JPH08185082A - Heating device - Google Patents

Abstract

PURPOSE: To provide a heating device not having deformation, alteration, a nasty smell, etc., caused by the abnormal heating of a heating roller. CONSTITUTION: The ratio of the ON times of both heaters of the heating roller and a pressure roller is set 1:1 (101), it is decided whether they are under rotation or not (102) and when they are under the rotation, it is decided whether a roller rotation starting temperature is obtained or not (103). When it is obtained, the rotation of a roller is started (104) and the start time of the rotation is held (105). However, when the heating roller and the pressure roller are not under the rotation, the time held at the time of starting the rotation is compared with the present time (106) and when a specified time or more lapses, the temperature variation of the pressure roller is measured (107), to calculate the quantity of heat required for the heating roller (108) and set the ratio of the ON times of both heaters (109). After that, it is decided whether VT>Vref is obtained or not (110), when VT>Vref is obtained, the rotation of the roller is stopped (112) and both heaters are turned off (113) and when VT<=Vref is obtained, both heaters are turned on at the set ratio (111) and then, it is decided that the heating roller and pressure roller are under the rotation or not again (102).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device used in an image forming apparatus such as an electrophotographic device and an electrostatic recording device.

[0002]

2. Description of the Related Art Conventionally, a heating method, particularly a heat roller fixing method, has been widely used for fixing an unfixed image in an electrophotographic apparatus or the like. In this system, basically, an unfixed image is supported between the heating roller and the pressure roller that is in pressure contact with the heating roller, and the recording material is passed through the unfixed image to fix the image.

FIG. 8 is a perspective view of an image heating apparatus for performing such heat fixing. However, driving motors, gears, etc. are not shown. In FIG. 8, 10 is a heating roller, 11 is a pressure roller as the other heating roller, and both rollers are rotatably arranged in pressure contact with each other in order to improve the fixing property of an image. Therefore, since the entire roller is deformed only by the heating roller 10 and the pressure roller 11 made of rubber, the core metal 1 is placed at the center of each roller.
5 and 17 are arranged to prevent deformation. That is,
The heating roller 10 and the pressure roller 11 have a core metal 15,
A core metal 17 and a core metal 17 are used to maintain the rigidity of the entire roller against the pressure applied between the heating roller 10 and the pressure roller 11. There is. Further, halogen heaters 5 and 18 which generate heat by power supply are arranged at the centers of the cores 15 and 17, and the temperature detecting means provided in contact with the surface of the pressure roller 11 as shown in FIG. Energization is controlled so that the resistance value of a certain thermistor 9 is constant with respect to the reference.

The heating roller 10 and the pressure roller 1 are also provided.
As shown in FIG. 9, a conveyance belt 13 is arranged in front of the recording paper 12 and a recording paper 12 which is conveyed in the direction of the arrow and which supports an unfixed powder toner image is attached to the heating roller 10 and the pressure roller 11. It is designed to be transported to the nip part of. Also,
Reference numeral 20 denotes a motor that rotates the heating roller 10 and the pressure roller 11. The motor 20 is driven when the recording paper 12 reaches the vicinity of the rollers.

When the recording paper 12 is thus sandwiched between the heating roller 10 and the pressure roller 11, the temperature of the roller is maintained at a predetermined temperature by the heaters 5 and 18 whose energization is controlled as described above. The unfixed toner image on the recording paper 12 is given heat and pressure and is fixed on the recording paper 12.

Therefore, in order to obtain a good fixing property, not only the pressure contact force between the rollers is maintained at a predetermined value as described above, but also the temperatures of the heating roller 10 and the pressure roller 11 are maintained at appropriate values. There is a need.

Therefore, in this conventional apparatus, the temperature control circuit as shown in FIG. 10 controls the temperature of the heating roller 10 and the pressure roller 11 and the drive control of the motor 20. In FIG. 10, 6 is a thermistor 9 and a resistor RT.
The digital value S1 from the voltage VT obtained by the voltage division ratio of
It is an A / D converter for obtaining 1. This voltage value V
The higher the temperature, the higher the value of T, and the temperature and voltage value VT
The relationship is as shown in FIG. That is, TMP1 <
When TMP5, V1 <V5. Further, 7 is an A / D for obtaining the digital value S12 from the control target voltage Vref.
It is a converter. The A / D converter 6 and the A / D converter 7 output digital values S11 and S12, respectively, to the control unit 21 which is a temperature control means, and the control unit 21 outputs S11 and S12.
According to the input of S12, the energization pattern signals S3 and S5 are controlled as shown in FIG. When the signals S3 and S5 are input to the power energization pattern generators 3 and 34, the heater control signals S4 and S6 are output to the heater drive circuits 4 and 19, and the halogen heaters 5 and 18 are AC-driven. ing.

