JP6782374B2 - Fixing device, image forming device and fixing temperature control program of fixing device - Google Patents

Description

The present embodiment relates to a fixing device , an image forming device, and a fixing temperature control program of the fixing device.

As a heat source of the fixing device mounted on the image forming apparatus, a lamp that emits infrared rays typified by a halogen lamp or a method of heating with Joule heat by electromagnetic induction has been put into practical use.

Generally, the fixing device is composed of a pair of a heating roller (or a fixing belt spanned by a plurality of rollers) and a press roller, but in order to maximize the thermal efficiency of the fixing device, the heat capacity of the component is reduced as much as possible. It is required to concentrate the heating area. From this point of view, in the above-mentioned heating method, since the heating width is wide, it is difficult to intensively apply the heat energy dispersed over a wide range only to the nip portion, and it is difficult to optimize the thermal efficiency.

Further, in the fixing device for electrophotographic, if heat generation unevenness occurs in the direction perpendicular to the paper transport direction, the fixing quality is affected. In particular, in the case of color printing, there is a possibility that differences in color development and gloss may occur.

Furthermore, in a fixing device with an extremely reduced heat capacity, the temperature of the part through which the paper does not pass rises extremely, which may cause problems such as warpage of the heater, deterioration of the belt, and speed unevenness due to expansion of the transport roller. It was. Further, it is not preferable to heat the portion through which the paper does not pass from the viewpoint of energy saving. Intensive heating of only the part through which the paper passes is an important technical issue from the viewpoint of environmental friendliness.

Japanese Unexamined Patent Publication No. 2000-243537

In view of the above problems of the prior art, the present invention provides a fixing device and a fixing temperature control program for the fixing device, which enables intensive and stable heating of the paper-passing area, and can achieve improvement of fixing quality and energy saving. With the goal.

The fixing device according to the present embodiment includes a heating means, a pressurizing means, and a heating control means. Heating means includes a rotating member of an endless shape, it is disposed in the straight direction orthogonal to the conveying direction of the predetermined is divided into lengths medium on which the toner image has been formed, while inclined at a predetermined angle with respect to the conveying direction, a plurality of heat-generating member in contact with the inner surface of the rotary member, anda switching unit for switching individual energization of a plurality of heat generating members, two or more of any portion also multiple heat-generating member of media bodies by passing the heating member, heating the medium body. Force means, to a plurality of heat generating members of the heating means, through a rotating member to form a nip medium passes by pressure contact, to convey the medium body to conveyance direction to the heating means together with. The heating control means selects a heat-generating member from among the heat-generating members corresponding to the positions through which the medium passes among the plurality of heat-generating members via the switching portion, and energizes the selected heat-generating member with the first power. Then, the remaining non-selective heat generating member is energized with a second power smaller than the first power. Heating control means, any of the locations of the medium so as to pass the selected heating member, characterized that you select the selected heating unit.

The figure which shows the structural example of the image forming apparatus which mounts the fixing apparatus which concerns on one Embodiment. FIG. 6 is an enlarged configuration diagram showing a part of an image forming portion in one embodiment. The block diagram which shows the structural example of the control system of the MFP in one Embodiment. The figure which shows the structural example of the fixing device which concerns on one Embodiment. The layout of the heat generating member group in one Embodiment. The figure which shows the heat generating member group and its drive circuit in one Embodiment. The figure which shows the connection state of the heat generating member group and its drive circuit in one Embodiment. The flowchart which shows the specific example of the control operation of the MFP in one Embodiment. The figure which shows the connection state of the heat generating member group and its drive circuit in one Embodiment. The figure which shows the state that the paper in one Embodiment passes through a group of heat generating members.

FIG. 1 is a diagram showing a configuration example of an image forming apparatus on which the fixing apparatus according to the present embodiment is mounted. In FIG. 1, the image forming apparatus 10 is, for example, an MFP (Multi-Function Peripherals) which is a multifunction device, a printer, a copying machine, or the like. In the following description, the MFP will be described as an example.

A transparent glass platen 12 is provided above the main body 11 of the MFP 10, and an automatic document transport unit (ADF) 13 is provided on the platen 12 so as to be openable and closable. An operation panel 14 is provided on the upper part of the main body 11. The operation panel 14 has various keys and a touch panel type display unit.

