Patent Application
20240069472
The present invention relates to image forming apparatuses such as copiers, printers, FAX machines, and multifunctional machines having multiple of these functions.
An image forming apparatus has a fixing device that fixes a toner image on a recording material by heating the toner image carried on the recording material. Such a fixing device, for example, fixes the toner image to the recording material by feeding and heating the recording material on which the toner image is carried in a nip portion formed between a first rotatable member, such as a fixing film, and a second rotatable member, such as a pressure roller, while pressurizing and heating the recording material.
As such a fixing device, a configuration in which the fixing device is moved back and forth in a widthwise direction that intersects a feeding direction of the recording material has been proposed (e.g., Japanese Laid-Open Patent Application No. 2000-194216) in order to prevent partial damage to the first rotatable member.
Furthermore, as a fixing device, a configuration in which an area on the edge side of the first rotatable member is cooled by a fan to prevent a non-passing portion where the recording material does not pass from heating up (non-passing portion heating) has also been proposed (e.g., Japanese Laid-Open Patent Application No. 2013-134421).
As described in Japanese Laid-Open Patent Application No. 2000-194216, when the fixing device is configured to move back and forth (reciprocating operation), the temperature balance of both ends of the first rotatable member in the widthwise direction is disrupted before and after the reciprocating operation of the fixing device. This is because the positional relationship in the widthwise direction between the heater that heats the first rotatable member and the recording material that passes through the nip portion changes before and after the reciprocating operation. For example, when the fixing device is moved to one side of the nip portion from the center position in the widthwise direction by the reciprocating operation, the recording material passes through the nip portion on the other side than the center position. Therefore, the non-passing portion of the first rotatable member is more likely to heat up on one side of the first rotator, while the non-passing portion is less likely to heat up on the other side.
Here, it is conceivable to combine the configuration for cooling the ends of the first rotatable member to suppress the temperature rise of the non-passing portion, as described in Japanese Laid-Open Patent Application No. 2013-134421, with the configuration for reciprocating operation as described above. However, in the case of a conventional configuration that blows air toward the ends of the first rotatable member to suppress the rise in temperature of the non-passing portion, the air flow rate (air flow) to each of the two ends of the first rotatable member is the same. Therefore, the combination of these configurations does not improve the temperature imbalance at both ends of the first rotatable member in the widthwise direction due to reciprocating operation.
The purpose of the present invention is to provide a configuration that can suppress the temperature imbalance at the widthwise direction end of the first rotatable member, even if the fixing device is configured to move back and forth.
The present invention is an image forming apparatus comprising a fixing device including a first rotatable member, a second rotatable member configured to form a nip portion where a recording material on which a toner image is carried is nipped and conveyed between the first rotatable member and the second rotatable member and the toner image is fixed on the recording material, and a heating portion configured to heat the first rotatable member; an air blowing portion configured to blow air; a first duct configured to guide the air blown from the air blowing portion toward a first area of the first rotatable member on a first end side from a central portion of the first rotatable member with respect to a widthwise direction crossing to a conveyance direction of the recording material; a first shutter capable of changing an opening width of the first duct; a second duct configured to guide the air blown from the air blowing portion toward a second area of the first rotatable member on a second end side opposite to the first end side from the central portion of the first rotatable member with respect to the widthwise direction; a second shutter capable of changing an opening width of the second duct; a reciprocating portion configured to reciprocate the fixing device in the widthwise direction; and a control portion configured to change at least one opening width of the opening width of the first duct formed by the first shutter and the opening width of the second duct formed by the second shutter depending on a position with respect to the widthwise direction of the fixing device.
In addition, an image forming apparatus comprising a fixing device including a first rotatable member, a second rotatable member configured to form a nip portion where a recording material on which a toner image is carried is nipped and conveyed between the first rotatable member and the second rotatable member and the toner image is fixed on the recording material, a heating portion configured to heat the first rotatable member, a first temperature detecting portion configured to detect a temperature of the first rotatable member on a first end side from a central portion of the first rotatable member with respect to a widthwise direction crossing a conveyance direction of the recording material, and a second temperature detecting portion configured to detect a temperature of the first rotatable member on a second end side opposite to the first end side from the central portion with respect to the widthwise direction, a first air blowing portion configured to blow air toward a first area of the first rotatable member on the first end side from the central portion with respect to the widthwise direction, a second air blowing portion configured to blow air toward a second area of the first rotatable member on the second end side from the central portion with respect to the widthwise direction, a reciprocating portion configured to reciprocate the fixing device in the widthwise direction; and a control portion configured to control driving and stopping of the first air blowing portion based on the temperature detected by the first temperature detecting portion and control driving and stopping of the second air blowing portion based on the temperature detected by the second temperature detecting portion, wherein the control portion configured to change at least one temperature of the temperature at which the first air blowing portion starts the driving and the temperature at which the second air blowing portion starts the driving.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Part (a) of
Embodiment 1 will be explained using
An image forming apparatus 1 is, for example, a printer. In a fixing portion 10, after transferring the toner image formed on a photosensitive drum 11 to a recording material P, the image is fixed on the recording material P by a fixing device 40. As shown in
Around each photosensitive drum 11, respectively, are placed a charger 12, an exposure unit 13, a developing unit 14, a primary transfer blade 17, and a cleaner 15. In the following, the procedure for forming a Bk color toner image will be explained, but the procedures for forming toner images of other colors is also similar. The recording material P is, for example, a sheet of paper, plastic sheet, or the like.
