JP2000162906A - Heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the temperature rise of the paper non-passing part of small size paper by providing plural heating patterns on a heat resistant body base plate so that temperature distribution in a direction orthogonal to the advancing direction of material to be heated may be nearly uniform. SOLUTION: Since the same Ag.Pd paste is used over the entire of a heating element, electric resistance is higher and a calorific value is larger at the thin part of the heating pattern. In order to make the heating value received by paper same all over the area in a longitudinal direction, the calorific value received from the heating pattern 12a is equal to the total sum of the calorific value received from the heating pattern 12b. The width of the wide parts of the heating patterns 12a and 12b is made D equally, and similarly the width of the narrow parts thereof is made C equally. When the longitudinal direction of the heating pattern is defined as L1, L2 and L3, L2=L1+L3 is set. When the small size paper passes, it passes through the center, and both ends become the paper non-passing parts. In such a case, the heating pattern 12b is mainly heated. In the case of large size paper, both heating patterns 12a and 12b are energized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant film moving in contact with a heater supported on the surface of a support, and a nip portion formed by pressing the heat-resistant film against the heater to move the heat-resistant film. A heating device for heating the material to be heated passing through the nip portion through the film, an electrophotographic recording apparatus using the heating device as a heat fixing device, and an electrophotographic copying machine. And an image forming apparatus such as a printer.

[0002]

2. Description of the Related Art Heretofore, as a heating device of this type, a contact heating type heat roller system and an energy saving type film heating system having good thermal efficiency and safety have been adopted.

A heat fixing device to which a heating device of the heat roller type is applied basically has a heating roller (fixing roller) as a heating rotating body and an elastic pressure roller as a pressing rotating body pressed against the heating roller. By rotating the pair of rollers, an unfixed image (toner image) is formed and held in a pressure contact nip (fixing nip) between the pair of rollers, and a recording material (transfer material sheet, electrostatic (Recording paper, electrofax paper, printing paper, etc.) is introduced and the press-contact nip is pinched and conveyed, so that the unfixed image is permanently applied to the surface of the recording material by the heat from the heating roller and the pressure of the press-contact nip. The fixing is performed by heat and pressure as a fixed image.

Further, a heating and fixing device to which a film heating type heating device is applied is disclosed in, for example, JP-A-63-313182, JP-A-2-15778, and JP-A-4-44.
075-44083, JP-A-4-204980
No. 2,049,844, and the like, a heat-resistant film (fixing film), which is a heating rotating body, is brought into close contact with a heating body by a pressing rotating body (elastic roller) and slid and conveyed. A transfer material as a recording material carrying an unfixed image is introduced into a press-contact nip formed by a heating element and a pressing member, and is conveyed together with the heat-resistant film. The unfixed image is fixed on the transfer material as a permanent image by the applied heat from the heating body and the pressing force of the pressure contact nip portion.

In this film heating type heating apparatus, a linear heating element having a low heat capacity can be used as a heating element, and a thin film having a low heat capacity can be used as a heat-resistant film. Startability) is possible.

[0006]

However, in the above-described film heating type heating apparatus, since the heating capacity of both the heating heater as the heating body and the heating film as the heating rotating body is small, the transfer direction of the transfer material is small. The thermal conductivity in the direction perpendicular to the vertical direction (hereinafter referred to as the longitudinal direction) is poor, and when a transfer material having a width smaller than the maximum size is passed, the temperature rise in the non-sheet passing area tends to be large, and the heater is held. In such a case, thermal damage to members, films, pressure rollers, and the like is likely to occur, and in order to prevent such damage, the throughput of small-sized paper has to be reduced.

Further, if a wide transfer material is passed immediately after the passing of the small-size paper, the heater and the pressure roller corresponding to the non-sheet passing area when the small-size paper passes are high in temperature. However, there is a problem in that hot offset is likely to occur in this portion, and in order to prevent this phenomenon, a pause must be provided before printing large-size paper after passing small-size paper.

[0008] More recently, the use of laser beam printers to print mails such as envelopes has increased.
At this time, the address of the destination is printed on the envelope, and the text is printed on plain paper alternately.
Is widespread. In contrast to such alternate feeding, in the conventional film fixing device, if the interval between alternate feeding of envelopes and plain paper is not widened, there is a disadvantage that hot offset occurs on plain paper after passing the envelope. It was necessary to widen the paper feed interval in accordance with the increase in the number of continuous prints. However, control in a case where various print modes were assumed (especially, the history before the alternate feed of the fixing device, etc.) became complicated. Only a constant paper feed interval has been put to practical use.

For this reason, the alternate paper feed interval is very long in order to provide a sufficient margin in advance, assuming that the number of continuous print sheets is large. Even in an image forming apparatus capable of printing sheets, in alternate paper feeding, when only one set of envelopes and plain paper is used, only about two sets of throughput per minute can be obtained, and the throughput is extremely reduced.

