JP5595541B2 - Heating device - Google Patents

Description

  The embodiment described in this specification relates to a technique for controlling the temperature of a heat roller in a heating device such as a fixing device that fixes an unfixed toner image on a sheet by heating and pressing.

  In the electrophotographic image forming apparatus, the temperature control of the fixing device is performed by detecting the temperature of the outer peripheral surface of the heat roller in a non-contact manner using a non-contact temperature detecting means and controlling the temperature to a predetermined fixing temperature by the control unit.

  It has been proposed to measure the surface temperature of the heat roller using an inexpensive non-contact thermistor instead of an expensive thermopile as the non-contact temperature detecting means (Patent Document 1).

  The non-contact thermistor may cause a decrease in temperature detection accuracy due to the influence of the gap with the surface of the heat roller to be measured and the ambient temperature as compared with the thermopile, and may not be able to perform high-precision temperature control. Further, depending on the attachment state of the non-contact thermistor, the gap with the surface of the heat roller may vary, and the heat roller may not be accurately controlled.

JP 2009-175538 A

  An object of the present invention is to provide a heating device capable of controlling the temperature of a heat roller with high accuracy using a non-contact thermistor as a main thermistor.

  The heating device according to the embodiment relates to a heating device that heats a toner image on a sheet that is passed through a nip portion between a heating member and a pressure member.

The heating device includes a heating source that heats the heating member, a non-contact thermistor that is disposed with a gap between the heating member and detects the temperature of the heating member, and the heating member that contacts the heating member. A contact thermistor that detects the temperature of the contact temperature, and the temperature of the contact thermistor is used for temperature control from the start-up to the target temperature, and when the target temperature is exceeded, the detected temperature of the non-contact thermistor is used to perform the heating A control unit that controls a source and controls the heating member to a predetermined temperature, a detection temperature correction unit that obtains in advance a correction amount for the detected temperature of the non-contact thermistor by comparison with the detected temperature of the contact thermistor, and a heating device Ambient temperature detection means for detecting the ambient temperature, and an ambient temperature for further correcting the correction amount obtained by the detected temperature correction unit based on the ambient temperature detected by the ambient temperature detection means A correction unit, wherein the peripheral temperature correction unit includes a correction time ambient temperature detected by the ambient temperature detecting means when determined the correction amount, at the ambient temperature detecting means at the time of start-up of the heating device A peripheral correction amount for further correcting the correction amount is obtained based on the detected startup ambient temperature .

The figure which shows schematic structure of embodiment which applied the heating apparatus to the fixing device. The figure which shows the arrangement position of the non-contact thermistor and the contact thermistor with respect to the heat roller of FIG. The circuit block diagram of a control part. The flowchart which shows the flow of the correction process by the control part of FIG. The coefficient calculation chart which calculates | requires the coefficient a from the relationship between the corrected amount shown in Table 1, and the ambient temperature at the time of correction | amendment.

  Hereinafter, a heating device will be described based on an embodiment shown in the drawings.

  1 is a diagram showing a schematic configuration of an embodiment in which a heating device is applied to a fixing device, FIG. 2 is a diagram showing an arrangement position of a non-contact thermistor and a contact thermistor with respect to the heat roller of FIG. 1, and FIG. FIG. 4 is a flowchart showing a flow of correction processing by the control unit of FIG.

  1 and 2, a fixing device 1 is disposed in an image forming apparatus main body (not shown), and fixes an unfixed toner image on a sheet by heating and pressing. In the fixing device 1, a fixing roller (heat roller) 3 as a heating member and a pressure roller (press roller) 5 as a pressure member are in pressure contact with each other by pressure means (not shown), and both rollers are in pressure contact. The sheet on which the unfixed toner image is transferred is passed through the nip portion. The heat roller 3 is heated by energizing a heating source 7 such as a halogen lamp accommodated in a hollow portion. The heat roller 3 and the press roller 5 are driven by a roller drive motor (not shown).

  A first non-contact thermistor 9 and a second non-contact thermistor 11 are arranged with a predetermined gap so as to face the outer peripheral surface of the heat roller 3, and detect the temperature of the outer peripheral surface of the heat roller 3. The first non-contact thermistor 9 is disposed at the center of the heat roller 3 in the length direction, and the second non-contact thermistor 11 is disposed at one end of the maximum sheet passing area of the sheet. Further, the contact thermistor 13 is brought into contact with the outer peripheral surface of the heat roller 3 to detect the temperature of the outer peripheral surface of the heat roller 3. The contact thermistor 13 is disposed at the other end in the length direction of the heat roller 3 on the side opposite to the position where the second non-contact thermistor 11 is disposed, and is disposed outside the other end of the maximum sheet passing area of the sheet. Has been.

