JP2019061012A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus capable of improving a predicted accuracy of a time period from the start of heating a fixing device to reaching a target temperature, and thereby achieving a fast FPOT.SOLUTION: The image forming apparatus has: a fixing device having a rotary member, a heater, a temperature detection unit and a pressurizing member; a memory unit in which relational information relating to the temperature of the pressurizing member is preliminarily stored, the relational information based on a lapse time from the start time when application of a voltage to the heater is started and based on the temperature of the heater detected by the temperature detection unit during the lapse time; a conveyance unit for conveying a sheet to a nip portion of the fixing device; and a control unit for controlling the conveyance of the sheet by the conveyance unit. The control unit predicts a temperature of the pressurizing member based on the temperature of the heater detected by the temperature detection unit, the lapse time, and the relational information stored in the memory unit, and controls the conveyance unit to start to convey the sheet when the predicted temperature reaches a threshold or higher.SELECTED DRAWING: Figure 7

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine and an electrophotographic printer (for example, a laser beam printer, an LED printer).

  In an electrophotographic image forming apparatus, a fixing device for heating a toner image and fixing it on a sheet is mounted. The fixing device nips and conveys the sheet at the fixing nip portion and applies heat and pressure to the toner image on the sheet to fix the toner image to the sheet. Therefore, in order to perform fixing in the fixing device, it is necessary to heat the fixing nip portion to a predetermined target temperature before the sheet reaches the fixing nip portion.

  Here, in recent years, shortening of first print out time (hereinafter referred to as “FPOT”), which is a time from the start of an image forming operation to the complete output of an image formed sheet in an image forming apparatus, is required. It is done. In order to shorten the FPOT, it is necessary to predict the time from the start of heating of the fixing nip to reaching the target temperature, and to start conveying the sheet toward the fixing nip at the earliest possible timing according to the predicted value. .

  Therefore, in Patent Document 1, the time until the target temperature is reached is predicted based on the detection temperatures of the thermistor at arbitrary two detection times from the start of heating of the fixing nip portion to the arrival of the target temperature. The configuration for determining the time is described.

JP 2001-236126 A

  The temperature detection unit such as a thermistor that detects the temperature of the heater that is the heating source of the fixing nip portion changes in resistance value against the applied heat although the resistance value changes due to the temperature change according to the applied heat The response speed of the device varies from element to element. Further, the temperature rise of the fixing nip portion (particularly, a pressure member constituting the fixing nip portion) varies depending on the individual fixing device.

  However, in the configuration described in Patent Document 1, it is difficult to predict the time from the start of heating by the heater to the arrival of the target temperature in consideration of the responsiveness of the temperature detection unit as described above. For this reason, it is necessary to match the time until the target temperature is reached with the temperature detection unit having poor responsiveness, and an extra waiting time is generated to delay the FPOT. Further, in the configuration described in Patent Document 1, when predicting the temperature of the fixing nip portion (in particular, the pressing member that constitutes the fixing nip portion), the temperature rise of the fixing nip portion that varies depending on each fixing device is accurately predicted. Things are difficult.

  Therefore, the present invention has been made in view of such a current situation, and an image forming apparatus capable of speeding up FPOT by improving the prediction accuracy of the time from the start of heating of the fixing device to the arrival of the target temperature. Intended to be provided.

  A representative configuration of an image forming apparatus according to the present invention for achieving the above object is a rotating member, a heater which generates heat by contacting an inner surface of the rotating member and is energized, and heating the rotating member. A temperature detection unit for detecting the temperature of the heater, the rotation member is pressurized to form a nip portion with the heater via the rotation member, and the developer image on the sheet is nipped and conveyed in the nip portion A fixing device having a pressing member that heats and fixes the sheet by the heat of the heater; an elapsed time elapsed from the start of the start of application of a voltage to the heater; and the temperature detection unit at the elapsed time Storage unit in which related information related to the temperature of the pressure member based on the temperature of the heater detected by the control unit is stored in advance, and the sheet toward the nip portion of the fixing device And a control unit configured to control conveyance of a sheet by the conveyance unit. The control unit controls the temperature of the heater detected by the temperature detection unit, the elapsed time, and the storage time. The temperature of the pressing member is predicted based on the related information stored in the unit, and the conveyance of the sheet by the conveyance unit is started when the predicted temperature becomes equal to or higher than a threshold. .

  According to the present invention, in the image forming apparatus, it is possible to improve the prediction accuracy of the time from the start of heating of the fixing device to the arrival of the target temperature, and to speed up FPOT.

