JP3798119B2 - Fixing apparatus and fixing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a fixing device for fixing a developer image transferred on a non-transfer medium by heating and melting the image.And fixing methodAbout.
[0002]
[Prior art]
An image forming apparatus such as a copying machine includes a fixing device that fixes a developer image on a recording sheet by heating and melting an image of the developer transferred onto the recording sheet as a transfer medium.
[0003]
The fixing device includes a fixing roller having a heat source such as a halogen lamp inside, and a backup roller that is in rolling contact with the fixing roller at a predetermined pressure. The recording paper holding the developer image is supplied between these rollers, heated and pressurized at a predetermined fixing temperature, and the developer image is fixed on the recording paper.
[0004]
There are various sizes of recording paper that is passed between the rollers of the fixing device. If recording paper having a width smaller than the width of each roller, for example, A4 size recording paper, is continuously passed, The heat is taken away from the roller surface by the passage and the temperature of the roller surface is lowered only in the region where the recording paper has passed.
[0005]
Normally, when the surface temperature of the fixing roller is controlled, the roller surface temperature is detected by a thermistor disposed substantially at the center of the roller, and the lamp is turned on / off so that the temperature at the center is constant. For this reason, if the temperature at the center of the roller is reduced by the temperature of the central part of the roller as in the case of continuously passing recording paper of a predetermined size, the temperature at the end of the roller will rise abnormally if the temperature is controlled by the thermistor at the center. There is a possibility of being.
[0006]
For this reason, in the conventional fixing device, in addition to the thermistor disposed at the center of the roller, another thermistor is disposed at the roller end, and the lamp is turned on when an abnormal temperature rise at the roller end is detected. By turning off, destruction of the roller end portion due to heat is prevented. If an abnormal temperature rise at the end of the roller is detected, the lamp is turned off until the difference between the temperatures detected by the central thermistor and the end thermistor is within 5 ° C., and the temperature difference between the two is within 5 ° C. The lamp is turned on / off so that
[0007]
[Problems to be solved by the invention]
However, the thermistor used for temperature detection of the fixing device has a specific resistance value that varies with temperature, and the detected temperature varies depending on the thermistor used. For this reason, even if separate thermistors are arranged at the center and end of the roller as in the conventional fixing device and the surface temperature of the roller is controlled, a difference is detected in the detected temperature by each thermistor, and the accurate temperature Control may not be possible.
[0008]
Normally, thermistors have a variation of about ± 5% in their resistance values in consideration of mass production. For example, when a thermistor having a resistance value of 1.803 kΩ when a temperature of 160 ° C. is detected is mass-produced, the resistance value varies within a range of 1.713 to 1.893 kΩ. At this time, when the variation in the detection temperature by the thermistor is seen, it becomes 157.5 ° C. to 162.5 ° C., and a difference of 5 ° C. at maximum is generated in the detection temperature.
[0009]
In this way, when the temperature of the roller center part and the end part are detected using a thermistor having a variation in resistance value and the surface temperature of the roller is controlled, a difference occurs in the temperature detected by each thermistor, In some cases, the temperature difference between the end portion and the fixing portion may be increased. In particular, in the case of full-color printing, there is a problem that if the fixing temperature changes greatly between the central portion and the end portion of the roller, the degree of melting of the developer changes, and the output color tone also changes.
[0010]
The present invention has been made in view of the above points, and its purpose is to correct variations in detection temperature by a plurality of thermistors, to accurately control a fixing temperature, and to fix a developer image onto a transfer medium satisfactorily. An object of the present invention is to provide a fixing device that can be used.
[0011]
[Means for Solving the Problems]
  In order to achieve the above object, a fixing device according to claim 1 of the present invention heats and melts an image of a developer transferred onto a transfer medium, pressurizes the image together with the transfer medium, and transfers the transferred image. In a fixing device for fixing a developer image on a medium,First and second roller means for nipping and transporting a transfer medium to which the developer image is transferred, which are in rolling contact with each other at a predetermined pressure, and heating means for heating the first roller means A detecting means for detecting the surface temperature at a plurality of positions, and the surface temperature of the first roller means is substantially uniform in the axial direction. A correction means for correcting the detection result output from the detection means, and a control means for controlling the heating means according to the detection result corrected by the correction means,It has.
[0012]
  According to a second aspect of the present invention, the fixing device according to claim 2 heats and melts an image formed by the developer transferred onto the transfer medium, pressurizes the image together with the transfer medium, and applies the developer onto the transfer medium. In a fixing device for fixing an image,First and second roller means for nipping and transporting a transfer medium to which the developer image is transferred, which are in rolling contact with each other at a predetermined pressure, and heating means for heating the first roller means A detecting means for detecting the surface temperature at a plurality of positions, and the surface temperature of the first roller means is substantially uniform in the axial direction. In this case, the detection means detects the surface temperature of the first roller means, and corrects the detection result of the other detection means in accordance with the detection result of one of the detection means. And control means for controlling the heating means according to the detection result corrected by the correction means,It has.
[0013]
  According to a third aspect of the present invention, the fixing device according to the third aspect of the present invention heats and melts an image formed by the developer transferred onto the transfer medium, pressurizes the image together with the transfer medium, and applies the developer onto the transfer medium. In a fixing device for fixing an image,First and second roller means for nipping and transporting a transfer medium to which the developer image is transferred, which are in rolling contact with each other at a predetermined pressure, and heating means for heating the first roller means And detection means disposed on the outer surface of the image area through which the developer image held on the transfer medium passes, the surface of the first roller means heated by the heating means. Detecting means for detecting the temperature of the surface of the first roller means at a plurality of positions; and when the surface temperature of the first roller means becomes substantially uniform in the axial direction, the detecting means detects the first roller. A correction means for detecting a surface temperature of the means and correcting a detection result by another detection means in accordance with a detection result by the detection means provided outside the image area; and the detection result corrected by the correction means Control to control the heating means And means,It has.