  By disposing the first non-contact thermistor 9 and the second non-contact thermistor 11 in the sheet passing area, formation of contact marks by the thermistor on the outer surface of the heat roller 3 is prevented, and fixing by the contact marks is performed. The influence on the image is eliminated. The toner adhering to the outer peripheral surfaces of the heat roller 3 and the press roller 5 is peeled off by the peeling claw 15.

  The control unit 20 illustrated in FIG. 3 includes a processing unit (CPU) 21 that performs energization control to the heating source 7 and a memory 22. The memory 22 is, for example, a semiconductor memory, and includes a ROM (Read Only Memory) that stores various control programs, and a RAM (Random Access Memory) that provides a temporary work area for the processing unit 21. In the ROM, a flowchart of processing shown in FIG. 4 to be described later, a correction table in consideration of the ambient temperature shown in Table 1, a coefficient calculation chart for obtaining the coefficient a from the relationship between the correction amount and the ambient temperature at the time of correction shown in FIG. The thermistor switching table shown in Table 2 is stored.

  The controller 20 outputs temperature detection signals detected by the first non-contact thermistor 9, the second non-contact thermistor 11, and the contact thermistor 13, respectively. Further, an ambient temperature detection signal detected by the ambient temperature detection sensor 23 provided in the image forming apparatus main body is output, and a power-on signal (start-up signal) from the power switch 27 is output.

  Furthermore, the control unit 20 performs drive control of the heating source 7 and the roller drive motor 25.

  In the present embodiment, the first non-contact thermistor 9 and the second non-contact thermistor 11 are used as main thermistors, and the contact thermistor 13 is used for correcting the main thermistor and as a sub-thermistor.

  In this embodiment, before the image forming apparatus including the fixing device 1 is delivered to the user, the temperature of the first non-contact thermistor 9 and the second non-contact thermistor 11 that are main thermistors is corrected. This temperature correction is performed by calling up a correction mode from the memory 22 of the control unit 20 and based on the flowchart shown in FIG. This correction is performed for the first non-contact thermistor 9 and the second non-contact thermistor 11, the assumed temperature of the outer peripheral surface of the heat roller 3 at the arrangement position, the first non-contact thermistor 9 and the second non-contact thermistor 11. The correction value is determined by the difference from the detected temperature of the contact thermistor 11.

  Specifically, the heating source 7 is energized and controlled so that the temperature detected by the contact thermistor 13 is maintained at a predetermined temperature. At this time, a difference between the temperature of the temperature detection portion of the heat roller 3 detected by the first non-contact thermistor 9 and the detected temperature detected by the first non-contact thermistor 9 becomes a correction value. This process will be described below with reference to the flowchart of FIG. TE is a temperature detected by the contact thermistor 13, Tc1 is a target temperature when the correction mode is started up, Tc2 is a correction mode control temperature, and tc is a control temperature maintaining time.

  In Act1, it is determined whether or not the detected temperature TE of the contact thermistor 13 is lower than the target temperature Tc1 at the time of starting the correction mode. If it is lower than the target temperature Tc1, the process proceeds to Act2, and if it exceeds the target temperature Tc1, Act5 Proceed to

  In Act 2, the heating source 7 is energized to heat the heat roller 3, and the process proceeds to Act 3.

  In Act3, it is determined whether or not the detected temperature TE of the contact thermistor 13 has reached the correction mode control temperature Tc2. If it has reached, the process proceeds to Act4, and if not reached, the process returns to Act2 to continue heating.

  In Act 4, the power supply to the heating source 7 is turned off, and the process proceeds to Act 5.

  In Act5, the timer t starts to be counted, and the process proceeds to Act6.

  In Act 6, it is determined whether or not the detected temperature TE of the contact thermistor 13 is lower than the correction mode control temperature Tc2, and if it is lower than the correction mode control temperature Tc2, the process proceeds to Act7, and if not, the process proceeds to Act10.

  In Act 7, the heating source 7 is energized to heat the heat roller 3, and the process proceeds to Act 8.

  In Act 8, it is determined whether or not the detected temperature TE of the contact thermistor 13 has reached the correction mode control temperature Tc2. If reached, the process proceeds to Act 9, and if not reached, the process returns to Act 7 to continue heating.

  In Act 9, the power supply to the heating source 7 is turned off, and the process proceeds to Act10.

  In Act 10, the detected temperature TE of the contact thermistor 13 is maintained at the correction mode control temperature Tc2, and the operation of Act 6-8 is performed until the count time of the timer t exceeds the control temperature maintenance time tc, and the process proceeds to Act11.

