JP3882317B2 - Fixing device and image forming apparatus to which the fixing device is attached - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fixing device attached to an image forming apparatus and an image forming apparatus to which the fixing device is attached.
[0002]
[Prior art]
In a conventional fixing device of an image forming apparatus using an electrophotographic system, various techniques for applying a release agent such as silicone oil to a fixing roll to prevent toner offset are employed. In particular, in a full-color image forming apparatus that mixes a plurality of different color toners, the fixing roll requires a very high release property, so that a large amount of release agent is applied to the fixing roll.
[0003]
Here, the conventional supply of the release agent has mainly used a structure in which a roll impregnated with a release agent such as silicone oil is directly pressed against the surface of the fixing roll. However, such an impregnating roll method has a problem that the supply amount of the release agent varies with time and the offset effect does not last for a long time.
[0004]
In order to solve this problem, a sheet-type release agent supply structure has been proposed in which a wave impregnated with a release agent is wound up while being in contact with a fixing roll.
[0005]
Next, an image forming apparatus using a fixing device having a conventional sheet type release agent supply structure will be described.
[0006]
A developing unit that stores toner of each color of black (B), cyan (C), magenta (M), and yellow (Y) along the outer peripheral surface of the photosensitive belt that is coated with the photosensitive receiving layer and rotates. In addition, a charger for charging the photosensitive belt by corona discharge is provided. Further, a semiconductor laser element is built in, and an LSU (Laser Scanning Unit) is provided that forms an electrostatic latent image by irradiating the photosensitive belt with laser light while switching between emission and extinction of the laser according to image data. Further, an intermediate transfer body belt to which the toner image on the photoreceptor belt is transferred is installed facing the photoreceptor belt.
[0007]
Then, a paper conveyance path is formed so as to contact the circumferentially rotating intermediate transfer belt, and the toner image formed on the intermediate transfer belt is transferred onto the paper conveyed on the paper conveyance path.
[0008]
A fixing device is installed on the downstream side of the paper conveyance path, and the unfixed toner image transferred onto the paper is heated and pressure-fixed by the fixing device.
[0009]
Here, the structure of a fixing device for fixing a toner image on a sheet will be described.
FIG. 9 is a schematic view showing the structure of a fixing device in a conventional image forming apparatus.
[0010]
As shown in FIG. 9, the fixing device includes a fixing roller 8 heated so that the surface temperature becomes an optimum fixing temperature (160 ° C. to 180 ° C.) by an internal or external heat source, and the fixing roller 8 and a pair. An unfixed toner image that is provided and transported between the pressure roller 9 and the sheet, and the fixing roller 8 is coated with silicone oil as a release agent and the surface of the fixing roller 8 after the fixing operation is completed. It has a wave unit 10 as a release agent coating means for cleaning.
[0011]
The wave unit 10 is composed of a sheet-like member made of a nonwoven fabric or a porous material, and a first shaft 12a around which a wave 11 impregnated with a release agent such as silicon oil is wound, and the surface of the fixing roller 8 A second shaft 12b that winds up a used wave 11 that has been coated with a release agent and whose surface has been cleaned, and an unused wave 11 that is wound around the first shaft 12a, that is, a spring against the outer peripheral surface of the wave roll It is comprised from the friction board 13 press-contacted by biasing means (not shown), such as. The wave 11 is pressed against the surface of the fixing roller 8 by the pressing roller 14 from the back side.
[0012]
Here, the fixing roller 8 forms an elastic layer 16 made of HTV silicone rubber (high temperature vulcanization type silicone rubber) on an aluminum core 15 and an oil resistant layer F made of fluoro rubber is formed on the elastic layer 16. Further, an offset prevention layer 17 made of RTV silicone rubber (room temperature vulcanization type silicone rubber) is formed thereon. The outer diameter of the fixing roller 8 is, for example, φ40.
[0013]
The pressure roller 9 is formed by forming an elastic layer 19 made of HTV silicone rubber on an aluminum cored bar 18, and forming a fluororesin resin layer 20 on the elastic layer 19, and the outer diameter is For example, it is φ40.
[0014]
Halogen heaters 21 are disposed in the metal core 15 of the fixing roller 8 and the metal core 18 of the pressure roller 9. Then, the temperature of the fixing roller 8 is detected by a thermistor 22 in contact therewith, and the halogen heater 21 is controlled to be turned on / off, so that the temperature of the fixing roller 8 is kept constant at about 165 ° C.
