Image forming apparatus

Abstract

This reduces shock noise generated during transfer, allowing for optimal printing. [Solution] The transfer unit includes a transfer body that sandwiches a recording material being transported and transfers an image onto the recording material, and a pressing roller that presses the transfer body; a characteristic detection unit that detects characteristic information corresponding to the characteristics of the recording material being transported to the transfer unit; and a control unit that adjusts the pressing force of the roller against the transfer body or the distance between the roller and the transfer body in the transfer unit based on the detected characteristic information.

Description

Technical Field

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

Background Art

[0002] Conventionally, an image forming apparatus using an intermediate transfer method has been widespread, in which a toner image formed on a photoreceptor (image carrier) is primarily transferred to an intermediate transfer belt (image carrier and intermediate transfer body), and the toner image on the intermediate transfer belt is secondarily transferred to paper.

[0003] At the secondary transfer position, a transfer unit is arranged that has a support roller that supports the intermediate transfer belt from the inside thereof and a transfer roller that presses the intermediate transfer belt from the outside of the intermediate transfer belt. When the paper being carried in passes between the outer peripheral surface of the intermediate transfer belt and the secondary transfer roller, the transfer unit transfers the toner image on the intermediate transfer belt to the paper.

[0004] In this image forming apparatus, when paper enters the transfer unit, it is known that so-called shock noise occurs, in which noise such as horizontal lines is transferred to the paper. As a method for reducing this shock noise, a method of increasing the separation amount between the intermediate transfer belt and the transfer roller when entering the transfer unit to reduce the shock noise is known.

[0005] Also, as an apparatus that adjusts the separation amount between the intermediate transfer belt and the transfer roller, the image forming apparatus of Patent Document 1 is known. In this image forming apparatus, pre-printing before main printing is performed, and in this pre-printing, the conveyance speed of the paper is detected, and based on the detected conveyance speed result, the separation amount between the intermediate transfer belt and the transfer roller for the paper printed in the main printing is automatically adjusted.

Prior Art Documents

Patent Documents

[0007] However, conventional image forming machines use the paper speed detected during pre-printing for the main print run. This means they cannot handle different types or conditions of paper during the main print run, resulting in the problem of shock noise. Furthermore, waste paper is generated, so there is a desire for a method that allows for satisfactory printing without using waste paper.

[0008] This disclosure has been made in view of the above-mentioned problems, and aims to provide an image forming apparatus that can reduce shock noise generated during transfer and print suitably. [Means for solving the problem]

[0009] The main disclosure that addresses the aforementioned issues is: A transfer unit having a transfer body that sandwiches a sheet-like recording material being transported and transfers an image onto the recording material, and a roller facing the transfer body, A characteristic detection unit detects characteristic information corresponding to the characteristics of the recording material conveyed to the transfer unit, A control unit adjusts the pressing force between the transfer body and the roller or the distance between the transfer body and the roller in the transfer unit based on the detected characteristic information, It is equipped with. [Effects of the Invention]

[0010] According to the image forming apparatus of this disclosure, shock noise generated during transfer can be reduced, and printing can be performed effectively. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a diagram showing a schematic configuration of an image forming apparatus according to one embodiment of the present invention. [Figure 2] Figure 2 is a system block diagram of an image forming apparatus according to one embodiment of the present invention. [Figure 3]Figure 3 is a functional block diagram of the control unit in an image forming apparatus according to one embodiment of the present invention. [Figure 4] Figure 4 is a functional block diagram showing the main components of a detection device according to one embodiment of the present invention. [Figure 5] Figure 5 is a flowchart showing the operation of an image forming apparatus according to one embodiment of the present invention. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of an image forming apparatus to which the present invention is applied will be described with reference to the drawings.

[0013] <Configuration of an image forming apparatus> The configuration of an image forming apparatus according to one embodiment will be described with reference to Figure 1. Figure 1 is a diagram showing a schematic configuration of an image forming apparatus according to one embodiment.

[0014] As shown in Figure 1, the image forming apparatus 10 comprises a recording material supply device 100, a recording material transport device 400, an image forming apparatus main body 200, and a post-processing device 300.

[0015] In the image forming apparatus 10, when forming an image on a recording material S, first, a sheet-like recording material S, such as paper, is supplied from the recording material supply device 100 to the recording material transport device 400. The recording material transport device 400 then transports the recording material S to the main body of the image forming apparatus 200. The recording material transport device 400 is equipped with a characteristic detection unit ("first detection unit 71", "second detection unit 72") for measuring the characteristics of the recording material S. Characteristics are characteristic information that indicates the characteristics, and for example, the characteristics of paper include the paper thickness, paper moisture content, paper stiffness, paper basis weight or paper resistance, paper surface properties (smoothness), paper size, etc. Characteristics are also physical property values ​​that indicate the physical properties.

