed in the substrate as a material that reduces the surface energy and enhances the lubricity, or with different particle diameters. , forming the surface layer. In this embodiment, the intermediate transfer belt 44b has a volume resistivity of 5×10 ⁸ to 1×10 ¹⁴ Ω·cm (23° C., 50% RH) and a hardness of 60 to 85° (23° C., 50% RH) in MD1 hardness. % RH). In this embodiment, the static friction coefficient of the intermediate transfer belt 44b is 0.15 to 0.6 (23° C., 50% RH, type 94i manufactured by HEIDON). Although the intermediate transfer belt 44b has a three-layer structure in this embodiment, it may have a single-layer structure of a material corresponding to the base layer described above.

A secondary transfer outer roller 45b, which is a roller-type secondary transfer member serving as a secondary transfer unit, is arranged on the outer peripheral surface side of the intermediate transfer belt 44b, which constitutes the secondary transfer device 45 together with the secondary transfer inner roller 45a. It is The secondary transfer outer roller 45b sandwiches the intermediate transfer belt 44b with the secondary transfer inner roller 45a. As a result, the secondary transfer outer roller 45b contacts the secondary transfer inner roller 45a via the intermediate transfer belt 44b, and the intermediate transfer belt 44b and the secondary transfer outer roller 45b contact the secondary transfer portion (secondary transfer roller 45b). Nip) N2 is formed. The toner image formed on the intermediate transfer belt 44b is secondarily transferred at the secondary transfer portion N2 onto the recording material S that is conveyed while being sandwiched between the intermediate transfer belt 44b and the secondary transfer outer roller 45b. . In this embodiment, a secondary transfer voltage (secondary transfer bias) is applied to the secondary transfer outer roller 45b during the secondary transfer process.

As described above, in this embodiment, the secondary transfer device 45 includes the inner secondary transfer roller 45a as a facing member and the outer secondary transfer roller 45b as a secondary transfer member. The inner secondary transfer roller 45a is arranged to face the outer secondary transfer roller 45b via the intermediate transfer belt 44b. The secondary transfer outer roller 45b is connected to a secondary transfer power supply 76 (FIG. 2) as voltage applying means (applying section). During the secondary transfer process, the secondary transfer power supply 76 applies a secondary transfer voltage (secondary transfer bias) is applied. A voltage detection sensor 76a for detecting an output voltage and a current detection sensor 76b for detecting an output current are connected to the secondary transfer power source 76 (FIG. 2). Further, in this embodiment, the core metal of the inner secondary transfer roller 45a is connected to the ground potential. That is, in this embodiment, the inner secondary transfer roller 45a is electrically grounded (connected to the ground). When the recording material S is supplied to the secondary transfer portion N2, a constant-voltage-controlled secondary transfer voltage having a polarity opposite to the normal charge polarity of the toner is applied to the secondary transfer outer roller 45b. In this embodiment, a secondary transfer voltage of, for example, 1 to 7 kV is applied, and a current of 40 to 120 μA is applied to secondarily transfer the toner image on the intermediate transfer belt 44b onto the recording material S. FIG. In this embodiment, the secondary transfer power supply 76 applies a DC voltage to the secondary transfer outer roller 45b to apply the secondary transfer voltage to the secondary transfer portion N2. It is not limited. For example, the secondary transfer voltage may be applied to the secondary transfer portion N2 by the secondary transfer power source 76 applying a DC voltage to the inner secondary transfer roller 45a. In this case, a DC voltage having the same polarity as the normal charging polarity of the toner is applied to the inner secondary transfer roller 45a as the secondary transfer member, and the outer secondary transfer roller 45b as the opposing member is electrically grounded. In this embodiment, the secondary transfer outer roller 45b has an elastic layer of ion conductive foamed rubber (NBR rubber) and a core bar. 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 roller having an electrical resistance value of 1×10 ⁵ to 1×10 ⁸ Ω (N/N (23° C., 50% RH) measurement, 2 kV applied) is preferably used. can be done.

The recording material S is fed from the feeding unit 90 in parallel with the above-described toner image forming operation. That is, the recording material S is stacked and stored in a recording material cassette 91 as a recording material storage portion. In this embodiment, the image forming apparatus 1 is provided with a plurality of recording material cassettes 91 (91a, 91b) in which the recording materials S are stored respectively. The recording material S accommodated in each recording material cassette 91 is sent out to a conveying path 93 by feeding rollers 92 (92a, 92b) serving as feeding members. The recording material S sent out to the transport path 93 is transported to a registration roller pair 43 as a transport member by a transport roller pair 94 as a transport member. The recording material S is corrected for skew by the pair of registration rollers 43, and supplied to the secondary transfer portion N2 in synchronization with the toner image on the intermediate transfer belt 44b. A feeding unit 90 is configured by the recording material cassette 91, the feeding roller 92, the conveying path 93, the pair of conveying rollers 94, and the like.

The recording material S onto which the toner image has been transferred is conveyed to a fixing section (fixing device) 46 as fixing means. The fixing section 46 has a fixing roller 46a and a pressure roller 46b. The fixing roller 46a incorporates a heater as a heating means. The recording material S bearing the unfixed toner image is heated and pressurized by being pinched and conveyed between the fixing roller 46a and the pressure roller 46b. As a result, the toner image is fixed (melted, fixed) on the recording material S. As shown in FIG. The temperature (fixing temperature) of the fixing roller 46a is detected by a fixing temperature sensor 77 (FIG. 2).

The recording material S on which the toner image is fixed is conveyed through a discharge path 48a by a pair of discharge rollers 48b serving as a conveying member, and is discharged (output) from a discharge port 48c. 48d is loaded. A discharge section (discharge device) 48 is configured by the discharge path 48a, the discharge roller pair 48b, the discharge port 48c, the discharge tray 48d, and the like. In this embodiment, the image forming apparatus 1 is capable of double-sided image formation (double-sided printing, automatic double-sided printing) for forming images on both sides of the recording material S. FIG. Between the fixing section 46 and the discharge port 48c, there is a reversing conveying path 12 for turning over the recording material S after the toner image has been fixed on the first side and feeding it again to the secondary transfer section N2. is provided. During double-sided image formation, the recording material S on which the toner image has been fixed on the first side is guided to the reverse conveying path 12 . The conveying direction of the recording material S is reversed by a pair of switchback rollers 13 provided on the reversing conveying path 12 and guided to the double-sided conveying path 14 . Then, the recording material S is sent to the conveying path 93 by the re-conveying roller pair 15 provided on the double-sided conveying path 14, conveyed to the registration roller pair 43, and transferred to the secondary transfer portion N2 by the registration roller pair 43. and supplied. After that, the toner image is secondarily transferred to the second surface of the recording material S in the same manner as the image formation on the first surface, and after the toner image is fixed, the recording material S is discharged to the discharge tray 48d. A double-sided conveying section (double-sided conveying device) 11 is configured by the reversing conveying path 12, the switchback roller pair 13, the double-sided conveying path 14, the re-conveying roller pair 15, and the like. Images can be formed on both sides of one recording material S by the operation of the double-sided conveying unit 11 .

After the primary transfer, the surface of the photosensitive drum 51 is neutralized by the pre-exposure device 54 . Adhered matter such as toner remaining on the photosensitive drum 51 without being transferred to the intermediate transfer belt 44b during the primary transfer process (primary transfer residual toner) is removed from the photosensitive drum 51 by the drum cleaning device 55 and collected. be. The drum cleaning device 55 scrapes off deposits from the surface of the rotating photosensitive drum 51 with a cleaning blade as a cleaning member that contacts the surface of the photosensitive drum 51, and stores it in a cleaning container. The cleaning blade is in contact with the surface of the photosensitive drum 51 with a predetermined pressing force so that the free end of the cleaning blade faces the upstream side in the rotation direction of the photosensitive drum 51 in the counter direction. Further, the intermediate transfer unit 44 has a belt cleaning device 60 as an intermediate transfer body cleaning means. Adhered matter such as toner remaining on the intermediate transfer belt 44b without being transferred to the recording material S during the secondary transfer process (secondary transfer residual toner) is removed from the intermediate transfer belt 44b by the belt cleaning device 60 and collected. be done.

