JP6897272B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus having a fixing equipment for fixing an image on a recording medium.

In recent years, there has been an increasing market demand for energy saving and high speed for image forming devices such as printers, copiers, and facsimiles.
In the image forming apparatus, the unfixed toner image is transferred to the recording material sheet, printing paper, photosensitive paper, electrostatic recording paper, etc. by the image transfer method or the direct method by the image forming process such as electrophotographic recording, electrostatic recording, and magnetic recording. It is formed on the recording material. As a fixing device for fixing an unfixed toner image, a contact heating type fixing device such as a thermal roller method, a film heating method, and an electromagnetic induction heating method is widely adopted.

In image forming devices such as copiers, printers, and facsimiles, toner images (unfixed toner images) formed by image forming processes such as electrophotographic recording, electrostatic recording, and magnetic recording are recorded directly or via an intermediate transfer body. The toner image is transferred onto a recording medium such as a material sheet, printing paper, photosensitive paper, or electrostatic recording paper, and the recording medium carrying the toner image is passed through a fixing device to fix the toner image on the recording medium.

As a fixing device for fixing an unfixed toner image, a heat fixing device for fixing a toner image on a recording material (recording medium) by heat and pressure is widely adopted. In a typical such fixing device, a fixing member and a pressure member, for example, a fixing roller and a pressure roller are brought into contact with each other at a predetermined pressure, and a toner image is displayed at the contacted portion. By transporting the paper to be held, the unfixed toner image is fixed to the paper by the fixing and pressure rollers. A method in which a heater member such as a halogen lamp is housed in the fixing roller used in such a fixing device and the fixing roller is uniformly heated by the heater member is generally used.

However, in these image forming apparatus, the size of the paper conveyed for image forming is not constant. For example, paper of various sizes, such as A3 size (297 × 420 mm) to official postcard size (100 × 148 mm), is conveyed and fixed by a fixing device. At this time, in order to sufficiently fix the paper of a large size (for example, A3 size), a heater member is formed corresponding to the large size paper and sufficiently extended in the axial direction of the fixing roller (a state in which the heater member is formed. For example, it is common to arrange the heater member so as to sufficiently cover the short side 297 mm of A3 size).

However, as described above, when the heater member is formed according to the large size paper, if the small size paper such as postcard size or B5 size is continuously conveyed to the fixing device, the small size paper passes through. There is a problem that the temperature of only one part drops and the temperature of other parts rises above the specified value. Therefore, a heater member having a long heating action portion and a heater member having a short heating action portion are provided in the axial direction of the fixing roller according to the large size and small size paper to be conveyed, and the paper is conveyed. A method of arranging each heater member so that the heating portion is located at the position where the heating portion is formed is already known.

Further, in the fixing device that uses a plurality of heating elements (heater members) properly according to the paper size as described above, a temperature detecting means is provided at a position corresponding to each heat generating portion (paper passing area). For example, a thermistor is adopted as the temperature detecting means, and temperature control for the heater is executed from the surface temperature of the fixing roller measured by this sensor.

However, there is a problem that the plurality of heating elements heat the non-passing portion of the small-sized paper even if the heating element heats the small-sized paper portion. Therefore, when the central heater is turned on to heat the central portion, the end portion is also heated, and conversely, when the end heater is heated to heat the end portion, there is a problem that the central portion is also heated.

On the other hand, Patent Document 1 (Japanese Unexamined Patent Publication No. 2015-7755) has a plurality of heaters for heating the axially central portion and the end portion of the fixing roller, and is provided with a mobile reflective member. A fixing device capable of heating only a specific part at the time of printing a small size is disclosed.

In the fixing device of Patent Document 1, the heater emits light at the portion covered with the reflecting member, but it is not used for heating the fixing member, and the problem of preventing interference between the heaters can be solved, but the reflection By covering with a plate, there is energy that is not used for heating the fixing member that emits light from the heater, so there is a problem that wasteful energy is consumed.

Therefore, the present invention can heat a desired region and reduce energy consumption in an image forming apparatus having a fixing device using a plurality of heat sources having different heat distributions (light distributions). and to provide the images forming apparatus that can the be temperature controlled.

