JP2017009989A - Image forming device and image forming program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device and an image forming program capable of deriving a thickness of a recording medium with a reduced error from a posture of the recording medium compared to a case of deriving the thickness thereof from a load of drive means to drive conveying means when the recording medium is plunged into the conveying means.SOLUTION: An image forming device 10 comprises: a fixing device 24 which pinches and conveys a sheet P on which an image is formed; drive means which drives the fixing device 24; and detection means which detects a peak value of a load of the drive means when the sheet P is discharged from the fixing device 24. The image forming device derives a thickness of the sheet P from the peak value detected by the detection means.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming apparatus and an image forming program.

  In Patent Document 1, paper size detection means for detecting the paper size, conveyance position detection means for detecting the paper conveyance position, passage time measurement means after the paper passes through the conveyance position detection means, and paper An image forming apparatus including a plurality of conveying units that perform pressure conveyance is disclosed. The image forming apparatus further includes a motor torque detecting unit that detects a torque of a motor when the paper is conveyed, and a fixing unit that carries in and fixes the paper from the conveying unit. Further, in this image forming apparatus, the position of the plurality of conveying units through which the plurality of sheets pass is specified based on the information of the sheet size detecting unit, the conveying position detecting unit, and the passing time measuring unit. A paper transport position specifying unit is further provided. Further, the image forming apparatus further includes a torque decomposing unit that decomposes a plurality of conveying units into a torque for each conveying unit based on the paper conveying position specifying unit and the torque measured by the motor torque detecting unit. ing. Further, in this image forming apparatus, based on the torque of each conveying unit decomposed for each conveying unit by the torque decomposing unit and the paper size information in the direction perpendicular to the conveying direction of the paper passing through each conveying unit. The paper thickness is calculated for each conveying means. Further, in this image forming apparatus, based on the thickness calculated for each conveying unit, the paper thickness is corrected and recalculated before being carried into the fixing device.

  Further, in Patent Document 2, by driving the paper transporting means by a motor and abutting the leading end of the paper against the paper stop means, and further driving the paper transporting means by the motor after the contact, Disclosed is a paper thickness detection method for detecting a paper thickness by forming a paper loop upstream of the paper stopping means and measuring a motor driving current supplied to the motor when the loop is formed. Yes.

  In Patent Document 3, a heat fixing film that is pressed against each other, or a heat fixing roller and a pressure roller are arranged opposite to each other, and an image is formed by heat fixing while moving a recording material by driving a DC motor. An image forming apparatus including an image forming unit for performing the above is disclosed. In this image forming apparatus, the DC motor has a characteristic that the current increases due to an increase in load due to the thickness of the recording material, a detecting means for detecting the DC motor current, and a holding for holding a peak value of the detection signal. And a circuit having means for limiting temporary overvoltage of the output.

JP 2003-285484 A JP 2004-018127 A JP 2003-029555 A

  The present invention provides an image forming method capable of deriving the thickness of the recording medium by improving the signal-to-noise ratio as compared with the case where the reference of the peak value at the time of discharging the recording medium is set to the detection value in another period An object is to provide an apparatus and an image forming program.

  In order to achieve the above object, an image forming apparatus according to claim 1, a conveying unit that conveys a recording medium on which an image is formed, a driving unit that drives the conveying unit, and the recording medium includes the recording medium. A detecting means for detecting a peak value of the load of the driving means when discharged from the conveying means and a peak value of the load of the driving means when the recording medium enters the conveying means; and the detecting means Deriving means for deriving the thickness of the recording medium from the difference between the detected peak value when ejected and the peak value when entering.

  According to a second aspect of the present invention, in the first aspect of the present invention, the correction for correcting an inclination of the recording medium with respect to the transport direction upstream of the transport unit in the transport direction of the recording medium. Means are further provided.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the conveying means is a fixing device that fixes the image onto the recording medium.

  On the other hand, in order to achieve the above object, the image forming program according to claim 4 is a computer program product comprising: a drive unit configured to drive a conveyance unit that conveys a computer with a recording medium on which an image is formed; Function as a derivation unit for deriving the thickness of the recording medium from the difference between the peak value of the load when the recording medium is discharged and the peak value of the load of the driving unit when the recording medium enters the conveying unit It is for making it happen.

  According to the first and fourth aspects of the present invention, the signal-to-noise ratio is improved as compared with the case where the reference of the peak value when the recording medium is discharged is set to the detection value in another period. The thickness of the recording medium can be derived.

  According to the second aspect of the present invention, the thickness of the recording medium can be derived with higher accuracy than when the thickness of the recording medium is derived with the recording medium inclined with respect to the transport direction. .

  According to the third aspect of the present invention, the thickness of the recording medium can be derived with higher accuracy than when the thickness of the recording medium is derived from the load of the driving unit that drives the conveying unit other than the fixing device. Can do.

1 is a schematic configuration diagram illustrating a configuration of an image forming apparatus according to each embodiment. 1 is a block diagram illustrating a main configuration of an electric system of an image forming apparatus according to each embodiment. It is a graph which shows an example of the time series data of the detection result by the torque detection part which concerns on each embodiment. FIG. 6 is a schematic configuration diagram for explaining a timing at which a sheet according to each embodiment enters a fixing device. FIG. 6 is a schematic configuration diagram for explaining timing when a sheet according to each embodiment is discharged from a secondary transfer roll and an intermediate transfer belt. FIG. 6 is a schematic configuration diagram for explaining a timing at which a sheet according to each embodiment is discharged from a fixing device. FIG. 6 is a schematic configuration diagram for explaining noise at a timing when a sheet according to each embodiment enters a fixing device. It is a graph which shows an example of the relationship between the voltage value which concerns on each embodiment, and the thickness of a paper. It is a flowchart which shows the flow of a process of the thickness derivation processing program concerning each embodiment. It is the schematic which shows an example of the error notification screen which concerns on each embodiment. It is a graph which shows an example of the time series data of the detection result by the torque detection part concerning a modification.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The second, fourth, and fifth embodiments correspond to reference examples.

