JP4579717B2 - Sheet conveying device, fixing device, and image forming apparatus - Google Patents

Description

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

  Image forming apparatuses such as printers, facsimiles, and copiers that form images by electrophotography have a fixing device for fixing the toner image by heating and pressing an unfixed toner image formed on a sheet. It is installed.

  Since the fixing unit provided in the fixing device heats and pressurizes the sheet, there is a concern that a jam may occur inside the fixing device depending on the state of the sheet. This is because, for example, an extremely moisture-containing sheet or a sheet with a large amount of wrinkles causes the sheet to be bent or warped after heating and pressing.

  In the present day when image forming apparatuses are being downsized, the fixing apparatus is also downsized. In such a case, the width of the sheet conveyance path in the fixing apparatus must be narrowed. . This also contributes to further increasing the occurrence of the jam.

  There are two main types of jam situations. One is a case in which a jam occurs in a state that does not appear outside the fixing device, that is, in a state where it completely stays inside the fixing device. In this case, the user (operator) can reliably remove the jammed sheet by directly accessing the fixing device.

  On the other hand, as another jam situation, there is a case where the fixing device is stopped in a state where a part of the sheet causing the jam appears outside the fixing device. In this case, the user generally tries to pull out the sheet that has caused the jam directly. However, in such a situation, due to the configuration of the fixing device, the jammed sheet is often stopped in a state of being sandwiched between the sheet conveying rotating bodies, and when the user pulls out the sheet, A force that overcomes the rotational load including the rotational drive source connected to the conveying rotator is required.

  Here, when the rotational drive source is connected to the fixing means, the pressure means, or both, a larger urging force is applied to the pressure means, so that a larger rotational load is required. For this reason, there is a concern that the burden on the jam processing is increased for the user.

  In addition to the above, when a large pulling force is applied to the sheet, the sheet is torn and a part of the sheet is left in the fixing device. There is also a concern that the drive transmission means connecting the means may be damaged.

  For this reason, the drive transmission means is disconnected from the connection between the drive transmission means, the sheet conveying rotator, the fixing means, and the pressure means, for example, by providing a clutch.

  For example, as shown in FIG. 11, the driving mechanism is driven only in one direction in a mechanism that transmits the driving of the rotation driving source and the gear provided in the fixing unit or the pressing unit, or both. This is performed by a method of incorporating an element for transmitting information (for example, Patent Document 1).

In FIG. 11, a driving side gear 211 and a driven side gear 212 are coaxially disposed between the intermediate gear 202 and the roller gear 204, and the driving side gear 211 can move linearly on the shaft, The intermediate gear 202 meshes with the intermediate gear 202.

  On the shaft, the drive side gear 211 is urged to the driven side gear 212 by a spring.

  Here, the pressure contact surfaces of the drive side gear 211 and the driven side gear 212 mesh with each other in one rotation direction, and in the other rotation direction, the drive side gear 211 repeats the separation / contact operation to transmit the rotation. Claw-like projections are provided to prevent this.

  Next, when attention is paid to the stopping of the fixing device when a jam occurs, when a jam occurs in a state where the sheet is in contact with or sandwiched between the sheet conveyance rotator, a braking force is applied to the sheet conveyance rotator. In contrast, until the rotational drive source stops supplying the rotational drive force, the rotational drive source transmits the rotational drive force to the drive transmission means one after another, and these rotational drive forces are transmitted to the drive transmission means. Each element is converted into torsional shear stress and accumulated. Eventually, there is a concern that any of the elements will be destroyed, causing a problem that the fixing device is damaged.

For this reason, when a force exceeding a predetermined rotational driving force is applied to the drive transmission means, measures such as providing a torque limiter for canceling the transmission of the rotational driving force are taken.
JP 2001-173642 A

  However, in the case of the conventional technology as described above, there are concerns that the following problems will occur.

  (1) When a dedicated element such as the clutch or torque limiter is used, the cost becomes high.

  (2) When the clutch and torque limiter are incorporated in the drive transmission means, respectively, the size of the entire fixing device is increased.

  Further, as disclosed in Patent Document 1, an element that transmits driving only in one rotation direction is a mechanism that transmits driving between a fixing unit, a pressing unit, or a gear provided in both of them, and a rotational driving source. In the case where there are only a pair of rollers to be driven, the degree of contribution to light load is high, but when a plurality of roller pairs are connected, especially with the gears of the fixing means and the pressure means. When the sheet conveying rotating body pair is connected, when the sheet is jammed between the fixing unit and the nip N of the pressing unit and between the sheet conveying rotating body pair, as described above. No consideration is given to breakage of the fixing device.

  The present invention has been made in view of the circumstances as described above, and provides a technique capable of reducing the load imposed on the user by jam processing while preventing an increase in cost and size of the apparatus. Objective.