In order to solve this problem, the present invention includes a rotatable fixing member and a pressure member that is pressed against the fixing member to form a nip portion, and a recording material that carries an unfixed toner image on the nip portion. In an image forming apparatus having a fixing device for fixing an unfixed toner image to a recording material, a first heat source for heating an axial central portion of the fixing member and an axial end portion of the fixing member are heated. A second heat source, a first temperature detecting means for detecting the temperature of the axially central portion of the fixing member, and a second temperature detecting means for detecting the temperature of the axially end portion of the fixing member. It has heat source-to-heat source interference removal control for removing interference between the heat sources, and the heat source-to-heat source interference removal control is based on the axial central target temperature at the time of heating the fixing member and the first temperature detecting means. The heat generation rate of the first heat source and the heat generation rate of the second heat source are based on the deviation of the detected temperature, the target temperature at the axial end when the fixing member is heated, and the deviation of the detected temperature by the second temperature detecting means. The calorific value is calculated, and a value obtained by multiplying the calorific value of the second heat source by a predetermined coefficient is subtracted from the calculated calorific value of the first heat source, and the calorific value of the second heat source calculated is subtracted. From, the heat generation rate correction value of the first heat source and the heat generation rate correction value of the second heat source are calculated by subtracting the value obtained by multiplying the heat generation rate of the first heat source by a predetermined coefficient. The heat generation rate correction value of the first heat source and the heat generation rate correction value of the second heat source are the temperature rise gradient of the central portion in the axial direction = A11 × the heat generation rate of the first heat source + A12 × the heat generation of the second heat source. When the rate, the temperature rise gradient at the axial end = A21 × the heat generation rate of the first heat source + A22 × the heat generation rate of the second heat source, the heat generation rate correction value of the first heat source = (first) Heat source heat generation rate)-(heat generation rate of second heat source) x (A12 / A11), heat generation rate correction value of the second heat source = (heat generation rate of second heat source)-(heat generation of first heat source) Rate) × (A21 / A22) .

The lighting of the first heat source for heating the axial central portion of the fixing member and the second heat source for heating the axial end portion can be effectively used for heating the central portion and the end portion of the fixing member. Therefore, it is possible to efficiently heat a desired region and realize heat source control without wasting power.

It is a schematic block diagram of the image forming apparatus which concerns on embodiment of this invention. It is the schematic sectional drawing of the fixing device which concerns on 1st Embodiment. It is a figure which shows the arrangement of a plurality of heaters which a fixing device has. It is a schematic diagram which shows the heat distribution example of each heater. It is a graph which shows the temperature rise state of the fixing roller at the time of starting up an apparatus. It is a schematic diagram explaining the heater duty. It is a figure which shows the example of the temperature rise of the center and the end part in the fixing roller axial direction when a plurality of heaters in an embodiment are turned on independently (heat generation). It is a control block diagram which shows the characteristic structure of this invention. It is the schematic sectional drawing which shows the fixing apparatus of 2nd Embodiment.

The fixing device according to the present invention has a heating element (heater) that is a plurality of heat sources, and is characterized in that interference can be removed by providing an inter-heater interference removing device that removes interference between heaters at a heating site. It is supposed to be. The features of the present invention will be described in detail below.

In the present invention, the heater duty of the central heater and the end heater (defined as the heater lighting time ratio per unit time = heat generation rate) as the heating element for heating the fixing member, the temperature rising gradient at the center of the fixing member, and the end portion. By formulating the relationship between the temperature rise gradients and associating them with a 2 * 2 matrix,
(Central heating gradient) = (A11 A12) (Central heater duty)
(End temperature rise gradient) (A21 A22) (End heater duty) ... (Equation 1)
For the relationship
Central heater duty correction value = (Central heater duty)-(End heater duty) * Coefficient α
End heater duty correction value = (end heater duty)-(center heater duty) * coefficient β ... (Equation 2)
By setting, it is possible to set A12 = A21 = 0 in the equation (1), and the relationship as in the equation (3) can be obtained.
(Central heating gradient) = (A110) (Central heater duty)
(End temperature rise gradient) (0 A22) (End heater duty) ... (Equation 3)
In addition, since each mathematical formula is described in characters here, it is shown in a simulated manner, and an accurate mathematical formula is inserted as an image in the embodiment.