A reading unit (reading device) 80 as reading means is arranged in the upper portion of the device main body 10 . The reading unit 80 includes an automatic document feeder (automatic document feeder (ADF)) 81 as a document feeder (document feeder), a platen glass 82, a light source 83, a mirror group 84a, an imaging lens 84b, and the like. It has a system 84 and a reading element 85 such as a CCD. In this embodiment, the reading unit 80 scans and exposes an image of a document (recording material S on which an image is formed) placed on a platen glass 82 with a movable light source 82 through an optical system 84 . They can be read sequentially by the reading element 85 . In this case, the reading unit 80 sequentially illuminates the document placed on the platen glass 82 with the moving light source 83 , and the reflected light images from the document are sequentially formed on the reading element 85 via the optical system 84 . do. As a result, the image of the document can be read by the reading element 85 at a predetermined dot density. Further, in this embodiment, the reading unit 80 sequentially exposes the images of the document conveyed by the automatic document feeder 81 with the light source 82 as the document is conveyed, and scans the images through the reading element 85 via the optical system 84 . can be read sequentially by In this case, the reading unit 80 sequentially illuminates the document passing through a predetermined reading position on the platen glass 82 with the light source 83 , and sequentially focuses reflected light images from the document on the reading element 85 via the optical system 84 . image. As a result, the image of the document can be read by the reading element 85 at a predetermined dot density. Thus, the reading unit 80 optically reads an image on the recording material S placed on the platen glass 82 or conveyed by the automatic document feeder 81 and converts it into an electric signal.

For example, when the image forming apparatus 1 operates as a copier, the image of the document read by the reading unit 80 is, for example, three colors of red (R), green (G), and blue (B) (8 bits each). It is sent to the image processing section of the control section 30 as image data. In the image processing unit, the image data of the document is subjected to predetermined image processing as necessary, and converted into four-color image data of yellow, magenta, cyan, and black. Examples of the image processing include shading correction, positional deviation correction, brightness/color space conversion, gamma correction, frame removal, color/movement editing, and the like. Image data corresponding to the four colors of yellow, magenta, cyan, and black are sequentially sent to the exposure devices 42y, 42m, 42c, and 42k, respectively, and the above-described image exposure is performed according to this image data. Further, as will be described later in detail, the reading unit 80 is also used for reading patches on the chart (obtaining density information (luminance information)) in the adjustment mode.

FIG. 2 is a block diagram showing a schematic configuration of the control system of the image forming apparatus 1 of this embodiment. As shown in FIG. 2, the control unit 30 is configured by a computer. The control unit 30 includes, for example, a CPU 31 as arithmetic control means, a ROM 32 as storage means for storing programs for controlling each part, a RAM 33 as storage means for temporarily storing data, and externally inputting and outputting signals. and an input/output circuit (I/F) 34 . A CPU (arithmetic unit) 31 is a microprocessor that controls the overall control of the image forming apparatus 1 and is the main body of the system controller. The CPU 31 is connected to the feeding section 90, the printer section 40, the discharge section 48, and the operation section 70 via the input/output circuit 34, exchanges signals with these sections, and controls the operations of these sections. The ROM 32 stores an image formation control sequence for forming an image on the recording material S, and the like. A charging power supply 73 , a development power supply 74 , a primary transfer power supply 75 , and a secondary transfer power supply 76 are connected to the control section 30 , and these are controlled by signals from the control section 30 . The control unit 30 also includes a temperature sensor 71, a humidity sensor 72, a voltage detection sensor 75a and a current detection sensor 75b of the primary transfer power source 75, a voltage detection sensor 76a and a current detection sensor 76b of the secondary transfer power source 76, and a fixing temperature sensor. 77 are connected. A signal detected by each sensor is input to the control unit 30 .

The operation unit 70 has an input unit such as an operation button as input means, and a display unit 70a such as a liquid crystal panel as display means. In this embodiment, the display section 70a is configured as a touch panel and also has a function as an input means. An operator such as a user or a service person can cause the image forming apparatus 1 to execute a job (described later) by operating the operation unit 70 . The control unit 30 receives signals from the operation unit 70 and operates various devices of the image forming apparatus 1 . The image forming apparatus 1 can also execute a job based on an image forming signal (image data, control command) from an external device 200 such as a personal computer.

In this embodiment, the control section 30 has a pre-image formation preparation process section 31a, an ATVC control process section 31b, an image formation process section 31c, and an adjustment process section 31d. The control unit 30 also has a primary transfer voltage storage/calculation unit 31e and a secondary transfer voltage storage/calculation unit 31f. Note that each of these process units and storage/calculation units may be provided as part of the CPU 31 and RAM 33 . For example, the control unit 30 (more specifically, the image forming process unit 31c) can execute jobs. The control unit 30 (more specifically, the ATVC control process unit 31b) can execute ATVC control (setting mode) of the primary transfer unit and the secondary transfer unit. ATVC control will be described later in detail. Further, the control section 30 (more specifically, the adjustment process section 31d) can execute an adjustment mode for adjusting the set value of the secondary transfer voltage. The adjustment mode will be described later in detail.

In this embodiment, the image forming apparatus 1 can perform image formation in the following first mode (first image forming mode) and second mode (second image forming mode). In the first mode, at least two image forming units 50 out of the plurality of image forming units 50 transfer toner images formed on the intermediate transfer belt 44b by superimposing toner onto the recording material S at the secondary transfer portion N2. In this mode, image formation can be performed by The second mode is a mode in which an image is formed by transferring a toner image formed on the intermediate transfer belt 44b by one image forming unit 50 out of the plurality of image forming units 50 onto the recording material S at the secondary transfer portion N2. be. In particular, in this embodiment, the image forming apparatus 1 performs image formation in a full-color mode capable of forming a full-color image as a first mode and a monochrome mode for forming a black single-color image as a second mode. It is possible. In full-color mode, toner images can be formed by all four image forming units 50y, 50m, 50c, and 50k. In the monochrome mode, only the image forming unit 50k for black among the four image forming units 50y, 50m, 50c, and 50k can form a toner image. That is, in this embodiment, the control unit 30 (image forming process unit 31c) applies the primary transfer voltage to all of the four primary transfer units N1 to form a multi-color image, a full-color mode, and a black primary transfer unit N1. A monochrome mode in which the primary transfer voltage is applied only to the transfer portion N1k to form a monochromatic image can be switched and executed.

Here, the image forming apparatus 1 executes a job (image output operation, print job), which is a series of operations for forming and outputting an image on a single or a plurality of recording materials S, which is started by one start instruction. do. A job generally includes an image forming process, a pre-rotation process, an inter-paper process when forming images on a plurality of recording materials S, and a post-rotation process. The image forming process is a period in which electrostatic image formation of an image to be actually formed and output on the recording material S, toner image formation, primary transfer, and secondary transfer of the toner image are performed. period) refers to this period. More specifically, the timing during image formation differs depending on the position where each step of electrostatic image formation, toner image formation, primary transfer, and secondary transfer of the toner image is performed. The pre-rotation process is a period from when the start instruction is input to when the image formation is actually started, during which preparatory operations are performed before the image forming process. The inter-paper process is a period corresponding to a period between recording materials S when image formation is continuously performed on a plurality of recording materials S (continuous image formation). The post-rotation process is a period during which an arrangement operation (preparation operation) is performed after the image forming process. The non-image forming period (non-image forming period) is a period other than the image forming period, and includes the pre-rotation process, the paper interval process, the post-rotation process, and further, when the power of the image forming apparatus 1 is turned on or from the sleep state. It includes a pre-multi-rotation process, etc., which is a preparatory operation at the time of return.

2. Control of Secondary Transfer Voltage Next, control of the secondary transfer voltage will be described. FIG. 3 is a flow chart showing the outline of the procedure for controlling the secondary transfer voltage in this embodiment. In general, there are constant voltage control and constant current control for controlling the secondary transfer voltage, and constant voltage control is used in this embodiment.

First, when the control unit 30 (the pre-image formation preparation process unit 31a) acquires job information from the operation unit 70 or the external device 200, it starts the operation of the job (S101). The information of this job includes image information designated by the operator and information of the recording material S. FIG. The information about the recording material S includes the size (width, length) of the recording material S on which an image is formed, information related to the thickness of the recording material S (thickness, basis weight, etc.), and whether the recording material S is coated paper. Information related to the surface properties of the recording material S may be included, such as whether or not the recording material S is In particular, in this embodiment, the information about the recording material S includes information about the size of the recording material S, and a category of the recording material S such as "thin paper, plain paper, thick paper, etc." related to the thickness of the recording material S. (so-called paper type category). Information about the recording material S (recording material information) refers to attributes based on general characteristics such as plain paper, high-quality paper, glossy paper, glossy paper, coated paper, embossed paper, thick paper, and thin paper (so-called paper type category), basis weight, thickness, size, rigidity, etc., or any information that can distinguish the recording material S, such as brand (including manufacturer, product name, product number, etc.). It includes. It can be considered that each recording material S distinguished by information on the recording material S constitutes the type of the recording material S. FIG. Information about the recording material S may be included in print mode information specifying operation settings of the image forming apparatus 1, such as "plain paper mode" or "thick paper mode", or may be substituted by print mode information. You may The control unit 30 (the pre-image formation preparation process unit 31a) writes the information of this job to the RAM 33 (S102).

