Image formation system

Abstract

To suppress failure in fixation of a toner image to a recording medium, as compared to the case of execution of temperature control of a heating roller on the basis of only either of the thickness of the recording medium and the heat capacity of the recording medium.SOLUTION: An image formation system comprises: a conveyance part 14 for conveying a recording medium P using a roller 24; a transfer part 32 for applying a transfer voltage to the recording medium conveyed by the conveyance part with a transfer body to transfer a toner image; a fixation part 34 for fixing the toner image to the recording medium to which the toner image has been transferred using a heating roller 35; and a processor 60A. The processor executes temperature control of the heating roller on the basis of a result detected by current value detection means 25a that detects a current value of an electric actuator 25 that rotates the roller and a result detected by resistance value detection means that detects a volume resistance of the recording medium when the toner image is transferred to the recording medium after the current value is detected by the current value detection means.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an image forming system. [Background technology]

[0002] Patent document 1 describes a fixing device that includes a detection unit that detects the load of a drive unit that drives a fixing unit that fixes an image formed on a medium, a detection unit that detects the type of medium using the detection result of the detection unit, and a setting unit that sets a threshold value for the detection unit to detect the type of medium for each temperature detected by a temperature detection unit that detects the temperature of the fixing unit or for each number of media on which an image is fixed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-58481 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to suppress poor fixing of a toner image onto a recording medium, compared to a case where the temperature of the heating roll is controlled based on only one of the thickness of the recording medium and the heat capacity of the recording medium. [Means for solving the problem]

[0005] The image forming system according to a first aspect of the present disclosure includes a transport unit that transports a recording medium using a roll, a transfer unit that transfers a toner image to the recording medium transported by the transport unit by applying a transfer voltage using a transfer body, a fixing unit that fixes the toner image to the recording medium to which the toner image has been transferred using a heating roll, and a processor, wherein the processor controls the temperature of the heating roll based on a detection result of a current value detection means that detects a current value of an electric actuator that rotates the roll, and a detection result of a resistance value detection means that detects the volume resistance of the recording medium when the toner image is transferred to the recording medium after detecting the current value by the current value detection means.

[0006] An image forming system according to a second aspect of the present disclosure is the image forming system according to the first aspect, characterized in that the roll of the transport section is a registration roll.

[0007] An image forming system according to a third aspect of the present disclosure is the image forming system according to the first or second aspect, further comprising an information input unit into which a user can input information regarding the type of the recording medium, and a notification unit capable of notifying the user, wherein the processor estimates the type of the recording medium based on the detection results of the current value detection means and the resistance value detection means, and when it determines that the estimated type of the recording medium differs from the type of the recording medium represented by the information input to the information input unit, causes the notification unit to execute a notification operation.

[0008] An image forming system according to a fourth aspect of the present disclosure is characterized in that, in the image forming system described in the third aspect, the notification unit is a display unit capable of displaying information regarding the estimated type of the recording medium.

[0009] An image forming system according to a fifth aspect of the present disclosure is characterized in that, in the image forming system described in the first or second aspect, the processor starts temperature control of the heating roll based only on the detection result of the current value detection means, and then performs temperature control of the heating roll based on the detection result of the current value detection means and the detection result of the resistance value detection means.

[0010] An image forming system according to a sixth aspect of the present disclosure is the image forming system according to the first or second aspect, further comprising a housing that houses the conveying unit, the transfer unit, and the fixing unit, a temperature and humidity sensor provided within the housing, and a basis weight detection unit that detects the basis weight of the recording medium, wherein the processor estimates the moisture content of the recording medium based on the humidity value detected by the temperature and humidity sensor and the volume resistance of the recording medium, acquires the basis weight of the recording medium from the basis weight detection unit, and, when the estimated moisture content is equal to or greater than a first threshold value and the acquired basis weight is within a predetermined range, executes a reduction process to lower the temperature of the heating roll compared to when the moisture content is less than the first threshold value or the basis weight is not within the predetermined range.

[0011] An image forming system according to a seventh aspect of the present disclosure is the image forming system according to the first aspect, further comprising a housing that houses the conveying unit, the transfer unit, and the fixing unit, and a temperature and humidity sensor provided within the housing, and the processor is characterized in that when the humidity value detected by the temperature and humidity sensor is equal to or less than a second threshold value and the volume resistance of the recording medium is equal to or less than a third threshold value, the processor does not perform a reduction process to lower the temperature of the heating roll compared to when the humidity value is greater than the second threshold value or the volume resistance of the recording medium is greater than the third threshold value.

[0012] An image forming system according to an eighth aspect of the present disclosure is the image forming system according to the seventh aspect, wherein the processor executes the reduction process when the humidity value is greater than the second threshold value or when the volume resistivity is greater than the third threshold value. Effect of the Invention

[0013] According to the image forming system relating to the first aspect of the present disclosure, poor fixing of a toner image to a recording medium can be suppressed compared to a case where the temperature of the heating roll is controlled based on only one of the thickness of the recording medium and the thermal capacity of the recording medium.

[0014] According to the image forming system according to the second aspect of the present disclosure, the number of parts is smaller than in a configuration in which a roll dedicated to measuring the thickness of the recording medium is provided.

[0015] The image forming system according to the third aspect of the present disclosure allows a user who has input information regarding the type of recording medium to the information input section to recognize that the input information regarding the type of recording medium is incorrect.