[0016] Next, the image forming apparatus main body 200 forms an image on the supplied recording material S. Then, the image forming apparatus main body 200 sends the recording material S on which the image has been formed to the post-processing apparatus 300. The post-processing apparatus 300 performs predetermined post-processing on the recording material S on which the image has been formed. After that, the post-processing apparatus 300 discharges the recording material S.

[0017] [Recording material supply device] The recording material supply device 100 stores a recording material (printing medium) S for image formation. When the recording material supply device 100 receives an image forming job from a control unit 90 (to be described later) of the image forming apparatus 10, the recording material supply device 100 supplies the recording material S corresponding to the image forming job to the recording material conveyance device 400. The recording material supply device 100 includes a conveyance unit 50 and a recording material supply unit 70.

[0018] The recording material supply unit 70 includes a plurality of recording material storage units. The plurality of recording material storage units individually store recording materials S of different types and sizes. In the present embodiment, the recording material S is a recording medium (printing medium) on which an image is formed, and for example, it is paper. As long as the recording material S can be measured including at least one of thickness, moisture content, stiffness, basis weight, or resistance among the above characteristics, it may be other than paper.

[0019] The conveyance unit 50 includes a plurality of pickup rollers (not shown) for picking up the recording material S from the recording material supply unit 70 and a plurality of conveyance rollers 53. The plurality of conveyance rollers 53 are provided along a predetermined recording material conveyance path. The plurality of conveyance rollers 53 convey the recording materials S taken out from the recording material supply unit 70 one by one to the recording material conveyance device 400.

[0020] [Recording material conveyance device] The recording material conveyance device 400 includes a conveyance inlet 54, a conveyance outlet 55, a first conveyance unit 51, a second conveyance unit 52, a third conveyance unit 56, a discharge unit 57, a first detection unit 71 (711, 712, 713, 714), and a second detection unit 72.

[0021] The loading entrance 54 receives the recording material S supplied from the recording material supply device 100. The first transport section 51, the second transport section 52, and the third transport section 56 transport the recording material S received from the loading entrance 54 to the discharge entrance 55 or the discharge section 57. The first transport section 51, the second transport section 52, and the third transport section 56 are equipped with a plurality of transport rollers 53 for transporting the recording material S.

[0022] The first detection unit 71 and the second detection unit 72 each acquire characteristic information of the recording material S. Specifically, the first detection unit 71 and the second detection unit 72 have media sensors that measure the characteristics of the recording material S. The media sensors measure various characteristics of the recording material S, that is, characteristic information that indicates its characteristics, so-called physical property values ​​that indicate physical properties, and output this characteristic information to the control unit 90.

[0023] The characteristic information of the recording material S includes at least one of the following: thickness, moisture content, stiffness, basis weight, surface properties (smoothness), resistance, etc. The characteristic information may also include the size of the recording material S. In particular, stiffness is an indicator of the resistance when the recording material S is bent, and can be expressed in various physical quantities.

[0024] The recording material transport device 400 has a branching section 58 that branches the transport path of the recording material S. The recording material transport device 400 has a first transport path formed in the first transport section 51 and a second transport path formed in the second transport section 52, which branch off from the branching section 58, and a discharge (purge) path formed in the third transport section 56, which branch off from the second transport path.

[0025] The first transport route is located upstream of the outlet 55 and connects the inlet 54 and the outlet 55. The first transport route branches off at the branching section 58 and then merges with the second transport route (second transport section 52) at the merging section 59 to connect with the outlet 55.

[0026] The second transport path is a path upstream of the discharge port 55 for acquiring characteristic information of the paper S being transported. The second transport path is equipped with media sensors (first detection unit 71, second detection unit 72) for measuring the characteristics of the paper S passing through the second transport path. The recording material S transported along the second transport path has its characteristics acquired as characteristic information and is discharged from the discharge port 55 via the merging unit 59 or discharged (purged) to the outside via the discharge path. The acquisition of characteristic information of the recording material S in the second transport path may be measured while the recording material is stopped on the second transport path or while it is moving.

[0027] The discharge path is formed in the third transport section 56, which is a transport section that branches off from the second transport section, and is a path for discharging (purging) recording material S with characteristics unsuitable for image formation (for example, characteristics with an extremely high moisture content) to the outside of the transport path. The third transport section 56 can purge the recording material S before it is transported from the outlet 55 into the image forming apparatus main body 200.

[0028] [Image forming apparatus main unit] The image forming apparatus main unit 200 includes an operation display unit 220, a scanner 230, an image forming unit 240, and a transport unit 250.

[0029] The operation display unit 220 comprises an operation unit and a display unit. The display unit is composed of a display device such as an LCD (Liquid Crystal Display). The display unit displays various screens according to the instructions of the display signals input from the control unit 90 (see Figure 2), which will be described later. The operation unit comprises a touch panel formed to cover the display screen of the display unit, as well as various operation buttons such as number buttons and a start button. The operation unit receives operation instructions from the user. The operation unit outputs operation signals based on the user's operation to the control unit 90, which will be described later.

