JP2006220939A - Image forming apparatus and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus detecting a temperature of a fixing roller at good precision even when the distance between a temperature sensor and a fixing roller is varied due to expansion of the fixing roller or deviation, etc., of the fixing roller in the image forming apparatus detecting the temperature of the fixing roller using a non contact temperature sensor in which an error occurs in a detected result due to variation in the distance from an object to be measured. <P>SOLUTION: In the image forming apparatus, the variation of a fixing roller diameter is obtained from an average rotating speed of a motor in the case where the motor rotating speed of the motor driving the roller is adjusted so that the paper is transported at a specified transporting speed even when the diameter in the fixing roller is varied, and from the result, the variation in the distance between the non contact temperature sensor measuring the temperature of the fixing roller and the fixing roller is obtained, and the temperature detection result by the non contact temperature sensor is compensated. An equalization process is carried out to cancel any periodical change of output in the non contact temperature sensor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus and a control method thereof, for example, an electrophotographic image forming apparatus and a control method thereof.

  FIG. 11 includes image forming means for four colors, that is, yellow (hereinafter referred to as Y), magenta (hereinafter referred to as M), cyan (hereinafter referred to as C), and black (hereinafter referred to as K). FIG. 1 shows a color image forming apparatus. In FIG. 1, reference numeral 1 denotes a photosensitive drum for forming an electrostatic latent image (a, b, c, d are for Y, M, C, K, respectively), and 6 is each It is a motor that drives the photosensitive drum.

  2 is a laser scanner that performs exposure according to an image signal to form an electrostatic latent image on the photosensitive drum 1, 3 is an endless conveyance belt that sequentially conveys paper to an image forming unit of each color, 4 is a motor, A driving roller connected to driving means such as a gear and driving the conveying belt 3, a motor 6 e for driving the driving roller 4, a fixing device for melting and fixing the toner transferred onto the paper, and a fixing roller 9. is there.

  When data to be printed is sent from the PC to the printer and image formation according to the system of the printer engine is completed and the printer is ready, the paper is supplied from the paper cassette and reaches the conveyance belt 3. Each color is sequentially conveyed to the image forming unit. The image signals of the respective colors are sent to the laser scanners 2 in synchronism with the conveyance of the paper by the conveyance belt 3, and an electrostatic latent image is formed on the photosensitive drum 3, and the electrostatic latent image is converted into toner by a developing device (not shown). And is transferred onto a sheet by a transfer unit (not shown). In the figure, images are sequentially formed in the order of Y, M, C, and K. Thereafter, the paper is separated from the conveying belt 3, and the toner image is fixed on the paper by the fixing device 5 by heat and discharged to the outside.

  Further, the Y, M, and C photosensitive drums 1a to 1c and the conveying belt 3 can be switched between a contact state and a separation state by an actuator (not shown). In the monochrome mode in which only black is printed, the Y, M, and C photosensitive drums 1a to 1c and the conveyance belt 3 are separated from each other, and the Y, M, and C photosensitive drums 1a to 1c and the developing devices for the respective colors are driven. Without being performed, the Y, M, and C photosensitive drums 1a to 1c and the developing devices for the respective colors are prevented from being deteriorated and consumed.

  By the way, in the multi-color image forming apparatus configured as described above, the temperature of the fixing roller 9 is measured by a temperature sensor and put into the fixing roller 9 in order to keep the temperature of the fixing device 5 at a desired value. The power to be adjusted.

As a temperature measurement method, there are a method of using a thermistor in contact with a fixing roller, and a method of using a non-contact type temperature sensor such as a thermopile in order to prevent damage to the surface of the fixing roller (see, for example, Patent Document 1). ).
Japanese Patent No. 3478761

  However, the conventional temperature measuring method has the following problems.

  There are various types of non-contact temperature sensors such as those using a thermopile and those using a thermistor.

  On the other hand, the fixing roller uses a material such as rubber on the surface of the fixing roller. As the temperature of the fixing roller rises, the diameter of the fixing roller expands, and the distance between the sensor and the surface of the fixing roller changes.

  Further, the distance between the sensor and the surface of the fixing roller periodically changes due to the eccentricity of the fixing roller and the shaft that supports the fixing roller, the deviation of the fixing roller from the perfect circle, and the like.