In order to achieve the above object, the present invention provides:
A sheet conveying rotating body that conveys the sheet in the sheet conveying direction;
Drive transmission means for transmitting the rotational driving force from the drive means to the sheet conveying rotator for conveying the sheet by the sheet conveying rotator;
In a sheet conveying apparatus comprising:
The drive transmission means includes at least first drive transmission means for transmitting rotational driving force between drive transmission portions provided in each of the drive transmission means, and second drive transmission means on the drive means side of the first drive transmission means. ,
Provided in the drive transmission portion provided to each of the first drive transmission means and the second drive transmission means, the direction of the relative rotation between the first drive transmission means and the second drive transmitting means any Even in this case , based on the magnitude of the rotational driving force acting between the first drive transmission means and the second drive transmission means, the distance between the first drive transmission means and the second drive transmission means. Drive intermittent means for intermittently transmitting the rotational driving force ,
The drive transmission portions of the first drive transmission means and the second drive transmission means are opposed to each other in the axial direction of the rotation axis of the transmitted rotation, and protrude in the axial direction at a position shifted from the rotation center. Provided to have a protrusion and rotate on the same axis,
At least one of the drive transmission portions is provided so as to be movable in the axial direction, and is pressed against the other of the drive transmission portions by the urging force of the urging means, and the protruding portions mesh with each other in the rotation direction. Thereby, transmission of the rotational driving force between the first drive transmission means and the second drive transmission means is performed,
The engagement state of the protrusions is released by separating the drive transmission portions from each other against the urging force of the urging means, so that the first drive transmission means and the second drive transmission means The transmission of the rotational driving force between them is cut off .

In the fixing device, the sheet conveying device described above,
A fixing unit provided so that a driving force from the driving unit is transmitted by the driving transmission unit on the upstream side of the sheet conveying rotating body, and fixes an unfixed toner image formed on the sheet to the sheet; ,
It is characterized by providing.
Further, in the fixing device, a sheet conveying rotating body that conveys the sheet in the sheet conveying direction;
Drive transmission means for transmitting the rotational driving force from the drive means to the sheet conveying rotator for conveying the sheet by the sheet conveying rotator,
The drive transmission means includes at least first drive transmission means for transmitting rotational driving force between drive transmission portions provided in each of the drive transmission means, and second drive transmission means on the drive means side of the first drive transmission means. ,
Which is provided in the drive transmission portion provided in each of the first drive transmission means and the second drive transmission means, and the relative rotational direction between the first drive transmission means and the second drive transmission means is any Even in this case, based on the magnitude of the rotational driving force acting between the first drive transmission means and the second drive transmission means, the distance between the first drive transmission means and the second drive transmission means. Drive intermittent means for intermittently transmitting the rotational driving force,
Fixing is provided so that the driving force from the driving means is transmitted by the second drive transmission means on the upstream side of the sheet conveying rotator, and the unfixed toner image formed on the sheet is fixed on the sheet. Means,
A pressure unit that presses against the fixing unit in order to sandwich and convey the sheet at the nip with the fixing unit;
Release means for eliminating the contact state between the fixing means and the pressure means;
It is characterized by providing.

In the image forming apparatus,
Image forming means for forming a toner image on a sheet;
The fixing device as described above for fixing a toner image formed by the image forming unit to a sheet;
It is characterized by providing.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to reduce the load which a user is forced to jam processing, preventing high cost and the enlargement of an apparatus.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

  First, the configuration and operation of a full-color laser beam printer 170 as an image forming apparatus according to an embodiment of the present invention will be described with reference to FIG. The image forming apparatus according to the present embodiment can be applied not only to a full-color laser beam printer but also to other electrophotographic image forming apparatuses such as a monochrome printer, a copying machine, and a facsimile apparatus having a single photosensitive member.

[Configuration of Image Forming Apparatus]
FIG. 10 is a longitudinal sectional view showing an outline of a full-color laser beam printer (hereinafter referred to as a printer) 170 according to the embodiment of the present invention.

  A sheet supply device 120 that supplies the sheet S to the image forming unit 108 is provided at the bottom of the apparatus main body 171 of the printer 170.

The sheet supply apparatus 120 supplies the sheet S to the image forming unit 108 from a sheet supply cassette 121 that stores a plurality of sheets S.

  The printer main body 171 includes four photosensitive drums 101a, 101b, and 101c as image carriers corresponding to the respective colors of yellow (Y), cyan (C), magenta (M), and black (BK) in the vertical direction. , 101d (hereinafter, the reference numeral 101 is used to collectively refer to the photosensitive drum). The photosensitive drum 101 is rotated counterclockwise in FIG. 10 by a rotating means (not shown).

  Around the photosensitive drum 101, charging devices 102a, 102b, 102c, and 102d that uniformly charge the surface of the photosensitive drum 101 in order according to the rotation direction (hereinafter, the charging device is collectively referred to as reference numeral 102). The scanner units 103a, 103b, 103c, and 103d that irradiate a laser beam based on the image information of each color and form an electrostatic latent image on the photosensitive drum 1 (hereinafter, the reference numeral 103 is used to collectively refer to the scanner unit). ), Developing devices 104a, 104b, 104c, and 104d for developing toner images by attaching toners of yellow, cyan, magenta, and black to the electrostatic latent image (hereinafter, the reference numeral 104 is used to collectively refer to the developing devices). ), A cleaning device 10 for removing toner remaining on the surface of the photosensitive drum 101 after transfer. a, 106b, 106c, 106d, etc. are disposed (hereinafter, using the code 106 will be collectively cleaning device). The photosensitive drum 101, the charging device 102, the developing device 104, and the like constitute an image forming unit (image forming unit) 108.

  Here, the photosensitive drum 101, the charging device 102, the developing device 104, and the cleaning device 106 are integrated into a cartridge, and the process cartridges 107a, 107b, 107c, and 107d (hereinafter, the process cartridge is collectively referred to by reference numeral 107). ) Is formed.