[0030] Scanner 230 is equipped with an automatic document feeder (ADF) and a document image scanning device (scanner). The automatic document feeder transports documents placed on the document tray via a transport mechanism and sends them to the document image scanning device. The document image scanning device optically scans documents transported onto the contact glass by the automatic document feeder, or documents placed on the contact glass by the user. The document image scanning device forms an image of the reflected light from the scanned document onto a light-receiving surface such as a CCD (Charge Coupled Device) sensor. In this way, the document image scanning device reads the image of the document. Scanner 230 generates image data based on the reading results from the document image scanning device.

[0031] The image forming unit 240 forms an image on the recording material S based on the image data. The image forming unit 240 has photosensitive drums 241Y, 241M, 241C, and 241K corresponding to yellow (Y), magenta (M), cyan (C), and black (K). The image forming unit 240 further includes charging units 242Y, 242M, 242C, and 242K, exposure units 243Y, 243M, 243C, and 243K, developing units 244Y, 244M, 244C, and 244K, and primary transfer rollers 245Y, 245M, 245C, and 245K. The image forming unit 240 also includes an intermediate transfer belt 246, a secondary transfer roller 247, and a fixing unit 248.

[0032] Hereafter, the photoreceptor drums 241Y, 241M, 241C, and 241K will be collectively referred to as "photoreceptor drum 241". The charging sections 242Y, 242M, 242C, and 242K will be collectively referred to as "charging section 242", and the exposure sections 243Y, 243M, 243C, and 243K will be collectively referred to as "exposure section 243". Furthermore, the developing sections 244Y, 244M, 244C, and 244K will be collectively referred to as "developing section 244", and the primary transfer rollers 245Y, 245M, 245C, and 245K will be collectively referred to as "primary transfer roller 245".

[0033] The photoreceptor drum 241 is an image carrier that holds the toner image. The photoreceptor drum 241 rotates according to the drive of a photoreceptor drive motor (not shown). Around the photoreceptor drum 241, the charging unit 242, the exposure unit 243, and the developing unit 244 are arranged in order from the upstream side to the downstream side in the direction of rotation of the photoreceptor drum 241. The charging unit 242 uniformly charges the photoreceptor drum 241.

[0034] The exposure unit 243 consists of a laser light source, a polygon mirror, a lens, and the like. The exposure unit 243 scans and exposes the surface of the photoreceptor drum 241 with a laser beam to form an electrostatic latent image. Scanning exposure by the exposure unit 243 is performed based on image data read by the scanner 230 or image data received from an external device.

[0035] The developing unit 244 develops the image by attaching toners of each color to the electrostatic latent image formed on the photoreceptor drum 241. As a result, a toner image is formed on the image-bearing surface of the photoreceptor drum 241. Specifically, yellow, magenta, cyan, and black toner images are formed on the image-bearing surfaces of the photoreceptor drums 241Y, 241M, 241C, and 241K, respectively.

[0036] The intermediate transfer belt 246 is stretched across multiple belt support rollers and arranged in a loop. A primary transfer roller 245, a secondary transfer roller 247, an anti-static roller (not shown), and a cleaning unit 249 are arranged along the movement path of the intermediate transfer belt 246.

[0037] The outer surface of the intermediate transfer belt 246 is the image-bearing surface and is positioned in contact with the outer surface of the photoreceptor drum 241. The intermediate transfer belt 246 rotates in the opposite direction to the rotation of the photoreceptor drum 241. Specifically, the photoreceptor drum 241 rotates counterclockwise in Figure 1, and the intermediate transfer belt 246 rotates clockwise in Figure 1.

[0038] The primary transfer roller 245 is positioned opposite the photoreceptor drum 241. The primary transfer roller 245 is positioned on the inner circumference side of the intermediate transfer belt 246 and sandwiches the intermediate transfer belt 246 between itself and the opposing photoreceptor drum 241.

[0039] The primary transfer roller 245 applies a charge of opposite polarity to the toner to the intermediate transfer belt 246, thereby transferring the toner adhering to the image-bearing surface of the photoreceptor drum 241 to the image-bearing surface of the intermediate transfer belt 246 (primary transfer). As a result, a color toner image is formed on the image-bearing surface of the intermediate transfer belt 246, in which the four toner images are superimposed.

[0040] The secondary transfer roller (roller) 247, together with the intermediate transfer belt (transfer body) 246 and the support roller that supports the intermediate transfer belt 246 from the inside, constitutes the second transfer section (transfer section). The second transfer section may also be called the transfer nip section.

[0041] The secondary transfer roller 247 transfers the color toner image from the image-bearing surface of the intermediate transfer belt (transfer body) 246 onto one of the recording surfaces of the recording material S in one go (secondary transfer). The secondary transfer roller 247 sandwiches the intermediate transfer belt 246 between itself and the belt support roller (support roller).