First, the procedure for forming a toner image on a recording material P is explained. The surface of the photosensitive drum 11 is uniformly charged by the charger 12, and then exposed by the exposure unit 13 according to the image information. This forms an electrostatic latent image on the photosensitive drum 11. The developing unit 14 develops toner on the electrostatic latent image obtained by the exposure unit 13 to form a toner image on the photosensitive drum 11. At this time, the same process is performed for other colors.
The toner images on each photosensitive drum 11 are transferred to an intermediary transfer belt 31 as an intermediary transfer member by the primary transfer blade 17 in a sequential overlapping primary transfer. As a result, a full-color toner image is formed on the intermediary transfer belt 31. Any toner remaining on the photosensitive drum 11 after the primary transfer is removed by the cleaner 15. Thus, the photosensitive drum 11 becomes ready for the next image formation.
Meanwhile, the recording material P accommodated in a feed cassette 20 or placed in a multi-feed tray 25 is fed out one by one by the feeding mechanism (not shown) and fed into a registration roller pair 23. The registration roller pair 23 stops the recording material P once, straightens the direction of the recording material P if it is at an angle to the feeding direction, synchronizes it with the toner image on the intermediary transfer belt 31, and feeds the recording material P between the intermediary transfer belt 31 and a secondary transfer roller 35. The secondary transfer roller 35 performs a secondary transfer of the toner image on the intermediary transfer belt 31 to the recording material P.
The recording material P on which the toner image is transferred is fed to the fixing device 40, where the toner image permanently fixed on the recording material P is formed by the heating and pressurizing process. The recording material P that has passed through the fixing device 40 is discharged to a discharge tray 26a or 26b by discharge rollers 43a and 43b. In the case of double-sided printing mode, the recording material P discharged by the discharge rollers 43a and 43b is switched back and fed into a double-sided feeding path 27, and is again fed into the registration roller pair 23. Then, as described above, a toner image is formed on the back side of the recording material P.
Next, the fixing device 40 will be explained using
The pressure roller 70 as the second rotatable member forms a nip portion N for fixing the toner image to the recording material by nipping and feeding the recording material P bearing the toner image between it and the fixing film 603. That is, as shown in
The film unit 60 is for heating and pressurizing the toner image on the recording material P. It is installed parallel to the pressure roller 70 and consists of a heater 600, a heater holder 601, a support stay 602, and a fixing film 603.
The fixing film 603 is pressed toward the pressure roller 70 so that the fixing nip portion N is of a predetermined width. The heater 600 has a substrate 610 and a heating resistor member 620 on the substrate 610, and is fixed in a recess on the underside of the heater holder 601. In the present embodiment, the heating member 620 is provided on the back side of the substrate 610 (the side not in contact with the fixing film 603), but it is not limited to this, and the heating member may be provided on the front side (the side in contact with the fixing film 603).
A semi-solid lubricant (hereinafter referred to as “grease”) consisting of a solid component (compound) and a base oil component (oil) is applied to the surface of the plate 610 to reduce the sliding load between the fixing film 603 and the heater 600, and to assure the slidability between the heater 600 and the fixing film 603 and between the heater holder 601 and the fixing film 603. The grease compound include solid lubricants such as graphite and molybdenum disulfide, metal oxides such as zinc oxide and silica, and fluoropolymers such as polytetrafluoroethylene (PTFE). The grease oils include heat-resistant polymer resin oils such as silicone oil and fluoro silicone oil. In the present embodiment, the grease is made of PTFE powder particles (particle size 3 μm) as the compound and fluoro silicone oil as the oil.
The fixing film 603 is a cylindrical film for heating and pressurizing the toner image on the recording material at the fixing nip portion N.
A heater holder 601 (hereafter referred to as holder 601) is a member that holds the heater 600 pressed toward the fixing film 603. The holder 601 has a semi-circular arc shape in cross section and functions to regulate the rotation path of the fixing film 603. The heater holder 601 is made of high heat-resistant resin or the like, and in this embodiment, ZENITE 7755 (trade name) manufactured by Du Pont de Nemours and Company is used.
A support stay 602 is a member that supports the heater 600 via the heater holder 601. The support stay 602 should be made of a material that does not flex easily even when a large load is applied, and stainless steel (SUS304) is used in the present embodiment.
As shown in
A connector 500 is a power-feeding member that is electrically connected to the heater 600 to apply voltage to the heater 600, and is detachable and attachable to one end side of the heater 600 in the longitudinal direction.
As shown in
As shown in
Thermistor (TH) 630, shown in
Next, a reciprocating mechanism 700 of the present embodiment is explained. The fixing film 603 is formed of a soft resin or the like with relatively good mold-releasing properties, such as PFA or PTFE, for its surface layer to prevent toner adhesion from the recording material. Therefore, the surface of the fixing film 603 is easily scratched in the rotational direction (circumferential direction) by the paper edges (burrs) that occur at the edge cut of the paper when the paper or other recording material passes through the nip portion N and the paper is cut. These scratches (“paper edge damages”) tend to become deeper and larger as the recording material repeatedly passes through the same spot against the fixing film 603. In other words, the surface of the fixing film 603 is locally scratched.
If the surface of the fixing film 603 has deeper and larger paper edge damages, when the maximum size width of the recording material passes through the nip portion N in the widthwise direction that intersects the feeding malfunction direction of the recording material, the position of the scars may overlap with the image area of the recording material, causing a thread-like image defect to occur on the recording material after fixing.
