JP2004295044A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of maintaining high image quality and contributing to energy saving while shortening warm-up time. <P>SOLUTION: A CPU 22 executes an actual heating value calculation program stored in a ROM 21 to calculate an actual heating value stored in a pressure roller 6 by using the lapse of time from the end of heating by a halogen heater 10 and the temperature of a belt 2 detected by a thermistor 11 as calculation elements. Then the CPU 22 executes a heat transmission variable control program stored in the ROM 21 to calculate an ideal heating value to be stored in the pressure roller 6. Then the CPU 22 executes the heat transmission variable control program stored in the ROM 21 to calculate a heat transmission variable from the belt to the pressure roller 6 by using a difference between the calculated actual heating value and the calculated ideal heating value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus that can maintain high image quality and contribute to energy saving while shortening a warm-up time.
[0002]
[Prior art]
2. Description of the Related Art As a conventional image forming apparatus, a printer disclosed in Patent Document 1 is known. The printer includes a fixing roller having a heating source, and a pressure roller driven by the fixing roller, and performs control to rotate the fixing roller until a predetermined temperature is reached during warm-up of the fixing roller. In this way, the warm-up time is reduced.
[0003]
[Patent Document 1]
JP-A-2002-40871 (see paragraphs [0040] and [0044])
[0004]
[Problems to be solved by the invention]
However, in this conventional image forming apparatus, since the rotation of the fixing roller is controlled based on the temperature of the fixing roller, paper feeding is started even if the temperature of the pressure roller does not reach the optimum temperature. There is a disadvantage that an image is generated. In addition, since control is performed so that the fixing roller reaches a preset temperature, excess heat is transmitted to the pressure roller, and energy is wasted.
[0005]
Accordingly, it is an object of the present invention to provide an image forming apparatus that can maintain high image quality while reducing warm-up time and contribute to energy saving.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, an image forming apparatus according to the present invention includes a heating unit that applies heat to a sheet, a pressing unit that is provided at a position facing the heating unit and applies pressure to a sheet, Actual heat amount calculation means for calculating the actual heat amount actually stored, and comparing the actual heat amount calculated by the actual heat amount calculation means with the ideal heat amount to be stored in the pressurizing means, from the heating means Heat transfer amount control means for outputting a control signal for controlling the amount of heat transferred to the pressurizing means.
[0007]
In the image forming apparatus according to the present invention, the heat transfer amount control unit determines an ideal heat amount using at least one of a sheet attribute, a powder ink attribute, an environmental temperature, and an ambient temperature as a determining factor. It has a configuration. Here, the attributes of the sheet refer to the properties of the sheet, such as the sheet thickness and the material of the sheet. The attribute of the powder ink refers to the properties of the powder ink, such as colors and raw materials. The environmental temperature refers to a temperature around the device such as a room temperature. The ambient temperature refers to the temperature around the pressure means.
[0008]
In the image forming apparatus according to the present invention, the actual heat amount calculating unit calculates the actual heat amount by using the temperature of the heating unit as one of the calculation elements.
[0009]
In the image forming apparatus according to the present invention, the actual heat amount calculating unit may calculate the actual heat amount by using a time lapse starting from the time when the heating unit ends heating as one of the calculation elements. have.
[0010]
The image forming apparatus according to the present invention includes a nip width control unit that controls a nip width generated between the heating unit and the pressing unit based on a control signal output by the heat transfer amount control unit. It has a configuration characterized by the following.
[0011]
The image forming apparatus according to the present invention may further include a driving speed control unit that controls a driving speed of at least one of the heating unit and the pressing unit based on a control signal output by the heat transfer amount control unit. It has a characteristic configuration.
[0012]
In the image forming apparatus according to the present invention, heat is circulated between the contacting / separating portion that can contact and separate from the pressurizing unit and a high-temperature portion located at a portion where the temperature becomes higher than the temperature of the pressing unit. A heat circulating means; and a contact / separation control means for controlling a contact / separation operation in the contact / separation part of the heat circulation means based on a control signal output by the heat transfer amount control means. are doing.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of an image forming apparatus according to the present invention will be described with reference to FIGS.
