JPH07129024A - Heater and image forming device - Google Patents

Abstract

PURPOSE:To reduce the timewise fluctuation of a heater temperature and to reduce uneven heating on a member to be heated by keeping a power level other than the maximum power constant irrespective of the resistance value of the heater and a voltage impressed to the heater. CONSTITUTION:The resistance value of the heater 1 is stored on an MPU 18, and the driving condition for a heater driving circuit 16 is varied in accordance with the value. A voltage detecting means is installed in the circuit 16 so as to detect the voltage impressed to the heater 1 and to vary the action of a switching element. In this case, the variance of the effective value of the voltage impressed to the heater is between 80V and 110V, and the minimum value of the maximum power is 720W and the maximum value is 880W. For example, when the resistance value of the heater is 8OMEGA and T is <200 deg.C, the maximum impressed power is 800W, but, when Rnot equal to 8OMEGA is obtained, the maximum impressed power is varied in accordance with the inputted voltage, or the resistance value of the heater. Thus, the member to be heated can be uniformly heated only by changing the impressed power when T is <200 deg.C even in the case the resistance value of the heater and the impressed voltage are changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heater (heater) which is heated by energization, a material to be heated is closely attached through a film member, and the heater position is conveyed together with the film member so that the heat of the heater is transferred to the film. The present invention relates to a film heating type heating device which is applied to a material to be heated via a member.

Further, the present invention relates to an image forming apparatus provided with the heating device as an image heating and fixing device.

[0003]

2. Description of the Related Art A heating device of the film heating type as described above is disclosed in, for example, JP-A-63-313182, JP-A-2-157878, and JP-A-4-44075-44.
No. 083, 204980-204984, and the like, in image forming apparatuses such as a copying machine, a laser beam printer, a facsimile, a microfilm reader printer, an image display (display) device, and a recording machine,
A recording material (electrofax sheet, electrostatic recording sheet, transfer material) as an image support is formed by using a toner made of a heat-meltable resin or the like by an appropriate image forming process means such as electrophotography, electrostatic recording, magnetic recording. An unfixed toner image (fixed image) corresponding to the target image information formed on the surface of the sheet or printing paper by a direct method or an indirect (transfer) method is applied to the surface of the recording material carrying the image. It can be used as an image heating stationary device that performs heat fixing processing as a permanently fixed image.

Further, it is not limited to the fixing device, but is widely used as a means for heating a material to be heated, such as an apparatus for heating a recording material carrying an image to modify its surface property, a hypothetical apparatus, etc. it can.

The film heating type heating device is compared with other known heating devices such as a heat roller type, a hot plate type, a belt heating type, a flash heating type and an open heating type, or an image heating and fixing device. ． Since a heater with a low thermal capacity such as a thermal head and a thin film with a low thermal capacity can be used as the heater, it is possible to save power and shorten the wait time (quick start property). The temperature rise inside the machine can be suppressed ,. The image heating and fixing device is advantageous in that it can prevent offset because the fixing point and the separation point can be set separately, and that it can solve various drawbacks of other types of devices.

As the heater, a ceramic substrate provided with a pattern layer of an electric resistance heating element is used as a basic structure, and a heater having a low heat capacity is used. The temperature of the heater is raised by energizing the electric resistance heating element. The power supply to the energization resistance heating element is controlled so as to maintain the heater temperature at a predetermined constant value in accordance with the detected temperature of a thermistor or the like for detecting.

Since the heat capacity of the heater used in the film heating type heating device is remarkably smaller than that of the heating roller in the heat roller type device, the power supplied to the heater (more accurately, supply to the energization resistance heating element). Power, the same below)
Depending on whether the temperature detected by the temperature detecting means is equal to or higher than a predetermined control value or OFF (OFF) and ON (ON).
When switching in stages, the temperature of the heater fluctuates greatly with time, and uneven heating of the material to be heated is likely to occur.

In order to prevent such heating unevenness, a technique is known in which an intermediate output power level is provided between turning the power supplied to the heater off and on, and the output voltage is switched according to the detected heater temperature. There is.

