JP2018018045A - Fixation device and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable replenishment of a lubricant as needed, prevent a rising of torque or falling of oscillatability arising from a shortage of the lubricant, and can prevent an adverse effect due to the excessive replenishment of the lubricant.SOLUTION: A fixation device comprises: an endless belt-like fixation member 1; a heat source 2; a pressure member 3; a nip formation member 6 that forms a nip part N; a reinforcement member 7 that supports the nip formation member 6 against force to be applied to the nip formation member 6 from the pressure member 3; an oscillation member 80 that is dispose between the fixation member 1 and the nip formation member 6; and a lubricant holding member 5 that holds a lubricant to be coated on an inner peripheral face of the fixation member 1, in which non-fixation toner on a recording medium passing through the nip part N is fixed by heating the non-fixation toner thereon. The nip formation part 6 has a liquid chamber 81 inside that serves as a flow path of the lubricant to be supplied to the oscillation member 80, and further comprises: oscillatability detection means 86 that detects an oscillation state between the fixation member 1 and the oscillation member 80; and lubricant replenishment means that supplies the lubricant to the liquid chamber 81.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a fixing device and an image forming apparatus.

  In recent years, market demands for energy saving and high speed have been increasing for image forming apparatuses such as printers, copiers, and facsimiles. In an image forming apparatus, an unfixed toner image is transferred to a recording material (for example, a recording material sheet, printing paper, photosensitive paper, static paper, or the like by an image transfer method or a direct method by an image forming process such as electrophotographic recording, electrostatic recording, or magnetic recording. Electric recording paper or the like). As a fixing device for fixing an unfixed toner image, a belt-type fixing device using an endless fixing belt is known (for example, see Patent Document 1).

FIG. 12 shows a schematic diagram of the fixing device of Patent Document 1.
In the fixing device shown in FIG. 12, a pipe-shaped metal heat conductor 25 is fixed inside an endless belt (fixing member) 1 so that the movement of the endless belt 1 can be guided. The endless belt 1 is heated by the heat source 2 through the metal heat conductor 25. Further, a pressure roller (pressure member) 3 that forms a nip portion N in contact with the metal heat conductor 25 via the endless belt 1 is provided, and the endless belt 1 is rotated so as to rotate as the pressure roller 3 rotates. Is moved in the circumferential direction. In the drawing, D represents the conveyance direction of the recording material (paper).
With this configuration, it is possible to heat the entire endless belt, and shorten the first print time from the time of heating standby (the time it takes for printing to be completed after receiving a print request and printing is completed). It is possible to solve the shortage of heat during high-speed rotation.

  However, it is necessary to further improve the thermal efficiency in order to further save energy and improve the first print time. On the other hand, the structure which heats an endless belt directly without using a metal heat conductor is proposed. According to this configuration, power consumption can be reduced by significantly improving the heat transfer efficiency, and the first print time from the heating standby time can be further shortened. In addition, the cost can be reduced without using a metal heat conductor.

  In the configuration in which the endless belt is directly heated, the nip forming member is arranged in contact with the inner peripheral surface in the endless belt, and the pressure roller presses the endless belt against the nip forming member to form a nip portion with the endless belt. To do. In the configuration in which the inner surface of the endless belt slides while being pressed against the nip forming member by the pressure applied from the pressure roller, the driving load tends to increase and becomes particularly prominent over time.

  Therefore, a configuration has been proposed in which a member having excellent slidability is provided on the nip forming member and the sliding load is reduced by a lubricant such as oil or grease. However, parts wear and lubricant outflow over time are inevitable.

The cause of lubricant leakage is that the lubricant holding function is concentrated in the nip forming part that is pressed by the pressure roller. For example, most of the lubricant may be squeezed out at the time, and it may be difficult to seal with a follow-up sleeve configuration controlled to a high temperature.
When the lubricant starts to run out, the wear of parts gradually proceeds, leading to a shortened device life. In addition, there may be a case where a conveyance slip or a fixing unit driving motor lock occurs.

On the other hand, techniques for compensating for the shortage of lubricant have been proposed (see, for example, Patent Documents 2 to 4).
In Patent Document 2, attention is paid to the fact that the lubricant leaks in the end regions on both sides in the longitudinal direction of the sliding member, so that the holding capacity of the lubricant is larger in the end region than in the longitudinal center. The composition is described. Further, in Patent Document 3, it is noted that the lubricant leaks at the outlet portion of the nip portion in the sliding member, and the holding capacity of the lubricant is set to be larger at the outlet portion than at the inlet portion of the nip portion. The composition is described.
Further, Patent Document 4 describes that a tank for storing a lubricant is provided, and the lubricant is prevented from being exhausted by constantly supplying the lubricant to the sliding member.