  Therefore, in order to accurately measure the surface temperature of the fixing roller, it is necessary to use a sensor that is hardly affected by the temperature detection result even if the distance between the sensor and the surface of the fixing roller changes.

  For example, in the case of a thermopile, even if the distance between the sensor and the surface of the fixing roller is changed, the temperature detection result is hardly affected, but the price of the sensor is relatively expensive, resulting in an increase in product cost.

  As a relatively inexpensive non-contact temperature sensor, one using a thermistor can be cited, but there has been a problem that the temperature detection result varies greatly depending on the distance to the object to be measured and an error occurs in the temperature detection result.

  The present invention has been made in view of such problems, and even if a non-contact temperature sensor such as a thermistor system in which the detection result changes depending on the distance between the sensor and the measured object is used. Another object of the present invention is to provide an image forming apparatus capable of accurately detecting the temperature of the fixing roller and a control method therefor.

  SUMMARY An advantage of some aspects of the invention is that the image forming apparatus has the following configuration.

  A fixing unit driven by a driving unit; a fixing unit configured to fix an unfixed toner image on a transfer material by heat; a heating unit configured to heat the fixing unit; and a temperature of the fixing unit in contact with the fixing unit. Non-contact temperature detection means for detecting temperature, temperature detection result correction means for correcting the temperature detection result of the non-contact temperature detection means, and electric power input to the heating means according to the temperature detected by the non-contact temperature detection means A temperature control means for controlling the transfer material, a conveyance means for conveying the transfer material, a deflection amount detection means for detecting a deflection amount of the transfer material between the fixing means and the conveyance means located upstream thereof, and An image forming apparatus comprising: a driving speed adjusting unit that adjusts a driving speed of the driving unit; and the non-contact temperature detecting unit according to a change in a distance between the non-contact temperature detecting unit and the fixing roller. Image forming apparatus and correcting a result of temperature detection.

  Further, with respect to the periodic output fluctuation of the non-contact temperature detecting means caused by the periodic change of the distance between the non-contact temperature detecting means and the fixing member, the output of An image forming apparatus characterized in that a sampling period is set short and an averaging process is performed on temperature data corresponding to an integer period of the output fluctuation period.

  According to the present invention, an image forming apparatus capable of accurately detecting the temperature of the fixing roller even when using a non-contact temperature sensor such as a thermistor system whose detection result changes depending on the distance between the sensor and the measured object. And a control method thereof.

  Hereinafter, an embodiment of an image processing apparatus to which the present invention is applied will be described in detail with reference to the drawings.

  The configuration of the image forming apparatus according to Embodiment 1 of the present invention is the same as that shown in FIG. In the figure, the temperature sensor is corrected according to the present invention. Since other configurations and operations are the same as those of the conventional example, the description thereof is omitted.

  FIG. 2 shows a schematic configuration of the control system of this apparatus.

  Reference numeral 10 denotes a printer as an image forming apparatus. A printer control unit 11 controls each device in the printer. A power source 12 supplies power to each device in the printer. Reference numeral 13 denotes sensors for detecting the status of each unit in the printer. A motor control unit 14 controls the motors according to instructions from the printer control unit 11. Reference numeral 15 denotes motors which are power sources of the respective devices in the printer. Reference numeral 16 denotes a display unit that notifies the user of the operation status of the printer. A communication controller 17 communicates between the printer and the host computer. A host computer 18 transfers data to be printed to the printer.

  1, 3, 4, and 5 show a configuration of a main part according to the present invention.

  In FIG. 1, 14 is a motor control unit, 40 is a DC brushless motor, 30 is a driver for controlling power to the motor, and 9 is a fixing roller driven by the motor. The fixing roller 9 has a diameter of 50 mm when the roller temperature is 25 ° C., and has a maximum diameter of about 50.6 to 50.8 mm when the roller temperature is 150 ° C.

  The motor control unit 14 is equipped with a DSP 20 (FIG. 3). The DSP 20 controls the phase switching by the rotor position signal from the DC brushless motor 40, starts and stops the motor by the control signal from the printer control unit 11, and compares the speed signal from the printer control unit 11 with the output of the speed detection means. Then, speed control is performed via the driver 30.

  In FIG. 4, reference numeral 8 denotes a non-contact temperature sensor, which is connected to the printer control unit 11.