[0042] The position where the secondary transfer roller 247 and the belt support roller, which constitute the transfer nip section, face each other becomes the transfer position where the toner image transferred to the image-carrying surface of the intermediate transfer belt 246 is transferred to the recording material S. The paper S enters this transfer position and is nipped by the intermediate transfer belt 246 and the secondary transfer roller 247, and the image is transferred. At this time, the amount of separation between the secondary transfer roller 247 and the intermediate transfer belt 246 and the pressing force of the secondary transfer roller 247 are adjusted according to the characteristics of the recording material S that enters during transport.

[0043] The cleaning unit 249 is positioned upstream of the primary transfer roller 245 and downstream of the static elimination roller (not shown) in the rotational direction of the intermediate transfer belt 246. The cleaning unit 249 removes toner remaining on the image-bearing surface of the intermediate transfer belt 246.

[0044] The fixing unit 248 comprises a fixing roller 248a and a pressure roller 248b. The fixing roller 248a has a built-in heater. The pressure roller 248b is pressed against the fixing roller 248a. As a result, the fixing roller 248a and the pressure roller 248b are pressed against each other, and a fixing nip is formed at this pressed portion. The recording material S is heated and pressurized as it passes through the fixing nip. This fixes the toner image transferred to the recording material S.

[0045] The transport unit 250 is equipped with a plurality of transport rollers 53 for transporting the recording material S along a predetermined transport path. The transport unit 250 transports the recording material S supplied from the recording material transport device 400 to the transfer position. The transport unit 250 also transports the recording material S after image formation to the post-processing device 300.

[0046] [Post-processing equipment] The post-processing device 300 receives the recording material S that has been image-formed in the main image forming apparatus 200. The post-processing device 300 comprises a plurality of post-processing units, a transport unit 350, an discharge unit 351, and a paper output tray 352.

[0047] When the post-processing device 300 receives a post-processing job from the control unit 90 (described later), it performs predetermined post-processing in the post-processing unit specified by the post-processing job. Examples of post-processing include perforation, folding, foil stamping, binding, cutting, stapling, gluing, and stitching.

[0048] The transport unit 350 is equipped with a plurality of transport rollers (not shown) for transporting the recording material S along a predetermined transport path. The transport unit 350 transports the recording material S supplied from the image forming apparatus main body 200 to a post-processing unit corresponding to the type of post-processing to be performed. The transport unit 350 also transports the recording material S after post-processing and discharges it from the discharge unit 351. The recording material S discharged from the discharge unit 351 is placed on the output tray 352.

[0049] [Control system for image forming apparatus 10] Next, an example of the control system configuration of the image forming apparatus 10 will be explained with reference to Figure 2. Figure 2 is a functional block diagram of the image forming apparatus 10.

[0050] The image forming apparatus 10 comprises a control unit 90, a storage unit 98, a communication unit 99, an operation display unit 220, a scanner 230, an image processing unit 80, a recording material supply unit 70, an image forming unit 240, first and second detection units 71 and 72, and transport units 50, 250, and 350. The image forming apparatus 10 also has a first transport unit 51, a second transport unit 52, and a third transport unit 56 as transport units. In the following description, components that overlap with the description of the image forming apparatus 10 shown in Figure 1 above will be omitted.

[0051] The control unit 90 is composed of, for example, a CPU (Central Processing Unit) 91, a ROM (Read Only Memory) 92, a RAM (Random Access Memory) 93, etc. The CPU 91 reads various processing programs stored in the ROM 92 and loads them into the RAM 93, and centrally controls the operation of each part of the image forming apparatus 10 according to the loaded programs.

[0052] ROM92 stores various processing programs for controlling each part of the image forming apparatus 10, parameters and table data necessary for executing these programs, and various files.

[0053] RAM93 is composed of volatile semiconductor memory. RAM93 forms a work area that temporarily stores various processing programs, input or output data, and parameters read from ROM92 during various processes controlled by the CPU91.

[0054] The storage unit 98 stores, for example, image data received from an external device. The storage unit 98 also stores various processing programs executed by the CPU 91, and information regarding the processing functions of the device necessary for executing those programs. Furthermore, the storage unit 98 stores image data read by the scanner 230, and image data input from client devices (not shown). In addition, the storage unit 98 stores characteristic information of the recording material S (size, thickness, moisture content, stiffness, basis weight, or resistance of the recording material S) measured by the first detection unit 71 and the second detection unit 72. The storage unit 98 may be composed of, for example, a non-volatile memory such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), or flash memory.

[0055] The communication unit 99 consists of a NIC (Network Interface Card), a modem, and other components. The communication unit 99 connects the recording material supply device 100, the recording material transport device 400, the image forming apparatus main unit 200, the post-processing device 300, the first detection unit 71, and the second detection unit 72 to a communication network. The communication network is a LAN (Local Area Network) or a WAN (Wide Area Network), etc. The communication unit 99 then transmits and receives various types of data between each device and external information devices (e.g., client devices).