[0016] According to the image forming system according to the fourth aspect of the present disclosure, the user can be made aware of information relating to the estimated type of recording medium.

[0017] According to the image forming system relating to the fifth aspect of the present disclosure, poor fixing of the toner image to the recording medium can be suppressed compared to a case in which temperature control of the heating roll is started after the thickness and heat capacity of the recording medium are estimated.

[0018] According to the image forming system according to the sixth aspect of the present disclosure, curling of the recording medium is less likely to occur compared to a case where the temperature of the heating roll is constant regardless of the basis weight and moisture content.

[0019] A transfer device according to the seventh aspect of the present disclosure can suppress poor fixing of a toner image onto a recording medium compared to a case in which a reduction process is performed even when the detection value of the temperature and humidity sensor is below the second threshold value and the volume resistance of the recording medium is below the third threshold value.

[0020] In the transfer device according to the eighth aspect of the present disclosure, curling of the recording medium is less likely to occur compared to a case in which the temperature of the heating roll is constant regardless of the humidity value and the volume resistance. [Brief description of the drawings]

[0021] [Figure 1]1 is a schematic configuration diagram illustrating an image forming apparatus including an image forming system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a configuration diagram illustrating a toner image forming unit of the image forming apparatus according to the embodiment of the present disclosure. [Diagram 3] FIG. 2 is a front view of a transfer device according to an embodiment of the present disclosure, illustrating a color mode state. [Figure 4] FIG. 2 is a control block diagram of a hardware configuration of the image forming apparatus. [Diagram 5] FIG. 2 is a functional block diagram of a hardware configuration. [Figure 6] FIG. [Figure 7] FIG. 4 is a diagram illustrating an example of a current detected by a torque detection unit. [Figure 8] FIG. 13 is a diagram showing a heat capacity estimation map. [Figure 9] FIG. 4 is a diagram showing a temperature control map. [Figure 10] 1 is a flowchart showing a process executed by a CPU. [Figure 11] FIG. 2 is a view corresponding to FIG. 1 of a first modified example. [Figure 12] FIG. 13 is a functional block diagram of a hardware configuration of a first modified example. [Figure 13] 13 is a flowchart showing a process executed by a CPU in a first modified example. [Figure 14] FIG. 11 is a view of a second modified example corresponding to FIG. [Figure 15] 13 is a flowchart showing a process executed by a CPU in a second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] An example of an image forming system according to an embodiment of the present disclosure will be described with reference to Figures 1 to 10. Note that arrow H in each figure indicates the vertical direction, which is the up-down direction of the device, and arrow W indicates the horizontal direction, which is the width direction of the device.

[0023] (Overall configuration of image forming apparatus 10) 1, the image forming apparatus 10 includes an image forming section 12 that forms a toner image by electrophotography, and a transport section 14 that transports printing paper (recording medium) P as a recording medium along a transport path 16. The image forming apparatus 10 also includes a storage member 18 that stores the printing paper P, and a control section 60 that controls the entire apparatus.

[0024] In this image forming apparatus 10, the print paper P stored in the storage member 18 is transported by the transport unit 14 along the transport path 16. Furthermore, a toner image formed by the image forming unit 12 is formed on the print paper P being transported, and the print paper P with the toner image formed thereon is discharged to the outside of the housing 10a by the discharge rolls 26 described below.

[0025] [Image forming unit 12] 1, the image forming unit 12 includes a plurality of toner image forming units 30 each forming a toner image of each color, and a transfer unit 32 that transfers the toner images formed in the toner image forming units 30 onto a printing paper P. Furthermore, the image forming unit 12 includes a fixing device (fixing unit) 34 that fixes the toner images transferred onto the printing paper P by the transfer units 32 onto the printing paper P.

[0026] -Toner image forming unit 30- A plurality of toner image forming units 30 are provided to form toner images for each color. In this embodiment, toner image forming units 30Y, 30M, 30C, and 30K are provided for a total of four colors: yellow (Y), magenta (M), cyan (C), and black (K). In the following description, when there is no need to distinguish between yellow (Y), magenta (M), cyan (C), and black (K), the letters Y, M, C, and K attached to the reference characters are omitted.

[0027] 2, each toner image forming unit 30 includes a rotating cylindrical image carrier 40 and a charger 42 that charges the image carrier 40. The toner image forming unit 30 further includes an exposure device 44 that irradiates the charged image carrier 40 with exposure light to form an electrostatic latent image, and a developing device 46 that develops the electrostatic latent image into a toner image with developer Z that contains toner. As a result, the toner image forming unit 30 for each color forms an image of each color using the toner of the corresponding color.

[0028] 1, the image carriers 40 of each color are in contact with the rotating transfer belt 50. In the rotation direction of the transfer belt 50 (see the arrow in the figure), the toner image forming units 30 of yellow (Y), magenta (M), cyan (C), and black (K) are arranged in this order from the upstream side.

[0029] -Transfer section 32- The transfer unit 32 has a function of transferring the toner image formed by the toner image forming unit 30 onto the printing paper P. The transfer unit 32 will be described in detail later.