In order to prevent this phenomenon, it has been proposed to provide a plurality of heat generating patterns on the heating element in accordance with the width of the transfer material and to make the heat generating area variable. The types and sizes of papers are very diverse, and it is necessary to control the conduction of several types of heating patterns independently in order to correspond to the various transfer material widths. A large number of electrodes are required, and not only the heating element becomes extremely large,
The number of drive circuits for driving each heat generation pattern becomes too large, resulting in high cost and no practical use.

Further, if there is no information about the transfer material width, it is unclear which of the plurality of heat generating patterns to use, so that a transfer material width detecting means corresponding to various different transfer material widths is required. This leads to increased complexity and cost, and is not practical. Particularly, in recent years, transfer materials other than the standard size have been widely used, and there has been a problem that it is impossible to detect all the transfer material widths.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has a heating device capable of reducing the temperature rise of a non-sheet passing portion in a small size, and applying the heating device as a heat fixing device. It is an object of the present invention to obtain a completed image forming apparatus.

[0013]

According to the present invention, there is provided a heating apparatus and an image forming apparatus having the following constitutions. (1) A heating element provided on the surface of the support means in a direction perpendicular to the traveling direction of the material to be heated, a heating film moving in contact with the heating element, and a nip by pressing the heating film against the heating element Pressurizing rotator forming a portion, wherein the heating element has a different heat generation distribution in a direction orthogonal to the advancing direction of the material to be heated, and when all are energized simultaneously, the heating element is orthogonal to the advancing direction of the material to be heated. A heating apparatus comprising: a plurality of heat generating patterns provided on a heat-resistant substrate so that a temperature distribution in a direction in which heat is applied is substantially uniform. (2) The heating device according to claim 1, wherein the heat-resistant substrate is made of a ceramic substrate. (3) The heating device according to claim 2, wherein the ceramic substrate is made of titanium aluminum. (4) In an image forming apparatus having an image forming means for forming and carrying an unfixed image on a recording material and a heating and fixing means for heating and fixing the unfixed image formed and carried on the recording material, the fixing means is described. An image forming apparatus, comprising: the heating device according to claim 1.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a schematic sectional view showing a film fixing type heat fixing device according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 10 denotes an endless belt-shaped film (fixing film), which is fitted around a semicircular film guide member (stay) 13 with a margin in the circumferential length. The film 10 is made of a heat-resistant resin such as a polyimide film or a PEEK film having a total thickness of 100 μm or less, preferably 60 μm or less and 20 μm or more in order to reduce the heat capacity and improve the quick start property.

Reference numeral 11 denotes a pressure roller as a pressure rotating body, which is provided with a silicone rubber layer 11b on a metal core 11a of iron, aluminum or the like, and a PFA tube layer 11c as a release layer on the silicone rubber layer. Having.

By rotating the pressure roller 11, the film 10 is brought into close contact with the surface of the heating body 12 in the clockwise direction as indicated by an arrow at least during execution of image fixing, and slides on the surface of the heating body 12 at a predetermined peripheral speed, that is, at a predetermined peripheral speed. The transfer material P carrying the unfixed toner image T conveyed from the image forming unit shown in the drawing is rotationally driven at substantially the same peripheral speed as the conveyance speed of the transfer material P without wrinkles. The heating element 12 has energized heat generating patterns (resistive heat generating patterns) 12a and 12b as heat sources that generate heat by supplying power, and the temperature is increased by the energized heat generated by the heat generating patterns.

When the transfer material P passes through the fixing nip portion, heat energy is applied from the heating body 12 via the film 10, so that the unfixed toner image T on the surface is heated and fused. Then, after passing through the fixing nip, the transfer material P is separated from the film 10 and discharged onto a discharge tray (not shown).

The fixing film 10 used in the heat fixing device according to the first embodiment is prepared by applying a polyimide varnish to the surface of a cylindrical mold to a predetermined thickness, heating and curing the same, and then applying PF to the surface.
A, PTFE or a mixture thereof is obtained by coating and baking. As a specific example, a film substrate having a thickness of 5
0 μm polyimide and a 10 μm thick P
An FA layer was provided, and the inner diameter of the film was 25φ.

The pressure roller 11 is made of a metal core 1 made of iron, aluminum or the like.
After performing surface roughening treatment such as blasting of 1a, washing is performed, and then the core metal 11a is inserted into a cylindrical mold, and liquid silicone rubber is injected into the mold and cured by heating. At this time, in order to form a resin tube layer 11c such as a PFA tube as a release layer on the surface layer of the pressure roller, a tube coated with a primer on the inner surface in advance is inserted into the mold to heat the rubber. At the same time as curing, the tube and the rubber layer 11b are bonded. The pressure roller molded in this way is subjected to a secondary vulcanization after demolding. At this time, the diameter of the core metal of the pressure roller 11 was φ14, the thickness of the rubber layer was 4 mm, the thickness of the tube layer was 50 μm, and the pressure roller 11 had an outer diameter of about φ22.