[0014]
(First Embodiment)
A configuration of a printer which is a first embodiment of the image forming apparatus according to the present invention will be described with reference to FIGS. As shown in FIG. 1, the printer 1 includes a belt 2, a pressing roller 3 for pressing the inner peripheral surface 2 a of the belt 2, a pressing pad 4 for pressing the inner peripheral surface 2 a of the belt 2, and an inner periphery of the belt 2. The tension roller 5 includes a tension roller 5 that presses the surface 2 a and a pressure roller 6 that faces the belt 2 and applies pressure to the outer peripheral surface 2 b of the belt 2.
[0015]
The belt 2 has a base made of a heat-resistant resin such as polyimide. The outer peripheral surface 2b of the belt 2 is coated with a release material such as fluororesin, and a heat-resistant elastic layer such as fluororubber is formed below the outer peripheral surface 2b of the belt 2.
[0016]
The pressing roller 3 has rotating shafts 3a at both ends. The rotating shaft 3a of the pressing roller 3 is rotatably supported by a support plate 7. The moving cam 8 is in contact with the support plate 7. When the moving cam 8 is rotated by a solenoid (not shown), the support plate 7 moves the rotating shaft 3 a of the pressing roller 3. When the rotating shaft 3a of the pressing roller 3 moves, the pressing force of the pressing roller 3 against the inner peripheral surface of the belt 2 changes. As a result, the width L0 of the nip generated between the outer peripheral surface 2a of the belt 2 and the pressure roller 6 changes.
[0017]
The tension roller 5 is stretched in the direction A by a spring 9 and presses the inner peripheral surface 2 a of the belt 2. The tension roller 5 is a thin metal roller, and applies heat generated by a halogen heater 10 provided inside the tension roller 5 to the belt 2. A thermistor 11 for detecting the temperature of the belt 2 is provided at a position facing the tension roller 5 via the belt 2.
[0018]
The pressure roller 6 is driven in the direction B by a motor (not shown). When the pressure roller 6 applies pressure to the belt 2, a frictional force is generated between the belt 2 and the pressure roller 6. Thus, the belt 2 is driven by the pressure roller 6, and when the pressure roller is driven in the B direction, the belt 2 moves in the C direction. When the belt 2 moves in the direction C, the sheet 13 on which the toner 12 is placed moves in the direction D and passes through the nip.
[0019]
Thus, the belt 2, the tension roller 5, and the halogen heater 10 have a function as a heating unit. The pressing roller 6 has a function as a pressing unit.
[0020]
As shown in FIG. 2, the printer 1 includes a ROM 21 for storing various programs, a CPU 22 for interpreting and executing various programs stored in the ROM 21, a RAM 23 for storing processing results of the CPU 22, and a thermistor. And an input unit 24 to which the signal of (i) is input, and a timer 25 for counting time.
[0021]
The ROM 21 compares the calculated actual heat amount with the ideal heat amount to be stored in the pressure roller 6 by comparing the calculated actual heat amount with the ideal heat amount to be stored in the pressure roller 6. A heat transfer amount control program that outputs a control signal for controlling the amount of heat transferred to the pressure roller 6, and a nip width generated between the belt 2 and the pressure roller 6 is controlled based on the output control signal. A nip width control program, an energization control program for controlling energization of the halogen heater 10 based on the output control signal, and a temperature monitoring program for monitoring whether the detected temperature of the thermistor 10 has reached a predetermined value are stored. Have been.
[0022]
As described above, the ROM 21 and the CPU have a function as an actual heat amount calculation unit, a function as a heat transfer amount control unit, and a function as a nip width control unit.
[0023]
Next, the characteristic operation of the copying machine according to the present embodiment will be described with reference to FIG. As shown in FIG. 3, when the power is turned on, the CPU 22 executes an actual heat amount calculation program stored in the ROM 21 to acquire information necessary for calculating the actual heat amount (step S1). Specifically, the CPU 22 executes the actual calorific value calculation program stored in the ROM 21 and obtains from the timer 23 a time lapse starting from the time when the halogen heater 10 ends heating as one of the calculation elements. Further, the CPU 22 executes the actual calorific value calculation program stored in the ROM 21 and acquires the temperature of the belt 2 detected by the thermistor 11 from the thermistor 11 as one of the calculation elements.
[0024]
When the information necessary for calculating the actual heat amount is acquired, the CPU 22 executes the actual heat amount calculation program stored in the ROM 21 to determine whether the time elapsed from the time when the halogen heater 10 has finished heating and the thermistor 11 have elapsed. The actual heat amount stored in the pressure roller 6 is calculated using the detected temperature of the belt 2 as a calculation element (step S2).
