JP2006201480A - Roller volume resistance value estimation method, program, recording medium, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and exactly estimate the volume resistivity value of a roller. <P>SOLUTION: A roller diameter, a roller length, a shaft diameter, an indentation, and an applied voltage are inputted (S1) and the total amount of the current flowing from the shaft by each of various values of electric conductivity (inverse numbers of volume resistivity value ρ) of the roller is calculated by an electric field analysis program according to the inputted parameter. A map indicating the corresponding relation between the calculated value of the effective resistance and the volume resistivity value ρ is then generated (S3). The effective resistance of the actual roller actually measured by separate processing is inputted (S5) and the volume resistivity value ρ of the roller is calculated according to the actually measured value of the roller (S7). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a roller volume resistance value estimation method for estimating a volume resistance value of a roller having a conductive rotating shaft, and a program, a recording medium, and an image forming apparatus to which the roller volume resistance value estimation method is applied. .

  In an electrophotographic image forming apparatus, a charging roller that charges a photosensitive member prior to the formation of an electrostatic latent image on the photosensitive member, and a developing roller that attaches a developer to the electrostatic latent image formed on the photosensitive member. Various rollers are used, such as a transfer roller for transferring the developer attached to the photosensitive member to a recording medium such as recording paper, and a cleaning roller for removing the developer remaining on the photosensitive member after transfer. In addition, the volume resistance value of these rollers is a very important parameter in controlling charging and developer behavior. Further, the volume resistance value of the roller is an indispensable parameter even when each development of charging, development, and transfer is simulated on a personal computer.

  However, in order to accurately measure the volume resistance value of the roller, it has been necessary to cut out the members constituting the roller into a special shape and measure using a special measuring instrument. The volume resistance value of the rollers varies among rollers manufactured through the same manufacturing process, and it is difficult to perform the above measurement for each roller of each image forming apparatus.

Therefore, for example, for the transfer roller, one sheet of recording paper is run before copying by the image forming apparatus, and the resistance value of the transfer roller is estimated based on the voltage drop of the current flowing through the transfer roller at that time. A method has been proposed (see, for example, Patent Document 1).
JP-A-6-161295

  However, in this case, it is necessary to provide a large-scale detection device for each of the image forming apparatuses, and recording paper is wasted, which is not practical. Also, in fields other than the image forming apparatus, the volume resistance value of the roller may be an important parameter, but a method for easily and accurately estimating the volume resistance value of the roller has not been proposed. Therefore, the present invention has been made for the purpose of easily and accurately estimating the volume resistance value of the roller.

  The present invention made in order to achieve the above object is a method for estimating a volume resistance value of a roller having a conductive rotation shaft, which is based on the input volume resistance value. Current calculation processing for calculating the current value or voltage drop of the current flowing through the roller having the volume resistance value from the rotating shaft to the outer periphery through the roller in the actual roller. The volume resistance value of the actual roller in the current calculation process in which the current measurement process for actually measuring the value or voltage drop, and the current calculation process in which the calculated value by the current calculation process and the actual measurement value by the current measurement process match or approximate And a resistance value estimation process for estimating the value as a value.

  In the present invention configured as described above, the current value or voltage drop of the current flowing from the rotating shaft to the outer peripheral portion through the roller having the volume resistance value is calculated based on the input volume resistance value by the current calculation process. calculate. As this current calculation process, for example, a well-known electric field analysis program may be used as it is.

  In the current measurement process, the current value or voltage drop of the current flowing from the rotating shaft to the outer peripheral portion of the actual roller through the roller is measured. In the resistance value estimation process, the volume resistance value in the current calculation process in which the calculated value in the current calculation process and the actual measurement value in the current actual measurement process match or approximate is estimated as the actual volume resistance value of the roller.

  For this reason, in this invention, the volume resistance value of a roller can be estimated easily. Moreover, in the present invention, the volume resistance value in the current calculation process is estimated such that the calculated value by the current calculation process and the actual measurement value match or approximate, and this is used as the volume resistance value of the roller. The resistance value can be accurately estimated.