[0015]
Further, the fixing roller 8 and the pressure roller 9 as fixing means are continuously driven to rotate during a printing operation by a driving mechanism (not shown).
[0016]
On the other hand, the wave unit 10 may be driven intermittently as necessary, and the conveyance (winding) speed of the wave 11 may be lower than the rotation speed of the fixing roller 8, so that silicone oil with a viscosity of 500 cS is impregnated. The measured wave 11 is quantitatively fed so as to be wound around the second shaft 12b via the drive gear 25A of the drive mechanism 25 having a single drive source (motor), and pressed against the fixing roller 8 by the pressing roller 14, It is applied to the offset prevention layer 17 of the fixing roller 8. Further, the friction plate 13 pressed against the outer periphery of the wave roll generates a frictional force on the wave roll when the wave 11 is wound by the pressure contact force, and the first shaft 12a and the second shaft 12b. Appropriate tension is given to the wave 11 placed between them. At the same time, the toner offset (attached) to the offset prevention layer 17 of the fixing roller 8 is removed.
[0017]
The wave unit 10 is detachably attached to the fixing device main body, and can be replaced when the wave 11 is used up.
[0018]
However, the conventional technology having an independent drive source for wave feeding requires expensive parts such as a motor, which is expensive.
[0019]
In order to solve such a high cost problem, a drive transmission mechanism that synchronizes the driving of the fixing roller 8 and the pressure roller 9 as fixing means with the rotational speed and operation timing required for driving the wave unit 10 has been studied. Has been made.
[0020]
The winding mechanism of the wave 11 in such a drive transmission mechanism, specifically, the quantitative rotation driving mechanism of the second shaft 12b will be described in detail.
[0021]
FIG. 10A is a cross-sectional view showing a drive mechanism of the second shaft 12b, and FIG. 10B is a front view showing an operating state of the second shaft 12b.
[0022]
The second shaft 12b is fitted with a bearing 20 incorporating a direction-regulating ball bearing so as to rotatably support the second shaft 12b in only one direction. Further, the second shaft 12 b is fitted with a lever member 21 having a lever portion 21 a and a built-in direction-regulating ball bearing that rotatably supports the second shaft 12 b only in the same direction as the bearing 20. . A solenoid 22 as a suction member that sucks the lever portion 21 a and an elastic member 23 that pulls the lever portion 21 a in a direction opposite to the suction direction of the solenoid 22 are attached to the tip of the lever member 21.
[0023]
As shown in FIG. 10 (b), the bearing 20 and the lever member 21 are set so that the rotational direction is restricted so as to apply the rotational torque to the second shaft 12b only in the counterclockwise direction.
[0024]
In the drive mechanism configured as described above, the second shaft 12b is intermittently driven to rotate at a predetermined interval by driving the solenoid 22 at a predetermined timing.
[0025]
According to the wave unit 10 as described above, a laminated toner image is obtained by passing a sheet carrying a plurality of unfixed toner images while being sandwiched between a rotating fixing roller 8 and a pressure roller 9. Is mixed on the paper and heat-fixed to form a full-color image.
[0026]
[Problems to be solved by the invention]
However, in such a conventional wave feed mechanism, since the drive transmission mechanism to the wave unit is incorporated in the fixing unit drive mechanism, the drive mechanism becomes complicated and a large space is required, so that the fixing device is enlarged. A new problem arises.
[0027]
Further, since the rotation angle of the lever member and the rotation angle of the second shaft that is the winding shaft do not always coincide with each other, it is difficult to obtain a predetermined wave feed amount. Here, FIG. 11 is a graph showing the relationship between the rotational torque of the second shaft necessary for winding the wave and the angle θ at which the second shaft rotates when the lever member rotates. As shown in FIG. 11, when the torque required for rotation is small as in the early stage of wave winding, the second shaft rotates more than the rotation angle θ of the lever member due to the inertial force during rotation. Conversely, when the torque required for rotation is large as in the latter half of the winding of the wave, slip occurs between the lever member and the second shaft, so the second shaft is smaller than the rotation angle θ of the lever member. Rotate.
[0028]
SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device that can drive a fixing unit and stably feed a wave with a single driving source, and an image forming apparatus to which the fixing device is attached.