[0014]
  According to a fourth aspect of the present invention, the fixing device according to the fourth aspect of the present invention heats and melts an image formed by the developer transferred onto the transfer medium, pressurizes the image together with the transfer medium, and applies the developer onto the transfer medium. In a fixing device for fixing an image,First and second roller means for nipping and transporting a transfer medium to which the developer image is transferred, which are in rolling contact with each other at a predetermined pressure, and heating means for heating the first roller means And the surface of the first roller means heated by the heating means, disposed at a substantially central position in the axial direction of the first roller means, and the surface temperature of the first roller means at the central position. An image through which a developer image held on the transfer medium is passed, which is a surface of the first roller means provided with the first detection means and the first roller means provided with the first detection means. A second detecting means for detecting a surface temperature of the first roller means at the end position, and a surface temperature of the first roller means being substantially uniform in the axial direction. When the first detection means and the second detection means According to the detection result corrected by the correction means, the correction means for detecting the surface temperature of the first roller means and correcting the detection result by the first detection means in accordance with the detection result by the second detection means Control means for controlling the heating means;It has.
[0015]
According to a fifth aspect of the present invention, the fixing device according to the fifth aspect heats and melts an image formed by the developer transferred onto the transfer medium, pressurizes the image together with the transfer medium, and applies the developer onto the transfer medium. In a fixing device for fixing an image, a pair of rollers that are in rolling contact with each other at a predetermined pressure so as to be slidable and sandwich and transfer a transfer medium onto which the developer image is transferred, and at least one of the pair of rollers A heating means for heating the roller; a first detection means disposed on the surface of the at least one roller at a substantially central position in the axial direction of the roller; and detecting a roller surface temperature at the central position; An end position on the surface of the roller on which the first detection means is disposed, disposed at an end position outside the image area through which the developer image held on the transfer medium passes. Detects roller surface temperature The first detection means and the second detection means in a state where the surface temperature of the at least one roller is substantially uniform in the axial direction and the transfer medium is not conveyed by the pair of rollers. Detecting the roller surface temperature at the center position and the end position, and correcting the roller surface temperature at the center position based on the roller surface temperature at the end position; and the center position corrected by the correction means Control means for controlling the heating means based on the roller surface temperature and controlling the surface temperature of the at least one roller to a predetermined temperature.
[0016]
  According to a sixth aspect of the present invention, the fixing device according to the sixth aspect heats and melts an image formed by the developer transferred onto the transfer medium, pressurizes the image together with the transfer medium, and applies the developer onto the transfer medium. In a fixing device for fixing an image,First and second roller means for nipping and transporting a transfer medium to which the developer image is transferred, which are in rolling contact with each other at a predetermined pressure, and heating means for heating the first roller means And the surface of the first roller means heated by the heating means, being in contact with the substantially central position in the axial direction of the first roller means, and the surface temperature of the first roller means at the central position is adjusted. A developer image held on the transfer medium is passed on the surface of the first detection means to detect and the surface of the first roller means on which the first detection means is contacted. A second detection means for detecting a surface temperature of the first roller means at the end position, in contact with an end position outside the image area; and according to a detection result by the second detection means. Correction means for correcting the detection result by the first detection means, and the correction And control means for controlling said heating means in accordance with detection result of the correction in stage,It has.
[0017]
  According to a seventh aspect of the present invention, the fixing device according to the seventh aspect heats and melts an image formed by the developer transferred onto the transfer medium, pressurizes the image together with the transfer medium, and applies the developer onto the transfer medium. In a fixing device for fixing an image,First and second roller means for nipping and transporting a transfer medium to which the developer image is transferred, which are in rolling contact with each other at a predetermined pressure, and heating means for heating the first roller means A thermistor disposed on the surface of the first roller means heated by the heating means and detecting the temperature of the surface at a plurality of positions, and the surface temperature of the first roller means is substantially uniform in the axial direction. A correction means for correcting the detection result output from the thermistor, and a control means for controlling the heating means based on the detection value corrected by the correction means,It has.
[0018]
  In the fixing device according to the eighth aspect of the present invention, the image of the developer transferred onto the transfer medium is heated and melted, and the image is pressed together with the transfer medium, and the developer is applied onto the transfer medium. In a fixing device for fixing an image,First and second roller means for nipping and transporting a transfer medium to which the developer image is transferred, which are in rolling contact with each other at a predetermined pressure, and heating means for heating the first roller means A thermistor disposed on the surface of the first roller means heated by the heating means and detecting the temperature of the surface at a plurality of positions, and the surface temperature of the first roller means is substantially in the axial direction. Correction means for detecting the surface temperature of the first roller means when the thermistor becomes uniform and correcting the detection value by another thermistor in accordance with the detection value by one thermistor of the thermistors; Control means for controlling the heating means based on the detection value corrected by the correction means;It has.
[0019]
  In addition, the fixing device according to claim 9 is the invention.A fixing device that heats and melts an image of the developer transferred onto the transfer medium, pressurizes the image together with the transfer medium, and fixes the developer image on the transfer medium. First and second roller means for nipping and conveying the transfer medium to which the developer image has been transferred, which is rolled by pressure, heating means for heating the first roller means, and heating by the heating means A surface of the first roller means including a thermistor disposed on the surface of the first roller means arranged outside the image area through which the developer image held on the transfer medium passes. A thermistor for detecting the temperature of the first roller means when the surface temperature of the first roller means becomes substantially uniform in the axial direction, the surface temperature of the first roller means is detected by the thermistor, Outside the image area And a control unit the heating means based on the detection value corrected by the correction means and the correction means in accordance with the values detected by the thermistor provided for correcting the detection value by the other thermistor,It has.
