JP2018140529A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means for suppressing damaging of a cutting member when an opening/closing section is closed with respect to a device body.SOLUTION: An image forming apparatus includes a cutting section. The cutting section has a body section having a rotary blade and a counter blade performing cutting by sandwiching a printing medium between the counter blade and the rotary blade. The body section has a rotary blade shaft gear mounted in a rotary shaft of the rotary blade, a load member for applying a load to rotation of the rotary blade, and driving transmission switching means for switching connection or disconnection of the transmission of driving to the rotary blade shaft gear. The driving transmission switching means has a gear and transmits driving to the rotary blade shaft gear via a driven gear which comes into contact with or separates from the rotary blade shaft gear. Torque required for rotation of the rotary blade shaft gear is set to be larger than torque required for rotation in a state that the driving transmission means is disconnected.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an image forming apparatus having a cutter unit for cutting a print medium.

  A conventional image forming apparatus can switch a cutting operation member that drives a tape cutting device between an inoperable state and an operable state in conjunction with an opening / closing operation of the apparatus main body by a lid member. By making the cutting operation member inoperable when it is opened, the tape cutting device is prevented from operating unexpectedly even when the cutting operation member is operated by mistake with the lid member opened. (For example, refer to Patent Document 1).

JP 2009-220417 A

However, in the conventional technology, when the lid member as the opening / closing portion is opened from the apparatus main body, the connection between the cutting member and the lid member is cut off. Therefore, when the lid member is opened from the apparatus main body. The connecting member moves, and the rotary blade as the cutting member does not stop at a fixed position, and there is a problem that the cutting member may be damaged when the lid member is closed with respect to the apparatus main body. .
This invention makes it a subject to solve such a problem, and it aims at suppressing that a cutting member is damaged.

  Therefore, the present invention is an image forming apparatus having a cutting unit for cutting a print medium, wherein the cutting unit is opposed to the main unit having a rotary blade and the print blade sandwiched between the rotary blade. A blade, a rotary blade shaft gear attached to a rotary shaft of the rotary blade, a load member that applies a load to the rotation of the rotary blade, and a drive for driving the rotary blade shaft gear. Drive transmission switching means for switching connection or disconnection of transmission, and the drive transmission switching means has a gear, and the rotary blade shaft via a driven gear that contacts or separates from the rotary blade shaft gear. The torque necessary for transmitting the drive to the gear and rotating the rotary blade shaft gear is set to be larger than the torque necessary for the drive transmission switching means to rotate in the cut state. To do.

  According to the present invention thus configured, it is possible to prevent the cutting member from being damaged.

External perspective view of image forming apparatus in embodiment Schematic side sectional view showing formation of image forming apparatus in embodiment Sectional drawing which shows the structure of the closed cutter unit in an Example Sectional drawing which shows the structure of the open cutter unit in an Example The perspective view of the open cutter unit in an Example The perspective view of the closed cutter unit in an Example The perspective view of the cutter shaft gear in an Example Explanatory drawing which shows the structure of the cutter shaft gear and detent lever in an Example Explanatory drawing of an effect | action of the detent lever in an Example Explanatory drawing of the torque for rotating the cutter shaft gear in the embodiment Explanatory drawing of the torque for rotating the cutter shaft gear in the embodiment Explanatory drawing which shows the structure of the cutter shaft gear and detent lever in a modification.

  Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings.

  FIG. 1 is an external perspective view of an image forming apparatus according to the embodiment, and FIG. 2 is a schematic side sectional view showing formation of the image forming apparatus according to the embodiment.

  In FIG. 1 and FIG. 2, an image forming apparatus 1 is a roll paper printer having an image forming unit using, for example, an electrophotographic method, and has a substantially box-shaped casing 2 and roll paper as a printing medium. It has a cutter unit 26 for cutting. The left side of the housing 2 in the drawing is the front surface, the right surface in the drawing is the rear surface, the direction from the rear surface to the front surface of the housing 2 is the front direction, the direction from the front surface to the rear surface is the rear direction, and the housing 2 The direction from the lower side to the upper side is the upward direction, the direction from the upper side to the lower side is the downward direction, the direction from the front side to the back side in the figure of the housing 2 is the left direction, and The direction toward you is the right direction.

