JP2002207391A - Heating device and image forming device equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating device capable of preventing the deterioration and breakage of the heating device due to consecutively feeding at the continuous heating processing of a recording material such as a small-sized paper, etc., besides, capable of preventing an defective image on the following recording material after the consecutively feeding at the continuous fixation processing of the recording material such as a large-sized paper, etc., and to provide an image forming device equipped with the heating device. SOLUTION: When various small-sized recording materials are consecutively carried to a fixation nip part N, the comparison of a power Pn which is supplied from a power source 26 to a heater 3 when an n-th recording material is heated with a power Pn-1 which is supplied from the power source 26 to the heater 3 when the n-1 recording material is heated is performed by a CPU 24, and in the case Pn-Pn-1 is exceeding a prescribed value Δ P, the power to be supplied from the power source 26 to the heater 3 is interrupted or reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device used for an image forming apparatus such as a copying machine and a laser beam printer, and an image forming apparatus provided with the heating device.

[0002]

2. Description of the Related Art Conventionally, in a heating apparatus for heating a recording material carrying an image, for example, by heating and fixing an unfixed image on the recording material on the recording material, a predetermined temperature is maintained. A heat roller system is widely used in which a recording material is nipped and conveyed by a heating roller having an elastic layer and a pressure roller having a pressure contact with the heating roller, and the recording material is heated while being pressed.
In addition, various systems and configurations such as a flash heating system, an oven heating system, and a hot plate heating system are known and are in practical use.

Recently, instead of the above method,
A heater that is a fixedly supported heating element, a heat-resistant fixing film that is a film-shaped film member that slides with respect to the heater, and a nip area formed by being pressed by the heater via the fixing film to rotate A pressure roller as a pressure member, and heats the heat from the heater through the fixing film while passing the recording material between the fixing film and the pressure roller in the nip region and pressing the recording material. There has been proposed a heating device of a film heating type for applying heat to the recording material by heating the recording material (for example, a fixing device for heating and fixing an unfixed image on the recording material on the recording material). The power supply from the power supply is controlled by the power control means so that the heater is maintained at a predetermined target temperature.

[0004] In such a film heating type heating device, since a heating element having a low heat capacity can be used, a heat roller type, which is a conventional contact heating type, can be used.
It is possible to save power and shorten the wait time (quick start) as compared with a belt heating system or the like.

[0005]

However, in the above-described heating apparatus of the heat roller type, the film heating type, or the like, when the recording material is fed to the nip area by multi-feeding, the following problem occurs.

First, when a recording material having a width somewhat smaller than the maximum size that can be passed (hereinafter, referred to as a small size paper) is fed into the nip area by multi-feeding, the non-sheet passing portion of the nip area Since the heat is not taken away by the recording material, the temperature of the recording material becomes higher than that of the paper passing portion (hereinafter, referred to as a non-paper passing portion temperature increase).

In particular, when a small recording sheet and a thick recording material such as thick paper or an envelope (hereinafter, referred to as small cardboard) are fed in a multi-feed manner and passed through the nip area, recording is performed in the paper passing portion of the nip area. A large amount of heat is taken by the material, and the temperature is controlled based on the output of the temperature detecting element provided in the sheet passing portion, so that a large amount of electric power is supplied to the heater. On the other hand, in the non-sheet passing portion, the recording material does not lose heat, so the temperature becomes extremely high.In the heating device of the heating roller type, the fixing roller and the pressure roller are deteriorated or damaged, while the heating of the film heating type is performed. In the apparatus, there is a possibility that the heater, the heater stay, the fixing film, the pressure roller and the like may be deteriorated or damaged.

When a recording material having a width close to the maximum size that can be passed through the nip area (hereinafter, referred to as a large-size sheet) is fed to the nip area by multi-feeding, the non-sheet passing area of the nip area is not passed. Since the area of the sheet is small, the possibility of deterioration or damage of the heating device due to the temperature rise of the non-sheet passing area is small, but when the toner is transferred to the fixing roller or the fixing film due to the fixing failure and the subsequent recording material is printed. The image may be dirty. This image defect may also occur when multiple small-size paper sheets are fed.

Therefore, the present invention prevents deterioration and breakage of a heating device due to double feeding or the like during continuous heating of recording materials such as small-size paper, and furthermore, prevents continuous fixing of recording materials such as large-size paper. It is an object of the present invention to provide a heating device capable of preventing an image defect on a succeeding recording material after the double feeding in the above, and an image forming apparatus provided with the heating device.