[0020]
  According to a tenth aspect of the present invention, the fixing device according to the tenth aspect heats and melts an image formed by the developer transferred onto the transfer medium, pressurizes the image together with the transfer medium, and the developer onto the transfer medium. In a fixing device for fixing an image,First and second roller means for nipping and transporting a transfer medium to which the developer image is transferred, which are in rolling contact with each other at a predetermined pressure, and heating means for heating the first roller means And disposed on the surface of the first roller means heated by the heating means at a substantially central position in the axial direction of the first roller means, and the surface temperature of the first roller means at the central position is determined. A first thermistor to be detected and an image area on the surface of the first roller means on which the first thermistor is disposed, through which the developer image held on the transfer medium passes. The second thermistor which is disposed at the outer end position and detects the surface temperature of the first roller means at the end position, and the surface temperature of the first roller means is substantially uniform in the axial direction. Sometimes the first thermistor and the second thermistor The surface temperature of the first roller means is detected by the correction means, the correction value for correcting the detection value by the first thermistor in accordance with the detection value by the second thermistor, and the detection value corrected by the correction means. Control means for controlling the heating means;It has.
[0021]
  Furthermore, the fixing device according to claim 11 of the present invention heats and melts an image formed by the developer transferred onto the transfer medium, pressurizes the image together with the transfer medium, and applies the developer onto the transfer medium. In a fixing device for fixing an image,First and second roller means for nipping and transporting a transfer medium to which the developer image is transferred, which are in rolling contact with each other at a predetermined pressure, and heating means for heating the first roller means The surface of the first roller means heated by the heating means is disposed in contact with the substantially central position in the axial direction of the first roller means, and detects the surface temperature of the first roller means at the central position. And a surface of the first roller means on which the first thermistor is disposed in contact with the first thermistor and outside the image region through which the developer image held on the transfer medium passes. When the surface temperature of the first roller means is substantially uniform in the axial direction, the second thermistor that is disposed in contact with the end position of the first and detects the surface temperature of the first roller means at the end position. And the first thermistor and the second thermistor. The surface temperature of the first roller means is detected by the correction means, the correction value for correcting the detection value by the first thermistor in accordance with the detection value by the second thermistor, and the detection value corrected by the correction means. Control means for controlling the heating means;It has.
  In the fixing method according to the twelfth aspect of the present invention, the image of the developer transferred onto the transfer medium is heated and melted, and the image is pressed together with the transfer medium, and the developer is applied onto the transfer medium. In a fixing method for fixing an image, the image forming apparatus includes first and second rollers, and is slidably contacted with a predetermined pressure so as to be slidable with respect to each other. The first roller is heated, disposed on the surface of the heated first roller, the surface temperature is detected at a plurality of positions, and the detected result is expressed as the surface temperature of the first roller. It is characterized by correcting when it becomes substantially uniform.
  In the fixing method according to the thirteenth aspect of the present invention, the image of the developer transferred onto the transfer medium is heated and melted, and the image is pressed together with the transfer medium, and the developer is applied onto the transfer medium. In a fixing method for fixing an image, the image forming apparatus includes first and second rollers, and is slidably contacted with a predetermined pressure so as to be slidable with respect to each other. The first roller is heated, disposed on the surface of the heated first roller, the surface temperature is detected at a plurality of positions, and the detected result is expressed as the surface temperature of the first roller. It is characterized in that other detection results are corrected in accordance with one detection result when it becomes substantially uniform.
  In the fixing method according to the fourteenth aspect of the present invention, an image formed by the developer transferred onto the transfer medium is heated and melted, and the image is pressed together with the transfer medium, and the developer is applied onto the transfer medium. In a fixing method for fixing an image, the image forming apparatus includes first and second rollers, and is slidably contacted with a predetermined pressure so as to be slidable with respect to each other. The first roller is heated, disposed on the surface of the heated first roller, the surface temperature is detected at a plurality of positions, and the detected result is expressed as the surface temperature of the first roller. It is characterized in that other detection results are corrected in accordance with the detection result detected outside the image area among the detected image areas when the image becomes substantially uniform.
  In the fixing method according to the fifteenth aspect of the present invention, the image of the developer transferred onto the transfer medium is heated and melted, and the image is pressed together with the transfer medium, and the developer is applied onto the transfer medium. In a fixing method for fixing an image, the image forming apparatus includes first and second rollers, and is slidably contacted with a predetermined pressure so as to be slidable with respect to each other. The first roller is heated and disposed on the surface of the heated first roller, and the surface temperature of the first roller in the axial center position and the end portion outside the image forming area of the first roller The detection result detected at the center position is matched with the detection result detected at the end position when the surface temperature of the first roller becomes substantially uniform. It is characterized by correction.
  Further, in the fixing method according to the sixteenth aspect of the present invention, the image of the developer transferred onto the transfer medium is heated and melted, and the image is pressed together with the transfer medium, and the developer is applied onto the transfer medium. In a fixing method for fixing an image, the image forming apparatus includes first and second rollers, and is slidably contacted with a predetermined pressure so as to be slidable with respect to each other. First One roller is heated, and the temperature of the surface of the heated first roller is detected at the axial center position of the first roller and the end position outside the image area of the first roller. The detection result detected at the center position is corrected in accordance with the detection result detected at the end position when the surface temperature of the first roller becomes substantially uniform. It is a feature.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, a fixing device 1 of the present invention is incorporated in a copying machine or the like, and heats an image formed by a developer transferred onto a recording paper P as a transfer medium to a predetermined fixing temperature. Melt and press the developer image onto the recording paper to fix it.
