JP2015230476A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of, when predicting humidity in a machine, and correcting operation setting on the basis of the electrical resistance of a transfer member, improving the predicting accuracy, and much more appropriately correcting the operation setting.SOLUTION: An image forming apparatus 100 includes: detection means 161 for detecting a value correlated with the electrical resistance of a transfer member 122; correction means 305 for correcting predetermined operation setting on the basis of a value detected by the detection means 161; measurement means 305 for measuring time when a recording material S is stored in a storage part 101; and inhibition means 305 for inhibiting the correction means 305 from correcting the predetermined operation setting. The inhibition means 305 inhibits the correction means 305 from correcting the predetermined operation setting on the basis of a value to be detected by the detection means 161 during a predetermined period to be determined on the basis of the measurement result of the measurement means 305 since the correction means 305 starts first image formation for the recording material S.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, or a facsimile apparatus using an electrophotographic system or an electrostatic recording system.

  2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic method or an electrostatic recording method, toner is applied to an image carrier such as an electrophotographic photosensitive member (photosensitive member), an electrostatic recording dielectric, and an intermediate transfer member by an appropriate image forming process. An image is formed. This toner image is transferred to a recording material (recording medium, transfer material) such as recording paper (paper) by a transfer means. The recording material is output from the main body of the image forming apparatus as an image formed product (print, copy) after the toner image is thermally fixed thereon by the fixing unit.

  In such an image forming apparatus, a transfer roller that is a roller-shaped transfer member is often used as a transfer unit that transfers a toner image from an image carrier to a recording material. In other words, a transfer roller having conductivity and elasticity is brought into contact with the image carrier to form a transfer nip portion which is a transfer portion (transfer position). The recording material is introduced into the transfer nip portion at a predetermined timing and is nipped and conveyed. Further, while the recording material is nipped and conveyed at the transfer nip portion, a transfer voltage having a polarity opposite to the charging polarity of the toner is applied to the transfer roller. Thereby, the toner image on the image carrier is electrostatically moved to the surface of the recording material (electrostatic transfer).

  As a method for controlling the transfer voltage, there is known the following ATVC (Active Transfer Voltage Control) control for appropriately controlling the transfer voltage by measuring the electric resistance of the transfer roller (Patent Document 1). That is, a predetermined constant current is passed through the transfer roller during the pre-rotation process (image forming unit initialization process), which is a preparatory operation before the image forming process, and the electrical resistance of the transfer roller is measured from the applied voltage value at that time. At the time of actual transfer, an appropriate transfer voltage corresponding to the electric resistance is applied to the transfer roller. In addition, when the recording material during continuous image formation for a plurality of recording materials does not exist in the transfer nip portion, the electrical resistance of the transfer roller is measured in the same manner as described above, and an appropriate transfer voltage corresponding to the electrical resistance during actual transfer is measured. Is also applied.

  On the other hand, as a fixing means for thermally fixing a toner image transferred onto a recording material, a heat roller type or a heating film type heat fixing device (hereinafter also simply referred to as “fixing device”) is often used. The heat roller type fixing device includes a heating roller (fixing roller) maintained at a predetermined temperature and a pressure roller having an elastic layer and press-contacting the heating roller to form a fixing nip portion. Then, a recording material is introduced into the fixing nip portion and is nipped and conveyed. As a result, the toner image is thermally fixed to the recording material by the heat of the heating roller. A heating film type fixing device includes a heating body, a film that slides on the heating body (hereinafter referred to as “fixing film”), and a pressure member that forms a fixing nip portion with the heating body via the fixing film. And having. Then, a recording material carrying a toner image is introduced into the fixing nip portion and is nipped and conveyed. As a result, the toner image is thermally fixed to the recording material by the heat from the heating body via the fixing film (Patent Document 2).

  By the way, when a recording material with relatively high moisture absorption is introduced into the fixing nip portion of the fixing device and heated suddenly at a high temperature, it is included in the recording material than in the case of a recording material with relatively low moisture absorption. A large amount of water vapor is generated by evaporating the water. For example, when images are continuously formed on a recording material having relatively high moisture absorption, the toner image is disturbed by water vapor blown from the fixing nip portion, so that an image defect such as a so-called tail image may occur. is there. Further, in the case of a heating film type fixing device, for example, when images are continuously formed on a recording material having a relatively high moisture absorption, as described above, between the fixing film and the recording material in the fixing nip portion. Water vapor may accumulate. If the recording material is conveyed at a high speed in this state, the fixing film slips, and the image after fixing may be disturbed.

  For example, due to a change in humidity in the apparatus when images are continuously formed on a plurality of recording materials such as the phenomenon described above, it may be difficult to form an appropriate image with a certain operation setting.

  For such a problem, it is conceivable to provide an environmental sensor such as a humidity sensor to detect the humidity in the apparatus and adjust, for example, the operation of the fan, the fixing temperature, and the fixing speed. However, providing an environmental sensor for this purpose causes an increase in cost.

  On the other hand, without providing an environmental sensor such as a humidity sensor, the humidity inside the apparatus can be predicted by utilizing the fact that the electrical resistance of the transfer roller changes depending on the humidity (Patent Document 3).

JP-A-2-123385 JP-A-4-44075 JP 2004-333827 A

  As described above, when the humidity inside the machine is predicted by measuring the electrical resistance of the transfer roller, for example, the decrease in the electrical resistance of the transfer roller due to the water vapor generated in the fixing nip is absorbed by the transfer roller. Will do. A predetermined constant current is passed through the transfer roller during a period when the recording material during the continuous image forming operation does not exist in the transfer nip portion, and the humidity of the environment can be predicted from the applied voltage value at that time. Also, until the electrical resistance of the transfer roller becomes constant, it takes time until water vapor generated in the fixing nip reaches the transfer portion located upstream of the fixing nip and is sufficiently absorbed by the transfer roller. . For this reason, for example, it is conceivable to predict the humidity in the apparatus from the amount of change or inclination from the electrical resistance of the transfer roller measured during a period when the recording material is not present in the transfer nip at the initial stage of the continuous image forming operation.