[0010]

According to the present application, the object is to provide a heating element for heating a recording material carrying an image by receiving power from a power supply, and to heat the heating element to a predetermined target temperature. A power control means for controlling the power supply from the power supply to the heating element to maintain the power supply, comprising: a power detection means for detecting the power supplied from the power supply to the heating element, the control means, Based on the electric power detected by the detecting means, when a predetermined same type of recording material is continuously subjected to the heat treatment, the electric power is detected by the power detecting means when the nth recording material is being subjected to the heat treatment. Power P
_n and the power P _n-1 detected by the power detection means when the (n-1) th recording material is being heated, and P _n -P _n-1 is determined to be a predetermined value ΔP This is achieved by the first invention in which the power supply from the power supply to the heating element is set to be cut off or reduced when the power is larger than the power supply.

Further, according to the present invention, the above object is achieved in the first aspect, wherein the electric power control means detects the electric power detected by the electric power detection means when the first half in the conveying direction of the recording material is being heated. It is also attained by the second invention that a determination is made as to whether or not P _n -P _n- 1> ΔP.

Further, according to the present invention, the above object is achieved in the first invention or the second invention, wherein the power control means has a width in a direction perpendicular to a conveying direction of the recording material subjected to the continuous heating process. If narrower than a predetermined width, P _n -P _n-1> blocking or reducing the power supplied to the heating body from the power supply when the [Delta] P, perpendicular direction of the conveying direction of the recording material to be subjected to continuous heat treatment When the width is wider than the predetermined width, the third invention is also achieved in that the power supplied from the power supply to the heating element is set to be increased when P _n −P _n−1 > ΔP.

According to the present application, the above object is provided in any one of the first to third inventions, comprising a temperature detecting means for detecting a temperature of the heating element, wherein the power control means comprises the temperature detecting means. The present invention is also achieved by the fourth invention in which the power from the power supply to the heating element is controlled so that the temperature detected by the means becomes a predetermined target temperature, and ΔP is set corresponding to the target temperature.

Further, according to the present application, the above object is achieved in any one of the first to fourth inventions by providing a film-like film member sliding on a heating element, A pressure member that forms a nip area pressed by the heating element, and heats the recording material carrying an image between the film member and the pressure member in the nip area while pressing the recording material. This is also achieved by the fifth invention in which processing is performed.

Further, according to the present application, the object is an image forming apparatus for recording an image formed by a series of image forming processes on a recording material, wherein the image forming apparatus is any one of the first to fifth inventions. The invention is also attained by the sixth invention including the heating device of (1).

[0016]

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

(First Embodiment) First, a first embodiment of the present invention will be described.

FIG. 1 is a sectional view showing a schematic configuration of a main part of a laser beam printer as an example of an image forming apparatus according to the present embodiment.

As shown in FIG. 1, such a laser beam printer has an organic photosensitive drum 101 as an image carrier, a charging roller 102 as a charging member, and a laser exposure device 1.
03, a developing device 104 employing a developing method using a one-component magnetic toner, a cleaning blade 105, a transfer roller 106, a heating device 107, and the like.

In the laser beam printer, first, the organic photosensitive drum 101 is uniformly charged to a negative charge by the charging roller 102, and the laser exposure device 1
03 and the organic photosensitive drum 10
1, an electrostatic latent image is formed.

Next, the electrostatic latent image on the organic photosensitive drum 101 is visualized as a toner image by charging the charged toner in the developing device 104 to the electrostatic latent image.

The toner image is transferred to the transfer roller 10
After being transferred to the recording material paper by the fixing device 6, the recording material is fixed on the paper by a heating device 107 as a fixing device.

On the other hand, the toner remaining on the organic photosensitive drum 101 is removed from the organic photosensitive drum 101 by the cleaning blade 105.

In this manner, an image is recorded on paper as a recording material by the operation of each unit as described above.

Here, the heating device 107 according to the present invention will be described. In the present embodiment, a film heating type heating device will be described as an example, but the present invention is also applicable to a heating device such as a heat roller type, and is not limited to a film heating type heating device. .

FIG. 2 shows a heating device 10 according to this embodiment.
7 is a schematic configuration diagram illustrating an example of FIG. In the heating device 107 of the present embodiment, the maximum sheet passing width is A4 length.