  The temperature sensor 8 is a non-contact temperature sensor using a thermistor. The temperature sensor is installed at a position 1.5 mm away from the surface of the fixing roller when the fixing roller has a diameter of 50 mm.

  FIG. 12 shows changes in the temperature detection result depending on the distance between the temperature sensor and the fixing roller surface when the fixing roller having a surface temperature of 150 ° C. is measured. Note that the temperature detection result in this case is the temperature reached by the thermistor, and is a value lower than the roller surface temperature of 150 ° C.

  As can be seen from the figure, if the maximum diameter of the fixing roller is 50.8 mm, the temperature sensor-fixing roller surface distance is reduced by 0.4 mm, so that the temperature detection result is about 8 ° C. higher.

  A block diagram of the DSP 20 is shown in FIG.

  21 is a program controller, 22 is an arithmetic unit for performing addition / subtraction, logical operation, and product-sum operation, 23 is a data memory, 24 is a program memory, 25 is a data memory bus, 26 is a program memory bus, 27 is a serial port, 28 Is a timer and 29 is an I / O port. As described above, the memory is made independent for data and the program, the bus is separated into the data bus and the program bus, and the arithmetic unit for executing multiplication and addition in one machine cycle is provided, thereby enabling high-speed operation.

  As shown in FIG. 3, the DC brushless motor 40 has a coil 43 and a rotor 44 that are three-phase star connection of U, V, and W. Further, three Hall elements 42 for detecting the magnetic poles of the rotor 44 are provided as position detecting means for the rotor 44, and their outputs are connected to the DSP 20. Further, it has a rotational speed detecting means comprising a magnetic pattern 45 and a magnetic sensor 41 provided on the outer periphery of the rotor 44, and its output is connected to the DSP 20.

  Reference numeral 30 denotes a driver for driving the DC brushless motor 40, which includes three high-side transistors 31 and three low-side transistors 32, and is connected to U, V, and W of the coil 43, respectively.

  The DSP 20 specifies the position of the rotor based on the rotor position signals HU to W generated by the Hall element 42 and generates a phase switching signal. The phase switching signals UU to W and LU to W sequentially turn on and off the transistors 31 and 32 of the driver 30 and sequentially switch the phases to be excited to rotate the rotor.

  Furthermore, in order to perform speed control, the DSP 20 compares the rotational speed target value with the rotational speed information to obtain speed error information. The motor operation amount is calculated from the speed error information, and the phase switching signals UU to W are output as PWM signals according to the result. The drive current is chopped in accordance with the DUTY of the PWM signal to control the rotation speed of the motor.

  Further, the DSP 20 sequentially samples the rotational speed information and calculates an average rotational speed for a predetermined period.

  Next, operations of the motor control unit 14 and the printer control unit 11 will be described.

  When the printer control unit 11 instructs to start all the motors in order to execute image formation, the motor control unit 14 performs speed control on each motor and accelerates it to a predetermined rotational speed. Is controlled so as to maintain a predetermined rotational speed.

  In this embodiment, it is assumed that the rotation speed of the fixing motor is switched to two stages. Further, the speed target value of the fixing motor immediately after the motor is started is set so that the peripheral speed of the fixing roller 9 is smaller than the conveying speed of the image forming unit even when the fixing roller 9 is thermally expanded. Accordingly, when printing is started and the sheet enters the fixing roller 9, the conveyance speed by the fixing roller 9 is slower than the conveyance speed of the image forming unit, so that the sheet is bent and the loop amount between the image forming unit and the fixing device (deflection). Quantity). This speed target value is set as speed target value 1.

  Next, the loop sensor 7 is monitored. It is assumed that the loop sensor 7 outputs analog or multivalued digital data that changes according to the loop amount.

  When it is detected that the loop amount exceeds a predetermined value, the speed target value of the fixing motor is set so that the peripheral speed of the fixing roller 9 is larger than the transport speed. That is, the deflection of the paper is eliminated and the loop amount is reduced. This speed target value is set as speed target value 2.

  Further, when it is detected that the loop amount is equal to or less than a predetermined value, the speed target value of the fixing motor is switched to the speed target value 1, and the above operation is repeatedly executed until the paper passes through the fixing device. FIG. 6 schematically shows the above state.