Therefore, the present embodiment has a reciprocating mechanism 700 as a reciprocating moving portion that reciprocates the fixing device 40 in the widthwise direction (reciprocating movement) in order to distribute or disperse paperedge damages in the widthwise direction and to suppress deep and large localized damages on the surface of the fixing film 603. This reciprocating mechanism 700 is explained using parts (a) and (b) of
In the present embodiment, the fixing device 40 is supported by a roller 706 and can move back and forth in the widthwise direction by moving on a slider 704 provided on the main assembly of the image forming apparatus 1 by rotation of the roller 706.
The reciprocating mechanism 700 has a reciprocating cam 703 and a reciprocating motor M2. The side plate of the fixing device 40 is provided with a projection 40a that fits into a slot 703a of the reciprocating cam 703. The reciprocating cam 703 is fixed to the main assembly of the image forming apparatus 1, which can be rotated by the reciprocating motor M2. The reciprocating motor M2 is composed of a stepping motor and controls the rotation of the reciprocating cam 703. The reciprocating cam 703 is formed in a cylindrical shape with a slot 703a on its outer circumference. This groove 703a is formed in a shape that displaces the projection 40a fitted to the reciprocating cam 703 in an axial direction (widthwise direction) as it advances in the circumferential direction, specifically in an abbreviated V-shape as shown in the Figure.
When the reciprocating cam 703 rotates, the projection 40a fitted in the slot 703a moves along the groove 703a in the axial direction of the reciprocating cam 703. That is, as the reciprocating cam 703 fixed to the image forming apparatus 1 rotates, the projection 40a secured to the fixing device 40 moves in the rotational direction of the reciprocating cam 703. This makes it possible to move the recording material P fed direction by the image forming apparatus 1 and the fixing device 40 relatively with respect to the widthwise direction.
As a result, it is possible to suppress the edge of the recording material P from repeatedly passing through one part of the surface of the fixing film 603 (and also the pressure roller 70) and to delay the progress of wear caused by contact between the fixing film 603 (and also the pressure roller 70) and the edge of the recording material. In this embodiment, as shown in
As can be understood from
In the present embodiment, during image forming of the maximum size width recording material P, the reciprocation operation is stopped at the position indicated by symbol b in
Next, a cooling mechanism 800 of the present embodiment will be described using
The following is a specific explanation. When the largest-sized recording material is passed through the nip portion N to fix the toner image on the recording material, the surfaces of the fixing film and pressure roller have an approximately uniform temperature distribution over the entire fixing portion with respect to the widthwise direction. However, when continuously fixing small-sized recording material, the temperature of the surfaces of the fixing film and pressure roller in the non-passing portion where the recording material does not pass rises excessively. This is because when small-sized recording material is continuously passed through the nip portion N, heat is not taken away by the recording material in the non-passing portion area where the recording material does not pass, and heat is partially accumulated in that portion.
If the temperature of the non-passing area rises due to the continuous passing of small-sized recording material through the nip portion N, the recording material will pass through the non-passing area in the small-sized recording material when the larger-sized recording material, including the largest-sized recording material, is passed through the nip portion N in the next job. In this case, if the non-passing area exceeds the appropriate fixing temperature, the toner melts excessively and a part of it remains on the fixing film, which is fixed on the recording material after a delay of one lap. This causes an image defect called high-temperature offset.
In addition, uneven temperature in the longitudinal direction of the non-passing area causes uneven gloss on the image. Furthermore, when the temperature rise reaches a high temperature, control may be performed to suppress the temperature rise in the non-passing area by increasing the interval between recording material continuously passing through the nip portion N. In this case, productivity is reduced. The temperature rise in the non-passing area increases under conditions where the amount of heat lost by the recording material increases. For example, when the number of sheets processed per unit time (productivity) is large, or when the weight per unit area of recording material is large (so-called thick paper).
Therefore, in the present embodiment, a cooling mechanism 800 is provided to suppress the temperature rise of the non-passing portion of the fixing film 603, which occurs when small-sized recording material is continuously processed for fixing, by cooling (air blowing). As shown in
That is, the fan 44a blows air through the duct 45a toward the first area of the fixing film 603 that is on the first end side of the fixing film 603 from the center of the fixing film 603 with respect to the widthwise direction that intersects with respect to the feeding direction of the recording material. The fan 44b also blows air through the duct 45b toward the second region of the fixing film 603, which is the second end side opposite to the first end side from the center of the fixing film 603 in the widthwise direction. Here, the first and second areas correspond to the areas on both sides in the widthwise direction of the area through which the small-sized recording material passes when the small-sized recording material is passed through the fixing nip portion N, in other words, the area through which the small-sized recording material does not pass.
The cooling mechanism 800 has shutters 47a and 47b as adjusting members that adjust the opening width of the openings 46a and 46b according to the width of the recording material used, and a shutter driving portion 48 (
The fans 44a, 44b, ducts 45a, 45b, openings 46a, 46b, and shutters 47a, 47b are symmetrically arranged in the longitudinal direction (widthwise direction) of the fixing film 603. In the present embodiment, axial flow fans are used as fans 44a and 44b, but centrifugal fans such as sirocco fans may also be used.