With such a setting, the relationship between the input duty of the central heater and the central ascending / descending gradient becomes a proportional relationship, and the relationship between the input duty of the end heater and the end temperature rising gradient can be made a proportional relationship.

As a result, when you want to heat the center of the fixing member, only the center heater is lit with a high heater duty, and when you want to heat the end of the fixing member, only the end heater is lit with a high heater duty. The lighting of the heater and the end heater can be effectively used for heating the central portion and the end portion of the fixing member. Therefore, it becomes possible to control the heater of the fixing device, which can heat a desired region and does not consume unnecessary electric power.

Hereinafter, the description of the embodiment will be continued with reference to the drawings.
FIG. 1 is a cross-sectional configuration diagram showing an example of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 shown in this figure is a tandem color printer in which image forming portions forming a plurality of color images are juxtaposed along the stretching direction of the belt. However, the present invention is not limited to this method, and it is also possible to target not only a printer but also a copier, a facsimile machine, and the like.

Four toner bottles 102Y, 102M, 102C, and 102K corresponding to each color (yellow, magenta, cyan, and black) are detachably installed (replaceable) in the bottle accommodating portion 101 above the image forming apparatus main body. There is.

An intermediate transfer unit 85 is arranged below the bottle accommodating portion 101.
Image-forming units 4Y, 4M, 4C, and 4K corresponding to each color (yellow, magenta, cyan, and black) are arranged side by side so as to face the intermediate transfer belt 78 of the intermediate transfer unit 85. Photoreceptor drums 5Y, 5M, 5C, and 5K are arranged in each image forming unit 4Y, 4M, 4C, and 4K, respectively.

Further, around each of the photoconductor drums 5Y, 5M, 5C, and 5K, a charging unit 75, a developing unit 76, a cleaning unit 77, a static elimination unit, and the like are arranged, respectively. Then, an image forming process (charging step, exposure step, developing step, transfer step, cleaning step) is performed on each photoconductor drum 5Y, 5M, 5C, 5K, and each photoconductor drum 5Y, 5M, 5C, Images of each color will be formed on 5K.

The photoconductor drums 5Y, 5M, 5C, and 5K are rotationally driven clockwise in FIG. 1 by a drive motor. Then, at the position of the charging portion 75, the surfaces of the photoconductor drums 5Y, 5M, 5C, and 5K are uniformly charged (charging step).

After that, the surfaces of the photoconductor drums 5Y, 5M, 5C, and 5K reach the irradiation position of the laser beam L emitted from the exposure unit 3, and an electrostatic latent image corresponding to each color is formed by exposure scanning at this position. (Exposure process).

After that, the surfaces of the photoconductor drums 5Y, 5M, 5C, and 5K reach a position facing the developing device 76, and the electrostatic latent image is developed at this position to form a toner image of each color (development step). ). After that, the surfaces of the photoconductor drums 5Y, 5M, 5C, and 5K reach the positions facing the intermediate transfer belt 78 and the first transfer bias rollers 79Y, 79M, 79C, and 79K, and at this position, the photoconductor drums 5Y and 5M The toner images on 5, 5C and 5K are transferred onto the intermediate transfer belt 78 (primary transfer step). At this time, a small amount of untransferred toner remains on the photoconductor drums 5Y, 5M, 5C, and 5K.

After that, the surface of the photoconductor drum 5Y, 5M, 5C, and 5K reaches a position facing the cleaning unit 77, and the untransferred toner remaining on the photoconductor drum 5Y, 5M, 5C, and 5K at this position reaches the cleaning unit. It is mechanically recovered by 77 cleaning blades (cleaning step).

Finally, the surface of the photoconductor drums 5Y, 5M, 5C, and 5K reaches a position facing the static elimination portion, and the residual potential on the photoconductor drums 5Y, 5M, 5C, and 5K is removed at this position. In this way, a series of image forming processes performed on the photoconductor drums 5Y, 5M, 5C, and 5K are completed. Then, the toner images of each color formed on each photoconductor drum through the developing process are superimposed and transferred on the intermediate transfer belt 78. In this way, a color image is formed on the intermediate transfer belt 78.

