JP3067395B2 - Fixing device temperature control method and 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 method for controlling the temperature of a fixing device for heating and fixing a toner image on a recording sheet in a copying machine, a printer, or the like. The present invention relates to a method for controlling the temperature of a fixing device having a heater.

[0002]

2. Description of the Related Art Conventionally, as a fixing device of this type, among a pair of rolls abutting on the front and back of a recording sheet, a heater is provided only in a roll abutting on a surface side of a recording sheet carrying a toner image. Was mainstream. Speaking of the temperature control of the heater, a certain target temperature is set in advance, and the heater is energized only when the surface temperature of the roll in which the heater is installed falls below the target temperature, and the surface temperature of the roll is constantly controlled. Control was performed to match the target temperature.

However, in a so-called full-color copying machine, four colors of cyan, magenta, yellow and black are used.
Since the unfixed toner image is formed by stacking the color toners, if the unfixed toner image is heated only from the surface side of the recording sheet, sufficient heat energy is transmitted to the lowermost layer toner in contact with the recording sheet. However, there was a problem that the fixability deteriorated. Further, in consideration of its color developing properties, a full-color recorded image needs to be applied with sufficient thermal energy to the toner as compared with a monochrome recorded image.

For this reason, in recent years, a fixing device has also been proposed for use in a full-color copying machine or the like, in which a heater is also provided inside a roll that comes into contact with the back side of a recording sheet.
However, in a fixing device in which a heater is provided inside each of the rolls abutting on the front and back of the recording sheet, how to control the temperature of each roll is an important problem. Because a copier or printer incorporating this type of fixing device is designed on the assumption that it will be used with a household power supply of 100 V, it is not possible to energize both heaters at the same time because of the rated current. This is because only one of the heaters can be energized. Hereinafter, specific temperature control methods conventionally proposed and their problems will be described.

First, as a first method, a target temperature is set for each of two rolls, and when only the surface temperature of one of the rolls is lower than the target temperature, the heater of the roll is energized. Further, when the surface temperatures of the two rolls are both equal to or lower than the target temperature, a method of alternately energizing the respective heaters for a predetermined time is used. However, the efficiency with which the rolls in contact with the front and back of the recording sheet contribute to the fixing of the unfixed toner image, that is, the heat energy given to the toner by each roll for a certain period of time depends on the surface roll on the front side which directly contacts the unfixed toner image. Is larger than the back side roll. Therefore, in the case where the surface temperature of the roll is remarkably lowered as in the case of continuous copying or the like, it is possible to use the thermal energy accumulated in each roll efficiently by energizing the heater of the front roll preferentially. . In this regard, in this control method, since the same amount of heat energy is given to the rolls that come into contact with the front and back of the recording sheet, the excess heat energy tends to be accumulated in the rolls that come into contact with the back side, which is limited. There is a problem that the heat energy cannot be used efficiently.

Next, as a second method, in consideration of the problems of the first method, when both of the surface temperatures of the two rolls are equal to or lower than the target temperature, the heater of the front roll is preferentially energized. Has been proposed. That is, unless the surface temperature of the front roll reaches the target temperature, the heater of the rear roll is not energized. However, in a fixing device in which a heater is provided on both the front side roll and the back side roll, if the surface temperature of the back side roll is somewhat high, sufficient fixability can be obtained even if the front side roll is lower than the target temperature. In some cases, this control method heats the surface roll more than necessary, resulting in extremely low energy efficiency.

Further, in continuous copying or the like, the surface temperature of the roll cannot reach the target temperature during the copying operation. Therefore, in this control method, once the copying operation is started, the copying operation is completed and the front side is stopped. Until the surface temperature of the roll returns to the target temperature, the heater of the front-side roll is always energized. Therefore, the inside of the front side roll becomes higher than the target temperature by about 50 ° C before the heater is turned off, and as a result, the roll surface temperature becomes higher than the target temperature by 20 ° C to 30 ° C, so-called overshoot. There was a problem that a phenomenon occurred.

By the way, in the conventional fixing device, in connection with the temperature control of the roll in which the heater is installed, a control means for judging that the fixing is impossible when the surface temperature of the roll falls below a predetermined minimum fixable temperature is provided. Provided. However, as described above, in a fixing device in which the rolls that come into contact with the front and back of the recording sheet each include a heater, when the surface temperature of the back side roll changes, it is necessary to reproduce a predetermined fixing property. The minimum temperature of the front roll also changes. Therefore, it is extremely inconvenient to determine whether fixing is possible or not based on a fixed minimum fixing temperature as in the related art. In other words, it may be determined that fixing is impossible when fixing is actually possible, or vice versa. There is no.

[0009]

As described above, in the conventional temperature control method, unnecessary heat energy not contributing to the fixing of the unfixed toner image is accumulated in each roll, and the energy efficiency is extremely low. It had a bad effect on itself. In addition, the determination as to whether fixing is possible or not is not accurate, which deteriorates the operation efficiency of a copying machine or a printer and impairs the reliability of fixing.

In view of the above problems of the present invention, a first object of the present invention is to suppress accumulation of useless heat energy that does not contribute to fixing on a roll, and to obtain good heat energy with little heat energy. It is an object of the present invention to provide a fixing device temperature control method and a fixing device capable of performing fixing. A second object of the present invention is to provide a fixing device temperature control method capable of accurately determining whether fixing is possible or not, and improving operation efficiency and reliability. .

[0011]

In order to achieve the above object, the present invention proposes four temperature control methods for a fixing device and an apparatus for implementing the methods.

First, a first temperature control method comprises a first roll having a first heating means therein, and a second roll disposed in contact with the first roll and having a second heating means therein. A temperature control method of a fixing device that heats and fixes a toner image on a recording sheet sent from an image forming apparatus, the method including an image fixing mode executed during an image forming operation of the image forming apparatus, The image fixing mode is a target surface temperature required for the second roll to reproduce the fixability of a predetermined toner image from the actually measured temperature value X of the first roll.
a calculating step of calculating y, a calculating temperature comparing step of comparing the target surface temperature y and the actually measured temperature value Y of the second roll, and driving the first heating means or the second heating means based on the comparison result. And a fixing control step.

[0013] Further, an apparatus for performing this method includes:
As shown in FIG. 1, a first roll 1 having a first heating means 1a therein, a second roll 2 disposed in contact with the first roll 1 and having a second heating means 2a therein, First temperature detecting means 5 for detecting the surface temperature of the first roll 1 and second temperature detecting means 6 for detecting the surface temperature of the second roll 2
And a control unit for controlling the first heating unit 1a and the second heating unit 2a, and a fixing device for heating and fixing the toner image 3 on the recording sheet 4 sent from an image forming apparatus (not shown). In the above, the control means comprises an image fixing mode executing means functioning during an image forming operation of the image forming apparatus, and the image fixing mode executing means is an actual measured temperature value of the first roll 1 by the first temperature detecting means 5. A calculating means 7 for calculating a target surface temperature y required for the second roll 2 in order to reproduce a predetermined fixing property from X, and a second roll 2 based on the target surface temperature y and the second temperature detecting means 6 And a fixing-time driving unit 9 that drives the first heating unit 1a or the second heating unit 2a based on the comparison result.

In the fixing device to which the method of the present invention is applied, since the first roll and the second roll contacting the front and back of the recording sheet each have a heating means, the fixing property of the toner image to the recording sheet is two. The surface temperatures of the rolls are determined in relation to each other. That is, even if the surface temperature of the first roll is reduced, if the surface temperature of the second roll is increased to a degree that compensates for it, the same fixing property as before the temperature change can be secured. Here, the surface temperature of the first roll is x
Then, the surface temperature y required for the second roll to reproduce a fixed fixing property is a fixing characteristic equation y = f where x is a variable.
It is represented by (x).