FIG. 1 is a schematic cross-sectional view of an image forming apparatus. FIG. 2 is a schematic cross-sectional view of a fixing device. FIG. 2 is a block diagram showing a control system of the image forming apparatus. It is a block diagram showing composition of a characteristic information measuring device. It is a flowchart of a characteristic information measurement sequence. It is a measurement result of characteristic information ΔT. 7 is a flowchart of a sheet feeding permission determination sequence. It is a graph which shows the measurement result of the temperature of a heater with respect to the elapsed time from the largest electric power supply start to a heater start, and the temperature of a pressure roller. 7 is a flowchart of a sheet feeding permission determination sequence. It is a graph which shows the measurement result of the temperature of a heater with respect to the elapsed time from the largest electric power supply start to a heater start, and the temperature of a pressure roller.

First Embodiment
<Image forming apparatus>
Hereinafter, the entire configuration of the image forming apparatus according to the first embodiment of the present invention will be described together with the operation at the time of image formation with reference to the drawings.

  The image forming apparatus A of FIG. 1 is an electrophotographic image forming apparatus which is a monochrome laser printer. The image forming apparatus A includes: an image forming unit that transfers a toner image to a sheet that is a recording material such as paper; a sheet feeding unit that supplies a sheet that is a recording material such as paper toward the image forming unit; And a fixing unit configured to fix the toner image to a sheet as the recording material.

  The image forming unit includes a photosensitive drum 101 (image carrier), a charging roller 102, a developing device 104, a laser scanner unit 103, a transfer roller 106, and the like.

  At the time of image formation, when the control unit 205 shown in FIG. 3 receives an image forming job signal, the sheet S stacked and stored in the sheet stacking unit 111 by the feeding roller 110 (conveying unit) and the conveying rollers 112 and 113 form an image. It is sent out to the department.

  On the other hand, in the image forming unit, a bias is applied to the charging roller 102, whereby the surface of the photosensitive drum 101 in contact with the charging roller 102 is charged. Thereafter, the laser scanner unit 103 emits a laser beam from a light source (not shown), and irradiates the photosensitive drum 101 with the laser beam according to the image information. As a result, the potential of the photosensitive drum 101 is partially lowered, and an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive drum 101.

  Thereafter, a bias is applied to the developing sleeve 120 included in the developing device 104, whereby toner is attached to the electrostatic latent image formed on the surface of the photosensitive drum 101 from the developing sleeve 120, and a toner image (developer image) is formed. Ru.

  Next, the toner image formed on the surface of the photosensitive drum 101 is sent to a transfer nip portion formed between the photosensitive drum 101 and the transfer roller 106. When the toner image arrives at the transfer nip portion, a bias having a polarity opposite to the charging polarity of the toner is applied to the transfer roller 106, and the toner image is transferred onto the sheet S. The toner remaining on the surface of the photosensitive drum 101 after transfer is scraped off by the cleaning blade 105 and removed.

  Thereafter, the sheet S to which the toner image has been transferred is sent to the fixing device 107, and heated and pressed in the fixing nip portion formed between the fixing film 108 and the pressure roller 109 of the fixing device 107, and the toner image is The sheet S is fixed. Thereafter, the sheet S is discharged onto the discharge tray 117 by the discharge roller 116.

<Fixing device>
Next, the configuration of the fixing device 107 (fixing device) will be described.

  FIG. 2 is a schematic cross-sectional view of the fixing device 107. As shown in FIG. As shown in FIG. 2, the fixing device 107 has a heating unit that heats the toner image carried on the sheet S, melts the toner, and causes the sheet S to be fixed and fixed. Further, the fixing film 108, which is a rotating member of the heating unit, is in pressure contact with the fixing film 108 to form a fixing nip portion together with the fixing film 108 to hold and convey the sheet S. In the present embodiment, the pressure roller is described as a pressure member, but depending on the configuration, it may be a film or a belt.

  The heating unit includes a fixing film 108 as a rotating member, a heater 201 for heating the fixing film 108, a thermistor 202 for detecting the temperature of the heater 201, and a holder member 210 for holding the fixing film 108 and the heater 201.

  The pressing roller 109 as a pressing member is rotatably supported at both ends, and a gear (not shown) disposed at the end is rotated by receiving a driving force from a driving source (not shown).

  The fixing film 108 as a rotation member is externally fitted to the holder member 210 and rotatably supported. The fixing film 108 as a rotating member is driven to rotate by the frictional force of the pressure roller 109 as a rotating pressure member.

  The heater 201 is disposed in contact with the inner surface of the fixing film 108 in the fixing nip portion, generates heat by energization, and heats the fixing film 108 from the inner surface side. Further, the heater 201 is fitted in the groove of the heater substrate 211 and thermally insulated. The heater substrate 211 is fitted and held in the holder member 210, thereby fixing the heater 201 to the holder member 210 via the heater substrate 211.

  Further, a thermistor 202 as a temperature detection unit for detecting the temperature of the heater 201 is provided on the side of the heater substrate 211 facing the holder member 210.