A scanner unit 15 which is a reading device is provided below the ADF 13 in the main body 11. The scanner unit 15 reads a document sent by the ADF 13 or a document placed on a platen to generate image data, and includes a close contact type image sensor 16 (hereinafter, simply referred to as an image sensor). The image sensor 16 is arranged in the main scanning direction (depth direction in FIG. 1).

When the image sensor 16 reads the image of the original placed on the platen 12, the image sensor 16 reads the original image line by line while moving along the platen 12. This is executed over the entire document size to read one page of the document. Further, when reading the image of the original document sent by the ADF 13, the image sensor 16 is in a fixed position (position shown in the drawing).

Further, a printer unit 17 is provided in the central portion of the main body 11, and a plurality of paper feed cassettes 18 for accommodating various sizes of paper P are provided in the lower portion of the main body 11. The printer unit 17 has a photoconductor drum and a laser exposure device (scanning head) 19 including an LED as an exposure device, and scans the photoconductor with light rays from the laser exposure device 19 to generate an image.

The printer unit 17 processes the image data read by the scanner unit 15 and the image data created by a personal computer or the like to form an image on paper. The printer unit 17 is, for example, a tandem color laser printer, and includes image forming units 20Y, 20M, 20C, and 20K of each color of yellow (Y), magenta (M), cyan (C), and black (K). The image forming portions 20Y, 20M, 20C, and 20K are arranged in parallel on the lower side of the intermediate transfer belt 21 from the upstream side to the downstream side. Further, the laser exposure device 19 also has a plurality of laser exposure devices 19Y, 19M, 19C, 19K corresponding to the image forming units 20Y, 20M, 20C, 20K.

FIG. 2 is a configuration diagram showing an enlarged image forming unit 20K among the image forming units 20Y, 20M, 20C, and 20K. In the following description, since the image forming units 20Y, 20M, 20C, and 20K have the same configuration, the image forming unit 20K will be described as an example.

The image forming unit 20K has a photoconductor drum 22K which is an image carrier. A charged charger 23K, a developing device 24K, a primary transfer roller (transfer device) 25K, a cleaner 26K, a blade 27K, and the like are arranged around the photoconductor drum 22K along the rotation direction t. The exposure position of the photoconductor drum 22K is irradiated with light from the laser exposure device 19K to form an electrostatic latent image on the photoconductor drum 22K.

The charging charger 23K of the image forming unit 20K uniformly charges the surface of the photoconductor drum 22K. The developer 24K supplies a two-component developer containing black toner and carriers to the photoconductor drum 22K by a developing roller 24a to which a development bias is applied to develop an electrostatic latent image. The cleaner 26K uses a blade 27K to remove residual toner on the surface of the photoconductor drum 22K.

Further, as shown in FIG. 1, a toner cartridge 28 for supplying toner to the developing units 24Y to 24K is provided above the image forming portions 20Y to 20K. The toner cartridge 28 includes toner cartridges of each color of yellow (Y), magenta (M), cyan (C), and black (K).

The intermediate transfer belt 21 moves cyclically. The intermediate transfer belt 21 is stretched on the drive roller 31 and the driven roller 32. Further, the intermediate transfer belt 21 is in contact with the photoconductor drums 22Y to 22K facing each other. A primary transfer voltage is applied by the primary transfer roller 25K to the position of the intermediate transfer belt 21 facing the photoconductor drum 22K, and the toner image on the photoconductor drum 22K is primarily transferred to the intermediate transfer belt 21.

A secondary transfer roller 33 is arranged to face the drive roller 31 on which the intermediate transfer belt 21 is stretched. When the paper P passes between the drive roller 31 and the secondary transfer roller 33, the secondary transfer voltage is applied to the paper P by the secondary transfer roller 33. Then, the toner image on the intermediate transfer belt 21 is secondarily transferred to the paper P. A belt cleaner 34 is provided in the vicinity of the driven roller 32 of the intermediate transfer belt 21.