[0023]
The fixing device 1 includes a fixing roller 2 having a rotation shaft extending perpendicularly to the paper surface, and a backup roller 4 that is in rolling contact with a predetermined pressure from below the fixing roller 2. Each of the rollers 2 and 4 is formed by coating a surface of a cylindrical roller made of a material having a good thermal conductivity such as aluminum with a material having excellent releasability such as silicon rubber or tetrafluoroethylene resin. . The fixing roller 2 is rotated at a predetermined speed in the direction of the arrow by a motor (not shown) or the like, and the backup roller 4 is driven by the fixing roller 2 and rotated.
[0024]
Halogen lamps 3 and 5 as heat sources that act as heating means of the present invention are coaxially provided inside the rollers 2 and 4, respectively, and each of the rollers 2 and 4 is controlled by on / off control of the lamps 3 and 5. The surface temperature of 4 is controlled to a predetermined temperature.
[0025]
The recording paper P is conveyed along the guide plate 6, passes through the nip where the rollers 2 and 4 are in contact, and is discharged out of the copying machine via the pair of discharge rollers 7 and 8. At this time, the developer image transferred onto the recording paper P is heated and melted by the rollers 2 and 4 and pressed against the recording paper P, and the developer image is fixed on the recording paper P.
[0026]
On the surface of the fixing roller 2, an application mechanism 10 for applying the offset prevention liquid to the roller surface and a cleaning mechanism 20 for cleaning the roller surface are provided.
[0027]
The application mechanism 10 supplies the application roller 11 that is slidably contacted with the surface of the fixing roller 2, the supply roller 12 that is in contact with the application roller 11 on the side opposite to the fixing roller 2, and the supply roller 12. An oil tank (not shown) that stores an anti-offset liquid such as dimethyl silicone oil or methylphenyl silicone oil is provided.
[0028]
The offset prevention liquid in the oil tank is supplied to the felt 14 disposed in the oil pan 13 by a pump (not shown), and is supplied to the supply roller 12 by the capillary action of the felt 14. The offset prevention liquid supplied to the supply roller 12 is regulated to an appropriate layer thickness by an oil regulating blade 15 disposed in contact with the supply roller 12, and is supplied to the fixing roller 2 through the application roller 11. Excess offset prevention liquid transmitted from the felt 14 and the oil regulating blade 15 is once collected by the oil pan 13 and returned to the oil tank.
[0029]
The cleaning mechanism 20 for the fixing roller 2 cleans the roller surface by bringing the web 21 made of a nonwoven fabric into contact with the surface of the fixing roller 2 while running slightly. The web 21 is wound around a feeding roll 22 and is wound up little by little by a winding roll 23. Then, the web 21 traveling between the rolls 22 and 23 is brought into contact with the surface of the fixing roller 2 by a pressing roll 24 provided so as to be able to come into contact with the fixing roller 2 between the feeding roll 22 and the take-up roll 23. Pressed against.
[0030]
A cleaning roller 25 is slidably pressed onto the surface of the backup roller 4 so that the surface of the backup roller 4 is cleaned.
[0031]
As shown in FIG. 2, a plurality of thermistors 31, 32, 33, and 34 that act as detection means for detecting the surface temperature are disposed in contact with the surfaces of the fixing roller 2 and the backup roller 4. Central thermistors 31 and 33 are provided at substantially central positions of the rollers 2 and 4, respectively, and an image region through which the developer image formed on the recording paper P having the maximum width passes, that is, the developer is attached. End thermistors 32 and 34 are respectively provided outside the possible areas. Therefore, for example, when an A4 vertical size recording sheet is passed, only the area of the central thermistors 31 and 33 passes, and the area of the end thermistors 32 and 34 does not pass.
[0032]
On the surfaces of the fixing roller 2 and the backup roller 4, thermostats 35 and 36 for forcibly turning off the halogen lamps 3 and 5 in the rollers 2 and 4 when an abnormal temperature is detected (see FIG. 1). ) Is provided to increase the safety of the apparatus.
[0033]
Next, characteristics of the thermistors 31 to 34 disposed on the respective roller surfaces will be described with reference to FIGS.
As shown in FIG. 3, the thermistor has a specific resistance Rth whose resistance value changes in accordance with a change in temperature. The voltage detection unit 40 detects this change in resistance value, that is, a change in temperature as a change in voltage. It is connected. The resistance value of the thermistor decreases as the temperature rises according to the graph shown in FIG. In addition, the specific resistances Rth of the thermistors do not exactly match and vary within a certain range.
[0034]
The specific resistance Rth of the thermistor is serially connected to the resistors Ra and Rb of the voltage detector 40, and the voltage Vth output from the voltage detector 40 is expressed by the following equation.
[0035]
Vth = Rb · Vcc / (Ra + Rth + Rb)
Therefore, when the resistance value of the thermistor is changed due to a change in temperature, the output voltage Vth of the voltage detector 40 is changed in accordance with the change in Rth. Therefore, the temperature change can be detected by reading the change in the output voltage Vth.
[0036]
Incidentally, as described above, the specific resistance Rth of each thermistor varies and the resistance values of the resistors Ra and Rb of the voltage detection unit 40 also vary, so that the output voltage Vth detected as a temperature change is also shown in FIG. Variation occurs within the range shown in FIG. For this reason, variations in the detected temperature occur between the thermistors, making accurate temperature control difficult.
[0037]
For this reason, in this embodiment, the detection value of the central thermistor is corrected based on the detection value (output voltage Vth) by the end thermistor provided at the end of each roller 2, 4, and the detection temperature by each thermistor The temperature difference is eliminated and accurate temperature control is always possible. That is, the end thermistors 32 and 34 disposed outside the image area are not contaminated by the developer on the surface facing the roller surface, so that the detection value does not change over a long period of time. For this reason, the detection values of the central thermistors 31 and 33 are corrected so that the detection values of the central thermistors 31 and 33 are matched with the detection values of the end thermistors 32 and 34.