A roll paper storage unit 3 for storing roll paper wound in a columnar shape is provided on the front side of the casing 2.
Further, a cover 6 that covers the roll paper storage unit 3 is attached to the top of the housing 2 on the front side thereof.

The image forming apparatus 1 stores cylindrical roll paper in a cylindrical space formed by the storage space of the roll paper storage unit 3 and the space inside the closed cover 6.
The roll paper storage unit 3 is provided with a storage unit side conveyance roller 9 and a cover side conveyance roller 11 at the upper front end of the storage space. When the cover 6 is closed, the cover-side transport roller 11 is in contact with the storage unit-side transport roller 9 so that the roll-side paper can be sandwiched and transported.

Inside the housing 2 of the image forming apparatus 1, it extends from the front end of the roll paper storage unit 3 to the rear end of the roll paper storage unit 3 along the lower side of the roll paper storage unit 3. A conveyance path 21 that is connected to the roll paper discharge port 20 via 22, 23, 24, 25, and 33 is provided.
The conveyance path 21 is a path for conveying the roll paper stored in the roll paper storage unit 3 to the roll paper discharge port 20 in the medium conveyance direction indicated by the arrow A in the figure, and the roll paper storage unit 3 side is upstream in the medium conveyance direction. The roll paper discharge port 20 side is the downstream side in the medium conveyance direction.

The conveyance roller pairs 22, 23, 24, 25, and 33 are roller pairs that sandwich and convey the roll paper, and sequentially from the upstream side of the conveyance path 21, the conveyance roller pair 22, the conveyance roller pair 23, and the conveyance roller pair 24. A conveying roller pair 25 and a conveying roller pair 33 are arranged.
A cutter unit 26 for cutting roll paper is disposed between the conveyance roller pair 24 and the conveyance roller pair 25. The configuration of the cutter unit 26 will be described later.

In addition, image forming units 27 a, 27 b, and 27 c are disposed in the conveyance path 21 between the conveyance roller pair 25 and the conveyance roller pair 33.
The image forming units 27 a, 27 b, and 27 c form toner images as developers of a plurality of colors (for example, three colors), and sequentially from the upstream side of the conveyance path 21, the image forming unit 27 a and the image forming unit. 27b and the image forming unit 27c are arranged side by side. The image forming units 27a, 27b, and 27c are attached with waste toner storage units 28a, 28b, and 28c that store the waste toner collected from the respective image forming units 27a, 27b, and 27c.

  The image forming unit 27 (27a, 27b, 27c) forms a toner image as a developer image using an electrophotographic system. The image forming unit 27 includes a photosensitive drum 30 (30a, 30b, 30c) as a rotatable image carrier and a charging roller 35 (35a, 35b) as a charging unit that uniformly charges the surface of the photosensitive drum. 35c), an exposure device 36 (36a, 36b, 36c) as exposure means for selectively irradiating light onto the surface of the charged photosensitive drum 30 to form an electrostatic latent image, and a photosensitive drum The image forming apparatus includes a developing unit 60 that transports toner as a developer to the formed electrostatic latent image to form a toner image.

The developing unit 60 includes a developing roller 64 (64a, 64b, 64c) as developing means for conveying toner as a developer to the electrostatic latent image formed on the photosensitive drum 30, and a developing roller 64 (64a, 64b, 64c) and a supply roller 63 (63a, 63b, 63c) as developer supply means for supplying toner.
An annular transfer belt 29 extending in the front-rear direction along the conveyance path 21 and transfer rollers 31a, 31b, and 31c are provided below the image forming units 27a, 27b, and 27c.