In the present embodiment, Japanese Patent Application Laid-Open No. 4-44075
No. 44083, 4-204980-204498
An example in which the present invention is applied to a so-called tensionless type heating device disclosed in Japanese Unexamined Patent Publication (Kokai) No. H10-15095 will be described. This tensionless type heating device uses an endless belt-like or cylindrical one as a heat-resistant film as a film member, and at least a part of the circumferential length of the film is always tension-free (state in which tension is not applied). The film is a device configured to be rotated by the rotational driving force of the pressing member.

As shown in FIG. 2, the heating device 107 of this embodiment comprises a film 2 as a film member, a heater 3 as a heating element, a pressure roller 4 as a pressure member, and a temperature detecting element 5 as a temperature detecting means. And a CPU 24 serving as power detection means and power control means.

The film 2 is an endless heat-resistant film, and is fitted on a stay 1 which is a film guide member including the heater 3. Since the inner peripheral length of the film 2 is, for example, about 3 mm larger than the outer peripheral length of the stay 1 including the heater 3, the endless and heat-resistant film 2 is fitted around the stay 1 with a margin in the peripheral length. .

The stay 1 can be made of a high heat resistant resin such as polyimide, polyamide imide, PEEK, PPS, liquid crystal polymer, or a composite material of these resins with ceramics, metal, glass and the like. In this embodiment, a liquid crystal polymer is used.

The film 2 has a film thickness of 10 to reduce the heat capacity and improve the quick start property.
0 μm or less, preferably 50 μm or less 20 μm or more heat-resistant single-layer film such as PTFE, PFA, FEP, or polyimide, polyamide imide, PEEK,
PTFE, PPS on the outer surface of the film such as PES, PPS
A composite layer film coated with FA, FEP or the like can be used. In the present embodiment, a polyimide film having a thickness of about 50 μm and having an outer peripheral surface coated with PTFE is used.

FIG. 3 is a front view of the heater 3 which is a heating element according to the present embodiment, and a diagram showing a configuration of a circuit for controlling the energization thereof.

The heater 3 is an elongated heat-resistant, insulating and good heat-conductive substrate 31 whose longitudinal direction is perpendicular to the conveying direction a of the heat-resistant film 2 or the recording material P as a material to be heated. A resistance heating element 32 formed along the longitudinal direction of the substrate 31 at the center in the lateral direction on the front side of the substrate 31; a heat-resistant overcoat layer 34 protecting the surface of the heater 3 on which the resistance heating element 32 is formed; It is a heating element having a low heat capacity as a whole, comprising power supply electrodes 21 and 22 at both longitudinal ends of the resistance heating element 32.

On the back surface (non-film sliding surface) of the heater 3 shown in FIG. 3, a temperature detecting element 5 is provided within the minimum sheet passing area. In the present embodiment, the temperature measuring element 5 is adhered to the back surface of the heater 3 with an adhesive having heat resistance, electrical conductivity, and excellent thermal conductivity, and the temperature measuring element 5 is connected to the CPU 24.

The heater 3 is fixedly arranged such that the surface (film sliding surface) on which the resistance heating element 32 is formed is exposed downward and held on the lower surface of the stay 1.

As the substrate 31 of the heater 3, for example, a material such as alumina or aluminum nitride is used. In the present embodiment, an alumina substrate having a thickness of 1 mm, a width of 7 mm, and a length of 270 mm is used.

The resistance heating element 32 is made of, for example, Ag / Pd
(Ag palladium), RuO ₂ , Ta ₂ N, etc. are formed by applying an electric resistance material such as screen printing or the like in a linear or linear band form. In the present embodiment, Ag / Pd is applied by screen printing. It was formed by coating to a thickness of about 10 μm and a width of 3 mm.

As the power supply electrodes 21 and 22, a screen printing pattern layer of Ag / Pd was used.

As the overcoat layer 34, a heat-resistant glass layer having a thickness of about 50 μm was used.

The pressure roller 4 forms a pressure contact nip portion (fixing nip portion) N with the film 3 interposed between the pressure roller 4 and the heater 3 and also serves as a film outer surface contact drive means for driving the film 2 to rotate. The pressure roller 4 has a core 4a.
And an elastic layer 4b made of silicone rubber or the like, and an outermost release layer 4c. The bearing means and the urging means (not shown) provide a predetermined pressing force to the heater 3 via the film 2. It is arranged in pressure contact with the surface. The rotation of the pressure roller 4 causes the pressure roller 4 and the film 2 to rotate.
The rotational force acts on the film 2 by the frictional force generated between the film 2 and the outer peripheral surface.