  However, the recording material is stacked in a storage unit such as a cassette (paper basket), and the moisture absorption is not constant between the upper recording material in the storage unit and the lower recording material in the storage unit. Also, the moisture absorption changes according to the time left in the storage unit, and the longer the time, the higher the moisture absorption.

  Therefore, by predicting the humidity inside the machine when forming an image on the upper recording material in the storage unit, which has relatively high moisture absorption, the lower part in the storage unit, where the moisture absorption is relatively low and stable. There is a possibility that the humidity inside the apparatus when forming an image on the recording material cannot be accurately predicted. In other words, the operation setting when forming an image on the lower recording material in the storage unit by correcting the image forming operation setting by predicting the humidity inside the machine while forming an image on the upper recording material in the storage unit However, you may end up in an undesired state.

  Accordingly, an object of the present invention is to improve the prediction accuracy when correcting the operation setting by predicting the humidity inside the apparatus based on the electrical resistance of the transfer member, and correcting the operation setting to a more suitable operation setting. It is an object to provide a possible image forming apparatus.

  The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention relates to an image carrier that carries a toner image, a transfer member that transfers a toner image from the image carrier to a recording material in a transfer portion when a voltage is applied, and a voltage applied to the transfer member. In an image forming apparatus having an applying unit that applies a recording medium and a storage unit that stores a recording material, a voltage that is correlated with the electrical resistance of the transfer member is detected by applying a voltage to the transfer member by the applying unit. Detection means; correction means for correcting a predetermined operation setting based on a value detected by the detection means while continuously forming images on a plurality of recording materials; and a recording material in the storage section. A measuring unit that measures the time held in the storage unit; and when the image is continuously formed on a plurality of recording materials fed from the storage unit, the correction unit performs the transfer on the first recording material. Have you started And a prohibiting unit for prohibiting the correction of the predetermined operation setting based on a value detected by the detecting unit during a predetermined period determined based on a measurement result of the measuring unit. The image forming apparatus.

  According to the present invention, when the operation setting is corrected by predicting the humidity in the apparatus based on the electric resistance of the transfer member, it is possible to improve the prediction accuracy and correct the operation setting to a more suitable operation setting. is there.

1 is a schematic sectional view of an image forming apparatus. FIG. 3 is a schematic diagram illustrating an arrangement of fans of the image forming apparatus. 2 is a block diagram illustrating a control configuration of the image forming apparatus. FIG. 6 is a schematic diagram illustrating storage unit information recorded by the image forming apparatus. FIG. It is a flowchart figure which shows the procedure of the update control of storage part information. It is a flowchart figure which shows the procedure of update control of the prohibition number of sheets performed in update control of storage part information. FIG. 12 is a flowchart illustrating another example of the procedure for updating the prohibited number of sheets performed in the storage unit information update control. It is a chart for demonstrating the period which prohibits correction | amendment of operation | movement setting.

  The image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

Example 1
1. 1 is a schematic cross-sectional view of an image forming apparatus 100 according to an embodiment of the present invention. The image forming apparatus 100 of this embodiment is a laser beam printer using an electrophotographic image forming process. 1 are the left and right sides of the image forming apparatus 100, respectively, and the left and right sides of FIG. 1 are the back (rear) side and the front (front) side of the image forming apparatus, respectively. . The direction connecting the left side and the right side of the image forming apparatus 100 (the direction perpendicular to the paper surface of FIG. 1) is substantially parallel to the longitudinal direction (rotation axis direction) of the photosensitive drum described later.

  The apparatus main body A of the image forming apparatus 100 is provided with the following main components as the recording material feeding / conveying section B. A cassette 101 serving as a storage unit that stores recording paper (paper) as a recording material (recording medium) S. A recording material presence sensor 102 that detects the presence or absence of the recording material S in the cassette 101. A recording material size sensor 103 (consisting of a plurality of microswitches) that detects the size of the recording material S in the cassette 101. A feeding roller 104 for feeding the recording material S from the cassette 101. A feed roller 105 and a retard roller 106 that separate and convey the recording material S fed by the feed roller 104 one by one. A lifter motor (not shown) for controlling the recording material S in the cassette 101 to a height that can be fed by the feeding roller 104. An intermediate roller 107 that conveys the separated recording material S. A pre-feed sensor 108 for confirming the successful feeding of the recording material S on the downstream side of the intermediate roller 107. A registration roller pair 109 that corrects the skew of the recording material S. A top sensor 110 that detects the leading edge of the recording material S. A recording material width sensor (right) 111 and a recording material width sensor (left) 112 that are provided on the left and right in the width direction of the recording material S around the top sensor 110 and detect the width of the recording material S. Here, a plurality of cassettes 101 may be provided. The cassette 101 can be opened and closed (removed from and attached to the apparatus main body A) to replenish the recording material S.

  Further, the apparatus main body A of the image forming apparatus 100 is provided with a laser scanner section D. The laser scanner part D has the following main components. A laser unit 113 that emits a laser beam L that is modulated based on an image signal (VDO signal) obtained by developing image information sent from an external device 301 to be described later. A polygon mirror 114 for scanning laser light from the laser unit 113 on a photosensitive drum 119 described later. A polygon motor 115 that rotates the polygon mirror 114. An imaging lens 116 and a folding mirror 117 for imaging the laser beam from the polygon mirror 114 on the photosensitive drum 119.

  Further, downstream of the registration roller pair 109 in the conveyance direction of the recording material S, a process cartridge (hereinafter also simply referred to as “cartridge”) that forms a toner image on the recording material S based on laser light from the laser scanner unit D. .) C is provided. The cartridge C is detachable from the apparatus main body A of the image forming apparatus 100. The cartridge C has the following main configuration in order to form an image on the recording material S by electrophotography. A photosensitive drum 119 which is a rotatable drum type (cylindrical) electrophotographic photosensitive member (photosensitive member) as an image carrier. A charging roller 120 which is a roller-shaped charging member as charging means for charging the surface of the photosensitive drum 119 to a uniform potential. A developing device 118 as a developing unit that supplies toner as a developer by a developing roller 121 as a developer carrying member to form a toner image on the photosensitive drum 119. A cleaner 123 that removes and collects transfer residual toner remaining on the photosensitive drum 119 without being transferred onto the recording material S by a transfer roller 122 described later. Here, at the time of image formation, the photosensitive drum 119 is rotationally driven in the direction of the arrow R1 in the drawing, and the surface of the rotating photosensitive drum 119 is charged by the charging roller 120. The charged surface of the photosensitive drum 119 is exposed by laser light from the laser scanner unit D, and an electrostatic latent image (electrostatic image) is formed on the surface of the photosensitive drum 119. The electrostatic latent image formed on the photosensitive drum 119 is developed (visualized) as a toner image by the toner supplied by the developing device 118.