  In the present invention, in the current measurement process, the roller flows between the rotating shaft of the roller and the conductive member in a state where the roller is pressed against the conductive member so as to have a predetermined pushing amount or nip width. The current value or voltage drop of the current may be measured, and the current value or voltage drop in the same state may be calculated in the current calculation process. In this case, the measurement operation of the current value or voltage drop in the current measurement process only needs to be performed while pressing the roller against the conductive member, which makes the measurement operation easier and further increases the volume resistance value of the roller. The further effect that it can be estimated easily arises.

  In this case, in the current calculation process, the calculation may be performed on the assumption that the roller deformed to have the indentation amount or the nip width is an object having a uniform volume resistance value. In this case, the current calculation process is further simplified, and a further effect that the processing speed can be improved occurs.

  In the current calculation process, various known programs can be used as described above, but the current value or voltage drop may be calculated by a finite element method. Furthermore, although the volume resistance value estimation method of the present invention can be applied to various rollers, the roller may be any of a transfer roller, a developing roller, a cleaning roller, and a charging roller.

  Next, a program according to the present invention is a program for causing a computer to execute the current calculation process and the resistance value estimation process described above. For this reason, if the program of this invention is made to run a computer and the said current measurement process is performed, the volume resistance value estimation method of the roller of any one of said invention can be implemented easily.

  The recording medium of the present invention is characterized in that the program of the present invention is recorded so as to be readable by a computer. For this reason, if the program recorded on the recording medium of the present invention is executed by a computer and further the current measurement process is performed, the volume resistance value estimation method for a roller of any one of the above inventions can be easily implemented.

  Furthermore, an image forming apparatus of the present invention is an image forming apparatus provided with at least one of a transfer roller, a developing roller, a cleaning roller, and a charging roller, and is attached to the roller, and the above-described roller is the above Instruction means for instructing the volume resistance value estimated by the volume resistance value estimation method of any of the rollers, reading means for reading the volume resistance value indicated by the instruction means, and volume resistance value read by the reading means And a control means for controlling the voltage applied to the roller.

  In the image forming apparatus of the present invention configured as described above, the instruction unit attached to the roller instructs the volume resistance value estimated by any one of the above-described roller volume resistance value estimation methods. The reading means reads the volume resistance value indicated by the indicating means, and the control means controls the voltage applied to the roller based on the volume resistance value read by the reading means. Therefore, in the image forming apparatus of the present invention, the voltage applied to the roller can be controlled to a value corresponding to the actual volume resistance value of the roller, and image formation can be performed extremely well.

  In the image forming apparatus of the present invention, the instruction unit may be an IC tag, and the reading unit may be an IC tag reader. In this case, the reading unit can accurately read the volume resistance value without contact with the roller, and can perform image formation more satisfactorily.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a configuration of a laser printer 1 as an image forming apparatus to which the present invention is applied. As shown in FIG. 1, the laser printer 1 includes a feeder unit 20 that supplies paper P as a recording medium to the bottom of a main body case 2. The feeder unit 20 stacks and holds the sheets P, the sheet feeding roller 23 that supplies the stacked sheets P, and urges the sheet pressing plate 22 toward the sheet feeding roller 23. The uppermost sheet P, which is provided with a compression spring 22a and is laminated and held on the sheet pressing plate 22, is supplied at a predetermined timing.

  A pair of registration rollers 24 a and 24 b are rotatably provided on the downstream side of the paper feed roller 23 in the paper conveyance direction, and the paper P is conveyed to a transfer position formed by the photosensitive drum 25 and the transfer roller 32 at a predetermined timing. To do.

  The photosensitive drum 25 as an electrostatic latent image carrier is made of a positively chargeable material, for example, an organic photoreceptor whose main component is a positively chargeable polycarbonate. In the present embodiment, the photosensitive drum 25 is configured by forming a photoconductive layer having a predetermined thickness (for example, about 20 μm) in which a photoconductive resin is dispersed in polycarbonate on the outer periphery of a cylindrical cylindrical sleeve made of aluminum. did. A charger 26 is disposed opposite the photosensitive drum 25, and the laser beam L from the laser scanner unit 27 is irradiated to the downstream side of the photosensitive drum 25 in the rotation direction.