The temperature of the heater 3 rises as the resistance heating element 32 generates heat over its entire length by power supply from the power supply 26 to the power supply electrodes 21 and 22 at both longitudinal ends of the resistance heating element 32. The temperature rise is detected by the temperature detecting element 5, the output of the temperature detecting element 5 is A / D converted and taken into the CPU 24,
The temperature of the heater 3 is controlled by controlling the driving of the triac 25 by the CPU 24 based on the information to control the power supplied to the resistance heating element 32 by controlling the phase and wave number. That is, by controlling the energization so that the temperature of the heater 3 rises when the temperature detected by the temperature detecting element 5 is lower than the set temperature, which is a predetermined target temperature, and to lower the temperature when the temperature is higher than the set temperature, the heater 3 is activated during fixing. It is kept at a constant temperature.
In the present embodiment, the output to the heater 3 is changed from 0% to 100% in 21 steps in 5% increments by phase control. The output of 100% indicates the output when the heating element is fully energized.

When the temperature of the heater 3 rises to a predetermined value and the rotational peripheral speed of the film 2 is stabilized by the rotation of the pressure roller 4, the heater 3 and the pressure roller 4 sandwich the film 2 therebetween. A recording material P to be image-fixed as a material to be heated is introduced from the image forming portion (transfer portion) between the film 2 and the pressure roller 4 in the pressure nip portion N formed by When the nip portion N is nipped and conveyed, the heat of the heater 3 is applied to the recording material P via the film 2 and the unfixed visible image (toner image) T on the recording material P is heated and fixed on the surface of the recording material P. . Fixing nip N
The recording material P that has passed through is transported separated from the surface of the film 2.

Conventionally, in the above-described heating apparatus, when small-size paper (for example, B5 lengthwise) is fed to the nip area by double feeding, the heater, heater stay, fixing film In addition, there is a possibility that the pressure roller and the like may be deteriorated or damaged. In particular, when a small-sized thick paper is passed through the nip area by being double-fed, the temperature of the non-paper passing portion rises remarkably, and the risk of deterioration and breakage increases.

In this embodiment, when the same type of small-size paper is continuously passed through the fixing nip N, the power consumption of the heater 3 while the recording material is passing through the fixing nip N is measured. The power consumption of the heater 3 when the n-th recording material is passed through the fixing nip portion N and the n-th recording material before (n−1)
By comparing the power consumption of the heater 3 when the recording material of the (sheet) is passed through the fixing nip N,
Detects double feed of small size paper and prevents deterioration and breakage of the heating device.

FIG. 4 is a flowchart for explaining the drive control of the heater 3 by the CPU 24 in the present embodiment.

In this embodiment, first, when the image forming apparatus receives the print signal, it is determined whether or not the image forming (heating process) in the image forming apparatus is a continuous output of the same type of small-sized paper. Is performed (S1). Which width or less of the recording material is regarded as the small size paper can be appropriately set according to the image forming apparatus. In this embodiment, a recording material having a width of B5 length or less is a small-size sheet. Information on the size of the recording material and whether the output is continuous or only one is obtained from a terminal or the like used by the user via a formatter.

If it is determined in S1 that the form of image formation is not continuous output of the same type of small-size paper, the power consumption of the heater 3 is not measured (S9).

If it is determined in S1 that the image forming mode is a continuous output of the same type of small-size paper, the power P1, which is the power consumption of the first heater 3, is measured (S1).
2). In the present embodiment, the power consumption of the heater 3 is measured by accumulating and averaging the power values determined by the phase control in the CPU 24 and output to the heater 3 for a certain period of time from a certain timing. Therefore, the unit of the measured power value is%. Integration is performed every time the output is updated (several meters
sec. Every).

FIG. 5 shows a heating device 10 according to this embodiment.
FIG. 7 is a schematic diagram illustrating a time change of power consumption of FIG.

As shown in FIG. 5, in this embodiment, the recording material enters the fixing nip N for 0.5 sec. After 1.5 sec. 1.0 sec. Power between C
The PU 24 is measuring. The time when the recording material enters the fixing nip portion N is determined by a sensor (not shown) provided on the upstream side of the heating device 107 in the recording material conveyance direction. It is measured afterwards.

