Image forming system

Abstract

The invention discloses an image forming system including: a transport unit that transports a recording medium using a roller; a transfer section that transfers a toner image onto the recording medium conveyed by the conveying section by applying a transfer voltage to a transfer body; a fixing section that fixes the toner image on the recording medium to which the toner image is transferred by using a heating roller; and a processor that performs temperature control of the heating roller based on a detection result of a current value detection unit that detects a current value of an electric actuator that rotates the roller and a detection result of a resistance value detection unit that detects a resistance value of the electric actuator that rotates the roller. The resistance value detection unit detects a volume resistance of the recording medium when the toner image is transferred onto the recording medium after the current value is detected by the current value detection unit.

Description

Technical Field

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

[0002] Japanese Patent Gazette No. 2017-58481 describes a fixing device comprising: a detection unit that detects a load of a driving unit that drives the fixing unit to fix 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 each number of media on which the image is fixed. Summary of the invention

[0003] An object of the present invention is to suppress the fixing failure of a toner image on a recording medium, compared with a case where the temperature of a heating roller is controlled based on only one of the thickness of the recording medium and the heat capacity of the recording medium.

[0004] According to a first aspect of the present invention, there is provided an image forming system comprising: a conveying section that conveys a recording medium using a roller; a transfer section that transfers a colorant image to the recording medium conveyed by the conveying section by applying a transfer voltage through a transfer body; a fixing section that fixes the colorant image on the recording medium to which the colorant image is transferred using a heating roller; and a processor that controls the temperature of the heating roller based on a detection result of a current value detection unit that detects a current value of an electric actuator that rotates the roller and a detection result of a resistance value detection unit that detects a volume resistance of the recording medium when the colorant image is transferred to the recording medium after the current value detection unit detects the current value.

[0005] According to a second aspect of the present invention, in the image forming system of the first aspect, the roller of the conveying portion is a registration roller.

[0006] According to the third aspect of the present invention, in the image forming system of the first or second aspect, there is provided: an information input unit, which enables a user to input information related to the type of the recording medium; and a notification unit, which can notify the user, the processor infers the type of the recording medium based on the detection results of the current value detection unit and the resistance value detection unit, and when it is determined that the inferred type of the recording medium is different from the type of the recording medium represented by the information input to the information input unit, the notification unit performs a notification action.

[0007] According to a fourth aspect of the present invention, in the image forming system according to the third aspect, the notification unit is a display unit capable of displaying information related to the estimated type of the recording medium.

[0008] According to the fifth aspect of the present invention, in the image forming system of any one of the first to fourth aspects, after the processor starts the temperature control of the heating roller based only on the detection result of the current value detection unit, it performs the temperature control of the heating roller based on the detection result of the current value detection unit and the detection result of the resistance value detection unit.

[0009] According to the sixth aspect of the present invention, in the image forming system of any one of the first to fifth aspects, there is provided: a frame which accommodates the conveying section, the transfer section and the fixing section; a temperature and humidity sensor which is arranged in the frame; and a basis weight detection section which detects the basis weight of the recording medium, 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 resistivity of the recording medium, obtains the basis weight of the recording medium from the basis weight detection section, and when the estimated moisture content is above a first threshold value and the obtained basis weight is included in a prescribed range, performs a reduction process of lowering the temperature of the heating roller compared with a case where the moisture content is less than the first threshold value or the basis weight is not included in the prescribed range.

[0010] According to the seventh aspect of the present invention, in the image forming system of any one of the first to sixth aspects, there is provided: a frame which accommodates the conveying section, the transfer section and the fixing section; and a temperature and humidity sensor which is arranged in the frame, and when the humidity value detected by 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, the processor does not perform the processing of reducing the temperature of the heating roller compared with the case where 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.

[0011] According to an eighth aspect of the present invention, in the image forming system of the seventh aspect, the processor executes the lowering process when the humidity value is greater than the second threshold value or when the volume resistivity is greater than the third threshold value.

[0012] (Effect)

[0013] According to the first aspect, compared with a case where the temperature of the heating roller is controlled based on only one of the thickness of the recording medium and the heat capacity of the recording medium, it is possible to suppress poor fixing of the toner image on the recording medium.

[0014] According to the second aspect, the number of parts is reduced compared to a configuration in which a roller dedicated to measuring the thickness of a recording medium is provided.

[0015] According to the third aspect, the user who inputs the information on the type of the recording medium into the information input unit is made aware that the input information on the type of the recording medium is incorrect.

[0016] According to the fourth aspect, the user is made aware of information related to the estimated type of the recording medium.

[0017] According to the fifth aspect, compared with the case where the temperature control of the heating roller is started after the thickness and heat capacity of the recording medium are estimated, it is possible to suppress the fixing failure of the toner image on the recording medium.

[0018] According to the sixth aspect, compared with a case where the temperature of the heating roller is constant regardless of the basis weight and the moisture content, the recording medium is less likely to curl.