  The charger 26 is a positively charged scorotron type charger that generates corona discharge from a charging wire made of tungsten or the like, for example, and positively charges the surface of the photosensitive drum 25. The laser scanner unit 27 includes a polygon mirror (pentahedral mirror) 28 that is driven to rotate while reflecting a laser beam L generated by a laser generator (not shown), a pair of lenses 30a and 30b, and a pair of mirrors 31a and 31a. 31b, and scans and exposes the surface of the photosensitive drum 25 with a laser beam L according to an image to be formed. In this manner, when an electrostatic latent image is formed on the photosensitive drum 25 by the cooperation of the charger 26 and the laser scanner unit 27, the electrostatic latent image is used as a developer supplied from the developing device cartridge 50. The toner T is developed as follows.

  The developing device cartridge 50 includes a toner storage chamber 53 that stores toner T as a positively chargeable nonmagnetic one-component developer, and an agitator 54 that stirs the toner T is provided in the toner storage chamber 53. Yes. A developing chamber 55 for performing development is formed on the side adjacent to the toner storage chamber 53 (on the photosensitive drum 25 side). In the developing chamber 55, a supply roller 56 and a developing roller 57 are rotatably provided. The toner T conveyed from the toner storage chamber 53 to the surface of the developing roller 57 through the supply roller 56 is regulated by the layer thickness regulating blade 59 while being regulated to a predetermined layer thickness, and then conveyed to the surface of the photosensitive drum 25. It is used for development.

  The toner T is transferred to the paper P conveyed to the transfer position between the photosensitive drum 25 and the transfer roller 32, whereby an image is formed on the paper P. As will be described later, a predetermined voltage is applied to the transfer roller 32, and the toner T is transferred to the paper P by electrostatic attraction acting on the voltage.

  The paper P on which the image is formed in this manner is sandwiched between the heating roller 33 and the pressing roller 34 and the image by the toner T is fixed, and then a pair of transport rollers 35a and 35b and a pair of paper discharge rollers 36a, The paper is transported by 36 b and discharged to a paper discharge tray 37 provided on the upper surface of the main body case 2.

  As described above, in the transfer process of the laser printer 1, since the toner T is transferred to the paper P by the electrostatic attraction acting on the toner T from the transfer roller 32, the voltage applied to the transfer roller 32 is appropriately controlled. The transfer conditions, such as, are very important. That is, if the electrostatic attraction is too strong, the toner T may adhere to the non-image portion of the paper P, and if the electrostatic attraction is too weak, the image may be faded.

  Therefore, in the present embodiment, the volume resistance value ρ of the transfer roller 32 that actually exists and whose volume resistance value ρ is unknown is estimated as follows, and the transfer roller 32 is based on the estimated volume resistance value ρ. The applied voltage is controlled. Further, in order to obtain an ideal transfer condition, even when a simulation is performed using a personal computer while changing the applied voltage, transfer roller diameter, nip pressure (nip width), etc., the deposition resistance value ρ estimated as follows: Can be easily simulated. Next, a method for estimating the volume resistance value of the transfer roller 32 that is closely related to the main part of the present invention will be described.

  FIG. 2 is an explanatory diagram showing current measurement processing for actually measuring the current value of the current flowing through the transfer roller 32. As shown in FIG. 2, the transfer roller 32 is configured by providing a roller body 32b made of conductive rubber or conductive sponge around a conductive metal shaft 32a (corresponding to a rotating shaft). . In this current measurement process, the roller main body 32b is placed on a metal plate 60 as a conductive member, and a load F is applied to the shaft 32a protruding from both ends of the roller main body 32b so that the roller main body 32b has a predetermined pushing amount. To deform.