  In Act 11, the detected temperatures of the first non-contact thermistor 9 and the second non-contact thermistor 11 are read, and the process proceeds to Act 12. At that time, the ambient temperature detected by the ambient temperature detection sensor 23 is stored in the memory 22. Here, the detected temperature of the first non-contact thermistor 9 is T31 (first detected temperature), and the detected temperature of the second non-contact thermistor 11 is T32 (second detected temperature).

  In Act 12, the correction amounts (T1, T2) of the first non-contact thermistor 9 and the second non-contact thermistor 11 are calculated, and this process ends.

  Here, in a state where the detected temperature of the contact thermistor 13 is maintained at TE, the first temperature T21 of the measurement part of the first contact thermistor 9 in the heat roller 3 and the second temperature T22 of the measurement part of the second contact thermistor 11 are detected. Is known. Therefore, the difference (T21−T31) between the known first temperature T21 and the first detected temperature T31 is the first correction amount (T1). Similarly, the difference (T22−T32) between the known second temperature T22 and the second detected temperature T32 becomes the second correction amount (T2), and these correction amounts are stored in the memory 22.

  That is, when the sheet is passed through the fixing device 1, the heat of the heat roller 3 is taken away by the sheet. Therefore, the temperature of the nip portion needs to be detected by the non-contact thermistors 9 and 11 and controlled to a predetermined fixing temperature. However, the detected temperature of the non-contact thermistors 9 and 11 is detected lower than the actual temperature by the respective gaps with the heat roller 3. For this reason, the control is performed by adding the first correction amount (T1) and the second correction amount (T2) to the detected temperature.

  By the way, the first detection temperature T31 and the second detection temperature T32 of the non-contact thermistors 9 and 11 are also affected by the ambient temperature at the time of detection.

  Therefore, when the first correction amount (T1) and the second correction amount (T2) are determined by the correction ambient temperature (TA), and the first non-contact thermistor 9 and the second non-contact thermistor 11, If the ambient temperature (TB) at the time of startup of the fixing device detected by the ambient temperature detection sensor 23 is different, the values of the first correction amount (T1) and the second correction amount (T2) and the peripheral at the time of correction Correction is also made by the temperature difference between the temperature TA and the ambient temperature TB at the time of start-up. The first peripheral correction amount with respect to the first correction amount T1 due to the peripheral temperature difference T41 and the second peripheral correction amount T42 with respect to the second correction amount T2 are obtained from the following Table 1 and the chart of FIG. In Table 1, a1 represents a coefficient for the first correction amount T1, a2 represents a coefficient for the second correction amount T2, and both are values of a as shown in FIG.

  As shown in Table 1, the first peripheral correction amount T41 and the second peripheral correction amount T42 are obtained when the peripheral temperature (TA) at the time of correction for obtaining the first correction amount T1 and the second correction amount T2 is less than 20 ° C. It is determined separately when the temperature is 20 ° C. or higher (Formula 1 to Formula 4). Further, when the ambient temperature at the time of correction is less than 20 ° C., when the ambient temperature TB at the time of start-up (for example, when the power is turned on or when switching from the standby state to the fixable state) is less than 20 ° C., or above 20 ° C. I ask to divide it into two. Further, even when the correction ambient temperature (TA) is 20 ° C. or higher, the first peripheral correction amount T41 and the second peripheral correction amount T42 are obtained separately for cases where the startup peripheral temperature TB is less than 20 ° C. or more than 20 ° C. I have to.

  Equations 1 and 2 shown in Table 1 are obtained by multiplying the difference between the correction ambient temperature (TA) and the startup ambient temperature (TB) by a predetermined coefficient (a1, a2), and a correction amount (T1 , T2), a first peripheral correction amount T41 and a second peripheral correction amount T42 are obtained. Equations 3 and 4 are obtained by subtracting the threshold temperature 20 ° C. from the correction ambient temperature (TA) and the coefficient (a1, a2) and the startup ambient temperature (TB) from the threshold temperature 20 ° C. ) And the sum of the value obtained by multiplying the coefficient by 0.1 are further added to the correction amounts (T1, T2) to obtain the first peripheral correction amount T41 and the second peripheral correction amount T42.

  Equations 5 and 6 are the same as Equations 3 and 4, and Equations 7 and 8 multiply the difference between the corrected ambient temperature (TA) and the startup ambient temperature (TB) by a factor of 0.1. The first peripheral correction amount T41 and the second peripheral correction amount T42 are obtained by further adding the obtained values to the correction amounts (T1, T2).