As a method of changing the output voltage, a so-called "phase control method" is used in which alternating current is used and a switching element such as a triac is used to suspend the output at a predetermined duty every cycle.

In the heater used in this type of device, the resistance value of the energization resistance heating element between the power supply terminals at both ends in the longitudinal direction (hereinafter referred to as the resistance value of the heater) is R, and the voltage between the power supply terminals is applied. the voltage V (however, V = V _P sinθ), the duty ratio is energized r (however, 0 ≦ r ≦ 1) when the,

[0011]

[Equation 1] It is represented by.

By the way, the resistance R of the heater has a predetermined tolerance for each heater. The predetermined variation is present in the amplitude V _P of the voltage applied to the heater. Then, even if electricity is supplied with the same duty ratio r, the power W varies.

In order to prevent this, the resistance value R of the heater,
It is known to provide a correction means for correcting the duty ratio r so that the same electric power W is output even if the amplitude V _{P of the} voltage applied to the heater is different.

[0014]

However, the above-mentioned conventional example has the following problems.

That is, the maximum current value that can be supplied to the heating device has a predetermined upper limit value I _max due to the durability of the heater and the device itself and the performance of the power supply. Further, the maximum power value that can be supplied to the heating device also has a predetermined upper limit value W _max for the same reason.

At this time, the electric power supplied to the heater is RI
_max ² and V _a ² / R (V _a ; heater applied voltage effective value)
Then, it becomes the minimum power of the three of W _max .

Then, when the resistance value R of the heater is small,
Since the electric power is regulated by RI _max ² , only a small amount of electric power is supplied.

In order to prevent this, when the resistance value R of the heater is increased, the electric power is regulated by V _a ² / R this time, and when the input voltage is small, only a small amount of electric power is supplied.

After all, if the heater resistance value R or the heater applied voltage effective value V _a is different, a difference occurs in the electric power supplied to the heater.

On the other hand, conventionally, as shown in FIG. 4, the maximum electric power input to the heater (hereinafter referred to as W ') is gradually proportional to W'as the heater temperature becomes higher than a predetermined value T _o . Then, the method of reducing the amount was used.

In such a system, if W'is varied, the relatively small level of electric power (for example, 0.2 W ') given when the temperature of the heater becomes high also varies. Then, the temperature of the heater fluctuates with time, which causes uneven heating.

Therefore, an object of the present invention is to provide a heating device of this type, which is effective in reducing the temporal change of the heater temperature even when the heater resistance value or the electric power supplied to the heater varies. To do.

[0023]

The present invention is a heating device and an image forming apparatus characterized by the following configurations.

(1) The heat of the heater is applied to the material to be heated through the film member by bringing the material to be heated into close contact with the heater that generates heat by energization through the film member and transporting the heater position together with the film member. In the heating device to
The temperature detection means for detecting the temperature of the heater, the resistance value recording means for recording the resistance value R of the heater, the level L _{i of the} power supplied to the heater (where i is 0 or a natural number), and the output off state are also set. Including at least three levels, the energization control means that can be selected from L ₀ , L ₁ ... L _n (where n is an integer of 2 or more) in order of decreasing power, and the input to the energization control means Voltage detection means for detecting a voltage or an output voltage V from the energization control means, and the energization control means detects the temperature detected by the temperature detection means and the heater resistance value R recorded in the heater resistance value recording means. And the power supply to the heater is set according to the voltage V detected by the voltage detection means, and at least the power level L _n at which the energization control means outputs the maximum power is output. Power is above It is set so as to differ depending on the resistance value R of the heater and the voltage V, and at least 1 other than the maximum output power level L _n and the output off level L _0.
The two power levels L _{1 to} L _{n-1 correspond} to the resistance value R of the heater.
And the heating device, wherein the energization control means is set to be substantially constant regardless of the voltage V.

(2) The heating device according to (1), characterized in that the electric power supplied to the heater is reduced as the temperature detected by the heater increases.