  However, there may be an excessive amount of lubricant held by the sliding member by expanding the holding capacity of the lubricant in the sliding member or by constantly supplying the sliding member. If the amount of lubricant retained by the sliding member increases, the amount of lubricant that leaks also increases. The leaked large amount of lubricant may contaminate the internal and external components, the recording medium being conveyed, and the like.

  Accordingly, the present invention provides a fixing device that can replenish the lubricant in a timely manner, prevent an increase in torque and a decrease in slidability due to lack of the lubricant, and prevent adverse effects due to excessive replenishment of the lubricant. The purpose is to do.

  In order to achieve this object, a fixing device according to the present invention is provided with an endless belt-shaped fixing member, a heat source for heating the fixing member, a pressure member facing the fixing member, and an inside of the fixing member. A nip forming member that forms a nip portion facing the pressure member, a reinforcing member that supports the nip forming member against pressure applied from the pressure member to the nip forming member, and the fixing member. A sliding member disposed between the nip forming member and a lubricant holding member for holding a lubricant applied to an inner peripheral surface of the fixing member, and on a recording medium passing through the nip portion. In the fixing device that heats and fixes the unfixed toner, the nip forming member has a liquid chamber serving as a flow path for the lubricant supplied to the sliding member, and the sliding member and the sliding member Detects sliding state with members And the dynamic characteristic detection means, and a lubricant supply means for supplying a lubricant to said fluid chamber, a fixing device characterized by further comprising a.

  According to the present invention, there is provided a fixing device that can replenish lubricant in a timely manner, prevent an increase in torque and a decrease in slidability due to lack of lubricant, and prevent adverse effects due to excessive replenishment of lubricant. Can be provided.

1 is a schematic configuration diagram illustrating an example of a configuration of an image forming apparatus according to the present invention. 1 is a schematic configuration diagram illustrating an example of a fixing device to which the present invention is applied. 1 is a schematic configuration diagram illustrating an example of a fixing device to which the present invention is applied. 1 is a schematic configuration diagram illustrating an example of a fixing device to which the present invention is applied. It is explanatory drawing which shows an example of a light-shielding member. It is explanatory drawing which shows one Embodiment of operation | movement of a light-shielding member. 1 is a schematic configuration diagram showing an embodiment of a fixing device according to the present invention. 1 is a schematic top view of an embodiment of a fixing device according to the present invention. 1 is a schematic configuration diagram showing an embodiment of a fixing device according to the present invention. FIG. 4 is a schematic diagram illustrating lubricant supply in the fixing device according to the present invention. It is a schematic diagram which shows an example of a structure of a lubricant supply means. FIG. 10 is an explanatory diagram illustrating an example of a configuration of a conventional fixing device.

  Hereinafter, a fixing device and an image forming apparatus according to the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and other embodiments, additions, modifications, deletions, and the like can be changed within a range that can be conceived by those skilled in the art, and any aspect is possible. As long as the functions and effects of the present invention are exhibited, the scope of the present invention is included.

[Image forming apparatus]
FIG. 1 shows a schematic configuration diagram of an electrophotographic printer as an image forming apparatus provided with a fixing device according to the present invention.
A tandem structure is employed in the printer (image forming apparatus) 100 of the present embodiment illustrated in FIG. In this tandem structure, photosensitive drums 20Y, 20C, 20M, and 20Bk as image carriers are arranged in parallel. The image carrier can form an image as an image corresponding to each color separated into yellow, cyan, magenta, and black.

The printer (image forming apparatus) 100 forms an electrostatic latent image on each of the photosensitive drums 20Y, 20C, 20M, and 20Bk, develops each electrostatic latent image with each color toner, and visualizes it to form a toner image. To do. Subsequently, these toner images are transferred onto the intermediate transfer belt 11 serving as an intermediate transfer member in a superimposed manner (primary transfer), and then collectively transferred onto the recording sheet S serving as a recording medium (secondary transfer). Thereafter, the image is fixed on the recording paper S by the fixing device 10.
Details of the fixing device 10 according to the present invention will be described later.