Next, the control unit 30 (the pre-image formation preparation process unit 31a) acquires environmental information detected by the temperature sensor 71 and the humidity sensor 72 (S103). The ROM 32 also 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 onto the recording material S. FIG. Based on the environment information read in S103, the control unit 30 (secondary transfer voltage storage unit/calculation unit 31f) determines the target current Itarget corresponding to the environment from the information indicating the relationship between the environment information and the target current Itarget. Ask. Then, the control unit 30 writes the target current Itarget to the RAM 33 (or the secondary transfer voltage storage unit/calculation unit 31f) (S104). The reason why the target current Itarget is changed according to the environmental information is that the charge amount of the toner changes depending on the environment. The information indicating the relationship between the environmental information and the target current Itarget is obtained in advance through experiments or the like.

Next, the control unit 30 (ATVC control process unit 31b) performs ATVC control (Active Information on the electric resistance of the secondary transfer portion N2 is obtained by Transfer Voltage Control (S105). In other words, a plurality of levels of predetermined voltages are supplied from the secondary transfer power source 76 to the secondary transfer outer roller 45b while the secondary transfer outer roller 45b and the intermediate transfer belt 44b are in contact with each other. Then, the current value when a predetermined voltage is supplied is detected by the current detection sensor 76b, and the relationship between voltage and current (voltage-current characteristics) as shown in FIG. 4 is obtained. The control section 30 writes the information on the relationship between the voltage and the current in the RAM 33 (or the secondary transfer voltage storage section/calculation section 31f). The relationship between this voltage and current changes according to the electrical resistance of the secondary transfer portion N2. In the configuration of this embodiment, the relationship between the voltage and the current is not such that the current changes linearly (proportionally) to the voltage, but the current is a polynomial of second or higher order of the voltage (in this embodiment, it is a quadratic expression). ). Therefore, in this embodiment, the predetermined voltage or current supplied when acquiring the information on the electrical resistance of the secondary transfer portion N2 is set at three points so that the relationship between the voltage and the current can be represented by a polynomial. It is assumed that there are multiple stages as described above.

Next, the control section 30 (secondary transfer voltage storage section/calculation section 31f) obtains a voltage value to be applied from the secondary transfer power supply 76 to the secondary transfer outer roller 45b (S106). In other words, the control unit 30 calculates the target current Itarget written in the RAM 33 in S104 and the relationship between the voltage and the current obtained in S105 when there is no recording material S at the secondary transfer portion N2. A voltage value Vb required to flow Itarget is obtained. This voltage value Vb corresponds to the secondary transfer partial voltage (transfer voltage corresponding to the electrical resistance of the secondary transfer portion N2). Note that the target current Itarget is applied from the secondary transfer power supply 76 to the secondary transfer outer roller 45b by constant current control, the voltage value at that time is detected by the voltage detection sensor 76a, and the detected voltage is set to the voltage value Vb. can also be configured. The ROM 32 also stores information for obtaining the recording material assigned voltage (transfer voltage corresponding to the electric resistance of the recording material S) Vp as shown in FIG. In this embodiment, this information is set as table data indicating the relationship between the atmospheric moisture amount and the recording material apportionment voltage Vp for each basis weight category of the recording material S (corresponding to the paper type category). Note that the control section 30 (preparation process section 31 a before image formation) can obtain the amount of moisture in the atmosphere based on 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 apportionment voltage Vp from the table data based on the job information acquired in S101 and the environment information acquired in S103. In addition, when an adjustment value is set in an adjustment mode for adjusting the setting value of the secondary transfer voltage, the control unit 30 (secondary transfer voltage storage unit/calculation unit 31f) sets the adjustment value (correction value). ), the adjustment amount (correction amount) ΔV is calculated. As will be described later, this adjustment amount ΔV is stored in the RAM 33 (or the secondary transfer voltage storage section/calculation section 31f) when set in the adjustment mode. The control unit 30 sets Vb, Vp, and ΔV as the secondary transfer voltage Vtr to be applied from the secondary transfer power supply 76 to the secondary transfer outer roller 45b while the recording material S is passing through the secondary transfer portion N2. is added to obtain Vb+Vp+ΔV. Then, the control section 30 writes this Vtr (=Vb+Vp+ΔV) to the RAM 33 (or the secondary transfer voltage storage section/calculation section 31f). Note that the table data for obtaining the recording material apportionment voltage Vp as shown in FIG. 5 is obtained in advance through experiments or the like.

Here, the recording material apportioned voltage Vp may change depending on the surface properties of the recording material S in addition to information related to the thickness of the recording material S (thickness, basis weight, etc.). Therefore, the table data may be set so that the recording material apportionment voltage Vp is also changed by information relating to the surface properties of the recording material S. FIG. In this embodiment, information related to the thickness of the recording material S (further information related to the surface properties of the recording material S) is included in the job information acquired in S101. However, the image forming apparatus 1 may be provided with measuring means for detecting the thickness of the recording material S and the surface properties of the recording material S, and the recording material apportionment voltage Vp may be obtained based on the information obtained by this measuring means. .

Next, the control unit 30 (image forming process unit 31c) executes image formation, sends the recording material S to the secondary transfer unit N2, applies the secondary transfer voltage Vtr determined as described above, and performs secondary transfer. Transfer is performed (S107). After that, the control unit 30 (image forming process unit 31c) repeats the process of S107 until all the images of the job are transferred to the recording material S and output (S108).

As for the primary transfer portion N1, the same ATVC control as described above is performed from when the job is started until the toner image is conveyed to the primary transfer portion N1, but detailed description thereof will be omitted here.

3. Overview of Adjustment Mode Next, an adjustment mode (simple adjustment mode) for adjusting the set value of the secondary transfer voltage will be described.

Depending on the type and condition of the recording material S used for image formation, the water content and electrical resistance of the recording material S may be significantly different from those of the standard recording material S. In this case, the setting value of the secondary transfer voltage using the preset default recording material apportionment voltage Vp as described above may not be able to perform appropriate transfer. That is, the secondary transfer voltage must first be a voltage necessary for transferring the toner on the intermediate transfer belt 44b onto the recording material S. FIG. Also, the secondary transfer voltage must be suppressed to a voltage at which abnormal discharge does not occur. However, depending on the type and condition of the recording material S actually used for image formation, the electrical resistance may be higher than the assumed standard value. In this case, the voltage required to transfer the toner on the intermediate transfer belt 44b to the recording material S is insufficient with the set value of the secondary transfer voltage using the preset default recording material apportionment voltage Vp. Sometimes. Therefore, in this case, it is desirable to increase the secondary transfer voltage by, for example, increasing the recording material apportionment voltage Vp. Conversely, depending on the type and condition of the recording material S actually used for image formation, the recording material S may absorb moisture, and the electrical resistance may be lower than the value assumed as the standard value. , discharge may occur easily. In this case, the set value of the secondary transfer voltage using the preset default recording material apportionment voltage Vp may cause an image defect due to abnormal discharge. Therefore, in this case, it is desirable to lower the secondary transfer voltage by, for example, lowering the recording material apportionment voltage Vp.

For this reason, an operator such as a user or a service staff adjusts (changes) the recording material allotted voltage Vp according to the recording material S actually used for image formation, thereby setting the secondary transfer voltage at the time of job execution. It may be desired to adjust (change) the value to an appropriate value. In other words, it may be desired to select an appropriate recording material apportionment voltage Vp+ΔV (adjustment amount) according to the recording material S actually used for image formation.

This adjustment may be performed by the following method. That is, for example, the operator outputs an image to be output while switching the secondary transfer voltage for each sheet of recording material S, checks the output image, and determines an appropriate secondary transfer voltage set value ( More specifically, it is a method of determining the recording material apportionment voltage (Vp+ΔV). However, in this method, since the output of the image and the adjustment of the set value of the secondary transfer voltage are repeated, the amount of wasted recording material S may increase and the adjustment may take time.

