JP2005315990A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize the temperature of a fixing roller within a range of a target temperature by reducing the temperature ripples with respect to the fixing roller of a high temperature elevation rate. <P>SOLUTION: The image forming apparatus comprises a heating means for heating the fixing roller which performs heat fixing, a temperature detection means for detecting the temperature of the fixing roller corresponding to the heating means, and a control means for controlling the electric power supply to the heating means by referring to the detection temperature detected by the temperature detection means and controlling the fixing roller so as to attain a fixing target temperature. The control means starts supplying electric power to the heating means, then stops the power supply upon lapse of the prescribed time even when the detection temperature does not reach the fixing target temperature according to the responsiveness of the temperature detection means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus that heats and fixes a toner image transferred onto a recording medium, and more particularly to improvement in temperature control of a fixing roller of the image forming apparatus.

  Generally, in an electrophotographic image forming apparatus, one surface of an image support is used to thermally fix a toner image transferred to one surface of an image support (recording medium) such as transfer paper to the image support. 2. Description of the Related Art A fixing device is widely used that includes a fixing heating roller in contact with the fixing heating roller and a pressure roller disposed so as to be pressed against the fixing heating roller.

  In a certain type of fixing device, a heater lamp such as a halogen lamp (hereinafter simply referred to as “heater”) or an induction heating type heat source (heating means) is provided in the roller as a heating means of the fixing heating roller. It has been.

  In such a fixing device, a target fixing temperature is set, and power supply to the heating unit is controlled so that the fixing roller reaches the target fixing temperature. For such temperature control, a temperature sensor is disposed in the vicinity of the fixing roller so as to detect the temperature of the fixing roller.

  Note that the temperature sensor has a thermal response characteristic called responsiveness, and does not measure the temperature of the measurement object instantaneously, but has a problem that a measurement result can be obtained after a certain time.

In view of such a responsiveness problem, in Patent Document 1 below, the temperature control of the fixing roller is performed by adding the temperature change rate of the detected temperature, the responsiveness (time constant) of the temperature sensor, and the correction rate. I have to.
JP-A-9-146406 (first page, FIG. 1)

  In the temperature control described in Patent Document 1, correction is not performed when the temperature is equal to or higher than a predetermined temperature. For this reason, overshooting can be suppressed by temperature correction when the temperature is lower than the predetermined temperature (during warm-up), but overshooting is not performed when the temperature is higher than the predetermined temperature (during standby or image formation). Cannot be suppressed, and the error between the actual temperature and the detected temperature increases.

  Note that when a contact thermistor is used as the temperature sensor, the roller may be damaged and the image quality may be adversely affected. On the other hand, when a non-contact thermistor is used, the temperature is indirectly detected, so that the actual temperature cannot be detected and the response is deteriorated.

  In recent years, infrared temperature sensors are sometimes used as non-contact temperature detection means. This infrared temperature sensor is configured to output a temperature detection signal that is a result of detecting infrared rays radiated from a measurement object, and to output a temperature compensation signal that is a result of detecting an ambient temperature. The temperature of the measurement object is calculated from the detection signal and the temperature compensation signal.

  A calculation table (look-up table) for calculating the temperature of the measurement object from the temperature detection signal and the temperature compensation signal is provided by a manufacturer that manufactures the sensor.

  However, when the infrared temperature sensor is used to detect the temperature of the fixing roller having a large temperature change, the infrared radiation radiated from various parts other than the fixing roller increases as the ambient temperature in the apparatus rises. It became clear by experiment of an inventor that an error becomes large.

  As a result of detailed examination by the inventor, when the ambient temperature in the apparatus is lower than the predetermined temperature, the actual temperature (actual temperature) is higher than the detected temperature calculated from the temperature detection signal and the temperature compensation signal. It was found to be about 10 ° C lower. Similarly, when the ambient temperature in the apparatus is higher than the predetermined temperature, it has been found that the actual temperature is about 10 ° C. higher than the detected temperature calculated from the temperature detection signal and the temperature compensation signal (see FIG. 12). .

  In this way, despite the use of the temperature compensation signal, the direction of the error and the magnitude of the error change due to changes in the ambient temperature, so that the fixing roller temperature is stabilized within the target temperature range. It was a very difficult situation.

  The present invention has been made to solve the above-described problems, and its purpose is to detect the temperature detection signal and the temperature compensation signal of the infrared temperature sensor even when the temperature change in the apparatus is large. It is an object of the present invention to provide an image forming apparatus capable of suppressing the difference between the detected temperature calculated by the above and the actual temperature and stabilizing the temperature of the fixing roller within the target temperature range.

The present invention for solving the above problems is as described below.
(1) The invention described in claim 1 is an image forming apparatus for heating and fixing a toner image transferred onto a recording medium, the heating means for heating a fixing roller for heat fixing, and the heating means corresponding to the heating means. With the fixing roller as a measurement object, a temperature detection means for outputting a temperature detection signal that is a result of detecting infrared rays radiated from the measurement object, and for outputting a temperature compensation signal that is a result of detecting the ambient temperature; Temperature calculating means for calculating the temperature of the fixing roller from the temperature detection signal and the temperature compensation signal, and correction means for correcting the temperature of the fixing roller calculated by the temperature calculating means according to the temperature compensation signal. And referring to the temperature of the fixing roller corrected by the correcting unit, the power supply to the heating unit is controlled, and the fixing roller is controlled to reach a predetermined fixing target temperature. And control means that is an image forming apparatus characterized by having a.

  (2) In the invention according to claim 2, the correction unit obtains a correction value by a predetermined correction table or correction formula based on the temperature compensation signal, and the fixing roller calculated by the temperature calculation unit. The image forming apparatus according to claim 1, wherein the correction value is corrected by applying the correction value to the temperature.

  (3) The invention described in claim 3 is an image forming apparatus for heating and fixing a toner image transferred onto a recording medium, the heating means for heating a fixing roller for heat fixing, and the heating means corresponding to the heating means. With the fixing roller as a measurement object, a temperature detection means for outputting a temperature detection signal that is a result of detecting infrared rays radiated from the measurement object, and for outputting a temperature compensation signal that is a result of detecting the ambient temperature; A temperature calculating means for calculating the temperature of the fixing roller from the temperature detection signal and the temperature compensation signal; an ambient temperature detecting means for detecting an end or ambient temperature of the fixing roller or an internal temperature; and the ambient temperature. According to the detection result of the detection means, a correction means for correcting the temperature of the fixing roller calculated by the temperature calculation means, and a temperature of the fixing roller corrected by the correction means. See, by controlling the power supply to the heating means, an image forming apparatus characterized by comprising a control means for controlling so that the fixing roller to a predetermined fixing target temperature.

  (4) According to a fourth aspect of the present invention, the correction means is a correction table determined in advance based on an end portion or ambient temperature of the fixing roller detected by the ambient temperature detection means or a temperature in the apparatus. 4. The image forming apparatus according to claim 3, wherein a correction value is obtained by a correction formula, and correction is performed by applying the correction value to the temperature of the fixing roller calculated by the temperature calculation unit.

  (5) The invention according to claim 5 is characterized in that the correction means has a plurality of correction tables or correction formulas that differ depending on the heat capacity of the heating means, and the control means corresponds to the heat capacity. The correction value that is suitable from the plurality of correction tables or correction formulas, either as a result of detecting the state of the preset setting unit or as a result of detecting the rate of temperature increase during warm-up. 5. The image forming apparatus according to claim 2, wherein the image forming apparatus is selected for calculation.

  (6) The invention according to claim 6 is provided with a plurality of the heating means and a plurality of the temperature detection means corresponding to the heating means, and the control means corresponds to the heating means and the heating means. 6. The image forming apparatus according to claim 1, wherein each of the plurality of temperature detection units is independently controlled to have a predetermined fixing target temperature.