[0019] According to the seventh aspect, compared with the case where the reduction process is performed even when the detection value of the temperature and humidity sensor is below the second threshold and the volume resistance of the recording medium is below the third threshold, it is possible to suppress the fixing failure of the toner image on the recording medium.

[0020] According to the eighth aspect, compared with a case where the temperature of the heating roller is constant regardless of the humidity value and the volume resistivity, the recording medium is less likely to curl. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram showing an image forming apparatus including an image forming system according to an embodiment of the present invention;

[0022] Figure 2 is a structural diagram showing a toner image forming unit of an image forming apparatus according to an embodiment of the present invention;

[0023] Figure 3 is a front view showing a state of a transfer device in a color mode according to an embodiment of the present invention;

[0024] Figure 4 is a control block diagram of the hardware structure of the image forming device;

[0025] Figure 5 It is a functional block diagram of the hardware structure;

[0026] Figure 6 is a diagram showing a display unit;

[0027] Figure 7 is a diagram showing an example of current detected by a torque detection unit;

[0028] Figure 8is a diagram showing a heat capacity estimation diagram;

[0029] Fig. 9 It is a diagram showing a temperature control diagram;

[0030] Fig.10 is a flow chart showing a process performed by the CPU;

[0031] Fig.11 is the first variant of Figure 1 The corresponding figure;

[0032] Fig.12 is a functional block diagram of the hardware structure of the first variant;

[0033] Fig.13 is a flowchart showing a process executed by the CPU of the first modification example;

[0034] Fig.14 is the second variant of Figure 1 The corresponding figure;

[0035] Fig.15 This is a flowchart showing the processing executed by the CPU according to the second modification. DETAILED DESCRIPTION

[0036] according to Figures 1 to 10 An example of an image forming system according to an embodiment of the present invention will be described. In addition, arrow H shown in each figure is a vertical direction, indicating the vertical direction of the device, and arrow W is a horizontal direction, indicating the width direction of the device.

[0037] (Overall Structure of Image Forming Apparatus 10)

[0038] like Figure 1 As shown, the image forming apparatus 10 includes an image forming unit 12 for forming a toner image by electrophotography, and a transport unit 14 for transporting a printing paper (recording medium) P as a recording medium along a transport path 16. In addition, the image forming apparatus 10 includes a storage unit 18 for storing the printing paper P and a control unit 60 for controlling the entire apparatus.

[0039] In the image forming apparatus 10, the printing paper P accommodated in the accommodating member 18 is transported by the transporting section 14 along the transporting path 16. Then, the toner image formed by the image forming section 12 is formed on the transported printing paper P, and the printing paper P with the toner image formed thereon is discharged to the outside of the housing 10a by the discharge rollers 26 described later.

[0040] [Image forming unit 12]

[0041] like Figure 1As shown in FIG. 1 , the image forming section 12 includes a plurality of toner image forming sections 30 for forming toner images of respective colors, and a transfer section 32 for transferring the toner images formed by the toner image forming sections 30 onto the printing paper P. The image forming section 12 further includes a fixing device (fixing section) 34 for fixing the toner images transferred onto the printing paper P by the transfer section 32 onto the printing paper P.

[0042] -Toner Image Forming Section 30-

[0043] A plurality of toner image forming units 30 are provided to form toner images for each color. In the present embodiment, toner image forming units 30Y, 30M, 30C, and 30K for a total of four colors, namely yellow (Y), magenta (M), cyan (C), and black (K) are provided. In the following description, when it is not necessary to distinguish between yellow (Y), magenta (M), cyan (C), and black (K), Y, M, C, and K added to the symbols are omitted.

[0044] The toner image forming units 30 of the respective colors are basically configured in the same manner except for the toner used. Figure 2 As shown in FIG. 1 , the toner image forming unit 30 includes a rotating cylindrical image holding body 40 and a charger 42 for charging the image holding body 40. Furthermore, the toner image forming unit 30 includes an exposure device 44 for irradiating the charged image holding body 40 with exposure light to form an electrostatic latent image, and a developing device 46 for developing the electrostatic latent image into a toner image using a developer Z containing toner. Thus, the toner image forming unit 30 of each color forms an image of each color using the toner of each color.

[0045] In addition, if Figure 1 As shown, the image holders 40 of each color are in contact with the transfer belt 50 that moves in a circular motion. In addition, in the circular direction of the transfer belt 50 (refer to the arrow in the figure), the toner image forming units 30 of yellow (Y), magenta (M), cyan (C) and black (K) are arranged in order from the upstream side.

[0046] -Transfer unit 32-

[0047] The transfer section 32 has a function of transferring the toner image formed by the toner image forming section 30 onto the printing paper P. The transfer section 32 will be described in detail later.