Therefore, in this embodiment, the image forming apparatus 1 is provided with an adjustment mode for adjusting the set value of the secondary transfer voltage. In this adjustment mode, a chart is formed by transferring a plurality of patches (test images) of representative colors onto the recording material S that is actually used for image formation by switching the secondary transfer voltage (test voltage) for each patch. output. Then, based on the output chart, it is possible to determine an appropriate set value of the secondary transfer voltage (more specifically, recording material shared voltage Vp+ΔV). In this embodiment, in the adjustment mode, the control unit 30 reads density information (luminance information) of patches on the chart (typically solid image patches) by the reading unit 80, and performs secondary transfer based on the results. Provides information on the recommended adjustment ΔV for the voltage set point. As a result, the need for the operator to visually check the image on the chart is reduced, and the operator's operational burden is reduced, and the set value of the secondary transfer voltage can be adjusted more appropriately. .

4. Chart Next, a chart (adjustment image, test page) output in the adjustment mode in this embodiment will be described. 6 and 7 are schematic diagrams of the chart 100 in this embodiment. In this embodiment, in the adjustment mode, two types of charts 100 shown in FIGS. 6 and 7 are output according to the size of the recording material S to be used. FIG. 6 shows a chart 100 output when the length of the recording material S in the conveying direction is 420 to 487 mm. FIG. 7 shows a chart 100 output when the length of the recording material S in the conveying direction is 210 to 419 mm. In this embodiment, the recording material S is adjusted even in the adjustment mode so that the secondary transfer voltages for secondary transfer to the front side (first side) and the back side (second side) in double-sided image formation can be adjusted. Charts can be printed on both sides. 6 and 7 show a case where a chart is formed on one side of the recording material S (hereinafter also referred to as a "single-sided chart") and a case where a chart is formed on both sides of the recording material S (hereinafter also referred to as a "double-sided chart"). ) is shown. In this embodiment, formation of the chart 100 is performed in full color mode operation. A double-sided chart is formed by double-sided image formation using the double-sided conveying section 11 described above.

Here, the size of the recording material S is represented by recording material width (length in the main scanning direction)×recording material length (length in the sub-scanning direction). The recording material width is the length in the direction (width direction) substantially orthogonal to the conveying direction of the recording material S when passing through the secondary transfer portion N2. The length of the recording material is the length in the direction substantially parallel to the conveying direction of the recording material S when passing through the secondary transfer portion N2.

FIG. 6 shows a large size chart (hereinafter also referred to as a “large chart”) 100L (hereinafter also referred to as “large chart”) output when using a large size recording material S such as A3 (297 mm×420 mm) or ledger (approximately 280 mm×432 mm). 100 La, 100 Lb). FIG. 6A shows the large chart 100La when outputting a single-sided chart (or the first side when outputting a double-sided chart). FIG. 6B shows a large chart 100Lb on the second side when outputting a double-sided chart.

FIG. 7 is a small-size chart (hereinafter also referred to as a “small chart”) output when using a small-size recording material S such as A4 (297 mm×210 mm) or Letter (approximately 280 mm×216 mm). ) indicates 100S (100Sa, 100Sb). FIGS. 7A and 7B show the first and second small charts 100Sa when outputting a single-sided chart (or the first side when outputting a double-sided chart), respectively. Also, FIGS. 7C and 7D show the first and second small charts 100Sb on the second side when outputting a double-sided chart, respectively.

In this embodiment, the chart 100 has a patch set in which one solid blue patch 101, one solid black patch 102, and two halftone patches 103 are arranged side by side in the width direction. In the large chart 100L of FIG. 6, 11 sets of the patch sets 101 to 103 in the width direction are arranged in the transport direction. In addition, in the small chart 100S of FIG. 7, 10 sets of the patch sets 101 to 103 in the width direction are arranged in the transport direction. In this embodiment, the halftone patch 103 is a gray (black halftone) patch. Here, a solid image is an image with the maximum density level. In this embodiment, the solid blue is a superposition of magenta (M) toner=100% and cyan (C) toner=100%, and the solid blue toner amount is 200%. A solid black image is an image with black (K) toner=100%. A halftone image is, for example, an image with a toner bearing amount of 10 to 80% when the toner bearing amount of a solid image is 100%. Further, in this embodiment, the chart 100 is associated with each of the patch sets 101 to 103 to identify the setting value of the secondary transfer voltage applied to each of the patch sets. of patch identification information 104 is provided. This patch identification information 104 may be a value corresponding to an adjustment value of the secondary transfer voltage, which will be described later. In the large chart 100L of FIG. 6, 11 pieces of patch identification information 104 (11 pieces of -5 to 0 to +5 in this embodiment) corresponding to 11 stages of secondary transfer voltage settings are arranged. In the small chart 100S of FIG. 7, 10 corresponding to 10 stages of secondary transfer voltage setting (in this embodiment, 5 from -4 to 0 for the first sheet, 5 from +1 to +5 for the second sheet). ) is arranged. In addition, the chart 100 indicates that at least one of the front side (first side) and the back side (second side) of the recording material S is the front side (first side) or the back side (second side) of the recording material S. Front/back identification information 105 may be provided to indicate at least one of.

The size of the patch is required to be a size that allows the operator to easily determine the presence or absence of an image defect. Regarding the transferability of the solid blue patch 101 and the solid black patch 102, since it is likely to be difficult to judge the transferability of the patch if the size of the patch is small, the size of the patch is preferably 10 mm square or larger, and is preferably 25 mm square. It is more preferable that the size is equal to or greater than In the halftone patch 103, the image defects caused by the discharge that occurs when the secondary transfer voltage is increased often become image defects such as white dots. This image defect tends to be easier to determine even in a small image compared to the transferability of a solid image. However, since the image is easier to see if it is not too small, in this embodiment, the width of the halftone patch 103 in the conveying direction is the same as the width of the solid blue patch 101 and the solid black patch 102 in the conveying direction. Also, the intervals between the patch sets 101 to 103 in the transport direction may be set so that the secondary transfer voltage can be switched. In this embodiment, each of the solid blue patch 101 and the solid black patch 102 is a square of 25.7 mm×25.7 mm (with one side substantially parallel to the width direction). Further, in this embodiment, the halftone patches 103 at both ends in the width direction have a width of 25.7 mm in the conveying direction, and the width direction is the extreme end portion of the chart 100 (there may be a margin, which will be described later). extends to Also, in this embodiment, the interval between the patch sets 101 to 103 in the conveying direction is set to 9.5 mm. The secondary transfer voltage is switched at the timing when the portion on the chart 100 corresponding to this interval passes through the secondary transfer portion N2. In this embodiment, each of the patch sets 101 to 103 of the chart 100 uses a plurality of secondary transfer voltages whose absolute values are different in order to increase the transfer direction of the recording material S when the chart 100 is formed. The images are sequentially transferred from the upstream side to the downstream side. However, the present invention is not limited to such aspects. Each of the patch sets 101 to 103 of the chart 100 is transferred from the upstream side to the downstream side in the conveying direction of the recording material S during the formation of the chart 100 by using a plurality of secondary transfer voltages that are different so that the absolute values are sequentially decreased. may be sequentially transferred to the

It is preferable that no patch be formed in the vicinity of the leading edge and the trailing edge of the recording material S in the conveying direction (for example, in a range of about 20 to 30 mm inward from the edge). This is for the following reasons. In other words, there may be an image defect that occurs only at the leading end or the trailing end in the transporting direction of the recording material S, not at the widthwise end thereof. This is because, in this case, it may be difficult to determine whether or not an image defect has occurred due to the fluctuation of the secondary transfer voltage.

The maximum size of the recording material S that can be used in the image forming apparatus 1 of this embodiment is 13 inches (approximately 330 mm)×19.2 inches (approximately 487 mm). It corresponds to material S. When the size of the recording material S is 13 inches×19.2 inches or less and A3 (297 mm×420 mm) or more, the image data of the large chart 100L shown in FIG. A chart corresponding to the image data is output. At this time, in this embodiment, the image data is cut out according to the size of the recording material S with reference to the center of the leading edge. That is, the leading edge of the recording material S in the conveying direction and the leading edge of the large chart 100L in the conveying direction (the upper end in the figure) are aligned, and the center of the recording material S in the width direction is aligned with the center of the large chart 100L in the width direction. Image data is cropped. Further, in this embodiment, the image data is cut so that a margin of 2.5 mm is provided at the edges (both edges in the width direction and both edges in the transport direction in this embodiment). For example, when the large chart 100L is output on an A3 (297 mm×420 mm) recording material S, the image data is cut out in a range of 292 mm×415 mm with a margin of 2.5 mm at each end. Then, the large chart 100L corresponding to the image data is output on the recording material S of A3 (297 mm×420 mm) with the tip center as the reference. When a recording material S having a width smaller than 13 inches is used, the widthwise size of the halftone patch 103 at the edge in the widthwise direction becomes smaller. Also, when a recording material S having a width smaller than 13 inches is used, the margin at the rear end in the conveying direction becomes smaller. As described above, the large chart 100L has 11 sets of patch sets from -5 to 0 to +5. The eleven patch sets 101 to 103 of the large chart 100L are arranged in a range of 387 mm in length in the conveying direction so that the length of the recording material S in the conveying direction is 415 mm when the size of the recording material S is A3. ing.