  (7) In the invention according to claim 7, the plurality of heating means are heating means of an electromagnetic induction heating system, and the maximum power usable for heat fixing is generated independently by any of the plurality of heating means. When the maximum power that can be used for heat fixing is supplied to any of the heating means, the control means does not supply power to the other heating means. The image forming apparatus according to claim 6.

According to the present invention, the following effects can be obtained.
(1) According to the first aspect of the present invention, the temperature of the fixing roller is calculated from the temperature detection signal and the temperature compensation signal at the time of image formation in which the toner image transferred onto the recording medium is heated and fixed, and the calculated fixing is performed. The temperature of the roller is corrected according to the temperature compensation signal.

  That is, since the detected temperature calculated from the temperature detection signal and the temperature compensation signal is further corrected according to the temperature compensation signal, even if the temperature change in the apparatus is large, the detected temperature A difference between the actual temperature and the actual temperature is suppressed. As a result, it becomes possible to stabilize the temperature of the fixing roller within the range of the target temperature regardless of the change in the ambient temperature.

  (2) In the invention according to claim 2, the correction means obtains a correction value by a predetermined correction table or correction formula based on the temperature compensation signal, and calculates the correction value to the calculated fixing roller temperature. Apply and correct.

  In other words, the detected temperature calculated from the temperature detection signal and the temperature compensation signal is corrected by applying the correction value obtained from the temperature compensation signal and the correction table or the correction formula. Even when the change is large, the occurrence of a difference between the detected temperature and the actual temperature is effectively suppressed. As a result, it becomes possible to stabilize the temperature of the fixing roller within the range of the target temperature regardless of the change in the ambient temperature.

  (3) In the invention according to claim 3, the temperature of the fixing roller is calculated from the temperature detection signal and the temperature compensation signal at the time of image formation in which the toner image transferred onto the recording medium is heated and fixed. The detecting means detects the temperature of the end or the surrounding of the fixing roller or the temperature inside the apparatus, and corrects the calculated temperature of the fixing roller according to the detection result of the ambient temperature detecting means.

  That is, since the detected temperature calculated from the temperature detection signal and the temperature compensation signal is further corrected according to the detection result of the ambient temperature detection means, even if the temperature change in the apparatus is large The difference between the detected temperature and the actual temperature is suppressed. As a result, it becomes possible to stabilize the temperature of the fixing roller within the range of the target temperature regardless of the change in the ambient temperature.

  (4) In the invention according to claim 4, the correction means is based on a predetermined correction table or a correction equation based on the end or ambient temperature of the fixing roller detected by the ambient temperature detection means or the temperature in the apparatus. A correction value is obtained and the correction value is applied to the calculated temperature of the fixing roller for correction.

  That is, for the detection temperature calculated from the temperature detection signal and the temperature compensation signal, the correction value obtained from the detection result of the ambient temperature detection means and the correction table or the correction formula is applied and corrected. Even when the temperature change in the apparatus is large, the occurrence of a difference between the detected temperature and the actual temperature is effectively suppressed. As a result, it becomes possible to stabilize the temperature of the fixing roller within the range of the target temperature regardless of the change in the ambient temperature.

  (5) In the invention described in claim 5, there are a plurality of different correction tables or correction formulas depending on the heat capacity of the heating means, and the result of detecting the state of the setting unit preset according to the heat capacity Alternatively, a suitable one of a plurality of correction tables or correction equations is selected for correction value calculation based on either the result of detecting the temperature increase rate during warm-up.

  That is, when a correction value is applied to the detected temperature calculated from the temperature detection signal and the temperature compensation signal, a plurality of correction tables or corrections are performed depending on either the setting according to the heat capacity or the temperature increase rate during warm-up. Since the correct value is obtained by selecting a suitable one from the formula, even if the temperature change in the device is large, the correction value can be obtained according to how the temperature change occurs. Thus, the occurrence of a difference between the detected temperature and the actual temperature is extremely effectively suppressed. As a result, it becomes possible to stabilize the temperature of the fixing roller within the range of the target temperature regardless of the change in the ambient temperature.

(6) In the invention described in claim 6, each of the plurality of sets of the heating means and the temperature detection means corresponding to the heating means is controlled independently to have a predetermined fixing target temperature.
In other words, the detection temperature calculated from the temperature detection signal and the temperature compensation signal is further corrected according to the detection result of the ambient temperature, and such calculation and correction are performed independently for each set. Therefore, even when the temperature change in the apparatus is different in each part, the difference between the detected temperature and the actual temperature is suppressed in each part. As a result, the entire fixing roller can be stabilized within the target temperature range.

  (7) In the invention according to claim 7, the plurality of heating means are electromagnetic induction heating (IH) type heating means, and the maximum power that can be used for heat fixing is generated independently by any of the plurality of heating means. When supplying the maximum power that can be used for heating and fixing to any one of the heating means, the power is not supplied to the other heating means. In other words, the maximum power that can be supplied to the fixing roller can be supplied to only one of the plurality of heating units.

  As a result, the temperature of the fixing roller can be stabilized within the target temperature range even if the fixing roller has a partially high temperature rise rate due to heating by the maximum power supply of the electromagnetic induction heating method.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described below in detail with reference to the drawings.
The image forming apparatus of this embodiment is a document reading unit (scanner) even if it is an image output device (copying device) having a function of reading and copying the contents of a copy object as image information by a document reading unit (scanner) The present invention can also be applied to an image output apparatus (printer) that does not have ().

<First Embodiment>
FIG. 1 is a circuit configuration diagram showing a first embodiment of an image forming apparatus of the present invention. In FIG. 1, the periphery of the portion (fixing portion) necessary for the operation description of the present embodiment is mainly described, and other portions known as the image forming apparatus are omitted.

  The image forming apparatus 100 is supplied with electric power from a commercial power supply 10 having an AC (alternating current) of about 100 V or an AC of about 200 V. The AC from the commercial power source is used as it is for a fixing device, and a voltage required inside the apparatus. Is generated and supplied to each part. Note that the voltage and frequency of the commercial power supply 10 may be slightly different for each country (destination) where the image forming apparatus 100 is used.

  Reference numeral 101 denotes a control unit configured by a CPU or the like as a control unit for controlling each unit, and corrects an accurate detection temperature that is not affected by the ambient temperature by referring to the storage contents of the internal storage unit and the detection result of the temperature detection unit. However, the control to be calculated and the control to control the power supply to the heating unit with reference to the corrected temperature to stabilize the temperature of the fixing roller within the target temperature range are performed. That is, the control unit 101 includes a control unit that performs various controls, a temperature calculation unit that calculates the temperature of the fixing roller, and a correction unit that further corrects the calculated temperature of the fixing roller.

  Note that the control unit 101 may be a dedicated control unit that performs control of fixing temperature and control of power supply, or may be used as a control unit that performs various controls of the entire image forming apparatus 100. Good.

  A fixing power source 120 serves as a power source unit that controls power supply to the fixing unit 130, and includes a heater power source 121 that supplies power to the heater 131a and a main relay 123. Here, the heater power supply 121 is an induction heating type power supply means when the heater 131a is an induction heating type heater, and an SSR (solid state relay) when the heater 131a is a lamp type heater. The switching means is configured to be able to control power supply in response to a control signal from the control unit 101. The main relay 123 is configured to be able to control on / off of power supply to the heater power supply 121 in response to a control signal (main relay ON / OFF signal) from the control unit 101.

  Reference numeral 130 denotes a fixing device for thermally fixing the toner image transferred to the transfer paper, and includes a fixing roller 131 that performs heat fixing and a fixing roller 132 that performs pressure fixing.

Inside the fixing roller 131 that performs the heat fixing, a heater 131a is built in as a heating unit that heats the entire fixing roller 131 from the inside.
Further, the fixing unit 130 is provided with a temperature sensor 131as as temperature detecting means for detecting the temperature (detected temperature) of the fixing roller corresponding to the heater 131a in a non-contact manner. The temperature sensor 131as detects the surface temperature of the fixing roller 131 and transmits the detection result to the control unit 101.