[0030] -Fixing device 34- As shown in FIG. 1, the fixing device 34 is disposed downstream of the transfer nip NT in the conveying direction of the print paper P. The fixing device 34 heats and pressurizes the toner image transferred to the print paper P to fix it to the print paper P. More specifically, the fixing device 34 includes a heating roll 35 incorporating a heater 35a, and a pressure roll 36 that faces the heating roll 35 and rotates following the heating roll 35. When the print paper P passes through the nip area between the heating roll 35 and the pressure roll 36, the toner image on the print paper P is fixed to the print paper P by the heat and pressure. Reference numeral 37 denotes a temperature sensor that detects the surface temperature of the heating roll 35. The fixing device 34 includes an electric motor 38 that drives the heating roll 35 to rotate at a predetermined speed.

[0031] [Transport section 14] 1, the transport section 14 includes a feed roll 20 that feeds the printing paper P stored in the storage member 18 onto the transport path 16, and a prevention roll 22 that prevents double feeding of the printing paper P fed by the feed roll 20. The transport section 14 further includes a registration roll (roll) 24 that adjusts the timing at which the printing paper P is fed into the transfer nip NT, and a discharge roll 26 that discharges the printing paper P, on which the toner image has been fixed by the fixing device 34, to the outside of the housing 10a.

[0032] The registration roll 24 is rotated by a rotational driving force generated by an electric motor (electric actuator) 25. The electric motor 25 is controlled by a control unit 60. The electric motor 25 is connected to a torque detection unit (current value detection means) 25a.

[0033] The torque detection unit 25 a detects the torque of the electric motor 25 as the value of a current flowing through the electric motor 25 .

[0034] The configuration of the torque detection unit 25a according to the present embodiment is not particularly limited as long as it can detect the torque of the electric motor 25. For example, the torque detection unit 25a may be configured to detect the torque of the electric motor 25 as a current value flowing through the electric motor 25, convert the detected current value into a voltage value, and output the voltage value. The torque detection unit 25a may be configured to measure a voltage between shunt resistors to detect a current. For example, the torque detection unit 25a may be configured to provide a resistor on a path through which a current flows through the electric motor 25, measure the voltage between the resistors, and detect a current. For example, the torque detection unit 25a may be configured to provide a current sensor using a Hall element on a path through which a current flows through the electric motor 25 to detect a current. For example, the torque detection unit 25a may be configured to be a torque detector that detects the torque of the electric motor 25.

[0035] Next, the transfer unit 32 will be described.

[0036] 3, the transfer section 32 includes a transfer belt 50 and primary transfer rolls 52 that are disposed on the opposite side of the image carriers 40 of each color across the transfer belt 50 and transfer the toner images formed on the image carriers 40 of each color to the transfer belt 50. The transfer section 32 also includes a contact / separation unit (not shown) that moves at least some of the multiple primary transfer rolls 52 to contact and separate the transfer belt 50 and the image carriers 40.

[0037] Furthermore, the transfer unit 32 includes a winding roll 56 around which the transfer belt 50 is wound, a driving roll 58 around which the transfer belt 50 is wound and which transmits a rotational force to the transfer belt 50, and a positioning roll 64 which positions the portion of the transfer belt 50 onto which the toner image is transferred. The transfer unit 32 also includes an applying roll 70 which applies tension to the transfer belt 50.

[0038] Furthermore, the transfer unit 32 includes a secondary transfer roll 54 that is disposed on the opposite side of the transfer belt 50 from the winding roll 56 and transfers the toner image transferred to the transfer belt 50 onto the printing paper P. A transfer nip NT that transfers the toner image onto the printing paper P is formed between the secondary transfer roll 54 and the transfer belt 50.

[0039] [Transfer belt 50, wrapping roll 56, driving roll 58] 3, the transfer belt 50 is endless and is disposed such that one end (the left end in the figure) in the device width direction is lower than the other end. The transfer belt 50 is an example of an endless member.

[0040] The axial direction of the winding roll 56 is the depth direction of the device, and one end portion of the transfer belt 50 in the width direction of the device is wound around the winding roll 56. The axial direction of the driving roll 58 is the depth direction of the device, and the other end portion of the transfer belt 50 in the width direction of the device is wound around the driving roll 58.

[0041] In this configuration, the drive roll 58 to which a drive force is transmitted from a drive source (not shown) rotates, causing the transfer belt 50 to rotate in the direction of the arrow in the figure (clockwise direction).

[0042] [Primary transfer roll 52, secondary transfer roll 54] 3, the primary transfer roll 52 of each color is disposed downstream of the drive roll 58 and upstream of the winding roll 56 in the rotation direction of the transfer belt 50 (hereinafter, "belt rotation direction"). The primary transfer roll 52 of each color is in contact with the inner circumferential surface of the transfer belt 50 on the opposite side of the transfer belt 50 to the image carrier 40 of each color. The secondary transfer roll 54 is disposed on the opposite side of the transfer belt 50 to the winding roll 56. The primary transfer roll 52 is an example of a primary transfer member, and the secondary transfer roll 54 is an example of a secondary transfer member.

[0043] In this configuration, the primary transfer rolls 52 of each color transfer the toner images formed on the image carriers 40 of each color to the transfer belt 50 while sandwiching the transfer belt 50 between the primary transfer rolls 52 and the image carriers 40 of each color. Furthermore, the secondary transfer roll 54 transfers the toner images transferred to the transfer belt 50 by the primary transfer rolls 52 to the print paper P conveyed through the transfer nip NT. Furthermore, a transfer voltage is applied to the secondary transfer roll 54 by constant current control executed by a constant current control unit 603 described later. Although not shown in the figure, a detection device capable of detecting that the print paper P has entered the secondary transfer roll 54 is provided near the secondary transfer roll 54. This detection device is connected to the control unit 60.