[0025]
Specifically, the temperature reduction rate of the belt 2 is calculated based on the relationship between the time elapsed from the time when the halogen heater 10 completes heating and the temperature of the belt 2 detected by the thermistor 11. Here, an actual heat amount table indicating the relationship between the temperature reduction rate of the belt 2 and the actual heat amount stored in the pressure roller 6 is prepared, and the calculated temperature reduction rate of the belt 2 is applied to the actual heat amount table. By doing so, the actual amount of heat stored in the pressure roller 6 is calculated.
[0026]
When the actual heat amount stored in the pressure roller 6 is calculated in step S2, the CPU 22 executes the heat transfer amount control program stored in the ROM 21 to determine the ideal heat amount to be stored in the pressure roller 6. It is calculated (step S3).
[0027]
Specifically, a table indicating the relationship between the above-described temperature reduction rate of the belt 2 and the environmental temperature is prepared. By applying the calculated temperature reduction rate of the belt 2 to the environmental temperature table, the environmental temperature can be reduced. Is calculated. Here, an ideal calorific value table showing the relationship between the environmental temperature and the ideal calorific value is prepared, and the ideal calorific value is calculated by applying the calculated environmental temperature to the ideal caloric value table. Further, it is desirable that an ideal calorie table be prepared in consideration of factors such as the thickness and material of the sheet, the color and raw material of the powder ink, and the ambient temperature around the pressure roller 6 in addition to the environmental temperature.
[0028]
In step S3, when the ideal heat amount to be stored in the pressure roller 6 is calculated, the CPU 22 executes the heat transfer amount control program stored in the ROM 21, and calculates the calculated actual heat amount and the calculated ideal heat amount. Is calculated, and the amount of heat transfer from the belt to the pressure roller 6 is calculated (step S4).
[0029]
When the heat transfer amount is calculated, the CPU 22 executes the nip width control means program stored in the ROM 21 to drive the moving cam 8 to control the nip width L0 (Step S5).
[0030]
Specifically, when the calculated heat transfer amount is large, the nip width L0 is controlled to be large, while when the calculated heat transfer amount is small, the nip width L0 is small. Controlled.
[0031]
As shown in FIG. 4, under the condition A where the nip width L0 is relatively wide, it takes time T0 for the belt 2 to reach the optimum temperature. On the other hand, under the condition B indicating that the nip width L0 is relatively narrow, it takes time T1 (T1 <T0) until the belt 2 reaches the optimum temperature. That is, the time required for the belt 2 to reach the optimum temperature is shorter when the nip width L0 is relatively narrow than when the nip width L0 is relatively wide. On the other hand, the temperature of the pressure roller 6 at the time T0 is higher when the nip width L0 is relatively wide than when the nip width L0 is relatively narrow. That is, the actual heat amount of the pressure roller 6 at the time T0 is larger when the nip width L0 is relatively wide than when the nip width L0 is relatively narrow.
[0032]
In step S5, when the nip width L0 is controlled, the CPU 22 executes an energization control program stored in the ROM 21 and performs heat transfer from the belt 2 to the pressure roller 6 based on the calculated heat transfer amount. Is calculated (hereinafter referred to as a warm-up time). Further, the CPU 22 executes an energization control program stored in the ROM 21 to start energization (hereinafter, referred to as warm-up) for the halogen heater 10 (step S6).
[0033]
When the warm-up is started, the CPU 22 executes an energization control program stored in the ROM 21 and determines whether the warm-up time has elapsed based on a signal from the timer 25. At the same time, the CPU 22 executes the temperature monitoring program stored in the ROM 21 and determines whether or not the detected temperature of the thermistor 11 has exceeded a predetermined value Tu based on the detection signal from the thermistor 11 (Step S7).
[0034]
If it is determined in step S7 that the detected temperature of the thermistor 11 has exceeded the predetermined value Tu, or if it has been determined that the warm-up time has elapsed, the CPU 22 executes the energization control program stored in the ROM 21. Then, the warm-up ends (step S8).