(3) Output power W _{i of the} energization control means
(Where i is 0 or a natural number), W ₀ (= 0 watt), W ₁ , ... W _n (n
Is an integer of 2 or more), and the output power W _i0 of the energization control means (where i is 0 or a natural number) when the resistance value R of the heater and the voltage V are predetermined values R ₀ and V ₀ , respectively. ) Is W ₀₀ (= 0 watts), W ₁₀ , ..., W _{n0 in} order from the smallest power, in the range of i where W _n ≧ W _i0 holds, W _i = W _i0 The heating device according to (1), characterized in that

(4) A pressurizing member for bringing the film member into close contact with the heater is provided, and the film member is sandwiched between the film member and the pressurizing member in the press-contact nip portion formed by the heater and the pressurizing member. The heating device according to (1), wherein a heating material is introduced, and the pressure contact nip portion is nipped and conveyed together with the film member to apply heat of the heater to the material to be heated via the film member.

(5) The heating device according to (1), characterized in that the material to be heated is passed through the device on a one-sided basis.

(6) The heating apparatus according to (1), wherein the film member is an endless film which is rotationally conveyed or an end film which is conveyed by conveyance.

(7) The pressurizing member is a rotating body which is rotationally driven, and the rotational force of the rotating member causes the film member to be rotatably conveyed or conveyed while closely sliding on the heater. Heating device.

(8) An image heating fixing device in which the material to be heated is a recording material supporting an unfixed developer image to be image-fixed, and the unfixed developer image is heat-fixed on the recording material. The heating device according to any one of (1) to (7), characterized in that.

(9) An image comprising the heating device according to any one of (1) to (8) as an image heating and fixing device for heating and fixing an unfixed developer image on a recording material. Forming equipment.

[0033]

By making at least one power level other than the maximum power constant regardless of the heater resistance value and the voltage applied to the heater, it is possible to reduce the temporal change in the heater temperature.

As a result, uneven heating of the material to be heated is reduced. In the image heating and fixing device, it is possible to prevent toner stains on the film member and the pressing member due to image heating failure (fixing failure). Therefore, an apparatus capable of performing stable heat treatment for a long period of time is configured.

[0035]

【Example】

<Embodiment 1> (FIGS. 1 to 3) (1) Heating device FIG. 1 is a schematic configuration diagram of a heating device (image heating and fixing device) A according to one embodiment, and FIG. A cutaway plan view, (b) is a vertical sectional front view of the heater 1 and a block diagram of an energization system.

In FIG. 1, 6 is an endless belt-shaped fixing film, and the fixing film 6 includes a left driving roller 7, a right driven roller 8, and both rollers 7, 8.
A low heat capacity linear heater 1 supported by a heater support 11 and fixedly disposed below the space between the heater support 11 and the linear heater 1. The vertical movement roller 8 also serves as a tension roller that applies tension in a direction in which the fixing film 6 is stretched outward.

The fixing film 6 has a predetermined peripheral speed in the clockwise direction a along with the clockwise rotation of the driving roller 7 whose surface is coated with silicone rubber or the like to increase the friction coefficient, and has wrinkles, meandering, and speed. It is driven to rotate without delay.

Reference numeral 9 denotes a pressure roller having a rubber elastic layer having a good releasability such as silicone rubber as a pressure member which is pressed against the heater 1 with the fixing film 6 sandwiched therebetween. Are urged against each other by a biasing means such as a spring with a contact force of, for example, a total load of 5 to 10 kg,
The recording material P as the material to be heated is rotated counterclockwise in the forward direction in the conveying direction.

Since the endless belt-shaped fixing film 6 which is rotationally driven is repeatedly used for heat fixing of the toner image, it is excellent in heat resistance, releasability and durability, and is generally 1
A thin film having a thickness of 00 μm or less, preferably 40 μm or less is used.