  A DC power supply 61 and an ammeter 62 are connected in advance between the metal plate 60 and the shaft 32a, and the current value at the time of deformation is measured by this circuit. The resistance value of the shaft 32a, the metal plate 60, and the circuit from the metal plate 60 to the shaft 32a via the DC power supply 61 and the ammeter 62 is extremely smaller than the resistance value of the roller body 32b, and can be regarded as zero. it can. Therefore, by dividing the voltage applied by the DC power supply 61 by the actually measured current value, the resistance (hereinafter referred to as effective resistance) from the shaft 32a to the nip portion of the roller main body 32b and the metal plate 60 can be calculated. it can.

  Next, a process for estimating the volume resistance value ρ of the roller body 32b using the actually measured effective resistance will be described. Note that programs for executing the following processes are stored in a hard disk device (HDD) 71d of the personal computer 70 shown in FIG. The personal computer 70 has a general configuration in which a display 72, a keyboard 73, a mouse 74, and the like are connected to a main body 71 having a CPU 71a, a ROM 71b, and a RAM 71c in addition to the hard disk device 71d.

  FIG. 4 is a flowchart showing processing executed by the personal computer 70. When the process is started, first in S1 (S represents a step: the same applies hereinafter), the diameter of the roller body 32b and the roller diameter and the roller length as the axial length based on the operation state of the keyboard 73 and the like, The diameter (shaft diameter) of the shaft 32a, the aforementioned pushing amount, and the applied voltage are input.

  In subsequent S3, based on the parameters input in S1, the total amount of current flowing from the shaft 32a is calculated for each of various electrical conductivities (reciprocal of the volume resistance value ρ) of the roller body 32b, and the effective resistance and volume resistance value are calculated. A map representing the correspondence relationship with ρ is created. Details of this processing will be described with reference to FIGS.

  First, in the calculation of the total current amount, the calculation of current by the electric field analysis program “JMAG” (registered trademark: Japan Research Institute, Ltd.) based on the finite element method can be applied. For example, under the conditions of roller diameter: 15.2 mm, roller length: 231 mm, shaft diameter 6 mm, push-in amount 1 mm, electrical conductivity: 1e-8, applied voltage 1 kV, boundary conditions of nip node 0 V and shaft node 1 kV When the calculation is performed, the current vector and the potential distribution can be calculated as shown in FIG. In the model of FIG. 5, it is assumed that the roller body 32b deformed as described above is an object having a uniform volume resistance value ρ, and is further symmetrical with respect to a plane that passes through the center of the shaft 32a and is perpendicular to the nip surface. Assuming that there is a half model of the roller body 32b.

  Since the total current calculated by the above model was 2.633 μA, the total amount of current flowing from the shaft 32a under the above conditions is 2.633 μA × 2. Then, the calculated value of effective resistance is obtained by dividing 1 kV of the applied voltage by this value. By performing the same calculation with respect to various electric conductivities, as shown in FIG. 6, a map representing the correspondence relationship between the calculated effective resistance value (effectiveR) and the volume resistance value ρ is obtained.

  In FIG. 6, for convenience of explanation, a map is created for a plurality of push-in amounts (0.2 mm, 0.4 mm, 0.6 mm, and 0.8 mm). You only need to create a map for.

  Returning to FIG. 4, in the subsequent S5, the effective resistance measured in the above-described current measurement process is input based on the operation state of the keyboard 73 and the like. In the subsequent S7, the volume resistance value ρ of the roller body 32b is calculated based on the map created in S3 and the actual resistance value input in S5. That is, the volume resistance value ρ corresponding to the measured value of effective resistance and the push-in amount when the measured value is measured is read from the map, and the value is set as the volume resistance value ρ of the roller body 32b.

  As described above, in this embodiment, the volume resistance value ρ that the calculated value of the effective resistance by the process of S3 matches or approximates the actually measured value is estimated as the volume resistance value ρ of the roller body 32b. Therefore, the volume resistance value ρ can be estimated easily and accurately before the transfer roller 32 is attached to the apparatus. Moreover, the current measurement process is easy because the measurement can be performed with the roller main body 32b pressed against the metal plate 60. In S3, since the deformed roller body 32b is assumed to be an object having a uniform volume resistance value ρ, the processing is simplified and the processing speed can be improved.