  Reference numeral 133 denotes a jumper pin as a setting unit that is preset according to the heat capacity of the fixing unit 130. This jumper pin 133 is mounted at the time of factory shipment. The presence or absence of the jumper pin 133 is detected by the CPU 101a as a voltage change (that is, a heat capacity detection signal) using a pull-up resistor.

  Further, in this image forming apparatus 100, the temperature sensor 131as constitutes a temperature detection means, and a temperature detection signal TD1 which is a result of detecting infrared rays radiated from the measurement object with the fixing roller 131 as a measurement object. In addition to outputting, a temperature compensation signal TC1 which is a result of detecting the ambient temperature is output.

  The control unit 101 includes a buffer amplifier A1 that amplifies the temperature detection signal TD1, a buffer amplifier A2 that amplifies the temperature compensation signal TC1, an amplification signal (A1 output) of the temperature detection signal TD1, and a temperature compensation signal TC1. And a differential amplifier A3 that amplifies a potential difference from the amplified signal (A2 output) to generate a difference signal TF1.

  Here, the output of the buffer amplifier A1, the output of the buffer amplifier A2, the output of the differential amplifier A3, and the heat capacity detection signal are supplied to the input port of the CPU 101a in the control unit 101.

In this case, the buffer amplifier A1, the buffer amplifier A2, the differential amplifier A3, and the CPU 101a constitute the temperature calculation means in the claims.
In such a configuration, the CPU 101a calculates the surface temperature of the fixing roller 131 in a temperature compensated state from the difference signal TF1 corresponding to the potential difference between the temperature detection signal TD1 and the temperature compensation signal TC1. When the surface temperature of the fixing roller 131 is calculated from the temperature detection signal and the temperature compensation signal, the CPU 101a takes the temperature detection signal TD1, the temperature compensation signal TC1, and the difference signal TF1 for a predetermined number of times and averages them. After that, the temperature of the fixing roller 131 is calculated.

  A calculation table (lookup table) for calculating the temperature of the measurement object from the temperature detection signal TD1 (or the difference signal TF1) and the temperature compensation signal TC1 is provided by the manufacturer of the infrared temperature sensor. It is what. For this reason, when an infrared temperature sensor is used to detect the temperature of a fixing roller having a large temperature change, the infrared radiation radiated from various parts other than the fixing roller increases as the ambient temperature in the image forming apparatus and around the fixing roller increases. Thus, it has been found by experiments of the inventors that the error of the infrared temperature sensor becomes large.

  Therefore, in this embodiment, the temperature of the fixing roller calculated using the temperature detection signal TD1 and the temperature compensation signal TC1 is further corrected according to the temperature compensation signal TC1. Thereby, even when the temperature change in the image forming apparatus is large, the difference between the detected temperature and the actual temperature is suppressed.

The operation of the image forming apparatus 100 of the present embodiment configured as described above will be described with reference to the flowchart of FIG. 2 and the temperature control characteristic diagrams of FIGS.
First, when the power SW 102 of the image forming apparatus 100 is turned on, the control unit 101 turns on the main relay 123 to supply power from the heater power supply 121 to the heater 131a, and the temperature control of FIG. Execute the process.

  The control unit 101 takes in the temperature detection signal TD1, the temperature compensation signal TC1, and the difference signal TF1. Note that at least the difference signal TF1 and the temperature compensation signal TC1 may be captured. Hereinafter, in this embodiment, the CPU 101a will be described as capturing the difference signal TF1 and the temperature compensation signal TC1. Further, the CPU 101a performs A / D conversion on the difference signal TF1 and the temperature compensation signal TC1 by an A / D converter (not shown), and takes it as digital data (S1 in FIG. 2).

  In order to minimize the influence of data variation, digital data is acquired for a predetermined number of times for the difference signal TF1 and the temperature compensation signal TC1 and averaged (S2 in FIG. 2).

  Here, the CPU 101a refers to the temperature table in the LUT format stored in the CPU 101a or in an information holding unit (not shown), and performs temperature compensation from the averaged digital data of the difference signal TF1 and the digital data of the temperature compensation signal TC1. The surface temperature TDC of the fixing roller 131 in the completed state is calculated (S3 in FIG. 2).

  Note that the temperature table used at this stage is a standard one provided by the manufacturer that manufactures the infrared temperature sensor 131as. For this reason, the surface temperature TDC of the fixing roller 131 calculated at this stage includes an error (FIG. 12) corresponding to a change in the ambient temperature.

  Then, the CPU 101a refers to the LUT format ambient temperature table (FIG. 3A) stored in the CPU 101a or in an information holding unit (not shown), and calculates the infrared temperature from the digital data of the averaged temperature compensation signal TC1. Data on the ambient temperature in the vicinity of the sensor 131as is obtained (S4 in FIG. 2).

  Further, the CPU 101a refers to an LUT-format correction temperature table (FIG. 3B) stored in the CPU 101a or in an information holding unit (not shown), and acquires data of the correction temperature ΔT from the digital data of the ambient temperature. (FIG. 2S5).

  For example, when the digital data of the temperature compensation signal TC1 is 237, the ambient temperature is 20 ° C. (FIG. 3A). The correction temperature ΔT corresponding to the ambient temperature of 20 ° C. is −6 ° C. (FIG. 3B).

  Here, the correction temperature ΔT is a correction value for correcting an error (FIG. 12) between the detected temperature detected by the infrared temperature sensor 131as and the actual temperature that is the actual temperature. Note that this error is generated according to a change in ambient temperature, as described with reference to FIG.

  Therefore, the correction temperature ΔT is measured in advance according to the error (correction value) that changes according to the heat capacity of the fixing roller, the heater, the image forming apparatus, etc., and the ΔT is calculated as a correction temperature table (FIG. As b)), it may be stored in the CPU 101a or in an information holding unit (not shown).

  As for the correction temperature ΔT, in addition to the correction temperature table in the LUT format, a correction formula for calculating the correction temperature ΔT according to the ambient temperature data can be used. In this case, the correction temperature correction formula may be stored in the CPU 101a or in an information holding unit (not shown).

When the correction temperature ΔT based on the ambient temperature is acquired as described above, the CPU 101a calculates the corrected temperature Tm on which the correction temperature ΔT is applied with reference to the following calculation formula (1) ( FIG. 2S6).
Tm = TDC + ΔT (1),
In this way, when the corrected temperature Tm obtained by applying the correction temperature ΔT is obtained as the surface temperature of the fixing roller 131, the CPU 101a compares the corrected temperature Tm with the target temperature (S7 in FIG. 2), and the heater The control signal is used to control power supply from the heater power supply 121 to the heater 131a (S8 and S9 in FIG. 2), and the fixing roller 131 is controlled to a predetermined fixing target temperature.

  Here, the heater power supply 121 performs induction heating type power supply control when the heater 131a is an induction heating type heater, and performs switching control by SSR when the heater 131a is a lamp type heater.

  As described above, with respect to the detected temperature TDC calculated from the temperature detection signal TD1 (or difference signal TF1) and the temperature compensation signal TC1, the correction temperature ΔT obtained from the temperature compensation signal TC1 and the correction table or correction equation. As shown in FIG. 4, there is a difference between the detected temperature (corrected temperature Tm) and the actual temperature as shown in FIG. Is effectively suppressed.

  As a result, it becomes possible to stabilize the temperature of the fixing roller within the range of the target temperature regardless of the change in the ambient temperature. When the inventor confirmed by experiment, it was found that the error over a total of about 20 ° C. from about −10 ° C. to + 10 ° C., which has conventionally occurred as shown in FIG. 12, was eliminated as shown in FIG.

