JP2014088253A - Recording medium thickness detection apparatus, image formation apparatus, recording medium thickness detection method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording medium thickness detection apparatus capable of highly accurately detecting the thickness of a recording medium by a simple structure while increasing the conveying capacity of recording media.SOLUTION: A recording medium thickness detection apparatus comprises: conveyance means for holding and conveying a recording medium between a driving roller and a driven roller which rotates submissively in contact with the driving roller; position measurement means for measuring the position of the driven roller in a contacting/separating direction with respect to the driving roller and outputting the measured value; and thickness calculation means for obtaining a first reference value from the measured value when the recording medium is not conveyed by the conveyance means, and calculating the thickness of the recording medium on the basis of the difference between the measured value when the recording medium is conveyed and the first reference value. In the recording medium thickness detection apparatus, the thickness calculation means obtains the first reference value when the last number of the recording media conveyed by the conveyance means after the first reference value was obtained reaches a first predetermined number N1 (N1 is an integer of 2 or greater).

Description

  The present invention relates to a recording medium thickness detection apparatus, an image forming apparatus, a recording medium thickness detection method, and a program.

  In an image forming apparatus such as a printer or a copying machine, it is necessary to set image forming conditions appropriately according to the characteristics of various types of paper, and always output an image of a certain quality or higher regardless of the type of paper. For example, in an electrophotographic image forming apparatus, it is generally performed to appropriately change fixing conditions, transfer conditions, and the like according to the thickness of a sheet.

  The thickness of the sheet can be input and set by the user of the image forming apparatus. However, in order to prevent an operation error and reduce the burden on the user, the image forming apparatus detects the sheet thickness and determines the detected sheet thickness. It is preferable to automatically set the image forming conditions based on this.

  Here, as a method for detecting the sheet thickness, there is known a method for detecting the sheet thickness based on the displacement amount when one of the conveyance rollers of the conveyance roller pair holding and conveying the sheet is conveyed and not conveyed. It has been. However, in such a method, in order to remove the eccentric component of the conveyance roller, for example, a displacement amount equal to or greater than one rotation of the conveyance roller is measured during the conveyance and non-conveyance of the paper, and the average of the measured displacement amount is measured. It is necessary to detect the thickness of the sheet using the value. Therefore, every time an image is printed, it is necessary to transport the paper with an interval of at least one rotation of the conveyance roller in order to measure the amount of displacement of at least one rotation of the conveyance roller, which hinders improvement in printing productivity. was there.

  Therefore, the reference value used by the thickness discriminating means is obtained by averaging a plurality of detected values by different positions along the rotation direction of the transport roller between transported papers when the paper is not transported. Is calculated, and the paper thickness is detected using the reference value (see, for example, Patent Document 1).

  According to such a method, even if the interval between the sheets to be conveyed is less than one rotation of the conveyance roller, the amount of displacement corresponding to one rotation of the conveyance roller when the sheet is not conveyed is divided into a plurality of times and detected. The reference value can be calculated by averaging the values obtained. Therefore, the productivity of printing can be improved by narrowing the sheet interval, and the influence of the eccentric component of the transport roller in detecting the sheet thickness can be removed.

  However, in the method according to Patent Document 1, in order to detect the rotation position of the conveyance roller, a conveyance roller rotation position detection unit such as an encoder is necessary, which may complicate the apparatus configuration. Further, the position of the transport roller may change every time the sheet is transported, and the position of the transport roller changes while detecting the amount of displacement corresponding to one rotation of the transport roller, and the calculated reference value is used to detect the sheet thickness. Unlike the actual transport roller position at the time, it may be difficult to detect the sheet thickness with high accuracy.

  The present invention has been made in view of the above, and provides a recording medium thickness detection device capable of detecting the recording medium thickness with high accuracy and improving the conveyance capability of the recording medium. The purpose is to do.

  According to the recording medium thickness detection apparatus of one aspect of the present invention, the conveyance unit that sandwiches and conveys the recording medium between the driving roller and the driven roller that rotates following the driving roller, and the contact with the driving roller. A position measurement unit that measures the position of the driven roller in the separating direction and outputs a measurement value; and a first reference value is acquired from the measurement value when the recording medium is not conveyed in the conveying unit; Thickness calculating means for calculating the thickness of the recording medium based on the difference between the measured value during conveyance and the first reference value, and the thickness calculating means includes the first reference immediately before The first reference value is acquired when the number of the recording media conveyed by the conveying means after the acquisition of the value reaches a first predetermined number N1 (N1 is an integer of 2 or more).