[0035]
As described above, according to the configuration of the present embodiment, the actual heat amount actually stored in the pressure roller 6 is compared with the ideal heat amount to be stored in the pressure roller 6, and the heat transfer from the belt 2 to the pressure roller 6 is performed. Since the amount of movement is controlled, the amount of heat transfer from the belt 2 to the pressure roller 6 is prevented from being excessively small or too small. That is, since the amount of heat transfer from the belt 2 to the pressure roller 6 is prevented from being excessive, the time for transferring excess heat is reduced, and the warm-up time can be shortened. Further, since the amount of heat transfer from the belt 2 to the pressure roller 6 is prevented from being excessive, the energy for generating extra heat is reduced, which can contribute to energy saving. On the other hand, since the amount of heat transfer from the belt 2 to the pressure roller 6 is prevented from being too small, the toner 12 is sufficiently melted, and the image quality can be maintained high.
[0036]
According to the configuration of the present embodiment, the ideal heat amount is determined using at least one of the attribute of the sheet 13, the attribute of the toner 12, the environmental temperature, and the ambient temperature, so that the heat from the belt 2 to the pressure roller 6 is determined. Is an amount suitable for at least one of the attribute of the sheet 13, the attribute of the toner 12, the ambient temperature, and the ambient temperature. In other words, the amount of heat transferred from the belt 2 to the pressure roller 6 is an amount suitable for at least one of the attribute of the sheet 13, the attribute of the toner 12, the environmental temperature, and the ambient temperature. Is further reduced, and the warm-up time can be further reduced. Further, the energy for generating extra heat is further reduced, which can contribute to energy saving. Further, the toner 12 is more sufficiently melted, and the image quality can be maintained higher.
[0037]
According to the configuration of the present embodiment, since the actual amount of heat is calculated using the temperature of the belt 2 as one of the calculation elements, it is accurate that the amount of heat transfer from the belt 2 to the pressure roller 6 is excessively large or small. Is prevented. That is, the amount of heat transferred from the belt 2 to the pressure roller 6 is accurately prevented from being excessive, so that the time for transferring excess heat is further reduced, and the warm-up time can be further reduced. . In addition, since the amount of heat transfer from the belt 2 to the pressure roller 6 is accurately prevented from being excessive, the energy for generating extra heat is further reduced, which can contribute to energy saving. On the other hand, the amount of heat transferred from the belt 2 to the pressure roller 6 is accurately prevented from being too small, so that the toner 12 is more sufficiently melted and the image quality can be maintained higher.
[0038]
According to the configuration of the present embodiment, the actual amount of heat is calculated by using the elapsed time from the time when the heating of the belt 2 is completed as one of the calculation elements, so that the heat transfer from the belt 2 to the pressure roller 6 is performed. Excessive and excessive amounts are precisely prevented. That is, the amount of heat transferred from the belt 2 to the pressure roller 6 is accurately prevented from being excessive, so that the time for transferring excess heat is further reduced, and the warm-up time can be further reduced. . In addition, since the amount of heat transfer from the belt 2 to the pressure roller 6 is accurately prevented from being excessive, the energy for generating extra heat is further reduced, which can contribute to energy saving. On the other hand, the amount of heat transferred from the belt 2 to the pressure roller 6 is accurately prevented from being too small, so that the toner 12 is more sufficiently melted and the image quality can be maintained higher.
[0039]
According to the configuration of the present embodiment, since the width of the nip generated between the belt 2 and the pressure roller 6 is controlled, the amount of heat transfer from the belt 2 to the pressure roller 6 is excessively small and small. Is prevented. That is, since the amount of heat transfer from the belt 2 to the pressure roller 6 is prevented from being excessive, the time for transferring excess heat is reduced, and the warm-up time can be shortened. Further, since the amount of heat transfer from the belt 2 to the pressure roller 6 is prevented from being excessive, the energy for generating extra heat is reduced, which can contribute to energy saving. On the other hand, since the amount of heat transfer from the belt 2 to the pressure roller 6 is prevented from being too small, the toner 12 is sufficiently melted, and the image quality can be maintained high.
[0040]
(Second embodiment)
With reference to FIG. 5, a characteristic portion of the image forming apparatus according to the second embodiment of the present invention will be described, and a description of a portion that is the same as that of the first embodiment will be omitted. The ROM 21 stores a drive speed control program for controlling the drive speed of the pressure roller 6 based on the control signal.