Further, as shown in FIG. 1, a paper feed roller 35 for conveying the paper P taken out from the paper feed cassette 18 is provided between the paper feed cassette 18 and the secondary transfer roller 33. Further, a fixing device 36 is provided downstream of the secondary transfer roller 33. A transport roller 37 is provided downstream of the fixing device 36. The transport roller 37 discharges the paper P to the paper ejection unit 38. Further, a reverse transfer path 39 is provided downstream of the fixing device 36. The reverse transfer path 39 reverses the paper P and guides it in the direction of the secondary transfer roller 33, and is used when performing double-sided printing. 1 and 2 show an example of carrying out the present invention, and do not limit the structure of the image forming apparatus portion other than the fixing device 36, and the structure of a known electrophotographic image forming apparatus can be used. it can.

FIG. 3 is a block diagram showing a configuration example of the control system 50 of the MFP 10 in the first embodiment. The control system 50 includes, for example, a CPU 100 that controls the entire MFP 10, a read-only memory (ROM) 120, a random access memory (RAM) 121, an interface (I / F) 122, an input / output control circuit 123, and a paper feed / transport control circuit. It includes 130, an image formation control circuit 140, and a fixing control circuit 150.

The CPU 100 realizes a processing function for image formation by executing a program stored in the ROM 120 or the RAM 121. The ROM 120 stores a control program, control data, and the like that control the basic operation of the image forming process. The RAM 121 is a working memory. The ROM 120 (or RAM 121) stores, for example, control programs such as the image forming unit 20 and the fixing device 36, and various control data used by the control programs. Specific examples of the control data in the present embodiment include the correspondence between the paper size and the heat generating member to be energized, the basis weight of the paper detected by various sensors in the MFP 10, the surface temperature of the heat generating member, the value of the outside air temperature, and the like. Examples include the correspondence with the heat generating member to be energized.

The fixing temperature control program of the fixing device 36 has a determination logic for determining the size and basis weight of the paper, the surface temperature of the heat generating member, the value of the outside air temperature, etc. based on the detection signal of the sensor in the MFP 10, and the paper passes through. It includes a heating control logic that controls heating in the heating means by selecting and energizing the switching element of the heat generating member corresponding to the position to be heated.

The I / F 122 communicates with various devices such as a user terminal and a facsimile. The input / output control circuit 123 controls the operation panel 123a and the display 123b. The paper feed / transport control circuit 130 controls the motor group 130a or the like that drives the paper feed roller 35 or the transport roller 37 of the transport path. The paper feed / transport control circuit 130 controls the motor group 130a and the like based on the control signal from the CPU 100 in consideration of the detection results of various sensors 130b in the vicinity of the paper feed cassette 18 or on the transport path. The image formation control circuit 140 controls the photoconductor drum 22, the charger 23, the laser exposure device 19, the developer 24, and the transfer device 25, respectively, based on the control signal from the CPU 100. The fixing control circuit 150 controls the drive motor 360 of the fixing device 36, the heating member 361, and the temperature detecting member 362 such as the thermistor based on the control signal from the CPU 100. In the present embodiment, the control program and control data of the fixing device 36 are stored in the storage device of the MFP 10 and executed by the CPU 100. However, a calculation processing device and a storage device are separately provided for the fixing device 36. You may.

FIG. 4 is a diagram showing a configuration example of the fixing device 36. Here, the fixing device 36 applies tension to the plate-shaped heating member 361, the elastic layer, the endless belt 363 suspended on a plurality of rollers, the belt transport roller 364 for driving the endless belt 363, and the endless belt 363. It includes a tension roller 365 and a press roller 366 having an elastic layer formed on the surface. In the heating member 361, the heat generating portion side comes into contact with the inside of the endless belt 363 and is pressed in the direction of the press roller 366 to form a fixing nip having a predetermined width with the press roller 366. Since the heating member 361 heats while forming the nip region, the responsiveness at the time of energization is higher than that in the case of the heating method using a halogen lamp.

In the endless belt 363, for example, a silicon rubber layer having a thickness of 200 um is formed on the outer side of a SUS base material having a thickness of 50 um or a polyimide which is a heat resistant resin of 70 um, and the outermost periphery is covered with a surface protective layer such as PFA. .. In the press roller 366, for example, a silicon sponge layer having a thickness of 5 mm is formed on the surface of an iron rod having a diameter of 10 mm, and the outermost periphery thereof is covered with a surface protective layer such as PFA.