<Second Embodiment>
In FIG. 12, it has been confirmed by experiments by the inventor that the ambient temperature and the occurrence state of the error according to the ambient temperature change according to the heat capacity of the fixing roller, the heater, the image forming apparatus, or the like. In addition, the voltage and frequency of the commercial power supply 10 are slightly different for each country (destination) where the image forming apparatus 100 is used, and the error generation state corresponding to the ambient temperature changes accordingly.

  Therefore, as shown in FIG. 1, the jumper pin 133 as a setting unit set in advance according to the heat capacity of the fixing unit 130 is configured to be mountable at the time of shipment from the factory, and whether or not the jumper pin 133 is mounted is determined. The CPU 101a is configured to detect a change in voltage (heat capacity detection signal) using a pull-up resistor.

  Further, a plurality of correction temperature tables of the same type as shown in FIG. 3B are stored in the CPU 101a or in an information holding unit (not shown) according to the heat capacity (see FIG. 5). Here, FIG. 5A shows an example of the ambient temperature table, FIG. 5B shows an example of the correction temperature table # 1, and FIG. 5C shows an example of the correction temperature table # 2.

  Then, depending on whether or not the jumper pin 133 is attached, the CPU 101a is suitable from the LUT type correction temperature table (FIG. 5B or FIG. 5C) stored in the CPU 101a or in an information holding unit (not shown). The data of the correction temperature ΔT may be acquired from the digital data of the ambient temperature. Note that by preparing a plurality of n jumper pins 133, it is possible to identify a plurality of 2 ^ n states (a plurality of heat capacities).

  Instead of using the jumper pin 133, the CPU 101a may obtain the rate of temperature increase during warm-up and determine the heat capacity from this rate of temperature increase. In this way, it is possible to flexibly cope with a change in voltage at the destination. It is also possible to cope with an image forming apparatus that can be used with a plurality of voltages.

  As described above, the operation of the image forming apparatus 100 of the present embodiment configured with a plurality of correction temperature tables will be described with reference to the explanatory diagram of the correction temperature table of FIG. 5 and the flowchart of FIG.

  First, when the power SW 102 of the image forming apparatus 100 is turned on, the control unit 101 turns on the main relay 123 to supply power to the heater 131a from the heater power supply 121, and performs temperature control in FIG. Execute the process.

  The control unit 101 takes in the temperature detection signal TD1, the temperature compensation signal TC1, and the difference signal TF1. Note that at least the difference signal TF1 and the temperature compensation signal TC1 may be captured. Hereinafter, in this embodiment, the CPU 101a will be described as capturing the difference signal TF1 and the temperature compensation signal TC1.

  First, when the power SW 102 of the image forming apparatus 100 is turned on, the control unit 101 turns on the main relay 123 to supply power to the heater 131a from the heater power supply 121, and performs temperature control in FIG. Execute the process.

  The control unit 101 takes in the temperature detection signal TD1, the temperature compensation signal TC1, and the difference signal TF1. Here, the CPU 101a performs A / D conversion of the difference signal TF1 and the temperature compensation signal TC1 by an A / D converter (not shown), and takes it in as digital data (S1 in FIG. 6). In order to minimize the influence of data variation, digital data is acquired for a predetermined number of times for the difference signal TF1 and the temperature compensation signal TC1 and averaged (S2 in FIG. 6).

  Here, the CPU 101a refers to the temperature table in the LUT format stored in the CPU 101a or in an information holding unit (not shown), and performs temperature compensation from the averaged digital data of the difference signal TF1 and the digital data of the temperature compensation signal TC1. The surface temperature TDC of the fixing roller 131 in the completed state is calculated (S3 in FIG. 6).

  Note that the temperature table used at this stage is a standard one provided by the manufacturer that manufactures the infrared temperature sensor 131as. Therefore, the surface temperature TDC of the fixing roller 131 calculated at this stage is: An error (FIG. 12) corresponding to a change in ambient temperature is included.

  Then, the CPU 101a refers to the LUT format ambient temperature table (FIG. 5A) stored in the CPU 101a or in an information holding unit (not shown), and calculates the infrared temperature from the digital data of the averaged temperature compensation signal TC1. Data on the ambient temperature in the vicinity of the sensor 131as is obtained (S4 in FIG. 6).

  The CPU 101a checks the state of the heat capacity detection signal, and according to the state (L / H), the LUT type correction temperature table (FIG. 5B or FIG. 5) stored in the CPU 101a or in an information holding unit (not shown). A suitable one is selected from (c)) (S5 in FIG. 6).

  Then, according to the state of the heat capacity detection signal, the CPU 101a refers to the selected correction temperature table # 1 if the detection result is L, and acquires data of the correction temperature ΔT from the digital data of the ambient temperature. (FIG. 6 S6).

  For example, when the digital data of the temperature compensation signal TC1 is 237, the ambient temperature is 20 ° C. (FIG. 5A). The correction temperature ΔT in the correction temperature table # 1 corresponding to the ambient temperature 20 ° C. is −6 ° C. (FIG. 5B).

  Further, the CPU 101a refers to the selected correction temperature table # 2 if the detection result is H in accordance with the state of the heat capacity detection signal, and acquires data of the correction temperature ΔT from the digital data of the ambient temperature. (FIG. 6 S7).

  For example, when the digital data of the temperature compensation signal TC1 is 237, the ambient temperature is 20 ° C. (FIG. 5A). The correction temperature ΔT in the correction temperature table # 2 corresponding to the ambient temperature 20 ° C. is −10 ° C. (FIG. 5C).

  Here, the correction temperature ΔT according to the correction temperature table # 1 is an error (FIG. 12) between the detection temperature detected by the infrared temperature sensor 131as and the actual temperature when the heat capacity detection signal is L. This is a correction value for correction. Further, the correction temperature ΔT according to the correction temperature table # 2 corrects an error (FIG. 12) between the detected temperature detected by the infrared temperature sensor 131as and the actual temperature when the heat capacity detection signal is H. It is a correction value to do. This error is generated according to the change in ambient temperature and the heat capacity.

  As for the correction temperature ΔT, in addition to the correction temperature table in the LUT format, any one of a plurality of correction equations for calculating the correction temperature ΔT according to the ambient temperature data can be used. Also in this case, a plurality of correction formulas may be stored in the CPU 101a or an information holding unit (not shown) as the correction temperature correction formula.

  As described above, when the correction temperature ΔT based on the ambient temperature is acquired, the CPU 101a refers to the above-described calculation formula (Tm = TDC + ΔT) and calculates the corrected temperature Tm on which the correction temperature ΔT is applied. (S8 in FIG. 6).

  In this way, when the corrected temperature Tm obtained by applying the corrected temperature ΔT referred to from the corrected temperature table selected according to the heat capacity is obtained as the surface temperature of the fixing roller 131, the CPU 101a corrects the corrected temperature Tm. And the target temperature (FIG. 6 S9), the heater control signal is used to control the power supply from the heater power supply 121 to the heater 131a (FIG. 6 S10, S11), and the fixing roller 131 reaches the predetermined fixing target temperature. To control.

  As a result, when the correction value is applied to the detected temperature calculated from the temperature detection signal and the temperature compensation signal, a plurality of correction tables or a plurality of correction tables are set by either setting according to the heat capacity or the temperature increase rate during warm-up. Since the correction value is determined by selecting a suitable correction formula, even if the temperature change in the device is large, the correction value can be calculated according to how the temperature change occurs. Thus, the difference between the detected temperature and the actual temperature is extremely effectively suppressed. As a result, it becomes possible to stabilize the temperature of the fixing roller within the range of the target temperature regardless of the change in the ambient temperature.

<Third Embodiment>
FIG. 7 is a circuit configuration diagram showing a third embodiment of the image forming apparatus of the present invention. In FIG. 7, the periphery of the portion (fixing portion) necessary for the explanation of the operation of the present embodiment is mainly described, and other portions known as the image forming apparatus are omitted. The same components as those in FIG. 1 are denoted by the same reference numerals.