  The endless intermediate transfer belt 11 is stretched between a driving roller 71 and a plurality of slave rollers 72 and 73, and can move in the direction of arrow A1 while facing each of the photosensitive drums 20Y, 20C, 20M, and 20Bk. is there. On the surface of the intermediate transfer belt 11, a cleaning device 74 that removes and removes foreign matters such as residual toner on the intermediate transfer belt 11 is provided.

Around each of the photosensitive drums 20Y, 20C, 20M, and 20Bk, members for image forming processing are arranged according to the rotation of the photosensitive drum. This will be described below by taking the photosensitive drum 20Bk for forming a black image as an example.
Around the photosensitive drum 20Bk, a charging device 30Bk, a developing device 40Bk, a primary transfer roller 12Bk, and a cleaning device 50Bk that perform image forming processing along the rotational direction of the photosensitive drum 20Bk are arranged. The optical writing device 18 is used for writing performed after charging.

In the superimposing transfer (primary transfer) to the intermediate transfer belt 11, each intermediate toner image formed on each of the photosensitive drums 20Y, 20C, 20M, and 20Bk is transferred to the intermediate transfer belt while the intermediate transfer belt 11 moves in the A1 direction. 11 is performed so as to be transferred to the same position.
Specifically, the toner images formed on the respective photosensitive drums 20Y, 20C, 20M, and 20Bk are applied from the upstream side to the downstream side in the A1 direction by voltage application by the primary transfer rollers 12Y, 12C, 12M, and 12Bk. This is done at different timings. The primary transfer rollers 12Y, 12C, 12M, and 12Bk are arranged to face the respective photosensitive drums 20Y, 20C, 20M, and 20Bk with the intermediate transfer belt 11 interposed therebetween.

  The secondary transfer roller 15 is a transfer member that is disposed to face the drive roller 71 and the intermediate transfer belt 11 so as to sandwich the drive roller 71 and the intermediate transfer belt 11.

The optical writing device 18 is disposed above the sheet feeding device 61 in the apparatus main body. The optical writing device 18 includes a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, a rotating polygon mirror as a deflecting unit, and the like.
The optical writing device 18 emits writing light corresponding to each color to each of the photosensitive drums 20Y, 20C, 20M, and 20Bk, and outputs an electrostatic latent image to each of the photosensitive drums 20Y, 20C, 20M, and 20Bk. Form.

  The sheet feeding device 61 includes a sheet feeding roller 13. The paper feed roller 13 contacts the upper surface of the uppermost recording paper S stacked in the paper feed cassette 62 during the paper feeding operation. Then, the sheet feeding device 61 feeds the uppermost recording sheet S toward the registration roller 14 when the sheet feeding roller 13 is driven to rotate counterclockwise.

  In addition, toner bottles 9Y, 9C, 9M, and 9Bk filled with yellow, cyan, magenta, and black toners are detachably disposed in the upper portion of the apparatus main body, and each color toner is developed. The devices 40Y, 40C, 40M, and 40Bk are supplied.

Next, an image forming operation by the printer 100 will be described.
The surfaces of the photosensitive drums 20Y, 20C, 20M, and 20Bk rotating in the direction of the arrow at a predetermined process speed are uniformly charged by the charging devices 30Y, 30C, 30M, and 30Bk. Then, an electrostatic latent image corresponding to image information input from, for example, an external personal computer is formed on the surface of the photosensitive drums 20Y, 20C, 20M, and 20Bk by exposure with laser light from the optical writing device 18.

  Then, development (visualization) is performed by attaching toner (developer) to the electrostatic latent images formed on the surfaces of the photosensitive drums 20Y, 20C, 20M, and 20Bk by the developing devices 40Y, 40C, 40M, and 40Bk. ) As a result, toner images of the respective colors are formed on the surfaces of the photosensitive drums 20Y, 20C, 20M, and 20Bk, and toners of the respective colors are further transferred onto the moving intermediate transfer belt 11 by the primary transfer rollers 12Y, 12C, 12M, and 12Bk. The image is superimposed and transferred.