  During this time, the rotation speed of the fixing motor is sampled, and the average rotation speed for a predetermined period is calculated. Upon receiving a fixing motor average speed transmission command from the printer control unit 11, the motor control unit 14 notifies the printer control unit 11 of the average speed of the fixing motor.

  The printer control unit 11 as temperature detection result correction means calculates a change in the fixing roller diameter based on the average speed of the fixing motor notified from the motor control unit 14, and detects the detection of the fixing roller temperature sensor 8 based on the result. Correct the result.

  That is, the fixing roller 9 is determined based on the ratio of the reference fixing motor rotation speed (the fixing motor rotation speed at which the peripheral speed of the fixing roller 9 when not expanded corresponds to the conveying speed of the image forming unit) and the average speed. Is calculated, and a change in the distance between the temperature sensor 8 and the fixing roller 9 is obtained. Then, the temperature detection result of the temperature sensor 8 is corrected by the change in the distance between the temperature sensor 8 and the fixing roller 9. For correction, a change in the temperature detection result when the distance between the temperature sensor 8 and the fixing roller 9 is changed is obtained in advance and stored as a table of distance versus correction amount, and the temperature detection result is stored according to the table. to correct.

  Alternatively, the temperature detection result may be corrected using an arithmetic expression representing a change in the temperature detection result when the distance between the temperature sensor 8 and the fixing roller 9 is changed instead of the table. In addition, the temperature detection result can be corrected using a table of the relationship between the average speed and the temperature detection error or an arithmetic expression.

  For example, when the reference fixing motor rotation speed is 1500 rpm and the average speed is 1482 rpm, the change of the roller diameter is 50 × 1500/1482 = 50.6. Therefore, assuming that the distance between the sensor and the roller is reduced by 0.3 mm, the sensor temperature detection result is corrected by 6.5 ° C. lower than the relationship shown in FIG.

  Next, a method for canceling fluctuations in the temperature sensor output caused by periodic changes in the distance between the temperature sensor and the fixing roller due to eccentricity of the fixing roller and the shaft that supports the fixing roller, deviation from the perfect circle of the fixing roller, etc. explain. This operation is performed by the printer controller 11 as temperature detection result correction means.

  First, the sampling period of the temperature sensor output is set to be shorter than the fluctuation period of the temperature sensor output. For example, it is preferable to set the sampling period to an integer period such as 1/5 or 1/10 of the temperature sensor output fluctuation period.

  Then, an averaging process is performed on the number of data that is an integral multiple of one period of the fixing roller.

  For example, when the motor rotation speed is 1500 rpm, the fixing roller rotation speed is 1 rps, and the output of the temperature sensor is generated in synchronization with the rotation of the fixing roller, the fluctuation cycle of the temperature sensor is 1 s, so the sampling period is 100 ms, An averaging process is performed on 10 pieces of continuous temperature data. This is shown in FIG.

  Further, when the motor rotation speed is set to, for example, 750 rpm in the cardboard printing mode or the like, the sampling cycle is set to 200 ms, and averaging processing is performed on 10 pieces of continuous temperature data. Alternatively, an averaging process may be performed on 20 pieces of continuous temperature data with a sampling period of 100 ms.

  As described above, the change in the diameter of the fixing roller 9 is obtained and the detection result of the fixing roller temperature sensor 8 is corrected, thereby correcting the error in the temperature detection result due to the change in the distance between the fixing roller and the temperature sensor, The temperature control of the fixing roller can be accurately performed.

  In addition, the fluctuation of the temperature detection result caused by the periodic change of the distance between the temperature sensor and the fixing roller due to the eccentricity of the fixing roller and the shaft supporting the fixing roller, the deviation from the perfect circle of the fixing roller, etc. is canceled, and fixing Roller temperature control can be performed with high accuracy.

  A second embodiment of the present invention will be described.

  FIG. 8 shows a schematic configuration of the control system of this apparatus.

  A motor control unit 14 is equipped with a DSP as in the first embodiment. In order to perform speed control, the DSP compares the rotational speed target value with the rotational speed information to obtain speed error information. The motor operation amount is calculated from the speed error information, and the rotational speed of the motor is controlled.

  The DSP monitors the time during which the speed target value for each level has been set, and calculates the ratio of the time during which the speed target value for each level has been set.