If the time for measuring the power consumption of the heater 3 is too long, the temperature rise in the non-sheet passing portion is already large at the time when the double feed is detected, and the effect of preventing the heating device from being deteriorated or damaged is not sufficient. If it is short enough, the measurement accuracy required for double feed detection cannot be obtained. In the present embodiment, 0.
5 sec. After 1.5 sec. 1.0 sec.
During the measurement, the double feed was detected with the highest accuracy, and there was no false detection. In order to further improve the detection accuracy, the measurement time and the measurement timing can be changed according to the size of the recording material in the transport direction.

After the measurement of the electric power P ₁ at the time of passing the fixing nip portion N of the first recording material, the power P ₂ at the time of passing the fixing nip portion N of the second recording material is measured in the same manner. (S3).

Thereafter, P ₂ −P ₁ is compared with ΔP (S
4) If P ₂ −P ₁ > ΔP, it is determined that multi-feeding has occurred (S
5) If P ₂ −P ₁ ≦ ΔP, it is determined that multi-feeding is not performed, and power measurement of the next sheet is performed (S6).

If it is determined that the double feeding is not performed, the above measurement is repeated until the continuous output is completed. That performs a comparison between the power difference P _n -P _n-1 and [Delta] P of the previous number (S7), and determines that in the case of P _n -P _n-1> ΔP is double feed (S5), _{If Pn-Pn-} 1≤ [Delta] P, it is determined that multifeed is not performed, and the process returns to S6. In this embodiment, ΔP is 20
%. That is, if the average output of the recording material during the passage through the fixing nip N is larger than 20% as compared with the previous number, it is determined that the multi-feed has been performed. If the value of ΔP is too large, double feed may not be detected in some cases. If the value of ΔP is too small, double feed may be erroneously detected when double feed is not performed.

When a double feed is detected by the above control,
In order to suppress the temperature rise in the non-sheet passing portion of the fixing nip portion N, the power supply to the heater 3 is stopped or the power supply power is forcibly reduced (S8). The target temperature of the heater 3 may be greatly reduced.
If a double feed is detected, it is also possible to issue a message notifying the user to that effect.

FIG. 5 shows a comparison of power changes in the heating apparatus 107 according to the present embodiment when no double feeding is performed and when double feeding is performed.

In FIG. 5, the (n-1) th sheet is not multi-fed, the case where the n-th sheet is not multi-fed is indicated by a solid line, and the case where the n-th sheet is multi-fed is indicated by a broken line. The (n-1) th heating device 10
The power passing through 7 is approximately constant at 55 to 60%. n
When the multi-feed is not performed, the power is the same. However, when the multi-feed is performed, a large amount of power is supplied to maintain the temperature of the heating element because the amount of heat taken by the recording material increases.

In the case of FIG. 5, the power P _n-1 of the ( _{n-1) -th} sheet is 57.5%, and the power Pn of the n-th sheet in the case of not performing double feeding is 58.
0%, the power Pn of the n-th sheet when multi-feeding is measured is 86.0%, and when multi-feeding is performed, P _n -P _n-1 = 28.0%> ΔP
Since the electric power Pn is measured, the power supply to the heater 3 is stopped.

When the target temperature of the heating element is changed while the recording material is continuously output, the power during the passage of the recording material changes even if the multi-feed is not performed. Therefore, to prevent false detection,
In the present embodiment, power comparison is not performed before and after the target temperature change. However, only before and after the target temperature change, ΔP can be separately set in consideration of the power difference due to the temperature change, and the double feed detection similar to the present embodiment can be performed. Further, ΔP may be set for each target temperature in order to improve detection accuracy.

Next, a comparison between the case where the control of this embodiment is used and the case where it is not used will be shown.

As described above, the control according to the present embodiment is carried out with P _n −
When P _n-1 > 20%, the control to stop the current supply to the heating element is performed. In the comparative example, the configurations of the heating device and the image forming device other than the control were all the same.

For comparison between the present embodiment and the comparative example, a test was conducted in which one small-size sheet was first passed, and then the small-size sheet continuously and forcibly fed was passed. or,
At the same time, a test to increase the number of sheets to be multi-fed was also performed. For small size paper, paper width 105mm, length in the transport direction 240m
m envelope was used.