  In addition to the configuration shown in FIG. 1, a contact thermistor 134 that detects the temperature at the end of the fixing roller while being in contact with the fixing unit 130 is disposed in the fixing unit 130. The contact thermistor 134 detects the surface temperature of the end portion of the fixing roller 131 and transmits the detection result to the control unit 101.

  The control unit 101 includes a buffer amplifier A1 that amplifies the temperature detection signal TD1, a buffer amplifier A2 that amplifies the temperature compensation signal TC1, an amplification signal (A1 output) of the temperature detection signal TD1, and a temperature compensation signal TC1. In addition to the differential amplifier A3 that amplifies the potential difference with the amplified signal (A2 output) to generate the difference signal TF1, there is a buffer amplifier A7 that amplifies the end temperature detection signal TH1 that is the detection result of the contact thermistor 134. doing.

  Here, the output of the buffer amplifier A1, the output of the buffer amplifier A2, the output of the differential amplifier A3, the buffer amplifier A7, and the heat capacity detection signal are supplied to the input port of the CPU 101a inside the control unit 101.

The operation of the image forming apparatus 100 of the present embodiment configured as described above will be described with reference to the flowchart of FIG. 8 and the explanatory diagram of the table of FIG.
First, when the power SW 102 of the image forming apparatus 100 is turned on, the control unit 101 turns on the main relay 123 to supply power to the heater 131a from the heater power supply 121, and the temperature control of FIG. Execute the process.

  The control unit 101 takes in the difference signal TF1, the temperature compensation signal TC1, and the end temperature detection signal TH1. Here, the CPU 101a uses an A / D converter (not shown) to A-D convert the difference signal TF1, the temperature compensation signal TC1, and the end temperature detection signal TH1 into digital data (S1 in FIG. 8). In order to minimize the influence of data variation, digital data is taken in a predetermined number of times for the difference signal TF1, the temperature compensation signal TC1, and the end temperature detection signal TH1 and averaged (S2 in FIG. 8). ).

  Here, the CPU 101a refers to the temperature table in the LUT format stored in the CPU 101a or in an information holding unit (not shown), and performs temperature compensation from the averaged digital data of the difference signal TF1 and the digital data of the temperature compensation signal TC1. The surface temperature TDC of the fixing roller 131 in the state thus obtained is calculated (S3 in FIG. 8).

  Note that the temperature table used at this stage is a standard one provided by the manufacturer that manufactures the infrared temperature sensor 131as. For this reason, the surface temperature TDC of the fixing roller 131 calculated at this stage includes an error (FIG. 12) corresponding to a change in the ambient temperature.

  Then, the CPU 101a refers to the LUT format ambient temperature table (FIG. 9A) stored in the CPU 101a or in an information holding unit (not shown), and calculates the averaged end temperature detection signal TH1 from the digital data. Data on the ambient temperature in the vicinity of the contact thermistor 134 is obtained (S4 in FIG. 8).

  Further, the CPU 101a refers to an LUT-format correction temperature table (FIG. 9B) stored in the CPU 101a or in an information holding unit (not shown), and acquires data of the correction temperature ΔT from the digital data of the ambient temperature. (FIG. 8 S5).

  For example, when the digital data of the temperature compensation signal TH1 is 248, the ambient temperature is 20 ° C. (FIG. 9A). The correction temperature ΔT in the correction temperature table # 2 corresponding to the ambient temperature of 20 ° C. is −10 ° C. (FIG. 9B).

  Here, the correction temperature ΔT is a correction value for correcting an error (FIG. 12) between the detected temperature detected by the infrared temperature sensor 131as and the actual temperature that is the actual temperature. Note that this error is generated according to a change in ambient temperature, as described with reference to FIG.

  Therefore, the correction temperature ΔT is measured in advance according to the error (correction value) that changes according to the heat capacity of the fixing roller, the heater, the image forming apparatus, etc., and the ΔT is measured using the LUT-type correction temperature table (FIG. 9 ( As b)), it may be stored in the CPU 101a or in an information holding unit (not shown).

  As for the correction temperature ΔT, in addition to the correction temperature table in the LUT format, a correction formula for calculating the correction temperature ΔT according to the ambient temperature data can be used. In this case, the correction temperature correction formula may be stored in the CPU 101a or in an information holding unit (not shown).

  As described above, when the correction temperature ΔT based on the ambient temperature is acquired, the CPU 101a refers to the above-described calculation formula (Tm = TDC + ΔT) and calculates the corrected temperature Tm on which the correction temperature ΔT is applied. (S6 in FIG. 8).

  In this way, when the corrected temperature Tm obtained by applying the correction temperature ΔT as the surface temperature of the fixing roller 131 is obtained, the CPU 101a compares the corrected temperature Tm with the target temperature (S7 in FIG. 8), and the heater The control signal is used to control power supply from the heater power supply 121 to the heater 131a (S8 and S9 in FIG. 8), and the fixing roller 131 is controlled to a predetermined fixing target temperature.

  Here, the heater power supply 121 performs induction heating type power supply control when the heater 131a is an induction heating type heater, and performs switching control by SSR when the heater 131a is a lamp type heater.

  As described above, the detected temperature TDC calculated from the temperature detection signal TD1 (or the difference signal TF1) and the temperature compensation signal TC1 is corrected from the end temperature detection signal TH1 and the correction table or the correction formula. Since the temperature ΔT is applied and corrected, as shown in FIG. 4, even if the temperature change in the apparatus is large, there is a difference between the detected temperature (corrected temperature Tm) and the actual temperature. Is effectively suppressed. As a result, the temperature of the fixing roller can be stabilized within the target temperature range regardless of the change in the end temperature (ambient temperature) of the fixing roller 131.

  In the third embodiment, as in the second embodiment, a plurality of correction temperature tables corresponding to the heat capacity are prepared in advance, and the state of the heat capacity detection signal or the temperature increase rate is referred to. The correction temperature table for acquiring the correction temperature ΔT may be selected. Also in this case, the correction value is obtained according to how the temperature change occurs, and the occurrence of a difference between the detected temperature and the actual temperature is extremely effectively suppressed. As a result, it becomes possible to stabilize the temperature of the fixing roller within the range of the target temperature regardless of changes in the ambient temperature.

<Fourth Embodiment>
In the above-described FIG. 7 (third embodiment), in addition to the configuration shown in FIG. 1 (first embodiment), the fixing unit 130 is brought into contact with the end temperature of the fixing roller as ambient temperature detecting means. A contact thermistor 134 that detects the above is disposed. The contact thermistor 134 detects the surface temperature of the end portion of the fixing roller 131 and supplies an end portion temperature detection signal TH1 to the CPU 101a. Further, as in the third embodiment, the temperature compensation signal TC1 is also supplied to the CPU 101a.

  Therefore, in the fourth embodiment, in the image forming apparatus having the configuration shown in FIG. 7, the CPU 101a selects one of the temperature compensation signal TC1 and the end temperature detection signal TH1, so that a predetermined correction table or The correction temperature ΔT is obtained by a correction formula.

  For this purpose, an ambient temperature table # 1 for obtaining the ambient temperature from the temperature compensation signal TC1 and an ambient temperature table # 2 for obtaining the ambient temperature from the end temperature detection signal TH1 are provided. Further, the correction temperature table # 1 for acquiring the correction temperature ΔT from the ambient temperature detected by the temperature compensation signal TC1, and the correction for acquiring the correction temperature ΔT from the ambient temperature detected by the end temperature detection signal TH1. And a temperature table # 2. Note that correction equation # 1 may be prepared instead of correction temperature table # 1, and correction equation # 2 may be prepared instead of correction temperature table # 2.

  The CPU 101a refers to the heat capacity detection signal or the temperature rise rate during warm-up, and determines whether to use the temperature compensation signal TC1 or the end temperature detection signal TH1 for obtaining the correction temperature ΔT (S10 in FIG. 10).