[0029]
[Means for Solving the Problems]
In order to solve this problem, a fixing device of the present invention includes a fixing roller comprising a fixing roller and a pressure roller that heat and press a toner image transferred to a recording medium and fix the toner image on the recording medium, and a release agent. Is attached to the sheet-shaped wave that is impregnated with the pressure roller and is supplied to the surface of the fixing roller by being pressed by the pressure roller, the first shaft around which the unused portion of the wave is wound, and the second drive unit. A second shaft that winds the wave after the release agent is supplied to the fixing roller, and a drive source that rotationally drives the fixing means via the first drive unit attached to the fixing roller or the pressure roller. One of the plurality of gear trains attached to the fixing roller or the pressure roller having the first driving unit, and the driving force of the driving source transmitted to the fixing means via the first driving unit is the second. To the drive And a second driving force transmission unit that rotates the second shaft at a predetermined speed, and the second driving force transmission unit includes a first gear having a plurality of feed dogs formed on the inner periphery thereof. A rotation restricting member that is rotatably supported over a predetermined angle and is formed with rotation restricting teeth that are alternately engaged with different feed teeth at both ends of the rotation movement; and the rotation restricting member in cooperation with the elastic member. When the feed dog and the rotation restricting tooth are engaged, the displacement means for reciprocatingly rotating and intermittently engaging the feed dog and the rotation restricting tooth idles, and when not engaged, the first It is comprised from the gear train containing the 2nd gearwheel which transmits a driving force to this gearwheel.
[0030]
As a result, it is possible to drive the fixing unit and stably feed the wave with a single drive source.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 of the present invention is impregnated with a fixing means comprising a fixing roller and a pressure roller for heating and pressing a toner image transferred to a recording medium and fixing the toner image on the recording medium, and a release agent. A sheet-like wave that is pressed by the pressing roller to supply the release agent to the surface of the fixing roller, a first shaft around which an unused portion of the wave is wound, and a second driving unit are attached and separated. A second shaft for winding the wave after supplying the mold material to the fixing roller, a driving source for rotationally driving the fixing means via a first driving unit attached to the fixing roller or the pressure roller, and one Comprises a plurality of gear trains attached to a fixing roller or a pressure roller having a first driving unit, and a driving force of a driving source transmitted to the fixing means via the first driving unit is a second driving unit. To the second A second driving force transmission unit that rotates the shaft at a predetermined speed, and the second driving force transmission unit has a first gear having a plurality of feed dogs formed on the inner periphery and a predetermined angle. A rotation restricting member that is rotatably supported and formed with rotation restricting teeth that are alternately engaged with different feed teeth at both ends of the turning movement; Displacement means for intermittently engaging the feed dog and the rotation restricting tooth, and when the feed dog and the rotation restricting tooth are engaged, the wheel rotates idly, and when not engaged, a driving force is applied to the first gear. Is a fixing device composed of a gear train including a second gear for transmitting the power, and has a function of enabling driving of fixing means and stable quantitative feeding of a wave by a single driving source. .
[0032]
The invention according to claim 2 of the present invention is an image forming apparatus to which the fixing device according to claim 1 is attached, and has an effect that the size of the apparatus becomes compact.
[0033]
Hereinafter, embodiments of the present invention will be described with reference to FIGS. In these drawings, the same members are denoted by the same reference numerals, and redundant description is omitted.
[0034]
FIG. 1 is an explanatory view showing an internal structure of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a driving force transmission mechanism to a wave unit in a fixing device mounted on the image forming apparatus of FIG. 3 is a perspective view showing the image forming apparatus of FIG. 1 with the front door opened, FIG. 4 is a perspective view showing the arrangement of various drive sources in the image forming apparatus of FIG. 1, and FIG. FIG. 6 is an exploded perspective view showing a fixing means in the fixing device shown in FIG. 5, and FIG. 7 is an exploded perspective view showing a wave unit in the fixing device shown in FIG. 8 and 8 are exploded perspective views of the fixing device of FIG.
[0035]
In FIG. 1, a photosensitive belt (photosensitive body) 3 on which a photosensitive receiving layer such as an organic photoconductor (OPC) is applied in a thin film is formed on one side by three photosensitive belt supporting and conveying rollers 3a, 3b, and 3c. The belt is tuned and supported so as to form a horizontal plane, and is rotated around the photosensitive belt supporting and conveying rollers 3a, 3b, and 3c by a drive motor (not shown). On the upper portion of the photosensitive belt 3, along the outer peripheral surface thereof, developing devices 2B, 2C, 2M, and 2Y that store toners of each color of black (B), cyan (C), magenta (M), and yellow (Y). Is provided. On the side of the photoreceptor belt 3, a photoreceptor cleaning device 212 that removes toner remaining on the photoreceptor belt 3, a neutralizer 209 that discharges the photoreceptor belt 3 in parallel with an LED lamp, and a photoreceptor belt by corona discharge. 3 is installed, and a laser unit 1 is further provided.