Here, the intermediate transfer unit 85 includes an intermediate transfer belt 78, four primary transfer bias rollers 79Y, 79M, 79C, 79K, a secondary transfer backup roller 82, a cleaning backup roller 83, a tension roller 84, and an intermediate transfer cleaning unit 80. , Etc. The intermediate transfer belt 78 is stretched and supported by three rollers 82 to 84, and is endlessly moved in the direction of the arrow in the figure (counterclockwise in the figure) by the rotational drive of one roller 82.

Each of the four primary transfer bias rollers 79Y, 79M, 79C, and 79K forms a primary transfer nip by sandwiching the intermediate transfer belt 78 between the photoconductor drums 5Y, 5M, 5C, and 5K, respectively. Then, a transfer bias opposite to the polarity of the toner is applied to the primary transfer bias rollers 79Y, 79M, 79C, 79K. Then, the intermediate transfer belt 78 travels in the direction of the arrow and sequentially passes through the primary transfer nips of the primary transfer bias rollers 79Y, 79M, 79C, and 79K, respectively. In this way, the toner images of each color on the photoconductor drums 5Y, 5M, 5C, and 5K are superimposed on the intermediate transfer belt 78 and first-order transferred.

After that, the intermediate transfer belt 78 on which the toner images of each color are superimposed and transferred reaches a position facing the secondary transfer roller 89. At this position, the secondary transfer backup roller 82 sandwiches the intermediate transfer belt 78 with the secondary transfer roller 89 to form the secondary transfer nip. Then, the four-color toner images formed on the intermediate transfer belt 78 are transferred onto the recording medium P conveyed to the position of the secondary transfer nip. At this time, untransferred toner that has not been transferred to the recording medium P remains on the intermediate transfer belt 78. After that, the intermediate transfer belt 78 reaches the position of the intermediate transfer cleaning unit 80. Then, at this position, the untransferred toner on the intermediate transfer belt 78 is collected.

In this way, a series of transfer processes performed on the intermediate transfer belt 78 is completed.
Here, the recording medium P conveyed to the position of the secondary transfer nip is conveyed from the paper feeding unit 12 arranged below the apparatus main body 1 via the paper feeding roller 97, the resist roller pair 98, and the like. It is a paper.

Specifically, a plurality of recording media P such as transfer paper are stacked and stored in the paper feed unit 12. Then, when the paper feed roller 97 is rotationally driven in the counterclockwise direction in FIG. 3, the top recording medium P is fed between the resist rollers and the rollers 98. The recording medium P conveyed to the resist roller pair 98 is temporarily stopped at the position of the roller nip of the resist roller pair 98 where the rotational drive is stopped. Then, the resist roller pair 98 is rotationally driven in time with the color image on the intermediate transfer belt 78, and the recording medium P is conveyed toward the secondary transfer nip. In this way, the desired color image is transferred onto the recording medium P.

After that, the recording medium P on which the color image is transferred at the position of the secondary transfer nip is conveyed to the position of the fixing device 20. Then, at this position, the color image transferred to the surface is fixed on the recording medium P by the heat and pressure of the fixing member 21 and the pressure member 31. After that, the recording medium P is discharged to the outside of the apparatus via the paper ejection roller vs. 99 rollers. The recording medium P discharged to the outside of the device by the paper ejection roller pair 99 is sequentially stacked on the stack unit 100 as an output image. In this way, a series of image forming processes in the image forming apparatus is completed.

FIG. 2 is a cross-sectional view showing a configuration example of the fixing device. The present invention is not limited to this method, and an appropriate configuration such as a belt fixing device can be adopted.
The fixing device 20 shown in FIG. 2 includes a fixing member 21 and a pressure member 31 that is pressure-contacted with the fixing member 21. In this example, the pressure roller 31 is in pressure contact with the fixing roller 21 having a heat source 41 inside.