  When it is determined to use the temperature compensation signal TC1, the control unit 101 takes in the temperature detection signal TD1, the temperature compensation signal TC1, and the difference signal TF1. Here, the CPU 101a performs A / D conversion of the difference signal TF1 and the temperature compensation signal TC1 by an A / D converter (not shown), and takes it in as digital data (S11 in FIG. 10). In order to minimize the influence of data variation, digital data is acquired for a predetermined number of times for the difference signal TF1 and the temperature compensation signal TC1 and averaged (S12 in FIG. 10).

  Here, the CPU 101a refers to the temperature table in the LUT format stored in the CPU 101a or in an information holding unit (not shown), and performs temperature compensation from the averaged digital data of the difference signal TF1 and the digital data of the temperature compensation signal TC1. The surface temperature TDC of the fixing roller 131 in the state thus obtained is calculated (S13 in FIG. 10).

  Note that the temperature table used at this stage is a standard one provided by the manufacturer that manufactures the infrared temperature sensor 131as. Therefore, the surface temperature TDC of the fixing roller 131 calculated at this stage is: An error (FIG. 12) corresponding to a change in ambient temperature is included.

  The CPU 101a refers to the LUT format ambient temperature table # 1 stored in the CPU 101a or in an information holding unit (not shown), and calculates the ambient temperature in the vicinity of the infrared temperature sensor 131as from the digital data of the temperature compensation signal TC1 averaged. Data is obtained (S14 in FIG. 10).

  Further, the CPU 101a refers to the LUT-type correction temperature table # 1 stored in the CPU 101a or in an information holding unit (not shown), and acquires data of the correction temperature ΔT from the digital data of the ambient temperature (S15 in FIG. 10).

  Here, the correction temperature ΔT based on the correction temperature table # 1 is a correction value for correcting an error (FIG. 12) between the detected temperature detected by the infrared temperature sensor 131as and the actual temperature. As for the correction temperature ΔT, in addition to the correction temperature table in the LUT format, it is also possible to use the correction equation # 1 in which the correction temperature ΔT is calculated according to the ambient temperature data. Also in this case, the correction temperature correction formula # 1 may be stored in the CPU 101a or in an information holding unit (not shown).

  As described above, when the correction temperature ΔT based on the ambient temperature is acquired, the CPU 101a refers to the above-described calculation formula (Tm = TDC + ΔT) and calculates the corrected temperature Tm on which the correction temperature ΔT is applied. (S16 in FIG. 10).

  In this way, when the corrected temperature Tm obtained by applying the correction temperature ΔT referred to from the correction temperature table # 1 selected according to the determination of the CPU 101a is obtained as the surface temperature of the fixing roller 131, the CPU 101a The corrected temperature Tm is compared with the target temperature (S17 in FIG. 10), power supply from the heater power supply 121 to the heater 131a is controlled using the heater control signal (S18, S19 in FIG. 10), and the fixing roller 131 is fixed to a predetermined level. Control to reach the target temperature.

  If it is determined by the CPU 101a (S10 in FIG. 10) that the end temperature detection signal TH1 is used, the control unit 101 takes in the difference signal TF1, the temperature compensation signal TC1, and the end temperature detection signal TH1. Here, the CPU 101a converts the difference signal TF1, the temperature compensation signal TC1, and the end temperature detection signal TH1 into digital data by A / D conversion using an A / D converter (not shown) (S21 in FIG. 10). In order to minimize the influence of data variations, digital data is taken in a predetermined number of times for the difference signal TF1, the temperature compensation signal TC1, and the end temperature detection signal TH1 and averaged (S22 in FIG. 10). ).

  Here, the CPU 101a refers to the temperature table in the LUT format stored in the CPU 101a or in an information holding unit (not shown), and performs temperature compensation from the averaged digital data of the difference signal TF1 and the digital data of the temperature compensation signal TC1. The surface temperature TDC of the fixing roller 131 in the state thus obtained is calculated (S23 in FIG. 10).

  Note that the temperature table used at this stage is a standard one provided by the manufacturer that manufactures the infrared temperature sensor 131as. For this reason, the surface temperature TDC of the fixing roller 131 calculated at this stage includes an error (FIG. 12) corresponding to a change in the ambient temperature.

  Then, the CPU 101a refers to the LUT format ambient temperature table # 2 stored in the CPU 101a or in an information holding unit (not shown), and calculates the vicinity of the contact thermistor 134 from the digital data of the averaged end temperature detection signal TH1. Is obtained (S24 in FIG. 10).

  Further, the CPU 101a refers to the LUT-format correction temperature table # 2 stored in the CPU 101a or in an information holding unit (not shown), and acquires data of the correction temperature ΔT from the digital data of the ambient temperature (S25 in FIG. 10).

  Here, the correction temperature ΔT according to the correction temperature table # 2 is a correction value for correcting an error (FIG. 12) between the detected temperature detected by the infrared temperature sensor 131as and the actual temperature. Note that this error occurs according to a change in ambient temperature, as described with reference to FIG.

  Therefore, the correction temperature ΔT is measured in advance according to the error (correction value) that changes according to the heat capacity of the fixing roller, the heater, the image forming apparatus, etc., and the ΔT is used as the correction temperature table # 2 in the LUT format. It may be stored in the CPU 101a or in an information holding unit (not shown). As for the correction temperature ΔT, in addition to the correction temperature table in the LUT format, it is also possible to use a correction equation # 2 in which the correction temperature ΔT is calculated according to ambient temperature data. Also in this case, the correction temperature correction formula # 2 may be stored in the CPU 101a or in an information holding unit (not shown).

  As described above, when the correction temperature ΔT based on the ambient temperature is acquired, the CPU 101a refers to the above-described calculation formula (Tm = TDC + ΔT) and calculates the corrected temperature Tm on which the correction temperature ΔT is applied. (S26 in FIG. 10).

  In this way, when the corrected temperature Tm obtained by applying the correction temperature ΔT referred to from the correction temperature table # 2 selected according to the determination of the CPU 101a is obtained as the surface temperature of the fixing roller 131, the CPU 101a The corrected temperature Tm is compared with the target temperature (S27 in FIG. 10), the power supply from the heater power supply 121 to the heater 131a is controlled using the heater control signal (S28, S29 in FIG. 10), and the fixing roller 131 is fixed to a predetermined level. Control to reach the target temperature.

  As described above, the detected temperature TDC calculated from the temperature detection signal TD1 (or the difference signal TF1) and the temperature compensation signal TC1 is obtained from the temperature compensation signal TC1 and the correction table # 1 or the correction equation # 1. Since the correction temperature ΔT or the correction temperature ΔT obtained from the end temperature detection signal TH1 and the correction table # 2 or the correction equation # 2 is applied and corrected, the temperature change in the apparatus is large. Even in this case, the occurrence of a difference between the detected temperature (corrected temperature Tm) and the actual temperature is effectively suppressed. As a result, the temperature of the fixing roller can be stabilized within the target temperature range regardless of the change in the end temperature (ambient temperature) of the fixing roller 131.

  As a result, when the correction value is applied to the detected temperature calculated from the temperature detection signal and the temperature compensation signal, a plurality of correction tables or a plurality of correction tables are set by either setting according to the heat capacity or the temperature increase rate during warm-up. Since the correction value is determined by selecting a suitable correction formula, even if the temperature change in the device is large, the correction value can be calculated according to how the temperature change occurs. Therefore, the difference between the detected temperature and the actual temperature is extremely effectively suppressed. As a result, it becomes possible to stabilize the temperature of the fixing roller within the range of the target temperature regardless of changes in the ambient temperature.

