JP3497401B2 - Heating temperature control method and heating temperature control device in heat fixing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control method in a fixing device for thermally fixing an unfixed toner image,
In particular, the present invention relates to a temperature control method capable of realizing optimum fixing temperature setting by using a plurality of heaters.

[0002]

2. Description of the Related Art Conventionally, as a technique for thermally fixing an unfixed toner image formed by an electrophotographic apparatus or the like, a heat roller system in contact with toner or a surf system using a seamless belt, and a hot plate not in contact with toner are used. Although there are methods, flash methods, infrared lamp methods, oven methods, dielectric heating methods, etc., the toner contact method is the mainstream in terms of thermal efficiency.

On the other hand, in the toner contact method, especially in the heat roller method, in order to reduce the power consumption, a thin fixing roller method in which the heat capacity of the roller is reduced is often adopted. However, in the case of a thin fixing roller type, heat flow in the longitudinal direction deteriorates due to thinning, and heat retention occurs in the non-paper passing area, for example, and when paper with a small paper width is continuously passed, The temperature rises excessively, and an offset phenomenon or the like is likely to occur.

In order to solve such a defect, the number of heaters inserted in the heating roller is arranged in a plurality of two to several heaters, and the energization of each heater is controlled according to the size of the paper to be passed. It was Further, such a technique of inserting a plurality of heaters to control energization is applicable not only to the thin-wall fixing roller system, but also to other heat roller systems, surf systems, and toner non-contact heating systems. Kaisho 5
No. 7-148779 is a heat fixing system using a preheating plate, which comprises a plurality of heat generating heaters and first and second temperature control elements, controls the first temperature control element heat fusion temperature, and The temperature control element controls the temperature unevenness caused by the paper width. However, controlling the plurality of heaters while the two temperature control elements perform different heating controls complicates the control circuit and easily causes malfunctions.

Further, in Japanese Patent Laid-Open No. 62-124581, one of a plurality of heaters is selected from the viewpoint that the fixing roller not only radiates heat to the transfer material but also radiates much to the peripheral portion. There is disclosed a technique in which one of the temperature sensors is arranged so that the amount of heat applied to both ends of the roller is large, and this heater is controlled to be turned off with a delay from other heaters.

However, this technique is based on the premise that a large amount of heat is radiated to the peripheral portion of the roller. For example, when an exhaust heat fan for radiating heat of the fixing roller is arranged in the fixing roller axial direction, the fan suction position Cooling air flows from the one end side of the farthest roller toward the other end side that is the closest, so that the temperature of one end side of the roller farthest from the fan suction position is low,
There is a problem that the temperature of the other end side closest to the other end becomes the highest.

[0007]

That is, to explain the above-mentioned problems again, even if a plurality of heaters are provided in the roller, the signal detected by the temperature sensor is only a value around the temperature sensor. Therefore, to control a plurality of heating heaters with one temperature sensor, it is necessary to obtain the correlation between the temperature detected at the temperature sensor position and each heating heater. When controlling the ON / OFF of multiple heaters, when passing small size paper, various variations of exhaust heat load such as the position of the exhaust fan, the paper passing interval, etc. are mixed, and a uniform correlation is not always obtained. Absent. On the other hand, if a temperature detector is provided for each heater, the heating control circuit becomes complicated.

In order to solve such a problem, the present invention provides a heating temperature control method and a heating temperature control device in a heat fixing device capable of performing accurate temperature control with a simple control circuit even when a plurality of heaters are used. The purpose is to do.

[0009]

In order to solve such a problem, the present invention provides two or more N's as described in claim 1.
The present invention relates to a heating temperature control method in a thermal fixing device including individual heating heaters and a temperature detection sensor of (N-1) or less. That is, the present invention mainly aims to precisely control heating of a plurality of heating heaters by one temperature detection sensor, but not only this, but a fixing temperature detection sensor which is one or more less than N heating heaters. Any heat fixing device equipped with can be applied. (For example, the heater is 3
(If there are four, there are two sensors, if there are four heaters, then there are two sensors, etc.)

Further, in the present invention, a heating temperature control method in a thermal fixing device comprising two or more N heaters and (N-1) or less temperature detection sensors,
(N-1) The following heaters (hereinafter referred to as main heaters) are controlled for lighting time based on the temperature detected by the temperature detection sensor, and the continuous lighting time of the main heater is compared with a predetermined determination time. Based on the determination result, the remaining heaters other than the main heater (hereinafter referred to as sub heaters)
Continuous lighting time of the main heater continuous lighting time
It is characterized by determining whether or not to change.