The transfer rollers 31a, 31b, and 31c are disposed at positions facing the photosensitive drums 30a, 30b, and 30c of the image forming units 27a, 27b, and 27c with the transfer belt 29 interposed therebetween.
In the conveyance path 21, a fixing device 32 is provided on the downstream side of the transfer belt 29, and a conveyance roller pair 33 is provided on the downstream side of the fixing device 32 in the vicinity of the roll paper discharge port 20.

The roll paper storage unit 3, the cover 6, the cover-side transport roller 11, and the transport roller pairs 22, 23 are disposed on an upper surface cover that can be opened and closed with respect to the apparatus main body. Is disposed on the apparatus main body side.
The roll paper is conveyed by a pair of conveyance rollers 22, 23, 24, and 25, cut by a cutter unit 26, and conveyed to a transfer portion formed by a transfer belt 29 and transfer rollers 31a, 31b, and 31c. The toner images formed in the image forming units 27a, 27b, and 27c are transferred by the transfer unit to form an image.

The roll paper on which the image is formed is conveyed to the fixing device 32 to fix the toner image, and is discharged out of the apparatus by the conveying roller pair 33.
When the roll paper is jammed in the vicinity of the cutter unit 26, the jam release cover 262 is rotated with respect to the apparatus main body in the direction indicated by the arrow C in the figure to open the conveyance path 21, thereby removing the jammed roll paper. It can be removed.

3 is a cross-sectional view showing the configuration of the closed cutter unit in the embodiment, FIG. 4 is a cross-sectional view showing the configuration of the opened cutter unit in the embodiment, FIG. 5 is a perspective view of the opened cutter unit in the embodiment, and FIG. FIG. 3 is a perspective view of a closed cutter unit in the embodiment.
First, an outline of the cutter unit will be described with reference to FIGS.

As shown in FIG. 5A, a cutter unit 26 as a cutting unit includes a main body unit 261, a jam release cover 262, a rotary blade 263 as a cutting member, a counter blade 264, a conveying roller pair 24, and a conveying roller. A roller pair 25 is provided.
A main body unit 261 as a main body portion includes a rotatable rotary blade 263. Further, the jam release cover 262 as an opening / closing portion includes an opposing blade 264 that cuts with a roll paper sandwiched between the rotating blade and a rotating blade.

The facing blade 264 is a blade disposed so as to face the rotating blade 263, and is preferably fixed to the jam release cover 262.
The jam release cover 262 is supported by the main body unit 261 so as to be rotatable about axes (shafts 269a and 269b shown in FIG. 6B), and is configured to be openable and closable with respect to the main body unit 261.

Therefore, by rotating the jam release cover 262 and opening it with respect to the main body unit 261, the counter blade 264 is separated from the rotary blade 263 and closed with respect to the main body unit 261, thereby rotating with the counter blade 264. The blade 263 approaches.
Further, the main body unit 261 is provided with one conveyance roller of the conveyance roller pair 24 and the conveyance roller pair 25, and the jam release cover 262 is provided with the other conveyance roller of the conveyance roller pair 24 and the conveyance roller pair 25.

Accordingly, the roll paper transport path can be opened or closed by rotating the jam release cover 262 and opening it to the main body unit 261.
As shown in FIG. 5 (b), the jam release cover 262 has lock levers 270a and 270b protruding toward the main unit 261, and the main unit 261 has a hole into which the distal ends of the lock levers 270a and 270b are fitted. 271a and 271b are formed, and the lock lever 270a is engaged with the hole 271a and the lock lever 270b is engaged with the hole 271b, so that the jam release cover 262 can be kept closed with respect to the main body unit 261. It has become.

  Further, as shown in FIG. 5C, the lock levers 270a and 270b are urged in the direction indicated by the arrow Y in the drawing by springs 272a and 272b as urging members, and the holes 271a shown in FIG. , 271b, that is, the jam release cover 262 shown in FIGS. 6A and 6B can be kept closed with respect to the main unit 261.

  Next, the drive configuration of the rotary blade 263 will be described with reference to FIGS.