[0036]
The charger 210 includes a charging wire 210a made of tungsten wire or the like, a shield plate 210b made of a metal plate, and a grid plate 210c. Then, by applying a high voltage to the charging wire 210a, the charging wire 210a causes corona discharge, and the photosensitive belt 3 is uniformly charged through the grid plate 210c. The laser light emitted from the laser unit is controlled by a signal from a host computer (not shown), and a plurality of predetermined components on the photosensitive belt 3 corresponding to specific components among a plurality of predetermined color components. An electrostatic latent image is formed.
[0037]
The developing units 2B, 2C, 2M, and 2Y for each color are detachably arranged at predetermined intervals in a predetermined storage portion provided in the main body of the apparatus, and the inside of each developing unit is except for the type of the stored toner. The configuration is the same.
[0038]
Corresponding to the developing devices 2B, 2C, 2M, and 2Y, the developing devices 2B, 2C, 2M, and 2Y are brought into contact with the photosensitive belt 3 when developing an electrostatic latent image of a predetermined color. Cams 5B, 5C, 5M, and 5Y are provided, and when the developing devices 2B, 2C, 2M, and 2Y are not pushed in the direction of the photosensitive belt 3 by the contact cams 5B, 5C, 5M, and 5Y, the photosensitive belt 3 And is held at a stand-by position separated from each other.
[0039]
The intermediate transfer body unit includes an intermediate transfer body belt (intermediate transfer body) 4 made of a conductive resin and the like, and three intermediate transfer body belt supporting and conveying rollers 4a, 4b, and 4c on which the intermediate transfer body belt 4 is adjusted. And have. In order to transfer the toner image on the photoreceptor belt 3 onto the intermediate transfer body belt 4, an intermediate transfer roller 213 is disposed to face the photoreceptor belt 3 with the intermediate transfer body belt 4 interposed therebetween.
[0040]
Here, the surface circumferential length of the intermediate transfer belt 4 is set to be equal to the surface circumferential length of the photosensitive belt 3. In order to scrape the residual toner on the intermediate transfer body belt 4, an intermediate transfer body belt cleaning device 215 is installed in the vicinity of the intermediate transfer body belt supporting and conveying roller 4 c. The intermediate transfer belt cleaning device 215 is separated from the intermediate transfer belt 4 while a composite image is formed on the intermediate transfer belt 4, and contacts the intermediate transfer belt 4 only when it is used for cleaning.
[0041]
A paper cassette (not shown) for storing paper (recording medium) 214 is provided at the lower part of the apparatus. The sheets 214 are sent one by one from the sheet cassette to the sheet conveyance path by the sheet feeding roller 217. In order to match the position of the composite image formed on the sheet 214 and the intermediate transfer body belt 4, a registration roller 218 for temporarily stopping and waiting for the sheet 214 is provided in pressure contact with the driven roller 219. Further, a medium transfer roller (transfer roller) 7 is provided on the sheet conveyance path to transfer a composite image formed on the intermediate transfer body belt 4 to the sheet 214 by applying a voltage having a polarity different from that of the toner. Thus, only when the composite image is transferred onto the sheet 214, it is rotated in contact with the intermediate transfer belt 4. The medium transfer roller 7 is made of, for example, conductive foamed polyurethane. In addition to the paper 214, for example, an OHP film can be applied to the recording medium.
[0042]
In order to fix the composite image transferred to the paper 214, a fixing device 101 including a fixing roller 106 having a heat source and a pressure roller 107 is disposed. Then, the composite image transferred by pressure and heat is fixed on the sheet 214 as the fixing roller 106 and the pressure roller 107 are nipped and rotated when passing through the fixing device 101, and a color image is formed.
[0043]
The fixing device 101 includes a wave unit 105 and fixing means including a fixing roller 106 and a pressure roller 107.