[0056] As described above, the operation display unit 220 functions as both a display unit and an operation unit. The display unit displays various operation screens according to the display control signals input from the control unit 90. The operation unit receives various input operations from the user and outputs operation signals corresponding to those input operations to the control unit 90.

[0057] The scanner 230 outputs the scanned image (analog image signal) to the image processing unit 80.

[0058] The image processing unit 80 consists of circuits that perform analog-to-digital (A / D) conversion processing and circuits that perform digital image processing. The image processing unit 80 performs A / D conversion processing on the analog image signal supplied from the scanner 230 to generate digital image data.

[0059] Furthermore, the image processing unit 80 analyzes the print job acquired from an external information device (e.g., a client device), rasterizes each page of the original document, and generates digital image data. In addition, the image processing unit 80 applies image processing to the image data as needed, such as color conversion, correction processing according to initial settings or user settings (e.g., shading correction), and compression processing. The image processing unit 80 outputs the processed image data to the image forming unit 240.

[0060] The first detection unit 71 and the second detection unit 72 have multiple media sensors for measuring the characteristics (physical properties) of the recording material S. The first detection unit 71 and the second detection unit 72 are provided in the recording material transport device 400 (see Figure 1). When the first detection unit 71 and the second detection unit 72 receive a characteristic measurement signal indicating the characteristics of the recording material S output by the control unit 90, they measure the characteristics of the recording material S corresponding to the received signal in the recording material S. The paper characteristic detection device 700 also outputs the measurement results to the control unit 90.

[0061] [Functional configuration of the control unit] Next, the functional configuration of the control unit 90 will be explained with reference to Figure 3. Figure 3 is a functional block diagram of the control unit 90.

[0062] As shown in Figure 3, the control unit 90 includes a paper feeding control unit 94, a transport control unit 95, a media detection control unit 96, and an image forming control unit 97.

[0063] The paper feed control unit 94 controls the supply of recording material S from the recording material supply unit 70 to the transport unit 50 in the recording material supply device 100. The paper feed control unit 94 supplies the recording material S to the transport unit 50 in accordance with the transport control of the recording material S by the transport control unit 95.

[0064] The transport control unit 95 controls the drive of the transport units (50, 51, 52, 53, 250, 350) provided in the recording material supply device 100, the recording material transport device 400, the image forming apparatus main body 200, and the post-processing device 300. As a result, the recording material S is transported to various locations in the image forming apparatus 10. The transport control unit 95 also controls the transport mechanism, such as the branching section 58 of the recording material transport device 400, to change the transport path of the recording material S. The transport control unit 95 works in cooperation with the media detection control unit 96 to drive and control the first transport unit 51 and the second transport unit 52 of the transport units to transport the recording material S, and the third transport unit 56 can be used to purge the recording material S.

[0065] When transporting recording materials S according to an image forming job, the transport control unit 95 guides at least one or more recording materials S to a second transport path transported by the second transport unit 52 of the recording material transport device 400. In the second transport path, the characteristics of the recording materials S are measured by the first detection unit 71 and the second detection unit 72.

[0066] The transport control unit 95 corrects the control parameters related to the transport of the recording material S according to the rigidity of the recording material S. A specific example of the transport control parameters is the transport speed of the recording material S.

[0067] The media detection control unit 96 controls the first detection unit 71 and the second detection unit 72. Specifically, the media detection control unit 96 controls the first detection unit 71 and the second detection unit 72 as part of the paper characteristic detection device 700 (see Figure 4) of the image forming apparatus.

[0068] The image forming control unit 97 controls the image forming operation of the image forming unit 240. The image forming control unit 97 also determines control parameters related to image forming according to the characteristics of the recording material S measured by the first detection unit 71 and the second detection unit 72.

[0069] Control parameters related to image formation include the charging potential provided by the charging unit 242, the transfer current supplied to the primary transfer roller 245 and the secondary transfer roller 247, and the fixing temperature and fixing pressure in the fixing unit 248. In particular, the image forming control unit 97 works in cooperation with the media detection control unit 96 to drive and control the secondary transfer roller 247 in the image forming unit 240 according to the characteristics of the recording material S. By driving and controlling the secondary transfer roller 247, the pressing force on the intermediate transfer belt 246 is adjusted, and the distance between the intermediate transfer belt 246 and the secondary transfer roller 247 is adjusted.

[0070] The image forming control unit 97, via the image forming unit 240, adjusts the transfer nip section by adjusting the amount of separation between the intermediate transfer belt 246 and the secondary transfer roller 247, and the pressing force of the secondary transfer roller 247 against the intermediate transfer belt 246, in accordance with the characteristics of the recording material.