In this embodiment, when a recording material S having a size smaller than A3 (297 mm×420 mm) is used, a small chart 100S in FIG. 7 is output. The small chart 100S in FIG. 7 corresponds to sizes smaller than A5 (longitudinal feed) to A3 (297 mm×420 mm) (that is, the length in the transport direction is 210 to 419 mm). As described above, the small chart 100S has 5 patch sets of -4 to 0 on the first sheet and 10 patch sets in total of +1 to +5 on the second sheet. The size of the image data of the small chart 100S is 13 inches×210 mm. In the width direction, the halftone patch 103 becomes smaller in accordance with the size of the recording material S. FIG. In the conveying direction, five patch sets are accommodated within a length of 167 mm in the conveying direction, and the trailing margin becomes longer according to the length of the recording material S in the conveying direction of 210 to 419 mm. In the case of the recording material S having a length of 210 to 419 mm in the conveying direction, only five sets of patch sets can be formed in the conveying direction with one sheet. Therefore, in order to increase the number of patches, the chart is divided into two sheets, and 5 sets of -4 to 0 and 5 sets of +1 to +5 form a total of 10 patch sets. In the small chart 100S, the -5 patch set in the large chart 100L is omitted.

Further, in this embodiment, the solid blue patches 101 and the solid black patches 102 are arranged on the front side (first side) and the back side (second side) of the double-sided chart so as not to overlap each other on the front and back sides of the recording material S. is doing. In this embodiment, the patch interval in the width direction is set to 5.4 mm. This is to suppress variations in the patch density on the second side due to the effect of the patch density on the first side, and to more accurately adjust the secondary transfer voltage for the second side.

In addition, in this embodiment, the chart 100 can be printed using not only the standard size but also any size (free size) of the recording material S by inputting and specifying the chart 100 from the operation unit 70 or the external device 200 by the operator. Output is also possible.

Here, one chart 100 is formed on one side of one sheet of recording material S, or formed separately on one side of each of a plurality of sheets of recording material S (that is, a step chart 100). A set of charts having a set of patches whose test voltages are varied dynamically. In the above example, the large chart 100La (first side) and the large chart 100Lb (second side) each correspond to one chart. Further, in the above example, the first and second small charts 100Sa (first side) correspond to one chart as a whole. Similarly, the first and second small charts 100Sb (second side) correspond to one chart as a whole.

5. Operation in adjustment mode 5-1. Outline of Operation in Adjustment Mode As described above, in the conventional adjustment mode, control is performed so that the secondary transfer voltage is selected so that both the density of single-color patches and the density of multi-color (multi-color) patches are good. is being done. However, there may be a relatively large discrepancy between the set value of the secondary transfer voltage at which the density of the single-color patch is good and the set value of the secondary transfer voltage at which the density of the multi-color patch is good. In this case, in the above-described conventional adjustment mode, the secondary transfer voltage is selected so that both the density of the single-color patch and the density of the multi-color patch are good. There is a possibility that it will not be the next transfer voltage. This is because in the monochrome mode, the secondary transfer voltage is such that both the density of the single-color patch and the density of the multiple-color patch are good, although it is not necessary to consider the secondary transfer performance of the multiple-color toner image. is selected.

Therefore, in this embodiment, the image forming apparatus 1 is configured to be able to individually adjust the set value of the secondary transfer voltage in each of the full-color mode and the monochrome mode using the adjustment mode. This makes it possible to individually optimize the secondary transfer performance in each of the full-color mode and the monochrome mode. A more detailed description will be given below.

5-2. Procedure of Adjustment Mode Operation Next, the adjustment mode operation in this embodiment will be described in more detail. FIG. 8 is a flow chart showing the outline of the procedure of the adjustment mode in this embodiment. Here, the case where the chart 100 is formed as the large chart 100L as described above is taken as an example. Further, here, a case where the operator inputs an instruction from the operation unit 70 of the image forming apparatus 1 to execute the adjustment mode is taken as an example. Also, for the sake of simplicity, a recording material on which a chart is formed may be simply referred to as a "chart".

First, the control unit 30 (adjustment process unit 31d) acquires information (paper type category, size, etc.) of the recording material S selected by the operator for which the operator wants to adjust the set value of the secondary transfer voltage ( S201). In this embodiment, the control unit 30 (adjustment process unit 31d) causes the display unit 70a of the operation unit 70 to display a recording material setting screen 400 for setting the recording material S as shown in FIG. 9, for example. In this recording material setting screen 400, a name 401 of the recording material S (for example, "recording material 1", "recording material 2", etc.), information of the recording material S (paper type category, size, etc.) 402, , and selection of the recording material S to be used. Then, when the operator operates the adjustment mode activation button 403 provided corresponding to each recording material S, the control unit 30 (adjustment process unit 31d) causes the display unit 70a of the operation unit 70 to display the ) for setting the adjustment mode is displayed. That is, in this embodiment, the control unit 30 (adjustment process unit 31d) acquires information about the recording material S in response to the operator's operation of the adjustment mode activation button 403, and associates the information with the information. An adjustment mode process for adjusting the set value of the secondary transfer voltage is started. Since the adjustment screen 300 shown in FIG. 10A is displayed before the chart 100 is output, the adjustment screen 300 shown in FIG. Since it is displayed after output, it is also called a "post-output adjustment screen 300b".

The pre-output adjustment screen 300a has a voltage setting section 301 for setting adjustment values of the secondary transfer voltage for the front side (first side) and the back side (second side) of the recording material S. FIG. The pre-output adjustment screen 300a also has an output side selection section 302 for selecting whether to output the chart 100 on one side or both sides of the recording material S. FIG. The pre-output adjustment screen 300 a also has an output instruction section (chart output button) 303 for instructing output of the chart 100 . The pre-output adjustment screen 300a also has a cancel button 304 for canceling the setting change (or canceling the adjustment mode).

The control unit 30 (adjustment process unit 31d) acquires the following information input by the operator on the pre-output adjustment screen 300a (S202). That is, setting information of the central voltage value of the secondary transfer voltage (value corresponding to the patch of "0" of the chart) when forming the chart 100, and setting of whether to output a single-sided chart or a double-sided chart. Information. When the adjustment value “±0” is selected in the voltage setting unit 301, the central voltage value of the secondary transfer voltage (more specifically, the recording material allotted voltage Vp) at the time of forming the chart 100 is currently selected. A specified value (table value) preset for the recording material S is set. Further, when an adjustment value other than "±0" is selected, the center voltage value is changed by an adjustment amount ΔV of 150 V for each level of the adjustment value.

Next, when the chart output button 303 is operated by the operator on the pre-output adjustment screen 300a, the control unit 30 (adjustment process unit 31d) first performs the same operation as the ATVC control described above to perform the secondary transfer unit N2. Information on electrical resistance is acquired (S203). Then, the control unit 30 (adjustment process unit 31d) sets the secondary transfer voltage Vtr=Vb+Vp+ΔV based on the acquired information on the electrical resistance and the information on the center voltage value set on the pre-output adjustment screen 300a. , the chart 100 is output (S204). At this time, the control unit 30 (adjustment process unit 31d) adjusts the image data of the chart 100 according to the size of the recording material S as described above, and adjusts the chart 100 while changing the adjustment amount ΔV by 150V. Control to output. Here, the case of outputting the large chart 100L is taken as an example, so the control unit 30 (adjustment processing unit 31d) controls to output the chart 100 having 11 patch sets as described above. For example, if the recording material shared voltage Vp in the environment during execution of the adjustment mode is 2500V and the Vb obtained by ATVC control is 1000V, the chart 100 is printed while changing the secondary transfer voltage from 2750V to 4250V in increments of 150V. Image formation is performed.