The heating element 12, which is a heater for heating, includes A12
Ag / Pd with the pattern shown in FIG.
It is formed by performing a thick-film printing and firing, and a glass coating layer having a thickness of 50 to 60 μm is provided thereon. The heating element 12 has two patterns 12a,
12b. The heater 12 according to the first embodiment includes:
Since the thick film printing is performed once and baked using a kind of Ag · Pd ぺ list, two heat generating patterns 12a · 1
2b has a shape as shown in FIG. 2 (a) in order to give the paper a uniform calorific value over the entire region in the longitudinal direction. The pattern on the upstream side in the paper traveling direction is 12a, and the heating element in the downstream pattern is 12b.

Since the same Ag / Pd cost is used for the entire heating element, a thin portion of the heating pattern has a higher electric resistance and a larger amount of heat generation. In the heat generation pattern 12a, both ends L1 and L3 generate a large amount of heat, and the L2 portion generates a small amount of heat. Conversely, the heat generation pattern 12b generates a large amount of heat at the central portion L2 and a small amount of heat at the ends L1 and L3. Here, this device passes paper as a material to be heated based on the center of the device, so when passing small-size paper, pass through the center,
Both ends are non-paper passing portions. That is, when small-sized paper is passed, heating is performed mainly on the heat generation pattern 12b.

In the case of large-size paper, the L1 and L3 portions are mainly heated by the heating pattern 12b, and the L2 portion is mainly heated by the heating pattern 12a.
2b are energized together.

In the present invention, in order to make the amount of heat received by the paper the same in the entire area in the longitudinal direction, the total amount of the amount of heat received from the heat generating pattern 12a and the amount of heat generated from the heat generating pattern 12b are equal. The widths of the wide portions of the heat generating patterns 12a and 12b are equally D, and the widths of the narrow portions are equally C. When the longitudinal direction is L1, L2, L3, L2 = L1 + L3. As shown in the enlarged view of FIG. 2B, at the switching portion of the heat generation pattern width at both ends of L2, the heater width C is connected to the D at a distance E of about 5 to 6 mm at an angle θ at an angle θ to form a heat generation pattern width. 2 in the changing part
The total amount of heat from the heat generation pattern of the book is made uniform with other portions.

By forming the two heat generating patterns in such a shape, the total resistance of each heat generating pattern is equal, and the amount of heat generated from a narrow portion and a wide portion of each heat generating pattern is equal to each other. And a uniform calorific value can be given to the paper.

The specific numerical value is that the maximum width of the paper is LT
Because of the R size, L = 222 mm, L1 = L3 = 5
5.5 mm, L2 = 110 mm, C = 1.5 mm, D =
4.5 mm. The heater substrate width is 14 mm.

Although the heat generation distribution, that is, the resistance distribution in the longitudinal direction of the heating element 12 is adjusted by the width of the heating element, the resistance can be adjusted by the cost of the heat generation pattern. However, for this, it is necessary to apply the first strike having different resistance values several times, and it is difficult to adjust the resistance of the connection between the first strikes, which is not practical.

On the other hand, chip-shaped thermistors are provided at two positions TH1 and TH2 on the substrate opposite to the surface on which the heat generation pattern is formed (the back surface of the substrate). Position TH1 is L
In the area of No. 1 in the upstream and downstream directions of the substrate, the
Reference numeral 2 denotes the same central position in the L2 region. No thermistor is provided in the region L3. The L3 portion is unnecessary because it exhibits the same temperature behavior as the L1 portion.

In the first embodiment, the heat generation pattern 12b
The width of the L2 portion having a large heat generation distribution is 110 mm, and the size of the DL envelope (width 110 mm) or less is 12 mm.
Fix only with b. This applies to Monarch envelopes (width 98.4 mm), Com10 envelopes (width 104.7 m)
m) mainly envelopes. In this embodiment, in order to detect this size, slightly outside the DL envelope width,
A paper width sensor was provided at a position 57 mm from the center. When it is known from the paper width sensor and the paper size signal that this size is passed, the fixing is performed only by the heat generation pattern 12b.

When heating a size larger than the DL size, the same power is first applied to both the heat generating patterns 12a and 12b, but the thermistor TH1 corresponding to the non-sheet passing portion is applied.
As the temperature rises, the power ratio of the heat generation pattern 12b is reduced. In the case of a large-sized LTR or A4, fixing is performed by supplying the same power to both of the heat generation patterns 12a and 12b.

Hereinafter, the operation and effect of the present invention will be described based on specific examples.

When this heating device is applied to a laser beam printer of 16 sheets per minute (A4 size longitudinal feed), the thermistor TH2 corresponds to the center of the sheet passing area and is provided in the minimum size sheet passing area. TH1 is a region outside the width of the B5 size and is arranged at a position 10 mm from the end of the heating element 12.

The A4 size width (21
0 mm) or more, the same power is applied to the heat generation patterns 12a and 12b at a throughput of 16 sheets per minute for the transfer material (heated material), and the thermistors TH1 and TH2 provided on the heater substrate are both of the thermistor portion. Heater temperature is 1
By controlling the energization of the heat generating patterns 12a and 12b by the control circuits 21 and 22 so that the temperature becomes 90 ° C., it was possible to obtain a sufficient heating property.