  Further, the fixing device 107 is mounted with a memory 203 as a storage unit. In the memory 203, characteristic information ΔT of each fixing device 107 is stored in advance. Here, the characteristic information ΔT in the present embodiment is the difference temperature information between the temperature Tth of the heater 201 detected by the thermistor 202 and the temperature Tpr of the pressure roller 109 with respect to the elapsed time from the start of maximum power supply to the heater 201. is there. Specifically, it is differential temperature information of the temperature of the heater 201 detected by the thermistor 202 and the measured temperature of the pressure roller 109 every predetermined time elapsed since the start of the maximum power supply to the heater 201. This difference temperature information is also related information related to the temperature of the pressure roller. The difference temperature information, which is related information related to the pressure roller, is measured by a characteristic information measuring device 301 described later. That is, the characteristic information ΔT is related information on the temperature of the pressure roller 109 based on the temperature of the heater 201 detected by the thermistor 202 in the elapsed time elapsed from the start time when the voltage is applied to the heater 201. It is the information which each apparatus 107 has.

<Control system>
Next, the configuration of the control system of the image forming apparatus A will be described.

  FIG. 3 is a block diagram showing a part of the control system of the image forming apparatus A. As shown in FIG. As shown in FIG. 3, the image forming apparatus A is equipped with a control unit 205 including a CPU. Further, to the control unit 205, the TRIAC 206, the environmental temperature sensor 802, and the heater 201, the thermistor 202, and the memory 203 provided in the fixing device 107 are connected directly or through a communication line.

  The control unit 205 switches between conduction and non-conduction of the triac 206 to control the power supplied from the commercial AC power supply 207 to the heater 201 provided in the fixing device 107. The heater 201 is supplied with the maximum power determined depending on the effective value voltage of the commercial AC power supply 207 and the resistance value of the heater 201.

  Further, when heat is applied to the thermistor 202 by the heat generation of the heater 201, the temperature of the thermistor 202 rises and the resistance value changes. The control unit 205 converts the resistance value of the thermistor 202 into a voltage value. Thus, the thermistor 202 as a temperature detection unit detects the temperature of the heater 201.

  Further, until the temperature of the heater 201 (the temperature detected by the thermistor 202) approaches a target temperature at which the toner image can be fixed, the triac 206 always keeps supplying the maximum power in the conductive state. When the target temperature is approached, the control unit 205 switches between conduction and non-conduction for each half wave of the triac 206 to control the power supplied to the heater 201, thereby maintaining the target temperature.

  An environmental temperature sensor 802 as an environmental detection unit detects room temperature Ti of the environment in which the main body of the image forming apparatus A is installed, and outputs it to the control unit 205.

  Further, the memory 203 as a storage unit stores information such as the above-mentioned characteristic information ΔT. When the fixing device 107 is attached to the main body of the image forming apparatus A, the control unit 205 and the memory 203 as a storage unit are in a communicable state.

<Characteristic information measurement device>
Next, a characteristic information measuring device 301 for measuring and storing characteristic information ΔT in the memory 203 mounted on the fixing device 107 will be described. The measurement of the characteristic information ΔT is carried out by connecting the fixing device 107 to the characteristic information measuring device 301 after removing the fixing device 107 from the image forming apparatus A.

  FIG. 4 is a block diagram showing the configuration of the characteristic information measuring device 301. As shown in FIG. As shown in FIG. 4, the characteristic information measuring device 301 is composed of a temperature measuring device 303, a power control device 304, an arithmetic device 305, a communication device 306, and an environmental temperature measuring device 902.

  The temperature measurement device 303 is connected to the pressure roller 109 and measures the temperature of the pressure roller 109.

  The energization control device 304 is connected to the commercial AC power supply 207 and the heater 201. The energization control device 304 controls the power supplied from the commercial AC power supply 207 to the heater 201 by switching between conduction and non-conduction of the current path from the commercial AC power supply 207 to the heater 201.

  The communication device 306 is connected to the memory 203 mounted on the fixing device 107, and writes information in the memory 203.

  The environmental temperature measurement device 902 detects the room temperature Tm of the measurement environment of the characteristic information ΔT immediately before the start of the measurement operation of the characteristic information ΔT by the characteristic information measurement device 301. The detected room temperature Tm is stored in the memory 203 of the fixing device 107 via the communication device 306.

<Characteristic information measurement sequence>
Next, a characteristic information measurement sequence for measuring the characteristic information ΔT of the fixing device 107 using the characteristic information measurement device 301 will be described using the flowchart shown in FIG.

  As shown in FIG. 5, when the current path is first made conductive by the energization control device 304 and supply of the maximum power determined depending on the effective value voltage of the commercial AC power supply 207 and the resistance value of the heater 201 is started, The measurement is started (S101).

  Next, the resistance value of the thermistor 202 as a temperature detection unit, which changes with the temperature change of the heater 201 due to the power supply, is converted into a voltage value by the arithmetic unit 305 to detect the temperature Tth of the heater 201 (S102). At this time, the arithmetic device 305 detects the temperature Tth of the heater 201 every 0.1 sec from the start of maximum power supply to the start of temperature control by the thermistor 202 as a temperature detection unit.

