JP6929693B2 - Image forming device - Google Patents

Description

The present invention relates to a life determination of a fixing member in an image forming apparatus and a fixing apparatus used therein. This image forming apparatus forms a developer image (toner image) on a recording material by using an image forming process such as an electrophotographic process, an electrostatic recording process, or a magnetic recording process. For example, copiers, printers (laser beam printers, LED printers, etc.), facsimiles, multi-function machines thereof, word processors, and the like are included.

Conventionally, as a fixing device, a configuration that realizes heating / pressurization by using a heating / pressurizing member that is in contact with and fixed to the inside of a rotating belt body is known. Here, if a fixed heating member or pressurizing member is provided inside the rotating belt body, a sliding load is generated and the driving of the rotating belt body is increased. Therefore, in order to reduce the sliding load inside the rotating belt body. Lubricating material such as oil is applied to the belt. When the lubricating material inside the rotating belt body decreases or deteriorates over the diameter, such a fixing device increases the drive load and causes image defects, paper wrinkles, paper jams, etc. due to poor rotation of the rotating belt body. It will be connected.

Therefore, in order to maintain the performance of the image forming apparatus, it is necessary to periodically replace the rotating belt body, the sliding member, and the like before the load of the sliding member exceeds a certain level.

Conventionally, as a guideline for replacing consumable members not only for fixing devices but also for image forming devices, the cumulative number of recording materials (number of sheets to be passed) for which image formation has been performed has been considered, and the cumulative number of sheets is set to a predetermined value. When it comes to it, it is common to encourage replacement.

Further, it has been proposed to specify a function including the detected drive current value and use it for determining the life of the oil supply member as the fixing member by referring to the defining function of the number of sheets to be passed and the drive current value (Patent Document 1). ).

Japanese Unexamined Patent Publication No. 2008-083091

However, Patent Document 1 does not support forward rotation and backward rotation as described below, and has diversified the usage of copiers in recent years (for example, printing a small number of sheets as used in an office environment and commerce). It does not support continuous printing of thousands of sheets as used in printing).

That is, in the forward rotation and the backward rotation performed before and after the print job, the cumulative number of recording materials (number of sheets to be passed) does not increase, but the fixing device is in the same state as the recording material is fixed. .. That is, the amount of lubricating material used inside the belt body of the fixing device is reduced, and the deterioration of the fixing device progresses.

Since the forward rotation and the backward rotation are always performed before and after the continuous printing operation, when the printing operation operates on a small number of sheets, the front rotation and the backward rotation time are about the same as those of the printing operation. Therefore, it greatly affects the life of the fixing device. On the contrary, if the number of printed sheets increases, the influence of the forward rotation and the backward rotation on the life of the fixing device can be almost ignored. In this way, when the average number of prints is significantly different, the judgment accuracy varies depending on the average number of prints even if the correct life is determined (the life judgment accuracy deteriorates as the average number of prints decreases). go).

Here, as a result of diligent studies, the present inventor has recognized that simply this alone does not necessarily lead to a correct life determination on the premise that the life of the fixing member is determined based on the mileage or the mileage.

An object of the present invention, by correcting the distance traveled by the magnitude of the torque value of the motor to provide a stable image forming equipment which the life associated with the driving load increases of the endless belt can be determined accurately.

In order to achieve the above object, the image forming apparatus according to the present invention heats an image forming portion for forming a toner image on a recording material and a toner image formed on the recording material by the image forming portion at a nip portion. A drive rotating body that forms the nip portion between the endless belt and the endless belt and rotationally drives the endless belt, and a pad that presses the endless belt from its inner surface toward the driving rotating body. , The motor that drives the drive rotating body, the torque detection unit that detects the torque value of the motor, the calculation unit that calculates the mileage of the endless belt, and the heating operation that heats the toner image on the recording material. A correction unit that corrects the mileage of the endless belt by weighting according to the torque detected by the torque detection unit inside, and a correction unit that corrects the mileage corrected by the correction unit, and notifies the life of the endless belt based on the mileage corrected by the correction unit. It is characterized by having a notification unit and a notification unit.