  Further, a transfer roller 122 that applies a voltage having a polarity opposite to the charging polarity (normal charging polarity) of the toner at the time of development to the photosensitive drum 119 from the back surface of the recording material S to the apparatus main body A of the image forming apparatus 100. Is provided. The toner image on the photosensitive drum 119 is electrostatically applied to the recording material S conveyed to the transfer nip portion (transfer portion) N where the photosensitive drum 119 and the transfer roller 122 abut by the registration roller pair 109 by the action of the transfer roller 122. Is transcribed. A transfer voltage having a polarity opposite to the normal charging polarity (negative polarity in this embodiment) of the toner is applied to the transfer roller 122 from a transfer power supply 160 as an application unit.

  The apparatus main body A of the image forming apparatus 100 is provided with a heating film type fixing device 124 as the fixing unit E. The fixing device 124 heat-fixes the toner image formed on the recording material S on the recording material S downstream of the cartridge C in the conveyance direction of the recording material S. The fixing device 124 has the following main components. A fixing film 125 and a pressure roller 126 that contact each other to form a fixing nip portion. A ceramic heater (fixing heater) 127 that is provided inside the fixing film 125 and heats the toner image on the recording material S by heat generation. A thermistor 128 that detects the surface temperature of the ceramic heater 127. A fixing sensor 129 that detects the presence or absence of the recording material S downstream of the fixing nip formed by the fixing film 125 and the pressure roller 126 in the conveyance direction of the recording material S. Here, in the heating film type fixing device, a heating element having a low heat capacity and a high temperature rise such as a ceramic heater can be used, and a thin film having a small heat capacity can be used as the fixing film. By heating only the fixing nip portion, a quick start property is good and an energy-saving heating device can be realized. In other words, there is an advantage that the power consumption can be kept low because it is not necessary to heat during standby. The fixing device 124 is an example of a heating unit that heats the recording material S to which the toner image is transferred.

  Further, the apparatus main body A of the image forming apparatus 100 is provided with the following main components as the recording material discharge conveyance unit F. A triple roller 130 for conveying the recording material S on which the toner image is fixed by the fixing device 124 to the stacking tray 151 or the duplex unit 140. A recording material discharge path 131 for discharging the recording material S to the stacking tray 151 by the recording material discharge roller 150 downstream of the fixing device 124 in the conveyance direction of the recording material S. A double-sided conveyance path 132 that reverses the image forming surface and conveys it to the image forming unit in order to form an image on the second surface of double-sided image formation downstream of the fixing device 124 in the conveyance direction of the recording material S. A duplex unit 140 through which the recording material S on which the image is formed on the first surface is conveyed through the duplex conveyance path 132. Here, the duplex unit 140 includes skew feeding rollers 141a and 141b, a duplex recording material sensor 142, a duplex feeding roller 143, and a lateral registration regulating plate (not shown).

  The apparatus main body A of the image forming apparatus 100 is provided with a fan (cooling fan) that sucks air from the outside of the apparatus main body A into the inside or exhausts air from the inside of the apparatus main body A to the outside. 2A and 2B are schematic views showing the arrangement of the fans, in which FIG. 2A is a view of the image forming apparatus 100 viewed from the left side, and FIG. 2B is a view of the image forming apparatus viewed from the right side. An intake fan 201 that cools the power supply board is provided on the left side surface of the apparatus main body A. The intake fan 201 includes an outside air temperature sensor 202. The outside air temperature sensor 202 is an example of an environment detection unit that detects at least one of the temperature and humidity of the environment of the image forming apparatus 100. In particular, in this embodiment, the outside air temperature sensor 202 detects the temperature of the air in the outside environment of the image forming apparatus 100 when the intake fan 201 is driven. Further, exhaust fans 203 and 204 for cooling the cartridge C are provided on the left side surface and the right side surface of the apparatus main body A, respectively. Further, an exhaust fan 205 for cooling the fixing device 24 is provided on the right side surface of the apparatus main body A.

  In this embodiment, the above-described laser scanner unit D, cartridge C, transfer roller 122, and the like constitute an image forming unit.

2. Control Configuration Next, a control configuration of the image forming apparatus 100 of the present embodiment will be described. FIG. 3 is a block diagram illustrating a control configuration of the image forming apparatus 100.

  An external device 301 such as a personal computer transmits image information to be imaged together with the image formation information to the image forming device 100 via a general-purpose interface 302 (Centronics, RS232C, LAN, etc.). Here, the image formation information includes size information of the recording material S, cassette designation information, double-sided image formation presence / absence information, and the like. The video controller 303 develops the image information transmitted from the external device 301 into bit data and converts it into an image signal (VDO signal), and transmits the VDO signal to the engine controller 305 as a control unit via the video interface 304. To do. The engine controller 305 controls each part of the image forming apparatus 100. For example, the engine controller 305 controls the charging voltage (charging bias) applied to the charging roller 120, the light amount of the laser unit 113, the number of rotations of the polygon motor 115, and the like. The engine controller 305 controls a developing voltage (developing bias) applied to the developing roller 121 constituting the developing device 118, a transfer voltage (transfer bias) applied to the transfer roller 122, and the like. The engine controller 305 controls each part related to the conveyance of the recording material S.

  The high voltage control unit 306 performs high voltage output control in each process such as charging, development, and transfer in accordance with an instruction from the engine controller 305. The optical system control unit 307 controls driving / stopping of the scanner motor 115 and lighting of the laser beam in accordance with an instruction from the engine controller 305. The fixing control unit 308 drives / stops energization of the fixing heater 127 according to an instruction from the engine controller 305. The conveyance control unit 309 drives / stops the motor / roller and the like for conveying the recording material S in accordance with an instruction from the engine controller 305. The cooling control unit 310 drives / stops the fans (201, 203, 204, 205) according to instructions from the engine controller 305.

