JP3498271B2 - Image recording apparatus with temperature controller for heat roller type fixing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus having a temperature controller in a heat roller type fixing device, which does not cause a problem such as hot offset or fixing under. It is. 2. Description of the Related Art Conventionally, in a heat roller fixing method, a heater 1 for heating a portion corresponding to a small-size paper passing portion of a fixing roller is used.
There is a method of making the temperature distribution of the fixing roller as uniform as possible by using two heaters (the power W1) and the heater 2 (the power W2) that heats a portion corresponding to the small-size non-sheet passing portion of the fixing roller. The value of W1 + W2 is limited to a certain value or less). That is, the two heaters are controlled by detecting the temperature of the roller at a position corresponding to each heat-generating portion. Normally, the temperatures for controlling the two heaters are the same. At the time of small-size sheet passing, the heater 1 keeps the ON state because the roller temperature decreases, but the heater 2 turns ON / OFF because the roller temperature of the non-sheet passing portion does not decrease.
State. Therefore, it cannot be said that the power of W2 is being used effectively during copying. However, if the heater 2 is kept turned on in the same manner as the heater 1, the decrease in the temperature of the paper passing portion is reduced, but the meaning of the two heaters is lost, and the temperature of the roller in the non-paper passing portion becomes abnormally high. In a large-size copy after a small-size copy, a so-called hot offset phenomenon occurs in which minute toner adheres to the surface of the heat roller. Further, in a fixing device using a non-contact type temperature sensor for detecting the temperature of the fixing roller, there are two cases, that is, immediately after warming up by turning on a heater in a state where the fixing device is cold, and when the fixing device is warm. Since the value of the difference TR−TS = ΔT between the roller surface temperature TR and the sensor detection temperature TS is different, if the temperature is controlled at the same set temperature, the roller surface temperature becomes as shown in FIG. 1 (immediately after the warm-up, the sensor ambient temperature is sufficient. ΔT is large because it is not warm). That is, the temperature of the roller immediately after warm-up becomes extremely high, which may cause a reduction in roller life, hot offset, and the like. In addition, when the copying is performed (when the roller is rotated) and during standby (when the roller is stopped), the temperature around the sensor is different even after the same time elapses. Unless such factors are taken into account, it is difficult to control the target roller temperature. Further, when the temperature is not switched during continuous copying of paper having a width shorter than the heater heat-generating portion in the heat roller fixing, as shown in FIG. The temperature rises, causing problems such as occurrence of hot offset and reduction of roller life. The following has been proposed as a means for suppressing a rise in temperature in a non-sheet-passing portion as a heater heat-generating portion of a fixing roller. JP 60-247A
In No. 277, after a fixed number of copies have been made from the start of copying, the fixing roller set temperature is sequentially switched to the lower one. In Japanese Utility Model Application Laid-Open No. 63-105169, the set temperature of the fixing roller is switched to a lower temperature after a fixed time from the start of copying. However, the proposal of Japanese Patent Application Laid-Open No. 60-247277 is a prospective control in the case where the heat supply amount is assumed to be a constant value, and hot offset or fixing under may not occur. As shown in FIG. 2B, the fixing under may occur. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in consideration of the temperature of a fixing roller.
Heat roller type using non-contact temperature sensor for detection
The fixing roller surface temperature with high accuracy.
Temperature control for the heat roller type fuser
An object of the present invention is to provide an image recording apparatus provided with a roller. [0007] [0008] [0009] [Means for Solving the Problems] The above object is achieved by the following hand stage. A fixing roller having a built-in heater and a fixing roller
A pressure roller that presses and rotates cooperatively with the
Close and non-contact temperature for detecting the temperature of the roller outer peripheral surface
Temperature sensor for heat roller type fuser using sensor and
Turn on the heater in the image recording device equipped with the roller
Multiple control temperatures to turn on / off and when main switch is on
Having a set temperature for changing the control temperature of the
Controller is ON when heater is ON by main switch ON
If the detected temperature is below the set temperature, the control temperature
Lower control temperature, and after warm-up is complete
And / or the rotation time of the fixing roller is detected.