The fixing roller 21 is composed of a base material 21b and a surface layer 21a, the base material 21b is a metal such as iron or aluminum, and the surface layer 21a is provided with a release layer such as PFA on a thin elastic member such as silicone rubber. .. The surface layer 21a of the fixing roller 21 may have a structure in which a release layer such as PFA is directly coated on the base material 21b. In order to save energy, the base material 21b of the fixing roller 21 is made of a thin material having a wall thickness of about 0.3 to 0.7 mm.

The pressure roller 31 of the pressure member is also composed of a base material 31b and an elastic layer 31a. The base material 31b is made of a metal such as iron, and the elastic layer 31a is made of silicone rubber or sponge, and is fixed to the surface layer. Like the rollers, a release layer such as PFA is provided.

A nip portion N is formed between the fixing roller 21 and the pressure roller 31, and the toner adhering to the transfer paper is removed by passing the transfer paper on which the toner image is formed through the nip portion N. It is melted by heat and adhered to the transfer paper by pressurization.

FIG. 3 is a diagram showing an arrangement of a plurality of heaters included in the fixing device.
In the fixing device 20 of this example, two halogen heaters as heat sources 41 are arranged inside the fixing roller 21. One is a heater 41a (first heater) that mainly heats the central portion of the paper passing region, and the other is a heater 41b (second heater) that mainly heats the end portion of the paper passing region.

An example of heat distribution of each heater is shown in FIG. The first heater 41a has a heat distribution peak at the center of the maximum paper width. The width of this peak is adjusted so that the winding of the filament corresponds to, for example, the width of A5 size paper. The second heater 41b is set so that both ends of the second heater 41b have peaks of heat distribution with respect to the maximum paper width. The central portion of the second heater 41b adjusts the winding of the filament so that a power of about 20% of the rating is applied.

FIG. 4 is a schematic diagram showing the heat distribution of the halogen heater. Since the halogen heater heater as the heat source 41 has such a configuration, the first heater 41a heats the central portion of the paper (in this example, the central portion in the width direction of the paper conveyed based on the center), and the second heater The 41b has a role of heating the edge of the paper, but since the first heater 41a also has a filament winding at the end (the filament winding portion is shown by cross-hatching in the figure), the first heater 41a is heated. As a result, a temperature rise is also observed at the end portion, and by heating the second heater 41b, the center is also heated by the filament winding at the center portion of the second heater.

The reason why multiple heaters are provided is that when printing on paper with a small paper width (small size paper), only the first heater 41a (also called the center heater) is used, and the paper with a wide paper width (large size paper) is used. At the time of printing, the second heater 41b (also referred to as the edge heater) is used in combination with the first heater 41a (center heater) to impart a heat amount capable of fixing the toner to the paper over the entire width of the paper.

FIG. 5 is a graph showing a temperature rise state of the fixing roller at the time of starting the device (at the start of use at the beginning of the morning). The temperature rise of the fixing roller may differ between the central portion and the end portion. In the graph of FIG. 5, the temperature rise gradient at the central portion in the axial direction of the fixing roller 21 is shown as “center temperature rise gradient: dT1 / dt”, and the temperature rise gradient at the axial end portion is shown as “end temperature rise gradient: dT2 /”. It is shown as "dt".

FIG. 6 is a schematic diagram illustrating a heater duty representing the lighting rate of the heater. The ratio of the heater ON time (heater ON time / control cycle) to the control cycle for controlling the heater is expressed as a percentage, which is called the heater duty.

In the fixing device of the embodiment, when a plurality of heaters having the heat distribution distribution shown in FIG. 4 are independently lit (heat generated), the temperature rises at the center and the end portion in the longitudinal direction of the fixing member (the axial direction of the fixing roller). An example is shown in FIG.

FIG. 7A shows the lighting duty of the first heater 41a (center heater) and the second heater 41b (end heater), and the temperature rise gradients at the center and the end in the axial direction under each condition. Further, FIG. 7B shows the rate of contribution to the temperature rise gradient of the first heater 41a (center heater) and the second heater 41b (end heater).