Such operation of the fans 44a and 44b is performed when the temperature of a thermistor (temperature sensing portion) 631 in
Next, the drive configuration of shutters 47a and 47b will be explained using
When the pinion gear 51 is rotated forward and backward by the forward and reverse rotation driving of the shutter motor M3, the shutters 47a and 47b on both sides are linked together to open and close the corresponding openings 46a and 46b in a symmetrical relationship with respect to the widthwise direction. As shown in
When the width information of the recording material P is the maximum size recording material, the control circuitry 90 controls the shutter driving portion 48 to move to the fully closed position where the openings 46a and 46b are closed by the shutters 47a and 47b, as shown in
The image forming apparatus 1 is equipped with a control circuit portion 90 as a control portion. The control circuit portion 90 is explained using
The control circuit portion 90 performs various controls of the image forming apparatus 1, such as image forming operations, and has, for example, a CPU (Central Processing Unit) and a memory. The memory consists of ROM (Read Only Memory) and RAM (Random Access Memory). The memory stores various programs for controlling the image forming apparatus 1 and various data such as the maximum size width of recording material P that can form an image and the reciprocal center mentioned above, etc. The CPU can execute the various programs stored in the memory and operates the image forming apparatus 1 by executing the various programs. In the case of the present embodiment, the CPU is capable of executing “image forming job processing (program),” “reciprocation control processing (program),” and “cooling control processing (program)” stored in the memory. The memory can also temporarily store arithmetic processing results, etc. associated with the execution of various programs.
An image forming job is a series of operations from the start of image forming to the completion of image forming based on a print signal to form an image on recording material P. In other words, it is a series of operations from the start of the preliminary operation (so-called “pre-rotation”) necessary for image forming, through the image forming process, to the completion of the preliminary operation (so-called “post-rotation”) necessary for completing image forming. Specifically, it refers to the period from the pre-rotation (preparation operation before image formation) to the post-rotation (operation after image formation) after receiving a print signal, including the image formation period and the period between the trailing end and leading end of consecutive recording material (so-called “paper interval”).
The control portion 90 is further connected to a fixing drive motor M1, reciprocating motor M2, shutter motor M3, heater energizing circuit 92, fan 44a on the front side, fan 44b on the back side, and thermistors 630 and 631 via an input/output interface. In the present embodiment, the front side is the side where the user operates the image forming apparatus 1, for example, the side where the operation panel is installed, and the rear side is the opposite side of the front side. The direction from the front side to the back side and vice versa is the widthwise direction described above.
When an instruction to start an image forming job is received from an external host device such as a personal computer or from a control panel, the control portion 90 executes the “image forming job processing” stored in the memory. The control circuit portion 90 controls the image forming apparatus 1 based on the execution of the “image forming job processing.” Accordingly, the control circuit portion 90 drives the fixing drive motor M1 to rotate the pressure roller 70, thereby following the fixing film 603. The control circuit portion 90 then controls the temperature by the heater energizing circuit 92 so that the surface temperature of the fixing film 603 becomes the desired target temperature.
The control circuit 90 controls the reciprocating motor M2 to rotate the reciprocating cam 703 to perform reciprocating operation of the fixing device 40 every time a predetermined number of sheets of recording material P are discharged from the fixing nip portion N. That is, the control circuit 90 controls the reciprocating mechanism 700 to move the fixing device 40 every time a predetermined number of sheets of recording material passes through the nip portion N. In addition, at the same time when the reciprocating operation is executed, the cooling mechanism 800 is controlled to change the cooling control of the fixing film 603 on the first end portion (one end portion) and the second end portion (reverse end portion) independently of each other.
Next, the airflow correction of fans 44a and 44b in the present embodiment is explained. As described above, when the fixing device is operated in reciprocating mode, the temperature balance at the end portion of the fixing film in the widthwise direction is out of balance. Therefore, in the present embodiment, the airflow of at least one of the fans 44a and 44b is changed according to the position of the fixing device 40 in the widthwise direction.
Specifically, when the fixing device 40 is in the center position with respect to the widthwise direction, the control circuit portion 90 sets the airflow of fan 44a to the first airflow and the airflow of fan 44b to the second airflow. This central position is the reciprocating center described above. Next, when the fixing device 40 is moved by the reciprocating mechanism 700 and the fixing device 40 is positioned on the first end side (front side) with respect to the center position in the widthwise direction, the airflow of the fan 44a is set to the third airflow which is smaller than the first airflow and the airflow of the fan 44b is set to the fourth airflow which is larger than the second airflow. Similarly, when the fixing device 40 is located on the second end side (back side) than the center position with respect to the widthwise direction, the airflow of fan 44a shall be larger than the first airflow and the airflow of fan 44b shall be smaller than the second airflow. In other words, the airflow of the fan on the side where the fixing device 40 is moved is lowered and the airflow of the fan on the opposite side is increased.
The airflow may be changed in steps according to the position of the fixing device 40 in the widthwise direction. For example, when the fixing device 40 is located at the first position on the first end side than the center position with respect to the widthwise direction, the airflow of the fan 44a is the third flow rate and the airflow of the fan 44b is the fourth airflow. When the fixing device 40 is located at the second position on the first end side than the first position with respect to the widthwise direction, the airflow of the fan 44a shall be the fifth airflow which is smaller than the third airflow and the airflow of the fan 44b shall be the sixth airflow which is larger than the fourth airflow. The same applies when the fixing device 40 is moved to the second end portion side.