[0071] <Configuration of the paper characteristics detection device 700> Next, the paper characteristic detection device provided in the image forming apparatus 10 will be described with reference to Figure 4. Figure 4 is a functional block diagram showing the schematic configuration of the paper characteristic detection device 700 in the image forming apparatus. In the following description, configurations that overlap with the descriptions of the image forming apparatus 10 and control unit 90 shown in Figures 2 and 3 above will be omitted.

[0072] The paper characteristic detection device 700 is configured according to the constituent elements of the image forming apparatus 10, and controls the nip state in the second transfer section in accordance with the characteristics of the paper on which the image is formed, according to the configuration of the image forming apparatus 10.

[0073] The paper characteristic detection device 700 includes a transport unit (mainly a first transport unit 51, a second transport unit 52, and a third transport unit 56), a control unit 90, a storage unit 98, a detection unit consisting of a first detection unit 71 and a second detection unit 72, an environmental sensor 75, and a communication unit 99.

[0074] The first transport unit 51, the second transport unit 52, and the third transport unit 56 are installed in the recording material transport device 400. The second transport unit 52 mainly transports the recording material S whose characteristics have been detected to the discharge port 55, discharges it from the discharge port 55, and transports it to the second transfer unit.

[0075] The control unit 90 mainly comprises a media detection control unit 96 (see Figure 3), which measures the characteristics of the recording material S (physical properties such as stiffness, moisture content, thickness, basis weight, size, surface properties, and resistance) using the first detection unit 71 and the second detection unit 72, and outputs characteristic information indicating the measured characteristics to the control unit 90. The media detection control unit 96 of the control unit 90 also determines whether the detected physical property information (physical property values) is within a predetermined range (a range that can be adjusted in the second transfer unit). If the detected physical property information is outside the predetermined range, the media detection control unit 96 uses the transport control unit 95 to drive and control the second transport unit 52 and the third transport unit 56 of the transport unit to discharge the material to the outside.

[0076] Based on the measured characteristic information, the control unit 90, via the image forming control unit 97, drives and controls the secondary transfer roller 247 in the second transfer section via the image forming section 240 to adjust the degree of pressure or the amount of separation from the intermediate transfer belt 246, thereby adjusting the transfer nip section.

[0077] The control unit 90 reads the adjustment information for the secondary transfer unit (pressing force of the secondary transfer roller 247 on the intermediate transfer belt 246 or the distance between the intermediate transfer belt 246 and the secondary transfer roller 247) stored in the memory unit 98, which corresponds to the characteristic information of the recording material S. The control unit 90 drives and controls the second transfer unit using the adjustment information corresponding to the measured characteristics.

[0078] The first detection unit 71 includes a size sensor 711, a paper thickness sensor 712, a basis weight sensor 713, and a moisture content sensor 714 as media sensors for measuring the characteristics of the recording material S. The size sensor 711 measures the size of the recording material S as it is transported along the second transport path of the second transport unit 52, and the paper thickness sensor 712 measures the thickness of the recording material S. The basis weight sensor 713 measures the basis weight of the recording material S, and the moisture content sensor 714 measures the moisture content of the recording material S. Each of the sensors 711 to 714 outputs the measured information to the control unit 90. Note that the sensors 711 to 714 and the second detection unit 72 shown in Figure 1 may be installed anywhere along the second transport path of the second transport unit 52, as long as the characteristics of the recording material S can be measured.

[0079] The second detection unit 72 includes a stiffness sensor 721, a surface properties sensor 722, and a resistance sensor 723 as media sensors for measuring the characteristics of the recording material S.

[0080] The stiffness sensor 721 measures the stiffness of the recording material S being transported along the second transport path of the second transport unit 52, the surface quality sensor 722 measures the surface quality (smoothness) of the recording material S, and the resistance sensor 723 measures the resistance of the recording material S. Characteristic information indicating the stiffness, surface quality, and resistance of the recording material S measured by each of these sensors 721 to 723 is output to the control unit 90.

[0081] The environmental sensor 75 measures the environmental conditions in which the image forming apparatus 10 is installed. For example, it measures at least the humidity among the humidity and temperature of the space in which the image forming apparatus 10 is installed, and outputs this environmental information to the control unit 90.

[0082] Using the information acquired by the environmental sensor 75, the control unit 90 ensures the accuracy of one of the characteristics of the recording material S, such as the moisture content. Based on this information, for example, the moisture content of the recording material S can be estimated more clearly, and adjustments in the second transfer unit can be made more favorably accordingly.

[0083] [Adjustment of the second transfer section] Next, the processing of the image forming apparatus 10 according to this embodiment, mainly the processing of the recording paper characteristic detection device 700, will be described with reference to Figure 5. Figure 5 is a flowchart showing the operation of an image forming apparatus according to one embodiment of the present invention.