On the other hand, for a transfer material having a DL size width or less, the throughput of 16 sheets per minute is increased by the thermistor TH2 in the same manner as described above.
Thus, by controlling the energization of the heat generation pattern 12b by the control circuit 22 so that the heater temperature of the thermistor portion becomes 190 ° C., it was possible to secure sufficient heating properties. Here, since the transfer material having a DL width or less has a short length in the feeding direction, the throughput can be increased to 16 sheets or more by maintaining the same sheet interval of 50 mm as the large size.
Further, assuming that a transfer material such as a narrow envelope is passed, the throughput is forcibly increased to prevent thermal damage to the heater support member, the fixing film, the pressure roller, etc. due to non-passage temperature rise at that time. Absent.

For a transfer material wider than the DL size width and smaller than the B5 size width (182 mm), the energization of the heat generation patterns 12a and 12b is controlled by the following algorithm.
It is possible to obtain the maximum throughput while maintaining the desired fixing property.

When the transfer material size is determined to be equal to or larger than the DL size by a paper width sensor (not shown) provided in the main body conveyance path, first, as shown in the flowchart of FIG. In the first embodiment, the current is supplied to 10: 1 O (steps S1 and S2).
Then, energization control is performed so that the heater temperature of the thermistor TH2 is maintained at 190 ° C. (step S3). In this state, the fixing operation of the transfer material is performed. At this time, the temperature T of the thermistor TH1 is monitored at the same time, and the temperature T becomes the specified temperature T.
1 (210 ° C. in the first embodiment) (step S4), the heater temperature T of the thermistor TH2 is maintained at 190 ° C. while the energization ratio of the heat generation patterns 12a and 12b is 9:10. Perform energization control (0.5
Power is supplied to the heat generating patterns 12a and 12b by frequency or phase control so as to maintain a predetermined power supply ratio for a period of up to 1.0 sec.).

During the operation, the thermistor T
When the heater temperature T detected in the portion H1 falls below T1, the energization ratio of the heat generation patterns 12a and 12b is reduced to 10:10 again.
The temperature control is performed with the uniform power of the heat generation patterns 12a and 12b.

When the above control is being performed, the heater temperature T of the thermistor TH1 is increased to the specified temperature T12 (220).
C.), the energization ratio of the heat generation patterns 12a and 12b is set to 8:10, and energization control is performed so that the heater temperature of the thermistor TH2 is maintained at 190 ° C. (step S).
5, S6).

Further, when the above control is being performed, the heater temperature T of the thermistor TH1 is increased to the specified temperature T3 (230
C.), the energization ratio of the heating patterns 12a and 12b is set to 7:10, and energization is controlled so that the heater temperature of the thermistor TH2 is maintained at 190 ° C. (steps S7 and S8).

Even if the control mode described above is entered, if the heater temperature T of the thermistor TH1 continues to rise and exceeds the specified temperature T4 (240 ° C.), the heat generation pattern 12
It is determined that it is impossible to suppress the non-sheet-passing temperature rise while maintaining the fixing property (particularly at the L1 and L2 portions) only by switching the energization ratios a and 12b, and temporarily interrupts the continuous feeding operation of the transfer material. (Steps S9 to S11).

Thereafter, when the temperature of the thermistor TH1 becomes equal to or lower than a predetermined temperature (220 ° C. in this embodiment), the printing operation is started again (step S1).
2). As described above, by providing a table for switching the energization ratio to the heat generating patterns 12a and 12b in accordance with the temperature detected by the thermistor TH1, it is possible to pass a sheet while maintaining a predetermined throughput without accurate transfer material width information. It is possible to do.

Here, it is considered that the heating pattern 12a should be controlled by the thermistor TH1 and the heating pattern 12b by the thermistor TH2 so as to be controlled to 190 ° C. without performing the above control. When the width is larger than the range of L2 but smaller than the thermistor TH1, the temperature rises because the thermistor TH1 becomes a non-sheet passing portion, and the control circuit 22 sharply reduces the power to the heat generation pattern 12a. Since there is a problem that the heating property of the portion outside L2 is poorly heated, the aperture is gradually reduced as described above.

By performing the above-described temperature control, for example, when the transfer material width is 170 mm and the size is irregular, in the first embodiment, even if the paper is continuously passed at a throughput of 16 sheets per minute, the thermistor 14b Heater temperature is 230
The temperature was about ℃, and the heating property was also at a sufficient level.

On the other hand, the transfer material is passed at a throughput of 16 sheets per minute, and is uniformly applied to the heating elements 12a and 12b.
When the energization control is performed, the heater temperature of the thermistor TH1 exceeds 240 ° C., and a high heat-resistant resin must be used for the film guide, which leads to an increase in cost or an A4 size or letter size immediately after. When a transfer material having a wide width such as that described above is passed, inconveniences such as a severe hot offset occurring in a portion where a non-sheet passing temperature rise is large occur.

In order to prevent such inconveniences, a detecting means for detecting the size of the transfer material more finely in the conveyance path is added, and the throughput is reduced when the transfer material having a predetermined width is passed. Although it is necessary, in addition to the inconvenience that the throughput is reduced, the cost of adding a transfer material width detecting unit is increased.