[0041]
As shown in FIG. 5, when the power is turned on, the CPU 22 executes the actual heat amount calculation program stored in the ROM 21 to obtain information necessary for calculating the actual heat amount (step S11).
[0042]
When the information necessary for calculating the actual heat amount is acquired, the CPU 22 executes the actual heat amount calculation program stored in the ROM 21 to determine whether the time elapsed from the time when the halogen heater 10 has finished heating and the thermistor 11 have elapsed. Using the detected temperature of the belt 2 as a calculation element, the actual amount of heat stored in the pressure roller 6 is calculated (step S12).
[0043]
When the actual heat amount stored in the pressure roller 6 is calculated in step S12, the CPU 22 executes the heat transfer amount control program stored in the ROM 21 to determine the ideal heat amount to be stored in the pressure roller 6. It is calculated (step S13).
[0044]
In step S13, when the ideal heat amount to be stored in the pressure roller 6 is calculated, the CPU 22 executes the heat transfer amount control program stored in the ROM 21, and calculates the calculated actual heat amount and the calculated ideal heat amount. Is calculated, and the amount of heat transfer from the belt to the pressure roller 6 is calculated (step S14).
[0045]
When the heat transfer amount is calculated, the CPU 22 executes the drive speed control program stored in the ROM 21 to control the drive speed of the pressure roller 6 (Step S15). Specifically, when the calculated heat transfer amount is large, the drive speed is controlled to increase, and when the calculated heat transfer amount is small, the drive speed is controlled to decrease. You.
[0046]
When the drive speed is controlled, the CPU 22 executes an energization control program stored in the ROM 21 and, based on the calculated amount of heat transfer, an energization time required for heat transfer from the belt 2 to the pressure roller 6. (Hereinafter referred to as a warm-up time). Further, the CPU 22 executes an energization control program stored in the ROM 21 to start energization (hereinafter, referred to as warm-up) of the halogen heater 10 (step S16).
[0047]
When the warm-up is started, the CPU 22 executes an energization control program stored in the ROM 21 and determines whether the warm-up time has elapsed based on a signal from the timer 25. At the same time, the CPU 22 executes the temperature monitoring program stored in the ROM 21 and determines whether or not the detected temperature of the thermistor 11 has exceeded a predetermined value Tu based on the detection signal from the thermistor 11 (Step S17).
[0048]
If it is determined in step S8 that the detected temperature of the thermistor 11 has exceeded the predetermined value Tu, or if it has been determined that the warm-up time has elapsed, the CPU 22 executes the energization control program stored in the ROM 21. Then, the warm-up ends (step S18).
[0049]
In the present embodiment, the driving speed of the pressure roller 6 is controlled because the belt 2 is driven by the pressure roller 6. However, when the pressure roller 6 is driven by the belt 2, Is controlled.
[0050]
According to the configuration of the present embodiment, since the driving speed of at least one of the belt 2 and the pressure roller 6 is controlled, the amount of heat transfer from the belt 2 to the pressure roller 6 may be excessive or insufficient. Is prevented. That is, since the amount of heat transfer from the belt 2 to the pressure roller 6 is prevented from being excessive, the time for transferring excess heat is reduced, and the warm-up time can be shortened. Further, since the amount of heat transfer from the belt 2 to the pressure roller 6 is prevented from being excessive, the energy for generating extra heat is reduced, which can contribute to energy saving. On the other hand, since the amount of heat transfer from the belt 2 to the pressure roller 6 is prevented from being too small, the toner 12 is sufficiently melted, and the image quality can be maintained high.
[0051]
(Third embodiment)
With reference to FIGS. 6 to 8, a description will be given of a characteristic portion of the image forming apparatus according to the third embodiment of the present invention, and a description of a portion overlapping with the first embodiment will be omitted. As shown in FIG. 6, a hollow annular pipe 17 is provided at a position facing the pressure roller 6. A wick layer is formed inside the annular pipe 17, and a liquid is sealed as a heat transfer medium. The liquid has a function of increasing the efficiency of heat transfer because its thermal conductivity is several hundred times the thermal conductivity of metal.
[0052]
As shown in FIG. 7, the annular pipe 17 has two parallel portions 17a and 17b parallel to the axial direction of the rotating shaft 3a of the pressing roller 3. The parallel portion 17a of the annular pipe 17 is always in contact with the inner peripheral surface 2a of the belt 2. On the other hand, the parallel portion 17b of the annular pipe 17 comes into contact with and separates from the pressure roller 6 according to the operation of the moving tool 18.