Next, the conventional temperature control will be described with reference to the flowchart of FIG. First, the control target voltage Vref and the voltage VT are compared (step 201),
If Vref is larger than VT, energization pattern signal S3
And S5 are turned on (step 202), and if smaller than VT, energization pattern signals S3 and S5 are turned off (step 203). By such control, the heating roller 1
The temperatures of 0 and the pressure roller 11 are maintained at set temperatures as shown in FIG.

[0009]

However, according to the above-mentioned conventional example, the pressure roller 1 is constituted by one thermistor 9.
The two heaters 5 and 18 are controlled based on the temperature of 1. Therefore, when the heating roller 10 and the pressure roller 11 are stopped rotating, the heat is almost independent between the heating roller 10 and the pressure roller 11, so that the heater 5,
The temperature of the heating roller 10 not in contact with the thermistor 9 may be far from the set temperature due to variations in the amount of heat generated during manufacturing of 18, the heat flow, the air temperature, and the like.

FIG. 15 shows a heating roller 10 and a pressure roller 1.
1 shows the temperature of the pressure roller 11 and the temperature of the heating roller 10 when the rotation of No. 1 is stopped and the conventional temperature control is performed.
In this figure, the horizontal axis represents time and the vertical axis represents temperature.

Therefore, in the conventional example as shown in this figure, when the heating roller 10 and the pressure roller 11 are stopped rotating, the temperature of the heating roller 10 becomes abnormally high and the heating roller 10 and the pressure roller 11 are abnormally heated. Deformation, deterioration, and offensive odor could occur.

A first aspect of the present invention has an object to solve the above-mentioned problems and to provide a heating device which is free from deformation, deterioration, and odor due to abnormal heating of the heating roller.

Another object of the present invention is to provide a heating device having a configuration different from that of the first invention and capable of achieving the above object.

Further, the third invention according to the present application provides a heating device which is free from deformation, deterioration, odor and the like due to abnormal heating of the heating roller even when the temperature of the heating roller fluctuates due to fluctuations in outside air or the like. Is intended.

A fourth invention according to the present application aims to provide a heating device capable of achieving the above object by a configuration different from that of the third invention.

[0016]

According to the first invention of the present application, the above object is to provide a heating roller which is rotatably arranged in pressure contact with each other and which nips and conveys a recording material, and the heating roller. Two heating elements contained in each of them, which generate heat when energized, temperature detecting means for detecting the temperature of at least one of the heating rollers, and energization of the plurality of heating elements based on the temperature detected by the temperature detecting means. In a heating device provided with a temperature control means for controlling and maintaining the heating roller at a predetermined temperature, the energization ratio of the two heating bodies is
This is achieved by determining by the temperature change when the heating roller starts rotating.

According to the second invention of the present application,
The above-mentioned object is achieved in the above-mentioned first aspect of the invention by determining the energization start timing of the two heating bodies based on the temperature change when the heating roller starts rotating.

Further, according to the third invention of the present application, in the above-mentioned first invention, the energization ratio of the two heating bodies is set such that the heating roller is rotated at predetermined intervals.
This is achieved by determining the temperature change at that time.

According to the fourth invention of the present application,
The above-mentioned object is achieved in the above-mentioned first invention by determining the energization start timing of the two heating bodies by rotating the heating roller at predetermined time intervals and by the temperature change at that time.

[0020]

According to the first invention of the present application, since the heating elements of the two heating rollers are driven independently of each other, the heating value of each heating element may vary due to variations in heat generation, heat flow, temperature, etc. The temperature of the roller not in contact with the temperature detecting means tends to be far from the set temperature, but the temperature control means determines the energization ratio of each heating body by the temperature change when the heating roller starts rotating. So, correct the fluctuation from the above set temperature, give an appropriate amount of heat to the heating roller,
Prevents the temperature of the heating roller from rising and prevents deformation.