[0044]
As shown in FIG. 3, the fixing device 101 is detachable from the front of the image forming apparatus together with an image forming unit including an image carrier (not shown). As shown in FIG. 4, the drive system of the image forming apparatus in the present embodiment includes a motor (drive source) 102 that drives a fixing unit and a conveyance system of a sheet to which a toner image is transferred, a photosensitive belt. 3 and a main motor 103 for rotating the intermediate transfer belt 4 and a developing device drive motor 104 as a driving source for bringing the developing devices 2B, 2C, 2M and 2Y into contact with and separating from the photosensitive belt 3 are provided. .
[0045]
The fixing roller 106 is heated by an internal or external heat source so that the surface temperature thereof is 160 ° C. to 180 ° C. which is the optimum fixing temperature. A pressure roller 107 that contacts the fixing roller 106 and rotates with the rotation of the fixing roller 106 cooperates with the fixing roller 106 to pinch the conveyed unfixed toner image together with the paper. Further, the wave unit 105 applies silicone oil as a release agent to the fixing roller 106 and cleans the surface of the fixing roller 106 that has completed the fixing operation. The configurations of the fixing roller 106 and the pressure roller 107 are substantially the same as those of the fixing roller 8 and the pressure roller 9 shown in FIG.
[0046]
Here, the wave unit 105 includes a first shaft 109 around which a sheet-like wave 108 made of a nonwoven fabric or a porous material impregnated with a release agent such as silicon oil is wound, and a second shaft that winds the wave 108. The shaft 110, the pressing roller 111 that presses the wave 108 from the inside along the longitudinal direction of the surface of the fixing roller 106 with a predetermined pressing force, and a determination unit 112 including a resistance fuse and a resistance.
[0047]
At one end of the second shaft 110, a wave gear (second drive unit) 113 is attached to which the driving force from the motor 102 as a drive source is transmitted when the fixing device 101 is mounted on the apparatus main body. . A gear train is provided as a second driving force transmission unit to which the wave gear 113 is engaged when the wave unit 105 is mounted on the fixing device 101.
[0048]
Further, a fixing roller gear (first driving unit) 115 that rotationally drives the fixing roller 106 is provided at the shaft end on the same side as the motor 102 of the fixing roller 106 that is rotatably supported by bearings 116 attached to both ends. Is provided. Further, a gear 117 forming a part of the second driving force transmission unit is attached to the shaft end opposite to the fixing roller gear 115. Note that the fixing roller gear 115 and the gear 117 may be attached to the pressure roller 107.
[0049]
Here, the gear train that is the second driving force transmission unit and the wave gear 113 that is the second driving unit will be described with reference to FIG.
[0050]
In FIG. 2A, the gear train has gears 118 to 123 that are chain-engaged with each other, and the wave gear 113 is connected to the plurality of feed teeth 124a on the inner periphery via these gears 118 to 123. Is connected to a gear (first gear) 124 having The rotation of the gear 124 is restricted by a rotation restricting member 125. Note that the gear ratios of the gears 122, 121, 120, and 119 are set so that the rotation angle of one gear tooth 124 a of the gear 124 becomes a predetermined rotation angle of the second shaft 110.
[0051]
As shown in detail in FIG. 2 (b), the rotation restricting member 125 is rotated by a reciprocating motion of a solenoid (displacement means) 126 and a resilient force of a spring 127 (elastic member) about a rotation shaft 125c. It is formed in a letter shape. Further, at one end, two rotation restricting teeth 125a and 125b that are alternately engaged with different positions of the feed dog 124a of the gear 124 are formed with a phase shifted from the tooth pitch of the feed dog 124a by a half pitch. Yes.
[0052]
The gear 123 is connected to the gear 117 via a gear (second gear) 128 and a gear 129. Therefore, the gear 123 is engaged with the gear 124 and the gear 128.
[0053]
As shown in FIG. 2 (c), the gear 128 includes two gears 128b and 128c provided coaxially with the rotating shaft 128d, and a coil spring (elastic member) that is fitted into the rotating shaft 128d and provides a torque limiter effect. Become.
[0054]
The operation of the image forming apparatus configured as described above will be described below. In FIG. 1, the charged photoreceptor belt 3 is uniformly neutralized by the static eliminator 209, and then a high voltage is applied to the charging wire 210 a in the charger 210 connected to the high voltage power source to cause corona discharge. Is uniformly charged to about -500v to -650v.