[0053]
Thus, the annular pipe 17 has a function as a heat circulation unit. The parallel portion 17a of the annular pipe 17 has a function as a high-temperature portion. The parallel portion 17b of the annular pipe 17 has a function as a contact / separation portion.
[0054]
Further, the ROM 21 stores a contact / separation control program for controlling the contact / separation operation of the parallel portion 17a of the annular pipe 17 based on the control signal. Thus, the ROM 21 and the CPU 22 have a function as a contact / separation control unit.
[0055]
Next, a characteristic operation of the third embodiment will be described with reference to FIG. As shown in FIG. 8, when the power is turned on, the CPU 22 executes the actual heat amount calculation program stored in the ROM 21 to acquire information necessary for calculating the actual heat amount (step S21).
[0056]
When the information necessary for calculating the actual heat amount is acquired, the CPU 22 executes the actual heat amount calculation program stored in the ROM 21 to determine whether the time elapsed from the time when the halogen heater 10 has finished heating and the thermistor 11 have elapsed. The actual amount of heat stored in the pressure roller 6 is calculated using the detected temperature of the belt 2 as a calculation element (step S22).
[0057]
When the actual heat amount stored in the pressure roller 6 is calculated in step S22, the CPU 22 executes a heat transfer amount control program stored in the ROM 21 to determine an ideal heat amount to be stored in the pressure roller 6. It is calculated (step S23).
[0058]
In step S23, when the ideal heat amount to be stored in the pressure roller 6 is calculated, the CPU 22 executes the heat transfer amount control program stored in the ROM 21, and calculates the calculated actual heat amount and the calculated ideal heat amount. Is calculated, and the amount of heat transfer from the belt to the pressure roller 6 is calculated (step S24).
[0059]
When the heat transfer amount is calculated, the CPU 22 executes the contact / separation control program stored in the ROM 21 and, based on the calculated heat transfer amount, causes the parallel portion 17 b of the annular pipe 17 to move with respect to the pressure roller 6. Is calculated (corresponding to the warm-up time) (step S25).
[0060]
Specifically, if the calculated heat transfer amount is large, a decision is made to lengthen the contact / separation time, while if the calculated heat transfer amount is small, a decision is made to shorten the contact / separation time. You.
[0061]
When the contact time is calculated in step S25, the CPU 22 executes the contact / separation control program stored in the ROM 21 to move the moving tool 18 so that the parallel portion 17b of the annular pipe 17 contacts the pressure roller 6. Control the operation of. At this time, the CPU 22 executes the energization control program stored in the ROM 21 to energize the halogen heater 10 (step S26).
[0062]
When the contact is started, the CPU 22 executes the contact / separation control program stored in the ROM 21 and determines whether or not the contact time has elapsed based on a signal from the timer 25. At the same time, the CPU 22 executes the temperature monitoring program stored in the ROM 21 and determines whether or not the detected temperature of the thermistor 11 has exceeded a predetermined value Tu based on the detection signal from the thermistor 11 (Step S27).
[0063]
If it is determined in step S8 that the detected temperature of the thermistor 11 has exceeded the predetermined value Tu, or if it has been determined that the contact time has elapsed, the CPU 22 executes the contact / separation control program stored in the ROM 21. Then, the operation of the moving tool 18 is controlled so that the parallel portion 17b of the annular pipe 17 is separated from the pressure roller 6 (Step S28).
[0064]
As described above, according to the configuration of the present embodiment, the parallel portion 17b of the annular pipe 17 that can be brought into contact with and separated from the belt 2 and the parallel portion 17a of the annular pipe 17 that is located at a temperature higher than the temperature of the pressure roller 6 Since the heat circulation using the liquid as the medium is performed between the two, the transfer amount of heat from the belt 2 to the pressure roller 6 is prevented from being excessively large or small. That is, since the amount of heat transfer from the belt 2 to the pressure roller 6 is prevented from being excessive, the time for transferring excess heat is reduced, and the warm-up time can be shortened. Further, since the amount of heat transfer from the belt 2 to the pressure roller 6 is prevented from being excessive, the energy for generating extra heat is reduced, which can contribute to energy saving. On the other hand, since the amount of heat transfer from the belt 2 to the pressure roller 6 is prevented from being too small, the toner 12 is sufficiently melted, and the image quality can be maintained high.