According to the second invention of the present application,
In the first aspect of the invention, the energization start timing of the two heating bodies is determined by the temperature change when the heating roller starts to rotate, so that the fluctuation from the set temperature is corrected and an appropriate amount of heat is applied to the heating roller. To prevent the temperature of the heating roller from rising and prevent deformation and the like.

Further, according to the third invention of the present application, in the above-mentioned first invention, the energization ratio of the two heating bodies is determined by rotating the heating roller every predetermined time and changing the temperature at that time. Therefore, even if the temperature of the heating roller fluctuates due to variations in the outside temperature, etc., correct it,
An appropriate amount of heat is applied to the heating roller to prevent the temperature of the heating roller from rising and to prevent deformation and the like.

According to the fourth invention of the present application,
In the first aspect of the invention, the energization start timing of the two heating bodies is determined by rotating the heating roller every predetermined time and changing the temperature at that time. Therefore, the temperature of the heating roller fluctuates due to variations in outside air temperature and the like. Even so, it is corrected so that an appropriate amount of heat is given to the heating roller to prevent the temperature of the heating roller from rising and prevent the occurrence of deformation or the like.

[0024]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. Note that FIG.
The same parts as those of the conventional example shown in FIG.

FIG. 1 shows a temperature control and drive control circuit of the heating apparatus according to the first embodiment of the present invention. In FIG. 1, 1
Is ON / OFF of the halogen heater 5 which is the heating body of the heating roller 10 and the halogen heater 18 which is the heating body of the pressure roller 11 which is the other heating roller, according to the digital value of the signal S11 from the thermistor 9 which is the temperature detecting means.
It is a control unit which is a temperature control means for controlling and controlling the ON / OFF drive signal of the motor 20.

The controller 1 has these heaters 5, 18
Power supply pattern generators 3, 34 for alternating current driving
Are connected, and the power energization pattern generators 3, 34 are connected.
The heater drive circuits 4 and 19 of the heaters 5 and 18 are connected to the.

Further, the control unit 1 is connected to a control unit 36 which is a time measuring means for measuring and holding time.

Further, a thermistor 9 is arranged so as to contact the pressure roller 11, and the control section 1 is an A / D.
The temperature of the pressure roller 11 is detected by the digital signal S11 via the converter 6. Further, the control unit 1 inputs the control target voltage Vref by the digital signal S12 via the A / D converter 7, and drives the heaters 5, 18 so that the control target voltage Vref and the voltage VT of the thermistor 9 become equal. Signals S3 and S5 are turned ON / OFF at the same time.

However, in such a temperature control circuit, when the heating roller 10 and the pressure roller 11 are stopped rotating, the heating roller 10 is abnormally heated due to manufacturing variations in the amount of heat generated by the heaters 5 and 18. May cause deformation, deterioration, and offensive odor.

Therefore, in the present embodiment, the ratio of the amount of heat applied to the heating roller 10 and the pressure roller 11 is based on the temperature change of the pressure roller 11 after the roller starts to rotate from the roller stop state when the apparatus is started up. This is to prevent abnormal heating of the heating roller 10. The rotation of the roller at the time of start-up is performed after turning on the heaters 5 and 18 for a predetermined time.

The method of determining the ratio of the amount of heat applied to the heating roller 10 and the pressure roller 11 and the temperature and motor control method in the control circuit shown in FIG. 1 will be described below.

FIG. 2 shows a flow chart of ON / OFF control of the heaters 5 and 18 in the control unit 1. First, the time ratio of turning on the heater 5 and the heater 18 is set to 1: 1 (step 101), and the heating roller 10 and the pressure roller 1 are set.
It is determined whether 1 is rotating (step 102),
If the temperature is during rotation, it is determined whether the temperature is the roller rotation start temperature (step 103). If the temperature is reached, the roller rotation is started (step 104) and the time when the rotation is started is held (step 105). .

However, when the rotation is not in progress, the time held at the start of rotation is compared with the current time (step 10
6) If the predetermined time or more has elapsed, the temperature change of the pressure roller 11 is measured (step 107), and the heating roller 10
Of the required heat is calculated (step 108), and the ON time ratio of the heater 5 and the heater 18 is determined (step 10).
9).

Thereafter, it is determined whether VT> Vref (step 110). If VT> Vref, roller rotation is stopped (step 112), and the heater 5 and the heater 1 are stopped.
8 is turned off (step 113), and if VT <= Vref, the heater 5 and the heater 18 are turned on at a set ratio (step 111), and the heating roller 10 and the pressure roller 11 are turned on again.
The routine returns to the routine for determining whether or not is rotating (step 102).