[0044] [Applying roll 70, positioning roll 64] 3, the application roll 70 is disposed downstream of the primary transfer roll 52K and upstream of the secondary transfer roll 54 in the belt rotation direction. The application roll 70 contacts the inner circumferential surface of the transfer belt 50 and presses the transfer belt 50. This applies tension to the transfer belt 50.

[0045] 3, a pair of positioning rolls 64 are provided in the belt rotation direction, with all of the primary transfer rolls 52 therebetween. Specifically, a positioning roll 64a is provided upstream of all of the primary transfer rolls 52 in the belt rotation direction, and a positioning roll 64b is provided downstream of all of the primary transfer rolls 52.

[0046] As shown in FIG. 6, the image forming apparatus 10 is further provided with a touch panel display unit 59. The display unit 59 has an input unit (information input unit) 59a and a first display unit 59b. A user of the image forming apparatus 10 can input information about the type of print paper P to be printed using the input unit 59a, for example. The types of print paper P include, for example, plain paper and coated paper. The information input using the input unit 59a is displayed on the first display unit 59b. For example, when a user inputs information representing plain paper using the input unit 59a, the words "plain paper" are displayed on the first display unit 59b. The second display unit (notification unit) (display unit) 59c displays a notification under the control of a display unit control unit 606, which will be described later.

[0047] 4, the control unit 60 includes, as a hardware configuration, a CPU (Central Processing Unit: processor) 60A, a ROM (Read Only Memory) 60B, a RAM (Random Access Memory) 60C, a storage 60D, a communication I / F (Interface) 60E, and an input / output I / F 60F. The CPU 60A, the ROM 60B, the RAM 60C, the storage 60D, the communication I / F 60E, and the input / output I / F 60F are connected to each other so as to be able to communicate with each other via a bus 60Z.

[0048] The CPU 60A is a central processing unit that executes various programs and controls each part. That is, the CPU 60A reads a program from the ROM 60B or the storage 60D, and executes the program using the RAM 60C as a working area. The CPU 60A controls each component and performs various arithmetic processing according to the program recorded in the ROM 60B or the storage 60D.

[0049] The ROM 60B stores various programs and various data. The RAM 60C temporarily stores programs or data as a working area. The storage 60D is configured with a storage device such as a hard disk drive (HDD) or a solid state drive (SSD), and stores various programs and various data. The communication I / F 60E is an interface for communicating with other devices.

[0050] 5 is a block diagram showing an example of the functional configuration of the control unit 60. The control unit 60 has, as its functional configuration, a rotation control unit 601, a thickness estimation unit 602, a constant current control unit 603, a heat capacity estimation unit (resistance value detection means) 604, a temperature control unit 605, and a display control unit 606. The rotation control unit 601, the thickness estimation unit 602, the constant current control unit 603, the heat capacity estimation unit 604, the temperature control unit 605, and the display control unit 606 are realized by the CPU 60A reading and executing a program stored in the ROM 60B.

[0051] The rotation control unit 601 controls the rotation of the electric motor 25 and the electric motor 38 .

[0052] The thickness estimation unit 602 detects the thickness of the printing paper P based on the current value detected by the torque detection unit 25a. As shown in FIG. 7, the current value detected by the torque detection unit 25a rises sharply at the timing when the printing paper P enters the registration roll 24, becoming a peak value with an upward convexity, and then drops sharply at the timing when the printing paper P is discharged from the registration roll 24, becoming a peak value with a downward convexity. In the example shown in FIG. 7, the printing paper P enters the registration roll 24 at time t1, and the printing paper P is discharged from the registration roll 24 at time t2. The current detected by the torque detection unit 25a changes depending on the thickness of the printing paper P, including the peak values ​​when the printing paper P enters the registration roll 24 and when it is discharged, and the value while passing through the registration roll 24. In the detection function of this embodiment, the CPU 60A detects the thickness of the printing paper P by utilizing the fact that the current detected by the torque detection unit 25a changes depending on the thickness of the printing paper P.

[0053] As described above, the constant current control unit 603 executes the constant current control for applying the transfer voltage to the secondary transfer roll 54 .

[0054] The heat capacity estimation unit 604 acquires the volume resistance of the print paper P using the current value and voltage value of the power supplied to the secondary transfer roll 54 by constant current control. Furthermore, the heat capacity estimation unit 604 estimates the heat capacity of the print paper P using a heat capacity estimation map 61 (see FIG. 8) that defines the relationship between the volume resistance of the print paper P and the heat capacity of the print paper P, and the acquired volume resistance of the print paper P. As is clear from FIG. 8, the heat capacity and volume resistance of the print paper P are approximately proportional. Note that this heat capacity estimation map 61 is just an example, and the relationship between the volume resistance and the heat capacity defined in the heat capacity estimation map 61 may be modified while taking into account the temperature and humidity inside the housing 10a.