As an example, a highly heat resistant resin such as polyimide, polyetherimide, polyethersulfone, polyetheretherketone, etc. having a thickness of 20 μm, nickel,
A low surface energy resin such as PTFE (tetrafluoroethylene resin), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin) or the like on the outer peripheral surface of a thin endless belt member made of metal such as SUS An endless belt having a total thickness of 30 μm in which a release coating layer having a conductive material such as carbon black added thereto is applied to a thickness of 10 μm.

The heater 1 having a low heat capacity has a thickness of 1.0, for example.
A resistance material such as silver palladium or ruthenium oxide having a thickness of 10 μm and a width of 1.0 mm is applied to an alumina substrate 2 having a size of 10 mm, a width of 10 mm, and a length of 340 mm in the longitudinal direction to form an energization resistance heating element layer 3. A protective layer 4 made of glass or the like having a thickness of about 10 μm is formed thereon in consideration of sliding with the film 6.

The heater support 11 has a heat insulating property, a high heat resistance, and rigidity for adiabatically supporting the heater 1 with respect to the apparatus A and the image forming apparatus. For example, PPS (polyphenylene sulfide), PEEK (polyether ether ketone). ), A high heat resistant resin such as a liquid crystal polymer, or a composite material of these resins and ceramics, metal or the like.

Electric current is applied to the resistance heating element layer 3 of the heater 1 from both ends in the longitudinal direction. The energization is 100 V AC, and the MPU 18 is connected to the back surface of the substrate 2 according to the detection temperature of the temperature detection element 5 (A, B) such as an NTC thermistor or the like which is adhered or pressure-bonded or integrally formed with a heat conductive silicone rubber adhesive or the like. The energization is controlled by.

The energization resistance heating element layer 3 of the heater 1 is formed in a straight line along the substrate longitudinal direction at the central portion of the lower surface of the substrate 2 as shown in FIG. Denoted at 3a and 3b are current-carrying electrodes (power supply terminals, input terminals) made of a material having good conductivity such as silver provided at the left and right ends of the heating element layer 3.

E is the effective total length region of the heating element layer 3 between the electrodes 3a and 3b. In the case of this embodiment, the maximum size of the recording material that can be supplied to the apparatus and used is the A3 plate (width 297 m).
m) and the length dimension corresponding to the width of the recording material is set.

In the apparatus of this embodiment, recording materials of various sizes are supplied on the basis of the so-called one-sided sheet feeding reference, which is based on the base line a on the left side of the heating element layer 3. A6 size (width 105 mm) paper feed area c is the paper feed area of the minimum size recording material that can be used in the apparatus of this embodiment. d is B4 version (width 2
57 mm) is the paper passing area of the recording material.

5A is the first area provided in the minimum paper passing area c.
Is a thermistor as a temperature detecting element. At the time of fixing (during the heating process of the material to be heated), the MPU 18 controls the heater drive circuit 16 so that the detection output of the first thermistor 5A becomes a predetermined constant value, and controls the energization to the heating element layer 3. ing.

Reference numeral 5B is a thermistor which is a second temperature detecting element provided outside the minimum paper passing area c, and is located inside the maximum paper passing area e in the present embodiment and outside the paper passing area d of the B4 plate. I am doing it.

From an image forming process section (not shown), a recording material P as a material to be heated having an unfixed toner image T formed and carried on the upper surface thereof is conveyed to the apparatus A and guided by the entrance guide 10 to fix the fixing film. The toner image surface faces the fixing film 6 between the fixing film 6 and the pressure roller 9 in the pressure contact nip portion N (fixing nip portion) of the heater 1 and the pressure roller 9 which are in pressure contact with each other with the heater 6 interposed therebetween. enter in.

By the time the recording material P enters, the fixing film 6 has been rotationally driven at a predetermined speed, and the heater 1 has risen to a predetermined fixing temperature (200 ° C. in this embodiment).

The recording material P which has entered the fixing nip portion N passes through the fixing nip portion N between the heater 1 and the pressure roller 9 in an overlapping state with the fixing film 6 which rotates without causing surface deviation or wrinkling. The toner image bearing surface of the recording material P receives the heat of the heating element layer 3 through the fixing film 6 in the process of passing through the fixing nip portion N in a press-contact state with the fixing film 6 while passing through while receiving the pinching pressure. The toner image T is melted at a high temperature to form an image Ta that is softened and adhered to the surface of the recording material P.