FIG. 3 shows the temperature change and the ON / OFF timing of each signal in the above control. In this figure, the vertical axis represents time and the vertical axis represents temperature.

As shown in the figure, even when the heating roller 10 and the pressure roller 11 are stopped, the heating roller 10
By applying an appropriate amount of heat to the heating roller 10, it is possible to prevent the temperature of the heating roller 10 from rising and prevent deformation and the like.

In the present embodiment, the case where the thermistor 9 is in contact with the pressure roller 11 has been described, but the thermistor 9 may be in contact with the heating roller 10. Further, the control unit 36 may be included in the control unit 1.

Further, in this embodiment, the heater 5 and the heater 1
The ON time ratio of 8 was decided, but the heater 5 is turned ON.
The time difference between the timing of turning on and the timing of turning on the heater 18 may be determined.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. The first
The same parts as those of the above embodiment are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 4, reference numeral 31 is a control unit corresponding to the control unit 1 in the first embodiment, and the control unit 31 is connected to a control unit 37 as a time measuring means.

In the first embodiment described above, the heating roller 10 and the pressure roller 11 are rotated at the time of starting the apparatus to determine the ON ratio of the heater 5 and the heater 18, but in the vicinity of the target temperature. If left for a long time, as shown in FIG. 5, the ratio of the required amount of heat between the heating roller 10 and the pressure roller 11 may change due to changes in the outside air temperature and the like. Therefore, in the present embodiment, the heating roller 10 and the pressure roller 11 are rotated for a predetermined period of time from the time when the target temperature is reached, and the necessary heat quantity is recalculated by the temperature change of the pressure roller 11 at that time. Is performed to prevent abnormal heating of the heating roller 10.

The method of determining the ratio of the amount of heat applied to the heating roller 10 and the pressure roller 11 and the temperature and motor control method in the control circuit shown in FIG. 4 will be described below.

FIG. 6 shows the heaters 5 and 18 in the controller 31.
The flowchart of ON / OFF decision of is shown. First, the time ratio of turning on the heater 5 and the heater 18 is set to 1: 1 (step 151), and the heating roller 10 and the pressure roller 1 are set.
It is determined whether 1 is rotating (step 152), and if it is rotating, it is determined whether it is the roller rotation start temperature (step 153). If the temperature is reached, roller rotation is started (step 153). 154), the time when the rotation is started is held (step 155). After that, it is determined whether or not a predetermined time has elapsed since the rotation was stopped (step 156). If the predetermined time has elapsed, the roller rotation is started (step 157) and the time when the rotation is started is held (step 158).

However, if the rotation is not in progress, the time held at the start of rotation is compared with the current time (step 15).
9) If the predetermined time or more has elapsed, the temperature change of the pressure roller 11 is measured (step 160), the necessary heat quantity of the heating roller is calculated (step 161), and the ON time ratio of the heater 5 and the heater 18 is calculated. Is determined (step 162), and the roller rotation is stopped (step 163). After this VT>
It is determined whether it is Vref (step 164), and VT>
If Vref, the heaters 5 and 18 are turned off (step 166), and if VT <= Vref, the heaters 5 and 18 are turned on at a set ratio (step 16).
5) Then, the process returns to the routine for determining whether the heating roller 10 and the pressure roller 11 are rotating again (step 152).

FIG. 7 shows the temperature change and the ON / OFF timing of each signal in the above control. In this figure, the vertical axis represents time and the vertical axis represents temperature.

As shown in the figure, when the heating roller 10 and the pressure roller 11 are stopped, the variation of the heat quantity of the heating roller 10 due to the variation of the outside air temperature,
By rotating the roller at regular intervals and calculating the amount of heat each time, it is possible to prevent the temperature of the heating roller 10 from rising and prevent deformation and the like.

In this embodiment, the case where the thermistor 9 is in contact with the pressure roller 11 has been described, but the thermistor 9 may be in contact with the heating roller 10. Further, the control unit 37 may be included in the control unit 1.

Further, in this embodiment, the heater 5 and the heater 1
The ON time ratio of 8 was decided, but the heater 5 is turned ON.
The time difference between the timing of turning on and the timing of turning on the heater 18 may be determined.