  Since the configuration of the image forming apparatus of this apparatus is the same as that of the first embodiment, description thereof is omitted. Moreover, the same code | symbol is attached | subjected to the same structure.

  Hereinafter, operations of the motor control unit 14 and the printer control unit 11 will be described.

  When the printer control unit 11 instructs to start all the motors in order to execute image formation, the motor control unit 14 performs speed control on each motor and accelerates it to a predetermined rotational speed. Is controlled so as to maintain a predetermined rotational speed. At this time, the target speed value of the fixing motor is set so that the peripheral speed of the fixing roller 9 is smaller than the conveying speed. That is, when the sheet enters the fixing roller, the sheet is bent and the loop amount between the image forming unit and the fixing unit increases. This speed target value is set as speed target value 1.

  Next, the loop sensor 7 is monitored, and when it is detected that the loop amount exceeds a predetermined value, the speed target value of the fixing motor 9 is set so that the peripheral speed of the fixing roller is larger than the conveyance speed. That is, the deflection of the paper is eliminated and the loop amount is reduced. This speed target value is set as speed target value 2.

  Further, when it is detected that the loop amount is equal to or less than a predetermined value, the speed target value of the fixing motor is switched to the speed target value 1, and the above operation is repeatedly executed until the paper passes through the fixing device.

  During this period, the sum of the value obtained by integrating the speed target value 1 during the period set for the speed target value 1 and the value obtained by integrating the speed target value 2 during the period set for the speed target value 2. Is calculated.

  That is, it can be seen that the smaller the integrated value of the speed target value 1 and the speed target value 2, the larger the fixing roller diameter.

  Alternatively, a result obtained by multiplying each set period by a coefficient corresponding to the ratio between the speed target value 1 and the speed target value 2 and summing them may be used.

  FIG. 9 schematically shows the above state. FIG. 9A shows the operation when the fixing roller diameter is not expanded, and FIG. 9B shows the operation when the fixing roller diameter is expanded.

  Upon receiving the fixing motor target set time ratio transmission command from the printer control unit 11, the motor control unit 14 notifies the printer control unit 11 of the target set time ratio of the fixing motor.

  The printer control unit 11 calculates a change in the fixing roller diameter based on the target setting time ratio of the fixing motor notified from the motor control unit 14, and corrects the detection result of the fixing roller temperature sensor 8 from the result.

  That is, the change in the diameter of the fixing roller 9 is calculated from the reference value and the target setting time ratio, and the change in the distance between the temperature sensor 8 and the fixing roller 9 is obtained. Then, the temperature detection result of the temperature sensor 8 is corrected by the change in the distance between the temperature sensor 8 and the fixing roller 9. For correction, a change in the temperature detection result when the distance between the temperature sensor 8 and the fixing roller 9 is changed is obtained in advance and stored as a table of distance versus correction amount, and the temperature detection result is stored according to the table. to correct.

  Alternatively, the temperature detection result may be corrected using an arithmetic expression representing a change in the temperature detection result when the distance between the temperature sensor 8 and the fixing roller 9 is changed instead of the table. In addition, the temperature detection result can be corrected using a table of the relationship between the average speed and the temperature detection error or an arithmetic expression.

  For example, when the ratio between the speed target value 1 and the speed target value 2 is 0.9: 1.1 and the fixing roller 9 is not expanded, the speed target value 1 is repeated every 200 ms and the speed target value 2 is repeated every 200 ms. When the peripheral speed matches the conveyance speed of the image forming unit, the reference value is set to 0.9 × 200 + 1.1 × 200 = 400. If the speed target value 1 is repeated 220 ms and the speed target value 2 is repeated every 180 ms when the fixing roller 9 expands, the integrated value of the target speeds 1 and 2 is 0.9 × 220 + 1.1 × 180. = 396. Therefore, the change in roller diameter is 50 × 400/396 = 50.5. Therefore, assuming that the distance between the sensor and the roller is reduced by 0.25 mm, the sensor temperature detection result is corrected by 5.3 ° C. lower than the relationship shown in FIG.

  As described above, the change in the diameter of the fixing roller 9 is obtained, and the detection result of the fixing roller temperature sensor 8 is corrected, thereby correcting the error in the temperature detection result due to the change in the distance between the fixing roller 9 and the temperature sensor 8. In addition, the temperature control of the fixing roller 9 can be performed with high accuracy.