  An electrostatic transfer belt device 110 is disposed at the opposing portion of the photosensitive drums 101a, 101b, 101c, and 101d so that the electrostatic transfer belt 111 is in contact with the photosensitive drums 101a, 101b, 101c, and 101d. The electrostatic transfer belt 111 is formed of a film-like member having a predetermined volume specific resistance. The electrostatic transfer belt 111 is stretched around four rollers, a driving roller 112 and driven rollers 113, 114, and 115, and rotates clockwise in FIG.

  The driving roller 112 is supported on both side frames (not shown) by ball bearings 116 attached to shafts 112a at both ends. The driven rollers 113, 114, and 115 are also supported on both side frames (not shown) in the same manner.

  An electrostatic attraction roller 117 is provided on the most upstream side of the electrostatic transfer belt device 110 in the transport direction of the sheet S so as to face the driven roller 113 with the electrostatic transfer belt 111 interposed therebetween. The electrostatic attraction roller 117 presses the sheet S to the outer periphery of the electrostatic transfer belt 111 and applies a voltage between the electrostatic transfer belt 111 and the sheet S is electrostatically attracted to the electrostatic transfer belt 111. To be transported. Inside the electrostatic transfer belt 111, transfer rollers 118a, 118b, 118c, and 118d (hereinafter referred to as transfer rollers) that contact the electrostatic transfer belt 111 so as to face the four photosensitive drums 101a, 101b, 101c, and 101d. When used collectively, reference numeral 118 is used).

  A fixing device 130 is provided on the downstream side of the electrostatic transfer belt device 110.

[Operation of Image Forming Apparatus]
When the printer 170 prints (image forming operation), the sheet supply roller 122 is driven and rotated in accordance with the image forming operation.

  The sheet supply roller 122 separates the sheets S in the sheet supply cassette 121 one by one and sends them out from the sheet supply cassette 121. The leading edge of the sheet S abuts against the registration roller pair 123 that has stopped rotating, temporarily stops to form a loop, and the skew is corrected.

  On the other hand, the process cartridges 107a, 107b, 107c, and 107d are sequentially driven in accordance with the print timing, and the photosensitive drums 101a, 101b, 101c, and 101d are driven to rotate counterclockwise in accordance with the drive. Then, the scanner units 103 corresponding to the respective process cartridges 107 are sequentially driven. By this driving, the charging roller 102 applies a uniform charge to the peripheral surface of the photosensitive drum 101, and the scanner unit 103 exposes the peripheral surface of the photosensitive drum 101 in accordance with an image signal to perform the photosensitive drum 1. An electrostatic latent image is formed on the peripheral surface.

  A developing roller in the developing device 104 transfers toner to a low potential portion of the electrostatic latent image to form a toner image on the peripheral surface of the photosensitive drum 101.

  At the timing when the leading edge of the toner image on the peripheral surface of the most upstream photosensitive drum 101a is rotated and conveyed to a point facing the electrostatic transfer belt 111, the printing start position of the sheet S coincides with that point. Then, the registration roller pair 123 starts to rotate and feeds the sheet S to the electrostatic transfer belt device 10.

  The sheet S charged by the electrostatic attraction roller 117 and adsorbed to the electrostatic transfer belt 111 is subjected to the toner images on the photosensitive drums 101 sequentially by an electric field formed between the photosensitive drums 101 and the transfer roller 118. Transcribed.

  The sheet S on which the four color toner images have been transferred is separated from the electrostatic transfer belt 111 by the curvature of the belt driving roller 112, guided to the fixing inlet guide 133, and carried into the fixing device 130. The sheet S is pressurized and heated at the nip N to fix the toner image, and is then fed along the sheet conveyance guide 134 and discharged to the sheet discharge tray 160 by the conveyance roller pair 26.

  Next, the fixing device 130 according to the first embodiment of the present invention will be described with reference to FIGS.

[Configuration of Fixing Device]
FIG. 1 is a longitudinal sectional view showing an outline of a fixing device 130 according to the first embodiment of the present invention.

  The fixing device 130 is disposed inside the cylinder of the fixing film 10 and the pressure roller 12 that presses against the fixing film 10 to form the fixing nip N, and heating means for heating the fixing film 10. 11 is provided.

  At both ends of the fixing film 10, the movement of the fixing film 10 in the rotation axis direction is restricted, and the posture of the fixing film 10 in the rotation direction is formed, and at the same time, both ends of the heating unit 11 are supported. A fixing film flange (not shown) is provided.

  On the other hand, both ends of the pressure roller 12 are provided with bearing materials (not shown) that rotatably support the pressure roller 12.

  In addition, by urging the heating means 11 or the fixing film flange, the pressing spring 14 for pressing the fixing film 10 against the pressing roller 12 and the urging force of the pressing spring 14 are There are provided a pressure plate 15 for converting the urging force according to the principle, and a separation means 16 for allowing the fixing film 10 to be separated from the pressure roller 12 by a predetermined distance.

  Here, the fixing film 10, the heating means 11, and the fixing film flange constitute the fixing means according to the present invention, and the pressure roller 12, the pressure spring 14, the pressure plate 15, and the bearing material are the pressure means according to the present invention. The separating means 16 and the pressure plate 15 constitute a releasing means according to the present invention.

  Further, on the downstream side of the nip N formed between the fixing film 10 and the pressure roller 12 in the sheet conveying direction, a sheet S on which toner is heated and pressed and fixed is provided outside the fixing device 130. A conveying roller pair 26 is provided as a sheet conveying rotating body for discharging the sheet. The conveying roller pair 26 includes a gear 26c for receiving power from the driving means (not shown) at one end of the conveying roller 26a constituting the conveying roller pair 26. The gear for receiving the power from the driving means (not shown) may be further provided at one end of the transport roller 26b, that is, provided at least one of the transport roller pair 26. That's fine.