  According to the embodiment of the present invention, it is possible to provide a recording medium thickness detection device that can detect the recording medium thickness with high accuracy and can improve the conveyance capability of the recording medium.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment. 1 is a diagram illustrating a functional configuration of an image forming apparatus according to an embodiment. It is a figure which illustrates schematic structure of the paper thickness detection part in embodiment. It is a figure which shows the example of an output of the position measurement sensor in embodiment. It is a figure which illustrates the change of the output of a position measurement sensor with paper conveyance. FIG. 6 is a diagram illustrating a flowchart of a printing process of the image forming apparatus according to the embodiment. It is a figure which illustrates the flowchart of the reference value acquisition determination process in embodiment. It is a figure for demonstrating the reference value acquisition determination process in embodiment. It is a figure which illustrates the flowchart of the reference value acquisition determination process at the time of starting in embodiment. It is a figure for demonstrating the reference value acquisition determination process at the time of starting in embodiment.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

<Configuration of image forming apparatus>
First, a schematic configuration of the image forming apparatus 100 according to the embodiment will be described with reference to FIG.

  The image forming apparatus 100 includes a photoconductor 10, a charging device 11, an exposure device 12, a developing device 13, an intermediate transfer belt 20, a secondary transfer roller 30, a fixing device 40, an automatic document feeder (ADF) 50, a reading device 51, and the like. Is provided. The image forming apparatus 100 includes a plurality of developing units including a photoconductor 10 that forms toner images of different colors, a charging device 11, an exposure device 12, a developing device 13, and the like, and is a recording medium stored in a paper tray 60. Is a multi-function machine that prints and outputs a color image on paper P.

  When an image is printed on the paper P in the image forming apparatus 100, first, the surface of the photoreceptor 10 on which the charging device 11 rotates is uniformly charged, and an image obtained by the reading device 51 reading a document set on the ADF 50, for example. Based on the data and the like, the exposure device 12 exposes the surface of the photoreceptor 10 to form an electrostatic latent image. Next, the developing device 13 containing a developer containing toner therein develops the electrostatic latent image on the surface of the photoreceptor 10 to form a toner image. The image forming apparatus 100 forms toner images of different colors by a plurality of developing units, and then superimposes and transfers the toner images on the rotating intermediate transfer belt 20.

  The toner image transferred to the intermediate transfer belt 20 is transferred from the paper tray 60 to the roller pairs 31, 32, 33, 34, 35, the resist at the secondary transfer portion between the intermediate transfer belt 20 and the secondary transfer roller 30. Secondary transfer is performed on the paper P conveyed by the roller 36 or the like. The sheet P on which the toner image has been transferred is further conveyed, heated and pressed by the fixing device 40, and discharged to the sheet discharge tray 70 in a state where the toner image is fixed.

  After the toner image is transferred to the intermediate transfer belt 20, the toner remaining on the surface is removed by the cleaning device 14 to prepare for the next image formation.

  The image forming apparatus 100 detects the thickness of the paper P on which an image is to be printed by the method described below, and sets the secondary transfer conditions, the fixing conditions, and the like according to the thickness, for example. Regardless, a constant quality image can always be formed on the paper P.

  Note that the image forming apparatus 100 according to the present embodiment prints an image on a recording medium by an electrophotographic method, but other image forming methods such as an ink jet method may be used. As the recording medium, for example, plain paper, OHP, envelopes, cardboards such as postcards, cloth, and the like can be used.

<Functional configuration of image forming apparatus>
FIG. 2 is a diagram illustrating a functional configuration of the image forming apparatus 100 according to the embodiment.

  As shown in FIG. 2, the image forming apparatus 100 includes a sheet thickness detection unit 101, a temperature detection unit 102, an engine control unit 110, a paper feeding unit 120, a fixing unit 130, an image forming unit 140, a controller control unit 150, an operation The display unit 160 includes a network I / F unit 170 and a recording medium I / F unit 180.

  The paper thickness detection unit 101 includes a driving roller and a driven roller as conveyance means for nipping and conveying the paper P, and a position measurement sensor for measuring the position of the driven roller. The paper thickness detecting unit 101 conveys the paper P and measures the thickness of the paper P. Obtains and outputs measurement values for calculation.