Test condition A shows the central heating gradient and the edge heating gradient when the central heater duty is 100% and the end heater duty is 100%. In test condition B, only the central heater is lit with a heater duty of 100%. The end heater shows the central temperature rise gradient and the end temperature rise gradient when the duty is 0% (not lit).

Test condition C shows the central temperature rise gradient and the end temperature rise gradient when only the end heater is turned on with a heater duty of 100% and the center heater is not turned on.
The sum of the temperature rise gradients of the test condition B and the test condition C is the temperature rise gradient of the test condition A, and by turning on both the central heater and the end heater, the temperature rise at the time of startup is accelerated. .. The contribution of the central heater and the end heater to the temperature rise gradient of the central portion and the end portion is as shown in FIG. 7 (b). In this example, the central heater contributes about 79% to the central temperature rise. However, it can be seen that the end heater contributes about 50% to the temperature rise at the end.

This also leads to the fact that the conventional fixing device consumes a large amount of energy because it cannot be controlled independently when only the center is desired to be heated.
The following mathematical formula (Equation 1) formulates the result of FIG. 7.

This is shown in the control block diagram in FIG.
Based on the difference between the target temperature at the center and the end in the axial direction and the detected temperature at the center and the end, the heater duty required by the temperature controller (PID control, etc.) is calculated for each of the center and the end.

Conventionally, the power supply circuit is driven with the heater duty calculated as described above to light the heater, and the temperature rise gradient at the center and the end is obtained, and the center and end detection temperatures are obtained as the integrated amount. Has been done.

On the other hand, in the present invention, the inter-heater interference removing device 55 is provided after the temperature controller 51.
Here, the inter-heater interference removing device is a correction duty d1r obtained by subtracting a value obtained by multiplying the duty d1 of the central heater 41a by the duty d2 of the end heater 41b and a coefficient α into the power supply circuit 52a. This is a device that applies a modified duty d2r obtained by subtracting a value obtained by multiplying the duty d1 of the central heater 41a by a coefficient β to the duty d2 of the end heater 41b into the power supply circuit 52b.

In the embodiment, the axial center and end temperatures of the fixing roller 21 are detected by the temperature sensors 45 and 46. Further, the temperature rise gradients at the center and the end of the fixing roller 21 are integrated by the integrators 53a and 53b to obtain the detected temperatures at the center and the end, respectively. Moreover, this detection temperature is fed back.

The configuration of the inter-heater interference removing device is shown in the following mathematical formula (Equation 2).

The following equation (Equation 3) is formulated by putting the equation of Equation 2 into the term of the central heater duty of Equation 1.

From this, the relationship between the temperature rise gradient at the center and the end and the duties d1 and d2 is expressed by a coefficient including α and β.
Therefore, in order to set the interference term to 0, the interference can be eliminated by selecting the values of α and β in the following equation (Equation 4), and the heater duty without interference as in the following equation (Equation 5). The relationship of the temperature rise gradient can be obtained.

The configuration of the inter-heater interference removing device in the embodiment is as shown in FIG.
By the way, in the example of FIG. 7,
A11 = 0.172, A12 = 0.057, A21 = 0.044, A22 = 0.058
α = 0.33, β = 0.759.

In the image forming apparatus of the present embodiment, by applying the interference removal between heaters as described above at the time of printing, it is possible to fix the width of the paper without consuming unnecessary power. , in particular, be enabled during printing is effective in reducing consumption energy. That is, in a fixing device using a plurality of heat sources having different heat distributions (light distributions), a desired region can be heated and energy consumption can be reduced to control the temperature.

FIG. 9 is a cross-sectional configuration diagram showing an embodiment of a belt fixing device using a fixing belt as a fixing member.
The fixing device 120 has a fixing belt 121 as a rotatable fixing member and a pressure roller 131 as a rotatable pressure member arranged opposite to the fixing belt 121, and halogen heaters 141a and 141b as a plurality of heat sources. The fixing belt 121 is directly heated by radiant heat from the inner peripheral side. At this time, in the loop of the fixing belt 121, there is a nip forming member 124 that forms a nip portion between the fixing belt 121 and the pressurizing roller 131, and the nip forming member 124 is formed directly with the inner surface of the fixing belt or via the sliding sheet 127. It is designed to slide indirectly. The recording medium P that has passed through the secondary transfer roller is conveyed in the direction of the arrow in the drawing, and the toner image on the recording medium P is fixed at the nip portion N by heating and pressurizing.