[0038]
Hereinafter, the temperature control operation of each roller including the thermistor correction operation will be described. Here, the correction operation of the thermistor disposed on the surface of the fixing roller 2 and the operation of controlling the surface temperature of the fixing roller 2 will be described as a representative, but the backup roller 4 is similarly controlled.
[0039]
First, the control system for the correction operation and the temperature control operation will be described. As shown in FIG. 6, the control system for controlling each operation has a microcontroller (hereinafter simply referred to as a controller) 50 that acts as a control means and a correction means of the present invention.
[0040]
A voltage detector 40 connected to the central thermistor 31 and a voltage detector 40 connected to the end thermistor 32 are connected to the controller 50 via the amplifier 41 and the A / D converter 42, respectively. .
[0041]
Further, a comparator 54 is connected to the controller 50 via a D / A converter 52, and an output terminal of the voltage detection unit 40 of the end thermistor 32 is connected to the comparator 54. Further, the output terminal of the comparator 54 is connected to a control circuit 56 that controls on / off of the halogen lamp 3.
[0042]
The voltages Vc and Ve detected by the respective voltage detectors 40 through the central thermistor 31 and the end thermistor 32 are respectively amplified by the amplifier 41 and then the temperature data via the A / D converter 42 as a controller. 50.
[0043]
The controller 50 corrects (or does not correct) the temperature data acquired from the central thermistor 31 based on the temperature data acquired from the end thermistor 32 according to a calculation formula described later. The reference potential is output to the comparator 54 via the A converter 52. The reference potential is compared with the voltage Ve by the comparator 54, and a comparison signal is output to the control circuit 56.
[0044]
The control circuit 56 outputs a control signal to the solid state relay (SSR) 58 based on the comparison signal input from the comparator 54, and the AC power is controlled by the SSR 58 based on this control signal to turn on / off the halogen lamp 3. Controlled off.
[0045]
Next, the correction operation of the central thermistor 31 and the control operation of the surface temperature of the fixing roller 2 by the controller 50 will be described in detail with reference to the flowcharts shown in FIGS. Here, the operation at the timing when the power of the copying machine is turned on will be described.
[0046]
First, when the power of the copying machine is turned on (step 1), the surface temperature at the end of the fixing roller 2 and the surface temperature at the center of the fixing roller 2 are detected via the center thermistor 31 and the end thermistor 32, respectively. (Step 2).
[0047]
Then, it is determined whether or not both of these temperatures are the same as the environmental temperature (step 3), and when each temperature is the same as the environmental temperature, a mode for correcting the detection value of the central thermistor 31 is selected. (Step 4) When at least one of the temperatures is different from the environmental temperature, a mode in which the detection value of the central thermistor 31 is not corrected is selected (Step 5). Here, when the detected temperature is 30 ° C. or less, it is determined that the detected temperature is the same as the environmental temperature. Moreover, environmental temperature means the temperature of the use environment of an apparatus.
[0048]
That is, when the temperature detected by the end thermistor 32 is different from the environmental temperature, for example, when a problem such as paper jam occurs during the printing operation and the power is turned off once, and the power is turned on after the problem is solved, There may be a case where a temperature difference is caused between the central portion and the end portion of the fixing roller 2 due to continuous passage of only A4 vertical size recording paper. From this state, the detected value of the central thermistor 31 is considered. This is because if it is corrected, accurate correction cannot be made.
[0049]
When the correction mode is selected in step 4, the halogen lamp 3 is turned on (step 6), and the fixing roller 2 is heated. Then, the end thermistor 32 determines whether or not the temperature at the end of the fixing roller 2 has reached 110 ° C. (step 7), and when the temperature reaches 110 ° C., rotation of the fixing roller 2 is started (step 8). ). As a result, the backup roller 4 is rotated by being driven by the fixing roller 2, and the surface of each roller is uniformly heated without unevenness.
[0050]
Subsequently, it is determined by the end thermistor 32 whether or not the temperature at the end of the fixing roller 2 has reached 160 ° C. (step 9), and from the point in time when the temperature at the end of the fixing roller 2 has reached 160 ° C. The halogen lamp 3 is on / off controlled so that the temperature at the two ends is 160 ° C. (step 10). That is, the lamp 3 is controlled so that the surface temperature of the fixing roller 2 is maintained at 160 ° C.
[0051]
As described above, the surface temperature of the center portion and the surface temperature of the end portion of the fixing roller 2 are set via the center portion thermistor 31 and the end portion thermistor 32 in a state where the surface of the fixing roller 2 is uniformly heated over the entire area. Each is redetected (step 11). A conversion table corresponding to these detected temperatures is selected, and the detected temperature of the central thermistor 31 is corrected according to this conversion table (step 12).
[0052]
This conversion table is calculated by the following equation based on the output voltage Vc from the central thermistor 31 and the output voltage Ve from the end thermistor 32, and a plurality of conversion tables are prepared in advance for each output voltage. That is, if the output voltage of an arbitrary central thermistor 31 before correction is Vc ′, the corrected output voltage Vc ″ of the central thermistor 31 is
Vc ″ = Ve / Vc × Vc ′
It becomes.
[0053]
Therefore, by substituting the output voltage V ′ of the central thermistor 31 into this equation, the corrected output voltage V ″ can be calculated, and the detected temperature of the central thermistor 31 can be corrected according to the detected temperature of the end thermistor 32. .
[0054]
As described above, when the detected temperature of the central thermistor 31 is corrected, a printing operation is started (step 13), and the central and end surface temperatures of the fixing roller 2 are detected by the central thermistor 31 and the end thermistor 32. Is monitored again.