  The temperature detection unit 102 is a temperature sensor provided in the apparatus of the image forming apparatus 100, and detects and outputs an in-machine temperature around the sheet thickness detection unit 101, for example.

  The engine control unit 110 includes a thickness calculation unit 111 and a storage unit 112. The engine control unit 110 calculates the thickness of the paper P based on the measurement value output from the paper thickness detection unit 101, and feeds the image so that an image is printed under an image forming condition corresponding to the thickness of the paper P. Control unit 120, fixing unit 130, and image forming unit 140.

  The thickness calculation unit 111 acquires the measurement value output from the paper thickness detection unit 101, and calculates the thickness of the paper P based on the acquired measurement value. The thickness calculation unit 111 is a function realized by the CPU processing various programs stored in the storage unit 112, for example.

  The storage unit 112 is, for example, a ROM, RAM, HDD, or the like, and stores various programs including data used by the thickness calculation unit 111 for calculating the thickness of the paper P, data used by the programs, and the like.

  The sheet feeding unit 120 is a pair of rollers 31, 32, 33, 34, 35, a registration roller 36, and the like that feeds the sheet tray 60 and the sheet P of the image forming apparatus 100 shown in FIG. The paper P is fed and conveyed.

  The fixing unit 130 is the fixing device 40 of the image forming apparatus 100 shown in FIG. 1, and fixes the toner image on the paper P by heating and pressing the paper P conveyed between the heating roller and the pressure roller. .

  The image forming unit 140 includes the photoconductor 10, the charging device 11, the developing device 13, and the like of the image forming apparatus 100, and transfers the toner image formed on the surface of the photoconductor 10 onto the paper P.

  The controller control unit 150 includes an RTC (Real Time Clock) 151 and controls each unit of the image forming apparatus 100 and the operation display unit 160.

  The RTC 151 is a timepiece that operates while receiving power from an internal battery, for example, while the image forming apparatus 100 is powered off. The thickness calculation unit 111 of the engine control unit 110 acquires time from the RTC 151 in a process described later.

  The operation display unit 160 includes various operation keys, for example, a display such as a liquid crystal display, an LED lamp, and the like. The operation keys are used for inputting operations necessary for using functions such as copying, printing, and scanner of the image forming apparatus 100, and for specifying the type of paper P. The display also displays the contents of commands input from the operation keys and various types of information notified from the image forming apparatus 100 to the user.

  The network I / F unit 170 has a communication function connected via a network such as a LAN (Local Area Network) or a WAN (Wide Area Network) constructed by a data transmission path such as a wired and / or wireless line. This is an interface between the device and the image forming apparatus 100.

  The recording medium I / F unit 180 is an interface with the recording medium. The image forming apparatus 100 can read and / or write the recording medium 181 via the recording medium I / F unit 180. The recording medium 181 includes a flexible disk, a CD, a DVD (Digital Versatile Disk), an SD memory card, a USB memory (Universal Serial Bus memory), and the like.

<Configuration of paper thickness detector>
FIG. 3 is a diagram illustrating a schematic configuration of the sheet thickness detection unit 101 according to the embodiment.

  As shown in FIG. 3A, the sheet thickness detection unit 101 includes a conveyance roller 55 as an example of a conveyance unit and a position measurement sensor 57 as an example of a position measurement unit.

  The conveyance roller 55 includes a driving roller 55a that rotates and a driven roller 55b that rotates following contact with the driving roller 55a. The conveyance roller 55 sandwiches and conveys the paper P between the driving roller 55a and the driven roller 55b. The driven roller 55b is provided so as to be movable in a direction in which the driven roller 55b is fixed to the driving roller 55a, and is pressed against the driving roller 55a by a pressing means (not shown).

  The position measurement sensor 57 includes a wheel 57a having slits formed at regular intervals, a sensor 57b that detects the rotation angle of the wheel 57a by detecting the slit of the wheel 57a, and one end fixed to the rotation shaft of the wheel 57a. The arm 57c is provided so that the end is in contact with the rotating shaft of the driven roller 55b.

  When the paper P is conveyed between the driving roller 55a and the driven roller 55b, the driven roller 55b is displaced in a direction away from the driving roller 55a as shown in FIG. 3B, and the arm 57c of the position measuring sensor 57 is moved. Pushing up in the direction of the arrow rotates the wheel 57a.