  In the above processing, the roller main body 32b is deformed so as to have a specific pushing amount. However, since the pushing amount and the nip width have a close correspondence, the roller main body 32b has a specific nip width. The processing of S3 and the like may be performed based on the nip width. Further, instead of applying a constant voltage between the shaft 32a and the metal plate 60, the effective resistance may be measured by applying a constant current and measuring a voltage drop at that time. In this case, a model in which a constant current is applied is also used in the process of S3.

  Furthermore, in the above embodiment, the volume resistance value ρ of the roller body 32b is extremely larger than the volume resistance value of the shaft 32a, and the volume resistance value ρ of the roller body 32b is ignored. If it is smaller, it is desirable to create the map by inputting the volume resistance value of the shaft 32a in S1.

  Next, in the present embodiment, the volume resistance value ρ calculated as described above is written in the IC tag 32c and attached to one end of the shaft 32a as shown in FIG. Based on the volume resistance value ρ written in the IC tag 32c, the laser printer 1 performs the following processing. FIG. 7 is a block diagram showing the configuration of the control system of the laser printer 1.

  As shown in FIG. 7, the control circuit 80 is configured as a microcomputer including a CPU 81, a ROM 82, and a RAM 83. Further, the control circuit 80 includes an IC tag reader 91 that reads information written on the IC tag 32c and is disposed at the mounting position of the shaft 32a, and a transfer voltage control unit 92 that controls a transfer voltage applied to the transfer roller 32. Etc. are connected. In addition, the control circuit 80 is connected to various sensors and actuators including a main motor 93 that drives each part including the transfer roller 32 and the paper feed roller 23, but is directly related to the present invention. Since there is no, description of those structures is abbreviate | omitted.

  FIG. 8 is a flowchart showing an applied voltage control process executed by the control circuit 80. As shown in FIG. 8, in this process, first, in S11, the volume resistance value ρ of the roller body 32b written on the IC tag 32c is read via the IC tag reader 91. In subsequent S13, the voltage applied to the transfer roller 32 is set in accordance with the read volume resistance value ρ, and the process ends. The applied voltage set in this way is applied to the transfer roller 32 via the transfer voltage controller 92 at a predetermined timing by another routine (not shown).

  Therefore, in the laser printer 1, the voltage applied to the transfer roller 32 can be controlled to a value corresponding to the actual volume resistance value ρ of the transfer roller 32. Since the volume resistance value ρ is known, a sensor for measuring the paper thickness of the paper P is provided near the registration rollers 24a and 24b of the laser printer 1, and the voltage applied to the transfer roller 32 is used as the output of the sensor. If the value is controlled in accordance with the paper thickness based on this, ideal transfer according to the paper thickness of the paper P can be realized. Therefore, in the laser printer 1, it is possible to prevent the toner T from adhering to the non-image portion of the paper P and the image from fading and to form an image very well.

  The current measurement process and the mounting of the IC tag 32c may be performed manually, or may be performed automatically by being integrated with a work robot or a production line. When performing such automation, the process from the current measurement process to the estimation of the volume resistance value ρ and the mounting of the IC tag 32c can also be automated as a series of processes by a computer.

  In the above embodiment, the process of S3 is the current calculation process, the process of S7 is the resistance estimation process, the hard disk device 71d is the recording medium, the IC tag 32c is the instruction unit, and the IC tag reader 91 is the reading unit. The control circuit 80 corresponds to control means.

  Furthermore, the present invention is not limited to the above embodiment, and can be implemented in various forms without departing from the gist of the present invention. For example, the roller volume resistance value estimation method of the present invention can be applied to other rollers such as the developing roller 57, and can also be applied to rollers used in fields other than the image forming apparatus.

  In the above embodiment, the actual volume resistance value ρ is estimated using a map representing the correspondence relationship between the effective resistance and the volume resistance value ρ. Various forms are possible.