[0055] The temperature control unit 605 controls the heater 35a by applying the thickness of the printing paper P estimated by the thickness estimation unit 602 and the heat capacity of the printing paper P estimated by the heat capacity estimation unit 604 to the temperature control map 62 shown in FIG. 9 and recorded in the ROM 60B. The temperature control map 62 is a two-dimensional map defined by the thickness of the printing paper P and the heat capacity of the printing paper P. The thickness of the printing paper P in the temperature control map 62 is defined by three thicknesses, and the heat capacity of the temperature control map 62 is defined by two capacities. The thickness of the printing paper gradually increases in the order of thickness 1, thickness 2, and thickness 3. Also, heat capacity 2 is greater than heat capacity 1. For example, when the estimated thickness of the printing paper P is "thickness 2" and the estimated heat capacity of the printing paper P is "heat capacity 1", the temperature control unit 605 controls the heater 35a so that the target temperature of the heating roll 35 (the temperature detected by the temperature sensor 37) becomes the set temperature 2.

[0056] The display control unit 606 controls the display unit 59. For example, the display control unit 606 causes the information inputted by the input unit 59a to be displayed on the first display unit 59b.

[0057] Furthermore, the display unit control unit 606 causes the second display unit 59c to display a notification when the information on the type of printing paper P input by the input unit 59a differs from the estimated type of printing paper P. The ROM 60B records paper information on the thickness and heat capacity of various types of printing paper. Therefore, when the paper information includes information on the thickness of the printing paper P input by the input unit 59a, and the information on the thickness included in the paper information differs from the thickness estimated by the thickness estimation unit 602, the second display unit 59c displays a notification. When the paper information includes information on the heat capacity of the printing paper P input by the input unit 59a, and the information on the heat capacity included in the paper information differs from the heat capacity estimated by the heat capacity estimation unit 604, the second display unit 59c displays a notification. For example, if the printing paper P input by the input unit 59a is a paper of a predetermined thickness and the printing paper P estimated by the thickness estimation unit 602 is a paper of a thickness thicker than this predetermined thickness, the second display unit 59c displays the text "The paper to be printed is a different type of paper from the input paper." Also, if the heat capacity of the printing paper P input by the input unit 59a is a predetermined value and the heat capacity of the printing paper P estimated by the heat capacity estimation unit 604 is larger than this predetermined value, the second display unit 59c displays the text "The paper to be printed is a different type of paper from the input paper."

[0058] Of the components described above, the conveying section 14, the registration roll 24, the electric motor 25, the torque detection section 25a, the transfer section 32, the fixing device 34, the secondary transfer roll 54, the display section 59, the control section 60, the heat capacity estimation map 61, and the temperature control map 62 are components of the image forming system 65.

[0059] Next, the operation of the image forming apparatus 10 having the above configuration will be described with reference to the flowchart of Fig. 10. The CPU 60A repeatedly executes the process of the flowchart of Fig. 10 every time a predetermined time elapses.

[0060] First, in step S10 (hereinafter, the word "step" will be omitted), the CPU 60A determines whether or not the printing paper P has entered the registration rolls 24, based on information received from the torque detection unit 25a.

[0061] If the answer is Yes in S10, the CPU 60A proceeds to S11, where it estimates the thickness of the print paper P based on the information received from the torque detection unit 25a.

[0062] If the answer is Yes in S11, the CPU 60A proceeds to S12, where it determines whether or not the print paper P has entered the secondary transfer roll 54 based on the information received by the detection device.

[0063] If the answer is Yes in S12, the CPU 60A proceeds to S13, where it estimates the heat capacity of the print paper P based on the volume resistivity and heat capacity estimation map 61 of the print paper P.

[0064] When the processing of S13 is completed, the CPU 60A proceeds to S14, and applies the information regarding the thickness of the printing paper P obtained in S11 and the information regarding the heat capacity of the printing paper P obtained in S13 to the temperature control map 62, thereby controlling the heater 35a so that the target temperature of the heating roll 35 becomes the set temperature specified in the temperature control map 62.

[0065] When the process of S14 is completed, the CPU 60A proceeds to S15, where it determines whether or not there is an error in the information about the printing paper P inputted using the input section 59a.

[0066] If the result of S15 is Yes, CPU 60A proceeds to S16, and causes second display unit 59c to display a notification.

[0067] When the determinations in S10, S12, and S15 are No, or when the process of S16 is completed, the CPU 60A temporarily ends the process of the flowchart in FIG.

[0068] As described above, the image forming system 65 of this embodiment controls the temperature of the heating roll 35 (heater 35a) based on both the thickness of the printing paper P and the heat capacity of the printing paper P. Therefore, the image forming system 65 can suppress poor fixing of the toner image to the printing paper P, compared to when the temperature of the heating roll 35 is controlled based on only one of the thickness of the printing paper P and the heat capacity of the printing paper P. For example, assume an image forming system of a comparative example in which the temperature of the heating roll 35 (heater 35a) is controlled based on only the thickness of the printing paper P. In the image forming system of the comparative example, the temperature control of the heating roller (heater) when forming a toner image on the printing paper A (not shown) is the same as the temperature control of the heating roller (heater) when forming a toner image on the printing paper B (not shown) which has the same thickness as the printing paper A but a different heat capacity. Therefore, in the image forming system of the comparative example, poor fixing of the toner image is likely to occur on at least one of the printing paper A and the printing paper B. In the image forming system 65 of this embodiment, poor fixing of the toner image to the printing paper A and the printing paper B is more likely to be suppressed than in this comparative example.