3. Humidity Prediction and Operation Setting Correction Next, a method for predicting the humidity inside the apparatus main body A (in-machine) and a method for correcting the operation setting of the image forming apparatus 100 based on the prediction result will be described. In the present embodiment, the humidity inside the apparatus is predicted based on the transition of the transfer voltage for making the transfer current applied to the transfer roller 122 constant.

  Here, the image forming apparatus 100 according to the present exemplary embodiment starts a series of image forming operations in which an image is formed on a single or a plurality of recording materials S and discharged (output) from the apparatus main body A, which is started by one start instruction. (Job). A job generally includes an image forming process (printing process), a pre-rotating process, a paper-to-paper (inter-recording-material) process when images are formed on a plurality of recording materials S, and a post-rotating process. The image forming process is a period in which the electrostatic latent image is actually formed on the photosensitive drum 119, the toner image is formed, and the toner image is transferred to the recording material S. The pre-rotation process is a period for performing a preparatory operation before the image forming process. The inter-sheet process is a period corresponding to the interval between the recording material S and the recording material S in the transfer portion N when the image forming process is continuously performed on the plurality of recording materials S. The post-rotation process is a period during which an organizing operation (preparation operation) after the image forming process is performed.

  In this embodiment, the transfer voltage value to be applied to the transfer roller 122 at the time of transfer of the job is determined by ATVC control executed in the pre-rotation process of the job. This transfer voltage value is determined according to the applied voltage value measured in the ATVC control in the pre-rotation process. The transfer voltage value may be the measured applied voltage value itself, or may be obtained from the applied voltage value based on an arithmetic expression, a lookup table, or the like obtained in advance. For this purpose, the image forming apparatus 100 includes an ammeter (current detection circuit) 161 that detects a current flowing through the transfer roller 122 when a voltage is applied to the transfer roller 122 from a transfer power supply 160 as an application unit. The ammeter 161 is an example of a detection unit that detects a value correlated with the electrical resistance of the transfer roller 122 by applying a voltage to the transfer roller 122 from the transfer power supply 160.

  In the present embodiment, this ammeter 161 is used and during a period in which the recording material S during continuous image formation does not exist in the transfer portion N (when the section between the recording material S and the recording material S is in the transfer portion N). A predetermined constant current is passed through the transfer roller 122, and the humidity inside the apparatus is predicted from the applied voltage value at that time. That is, the current flowing by applying a voltage from the transfer power supply 160 to the transfer roller 122 is detected by the ammeter 161 in the inter-sheet process of the job. Then, the output voltage value of the transfer power supply 160 is controlled so that the current value approaches a predetermined value, and the applied voltage value at that time is obtained. As the electric resistance of the transfer roller 122 decreases, the applied voltage value obtained at this time tends to decrease. Further, the higher the humidity in the machine, the more the transfer roller 122 absorbs moisture and the electric resistance tends to decrease. Therefore, the humidity in the machine can be predicted from the applied voltage value obtained at this time.

  In this embodiment, the predetermined operation setting in the job can be corrected according to the humidity in the machine estimated by measuring the electrical resistance of the transfer roller 122 in the inter-sheet process of the job for continuous image formation. Yes. Specifically, the predetermined operation setting can be changed when the applied voltage value measured during the inter-sheet process satisfies a predetermined condition set in advance. Alternatively, the predetermined operation setting can be changed when the change amount (or inclination) of the applied voltage value measured during a plurality of inter-sheet processes satisfies a predetermined condition. Note that, as the amount of change in the applied voltage value, the amount of change in the applied voltage value measured during the paper-to-paper step with respect to the applied voltage measured in the pre-rotation step may be used.

  Here, in the present invention, the predetermined operation setting of the image forming apparatus 100 to be specifically corrected is not particularly limited, and the operation setting that is a preset target value is corrected according to the humidity inside the apparatus. It may be any desired operation setting. Typically, the predetermined operation setting includes the following.

  First, the predetermined operation setting includes the rotation speed of a fan that sucks air from the outside of the apparatus main body A of the image forming apparatus 100 or discharges air from the inside of the apparatus main body A to the outside. For example, when the internal humidity becomes high, the internal humidity can be reduced by increasing the rotation speed of the fan. Thereby, the above-described tailing and slipping of the recording material S at the fixing nip can be suppressed.

  The predetermined operation setting includes a heating temperature by the fixing device 124. For example, by reducing the heating temperature when the humidity in the apparatus becomes high, it is possible to suppress the generation of a large amount of water vapor from the fixing device 124 in a short time during continuous image formation. This can also suppress the above-described tailing and slipping of the recording material S at the fixing nip portion.

  Further, the predetermined operation setting includes a conveyance speed of the recording material S passing through the fixing device 124. For example, when the humidity in the apparatus becomes high, the conveyance speed of the recording material S in the fixing device 124 is improved by reducing the conveyance speed, and slipping of the recording material S at the fixing nip portion can be suppressed.

  Further, the predetermined operation setting includes an interval between recording materials fed to the transfer portion N. For example, when the humidity in the apparatus becomes high, widening the interval between the recording materials can suppress a large amount of water vapor from the fixing device 124 in a short time during continuous image formation. This can also suppress the above-described tailing and slipping of the recording material S at the fixing nip portion.

  Further, the predetermined operation setting may be a transfer voltage that is applied to the transfer roller 122 for transfer in order to change the transfer voltage to a suitable one in the middle of a continuous image forming job.

  In the present embodiment, the current when the voltage is applied to the transfer member is detected by the current detection means, and the voltage value for obtaining a predetermined current value is obtained to obtain information on the electrical resistance of the transfer member. To do. However, since it is only necessary to obtain information on the electrical resistance of the transfer member, the voltage value when the voltage is applied to the transfer member is detected by the voltage detection means, and the current value for obtaining the predetermined voltage value is obtained. Good. For example, when the transfer voltage is controlled at a constant current, a voltage controlled at a constant voltage in the pre-rotation process is applied to the transfer member, the current value at that time is detected, and a desired value at the time of transfer is determined according to the current value. Current value can be obtained. In this case, the detection means can detect information correlated with the electrical resistance of the transfer member by detecting the current value when the voltage controlled by the application means is applied to the transfer member.