[0055]
Then, it is determined whether or not the difference between the corrected temperature detected by the central thermistor 31 and the temperature detected by the end thermistor 32 exceeds 5 ° C. (step 14). When the temperature exceeds 5 ° C., the halogen lamp 3 is turned off. (Step 15). Thus, for example, when the A4 vertical size recording paper is continuously passed, the temperature of the roller end can be prevented from being abnormally increased and the roller end can be prevented from being destroyed by heat.
[0056]
If it is determined in step 14 that the temperature difference does not exceed 5 ° C., the upper limit / lower limit of the surface temperature of the fixing roller 2 is checked (step 16), and the control operation of the surface temperature of the fixing roller 2 is performed. Is terminated.
[0057]
On the other hand, when the non-correction mode is selected in step 5, a reference table prepared in advance is selected based on the output voltage of a standard thermistor (step 17), and detection by the central thermistor 31 is performed based on this reference table. The temperature is calculated. Then, it is determined whether or not the detected temperature has reached a desired control temperature (fixing temperature) (step 18). If the detected temperature has not reached the predetermined control temperature, the halogen lamp 3 is turned on (step 19). The surface temperature of the roller 2 is controlled to a predetermined temperature.
[0058]
When it is determined in step 18 that the surface temperature of the fixing roller 2 has reached a predetermined control temperature, the printing operation is started, and the operations after step 13 described above are performed.
[0059]
As described above, according to the fixing device of the present embodiment, since the detection value of the central thermistor 31 is corrected based on the detection value of the end thermistor 32, the variation in the detected temperature between the two thermistors can be corrected. The surface temperature of the fixing roller 2 can be accurately and finely controlled. As a result, the fixing temperature of the fixing device can be accurately controlled, and good fixing characteristics can be achieved.
[0060]
In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible within the scope of this invention. For example, the timing for correcting the detection value of the central thermistor as described above may be any arbitrary timing. For example, it may be corrected during the manufacturing process or setup of the copying machine.
[0061]
Further, the timing for correcting the detection value of the central thermistor is not particularly limited as long as the surface temperature of the central portion of the roller and the surface temperature of the end portion are uniform in a state where no recording paper is passed between the rollers. The temperature may be corrected when the temperature detected by the center thermistor and the end thermistor is 110 ° C. or lower. That is, even if there is a temperature difference between the surface temperature at the center and the surface temperature at the end, the entire roller surface is heated from 110 ° C. to the fixing temperature of the fixing device (about 160 ° C.). This is because it is heated substantially uniformly.
[0062]
Furthermore, in the above-described embodiment, the end thermistors 32 and 34 disposed at the ends of the rollers 2 and 4 are disposed outside the image area. However, the end thermistors are disposed within the image area in order to reduce the size of the apparatus. It may be arranged. Even in this case, the end thermistor is not contaminated by the developer at the initial stage, and the detection value of the central thermistor can be corrected appropriately.
[0063]
【The invention's effect】
  As described above, the fixing device of the present inventionAnd fixing methodSince it has the above-described configuration and operation, it is possible to correct variations in the detected temperature by a plurality of thermistors, accurately control the fixing temperature, and satisfactorily fix the developer image on the transfer medium.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a fixing device of the present invention.
2 is a perspective view showing a fixing roller, a backup roller, and a plurality of thermistors provided on the surface of each roller incorporated in the fixing device of FIG. 1;
3 is a diagram showing a circuit configuration of the thermistor of FIG. 2 and a voltage detection unit connected to the thermistor. FIG.
FIG. 4 is a graph showing a change in resistance value of the thermistor with respect to a change in temperature.
FIG. 5 is a graph showing the degree of variation in output voltage from a thermistor.
FIG. 6 is a block diagram showing a control system for correcting the detection value of the thermistor and controlling the roller surface temperature.
7 is a flowchart for explaining a control operation by the controller of FIG. 6;
FIG. 8 is a flowchart for explaining a control operation by the controller of FIG. 6;
FIG. 9 is a flowchart for explaining a control operation by the controller of FIG. 6;
[Explanation of symbols]
1 ... Fusing device,
2 Fixing roller,
3, 5 ... Halogen lamp,
4 ... Backup roller,
10 ... coating mechanism,
20 ... cleaning mechanism,
31, 33 ... Thermistor at the center,
32, 34 ... end thermistor,
40: Voltage detector,
41 ... Amplifier,
42 ... A / D converter,
50 ... Microcontroller,
52 ... D / A converter,
54 ... Comparator,
56 ... Control circuit,
58 ... SSR.

Claims (16)

In a fixing device that heats and melts an image of a developer transferred onto a transfer medium, pressurizes the image together with the transfer medium, and fixes the developer image on the transfer medium.
First and second roller means which are in rolling contact with each other at a predetermined pressure so as to sandwich and transfer a transfer medium onto which the developer image is transferred;
Heating means for heating the first roller means;
A detecting means disposed on the surface of the first roller means heated by the heating means and detecting the surface temperature at a plurality of positions;
Correction means for correcting the detection result output from the detection means when the surface temperature of the first roller means becomes substantially uniform in the axial direction;
Control means for controlling the heating means according to the detection result corrected by the correction means;
A fixing device. In a fixing device that heats and melts an image of a developer transferred onto a transfer medium, pressurizes the image together with the transfer medium, and fixes the developer image on the transfer medium.
First and second roller means which are in rolling contact with each other at a predetermined pressure so as to sandwich and transfer a transfer medium onto which the developer image is transferred;
Heating means for heating the first roller means;
A detecting means disposed on the surface of the first roller means heated by the heating means and detecting the surface temperature at a plurality of positions;
When the surface temperature of the first roller means becomes substantially uniform in the axial direction, the surface temperature of the first roller means is detected by the detection means, and detection by one of the detection means is performed. Correction means for correcting the detection result by other detection means according to the result;
Control means for controlling the heating means according to the detection result corrected by the correction means;
A fixing device. In a fixing device that heats and melts an image of a developer transferred onto a transfer medium, pressurizes the image together with the transfer medium, and fixes the developer image on the transfer medium.