[0055]
Next, the photosensitive belt 3 is rotated by a driving device (not shown), and a predetermined color of a plurality of color components, for example, black (B) is formed on the uniformly charged surface of the photosensitive belt 3. The laser beam corresponding to the image is irradiated. As a result, the portion of the photosensitive belt 3 irradiated with the laser light is erased and an electrostatic latent image is formed. On the other hand, the developing device 2B storing black toner that contributes to development contacts the photosensitive belt 3 when the contact cam 5B rotates halfway by a color selection signal from a host computer (not shown). Is done. Then, a thin layer of toner to which a predetermined voltage is applied adheres to the electrostatic latent image to form a toner image.
[0056]
The developing device 2B that has completed the development in this manner moves from the contact position with the photosensitive belt 3 to the standby position by further rotating the contact cam 5B. While the developing device 2B is developing, the other developing devices 2C, 2M, and 2Y are separated from the photosensitive belt 3.
[0057]
Next, for example, when a cyan (C) color is selected, the developing device 2C comes into contact with the photosensitive belt 3 and starts developing cyan by the same operation as described above. In the case of using four colors, such a development operation is sequentially repeated four times, and the four-color toner images of B, C, M, and Y are transferred onto the intermediate transfer belt 4 so as to overlap each other. A composite image is formed here. A single-layer toner image is formed for one color, a two-layer toner image for two colors, and a three-layer toner image for three colors.
[0058]
A small amount of toner remaining on the photoreceptor belt 3 without being transferred is cleaned by the photoreceptor cleaning device 212 and prepared for the next process.
[0059]
The composite image formed in this manner is collectively transferred to the sheet 214 sent from the sheet cassette along the sheet conveyance path when a high voltage having a polarity opposite to that of the toner is applied to the medium transfer roller 7.
[0060]
The sheet 214 onto which the composite image has been transferred is subsequently sent to the fixing device 101. Then, the image is fixed by heat and the clamping force of the fixing roller 106 and the pressure roller 107, and a color image is formed. The paper 214 that has passed through the fixing device 101 is discharged to a paper discharge tray.
[0061]
A small amount of toner remaining without being transferred onto the intermediate transfer belt 4 is cleaned by the intermediate transfer belt cleaning device 215 coming into contact with an electromagnetic clutch (not shown) to be ready for the next process.
[0062]
Next, the operation of the fixing device 101 configured as described above will be described.
As already described, the wave 108 is wound around the first shaft 109 in a roll shape to form a wave roll. Then, the wave 108 is drawn from the first shaft 109 in the direction of arrow P shown in FIG. 5 by the rotational drive of the second shaft 110.
[0063]
Here, the operation of the second driving force transmission unit will be described.
As shown in FIG. 2, the gear 128 has an inner peripheral gear 128 b meshed with the gear 123 and an outer peripheral gear 128 c meshed with the gear 129. The gear 128c is a friction wheel with respect to the rotating shaft 128d, and the gear 117 is rotated by the rotation of the fixing roller 106, and the drive is transmitted to the gear 128c via the gear 129. At this time, a frictional force is generated between the gear 129 and the gear 117 due to the elastic force of the coil spring 128a, whereby the gear 128 obtains a rotational torque having a specific width. This rotational torque is set such that the lower limit is the minimum driving force required for winding the wave 108, and the upper limit is the torque that causes the gear 128c to idle when the rotation of the gear 124 is restricted by the rotation restricting member 125.
[0064]
As described above, the two rotation restricting teeth 125a and 125b of the rotation restricting member 125 are in a relationship in which the phase is shifted by a half pitch from the tooth pitch of the feed dog 124a of the gear 124. Accordingly, the reciprocating motion of the rotation restricting member 125 having such rotation restricting teeth 125a and 125b restricts the gear 124 from rotating by two or more teeth of the feed dog 124a.
[0065]
Here, when the rotation restricting member 125 is displaced by the solenoid 126 at a predetermined timing, the rotation restricting tooth 125a is disengaged from the one feed dog 124a by the rotational movement around the rotating shaft 125c, and the other rotation is performed. Until the restricting tooth 125b newly engages with the feed dog 124a, the gear 124 can be rotated counterclockwise by the ½ tooth pitch (in the direction indicated by the arrow in FIG. 2B). As a result, the idling state of the gear 128c is released, and the gear 123 engaged with the gear 124 rotates in the direction indicated by the arrow by the rotational drive of the gear 128b.