  Further, although the fixing device that fixes the unfixed toner image on the recording material is exemplified as the heating unit, the heating unit is not limited to this. In addition to a fixing device for fixing an unfixed toner image on a recording material as a heating unit, the image forming apparatus is a recording material on which the toner image has been temporarily fixed in order to improve the smoothness (glossiness) of the image. In some cases, a gloss imparting device (image heating device) that heats the image is heated again. The change in the operation setting described for the fixing device 124 can also be applied to these arbitrary heating means.

4). Operation Setting Correction Prohibition Control Next, operation setting correction prohibition control in the present embodiment will be described.

  In this embodiment, generally, a deviation in moisture absorption corresponding to the number of recording materials S from the upper surface of the cassette 101 is predicted, and a period during which a change in transfer voltage should not be used for determination of the humidity environment is managed. In order to improve the accuracy of the humidity environment. More specifically, in this embodiment, the electric resistance of the transfer roller 122 is measured until an image is formed on a predetermined number of recording materials among the recording materials S stored in the cassette 101 based on the storage unit information. This will invalidate the result of predicting the humidity inside the aircraft.

  FIG. 4 shows storage unit information in this embodiment. In this embodiment, the engine controller 305 stores storage unit information for each cassette 101 in the storage unit, and updates it with an operation by an operator such as a user, an image forming operation, or the passage of time. As storage unit information, the size of the recording material S (hereinafter also referred to as “paper size” or “paper size (Now)”), the loading amount of the recording material S (hereinafter referred to as “paper loading amount” or “paper loading amount (Now)”). ), And the time during which the recording material S is held after the cassette 101 is opened and closed (hereinafter also referred to as “paper holding time”) is recorded. Further, as storage unit information, the size of the recording material S before opening and closing of the cassette 101 (hereinafter also referred to as “paper size (Before)”), the loading amount of the recording material S before opening and closing of the cassette 101 (hereinafter referred to as “paper loading amount”). (Also referred to as “Before”). Further, as the storage unit information, a prohibited number, which is the number of recording materials S while prohibiting the correction of the operation setting based on the predicted humidity in the apparatus, is recorded.

  In this embodiment, before the operator opens the cassette 101, “A4” size paper is loaded as the recording material S with the paper loading amount of “50%” of the cassette 101, and the operator performs “LTR”. It is assumed that the size paper is replaced with a paper stacking amount of “100%”.

  When the operator opens the cassette 101, the transport control unit 309 detects that the cassette 101 has been opened by the recording material size sensor 103. Next, when the operator changes the paper size and replenishes the cassette 101 with the recording material S and closes the cassette 101, the conveyance control unit 309 determines that the cassette 101 is closed by the recording material size sensor 103 and the paper size. Detect. In response to this, the engine controller 305 moves the “A4” size recorded in the paper size (Now) of the storage unit information to the paper size (Before). Further, the engine controller 305 moves “50%” recorded in the paper stacking amount (Now) to the paper stacking amount (Before). Further, the engine controller 305 records the “LTR” size newly detected by the recording material size sensor 103 on the paper size (Now). Further, the engine controller 305 determines the sheet stacking amount from the drive time of the lifter motor (not shown) of the recording material feeding / conveying section B, and records “100%” in the sheet stacking amount (Now). Since the paper size (Now) is different from the paper size (Before), the paper holding time and the prohibited number of sheets are cleared. The sheet holding time is automatically updated by the engine controller 305 according to the elapsed time. Further, the prohibited number is updated by the engine controller 305 as will be described in detail later.

  As described above, in the present exemplary embodiment, the image forming apparatus 100 includes the storage unit opening / closing detection unit (recording material size sensor 103) and the storage unit internal recording material detection unit (recording material presence / absence sensor 102). Further, the image forming apparatus 100 includes a recording material size detecting unit (recording material size sensor 103) and a recording material stacking amount detecting unit (lifter motor, engine controller 305). Then, the image forming apparatus 100 determines the replacement of the recording material in the storage unit by combining the detection results of the storage unit opening / closing detection unit, the recording material detection unit in the storage unit, the recording material size detection unit, and the recording material stacking amount detection unit. be able to. Further, as will be described in detail below, the image forming apparatus 100 determines whether to invalidate the prediction result of the humidity inside the apparatus. This determination is based on the detection result of the environment detection means (outside air temperature sensor 202), the measurement result of the measurement means (engine controller 305) during sheet holding, and the detection result of the recording material feed detection means (pre-feed sensor 108). Done with.

  FIG. 5 is a flowchart showing a procedure for storage unit information update control.

  When the transport controller 309 detects that the cassette 101 is closed, the engine controller 305 activates storage unit information update control, and stores the storage unit information until the transport controller 309 detects that the cassette 101 has been opened. Update continuously.

  When the transport controller 309 detects that the cassette 101 is closed, the engine controller 305 stores the previous paper size (paper size (Now)) as the previous paper size (paper size (Before)) (S101). ). At the same time, the engine controller 305 saves the previous paper load (paper load (Now)) as the previous paper load (paper load (Before)) (S102). Further, the engine controller 305 updates the paper size (Now) to the paper size detected when the cassette 101 is closed (S103). Further, the engine controller 305 waits for the lift-up of the recording material S in the cassette 101 to be completed (S104), and updates the sheet stacking amount (Now) (S105).

  The engine controller 305 determines whether or not the recording material S has been replaced, and determines whether or not it is necessary to initialize the sheet holding time and the prohibited number of sheets. First, the sheet size (Before) and the sheet size (Now) are determined. Are compared (S106). If the paper sizes are the same, the engine controller 305 next compares the paper stacking amount (Before) with the paper stacking amount (Now) (S107). If it is determined in S106 and S107 that either the sheet size or the sheet stacking amount is different, it is determined that the recording material S has been replaced, the sheet holding time is cleared (S108), and the prohibited number of sheets is cleared (S109). ). It is assumed that the sheet holding time is automatically updated by the engine controller 305 according to the elapsed time even after clearing.