  As shown in FIGS. 3 and 4, the body unit 261 is provided with a cutter shaft gear 267, a clutch 268, and a detent lever 276, and the jam release cover 262 is provided with an idle gear 265. . In addition, although teeth (gear) are formed on the outer periphery of the cutter shaft gear 267, the clutch 268, and the idle gear 265, the teeth (gear) are omitted in the following drawings including FIG. 3 and FIG. .

  The cutter shaft gear 267 as the rotary blade shaft gear is attached to the end of the rotary shaft 263a of the rotary blade 263 (see FIG. 5) and rotates together with the shaft of the rotary blade 263. The cutter shaft gear 267 rotates in the cutting direction indicated by the arrow B in FIG. 3 to rotate the rotary blade 263 to cut the roll paper. The cutter shaft gear 267 is configured to be rotatable only in the cutting direction indicated by the arrow B in FIG. 3, and is regulated by a regulating member so as not to rotate in the direction opposite to the cutting direction.

The clutch 268 as the drive transmission switching means is, for example, an electromagnetic clutch, and is provided on the downstream side of the cutter shaft gear 267 in the medium conveyance direction. The clutch 268 has a rotating gear and switches connection and disconnection between the gear and a drive source such as a motor, that is, switches connection and disconnection of drive transmission to the cutter shaft gear 267.
As shown in FIG. 3, the idle gear 265 as a driven gear is disposed between the cutter shaft gear 267 and the clutch 268, meshes with the cutter shaft gear 267 and the clutch 268, and drives the clutch 268 from the gear. This is transmitted to the cutter shaft gear 267.

Drive of the gear of the clutch 268 and the cutter shaft gear 267 is transmitted via the idle gear 265.
The detent lever 276 serving as a load member applies a load to the rotation of the rotary shaft 263a of the rotary blade 263 (see FIG. 5).

  Further, since the idle release gear 265 is provided in the jam release cover 262, when the jam release cover 262 is rotated and opened with respect to the main body unit 261 as shown in FIG. When separated from the cutter shaft gear 267 and closed with respect to the main unit 261 as shown in FIG. 3, the idle gear 265 comes into contact with and meshes with the gear of the clutch 268 and the cutter shaft gear 267.

As shown in FIG. 4, a gap 266 is formed between the gear of the clutch 268 and the cutter shaft gear 267.
As described above, the clutch 268 transmits driving to the cutter shaft gear 267 through the idle gear 265 that contacts or separates from the cutter shaft gear 267 as the jam release cover 262 rotates.

  7 is a perspective view of the cutter shaft gear in the embodiment, FIG. 7A is a perspective view of the entire cutter shaft gear, FIG. 7B is a perspective view of a drive gear portion of the cutter shaft gear, and FIG. ) Is a perspective view of the cam portion of the cutter shaft gear.

As shown in FIG. 7A, the cutter shaft gear 267 is provided at an end portion of the shaft of the rotary blade 263 (hereinafter referred to as “rotary blade shaft”) 263a, and includes a drive gear 267a, a sensor 273, and a light shield. Plate 274.
The drive gear 267a meshes with the idle gear 265 shown in FIGS.
The sensor 273 is an optical transmission sensor that detects the position of the rotary blade 263 by detecting the light shielding plate 274 that rotates together with the rotary blade shaft 263a.

The light shielding plate 274 is attached to the end side of the drive gear 267a of the rotary blade shaft 263a. The light shielding plate 274 rotates with the rotary blade shaft 263a and is formed in a substantially semicircular shape. The light shielding plate 274 blocks the optical axis between the light emitting unit and the light receiving unit of the sensor 273, and allows the light from the light emitting unit to enter the light receiving unit without blocking the light between the light emitting unit and the light receiving unit. is there.
The sensor 273 detects the position of the light shielding plate 274, thereby detecting the position of the rotary blade 263, for example, the initial position retracted from the conveyance path where the roll paper is conveyed, the position where the cutting of the roll paper is completed, or the like. It can be done.