  At this time, the uppermost recording sheet S is taken out from the sheet feeding cassette 62 by the sheet feeding roller 13, and the recording sheet S conveyed through the conveying path is temporarily held by the registration roller 14. Then, the recording sheet S held by the resist roller pair 14 is applied with the intermediate transfer belt 11 and the transfer bias in accordance with the toner image formation timing on the surfaces of the photosensitive drums 20Y, 20C, 20M, and 20Bk. The full color toner image is transferred onto the recording paper S by being conveyed to the transfer nip between the secondary transfer rollers 15.

  Then, the recording sheet S on which the toner image is transferred is conveyed to the fixing device 10 and heated and pressed at a fixing nip (nip portion) between the endless fixing belt 1 and the pressure roller 3 of the fixing device 10. As a result, the toner image is fixed on the recording paper S. The recording paper S on which the toner image is fixed is conveyed by the paper discharge roller 16 and discharged onto the paper discharge tray 17.

[Fixing device]
Examples of fixing devices to which the present invention can be applied are shown in FIGS.
The fixing device shown in FIG. 2 has an endless belt-like fixing member (hereinafter also referred to as “fixing belt”) 1 and a pressure member (hereinafter also referred to as “pressure roller”). 1 is a structure directly heated by radiant heat from the inner peripheral side.
In the fixing belt 1, there is a nip forming member 6 that forms a nip portion N with a pressure roller 3 that is opposed to the fixing belt 1, and slides indirectly with the inner surface of the fixing belt 1 through a sliding member. . The sliding member is a sheet-like member containing a liquid lubricant, and is for reducing the frictional resistance between the nip forming member 6 and the fixing belt 1.

  In the example of FIG. 2, the shape of the nip portion N is flat, but may be a concave shape or other shapes. By adopting the concave shape, the discharge direction of the leading edge of the recording paper S is closer to the pressure roller 3, so that the separability is improved and the occurrence of jam is suppressed.

  The fixing belt 1 is a metal belt such as nickel or SUS or an endless belt (or film) using a resin material such as polyimide. The surface layer of the belt has a release layer such as a PFA or PTFE layer, and has a release property so that toner does not adhere. There may be an elastic layer formed of a silicone rubber layer or the like between the belt substrate and the PFA or PTFE layer. When there is no silicone rubber layer, the heat capacity is reduced and the fixability is improved, but when the unfixed image is crushed and fixed, minute irregularities on the belt surface are transferred to the image, and the image has a crusty skin shape. There arises a problem that the gloss unevenness (zudder skin image) remains. In order to improve this, it is necessary to provide a silicone rubber layer with a thickness of 100 μm or more. Due to the deformation of the silicone rubber layer, fine irregularities are absorbed and the skin image is improved.

  Inside the fixing belt 1, a reinforcing member (hereinafter also referred to as “stay”) 7 for supporting the nip forming member 6 is provided. The stay 7 prevents the nip forming member 6 that receives pressure from the pressure roller 3 from bending. Thereby, a uniform nip width is obtained in the axial direction of the pressure roller 3. The stay 7 is held and fixed to a holding member (hereinafter also referred to as “flange”) 8 and positioned.

  A reflection member 9 is disposed between the heat source 2 and the stay 7. The reflective member 9 efficiently radiates heat from the heat source 2 to the inner surface of the fixing belt 1. In addition, the same effect is acquired even if it heat-insulates and the mirror surface process is performed to the surface facing the heat source 2 of the stay 7 instead of providing the reflection member 9. FIG.

  The heat source 2 may be a halogen heater as in the example shown in FIG. 2, but may be an IH, a resistance heating element, a carbon heater, or the like. Further, as shown in other examples described later, the number of halogen heaters constituting the heat source 2 is not limited.

  The pressure roller 3 includes a cored bar 3a and an elastic rubber layer 3b, and a release layer (PFA or PTFE layer) is provided on the surface in order to obtain releasability. The pressure roller 3 is rotated by a driving force transmitted from a driving source such as a motor provided in the image forming apparatus via a gear. Further, the pressure roller 3 is pressed against the fixing belt 1 by a lever 22 (see FIG. 7) having a spring 21, and the elastic rubber layer 3b is crushed and deformed so that a predetermined nip width is obtained. Have.

  The pressure roller 3 may be a hollow roller, and the pressure roller 3 may have a heating source such as a halogen heater. The elastic rubber layer 3b may be solid rubber, but when there is no heater inside the pressure roller 3, sponge rubber may be used. Sponge rubber is more desirable because it increases heat insulation and makes it difficult for the fixing belt 1 to lose heat.