  Thereafter, if the recording material S is fed from the cassette 101 (S110), the engine controller 305 checks whether it is 0 to decrement the prohibited number (S111), and decrements if the prohibited number is other than 0. (S112). Furthermore, when the recording material S in the cassette 101 is exhausted by feeding the recording material S (S113), the engine controller 305 does not need to prohibit the correction of the operation setting based on the humidity prediction result in the apparatus. Therefore, the prohibited number is set to 0 (S114).

  If the recording material S is not lost in the determination in S113, the engine controller 305 executes control to update the prohibited number (S115). As time passes, the recording material S in the cassette 101 absorbs moisture from the top, and the number of unstable recording materials S having relatively high moisture absorption that cannot be used for measuring the humidity in the apparatus increases. Environmental temperature and environmental humidity affect the increase in elapsed time and moisture absorption. Therefore, in this embodiment, in the system in which the ambient temperature sensor 202 determines the ambient temperature and the ambient humidity at the same time, the control for updating the prohibited number is executed as described below.

  FIG. 6 is a flowchart showing a specific procedure of control for updating the prohibited number in S115 of FIG.

  First, the engine controller 305 determines the environmental temperature from the temperature detected by the outside air temperature sensor 202 (S201). The environment is classified into three environments of HH environment (high temperature and high humidity) / NN environment (normal temperature and normal humidity) / LL environment (low temperature and low humidity) according to the voltage output by detecting the temperature of the outside air temperature sensor 202. For example, the HH environment is about 30 ° C./80% RH, the NN environment is about 23 ° C./50% RH, and the LL environment is about 15 ° C./10% RH. It can be said that the higher the temperature and humidity, the faster the number of recording materials S that cannot be used to predict the humidity in the apparatus from the upper part to the lower part of the cassette 101 due to moisture absorption. In the HH environment, the engine controller 305 sets the update timing of the prohibited number of sheets to 5 minutes (S202). Further, the engine controller 305 sets the update timing of the prohibited number of sheets to 10 minutes in the NN environment (S203). Further, in the case of the LL environment, the engine controller 305 sets the update timing of the prohibited number of sheets to 15 minutes (S204).

  Next, the engine controller 305 compares the sheet holding time with the update timing of the prohibited number of sheets (S205). If the paper holding time exceeds the prohibition number update timing, the engine controller 305 increments the prohibition number (S206), and subtracts the prohibition number update timing from the paper holding time (S207).

  The engine controller 305 refers to the recorded prohibited number every time the recording material S is fed from the cassette 101 during the image forming operation. If the prohibited number is not 0, the engine controller 305 performs the in-machine operation performed during the image forming operation. Invalidate the humidity prediction results. Then, the correction of the operation setting based on the prediction result of the humidity inside the apparatus at the time of image formation as described above, for example, the correction of the operation setting such as the change of the transfer voltage, the change of the fan drive control, or the change of the fixing temperature is not performed. Like that. In this embodiment, this series of control is operation setting correction prohibition control. On the other hand, the engine controller 305 performs the predictive control of the humidity inside the apparatus by measuring the electric resistance of the transfer roller 122 again when the recorded number of prohibited sheets reaches 0, and sets the operation according to the prediction result. Perform the correction.

  FIG. 8 shows, as an example, the state of the transfer unit N indicating a predetermined period (prohibition period) for prohibiting correction of the operation setting when the initial prohibition number is 10 in a continuous image forming job. FIG. As shown in the figure, in the pre-rotation process before the image forming process in the continuous image forming job, the transfer voltage in the job is determined by the above-described ATVC control. Thereafter, the image forming process for the first to tenth recording materials S and the inter-sheet process immediately after each recording material S are repeated. In this case, in this embodiment, the tenth recording material from the start of the image forming process for the first recording material (that is, when the leading edge of the first recording material S reaches the transfer portion N). Until the end of the image forming process (that is, when the trailing edge of the tenth recording material S passes through the transfer portion N and the interval between the sheets immediately after it reaches the transfer portion) Period). In this case, the measurement result of the electrical resistance of the transfer roller 122 in the inter-sheet process immediately after the 10th sheet (that is, immediately before the 11th sheet) can be reflected in the correction of the operation setting.

  As described above, the image forming apparatus 100 according to the present exemplary embodiment sets a predetermined operation based on the value detected by the detection unit (ammeter) 161 while continuously forming images on the plurality of recording materials S. Correction means (in this embodiment, the engine controller 305) is provided. Further, the image forming apparatus 100 includes a measuring unit (an engine controller 305 in this embodiment) that measures the time during which the recording material S in the storage unit is held in the storage unit 101. Further, the image forming apparatus 100 includes a prohibiting unit (in this embodiment, the engine controller 305) that prohibits the correcting unit from correcting a predetermined operation setting as follows. That is, based on the value detected by the detection unit 161 during a predetermined period determined based on the measurement result of the measurement unit after the correction unit starts image formation on the first recording material S during continuous image formation. It is prohibited to correct a predetermined operation. In the present embodiment, this predetermined period is the first recording material S determined based on the measurement result of the measuring means when images are successively formed on the plurality of recording materials S fed from the storage unit 101. Is a period from when image formation to a predetermined number of recording materials S is completed. The predetermined period is longer as the time measured by the measuring unit 309 is longer. In this embodiment, the predetermined period varies according to at least one of temperature and humidity detected by the environment detection unit 202. In particular, in the present embodiment, this predetermined period is not the case where at least one of the temperature and humidity detected by the environment detection unit 202 is equal to or higher than a threshold value (for example, temperature 30 ° C. or higher or humidity 80% RH or higher). Longer than.

  In this embodiment, the environmental temperature and the environmental humidity are determined from the detection result of the outside air temperature sensor 202, and the predetermined number is changed according to the environmental temperature and humidity. However, the present invention is not limited to this. Absent. Typically, it can be said that the higher the temperature and the higher humidity environment, the faster the number of recording materials S that cannot be used for predicting the humidity in the apparatus from the upper part to the lower part of the cassette 101 due to moisture absorption. Therefore, the predetermined period may be changed according to at least one of temperature and humidity.