[0048] -Fixing device 34-

[0049] like Figure 1As shown, the fixing device 34 is arranged on the downstream side of the transfer nip NT in the conveying direction of the printing paper P. The fixing device 34 heats and pressurizes the toner image transferred to the printing paper P to fix it on the printing paper P. More specifically, the fixing device 34 includes a heating roller 35 with a built-in heater 35a and a pressure roller 36 that rotates opposite to the heating roller 35 and driven by it. When the printing paper P passes through the nip area between the heating roller 35 and the pressure roller 36, the toner image on the printing paper P is fixed to the printing paper P by heat and pressure. In addition, the symbol 37 is a temperature sensor that detects the surface temperature of the heating roller 35. Moreover, the fixing device 34 includes an electric motor 38 that drives the heating roller 35 to rotate at a specified speed.

[0050] [Transmission unit 14]

[0051] like Figure 1 As shown, the conveying section 14 includes a delivery roller 20 for delivering the printing paper P accommodated in the accommodating member 18 to the conveying path 16, and a prevention roller 22 for preventing the duplicate delivery of the printing paper P delivered by the delivery roller 20. The conveying section 14 also includes a registration roller (roller) 24 and a discharge roller 26. The registration roller 24 adjusts the timing of delivering the printing paper P to the transfer nip portion NT, and the discharge roller 26 discharges the printing paper P to which the toner image is fixed by the fixing device 34 to the outside of the frame 10a.

[0052] The registration roller 24 is rotated by a rotational driving force generated by an electric motor (electric actuator) 25. The electric motor 25 is controlled by the control unit 60. The electric motor 25 is connected to a torque detection unit (current value detection means) 25a.

[0053] The torque detection unit 25 a detects the torque of the electric motor 25 as a current value flowing through the electric motor 25 .

[0054] In addition, the structure of the torque detection unit 25a of the present embodiment is not particularly limited, as long as it can detect the torque of the electric motor 25. For example, as the torque detection unit 25a, a structure that detects the torque of the electric motor 25 as the current value flowing through the electric motor 25 and converts the detected current value into a voltage value and outputs it can also be applied. In addition, as the torque detection unit 25a, a structure that measures the voltage between shunt resistors to detect the current can also be applied. In addition, for example, as the torque detection unit 25a, a structure that sets a resistor on the path where the current flows through the electric motor 25 and measures the voltage between the resistors to detect the current can also be applied. In addition, for example, as the torque detection unit 25a, a structure that sets a current sensor based on a Hall element on the path where the current flows through the electric motor 25 to detect the current can also be applied. Furthermore, for example, as the torque detection unit 25a, a torque detector that detects the torque of the electric motor 25 can also be applied.

[0055] Next, the transfer section 32 will be described.

[0056] like Figure 3 As shown in the figure, the transfer section 32 includes a transfer belt 50 and primary transfer rollers 52, each of which is arranged on the opposite side of the image holder 40 of each color across the transfer belt 50, and transfers the toner image formed on the image holder 40 of each color to the transfer belt 50. In addition, the transfer section 32 includes a contact / separation unit (not shown) that moves at least a part of the plurality of primary transfer rollers 52 to bring the transfer belt 50 and the image holder 40 into contact / separate.

[0057] The transfer section 32 further includes a winding roller 56 on which the transfer belt 50 is wound, a driving roller 58 on which the transfer belt 50 is wound and which transmits a rotational force to the transfer belt 50, and a positioning roller 64 for positioning a portion of the transfer belt 50 to which the toner image is transferred. The transfer section 32 also includes an applying roller 70 for applying tension to the transfer belt 50.

[0058] The transfer section 32 further includes a secondary transfer roller 54, which is disposed on the opposite side of the winding roller 56 with the transfer belt 50 interposed therebetween, and transfers the toner image transferred to the transfer belt 50 to the printing paper P. A transfer nip NT is formed between the secondary transfer roller 54 and the transfer belt 50, and transfers the toner image to the printing paper P.

[0059] [Transfer belt 50, winding roller 56, driving roller 58]

[0060] like Figure 3 As shown in FIG. 1 , the transfer belt 50 is in an endless shape, and is arranged with one end (the left end in the figure) in the width direction of the device being below the other end. The transfer belt 50 is an example of an endless member.

[0061] The winding roller 56 has an axial direction as the device depth direction, and one end portion of the transfer belt 50 in the device width direction is wound around the winding roller 56. The driving roller 58 has an axial direction as the device depth direction, and the other end portion of the transfer belt 50 in the device width direction is wound around the driving roller 58.

[0062] In this structure, the driving roller 58 to which the driving force is transmitted from a driving source (not shown) rotates, and thereby the transfer belt 50 is circulated in the direction of the arrow in the figure (clockwise direction).

[0063] [Primary transfer roller 52, secondary transfer roller 54]

[0064] like Figure 3As shown, the primary transfer roller 52 of each color is arranged on the downstream side of the driving roller 58 and the upstream side of the winding roller 56 in the winding direction of the transfer belt 50 (hereinafter referred to as the "belt winding direction"). Moreover, the primary transfer roller 52 of each color contacts the inner peripheral surface of the transfer belt 50 on the side opposite to the image holder 40 of each color across the transfer belt 50. In addition, the secondary transfer roller 54 is arranged on the side opposite to the winding roller 56 across the transfer belt 50. The primary transfer roller 52 is an example of a primary transfer component, and the secondary transfer roller 54 is an example of a secondary transfer component.