  The position measuring sensor 57 detects the rotational position of the wheel 57a that rotates in accordance with the positional fluctuation of the driven roller 55b caused by the conveyance of the paper P in this manner, and the contact / separation direction of the driven roller 55b with respect to the driving roller 55a. A measurement value indicating the position of is output. The thickness calculation unit 111 of the image forming apparatus 100 acquires the measurement value of the sensor 57b when the paper P is transported and when it is not transported, and detects the thickness of the paper P based on the difference between the acquired measurement values. As the position measurement sensor 57, for example, an optical sensor or the like may be used. The position measurement sensor 57 is not limited to the configuration according to the present embodiment as long as the position of the driven roller 55b can be detected.

  The sheet thickness detection unit 101 is provided in any one or more of the roller pairs 31, 32, 33, 34, and 35 and the registration roller 36 of the image forming apparatus 100 shown in FIG. Further, the sheet thickness detection unit 101 may be provided at a place other than the above as long as it is a conveyance path of the sheet P in the image forming apparatus 100.

<Paper thickness calculation method>
Next, a method for calculating the thickness of the paper P in the thickness calculation unit 111 of the image forming apparatus 100 will be described.

  FIG. 4 is an output example of the position measurement sensor 57 in the image forming apparatus 100 according to the embodiment. In FIG. 4, the driving roller 55a starts driving at time t1, the paper P enters between the driving roller 55a and the driven roller 55b at time t2, and the paper P is driven to the driving roller 55a and driven roller at time t3. It is an output example of the position measurement sensor 57 when it passes between 55b.

  When the paper is transported from time t2 to time t3, the driven roller 55b moves away from the driving roller 55a, so that a larger value is output from the position measurement sensor 57 than when the paper is not transported from time t1 to time t2. Has been. In addition, after the sheet P passes between the driving roller 55a and the driven roller 55b at time t3, the driven roller 55b returns to the non-conveying position where the sheet is in contact with the driving roller 55a. The output is almost the same value from time t1 to time t2.

  The thickness calculation unit 111 acquires the reference value V1 based on the measurement value output from the position measurement sensor 57 when the sheet is not conveyed, and the measurement value V2 and the reference value V1 output from the position measurement sensor 57 when the sheet is conveyed. Based on the difference, the thickness of the paper P is calculated.

  Note that the output of the position measurement sensor 57 includes periodic fluctuations due to the influence of the eccentricity of the driven roller 55b. Therefore, in order to remove such noise, the thickness calculation unit 111 acquires a measurement value during each rotation of the driven roller 55b during the paper conveyance and the non-conveyance, for example, and calculates an average value ( It is preferable to calculate the thickness of the paper P with the reference value V1 when the paper is not transported and the measured value V2 when the paper is transported as the value indicated by the broken line in FIG.

  In addition, the roller diameter may change due to thermal expansion of the driving roller 55a and the driven roller 55b due to an increase in the internal temperature of the image forming apparatus 100, execution of continuous printing, or the like. When the roller diameters of the driving roller 55a and the driven roller 55b change in this way, as shown in FIG. 5, the output value of the position measurement sensor 57 gradually changes as the roller diameter changes (in the example of FIG. Shift). For this reason, in order to detect the thickness of the paper P with high accuracy, the thickness calculation unit 111 needs to appropriately acquire and update the reference value V1 when the paper is not conveyed.

<Print processing in image forming apparatus>
In the image forming apparatus 100 according to the present embodiment, the thickness calculation unit 111 acquires the reference value V1 used for calculating the thickness of the paper P by processing described below, and detects the thickness of the paper P with high accuracy. Yes.

(Printing process)
First, a printing process of the image forming apparatus 100 in the embodiment will be described based on a flowchart illustrated in FIG.

  As shown in FIG. 6, when an image is printed on the paper P in the image forming apparatus 100, first, the conveyance of the paper P is started in step S1. Next, in step S2, when the paper P passes through the transport roller 55 provided in the transport path of the paper P, the thickness calculation unit 111 determines the measured value at the time of paper transport from the output value of the position measurement sensor 57. Get V2.