  At the same time as the temperature detection of the heater 201, the temperature measurement device 303 measures the temperature Tpr of the pressure roller 109 (S103). At this time, the temperature measurement device 303 measures the temperature Tpr of the pressure roller 109 every 0.1 sec from the start of the maximum power supply to the start of the temperature adjustment control.

  Next, characteristic information ΔT which is difference information between the temperature Tth of the heater 201 detected (measured) every 0.1 seconds and the measurement temperature Tpr of the pressure roller 109 is calculated (S104). The calculated characteristic information ΔT is written and stored in the memory 203 by the communication device 306 (S105). That is, before the fixing device 107 is attached to the image forming apparatus A, the characteristic information ΔT is the temperature of the heater 201 detected by the thermistor 202 in the elapsed time from the start of the maximum power supply to the heater 201 in advance. It is information created on the basis of the measurement temperature. The characteristic information ΔT can also be said to be information prepared based on the response speed to the temperature of the thermistor 202 in advance before the fixing device 107 is attached to the image forming apparatus A. FIG. 6 shows the measurement results of the characteristic information ΔT under the conditions of an input effective value voltage of 220 V of the commercial AC power supply 207, a frequency of 50 Hz, and an ambient temperature of 23.5 ° C.

  The fixing device 107 whose characteristic information ΔT is stored in the memory 203 as described above is mounted on the image forming apparatus A. When the image forming apparatus A receives the image forming job signal, the control unit 205 mounted on the image forming apparatus A uses the characteristic information ΔT stored in the memory 203 to feed the sheet S described below. A sheet feed permission determination sequence is performed to determine the permission.

<Feeding permission determination sequence>
Next, the sheet feeding permission determination sequence will be described using the flowchart shown in FIG.

  As shown in FIG. 7, when the power of the image forming apparatus A is first turned on, the control unit 205 communicates with the memory 203 mounted on the fixing device 107 (S201), and the characteristic information stored in the memory 203 is stored. The room temperature Tm at the time of measurement of ΔT and the characteristic information ΔT is read (S202).

  Next, when receiving the image forming job (S203), the control unit 205 detects the room temperature Ti of the environment in which the main body of the image forming apparatus A is installed by the environmental temperature sensor 802 as an environment detecting unit (S204). Then, it is determined whether or not the room temperature Ti of the environment in which the image forming apparatus A is installed detected by the environment temperature sensor 802 as an environment detection unit is equal to or more than the room temperature Tm at the time of measuring the characteristic information ΔT (S205).

  Here, when the room temperature Ti of the environment in which the image forming apparatus A is detected detected by the environment temperature sensor 802 as the environment detection unit is equal to or more than the room temperature Tm at the time of measuring the characteristic information ΔT, supply of maximum power to the heater 201 is started. (S206). After that, the control unit 205 calculates 0.1 based on the following equation 1 based on the elapsed time (t) from the start of maximum power supply, the temperature Tth of the heater 201 detected by the thermistor 202, and the acquired characteristic information ΔT. The temperature Tpr of the pressure roller 109 every second is calculated (S207).

  Tpr (t) = Tth (t) -ΔT (t) (1)

  Next, when the calculated temperature Tpr of the pressure roller 109 becomes equal to or higher than the threshold value ω (equal to or higher than the threshold value), the control unit 205 determines sheet feeding permission (S208, S211). The method of setting the threshold ω will be described later. Thus, the sheet feeding permission determination sequence is completed. After that, the control unit 205 causes the feeding roller 110 to start feeding the sheet S based on the signal of the feed permission determination. That is, the control unit 205 determines the temperature Tpr of the pressure roller 109 based on the elapsed time from the start of the maximum power supply to the heater 201, the temperature of the heater 201, and the characteristic information ΔT of each fixing device 107 stored in the memory 203. Calculate and predict. Then, when the predicted temperature becomes equal to or higher than the threshold value, the feeding of the sheet S by the feeding roller 110 is started. After the time required for the sheet S to reach the fixing nip portion from the start of feeding of the sheet S, the fixing nip portion reaches a target temperature at which the toner image can be fixed to the sheet S.

  As described above, in the present embodiment, the temperature of the fixing nip portion is determined based on the temperature Tpr of the pressure roller 109, and the sheet feeding timing of the sheet S is controlled. The temperature Tpr of the pressure roller 109 mentioned here is a predicted temperature calculated based on the characteristic information ΔT which each fixing device 107 stored in the memory 203 has. Therefore, the time until the target temperature of the fixing nip portion reaches the target temperature is predicted in consideration of the responsiveness of the thermistor 202 to temperature variations due to the individual fixing devices 107 and the ease of temperature increase of the pressure roller 109. be able to. Therefore, it is possible to improve the prediction accuracy of the time until the target temperature of the fixing nip portion is reached as compared with the conventional configuration, and it is possible to achieve speeding up of the FPOT.