Next, the control unit 30 (adjustment process unit 31d) acquires the density information (luminance information) of the multi-color patches and the density information (luminance information) of the single-color patches in the output chart 100 ( S205). In this embodiment, the output chart 100 is set in the reading section 80 by the operator and read by the reading section 80 . Then, the control unit 30 (adjustment process unit 31d) acquires RGB luminance data (8 bits) of each patch of solid blue and solid black based on the reading result of the reading unit 80 . At this time, the control unit 30 (adjustment process unit 31 d ) can display on the operation unit 70 prompting the operator to set the chart 100 on the reading unit 80 . Further, the control unit 30 (adjustment process unit 31d) can control the reading unit 80 to read the chart 100 in response to the operator's operation of a start button (not shown) on the operation unit 70. can. Next, the control unit 30 (adjustment process unit 31d) uses the acquired brightness data (density data) to find the average brightness value (“average brightness value”) of each patch (S206). B luminance data is used for solid blue patches, and G luminance data is used for solid black patches. Next, the control unit 30 (adjustment process unit 31d) determines a recommended adjustment value for the secondary transfer voltage based on the obtained luminance average value (S207).

Here, processing for determining a recommended adjustment value for the secondary transfer voltage in this embodiment will be described. Through the process of S206, the relationship between the adjustment value of the secondary transfer voltage at the time of forming the chart 100 and the luminance average value of each patch of solid blue and solid black is obtained as shown in FIG. 11, for example.

For each patch of solid blue and solid black, the lower the average luminance value, the higher the image density and the better the transferability. For example, in the case of the relationship between the adjustment value and the luminance average value shown in FIG. 11, it can be read that there is a discrepancy between the adjustment value for good blue solid transferability and the adjustment value for good black solid transferability.

In the full-color mode, it is necessary to consider both multi-color transferability and single-color transferability. In the configuration of this embodiment, it is preferable that the image density is such that the average luminance value of solid blue is 40 or less, and the average luminance value of black solid is 7 or less. In the case of the relationship between the adjustment value and the luminance average value shown in FIG. 11, the adjustment value that satisfies the condition of the luminance average value of the solid blue and the black solid is in the range of +1 to +3. In this case, in this embodiment, the control unit 30 (adjustment process unit 31d) determines +2, which is the middle value of the range, as the recommended adjustment value of the secondary transfer voltage in the full-color mode.

On the other hand, in the monochrome mode, since it is not necessary to consider the transferability of multiple colors, the transfer voltage can be determined by considering only the transferability of black. As described above, in the configuration of this embodiment, the image density is preferably such that the average luminance value of black solid is 7 or less. In the case of the relationship between the adjustment value and the luminance average value shown in FIG. 11, the adjustment value that makes the luminance average value of black solid 7 or less is in the range of -5 to +3. In this case, in this embodiment, the control unit 30 (adjustment process unit 31d) determines −1, which is the middle value of the range, as the recommended adjustment value of the secondary transfer voltage in the monochrome mode. It should be noted that the black solid transferability at the adjustment value of −1 determined for the black mode is better than the black solid transferability at the adjustment value +2 determined for the full color mode. (that is, the luminance average value is low).

As described above, in the present embodiment, the control unit 30 (adjustment process unit 31d) individually determines the recommended adjustment values of the secondary transfer voltage for each of the full-color mode and the monochrome mode in the adjustment mode. be able to. As a result, it is possible to individually set the optimum secondary transfer voltage adjustment value for each of the full-color mode and the monochrome mode, depending on the adjustment mode.

Next, the control unit 30 (adjustment process unit 31d) displays the recommended adjustment value of the secondary transfer voltage determined in S207 on the display unit 70a of the operation unit 70 as shown in FIG. 10B. It is displayed on the screen 300b (S208). The post-output adjustment screen 300b is used to individually set the secondary transfer voltage adjustment values for the front side (first side) and the back side (second side) of the recording material S in the full-color mode and the monochrome mode. has first and second voltage setting units 305 and 306 . The post-output adjustment screen 300b also has a confirming section (OK button) 307 for confirming the settings. The output adjustment screen 300b also has a cancel button 308 for canceling the change of settings. The adjustment values displayed in the first and second voltage setting sections 305 and 306 indicate preferred setting candidates for the secondary transfer voltage in the full-color mode and monochrome mode, respectively. The operator can determine whether or not the displayed adjustment values are acceptable based on the displayed content of the post-output adjustment screen 300b and the output chart. If the operator does not want to change the displayed adjustment value, the operator simply operates the OK button 307 . On the other hand, if the operator wishes to change the displayed adjustment value, he/she inputs to the first and second voltage setting sections 305 and 306 and operates the OK button 307 . Therefore, the control unit 30 (adjustment process unit 31d) determines whether or not the adjustment value has been changed (S209). When the OK button 307 is operated without changing the adjustment value, the control unit 30 (adjustment process unit 31d) stores the adjustment value determined in S207 in the RAM 33 (or the secondary transfer voltage storage/calculation unit 31f). Store (S210). On the other hand, when the adjustment value is changed, the control unit 30 (adjustment process unit 31d) stores the adjustment value input by the operator in the RAM 33 (or the secondary transfer voltage storage unit/calculation unit 31f) (S211). ). In this embodiment, as shown in FIG. 12, the control unit 30 (adjustment process unit 31d) controls the information of the recording material S, the adjustment value of the secondary transfer voltage in the full-color mode, and the adjustment of the secondary transfer voltage in the monochrome mode. and are stored in the storage unit (RAM 33 or secondary transfer voltage storage unit/calculation unit 31f) in association with each other. Incidentally, instead of or in addition to the adjustment value, an adjustment amount ΔV obtained as described later may be stored. This completes the adjustment mode.

The control unit 30 (secondary transfer voltage storage unit/calculation unit 31f) stores the stored adjustment value until the next adjustment when executing a subsequent job using the recording material S to be adjusted. to set the secondary transfer voltage. That is, the control unit 30 (secondary transfer voltage storage unit/calculation unit 31f) stores information about the recording material S used in image formation and the storage unit (RAM 33 or secondary transfer voltage storage unit/calculation unit 31f) corresponding to the information. The secondary transfer voltage during image formation is set based on the information stored in the calculation unit 31f). In this embodiment, the control unit 30 (secondary transfer voltage storage unit/calculation unit 31f) sets the adjustment amount ΔV to ΔV=adjustment value×150 [V] according to the adjustment value stored in the adjustment mode as described above. ]. Then, the control unit 30 (secondary transfer voltage storage unit/calculation unit 31f) uses the calculated adjustment amount ΔV to calculate the post-adjustment recording material apportionment voltage Vp+ΔV, and uses this to calculate the secondary transfer voltage during normal image formation. Next transfer voltage Vtr (=Vb+Vp+ΔV) is calculated.

Note that the method for determining the recommended adjustment values for the secondary transfer voltage in each of the full-color mode and monochrome mode is not limited to the above method. In the present embodiment, the center value of the adjustment values with which the luminance average value is equal to or less than the predetermined value is determined as the recommended adjustment value, but the present invention is not limited to this. For example, an adjustment value in a stable luminance region where the standard deviation of the average luminance value obtained sequentially for each predetermined number of adjustment values is the minimum, or where the luminance difference between adjacent adjustment values is equal to or less than a predetermined value. A recommended adjustment value may be determined, etc., based on extracting the . Alternatively, a recommended adjustment value may be determined based on extracting an adjustment value that minimizes the luminance average value (maximum density). A recommended adjustment value for the secondary transfer voltage in the full-color mode may be determined based on the density information (luminance information) of the multiple color patch with at least two color toners. Also, a recommended adjustment value for the secondary transfer voltage in the monochrome mode may be determined based on the density information of the monochrome patch.

In this embodiment, the brightness data for determining the recommended adjustment value of the secondary transfer voltage in the full-color mode was acquired using a solid blue patch, which is a multiple color, but the present invention is not limited to this. do not have. For example, instead of blue, patches of other colors such as secondary colors red and green may be used. However, from the viewpoint of adjustment accuracy, etc., it is preferable to use multicolor patches formed using the image forming section 50 that forms an image in the first mode (full color mode in this embodiment). In this embodiment, the brightness data for determining the recommended adjustment value of the secondary transfer voltage in the monochrome mode for forming a black monochrome image is acquired using a black monochrome patch, but the present invention is not limited to this. not something. For example, instead of black, patches of other single colors such as yellow, magenta, and cyan may be used. However, from the viewpoint of adjustment accuracy, it is preferable to use a single-color patch formed using the image forming section 50 that forms an image in the second mode (black monochrome mode in this embodiment).

Further, in this embodiment, the reading unit 80 for reading the chart 100 set by the operator as shown in FIG. 1 is used as the reading means, but the present invention is not limited to such an aspect. A reading unit that reads the chart 100 when the chart 100 is output from the image forming apparatus 1 may be used as the reading unit. For example, as shown in FIG. 13, an in-line image sensor 86 may be provided on the downstream side of the fixing section 46 in the conveying direction of the recording material S. In this case, when the chart 100 is output from the image forming apparatus 1, the chart 100 can be read by the image sensor 86 to obtain patch density information (luminance information).