  If it is determined in step S3 that the sheet P being conveyed is the first sheet after the acquisition of the reference value V1, the measured value V2 during sheet conveyance acquired in step S2 is conveyed in step S4. It is stored in the storage unit 112 as the reference value V2 ′ for the hour. The reference value V2 ′ at the time of paper conveyance is used for a reference value acquisition determination process described later.

  Subsequently, in step S5, the thickness calculation unit 111 is based on the difference between the reference value V1 when the sheet is not conveyed already acquired from the output value of the position measurement sensor 57 and the measurement value V2 acquired in step S2. The thickness of the paper P is calculated.

  In step S6, the engine control unit 110 sets image forming conditions and the like of the image forming unit 140 based on the thickness of the paper P calculated by the thickness calculating unit 111. In step S7, the image forming unit 140 is set. In addition, printing on the paper P is executed by the fixing unit 130 and the like.

  In step S8, a reference value determination process is performed to determine whether the thickness calculation unit 111 acquires the reference value V1 when the sheet is not transported, and the printing process ends.

(Reference value acquisition judgment processing)
FIG. 7 illustrates a flowchart of reference value acquisition determination processing for determining whether or not to acquire the reference value V1 when the sheet is not conveyed.

  In the reference value acquisition determination process, first, in step S701, the thickness calculation unit 111 acquires the print count value C1 stored in the storage unit 112. The print count value C1 is the number of sheets P printed by the image forming apparatus 100 after the thickness calculation unit 111 acquires the reference value V1 when the sheet is not conveyed, and is stored in the storage unit 112. It is a value.

  In step S702, the thickness calculation unit 111 compares the acquired print count value C1 with a preset threshold value C0. The threshold value C0 is the number of printed (conveyed) sheets from which the thickness calculation unit 111 acquires the reference value V1 when the sheet is not conveyed, and is set to 100 (sheets) in the present embodiment. If the print count value C1 is greater than or equal to the threshold value C0 in step S702, the thickness calculation unit 111 acquires and updates the reference value V1 when the sheet is not conveyed by the processing from step S709.

  Here, as the threshold value C0 is set to a smaller value, the reference value V1 when the sheet is not conveyed is acquired more frequently, and the sheet thickness can be obtained with higher accuracy. However, in order to eliminate the influence of the eccentricity of the driven roller 55b, it is necessary to make the sheet interval equal to or greater than the circumferential length of the driven roller 55b when acquiring the reference value V1. For example, when the paper interval is set to be less than or equal to the peripheral length of the driven roller 55b for the purpose of improving printing productivity, the paper interval is made larger than the peripheral length of the driven roller 55b only when the reference value V1 is acquired. There is a need. Therefore, if the acquisition interval of the reference value V1 is shortened, the number of times that the paper interval is greatly increased increases, and printing productivity is reduced. Accordingly, the value of the threshold value C0 is appropriately set to an integer of 2 or more within a range in which the printing productivity and the detection accuracy of the paper thickness are not lowered in accordance with changes in the roller diameters of the driving roller 55a and the driven roller 55b with respect to the number of printed sheets. Set.

  If the print count value C1 is less than the threshold value C0, in step S703, the thickness calculation unit 111 stores the measurement value V2 at the time of paper conveyance used for the calculation of the thickness of the paper P immediately before and the storage unit 112. The difference from the reference value V2 ′ at the time of paper conveyance is compared with a preset threshold value V0. The reference value V2 ′ at the time of paper conveyance is a measurement value V2 at the time of paper conveyance used by the thickness calculation unit 111 to detect the thickness of the first sheet after obtaining the reference value V1 at the time of paper non-conveyance. This value is stored in step S4 of the flowchart shown in FIG.

  When the difference between the measured value V2 and the reference value V2 ′ is greater than or equal to the threshold value V0 in step S704, it is considered that the roller diameters of the driving roller 55a and the driven roller 55b have changed, and thus the thickness calculation unit 111 However, the reference value V1 when the sheet is not conveyed is acquired and updated by the processing in step S709 and subsequent steps.

  If the difference between the measured value V2 and the reference value V2 ′ during paper conveyance is less than the threshold value V0, the thickness calculation unit 111 acquires the in-machine temperature Tm from the temperature detection unit 102 in step S704. Subsequently, in step S705, the difference between the in-machine temperature Tm and the reference temperature Tm ′ stored in the storage unit 112 is compared with a preset threshold value Tc.