  Since the method for canceling the periodic fluctuation of the temperature sensor output is the same as that of the first embodiment, the description thereof is omitted.

  A third embodiment of the present invention will be described.

  Since the image forming apparatus configuration and the schematic configuration of the control system of this apparatus are the same as those of the first embodiment, the description thereof is omitted. Moreover, the same code | symbol is attached | subjected to the same structure.

  Hereinafter, operations of the motor control unit 14 and the printer control unit 11 will be described.

  When the printer control unit 11 instructs to start all the motors in order to execute image formation, the motor control unit 14 performs speed control on each motor and accelerates it to a predetermined rotational speed. Is controlled so as to maintain a predetermined rotational speed. At this time, the target speed value of the fixing motor is set so that the peripheral speed of the fixing roller 9 is smaller than the conveying speed. That is, when the sheet enters the fixing roller 9, the sheet is bent, and the loop amount between the image forming unit and the fixing unit increases. The speed target value at this time is set as speed target value 1.

  Next, the loop sensor 7 is monitored. It is assumed that the output of the loop sensor 7 has binary values of H and L according to the loop amount.

  When the loop amount exceeds a predetermined value, the output of the loop sensor 7 switches to, for example, H, and when a predetermined time has elapsed, the speed target value of the fixing motor is set so that the peripheral speed of the fixing roller 9 is greater than the conveying speed. To do. That is, the deflection of the paper is eliminated and the loop amount is reduced. The speed target value at this time is set as speed target value 2.

  Further, when the loop amount becomes equal to or less than the predetermined value, the output of the loop sensor 7 is switched to L, and a predetermined time has elapsed, the speed target value of the fixing motor is switched to the speed target value 1, and Repeat the operation. FIG. 10 schematically shows the above state. The delay time in the figure represents “elapse of a predetermined time” in the above description.

  During this time, the rotation speed of the fixing motor is sampled, and the average rotation speed for a predetermined period is calculated. Upon receiving a fixing motor average speed transmission command from the printer control unit 11, the motor control unit 14 notifies the printer control unit 11 of the average speed of the fixing motor.

  The printer control unit 11 calculates a change in the fixing roller diameter based on the average speed of the fixing motor notified from the motor control unit 14, and corrects the detection result of the fixing roller temperature sensor 8 based on the result.

  That is, the change in the diameter of the fixing roller 9 is calculated from the ratio between the reference fixing motor rotation speed and the average speed, and the change in the distance between the temperature sensor 8 and the fixing roller 9 is obtained. Then, the temperature detection result of the temperature sensor 8 is corrected by the change in the distance between the temperature sensor 8 and the fixing roller 9. For correction, a change in the temperature detection result when the distance between the temperature sensor 8 and the fixing roller 9 is changed is obtained in advance and stored as a table of distance versus correction amount, and the temperature detection result is stored according to the table. to correct.

  Alternatively, the temperature detection result may be corrected using an arithmetic expression representing a change in the temperature detection result when the distance between the temperature sensor 8 and the fixing roller 9 is changed instead of the table. In addition, the temperature detection result can be corrected using a table of the relationship between the average speed and the temperature detection error or an arithmetic expression.

  As described above, the change in the diameter of the fixing roller 9 is obtained, and the detection result of the fixing roller temperature sensor 8 is corrected, thereby correcting the error in the temperature detection result due to the change in the distance between the fixing roller 9 and the temperature sensor 8. In addition, the temperature control of the fixing roller 9 can be performed with high accuracy.

  Since the method for canceling the periodic fluctuation of the temperature sensor output is the same as that of the first embodiment, the description thereof is omitted.