  In the fourth embodiment, a plurality of correction temperature tables corresponding to the heat capacity can be prepared in advance as in the second embodiment. That is, a plurality of correction temperature tables # 11 / # 12 are provided for the correction temperature table # 1, and a plurality of correction temperature tables # 21 / # 22 are provided for the correction temperature table # 2. Then, a plurality of correction temperature tables are selected with reference to the state of the heat capacity detection signal or the temperature increase rate. Also in this case, the correction value is obtained according to how the temperature change occurs, and the occurrence of a difference between the detected temperature and the actual temperature is extremely effectively suppressed. As a result, it becomes possible to stabilize the temperature of the fixing roller within the range of the target temperature regardless of changes in the ambient temperature.

<Fifth Embodiment>
FIG. 11 is a circuit configuration diagram showing a fifth embodiment of the image forming apparatus of the present invention. In FIG. 11, as in FIGS. 1 and 7, a part (fixing unit) necessary for describing the operation of this embodiment is shown, and other known parts are omitted.

  In this image forming apparatus 100, as different parts from the first embodiment, a first heater power supply 121 that supplies power to the first heater 131a and a second heater power supply 122 that supplies power to the second heater 131b are provided. Have.

  Here, the first heater power source 121 and the second heater power source 122 are induction heating type power supply means when the first heater 131a and the second heater 131b are induction heating type heaters. When the 131a and the second heater 131b are lamp type heaters, they are switching means such as SSR (Solid State Relay) so that the power supply can be controlled by receiving a control signal from the control unit 101. It is configured.

  Further, in the fixing roller 131, a first heater 131 a as a first heating unit that heats the central portion of the fixing roller 131, and a second heating unit that heats an end portion of the sheet passing area of the fixing roller 131. A heater 131b is built in.

  Further, the fixing unit 130 includes a first infrared temperature sensor 131as as a first temperature detecting unit that detects the temperature (first detection temperature) of the center of the fixing roller corresponding to the first heater 131a in a non-contact manner, and a second temperature sensor 131as. A second infrared temperature sensor 131bs is disposed as a second temperature detection unit that detects the temperature (second detection temperature) of the end of the fixing roller corresponding to the heater 131b in a non-contact manner. Note that the first infrared temperature sensor 131as and the second infrared temperature sensor 131bs have equivalent responsiveness. The first infrared temperature sensor 131as and the second infrared temperature sensor 131bs detect the surface temperature of the fixing roller 131 and transmit the detection result to the control unit 101.

  The first infrared temperature sensor 131as detects an infrared ray radiated from the fixing roller 131 and outputs a temperature detection signal TD1. The first infrared temperature sensor 131as detects the ambient temperature of the infrared temperature sensor and performs a temperature compensation signal TC1. Is configured to output. Similarly, the second infrared temperature sensor 131bs detects the infrared radiation radiated from the fixing roller 131 and outputs a temperature detection signal TD2, and also detects the ambient temperature of the infrared temperature sensor and performs temperature compensation on the temperature compensation signal TC2. Are output.

  In the control unit 101, a buffer amplifier A1 that amplifies the temperature detection signal TD1, a buffer amplifier A2 that amplifies the temperature compensation signal TC1, and a potential difference between the temperature detection signal TD1 and the temperature compensation signal TC1 is amplified and differenced. And a differential amplifier A3 that generates the signal TF1.

  Similarly, the controller 101 amplifies the potential difference between the buffer amplifier A4 that amplifies the temperature detection signal TD2, the buffer amplifier A5 that amplifies the temperature compensation signal TC2, and the temperature detection signal TD2 and the temperature compensation signal TC2. And a differential amplifier A6 that generates a difference signal TF2.

  Here, the output of the buffer amplifier A1, the output of the buffer amplifier A2, the output of the differential amplifier A3, the output of the buffer amplifier A4, the output of the buffer amplifier A5, and the output of the differential amplifier A6 are input to the CPU 101a in the control unit 101. Being supplied to the port. In this case, the buffer amplifier A1, the buffer amplifier A2, the differential amplifier A3, the buffer amplifier A4, the buffer amplifier A5, the differential amplifier A6, and the CPU 101a constitute the temperature calculation means in the claims.

  In such a configuration, the CPU 101a calculates the surface temperature TDC1 of the central portion of the fixing roller 131 in a temperature compensated state from the difference signal TF1 corresponding to the potential difference between the temperature detection signal TD1 of the infrared temperature sensor 131as and the temperature compensation signal TC1. To do. Note that the temperature table used at this stage is a standard one provided by the manufacturer that manufactures the infrared temperature sensor 131as. For this reason, the surface temperature TDC1 at the center of the fixing roller 131 calculated at this stage includes an error corresponding to a change in the ambient temperature of the infrared temperature sensor 131as.

  The CPU 101a refers to an LUT format ambient temperature table stored in the CPU 101a or in an information holding unit (not shown), and obtains ambient temperature data in the vicinity of the infrared temperature sensor 131as from the digital data of the temperature compensation signal TC1.

  Further, the CPU 101a refers to the LUT-type correction temperature table stored in the CPU 101a or in an information holding unit (not shown), and from the digital data of the ambient temperature of the infrared temperature sensor 131as, the correction temperature ΔT1 for the central portion of the fixing roller 131. Get the data.

  Here, the correction temperature ΔT1 is a correction value for correcting an error between the detected temperature at the center of the fixing roller 131 detected by the infrared temperature sensor 131as and the actual temperature.

  Accordingly, the correction temperature ΔT1 is measured in advance according to the error (correction value) that changes according to the heat capacity of the fixing roller, the heater, the image forming apparatus, etc., and the ΔT1 is used as a correction temperature table in the LUT format. Alternatively, it may be stored in an information holding unit (not shown).

  As for the correction temperature ΔT1, in addition to the correction temperature table in the LUT format, it is also possible to use a correction formula for calculating the correction temperature ΔT according to the ambient temperature data. In this case, the correction temperature correction formula may be stored in the CPU 101a or in an information holding unit (not shown).

  As described above, when the correction temperature ΔT1 based on the ambient temperature is acquired, the CPU 101a refers to the above-described calculation formula (Tm1 = TDC1 + ΔT1) and calculates the corrected temperature Tm1 on which the correction temperature ΔT1 is applied. To do.

  Thus, when the corrected temperature Tm1 obtained by applying the correction temperature ΔT1 is obtained as the surface temperature of the central portion of the fixing roller 131, the CPU 101a compares the corrected temperature Tm1 with the target temperature, and determines the heater control signal. Is used to control the power supply from the heater power supply 121 to the heater 131a to control the central portion of the fixing roller 131 to a predetermined fixing target temperature.

  Here, the heater power supply 121 performs induction heating type power supply control when the heater 131a is an induction heating type heater, and performs switching control by SSR when the heater 131a is a lamp type heater.

  Further, in such a configuration, the CPU 101a has the surface temperature TDC2 at the end of the fixing roller 131 in a state where the temperature is compensated from the difference signal TF2 corresponding to the potential difference between the temperature detection signal TD2 of the infrared temperature sensor 131bs and the temperature compensation signal TC2. Is calculated. The temperature table used at this stage is a standard table provided by a manufacturer that manufactures the infrared temperature sensor 131bs. For this reason, the surface temperature TDC2 at the end of the fixing roller 131 calculated at this stage includes an error corresponding to a change in the ambient temperature of the infrared temperature sensor 131bs.

  The CPU 101a refers to an LUT format ambient temperature table stored in the CPU 101a or in an information holding unit (not shown), and obtains ambient temperature data near the infrared temperature sensor 131bs from the digital data of the temperature compensation signal TC2.

  Further, the CPU 101a refers to a correction temperature table in the LUT format stored in the CPU 101a or in an information holding unit (not shown), and from the digital data of the ambient temperature of the infrared temperature sensor 131bs, the correction temperature ΔT2 for the end of the fixing roller 131. Get the data.