  Further, a plurality of gears 17 a, A drive transmission means 17 having 17b, 17c, 17d, 17e, and 17f is provided.

  Further, the drive transmission means 17 is provided on a part of the drive transmission path and is based on the magnitude of the rotational driving force (torque, load) transmitted and the rotation direction of the gears 17a, 17b, 17c relative to the gears 17d, 17e, 17f. In addition, a drive intermittent means (clutch unit with gear) 20 for releasing drive connection with a drive means (not shown), a frame, and the like are provided. In the present embodiment, the separating means 16 is configured by using a cam, but is not limited thereto, and may be configured by other mechanical elements such as gears, bolts and nuts. Good. Here, a part of the gears 17a, 17b, 17c and the drive interrupting means 20 constitutes a second drive transmission means according to the present invention, and a part of the gears 17d, 17e, 17f and the drive interrupting means 20 according to the present invention. The first drive transmission means is configured. Further, the drive transmission means 17, the gear 26c, and the conveyance roller pair 26 for transmitting a driving force from a drive means (drive source) (not shown) constitute a sheet conveyance apparatus according to the present invention.

  Further, the fixing device 130 includes a (first) sheet detecting unit 135 that detects the entrance of the sheet S on the upstream side of the fixing film 10 and the pressure roller 12 in the conveyance direction of the sheet S. . Further, on the downstream side of the fixing film 10 and the pressure roller 12, a (second) sheet detecting unit 136 that detects the discharge of the sheet S is provided.

  In the present embodiment, the above-described drive means (not shown) is provided in the printer 170, and when the fixing device 130 is mounted on the printer 170, the drive transmission means 17 and the drive means are connected to each other. Connected.

  The driving means (not shown) not only drives the pressure roller 12 and the conveying roller 26a in the forward rotation direction, but also drives the fixing film 10 in the opposite direction when the driving means (not shown) is driven in the opposite direction. A driving force is transmitted from the pressure roller 12 to a separation means 16 provided to separate the pressure film 12 by a predetermined distance, so that the fixing film 10 and the pressure roller 12 can be separated or pressed. .

[Configuration of Drive Intermittent Means 20]
FIG. 2 is a schematic cross-sectional view of the drive interrupting means 20 according to the present embodiment.

  The drive interrupting means 20 includes a drive input gear 21, an input side rotating shaft 22, a drive output gear 23, a drive interrupting part 24, and an urging spring 25 as an urging means.

  The drive input gear 21, the input-side rotary shaft 22, and the drive intermittent portion 24 are provided so as to be rotatable while being fixed to each other in the direction of the rotation center axis P in FIG. The drive transmission part of the 2nd drive transmission means which concerns on this invention is comprised.

  The drive output gear 23 is arranged so as to be movable in the axial direction (thrust direction) on the input side rotary shaft 22 and to be rotatable with respect to the input side rotary shaft 22. The drive transmission part of the 1st drive transmission means which concerns on this invention is comprised.

  The urging spring 25 is loosely inserted into the shaft portion 22b of the input-side rotating shaft 22 in the circumferential direction of the shaft portion 22b, and urges the drive output gear 23 to the drive intermittent portion 24. It is configured in a pressure contact state.

  The drive interrupting portion 24 and the drive output gear 23 are provided with projections (projection-like portions) 23c and 24c.

  FIG. 3A is a schematic view of the projection 23c of the drive output gear 23 as seen from the front, and is a view seen from the right side of FIG. FIG. 3B is a perspective view showing an overview of the drive output gear 23.

  The protrusion 23c has a predetermined amount of undulation in the axial direction of the imaginary rotation axis, which is the center of the rotation, according to the phase in the rotation direction of the drive output gear. In addition, the protrusion 23c is configured to substantially mesh with the protrusion 24c of the drive interrupting portion 24 in a predetermined phase.

  FIG. 4A is a schematic view of the drive interrupting portion 24 when the protrusion 24c of the drive interrupting portion 24 is seen from the front, and is a view seen from the left side of FIG. FIG. 4B is a perspective view showing an overview of the drive interrupting portion 24.

  The protrusion 24c has a predetermined undulation amount in the axial direction of the virtual rotation axis, which is the center of the rotation, according to the phase in the rotation direction of the drive interrupting portion 24. Further, the protrusion 24c is configured to substantially mesh with the protrusion 23c of the drive output gear 23 in a predetermined phase.

  When the sheet conveying roller 26a conveys a sheet, the load rotational force applied to the sheet conveying roller 26a is transmitted to the drive transmitting means 17 from the driving means (not shown), so that the driving torque T1 is driven. Rotational driving force that can be transmitted to the conveying roller 26a when the intermittent means 20 is rotated by the driving means (not shown) in the direction in which the sheet S is conveyed (hereinafter, this rotational direction is referred to as a normal rotation direction). , That is, the upper limit value of the transmission driving rotational force is T2.

  At this time, the set value of T2 can be determined by changing the shapes of the protrusion 23c of the drive output gear 23 and the protrusion 24c of the drive intermittent portion 24.