The airflow of the fans may be changed by only one of the fans. For example, when the airflow of the fan 44a at the center position is set as the first airflow and the airflow of the fan 44b as the second airflow as described above, if the fixing device 40 is located at the first end position than the center position in the widthwise direction, the airflow of the fan 44a is set as the third airflow, which is smaller than the first airflow, and the airflow of the fan 44b is remains at the second airflow. Alternatively, when the fixing device 40 is located on the first end portion side than the center position with respect to the widthwise direction, the airflow of the fan 44a may remain at the first airflow and the airflow of the fan 44b may be the fourth airflow which is greater than the second airflow. The same applies when the fixing device 40 is moved to the second end portion side.
In the present embodiment, the airflow of at least one of the fans 44a and 44b is changed at the timing when the fixing device 40 is moved by the reciprocating mechanism 700. However, the timing for changing the airflow is not limited to this; for example, after the fixing device 40 is moved, the temperature of the area on at least one of the first and second end portions sides of the fixing film 603 can be measured, and the airflow can be changed according to that temperature. For example, if the temperature on the side where the fixing device 40 is moved is measured, the airflow may be changed when the measured temperature drops below a certain temperature, and if the temperature on the side opposite to the side where the fixing device 40 is moved is measured, the airflow may be changed when the measured temperature rises above a certain temperature. Or, the airflow may be changed after a certain number of sheets of recording material pass through the nip portion N after the fixing device 40 is moved.
In the present embodiment, the cooling efficiency by the fans 44a and 44b is changed according to the position of the fixing device 40 in the widthwise direction, by changing the airflow of at least one of the fans 44a and 44b. Therefore, even in a configuration where the fixing device 40 is moved back and forth, the temperature balance at the end portions of the fixing film 603 in the widthwise direction can be suppressed.
For example, when the fixing device 40 moves to the first end portion side, the airflow of the fan 44a is reduced and the airflow of the fan 44b is increased. This allows the side to be cooled efficiently by the fan 44b, which has a wider non-passing area, while suppressing excessive cooling of the side to be cooled by the fan 44a, which has a narrower non-passing area due to the fixing device 40 moving.
The flowchart in
On the other hand, if the recording material is not the maximum width size in the widthwise direction (No in S003), printing is executed as is (S007), and the job is continued until printing is completed (S008). When the number of sheets reaches a predetermined number during the job (Yes in S009), the reciprocation operation is executed, and fan airflow correction as described above is also performed (S010).
In the present embodiment, the airflow correction of the fan employs a method in which the amount of correction is determined according to the reciprocation volume. That is, the airflow is changed in steps according to the position of the fixing device 40 in the widthwise direction. Table 1 shows an example of the airflow correction amount. In Table 1, the position of the fixing device 40 is shown as plus when the fixing device 40 moves from the center of the reciprocator to the front side and minus when the fixing device 40 moves to the back side. The airflow correction amount is expressed as a percentage increase or decrease relative to the airflow of the fan when the fixing device 40 is at the center of the reciprocator, using the airflow of the fan when the fixing device 40 is at the center of the reciprocator as a standard.
As shown in Table 1, for example, the fan airflow at the center of reciprocation was used as the standard, and when the reciprocation volume moved to the 0.3 mm position to the back side, the airflow of the fan 44a on the front side was set at +5% and that of the fan 44b on the back side at −5%. In another example, when the reciprocation volume moved to the 0.6 mm position on the front side, the airflow of the fan 44a on the front side was set at −10% and that of the fan 44b on the back side at +10%. In the present embodiment, the reciprocation amount per reciprocation was about 0.3 mm, and the fan airflow was also set correspondingly for every 0.3 mm.
Next, the results of experiments conducted with an embodiment example in which the control of the present embodiment was performed and a comparative example in which the control of the present embodiment was not performed is explained. In the embodiment example, image formation was performed according to the flow shown in
In the embodiment and comparative examples, image forming apparatus with the same configuration was used, and the same control was applied except for the control of the fan airflow change. The conditions for the embodiment and comparative examples were also the same. The experiments were conducted at a feeding speed of 260 mm/s for recording material, a print speed of 60 sheets/minute, paper type: CS068 (A4 size), and number of printed sheets: 1000 sheets. Reciprocation operation was performed once every 250 sheets. The temperature transition of the center position in the widthwise direction of the fixing film 603, the end position in the front side, and the end position in the back side was examined. Specifically, as shown in
The results of the above mentioned experiments are shown in
Embodiment 2 is explained using
In the present embodiment, as in embodiment 1, the cooling mechanism 800 has a fan 44a on the front side and a fan 44b on the back side as the airflow portion, a duct 45a as the first duct, and a duct 45b as the second duct. The duct 45a guides air sent from the fan 44a toward the first area, and the duct 45b guides air sent from the fan 44b toward the second area. In the present embodiment, for example, the air blowing portion may be a single fan, and the air from this fan may be split into duct 45a and duct 45b to send the air.