  When the difference between the in-machine temperature Tm and the reference temperature Tm ′ is equal to or greater than the threshold Tc, it is considered that the roller diameters of the driving roller 55a and the driven roller 55b have changed with the change in the in-machine temperature. The thickness calculation unit 111 acquires and updates the reference value V1 when the sheet is not transported through the processing from step S709.

  If the difference between the in-machine temperature Tm and the reference temperature Tm ′ is less than the threshold value Tc, the thickness calculation unit 111 determines whether or not the printing process input to the image forming apparatus 100 has ended in step S706. To do. If printing has not ended, the thickness calculation unit 111 adds (+1) the print count value stored in the storage unit 112 in step S708 to end the process, and prepares for printing of the next recording medium.

  If it is determined in step S706 that printing has ended, in step S707, the print count value C1 acquired in step S701 is compared with a preset threshold value C0 ′. When the print count value C1 is equal to or greater than the threshold value C0 ′, the thickness calculation unit 111 acquires and updates the reference value V1 when the sheet is not conveyed by the processing from step S709. When the print count value C1 exceeds the threshold value C0 ′, it is possible to obtain the paper thickness with high accuracy at the next printing by acquiring and updating the reference value V1 when the paper is not conveyed. become. The threshold value C0 ′ is a value that is an integer of 1 or more and is set to a value less than the threshold value C0, and is set to 50 (sheets) in the present embodiment. Since the reference value V1 is acquired at the end of printing and the threshold value C0 is not exceeded but printing is performed for a certain number of sheets (threshold value C0 ′) or more, the reference value may be changed. Even in this case, it is preferable to acquire and update the reference value V1.

  If the print count value C1 is less than the threshold value C0 ′, then in step S708, the thickness calculation unit 111 adds (+1) the print count value stored in the storage unit 112 and ends the process.

  If the print count value C1 is greater than or equal to the threshold value C0 in step S702, if the difference between the measured value V2 and the reference value V2 ′ is greater than or equal to the threshold value V0 in step S703, the in-machine temperature Tm and the reference temperature Tm ′ are determined in step S705. Is equal to or greater than the threshold value Tc, and in step S707, if the print count value C1 is equal to or greater than the threshold value C0 ′, the thickness calculation unit 111 performs step S709 and subsequent steps when the sheet is not conveyed. A reference value V1 is acquired.

  In step S709, first, the engine control unit 110 sets the conveyance interval of the sheet P in the sheet feeding unit 120 to be equal to or greater than the peripheral length of the driven roller 55b so that the driven roller 55b rotates one rotation or more in the non-conveyance state. Next, the thickness calculation unit 111 acquires the measurement value of the position measurement sensor 57 for one rotation or more of the driven roller 55b when the sheet is not conveyed. The thickness calculation unit 111 obtains the average value of the acquired measurement values as the reference value V1 when the sheet is not conveyed, overwrites the reference value V1 stored in the storage unit 112, and updates it.

  Next, in step S710, the thickness calculation unit 111 acquires the in-machine temperature Tm and stores it in the storage unit 112 as the reference temperature Tm ′.

  In step S711, the thickness calculation unit 111 clears (sets to zero) the print count value C1 stored in the storage unit 112. In step S712, the time T1 when the reference value V1 is acquired from the RTC 151 is acquired. And stored in the storage unit 112.

  The thickness calculation unit 111 acquires the reference value V1 when the sheet is not conveyed based on the reference value acquisition determination process described above. Note that at least one of the determination based on the measured value V2 at the time of paper conveyance in step S703, the determination based on the in-machine temperature Tm in step S705, and the determination based on the print count value C1 at the end of printing in step S707, and step The acquisition determination of the reference value V1 may be performed in combination with the determination based on the print count value C1 in S702.

  FIG. 8 is a schematic diagram illustrating an output example of the position measurement sensor 57 when the reference value acquisition determination process is executed during continuous printing in the image forming apparatus 100.

  As shown in FIG. 8, every time printing is performed on the paper P, the thickness calculation unit 111 confirms the print count value C1, the measured value V2 during paper conveyance, and the in-machine temperature Tm. In this case, the conveyance interval of the paper P is increased and the reference value V1 when the paper is not conveyed is acquired. At the end of printing, if the print count value C1 is greater than or equal to the threshold value C0 ′, the thickness calculation unit 111 acquires the reference value V1.