When the control according to the present embodiment is used, the double feed is detected when the multi-fed small-size paper is passed, and the power supply to the heating element is stopped. Did not. Also, even if the number of multi-feeds was increased to 5, no deterioration or breakage of the heating device occurred.

On the other hand, when the control according to the present embodiment is not used, the paper is passed as usual even if the multi-feed is performed, and the image is formed on the surface layer of the pressure roller when ten sheets of the multi-fed small size paper are continuously passed. Deterioration to the extent of affecting was observed. Further, as the number of multi-feeds was increased, the degree of deterioration of the surface layer of the pressure roller was increased, and the heater was damaged in the quintuple-feed test.

From the above results, it can be seen that the use of the control of the present embodiment greatly reduces the risk of deterioration and breakage of the heating device due to the double feeding of small size paper.

(Second Embodiment) Next, a second embodiment of the present invention will be described. Note that the same components as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the present embodiment, in addition to the control described in the first embodiment, control is performed to increase the power when a double feed is detected on large-size paper. The method for detecting double-feeding of small-size paper, and the configurations of the heating device and the image forming apparatus are the same as those of the first embodiment. In the present embodiment, when the width of the recording material is B5 portrait or less, it is regarded as small size paper, and when the width of the recording material is A4 portrait size, it is regarded as large size paper. Also, double feed detection is not performed for the size between B5 vertical and A4 vertical. As described in the first embodiment, which size of the recording material is regarded as the large size paper or the small size paper can be appropriately set according to the image forming apparatus.

FIG. 6 is a flowchart showing the drive control of the heating device in this embodiment.

First, when the image forming apparatus receives the print signal, it is determined whether or not the form of image formation (heating processing) is continuous output of the same type of large-size paper (S1).
1). At this time, as in the first embodiment shown in FIG.
It is also determined at the same time whether or not continuous output of the same type of small-size paper is performed. If the output is continuous output of the same type of small-size paper, the same control as in the first embodiment is performed.

If it is determined in S11 that the form of image formation is not continuous output of the same type of large-size paper, power measurement is not performed (S19).

If it is determined in S11 that the form of image formation is continuous output of the same type of large-size paper, the power P
₁ is measured (S12). The power measurement method is the same as in the first embodiment.

After the power measurement of the first sheet is completed, the power P ₂ of the second sheet is measured by the same method (S13).

Thereafter, P ₂ −P ₁ is compared with ΔP (S 1
4) If P ₂ −P ₁ > ΔP, it is determined that multi-feeding has occurred (S
15), if P ₂ −P ₁ ≦ ΔP, it is determined that multi-feeding is not being performed, and power measurement of the next sheet is performed (S16).

If the double feed is not performed, the same measurement as described above is repeated until the continuous output is completed. That is, the power difference from the previous number is compared with ΔP (S17), and P _n −P _n−1
If it is> ΔP, it is determined that double feed is present (S15), and P _n −
If P _n-1 ≤ ΔP, it is determined that multi-feeding is not performed, and S16
Return to In the present embodiment, the value of ΔP is set to 20% both when detecting large-size multi-feed and when detecting small-size paper multi-feed. That is, if the average output during the passage through the fixing nip N is larger than 20% as compared with the previous sheet number, it is determined that the multi-feed has been performed. As in the first embodiment, if the value of ΔP is too large, double feeding may not be detected in some cases.

When a double feed is detected by the above control,
A process for forcibly increasing the energized power is performed (S18). In the present embodiment, the power is uniformly increased by 10%. The target temperature of the heater 3 may be increased. If a double feed is detected, it is also possible to issue a message notifying the user to that effect.

When large-size paper is multi-fed, the possibility of deterioration or breakage of the heating device due to the rise in the temperature of the non-sheet passing portion is small because the area of the non-sheet passing portion is small. (In the case of a heat roller system, a fixing roller), and the image may be stained when the next recording material is printed. As in the present embodiment, when the double feed is detected, by controlling the power to be increased, the transfer amount of the toner to the fixing film can be reduced, and the image defect of the next recording material can be prevented. Can be. Although the image defect after the double feeding may occur at the time of the double feeding of the small size paper, in the present embodiment, the priority is given to the prevention and the deterioration of the heating device in the case of the small size paper.

In the present embodiment, as in the first embodiment, power comparison is not performed before and after the target temperature of the heating element is changed. However, only before and after the target temperature change, ΔP can be separately set in consideration of the power difference due to the temperature change, and the double feed detection similar to the present embodiment can be performed. Further, in order to improve the detection accuracy, ΔP and the power to be increased in the case of large-size paper may be set separately according to the target temperature.