For example, in the present invention, when the determination result indicates that the continuous lighting time of the main heater exceeds the determination time, the continuous lighting time of the sub heater is increased or decreased, and the determination result indicates that When the continuous lighting time of the main heater is equal to or less than the determination time, the auxiliary heater is controlled in lighting in synchronization with the lighting control of the main heater.

To specifically explain the present invention, for example, there is one main heater and one sub-heater (N: 2), and one temperature detection sensor is arranged close to the main heater. Assuming that the sub-heater has a larger (smaller) amount of heat than the main heater due to the influence of the exhaust fan, etc., the heat amount of the sub-heater is large when the main heater is turned on for a long time, such as in the initial stage of starting the fixing roller. It may be insufficient (excessive). On the other hand, in the case of normal temperature control in which the lighting time of the main heater is short, it is preferable to synchronize the lighting time of the sub heater with that of the main heater in order to achieve uniform heat distribution. Therefore, the lighting time of the sub heater is increased (decreased) from the lighting time of the main heater when the lighting time of the main heater is longer than a predetermined determination time. On the other hand, when the lighting time of the main heater is within the predetermined determination time, it is preferable to control the lighting in synchronization. The invention according to claim 2 is characterized in that the determination time is varied based on a variation factor of the fixing temperature such as the fixing load.

That is, the deviation of the temperature distribution between the main heater and the sub heater is not always constant, and when the fixing temperature is raised,
Difference in environmental temperature due to seasonal differences, whether continuous or intermittent paper passing,
Differs depending on the recording paper size and other factors. When the fixing temperature is raised, the fixing is performed in the winter season, the intermittent paper is passed, or the print fixing of a small size recording paper is performed, the deviation is likely to be large. In this case, the determination time is shortened and the auxiliary heater The lighting time is increased (decreased) from the lighting time of the main heater
Increase the frequency.

On the other hand, the deviation is likely to be small during normal fixing, fixing in summer, continuous paper feeding, or print fixing of macro-sized recording paper. In this case, the judgment time is lengthened and the auxiliary heater is used. The frequency of increasing (decreasing) the lighting time of the above from the lighting time of the main heater is reduced. This makes it possible to control heating with even distribution in the axial direction with higher accuracy.

Therefore, according to the present invention, the lighting time of the heater is measured by controlling at least one heating heater with the temperature sensor, the lighting time of the other heating heaters is determined, and the lighting time of the heating heater is determined. It is characterized in that the optimum temperature control can be realized by setting the temperature. In the present invention, for example, the temperature sensor and the heating temperature of the thermal fixing device equipped with the thermal fixing device is a heating roller, one of the main heater, and one of the sub-heater
It is a heating temperature control device that controls according to the detected temperature of
Te, the main heater comprises a first and a second heating coil provided in an end portion of the heating roller, the first heating coil is longer than the second heating coil, the auxiliary heater is the An exhaust fan is arranged at the end of the heating roller located between the first and second heating coils in the longitudinal direction of the heating roller, and is separated from the first heating coil. the main perform lighting time control of the heater, the main heater of the continuous lighting time and a predetermined determination time and the continuous lighting time of the sub heater based on the determination result by comparing, continuous of the main heater based on When lit
Control is performed to determine whether or not to change. Further, it is desirable that the temperature detection sensor is arranged corresponding to the first heating coil.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be exemplarily described in detail below with reference to the drawings. However, unless otherwise specified, the types of components, circuits, relative arrangements, operation sequences, etc. described in this embodiment are not intended to limit the scope of the present invention thereto, but merely illustrative examples. Nothing more.

FIG. 1 is a heat fixing device of a thin fixing type applied to the present invention, (A) is an overall schematic sectional view, and (B) is a vertical sectional view showing an internal structure of a heating roller 2. In FIG. 1, reference numeral 1 is a pressure roller, which is formed by winding a low hardness pressure rubber layer 1b around the outer circumference of a roller shaft 1a. Reference numeral 2 denotes a heating roller, which is formed by coating the outer peripheral surface of a thin roller member 2a made of carbon steel with a fluorine coating or a thin silicon rubber layer 2b. Further, the fixing device employs so-called center paper feeding in which conveyance papers of different sizes are symmetrically distributed to the left and right with the center of the heating roller 2 as a center. Therefore, the heating heater inserted in the heating roller 2 is adopted. The heating coils 3 and 4 are also provided in the central part and on the left and right sides thereof, respectively.
a, 3b, 4a a halogen lamp distributes the pressurized
Heat heater A (3) (main heater) and heater B (4)
Two (auxiliary heaters) are inserted.