Further, in the heating member 361, a glaze layer and a heat generation resistance layer are laminated on a ceramic substrate. An aluminum heat sink is glued to the other side to allow excess heat to escape and prevent the board from warping. The heat generation resistance layer is formed of a known material such as TaSiO _2, and is divided into a predetermined length and number in the main scanning direction.

The method for forming the heat generation resistance layer is the same as that of a known method (for example, a method for producing a thermal head), and a masking layer is formed of aluminum on the heat generation resistance layer. The aluminum layer is formed in a pattern in which adjacent heat generating members are insulated from each other and the heat generating resistor (heating member) is exposed in the paper transport direction. To energize the heat generating member, the wiring is connected from the aluminum layers (electrodes) at both ends, and each is connected to the switching element of the switching driver IC. Further, a protective layer is formed at the uppermost portion so as to cover all of the heat generating resistor, the aluminum layer, the wiring and the like. The protective layer is formed of, for example, Si ₃ N ₄ or the like.

FIG. 5 is a layout diagram of the heat generating member group in the present embodiment, and FIG. 6 is a diagram showing the heat generating member group and its drive circuit. As shown in these figures, a plurality of heat generating members 361a having a predetermined angle (here, about 45 degrees) with respect to the paper transport direction (vertical direction in the drawing) and divided into uniform widths are formed on the ceramic substrate. They are arranged side by side, and electrodes 361b are formed at both ends of the heat generating member 361a in the paper transport direction. It is shown that each of the heat generating members 361a is individually controlled to be energized by the corresponding drive IC 151. Specific examples of the drive IC 151 that is the switching unit of the heat generating member 361a include a switching element, a FET, a triax, a switching IC, and the like.

In the present embodiment, the heating member 361 is an aggregate of the heat generating members 361a having a parallelogram shape, and the bottom portions of the heat generating members 361a are arranged on the same line, so that the image area of the paper is fixed. At the time of processing, it passes over a plurality of heat generating members 361a. Therefore, for example, even if the heating element is not turned off after continuous operation, the apparent output is changed by thinning out these energizations at regular intervals with respect to the paper transport direction. It is possible to. This angle may be increased according to the resolution to be changed, and the configuration may span a large image area. By these thinning out, it is possible to arbitrarily adjust the output in increments of, for example, 1200 W to 0 W. Further, by changing the resistance value of the resistance heating element at regular intervals (changing the thickness and material of the heating layer), it is possible to set any output step instead of the output step at regular intervals. Since it can be handled by changing the shape of the masking layer described above, complicated changes are not required in the production process.

FIG. 7 is a diagram showing a connection state between the heat generating member group and the drive circuit thereof in the present embodiment. Here, it is shown that when the paper P is transported in the paper transport direction indicated by the arrow A, only the heat generating member 361a corresponding to the position through which the paper passes is selectively energized and heated. That is, only the paper P is intensively heated. Further, in the present embodiment, it is assumed that the size of the print area of the paper P is determined before the paper P is conveyed into the fixing device 36. Examples of the method for determining the print area of the paper P include a method using the analysis result of the image data, a method based on print format information such as a margin setting for the paper P, and a method based on the detection result of the optical sensor. Be done.

Hereinafter, the operation of the MFP 10 configured as described above during printing will be described with reference to the drawings. FIG. 8 is a flowchart showing a specific example of control of the MFP 10 in the present embodiment.

First, when the image data is read by the scanner unit 15 (Act101), the image formation control program in the image forming unit 20 and the fixing temperature control program in the fixing device 36 are executed in parallel.

When the image formation process is started, the read image data is processed (Act102), the electrostatic latent image is written on the surface of the photoconductor drum 22 (Act103), and the electrostatic latent image is developed by the developing device 24. (Act104), proceed to Act114.

On the other hand, when the fixing temperature control process is started, the paper size and thickness are determined based on, for example, the detection signal of the line sensor (not shown) arranged in the transport path and the paper selection information by the operation panel 14. (Act105), a group of heat generating members arranged at a position through which the paper P passes is selected as a heat generating target (Act106). For example, in the example shown in FIG. 7, 13 heat generating members 361a arranged in the center corresponding to the width of the paper P are selected. On the other hand, if the paper thickness is thin and the temperature rise rate is considered to be faster than that of normal paper even if the size is the same as that of FIG. 7, the energization target is reduced to 1/3 as shown in FIG. I do. Similarly, in addition to the thickness of the paper, the basis weight of the paper detected by the sensor, the surface temperature of the heat generating member, the value of the outside air temperature, and the like can be used as determination factors in selecting the energization target. FIG. 10 is a diagram showing how the paper P passes through the heat generating member group. Here, it is shown that the paper P is heated by any of the heat generating members during transportation, although the heating time to the same region is shortened because the number of objects to be energized is reduced.