As described above, the heating heater has a plurality of heating patterns formed on the heat-resistant ceramic substrate.
Each has a different heat generation distribution in the longitudinal direction on the substrate, and a plurality of heat generation patterns are simultaneously energized, whereby the temperature distribution in the longitudinal direction on the substrate becomes substantially uniform, so that the energization ratio can be reduced. By controlling the heating device, the fixing property can be maintained, the throughput can be maintained regardless of the transfer material width, the required transfer material width detection means is minimized, and the heating device can easily handle transfer materials other than the standard size. Can be provided.

Embodiment 2 In the second embodiment, the reference position of the passing paper is set to one side instead of the center. Hereinafter, features of the second embodiment will be specifically described.

FIG. 4 shows a heater according to the second embodiment.
c, a heat generation pattern 12d on the downstream side. In the second embodiment, the same heater A as in the first embodiment is used for the entire heater.
Since the g.Pd cost is used, a thin portion of the heat generation pattern has a higher electric resistance and a larger heat generation amount. The heat generation pattern 12c generates a large amount of heat at both ends L1 and a small amount of heat at the L2 portion. Conversely, the heat generation pattern 12d has a large heat value of L2 and a small heat value of the L1 portion. Here, since this apparatus passes paper based on the L1 side end, when passing small-sized paper, it passes through the L1 area and the L2 part is a non-paper passing part. That is, when passing small-size paper, 1
2c is mainly heated.

In the case of large-size paper, the L1 portion is mainly heated by the heating pattern 12c, and the L2 portion is heated by the heating pattern 12c.
Since the heating is mainly performed at d, both the heating patterns 12c and 12d are turned on.

In the present invention, in order to make the amount of heat received by the paper the same in the entire area in the longitudinal direction, the total amount of the amount of heat received from the heat generating pattern 12c and the amount of heat generated from the heat generating pattern 12d are equal. The widths of the wide portions of the heat generating patterns 12c and 12d are set equal to D, and the widths of the narrow portions are set equal to C. When the longitudinal directions are L1 and L2, L2
= L1.

By targeting the two heat generation patterns in this manner, the heat generation amounts from the narrow portion and the wide portion of each heat generation pattern become equal, and a uniform heat generation amount is given to the paper in the entire region in the longitudinal direction. Can be.

The specific numerical values are as follows. In this apparatus, the maximum width paper is LT.
Because of the R size, L = 222 mm, L1 = L2 = 1
10 mm, C = 1.5 mm, and D = 4.5 mm. The heater substrate width is 14 mm.

On the other hand, on the substrate (the back surface of the substrate) opposite to the surface on which the heat generating patterns 12c and 12d are formed, chip-shaped thermistors are provided at two positions TH1 and TH2. TH1 is located at the center of the area L1 in the upstream and downstream directions of the substrate, and TH2 is located at the same center of the L2 area.

Also in the second embodiment, the paper width sensor
113m from the paper passing reference position slightly outside the size
m.

This heating apparatus was applied to a laser beam printer of 16 sheets per minute (A4 size longitudinal feed). The thermistor TH1 is in the minimum size transfer material sheet passing area,
H2 is an area outside the DL envelope width (110 mm),
It is arranged at a position 10 mm from the end of the heating pattern 12d.

With such a heating device, the A4 size width (2
10 mm) or more transfer material, the throughput of which is 16 sheets per minute, thermistors TH1 and TH2 provided on the heater substrate
The energization of the heating patterns 12c and 12d is controlled by the control circuit 2 so that the heater temperature of the thermistor section becomes 190 ° C.
By controlling the energization ratios of 10 and 10 to 10 and 10, it was possible to obtain sufficient heating properties.

On the other hand, the transfer material having the DL size width or less is 1 / min.
As described above, by controlling the energization of the heat generation pattern 12c by the control circuit 21 so that the heater temperature of the thermistor unit becomes 190 ° C. by using the thermistor TH1 in the same manner as described above, it is possible to obtain sufficient throughput. Was completed.

Here, since the length of the transfer material of the DL width size or less is short in the feed direction, the paper interval is 50 mm, which is the same as the large size.
The throughput can be increased to 16 sheets or more if the length is maintained. However, assuming that the transfer material such as an envelope narrower than the DL size such as a Monarch envelope is passed, the heater is supported by the non-passage temperature rise even at that time. The throughput is not forcibly increased so as not to thermally damage the members, the fixing film, the pressure roller and the like.

For the transfer material wider than the DL size width and B5 size width (182 mm) or less, the energization of the heat generation patterns 12c and 12d is controlled by the following algorithm.
It is possible to obtain the maximum throughput while maintaining the desired fixing property.