Therefore, in the image fixing mode of the method of the present invention,
The target surface temperature y of the second roll required to reproduce the predetermined fixing property from the actually measured surface temperature X of the first roll y =
f (X) was calculated, and the target surface temperature y was compared with the actually measured surface temperature Y of the second roll. And
When the measured surface temperature Y of the second roll is lower than the target surface temperature y (Y <y), the measured temperature value Y of the second roll exceeds the target surface temperature y, that is, Y ≧ y. Thus, the first heating means provided in the first roll or the second heating means provided in the second roll is driven.

At this time, if the second heating means is driven, the actually measured temperature value Y of the second roll rises, so that it is natural that the relationship of Y ≧ y is obtained. The same result can be obtained by driving. This is because when the measured temperature value X of the first roll increases, the target surface temperature of the second roll calculated from the measured temperature value decreases. However, since a roll in contact with the front side of the recording sheet gives a larger amount of heat energy to the toner image than a roll in contact with the back side of the recording sheet, it is better to heat the roll in contact with the front side of the recording sheet. It is preferable in terms of energy efficiency, and a relationship of Y ≧ y can be obtained in a short time.

Although FIG. 1 shows a configuration in which the second roll 2 is in contact with the front side of the recording sheet 4, a configuration in which the first roll 1 is in contact with the front side of the recording sheet 4 may be used.

In order to specify the fixing characteristic equation y = f (x), the inventor of the present application calculates the surface temperature x of the first roll and the surface temperature y of the second roll when the toner images exhibit the same fixing property. combination
Measure a number of (x, y), the horizontal axis is the surface temperature x of the first roll,
The measured values were plotted on a graph using a coordinate system whose vertical axis indicates the surface temperature y of the second roll. As a result, FIG.
As a result, a straight line graph y = Ax + B as shown in FIG.
Therefore, in the embodiment of the present invention described later, this fixing characteristic formula: y
= Ax + B is used to calculate the target surface temperature y of the second roll.

In the fixing characteristic equation, the coefficient A is a ratio of the efficiency at which the first roll and the second roll contribute to fixing of the toner image. For example, as shown in FIG. 5, when the surface temperature x of the first roll decreases by 20 ° C., the surface temperature of the second roll decreases.
If the same fixing property is ensured by increasing y by 10 ° C., the coefficient A becomes −1/2. When the first roll is in contact with the back side of the recording sheet, the coefficient A is considered to be a value of about -1/2 to -1/3, but slightly varies depending on the material and structure of each roll. Therefore, this coefficient A is a different value for each fixing device, and is experimentally determined by sequentially confirming the fixability of the toner image when the combination of the surface temperatures (x, y) of each roll is arbitrarily changed. You can ask.

The coefficient B indicates the degree of fixability of the toner image, and can be arbitrarily selected according to the required fixability. That is, if the coefficient B is selected to be a large value, the target temperature value y = AX + B of the second roll calculated using the actually measured temperature value X of the first roll becomes a high value. The total amount of heat energy applied to the toner image from the roll increases, and the fixability of the toner image improves. Conversely, if the coefficient B is selected to be a small value, the target temperature value y = AX + B of the second roll becomes a low value, so that the total amount of heat energy given to the toner image from the first roll and the second roll is And the fixability of the toner image decreases.

The total amount of heat energy required for fixing a toner image varies depending on the image forming operation of an image forming apparatus such as a copying machine or a printer. A large-sized recording sheet has a larger total amount of heat energy required for fixing than a small-sized recording sheet, and a color toner image has a larger total amount of heat energy required for fixing than a single-color toner image. Therefore, it is preferable to select the coefficient B for each image forming operation of the image forming apparatus. As shown in FIG. 1, a specific apparatus includes a coefficient determining unit 10 in which a plurality of coefficients B ₁ , B ₂ , B ₃ ,... Corresponding to various image forming operations of the image forming apparatus are provided in advance. The specific coefficient _BN is provided to the calculating means in accordance with the information of the image forming operation inputted from the CPU of the above.

In the image fixing mode proposed by the first method, as shown in FIG. 5, the actual measured temperature value Y of the second roll is calculated by using the actual measured temperature value X of the first roll. A
If larger than X + B (Y ≧ y), the predetermined fixability determined by the coefficient B is reproduced on the recording sheet, so that any one of the first heating unit and the second heating unit is used. Need not be driven. Therefore, if the second roll is high temperature, even when the measured temperature value X of the first roll is extremely low, Y ≧
Since the relationship y is established, the heating means is not driven at all. However, if the toner image is fixed in this temperature state, a large amount of heat energy is taken from the second roll because the heat energy given to the recording sheet by the first roll is small, and the surface temperature of the second roll becomes extremely high. There is an adverse effect of lowering. Also, in this temperature state, if the measured temperature value Y of the second roll is lower than the target surface temperature y (Y <y), the second heating means may be driven to further increase the temperature of the second roll, There is also a risk that an overshoot phenomenon occurs.

[0023] Thus, in this image fixing mode, provided the reference temperature comparing step of comparing the measured temperature values X of the first roll and the reference temperature value X ₁ of the first roll defined arbitrarily, Y ≧
Even when the relationship of y is satisfied, the comparison result by the reference temperature comparison step to drive the first heating means if it is X <X _1, to restore the surface temperature of the first roll to the reference temperature value X ₁ or more Is preferred. In the specific apparatus, a reference temperature comparing unit 11 is newly provided as shown by a broken line in FIG. 1, and the fixing driving unit 9 drives the first heating unit 1a based on the comparison result of the reference temperature comparing unit 11. It is configured to

According to the first temperature control method, the energization control of each of the heating means 1a and 2a during the image forming operation of the image forming apparatus is executed based on the fixing characteristic equation obtained experimentally. Therefore, for example, if the surface temperature of the first roll is high to some extent, even if the surface temperature of the second roll is low, there is an opportunity to cut off the power supply to the second heating means provided in the second roll, This has the advantage that heat energy need not be applied to each roll. Also, whether or not the heating means is energized is determined by the surface temperatures of the two rolls being correlated with each other. Can be cut off, and the occurrence of the overshoot phenomenon in each of the rolls 1 and 2 can be effectively prevented. Further, there is an advantage that a certain fixing property expressed by a fixing characteristic formula can be guaranteed for the toner image fixed on the recording sheet.

The first temperature control method of the present invention described above relates to the image fixing mode for the image forming operation of the image forming apparatus. This is effective when the two heating means cannot be driven simultaneously. However, when the image forming apparatus is not performing image formation, for example, when the copying machine is in a copy waiting state or when the main power is turned on for the first time, power consumption other than that of the fixing device is small. And the second heating means can be driven simultaneously.
Therefore, in such a case, by driving both the first heating means and the second heating means and accumulating a large amount of heat energy in each roll, the subsequent fixing operation can be stabilized. Also, when the main power of the copying machine is turned on, the copying operation cannot be performed unless each roll of the fixing device reaches a predetermined temperature. There is an advantage that time can be reduced.

Therefore, a second temperature control method of the present invention is as follows.
An image fixing mode that is executed during an image forming operation of the image forming apparatus, and a standby mode that is executed while the image forming apparatus is in an image forming standby state, wherein the standby mode is an arbitrarily defined first roll. The first fixed temperature comparison step of comparing the standby surface temperature X ₀ and the measured temperature value X of the first roll, and the standby surface temperature Y ₀ of the second roll arbitrarily determined and the measured temperature of the second roll The second fixed temperature comparison step of comparing the value Y, the first roll control step of driving the first heating means based on the comparison result of the first fixed temperature comparison step, and the second fixed temperature comparison step A second roll control step of driving the second heating means based on the comparison result.