[0065]
【The invention's effect】
According to the present invention, the actual amount of heat actually stored in the pressurizing unit is compared with the ideal amount of heat to be stored in the pressurizing unit, and the amount of heat transfer from the heating unit to the pressurizing unit is controlled. In addition, the amount of heat transferred from the heating means to the pressurizing means is prevented from being excessively large or small. That is, since the amount of heat transfer from the heating means to the pressurizing means is prevented from being excessive, the time for transferring excess heat is reduced, and the warm-up time can be shortened. Further, since the amount of heat transferred from the heating unit to the pressurizing unit is prevented from being excessive, the energy for generating excess heat is reduced, which can contribute to energy saving. On the other hand, since the amount of heat transfer from the heating means to the pressurizing means is prevented from being too small, the powder ink is sufficiently melted and the image quality can be maintained at a high level.
[Brief description of the drawings]
FIG. 1 is a partial side view illustrating a configuration of an image forming unit of a copying machine according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of a copying machine according to the first embodiment of the present invention;
FIG. 3 is a flowchart showing the operation of the copying machine according to the first embodiment of the present invention;
FIG. 4 is a graph showing a relationship between an elapsed time, a belt temperature, and a pressure roller temperature.
FIG. 5 is a flowchart showing the operation of the copying machine according to the second embodiment of the present invention;
FIG. 6 is a partial side view illustrating a configuration of an image forming unit of a copying machine according to a third embodiment of the present invention.
FIG. 7 is a partial front view showing the configuration of a copying machine according to a third embodiment of the present invention.
FIG. 8 is a flowchart illustrating the operation of a copying machine according to a third embodiment of the present invention;
[Explanation of symbols]
2 belt (heating means)
5 tension roller (heating means)
6 pressure roller (pressure means)
10. Halogen heater (heating means)
17 Annular pipe (heat circulation means)
18 Moving equipment (heat circulation means)
21 ROM (actual heat amount calculation means, heat transfer amount control means, nip width control means, drive speed control means, contact / separation control means)
22 CPU (actual heat amount calculation means, heat transfer amount control means, nip width control means, drive speed control means, contact / separation control means)

Claims (7)

Heating means for applying heat to the sheet;
Pressing means for applying pressure to the sheet provided at a position facing the heating means,
An actual calorie calculating means for calculating an actual calorie actually stored in the pressurizing means,
The actual heat amount calculated by the actual heat amount calculation means is compared with the ideal heat amount to be stored in the pressurizing means, and a control signal for controlling the amount of heat transfer from the heating means to the pressurizing means is output. An image forming apparatus comprising: a heat transfer amount control unit. 2. The image forming apparatus according to claim 1, wherein the heat transfer amount control unit determines an ideal amount of heat using at least one of a sheet attribute, a powder ink attribute, an environmental temperature, and an ambient temperature as a determining factor. The image forming apparatus according to claim 1, wherein the actual heat amount calculating unit calculates the actual heat amount using the temperature of the heating unit as one of the calculation elements. 4. The actual heat amount calculation unit according to any one of claims 1 to 3, wherein the actual heat amount calculation unit calculates the actual heat amount by using a time lapse starting from a time point when the heating unit ends heating as one of the calculation elements. The image forming apparatus according to any one of the preceding claims. 2. A nip width control unit that controls a nip width generated between the heating unit and the pressurizing unit based on a control signal output by the heat transfer amount control unit. Item 5. The image forming apparatus according to any one of Items 4. 6. The apparatus according to claim 1, further comprising a driving speed control unit that controls a driving speed of at least one of the heating unit and the pressurizing unit based on a control signal output by the heat transfer amount control unit. The image forming apparatus according to any one of the above. A heat circulating unit that circulates heat between a contacting / separating unit that can contact and separate from the pressurizing unit and a high-temperature portion located at a site that is higher than the temperature of the pressing unit,
7. An apparatus according to claim 1, further comprising contact / separation control means for controlling a contact / separation operation in said contact / separation part of said heat circulating means based on a control signal output by said heat transfer amount control means. An image forming apparatus according to any one of the above.

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