When the size of the transfer material is determined to be equal to or larger than the DL size by a sensor (not shown) provided in the main body conveyance path, first, as shown in the flowchart of FIG. Energization is performed at a ratio of 10. In the second embodiment, energization control is performed so that the heater temperature of the thermistor TH1 is maintained at 190 ° C. (steps S21 to S23). Performs the heating operation of the transfer material,
At the same time, the temperature of the thermistor TH2 is monitored, and when the temperature T exceeds a specified temperature T1 (210 ° C. in the second embodiment), the heater of the thermistor TH1 is set while the energization ratio of the heat generating patterns 12c and 12d is set to 10: 9. The energization control is performed so that the temperature is maintained at 190 ° C. (Step S2)
4).

If the heater temperature T detected by the thermistor TH2 falls below T1 during this operation,
The energization ratio of the heating patterns 12c and 12d is 10: 1 again.
The temperature is set to 0 and temperature control is performed. If the heater temperature T of the thermistor TH2 exceeds the specified temperature T2 (220 ° C.) during the above control, the heat generation pattern 12a
And 12b are 10: 8, and the thermistor TH
The energization is controlled so that the temperature of one heater is maintained at 190 ° C. (steps S25 and S26).

Further, when the above control is being performed, the heater temperature T of the thermistor TH2 is set to the specified temperature T3 (230 ° C.).
Is exceeded, the energization ratio of the heat generation patterns 12c and 12d is set to 10: 7, and the heater temperature of the thermistor TH1 is set to 1
The energization is controlled so as to be maintained at 90 ° C. (Step S2
7, S28). And even if you enter the above control mode,
When the heater temperature T of the thermistor TH2 continues to rise and exceeds the specified temperature T4 (240 ° C.), the heat generation pattern 12
It is judged that it is impossible to suppress the non-sheet-passing temperature rise while maintaining the fixing property (particularly the outer portion of the heat generation pattern 12d) only by switching the energizing ratios of c and 12d, and temporarily interrupts the continuous feeding operation of the transfer material. (Steps S29 to S31). Thereafter, the temperature of the thermistor TH1 is increased to a predetermined temperature (220 ° C.).
When the following occurs, the printing operation is started again (step S32).

By providing a table for switching the energization ratio to the heat generating patterns 12c and 12d in accordance with the temperature detected by the thermistor TH1, an excessive heat can be maintained while maintaining good heating performance without accurate transfer material width information. Continuous paper passing can be performed without a non-paper passing temperature increase.

By performing the temperature control as described above, for example, the transfer material width is 170 mm and the paper thickness is 300 mm.
Even when a very thick transfer material such as .mu.m is passed, if the paper is continuously passed at an energizing ratio of 10:10 between the heat generation patterns 12c and 12d, the heater temperature of the thermistor 14b is about 30 sheets and 240.degree. Will exceed. As a result, in the control method according to the first embodiment, the printer may stop and a problem may occur. However, by changing the heat generation ratio of the heat generation patterns 12c and 12d according to the temperature detection result of the thermistor TH2 on the way as in the second embodiment, when the same thick paper as described above is passed, 100 or more continuous paper passes. Was possible.

A control method for alternately feeding different transfer material sizes will be described below. In this example, plain paper (LTR size: 216 mm in width) and an envelope (Com
10: width 104.8 mm) will be described. At the time of printing the first page of plain paper, power is supplied at a power supply ratio of 10:10 between the heat generation patterns 12c and 12d, and power supply is controlled so as to maintain the temperature of the thermistor TH1 at a predetermined temperature (190 ° C. in the second embodiment).

Next, the envelope Com10 is fed. At this time, if it is known that the next print is plain paper, the width of the envelope is smaller than the DL size, but the thermistors TH1 and TH2 are used. Are controlled to a predetermined temperature (both 190 ° C. in the second embodiment) at a power-on ratio of 10:10 between the heat-generating patterns 12c and 12d. In this case, the temperature of the thermistor TH2 rises due to the non-sheet-passing temperature rise during the passage of the envelope, and when the temperature exceeds 200 ° C., the energization is performed at the energization ratio of the heat generation patterns 12c and 12d at 10: 9. Thermistor 14a is 190 ° C
Is controlled so as to be maintained. As described above, the temperature distribution in the ceramic substrate of the heater 12 is maintained substantially uniform by repeating this operation when the envelope is passed.

As a result, even if plain paper is fed after the envelope is passed and a heating operation is started, local fixing failure and occurrence of hot offset can be prevented. Further, in the image forming apparatus in which the heating device of the second embodiment is used as a heat fixing device, both the plain paper and the envelope are controlled to 16 sheets per minute. A paper operation is performed. As a result, the throughput of the alternate paper feeding becomes eight sets when one set of plain paper and envelope is used, and high-speed printing is possible.

In the control method described in this example, for example, in addition to the alternate paper feeding of plain paper and envelopes, the paper feeding ports are alternately switched, and narrow and wide transfer materials are alternately fed. The present invention is also applicable to a case where a transfer material whose size is unknown is fed.

As described above, a plurality of independently driven heat generating patterns having different heat distributions in the longitudinal direction are provided, and by controlling the energization ratio of these heat generating patterns, the heating property is maintained, the transfer material width, the transfer material width, and the like. A long-term continuous printing is possible regardless of the thickness, and a heating device that can easily cope with a transfer material having a size other than the standard size can be obtained.