[First Embodiment]
First, the configuration of the image forming apparatus 10 according to the present embodiment will be described with reference to FIG. In the following, yellow is indicated by Y, magenta color is indicated by M, cyan color is indicated by C, black is indicated by K, and each component and toner image (image) need to be distinguished for each color. The description will be made with the reference numerals (Y, M, C, K) corresponding to the colors at the end. Further, in the following, when the component parts and the toner image are collectively referred to without being distinguished for each color, the description of the color at the end of the code is omitted.

(overall structure)
As shown in FIG. 1, an image processing unit that performs image processing for converting input image data into four-color gradation data of Y, M, C, and K is provided inside the apparatus main body 10 </ b> A of the image forming apparatus 10. 12 is provided.

  Further, an image forming unit 16 that forms toner images of the respective colors is disposed at a central side of the apparatus main body 10A with an interval in a direction inclined with respect to the horizontal direction. Further, a primary transfer unit 18 is provided above the image forming unit 16 for each color in the vertical direction. The toner image formed by the image forming unit 16 for each color is transferred in multiple layers.

  Further, on the side of the primary transfer unit 18 (on the left side in FIG. 1), a sheet P as an example of a recording medium transported along a transport path 60 by a supply transport unit 30 described later is multiplexed on the primary transfer unit 18. A secondary transfer roll 22 is provided for transferring the toner image transferred to the toner image.

  A fixing device 24 as an example of a conveying unit that conveys the image forming surface of the sheet P on the downstream side of the conveyance direction of the sheet P (hereinafter referred to as “sheet conveying direction”) with respect to the secondary transfer roll 22. Is provided. The fixing device 24 fixes the toner image transferred onto the paper P onto the paper P by heat and pressure.

  The fixing device 24 according to the present embodiment includes a heating belt 24A and a pressure roll 24B. The fixing device 24 is a so-called IH (Induction Heating) fixing device in which the heating belt 24A generates heat using electromagnetic induction. Further, the pressure roll 24B is driven (rotated) by a motor 112 (see FIG. 2) as an example of a driving unit, and the heating belt 24A is driven to rotate as the pressure roll 24B rotates.

  Further, on the downstream side of the fixing device 24 in the paper conveyance direction, a discharge roll 28 that discharges the paper P on which the toner image is fixed to a discharge portion 26 provided on the upper portion of the apparatus main body 10A of the image forming apparatus 10. Is provided.

  On the other hand, a supply transport unit 30 that supplies and transports the paper P is provided below and to the side of the vertical direction of the image forming unit 16. Also, above the primary transfer unit 18 in the vertical direction, there are four toner cartridges 14 that can be attached to and detached from the apparatus main body 10A from the front of the apparatus main body 10A and are filled with toner to be supplied to the developing device 38 by color. (14K to 14Y) are arranged side by side in the apparatus width direction. Each color toner cartridge 14 has a cylindrical shape extending in the depth direction of the apparatus, and is connected to each color developing device 38 via a supply pipe (not shown).

(Image forming unit)
As shown in FIG. 1, the image forming units 16 for the respective colors are all configured similarly. The image forming unit 16 includes a rotating columnar image carrier 34 and a charger 36 that charges the surface of the image carrier 34.

  Further, the image forming unit 16 includes an LED (Light Emitting Diode) head 32 that irradiates the surface of the charged image carrier 34 with exposure light. Further, the image forming unit 16 develops the electrostatic latent image formed by the exposure of the exposure light from the LED head 32 with a developer (in this embodiment, a toner charged on the negative electrode), and visualizes it as a toner image. A container 38 is provided. Further, the image forming unit 16 includes a cleaning blade (not shown) that cleans the surface of the image carrier 34.

  A developing roll 39 is disposed in the developing unit 38 so as to face the image holding member 34. The developing unit 38 uses the developing roll 39 to convert the electrostatic latent image formed on the image holding member 34 with a developer. Develop and visualize as a toner image.

  The charger 36, the LED head 32, the developing roll 39, and the cleaning blade are arranged in this order from the upstream side to the downstream side in the rotation direction of the image carrier 34 so as to face the surface of the image carrier 34. Has been.

(Transfer section (primary transfer unit, secondary transfer roll))
The primary transfer unit 18 includes an endless intermediate transfer belt 42 and a drive roll 46 around which the intermediate transfer belt 42 is wound and driven to rotate by a motor (not shown) to rotate the intermediate transfer belt 42 in the direction of arrow A. ing. In addition, the primary transfer unit 18 is wound around the intermediate transfer belt 42, is provided with a tension applying roll 48 that applies tension to the intermediate transfer belt 42, and is disposed vertically above the tension applying roll 48 and is driven by the intermediate transfer belt 42. And an auxiliary roll 50 that rotates. Further, the primary transfer unit 18 includes primary transfer rolls 52 disposed on the opposite sides of the image holders 34 of the respective colors with the intermediate transfer belt 42 interposed therebetween.

  With the above configuration, the toner images of each color Y, M, C, and K, which are sequentially formed on the image carrier 34 of the image forming unit 16 for each color, are transferred onto the intermediate transfer belt 42 by the primary transfer roll 52 for each color. Multiple transcriptions are made.

  Further, a cleaning blade 56 that contacts the surface of the intermediate transfer belt 42 and cleans the surface of the intermediate transfer belt 42 is disposed on the opposite side of the drive roll 46 with the intermediate transfer belt 42 interposed therebetween.