[0069] Furthermore, when the thickness of the printing paper P is estimated using a roll provided downstream of the secondary transfer roll 54 and upstream of the heating roll 35 and pressure roll 36, and an electric actuator that applies a driving force to this roll, there is a risk that the toner image on the printing paper P will be disturbed by this roll. In contrast, in the image forming system 65 of the present embodiment, the thickness of the printing paper P is estimated using the registration roll 24 and electric motor 25 located upstream of the secondary transfer roll 54, so there is no risk of the toner image on the printing paper P being disturbed by the registration roll 24.

[0070] Furthermore, when the thickness of the printing paper P is estimated using the heating roll 35 and the electric motor 38, when the printing paper P that is initially sent from the storage member 18 to the heating roll 35 and the pressure roll 36 after the main switch of the image forming apparatus 10 is turned on enters the heating roll 35 and the pressure roll 36, the temperature of the heating roll 35 (heater 35a) cannot be controlled based on both the thickness of the printing paper P and the heat capacity of the printing paper P. In contrast, in the image forming system 65 of this embodiment, the thickness of the printing paper P is estimated using the registration roll 24 and the electric motor 25 located upstream of the secondary transfer roll 54, so that the temperature of the heating roll 35 (heater 35a) can be controlled based on both the thickness of the printing paper P and the heat capacity of the printing paper P even when the printing paper P that is initially sent from the storage member 18 to the heating roll 35 and the pressure roll 36 enters the heating roll 35 and the pressure roll 36.

[0071] In the image forming system 65, the registration roll 24 and the electric motor 25, which are existing members in the image forming apparatus, are used to estimate the thickness of the print paper P. Therefore, the image forming system 65 has a smaller number of parts compared to a configuration including a roll dedicated to measuring the thickness of the print paper P.

[0072] Furthermore, in the image forming system 65, the second display unit 59c displays a notification when the information about the type of print paper P input by the input unit 59a differs from the estimated type of print paper P. Therefore, the image forming system 65 allows the user who inputs the information about the type of print paper P to the input unit 59a to recognize that the input information about the type of print paper P contains an error.

[0073] The image forming apparatus 10 according to the present embodiment has been described above with reference to the drawings. However, the image forming apparatus 10 according to the present embodiment is not limited to the one shown in the drawings, and the design can be appropriately modified within the scope that does not deviate from the gist of the present invention.

[0074] For example, the present invention may be embodied in the form of a first modified example shown in Figs. 11 to 13. As shown in Fig. 11, a basis weight detection unit 70 is provided in the housing 10a of the first modified example. The basis weight detection unit 70 is located downstream of the delivery roll 20 and upstream of the prevention roll 22. The basis weight detection unit 70 measures the basis weight of the print paper P transported by the transport unit 14. For example, the basis weight detection unit 70 may be a device that detects the basis weight by emitting light toward the print paper P and measuring the light that has passed through the print paper P. The basis weight detection unit 70 may also be a device that detects the basis weight by emitting ultrasonic waves toward the print paper P and measuring the ultrasonic waves that have passed through the print paper P. The basis weight detection unit 70 is connected to the control unit 60.

[0075] 12 is a block diagram showing an example of the functional configuration of the control unit 60 of the first modified example. The control unit 60 has, as its functional configuration, a rotation control unit 601, a thickness estimation unit 602, a constant current control unit 603, a heat capacity estimation unit 604, a temperature control unit 605, a display unit control unit 606, and a moisture content calculation unit 607. The moisture content calculation unit 607 calculates the moisture content of the printing paper P based on the humidity value and the volume resistance of the printing paper P. For example, the moisture content calculation unit 607 calculates the moisture content of the printing paper P by using a map (not shown) that defines the relationship between the humidity value and the volume resistance.

[0076] When the calculated moisture content is equal to or greater than a predetermined first threshold and the basis weight value acquired by the basis weight detection unit 70 is within a predetermined range, the temperature control unit 605 executes a reduction process to make the temperature of the heating roll 35 lower than the set temperature, compared to when the moisture content is less than the first threshold or the basis weight is not within the predetermined range. That is, the temperature control unit 605 controls the heater 35a so that the temperature of the heating roll 35 is a predetermined value lower than the set temperature determined based on the temperature control map 62. Note that when the printing paper P is plain paper, the basis weight value of the printing paper P is within the predetermined range.

[0077] A CPU 60A of the first modified example repeatedly executes the process of the flowchart in FIG. 13 every time a predetermined time elapses.

[0078] First, the processes in S10 to S13 are the same as those in the embodiment.

[0079] When the process of S13 is completed, the CPU 60A proceeds to S13A, where it determines whether or not the moisture content of the print paper P is equal to or greater than a first threshold value.

[0080] If the answer to the question in S13A is Yes, the CPU 60A proceeds to S13B, where it determines whether or not the basis weight of the print paper P is within a predetermined range.

[0081] If the result of the determination in S13B is Yes, the CPU 60A proceeds to S14A, where it controls the temperature of the heating roll 35 while executing the reduction process.

[0082] On the other hand, if the determination in S13B is No, the CPU 60A proceeds to S14.

[0083] When the process of S14 or S14A is completed, the CPU 60A proceeds to S15.