Next, a comparison between the case where the control of this embodiment is used and the case where it is not used will be shown.

[0079] Control of the present embodiment, as described above, when the large size sheet is continuously output _{P n -P n-1> 20} %
At this time, the control is to increase the power by 10%. In the comparative example, the configurations of the heating device and the image forming apparatus other than the control were all the same as in the present embodiment.

For comparison between the present embodiment and the comparative example, first, one large-size sheet is passed, and then five large-size sheets that are forcibly fed continuously are passed, and further double-feed is performed. A test was conducted in which one large-size paper sheet was passed. A4 size smooth paper was used as the large size paper.

When the control according to the present embodiment is used, the double feed is detected and the power is increased at the time when the double fed large size paper is passed, so that neither toner transfer to the fixing film nor image failure occurs. Did not.

On the other hand, when the control of this embodiment is not used, a fixing failure occurs at the time of multi-feeding, and a phenomenon that the next paper is stained occurs.

From the above results, it can be seen that the use of the control of the present embodiment prevents image defects of the next recording material due to double feeding of large-size paper.

[0084]

As described above, according to the first aspect of the present invention, the power detection means detects the power supplied from the power supply to the heating element, and the control means performs the power detection. Based on the power detected by the means, when a predetermined same type of recording material is continuously subjected to the heat treatment, the power detection means detects the power when the n-th recording material is subjected to the heat treatment. compares the power P _n, the magnitude of the power P _n-1 which is detected by said power detecting means when n-1 th recording material is heat treated, P _n -P _n-1 is given When the value is larger than the value ΔP, the power supplied from the power supply to the heating element is cut off or reduced. Deterioration and breakage can be prevented.

According to the second invention of the present application,
The power detection means detects the power supplied from the power supply to the heating element, the control means, based on the power detected by the power detection means when the first half in the conveying direction of the recording material is being heated, When a predetermined same type of recording material is continuously subjected to the heat treatment, the electric power P _n detected by the electric power detection means when the n-th recording material is being subjected to the heat treatment.
And the power P _n-1 detected by the power detecting means when the (n−1) th recording material is being subjected to the heat treatment, and P _n −P _n−1 is larger than a predetermined value ΔP. If large
Since the power supplied from the power supply to the heating element is cut off or reduced, it is possible to prevent the heating device from being deteriorated or damaged due to double feeding during continuous heating processing of recording material such as small-size paper. Can be.

Further, according to the third aspect of the present invention, the power detection means detects the power supplied from the power supply to the heating element, and the control means determines the power based on the power detected by the power detection means. If the width of the recording material subjected to the continuous heating process in the direction perpendicular to the conveying direction is smaller than a predetermined width, P
_n -P _n-1> blocking or reducing the power supplied to the heating body from the power supply when the [Delta] P, the width at right angles the direction of conveyance direction of the recording material to be subjected to continuous heat treatment is wider than the predetermined width since so to increase the power supplied from the power source when P _n -P _n-1> ΔP to the heating body, heating by double feeding or the like in the continuous heat treatment of the recording material such as small size sheets It is possible to prevent the apparatus from being deteriorated or damaged, and further to prevent an image defect on a succeeding recording material after a double feed during a continuous fixing process of a recording material such as large-size paper.

According to the fourth invention of the present application,
Temperature detecting means detects the temperature of the heating element, power detecting means detects electric power supplied from the power supply to the heating element, and control means detects a predetermined same type of electric power based on the electric power detected by the electric power detecting means. When the n-th recording material is subjected to the heat treatment, the power P _n detected by the power detection means when the n-th recording material is subjected to the heat treatment, and the (n−1) -th recording comparing the magnitude of the power P _n-1 which is detected by said power detecting means when the wood is heat-treated, P _n
When -P _n-1 is larger than a predetermined value ΔP, the power supplied from the power supply to the heating element is cut off or reduced, and the power supply is set so that the temperature detected by the temperature detection means becomes a predetermined target temperature. From the heater to the heating element, and ΔP is set according to the target temperature, so that the heating device is prevented from being deteriorated or damaged due to double feed during continuous heating of recording materials such as small size paper. can do.