  Further, on the opposite side of the auxiliary roll 50 with the intermediate transfer belt 42 interposed therebetween, a secondary transfer roll 22 for transferring the toner image transferred onto the intermediate transfer belt 42 onto the conveyed paper P is provided. The secondary transfer roll 22 is grounded, the auxiliary roll 50 forms a counter electrode of the secondary transfer roll 22, and the secondary transfer voltage is applied to the auxiliary roll 50, whereby the paper P The toner image is transferred to the toner image. In this embodiment, the conveyance speed of the paper P by the secondary transfer roll 22 and the intermediate transfer belt 42 is higher than the conveyance speed of the paper P by the fixing device 24.

(Supply transport unit)
The supply conveyance unit 30 includes a sheet feeding member 62 on which a plurality of sheets P are stacked, which is disposed in the apparatus main body 10 </ b> A below the image forming unit 16 in the vertical direction.

  Further, the supply and transport unit 30 includes a paper feed roll 64 that feeds the paper P stacked on the paper feed member 62 to the transport path 60, and a separation roll 66 that separates the paper P sent by the paper feed roll 64 one by one. , And an alignment roll 68 for adjusting the conveyance timing of the paper P. And each roll is arrange | positioned in this order toward the downstream from the upstream in the paper conveyance direction.

  Further, the alignment roll 68 is connected to a motor for rotating the alignment roll 68 via a clutch mechanism (not shown). The image forming apparatus 10 keeps the clutch mechanism in an unconnected state until the paper P reaches the installation position of the alignment roll 68 and abuts the front end of the paper P in the paper conveyance direction against the alignment roll 68. Accordingly, the image forming apparatus 10 performs alignment by correcting the inclination of the paper P with respect to the paper transport direction. Then, after the alignment, the alignment mechanism 68 is rotated by bringing the clutch mechanism into a connected state, and the paper P is conveyed. The alignment roll 68 is an example of a correction unit of the present invention.

  With the above configuration, the paper P supplied from the paper supply member 62 is set at a timing determined by the rotating alignment roll 68 to the contact portion (secondary transfer position) between the intermediate transfer belt 42 and the secondary transfer roll 22. Sent out.

  The sheet P conveyed to the fixing device 24 is heated by the heating belt 24A and is pressed by the heating belt 24A and the pressure roll 24B, so that a toner image is formed on one surface (image forming surface) of the sheet P. It is fixed.

  Further, the supply / conveyance unit 30 forms the toner image on the other side without discharging the paper P, on which the toner image is fixed on one side by the fixing device 24, to the discharge unit 26 by the discharge roll 28 as it is. The double-sided conveyance device 70 used for the above is provided.

  The double-sided conveyance device 70 conveys the paper P along the double-sided conveyance path 72, and the double-sided conveyance path 72 where the paper P is conveyed by reversing the front and back of the paper P from the discharge roll 28 toward the alignment roll 68. A roll 74 and a transport roll 76 are provided.

(Other)
The image forming apparatus 10 includes a sheet detection sensor 80 provided on the upstream side in the sheet conveyance direction of the fixing device 24 along the conveyance path 60 and a sheet detection sensor 82 provided on the downstream side. The sheet detection sensors 80 and 82 according to the present embodiment are, for example, reflection type sensors including a pair of light emitting elements and light receiving elements. The paper detection sensors 80 and 82 irradiate light from the light emitting element to the detection position on the transport path 60 corresponding to the installation position. Further, the paper detection sensors 80 and 82 output a signal having a signal level corresponding to the amount of light received by the light receiving element (hereinafter referred to as “detection signal”). During the period when the paper P is transported through the detection position, the light emitted from the light emitting element is reflected by the paper P. Accordingly, the sheet detection sensors 80 and 82 output detection signals having different signal levels depending on the period during which the sheet P is conveyed at the detection position and the period during which the sheet P is not conveyed.

  As described above, in the present embodiment, the reflection type sensors are applied as the paper detection sensors 80 and 82, but the present invention is not limited to this. For example, other sensors such as a transmission type sensor may be applied. Also good.

(Image formation process)
First, gradation data of each color is sequentially output from the image processing unit 12 to the LED head 32 of each color. The exposure light emitted from the LED head 32 in accordance with the gradation data is applied to the surface of the image carrier 34 charged by the charger 36. Thereby, an electrostatic latent image is formed on the surface of the image carrier 34. The electrostatic latent image formed on the image carrier 34 is developed by each color developer 38 and visualized as a toner image of each color of Y, M, C, K.

  Further, the primary transfer rolls 52 of the primary transfer unit 18 transfer the toner images of the respective colors formed on the image carrier 34 onto the rotating intermediate transfer belt 42 in a multiple manner.

  The toner images of the respective colors transferred in multiple on the intermediate transfer belt 42 are transferred onto the sheet P conveyed along the conveying path 60 from the sheet feeding member 62 by the sheet feeding roll 64, the separation roll 66, and the alignment roll 68. Secondary transfer is performed at the secondary transfer position by the secondary transfer roll 22.

  Further, the paper P on which the toner image is transferred is conveyed to the fixing device 24. Then, the toner image is fixed on the paper P by the fixing device 24. The paper P on which the toner image is fixed is discharged to the discharge unit 26 by the discharge roll 28.

  On the other hand, when images are formed on both sides of the paper P, the paper P on which the toner image is fixed on one side (front surface) by the fixing device 24 is not directly discharged to the discharge unit 26 by the discharge roll 28. The transport direction of the paper P is switched by the reverse rotation of the discharge roll 28. The sheet P is transported along the duplex transport path 72 by transport rollers 74 and 76.

  The sheet P transported along the duplex transport path 72 is transported again to the alignment roll 68 with its front and back reversed. Then, after the toner image is transferred and fixed on the other side (back side) of the sheet P, the sheet P is discharged to the discharge unit 26 by the discharge roll 28.