Control temperature to higher temperature based on the detection result of
Switch to the highest control temperature and turn on the main switch
The detected temperature when the heater is turned on is below the set temperature.
If not, set the control temperature to the highest control temperature.
Temperature control for heat roller type fixing device
Image recording device provided with rollers. [0013] The detection before the heater is turned on by the main switch being turned on.
Temperature, elapsed time from completion of warm-up, fixing roller
Rotation time (number of copies) is detected, and based on the detection result,
Control temperature for turning on / off the heater
Temperature controller (control
Part) is an image recording device equipped with
Detected by elapsed time or temperature sensor at that time
Fusing roller control temperature according to the fusing roller surface temperature
Temperature is properly switched, hot offset and fixing
The temperature is controlled so that no dust occurs. FIG. 3 shows a first embodiment of the image recording apparatus according to the present invention.
This will be described with reference to FIG. FIG. 3 shows a main part of an image recording apparatus according to the present invention. A photosensitive drum 1 is rotated in the direction of an arrow, and a potential is applied to the outer periphery of the photosensitive drum by a charger 2, and the photosensitive drum 1 is further exposed to light. The latent image is formed by projecting the original image at 3. The latent image is visualized by a developing device 4 to form a toner image.
And is transferred onto the recording paper by the timing roller 7 so as to match the toner image. The recording paper to which the toner image has been transferred is separated from the peripheral surface of the photoreceptor 1 by the separator 8 and conveyed to a heat roller fixing device 10 to be described later over the conveying belt 9 to perform the heat fixing process of the toner image. And output as an image forming product. The photoreceptor after the transfer of the toner image onto the recording paper is cleaned by removing the remaining toner by a cleaning device (not shown), and is repeatedly subjected to image formation. In the image recording apparatus according to the present embodiment, the recording paper is fed and conveyed in the apparatus on the basis of one-sided conveyance. FIG. 4 is an enlarged view of the heat roller fixing device 10 shown in FIG. Reference numeral 12 in the fixing device 10
A fixing roller which has a built-in heater A14 and a heater B15 and has a roller surface coated with a layer of a releasable material such as fluororesin or silicone rubber, and is a heating roller for fusing and fixing a toner image on recording paper as a transfer material. The rollers 13 are pressure-contact rollers that cover the surface of the roller, which does not include a heating unit, with silicon rubber or the like, and rotate cooperatively while pressing against the fixing roller 12. Further, as shown in FIG. 5, a heater A is a heater having a heat-generating portion in a small-size sheet passing portion made of a halogen lamp or the like provided in the fixing roller in parallel with the roller axis, and a heater B is also provided in the fixing roller. A heater provided with A and having a small size non-sheet passing portion and a heat generating portion in a non-sheet passing portion. Reference numeral 18 denotes a separating claw for preventing the recording paper from winding around the fixing roller peripheral surface, and reference numeral 20 denotes a control unit provided in the image recording apparatus main body. 21A and 2
Reference numeral 1B denotes a temperature sensor which is a temperature detecting means for detecting the surface temperature of the fixing roller 12 corresponding to the positions of the heaters A and B, for example, a thermistor or the like. It is provided a little away from. Reference numeral 22 denotes a copy button, 23 denotes an input key for inputting a recording paper size, the number of copies, and the like, for example, a numeric keypad, and 24 and 25 supply electric power to the heaters A and B and supply electric power under the control of the control unit 20, respectively. This is a heater power supply that is turned ON / OFF. Next, the sequence of the temperature control of the first embodiment will be described with reference to the flowchart of FIG. 6 and a diagram showing the control state of the roller surface temperature shown in FIG. First, the control temperature T of each of the heaters A and B
a and Tb are set to the same specified temperature T1 in advance (step 1). When a main switch (not shown) is turned on and the power is turned on, the control unit turns on the heaters A and B via the heater power supplies 24 and 25, heats the fixing roller 12 from the inside, and the outer peripheral surface temperature of the fixing roller rises to copy. When the temperature reaches the specified temperature T1 lower than the control temperature at the time, the temperature sensor 21A,
The control unit 20 sets the heaters A and B to O by the temperature signal of 21B.