As described above, the image forming apparatus 1 of this embodiment includes the image carrier (intermediate transfer belt in this embodiment) 44b that carries a toner image, and the image carrier 44b that forms toner images with toner. It has a forming section 50, a transfer member 45b forming a transfer section N2 for transferring the toner image from the image carrier 44b to the recording material S, and an application section 76 for applying voltage to the transfer member 45b. Further, in the present embodiment, the image forming apparatus 1 uses at least two image forming units 50 out of the plurality of image forming units 50 to superimpose toner images on the image carrier 44b so as to form toner images at the transfer unit N2. A first mode (full-color mode in this embodiment) in which an image can be formed by transferring onto the recording material S, and one image forming unit 50 out of a plurality of image forming units 50 to form an image on the image carrier 44b. A second mode (in this embodiment, a monochromatic black mode) in which an image is formed by transferring the toner image onto the recording material S at the transfer portion N2 can be executed. In this embodiment, the image forming apparatus 1 forms a test image with toner on the image carrier 44b, applies a test voltage to the transfer member 45b by the applying unit 76, and transfers the test image to the recording material S. , an execution unit (adjustment process unit in this embodiment) 31d for executing an output operation for outputting a chart 100 for adjusting the transfer voltage applied to the transfer member 45b by the application unit 76 during image formation, and an output operation execution unit 31d. First information about the adjustment amount of the transfer voltage in the first mode (in the present embodiment, an adjustment value indicating the adjustment amount ΔV of the secondary transfer voltage) and the adjustment of the transfer voltage in the second mode, which are set by the second information about the amount (in this embodiment, an adjustment value indicating the adjustment amount ΔV of the secondary transfer voltage); and a setting unit (secondary transfer voltage storage unit/calculation unit in the present embodiment) 31f for setting the transfer voltage during image formation based on.

In this embodiment, the storage unit 33 associates and stores information on the recording material S with the first information and the second information, and the setting unit 31f stores information on the recording material S used for image formation. and the information stored in the storage unit 33 corresponding to the information, the transfer voltage during image formation is set. In addition, in the present embodiment, the image forming apparatus 1 performs the first reading based on the information about the density of the test image of the chart 100 acquired by the reading means 80 that acquires the information about the density of the test image of the chart 100 and the reading means 80 . and an adjustment unit (adjustment processing unit in this embodiment) 31 d that obtains the first information and the second information and stores the first information and the second information in the storage unit 33 . In this embodiment, the adjustment unit 31d performs the first test image based on the information about the density of the test image formed by superimposing the toner on the image carrier 44b by at least two image forming units 50 out of the plurality of image forming units 50. 1 information is obtained, and the second information is obtained based on the information about the density of the test image formed with the toner on the image carrier 44b by one image forming unit 50 out of the plurality of image forming units 50 .

As described above, according to this embodiment, in the adjustment mode, it is possible to individually adjust the set value of the transfer voltage in each of the full-color mode and the monochrome mode. Therefore, according to this embodiment, it is possible to individually optimize the secondary transfer properties of the toner image in the full-color mode and the monochrome mode. That is, according to this embodiment, in a configuration capable of executing the first mode capable of forming a multi-color toner image and the second mode capable of forming a single-color toner image, the first mode can be selected by the adjustment mode. It becomes possible to appropriately adjust the transfer voltages of the mode and the second mode.

[Example 2]
Another embodiment of the present invention will now be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the image forming apparatus of the first embodiment. Accordingly, in the image forming apparatus of the present embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of the first embodiment are denoted by the same reference numerals as those of the image forming apparatus of the first embodiment. Therefore, a detailed explanation is omitted.

In Example 1, in S201 of FIG. Adjusted the settings. Here, the categorization of the recording material S in the image forming apparatus 1 is generally determined by information such as the basis weight and surface properties of the recording material S. FIG. Therefore, for example, even if the recording materials S are classified into the same category, the optimum secondary transfer voltage adjustment value may differ if the electrical resistance is significantly different.

Therefore, in the present embodiment, the image forming apparatus 1 includes information about the recording material cassette 91 in which the recording material S is stored, information about the recording material S, the adjustment value of the secondary transfer voltage in the full-color mode, and the secondary transfer voltage in the monochrome mode. The adjustment value of the next transfer voltage is linked and stored in the storage unit.

Specifically, in this embodiment, the control unit 30 (adjustment process unit 31d) selects the recording material S for which the operator wants to adjust the setting value of the secondary transfer voltage in S201 of FIG. acquires information on the recording material cassette 91 in which is stored. In this embodiment, the control unit 30 (adjustment process unit 31d) causes the display unit 70a of the operation unit 70 to display, for example, a storage unit setting screen 500 for setting the recording material cassette 91 as shown in FIG. . In this storage section setting screen 500, the name 501 of the recording material cassette 91 (for example, "cassette 1", "cassette 2", etc.) and the information 502 of the recording material S (paper type category, size, etc.) are set. It is possible to set the relationship. Then, when the operator operates the adjustment mode activation button 503 provided corresponding to each recording material cassette 91, the control unit 30 (adjustment process unit 31d) causes the display unit 70a of the operation unit 70 to display the screen shown in FIG. A pre-output adjustment screen 300c as shown in a) is displayed. That is, in this embodiment, the control unit 30 (adjustment process unit 31d) acquires information on the recording material cassette 91 in response to the operator's operation of the adjustment mode start button 503, and associates the information with the information. to start adjustment mode processing for adjusting the set value of the secondary transfer voltage.

After that, the control unit 30 (adjustment process unit 31d) determines the adjustment value of the secondary transfer voltage in the full-color mode and the adjustment value of the secondary transfer voltage in the monochrome mode by the same procedure as in the first embodiment. However, in this embodiment, the control unit 30 (adjustment process unit 31d) causes the display unit 70a of the operation unit 70 to display the post-output adjustment screen 300d as shown in FIG. 15B in S208 of FIG. Further, in this embodiment, the control unit 30 (adjustment process unit 31d), in S210 or S211 of FIG. The information of the recording material S, the adjustment value of the secondary transfer voltage in the full-color mode and the adjustment value of the secondary transfer voltage in the monochrome mode are associated with each other, and stored in the storage unit (RAM 33, or the secondary transfer voltage storage/calculation unit 31f). ).

Then, when executing a subsequent job using the recording material S from the recording material cassette 91 to be adjusted, the control unit 30 (secondary transfer voltage storage unit/calculation unit 31f) controls the following until the next adjustment is performed. A secondary transfer voltage is set according to the stored adjustment value. That is, the control unit 30 (secondary transfer voltage storage unit/calculation unit 31f) stores information about the recording material cassette 91 containing the recording material S used in image formation, and the storage unit (RAM 33, Alternatively, the secondary transfer voltage during image formation is set based on the information stored in the secondary transfer voltage storage unit/calculation unit 31f).

Thus, the image forming apparatus 1 of this embodiment has a plurality of recording material storage units 91 in which the recording materials S are stored respectively. Further, in this embodiment, the storage unit 33 stores information on the recording material storage unit 91, information on the recording material S stored in the recording material storage unit 91, and first information (in this embodiment, the second information in the full-color mode). Next transfer voltage adjustment value) and second information on the transfer voltage adjustment amount in the second mode (secondary transfer voltage adjustment value in monochrome mode in this embodiment) are stored in association with each other. In this embodiment, the setting unit 31f is based on the information of the recording material storage unit 91 in which the recording material S used for image formation is stored and the information stored in the storage unit 33 corresponding to the information. to set the transfer voltage for image formation.

As described in the first embodiment, the color of the patch for obtaining the density information (luminance information), the configuration of the reading means, etc. are not limited to the mode of the present embodiment, and are described in the first embodiment. It is good also as another aspect similar to this.

According to this embodiment, for example, even if the recording materials S are of the same category, when different recording material cassettes 91 are used, different secondary transfer voltage adjustment values can be set. As a result, for example, for each recording material cassette 91 containing the recording materials S that are classified into the same category but have different optimal secondary transfer voltage adjustment values, the optimum secondary transfer voltage for each of the full-color mode and the monochrome mode is obtained. An adjustment value for the transfer voltage can be set. As a result, for any recording material S, the secondary transfer properties can be optimized in both the full-color mode and the monochrome mode.

[Example 3]
Another embodiment of the present invention will now be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the image forming apparatus of the first embodiment. Accordingly, in the image forming apparatus of the present embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of the first embodiment are denoted by the same reference numerals as those of the image forming apparatus of the first embodiment. Therefore, a detailed explanation is omitted.