  On the other hand, when the room temperature Ti of the environment where the image forming apparatus A is installed is less than the room temperature Tm at the time of measuring the characteristic information ΔT, supply of maximum power to the heater 201 is started (S209). Thereafter, when the temperature Tth of the heater 201 detected by the thermistor 202 becomes equal to or higher than a predetermined target temperature Tg (equal to or higher than a predetermined value), the control unit 205 performs sheet feeding permission determination (S210, S211). Here, the temperature of the fixing nip portion when the temperature Tth of the heater 201 detected by the thermistor 202 reaches the target temperature Tg is when the temperature Tpr of the pressure roller 109 calculated using Equation 1 reaches the threshold value ω The temperature is set to be higher than the temperature of the fixing nip portion.

  As described above, when the room temperature Ti of the environment in which the image forming apparatus A is installed is less than the room temperature Tm at the time of measuring the characteristic information ΔT, the control unit 205 has the temperature of the fixing nip portion than the case where the room temperature Ti is the room temperature Tm or more. The paper feed permission judgment is performed in the high state. As a result, even in an environment where the temperature of the pressure roller 109 is less likely to rise than at the time of measurement of the characteristic information ΔT, the fixability of the fixing device 107 can be maintained favorably.

<Comparison with the configuration of the comparative example>
Next, the configuration of the comparative example is compared with the configuration of the present embodiment.

  FIG. 8 shows the temperature of the heater 201 and the temperature of the pressure roller 109 with respect to the elapsed time from the start of the maximum power supply to the heater 201 in the fixing device 107 (107a, b) equipped with two types of thermistors 202 having different responsiveness. It is a graph which shows the result of having measured. Here, the temperature of the heater 201 and the temperature of the pressure roller 109 are temperatures measured by connecting to the characteristic information measuring device 301.

  Further, in FIG. 8, a solid line indicates the measurement result of the fixing device 107a, and a broken line indicates the measurement result of the fixing device 107b including the thermistor 202, which has better responsiveness than the thermistor 202 included in the fixing device 107a. The temperature Tpr of the pressure roller 109 is lower than the temperature Tth of the heater 201 because the temperature of the portion away from the heater 201 is high. The measurement conditions are an input effective voltage of 220 V, a frequency of 50 Hz, and an ambient temperature of 23.5 ° C. (the same conditions as in the measurement of the characteristic information ΔT shown in FIG. 6).

  As shown in FIG. 8, even if the temperature Tpr of the pressure roller 109 is the same, it can be seen that the temperature Tth of the heater 201 detected by the thermistor 202 is different due to the difference in the responsiveness of the elements of the thermistor 202. That is, the thermistor 202 as a temperature detection unit that detects the temperature of the heater 201 changes the resistance value due to the temperature change according to the applied heat, but the response speed of the resistance value change with respect to the applied heat is There is variation among elements. That is, it can be seen that the correlation between the temperature Tth of the heater 201 detected by the thermistor 202 and the temperature Tpr of the pressure roller 109 differs depending on each fixing device 107.

  Here, for example, when the temperature of the pressure roller 109 is 150 ° C. or more, a case where the fixing nip portion is in a state where the toner image can be fixed will be considered. In the fixing device 107, the time (time t2) required for the sheet S to be conveyed to the fixing nip portion after the sheet feeding of the sheet S is started based on the sheet feeding permission determination of the control unit 205 is 1.8 seconds. I assume.

  In this case, the sheet feeding permission determination by the control unit 205 may be performed 1.8 seconds before the time when the temperature of the pressure roller 109 reaches 150 ° C. That is, as shown in FIG. 8, the time (time t1) at which the temperature of the pressure roller 109 reaches 150 ° C. from the start of maximum power supply to the heater 201 is 3.3 seconds. Therefore, originally, the time (t3) of the sheet feeding permission determination by the control unit 205 may be performed 1.5 seconds after the start of the maximum power supply to the heater 201 (t1 to t2).

  In the configuration of the comparative example, the temperature of the fixing nip portion is determined based on the temperature detected by the thermistor 202, and the sheet feeding permission determination is performed. Here, a configuration will be considered in which the control unit 205 performs the sheet feeding permission determination when the temperature detected by the thermistor 202 exceeds a threshold. As shown in FIG. 7, in the fixing device 107b on which the thermistor 202 of an element having high responsiveness is mounted, the detection temperature of the thermistor 202 1.5 seconds after the start of the maximum power supply to the heater 201 is 122 ° C. Therefore, it is assumed that the threshold is set to 122 ° C. At this time, the fixing device 107a mounted with the thermistor 202 of an element whose response is bad stands by until the detection of 122 ° C. is possible despite the fact that the feeding of the sheet S can be started when the detection temperature of the thermistor 202 is 107 ° C. Do. This causes an extra waiting time of about 0.3 seconds and delays the FPOT.