[0066]
Next, when the rotation restricting member 125 is rotated about the rotation shaft 125c in the opposite direction to the case where the rotation restricting member 125 is displaced by the solenoid 126 by the repulsive force (returning force) of the spring 127, the rotation restricting tooth 125b and one The gear 124 rotates counterclockwise by a 1/2 tooth pitch until the engagement with the feed dog 124a is disengaged and the other rotation restricting tooth 125a is newly engaged with the feed dog 124a. As a result, the gear 123 engaged with the gear 124 rotates again in the direction indicated by the arrow by the rotational drive of the gear 128b.
[0067]
Thus, the gear 124 rotates by one tooth pitch by one reciprocation of the rotation restricting member 125. As the gear 124 rotates, the driving force is sequentially transmitted from the gear 123 to the gear 122, gear 121, gear 120, and gear 119 and transmitted to the wave gear 113, and the second shaft 110 is rotated to cause the wave 108 to rotate. It can be wound up quantitatively.
[0068]
As a result, it is possible to drive the fixing means and perform stable quantitative feed of the wave with a compact drive mechanism by a single motor 102.
[0069]
【The invention's effect】
As described above, according to the present invention, it is possible to obtain an effective effect that it is possible to drive the fixing unit and perform stable quantitative feed of the wave with a single drive source.
[0070]
Further, by attaching such a fixing device to the image forming apparatus, an effective effect that the apparatus size can be reduced can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an internal structure of an image forming apparatus according to an embodiment of the present invention.
2 is a cross-sectional view showing a driving force transmission mechanism to a wave unit in a fixing device mounted on the image forming apparatus of FIG. 1;
3 is a perspective view showing the image forming apparatus of FIG. 1 with the front door opened. FIG.
4 is a perspective view illustrating the arrangement of various drive sources in the image forming apparatus of FIG.
5 is an explanatory view showing the structure of a fixing device attached to the image forming apparatus of FIG.
6 is an exploded perspective view showing fixing means in the fixing device of FIG.
7 is an exploded perspective view showing a wave unit in the fixing device of FIG. 5;
8 is an exploded perspective view of the fixing device of FIG.
FIG. 9 is a schematic diagram illustrating a structure of a fixing device in a conventional image forming apparatus.
FIG. 10A is a sectional view showing a driving mechanism of the second shaft.
(B) Front view showing the operating state of the second shaft
FIG. 11 is a graph showing the relationship between the rotational torque of the second shaft necessary for winding the wave and the angle θ at which the second shaft rotates when the lever member rotates.
[Explanation of symbols]
101 Fixing device
102 Motor (drive source)
106 Fixing roller
107 Pressure roller
108 Wave
109 First shaft
110 Second shaft
113 Wave Gear (Second Drive Unit)
115 Fixing roller gear (first driving unit)
124 Gear (first gear)
124a Feed dog
125 rotation restriction teeth
125a Rotation restriction tooth
125b Rotation restriction tooth
126 Solenoid (displacement means)
127 Spring (elastic member)
128 gear (second gear)

Claims (2)

A fixing means comprising a fixing roller and a pressure roller for heating and pressing the toner image transferred to the recording medium and fixing the toner image on the recording medium;
A sheet-like wave impregnated with a release agent and pressed against the pressure roller to supply the release agent to the surface of the fixing roller;
A first shaft around which the unused portion of the wave is wound;
A second shaft to which the second drive unit is attached and winds up the wave after the release agent is supplied to the fixing roller;
A drive source for rotationally driving the fixing means via a first drive unit attached to the fixing roller or the pressure roller;
One of the plurality of gear trains attached to the fixing roller or the pressure roller having the first driving unit, and the driving source transmitted to the fixing unit via the first driving unit. A second driving force transmission unit that transmits a driving force to the second driving unit to rotate the second shaft at a predetermined speed;
The second driving force transmission unit is
A first gear having a plurality of feed dogs formed on the inner periphery;
A rotation restricting member that is rotatably supported over a predetermined angle and is formed with a rotation restricting tooth that alternately engages different feed teeth at both ends of the turning motion;
Displacement means for reciprocally rotating the rotation restricting member in cooperation with an elastic member and intermittently engaging the feed dog and the rotation restricting tooth;
When the feed dog and the rotation restricting tooth are engaged, they are idled, and when not engaged, they are constituted by a gear train including a second gear that transmits a driving force to the first gear. A fixing device. An image forming apparatus comprising the fixing device according to claim 1.

Images