The figure explaining the structure of the principal part of Example 1. 1 is a diagram illustrating a schematic configuration of a control system for an image forming apparatus according to an embodiment of the present invention. The figure explaining the structure of the principal part of Example 1. The figure explaining the structure of the principal part of Example 1. The figure explaining the structure of the principal part of Example 1. The figure explaining operation | movement of Example 1. FIG. The figure explaining operation | movement of Example 1. FIG. The figure explaining the structure of the principal part of Example 2. The figure explaining operation | movement of Example 2. The figure explaining operation | movement of Example 2. The figure explaining operation | movement of Example 3. The figure explaining the whole image forming apparatus Diagram explaining characteristics of non-contact temperature sensor

Explanation of symbols

3 Conveying belt (corresponding to conveying means)
5 Fixing device (corresponding to fixing means)
7 Loop sensor (corresponding to deflection amount detection means)
8 Temperature sensor (supports non-contact temperature detection means)
9 Fixing roller (corresponding to fixing member)
11 Printer control unit (corresponding to temperature detection result correction means)
14 Motor controller (corresponding to drive speed adjustment means)
20 DSP
40 DC brushless motor (corresponding to drive means)

Claims (12)

Conveying means for conveying a transfer material onto which an unfixed toner image has been transferred;
A fixing unit having a fixing member and fixing the unfixed toner image on the transfer material by heat;
Driving means for driving the fixing member;
Heating means for heating the fixing member;
Non-contact temperature detecting means for detecting the temperature of the fixing member in a non-contact manner with the fixing member;
Temperature detection result correction means for correcting the temperature detection result of the non-contact temperature detection means;
Temperature control means for controlling the electric power supplied to the heating means according to the temperature detected by the non-contact temperature detecting means;
A deflection amount detecting unit for detecting a deflection amount of the transfer material between the fixing unit and the conveying unit located upstream thereof;
Driving speed adjusting means for adjusting the driving speed of the driving means;
An image forming apparatus comprising:
The image forming apparatus, wherein the temperature detection result correction unit corrects a temperature detection result of the non-contact temperature detection unit according to a change in a distance between the non-contact temperature detection unit and the fixing member.   The image forming apparatus according to claim 1, wherein the driving speed adjusting unit adjusts a driving speed of the driving unit so that a deflection amount of the transfer material is constant.   3. The drive speed adjusting unit according to claim 1, wherein the drive speed adjustment unit switches and adjusts the drive speed of the drive unit in at least two stages or more so that the amount of deflection of the transfer material is constant. Image forming apparatus.   4. The image forming apparatus according to claim 1, wherein a change in the distance between the non-contact temperature detection unit and the fixing member is obtained from an amount of change in the diameter of the fixing member.   The image forming apparatus according to claim 4, wherein the amount of change in the diameter of the fixing member is obtained from an average driving speed of the driving unit.   The image forming apparatus according to claim 4, wherein the amount of change in the diameter of the fixing member is obtained from the length of time at each stage of the driving speed adjusted by the driving speed adjusting unit and the driving speed.   The temperature detection result correcting unit is configured to change the output with respect to the periodic output variation of the non-contact temperature detecting unit caused by a periodic change in the distance between the non-contact temperature detecting unit and the fixing member. 7. The image forming apparatus according to claim 1, wherein the output sampling period is set shorter than the output period.   The temperature detection result correcting means causes a change in temperature data with respect to a periodic output fluctuation of the non-contact temperature detecting means caused by a periodic change in the distance between the non-contact temperature detecting means and the fixing member. The averaging process is performed on n × integer number of data when the number of data of the non-contact temperature detecting means for one cycle is n. An image forming apparatus according to claim 1.   9. The image forming apparatus according to claim 1, wherein the driving unit is a DC motor.   The image forming apparatus according to claim 9, wherein the DC motor is driven and controlled by digital signal processing.   The image forming apparatus according to claim 10, wherein the digital signal processing is performed using a DSP or a microcomputer. Conveying means for conveying a transfer material onto which an unfixed toner image has been transferred;
A fixing unit having a fixing member and fixing the unfixed toner image on the transfer material by heat;
Driving means for driving the fixing member;
Heating means for heating the fixing member;
Non-contact temperature detecting means for detecting the temperature of the fixing member in a non-contact manner with the fixing member;
Temperature detection result correction means for correcting the temperature detection result of the non-contact temperature detection means;
Temperature control means for controlling the electric power supplied to the heating means according to the temperature detected by the non-contact temperature detecting means;
A deflection amount detecting unit for detecting a deflection amount of the transfer material between the fixing unit and the conveying unit located upstream thereof;
Driving speed adjusting means for adjusting the driving speed of the driving means;
An image forming apparatus control method comprising:
A method for controlling an image forming apparatus, comprising: correcting a temperature detection result of the non-contact temperature detecting unit according to a change in a distance between the non-contact temperature detecting unit and the fixing member.