  In FIG. 4A, when the drive interrupting portion 24 rotates in the clockwise direction ahead of the drive output gear 23, as long as the rotational driving force applied to the drive interrupting portion 24 is equal to or less than T2. Since the drive output gear 23 is rotated counterclockwise in FIG. 3A, the rotational drive force can be transmitted to the gears 17d, 17e, 17f, 26c ahead of the drive output gear 23. The conveyance roller pair 26 can be rotated.

  Here, immediately before at least one of the members constituting the drive transmission means 17 is broken (damaged), the rotational driving force transmitted from the drive means to the transport roller 26a is T3, and T2 is It is set to be smaller than T3.

  On the other hand, when the driving force is transmitted from the driving unit to the driving transmission unit 17 in a direction opposite to the direction in which the conveying roller 26a conveys the sheet S (hereinafter, this rotational direction is referred to as a reverse direction). The maximum value of the rotational driving force that can be transmitted to the transport roller 26a is T4. In T4, when the conveying roller 26a is rotated in the normal rotation direction while the driving unit is stopped, the driving intermittent unit 20 transmits the rotational driving force to the driving unit. It is equivalent to the state when cutting.

  As described above, in FIG. 3A, the drive output gear 23 rotates counterclockwise in advance of the drive interrupting portion 24, or in FIG. When rotating in the counterclockwise direction prior to the output gear 23, a rotational driving force greater than T4 is applied, so that the (first) gentle slope of the gentle slope of the projection 23c of the output gear 23 is applied. The output gear 23 is separated from the drive interrupting portion 24 by sliding the portion 23d and the (second) gentle slope portion 24d of the gentle slope of the projection 24c of the drive interrupting portion 24, and the respective projections When the first top portion 23e and the second top portion 24e, which are the apexes of the portions 23c and 24c, are overcome, they are brought into pressure contact with the drive interrupting portion 24 again. By repeating this, the rotational driving force is canceled by the driving intermittent means 20. The first top portion 23e and the second top portion 24e are provided between the gentle slope portion and the steep slope portion, respectively, and have a flat portion as shown in the figure. And a steep slope portion may be formed into a ridge shape. Further, one of the first steep slope portion 23f of the output gear 23 and the first steep slope portion 24f of the drive interrupting portion 24 is connected to the first top portion 23e, FIG. 3 (a) or FIG. 4 (a). The rotational driving force T2 may be increased by configuring the second apex portion 24e so as to be substantially perpendicular to the surface of the second apex portion 24e so as to strike a wedge against the opposing steep slope.

  The set value of T4 is determined by changing the shape of the protrusion 23c of the drive output gear 23 and the protrusion 24c of the drive interrupting portion 24 in the same manner as T2. Can do. Note that it is desirable that T4 is considerably smaller than T2.

[Operation of fixing device]
FIG. 5 is a schematic diagram illustrating a fixing operation in the fixing device 130.

  When the fixing operation is performed in the fixing device 130, the following operation is performed.

  When an alternating current is supplied to the heating means 11 disposed in the hollow cylindrical portion of the fixing film 10, heat is generated and heated to a temperature required for fixing an unfixed toner image. Here, the temperature is detected by a temperature detection unit (not shown), for example, a thermistor that is in contact with or close to the inner periphery of the fixing film 10 to control the temperature of the fixing film 10. Yes.

The pressure roller 12 is rotated by the gear 17b by receiving the rotational driving force of the drive transmission means 17 from the driving means (not shown).

  The conveying roller pair 26 includes a rotational driving force within a predetermined range described later in the driving transmission unit 17 and a part of the driving transmission unit 17 among the power from the driving unit (not shown). The sheet S is rotated by being received by the gear 26c through the drive interrupting means 20, and the sheet S is discharged to the outside of the fixing device.

[Operations of Drive Transmission Means and Drive Intermittent Means]
6 to 9 are schematic diagrams showing the operation of the drive transmission means 17 and the drive interrupting means 20 in each state, and the operation in each state will be described using this.

(A) At the time of sheet conveyance FIG. 6 is a schematic diagram showing the operation of the drive transmission means 17 and the drive interrupting means 20 at the time of sheet conveyance.

  The rotational driving force in the forward rotation direction generated by the driving means (not shown) is transmitted to the gear 17a, and then transmitted to the gears 17b and 17c and the driving intermittent means 20.

  At this time, as shown in the configuration of the drive interrupting means 20, if the applied rotational driving force corresponds to T2 or less, it is transmitted from the drive interrupting means 20 to the gears 17d, 17e, 17f, 26c. Then, the pressure roller 12 provided with the gear 17b and the conveying roller 26a provided with the gear 26c are rotated.

  The rotational driving force (torque) transmitted to the conveying roller 26a at this time is T1 required for the fixing device 130 to convey the sheet S.

(B) When a sheet is jammed in the state where the sheet is close to the conveying roller pair FIG. FIG. 6 is a schematic diagram showing the operation of the drive transmission means 17 and the drive interrupting means 20 in the case of having been performed.

  The rotational driving force in the forward rotation direction generated by the driving means (not shown) is transmitted to the gear 17a, and then transmitted to the gears 17b, 17c, the drive interrupting means 20, and the gears 17d, 17e, 17f, 26c. The pressure roller 12 provided with the gear 17b is rotated, but the conveying roller 26a provided with the gear 26c is in a state in which it does not rotate because of a braking force. At this time, the load applied to the drive transmission means 17 is larger than that during the sheet conveyance, so the rotational driving force acting on the gear 26c is greater than T1.