First and second roller means which are in rolling contact with each other at a predetermined pressure so as to sandwich and transfer a transfer medium onto which the developer image is transferred;
Heating means for heating the first roller means;
The first roller means heated by the heating means includes detection means disposed outside the image region through which the developer image held on the transfer medium passes. Detecting means for detecting the temperature of the surface of the roller means at a plurality of positions;
When the surface temperature of the first roller means becomes substantially uniform in the axial direction, the detection means detects the surface temperature of the first roller means, and the detection means provided outside the image area Correction means for correcting the detection result by other detection means in accordance with the detection result;
Control means for controlling the heating means according to the detection result corrected by the correction means;
A fixing device. In a fixing device that heats and melts an image of a developer transferred onto a transfer medium, pressurizes the image together with the transfer medium, and fixes the developer image on the transfer medium.
First and second roller means which are in rolling contact with each other at a predetermined pressure so as to sandwich and transfer a transfer medium onto which the developer image is transferred;
Heating means for heating the first roller means;
The surface of the first roller means heated by the heating means is disposed at a substantially central position in the axial direction of the first roller means, and detects the surface temperature of the first roller means at the central position. First detecting means for
A surface of the said first detection means is arranged first roller means, distribution the outside of the end position than the image region developer image held on the transfer medium body is passed A second detecting means for detecting a surface temperature of the first roller means at the end position;
When the surface temperature of the first roller means becomes substantially uniform in the axial direction, the surface temperature of the first roller means is detected by the first detection means and the second detection means, Correction means for correcting the detection result by the first detection means in accordance with the detection result by the two detection means;
Control means for controlling the heating means according to the detection result corrected by the correction means;
A fixing device. In a fixing device that heats and melts an image of a developer transferred onto a transfer medium, pressurizes the image together with the transfer medium, and fixes the developer image on a non-transfer medium.
A pair of rollers that are in rolling contact with each other at a predetermined pressure so as to sandwich and transfer the transfer medium onto which the developer image is transferred;
Heating means for heating at least one of the pair of rollers;
A first detection means disposed on the surface of at least one of the rollers and disposed at a substantially central position in the axial direction of the roller to detect a roller surface temperature at the central position;
The roller is disposed on the surface of the roller on which the first detection unit is disposed, and is disposed at an end position outside the image region through which the developer image held on the transfer medium passes. Second detection means for detecting the roller surface temperature at the position;
In a state where the surface temperature of the at least one roller is substantially uniform in the axial direction and the medium to be transferred is not conveyed by the pair of rollers, the first and second detection means detect the center position and the end position. Correction means for detecting the roller surface temperature and correcting the roller surface temperature at the center position based on the roller surface temperature at the end position;
Control means for controlling the heating means based on the roller surface temperature at the center position corrected by the correction means, and controlling the surface temperature of the at least one roller to a predetermined temperature;
A fixing device. In a fixing device that heats and melts an image of a developer transferred onto a transfer medium, pressurizes the image together with the transfer medium, and fixes the developer image on the transfer medium.
First and second roller means which are in rolling contact with each other at a predetermined pressure so as to sandwich and transfer a transfer medium onto which the developer image is transferred;
Heating means for heating the first roller means;
The surface of the first roller means heated by the heating means is disposed in contact with the substantially central position in the axial direction of the first roller means, and detects the surface temperature of the first roller means at the central position. First detection means;
On the surface of the first roller means in contact with the first detection means, at an end position outside the image area through which the developer image held on the transfer medium passes. A second detection means disposed in contact and detecting a surface temperature of the first roller means at the end position;
Correction means for correcting the detection result by the first detection means in accordance with the detection result by the second detection means;
Control means for controlling the heating means according to the detection result corrected by the correction means;
A fixing device comprising: In a fixing device that heats and melts an image of a developer transferred onto a transfer medium, pressurizes the image together with the transfer medium, and fixes the developer image on the transfer medium.
First and second roller means which are in rolling contact with each other at a predetermined pressure so as to sandwich and transfer a transfer medium onto which the developer image is transferred;
Heating means for heating the first roller means;
A thermistor disposed on the surface of the first roller means heated by the heating means and detecting the temperature of the surface at a plurality of positions;
Correction means for correcting the detection result output from the thermistor when the surface temperature of the first roller means becomes substantially uniform in the axial direction;
Control means for controlling the heating means based on the detection value corrected by the correction means;
A fixing device. In a fixing device that heats and melts an image of a developer transferred onto a transfer medium, pressurizes the image together with the transfer medium, and fixes the developer image on the transfer medium.
First and second roller means which are in rolling contact with each other at a predetermined pressure so as to sandwich and transfer a transfer medium onto which the developer image is transferred;
Heating means for heating the first roller means;
A thermistor disposed on the surface of the first roller means heated by the heating means and detecting the temperature of the surface at a plurality of positions;
When the surface temperature of the first roller means becomes substantially uniform in the axial direction, the surface temperature of the first roller means is detected by the thermistor, and is adjusted to a detection value by one of the thermistors. Correction means for correcting the detection value by other thermistors,
Control means for controlling the heating means based on the detection value corrected by the correction means;
A fixing device. In a fixing device that heats and melts an image of a developer transferred onto a transfer medium, pressurizes the image together with the transfer medium, and fixes the developer image on the transfer medium.