That is, the two heaters A (3) and B (4) are arranged in parallel in two horizontal rows, and the heating coil 3a of the heater A (3),
3b (first and second heat generating coils) are located on the left and right sides, and the heat generating coil 4a of the heater B (4) is located at the central portion to facilitate the temperature control described later. In the heater A (3), the heat generating coils 3a and 3b arranged on the left and right sides of the roller have a small number of turns on the left side of the drawing, and the number of turns on the right side is large. This is because the heat generating coil 3a on the right side of the drawing has a larger heat absorbing energy taken along the exhaust flow. In the present embodiment, a thermistor or other temperature sensor 7 is arranged on the right end side of the outer peripheral surface of the heating roller 2, which faces the heat generating coil 3a on the right side in the drawing, which has the largest heat removal energy by the exhaust flow. Therefore, the temperature sensor 7 is heated by the heater A facing the heating roller 2.
(3) is directly controlled to be turned on / off, while the heater B (4) is the heater A (3).
The ON / OFF control is performed in synchronism with the lighting time of, or delayed as necessary. Incidentally, reference numeral 5 in the drawing denotes an unfixed toner image, which is carried on the conveying paper 6.

Next, the operation of this embodiment will be described in detail with reference to FIG. The heater A (3) causes the surface temperature of the heating roller 2 to change to the control temperature T in response to a signal from the temperature sensor 7.
It is controlled so as to be turned on when the value becomes c or less. With respect to the ON / OFF timing of the heater A (3), the heater B (4) determines whether the lighting time TA of the heater A (3) exceeds a predetermined determination time Ts, and the predetermined determination time Ts is exceeded. When it is longer than Ts, the lighting time (TB = TA + Tp) of the heater B (4) becomes longer by the additional lighting time Tp.

[0020]

This point will be described with reference to the flow chart shown in FIG. Heater A by (S1)
(3) is a heating roller in response to a signal from the temperature sensor 7.
When the surface temperature of 2 becomes equal to or lower than the control temperature Tc, it is turned on. Then, the heater B (4) is turned on at (S2) in synchronization with the ON timing of the heater A (3), and further at (S3), the lighting time TA of the heater A (3) is set.
Is longer than the predetermined judgment time Ts, and if it is longer than the predetermined judgment time Ts, the heater A (3)
Is turned off (S4), the timer for setting the additional lighting time Tp is turned on (S5), and when the lighting time (TB) of the heating heater B (4) exceeds (TA + Tp) (S6), the heating heater B (4) is turned off (S7).

On the other hand, the lighting time TA of the heater A (3)
Is shorter than the determination time Ts, the heating heater B (4) is turned off in synchronization with the turning-off operation (S4 ′) of the heating heater A (3) without turning on the timer for setting the additional lighting time Tp. (S7 ').

Next, the experimental results of a concrete prototype will be shown. The inventors of the present invention have modified the electrophotographic printer E having a linear velocity of 100 mm / sec as a base and modified it to obtain a linear velocity of 150.
We have developed a printer F that has a high speed of mm / sec. In the printer F, the amount of exhaust heat air around the fixing device is increasing in response to the increase in the heat generation amount of the fixing device due to the higher speed.
The problem cannot be dealt with only by changing the number of turns of the heating coils arranged on the left and right sides of the roller in (3). That is, due to the increase in the amount of the exhaust heat air, the heated air moves to the side closer to the exhaust fan 8 and stays there, and the surface temperature of the heating roller 2 increases. In this embodiment, since the exhaust fan 8 is provided on the side opposite to the temperature sensor 7, the temperature sensor 7 is used to heat the heater A.
Even if (3) is controlled, if the lighting time (TB = TA + 3) of the heating heater B (4) is automatically lengthened without determining the lighting time TA of the heating heater A (3),
The lengthened energy becomes excess energy, and the temperature easily rises at the center of the heating roller 2.