It is also similar to embodiment 1 in that it has shutters 47a and 47b that change the opening width of the respective openings 46a and 46b of the ducts 45a and 45b. However, unlike embodiment 1, in the present embodiment, the shutters 47a and 47b can be driven separately. For this purpose, the present embodiment has a shutter motor M3 to drive shutter 47a and a shutter motor M4 to drive shutter 47b, as shown in
The location of the thermistor as a temperature detection portion that detects the temperature of the heater 600 or fixing film 603 in the present embodiment is explained using
That is, thermistor TH4 is disposed inside the fixing film 603, for example, contacting or in proximity to the inner circumferential surface of the center portion of the fixing film 603 in the widthwise direction to detect the temperature of the fixing film 603. Thermistors TH5 and TH6 are disposed inside the fixing film 603 and detect the temperature of the fixing film 603, for example, by contacting or in proximity to the inner circumferential surface of the first and second end portions of the fixing film 603 in the widthwise direction, compared to the center portion. In
The detection information (signal values related to temperature) of the thermistors TH1, TH2, TH3, TH4, TH5, and TH6 are input to the control circuit portion 90 via an A/D converter. The control circuit portion 90 controls the power supplied to the heater 600 according to the detected temperature of the thermistor TH4. The control circuit portion 90 also controls the driving and stopping of the fans 44a and 44b based on the temperature detected by the thermistors TH5 and TH6. That is, the operation of fans 44a and 44b is performed when the temperature of thermistors TH5 and TH6 exceeds a predetermined temperature. For example, the drive of fan 44a is started when the temperature of the thermistor TH5 exceeds the predetermined temperature, and the drive of fan 44b is started when the temperature of thermistor TH6 exceeds the predetermined temperature.
Next, the opening width correction of shutters 47a and 47b in the present embodiment is explained. In the present embodiment, the opening width of at least one of the duct 45a formed by the shutter 47a and the opening width of the duct 45b formed by the shutter 47b is changed according to the position of the fixing device 40 in the widthwise direction. The opening width of the duct 45a formed by the shutter 47a is hereinafter referred to as the opening width of the shutter 47a, and the opening width of the duct 45b formed by the shutter 47b is hereinafter referred to as the opening width of the shutter 47b.
Specifically, when the fixing control portion 40 is in the center position with respect to the widthwise direction, the control circuit portion 90 shall set the opening width of shutter 47a to the first opening width and the opening width of shutter 47b to the second opening width. The central position is the reciprocal center as described above. Next, the fixing device 40 is moved by the reciprocating mechanism 700, and when the fixing device 40 is located on the first end side (front side) than the central position with respect to the widthwise direction, the opening width of the shutter 47a is the third opening width which is narrower than the first opening width and the opening width of the shutter 47b is the fourth opening width which is wider than the second opening width. Similarly, when the fixing device 40 is located on the second end side (back side) than the center position with respect to the widthwise direction, the opening width of the shutter 47a shall be wider than the first opening width and the opening width of the shutter 47b shall be narrower than the second opening width. In other words, the opening width of the shutter on the side where the fixing device 40 is moved is narrower and the opening width of the shutter on the opposite side is wider.
The opening width of the shutters may be changed in steps according to the position of the fixing device 40 in the widthwise direction. For example, when the fixing device 40 is located at the first position on the first end side than the center position with respect to the widthwise direction, the opening width of the shutter 47a is the third opening width and the opening width of the shutter 47b is the fourth opening width. When the fixing device 40 is positioned in the second position on the first end side with respect to the first position with respect to the widthwise direction, the opening width of the shutter 47a shall be the fifth opening width, which is narrower than the third opening width, and the opening width of the shutter 47b shall be the sixth opening width, which is wider than the fourth opening width. The same applies when the fixing device 40 is moved to the second end portion side.
The opening width change of the shutters may be made only for one of the shutters. For example, when the opening width of the shutter 47a at the center position is the first opening width and the opening width of the shutter 47b is the second opening width as described above, if the fixing device 40 is located on the first end side of the first position than the center position in the widthwise direction, the opening width of the shutter 47a is the third opening width which is narrower than the first opening width, and the opening width of the shutter 47b may remain at the second opening width. Alternatively, when the fixing device 40 is located on the first end side with respect to the center position with respect to the widthwise direction, the opening width of the shutter 47a may remain at the first opening width and the opening width of the shutter 47b may be the fourth opening width, which is wider than the second opening width. The same applies when the fixing device 40 is moved to the second end portion side.
In the present embodiment, the change of the opening width of at least one of the shutters 47a and 47b is made at the timing when the fixing device 40 is moved by the reciprocating mechanism 700. However, the timing for changing the opening width is not limited to this; for example, after the fixing device 40 is moved, the temperature of at least one of the areas on the first end portion side and the second end portion side of the fixing film 603 can be measured, and the opening width can be changed according to that temperature. For example, if the temperature on the side where the device is moved is measured, the opening width may be changed when the measured temperature drops below a certain temperature, and if the temperature on the side opposite to the side where the device is moved is measured, the opening width may be changed when the measured temperature rises above a certain temperature. Alternatively, the opening width may be changed after a certain number of sheets of recording material pass through the nip portion N after the fixing device 40 is moved.
In the present embodiment, the cooling efficiency by the fans 44a and 44b is changed according to the position of the fixing device 40 in the widthwise direction by changing the opening width of at least one of the shutter 47a and the opening width of the shutter 47b according to the position of the fixing device 40 in the widthwise direction. Therefore, even in a configuration where the fixing device 40 is moved back and forth, the temperature balance at the end of the fixing film 603 in the widthwise direction can be suppressed.
For example, when the fixing device 40 moves to the first end portion side, the opening width of the shutter 47a is narrowed and the opening width of the shutter 47b is widened. This allows the side to be cooled efficiently by the fan 44b, which has a wider non-passing area, while suppressing excessive cooling of the side to be blown by the fan 44a, which has a narrower non-passing area as the fixing device 40 moves.