Further, the image forming apparatus according to the present invention includes an image forming portion that forms a toner image on the recording material, an endless belt that heats the toner image formed on the recording material by the image forming portion at the nip portion, and the endless portion. A drive rotating body that forms the nip portion with the belt and rotationally drives the endless belt, a heater that comes into contact with the inner surface of the endless belt and presses against the driving rotating body, and the driving rotating body. The driving motor, the torque detection unit that detects the torque value of the motor, the calculation unit that calculates the mileage of the endless belt, and the torque detection unit that heats the toner image on the recording material during the heating operation. It has a correction unit that corrects the mileage of the endless belt by weighting according to the torque detected by the correction unit, and a notification unit that notifies the life of the endless belt based on the mileage corrected by the correction unit. It is characterized by that.

According to the present invention, by correcting the distance traveled by the magnitude of the torque value of the motor, stable life due to drive load increase of the endless belt can be accurately determined.

Schematic cross-sectional view of the fixing device according to the embodiment of the present invention Operation flowchart of the fixing device according to the embodiment of the present invention A graph showing the average number of prints and the total mileage when passing a predetermined number of sheets Graph showing torque change due to mileage of multiple fixing devices (A) is a graph showing the mileage and life display of the fixing device according to the comparative example, and (b) is a graph showing the mileage and life display of the fixing device according to the embodiment of the present invention. Schematic cross-sectional view of an image forming apparatus equipped with the fixing apparatus according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

<< First Embodiment >>
(Image forming device)
FIG. 6 is a cross-sectional view of a color electrophotographic printer which is an example of an image forming apparatus equipped with a fixing device according to an embodiment of the present invention, and is a cross-sectional view taken along a sheet conveying direction. In this embodiment, the color electrophotographic printer is simply referred to as a "printer".

The printer shown in FIG. 6 includes an image forming unit 10 of each color of Y (yellow), M (magenta), C (cyan), and Bk (black). The photosensitive drum 11 is precharged by the charger 12. After that, the photosensitive drum 11 is formed with a latent image by the laser scanner 13. The latent image becomes a toner image by the developer 14. The toner image of the photosensitive drum 11 is sequentially transferred by the primary transfer blade 17 to, for example, an intermediate transfer belt 31 which is an image carrier. After the transfer, the toner remaining on the photosensitive drum 11 is removed by the cleaner 15. As a result, the surface of the photosensitive drum 11 becomes clean and ready for the next image formation.

On the other hand, the sheets P are sent out one by one from the paper feed cassette 20 or the multi-paper feed tray 25, and are sent to the resist roller pair 23. The resist roller pair 23 once receives the sheet P, and if the sheet is skewed, straightens it. Then, the resist roller pair 23 feeds the sheet between the intermediate transfer belt 31 and the secondary transfer roller 35 in synchronization with the toner image on the intermediate transfer belt 31.

The color toner image on the intermediate transfer belt is transferred to the sheet P by a transfer body, for example, a secondary transfer roller 35. After that, the toner image of the sheet is fixed to the sheet by heating and pressurizing the sheet by the fixing device 40.

(Fixing device)
FIG. 1 is a schematic cross-sectional view of a fixing device according to an embodiment of the present invention. Here, with respect to the fixing member in the present fixing device, the longitudinal direction is a direction orthogonal to the transport direction of the recording material and the thickness direction of the recording material. In FIG. 1, the fixing belt (endless belt, endless belt) 101 is a belt body in which a metal such as SUS or a resin such as polyimide is used as a base layer, silicone rubber is arranged on the base layer, and a PFA resin tube is further arranged on the base layer.

A drive rotating body that rotationally drives the fixing belt 101. Further, the pressurizing roller 102 as a pressurizing member forms a fixing nip portion (nip portion) that sandwiches and conveys a recording material (recording paper) carrying an image together with the fixing belt 101 as an opposing body facing the fixing belt 101. .. The pressure roller 102 has a multi-layer structure in which an elastic layer of silicone rubber is laminated on a metal core metal, and a PFA resin tube is sequentially laminated on the elastic layer.