[0084] As described above, in the image forming system 65 of the first modification, the reduction process is executed when the moisture content of the printing paper P is equal to or greater than the first threshold value and the basis weight value acquired by the basis weight detection unit 70 is within a predetermined range. Therefore, the printing paper P is less likely to curl than when the temperature of the heating roll 35 is constant regardless of the basis weight and moisture content of the printing paper P. That is, for example, if the reduction process is not executed when the moisture content of the printing paper P is equal to or greater than the first threshold value, moisture is excessively lost from the surface of the printing paper P that contacts the heating roll 35, and the moisture amount difference between the front and back of the printing paper P increases, which makes the printing paper P more likely to curl. In the first modification, the reduction process is executed when the moisture content of the printing paper P is equal to or greater than the first threshold value and the basis weight value acquired by the basis weight detection unit 70 is within a predetermined range, so the moisture amount difference between the front and back of the printing paper P is less likely to increase and the printing paper P is less likely to curl.

[0085] The present invention may also be embodied in a second modified embodiment shown in Fig. 14 and Fig. 15. As shown in Fig. 14, a temperature and humidity sensor 71 is provided in the housing 10a of the second modified embodiment. The temperature and humidity sensor 71 detects the temperature and humidity inside the housing 10a. Hereinafter, the humidity detected by the temperature and humidity sensor 71 will be referred to as the humidity value. The temperature and humidity sensor 71 is connected to the control unit 60.

[0086] The temperature control unit 605 of the second modified example does not execute the reduction process when the humidity value is equal to or less than the second threshold value and the volume resistance of the printing paper P is equal to or less than the third threshold value. On the other hand, the temperature control unit 605 executes the reduction process when the humidity value is greater than the second threshold value or the volume resistance is greater than the third threshold value.

[0087] A CPU 60A of the second modified example repeatedly executes the process of the flowchart in FIG. 15 every time a predetermined time elapses.

[0088] First, the processes in S10 to S13 are the same as those in the embodiment.

[0089] When the process of S13 is completed, the CPU 60A proceeds to S13C to determine whether the humidity value is equal to or lower than the second threshold value and the volume resistivity of the printing paper P is equal to or lower than a third threshold value.

[0090] If the determination in S13C is Yes, the CPU 60A proceeds to S14. On the other hand, if the determination in S13C is No, the CPU 60A proceeds to S14A.

[0091] When the process of S14 or S14A is completed, the CPU 60A proceeds to S15.

[0092] As described above, in the image forming system 65 of the second modified example, the reduction process is not executed when the humidity value is equal to or less than the second threshold value and the volume resistance of the printing paper P is equal to or less than the third threshold value. In other words, when the humidity value is equal to or less than the second threshold value, it is estimated that the moisture content of the printing paper P is low. Therefore, in this case, it is not necessary to execute the reduction process. Therefore, according to the image forming system 65 of the first modified example, poor fixing of the toner image to the printing paper P can be suppressed compared to when the reduction process is executed even when the humidity value is equal to or less than the second threshold value and the volume resistance of the printing paper P is equal to or less than the third threshold value.

[0093] Furthermore, in the image forming system 65 of the second modification, the reduction process is executed when the humidity value is greater than the second threshold value or the volume resistance is greater than the third threshold value. Therefore, the print paper P is less likely to curl than when the temperature of the heating roll 35 is constant regardless of the humidity value and the volume resistance.

[0094] The image forming apparatus 10 is not limited to an intermediate transfer type, but may be a direct transfer color or monochrome machine. In that case, too, the heat capacity of the printing paper P may be estimated by using a transfer roll.

[0095] The image forming system 65 may start temperature control of the heating roll 35 (heater 35a) based only on the detection result of the torque detection unit (current value detection means) 25a, and then control the temperature of the heating roll 35 (heater 35a) based on the detection result of the torque detection unit 25a and the detection result of the heat capacity estimation unit (resistance value detection means) 604. That is, the image forming system 65 may control the heater 35a so that the heating roll 35 reaches a tentative target temperature based only on the detection result of the torque detection unit (current value detection means) 25a, and then control the heater 35a based on the temperature control map 62. According to this modification, it is easier to suppress poor fixing of the toner image to the printing paper P compared to the case where temperature control of the heating roll 35 (heater 35a) is started after the thickness and heat capacity of the printing paper P are estimated.

[0096] The recording medium may be a medium different from the printing paper P. For example, the recording medium may be a transparent film.

[0097] (((1))) A conveying unit that conveys the recording medium using a roll; a transfer unit that applies a transfer voltage to the recording medium conveyed by the conveyance unit using a transfer body to transfer a toner image; a fixing section that fixes the toner image onto the recording medium by using a heating roll; A processor; Equipped with The processor, An image forming system that controls the temperature of the heating roll based on the detection result of a current value detection means that detects the current value of an electric actuator that rotates the roll, and the detection result of a resistance value detection means that detects the volume resistance of the recording medium when the toner image is transferred to the recording medium after the current value detection means detects the current value.

[0098] (((2))) The roll of the transport section is a registration roll. The image forming system according to (((1))).

[0099] (((3))) an information input section in which a user can input information regarding the type of the recording medium; A notification unit capable of notifying the user; Equipped with The processor, estimating the type of the recording medium based on the detection results of the current value detection means and the resistance value detection means; when it is determined that the estimated type of the recording medium is different from the type of the recording medium represented by the information input to the information input unit, causing the notification unit to perform a notification operation. The image forming system according to (((1))) or ((2)).