  The fixing belt 1 rotates along with the pressure roller 3. In the example of FIG. 2, the pressure roller 3 is rotated by a driving source (not shown), and the driving force is transmitted through the nip portion N, whereby the fixing belt 1 is rotated. The fixing belt 1 is sandwiched and rotated at the nip portion N, and travels while being guided by the flange 8 at both ends except the nip portion.

  During the fixing operation, the fixing belt 1 is quickly heated by the heat generated by the heat source 2 and reaches a predetermined temperature. The recording sheet S on which the unfixed toner image conveyed to the nip N is transferred is heated and pressed while being nipped and conveyed between the fixing belt 1 and the pressure roller 3 in the nip N, and the toner image is fixed. Is done.

In the fixing device shown in FIG. 2, the heat source 2 is composed of one halogen heater, whereas in the fixing device shown in FIG. 3, the heat source 2 is composed of three halogen heaters.
In the fixing device of FIG. 3, since the light emission location is different for each heater constituting the heat source 2, a heater to be turned on according to the size of the recording paper S can be selected to ensure productivity.

The fixing device shown in FIG. 4 includes a light shielding member 4.
As shown in FIG. 5, the shape of the light shielding member 4 is a stepped shape in which a light shielding area corresponding to each paper width (W) is provided according to the size of the recording paper S. In FIG. 5, W1 indicates a postcard, W2 indicates a shape corresponding to a B4 size paper, and W3 indicates a shape corresponding to an A3 size paper.
As shown in FIG. 6, the light shielding member 4 is arranged so as to rotate without contact along the inner side of the fixing belt 1, and rotates to a position corresponding to each paper width to shield an area unnecessary for heating. To do. The upper part of FIG. 6 shows an overall perspective view, and the lower part shows a schematic cross-sectional view at a position indicated by an arrow. FIG. 6A is a diagram illustrating a case where an A3 size sheet is passed, and FIG. 6B is a diagram illustrating a case where a postcard is passed.

  By providing such a light shielding member 4, even when the recording paper S having a narrow paper width is continuously passed, the non-sheet passing area is not overheated, and production is performed to cancel the overheated area. There is no need to perform control that reduces performance. In addition, by providing the light shielding member 4, the number of halogen heaters as the heat source 2 can be reduced. In the fixing device of FIG. 4, the number of halogen heaters constituting the heat source 2 is two.

One embodiment of the fixing device according to the present invention is shown in FIG. FIG. 7A is a schematic sectional view in a cold state, and FIG. 7B is a schematic sectional view in a hot state.
The fixing device of this embodiment includes an endless belt-shaped fixing member (fixing belt) 1, a heat source 2 for heating the fixing member 1, a pressure member (pressure roller) 3 facing the fixing member 1, and a fixing member. 1 A nip forming member 6 that is disposed inside 1 and forms a nip portion N facing the pressure member 3, and a reinforcement that supports the nip forming member 6 against pressure applied from the pressure member 3 to the nip forming member 6. A member (stay) 7, a sliding member 80 disposed between the fixing member 1 and the nip forming member 6, and a lubricant holding member 5 that holds the lubricant applied to the inner peripheral surface of the fixing member 1. The unfixed toner on the recording medium (recording paper S) passing through the nip portion N is heated and fixed. The pressure member 3 is pressed against the fixing member by a lever 22 having a spring 21.
The nip forming member 6 has a liquid chamber 81 serving as a flow path for the lubricant supplied to the sliding member 80 inside.
Further, a slidability detecting means for detecting a sliding state between the fixing member 1 and the sliding member 80 and a lubricant replenishing means for supplying a lubricant to the liquid chamber 81 are further provided.

(Sliding member)
The sliding member 80 is provided on the surface that contacts the fixing belt 1 along the longitudinal direction of the nip forming member 6.
As a base material of the sliding member 80, a material excellent in wear resistance and heat resistance and having a small friction coefficient is preferable, and examples thereof include a fluorine-based fiber sheet. Specifically, the coefficient of dynamic friction is preferably 0.15 or less.
By forming the sliding member 80 with a mesh-like or porous material, a liquid lubricant (for example, silicone oil) can be contained.

By sufficiently holding the lubricant in the sliding member 80, it can be spread over the inner peripheral surface simultaneously with the rotation of the fixing belt 1. However, since a high pressure is applied to the nip portion N as described above, the lubricant is squeezed out at the initial stage of rotation. Further, since a high pressure is always applied to the sliding member 80, it is difficult to recover the leaked lubricant.
On the other hand, the fixing device of this embodiment includes a lubricant holding member 5.