  Here, the correction temperature ΔT2 is a correction value for correcting an error between the detected temperature at the end of the fixing roller 131 detected by the infrared temperature sensor 131bs and the actual temperature.

  Therefore, the correction temperature ΔT2 is measured in advance according to the error (correction value) that changes according to the heat capacity of the fixing roller, the heater, the image forming apparatus, etc., and the ΔT2 is used as a correction temperature table in the LUT format. Alternatively, it may be stored in an information holding unit (not shown).

  As for the correction temperature ΔT2, in addition to the correction temperature table in the LUT format, it is also possible to use a correction formula for calculating the correction temperature ΔT according to the ambient temperature data. In this case, the correction temperature correction formula may be stored in the CPU 101a or in an information holding unit (not shown).

  As described above, when the correction temperature ΔT2 based on the ambient temperature is acquired, the CPU 101a refers to the above-described calculation formula (Tm2 = TDC2 + ΔT2) and calculates the corrected temperature Tm2 on which the correction temperature ΔT2 is applied. To do.

  Thus, when the corrected temperature Tm2 obtained by applying the correction temperature ΔT2 is obtained as the surface temperature of the end portion of the fixing roller 131, the CPU 101a compares the corrected temperature Tm2 with the target temperature, and determines the heater control signal. Is used to control the power supply from the heater power supply 121 to the heater 131a, so that the end of the fixing roller 131 is controlled to a predetermined fixing target temperature.

  Here, the heater power supply 121 performs induction heating type power supply control when the heater 131a is an induction heating type heater, and performs switching control by SSR when the heater 131a is a lamp type heater.

  As described above, since the correction by the correction temperature ΔT1 and the correction temperature ΔT2 is performed independently, even if the temperature change in the apparatus is different in each part, the detected temperature and the actual temperature are different in each part. It is suppressed that a difference arises between temperature. As a result, the entire fixing roller can be stabilized within the target temperature range.

<Other embodiments>
The first heater 131a and the second heater 131b in the fifth embodiment described above can use an induction heating (IH) type heat source (heating means) in addition to a heater lamp such as a halogen lamp. When an induction heating type heat source is used, the first heater power supply 121 and the second heater power supply 122 use induction heating type power supply means.

  In this case, the maximum power (for example, 1000 W) that can be used for heat fixing can be generated independently on either side of the first heater 131a and the second heater 131b. In this case, when supplying the maximum power (1000 W) that can be used for heat fixing to one of the first heater 131a and the second heater 131b, the control unit 101 supplies power to the other. Control to not. However, as in the conventional case, the first heater 131a and the second heater 131b can also supply power, such as 500W and 500W.

  Such a configuration (1000W + 0W, 0W + 1000W) is equivalent to having a heat source with a capacity twice as large as that of the conventional 500W + 500W, resulting in a higher rate of temperature rise. Although there are concerns about the occurrence of this problem, by applying the above embodiment, even if the fixing roller has a high temperature rise rate due to heating by the maximum power supply of the electromagnetic induction heating method, the temperature ripple is reduced and the fixing roller It becomes possible to stabilize the temperature within the range of the target temperature.

1 is a configuration diagram illustrating a configuration of an image forming apparatus according to a first exemplary embodiment of the present invention. 3 is a flowchart illustrating an operation of the image forming apparatus according to the first exemplary embodiment of the present invention. FIG. 6 is a characteristic diagram illustrating an example of an image forming apparatus table according to the first embodiment of this invention. FIG. 6 is a characteristic diagram illustrating a temperature operation of the image forming apparatus according to the first exemplary embodiment of the present invention. It is a characteristic view which shows an example of the table of the image forming apparatus of the 2nd Embodiment of this invention. 6 is a flowchart illustrating an operation of the image forming apparatus according to the second exemplary embodiment of the present invention. It is a block diagram which shows the structure of the image forming apparatus of the 3rd Embodiment of this invention. 10 is a flowchart illustrating an operation of an image forming apparatus according to a third exemplary embodiment of the present invention. It is a characteristic view which shows an example of the table of the image forming apparatus of the 4th Embodiment of this invention. 10 is a flowchart illustrating an operation of an image forming apparatus according to a fourth exemplary embodiment of the present invention. It is a block diagram which shows the structure of the image forming apparatus of the 5th Embodiment of this invention. FIG. 10 is a temperature characteristic diagram showing the operation of a conventional image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 AC power supply 100 Image forming apparatus 101 Control part (a control means, a temperature calculation means, a correction means)
DESCRIPTION OF SYMBOLS 120 Fixing power supply part 121 1st heater power supply 122 2nd heater power supply 123 Main relay 130 Fixing part 131 Fixing roller 131a 1st heater (heating means)
131b Second heater (heating means)
131as first temperature sensor (temperature detection means)
131bs second temperature sensor (temperature detection means)
132 Fixing roller

Claims (7)

An image forming apparatus for heating and fixing a toner image transferred onto a recording medium,
Heating means for heating a fixing roller for performing heat fixing;
Using the fixing roller corresponding to the heating unit as a measurement object, a temperature detection signal that is a result of detecting infrared rays radiated from the measurement object is output, and a temperature compensation signal that is a result of detecting an ambient temperature is output. Temperature detecting means for outputting;
Temperature calculating means for calculating the temperature of the fixing roller from the temperature detection signal and the temperature compensation signal;
Correction means for correcting the temperature of the fixing roller calculated by the temperature calculation means in response to the temperature compensation signal;
Control means for controlling the power supply to the heating means with reference to the temperature of the fixing roller corrected by the correcting means and controlling the fixing roller to a predetermined fixing target temperature;
An image forming apparatus comprising: The correction means obtains a correction value by a predetermined correction table or correction formula based on the temperature compensation signal, and corrects the correction roller by applying the correction value to the temperature of the fixing roller calculated by the temperature calculation means. I do,
The image forming apparatus according to claim 1. An image forming apparatus for heating and fixing a toner image transferred onto a recording medium,
Heating means for heating a fixing roller for performing heat fixing;
Using the fixing roller corresponding to the heating means as a measurement object, a temperature detection signal that is a result of detecting infrared rays emitted from the measurement object is output, and a temperature compensation signal that is a result of detecting the ambient temperature is output. Temperature detecting means for outputting;
Temperature calculating means for calculating the temperature of the fixing roller from the temperature detection signal and the temperature compensation signal;
An ambient temperature detecting means for detecting an end or ambient temperature of the fixing roller or a temperature in the apparatus;
A correction unit that corrects the temperature of the fixing roller calculated by the temperature calculation unit according to a detection result of the ambient temperature detection unit;
Control means for controlling the power supply to the heating means with reference to the temperature of the fixing roller corrected by the correction means and controlling the fixing roller to a predetermined fixing target temperature;
An image forming apparatus comprising: The correction means obtains a correction value by a predetermined correction table or a correction formula based on the end or ambient temperature of the fixing roller or the temperature in the apparatus detected by the ambient temperature detection means, and calculates the temperature. Correction is performed by applying the correction value to the temperature of the fixing roller calculated by the means.
The image forming apparatus according to claim 3. The correction means has a plurality of correction tables or correction formulas that are different depending on the heat capacity of the heating means,
The control means is configured to detect the plurality of correction tables or correction formulas based on either a result of detecting a state of a setting unit set in advance according to the heat capacity or a result of detecting a temperature increase rate during warm-up. Selecting a suitable one for the correction value calculation,
The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus. A plurality of the heating means and the temperature detection means corresponding to the heating means are provided,
The control unit controls each of a plurality of the heating unit and the temperature detection unit corresponding to the heating unit to independently reach a predetermined fixing target temperature.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The plurality of heating means are heating means of an electromagnetic induction heating system, and are configured to be capable of generating the maximum power that can be used for heat fixing alone in any of the plurality of heating means,
The control means does not supply power to other heating means when supplying the maximum power usable for heat fixing to any of the heating means,
The image forming apparatus according to claim 6.

Images