The experimental results are shown in FIG. Figure 3 (A)
As shown in (B) and (B), even when the printers E and F have the same control, the temperature of the center part whose temperature is controlled by the heater B (4) is 10 ° C. higher in F than in E. Therefore,
As shown in (C), the lighting time of the heater A (3) is determined based on 5 seconds, and if it is less than that, the heater B is heated.
As a result of not performing the additional lighting in (4), the temperature rise in the center portion became equivalent to that of the engine E. Further, under a condition where the fixing device is not sufficiently heated, such as immediately after the power is turned on, a large amount of heat is taken by the pressure roller and the surroundings, so that the lighting time of the heater A (3) becomes longer than 5 seconds. Since the lighting time of B (4) is further added by 3 seconds, the heat quantity does not become insufficient in the center portion.

In FIG. 4A, a technique for making the judgment time variable is also added. For the determination time Ts, the signals of various sensors 7 provided in the electrophotographic apparatus are calculated by the CPU 9
C based on the measured values of the various sensors 7 described above.
A predetermined determination condition is calculated on the PU 9 side, and the memory map 10
The judgment time based on the judgment condition is selected from the above. For example, when the ambient temperature is the winter / summer temperature based on the temperature detected by the ambient temperature detection sensor 11, the determination time is changed, and when the recording papers of different sizes are inserted, this is also detected by the size detection sensor 12. Different judgment time.

The operation will be described with reference to the flow chart of FIG. First, the environmental temperature detection sensor 11
Based on the detected temperature (S10) of (1), it is determined in (S11) whether the environmental temperature is 15 ° C. or higher. In (S12), the size of the conveyed paper is first detected by the cassette detection sensor 12 or the like (S1
3) For example, when the size is A4 or larger, the determination time is 5 seconds (S15), and when fixing a small size paper smaller than A4 size, the heat load of the heater B (4) having a heating coil in the center becomes large. And the determination time is 3 seconds (S1
4), the lighting time (TB) of the heater B (4) is set to be long even when the on / off cycle of the heater A (3) is short. On the other hand, when the environmental temperature is 15 ° C. or higher, it is determined that it is summer and the process proceeds to (S13 ′). (S13 ')
Similarly, in the procedure of 1,
For example, when the size is A4 size or more, the determination time is set to 5 seconds (S15 ′) as in the winter season, but when fixing a small size paper smaller than A4 size, Since the uneven distribution of the heat load in the center does not become so large as compared with the winter season, the determination time is relaxed from 3 seconds to 4 seconds (S14 ').

FIG. 5 shows the determination time Ts of the heater B (4).
Shows a control pattern in which the heater A (3) is set to a judgment time Ts of 5 seconds.
For example, the lighting time of 2 seconds and 4 seconds, heater B
The case where the additional lighting of (4) is not performed is shown. Pattern 2
Indicates that the determination time Ts is set to 3 seconds, and only when the lighting time of the heater A (3) is 3 seconds or more, the lighting time of the heater B (4) is added by the time Tp.

The experimental results of a concrete prototype are shown below. FIG. 6 shows experimental results of an electrophotographic printer having a linear velocity of 100 mm / sec. As shown in patterns 1 and 2, the determination time Ts is set to 5 seconds in the pattern 1 and 3 seconds in the pattern 2, and only when the lighting time of the heater A (3) is longer than the determination time Ts, the heater B (4 The lighting time of) was set longer by 3 seconds. And the ambient temperature is 15 ℃
In the following winter, when the A4 plain paper and the A5 thick paper are inserted, respectively, and when A4 plain paper is inserted, the heater B
The control temperature of the center portion heated by (4) is + 3 ° C. and the determination time is 3 seconds in the pattern 1 with the determination time of 5 seconds, compared to the temperature detector 7 controlled by the heater A (3). In pattern 2, it can be understood that + 13 ° C. and the judgment time of 5 seconds are more advantageous.

On the other hand, when A5 thick paper is inserted, the control temperature of the center portion heated by the heater B (4) is determined by the judgment time for the temperature detector 7 controlled by the heater A (3). It can be understood that it is more advantageous that the pattern 1 of 5 seconds has a temperature of −8 ° C. and the pattern 2 having the determination time of 3 seconds has a determination time of + 1 ° C. and the determination time of 3 seconds.

If the fixing time is set to 5 seconds and the fixing device is not sufficiently heated, such as immediately after the power is turned on, a large amount of heat is taken away by the pressure roller and its surroundings.
The lighting time of the heater A (3) is longer than 5 seconds,
In any of the above patterns, the heater B (4)
Since the lighting time of is added by 3 seconds, the heat quantity does not become insufficient in the center portion even in the pattern 2.