In the apparatus of this embodiment, the recording material P and the fixing film 6 are separated from each other when the recording material P passes through the fixing nip portion N and comes out. At the time of this separation, the temperature of the molten toner Ta is still higher than the glass transition point of the toner.

The toner Ta, which is at a temperature higher than the glass transition point at this separation point, has an appropriate rubber characteristic, so that the toner image surface at the time of separation does not follow the surface of the fixing film and has an appropriate uneven surface property. Since the surface property is maintained and the solidified material is cooled and solidified, an appropriate image gloss is not generated on the fixed toner image surface, resulting in high quality image.

The recording material P separated from the fixing film 6 is guided by the paper discharge guide 12 and, while reaching the paper discharge roller pair 15, the temperature of the toner Ta higher than the glass transition point is naturally lowered (natural cooling). Then, the temperature becomes lower than the glass transition point and solidifies to reach the solidified image Tb. Therefore, after the recording material P has passed through the fixing nip N, it is output as the recording material P on which the image has been fixed.

(2) Control of Energization of Heater 1 In this embodiment, the resistance value of the heater 1 (that is, the electrode 3)
The design center value of the resistance value of the energization resistance heating element layer 3 between a and 3b is 8.0Ω, but due to variations in the thickness and width of the heating element layer 3 and variations in the volume resistivity of the resistance material itself. ,
It has a tolerance of ± 10%.

In the present embodiment, the actual value of the heater resistance value is stored in the MPU 18, and the drive condition of the heater drive circuit 16 is changed according to the stored value.

Further, in the present embodiment, the heater drive circuit 16 supplies the input AC current of the commercial AC power source S to the heater 1 by a switching element (not shown) such as a triac.

The voltage supplied to the heater drive circuit 16 is centered on 100 V as described above, but actually fluctuates between 80 V and 110 V. The heater drive circuit 16 is provided with a known voltage detection means (not shown), detects the electric w voltage applied to the heater drive circuit 16 (that is, the voltage applied to the heater 1), and detects the detected value. The operation of the switching element is changed accordingly.

In the present embodiment, the maximum current value that can be applied to the heater 1 is 10 A, and the maximum power value that can be applied is 100 W. The maximum power W _n that can actually be applied to the heater that satisfies these conditions is shown as a function of the heater applied voltage effective value V _a . As a parameter, the resistance value of the heater is taken, and a graph regarding the resistance lower limit of 7.2 (Ω), the center 8.0 (Ω), and the upper limit 8.8 (Ω) is prepared, and shown in FIG. Show.

Since the range of variation of the heater applied voltage effective value Va is from 80V to 110V, the minimum value of W _n is 720W and the maximum value is 880W in this range.

Table 1 is a table showing the electric power supplied to the heater with respect to the temperature detected by the first thermistor 5A in this embodiment.

[0062]

[Table 1] When the heater resistance value R = 8.0Ω, T <200 (° C)
The power applied to the heater at that time, that is, the maximum power applied is 800 W, but when R ≠ 8.0Ω, the maximum power applied changes depending on the input voltage or the resistance value of the heater, as is apparent from FIG.

However, when T ≧ 200 (° C.),
Predetermined power corresponding to the detected temperature T is supplied regardless of the input voltage and the heater resistance value.

The method of supplying the target power W shown in Table 1 is

[0065]

[Equation 2] The duty ratio r satisfying the above condition may be calculated at any time. Alternatively, the values of r for each V _P , R, and W may be stored in the MPU 18 as a table and the data may be used.

Thus, in this embodiment, even if the heater resistance value and the voltage applied to the heater are changed, T <200 (°
Since the applied power in the case of C) only changes, the temperature of the heater is changed only once, and once T ≧ 200 ° C., there is no time change of the heater temperature and stable and uniform heating can be realized.