  FIG. 5 is a chart for obtaining the coefficient a (a1, a2) from the relationship between the correction amounts (first correction amount T1, second correction amount T2) ° C. and the ambient temperature (TA) ° C. during correction. (Area 1, area 2, area 3), the value of coefficient a in the range of area 1 is 0.3, the value of coefficient a in the range of area 2 is 0.4, and the coefficient a in the range of area 3 is The value is 0.5.

  In FIG. 5, when the value of the first correction amount T1 is, for example, 17 ° C. and the correction ambient temperature (TA) is 14 ° C., it belongs to the range of area 2 and the coefficient a is 0.4.

  When the ambient temperature at start-up (TB) is 20 ° C. or higher, as shown in Table 1, the first peripheral correction amount (T41) is obtained by Equation 3, and the coefficient a1 is 0.4. It is done. Further, the second peripheral correction amount (T42) is obtained by Expression 4, and 0.4 is used as the coefficient a2.

On the other hand, when the normal control is performed on the fixing device 3, the non-contact thermistors 9 and 11 have poor responsiveness. Therefore, the contact thermistor 13 is used for temperature detection immediately after starting up, and the temperature of the fixing device 1 at starting up. The target temperature is changed as shown in Table 2 below depending on the state, and the control is switched to the non-contact thermistor after the target temperature is reached. The target temperature is preferably set to a temperature that is 10 to 30, preferably 20 to 30 ° C. lower than the fixing temperature.
By adopting such a configuration, the fixing device can be accurately controlled.

  In Table 2, when the temperature of the fixing device 1 is, for example, 40 ° C. or more and less than 60 ° C., temperature control using the contact thermistor 13 is performed up to 115 ° C., and when it exceeds 115 ° C., the first non-contact which is the main thermistor The thermistor 9 and the second non-contact thermistor 11 are used according to the width of the paper, and energization control to the heating source 7 is performed so that the outer peripheral surface of the heat roller 3 has a predetermined temperature.

  In the above-described embodiment, the fixing device that fixes the toner transferred onto the sheet by heating and pressing is used as an example of the heating device. However, the erasing is performed by heating the erasable toner to the erasing temperature. You may make it apply to a color machine. Further, the fixing device and the color erasing device may be used together.

  Further, in the above-described embodiment, the heat roller is described as an example of the heating member. However, the heating member may be a heating belt, and the heating source may be an IH system using an induction current generating coil. .

  According to this embodiment, high-precision temperature control can be performed by the first non-contact thermistor 9 and the second non-contact thermistor 11 which are main thermistors, and high-precision temperature control can be performed regardless of the ambient temperature at the start-up. Yes.

  It should be noted that the above-described embodiment is merely an example, and can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-mentioned embodiment is only a mere illustration in all points, and should not be interpreted limitedly. The interpretation of the technical matters indicated by the claims is not limited to the text of the specification. Further, all modifications, various improvements, alternatives and modifications belonging to the equivalent scope of the claims are all within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Fixing device 3 Heat roller 7 Heat source 9, 11 Non-contact thermistor 13 Contact thermistor 20 Control part 21 CPU
22 Memory 23 Ambient temperature detection sensor

Claims (3)

A heating device that heats a toner image on a sheet passed through a nip portion between a heating member and a pressure member,
A heating source for heating the heating member;
A non-contact thermistor that is arranged with a gap with the heating member and detects the temperature of the heating member;
A contact thermistor that contacts the heating member and detects the temperature of the heating member;
The temperature detected from the start-up to the target temperature uses the detected temperature of the contact thermistor. When the target temperature is exceeded, the detected temperature of the non-contact thermistor is used to control the heating source, and the heating member A control unit for controlling to a predetermined temperature;
A detection temperature correction unit for obtaining in advance a correction amount for the detection temperature of the non-contact thermistor by comparison with the detection temperature of the contact thermistor;
Ambient temperature detection means for detecting the ambient temperature of the heating device;
An ambient temperature correction unit that further corrects the correction amount obtained by the detected temperature correction unit based on the ambient temperature detected by the ambient temperature detection unit;
Have
The ambient temperature correction unit includes a correction ambient temperature detected by the ambient temperature detection unit when the correction amount is obtained, and a startup ambient temperature detected by the ambient temperature detection unit when the heating apparatus is started up. A heating device for obtaining a peripheral correction amount for further correcting the correction amount based on the above. The heating device according to claim 1,
The said control part changes target temperature with the temperature state of the said heating member, The heating apparatus characterized by the above-mentioned. The heating apparatus according to claim 1 or 2,
The said control part divides | segments the temperature state of the said heating member into several temperature range, and sets the target temperature for every said temperature range, The heating apparatus characterized by the above-mentioned.

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