  Next, with reference to FIG. 2, the configuration of the main part of the electrical system of the image forming apparatus 10 according to the present embodiment will be described.

  As shown in FIG. 2, an image forming apparatus 10 according to the present embodiment stores a CPU (Central Processing Unit) 100 that controls the overall operation of the image forming apparatus 10, and various programs, various parameters, and the like. A ROM (Read Only Memory) 102 is provided. The image forming apparatus 10 also includes a RAM (Random Access Memory) 104 that is used as a work area when the CPU 100 executes various programs, and a non-volatile storage unit 106 such as a flash memory.

  In addition, the image forming apparatus 10 includes a communication line I / F (Interface) unit 108 that transmits and receives communication data to and from an external device. In addition, the image forming apparatus 10 includes an operation display unit 110 that accepts an instruction from the user to the image forming apparatus 10 and displays various types of information regarding the operation status of the image forming apparatus 10 to the user. The operation display unit 110 includes, for example, a display button that realizes reception of an operation instruction by executing a program, a display provided with a touch panel on a display surface on which various information is displayed, and hardware keys such as a numeric keypad and a start button. including.

  Further, the image forming apparatus 10 includes a torque detection unit 114 as an example of a detection unit that detects a load (torque) of the motor 112 that rotationally drives the pressure roll 24B. The torque detector 114 according to the present embodiment is connected to the motor 112, detects the torque of the motor 112 as a current value flowing through the motor 112, converts the current value into a voltage value, and outputs the voltage value.

  Note that the configuration of the torque detection unit 114 according to the present embodiment is not particularly limited as long as the torque of the motor 112 can be detected. For example, the torque detector 114 may be configured to detect a current by measuring a voltage between shunt resistors. Further, for example, as the torque detection unit 114, a configuration in which a resistor is provided on a path through which a current flows in the motor 112 and the current is detected by measuring a voltage between the resistors may be applied. Further, for example, the torque detection unit 114 may be configured to detect a current by providing a current sensor using a Hall element on a path through which a current flows in the motor 112. Furthermore, for example, a torque detector that detects the torque of the motor 112 may be applied as the torque detector 114.

  The CPU 100, the ROM 102, the RAM 104, the storage unit 106, the communication line I / F unit 108, the operation display unit 110, the motor 112, the torque detection unit 114, and the paper detection sensors 80 and 82 are each configured as an address bus, a data bus, and They are connected to each other via a bus 116 such as a control bus.

  With the above configuration, the image forming apparatus 10 according to the present embodiment allows the CPU 100 to access the ROM 102, the RAM 104, and the storage unit 106 and to communicate with an external device via the communication line I / F unit 108. Send and receive data each. In the image forming apparatus 10, the CPU 100 acquires various instruction information via the operation display unit 110 and displays various information on the operation display unit 110. In addition, the image forming apparatus 10 performs control of the motor 112 and acquisition of the voltage value output from the torque detection unit 114 by the CPU 100, respectively.

  Further, the image forming apparatus 10 acquires detection signals output from the paper detection sensors 80 and 82 by the CPU 100, respectively. Accordingly, in the image forming apparatus 10, the front end and the rear end of the paper P in the paper transport direction pass through the detection positions of the paper detection sensors 80 and 82 according to the change in the signal level of the detection signal acquired by the CPU 100. Detect the timing. Hereinafter, the leading edge and the trailing edge of the sheet P in the sheet conveyance direction are also simply referred to as the leading edge and the trailing edge of the sheet P.

  Incidentally, the image forming apparatus 10 according to the present embodiment is equipped with a detection function for detecting the thickness of the paper P.

  The detection function will be described in detail with reference to FIGS. 3 is output from the torque detection unit 114 from the time when the leading edge of the paper P passes the detection position by the paper detection sensor 80 to the time when the trailing edge of the paper P passes the detection position by the paper detection sensor 82. The time-series data of the voltage values are shown for the three types of paper P. 4 to 6 are diagrams for explaining the time-series data of the voltage values shown in FIG. FIG. 7 is a diagram for explaining noise generated when the paper P enters the fixing device 24. In order to avoid complications, the intermediate transfer belt 42 is indicated by broken lines in FIGS.

  First, as shown in FIG. 3, the voltage value output from the torque detection unit 114 becomes a peak value P1 that protrudes upward at timing t1, then becomes larger than the previous value at timing t2, and decreases at timing t3. It becomes a convex peak value P2. In FIG. 3, the amount of change in the average value of the voltage values before and after the timing t2 is indicated by ΔA.

  Next, with reference to FIGS. 4 to 6, the principle of the time-series change of the voltage value shown in FIG. 3 will be described.

  As shown in FIG. 4, when the paper P enters the fixing device 24, a force in the direction opposite to the rotation direction of the pressure roll 24B (the force indicated by the arrow B in FIG. 4) acts on the pressure roll 24B. The torque of the motor 112 increases. Accordingly, the voltage value output by the torque detection unit 114 also increases and becomes the peak value P1. Thereafter, the paper P is conveyed while being sandwiched between the fixing devices 24, and the reverse force when the paper P enters the fixing device 24 does not work, so the voltage value decreases.

  Next, as shown in FIG. 5, when the paper P is discharged from the intermediate transfer belt 42 and the secondary transfer roll 22 upstream of the fixing device 24, a force that pushes the paper P (the force indicated by the arrow C in FIG. 5). The force working in the rotation direction of the pressure roll 24B will not work. For this reason, the torque of the motor 112 increases, and the voltage value output by the torque detector 114 also increases (ΔA shown in FIG. 3). The generation of the force for pushing out the paper P is considered to be due to the fact that the transport speed of the paper P by the secondary transfer roll 22 and the intermediate transfer belt 42 described above is faster than the transport speed of the paper P by the fixing device 24. It is done.