Next, when the temperature control start signal for the selected heat generating member group is turned ON (Act107), the selected heat generating member group is energized and the temperature rises.
Next, when the surface temperature of the heat generating member group is detected by the temperature detecting member (not shown) arranged inside or outside the endless belt 363 (Act108), is the surface temperature of the heat generating member group within a predetermined temperature range? Whether or not it is determined (Act109). Here, if it is determined that the surface temperature of the heat generating member group is within a predetermined temperature range (Act109: Yes), the process proceeds to Act110. On the other hand, when it is determined that the surface temperature of the heat generating member group is not within the predetermined temperature range (Act109: No), the process proceeds to Act111.

In Act111, it is determined whether or not the surface temperature of the heat generating member group exceeds a predetermined temperature upper limit value. Here, when it is determined that the surface temperature of the heat generating member group exceeds a predetermined temperature upper limit value (Act111: Yes), the energization of the heat generating member group selected in Act106 is turned off (Act112). Return to Act108. On the other hand, when it is determined that the surface temperature of the heat generating member group does not exceed the predetermined temperature upper limit value (Act111: No), the surface temperature is less than the predetermined temperature lower limit value from the determination result of Act109. Therefore, the energization of the heat generating member group is maintained in the ON state, or is turned ON again (Act113), and the process returns to Act108. The ON / OFF ratio in Act 112 and Act 113 can be appropriately changed according to the difference between the surface temperature and the fixing temperature of the heat generating member group in order to adjust the temperature rising rate and the temperature lowering rate.

Next, when the paper P is conveyed to the transfer unit (Act110) while the surface temperature of the heat generating member group is within a predetermined temperature range, the toner image is transferred to the paper P (Act114), and then the paper P is fixed. Transport within 36.

Next, when the toner image is fixed on the paper P in the fixing device 36 (Act115), it is determined whether or not to end the printing process of the image data (Act116). Here, when it is determined that the printing process is finished (Act116: Yes), the energization of all the heat generating member groups is turned off (Act117), and the process is finished. On the other hand, when it is determined that the printing process of the image data has not been completed (Act116: No), that is, when the image data to be printed remains, the process returns to Act101 and the same process is repeated until the process is completed. ..

As described above, in the fixing device 36 according to the present embodiment, each of the heat generating members constituting the heating member 361 is inclined in a predetermined angle direction with respect to the conveying direction of the paper P and is formed to have the same length, and is endless. It is arranged in contact with the inside of the belt 363, and selectively energizes the heat generating member group through which the paper passes. By switching the heat generation region based on the paper size, not only can abnormal heat generation in the non-passing portion be prevented, but also unnecessary heating of the non-passing portion can be suppressed, so that the heat energy consumed by the fixing device 36 is significantly reduced. It is possible to do. Further, since the printed portion can be heated intensively and stably, the fixing quality can be improved. Further, since the heat generating member has an inclined shape, each image region of the paper passes while straddling a plurality of heat generating members. Even if the ratio of the heat-generating member that is energized is reduced based on the thickness of the paper, each image area of the paper is heated by the heat-generating member that is energized. It is also possible to control the heating in. This is particularly effective when switching when printing continuously on paper of different sizes and thicknesses.

In the above embodiment, the case where the non-passing paper portion is completely unheated has been described, but in order to quickly respond to the mixed paper size, the heating element of the non-passing paper portion is energized within a necessary range. It is also possible. In this case, it is also very effective to prevent abnormal heat generation due to the absence of heat flow in the non-passing portion. Further, although the heat generating member at the passing position is energized based on the paper size, it can be deformed so as to energize the heat generating member corresponding to the image forming region of the paper.

Although the embodiment of the present invention has been described above, the present embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. The present embodiment and its modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and the equivalent scope thereof.