  The conveying roller 26a is maintained in the non-rotating state, and the rotational driving force continues to act on the gear 26c, and the magnitude of the rotational driving force (torque) acting on the gear 26c is a predetermined value (place (Or when the load of the drive interrupting portion 24 on the drive output gear 23 exceeds a predetermined value (predetermined amount)), between the drive output gear 23 and the drive interrupting portion 24 Then, when the (first) steep slope portion 23f of the projection 23c of the drive output gear 23 and the (second) steep slope portion 24f of the drive interrupting portion 24 slide, the output gear 23 is connected to the drive interrupting portion. Go away from 24. When the time T2 is exceeded, the protrusions 23c and 24c get over the respective apexes (the first top 23e and the second top 24e), and then the drive output gear 23 is again brought into pressure contact with the drive interrupting portion 24. . This is sequentially repeated, and the drive interrupting means 20 interrupts transmission of the rotational driving force. For this reason, the rotational driving force transmitted to the drive transmission means 17 does not reach T3 at which the drive means 17 breaks down.

(C) When the fixing device is stopped in a state where the sheet is held between the pair of conveying rollers. FIG. 8 is a diagram in which the sheet S is configured by pressing the fixing film 10 and the pressure roller 12 together. FIG. 6 is a schematic diagram illustrating an operation when the sheet S is pulled out downstream in the sheet conveying direction in a state where the sheet S completely stops passing through the nip N and is held between the conveying roller pairs 26.

  When the sheet S is pulled out, the transport roller 26a rotates in the forward rotation direction, so that a rotational driving force is transmitted from the gear 26c to the gears 17f, 17e, 17d and the output gear 23 of the drive interrupting means 20. .

  On the other hand, a rotational driving force is transmitted from the drive input gear of the drive interrupting means 20 to the drive means (not shown) via the gears 17c, 17b, 17a. The illustrated driving means maintains a stationary state.

  In this case, since the drive output gear 23 rotates counterclockwise prior to the drive interrupting portion 24, between the drive output gear 23 and the drive interrupting portion 24, as in the above case, The output gear 23 moves away from the drive interrupting portion 24 by sliding the gentle slope portion 23d of the projection 23c of the output gear 23 and the gentle slope portion 24d of the projection 24c of the drive interrupting portion 24. Go. Eventually, when the rotational force applied to the transport roller 26a exceeds T4, the top of the protrusions 23c and 24c is overcome, and then it is pressed against the drive interrupting portion 24 again. This is sequentially repeated, and the drive interrupting means 20 interrupts transmission of the rotational driving force.

  For this reason, even when the driving means (not shown) is kept stationary, the force when pulling out the sheet S can be suppressed within the range of the force according to T4.

(D) When the fixing device is stopped while the sheet is sandwiched between the conveying roller pair and the fixing device. FIG. 9 is configured by pressing the fixing film 10 and the pressure roller 12 on the sheet S. FIG. 6 is a schematic diagram illustrating an operation when the sheet S is pulled out downstream in the sheet conveyance direction in a state where the sheet S is nipped by the nip N and stopped while being nipped by the conveyance roller pair 26.

  The sheet S stays between the nip N formed by press-contacting the fixing film 10 and the pressure roller 12 and the conveying roller pair 26, and the sheet discharge detection unit 136 appropriately detects the sheet S. When the discharge cannot be detected, the conveyance of the sheet S of the printer 170 is stopped. Then, the driving means (not shown) is driven in the opposite direction to transmit the driving force to the separating means 16 so that the fixing film 10 is separated from the pressure roller 12 by a predetermined distance.

  When the sheet S is pulled out, since the nip N of the sheet S held in the nip N is eliminated, the force required to pull out the sheet S only needs to overcome the rotational drag received from the conveying roller pair 26.

  When pulling out the sheet S, the drive interrupting means 20 cuts off the drive transmission when the rotational force applied to the transport roller 26a reaches T4, as in (c) above. For this reason, even when the driving means (not shown) is kept stationary, the force when pulling out the sheet S can be suppressed within the range of the force according to T4.

As a result of the operations of the drive transmission means 17 and the drive interrupting means 20 as described above, a jam occurs at a position where the sheet S is close to the conveyance roller pair 26, or foreign matter is inserted in the vicinity of the conveyance roller 26. Even when the conveying roller pair 26 is stopped, it is possible to prevent the drive transmission means 17 from changing to a state in which it is destroyed.

  Further, the drive interrupting means 20 can freely determine the predetermined setting values T2 and T4 for determining the conditions to be used, for example, the driving interrupt, so that the applicable range of the drive interrupting means 20 is widened. be able to.

  Further, even when a jam occurs in a state where the sheet S is nipped by the nip N, the separation unit 16 that eliminates the nip N is operated to break the jammed sheet S and to fix the printer main body 171 or the fixing unit. The sheet S can be pulled out with a slight force without leaving the damaged sheet S inside the apparatus 130, and the jam handling performance of the user can be greatly improved.

  As described above, according to the present embodiment, a function element (mainly a main element) is newly provided in the drive transmission means by providing a function as a drive interrupting means for interrupting driving according to the rotation direction and the rotational driving force. In addition, it is not necessary to add a clutch, a torque limiter, or the like), so that an increase in cost due to the addition of the element can be prevented.

  At the same time, since the respective functions are integrated into one means, an increase in the size of the apparatus main body can be prevented.

  Further, the action of the drive interrupting means requires less force when the user pulls out the jam sheet, and further, it is possible to eliminate the necessity of secondary work due to jam sheet breakage or the like, so that jam processing is forced. The load can be reduced.