The flowchart in
In the present embodiment, the shutter opening width correction employs a means of determining the amount of correction according to the reciprocation amount. That is, the airflow was changed in steps according to the position of the fixing device 40 in the widthwise direction. Table 2 shows an example of the shutter opening width correction amount (hereinafter also referred to as correction width). In Table 2, the position of the fixing device 40 is shown as plus when the fixing device 40 is moved from the center of the reciprocator to the front side and minus when the fixing device 40 is moved to the back side. The correction width is based on the opening width of the shutter when the fixing device 40 is at the reciprocal center, and is expressed as the amount of increase or decrease relative to this standard opening width.
As shown in Table 2, for example, the opening width of the front side shutter 47a is +1 mm and the opening width of the back side shutter 47b is −1 mm when the reciprocation amount moves to the 0.3 mm position on the back side, based on the shutter position at the center of reciprocation. In another example, when the reciprocation amount moved to the 0.6 mm position on the front side, the opening width of the shutter 47a on the front side was set to −2 mm and the opening width of the shutter 47b on the back side to +2 mm. The reciprocation amount per reciprocation was approximately 0.3 mm, and the shutter opening widths were set correspondingly for every 0.3 mm.
Next, the results of experiments conducted with an embodiment example in which the control of the present embodiment was performed is described. In the embodiment example, image formation was performed according to the flow shown in
The third embodiment is described using
The location of the thermistor as a temperature detection portion that detects the temperature of the heater 600 or fixing film 603 in the present embodiment is the same as in embodiment 2 shown in
The thermistors TH5 and TH6 are disposed inside the fixing film 603, for example, contacting or in proximity to the inner surface of the first and second end portions of the fixing film 603, which are closer to the inner surface of the fixing film 603 than the center portion with respect to the widthwise direction, and detect the temperature of the fixing film 603. In
The control circuit portion 90 controls the driving and stopping of the fan 44a based on the temperature detected by the thermistor TH5 and the driving and stopping of the fan 44b based on the temperature detected by the thermistor TH6. For example, the drive of the fan 44a is started when the temperature of the thermistor TH5 exceeds the predetermined temperature, and the drive of the fan 44b is started when the temperature of the thermistor TH6 exceeds the predetermined temperature. In the present embodiment, this predetermined temperature is compensated by the reciprocation amount of the fixing device 40. That is, the control circuit portion 90 changes at least one of the temperature at which the fan 44a starts driving and the temperature at which the fan 44b starts driving, depending on the position of the fixing device 40 in the widthwise direction. In the present embodiment, the airflow of the fans 44a and 44b is not changed.
Specifically, when the fixing temperature control portion 40 is in the center position with respect to the widthwise direction, the control circuit 90 sets the temperature at which the fan 44a starts driving as the first temperature and the temperature at which the fan 44b starts driving as the second temperature. This central position is the reciprocal center mentioned above. Next, the fixing device 40 is moved by the reciprocating mechanism 700, and when the fixing device 40 is located on the first end side (front side) than the center position with respect to the widthwise direction, the temperature at which the fan 44a starts driving is the third temperature higher than the first temperature and the temperature at which the fan 44b starts driving is the second temperature lower than the second temperature. Similarly, when the fixing device 40 is located on the second end side (back side) than the center position with respect to the widthwise direction, the temperature at which the fan 44a starts driving is lower than the first temperature and the temperature at which the fan 44b starts driving is higher than the second temperature. That is, the temperature at which the fan on the side where the fixing device 40 is moved is set to start driving at a higher temperature, and the temperature at which the fan on the opposite side starts driving is set to be lower. The fan drive start temperature may be changed in steps according to the position of the fixing device 40 in the widthwise direction.
The fan drive start temperature change may be made at only one of the temperatures. For example, if the drive start temperature of the fan 44a at the center position is the first temperature and the drive start temperature of the fan 44b is the second temperature as described above, when the fixing device 40 is located on the first end portion of the fixing portion compared to the center position in the widthwise direction, the drive start temperature of the fan 44a is the third temperature higher than the first temperature and the drive start temperature of fan 44b may remain at the second temperature. Alternatively, when the fixing device 40 is located on the first end portion side with respect to the widthwise direction than the center position, the drive start temperature of the fan 44a may be kept at the first temperature and the drive start temperature of the fan 44b may be kept at the fourth temperature, which is lower than the second temperature. The same applies when the fixing device 40 is moved to the second end side.
In the present embodiment, the temperature change of at least one of the drive start temperatures of the fans 44a and 44b is made at the timing when the fixing device 40 is moved by the reciprocating mechanism 700. However, the timing for changing the temperature is not limited to this; for example, after the fixing device 40 is moved, the temperature of at least one of the areas on the first end side and the second end side of the fixing film 603 can be measured, and the driving start temperature can be changed according to that temperature. For example, when the temperature on the side where the fixing device 40 is moved is measured, the drive start temperature may be changed when the measured temperature drops below a certain temperature, and when the temperature on the opposite side where the fixing device 40 is moved is measured, the drive start temperature may be changed when the measured temperature rises above a certain temperature. Or, the driving start temperature may be changed when a certain number of sheets of recording material pass through the nip portion N after the fixing device 40 is moved.
In the present embodiment, by changing at least one of the temperatures at which the fan 44a starts driving and the temperature at which the fan 44b starts driving according to the position of the fixing device 40 in the widthwise direction, the drive timing and drive time of the fans 44a and 44b according to the position of the fixing device 40 in the widthwise direction can be changed. Therefore, even in a configuration where the fixing device 40 is moved back and forth, the temperature balance at the end of the fixing film 603 in the widthwise direction can be prevented from being out of balance.