  Further, as shown in FIG. 6, when the paper P is discharged from the fixing device 24, the pressure roll 24B has a force in the same direction as the rotation direction of the pressure roll 24B (the force indicated by the arrow D in FIG. 5). And the torque of the motor 112 is reduced. Therefore, the voltage value output by the torque detection unit 114 is also reduced to the peak value P2.

  That is, the timing t1 shown in FIG. 3 is the timing when the paper P shown in FIG. 4 enters the fixing device 24, and the timing t2 is the time when the paper P is fed from the intermediate transfer belt 42 and the secondary transfer roll 22 shown in FIG. It is the timing when it is discharged. 3 is a timing at which the paper P shown in FIG. 6 is discharged from the fixing device 24.

  As shown in FIG. 3, the peak value P1 becomes larger as the paper P becomes thicker, and the peak value P2 becomes smaller as the paper P becomes thicker. Further, the fluctuation amount ΔA increases as the paper P becomes thicker.

  However, the fluctuation amount ΔA is a smaller value than the peak values P1 and P2, and there is a concern that when the paper P is relatively thin, it is difficult to accurately derive the thickness of the paper P.

  On the other hand, as shown in FIG. 7, when the paper P enters the fixing device 24, the curling of the paper P and the leading edge of the paper P fluttering in the vertical direction in FIG. The position of may vary. In this case, when the paper P enters the fixing device 24, the voltage value output from the torque detection unit 114 includes noise due to fluctuations in the vertical position at the front end of the paper P, that is, An error due to the posture of the paper may occur. Therefore, when the thickness of the paper P is derived from the peak value P1, the thickness of the derived paper P may be affected by the noise. In this case, the thickness of the paper P is not accurately derived.

  On the other hand, when the paper P is discharged from the fixing device 24, the paper P is sandwiched and conveyed by the fixing device 24 until it is discharged from the fixing device 24. The position of does not fluctuate. Therefore, the voltage value output from the torque detector 114 when the paper P enters the fixing device 24 does not include the influence of the noise.

  Therefore, the image forming apparatus 10 according to the present embodiment derives the thickness of the paper P from the peak value P2 of the voltage value output from the torque detector 114 when the paper P is discharged from the fixing device 24. In addition, although demonstrated using the example which applied the minimum value which is strictly the top as the peak value P2, it is not limited to this, A value larger than the minimum value near the minimum value may be applied. This is also included in the peak value P2 described in the present application. However, it is preferable to use the minimum value of the acquired measurement values within the range of the measurement rate.

  Next, a process of deriving the thickness of the paper P from the peak value P2 of the voltage value output from the torque detection unit 114 when the paper P is discharged from the fixing device 24 will be described with reference to FIG.

  As described above, the peak value P2 becomes smaller as the paper P becomes thicker. Therefore, in the present embodiment, the voltage value output from the torque detection unit 114 corresponding to the thickness of the plurality of sheets P is obtained by experiments using the actual apparatus of the image forming apparatus 10 and the sheets P having a plurality of thicknesses. Measure in advance. Further, as shown in FIG. 8, the result obtained by measuring in advance is approximated to a linear line L by the least square method or the like. Then, a linear expression corresponding to the linear straight line L expressed by the following expression (1) is derived in advance as an arithmetic expression representing the relationship between the thickness T of the paper P and the voltage value V output from the torque detection unit 114. .

  Then, the image forming apparatus 10 uses the expression (1) to calculate the thickness T of the paper P from the peak value P2 of the voltage value V output from the torque detection unit 114 when the paper P is discharged from the fixing device 24. Is derived. For example, the thickness T may be derived by using a simple peak value P2 and the thickness T of the paper P as an LUT (Look Up Table) or the like.

  Next, with reference to FIG. 9, the operation of the image forming apparatus 10 according to the present embodiment when the detection function is executed will be described. FIG. 9 is a flowchart showing the flow of the thickness derivation program executed by the CPU 100 each time an image formation instruction for the paper P is input. The thickness derivation program is preinstalled in the ROM 102. Here, in order to avoid complications, description of the process of forming an image on the paper P by the above-described image forming process is omitted. In the following description, it is assumed that the thickness of the paper P to be used is preset for the image forming apparatus 10 by the user.

  In step 150 of FIG. 9, the CPU 100 acquires the detection signal output from the paper detection sensor 80. In the next step 152, the CPU 100 determines whether or not the leading edge of the paper P has passed the detection position by the paper detection sensor 80 on the transport path 60 based on the detection signal acquired by the processing in step 150. . If the determination is negative, the CPU 100 returns to step 150. If the determination is affirmative, the CPU 100 proceeds to step 154.

  In step 154, the CPU 100 acquires the voltage value V output from the torque detection unit 114. In the next step 156, the CPU 100 acquires the detection signal output from the paper detection sensor 82. In the next step 158, the CPU 100 determines whether or not the rear end of the paper P has passed the detection position by the paper detection sensor 82 on the transport path 60 based on the detection signal acquired by the processing in step 156. To do. If the determination is negative, the CPU 100 returns to step 154. If the determination is affirmative, the CPU 100 proceeds to step 160. The time series data of the voltage value V shown in FIG. 3 is acquired by repeating the above steps 154 to 158.

  In step 160, the CPU 100 derives the thickness T of the paper P from the downwardly convex peak value P2 in the time-series data of the voltage value V using the equation (1). In the next step 162, the CPU 100 determines whether or not the thickness T of the paper P derived by the process of step 160 is outside the allowable range.