[0065] In this structure, the primary transfer roller 52 of each color transfers the toner image formed on the image holder 40 of each color to the transfer belt 50 while sandwiching the transfer belt 50 between the primary transfer roller 52 and the image holder 40 of each color. Then, the secondary transfer roller 54 transfers the toner image transferred to the transfer belt 50 by the primary transfer roller 52 to the transported printing paper P at the transfer nip portion NT. Then, a transfer voltage is applied to the secondary transfer roller 54 by constant current control performed by a constant current control unit 603 described later. In addition, although not shown in the figure, a detection device capable of detecting that the printing paper P enters the secondary transfer roller 54 is provided near the secondary transfer roller 54. The detection device is connected to the control unit 60.

[0066] [Application roller 70, positioning roller 64]

[0067] like Figure 3 As shown, the application roller 70 is arranged downstream of the primary transfer roller 52K in the belt winding direction and upstream of the secondary transfer roller 54. The application roller 70 contacts the inner peripheral surface of the transfer belt 50 and presses the transfer belt 50. Thus, tension is applied to the transfer belt 50.

[0068] like Figure 3 As shown, a pair of positioning rollers 64 are provided in the belt winding direction, and all the primary transfer rollers 52 are arranged between the pair of positioning rollers 64. Specifically, a positioning roller 64a arranged on the upstream side of all the primary transfer rollers 52 and a positioning roller 64b arranged on the downstream side of all the primary transfer rollers 52 are provided in the belt winding direction.

[0069] In addition, if Figure 6As shown, a touch panel type display unit 59 is provided in the image forming device 10. The display unit 59 includes an input unit (information input unit) 59a and a first display unit 59b. The user of the image forming device 10 can, for example, use the input unit 59a to input information related to the type of printing paper P to be printed. The types of printing 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 the user inputs information indicating plain paper using the input unit 59a, the character "plain paper" is displayed on the first display unit 59b. The second display unit (notification unit) (display unit) 59c performs notification display through the control of the display unit control unit 606 described later.

[0070] like Figure 4 As shown in FIG. 1 , as a hardware structure, the control unit 60 includes a CPU (Central Processing Unit) 60A, a ROM (Read Only Memory) 60B, a RAM (Random Access Memory) 60C, a memory 60D, a communication I / F (Interface) 60E, and an input / output I / F 60F. The CPU 60A, the ROM 60B, the RAM 60C, the memory 60D, the communication I / F 60E, and the input / output I / F 60F are connected via a bus 60Z so as to be able to communicate with each other.

[0071] The CPU 60A is a central processing unit that executes various programs and controls various parts. That is, the CPU 60A reads programs from the ROM 60B or the memory 60D and executes the programs using the RAM 60C as a work area. The CPU 60A controls various structures and performs various calculations according to the programs recorded in the ROM 60B or the memory 60D.

[0072] ROM 60B stores various programs and various data. RAM 60C temporarily stores programs or data as a work area. Memory 60D is composed of a storage device such as HDD (Hard Disk Drive) or SSD (Solid State Drive), and stores various programs and various data. Communication I / F 60E is an interface for communicating with other devices.

[0073] exist Figure 5, an example of the functional structure of the control unit 60 is shown in a block diagram. The control unit 60 includes a rotation control unit 601, a thickness estimation unit 602, a constant current control unit 603, a heat capacity estimation unit (resistance value detection unit) 604, a temperature control unit 605, and a display unit control unit 606 as a functional structure. 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 unit control unit 606 are realized by the CPU 60A reading and executing a program stored in the ROM 60B.

[0074] The rotation control unit 601 performs rotation control of the electric motor 25 and the electric motor 38 .

[0075] The thickness estimating unit 602 detects the thickness of the printing paper P based on the current value detected by the torque detecting unit 25a. Figure 7 As shown, the current value detected by the torque detection unit 25a rises sharply to a peak value convex upward when the printing paper P enters the registration roller 24, and then decreases sharply to a peak value convex downward when the printing paper P is discharged from the registration roller 24. Figure 7 In the example shown, the printing paper P enters the registration roller 24 at time t1, and is discharged from the registration roller 24 at time t2. With respect to the current detected by the torque detection unit 25a, the peak values ​​when the printing paper P enters and is discharged from the registration roller 24, and the value when the printing paper P passes through the registration roller 24 vary according to the thickness of the printing paper P. 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 varies according to the thickness of the printing paper P.

[0076] As described above, the constant current control section 603 performs constant current control for applying the transfer voltage to the secondary transfer roller 54 .