  In addition, in order to prohibit the correction of the operation setting, execution of predictive control of humidity in the machine (measurement of applied voltage value between papers) itself may be prohibited, and the result of predictive control of humidity in the machine may be prohibited. It may be prohibited to reflect the correction in the operation setting.

5). Effect As described above, when the recording material S is left in the cassette 101, the recording material S gradually absorbs moisture from the recording material S on the upper surface of the cassette 101 with time. Further, the recording material S closer to the upper surface has a higher moisture absorption and is unstable. As the recording material S moves away from the upper surface, the moisture absorption decreases and becomes stable. As described above, a state in which the moisture absorption is uneven occurs in the cassette 101.

  In the image forming apparatus 100 according to the present exemplary embodiment, the humidity in the apparatus for determining whether or not to correct the operation setting is predicted for the recording material S in which the moisture absorption amount in the cassette 101 is not stable and increases. The period during image formation is invalidated. Thereby, it is prohibited to correct the operation setting based on the prediction result of the humidity inside the apparatus during this period, and it is possible to suppress the correction of the unnecessary operation setting. Then, after the image is formed on the recording material S having a stable moisture absorption amount, the humidity inside the apparatus is predicted again. As a result, the operation setting can be corrected at an appropriate timing. As a result, an image can be formed with an operation setting more suitable for the recording material S actually used.

  As described above, according to the present embodiment, it is possible to improve the prediction accuracy of the humidity in the apparatus by measuring the electric resistance of the transfer roller 122 during a period when the recording material S is not present in the transfer nip portion N during the image forming operation. It becomes possible. Then, according to the present embodiment, it is possible to suppress correction of unnecessary operation settings by prohibiting correction of operation settings during a period when the prediction result of the humidity inside the machine is not stable. Then, the operational setting can be corrected at an appropriate timing by predicting the internal humidity again after the prediction result of the internal humidity becomes stable. As a result, an image can be formed with an operation setting more suitable for the recording material S actually used.

Example 2
Next, another embodiment of the present invention will be described. Another embodiment of image formation according to this embodiment will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the first embodiment. Therefore, elements having the same functions and configurations as those of the first embodiment or corresponding to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The change in the moisture absorption of the recording material S left in the cassette 101 is affected not only by the environmental temperature / environmental humidity but also by the basis weight and surface properties of the recording material S. Therefore, in this embodiment, the control for updating the prohibited number in S115 in the procedure shown in FIG. 5 described in the first embodiment is control in consideration of the recording material information indicating the basis weight and surface property of the recording material S. .

  In this embodiment, a control panel 170 (FIG. 1) as an operation unit provided in the image forming apparatus 100 is used as a recording material information acquisition unit. It is assumed that recording material information is input from the control panel 170 when the operator opens and closes the cassette 101. However, as the recording material information acquisition means, any recording material information can be used as long as the recording material information can be obtained when the cassette 101 is opened and closed. For example, there are a method of inputting from a printer driver of a PC (personal computer) and a method of acquiring recording material information by a media sensor provided in the cassette 101.

  In this embodiment, when the engine controller 305 detects that the cassette 101 is closed, the engine controller 305 notifies the video controller 303 that the cassette 101 has been closed via the video interface 304. In response to this, the video controller 303 causes the control panel 170 to display a message prompting the operator to input recording material information to the control panel 170. The operator inputs the type of the recording material S set in the cassette 101 using the operation keys on the control panel 170 in accordance with this message. In response to this, the video controller 303 notifies the engine controller 305 of the recording material information via the video interface 304.

  FIG. 7 is a flowchart showing a specific procedure in this embodiment of the control for updating the prohibited number in S115 of FIG.

  First, the engine controller 305 determines the environmental temperature from the temperature detected by the outside air temperature sensor 202 (S301). The environment is classified into three environments of HH environment (high temperature and high humidity) / NN environment (normal temperature and normal humidity) / LL environment (low temperature and low humidity) according to the voltage output by detecting the temperature of the outside air temperature sensor 202. In the HH environment, the engine controller 305 sets the update timing of the prohibited number of sheets to 5 minutes (S302). Further, the engine controller 305 sets the update timing of the prohibited number of sheets to 10 minutes in the NN environment (S303). Further, in the case of the LL environment, the engine controller 305 sets the update timing of the prohibited number of sheets to 15 minutes (S304).

  Next, the engine controller 305 confirms the recording material information notified from the video controller 303 (S305). In this embodiment, the following five types are set as the types of recording materials S. "Light" belonging to a range with a relatively small basis weight, "Heavy" belonging to a range with a relatively large basis weight, "Normal" with a basis weight in the middle of these, "Rough" with a surface property of more than a certain level, “Plain” has a smoother surface property. It can be said that the larger the basis weight and the rougher the surface property, the faster the number of recording materials S that cannot be used for predicting the humidity in the apparatus from the upper part to the lower part of the cassette 101 due to moisture absorption. When the recording material information is “Normal” or “Plain”, the engine controller 305 does not change the update timing of the prohibited number of sheets. If the recording material information is “Light”, the engine controller 305 adds 1 minute to the update timing of the prohibited number of sheets (S306). If the recording material information is “Heavy”, the engine controller 305 subtracts 1 minute from the update timing of the prohibited number of sheets (S307). If the recording material information is “Rough”, the engine controller 305 subtracts 2 minutes from the update timing of the prohibited number of sheets (S308).

  Next, the engine controller 305 compares the sheet holding time with the update timing of the prohibited number of sheets (S309). If the paper holding time exceeds the prohibition number update timing, the engine controller 305 increments the prohibition number (S310), and subtracts the prohibition number update timing from the paper holding time (S311).

  As described above, in the present embodiment, the predetermined period during which the correction of the operation setting is prohibited varies depending on the type of the recording material S stored in the storage unit 101. In particular, in this embodiment, the recording material S is paper, and the predetermined period is longer as the basis weight of the recording material S stored in the storage unit 101 is larger, and the recording material S stored in the storage unit 101 is longer. The rougher the surface properties, the longer. Note that at least one of the information related to the basis weight of the recording material S or the information related to the surface property may be used.