For example, when the fixing device 40 moves to the first end portion, the drive start temperature of the fan 44a can be increased and the drive start temperature of the fan 44b can be decreased to delay the drive timing of the fan 44a from that of the fan 44b or to shorten the drive time of the fan 44a from that of the fan 44b. Therefore, the side that blows air by the fan 44a, which has a narrower area of a non-passing portion because the fixing device 40 moves, can be suppressed from being excessively cooled, while the side that blows air by the fan 44b, which has a wider area of a non-passing portion, can be efficiently cooled.
The flowchart in
In each of the above embodiments, a configuration using a fixing film, which is a film-like member, as the fixing belt is described, but the belt may be, for example, a belt with an elastic layer or surface layer on a resin layer base. The fixing unit may also have a configuration in which the fixing belt is tensioned by a plurality of tensioning members. Furthermore, the nip portion forming member may be a belt in addition to a roller, and it is preferred that it be a rotatable member.
Furthermore, the reciprocating mechanism 700 can move the fixing device 40 and the cooling mechanism 800 back and forth, and the fixing device 40 and the cooling mechanism 800 can be integrated into a single structure. In accordance with the above embodiments, there is no need to consider the amount of movement of the fixing device 40 by the reciprocating mechanism 700, and cooling can be performed corresponding to the non-passing area.
In addition, the structures corresponding to the above-mentioned disclosure of the embodiments will be stated in the following:
An image forming apparatus comprising:
An image forming apparatus according to Structure 1, wherein the control portion changes the air flow of the first air blowing portion to a first air flow and the air flow of the second air blowing portion to a second air flow in a case in which the fixing device is positioned in a central position with respect to the widthwise direction, and changes the air flow of the first air blowing portion to a third air flow smaller than the first air flow and the air flow of the second air blowing portion to a fourth air flow larger than the second air flow in a case in which the fixing device is positioned in a position on the first end side from the central position with respect to the widthwise direction.
An image forming apparatus according to Structure 2, wherein the control portion changes the air flow of the first air blowing portion to the third air flow and the air flow of the air blowing portion to the fourth air flow in a case in which the fixing device is positioned in a first position on the first end side from the central position with respect to the widthwise direction, and changes the air flow of the first air blowing portion to a fifth air flow smaller than the third air flow and the air flow of the second air blowing portion to a sixth air flow larger than the fourth air flow in a case in which the fixing device is positioned in a second position on the first end side from the first position with respect to the widthwise direction.
An image forming apparatus according to any one of Structures 1 to 3, wherein the control portion changes at least one of the air flow of the first air blowing portion and the air flow of the second air blowing portion at a timing when the fixing device.is moved by the reciprocating portion.
An image forming apparatus according to any one of Structures 1 to 4, wherein the control portion controls the reciprocating portion so that the fixing device is moved each time when a predetermined number of the recording materials pass through the.nip portion.
An image forming apparatus according to any one of Structure 1 to 5, wherein the fixing device includes a temperature detecting portion configured to detect a temperature of the first rotatable member on an end side from the central portion with respect to the widthwise direction, and
An image forming apparatus comprising:
An image forming apparatus according to Structure 7, wherein the opening width of the first duct formed by the first shutter is defined as an opening width of the first shutter and the opening width of the second duct formed by the second shutter is defined as an opening width of the second shutter, and
An image forming apparatus according to Structure 8, wherein the control portion changes the opening width of the first shutter to the third opening width and the opening width of the second shutter to the fourth opening width in a case in which the fixing device is positioned in a first position on the first end side from the central position with respect to the widthwise direction, and changes the opening width of the first shutter to a fifth opening width narrower than the third opening width and the opening width of the second shutter to a sixth opening width wider than the fourth opening width in a case in which the fixing device is positioned in a second position on the first end side from the first position with respect to the widthwise direction.
An image forming apparatus according to any one of Structures 7 to 9, wherein the control portion changes at least one of the opening width of the first shutter and the opening width of the second shutter at a timing when the fixing device.is moved by the reciprocating portion.
An image forming apparatus according to any one of Structures 7 to 10, wherein the control portion controls the reciprocating portion so that the fixing device is moved each time when a predetermined number of the recording materials pass through the nip portion.
An image forming apparatus according to any one of Structures 7 to 11, wherein the fixing device includes a temperature detecting portion configured to detect a temperature of the first rotatable member on an end side from the central portion with respect to the widthwise direction, and
An image forming apparatus comprising:
An image forming apparatus according to Structure 13, wherein the control portion changes the temperature at which the first air blowing portion starts the driving to a first temperature and the temperature at which the second air blowing portion starts the driving to a second temperature in a case in which the fixing device is positioned in a central position with respect to the widthwise direction, and changes the temperature at which the first air blowing portion starts the driving to a third temperature higher than the first temperature and the temperature at which the second air blowing portion starts the driving to a fourth temperature lower than the third temperature in a case in which the fixing device is positioned in a position on the first end side from the central position with respect to the widthwise direction.
An image forming apparatus according to Structure 13 or 14, wherein the control portion changes at least one temperature of the temperature at which the first air blowing portion starts the driving and the temperature at which the second air blowing portion starts the driving at a timing when the fixing device.is moved by the reciprocating portion.
An image forming apparatus according to any one of Structures 13 to 15, wherein the control portion controls the reciprocating portion so that the fixing device is moved each time when a predetermined number of the recording materials pass through the nip portion.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2022-134972 filed on Aug. 26, 2022, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-134972 | Aug 2022 | JP | national |