Further, according to the fifth aspect of the present invention, the electric power detecting means detects the electric power supplied from the power supply to the heating element, and the control means based on the electric power detected by the electric power detecting means. When a predetermined same type of recording material is continuously subjected to the heat treatment, the electric power P _n detected by the electric power detection means when the n- _th recording material is subjected to the heat treatment, and n−1 The magnitude of the power P _n-1 detected by the power detection means when the recording material of the sheet is being heated is compared, and when P _n -P _n-1 is larger than a predetermined value ΔP, Since the power supplied from the power supply to the heating element is cut off or reduced, it is possible to prevent the heating device from being deteriorated or damaged due to double feeding during continuous heating processing of recording material such as small-size paper. it can.

According to the sixth invention of the present application,
Power detection means detects power supplied from the power supply to the heating element.
The control means is detected by the power detection means.
The same type of recording material is continuously heated based on the
When the n-th recording material is heated,
The power P detected by the power detection means when _n
And when the (n-1) th recording material is being heated,
The power P detected by the power detection means_n-1Big and small
And P_n−P_n-1Is larger than the predetermined value ΔP,
Cut off the power supplied from the power supply to the heating element
Is designed to reduce the
Heating equipment by double feed etc. during continuous heating processing of recording materials
Deterioration and breakage can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view illustrating a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a schematic configuration of a heating device provided in the image forming apparatus of FIG.

FIG. 3 is a diagram showing a schematic configuration of a heating body provided in the heating device of FIG. 2;

FIG. 4 is a flowchart illustrating control of heating driving of a heating body by a control unit according to the first embodiment of the present invention.

FIG. 5 is a schematic diagram showing a time change of electric power supplied to the heating element according to the first embodiment of the present invention.

FIG. 6 is a flowchart illustrating control of heating driving of a heating body by a control unit according to a second embodiment of the present invention.

[Explanation of symbols]

 2 Film (Film Member) 3 Heater (Heating Body) 4 Pressure Roller (Pressure Roller) 5 Temperature Sensor (Temperature Detecting Means) 26 Power Supply 107 Heating Device a Transporting Direction (Conveying Direction of Recording Material) N Fixing Nip (Nip) Area) P Recording material

Claims (6)

[Claims] An electric power from a power source is supplied to a recording material carrying an image.
A heating element to be heated by receiving the supply of
Power from the power supply to the heating element to maintain the target temperature
A heating device comprising a power control means for controlling the supply.
Power detector to detect the power supplied from the power supply to the heater.
The control means is provided with a detection means.
Based on the known power, the same type of recording material
When the recording material is subjected to the heat treatment, the n-th recording material is subjected to the heat treatment.
The power detected by the power detection means
Force P_nAnd that the (n-1) th recording material has been heat-treated.
Power P detected by the power detection means_n-1When
Compare the size of P_n−P _n-1Is larger than the predetermined value ΔP
In this case, cut off the power supplied from the power supply to the heating element
Or set to decrease
Heating device. 2. The power control unit determines whether P _n −P _n− 1> ΔP based on the power detected by the power detection unit when the first half of the recording material in the conveying direction is being subjected to the heating process. The heating device according to claim 1, wherein a determination is made as to whether or not the heating device is in the heating device. 3. The power control means, when the width of the recording material to be subjected to the continuous heating process in the direction perpendicular to the conveying direction is smaller than a predetermined width, heating from a power supply when P _n −P _n-1 > ΔP. The power supplied to the body is cut off or reduced, and when the width in the direction perpendicular to the transport direction of the recording material subjected to the continuous heating process is wider than a predetermined width, the power is supplied when P _n −P _n-1 > ΔP. The heating device according to claim 1 or 2, wherein the heating device is set so as to increase electric power supplied to the heating element from the heating device. 4. A temperature control means for detecting a temperature of the heating element, wherein the power control means controls electric power from a power supply to the heating element so that the temperature detected by the temperature detection means becomes a predetermined target temperature. The heating device according to any one of claims 1 to 3, wherein ΔP is set corresponding to the target temperature. 5. A recording device for carrying an image, comprising: a film-shaped film member slidable with respect to a heating member; and a pressing member forming a nip area pressed by the heating member via the film member. The heat treatment is performed while the material is passed between the film member and the pressing member in the nip region and pressed.
The heating device according to claim 1. 6. An image forming apparatus for recording an image formed by a series of image forming processes on a recording material, comprising: the heating device according to claim 1. Description: Image forming apparatus.