FF is performed, the warm-up is completed, and thereafter control is performed at the specified temperature until the copy is started. After the warm-up is completed, the copy start button is pressed (step 2), and the recording paper size width to be used is determined (step 3).
If it is less than the width (step 4), the control temperature T of the heater A
a is reset to the specified temperature T2, and the control temperature Tb of the heater B is reset to the specified temperature T3 (T2 <T3) higher than the specified temperature T2 (step 4), and copying is performed. When the copying is completed (step 5), the control temperatures Ta and Tb of the heaters A and B are both reset to the specified temperature T1 at the time of warm-up (step 6).
On the other hand, if the recording paper size width to be used is equal to or larger than the A4 width (step 7), both the control temperatures Ta and Tb of the heaters A and B are reset to the specified temperature T2 (step 4), and copying is performed. When the copying is completed (Step 8), the control temperatures Ta and Tb of the heaters A and B are reset to the warm-up specified temperature T1 as described above. Note that heater A and heater B
The ON / OFF control is independently controlled so that the heaters are turned on when the temperature detected by the temperature sensors 21A and 21B is lower than the control temperature, and the heater is turned off when the temperature is equal to or higher than the control temperature. According to the first embodiment, it is possible to prevent a temperature drop in the paper passing portion as much as possible while preventing a problem such as a hot offset due to an abnormal temperature rise in the non-paper passing portion. In this embodiment, the case of single-side paper feeding has been described. However, in the case of center-based paper feeding, a heater for heating only a small-size paper passing portion and a heater for heating only a small-size non-paper passing portion are provided. A similar effect can be obtained by the above-described control method using a heater that operates as described above. Next, a second embodiment of the image recording apparatus according to the present invention will be described with reference to FIGS. FIG. 8 is an enlarged view of Embodiment 2 of the heat roller fixing device 10 used in the image recording apparatus shown in FIG.
The fixing device 10 includes a fixing roller 12 including at least one heater H such as a halogen lamp, and a pressure roller 13 that presses against the fixing roller from immediately below. The toner image is melted and fixed while the recording paper is conveyed by the pressure contact portion. A temperature sensor S for detecting the temperature of the peripheral surface of the fixing roller 12 is arranged on the fixing roller 12 so as not to be in contact with the peripheral surface. The temperature detected by the non-contact type temperature sensor S is fed back to a control unit of the printing apparatus main body, and the control unit (temperature controller) switches a heater power supply via a drive system according to the temperature data. The heater H is operated to interrupt the current to the heater H to control the temperature of the fixing roller. The control unit (temperature controller) detects the temperature detected by the temperature sensor S before the heater H is turned on,
The control (setting) temperature for turning on / off the heater H is changed in a plurality of ways based on the detection result of the elapsed time from the completion of the warm-up, the rotation time of the fixing roller 12 corresponding to the number of copies, and the like. Hereinafter, the temperature control sequence will be described based on the flowchart shown in FIG. 9 and the diagram showing the state of the roller temperature control shown in FIG. The main switch MSW of the recording device is turned on
At this time, if the fixing detection temperature is equal to or lower than the normal set temperature T1 (step 1), the control temperature is changed to T20 higher than T1 (step 2), and the fixing detection temperature is set to the normal setting temperature T1.
If it is not equal to or less than 1, the control temperature is changed to the highest control temperature T2n (step 3). Then, a predetermined time A or more elapses from the completion of warm-up or the rotation of the fixing roller is A '.