Embodiment 3 The third embodiment uses a back surface heater 12 in which the back surface of the substrate is in contact with the heating nip surface, in contrast to the configuration of the above embodiment, and the heating body 12 is made of aluminum nitride (AIN) for the substrate. Used. The AIN substrate has advantages mainly in the following characteristics as compared with the conventional alumina substrate.

The AIN substrate has a thermal conductivity of 220 (W / m ·
° k) and about 11 times higher than that of the alumina substrate (20 W / m · ° k), and the heat capacity is as small as about 2/3 if the volume is the same. And the thermal shock resistance is about twice as high, so that the advantage is obtained that even when the heating pattern is made thinner and used at a high temperature, the substrate is hardly damaged by rapid heating.

In particular, since the AIN substrate has a thermal conductivity that is about two orders of magnitude higher than that of the glass coat layer, the thickness of the substrate is at least 10 times greater than that of the glass coat layer (the substrate thickness is about 0.5 to 0.8 mm, In the third embodiment, the thickness is 0.65 mm, while the glass thickness is about 30 to 60 μm.)
Nevertheless, as in the third embodiment, a current-carrying heating pattern 12a and a glass coat layer (not shown) are formed on the upper surface of the substrate.
And the temperature detecting element 14 are arranged, and the backside heating type AIN heating element 12 in which the backside of the substrate contacts the fixing nip surface can be used. Heating can be uniformly and widely performed as a whole, and high fixability can be maintained even when the speed is increased. Further, since the temperature distribution in the longitudinal direction is also easily made uniform, there is an effect of alleviating the excessive temperature rise in the non-sheet passing portion, which is a problem when small size paper is continuously passed.

In the third embodiment, the heat generation pattern is shown in FIG. 6, however, it is the same as that shown in FIG. 2 of the first embodiment, and two systems of heat generation patterns 12a and 12b are used in accordance with the transfer material width. The energization is controlled by changing the energization ratio.

The heating element 12 on which the heat generation pattern shown in FIG. 6 is formed on the AIN substrate is obtained by printing a thick film of Ag.Pd paste and firing it, on which a glass coating layer having a thickness of 30 mm is formed. ５０50 μm. On the other hand, the surface of the substrate opposite to the surface on which the heat generation pattern is formed is smoothed by lapping or providing a thin glass coating layer having a thickness of 15 μm or less, thereby improving the slidability with the film. Thermistors TH1 and TH2 are also arranged in the same manner as in the first embodiment. In the third embodiment, no paper width sensor is provided.

On the other hand, for a transfer material having a B5 size width or less, the energization of the heat generating patterns 12a and 12b is controlled by the following algorithm, and a desired fixing property can be obtained. As shown in the flowchart of FIG. 7, first, the paper of all sizes is transferred to the heat generating patterns 12a and 12b by 10:
10 is energized, and in the third embodiment, the thermistor T
The energization control is performed so that the heater temperature of the H2 portion is maintained at 190 ° C. (steps S41 to S43). In this state, the fixing operation of the transfer material is performed. At this time, the thermistor TH is simultaneously operated.
1 is monitored, and when the temperature T exceeds a specified temperature T1 (210 ° C. in the third embodiment), the heater temperature of the thermistor TH2 is increased while the energization ratio of the heat generating patterns 12a and 12b is 9:10. The energization control is performed so as to be maintained at 190 ° C. (steps S44 to S46).

During this operation, the thermistor T
When the heater temperature T detected in the portion H1 falls below T1, the energization ratio of the heat generation patterns 12a and 12b is reduced to 10:10 again.
And temperature control is performed. A4 size width (210m
m) or more of the transfer material has a throughput of 16 sheets per minute, and the energization of the heat generation patterns 12a and 12b is 10:10.
It could be obtained while securing sufficient fixing property.

When the above control is being performed, the heater temperature T of the thermistor TH1 is set to the specified temperature T2 (220
C.), the energization ratio of the heat generation patterns 12a and 12b is set to 7:10, and energization control is performed so that the heater temperature of the thermistor TH2 is maintained at 190 ° C. (step S).
47, S48).

Further, when the above control is being performed, the heater temperature T of the thermistor TH1 becomes the specified temperature T3 (230 ° C.).
Is exceeded, the energization ratio of the heat generation patterns 12a and 12b is 5:10, and the heater temperature of the thermistor TH2 is 1
The energization is controlled to be maintained at 90 ° C. (step S4
9, S50). At this time, the feeding interval of the transfer material during continuous feeding is controlled to be 12 sheets per minute. After this, 220
When the temperature has become lower than or equal to ° C, the process returns to step S41 again (step S52).

When the temperature of the heater of the thermistor TH1 continues to rise even after entering the above control mode and exceeds the specified temperature T4 (240 ° C.), the energizing ratio of the heat generating patterns 12a and 12b is set to 3:10. At this time, the feeding interval of the transfer material during continuous feeding is controlled to be 10 sheets per minute (step S51).