  On the other hand, in the configuration of the present embodiment, 75 ° C., which is the temperature of the pressure roller 109 1.5 seconds after the start of the maximum power supply (after t3), is set as the threshold value ω. Then, the temperature Tpr of the pressure roller 109 is calculated based on the characteristic information ΔT of each fixing device 107 stored in the memory 203. For this reason, even when the responsiveness of the fixing devices 107a and 107b to the temperature change of the thermistor 202 varies, the image forming apparatus A has a temperature of 75 ° C. for the pressure roller 109 1.5 seconds after the start of the maximum power supply. The sheet feeding permission determination can be performed by calculation. As described above, according to the configuration of the present embodiment, the prediction accuracy of the time to reach the target temperature of the fixing nip portion is improved compared to the configuration of the comparative example in which the temperature of the fixing nip portion is determined based on the detected temperature of the thermistor 202 It is possible to increase the speed of FPOT.

Second Embodiment
Next, the configuration of the image forming apparatus according to the second embodiment of the present invention will be described. About the part which overlaps with the said 1st Embodiment, the same drawing and the same code | symbol are attached | subjected and description is abbreviate | omitted.

  In the present embodiment, in the sheet feeding permission determination sequence, the pressure calculated using the characteristic information ΔT based on the room temperature Tm at the time of measuring the characteristic information ΔT and the room temperature Ti of the environment where the image forming apparatus A main body is installed. The temperature Tpr of the roller 109 is corrected. Hereinafter, the sheet feed permission determination sequence according to the present embodiment will be described with reference to the flowchart shown in FIG. In FIG. 9, the same reference numerals are given to steps performing the same processes as the steps described using FIG. 7 in the first embodiment, and the description will be omitted or simplified.

  The difference between the sheet feeding permission determination sequence of this embodiment and the sheet feeding permission determination sequence of the first embodiment is only the method of calculating the pressure roller 109Tpr. That is, as shown in FIG. 9, in the sheet feeding permission determination sequence of the present embodiment, first, when the room temperature Ti of the environment in which the image forming apparatus A is installed is equal to or more than the room temperature Tm at the time of measuring the characteristic information ΔT Power supply is started (S206). Then, the control unit 205 calculates the following equation based on the temperature Tth of the heater 201 detected by the thermistor 202, the acquired characteristic information ΔT, and the room temperature Tm, Ti with respect to the elapsed time (t) from the start of maximum power supply. The temperature Tpr of the pressure roller 109 is calculated from 2 (S303). At this time, the control unit 205 calculates the temperature Tpr of the pressure roller 109 every 0.1 seconds.

  Tpr (t) = Tth (t) -ΔT (t) -ΔTen (t) (2)

Here, ΔTen is ΔTen = correction coefficient × environmental temperature difference × temporal correction term of environmental temperature = α × (Ti−Tm) × (a × t + b)
(Α = 0.155, a = -3.3992, b = 12.971)
Is a value represented by

  The time correction term of the environmental temperature is a value that can be calculated from the difference between the different characteristic information ΔT measured under the condition that the input effective voltage and the frequency are the same and only the ambient temperature differs. The correction coefficient is a value calculated experimentally to correct the temperature Tpr of the pressure roller 109 using ΔTen including the time dependency information of the environmental temperature difference.

  Thereafter, when the predicted temperature Tpr of the pressure roller 109 becomes equal to or higher than the threshold value ω (equal to or higher than the threshold value), the control unit 205 determines sheet feeding permission (S208, S211). Thus, the sheet feeding permission determination sequence is completed. After that, the control unit 205 causes the feeding roller 110 to start feeding the sheet S based on the signal of the feed permission determination. That is, the control unit 205 controls the pressure of the pressure roller 109 based on the elapsed time from the start of the maximum power supply to the heater 201, the temperature of the heater 201, the characteristic information ΔT of each fixing device 107 stored in the memory 203, and the environmental temperature. The temperature Tpr is calculated and predicted. Then, when the predicted temperature becomes equal to or higher than the threshold value, the feeding of the sheet S by the feeding roller 110 is started.

  As described above, in the present embodiment, with respect to the temperature Tpr of the pressure roller 109 calculated based on the characteristic information ΔT of the individual fixing devices 107 stored in the memory 203, the room temperature Tm at the time of the characteristic information ΔT measurement; The correction is performed based on the room temperature Ti of the installation environment of the image forming apparatus A. That is, the temperature Tpr of the pressure roller 109 is calculated and predicted based on the elapsed time from the start of the maximum power supply to the heater 201, the temperature of the heater 201, and the characteristic information ΔT of each fixing device 107 stored in the memory 203. , And correct the predicted temperature based on the environmental temperature information. Therefore, in addition to the responsiveness of the thermistor 202 to temperature variations due to the individual fixing devices 107 and the ease of temperature rise of the pressure roller 109, the target of the fixing nip portion is taken into consideration as well. The time to reach the temperature can be predicted. For this reason, it is possible to further improve the prediction accuracy of the time until the target temperature of the fixing nip portion is reached, and to speed up the FPOT.