[0077] The heat capacity estimation unit 604 obtains the volume resistance of the printing paper P using the current value and voltage value of the power supplied to the secondary transfer roller 54 by constant current control. Furthermore, the heat capacity estimation unit 604 uses the heat capacity estimation map 61 (see FIG. 61 ) which defines the relationship between the volume resistance of the printing paper P and the heat capacity of the printing paper P. Figure 8 ), and the volume resistance of the printing paper P obtained, the heat capacity of the printing paper P is estimated. Figure 8 This indicates that the heat capacity and volume resistance of the printing paper P are substantially proportional. The heat capacity estimation map 61 is an example, and the relationship between volume resistance and heat capacity specified in the heat capacity estimation map 61 may be corrected while taking into account the air temperature and humidity in the housing 10a.

[0078] The temperature control unit 605 applies the thickness of the printing paper P estimated by the thickness estimating unit 602 and the heat capacity of the printing paper P estimated by the heat capacity estimating unit 604 to the Fig. 9 The heater 35a is controlled by the temperature control diagram 62 shown in the figure and recorded in the ROM 60B. The temperature control diagram 62 is a two-dimensional diagram 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 diagram 62 is defined by three thicknesses, and the heat capacity of the temperature control diagram 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. In addition, heat capacity 2 is larger 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 roller 35 (the temperature detected by the temperature sensor 37) reaches the set temperature 2.

[0079] The display unit control unit 606 controls the display unit 59. For example, the display unit control unit 606 causes the first display unit 59b to display information input by the input unit 59a.

[0080] Furthermore, when the information related to the type of printing paper P input by the input unit 59a is different from the estimated type of printing paper P, the display unit control unit 606 causes the second display unit 59c to perform notification display. Paper information about thickness and thermal capacity related to various types of printing paper is recorded in the ROM 60B. Therefore, when the information related to the thickness of the printing paper P input by the input unit 59a is included in the paper information, and when the information related to the thickness included in the paper information is different from the thickness estimated by the thickness estimating unit 602, the second display unit 59c performs notification display. In addition, when the information related to the thermal capacity of the printing paper P input by the input unit 59a is included in the paper information, and when the information related to the thermal capacity included in the paper information is different from the thermal capacity estimated by the thermal capacity estimating unit 604, the second display unit 59c performs notification display. For example, when the printing paper P inputted by the input unit 59a is a paper of a prescribed thickness and the printing paper P estimated by the thickness estimating unit 602 is thicker than the prescribed thickness, the second display unit 59c displays characters "The paper to be printed is a different type of paper from the input paper". In addition, when the heat capacity of the printing paper P inputted by the input unit 59a is a prescribed value and the heat capacity of the printing paper P estimated by the heat capacity estimating unit 604 is greater than the prescribed value, the second display unit 59c displays characters "The paper to be printed is a different type of paper from the input paper".

[0081] In the structure described above, the conveying section 14, the registration roller 24, the electric motor 25, the torque detection section 25a, the transfer section 32, the fixing device 34, the secondary transfer roller 54, the display section 59, the control section 60, the heat capacity estimation diagram 61 and the temperature control diagram 62 are components of the image forming system 65.

[0082] Next, refer to Fig.10 The flowchart of FIG. 1 is used to explain the operation of the image forming apparatus 10 having the above configuration. The CPU 60A repeatedly executes the following operation every predetermined time. Fig.10 Flowchart of the process.

[0083] First, in step S10 (hereinafter, step characters are omitted), the CPU 60A determines whether or not the printing paper P has entered the registration rollers 24 based on the information received from the torque detection unit 25 a .

[0084] When the determination result in S10 is YES, the CPU 60A proceeds to S11 and estimates the thickness of the printing paper P based on the information received from the torque detection unit 25 a .

[0085] When the process of S11 is finished, the CPU 60A proceeds to S12 and determines whether the printing paper P has entered the secondary transfer roller 54 based on the information received by the detection device.

[0086] When the determination result in S12 is YES, the CPU 60A proceeds to S13 and estimates the heat capacity of the printing paper P based on the volume resistance and heat capacity estimation map 61 of the printing paper P.

[0087] When the processing of S13 is completed, CPU60A enters S14, and controls the heater 35a by applying the information related to the thickness of the printing paper P obtained in S11 and the information related to the heat capacity of the printing paper P obtained in S13 to the temperature control diagram 62, so that the target temperature of the heating roller 35 reaches the set temperature specified in the temperature control diagram 62.

[0088] When the process of S14 is finished, the CPU 60A proceeds to S15 to determine whether the information on the printing paper P inputted by the input unit 59a is incorrect.

[0089] When a "YES" determination is made in S15, the CPU 60A proceeds to S16 to cause the second display unit 59c to perform notification display.

[0090] When the determination result in S10, S12, or S15 is "No" or when the processing in S16 is terminated, the CPU 60A temporarily terminates the processing. Fig.10 Flowchart of the process.