  For example, an appropriate value is set as the volume resistance value ρ and the calculated value of the effective resistance calculated by the finite element method or the like is Rc, the actually measured value of the effective resistance measured by the above method is Rm, and the coefficient set appropriately is α In this case, the value of ρ is updated by the equation ρ = ρ + α (Rm−Rc), Rc is recalculated based on the ρ, and the calculation may be repeated until Rm−Rc becomes sufficiently small. In this case, the finally obtained value of ρ can be regarded as the actual volume resistance value ρ.

  Furthermore, programs for causing a personal computer, a microcomputer, etc. to execute the various processes described above are recorded on various recording media such as elements such as ROM, flexible disks, compact disks, and web servers on the Internet in addition to hard disk devices. It goes without saying that you can do it.

1 is a cross-sectional view schematically illustrating a configuration of a laser printer to which the present invention is applied. It is explanatory drawing showing the current measurement process with respect to the transfer roller of the laser printer. It is explanatory drawing showing the structure of the personal computer which performs the electric energy calculation process and resistance value estimation process with respect to the transfer roller. It is a flowchart showing the process which the personal computer performs. It is explanatory drawing which illustrates the electric current vector and electric potential distribution obtained by the process. It is explanatory drawing which illustrates the map obtained by the process. It is a block diagram showing the structure of the control system of the said laser printer. It is a flowchart showing the applied voltage control process performed with the control system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser printer 25 ... Photosensitive drum 26 ... Charger 27 ... Laser scanner unit 32 ... Transfer roller 32a ... Shaft 32b ... Roller main body 32c ... IC tag 50 ... Developer cartridge 57 ... Developing roller 60 ... Metal plate 61 ... DC power supply 62 ... Ammeter 70 ... Personal computer 71 ... Main body 71d ... Hard disk device 80 ... Control circuit 91 ... IC tag reader 92 ... Transfer voltage controller T ... Toner

Claims (9)

A volume resistance value estimation method for a roller that estimates a volume resistance value of a roller having a conductive rotation shaft,
Based on the input volume resistance value, a current calculation process for calculating the current value or voltage drop of the current flowing from the rotating shaft to the outer peripheral portion via the roller having the volume resistance value;
Current measurement processing for actually measuring the current value or voltage drop of the current flowing from the rotating shaft to the outer peripheral portion through the roller in the actual roller;
A resistance value estimation process for estimating the volume resistance value in the current calculation process in which the calculated value by the current calculation process and the actual measurement value by the current actual measurement process match or approximate, as the volume resistance value of the actual roller;
A method for estimating a volume resistance value of a roller. In the current measurement process, the current value or voltage of the current flowing between the rotating shaft of the roller and the conductive member in a state where the roller is pressed against the conductive member so as to have a predetermined push amount or nip width. Measure the descent,
2. The method for estimating a volume resistance value of a roller according to claim 1, wherein the current value or voltage drop in the same state is also calculated in the current calculation process.   3. The roller volume according to claim 2, wherein in the current calculation process, the calculation is performed on the assumption that the roller deformed to have the indentation amount or the nip width is an object having a uniform volume resistance value. Resistance value estimation method.   The roller current resistance estimation method according to any one of claims 1 to 3, wherein in the current calculation process, the current value or the voltage drop is calculated by a finite element method.   5. The roller volume resistance value estimating method according to claim 1, wherein the roller is any one of a transfer roller, a developing roller, a cleaning roller, and a charging roller.   The program for making a computer perform the said electric current calculation process in any one of Claims 1-5, and the said resistance value estimation process.   7. A recording medium on which the program according to claim 6 is recorded so as to be readable by a computer. An image forming apparatus comprising at least one of a transfer roller, a developing roller, a cleaning roller, and a charging roller,
Instructing means attached to the roller for indicating the volume resistance value estimated by the volume resistance value estimation method of the roller according to any one of claims 1 to 5 to the roller,
Reading means for reading the volume resistance value indicated by the indicating means;
Control means for controlling the voltage applied to the roller based on the volume resistance value read by the reading means;
An image forming apparatus comprising: The instruction means is an IC tag,
9. The image forming apparatus according to claim 8, wherein the reading unit is an IC tag reader.