(Reference value acquisition judgment process at startup)
In addition, the image forming apparatus 100 according to the embodiment determines whether to acquire the reference value V1 when the sheet is not conveyed at the time of activation. FIG. 9 is an example of a flowchart of the reference value acquisition determination process when the image forming apparatus 100 is started up.

  First, in step S <b> 901, it is determined whether or not the image forming apparatus 100 has been activated by turning on the main power source or returning from the energy saving mode when the image forming apparatus 100 is activated. If it is not the main power supply ON or the return from the energy saving mode, the reference value acquisition determination process at the time of start is ended, and it waits for printing or the like.

  When the main power is turned on or the apparatus is activated by returning from the energy saving mode, the thickness calculation unit 111 acquires the current time T2 from the RTC 151 in step S902. Next, in step S903, the thickness calculation unit 111 acquires the time T1 when the reference value V1 at the time of non-conveyance is acquired immediately before from the storage unit 112, and when the current time T2 and the reference value V1 are acquired. Is compared with a predetermined time T0.

  If the difference between the current time T2 and the time T1 when the reference value V1 is acquired is greater than the predetermined time T0, the driving roller 55a is first driven to rotate the driven roller 55b in step S904. Next, the thickness calculation unit 111 acquires the measurement value of the position measurement sensor 57 for one rotation or more of the driven roller 55b when the sheet is not conveyed. The thickness calculation unit 111 obtains an average value of the acquired measurement values as a reference value V1 when the sheet is not transported, and overwrites and stores the reference value V1 in the storage unit 112 for updating.

  In step S905, the in-machine temperature Tm is acquired and stored in the storage unit 112 as the reference temperature Tm ′. In step S906, the thickness calculation unit 111 clears (sets to zero) the print count value C1 stored in the storage unit 112. In step S907, the time T1 at which the reference value V1 is acquired from the RTC 151 is obtained. The data is acquired and stored in the storage unit 112, and the process ends.

  FIG. 10 is a schematic diagram illustrating an output example of the position measurement sensor 57 when the image forming apparatus 100 is activated after continuous printing.

  As shown in FIG. 10, when continuous printing is performed in the image forming apparatus 100, when the power is turned off or the mode is shifted to the energy saving mode, the driving roller whose roller diameter is increased due to thermal expansion or the like due to continuous driving. 55a and the driven roller 55b contract. Accordingly, when the image forming apparatus 100 is started after the power is turned off or the power saving mode is entered and a predetermined time has elapsed, the output value of the position measurement sensor 57 may change. For this reason, for example, if the thickness of the paper P is calculated using the reference value V1 acquired at the time of the previous continuous printing, there is a possibility that a value greatly different from the actual paper thickness may be calculated, and the calculation accuracy of the paper thickness decreases. there's a possibility that.

  Therefore, when the difference between the time T1 stored in the storage unit 112 when the previous reference value V1 is acquired and the time T2 when returning from the main power ON or the energy saving mode is equal to or greater than the predetermined time T0, The thickness calculation unit 111 acquires and updates the reference value V1 when the sheet is not conveyed. In this way, by performing the reference value acquisition determination process at the time of startup, it is possible to prevent a decrease in accuracy in calculating the paper thickness at the time of printing after turning on the main power source or returning from the energy saving mode.

  As described above, in the image forming apparatus 100 according to the present embodiment, the reference value acquisition determination process for determining the acquisition of the reference value V1 when the paper is not conveyed is performed based on the print count value set as appropriate. The sheet thickness is calculated using the reference value V1 acquired at intervals of. Since the reference value V1 at the time of non-conveyance of the paper updated at a predetermined interval is used, the paper thickness can be obtained with high accuracy. Further, since the sheet can be conveyed with the conveyance interval narrowed as much as possible except when the reference value V1 is acquired, the productivity of printing can be improved.

  In addition, when the image forming apparatus 100 is activated, the reference value V1 is acquired when the sheet is not transported, and the reference value V1 is acquired as necessary. Thus, when printing is performed after returning from the main power ON or the energy saving mode. It is possible to accurately obtain the sheet thickness.

  Up to this point, the present invention has been described based on the above-described embodiment, but the function of the image forming apparatus 100 according to the above-described embodiment is the same as the processing procedure described above for the image forming according to the above-described embodiment. This can be realized by executing the program as a program coded in a programming language suitable for the apparatus 100. Therefore, a program for realizing the image forming apparatus 100 according to the above embodiment can be stored in the computer-readable recording medium 181.