[0091] As described above, the image forming system 65 of the present embodiment performs temperature control of the heating roller 35 (heater 35a) based on both the thickness of the printing paper P and the heat capacity of the printing paper P. Therefore, in the image forming system 65, poor fixing of the toner image on the printing paper P can be suppressed compared with the case where the temperature of the heating roller 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, here, an image forming system of a comparative example in which the temperature of the heating roller 35 (heater 35a) is controlled based only on the thickness of the printing paper P is assumed. 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) having the same thickness as the printing paper A and a different heat capacity from the printing paper A. 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 the present embodiment, it is easier to suppress the fixing defects of the toner images on the printing paper A and the printing paper B than in the comparative example.

[0092] Furthermore, when the thickness of the printing paper P is estimated using a roller disposed downstream of the secondary transfer roller 54 and upstream of the heating roller 35 and the pressure roller 36 and an electric actuator that applies a driving force to the roller, the toner image on the printing paper P may be disturbed by the roller. In contrast, in the image forming system 65 of the present embodiment, the thickness of the printing paper P is estimated using the registration roller 24 and the electric motor 25 disposed upstream of the secondary transfer roller 54, so the toner image on the printing paper P is not disturbed by the registration roller 24.

[0093] In addition, when the thickness of the printing paper P is estimated by using the heating roller 35 and the electric motor 38, when the printing paper P fed from the storage unit 18 to the heating roller 35 and the pressure roller 36 enters the heating roller 35 and the pressure roller 36 for the first time after the main switch of the image forming apparatus 10 is turned on, the temperature of the heating roller 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 the present embodiment, the thickness of the printing paper P is estimated by using the registration roller 24 and the electric motor 25 located on the upstream side of the secondary transfer roller 54, so that even when the printing paper P fed from the storage unit 18 to the heating roller 35 and the pressure roller 36 enters the heating roller 35 and the pressure roller 36 for the first time, the temperature of the heating roller 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.

[0094] The image forming system 65 estimates the thickness of the printing paper P using the registration rollers 24 and the electric motor 25 which are already provided in the image forming apparatus. Therefore, the image forming system 65 has fewer parts than a structure including rollers dedicated to measuring the thickness of the printing paper P.

[0095] Furthermore, in the image forming system 65, the second display unit 59c performs a notification display when the information on the type of the printing paper P inputted by the input unit 59a is different from the estimated type of the printing paper P. Therefore, the image forming system 65 allows the user who inputs the information on the type of the printing paper P to the input unit 59a to recognize that the input information on the type of the printing paper P is incorrect.

[0096] The image forming apparatus 10 of the present embodiment has been described above based on the drawings. However, the image forming apparatus 10 of the present embodiment is not limited to the illustrated image forming apparatus 10 and can be appropriately modified in design without departing from the gist of the present invention.

[0097] For example, you can also press Figure 11 to Figure 13 The present invention is implemented in the manner of the first variant shown. Fig.11 As shown, a basic weight detection unit 70 is provided in the frame 10a of the first variant. The basic weight detection unit 70 is located on the downstream side of the delivery roller 20 and the upstream side of the prevention roller 22. The basic weight detection unit 70 measures the basic weight of the printing paper P conveyed by the conveying unit 14. For example, the basic weight detection unit 70 may be a device that detects the basic weight by emitting light toward the printing paper P and measuring the light transmitted through the printing paper P. In addition, the basic weight detection unit 70 may be a device that detects the basic weight by emitting ultrasonic waves toward the printing paper P and measuring the ultrasonic waves transmitted through the printing paper P. The basic weight detection unit 70 is connected to the control unit 60.

[0098] Fig.12 1 shows an example of the functional structure of the control unit 60 of the first modification example in a block diagram. The control unit 60 includes 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 as a functional structure. 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 using a map (not shown) that defines the relationship between the humidity value and the volume resistance.

[0099] When the calculated moisture content is greater than the first threshold value and the value of the basis weight acquired by the basis weight detection unit 70 is within the prescribed range, the temperature control unit 605 performs a process of lowering the temperature of the heating roller 35 to a lower value than the set temperature when the moisture content is less than the first threshold value or the basis weight is not within the prescribed range. That is, the temperature control unit 605 controls the heater 35a so that the temperature of the heating roller 35 is lower by a prescribed value than the set temperature obtained based on the temperature control diagram 62. In addition, when the printing paper P is plain paper, the value of the basis weight of the printing paper P is within the prescribed range.

[0100] The CPU 60A of the first modification repeatedly executes the Fig.13 Flowchart of the process.

[0101] First, the processing of S10 to S13 is the same as that of the embodiment.

[0102] When the process of S13 is completed, the CPU 60A proceeds to S13A to determine whether the moisture content of the printing paper P is equal to or greater than a first threshold value.

[0103] When the determination result in S13A is YES, the CPU 60A proceeds to S13B to determine whether the value of the basic weight of the printing paper P is within a prescribed range.

[0104] If it is determined to be YES in S13B, the CPU 60A proceeds to S14A to control the temperature of the heating roller 35 while executing the temperature reduction process.