  Furthermore, when a braking force is applied to the sheet conveying rotating body and an excessive driving force is applied to the drive transmission means, the excessive driving force can be canceled by the action of the drive interrupting means. The breakage of the means and the fixing device can be prevented.

  Note that the fixing device 130 according to the present embodiment is merely an example of the present invention. The scope of the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the technical idea. For example, instead of using a fixing film as fixing means, a fixing roller may be used.

  Further, not only a plurality of gears but also a belt, a pulley, a chain, a friction wheel, or the like may be used as the drive transmission means. Furthermore, since the conveyance roller pair 26 and the pressure roller 12 are driven independently, a plurality of driving means may be provided. This is effective when it is necessary to increase the distance between the fixing film 10 and the pressure roller 12, and it is desirable to reduce the number of gears of the drive transmission means 17 as much as possible even if the number of conveyance roller pairs is increased.

  In this embodiment, the sheet conveyance in the fixing device 130 has been described. However, the present invention is not limited to this, and the present invention is preferably applied to any sheet conveyance device including the drive transmission unit 17 and the conveyance roller pair 26. Is possible. Further, the sheet conveying apparatus is not limited to the configuration of the conveying roller pair 26, and may be any apparatus having a function of conveying a sheet. For example, the above-described sheet conveyance device may be applied to the fixing unit, that is, the pressure roller 12 may correspond to the conveyance roller pair 26 driven by the drive transmission unit 17.

1 is a longitudinal sectional view illustrating a schematic configuration of a fixing device according to an embodiment of the present invention. It is sectional drawing which shows schematic structure of the drive interruption means of embodiment of this invention. It is the schematic of the drive interruption part with which the drive interruption means of embodiment of this invention was equipped. It is the schematic of the output gear with which the drive intermittent means of embodiment of this invention was equipped. FIG. 6 is a schematic diagram illustrating a fixing operation in the fixing device according to the embodiment of the present invention. It is the schematic diagram which showed each operation | movement of the drive transmission means and drive intermittent means of embodiment of this invention. It is the schematic diagram which showed each operation | movement of the drive transmission means and drive intermittent means of embodiment of this invention. It is the schematic diagram which showed each operation | movement of the drive transmission means and drive intermittent means of embodiment of this invention. It is the schematic diagram which showed each operation | movement of the drive transmission means and drive intermittent means of embodiment of this invention. 1 is a longitudinal sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. It is the top view which showed the prior art example.

Explanation of symbols

N nip S sheet 10 fixing film 11 heating means 12 pressure roller 14 pressure spring 16 cam (separation means)
17a to 17f gear (drive transmission means)
20 Clutch unit with gear (drive intermittent means)
21 Drive Input Gear 23 Drive Output Gear 23c Projection 24 Drive Intermittent 24c Projection 25 Biasing Spring 26 Conveying Roller Pair 130 Fixing Device 170 Full Color Laser Beam Printer (Image Forming Device)

Claims (13)