  Specifically, in this embodiment, as an example, the CPU 100 determines that the absolute value of the difference between the thickness T of the derived paper P and the thickness of the paper P preset by the user is the thickness of the thickness. When the ratio is equal to or greater than a predetermined ratio (for example, 10%), it is determined that the value is out of the allowable range. When the determination at step 162 is affirmative, the CPU 100 proceeds to the process at step 164.

  In step 164, the CPU 100 displays an error notification screen indicating that the thickness T of the paper P derived by the processing of step 160 is outside the allowable range on the display of the operation display unit 110, and then derives the actual thickness. Terminate the processing program.

  FIG. 10 shows an example of an error notification screen according to the present embodiment. As shown in FIG. 10, on the error notification screen according to the present embodiment, information indicating that the derived thickness T is outside the allowable range, information indicating the derived thickness T of the paper P, and the user Thus, information indicating the preset thickness of the paper P is displayed. Here, when ending the display of the error notification screen, the user designates an end button displayed at the bottom of the error notification screen.

  On the other hand, when the determination in step 162 is negative, the CPU 100 ends the thickness derivation processing program without executing the processing in step 164.

  As described above, in the present embodiment, the thickness of the paper P is derived based on the torque of the motor 112 that drives the pressure roll 24B of the fixing device 24. The force by which the image forming surface of the paper P is sandwiched by the fixing device 24 is stronger than that of other transport means such as the secondary transfer roll 22, the intermediate transfer belt 42, the alignment roll 68, and the separation roll 66. Therefore, according to the present embodiment, the thickness of the paper P can be derived with higher accuracy than in the case where the thickness of the paper P is derived based on the torque of the motor that drives the other conveying means.

[Second Embodiment]
Hereinafter, the second embodiment of the present invention will be described in detail. Note that the configuration of the image forming apparatus 10 according to the present embodiment is the same as that of the first embodiment (see FIGS. 1 and 2), and thus the description thereof is omitted here.

  First, the detection function according to the present embodiment will be described. The image forming apparatus 10 according to the present exemplary embodiment has a predetermined period (hereinafter, referred to as a period from when the paper P is discharged from the intermediate transfer belt 42 and the secondary transfer roll 22 to when it is discharged from the fixing device 24). The thickness T of the paper P is derived from the difference between the voltage value V output from the torque detector 114 and the peak value P2 in the “first period”. A period from the time when the sheet is discharged from the intermediate transfer belt 42 and the secondary transfer roll 22 until the sheet is discharged from the fixing device 24 corresponds to the period from the timing t2 to the timing t3 shown in FIG. The intermediate transfer belt 42 and the secondary transfer roll 22 are examples of the second transport unit of the present invention.

  Specifically, the image forming apparatus 10 derives an average value of the voltage values V in the first period. The first period is not particularly limited as long as it is within the period from timing t2 to timing t3. The first period may be, for example, a predetermined ratio (for example, 50%) of the period including the center of the period from the timing t2 to the timing t3, or the ratio period immediately after the timing t2. It may be the whole period from timing t2 to timing t3.

  Then, the image forming apparatus 10 derives the thickness T of the paper P from the difference between the derived average value and the peak value P2. As shown in FIG. 3, the difference between the average value and the peak value P2 increases as the paper P becomes thicker.

  Therefore, in the present embodiment, similarly to the first embodiment, the thickness of the plurality of sheets P is supported by an experiment using the actual apparatus of the image forming apparatus 10 and the sheets P having a plurality of thicknesses. A difference between the average value and the peak value P2 is derived in advance. Further, the previously derived difference is approximated to a linear line by the least square method or the like, and a linear expression representing the relationship between the thickness T of the paper P and the difference is derived in advance.

  Then, the image forming apparatus 10 derives the thickness T of the paper P from the difference between the average value and the peak value P2 in the first period using the linear expression.

  Next, with reference to FIG. 9, the operation of the image forming apparatus 10 according to the present embodiment when the detection function is executed will be described. The operation of the image forming apparatus 10 according to the present embodiment is different from the process of the first embodiment in the process of step 160. Therefore, the process of step 160 will be described here.

  In step 160 of FIG. 9, the CPU 100 derives an average value of the voltage values V acquired by the processing of step 154 within the first period. Then, the CPU 100 derives the thickness T of the paper P from the difference between the derived average value and the peak value P2, using the above-described linear expression obtained in advance.

[Third Embodiment]
Hereinafter, the third embodiment of the present invention will be described in detail. Note that the configuration of the image forming apparatus 10 according to the present embodiment is the same as that of the first embodiment (see FIGS. 1 and 2), and thus the description thereof is omitted here.

  First, the detection function according to the present embodiment will be described. The image forming apparatus 10 according to the present embodiment derives the thickness T of the paper P from the difference between the peak value P1 and the peak value P2.

  As shown in FIG. 3, the difference between the peak value P1 and the peak value P2 increases as the paper P becomes thicker.

  Therefore, in the present embodiment, as in each of the above-described embodiments, the peak value corresponding to the thickness of the plurality of sheets P is determined by experiments using the actual apparatus of the image forming apparatus 10 and the sheets P having a plurality of thicknesses. The difference between P1 and the peak value P2 is derived in advance. Further, the previously derived difference is approximated to a linear line by the least square method or the like, and a linear expression representing the relationship between the thickness T of the paper P and the difference is derived in advance.

  Then, the image forming apparatus 10 derives the thickness T of the paper P from the difference using the linear expression.

  Next, with reference to FIG. 9, the operation of the image forming apparatus 10 according to the present embodiment when the detection function is executed will be described. The operation of the image forming apparatus 10 according to the present embodiment is different from the above-described embodiments in the process of step 160. Therefore, the process of step 160 will be described here.