If more than one minute has elapsed (step 4), the temperature is changed to a control temperature T21 higher than T20 (step 5). If the predetermined time A or less has elapsed from the completion of the warm-up or the rotation of the fixing roller has elapsed for A 'or less, the control temperature T20 is not changed. Further, if the time elapses and the predetermined time B or more has elapsed since the completion of the warm-up or the rotation of the fixing roller has elapsed B 'or more (Step 6), the control temperature is changed to a control temperature T22 higher than T21 (Step 7). ). If the predetermined time B or less has elapsed since the completion of the warm-up or the rotation of the fixing roller has elapsed no more than B ', the control temperature T21 is not changed. In this way, the control temperature is further increased to a control temperature T23 higher than T22 in accordance with the lapse of a predetermined time or more after the completion of warm-up or the rotation of the fixing roller for a predetermined time or more. T24,
As in T25,..., T2n, a plurality of control temperatures are sequentially switched and changed (step 8). According to the second embodiment, the surface temperature of the fixing roller can be accurately controlled even with a non-contact type sensor. Next, a third embodiment of the image recording apparatus according to the present invention will be described with reference to FIGS. The heat roller fixing device 10 according to the third embodiment includes:
The heat roller fixing device 10 used in the second embodiment.
The configuration is basically the same as The fixing roller 12 has a temperature sensor S for detecting the peripheral surface temperature of the fixing roller.
Are arranged on the outer peripheral surface or in a state of being slightly separated from the outer peripheral surface. The power supply to the heater H is controlled so that the temperature sensor S can always detect a predetermined control temperature in the sheet passing portion, and thereby the peripheral surface of the fixing roller 12 is maintained at a temperature suitable for fixing. The flowchart shown in FIG. 11 and the state of the roller temperature control will now be described with reference to FIGS.
The sequence of the temperature control will be described based on (b). In the heat roller fixing device 10 of the third embodiment, the normal control temperature of the fixing roller is T1, the second control temperature is T2, and the third control temperature is T3 (T1> T2).
≧ T3). First, the set temperature of the heater H is set in advance to the normal control temperature T1 (step 1). When a main switch (not shown) is turned on to turn on the power, the control unit turns on the heater via the heater power supplies 24 and 25, heats the fixing roller 12 from the inside, and the surface temperature of the fixing roller rises to reach the control temperature T1. Then, the control unit 20 turns off the heater H according to the temperature signal from the temperature sensor 21 and completes the warm-up. When the copy start button is pressed after the warm-up is completed (step 2), the surface temperature of the fixing roller is controlled at the control temperature T1 (step 3). As the copying progresses, heat is taken by the recording paper passing through the fixing roller, and the surface temperature of the fixing roller in the paper passing portion gradually decreases.
However, if the detected temperature of the fixing roller once drops below T2, which is a temperature lower than T1, and then rises again to T2 with sufficient heat supply (step 4), the control temperature is changed from T1 to T2. Switch to T3, which is a still lower temperature (step 5). The operation of switching the control temperature from T1 to T3 may be repeated. In this manner, when copying is continued while the control temperature is switched to T3 and the process is finished (step 6), the control is switched back to the control temperature T1 set first (step 7). However, if the heat supply amount does not have a margin and does not rise to T2 again in step 4, the control temperature is kept at T1 and switching is not performed. FIG. 12A shows the state of the fixing roller temperature control when the power supply voltage of the image recording apparatus of the present invention is low. That is, the roller temperature during copying set to the normal control temperature T1 gradually decreases, and once decreases from T2,
Since the temperature does not rise again to T2, it is considered that the temperature increase of the non-sheet passing portion does not cause any problem, so that the temperature is not switched from the normal control temperature T1. However, since the temperature is not switched to a lower temperature, the temperature does not decrease so as to cause the fixing under. FIG. 12B shows a case where the power supply voltage is high.