(3) Comparative Example Table 2 shows, as a comparative example, the power supplied to the heater with respect to the detected temperature T of the first thermistor 5A. The other device configuration and control are the same as those in the first embodiment.

The electric power supplied to the heater 1 is 200 ≦ T <21.
Even in the temperature T range of 5, it depends on the resistance value of the heater and the input voltage. Therefore, the amount of heat generated by the heater may be inappropriate. Then, the temperature of the heater changes with time, causing uneven heating.

[0069]

[Table 2] <Embodiment 2> In this embodiment, the voltage applied to the heater changes from 65V to 120V. Table 3 shows the electric power supplied to the heater with respect to the temperature detected by the first thermistor 5A in this embodiment. The other device configuration and control are the same as in the first embodiment.

[0070]

[Table 3] When T ≧ 205, a predetermined power supply can be obtained regardless of the heater resistance value and the voltage applied to the heater.

In this embodiment, W _n <700 (W)
When the, according to the value of W _n, by adjusting the time from the start of the energization of the heater to the recording material reaches the fixing nip portion N, the heating defective if W _n is small To prevent.

Further, in the case of the present embodiment, since it is possible to handle a wide range of input voltage, it is convenient as a heating device (image heating and fixing device).

<Embodiment 3> In this embodiment, the power supply is changed according to the thickness of the recording material used. Table 4 shows the electric power supplied to the heater with respect to the detected temperature T of the first thermistor 5A in this embodiment. Other device configuration / control is the first embodiment
Is the same as.

[0074]

[Table 4] The thickness of the recording material may be registered in the MPU 18 by the user, or the thickness of the recording material being conveyed may be measured and detected by a known means and the measured value may be taken into the MPU 18.

The power level for each paper thickness is a predetermined value shown in Table 4 in the range of T ≧ 200 ° C., regardless of the resistance value of the heater and the applied voltage.

In the case of this embodiment, the temporal change of the heater temperature is further reduced, and the heating uniformity is improved.

<Embodiment 4> In this embodiment, 210 ≦ T,
Constant power is supplied regardless of the heater resistance value and the voltage applied to the heater. The other device configuration and control are the same as in the first embodiment.

[0078]

[Table 5] In the case of the present embodiment, the temporal change of the heater temperature is practically allowable, while when T <210, the procedure for obtaining the duty ratio r for applying a predetermined electric power to the heater can be simplified. , MPU 18 memory capacity can be reduced.

The second temperature detecting means 5B may be omitted in the heater 1 of FIG. Further, by using the detection signal of the second temperature detecting means 5B, the first to fourth embodiments
You may change the energization conditions in.

<Embodiment 5> (FIG. 5) FIGS. 5 (a), (b), and (c) show another example of the configuration of a film heating type heating device.

(A) shows the heater 1 and the driving roller 3
Heat-resistant film 6 on the endless belt between the two members 1
Is suspended and rotatably driven by the drive roller 31.

(B) shows the heater 1 and the heater 1
The heat resistant film 6 having a cylindrical shape is loosely fitted on the outside of the film guide member 32 holding the film, and the film 6 is pressed against the heater 1 by the pressure roller 9.
Is rotationally driven while the inner surface of the film 6 is brought into close contact with the surface of the heater 1 by the rotational driving (pressure roller driving type) (JP-A-2-153602-1).
53610, 4-20490 to 20498, etc.).

In (c), the heat-resistant film 6 is not an endless belt-shaped one, but a long end film wound in a roll is used.
It is configured so as to travel at a predetermined speed from the side to the winding shaft 33 side via the heater 1.

The same effects can be obtained by applying the present invention to the heating device (image heating and fixing device) having such a configuration as in the first to fourth embodiments.

<Embodiment 6> (FIG. 6) FIG. 6 shows an example of an image forming apparatus incorporating the image heating and fixing device A as a film heating type heating device according to the present invention as shown in the above-mentioned embodiment 1, for example. Shows a schematic configuration of. The image forming apparatus of this embodiment is a reciprocating platen type, a rotary drum type, a transfer type, and a process cartridge attaching / detaching type electrophotographic copying apparatus.