  FIG. 10 is a graph showing measurement results or calculation results of the temperature Tth of the heater 201 detected by the thermistor 202 and the temperature Tpr of the pressure roller 109 with respect to the elapsed time from the start of the maximum power supply to the heater 201 in the fixing device 107. It is. Here, in FIG. 10, a line L1 is the temperature of the pressure roller 109 calculated using the above equation 1. Further, a line L2 is the temperature of the pressure roller 109 calculated using the equation 2. Line L3 is the measured temperature of the pressure roller 109.

  As the measurement conditions, the input effective voltage 220 V of the commercial AC power supply 207, the frequency 50 Hz, and the room temperature Ti of the environment in which the main body of the image forming apparatus A is installed is 17.2 ° C. The room temperature Tm at the time of measurement of the characteristic information ΔT is 23.5 ° C. That is, the measurement is performed under the condition that the room temperature Ti of the environment in which the main body of the image forming apparatus A is installed is 6.3 ° C. lower than that of the characteristic information ΔT.

  As shown in FIG. 10, in the case of room temperature Ti <room temperature Tm, the temperature Tpr of the pressure roller 109 calculated using Equation 1 without correction of the room temperature environment temperature is based on the measured temperature Tpr of the pressure roller 109. It turns out that it becomes high. On the other hand, the temperature Tpr of the pressure roller 109 calculated by performing the environment correction using the equation 2 as in the present embodiment is substantially the same as the actually measured temperature Tpr of the pressure roller 109. Therefore, it can be understood that the calculation accuracy of the temperature Tpr of the pressure roller 109 is improved by performing the environment correction as in the present embodiment.

  Here, for example, when the temperature Tpr of the pressure roller 109 exceeds 150 ° C., it is assumed that the fixing nip portion is in a state where the toner image can be fixed. In the fixing device 107, the time (time t2) required for the sheet S to be conveyed to the fixing nip portion after the sheet feeding of the sheet S is started based on the sheet feeding permission determination of the control unit 205 is 1.8 seconds. I assume.

  In this case, the sheet feeding permission determination by the control unit 205 may be performed 1.8 seconds before the time when the temperature Tpr of the pressure roller 109 reaches 150 ° C. That is, as shown in FIG. 10, the time (time t1) at which the temperature Tpr of the pressure roller 109 reaches 150 ° C. from the start of the maximum power supply to the heater 201 is 3.4 seconds. Therefore, the time (t3) of the sheet feed permission determination by the control unit 205 may be performed 1.6 seconds after the start of the maximum power supply to the heater 201 (t1 to t2). Therefore, 73 ° C., which is the temperature of the pressure roller 109 1.6 seconds after the start of the maximum power supply, is set as the threshold value ω.

  Here, under the environment where the temperature is lower than the measurement environment of the characteristic information ΔT, in the case where the temperature Tpr of the pressure roller 109 is calculated by Equation 1 without using the environmental correction term to perform the sheet feeding permission determination, the pressure roller 109 Although the temperature does not exceed 73 ° C., there is a possibility that the sheet feeding permission determination is made. In this case, image defects such as fixing defects may occur.

  Conversely, when the temperature Tpr of the pressure roller 109 is calculated by Equation 1 without using the environmental correction term under the environment where the temperature is higher than the measurement environment of the characteristic information ΔT, the pressure roller 109 is determined. Even though the temperature exceeds 73 ° C., there is a possibility that the sheet feeding permission determination can not be made. In this case, the FPOT is delayed.

  On the other hand, as in the present embodiment, by calculating the temperature of the pressure roller 109 using the environment correction term according to the equation 2, the prediction accuracy of the temperature of the pressure roller 109 is improved, and the conventional configuration can be achieved. Also, it is possible to improve the prediction accuracy of the time until the target temperature of the fixing nip portion is reached. Accordingly, it is possible to suppress the fixing failure and to speed up the FPOT.

  Although the configuration in which the memory 203 is provided in the fixing device 107 has been described in the first and second embodiments, the present invention is not limited to this. That is, the same effect can be obtained by arranging the memory 203 in the main body of the image forming apparatus A and storing the measurement result by the characteristic information measuring apparatus 301 in the memory 203 by a method such as communication.

  In the first and second embodiments, although the film heating method of heating the toner image on the sheet S by the fixing film 108 is adopted, the present invention is not limited to this. That is, the present invention can also be applied to a configuration in which the fixing nip portion is formed by the heating roller as a rotating member including a heater such as a halogen lamp and the pressure roller 109 as a pressure member. That is, the difference information between the temperature of the heating roller as the rotating member and the measured temperature of the pressing roller 109 as the pressing member with respect to the elapsed time from the start of the power supply to the heater is stored in the memory 203 as the storage unit as the characteristic information ΔT. It is stored in advance. Then, the temperature of the pressure roller 109 is calculated and predicted in the same manner as described above based on the elapsed time from the start of the power supply to the heater and the temperature of the heating roller. The same effect as described above can also be obtained as a configuration for determining permission.