Reference numeral 103 denotes a ceramic heater (heater) as a pressing member and a heating element (heating element), which is fixed to the lower surface of the heater holder 103 which also serves as a guide member for the fixing belt 101 having heat resistance. The ceramic heater 10 3 has a 10μm about resistance heater that created laden conductive paste of silver or palladium alloy on the alumina substrate by a screen printing method. Further, the surface of the resistance heating layer is protected by glass coating with pressure resistant glass.

The heater holder 104 is made of a liquid crystal polymer having high heat resistance, and also plays a role of regulating the trajectory of the fixing belt 101. Both ends of the core metal of the pressure roller 102 in the longitudinal direction are rotatably held by bearings by a fixing device frame (not shown). A heater holder 104 to which a ceramic heater 103 is fixed is urged at a total pressure of 300 N by a pressurizing mechanism (not shown) via a fixing belt 1 on the upper side of the pressurizing roller 102.

The pressure roller 102 is rotationally driven in the direction of the arrow at a predetermined peripheral speed by a drive motor 111 as a drive unit. Then, the fixing belt 101 is driven and rotated by the pressure roller 102 that is in pressure contact. At this time, the inner surface of the fixing belt 101 is in close contact with the ceramic heater 103 and the heater holder 104 and slides. A semi-solid lubricant (for example, fluorine grease) may be applied to the inner surface of the fixing belt 1 to ensure slidability.

The control unit 114 controls the energization of the ceramic heater 103 and controls the rotation of the drive motor 111 in order to control the temperature of the fixing belt 101 with a temperature detecting element (not shown).

In the present embodiment, the drive torque detection as a second acquisition unit that detects the drive torque of the drive motor 111 together with the control unit 114 as the first acquisition unit that acquires the mileage of the fixing belt 101 or the pressure roller 102. Means 112 are arranged. Then, as described in detail below, the control unit 114 as the determination unit corrects the acquisition result of the mileage (cumulative mileage) based on the acquisition result of the torque value of the drive unit (weighting coefficient (correction) corresponding to the torque value). Multiply the coefficient) to determine the life of the fixing member as the drive load increases.

(Control of fixing device)
FIG. 2 shows an operation flowchart of the fixing device for determining the life of the fixing member due to an increase in the driving load of the fixing member in the present embodiment. When the printing operation is started by the image forming apparatus (S101), the fixing apparatus refers to the information such as the paper type information required for the printing operation and the number of printed sheets (S102), and starts the forward rotation operation (S103). Here, the forward rotation means fixing in the preparation period for shifting from the state in which the image forming apparatus is in the standby state (the fixing device is in the low temperature, low pressure, low speed state) to the operating state (the fixing device is in the high temperature, high pressure, high speed state). This is the rotational movement of the member.

In the print standby state before S101, the fixing device stands by in a state where the fixing belt 1 is rotated at a low speed of about 30 mm / sec at a low temperature of, for example, about 150 ° C. in order to save energy and avoid wear of the fixing device. .. The front rotation is a step in which the fixing device heats and accelerates from this state to the optimum state of the fixing belt 1 corresponding to the basis weight and surface state of the recording material P, for example, 170 ° C. and 350 mm / sec.

The recording material P to which the toner image T was transferred was sandwiched and conveyed between the fixing belt 101 and the pressure roller 102 (nip portion) while the fixing device was sufficiently heated, so that the recording material P was formed in the image forming portion. The toner image T as an image is fixed to the recording material P by heat pressure. In S104, when a predetermined number of recording materials P pass through the fixing device and the fixing operation is completed, the fixing device returns the temperature and rotation speed of the fixing belt 1 to the standby state as a post-rotation process (S105). Here, the rear rotation is a rotation operation of the fixing member during a period for the fixing device to return from the operating state to the standby state, which is the opposite of the front rotation.

Although the details will be described later, the mileage calculation process (S106 to S108) related to the life determination is performed, and the printing operation is terminated (S109).

(Effect on life due to increase in driving load of fixing member in front rotation and rear rotation)
During fixing device operation, since the fixing belt 101 and the ceramic heater 103 and the heater holder 104 is rubbed, the fluorine grease is reduced and degraded by the high temperature high speed operation during the printing operation, the load on the driving motor 11 1 is gradually Increase to. The reason why the fluorine grease decreases at high temperature and high speed operation is that the viscosity of the fluorine grease decreases at high temperature and the circulation of fluorine grease increases at high speed drive, so that the fluorine grease leaks to the outside from the longitudinal end of the fixing belt 101. Etc. may be the cause.