Reference numeral 100 denotes an apparatus casing, 101 denotes a reciprocating type document placing table made of a transparent plate member such as a glass plate disposed on an upper surface plate 102 of the apparatus casing.
The upper part is driven to reciprocate to the right a and the left a'in the drawing at a predetermined speed.

Reference numeral G denotes an original document, which is placed on the upper surface of the original document table 101 according to a predetermined placement standard with the image surface side to be copied facing downward, and the original document pressure plate 103 is put on the original document platen 103 and pressed down. Set.

Reference numeral 104 denotes a slit opening serving as a document illuminating section which is opened on the surface of the top plate 102 of the machine as a long side in a direction perpendicular to the reciprocating direction of the document placing table 101 (direction perpendicular to the paper surface).

The downward image surface of the document G placed and set on the document placing table 101 sequentially moves the positions of the slit openings 104 from the right side to the left side during the forward movement process of the document placing table 101 to the right a. The light L of the lamp 105 is passed through the slit opening 104 and the transparent original placing table 101 to be illuminated and scanned in the passing process, and the original surface reflected light of the illumination scanning light is reflected by the image element array 106 by the photosensitive drum. Image formation exposure is performed on the 107th surface.

The photosensitive drum 107 is coated with a photosensitive layer such as a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer, and is rotated in the clockwise direction indicated by the arrow b at a predetermined peripheral speed around the central support shaft 108. During the rotation process, the charging device 109 receives a uniform positive or negative charging process, and the uniformly charged surface is subjected to the image formation exposure (slit exposure) of the original image, so that the surface of the photosensitive drum 107 is formed. An electrostatic latent image corresponding to the image-exposed original image is sequentially formed.

This electrostatic latent image is sequentially visualized by the developing device 110 with toner made of resin or the like that is softened and melted by heating, and the toner image as the visualized image is provided with a transfer discharger 111 as a transfer portion. It moves to the part.

Reference numeral 200 denotes a transfer material sheet P as a recording material.
Is a stacking and storing sheet, and the sheets in the cassette are fed and fed one by one by the rotation of the feeding roller 112, and then the registration roller 113 causes the drum 107 to move.
When the tip of the upper toner image forming portion reaches the portion of the transfer discharger 111, the tip of the transfer material sheet P is also transferred.
1 and the photosensitive drum 107 have just arrived at a position between them and they are fed in a timed manner so that they coincide with each other.

Then, the transfer discharger 111 sequentially transfers the toner image on the photosensitive drum 107 side to the surface of the fed sheet.

The sheet to which the toner image has been transferred at the transfer portion is sequentially separated from the surface of the photosensitive drum 107 by a separating means (not shown), and is guided to the fixing device A by the conveying device 114 to carry the unfixed toner. Receives heat fixing of the image,
An image formed product (copy) is discharged onto a paper discharge tray 117 outside the apparatus through a discharge roller 116.

The surface of the photosensitive drum 107 after the image transfer is subjected to removal of adhering contaminants such as transfer residual toner by the cleaning device 118, and is repeatedly used for image formation.

The PC is a process cartridge which is attached / detached to / from the cartridge attaching / detaching portion 120 in the apparatus main body 100.
In the case of the present example, the apparatus main body 10 including the four process devices of the photosensitive drum 107 as an image bearing member, the charging device 109, the developing device 110, and the cleaning device 118 together.
It is detachable and replaceable with respect to 0.

[0097]

As described above, according to the present invention, in the film heating type heating device, at least one power level other than the maximum power is constant regardless of the heater resistance value and the voltage applied to the heater. By doing so, even when the heater resistance value and the electric power supplied to the heater vary, the temporal change in the heater temperature can be reduced, and the uneven heating of the material to be heated is reduced. In the image heating and fixing device, it is possible to prevent toner stains on the film member and the pressing member due to image heating failure (fixing failure). Therefore, an apparatus capable of performing stable heat treatment for a long period of time is configured.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a film heating type heating device (image heating and fixing device) according to a first embodiment.