Further, an apparatus for carrying out this method includes:
A control unit for controlling the first heating unit and the second heating unit includes a standby mode execution unit that functions during image formation standby of the image forming apparatus, and the image fixing mode execution unit. as such, the standby mode executing means, the first fixing temperature comparing means 12 for comparing the measured temperature values X of the stand surface temperature X ₀ and the first roll 1 first roll 1 defined arbitrarily, optionally The second roll specified in
The second fixed temperature comparing means 13 which compares the standby surface temperature Y _{0 of} 2 with the actually measured temperature value Y of the second roll 2, and the first heating means based on the comparison result of the first fixed temperature comparing means 12. 1a
And a second roll driving means 15 for driving the second heating means 2a based on the comparison result of the second fixed temperature comparing means 13.

[0028] In this standby mode, the driving of the first heating means only from the magnitude relation between the waiting surface temperature X ₀ and the measured temperature value X of the first roll is determined and also the actually measured temperature value Y of the second roll driving the second heating means is determined only from the size relationship between the standby surface temperature Y _0. For this reason, depending on the measured temperature value (X, Y) of each roll, two heating means are driven simultaneously, and the measured temperature value (X, Y) of each roll is always changed to the standby surface temperature (X ₀ , Y) in the shortest time. Control that leads to ₀ ) is performed.

As the standby surface temperature (X ₀ , Y ₀ ), as shown in FIG. 5, a high temperature capable of sufficiently reproducing the fixability of the toner image expected in the image fixing mode is used. Therefore, when the target surface temperature y = f (X ₀ ) of the second roll calculated using the standby surface temperature X ₀ of the first roll is compared with the standby surface temperature Y ₀ of the second roll, the comparison result is naturally Y ₀ ≧ y = f
(X ₀ ).

FIG. 6 is a timing chart showing the correspondence between the image forming operation of the image forming apparatus and each mode. Since it is impossible to simultaneously drive the two heating units during the image forming operation of the image forming apparatus, in the second temperature control method, when the image forming apparatus starts the image forming operation, the standby mode is terminated, and The image fixing mode is executed instead.
The switching from the image fixing mode to the standby mode may be synchronized with the end of the image forming operation of the image forming apparatus as shown in FIG. 6, or may be switched at a predetermined timing from the end of the image forming operation. .

By the way, in this second temperature control method,
Since sufficient heat energy is accumulated in each roll in the standby mode, there occurs a time when neither the first heating unit nor the second heating unit is driven at the beginning of the image fixing mode. Because, in the standby mode, control is performed to match the measured temperature value (X, Y) of each roll to the standby surface temperature (X ₀ .Y ₀ ). Immediately after, it is considered that the measured temperature value (X, Y) of each roll is located near the standby surface temperature (X ₀ .Y ₀ ), and the target surface temperature y of the second roll calculated in the image fixing mode Is naturally smaller than the actually measured temperature value Y of the second roll. Therefore, when the mode is switched from the standby mode to the image fixing mode, the measured temperature values (X, Y) of the respective rolls are set in the regions shown in FIG.
Neither the first heating means nor the second heating means is driven unless moving from P to region Q.

However, when an image forming operation is started in the image forming apparatus, the thermal energy of each roll is consumed by the fixing of the toner image.
Moves rapidly from the area P to the area Q. As described above, it is important that the measured temperature value (X, Y) of each roll exists in the region P in order to reproduce a predetermined fixing property. Therefore, in the second temperature control method, there is a concern that the fixability of the toner image may be deteriorated early in a large amount of continuous copying or the like.

Therefore, a third temperature control method of the present invention is as follows.
The standby mode, the image fixing mode, and, if necessary, a transition mode executed at the beginning of image formation of the image forming apparatus, wherein the transition mode includes the first fixed temperature comparison step, A second fixed temperature comparing step, and a transition control step of driving the first heating means or the second heating means based on a comparison result of the first fixed temperature comparing step and the second fixed temperature comparing step. It is characterized by the following.

An apparatus for performing the method is as follows.
A control unit that controls the first heating unit and the second heating unit, wherein the standby mode execution unit, the image fixing mode execution unit, and, if necessary, a transition mode in which the image forming apparatus functions at the beginning of image formation. Execution mode, as shown in FIG. 3, the transition mode execution means, the first fixed temperature comparison means 12, the second fixed temperature comparison means 13, the first fixed temperature comparison means 12 and The first heating means based on the comparison result of the second fixed temperature comparison means 13
And the transition driving means 16 for driving the first heating means 1a or the second heating means 2a.

The difference between the transition mode and the standby mode is whether or not the first heating means and the second heating means are simultaneously driven. In the transition mode, since the image forming apparatus has already started image formation, the first heating unit and the second heating unit cannot be driven simultaneously. Therefore,
As a result of the fixed temperature comparison means comparing the measured temperature value of each roll (X, Y) with the standby target temperature (X ₀ , Y ₀ ), the measured temperature value of each roll is lower than the standby target temperature (X <X ₀ , Y <Y ₀ )
Is determined, only one of the heating means is driven. It is optional to drive either the first heating unit or the second heating unit, but it is preferable to heat the roll in contact with the front side of the recording sheet from the viewpoint of energy efficiency.

FIG. 8 is a timing chart showing the correspondence between the image forming operation of the image forming apparatus and each mode. Although the start of the transition mode is synchronized with the start of image formation of the image forming apparatus,
Switching from the transition mode to the image fixing mode may be at an arbitrary predetermined timing. However, when switching from the transition mode to the image fixing mode, if the measured temperature value (X, Y) of each roll exists in the region P shown in FIG. 7, the same problem as in the second temperature control method occurs. Therefore,
It is preferable to switch from the transition mode to the image fixing mode when the measured temperature value (X, Y) of each roll moves to the region Q.
Specifically, it is the time when the comparison result between the target surface temperature y of the second roll and the actually measured temperature value Y of the second roll becomes Y <y for the first time after the image forming apparatus starts image formation.

When the number of recording sheets on which images have been continuously formed reaches a predetermined number n, the mode may be switched from the transition mode to the image fixing mode. The number n is such that the measured temperature value (X, Y) of each roll exists in the area p at least when an image is formed on the nth recording sheet, and the image is recorded on the (n + 1) th recording sheet. This is a value determined on the assumption that the actual temperature value (X, Y) of each roll moves to the region Q when the formation is performed. As described above, since the total amount of heat energy required for fixing the toner image differs for each image forming operation of the image forming apparatus,
Is preferably selected from a plurality of n ₁ , n ₂ , n ₃ ,... Prepared in advance and the most appropriate value corresponding to the image forming operation at that time is used.

Further, the timing of switching from the transition mode to the image fixing mode may be a time when a predetermined time t has elapsed from the start of image formation by the image forming apparatus. In this case, it is preferable that the time t is selected from a plurality of t ₁ , t ₂ , t ₃ ,... Prepared in advance and the most appropriate value corresponding to the image forming operation of the image forming apparatus is used. .

When the timing of switching from the transition mode to the image fixing mode is determined according to the number of recording sheets and the elapsed time as described above, the actual measurement of each roll at the time when the image fixing mode is started is performed. It is preferable to determine the coefficient B of the fixing characteristic equation: y = Ax + B using the temperature value (X _N , Y _N ). That is, the coefficient B can be obtained from at B = Y _N -AX _N. If the coefficient B is determined in this way, the actually measured temperature values (X, Y) of each roll at the beginning of the image fixing mode must be as shown in FIG.
, The inconvenience that none of the heating means is driven at the time of switching from the transition mode to the image fixing mode can be avoided.

By the way, in the image fixing mode of the present invention, the target surface temperature y of the second roll required for reproducing the arbitrarily determined predetermined fixing property is calculated from the measured temperature value X of the first roll. Thus, the minimum surface temperature y _L of the second roll necessary to ensure the lowest fixing property acceptable recorded image also can be calculated from the measured temperature value X of the first roll. Then, by comparing the minimum surface temperature y _L of the second roll obtained by the calculation with the actually measured temperature value Y of the second roll, it is accurately determined whether or not this fixing device can fix the toner image on the recording sheet. You can judge.