First and second roller means which are in rolling contact with each other at a predetermined pressure so as to sandwich and transfer a transfer medium onto which the developer image is transferred;
Heating means for heating the first roller means;
A first thermistor disposed on the surface of the first roller means heated by the heating means and disposed outside the image area through which the developer image held on the transfer medium passes; A thermistor for detecting the temperature of the surface of the roller means at a plurality of positions;
When the surface temperature of the first roller means becomes substantially uniform in the axial direction, the surface temperature of the first roller means is detected by the thermistor, and the detection value by the thermistor provided outside the image area In accordance with the correction means for correcting the detection value by other thermistors,
Control means for controlling the heating means based on the detection value corrected by the correction means;
A fixing device. In a fixing device that heats and melts an image of a developer transferred onto a transfer medium, pressurizes the image together with the transfer medium, and fixes the developer image on the transfer medium.
First and second roller means which are in rolling contact with each other at a predetermined pressure so as to sandwich and transfer a transfer medium onto which the developer image is transferred;
Heating means for heating the first roller means;
On the surface of the first roller means heated by the heating means, the first roller means is disposed at a substantially central position in the axial direction of the first roller means, and detects the surface temperature of the first roller means at the central position. A first thermistor;
Arranged on the surface of the first roller means on which the first thermistor is disposed, at an end position outside the image area through which the developer image held on the transfer medium passes. A second thermistor for detecting the surface temperature of the first roller means at the end position;
When the surface temperature of the first roller means becomes substantially uniform in the axial direction, the surface temperature of the first roller means is detected by the first thermistor and the second thermistor. Correction means for correcting the detection value by the first thermistor according to the detection value by the thermistor;
Control means for controlling the heating means according to the detection value corrected by the correction means;
A fixing device. In a fixing device that heats and melts an image of a developer transferred onto a transfer medium, pressurizes the image together with the transfer medium, and fixes the developer image on the transfer medium.
First and second roller means which are in rolling contact with each other at a predetermined pressure so as to sandwich and transfer a transfer medium onto which the developer image is transferred;
Heating means for heating the first roller means;
The surface of the first roller means heated by the heating means is disposed in contact with the substantially central position in the axial direction of the first roller means to detect the surface temperature of the first roller means at the central position. 1 thermistor,
The first thermistor is in contact with the surface of the first roller means, and is disposed in contact with the end position outside the image area through which the developer image held on the transfer medium passes. A second thermistor which is provided and detects the surface temperature of the first roller means at the end position;
When the surface temperature of the first roller means becomes substantially uniform in the axial direction, the surface temperature of the first roller means is detected by the first thermistor and the second thermistor. Correction means for correcting the detection value by the first thermistor according to the detection value by the thermistor;
Control means for controlling the heating means according to the detection value corrected by the correction means;
A fixing device.   In a fixing method in which an image formed by a developer transferred onto a transfer medium is heated and melted, and the image is pressed together with the transfer medium to fix the developer image on the transfer medium.
  A first roller and a second roller, which are in rolling contact with each other at a predetermined pressure so as to be able to roll with each other;
  Heating the first roller;
  Disposed on the surface of the heated first roller, and detecting the surface temperature at a plurality of positions;
  The detected detection result is corrected when the surface temperature of the first roller becomes substantially uniform,
  A fixing method, wherein heating of the first roller is controlled according to the corrected detection result.   In a fixing method in which an image formed by a developer transferred onto a transfer medium is heated and melted, and the image is pressed together with the transfer medium to fix the developer image on the transfer medium.
A first roller and a second roller, which are in rolling contact with each other at a predetermined pressure so as to be able to roll with each other;
  Heating the first roller;
  Disposed on the surface of the heated first roller, and detecting the surface temperature at a plurality of positions;
  The detection result thus detected is adjusted to one detection result when the surface temperature of the first roller becomes substantially uniform, and other detection results are corrected,
  A fixing method, wherein heating of the first roller is controlled according to the corrected detection result.   In a fixing method in which an image formed by a developer transferred onto a transfer medium is heated and melted, and the image is pressed together with the transfer medium to fix the developer image on the transfer medium.
A first roller and a second roller, which are in rolling contact with each other at a predetermined pressure so as to be able to roll with each other;
  Heating the first roller;
  Disposed on the surface of the heated first roller, and detecting the surface temperature at a plurality of positions;
  This detection result is corrected in accordance with the detection result detected outside the image area of the first roller when the surface temperature of the first roller becomes substantially uniform, and other detection results are corrected.
  A fixing method, wherein heating of the first roller is controlled according to the corrected detection result.   In a fixing method in which an image formed by a developer transferred onto a transfer medium is heated and melted, and the image is pressed together with the transfer medium to fix the developer image on the transfer medium.
  A first roller and a second roller, which are in rolling contact with each other at a predetermined pressure so as to be able to roll with each other;
  Heating the first roller;
  Arranged on the surface of the heated first roller, and detecting the surface temperature at the axial center position of the first roller and the end position outside the image forming area of the first roller;
  The detection result detected is corrected at the center position according to the detection result detected at the end position when the surface temperature of the first roller becomes substantially uniform,
  A fixing method, wherein heating of the first roller is controlled according to the corrected detection result.   In a fixing method in which an image formed by a developer transferred onto a transfer medium is heated and melted, and the image is pressed together with the transfer medium to fix the developer image on the transfer medium.
  A first roller and a second roller, which are in rolling contact with each other at a predetermined pressure so as to be able to roll with each other;
  Heating the first roller;
Detecting the temperature of the surface of the heated first roller at the axial center position of the first roller and the end position outside the image area of the first roller;
  The detection result detected is corrected at the center position according to the detection result detected at the end position when the surface temperature of the first roller becomes substantially uniform,
  A fixing method, wherein the temperature of the first roller is controlled in accordance with the corrected detection result.

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