FIG. 2A is a partially cutaway plan view of a heater, and FIG.
Is a vertical sectional front view of the heater and a block diagram of the energizing system.

FIG. 3 is a graph showing the maximum power W _n that can be applied to the heater with respect to the heater applied voltage.

FIG. 4 is a diagram showing a condition for energizing a heater in a conventional device.

5 (a), (b), and (c) are schematic diagrams of other configuration examples of a film heating type heating device, respectively.

FIG. 6 is a schematic configuration diagram of an example of an image forming apparatus.

[Explanation of symbols]

A General symbol of a film heating type heating device (image heating and fixing device) 1 heating element (ceramic heater) 2 heater substrate 3 energization resistance heating element layer 4 surface protective layer 5 (A / B) heater temperature detecting means such as thermistor 6 Heat resistant film (fixing film) 7 Film drive roller 8 Driven roller (tension roller) 9 Pressure roller 16 Heater drive circuit 18 MPU S AC power supply P Recording material as heated material T Toner image B One-sided paper feed reference line

Claims (9)

[Claims] 1. The heat of the heater is applied to the material to be heated through the film member by bringing the material to be heated into close contact with a heater that generates heat by energization through the film member and transporting the heater position together with the film member. In the heating device, temperature detection means for detecting the temperature of the heater, resistance value recording means for recording the resistance value R of the heater, and level L _{i of} electric power supplied to the heater (where i is 0 or a natural number) are output. at least three stages, including off-state, L ₀ in order of less power, L ₁ ···· L _n
(Where n is an integer of 2 or more) and an energization control means, and a voltage detection means for detecting an input voltage to the energization control means or an output voltage V from the energization control means. Means controls the power supply to the heater according to the temperature detected by the temperature detecting means, the heater resistance value R recorded in the heater resistance value recording means, and the voltage V detected by the voltage detecting means. Is set as
At least the power level L _n at which the energization control means outputs the maximum power is set to be different depending on the resistance value R of the heater and the voltage V, and the maximum output power level L _n and the output are set. The energization control means is set so that at least one power level L _{1 to} L _n-1 other than the off level L ₀ is substantially constant regardless of the resistance value R of the heater and the voltage V. A heating device characterized by. 2. The heating device according to claim 1, wherein the electric power supplied to the heater is reduced as the detected temperature of the heater increases. 3. The output power W _i (where i is 0 or a natural number) of the energization control means is W ₀ (= 0 watt), W ₁ , ... W _n (in order from the output level with the least power). n is an integer of 2 or more), the resistance value R of the heater and the voltage V
Is a predetermined value R ₀ , V ₀ respectively, the output power W _i0 of the energization control means (where i is 0 or a natural number)
In order of decreasing power, W ₀₀ (= 0 watt), W
_10. The heating device according to claim 1, wherein W _i = W _i0 in a range of i where W _n ≧ W _i0 is satisfied when W _n0 . 4. A heating member is provided between a film member and a pressing member in a pressing nip portion formed by the heater and the pressing member with a film member sandwiched between the film member and the pressing member. 2. The heating device according to claim 1, wherein the material is introduced, and the pressure contact nip portion is nipped and conveyed together with the film member to apply the heat of the heater to the material to be heated via the film member. 5. The heating device according to claim 1, wherein the material to be heated is passed through the device on a one-sided basis. 6. The heating device according to claim 1, wherein the film member is an endless film which is rotationally conveyed or an end film which is conveyed and conveyed. 7. The pressure member is a rotating body that is rotationally driven, and the film member is rotationally conveyed or traveled while being brought into close contact with the heater by the rotational force of the rotating member. Heating device. 8. An image heating fixing device for heating a material to be recorded, which supports an unfixed developer image to be image-fixed, and heat-fixes the unfixed developer image to the recording material. The heating device according to any one of claims 1 to 7, wherein: 9. An image forming apparatus comprising the heating device according to any one of claims 1 to 8 as an image heating fixing device for heating and fixing an unfixed developer image on a recording material. .