(Lubricant holding member)
The lubricant holding member 5 is made of a material that expands or contracts as the temperature changes, and is disposed in contact with the stay 7. When the stay 7 exceeds a predetermined temperature, the lubricant holding member 5 expands and contacts the fixing belt 1. .

By providing the region other than the nip portion N with the function of retaining the lubricant, it is possible to improve the function of application and recovery of the lubricant and retention, and to significantly suppress the leakage of the lubricant. .
Further, in a state where a large amount of electric power is required immediately after the apparatus is started up, the toner is offset by increasing the power consumption or decreasing the surface temperature of the fixing belt 1 by not contacting the fixing belt 1. It does not cause image defects such as.

  When a member having a high heat capacity such as the stay 7 is at a high temperature, the entire fixing device is in a warm state, the viscosity of the lubricant is small, and the risk of the lubricant leaking increases. Under such circumstances, the swollen lubricant holding member 5 contacts the fixing belt 1.

In addition, the fixing device of the present embodiment includes a temperature detection unit 85 that detects the temperature of the fixing belt 1, and the lubricant holding member 5 is downstream of the nip forming member 6 in the rotation direction of the fixing belt and detects the temperature. It is preferable to be disposed upstream of the means 85.
Even if the lubricant holding member 5 is a member having excellent heat insulation properties, when it comes into contact with the fixing belt 1, a temperature difference is caused in the circumferential direction. Therefore, the accuracy of the temperature control of the fixing belt 1 can be maintained by arranging it so as to avoid the region between the temperature detection region related to the temperature control of the fixing belt 1 and the nip portion N.

The lubricant holding member 5 is preferably made of a porous material. The porous material includes a fiber braided sheet material. By using a porous material, it is possible to increase the lubricant retention ability and reduce the amount of heat transfer during contact. Moreover, it is preferable that it is a material which expand | swells with a temperature rise and consists of a material with a large heat capacity.
Examples of such a material include a porous sponge obtained by foaming a heat-resistant elastomer such as silicone rubber or fluorine rubber.

The lubricant holding member 5 is provided in contact with a stay 7 whose temperature rise is gentle compared to the fixing belt 1, and the positional relationship with respect to the fixing belt 1 is such that the fixing device itself is not warmed (startup). Immediately after that, or in a state in which several level print jobs enter intermittently at intervals (state shown in FIG. 7A).
On the other hand, during continuous printing jobs of several tens to several hundreds of sheets, the temperature of the stay 7 gradually increases due to the radiant heat of the heat source 2, and the lubricant holding member 5 expands as the temperature increases. By disposing the stay 7 so as to contact the fixing belt 1 when the temperature exceeds a certain temperature, the lubricant holding member 5 can apply and collect the lubricant in the hot state shown in FIG. Demonstrate the function.
After the end of the print job, the lubricant holding member 5 contracts as the temperature decreases, and is separated from the fixing belt 1 as shown in FIG.

  Since the stay 7 has a large heat capacity, it is unlikely that the lubricant holding member 5 expands excessively due to an excessive temperature rise and the fixing belt 1 is compressed. Further, the surface that is in sliding contact with the inner surface of the fixing belt 1 may be coated with fluorine or the like in order to suppress wear of the lubricant holding member 5 itself.

FIG. 8 is a schematic diagram showing a state (inside the fixing belt 1) of the fixing device according to the present embodiment as viewed from above. Only the end of the fixing belt 1 is shown.
The lubricant holding member 5 preferably has a length L1 in the axial direction of the fixing belt 1 shorter than a length L2 of the nip portion N.

In the flow path of the lubricant from the sliding member 80, the lubricant squeezed out by the pressure in the nip portion N is dammed by the upstream side surface of the nip portion N and the inner surface of the fixing belt 1, and the width direction line of the damming portion remains as it is. It forms a flow path and is formed by being transmitted from the end portion in the width direction of the nip portion N to the flange 8 that supports the end portion of the fixing belt 1.
The fixing device of the present embodiment is configured to suppress leakage due to excessive application of the lubricant, but the length L1 (width to which the lubricant is applied) of the lubricant holding member 5 is set to the nip portion N. Outflow can be suppressed more effectively by being narrower than the length L2 and narrowing toward the center.