Therefore, the fourth temperature control method of the present invention is as follows.
With a diagnosis mode executed in the image forming operation of the image forming apparatus, the diagnostic mode, it calculates the minimum surface temperature y _L required for the second roll from the measured temperature values X of the first roll operation A minimum temperature comparison step of comparing the minimum surface temperature y _L with the actually measured temperature value Y of the second roll, and a self-diagnosis step of determining whether fixing is possible or impossible based on the comparison result. It is characterized by the following.

Further, a fixing device for carrying out this method includes a first roll 1 having a first heating means 1a therein, and a fixing device disposed in contact with the first roll 1 and having a second heating means 2a therein. The second roll 2 having, the first temperature detecting means 5 for detecting the surface temperature of the first roll 1, the second temperature detecting means 6 for detecting the surface temperature of the second roll 2, the first heating Control means 17 for controlling means 1a and said second heating means 2a
And a diagnostic mode executing means for determining whether the fixing operation can be performed or cannot be performed, wherein the diagnostic mode executing means determines the second roll from the measured temperature value X of the first roll 1 by the first temperature detecting means 5. A calculating means 18 for calculating the minimum surface temperature y _L required for the second 2, and a minimum temperature comparing means for comparing the minimum surface temperature y _L and the actually measured temperature value Y of the second roll 2 by the second temperature detecting means 6. 19 and self-diagnosis means 20 for determining whether fixing is possible or impossible based on the comparison result.

The function for calculating the minimum surface temperature y _L of the second roll is a fixing characteristic equation used in the image fixing mode: y
= Ax + B, fixing coefficient y _L = AX +
C is used. The coefficient C is a coefficient indicating the minimum fixing property of the toner image, and has a relation of B ≧ C with the coefficient B indicating an arbitrary fixing property. Since this coefficient C varies depending on the total amount of heat energy required for fixing the toner image, a plurality of values are prepared according to the thickness and the material of the recording sheet or the difference in the number of colors of the toner image. It is preferable to keep it.

[0044]

According to the first temperature control method of the present invention having the image fixing mode, the target temperature y of the second roll required to reproduce a predetermined fixing property is calculated from the measured temperature value X of the first roll. It calculates and drives the first heating means or the second heating means based on the result of comparison between the target temperature y and the actually measured temperature value of the second roll, so that unnecessary heat energy is always applied to each roll without adding unnecessary heat energy to each roll. In addition to securing a fixed fixing property, it is possible to effectively prevent an overshoot phenomenon caused by applying too much heat energy to the roll.

According to the second temperature control method of the present invention comprising the image fixing mode and the standby mode, either one of the first and second heating means is used during the image forming operation of the image forming apparatus. Drive, while securing the minimum heat energy required to reproduce the predetermined fixing property, while driving the first heating means and the second heating means during the image forming standby of the image forming apparatus, A constant amount of heat energy is always stored in each roll. Therefore, excess heat energy can be stored in each roll during image formation standby with sufficient power, so that, for example, in continuous copying or the like, it is possible to prevent insufficient heat energy during the fixing operation to deteriorate the fixability. Can be prevented as much as possible.

According to the third temperature control method of the present invention comprising the image fixing mode, the standby mode and the transition mode, it is possible to avoid a state in which none of the heating means is driven at the beginning of the image fixing mode. Thus, it is possible to prevent the surface temperature of each roll from rapidly dropping immediately after the fixing operation is started.

[0047] Furthermore, according to a fourth temperature control method of the present invention with a diagnostic mode, the minimum surface temperature y _L of the second roll required for fixing the toner image on the recording sheet of the first roll calculated from the measured temperature values X, since the diagnosing fixable or fixed non based on the comparison result between the measured temperature value of the a target temperature y _L second roll, the heat energy to be held in the first roll And the thermal energy held by the second roll are closely related to each other to determine whether fixing is possible or impossible. Therefore, it is possible to strictly and accurately determine whether fixing is possible or not.

[0048]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a fixing device according to an embodiment of the present invention;

(1) Apparatus Configuration FIG. 9 shows a basic configuration example of a fixing device according to the present invention. In the figure, reference numeral 21 denotes a first roll having a heater 21a therein, and reference numeral 22 denotes a second roll having a heater 22a therein. The first roll 21 and the second roll 22 are in pressure contact with each other. Reference numeral 24 denotes a recording sheet carrying a toner image 23, which enters between the first roll 21 and the second roll 22 after the toner image 23 is transferred to the surface by an image forming apparatus (not shown). . A first temperature sensor 25 is provided on the surface of the first roll 21, and a surface temperature X of the first roll 21 is detected based on a detection signal of the first temperature sensor 25. Further, a second temperature sensor 26 is provided on the surface of the second roll 22, and a surface temperature Y of the second roll 22 is detected based on a detection signal of the second temperature sensor 26.
One end of each of the heaters 21a and 22a is connected in parallel to a power supply 27, and the other end of the heater 21a is connected to a switching element 28, and the other end of the heater 22a is connected to a switching element 29. The switching elements 28 and 29 are connected to a drive control system described later, and energize the heater 21a and the heater 22a based on a heater control signal output from the drive control system.

Referring to the drive control system, reference numeral 30 denotes a CPU for performing various operations and general control of each unit, reference numeral 31 denotes a ROM in which various data and programs are stored, and reference numeral 32 denotes a ROM.
Is a RAM for storing various calculation results in the CPU.
The CPU 30, the ROM 31, and the RAM 32 are connected by a bus. The detection signals from the first temperature sensor and the second temperature sensor are taken into the CPU 30 via an input interface circuit 33, while the heater control signals based on various calculations in the CPU 30 are output from the switching element via an output interface circuit 34. Output to 28 and 29.

The standby mode executing means, the image fixing mode executing means, the transition mode executing means, and the diagnostic mode executing means, which are constituent elements of the present invention, are realized as functions of the drive control system. For example, as for the image fixing mode executing means, the fixing characteristic formula for calculating the target temperature of the second roll is stored in the ROM 31, and the calculated temperature comparing means, the reference temperature comparing means and the fixing driving means are The CP
It is implemented as a U30 function.

FIG. 10 is a basic circuit diagram showing the fixing device of the present invention. Reference numeral 35 denotes a drive control circuit in which the CPU 30, the ROM 31, the RAM 32, the input interface circuit 33, and the output interface circuit 34 are integrated. Reference numeral 36 denotes a relay circuit in which the switching elements 28 and 29 are incorporated, and reference numeral 37 denotes a multiplexer to which detection signals of the first temperature sensor and the second temperature sensor are input. The multiplexer 37 inputs one of the detection signals of the two temperature sensors 25 and 26 to the drive control circuit 35 in accordance with the binary signal output from the drive control circuit 35. Reference numeral 38 denotes a safety circuit for preventing the heaters 21a and 22a from overheating.

(2) Control Method Next, a description will be given of a specific temperature control method of the fixing device thus configured. The temperature control method of the present embodiment includes:
As shown in FIG. 8, a standby mode that is executed during image forming standby of the image forming apparatus, a transition mode that is executed as needed only at the beginning of the image forming operation, and a transition mode following the transition mode And an image fixing mode executed during the image forming operation. In addition, during the execution of the image fixing mode, the diagnostic mode for simultaneously determining whether or not the minimum fixing property allowed as a recorded image can be ensured is executed.
First, the specific control of the heaters 21a and 22a in each mode will be described, and then the start and end of each mode will be described.