[0105] On the other hand, when the determination in S13B is "NO", the CPU 60A proceeds to S14.

[0106] When the processing of S14 or S14A is completed, the CPU 60A proceeds to S15.

[0107] As described above, in the image forming system 65 of the first modified example, the lowering process is performed when the moisture content of the printing paper P is greater than the first threshold value and the value of the basic weight obtained by the basic weight detection unit 70 is within the prescribed range. Therefore, compared with the case where the temperature of the heating roller 35 is constant regardless of the basic weight and moisture content of the printing paper P, curling is less likely to occur on the printing paper P. That is, for example, when the lowering process is not performed when the moisture content of the printing paper P is greater than the first threshold value, water is excessively lost from the surface of the printing paper P that contacts the heating roller 35, and the difference in moisture between the front and back of the printing paper P becomes large, thereby making it easy for curling to occur on the printing paper P. In the first modified example, the lowering process is performed when the moisture content of the printing paper P is greater than the first threshold value and the value of the basic weight obtained by the basic weight detection unit 70 is within the prescribed range, so the difference in moisture between the front and back of the printing paper P is less likely to become large, and curling is less likely to occur on the printing paper P.

[0108] In addition, the present invention can also be Fig.14 and Fig.15 The second variant is implemented as shown. Fig.14 As shown, a temperature and humidity sensor 71 is provided in the housing 10a of the second modification. The temperature and humidity sensor 71 detects the temperature and humidity in the housing 10a. Hereinafter, the humidity detected by the temperature and humidity sensor 71 is referred to as a humidity value. The temperature and humidity sensor 71 is connected to the control unit 60.

[0109] The temperature control unit 605 of the second modification does not perform the lowering process when the humidity value is below the second threshold and the volume resistance of the printing paper P is below the third threshold. On the other hand, the temperature control unit 605 performs the lowering process when the humidity value is greater than the second threshold or the volume resistance is greater than the third threshold.

[0110] The CPU 60A of the second modification repeatedly executes the Fig.15 Flowchart of the process.

[0111] First, the processing of S10 to S13 is the same as that of the embodiment.

[0112] When the process of S13 is finished, the CPU 60A proceeds to S13C to determine whether the humidity value is equal to or less than the second threshold value and whether the volume resistance of the printing paper P is equal to or less than the third threshold value.

[0113] If the determination result in S13C is "YES", the CPU 60A proceeds to S14. On the other hand, if the determination result in S13C is "NO", the CPU 60A proceeds to S14A.

[0114] When the processing of S14 or S14A is completed, the CPU 60A proceeds to S15.

[0115] As described above, in the image forming system 65 of the second modified example, when the humidity value is below the second threshold value and the volume resistance of the printing paper P is below the third threshold value, the lowering process is not performed. That is, when the humidity value is below the second threshold value, it is estimated that the moisture content of the printing paper P is small. Therefore, it is not necessary to perform the lowering process at this time. Therefore, according to the image forming system 65 of the second modified example, compared with the case where the lowering process is performed even if the humidity value is below the second threshold value and the volume resistance of the printing paper P is below the third threshold value, it is possible to suppress the poor fixing of the colorant image on the printing paper P.

[0116] Furthermore, in the image forming system 65 of the second modification, the reduction process is performed when the humidity value is greater than the second threshold value or when the volume resistance is greater than the third threshold value. Therefore, compared with the case where the temperature of the heating roller 35 is constant regardless of the humidity value and the volume resistance, curling is less likely to occur on the printing paper P.

[0117] The image forming apparatus 10 is not limited to an intermediate transfer apparatus, and may be a color machine or a monochrome machine of direct transfer. In this case, the heat capacity of the printing paper P may be estimated using the transfer roller.

[0118] In addition, the image forming system 65 may start the temperature control of the heating roller 35 (heater 35a) based on the detection result of the torque detection unit (current value detection unit) 25a only, and then control the temperature of the heating roller 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 unit) 604. That is, the image forming system 65 may control the heater 35a based on the temperature control diagram 62 after controlling the heater 35a so that the temperature of the heating roller 35 reaches the assumed target temperature based on the detection result of the torque detection unit (current value detection unit) 25a only. According to this modification, it is easier to suppress the fixing failure of the toner image on the printing paper P than in the case where the temperature control of the heating roller 35 (heater 35a) is started after the thickness and heat capacity of the printing paper P are estimated.

[0119] The recording medium may be a medium different from the printing paper P. For example, the recording medium may be a transparent film.