36 ... Fixing device 150 ... Fixing device control circuit 151 ... Drive IC
361 ... Heating member 361a ... Heat generating member 362b ... Electrode 363 ... Endless belt 366 ... Pressurizing roller

Claims (7)

A rotating body of endless shape, is disposed in the straight direction orthogonal to the conveying direction of the predetermined is divided into lengths medium on which the toner image has been formed, while inclined at a predetermined angle with respect to the conveying direction, the rotating body of a plurality of heat-generating member in contact with the inner surface, anda switching unit for switching individual energization of a plurality of the heat generating member, of any of the medium portion also 2 or more of the plurality of the heat generating member A heating means that heats the medium by passing it through a heat generating member, and
A plurality of the heat generating member of said heating means and pressurizing means for the medium to form a nip through by pressure contact, conveying said medium to the conveying direction together with the heating means through said rotating body,
From among the heat generating members corresponding to the medium passes the position of the plurality of the heat generating member, to select the heating member via the switching unit, energizing a selected heating element selected by the first power Then, the heating control means for energizing the remaining non-selective heat generating member with a second power smaller than the first power, and
Equipped with a,
The heating control means
Any point of the medium to pass through the object selection heating member, the fixing device characterized that you select the object selection heating unit. It said heating control means, from among the heat generating members corresponding to the position where the medium passes, in response to the output adjustment of heating in the heating means, to select the heating member via the switching unit, and selected The fixing device according to claim 1, wherein the selected heat generating member is energized with a first power, and the remaining non-selected heat generating member is energized with a second power smaller than the first power . Further, a determination means for determining the size of the medium is provided.
The determination means determines, together with the size of the medium, any one of the thickness or basis weight of the medium, the surface temperature of the heat generating member, and the value of the outside air temperature.
Said heating control means, from among the heat generating members corresponding to the position where the medium passes, based on the determination result, selects the heating member via the switching unit, the first to be selected heating member selected The fixing device according to claim 1 or 2, wherein the non-selective heat generating member is energized with a power of 1 and the remaining non-selective heat generating member is energized with a second power smaller than the first power . Any one of claims 1 to 3, wherein the plurality of heat generating members are formed in a parallelogram shape and have the same size, and their bottom portions are arranged on the same line. The fixing device according to one item. The fixing device according to any one of claims 1 to 4, wherein the resistance values of the plurality of heat generating members are changed at regular intervals. Disposed directly direction orthogonal to the conveying direction of the medium, while inclined at a predetermined angle with respect to the transport direction, a plurality of heat-generating members which are divided into a predetermined length, the power supply to a plurality of said heat generating member individually and a switching unit switching to, any portion of the medium also passing the two or more heat-generating member of the plurality of the heat generating member, fixes the toner image on the medium by heating the medium pressurized and It is a fixing temperature control program of the fixing device to be used.
From among the heat generating members corresponding to the medium passes the position of the plurality of the heat generating member, and selecting the heat-generating member via the switching unit,
It energized to be selected heating member selected in the first power, and Luz step to energize the remaining non-selected heating element in the first power is less than the second power,
A fixing temperature control program for a fixing device, which comprises having a computer execute the above. The rotating body having an endless shape and the medium having the toner image formed by being divided into a predetermined length are arranged in a direction orthogonal to the transporting direction, and the rotating body is inclined at a predetermined angle with respect to the transporting direction. It has a plurality of heat generating members that come into contact with the inner surface and a switching unit that individually switches the energization of the plurality of the heat generating members, and any portion of the medium generates heat of two or more of the plurality of the heat generating members. A heating means that heats the medium by passing the member,
A pressurizing means for forming nips through which the medium passes by pressure-contacting the plurality of heat generating members of the heating means via the rotating body, and transporting the medium together with the heating means in the transport direction.
The heat-generating member is selected from the heat-generating members corresponding to the positions through which the medium passes among the plurality of heat-generating members via the switching portion, and the selected heat-generating member is energized with the first power. Then, the heating control means for energizing the remaining non-selective heat generating member with a second power smaller than the first power, and
With
The heating control means
A fixing device characterized in that the selected heat generating portion is selected so that any portion of the medium passes through the selected heat generating member.
An image forming unit that forms a toner image on the recording medium,
An image forming apparatus comprising.

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