  In step 160 of FIG. 9, the CPU 100 uses the linear expression obtained in advance to calculate the upwardly convex peak value P <b> 1 in the time series data of the voltage value V acquired by the repetition processing of steps 154 to 158. The thickness T of the paper P is derived from the difference from the downwardly convex peak value P2.

[Fourth Embodiment]
Hereinafter, the fourth embodiment of the present invention will be described in detail. Note that the configuration of the image forming apparatus 10 according to the present embodiment is the same as that of the first embodiment (see FIGS. 1 and 2), and thus the description thereof is omitted here.

  First, the detection function according to the present embodiment will be described. In the image forming apparatus 10 according to the present exemplary embodiment, the sheet P is conveyed by both the intermediate transfer belt 42, the secondary transfer roll 22, and the fixing device 24. The thickness T of the paper P is derived from the difference between the voltage value V output from the torque detector 114 and the peak value P2 in the “second period”). It should be noted that the period during which both are conveyed corresponds to the period from timing t1 to timing t2 shown in FIG.

  Specifically, the image forming apparatus 10 derives an average value of the voltage values V in the second period. Note that the second period is not particularly limited as long as it is within the period from the timing t1 to the timing t2. The second period may be, for example, a predetermined ratio (for example, 50%) of the period including the center of the period from the timing t1 to the timing t2, or the period of the ratio immediately before the timing t2. Or the entire period from timing t1 to timing t2.

  Then, the image forming apparatus 10 derives the thickness T of the paper P from the difference between the derived average value and the peak value P2. As shown in FIG. 3, the difference between the average value and the peak value P2 increases as the paper P becomes thicker.

  Therefore, in the present embodiment, the average corresponding to the thickness of the plurality of sheets P is determined by experiments using the actual apparatus of the image forming apparatus 10 and the sheets P having a plurality of thicknesses, as in the above embodiments. The difference between the value and the peak value P2 is derived in advance. Further, the previously derived difference is approximated to a linear line by the least square method or the like, and a linear expression representing the relationship between the thickness T of the paper P and the difference is derived in advance.

  Then, the image forming apparatus 10 derives the thickness T of the sheet P from the difference between the average value and the peak value P2 in the second period using the linear expression.

  Next, with reference to FIG. 9, the operation of the image forming apparatus 10 according to the present embodiment when the detection function is executed will be described. The operation of the image forming apparatus 10 according to the present embodiment is different from the above-described embodiments in the process of step 160. Therefore, the process of step 160 will be described here.

  In step 160 of FIG. 9, the CPU 100 derives an average value of the voltage values V acquired by the process of step 154 within the second period. Then, the CPU 100 derives the thickness T of the paper P from the difference between the derived average value and the peak value P2, using the above-described linear expression obtained in advance.

[Fifth Embodiment]
Hereinafter, a fifth embodiment of the present invention will be described in detail. Note that the configuration of the image forming apparatus 10 according to the present embodiment is the same as that of the first embodiment (see FIGS. 1 and 2), and thus the description thereof is omitted here.

  First, the detection function according to the present embodiment will be described. The image forming apparatus 10 according to the present embodiment is output from the torque detection unit 114 in a predetermined period (hereinafter referred to as “third period”) within a period before the sheet P enters the fixing device 24. The thickness T of the paper P is derived from the difference between the measured voltage value V and the peak value P2. The period before the entry corresponds to the period before the timing t1 shown in FIG.

  Specifically, the image forming apparatus 10 derives an average value of the voltage values V in the third period. Note that the third period is not particularly limited as long as it is within the period before the timing t1. The third period is, for example, a predetermined ratio of the period including the center of the period from 0 at the left end shown in FIG. 3 (the timing at which the leading edge of the sheet P passes the detection position by the sheet detection sensor 80) to the timing t1. (For example, 50%) period, the period of the ratio immediately before timing t1, or the entire period from 0 on the left end to timing t1 shown in FIG.

  Then, the image forming apparatus 10 derives the thickness T of the paper P from the difference between the derived average value and the peak value P2. As shown in FIG. 3, the difference between the average value and the peak value P2 increases as the paper P becomes thicker.

  Therefore, in the present embodiment, the average corresponding to the thickness of the plurality of sheets P is determined by experiments using the actual apparatus of the image forming apparatus 10 and the sheets P having a plurality of thicknesses, as in the above embodiments. The difference between the value and the peak value P2 is derived in advance. Further, the previously derived difference is approximated to a linear line by the least square method or the like, and a linear expression representing the relationship between the thickness T of the paper P and the difference is derived in advance.

  Then, the image forming apparatus 10 derives the thickness T of the sheet P from the difference between the average value and the peak value P2 in the third period using the linear expression.

  Next, with reference to FIG. 9, the operation of the image forming apparatus 10 according to the present embodiment when the detection function is executed will be described. The operation of the image forming apparatus 10 according to the present embodiment is different from the above-described embodiments in the process of step 160. Therefore, the process of step 160 will be described here.

  In step 160 of FIG. 9, the CPU 100 derives an average value of the voltage values V acquired by the process of step 154 within the third period. Then, the CPU 100 derives the thickness T of the paper P from the difference between the derived average value and the peak value P2, using the above-described linear expression obtained in advance.

  Although each embodiment has been described above, the technical scope of the present invention is not limited to the scope described in each embodiment. Various modifications or improvements can be added to the above-described embodiments without departing from the gist of the invention, and embodiments to which the modifications or improvements are added are also included in the technical scope of the present invention.

  In addition, each of the above embodiments does not limit the invention according to the claims (claims), and all combinations of features described in each embodiment are indispensable for solving means of the invention. Not necessarily. Each embodiment described above includes inventions at various stages, and various inventions are extracted by combining a plurality of disclosed constituent elements. Even if several constituent requirements are deleted from all the constituent requirements shown in the respective embodiments, the configuration from which these several constituent requirements are deleted can be extracted as an invention as long as the effect is obtained.