In addition, when the fluorine grease becomes hot, the low-molecular-weight fluorine oil component volatilizes and is lost, resulting in deterioration of performance. Further, when the fluorine grease disappears and is completely deteriorated, the ceramic heater 103 and the heater holder 104 that slide with the fixing belt 101 are greatly worn, and the driving load of the fixing belt 101 suddenly increases and cannot be driven. Therefore, it is necessary to maintain the drive load of the fixing device at a predetermined value or less by periodically replacing the fixing belt 101 or reapplying the fluorine grease.

In considering the reduction and deterioration of the fluorine grease which causes sliding load increase of the fixing belt 101, the distance which the fixing belt 101 by the pre-rotation and post-rotation is driven (travel distance) greatly influences the life. The reason is that the amount of fluorine grease applied to the inner surface of the fixing belt 101 is reduced and deteriorated in the front rotation and the rear rotation, although it is not counted in the number of printed sheets. Here, Table 1 shows the breakdown of the printing operation time for each average number of printed sheets in the present embodiment. In Table 1, it is assumed that the front rotation time is 2.8 sec and the rear rotation time is 2.5 sec.

As can be seen from Table 1, the fixing operation time increases in proportion to the number of prints, but since the front rotation time and the back rotation time are constant regardless of the number of prints, the fixing operation time occupies the print operation time depending on the number of prints. (Print operation ratio) is significantly different. Further, it is empirically known that the weight reduction and the deterioration at the time of diameter of the fluorine grease generally deteriorate as the mileage increases.

Tables 2 and 3 show the mileage of the fixing belt 1 when the average number of printed sheets is changed when the number of printed sheets is aligned to 50. From this result, it can be seen that even if the cumulative number of prints is the same, the mileage differs greatly when the average number of prints changes.

Therefore, when predicting the life due to the increase in the sliding load of the fixing belt 1, the cumulative number of prints (cumulative number of sheets to be passed) as in the conventional example (Patent Document 1) is not used, but the cumulative running assumed in the present embodiment. It is better to use the distance (additional amount of mileage).

(Mileage correction by driving torque detection)
Next, as a prediction of the life of a fixing member fixing belt 10 1 are due to the wear by friction inner surface sliding (judging), the cumulative traveling distance (mileage using the value of the driving torque detecting means 1 12 of the present embodiment The correction of the addition amount) will be described. Generally, since the image forming apparatus is mass-produced, tolerances such as parts and assembly adjustment values are set. Therefore, the fixing device in each image forming device affects the rubbing wear of the fixing belt 101 such as the contact pressure between the fixing belt 101 and the pressure roller 102 and the amount of fluorine grease applied to the inner surface of the fixing belt 102. Is difficult to keep constant.

Therefore, there are variations in how far each fixing device can be used. FIG. 4 shows the transition of the drive torque when three types of fixing devices having variations in mileage are driven to the drive limit of the drive motor 111. When the value of the mileage (cumulative mileage (mileage addition amount)) increases and approaches the drive limit, the drive torque suddenly increases (increases).

It can be seen that the device that cannot be driven with a short mileage shown by the alternate long and short dash line (high contact pressure and small amount of grease) has a shorter life than the average device shown by the solid line. On the contrary, it can be seen that the device (low contact pressure and large amount of grease) capable of driving a long mileage shown by the broken line has a long life.

Therefore, as in the comparative example shown in FIG. 5A, when the life of the fixing device is set only by the mileage (cumulative mileage), a failure occurs before the life (about 70% of the assumed mileage). (Transition of alternate long and short dash line) In addition, when the notification unit notifies the life (at the time of life notification, at the time of life display), it may be replaced even if there is spare capacity (maintenance such as replacement is performed before the life) (transition of broken line). .. Therefore, in the comparative example shown in FIG. 5A, the accuracy of the life determination varies, and it is insufficient to stably and correctly determine the life.