[0084] When a print instruction, such as whether the number of sheets of paper used as the recording material S, which is the printing medium for forming the image, is one or multiple sheets is input via the operation display unit 220, the control unit 90 starts the print job and begins the printing process for the first sheet (S1: Normal printing and start of the first sheet printing process). In step S1, when the print job is started, the paper feed control unit 94 supplies the recording material S to the transport unit 50 in accordance with the transport control of the recording material S by the transport control unit 95 and starts the printing process for the first sheet.

[0085] The recording material S is transported into the recording material transport device 400 via the transport unit 50 through the entrance 54, and then transported along the second transport path by the second transport unit 52.

[0086] In step S2, the media detection control unit 96 in the control unit 90 measures the characteristics (physical property values ​​indicating physical properties) of the recording material S as paper using various sensors (711-714, 721-723) of the first detection unit 71 and the second detection unit 72.

[0087] The various sensors (media sensors) include a size sensor 711, a paper thickness sensor 712, a basis weight sensor 713, a moisture content sensor 714, a stiffness sensor 721, a surface texture sensor 722, and a resistance sensor 723. The various sensors (711-714, 721-723) measure the physical properties (physical property values) of the recording material S and output them to the control unit 90 (media detection control unit 96).

[0088] In step S3, the media detection control unit 96 determines whether the physical properties of the recording material S, which is paper, (detected physical property information) are within a predetermined range (within the range in which the second transfer unit can be adjusted) based on various sensors. Step S3 also includes determining whether or not the paper characteristics (paper physical properties) were detected.

[0089] In step S3, if the (characteristic information indicating the characteristics, physical property value) is within a predetermined range, the process proceeds to step S4. If it is outside the range, the process proceeds to step S5, where the recording material S, which is paper, is purged from the purge path, and the process proceeds to step S7.

[0090] In step S4, the control unit 90 adjusts (automatically adjusts) the amount of separation between the secondary transfer roller 247 in the second transfer section and the intermediate transfer belt (transfer body) 246, and the pressing force of the secondary transfer roller 247, in accordance with the characteristics of the paper detected by the media detection control unit 96. In other words, the image forming control unit 97 adjusts the transfer nip section.

[0091] For example, if the moisture content of the paper is higher than a preset value, the transport speed decreases, and the pressing force (separation amount) of the secondary transfer roller 247 is adjusted to be weaker than the normal setting for that paper. Also, if the stiffness of the paper is higher than a preset value, the transport speed increases, and the pressing force (separation amount) of the secondary transfer roller 247 is adjusted to be stronger than the normal setting for that paper.

[0092] Furthermore, if the paper thickness is greater than the set paper thickness, the transport speed of the thicker paper will increase compared to that of the thinner paper, so the pressing force (separation amount) of the secondary transfer roller 247 will be adjusted to be stronger than that of the thinner paper. Also, if the basis weight of the paper is greater than the preset value, the transport speed will increase, so the pressing force of the secondary transfer roller 247 will be adjusted to be higher than the set value.

[0093] The image forming control unit 97 adjusts the nip portion in the second transfer unit, that is, it adjusts (automatically adjusts) the pressure and separation amount of the secondary transfer roller 247 against the intermediate transfer belt (transfer body) 246 according to the paper properties. Specifically, in step S4, the image forming control unit 97 reads the adjustment information (pressure force, separation amount) in the second transfer unit corresponding to the detected characteristic information (physical property values), and drives and controls the second transfer unit via the image forming unit 240 using the read adjustment information.

[0094] In step S6, the image forming control unit 97 drives and controls the second transfer unit via the image forming unit 240 to adjust the pressing force of the secondary transfer roller (roller) 247, or the amount of separation between the secondary transfer roller (roller) 247 and the intermediate transfer belt (transfer body) 246.

[0095] The image forming control unit 97 inserts the recording material S into the second transfer unit, whose separation amount has been adjusted, transfers the image to the recording material S, forms an image on the recording material S, and finishes printing the first recording material S.

[0096] Next, in step S7, the control unit 90 starts the printing process for the second sheet. The control unit 90's paper feed control unit 94 supplies the recording material S to the transport unit 50 in accordance with the transport control of the recording material S by the transport control unit 95, and starts the printing process for the second sheet.

[0097] The transport unit 50 transports the recording material S into the recording material transport device 400 via the entrance 54. The recording material S, once transported into the recording material transport device 400, is transported along the second transport path by the second transport unit 52.

[0098] In step S8, the media detection control unit 96 in the control unit 90 measures the paper characteristics (physical property values ​​indicating physical properties) of the recording material S using various sensors (711-714, 721-723) of the first detection unit 71 and the second detection unit 72. The physical properties (physical property values) of the recording material S measured by each sensor are output to the control unit 90 (media detection control unit 96).

[0099] In step S9, the media detection control unit 96 determines whether the paper characteristics (physical properties and physical property values) of the recording material S detected by measurement are within a predetermined range (within the range in which the second transfer unit can be adjusted). Step S9 also includes determining whether the paper characteristics (paper physical properties) were detected.