[0100] (((4))) the notification unit is a display unit capable of displaying information regarding the estimated type of the recording medium. The image forming system according to (((3))).

[0101] (((5))) The processor, after starting temperature control of the heating roll based only on the detection result of the current value detection means, the temperature control of the heating roll is performed based on the detection result of the current value detection means and the detection result of the resistance value detection means; 13. An image forming system according to any one of ((1))) to (((4))).

[0102] (((6))) a housing that houses the conveying unit, the transfer unit, and the fixing unit; A temperature and humidity sensor provided in the housing; a basis weight detection unit for detecting a basis weight of the recording medium; Equipped with The processor, estimating a moisture content of the recording medium based on the humidity value detected by the temperature and humidity sensor and the volume resistivity of the recording medium; obtaining a basis weight of the recording medium from the basis weight detection unit; When the estimated moisture content is equal to or greater than a first threshold and the acquired basis weight is within a predetermined range, a reduction process is executed to lower the temperature of the heating roll compared to a case where the moisture content is less than the first threshold or the basis weight is not within the predetermined range. 13. An image forming system according to any one of ((1))) to (((5))).

[0103] (((7))) a housing that houses the conveying unit, the transfer unit, and the fixing unit; A temperature and humidity sensor provided in the housing; Equipped with The processor, when the humidity value detected by the temperature and humidity sensor is equal to or less than a second threshold value and the volume resistance of the recording medium is equal to or less than a third threshold value, a reduction process for lowering the temperature of the heating roll is not performed compared to when the humidity value is greater than the second threshold value or the volume resistance of the recording medium is greater than the third threshold value. 13. An image forming system according to any one of ((1))) to (((6))).

[0104] (((8))) The processor, The reduction process is performed when the humidity value is greater than the second threshold value or when the volume resistivity is greater than the third threshold value. The image forming system according to (((7))). [Explanation of symbols]

[0105] 14 Conveyor section 24 Resist roll (roll) 25 Electric motor (electric actuator) 25a Torque detection unit (current value detection means) 32 Transcription section 34 Fixing device (fixing section) 54 Secondary transfer roll 59 Display section 59a Input section (information input section) 59c 2nd display section (notification section) (display section) 60A CPU (processor) 604 Heat capacity estimation unit (resistance value detection means) 65 Image Formation System 70 Basis weight detection unit 71 Temperature and humidity sensor P Printing paper (recording medium)

Claims

1. A conveying unit that conveys the recording medium using a roll; a transfer unit that applies a transfer voltage to the recording medium conveyed by the conveyance unit using a transfer body to transfer a toner image; a fixing section that fixes the toner image onto the recording medium by using a heating roll; A processor; Equipped with The processor, An image forming system that controls the temperature of the heating roll based on the detection result of a current value detection means that detects the current value of an electric actuator that rotates the roll, and the detection result of a resistance value detection means that detects the volume resistance of the recording medium when the toner image is transferred to the recording medium after the current value detection means detects the current value.

2. The roll of the transport section is a registration roll. The image forming system according to claim 1 .

3. an information input section in which a user can input information regarding the type of the recording medium; A notification unit capable of notifying the user; Equipped with The processor, estimating the type of the recording medium based on the detection results of the current value detection means and the resistance value detection means; when it is determined that the estimated type of the recording medium is different from the type of the recording medium represented by the information input to the information input unit, causing the notification unit to perform a notification operation.

3. The image forming system according to claim 1 or 2.

4. the notification unit is a display unit capable of displaying information regarding the estimated type of the recording medium. The image forming system according to claim 3 .

5. The processor, after starting temperature control of the heating roll based only on the detection result of the current value detection means, the temperature control of the heating roll is performed based on the detection result of the current value detection means and the detection result of the resistance value detection means; 3. The image forming system according to claim 1 or 2.

6. a housing that houses the conveying unit, the transfer unit, and the fixing unit; A temperature and humidity sensor provided in the housing; a basis weight detection unit for detecting a basis weight of the recording medium; Equipped with The processor, estimating a moisture content of the recording medium based on the humidity value detected by the temperature and humidity sensor and the volume resistivity of the recording medium; obtaining a basis weight of the recording medium from the basis weight detection unit; When the estimated moisture content is equal to or greater than a first threshold and the acquired basis weight is within a predetermined range, a reduction process is executed to lower the temperature of the heating roll compared to a case where the moisture content is less than the first threshold or the basis weight is not within the predetermined range.

3. The image forming system according to claim 1 or 2.

7. a housing that houses the conveying unit, the transfer unit, and the fixing unit; A temperature and humidity sensor provided in the housing; Equipped with The processor, when the humidity value detected by the temperature and humidity sensor is equal to or less than a second threshold value and the volume resistance of the recording medium is equal to or less than a third threshold value, a reduction process for lowering the temperature of the heating roll is not performed compared to when the humidity value is greater than the second threshold value or the volume resistance of the recording medium is greater than the third threshold value. The image forming system according to claim 1 .

8. The processor, The reduction process is performed when the humidity value is greater than the second threshold value or when the volume resistivity is greater than the third threshold value. The image forming system according to claim 7.

Images