On the other hand, in the present embodiment, the heat generated by the endless belt or the inner surface of the endless belt is rubbed based on the mileage obtained by acquiring the torque value of the drive unit and being corrected so as to increase or decrease according to the increase or decrease from the reference value. The life of the rubbing body (heater 103, heater holder 104) including the body is determined. Then, the notification unit notifies (displays) the life. Here, the rubbing body presses the fixing belt as a pad from the inner surface thereof toward the pressure roller as the drive rotating body.

Regarding the life determination, more specifically, according to the flowcharts (S106, S107) of FIG. 2, the mileage addition amount (cumulative mileage) obtained by adding the mileage for each printing operation and the weighting coefficient (correction coefficient) are shown. The coefficient shown in 3 is integrated (multiplied). The fixing device shown in FIG. 5 (b) according to the present embodiment is the same as the fixing device of three types (estimated life, short life, and high life) shown in FIG. Here, as shown by the solid line in FIG. 5 (b) showing the life transition until the fixing device reaches the specified mileage, when the detection torque is a standard value, the mileage (cumulative mileage) x The life display y (%) with respect to is expressed as y = f (x).

When the detection torque is larger than the standard value, the life display y (%) with respect to the mileage (cumulative mileage) x is set to, for example, y = f (x) / (1-g (x)), and the detection torque is set. Is expressed as a larger value than when is a standard value (one-dot chain line in FIG. 5 (b)). On the contrary, when the detection torque is smaller than the standard value, the life display y (%) with respect to the mileage (cumulative mileage) x is set to, for example, y = f (x) * (1-g (x)). When the detection torque is a standard value, it is notified as a small value (broken line in FIG. 5B).

In such an embodiment, both the short-life fixing device shown by the alternate long and short dash line and the long-life fixing device shown by the broken line can reach the life within a certain assumed life (mileage corrected and added by the detection torque). I understand. Therefore, maintenance of the fixing device such as replacement of the fixing belt 1 and recoating of fluorine grease can be performed at an appropriate timing.

Regarding increasing the weighting coefficient (correction coefficient) as the detection torque increases, the detection torque includes the contact pressure between the fixing belt 101 and the ceramic heater 103 and the fluorine-based grease applied to the inner surface of the fixing belt 101. It is relevant that the reduction and deterioration are reflected. When the amount of fluorine-based grease is reduced and deterioration is accelerated, the sliding resistance on the inner surface of the fixing belt 101 increases and the detection torque increases. That is, it is considered that the increase in the detection torque generally indicates the degree of deterioration of the inner surface of the fixing belt 101, and it is necessary to increase the weighting coefficient (correction coefficient).

More specifically, in this embodiment, g (x) = 0.5 is adopted, and the weighting coefficient (correction coefficient) corresponding to the detection torque is shown in Table 3. In Table 3, in the comparative example, the correction coefficient was set to 1.0 and no correction was made regardless of the value of the detected torque. On the other hand, in the present embodiment, when the detection torque is larger than the standard value (greater than 150 mN ・ m and smaller than 170 mN ・ m) (170 mN ・ m or more), the correction coefficient is set to 2.0. When the detection torque is 150 mN · m or less, the correction coefficient is set to 0.5.

For the driving torque detecting means 112, for example, if the output torque of the driving motor 111 (driving torque) that is approximately proportional to the current value known in advance, the driving by detecting the current value of the drive motor 1 11 Mo the driving torque of over motor 1 11 may simply be acquired.

When to detect the drive torque is basically during the fixing operation, but if the same nip pressure as the nip pressure during the fixing operation (pressure at the fixing nip) is guaranteed, during forward rotation and backward rotation. , During non-fixing operation such as assembly (other than fixing operation).

As described above, for the prediction (judgment) of the life due to the increase in the drive load of the image forming apparatus, it is possible to use the value obtained by integrating (multiplying) the weighting coefficient (correction coefficient) according to the detection torque value of the drive unit and the cumulative mileage. It was shown to be preferable.

(Modification example)
Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and modifications can be made within the scope of the gist thereof.

(Modification example 1)
In the above-described embodiment, the mileage (cumulative mileage) is used, but since the mileage is the product of the mileage and the mileage, the mileage (cumulative mileage) can be used instead of the mileage. Then, the life can be determined by integrating (multiplying) the weighting coefficient (correction coefficient) according to the value of the detection torque of the drive unit and the traveling time (cumulative traveling time).