  For example, in each of the above embodiments, the case where the fixing device 24 is applied as the conveying unit of the present invention has been described. However, the present invention is not limited to this. For example, as the conveying unit of the present invention, other conveying units that convey the image forming surface of the sheet P such as the intermediate transfer belt 42, the secondary transfer roll 22, and the alignment roll 68 may be applied. In this case as well, the thickness of the paper P is derived from the load of the driving unit that drives the transport unit, as in the above embodiments.

  Further, when a transport unit provided upstream of the transport path is applied as the transport unit of the present invention, a member downstream of the transport path may be controlled based on the derived thickness of the paper P.

  In this case, for example, the thickness of the paper P is derived from the load (torque) of the motor that drives the alignment roll 68 as in the above embodiments. And the form which changes the voltage value of the secondary transfer voltage applied to the auxiliary | assistant roll 50 according to the derived thickness of the paper P is illustrated. Furthermore, a mode in which the transport speed of the paper P in the transport path 60 downstream from the alignment roll 68 and a mode in which the amount of heat heated by the heating belt 24A is changed according to the derived thickness of the paper P are exemplified. The

  In each of the above embodiments, the sheet P is fed by the second conveying unit (the intermediate transfer belt 42 and the secondary transfer roll 22) on the upstream side of the conveying unit based on the conveying speed of the sheet P by the conveying unit (fixing device 24). Although the case where the conveyance speed is high has been described, the present invention is not limited to this. For example, the conveyance speed of the paper P by the second conveyance means may be slower than the conveyance speed of the paper P by the conveyance means.

  FIG. 11 shows a graph corresponding to FIG. 3 of each of the above embodiments in this embodiment. As in FIG. 3, the torque detection unit 114 also includes FIG. 11 from the time when the leading edge of the paper P passes the detection position by the paper detection sensor 80 to the time when the rear edge of the paper P passes the detection position by the paper detection sensor 82. 2 shows an example of time-series data of voltage values output from. Further, timings t1, t2, and t3 in FIG. 11 correspond to timings t1, t2, and t3 in FIG. Also in this embodiment, the thickness of the paper P is derived using the peak value P2 as in the above embodiments.

  Further, in each of the above embodiments, the case where the thickness derivation processing program is preinstalled in the ROM 102 has been described, but the present invention is not limited to this. For example, the thickness derivation processing program may be provided by being stored in a storage medium such as a CD-ROM (Compact Disk Read Only Memory) or provided via a network.

  Further, although cases have been described with the above embodiments where the thickness derivation process is implemented by a software configuration using a computer by executing a program, the present invention is not limited to this. For example, the thickness derivation process may be realized by a hardware configuration or a combination of a hardware configuration and a software configuration.

  In addition, the configuration (see FIGS. 1 and 2) of the image forming apparatus 10 described in the above embodiments is merely an example, and unnecessary portions may be deleted or new ones may be used without departing from the gist of the present invention. Needless to say, you can add parts.

  Further, the flow of the thickness derivation processing program described in each of the above embodiments (see FIG. 9) is also an example, and unnecessary steps can be deleted or new steps can be made without departing from the gist of the present invention. Needless to say, the processing order may be changed.

  Furthermore, the configuration of the error notification screen (see FIG. 10) shown in each of the above embodiments is also an example. Some information may be deleted or new information may be deleted without departing from the gist of the present invention. Needless to say, it is possible to add or change the display position.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 22 Secondary transfer roll 24 Fixing apparatus 24A Heating belt 24B Pressure roll 42 Intermediate transfer belt 60 Conveyance path 68 Positioning roll 100 CPU
112 Motor 114 Torque detection part P Paper

In order to achieve the above object, an image forming apparatus according to claim 1 includes a conveying unit that conveys a recording medium on which an image is formed, a driving unit that drives the conveying unit, and a rear of the recording medium . Detecting means for detecting a peak value of the load of the driving means when the end is discharged from the conveying means and a peak value of the load of the driving means when the leading end of the recording medium enters the conveying means; Derivation means for deriving the thickness of the recording medium from a difference between the peak value at the time of ejection detected by the detection means and the peak value at the time of entry.

On the other hand, in order to achieve the above object, the image forming program according to claim 4 is configured such that the rear end of the recording medium is a driving unit that drives a conveying unit that conveys the computer with the recording medium on which the image is formed interposed therebetween. The thickness of the recording medium is derived from the difference between the peak value of the load when the recording medium is discharged from the conveying means and the peak value of the load of the driving means when the leading edge of the recording medium enters the conveying means. It is for functioning as a derivation means.

Claims (4)

Conveying means for conveying the recording medium on which an image is formed;
Driving means for driving the conveying means;
Detecting means for detecting a peak value of the load of the driving means when the recording medium is discharged from the conveying means and a peak value of the load of the driving means when the recording medium enters the conveying means; ,
Derivation means for deriving the thickness of the recording medium from the difference between the peak value at the time of ejection detected by the detection means and the peak value at the time of entry;
An image forming apparatus. The image forming apparatus according to claim 1, further comprising a correction unit that corrects an inclination of the recording medium with respect to the conveyance direction on an upstream side of the conveyance unit with respect to the conveyance direction of the recording medium. The image forming apparatus according to claim 1, wherein the transport unit is a fixing device that fixes the image to the recording medium.   The driving means for driving the conveying means for conveying the computer with the recording medium on which the image is formed sandwiched between the peak value of the load when the recording medium is discharged from the conveying means, and the recording medium to the conveying means An image forming program for functioning as a deriving unit for deriving the thickness of the recording medium from a difference from a peak load value of the driving unit when entering.