A sheet conveying rotating body that conveys the sheet in the sheet conveying direction;
Drive transmission means for transmitting the rotational driving force from the drive means to the sheet conveying rotator for conveying the sheet by the sheet conveying rotator;
In a sheet conveying apparatus comprising:
The drive transmission means includes at least first drive transmission means for transmitting rotational driving force between drive transmission portions provided in each of the drive transmission means, and second drive transmission means on the drive means side of the first drive transmission means. ,
Provided in the drive transmission portion provided to each of the first drive transmission means and the second drive transmission means, the direction of the relative rotation between the first drive transmission means and the second drive transmitting means any Even in this case , based on the magnitude of the rotational driving force acting between the first drive transmission means and the second drive transmission means, the distance between the first drive transmission means and the second drive transmission means. Drive intermittent means for intermittently transmitting the rotational driving force ,
The drive transmission portions of the first drive transmission means and the second drive transmission means are opposed to each other in the axial direction of the rotation axis of the transmitted rotation, and protrude in the axial direction at a position shifted from the rotation center. Provided to have a protrusion and rotate on the same axis,
At least one of the drive transmission portions is provided so as to be movable in the axial direction, and is pressed against the other of the drive transmission portions by the urging force of the urging means, and the protruding portions mesh with each other in the rotation direction. Thereby, transmission of the rotational driving force between the first drive transmission means and the second drive transmission means is performed,
The engagement state of the protrusions is released by separating the drive transmission portions from each other against the urging force of the urging means, so that the first drive transmission means and the second drive transmission means A sheet conveying apparatus characterized in that the transmission of the rotational driving force is interrupted .   The drive interrupting means is detachably provided between the drive transmission parts, and the engagement state between the drive transmission parts is released, so that the first drive transmission means and the second drive transmission means The sheet conveying apparatus according to claim 1, wherein transmission of rotational driving force between the two is interrupted. The protruding portion of the drive transmission portion provided in the first drive transmission means is
A first apex;
A first gentle slope portion provided so as to reduce the amount of undulation in the axial direction toward the rotation direction in which the drive transmission portion rotates so that the sheet is conveyed from the first top in the sheet conveyance direction;
A first steep slope portion provided so as to reduce the amount of undulation from the first top toward the direction opposite to the rotation direction;
The protruding portion of the drive transmission portion provided in the second drive transmission means is
A second apex;
A second steep slope portion provided so as to reduce the undulation amount in a rotation direction in which the drive transmission portion rotates so that the sheet is conveyed in the sheet conveyance direction from the second top portion;
A second gentle slope portion provided so as to reduce the amount of undulation from the second top to the direction opposite to the rotational direction,
When the first steep slope portion and the second steep slope portion are in pressure contact and rotate, transmission of rotational driving force is performed,
When the first steep slope portion and the second steep slope portion slide, the rotational transmission force is transmitted by moving the drive transmission portion away from the biasing force of the biasing means. Is shut off,
When the first gentle slope portion and the second gentle slope portion slide, a rotational driving force is generated by moving the drive transmission portion away from the biasing force of the biasing means. sheet conveying apparatus according to claim 1 or 2 transfer is characterized in that it is cut off. One of the first steep slope and a second steep slope, any one of claim 3, characterized in that by forming a substantially vertical plane wherein the first top portion, or the second top portion Sheet conveying device. In the first case where the load applied from the second drive transmission means to the first drive transmission means exceeds a predetermined amount, the first steep slope portion and the second steep slope portion slide to cause rotational driving force. Is interrupted,
In the second case where the second drive transmission means rotates relative to the first drive transmission means in a direction opposite to the rotation direction when the sheet is conveyed in the sheet conveyance direction, sheet conveying device according to claim 3 or 4, characterized in that transmission of the rotational driving force is cut off by the first and gentle slope portion and the second gentle slope slides. In the first case, the drive means in the drive transmission means and the second drive transmission means so that the sheet is conveyed in the sheet conveyance direction when the first drive transmission means is in a substantially stopped state. And the rotational driving force is transmitted between
In the second case, the first drive transmission means and the sheet conveyance in the drive transmission means so that the sheet is conveyed in the sheet conveyance direction when the second drive transmission means is in a substantially stopped state. The sheet conveying device according to claim 5 , wherein a rotational driving force is transmitted to and from the rotating body for use. When the sheet is conveyed in the sheet conveying direction by the sheet conveying rotator, a load rotational force applied to the sheet conveying rotator is transmitted to T1 by being transmitted from the driving unit to the drive transmitting unit.
The maximum value of the rotational driving force that can be transmitted to the rotating member for sheet conveyance when the driving intermittent means transmits the rotational driving force so that the sheet is conveyed in the sheet conveying direction by the rotating member for sheet conveyance. Is T2,
Of the rotational driving force transmitted from the driving means to the sheet conveying rotator, the rotational driving force when the drive transmitting means is damaged is T3,
When a rotational driving force is transmitted from the driving means to the sheet conveying rotator so that the sheet is conveyed in a direction opposite to the sheet conveying direction by the sheet conveying rotator, the sheet conveying rotator is transmitted to the sheet conveying rotator. When the maximum value of the rotational driving force that can be transmitted is T4,
T4 <T1 <T2 <as T3 becomes relation is established, the sheet conveying device according to any one of claims 1 to 6, characterized in that the shape of the projecting portion is determined. Sheet conveying device according to any one of claims 1 to 6, characterized in that it comprises at least one further rotary member for conveying the sheet by the driving force from the driving means is transmitted by said drive transmitting means. A sheet conveying device according to any one of claims 1 to 8 ,
A fixing unit provided so that a driving force from the driving unit is transmitted by the driving transmission unit on the upstream side of the sheet conveying rotating body, and fixes an unfixed toner image formed on the sheet to the sheet; ,
A fixing device comprising: The fixing unit is provided so that the driving force from the driving unit is transmitted by the second driving transmission unit, and
A pressure unit that presses against the fixing unit in order to sandwich and convey the sheet at the nip with the fixing unit;
Release means for eliminating the contact state between the fixing means and the pressure means;
The fixing device according to claim 9 , further comprising: A sheet conveying rotating body that conveys the sheet in the sheet conveying direction;
Drive transmission means for transmitting the rotational driving force from the drive means to the sheet conveying rotator for conveying the sheet by the sheet conveying rotator,
The drive transmission means includes at least first drive transmission means for transmitting rotational driving force between drive transmission portions provided in each of the drive transmission means, and second drive transmission means on the drive means side of the first drive transmission means. ,
Which is provided in the drive transmission portion provided in each of the first drive transmission means and the second drive transmission means, and the relative rotational direction between the first drive transmission means and the second drive transmission means is any Even in this case, based on the magnitude of the rotational driving force acting between the first drive transmission means and the second drive transmission means, the distance between the first drive transmission means and the second drive transmission means. Drive intermittent means for intermittently transmitting the rotational driving force,
Fixing is provided so that the driving force from the driving means is transmitted by the second drive transmission means on the upstream side of the sheet conveying rotator, and the unfixed toner image formed on the sheet is fixed on the sheet. Means,
A pressure unit that presses against the fixing unit in order to sandwich and convey the sheet at the nip with the fixing unit;
Release means for eliminating the contact state between the fixing means and the pressure means;
A fixing device comprising: A first sheet detecting unit that is provided upstream of the fixing unit in the sheet conveying direction and detects a sheet;
A second sheet detecting means provided on the downstream side of the fixing means in the sheet conveying direction for detecting a sheet;
With
When the sheet is not detected by the second sheet detecting means by a predetermined time after the sheet is detected by the first sheet detecting means, the releasing means makes contact between the fixing means and the pressing means. The fixing device according to claim 10 or 11 , wherein the state is canceled. Image forming means for forming a toner image on a sheet;
A fixing device according to any one of the image forming unit according to claim 9-12 for fixing the formed toner image to a sheet by,
An image forming apparatus comprising:

Images