[0120] (Note) (((1)))

[0122] An image forming system, characterized in that:

[0123] have:

[0124] a conveying section that conveys the recording medium using a roller;

[0125] a transfer section that applies a transfer voltage through a transfer body to transfer the toner image onto the recording medium conveyed by the conveying section;

[0126] a fixing unit that fixes the toner image on the recording medium to which the toner image is transferred using a heating roller; and

[0127] processor,

[0128] The processor controls the temperature of the heating roller based on a detection result of a current value detection unit that detects a current value of an electric actuator that rotates the roller and a detection result of a resistance value detection unit that detects a volume resistance of the recording medium when the colorant image is transferred onto the recording medium after the current value is detected by the current value detection unit. (((2)))

[0130] An image forming system according to (((1))), wherein:

[0131] The rollers of the transport portion are registration rollers. (((3)))

[0133] The image forming system according to (((1))) or (((2))), wherein:

[0134] have:

[0135] an information input unit that enables a user to input information related to the type of the recording medium; and

[0136] a notification unit capable of notifying the user,

[0137] The processor

[0138] The type of the recording medium is estimated based on the detection results of the current value detection unit and the resistance value detection unit,

[0139] When it is determined that the estimated type of the recording medium is different from the type of the recording medium indicated by the information input to the information input unit, the notification unit is caused to execute a notification operation. (((4)))

[0141] The image forming system according to (((3))), wherein:

[0142] The notification unit is a display unit capable of displaying information related to the estimated type of the recording medium. (((5)))

[0144] The image forming system according to any one of (((1))) to (((4))), wherein:

[0145] The processor

[0146] After the temperature control of the heating roller is started based only on the detection result of the current value detection unit, the temperature control of the heating roller is performed based on the detection result of the current value detection unit and the detection result of the resistance value detection unit. (((6)))

[0148] The image forming system according to any one of (((1))) to (((5))), wherein:

[0149] have:

[0150] a frame body, which accommodates the conveying unit, the transfer unit and the fixing unit;

[0151] A temperature and humidity sensor is disposed in the frame; and

[0152] a basis weight detection unit for detecting a basis weight of the recording medium,

[0153] The processor

[0154] estimating 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,

[0155] acquiring the basic weight of the recording medium from the basic weight detection section,

[0156] 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 temperature reduction process is performed to reduce the temperature of the heating roller compared to a case where the moisture content is less than the first threshold or the basis weight is not within the predetermined range. (((7)))

[0158] The image forming system according to any one of (((1))) to (((6))), wherein:

[0159] have:

[0160] a frame body that accommodates the conveying unit, the transfer unit, and the fixing unit; and

[0161] A temperature and humidity sensor is disposed in the frame.

[0162] The processor

[0163] When the humidity value detected by the temperature and humidity sensor is below the second threshold and the volume resistance of the recording medium is below the third threshold, the processing of lowering the temperature of the heating roller is not performed compared with the case where the humidity value is greater than the second threshold or the volume resistance of the recording medium is greater than the third threshold. (((8)))

[0165] An image forming system according to (((7))), wherein:

[0166] The processor

[0167] The lowering 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.

Claims

1. An image forming system, characterized in that: have: a conveying section that conveys the recording medium using a roller; a transfer section that applies a transfer voltage through a transfer body to transfer the toner image onto the recording medium conveyed by the conveying section; a fixing unit that fixes the toner image on the recording medium to which the toner image is transferred using a heating roller; as well as processor, The processor controls the temperature of the heating roller based on a detection result of a current value detection unit that detects a current value of an electric actuator that rotates the roller and a detection result of a resistance value detection unit that detects a volume resistance of the recording medium when the colorant image is transferred onto the recording medium after the current value is detected by the current value detection unit.

2. The image forming system according to claim 1, wherein: The rollers of the transport portion are registration rollers.

3. The image forming system according to claim 1 or 2, wherein: have: an information input unit that enables a user to input information related to the type of the recording medium; as well as a notification unit capable of notifying the user, The processor The type of the recording medium is estimated based on the detection results of the current value detection unit and the resistance value detection unit, When it is determined that the estimated type of the recording medium is different from the type of the recording medium indicated by the information input to the information input unit, the notification unit is caused to execute a notification operation.

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

5. The image forming system according to any one of claims 1 to 4, wherein: The processor performs temperature control of the heating roller based on the detection result of the current value detection unit and the detection result of the resistance value detection unit after starting temperature control of the heating roller based only on the detection result of the current value detection unit.

6. The image forming system according to any one of claims 1 to 5, wherein: have: a frame body, which accommodates the conveying unit, the transfer unit and the fixing unit; A temperature and humidity sensor is disposed in the frame; and a basis weight detection unit for detecting a basis weight of the recording medium, The processor estimating 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, acquiring the basic weight of the recording medium from the basic weight detection section, 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 temperature reduction process is performed to reduce the temperature of the heating roller compared to a case where the moisture content is less than the first threshold or the basis weight is not within the predetermined range.

7. The image forming system according to any one of claims 1 to 6, wherein: have: a frame body that accommodates the conveying unit, the transfer unit, and the fixing unit; and A temperature and humidity sensor is disposed in the frame. When the humidity value detected by the temperature and humidity sensor is below the second threshold and the volume resistance of the recording medium is below the third threshold, the processor does not perform processing to reduce the temperature of the heating roller compared to a case where the humidity value is greater than the second threshold or the volume resistance of the recording medium is greater than the third threshold.

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

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