In FIG. 9, the shape of the nip portion is flat, but it may be concave or other shape. In the case of the concave nip portion, the discharge direction of the tip of the recording material is closer to the pressure roller, and the separability is improved, so that the occurrence of jam is suppressed.

The fixing belt 121 is made of a metal belt such as nickel or SUS, or an endless belt or film using a resin material such as polyimide. The surface layer of the belt has a release layer such as a PFA or PTFE layer, and has a release property so that toner does not adhere to the surface layer. An elastic layer formed of a layer of silicone rubber or the like may be provided between the base material of the belt and the PFA or PTFE layer. If there is no silicone rubber layer, the heat capacity will be small and the fixability will be improved, but when the unfixed image is crushed and fixed, the minute irregularities on the belt surface will be transferred to the image and the solid part of the image will have a yuzu skin shape. There may be a problem that uneven gloss (Yuzu skin image) remains. To improve this, it is necessary to provide a silicone rubber layer of 100 [μm] or more. Due to the deformation of the silicone rubber layer, minute irregularities are absorbed and the yuzu skin image is improved.

A stay 125 as a support member for supporting the nip forming member 124 and the nip portion N is provided in the loop of the fixing belt 121 to prevent the nip forming member 124 receiving pressure from the pressure roller 131 from bending and in the axial direction. To obtain a uniform nip width. The stay 125 is held and fixed to a flange as a holding member at both ends and is positioned. Further, reflective members 128a and 128b are provided between the halogen heaters 141a and 141b and the stay 125 to suppress wasteful energy consumption due to the stay 125 being heated by radiant heat from the halogen heaters 141a and 141b. Here, instead of providing the reflective member 128, the same effect can be obtained by performing heat insulation or mirror surface treatment on the surface of the stay 125.

The pressure roller 131 has an elastic rubber layer on the core metal, and a release layer (PFA or PTFE layer) is provided on the surface in order to obtain mold releasability. The pressurizing roller 131 rotates by transmitting a driving force from a drive source such as a motor provided in the image forming apparatus via a gear. Further, the pressure roller 131 is pressed against the fixing belt 121 side by a spring or the like, and the elastic rubber layer is crushed and deformed to have a predetermined nip width. The pressurizing roller 131 may be a hollow roller, and the pressurizing roller 131 may have a heating source such as a halogen heater. The elastic rubber layer may be solid rubber, but if there is no heater inside the pressure roller 131, sponge rubber may be used. Sponge rubber is more preferable because it has higher heat insulating properties and is less likely to take away heat from the fixing belt.

The fixing belt 121 is rotated by the pressure roller 131. In the case of FIG. 9, the pressure roller 131 is rotated by the drive source, and the fixing belt 121 is rotated by transmitting the driving force to the belt at the nip portion N. The fixing belt 121 is sandwiched between the nip portions N and rotates, and is guided by the flanges at both ends except the nip portion to travel.

In this fixing device, the halogen heater 141a is the first heater (central heater), and the halogen heater 141b is the second heater (end heater). The first heater (central heater) and the second heater (end heater) 141b have the same heat distribution as the first heater (central heater) 41a and the second heater (end heater) 41b in the fixing device 20 of FIG. The filament winding of each heater is set so as to be.

Further, a temperature sensor 145 for detecting the temperature at the central portion of the fixing belt 121 in the axial direction and a temperature sensor 146 for detecting the temperature at the end portion in the axial direction of the fixing belt 121 are provided. In this example, the temperature sensor 145 is in contact with or close to the fixing belt 121 so as to face the first heater (central heater) 141a and the temperature sensor 146 so as to face the second heater (end heater) 141b. Is arranged. In the case of this example, the temperature sensor 145 that detects the temperature at the central portion uses a thermopile, and the temperature sensor 146 that detects the temperature at the end portion uses a contact thermistor. Since the temperature rise of the fixing device of the belt configuration is faster than that of the roller configuration, it is desirable to configure the thermopile at the center and the contact thermistor at the ends.