  In this embodiment, after the update timing of the prohibited number of sheets is determined according to the outside air temperature, this is uniformly corrected by the recording material information regardless of the outside air temperature. However, the prohibition number update timing may be uniquely determined by a combination of the outside air temperature and the recording material information. Further, the basis weight of the recording material S can be used as the recording material information, and the update timing of the prohibited number of sheets can be set more finely.

  As in the first embodiment, when the prohibited number of recorded sheets is not 0, the engine controller 305 invalidates the prediction result of the in-machine humidity performed during the image forming operation and does not correct the operation setting. To. On the other hand, the engine controller 305 performs the predictive control of the humidity inside the apparatus by measuring the electric resistance of the transfer roller 122 again when the recorded number of prohibited sheets reaches 0, and sets the operation according to the prediction result. Perform the correction.

  As described above, in the image forming apparatus 100 of the present embodiment, the influence of the humidity in the apparatus due to the difference in the surface property of the recording material S and the basis weight of the recording material S is considered. Thereby, in addition to the effect similar to Example 1, the prediction control of the in-machine humidity can be implemented at a more appropriate timing, and the more accurate prediction result of the in-machine humidity can be obtained. As a result, it is possible to form an image with operation settings more suitable for the recording material S actually used.

Others While the present invention has been described with reference to specific embodiments, the present invention is not limited to the above-described embodiments.

  For example, in the above-described embodiment, the transfer member is a transfer roller that forms a transfer portion in contact with a photosensitive drum as an image carrier, but is not limited thereto. The transfer member may be, for example, a transfer member that forms a secondary transfer portion in contact with an intermediate transfer member in an intermediate transfer type image forming apparatus. As is well known in the art, an intermediate transfer type image forming apparatus has a toner image formed on, for example, a photosensitive drum as a first image carrier, and an endless belt as a second image carrier. Primary transfer is performed on the intermediate transfer belt that is the formed intermediate transfer member. The toner image primarily transferred to the intermediate transfer belt is secondarily transferred to a recording material such as recording paper by the action of a secondary transfer member which is a transfer member. Then, the recording material on which the toner image is secondarily transferred undergoes a fixing process in the same manner as in the above-described embodiment, and is then discharged out of the main body of the image forming apparatus. As the secondary transfer member, for example, a secondary transfer roller that is in contact with the intermediate transfer belt and forms a secondary transfer portion is used, similarly to the transfer roller in the above-described embodiment. Even in such an image forming apparatus, the present invention can be applied in relation to the secondary transfer roller.

  In addition, the transfer member is not limited to a roller-like member, and is, for example, a plate shape (blade shape), a sheet shape, or a brush shape that is disposed so as to contact and rub the moving image carrier. In addition, it may be in any form such as a block shape.

DESCRIPTION OF SYMBOLS 101 Cassette 103 Recording material size sensor 119 Photosensitive drum 122 Transfer roller 124 Fixing device 160 Transfer power supply 161 Ammeter 201 Fan 202 Outside air temperature sensor

Claims (13)

An image carrier for carrying a toner image;
A transfer member for transferring a toner image from the image carrier to a recording material in a transfer portion by applying a voltage;
Applying means for applying a voltage to the transfer member;
A storage section for storing the recording material;
In an image forming apparatus having
Detecting means for detecting a value correlated with an electric resistance of the transfer member by applying a voltage to the transfer member by the applying means;
Correction means for correcting a predetermined operation setting based on a value detected by the detection means while continuously forming images on a plurality of recording materials;
Measuring means for measuring the time that the recording material in the storage unit is held in the storage unit;
When continuously forming images on a plurality of recording materials fed from the storage unit, the correction unit is determined based on the measurement result of the measurement unit after starting image formation on the first recording material. Prohibiting means for prohibiting correction of the predetermined operation setting based on a value detected by the detecting means during a predetermined period;
An image forming apparatus comprising:   The predetermined period is determined on the basis of the measurement result of the measuring means when continuously forming images on a plurality of recording materials fed from the storage unit, and a predetermined number of recordings from the first recording material The image forming apparatus according to claim 1, wherein the image forming apparatus has a period until image formation on the material is completed.   The image forming apparatus according to claim 1, wherein the predetermined period is longer as a time measured by the measuring unit is longer.   An environment detecting unit that detects at least one of an environmental temperature and a humidity of the image forming apparatus, and the predetermined period changes according to at least one of the temperature or the humidity detected by the environment detecting unit. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   5. The image forming apparatus according to claim 4, wherein the predetermined period is longer when at least one of the temperature and the humidity is equal to or higher than a threshold, and when it is not.   The image forming apparatus according to claim 1, wherein the predetermined period varies depending on a type of recording material stored in the storage unit.   The image forming apparatus according to claim 6, wherein the recording material is paper, and the predetermined period is longer as a basis weight of the recording material stored in the storage unit is larger.   The image forming apparatus according to claim 6, wherein the recording material is paper, and the predetermined period is longer as the surface property of the recording material stored in the storage portion becomes rougher.   The correcting means is based on a value detected by the detecting means when a section between the recording material and the recording material is in the transfer portion while images are continuously formed on a plurality of recording materials. The image forming apparatus according to claim 1, wherein the predetermined operation setting is corrected.   The correction means corrects the predetermined operation setting based on a change amount of a value detected by the detection means while continuously forming images on a plurality of recording materials. Item 10. The image forming apparatus according to any one of Items 1 to 9.   11. The image forming apparatus according to claim 1, wherein the detection unit detects a voltage value when a voltage controlled by a constant current by the application unit is applied to the transfer member. .   The image forming apparatus according to claim 1, wherein the detection unit detects a current value when a voltage controlled by a constant voltage by the application unit is applied to the transfer member. .   The predetermined operation setting includes a rotational speed of a fan that sucks air into or out of the apparatus main body of the image forming apparatus, and a recording material onto which a toner image is transferred. The heating temperature by the heating means for heating the recording material, the conveyance speed of the recording material passing through the heating means, the interval between the recording materials fed to the transfer section, and the voltage applied to the transfer member for the transfer, The image forming apparatus according to claim 1, wherein the image forming apparatus is at least one of them.

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