[0050]

As described above, according to the first invention of the present application, since the heating elements of the two heating rollers are driven independently, the variation in the amount of heat generated at the time of manufacturing each heating element. Due to heat flow, temperature, etc., the temperature of the roller not in contact with the temperature detection means tends to be far from the set temperature, but the temperature control means determines the energization ratio of each heating element and the heating roller starts to rotate. Since it is determined by the temperature change at that time, it is possible to correct the fluctuation from the set temperature, give an appropriate amount of heat to the heating roller, prevent the temperature of the heating roller from rising, and prevent deformation and the like.

According to the second invention of the present application,
In the first aspect of the invention, the energization start timing of the two heating bodies is determined by the temperature change when the heating roller starts to rotate, so that the fluctuation from the set temperature is corrected and an appropriate amount of heat is applied to the heating roller. It is possible to prevent the temperature of the heating roller from rising and prevent deformation and the like.

Further, according to the third invention of the present application, in the above-mentioned first invention, the energization ratio of the two heating bodies is determined by rotating the heating roller every predetermined time and changing the temperature at that time. Therefore, even if the temperature of the heating roller fluctuates due to variations in the outside temperature, etc., correct it,
It is possible to apply an appropriate amount of heat to the heating roller, prevent the temperature of the heating roller from rising, and prevent deformation and the like.

According to the fourth invention of the present application,
In the first aspect of the invention, the energization start timing of the two heating bodies is determined by rotating the heating roller every predetermined time and changing the temperature at that time. Therefore, the temperature of the heating roller fluctuates due to variations in outside air temperature and the like. However, it is possible to correct it to give an appropriate amount of heat to the heating roller, prevent the temperature of the heating roller from rising, and prevent deformation and the like.

[Brief description of drawings]

FIG. 1 is a diagram showing a temperature control circuit in a heating device according to a first embodiment of the present invention.

FIG. 2 is a flowchart of ON / OFF control of a heater in the control unit 1 according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a temperature change with respect to time in the first embodiment of the present invention.

FIG. 4 is a temperature control circuit diagram in the heating apparatus according to the second embodiment of the present invention.

FIG. 5 is a diagram showing a problem of the second embodiment of the present invention.

FIG. 6 is a flowchart of heater ON / OFF control in the control unit 31 according to the second embodiment of the present invention.

FIG. 7 is a diagram showing a temperature change with respect to time in the second embodiment of the present invention.

FIG. 8 is a perspective view of a heating device according to a second embodiment of the present invention.

FIG. 9 is a cross-sectional view of a heating roller for performing heat fixing according to the second embodiment of the present invention.

FIG. 10 is a diagram showing an example of a conventional heating roller temperature control circuit.

FIG. 11 is a diagram showing the relationship between the temperature of a conventional heating roller and the thermistor voltage.

FIG. 12 is a table of ON / OFF of conventional selection of digital values and energization patterns.

FIG. 13 is a flowchart of conventional temperature control.

FIG. 14 is a diagram showing a temperature change of a conventional heating roller.

FIG. 15 is a diagram showing a conventional problem.

[Explanation of symbols]

 1, 31 Control Unit (Temperature Control Unit) 5, 18 Halogen Heater (Heating Body) 9 Thermistor (Temperature Detection Unit) 10 Heating Roller 11 Pressure Roller (Heating Roller)

Claims (4)

[Claims] 1. A heating roller which is rotatably arranged in pressure contact with each other and which nips and conveys a recording material, two heating bodies which are respectively contained in each heating roller and generate heat when energized, and at least one of them is heated. The temperature detecting means for detecting the temperature of the roller, and the temperature control means for controlling the energization of the plurality of heating bodies based on the detected temperature of the temperature detecting means to maintain the heating roller at a predetermined temperature. In the heating device, the energization ratio of the two heating bodies is determined by the temperature change when the heating roller starts rotating. 2. The timing of starting energization of the two heating elements
The heating device according to claim 1, which is determined by a temperature change when the heating roller starts to rotate. 3. The heating device according to claim 1, wherein the energization ratio of the two heating elements is determined by rotating the heating roller at predetermined intervals and changing the temperature at that time. 4. The timing of starting the energization of the two heating elements,
The heating device according to claim 1, wherein the heating roller is rotated at predetermined time intervals, and the temperature is changed at that time.