This shows the state of the fixing roller temperature control. In other words, the roller temperature during copying set to the normal control temperature T1 gradually decreases, but once decreases from T2 and then rises again to T2. Therefore, the control temperature is switched from T1 to T3. However, since the power supply voltage is high, even if the control temperature is switched to a lower one and set, the temperature does not decrease so as to cause the fixing under. According to the configuration of the above embodiment, the following effects can be obtained. (1) The temperature drop in the paper passing portion can be reduced as much as possible while preventing the hot offset phenomenon due to the abnormal temperature rise in the non-paper passing portion. (2) Even with a non-contact sensor, the surface temperature of the fixing roller can be accurately controlled while preventing overshoot. (3) When the power supply voltage is low, the temperature rise in the non-sheet passing portion is considered to be small, so that the control temperature is not switched to a low temperature. Since the temperature switching is not performed, the temperature of the sheet passing portion does not decrease until reaching the fixing under. Further, when the power supply voltage is high, even when the control temperature is switched, the temperature of the sheet passing portion does not decrease until the fixing under occurs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a state of temperature control in a conventional fixing device using a non-contact type temperature sensor. FIGS. 2A and 2B show a state of an upper roller temperature change when a set temperature of a fixing roller is not switched or a power supply voltage is low in a conventional example. FIG. 3 is a diagram showing a main part of an image recording apparatus according to the present invention. FIG. 4 is an enlarged view of the heat roller fixing device shown in FIG. 3; FIG. 5 is a diagram showing a positional relationship between a heater and a temperature sensor used in the first embodiment. FIG. 6 is a flowchart illustrating a temperature control sequence according to the first embodiment. FIG. 7 is a view showing a state of temperature control of a sheet passing portion and a non-sheet passing portion according to the first embodiment of the present invention in comparison with a conventional example. FIG. 8 is an enlarged view of a fixing device according to a second embodiment of the present invention using a non-contact type temperature sensor. FIG. 9 is a diagram showing a flowchart of temperature control according to a second embodiment of the present invention. FIG. 10 is a diagram showing a state of temperature control. FIG. 11 shows a flowchart of temperature control according to a third embodiment of the present invention. FIG. 12 is a diagram illustrating a state of an upper roller temperature change when a power supply voltage is low in the third embodiment of the present invention.
12A and FIG. 12B showing the state of the upper roller temperature change when the power supply voltage is high. DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Charger 3 Exposure unit 4 Developing unit 5 Transfer unit 6 Paper feed cassette 7 Timing roller 8 Separator 9 Conveyor belt 10 Heat roller fixing device 12 Fixing roller 13 Press-contact rollers 14, 15 Heater A , B H heater S temperature sensor

Continuation of the front page (72) Inventor Kazumi Ishii 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Corporation (56) References JP-A-59-177581 (JP, A) JP-A-5-289574 (JP, A) JP-A-5-181546 (JP, A) JP-A-4-139480 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (1)

(57) [Claim 1] A fixing roller having a built-in heater, a pressing roller which presses against and rotates cooperatively with the fixing roller, and a close non-contact which detects the temperature of the outer peripheral surface of the fixing roller. a temperature sensor, the temperature con for thermal Roratai Pujo desorbing device using capital
Turn on the heater in the image recording device equipped with the roller
Multiple control temperatures to turn on / off and when main switch is on
Having a set temperature for changing the control temperature of the
If the detected temperature at the time of heater ON by the main switch ON is lower than the set temperature , the controller sets the control temperature to the minimum.
Also the lower control temperature, switching then to the highest control temperature profile detecting the time and / or the fixing roller rotation time, and the detection result to one after another in a higher have temperature control temperature-out based from the warm-up completion , Main switch ON
The detected temperature when the heater is turned on is below the set temperature.
In the case of a heat roller type fixing device, the control temperature is set to the highest control temperature.
Image recording device provided with rollers .