Then, by providing the inter-heater interference removing device 55 as in the fixing device 20 of FIG. 2 and applying the inter-heater interference removing as described with reference to FIG. 8 or the like at the time of printing, the same as the fixing device 20 of FIG. The effect can be obtained. That is, in a fixing device using a plurality of heat sources having different heat distributions (light distributions), a desired region can be heated, and energy consumption can be reduced to control the temperature.

Although the present invention has been described above with reference to the illustrated examples, the present invention is not limited thereto. For example, the heat source of the fixing device is not limited to the halogen heater, and an appropriate heat source can be adopted as long as the present invention can be applied. The present invention is also applicable to a configuration including three or more heat sources having different heat distribution distributions.

As the image forming apparatus, any configuration can be adopted as long as the present invention can be applied. The image forming apparatus is not limited to a printer, and may be a copying machine, a facsimile, or a multifunction device having a plurality of functions.

1 Image forming device 4 Image forming part 5 Photoreceptor drum 20 Fixing device 21 Fixing roller (fixing member)
31 Pressurizing roller (pressurizing member)
41 Halogen heater (heat source)
41a First heater (central heater)
41b Second heater (end heater)
45,46 Temperature sensor (temperature detection means)
51 Temperature controller 52 Power supply circuit 53 Integrator 55 Inter-heater interference removal device 120 Fixing device 121 Fixing belt (fixing member)
124 Nip forming member 131 Pressurizing roller (pressurizing member)
141 Halogen heater (heat source)
141a First heater (central heater)
141b Second heater (end heater)
145,146 Temperature sensor (Temperature detection means)
P paper (recording medium, recording material)
N fixing nip part

JP 2015-7755

Claims (4)

A rotatable fixing member and a pressure member that is pressed against the fixing member to form a nip portion are provided, and a recording material that carries an unfixed toner image is passed through the nip portion to record an unfixed toner image. In an image forming apparatus having a fixing device for fixing to
A first heat source for heating the axially central portion of the fixing member,
A second heat source that heats the axial end of the fixing member,
A first temperature detecting means for detecting the temperature of the axially central portion of the fixing member,
A second temperature detecting means for detecting the temperature of the axial end portion of the fixing member, and
Have,
It has a heat source-to-heat source interference removal control that removes interference between each heat source.
The heat source interference elimination control is
The deviation between the axial center target temperature when the fixing member is heated and the temperature detected by the first temperature detecting means, the axial end target temperature when the fixing member is heated, and the temperature detected by the second temperature detecting means. The calorific value of the first heat source and the calorific value of the second heat source are calculated based on the deviation of
From the calculated heat generation rate of the first heat source, a value obtained by multiplying the heat generation rate of the second heat source by a predetermined coefficient is subtracted, and from the calculated heat generation rate of the second heat source, the first By performing the process of subtracting the value obtained by multiplying the heat generation rate of the heat source by a predetermined coefficient, the heat generation rate correction value of the first heat source and the heat generation rate correction value of the second heat source are calculated.
The calorific value correction value of the first heat source and the calorific value correction value of the second heat source are
Temperature rise gradient in the central part in the axial direction = A11 × heat generation rate of the first heat source + A12 × heat generation rate of the second heat source
Temperature rise gradient at the axial end = A21 × heat generation rate of the first heat source + A22 × heat generation rate of the second heat source
When
The heat generation rate correction value of the first heat source = (heat generation rate of the first heat source)-(heat generation rate of the second heat source) × (A12 / A11)
The heat generation rate correction value of the second heat source = (heat generation rate of the second heat source)-(heat generation rate of the first heat source) × (A21 / A22)
An image forming apparatus characterized in that. The image forming apparatus according to claim 1 , wherein the heat source interference removal control is executed during a fixing operation. The image forming apparatus according to claim 1 or 2 , wherein the heat source is a halogen heater. Any of claims 1 to 3 , wherein the fixing member is a fixing belt, the first temperature detecting means is a thermopile, and the second temperature detecting means is a thermistor arranged in contact with the fixing member. The image forming apparatus according to item 1.

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