According to the fixing device of this embodiment, it is possible to prevent an early torque increase due to the leakage of the lubricant.
If the frequency of print jobs is high when the fixing device is not warmed sufficiently, the viscosity of the lubricant is relatively high and the possibility of leakage is low, but heating is performed until a constant torque is reached. You may add the function to perform internal control which performs idling. Torque confirmation can be determined from the current value of the drive motor, and a mode for executing torque confirmation at predetermined intervals may be mounted.

(Lubricant replenishment means)
The lubricant replenishing means will be described based on FIGS.
As shown in FIG. 9, the fixing device of the present embodiment has a liquid chamber 81 serving as a flow path for the lubricant supplied to the sliding member 80 inside the nip forming member 6. The lubricant is supplied from the liquid chamber 81 to the sliding member 80. However, if the lubricant is constantly supplied, the supply is excessive. Therefore, in the fixing device of this embodiment, a necessary amount of lubricant is supplied in a timely manner.

FIG. 10A is a cross-sectional view along the longitudinal direction around the nip portion N. FIG. A plurality of minute holes are provided on the surface of the liquid chamber 81 facing the sliding member 80. A supply path 93 is connected to the end of the liquid chamber 81, and the supply path 93 is connected to the lubricant supply means 90.
It is preferable that the lubricant sent from the supply path 93 does not cause excessive supply in the liquid chamber 81 (no variation). Therefore, for example, as shown in FIG. 10B, a member or the like that divides the liquid chamber 81 can be provided so that a plurality of supply paths are formed, and the lubricant can be distributed throughout the liquid chamber 81. .
In FIG. 10B, the member 93a for dividing the flow of the lubricant from the supply passage 93 into three parts and sending the lubricant to the center region and both side end regions in the width direction of the liquid chamber 81, Although the example which provided 93b is shown, the number and arrangement | positioning of a member are not limited to this.

  FIG. 11 is a schematic diagram showing an example of the lubricant replenishing means 90. The lubricant supply unit 90 stores the lubricant F according to the detection result of the storage unit 91 that stores the lubricant F, the supply path 93 that supplies the lubricant F from the storage unit 91 to the liquid chamber 81, and the slidability detection unit 86. Supply control means 92 for controlling the supply of lubricant from the section 91.

  The supply control unit 92 is not particularly limited as long as it can control the outflow of a small amount of lubricant in accordance with a signal from the slidability detection unit 86, and a known dispenser or the like can be applied.

(Slidability detection means)
As the slidability detecting means 86, means for detecting the sound pressure of the frictional sound generated in the nip portion N (sound pressure detecting means 86b in FIG. 10), means for detecting the vibration of the surface of the fixing belt 1 (in FIG. 9). And vibration detecting means 86a).

(1) Sound pressure detecting means The frictional sound generated at the nip portion N is caused by the lack of lubricant, the surface condition of the sliding member 80, the surface condition of the fixing belt 1 over time, and the like. This is an abnormal noise that occurs when the frictional characteristics change. The self-excited vibration is generated due to the change in the frictional characteristics, and the frequency or the harmonic component thereof matches the natural frequency of the fixing device and resonates.

  The sound pressure detection means 86b as the slidability detection means 86 is a means for detecting a frictional sound generated in the nip portion N, as shown in FIG. 10, for example, using a microphone. can do. From the viewpoint of cost, a microphone having a piezoelectric element is preferable.

  Since the air vibration generated in the nip portion N resonates with the constituent members of the fixing device, a sound wave is generated in the air and can be heard as an abnormal sound. Therefore, the sound pressure detecting unit 86b can detect the abnormal sound. Any position can be used regardless of the inside or outside of the fixing device.

When the sound pressure is detected by the sound pressure detection means 86b, a signal is sent to the supply control means 92, and an appropriate amount of lubricant is supplied from the storage portion 91 of the lubricant supply means 90 by the supply control means 92.
Since the frequency of the detected abnormal noise is substantially determined by the structure and components of the fixing device, the supply control unit 92 has a signal detected by the sound pressure detection unit 86b having a power that exceeds a specific frequency range and a reference level. Sometimes it can be set to replenish the lubricant.