[0100] In step S9, if the characteristics (characteristic information indicating the characteristics, physical property values) are within a predetermined range, the process proceeds to step S10. If the values ​​are outside the predetermined range, the process proceeds to step S11, where the recording material S is purged from the purge path, and the process proceeds to step S12.

[0101] In step S10, the image forming control unit 97 of the control unit 90 adjusts (automatically adjusts) the pressure on the pressing roller of the second transfer portion in the second transfer section according to the paper properties, and then proceeds to step S12. Specifically, in step S10, the image forming control unit 97 reads the adjustment information (pressing force, spacing amount) in the second transfer section corresponding to the detected characteristic information (physical property values), and drives and controls the second transfer section via the image forming unit 240 using the read adjustment information.

[0102] In step S12, the image forming control unit 97 drives and controls the second transfer unit via the image forming unit 240 to adjust the pressing force of the secondary transfer roller (roller) 247, or the amount of separation between the secondary transfer roller (roller) 247 and the intermediate transfer belt (transfer body) 246.

[0103] The image forming control unit 97 inserts the recording material S into the second transfer unit, whose separation amount has been adjusted, transfers the image to the recording material S, forms an image on the recording material S, and finishes printing the second recording material S.

[0104] The image forming apparatus 10 measures physical properties of the recording material S, which is a printing medium such as paper, using various media sensors for thickness, moisture content, stiffness, basis weight, and resistance, and automatically adjusts the amount of separation in the pressing direction and separation direction of the transfer nip based on the measured physical properties.

[0105] As a result, there is no timing discrepancy in the transfer nip section when the recording material is sandwiched between the intermediate transfer belt 246 and the secondary transfer roller 247. Furthermore, by adjusting the distance between the two to correspond to the characteristics of the recording material (such as its thickness), even if the recording material enters the transfer area, shock noise is not formed on the recording material, and the image can be transferred.

[0106] Thus, the image forming apparatus 10 measures the characteristics of the recording material to be printed and feeds back the physical property values ​​representing those measured characteristics to the secondary transfer unit. This allows the pressure applied to the recording material during transfer in the secondary transfer unit to be adjusted for each individual sheet, thereby reducing shock noise without the need for pre-printing or waste paper.

[0107] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. [Industrial applicability]

[0108] According to the image forming apparatus of this disclosure, it is possible to reduce shock noise generated during transfer and print suitably. [Explanation of Symbols]

[0109] 10 Image forming apparatus 50 Conveying section 51. First Conveyor Unit 52 Second Conveyor Unit 53 Conveyor rollers 54 Loading entrance 55 Exit 56 Third Conveyor Unit 57 Discharge section 58 Branching point 59 Confluence 70 Recording material supply unit 71 First detection unit 72 Second detection unit 75 Environmental Sensors 80 Image Processing Unit 90 Control Unit 94 Paper feed control unit 95 Transport Control Unit 96 Media Detection Control Unit 97 Image Forming Control Unit 100 Recording material supply device 200 Image forming apparatus main unit 240 Image forming unit 246 Intermediate transfer belt (transfer body) 247 Secondary transfer roller (roller) 248 Fixing section 300 Post-processing equipment 350 Conveyor Unit 351 Discharge section 400 Recording material transport device 700 Paper Characteristics Detection Device 711 Size Sensor 712 Paper Thickness Sensor 713 Basis weight sensor 714 Moisture content sensor 721 Stiffness Sensor 722 Surface Sensor 723 Resistance Sensor S Recording material

Claims

1. A transfer unit having a transfer body that sandwiches a sheet-like recording material being transported and transfers an image onto the recording material, and a roller facing the transfer body, A characteristic detection unit detects characteristic information corresponding to the characteristics of the recording material conveyed to the transfer unit, A control unit adjusts the pressing force between the transfer body and the roller or the distance between the transfer body and the roller in the transfer unit based on the detected characteristic information, An image forming apparatus equipped with the following features.

2. The characteristics of the recording material are at least one of the following: thickness, moisture content, stiffness, basis weight, and resistance. The image forming apparatus according to claim 1.

3. The characteristic detection unit is located upstream of the transfer unit in the transport path that transports the recording material to the transfer unit. The control unit performs adjustments in the transfer unit to the detected recording material based on the characteristic information detected upstream of the transfer unit. The image forming apparatus according to claim 1.

4. The characteristic detection unit detects characteristic information of the recording material being transported along the transport path. The image forming apparatus according to claim 3.

5. The characteristic information includes at least one of the thickness, moisture content, and basis weight of the recording material. The image forming apparatus according to claim 4.

6. Upstream of the transfer unit, there is a transport path for transporting the recording material to the transfer unit, A purge path is provided in the transport path and purges the recording material that can be transported to the transfer section, It has, The control unit, if the detected characteristic information of the recording material is outside a predetermined range, purges the recording material being transported from the purge path. The image forming apparatus according to claim 3.

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