(2.1) Heater control in each mode

Standby Mode In the standby mode, a predetermined standby surface temperature is compared with an actual measured temperature value of the roll measured by the temperature sensor, and based on a magnitude of the comparison result, the heater inside the roll is energized. Done. That is, the first roll
With respect to 21, the standby surface temperature X ₀ is set, and if the measured temperature value X of the first roll 21 detected by the first temperature sensor 25 satisfies the relationship of X <X ₀ , the output from the drive control system Switching element by the heater control signal
28 is short-circuited, and the heater 21a is energized. Also, the standby surface temperature Y ₀ is set for the second roll 22,
If the measured temperature value Y of the second roll 22, which is detected by the second temperature sensor 26 satisfies the relation of Y <Y _0, the switching element 29 is short-circuited by the heater control signal outputted from the drive control system, a heater 22a is energized. Therefore, whether or not the heater is energized is determined only by the surface temperature of the roll in which the heater is installed, and the surface temperatures of the other rolls have no influence on the determination. Table 1 shows a combination of the comparison result for the first roll 21 and the comparison result for the second roll 22, and the driving status of the heaters 21a and 22a at that time. The standby surface temperature X ₀ of the first roll 21 is, for example, 155 ° C
The standby surface temperature Y ₀ of the second roll is, for example, 155
° C. This value slightly varies depending on the material and structure of each roll, the material of the toner to be fixed, and the like.

[0056]

[Table 1]

Transition Mode In the transition mode, the measured temperature value X of the first roll 21 is compared with the standby surface temperature X _0, and the measured temperature value of the second roll 22 is compared.
Said Y in that compared with the standby surface temperature Y ₀ is the same as the standby mode. However, since this transition mode starts in synchronization with the start of image formation of the image forming apparatus,
It is not possible to secure power for energizing 21a and 22a simultaneously. Therefore, from the combination of the temperature comparison result for the first roll 21 and the temperature comparison result for the second roll 22,
It is determined which of the heaters 21a and 22a is energized. Specifically, the second roll 22 in contact with the front side of the recording sheet 4
If the actually measured temperature value Y falls below the standby surface temperature Y ₀ (Y <Y ₀₎
, The second heater 22a is always in an energized state regardless of the comparison result regarding the first roll 21. Table 2 shows a combination of the comparison result for the first roll 21 and the comparison result for the second roll 22, and the driving status of the heaters 21a and 22a at that time.

[0058]

[Table 2]

Image Fixing Mode (Basic Example) In this image fixing mode, a target surface temperature y of the second roll 22 required for reproducing a predetermined fixing property from the actually measured temperature value X of the first roll 21 is calculated. The heater 22a is energized only when the measured temperature value Y of the second roll 22 falls below the target surface temperature y (Y <y). The target surface temperature y of the second roll 22 is calculated by a fixing characteristic equation y = Ax + B using the surface temperature x of the first roll 21 as a variable.
1 is stored in advance. The coefficient A is, for example, −0.3, and the coefficient B is, for example, 180 ° C. Therefore, the fixing characteristic equation is y = −0.3x + 180.If the measured temperature value of the first roll 21 is, for example, 130 ° C., the target surface temperature y of the second roll 22 is 141 ° C. from the fixing characteristic equation. Is calculated. However, these coefficients A and B slightly vary depending on the material and structure of each roll, the material of the toner to be fixed, the speed at which the recording sheet is sent, and the like. FIG. 11 shows a graph of the fixing characteristic equation.

Even when the measured temperature value Y of the second roll is higher than the target surface temperature y (Y ≧ y),
Since measured temperature value X of the first roll 21 it is also contemplated significantly lower that, so that compared with the reference temperature value X ₁ obtained by setting the actual temperature value X of the first roll 21 in advance. When the measured temperature value X of the first roll 21 is below the reference temperature value X ₁ (X <
In X ₁ ), the power supply to the heater 22a is stopped when the measured temperature value Y of the second roll exceeds the target surface temperature y, and power is supplied to the heater 21a instead. Wherein a reference temperature value X ₁ is for example 145 ° C, this value may differ slightly depending on the material of the toner or the like subjected to fixing.

[0061]

[Table 3]

[0062] Table 3, the combination of the comparison results for the comparison with the reference temperature value X ₁ relating to the target surface temperature y, and illustrates that time of the heater 21a, the driving condition of 22a. Coordinates (X, Y) obtained by combining the actually measured temperature value X of the first roll 21 and the actually measured temperature value Y of the second roll 22 belonging to these four combinations belong to any of the regions to shown in FIG. Represents. For example, if (X, Y) belongs to the area, first, the heater 22a is energized to increase the surface temperature Y of the second roll 22. As a result, (X, Y) moves to the area, and then the heater 21a is energized, and (X, Y) finally reaches the area. If (X, Y) belongs to the area, the heater 22a is energized and (X, Y) moves to the area. That is, in this image fixing mode, a combination of the measured temperature value X of the first roll 21 and the measured temperature value Y of the second roll 22 (X,
Until Y) belongs to the area, one of the heaters is energized.

(Modification) When the measured temperature value Y of the second roll 22 falls below the target surface temperature y (Y <y), the heater 21a is energized. However, in view of preventing this case (Y <y) if even the measured temperature value X of the first roll is higher than the reference temperature value X ₁ (X ≧ X _1), the overheating of the first roll , The heater 22a is energized. Table shown 4 in combination with a comparison result and the comparison result about the target surface temperature y about the reference temperature value X _1, and the heater 21a at that time, the drive condition of 22a.

[0064]

[Table 4]

Diagnostic Mode In the diagnostic mode, the second roll necessary to fix the toner image on the recording sheet from the measured temperature value X of the first roll 21
Calculating a minimum surface temperature y _L 22, if the measured temperature value Y of the second roll 22 is below the lowest surface temperature y _L of the (Y <y _L),
It is determined that the toner image cannot be fixed at the surface temperature of each roll at that time. Minimum surface temperature y _L of the second roll 22, the image fixing characteristic equation of the coefficient B of the fixing mode is calculated by the fixing determination equation y _L = Ax + C was changed, the fixing determination equation stored in advance in the ROM31 ing. The coefficient C is, for example, 165 ° C., and the coefficient A uses the same value as in the image fixing mode, where A = −0,3. Therefore, the fixing judgment formula becomes y _L = −0.3x + 165.For example, if the measured temperature value X of the first roll 21 is 130 °, the minimum surface temperature y _L of the second roll 22 is calculated from the fixing judgment formula. Calculated as 126 ° C. Here, the coefficient C in the fixing determination formula indicates the lowest fixing property, and is clearly smaller than the coefficient B in the fixing characteristic formula.

(2.2) Start and End of Each Mode Hereinafter, the start and end of each mode will be described based on the flow from turning on the power to the copying operation in the copying machine.

Start and End of Standby Mode FIG. 12 is a flowchart showing the standby mode. When the main power switch of the copying machine is turned on, the standby mode is started by the CPU 30 receiving the signal. At this stage, since the measured temperature value X of the first roll 21 and the measured temperature value Y of the second roll 22 have not reached the standby surface temperature, both heaters 21a and 22a are energized. Further, a display indicating that copying is not possible is shown on the display unit of the copying machine. Measured temperature value X of the first roll 21 is cut off the power supply to the heater 21a exceeds the standby surface temperature X ₀ and elapsed time, also,
Measured temperature value Y of the second roll 22 is cut off energization to the heater 22a exceeds the standby surface temperature Y _0. And the heater 21
When both a and 22a are shut off for the first time, a copy available display is shown on the display of the copying machine.

The standby mode is executed even after the copy enabled display is displayed, and the CPU 30 compares the measured temperature values X, Y of the rolls 21, 22 with the standby surface temperatures X ₀ , Y ₀ , respectively. The heaters 21a, 22a are energized and de-energized according to the four combinations shown. This procedure is performed every predetermined time, and the first roll
The surface temperature of 21 in the vicinity of the standby surface temperature X _0, The surface temperature of the second roll 22 is maintained in the vicinity of the standby surface temperature Y _0. When a copy start signal is input to CPU 30, the standby mode ends.