(Modification 2)
In the above-described embodiment, in a fixing device in which the nip portion is heated by a heater that rubs against the inner surface of the endless belt by the rotation of the endless belt, the accuracy of determining the life of the endless belt as a fixing member or the heater can be improved. rice field. The present invention is not limited to this, and in a landing device in which an endless belt rubbed by rotation generates heat by an exciting coil or constantly generates heat by energizing a heat generating layer, the endless belt as a fixing member and its inner surface slide. It is possible to improve the accuracy of determining the life of the rubbing body to be rubbed.

(Modification example 3)
In the above-described embodiment, 0.5 or 2.0 is used as a constant in the region shown in Table 3 regarding the correction of the cumulative mileage according to the detected torque value of the drive unit, but the values of other constants are used. You may use it. Further, in the above-mentioned detection torque region, a variable (a variable such that the corrected cumulative mileage value increases as the detection torque increases) may be used instead of the constant. As described above, the present invention is not limited to the three levels of correction values exemplified, and it is possible to select and adapt an arbitrary number of correction levels and correction amounts according to the configuration and set values of the image forming apparatus. It is possible.

(Modification example 4)
In the above-described embodiment, the pressure roller is used as the pressurizing body facing the endless belt as the rotating body, but the pressurizing roller may be replaced with the endless belt.

Then, in the above-described embodiment, the case where the rotating body and the rotating body for pressurizing as the pressurizing body pressurize the fixed rotating body is shown. However, the present invention is not limited to this, and can be similarly applied to the case where a rotating body as an opposing body is pressurized from a fixed rotating body instead of as a pressurized body.

(Modification 5)
In the above-described embodiment, the recording paper has been described as the recording material, but the recording material in the present invention is not limited to paper. Generally, a recording material is a sheet-like member on which a toner image is formed by an image forming apparatus. Glossy paper and the like are included. In the above-described embodiment, the handling of the recording material (sheet) P has been described using terms such as paper feeding for convenience, but the recording material in the present invention is not limited to paper.

(Modification 6)
In the above-described embodiment, the fixing device for fixing the unfixed toner image to the sheet has been described as an example, but the present invention is not limited to this, and the toner image assumed to be attached to the sheet is used in order to improve the gloss of the image. It can also be applied to a device for heating and pressurizing (also referred to as a fixing device in this case).

101 ... Fixing belt (endless belt), 102 ... Pressurizing roller (opposite body), 103 ... Ceramic heater, 111 ... Drive motor, 112 ... Torque detection means, 114 ... Control unit, P ... Recording Material, T ... toner image (image)

Claims (3)

An image forming part that forms a toner image on the recording material,
An endless belt that heats the toner image formed on the recording material by the image forming portion at the nip portion, and
A drive rotating body that forms the nip portion with the endless belt and rotationally drives the endless belt,
A pad that presses the endless belt from its inner surface toward the drive rotating body, and
The motor that drives the drive rotating body and
A torque detector that detects the torque value of the motor and
A calculation unit that calculates the mileage of the endless belt,
A correction unit that corrects the mileage of the endless belt by weighting according to the torque detected by the torque detection unit during the heating operation that heats the toner image on the recording material.
A notification unit that notifies the life of the endless belt based on the mileage corrected by the correction unit, and a notification unit.
An image forming apparatus characterized by having. An image forming part that forms a toner image on the recording material,
An endless belt that heats the toner image formed on the recording material by the image forming portion at the nip portion, and
A drive rotating body that forms the nip portion with the endless belt and rotationally drives the endless belt.
A heater that comes into contact with the inner surface of the endless belt and presses it toward the drive rotating body.
The motor that drives the drive rotating body and
A torque detector that detects the torque value of the motor and
A calculation unit that calculates the mileage of the endless belt,
A correction unit that corrects the mileage of the endless belt by weighting according to the torque detected by the torque detection unit during the heating operation that heats the toner image on the recording material.
A notification unit that notifies the life of the endless belt based on the mileage corrected by the correction unit, and a notification unit.
An image forming apparatus characterized by having. The image forming apparatus according to claim 1 or 2, wherein the drive rotating body is a pressure roller.

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