  Therefore, the program according to each of the above embodiments is stored in a recording medium 181 such as a floppy (registered trademark) disk, a CD (Compact Disc), or a DVD (Digital Versatile Disk), thereby forming an image from the recording medium 181. It can be installed on the device 100. Since the image forming apparatus 100 includes the network I / F unit 170, the program according to each of the above embodiments can be downloaded and installed via an electric communication line such as the Internet.

  As described above, the recording medium thickness detection apparatus, the image forming apparatus, the recording medium thickness detection method, and the program according to the embodiment have been described. However, the present invention is not limited to the above-described embodiments, and is within the scope of the present invention. Various modifications and improvements are possible.

55 Conveying means 55a Driving roller 55b Followed roller 57 Position measuring sensor (position measuring means)
100 Image forming apparatus 102 Temperature detection unit (temperature detection means)
111 Thickness calculation unit (thickness calculation means)
P paper (recording medium)

JP 2009-234698 A

Claims (9)

Conveying means for nipping and conveying the recording medium between the driving roller and a driven roller that rotates in contact with the driving roller;
Position measuring means for measuring the position of the driven roller in the contact / separation direction with respect to the driving roller and outputting a measurement value;
A first reference value is acquired from the measured value when the recording medium is not conveyed by the conveying means, and the recording medium is recorded based on a difference between the measured value when the recording medium is conveyed and the first reference value. A thickness calculating means for calculating the thickness;
Have
When the number of the recording media conveyed by the conveying unit after the acquisition of the first reference value immediately before has reached a first predetermined number N1 (N1 is an integer of 2 or more), the thickness calculating unit A recording medium thickness detection apparatus that acquires a first reference value. When the thickness calculation unit acquires the first reference value, the transport unit causes the driven roller to rotate one or more times in a non-transport state of the recording medium,
The thickness calculating unit acquires an average value of the measured values of one rotation or more of the driven roller in the non-conveying state of the recording medium by the conveying unit as the first reference value. The recording medium thickness detection apparatus according to 1. The thickness calculating unit obtains a second reference value from the measured value during conveyance of the recording medium, and a difference between the measured value during conveyance of the recording medium and the second reference value is equal to or greater than a predetermined value. 3. The recording medium thickness detection apparatus according to claim 1, wherein the first reference value is acquired when the recording medium has been reached. Temperature detecting means for detecting the temperature around the conveying means;
The thickness calculating unit is configured such that a difference between the temperature detected by the temperature detecting unit when the recording medium is conveyed and a reference temperature acquired when the first reference value is acquired immediately before is greater than or equal to a predetermined temperature. 4. The recording medium thickness detection apparatus according to claim 1, wherein the first reference value is acquired when the recording medium reaches the first reference value. 5. The thickness calculating means has a second predetermined number N2 (N2 is 1) after the immediately preceding acquisition of the first reference value until the conveying means stops conveying the recording medium. The recording medium thickness detection according to any one of claims 1 to 4, wherein the first reference value is acquired when the integer is equal to or greater than the predetermined number N1). apparatus. The thickness calculating means acquires the first reference value when the time from the acquisition of the immediately preceding first reference value to the return from the main power ON or energy saving mode is a predetermined time or more. The recording medium thickness detection device according to claim 1, wherein the recording medium thickness detection device is a recording medium thickness detection device.   An image forming apparatus comprising the recording medium thickness detection device according to claim 1. A conveying step for nipping and conveying the recording medium between the driving roller and a driven roller that rotates in contact with the driving roller;
A position measurement step of measuring the position of the driven roller in the contact / separation direction with respect to the drive roller and outputting a measurement value;
A first reference value is obtained from the measured value when the recording medium is not conveyed in the conveying step, and based on a difference between the measured value when the recording medium is conveyed and the first reference value. A thickness calculating step for calculating the thickness;
After the acquisition of the first reference value, when the number of the recording media conveyed by the conveying step reaches a first predetermined number N1 (N1 is an integer equal to or greater than 2), the non-recording medium in the conveying step A reference value update step of acquiring the measurement value at the time of conveyance and updating the first reference value;
A method for detecting a thickness of a recording medium, comprising:   A program that causes a computer to execute the recording medium thickness detection method according to claim 8.

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