Start and End of Transition Mode (Example 1) FIG. 13 is a flowchart showing a first embodiment of the start and end of the transition mode. When the copy start signal is input to the CPU 30 and the standby mode ends, the CPU 30 determines whether to execute the transition mode or the image fixing mode. This determination is based on the actual measured temperature value X of the first roll 21 at the end of the standby mode and the target surface temperature y = AX + B of the second roll 22 calculated from the fixing characteristic equation. This is done in comparison with Y. Then, only when the actually measured temperature value Y of the second roll 22 exceeds the calculated target surface temperature y (Y> y), the transition mode starts. That is, the transition mode starts only when the temperature coordinates (X, Y) of each of the rolls 21 and 22 at the time when the standby mode ends are present in the region or the region shown in FIG. The coefficient B of the fixing characteristic equation is determined in advance by a plurality of coefficients B ₁ , B ₂ , B
_3, ... are stored in the ROM 31, CPU 30 reads from the ROM 31 the optimum coefficient B according to a recording sheet selection signal and a color copy selection signal input from the operation unit of the copying machine, which is used in the calculation . In the subsequent image fixing mode, the coefficient B read at this time is used for calculation.

During execution of the transition mode, the CPU 30 first compares the actually measured temperature value Y of the second roll 22 with the standby surface temperature Y _0, and determines that Y <Y ₀
If so, the heater 22a is energized. If Y ≧ Y ₀ , the actually measured temperature value X of the first roll 21 is further changed to the standby surface temperature X _0.
And the heater 21a is energized based on the comparison result. This procedure is performed for each predetermined time before the actual temperature value Y of the second roll 22 is compared with the standby surface temperature Y ₀ is always measured temperature value Y and the target surface temperature y of the second roll 22
Is compared with the size. Then, the transition mode ends when the measured temperature value Y of the second roll 22 falls below the target surface temperature y (Y ≦ y).

(Example 2) FIG. 14 is a flowchart showing a second embodiment of the start and end of the transition mode. When the copy start signal is input to the CPU 30 and the standby mode ends, the transition mode always starts in this embodiment. In this embodiment, the transition mode ends at the time when the number of copied recording sheets reaches the n-th sheet. Therefore, the measured temperature values X and Y of the rolls 21 and 22 have no influence on the determination of the end of the transition mode. Also, in this embodiment,
Measured temperature of the first roll 21 at the end of the transition mode
Utilizing X _N and the measured temperature Y _N of the second roll 22, and from the calculation of B = Y _N -AX _N to determine the coefficient B of the fixing characteristic equation.

A plurality of n ₁ , n ₂ , n ₃ ,... Are previously stored in the ROM 31 as the number n of recording sheets as a criterion for ending the transition mode, and the CPU 30 is inputted from the operation unit of the copying machine. The optimum number n is read from the ROM 31 according to the recording sheet selection signal, the color copy selection signal, and the like, and this is used as a criterion for determining the end of the transition mode. Therefore, also in this embodiment, the coefficient B of the fixing characteristic equation differs according to the recording sheet selection signal, the color copy selection signal, and the like input to the CPU 30. As the number n of the recording sheets, for example, n = 15 when a copy is made on the A3 recording sheet, and n = 30 when a copy is made on the A4 recording sheet. Actually, it slightly differs depending on the material and structure of each roll, the material of the toner to be fixed, the speed at which the recording sheet is sent, and the like.

Start and End of Image Fixing Mode FIG. 15 is a flowchart showing from the start to the end of the image fixing mode. When the transition mode ends, the CPU 30 executes the image fixing mode. In this image fixing mode, first, the CPU 30
Calculates the target surface temperature y of the second roll 22 from the measured temperature value X of the first roll 21, and then compares the target surface temperature y with the measured temperature value Y of the second roll. Further, CPU 30 compares the measured temperature value X and the reference temperature value X ₁ of the first roll 21. Then, according to the combinations shown in Table 3, only one of the heaters 21a and 22a is turned on. The above procedure is repeated every predetermined time. The image fixing mode ends when the copying operation ends, and after the image fixing mode ends, the standby mode is executed.

The start of the image fixing mode is not necessarily the end of the transition mode. When it is determined that the execution of the transition mode is not necessary in the first embodiment of the transition mode, the image fixing mode starts from the end of the standby mode. For example, when the copy operation is completed and the copy operation is started again in a short time after the image fixing mode is changed from the image fixing mode to the standby mode, the temperature coordinates (X, Y) including the actually measured temperature values of the rolls 21 and 22 are calculated. It may exist in the area or area shown in FIG. Therefore, in such a case, the image fixing mode starts without executing the transition mode.

Start and End of Diagnosis Mode The diagnosis mode is executed simultaneously with the image fixing mode. Figure
As shown in FIG. 15, the CPU 30 controls the energization of each of the heaters 21 a and 22 a, and then determines the minimum fixing temperature of the second roll 22 from the fixing determination formula stored in the ROM 31 and the actually measured temperature value X of the first roll 21. calculates the y _L, compares it with the measured temperature value Y of the second roll 22. Then, if the measured temperature value Y of the second roll 22 is above the minimum fixing temperature _{y L (Y ≧ y L)} , under the determination that the lowest fixing of the toner image is secured, the image fixing mode Is continuously executed. On the other hand, when the measured temperature value Y of the second roll 22 is lower than the minimum fixing temperature _{y L (Y <y L)} , under the determination that it is not possible to fix the toner image on the recording sheet, The image fixing mode is forcibly terminated and the standby mode is started. At this time, a copy-impossible signal is output from the CPU 30, and a copy-impossible display is displayed on the display of the copying machine.

(3) Conclusion In the temperature control method of the present embodiment described above, the heaters 21a and 22a mounted on the rolls 21 and 22 are used during the copying operation by using the fixing characteristic formulas obtained experimentally in advance. , The constant fixing property can always be secured without applying unnecessary heat energy to each roll. In addition, even during the copying operation in which the surface temperature of each roll is likely to decrease, the determination as to whether or not to energize the heater is made comprehensively from the actually measured surface temperatures of the two rolls. In some cases, the heater is not energized at all, and the overshoot phenomenon after the end of the copy operation can be effectively prevented.

During the copying operation, it is determined whether or not the toner image can be fixed on the recording sheet by using a fixing determination formula obtained experimentally in advance. can do.

[0078]

As described above, according to the first fixing device temperature control method of the present invention, in the image fixing mode, the second roll necessary for reproducing the predetermined fixing property is used. Since the target temperature y is calculated from the measured temperature value X of the first roll, and the first heating means or the second heating means is driven based on the comparison result between the target temperature y and the measured temperature value of the second roll. In addition, it is possible to prevent unnecessary heat energy from accumulating on each roll, and it is possible to perform good fixing with little heat energy. Further, the overshoot phenomenon of each roll can be effectively prevented.

Further, according to the second method of controlling the temperature of the fixing device according to the present invention, the excess heat energy can be stored in each roll in the standby mode where there is a margin in the electric power. It is possible to effectively prevent the fixing performance from deteriorating due to insufficient energy.

Further, according to the third fixing device temperature control method of the present invention, it is possible to avoid a state where none of the heating means is driven at the beginning of the fixing operation.
It is possible to prevent the surface temperature of each roll from suddenly lowering, and it is possible to guarantee a fixed fixing property even for a large number of continuous copies.

Further, according to the fourth method for controlling the temperature of the fixing device of the present invention, the diagnostic mode determines the minimum surface temperature y _L of the second roll required for fixing the toner image on the recording sheet. calculated from the measured temperature value X of the first roll, since the diagnosis of possible or fixing non fixing based on the comparison result of the a target temperature y _L and the measured temperature value of the second roll, the thermal energy state of each roll This makes it possible to judge whether fixing is possible or not.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a fixing device according to a first temperature control method of the present invention.

FIG. 2 is a basic configuration diagram of a fixing device according to a second temperature control method of the present invention.