In Example 1, the control unit 30 (adjustment process unit 31 d) determines the recommended adjustment value for the secondary transfer voltage based on the result of reading the chart 100 by the reading unit 80 . This is preferable because it is possible to reduce the operation burden on the operator. However, the present invention is not limited to such an aspect, and the operator may visually check the chart output in the adjustment mode or use a colorimeter to determine the adjustment value. good.

In this embodiment, in the adjustment mode, the image forming apparatus 1 does not determine the recommended adjustment value of the secondary transfer voltage by the control unit 30 (adjustment process unit 31d), and the operator adjusts based on the chart 100. It is configured to determine the value.

FIG. 17 is a flow chart showing the outline of the procedure of the adjustment mode in this embodiment. The processing of S301 to S304 of FIG. 17 is the same as the processing of S201 to S204 of FIG. 8 described in the first embodiment. In this embodiment, when the chart 100 is output, the control unit 30 (adjustment process unit 31d) causes the display unit 70a of the operation unit 70 to display a post-output adjustment screen 300b as shown in FIG. 10(b).

After that, in this embodiment, the operator determines the adjustment value of the secondary transfer voltage in the full-color mode and the adjustment value of the secondary transfer voltage in the monochrome mode based on the output chart 100 . At this time, the operator inputs the determined adjustment values to the first and second voltage setting sections 305 and 306 on the post-output adjustment screen 300b as shown in FIG. 10B, and operates the OK button 307. . Then, the control unit 30 (adjustment process unit 31d) causes the RAM 33 (or the secondary transfer voltage storage unit/calculation unit 31f) to store the adjustment value input by the operator (S305).

In this embodiment, as in the first embodiment, the control unit 30 (adjustment process unit 31d), as shown in FIG. and the adjusted value of the secondary transfer voltage in the storage unit (RAM 33 or secondary transfer voltage storage unit/calculation unit 31f). As in the second embodiment, a post-output adjustment screen 300d as shown in FIG. Information, information on the recording material S accommodated in the recording material cassette 91, the adjusted value of the secondary transfer voltage in the full-color mode and the adjusted value of the secondary transfer voltage in the monochrome mode are associated with each other and stored in a storage unit (RAM 33 , or may be stored in the secondary transfer voltage storage unit/calculation unit 31f).

As described above, in this embodiment, when the output operation of outputting the chart 100 is executed, the image forming apparatus 1 obtains the first information (secondary The input unit 70 stores the adjustment value of the transfer voltage) and the second information (the adjustment value of the secondary transfer voltage in the monochrome mode in this embodiment) in the storage unit 33 . The input unit 70 can be configured to have an operation unit (adjustment screen) 300b through which the operator inputs the first information and the second information in association with the information of the recording material S. FIG. Alternatively, the input unit 70 can be configured to have an operation unit (adjustment screen) 300 d through which the operator inputs the first information and the second information in association with the information of the recording material storage unit 91 .

As described above, the image forming apparatus 1 is configured such that the operator sets the adjustment value of the secondary transfer voltage in each of the full-color mode and the monochrome mode without reading the chart 100 by the reading unit 80. be able to.

[others]
Although the present invention has been described with reference to specific examples, the present invention is not limited to the above-described examples.

In the above embodiment, the secondary transfer voltage is adjusted using the adjustment value corresponding to the predetermined adjustment amount, but the adjustment amount may be set directly on an adjustment screen, for example.

Further, in the above-described embodiments, the operation performed by the operation unit of the image forming apparatus can be performed by an external device. That is, the case where the adjustment mode is executed by the operator performing the operation via the operation unit 70 of the image forming apparatus 1 has been described, but the operation is performed via the external device 200 such as a personal computer, and the adjustment mode is executed. An adjustment mode may be executed. In this case, the driver program of the image forming apparatus 1 installed in the external device 200 can perform the same settings as in the above embodiment via a screen displayed on the display section of the external device 200 . In this case, an input/output circuit (I/F) 34 for controlling input/output of signals constitutes an input section for storing information in a storage section according to an operation by an operator.

Further, in the above-described embodiment, the configuration in which the secondary transfer voltage is controlled by constant voltage is described, but the secondary transfer voltage may be controlled by constant current. In the above-described embodiment, 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 the secondary transfer voltage is controlled to a constant voltage. In the case of a configuration in which the secondary transfer voltage is controlled by a constant current, the secondary transfer voltage can be adjusted by adjusting the target current when the secondary transfer voltage is applied in the adjustment mode.

Further, the current detection result and the voltage detection result may be an average value of a plurality of sampling values obtained at predetermined sampling intervals at one detection timing. When the transfer voltage is under constant voltage control, the voltage value may be detected (recognized) from the output instruction value for the power supply, and when the transfer voltage is under constant current control, the current value may be detected from the output instruction value for the power supply. may be detected (recognized).

Further, the present invention is applicable not only to the tandem-type image forming apparatus but also to image forming apparatuses of other types. For example, the present invention can be applied to the transfer portion of an image forming apparatus having a configuration in which a multi-color toner image or a single-color toner image is formed on a photosensitive drum as an image bearing member and directly transferred onto a recording material at the transfer portion. may Further, the present invention can be implemented in various applications such as printers, various printing machines, copiers, facsimiles, and multi-function machines.

30 control unit 31d adjustment process unit (execution unit, adjustment unit)
31f secondary transfer voltage storage unit/calculation unit (setting unit, storage unit)
33 RAM (storage unit)
44b intermediate transfer belt (image carrier)
45b secondary transfer outer roller (transfer member)
70 operation unit (input unit)
80 reading section 100 chart N2 secondary transfer section S recording material

Claims (8)

an image carrier that carries a toner image;
a plurality of image forming units each forming a toner image with toner on the image carrier;
a transfer member forming a transfer portion for transferring the toner image from the image carrier to a recording material;
an applying unit that applies a voltage to the transfer member;
has
At least two image forming units out of the plurality of image forming units can form an image by transferring a toner image formed by superimposing toner on the image carrier onto a recording material at the transfer unit. a first mode, a second mode in which a toner image formed on the image carrier by one of the plurality of image forming units is transferred onto a recording material by the transfer unit to form an image; An image forming apparatus capable of executing
A test image is formed on the image carrier with toner, the test image is transferred to the recording material by applying the test voltage to the transfer member by the application unit, and the application unit transfers the test image to the transfer member when the image is formed. an execution unit that executes an output operation for outputting a chart for adjusting the applied transfer voltage;
First information about the adjustment amount of the transfer voltage in the first mode and second information about the adjustment amount of the transfer voltage in the second mode, which are set by executing the output operation. a storage unit that stores
a setting unit that sets the transfer voltage during the image formation based on the information stored in the storage unit;
An image forming apparatus comprising: the storage unit associates and stores information about a recording material with the first information and the second information;
The setting unit sets the transfer voltage during the image formation based on information on the recording material used during the image formation and information stored in the storage unit corresponding to the information.
2. The image forming apparatus according to claim 1, wherein: having a plurality of recording material storage units each storing a recording material,
the storage unit associates and stores information on the recording material storage unit, information on the recording materials stored in the recording material storage unit, and the first information and the second information;
The setting unit determines the recording material used in the image formation based on the information of the recording material storage unit in which the recording material used in the image formation is stored and the information stored in the storage unit corresponding to the information. setting the transfer voltage;
2. The image forming apparatus according to claim 1, wherein: reading means for obtaining information about the density of the test image of the chart;
The first information and the second information are obtained based on the information about the density of the test image of the chart acquired by the reading means, and the first information and the second information are stored in the storage unit. a memorizing adjustment unit;
4. The image forming apparatus according to claim 1, comprising: The adjustment unit adjusts the first information based on information regarding the density of the test image formed by superimposing toner on the image carrier by at least two image forming units out of the plurality of image forming units. 5. The second information is obtained based on the information about the density of the test image formed on the image carrier with toner by one of the plurality of image forming units. The image forming apparatus according to . 4. The apparatus according to any one of claims 1 to 3, further comprising an input unit for storing said first information and said second information in said storage unit according to an operation by an operator when said output operation is executed. The image forming apparatus according to any one of items 1 to 3. an input unit for storing the first information and the second information in the storage unit according to an operation of an operator when the output operation is performed, wherein the input unit stores the information by the operator; 3. The image forming apparatus according to claim 2, further comprising an operation unit for inputting the first information and the second information in association with material information. an input unit configured to store the first information and the second information in the storage unit according to an operation of an operator when the output operation is executed, 4. An image forming apparatus according to claim 3, further comprising an operation unit for inputting said first information and said second information in association with information on a recording material storage unit.

Images