[0031]

As described above, according to the present invention, in the fixing device having a plurality of heaters, at least one heating heater is controlled to a predetermined temperature, and then the surface of the heating roller is controlled by the exhaust heat condition or the like. It can be expected that the uneven temperature distribution can be easily corrected without changing the heat quantity distribution of the heater. Further, according to the present invention, it is sufficient to have a sensor for controlling at least one heater to a predetermined temperature, and there is an effect that a temperature sensor corresponding to a plurality of heaters is not required. Further, only when the heating heater has a long continuous lighting time immediately after the power is turned on or the like, the continuous lighting time of another heating heater can be added to raise the temperature of the portion of the heating roller where the heat radiation amount is large. Therefore, there is an effect that secondary adverse effects resulting from complicated heater control and complicated circuit configuration are prevented. Further, according to the present invention, since at least one heater is controlled to a predetermined temperature, there is an effect that a plurality of temperature detectors are unnecessary.

Further, according to the present invention, in a fixing device having a plurality of heaters, at least one heating heater is controlled to a predetermined temperature, and then the plurality of heaters are controlled without changing the heat quantity distribution of the heaters. Thus, it is possible to expect an effect that the temperature distribution of the heated portion of each heater can be corrected by a simple operation of changing the determination time.

[Brief description of drawings]

1A and 1B are a thin-wall fixing type thermal fixing device applied to the present invention, in which FIG. 1A is an overall schematic sectional view, and FIG. 1B is a vertical sectional view showing an internal structure of a heating roller.

FIG. 2 is a graph showing an example of a lighting control pattern of each heater by a plurality of heaters according to the invention of claim 1.

3 is a table showing experimental results of temperature rise according to the embodiment of FIG. 2 in a specific electrophotographic printer.

FIG. 4A is a flow chart showing the overall operation procedure of the present invention, and FIG. 4B shows a subroutine procedure for variably controlling the determination time.

FIG. 5 is a graph showing an example of a lighting control pattern of each heater by a plurality of heaters in the invention according to claim 2;

6 is a table showing experimental results of temperature rise according to the embodiment of FIG. 5 in a specific electrophotographic printer.

[Explanation of symbols]

1 pressure roller 3 Heater A 4 Heater B 5 Toner image before fixing 6 Transport paper before fixing 7 Temperature sensor

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (5)

(57) [Claims] 1. N heaters of 2 or more and (N-
1) In a heating temperature control method in a thermal fixing device having the following temperature detection sensors, (N-1) heating heaters (hereinafter referred to as main heaters) are controlled for lighting time based on the temperature detected by the temperature detection sensors. The continuous heating time of the main heater is compared with a predetermined judgment time, and the remaining heaters other than the main heater (hereinafter referred to as sub-heaters) based on the judgment result.
Continuous lighting time of the main heater continuous lighting time
A heating temperature control method, which comprises deciding whether or not to change. 2. The heating temperature control method according to claim 1, wherein the determination time is varied based on a fixing load and other factors of variation of the fixing temperature. 3. The main heater of the main heater is determined based on the determination result.
If the continuous lighting time exceeds the judgment time, the continuous lighting time of the auxiliary heater is increased or decreased, and the judgment result shows that the continuous lighting time of the main heater is equal to or less than the judgment time. 3. The heating temperature control method according to claim 1 or 2, wherein the auxiliary heater is controlled to be lit in synchronization with the lighting control of the main heater. 4. A heating temperature control device for controlling a heating temperature of a thermal fixing device comprising a heating roller, one main heater, and one sub-heater according to a temperature detected by a temperature detection sensor, The heater includes a first heater provided at an end of the heating roller.
And a second heat generating coil, the first heat generating coil is longer than the second heat generating coil, and the sub-heater is connected to the first and second heat generating coils in the longitudinal direction of the heating roller. An exhaust fan is arranged at an end of the heating roller positioned between the first heating coil and the first heating coil, and the lighting time of the main heater is controlled on the basis of the detected temperature to continuously connect the main heater. the lighting time and a predetermined determination time and by comparing the determination result to the continuous point <br/> lamp time of the sub heater based, to determine whether to change the continuous lighting time of the main heater A heating temperature control device characterized by performing control. 5. The heating temperature control device according to claim 4, wherein the temperature detection sensor is arranged corresponding to the first heating coil.