FIG. 3 is a basic configuration diagram of a fixing device according to a third temperature control method of the present invention.

FIG. 4 is a basic configuration diagram of a fixing device according to a fourth temperature control method of the present invention.

FIG. 5 is a graph illustrating the first temperature control method.

FIG. 6 is a timing chart showing a relationship between the second temperature control method and an operation state of the image forming apparatus.

FIG. 7 is a graph illustrating the second temperature control method.

FIG. 8 is a timing chart showing a relationship between the third temperature control method and an operation state of the image forming apparatus.

FIG. 9 is a specific configuration diagram of a fixing device described in an embodiment.

FIG. 10 is a circuit diagram of the fixing device described in the embodiment.

FIG. 11 is a graph illustrating a temperature control method of the fixing device described in the embodiment.

FIG. 12 is a flowchart illustrating a standby mode of the temperature control method described in the embodiment.

FIG. 13 is a flowchart showing a transition mode of the temperature control method described in the embodiment.

FIG. 14 is a flowchart showing another embodiment of the transition mode.

FIG. 15 is a flowchart showing an image fixing mode and a diagnostic mode of the temperature control method described in the embodiment.

[Explanation of symbols]

1,21 ... first roll, 1a ... first heating means, 2,22 ... second roll, 2a ... second heating means, 3,23 ... toner image, 4,24 ... recording sheet, 21a, 22a ... heater, 25… first temperature sensor, 26…
Second temperature sensor

Claims (15)