107 ... fixing device 108 ... fixing film (rotating member)
109: Pressure roller (pressure member)
110: Feeding roller (conveying unit)
201 ... heater 202 ... thermistor (temperature detection unit)
203: Memory (storage unit)
205: Control unit 802: Environmental temperature sensor (environment detection unit)
A: Image forming apparatus S: Sheet

Claims (10)

A rotating member,
A heater which generates heat by heating the rotating member by being in contact with the inner surface of the rotating member;
A temperature detection unit that detects the temperature of the heater;
The rotary member is pressed to form a nip portion with the heater via the rotary member, and while the sheet is nipped and conveyed in the nip portion, the developer image on the sheet is heated by the heat of the heater and fixed on the sheet A fixing member having a pressing member,
A relation related to the temperature of the pressure member based on an elapsed time elapsed from the start of application of voltage to the heater and a temperature of the heater detected by the temperature detection unit at the elapsed time A storage unit in which information is stored in advance;
A conveyance unit configured to convey a sheet toward the nip portion of the fixing device;
A control unit that controls the conveyance of the sheet by the conveyance unit;
The control unit predicts the temperature of the pressure member based on the temperature of the heater detected by the temperature detection unit, the elapsed time, and the related information stored in the storage unit. The image forming apparatus, wherein the conveyance of the sheet by the conveyance unit is started when the temperature reaches a threshold. The image forming apparatus further includes an environment detection unit that detects a temperature around the image forming apparatus.
The storage unit further stores a temperature around the fixing device when the related information is measured,
The control unit corrects the temperature of the pressure member predicted by the control unit based on the temperature detected by the environment detection unit and the temperature around the fixing device stored in the storage unit. The image forming apparatus according to claim 1, When the temperature detected by the environment detection unit is lower than the temperature around the fixing device stored in the storage unit, the control unit causes the temperature of the heater detected by the temperature detection unit to be a predetermined value or more. Control to start conveyance of the sheet by the conveyance unit when the
The temperature of the nip when the temperature of the heater reaches the predetermined value is higher than the temperature of the nip when the temperature of the pressure member is predicted to reach the threshold. The image forming apparatus according to claim 2.   The related information includes the temperature of the heater detected by the temperature detection unit in the elapsed time and the measured temperature of the pressing member in the elapsed time before the fixing device is attached to the image forming apparatus. The image forming apparatus according to any one of claims 1 to 3, wherein the image forming apparatus is information created on the basis of and.   The related information is difference information between a temperature of the heater detected by the temperature detection unit at the elapsed time and a measured temperature of the pressing member at the elapsed time. The image forming apparatus according to claim 1.   The related information is the difference information between the temperature of the heater detected by the temperature detection unit and the measured temperature of the pressure member, each time a predetermined time has elapsed since the start of application of a voltage to the heater. The image forming apparatus according to claim 5, wherein the image forming apparatus is provided.   4. The image forming apparatus according to claim 1, wherein the related information is information prepared based on a response speed to the temperature of the temperature detection unit before attaching the fixing device to the image forming apparatus. An image forming apparatus according to any one of the items. The time from when the application of voltage to the heater is started to when the pressing member reaches the target temperature is t1, and the sheet starts to be conveyed to the nip portion of the fixing device after the conveying portion starts conveying the sheet. When the time to reach is t2, let the time calculated from t1-t2 be t3.
The threshold value is a temperature of the pressing member predicted by the control unit using the related information after t3 has elapsed from the start of the application of a voltage to the heater. An image forming apparatus according to any one of 1 to 7.   The image forming apparatus according to any one of claims 1 to 8, wherein the temperature detection unit is a thermistor. A rotating member containing a heater that generates heat when energized;
A temperature detection unit that detects the temperature of the rotating member;
A pressure member that pressurizes the rotating member to form a nip portion with the rotating member, heats a developer image on the sheet by the heat of the heater while nipping and conveying the sheet at the nip portion, and fixes the sheet on the sheet; A fixing device having
It relates to the temperature of the pressing member based on the elapsed time elapsed from the start of the start of the application of the voltage to the heater and the temperature of the rotating member detected by the temperature detecting unit during the elapsed time A storage unit in which related information is stored in advance;
A conveyance unit configured to convey a sheet toward the nip portion of the fixing device;
A control unit that controls the conveyance of the sheet by the conveyance unit;
The control unit predicts the temperature of the pressure member based on the temperature of the heater detected by the temperature detection unit, the elapsed time, and the related information stored in the storage unit. The image forming apparatus, wherein the conveyance of the sheet by the conveyance unit is started when the temperature reaches a threshold.

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