When the size of the transfer material is equal to or smaller than the DL size, in the third embodiment, printing is performed at a throughput of 10 sheets per minute in a mode with an energization ratio of 3:10.

The contact of the high heat conductive member with the heating element 12 in this way slightly reduces the throughput. However, it is possible to cope with each size without providing a paper width sensor, which contributes to simplification of the apparatus. Was. Needless to say, even when an AIN substrate is used for the heating element 12, the same control as in the first embodiment can be performed by using a paper width sensor.

Embodiment 4 FIG. 8 is a schematic configuration diagram illustrating an image forming apparatus to which any one of the heating devices according to the first to third embodiments is applied as a heat fixing device.
In FIG. 8, reference numeral 15 denotes a photosensitive drum, which has a structure in which a photosensitive material such as OPC, amorphous Se, amorphous Si or the like is formed on a cylindrical substrate such as aluminum or nickel. The photosensitive drum 15 is driven to rotate in the direction of the arrow, and first, its surface is uniformly charged by a charging roller 16 as a charging device. Next, a laser beam 17 serving as an exposure unit is set to 0 N / OF in accordance with image information.
F control is performed to perform scanning exposure, and an electrostatic latent image is formed on the photosensitive drum 15. This electrostatic latent image is developed by the developing device 18 and visualized. As a developing method, a jumping developing method, a two-component developing method, or the like is used, and in many cases, a combination of image exposure and reversal developing is used. The visualized toner image is transferred from the photosensitive drum 15 by a transfer roller 19 as a transfer device onto a transfer material P fed and conveyed from a feed port such as a cassette or a multi-purpose tray at a predetermined timing. . The transfer material P holding the toner image is conveyed to the fixing device 20, and is heated and pressed at the nip portion of the fixing device to be fixed on the transfer material to be a permanent image. On the other hand, the transfer residual toner remaining on the photosensitive drum 15 after the transfer is transferred to the photosensitive drum 1 by the cleaning device 21.
5 Removed from the surface.

[0082]

As described above, according to the present invention,
The heating element has a plurality of heat generation patterns on a heat-resistant ceramic substrate, each having a different heat generation distribution in a direction orthogonal to the direction in which the material to be heated advances, and the plurality of heat generation patterns are simultaneously energized, so that the heat The temperature distribution in the direction orthogonal to the direction of travel of the heated material is substantially uniform, so that the temperature difference between the paper passing area and the non-paper passing area, particularly when a narrow transfer material is passed. Is minimized, and there is an effect of preventing hot offset of large-sized paper after small-sized paper.

Even when transfer materials of different sizes are alternately fed, phenomena such as hot offset and poor heating can be effectively prevented without significantly lowering the throughput.

Further, since the ceramic substrate is made of titanium aluminum, the same function and effect as described above can be obtained with a simpler configuration.

Further, since the heating device of the present invention is applied to the image forming apparatus as a heat fixing device, there is an effect that the fixing can be surely performed and a high quality image can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a heating device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of the heating element.

FIG. 3 is a control flowchart of the heating element.

FIG. 4 is a configuration diagram of a heating element according to a second embodiment of the present invention.

FIG. 5 is a control flowchart of the heating element.

FIG. 6 is a configuration diagram of a heating element according to Embodiment 3 of the present invention.

FIG. 7 is a control flowchart of the heating element.

FIG. 8 is a schematic diagram of an image forming apparatus in which the heating device of the present invention is applied to a heat fixing device.

[Explanation of symbols]

10 Pressing (film), 11 Rotating body for pressure, 12
Heating body, 12a to 12d Heat generation pattern, 13 Supporting means, 15 Photosensitive drum (Image forming means), 16 Charging roller (Image forming means), 17 Exposure (Image forming means), 18 Developing device (Image forming means), 19 Transfer Roller (image forming means), 20
Heat fixing device, P Heated material (recorded material), N nip.

Continued on the front page (72) Inventor Masahiko Suzumi 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H033 AA03 BA25 BA26 BA27 BE03 CA30 3K058 AA86 BA18 CA23 CA61 CE02 CE13 CE19 DA04 DA06 GA03 GA06

Claims (4)

[Claims] 1. A heating body provided on a surface of a support means perpendicular to a traveling direction of a material to be heated, a heating film moving in contact with the heating body, and pressing the heating film against the heating body. And a rotating body for pressure forming a nip portion,
The heating element has a different heat generation distribution in a direction orthogonal to the heating material advancing direction, and when all are energized simultaneously, the temperature distribution in the direction orthogonal to the advancing direction of the heating material is substantially uniform. A heating device comprising: a plurality of heat generating patterns provided on a heat-resistant substrate. 2. The heating device according to claim 1, wherein the heat-resistant substrate is made of a ceramic substrate. 3. The heating device according to claim 2, wherein the ceramic substrate is made of titanium aluminum. 4. An image forming apparatus comprising: an image forming means for forming and carrying an unfixed image on a recording material; and a heat fixing means for heating and fixing the unfixed image formed and carried on the recording material. An image forming apparatus, comprising: the heating apparatus according to claim 1.