(2) Vibration detection means As described above, since self-excited vibration is generated due to the change in the frictional characteristics between the sliding member 80 and the fixing belt 1, the vibration detection means 86 detects this vibration. You can also
As shown in FIG. 9, the vibration detecting means 86a as the slidability detecting means 86 is a means for detecting the vibration of the surface of the fixing belt 1 provided outside the fixing device. For example, a laser Doppler vibrometer is used. Can be used.
When the surface of the fixing belt 1 is vibrating when the surface of the fixing belt 1 is irradiated from the vibration detecting unit 86a, the frequency of the reflected light varies due to the vibration. By detecting this variation, it is possible to detect the mechanical speed and mechanical displacement of the vibration at the irradiated site.

  When vibration is detected by the vibration detection means 86a, a signal is sent to the supply control means 92, and an appropriate amount of lubricant is supplied from the storage portion 91 of the lubricant supply means 90 by the supply control means 92.

  The vibration detection means 86a can detect vibration from the outside of the fixing device in a non-contact manner, and therefore is suitable when the fixing device cannot be disposed inside the device due to restrictions on the structure of the fixing device or allowable temperature. ing. Further, compared to the case where the sound pressure detecting means 86b described above is installed outside the fixing device and the sound pressure is detected, the mechanical vibration generated on the surface of the fixing belt 1 can be directly detected, so that the detection accuracy is improved. Get higher.

  With the above-described configuration, the fixing device according to the present embodiment can replenish the lubricant in a timely manner, prevent an increase in torque and a decrease in slidability due to the lack of the lubricant, and prevent harmful effects caused by excessive replenishment of the lubricant. Can be prevented.

1 Fixing member (fixing belt)
2 Heat source 3 Pressure member (Pressure roller)
3a Metal core 3b Elastic body 4 Light shielding member 5 Lubricant holding member 6 Nip forming member 7 Reinforcing member (stay)
8 Holding member (flange)
9 Reflecting member 10 Fixing device 21 Spring 22 Lever 23 Step ring 24 Side plate 80 Sliding member 81 Liquid chamber 85 Temperature detecting means 86 Sliding property detecting means 86a Vibration detecting means 86b Sound pressure detecting means 90 Lubricant replenishing means 91 Reserving part 92 Supply control means 93 Supply path 100 Image forming apparatus N Nip part F Lubricant

JP 2007-334205 A JP 2014-178523 A Japanese Patent Laying-Open No. 2015-225286 JP 2012-220553 A

Claims (9)

An endless belt-shaped fixing member, a heat source that heats the fixing member, a pressure member that faces the fixing member, and a nip portion that is disposed inside the fixing member and faces the pressure member. A nip forming member, a reinforcing member that supports the nip forming member against pressure applied from the pressure member to the nip forming member, and a sliding member disposed between the fixing member and the nip forming member And a lubricant holding member that holds a lubricant applied to the inner peripheral surface of the fixing member, and a fixing device that heats and fixes unfixed toner on a recording medium that passes through the nip portion,
The nip forming member has a liquid chamber serving as a flow path for the lubricant supplied to the sliding member inside.
A fixing device further comprising: slidability detecting means for detecting a sliding state between the fixing member and the sliding member; and a lubricant replenishing means for supplying a lubricant to the liquid chamber.   The lubricant replenishing means includes a storage section for storing a lubricant, a supply path for supplying the lubricant from the storage section to the liquid chamber, and from the storage section according to a detection result of the slidability detecting means. The fixing device according to claim 1, further comprising a supply control unit that controls supply of the lubricant.   The lubricant holding member is made of a material that expands or contracts as the temperature changes, and is disposed in contact with the reinforcing member. When the reinforcing member exceeds a predetermined temperature, the lubricant holding member expands and contacts the fixing member. The fixing device according to claim 1, wherein the fixing device is in contact with the fixing device. A temperature detecting means for the fixing member;
The lubricant holding member is disposed downstream of the nip forming member and upstream of the temperature detecting means in the rotation direction of the fixing member. The fixing device according to 1.   The fixing device according to claim 1, wherein the lubricant holding member has an axial length of the fixing member shorter than a length of the nip portion.   The fixing device according to claim 1, wherein the lubricant holding member is made of a porous material.   The fixing device according to claim 1, wherein the slidability detecting unit detects a sound pressure of a frictional sound generated in the nip portion.   The fixing device according to claim 1, wherein the slidability detecting unit detects vibration of a surface of the fixing member.   An image forming apparatus comprising the fixing device according to claim 1.