(57) [Claims] 1. A first roll having first heating means therein.
Is disposed in contact with the first roll, and has a second
A second roll having a heating means, and
Fixing by heating and fixing the toner image on the sent recording sheet
In the method of controlling the temperature of an apparatus, the method is performed during an image forming operation of the image forming apparatus.
An image fixing mode, wherein the image fixing mode is the first
And the following fixing characteristic formula y = AX + BA A: The first roll and the second roll contribute to the fixing of the toner image
A coefficient indicating the ratio of efficiency to be performed X: Actual measured temperature value of the first roll B: A coefficient indicating the fixing property of the toner image is used for the second roll to reproduce a predetermined fixing property using the coefficient.
A calculating step of calculating a required target surface temperature y;
The target surface temperature y is compared with the actually measured temperature value Y of the second roll.
Calculating a temperature comparison step, based on the comparison result,
A fixing control step of driving the heating means or the second heating means;
And the coefficient B is determined by the type of the recording sheet or the number of colors of the toner image.
A fixing device characterized in that different values are used depending on the type of the fixing device.
Temperature control method. 2. A first roll having a first heating means therein.
Is disposed in contact with the first roll, and has a second
A second roll having a heating means, and
Fixing by heating and fixing the toner image on the sent recording sheet
In the method of controlling the temperature of an apparatus, the method is performed during an image forming operation of the image forming apparatus.
An image fixing mode, wherein the image fixing mode is the first
And the following fixing characteristic formula y = AX + BA A: The first roll and the second roll contribute to the fixing of the toner image
The coefficient X indicating the ratio of the efficiency to be applied to the second roll is necessary to reproduce the predetermined fixing property by using the actual temperature value B of the first roll and the coefficient indicating the fixing property of the toner image.
A calculating step of calculating a required target surface temperature y;
The target surface temperature y is compared with the actually measured temperature value Y of the second roll.
Calculating a temperature comparison step, based on the comparison result,
Fixing control step for driving the heating means or the second heating means
If, before a reference temperature value X ₁ of the first roll defined in any
Reference temperature comparison comparing the measured temperature value X of the first roll
The fixing temperature control step includes the step of:
Comparison result by the reference temperature comparison step with respect to the comparison result
In consideration of any of the first heating means or the second heating means
Is characterized by judging whether to preferentially drive
How to control the temperature of the device. 3. A first roll having first heating means therein.
Is disposed in contact with the first roll, and has a second
A second roll having heating means, and a surface temperature of the first roll
First temperature detecting means for detecting the temperature, and a table of the second roll
Second temperature detecting means for detecting a surface temperature, and the first heating means
Control means for controlling the stage and the second heating means,
The toner image is printed on the recording sheet sent from the image forming apparatus.
In a fixing device for performing heat fixing, the control unit functions during an image forming operation of the image forming apparatus.
Image fixing mode executing means, wherein the image fixing mode executing means is provided in the first temperature detecting means.
The measured temperature value X of the first roll and the following fixing characteristic equation y = AX + BA A: The first roll and the second roll contribute to the fixing of the toner image
A coefficient indicating the ratio of efficiency to be performed X: Actual measured temperature value of the first roll B: A coefficient indicating the fixing property of the toner image is used for the second roll to reproduce a predetermined fixing property using the coefficient.
Calculating means for calculating a required target surface temperature y;
The target surface temperature y and the second row by the second temperature detecting means
Calculating temperature comparing means for comparing the measured temperature value Y of the
The first heating means or the second heating means based on the comparison result
A fixing time of driving means for driving the type of the recording sheet over preparative also
Is a coefficient determination for determining the coefficient B according to the number of colors of the toner image.
A fixing device comprising fixing means. 4. A first roll having a first heating means therein.
Is disposed in contact with the first roll, and has a second
A second roll having heating means, and a surface temperature of the first roll
First temperature detecting means for detecting the temperature, and a table of the second roll
Second temperature detecting means for detecting a surface temperature, and the first heating means
Control means for controlling the stage and the second heating means,
The toner image is printed on the recording sheet sent from the image forming apparatus.
In a fixing device for performing heat fixing, the control unit functions during an image forming operation of the image forming apparatus.
Image fixing mode executing means, wherein the image fixing mode executing means is provided in the first temperature detecting means.
The measured temperature value X of the first roll and the following fixing characteristic equation y = AX + BA A: The first roll and the second roll contribute to the fixing of the toner image
A coefficient indicating the ratio of efficiency to be performed X: Actual measured temperature value of the first roll B: A coefficient indicating the fixing property of the toner image is used for the second roll to reproduce a predetermined fixing property using the coefficient.
Calculating means for calculating a required target surface temperature y;
The target surface temperature y and the second row by the second temperature detecting means
Calculating temperature comparing means for comparing the measured temperature value Y of the
The first heating means or the second heating means based on the comparison result
And a first roller arbitrarily determined.
The reference temperature value X ₁ of the first roll and the measured temperature value X of the first roll.
Reference temperature comparing means for comparing the calculated temperature with the calculated temperature comparing means.
The comparison result by the reference temperature comparison means is compared with the comparison result.
Addition, either the first heating means or the second heating means
Fixing device characterized in that it is determined whether to drive with priority
Place. 5. A first roll having a first heating means therein.
Is disposed in contact with the first roll, and has a second
A second roll having a heating means, and
Fixing by heating and fixing the toner image on the sent recording sheet
In the method of controlling temperature of an apparatus, the method includes the steps of:
A standby mode that is executed while the image forming apparatus is waiting for image formation;
An image fixing mode executed during an image forming operation of the image forming apparatus.
And the standby mode is a first roll arbitrarily determined.
The standby surface temperature X ₀ and the actually measured temperature value X of the first roll
The first fixed temperature comparison step of comparing the
The second roll stand surface temperature Y ₀ and the measured of the second roll
A second fixed temperature comparing step of comparing a temperature value Y with the second fixed temperature comparing step;
The first heating based on the comparison result of the one fixed temperature comparison step
A first roll control step for driving the means, and the second fixed temperature
The second heating means is driven based on the comparison result of the temperature comparison step.
A second roll control step of moving the image fixing mode , wherein the image fixing mode is the actual temperature value X
Is necessary for the second roll to reproduce the specified fixability.
Calculating a target surface temperature y to be calculated;
Calculated temperature for comparing the surface temperature y with the actually measured temperature value Y of the second roll
Temperature comparison step and the comparison result of the calculated temperature comparison step.
And fixing the first heating means or the second heating means.
And a time control step.
Temperature control method. 6. A first roll having a first heating means therein.
Is disposed in contact with the first roll, and has a second
A second roll having heating means, and a surface temperature of the first roll
First temperature detecting means for detecting the temperature, and a table of the second roll
Second temperature detecting means for detecting a surface temperature, and the first heating means
Control means for controlling the stage and the second heating means,
The recording sheet passing between the first roll and the second roll
In a fixing device for heating and fixing a toner image to a
The control means functions while the image forming apparatus waits for image formation.
Standby mode executing means, and an image forming operation of the image forming apparatus.
And an image fixing mode execution unit that functions during operation.
Found temperature of the the standby surface temperature X ₀ one roll first roll
Arbitrarily defined as first fixed temperature comparing means for comparing the temperature value X
The second row and stand the surface temperature Y ₀ of the second roll was fit
Fixed temperature comparison means for comparing the measured temperature value Y
Based on the comparison result of the first fixed temperature comparing means.
First roll driving means for driving the first heating means,
Comparison result to the second on the basis of the second fixing temperature comparing means
And second roll driving means for driving the heating means.
The image fixing mode control means includes a first temperature detection means.
The specified fixing property from the measured temperature value X of the first roll
Target surface temperature y required for the second roll to
Calculating means for calculating, the target surface temperature y and the second temperature
Compare the measured temperature value Y of the second roll by the degree detecting means
Computed temperature comparing means and comparison by the computed temperature comparing means
The first heating means or the second heating means is driven based on the result.
And a fixing driving means that moves.
Fixing device. 7. A first roll having a first heating means therein.
Is disposed in contact with the first roll, and has a second
A second roll having a heating means, and
Fixing by heating and fixing the toner image on the sent recording sheet
In the method of controlling temperature of an apparatus, the method includes the steps of:
A standby mode that is executed while the image forming apparatus is waiting for image formation;
An image fixing mode executed during an image forming operation of the image forming apparatus.
And, if necessary, at the beginning of image formation of the image forming apparatus.
And a transition mode to be executed, wherein the standby mode is an arbitrarily defined first roll.
The standby surface temperature X ₀ and the actually measured temperature value X of the first roll
The first fixed temperature comparison step of comparing the
The second roll stand surface temperature Y ₀ and the measured of the second roll
A second fixed temperature comparing step of comparing a temperature value Y with the second fixed temperature comparing step;
The first heating based on the comparison result of the one fixed temperature comparison step
A first roll control step for driving the means, and the second fixed temperature
The second heating means is driven based on the comparison result of the temperature comparison step.
A second roll control step of moving the image fixing mode , wherein the image fixing mode is the actual temperature value X
Is necessary for the second roll to reproduce the specified fixability.
Calculating a target surface temperature y to be calculated;
Calculated temperature for comparing the surface temperature y with the actually measured temperature value Y of the second roll
Temperature comparison step and the comparison result of the calculated temperature comparison step.
And fixing the first heating means or the second heating means.
Time control step, the transition mode, the first fixed temperature comparison step, the
A second fixed temperature comparison step, the first fixed temperature comparison step and
Based on the comparison result of the beauty second fixing temperature comparing step, the first
A transition control step for driving the heating means or the second heating means;
Temperature control method for a fixing device characterized by comprising:
Law. 8. A method for controlling the temperature of a fixing device according to claim 7.
In the image fixing mode, the operation of the image forming apparatus is
A predetermined number of recording sheets have passed through the fixing device from the start of the image.
Is executed from the time when the
The transition mode is not executed until the execution of the image fixing mode.
A temperature control method for a fixing device, wherein the temperature control method is performed. 9. A method for controlling the temperature of a fixing device according to claim 8.
Passing through the fixing device during the transition mode.
The number of recording sheets to be used depends on the image forming operation of the image forming apparatus.
Temperature control method for fixing device
Law. 10. A method for controlling the temperature of a fixing device according to claim 9.
In the method, the image fixing mode is the mode of the image forming apparatus.
It is executed after a predetermined time has elapsed from the start of image formation, and the
From the start of image formation of the forming apparatus to the execution of the image fixing mode,
A fixing device wherein the transition mode is executed.
Temperature control method. 11. The temperature control of a fixing device according to claim 10.
The method of claim 1, wherein the transition mode execution time comprises:
Characterized in that it differs according to the image forming operation of the forming apparatus.
Temperature control method for a dressing device. 12. The method according to claim 8, wherein
In the method for controlling the temperature of the fixing device, the eye of the second roll
The target surface temperature y is expressed by the following fixing characteristic equation y = AX + BA A: The first roll and the second roll contribute to the fixing of the toner image
X: A coefficient indicating the ratio of the efficiency to be performed : the actually measured temperature value of the first roll B: A coefficient indicating the fixability of the toner image is calculated from the coefficient B, and the coefficient B is the time when the execution of the image fixing mode is started.
Measured temperature value XN of the first roll and measured temperature of the second roll
The method of controlling the temperature of the fixing device, wherein the temperature value is calculated from the following equation after detecting the temperature value YN: B = YN−AXN
Law. 13. A method for controlling the temperature of a fixing device according to claim 7.
The image fixing mode is controlled by the eye of the second roll.
Comparison between target surface temperature y and measured temperature value Y of the second roll
The result is Y <y for the first time after the image forming apparatus starts image formation.
Is executed from the point in time at which the image forming apparatus starts image formation.
The transition mode is not executed until the execution of the image fixing mode.
A temperature control method for a fixing device, wherein the temperature control method is performed. 14. The temperature control of a fixing device according to claim 13.
Wherein the target surface temperature y of the second roll is
Formula y = AX + BA A: The first roll and the second roll contribute to the fixing of the toner image
X: A coefficient indicating the ratio of the efficiency to be performed : The actually measured temperature value of the first roll B: A coefficient indicating the fixability of the toner image, which is calculated from the coefficient B , and the coefficient B varies depending on the image forming operation of the image forming apparatus.
A temperature control method for a fixing device. 15. A first row having first heating means therein.
And the first roll are disposed in contact with the first roll, and the second
A second roll having heating means, and a surface of the first roll
First temperature detecting means for detecting a temperature, and the second roll
Second temperature detecting means for detecting a surface temperature, and the first heating
Means and control means for controlling the second heating means.
The record passing between the first roll and the second roll
In a fixing device that heats and fixes a toner image on a sheet,
The control means functions when the image forming apparatus is in an image forming standby state.
Standby mode executing means, and the operation of the image forming apparatus.
Means for executing the image fixing mode which functions during the image operation, and
The transfer functioning only when the image forming apparatus starts image formation.
Line mode execution means, wherein the standby mode execution means has an arbitrarily determined
Found temperature of the the standby surface temperature X ₀ one roll first roll
Arbitrarily defined as first fixed temperature comparing means for comparing the temperature value X
The second row and stand the surface temperature Y ₀ of the second roll was fit
Fixed temperature comparison means for comparing the measured temperature value Y
Based on the comparison result of the first fixed temperature comparing means.
First roll driving means for driving the first heating means,
Comparison result to the second on the basis of the second fixing temperature comparing means
And second roll driving means for driving the heating means.
Is, the image fixing mode execution means, said first temperature detecting means
The specified fixing property from the measured temperature value X of the first roll
Target surface temperature y required for the second roll to
Calculating means for calculating, the target surface temperature y and the second temperature
Compare the measured temperature value Y of the second roll by the degree detecting means
Computed temperature comparing means and comparison by the computed temperature comparing means
The first heating means or the second heating means is driven based on the result.
The transition mode executing means, the first fixed temperature comparing means.
And the second fixed temperature comparing means, and the first fixed temperature ratio
Comparison means and the second fixed temperature comparison means.
To drive the first heating means or the second heating means
And a time driving means.
Place.