  Further, as shown in FIGS. 7B and 7C, a cam 275 having a flat surface portion 275a is disposed between the drive gear portion 267a and the light shielding plate 274. As shown in FIG. 7A, the drive gear portion 267a, the light shielding plate 274, and the cam 275 are integrally attached to the rotary blade shaft 263a.

FIG. 8 is an explanatory diagram showing the configuration of the cutter shaft gear and the detent lever in the embodiment, and the cutter when the rotary blade 263 of the cutter unit 26 shown in FIG. 5 is disposed at the initial position retracted from the roll paper conveyance path. It is the figure which looked at the shaft gear from the axial direction.
As shown in FIG. 8, a detent lever 276 and a spring 277 that contact the cam 275 of the cutter shaft gear 267 are provided in the main unit 261 shown in FIGS.

The cam 275 is attached to the rotary blade shaft 263a, and a flat portion 275a that is a straight line is formed on a part of the outer periphery formed in a substantially circular shape when viewed from the axial direction.
The detent lever 276 is rotatably supported by a rotating shaft 276a, and has a contact surface 276b that comes into surface contact with the flat portion 275a of the cam 275. The detent lever 276 contacts the cam 275 and applies a load to the rotation of the rotary blade shaft 263a.

  The spring 277 as an urging member urges the detent lever 276 and urges the contact surface 276b of the detent lever 276 in the direction of the flat portion 275a of the cam 275 that is the direction of the rotary blade shaft 263a. Therefore, the contact surface 276b of the detent lever 276 is urged so as to contact the outer peripheral surface including the flat portion 275a of the cam 275.

By adjusting the urging force of the spring 277, the magnitude of torque necessary for the cutter shaft gear 267 to rotate can be adjusted.
In the present embodiment, the torque necessary for the cutter shaft gear 267 to rotate is set to be larger than the torque necessary for the clutch 268 shown in FIGS. 3 and 4 to rotate in the state where the drive transmission is disconnected.

Here, the arrangement of the detent lever 276 will be described.
A straight line passing through the center of the rotating shaft 276a of the detent lever 276 and the center of the rotating blade shaft 263a is J, and the rotation direction of the cutter shaft gear 267 divided by the straight line J with respect to the rotating shaft 276a (arrow B in the figure). When the upstream side Ja is the upstream region Ja and the downstream side is the downstream region Jb, the contact surface 276b of the detent lever 276 that is in surface contact with the flat portion 275a of the cam 275 is located in the upstream region Ja. A detent lever 276 is arranged as described above.

  That is, when the cutter shaft gear 267 rotates, the detent lever 276 is disposed so that the portion 275b of the flat portion 275a of the cam 275 that presses the contact surface 276b of the detent lever 276 is positioned in the upstream region Ja.

As described above, in this embodiment, the contact portion between the detent lever 276 and the cam 275 is a straight line passing through the rotation shaft 276a and the rotation blade shaft 263a, and the rotation direction of the cutter shaft gear 267 (rotation blade) (arrow in the figure). When the upstream (upstream region Ja) and the downstream (downstream region Jb) in the rotation direction indicated by B are separated, they are arranged upstream (upstream region Ja).
The operation of the above configuration will be described.

  First, the printing operation of the image forming apparatus will be briefly described with reference to FIG.

  The roll paper is set in the roll paper storage unit 3 with the leading end of the roll paper pulled out to the front of the roll paper storage unit 3 by the user. Thereafter, when the cover 6 is closed, the roll paper is sandwiched between the storage unit side conveyance roller 9 and the cover side conveyance roller 11.

  The image forming apparatus 1 rotates the storage unit side conveyance roller 9 with the roll paper sandwiched between the storage unit side conveyance roller 9 and the cover side conveyance roller 11, and each conveyance roller pair 22, 23, 24. , 25 and 33 are rotated, and the roll paper is conveyed to the transfer belt 29 along the conveyance path 21.

  The roll paper conveyed to the transfer belt 29 is conveyed by the transfer belt 29 and sequentially passes between the photosensitive drums 30a, 30b, and 30c of the image forming units 27a, 27b, and 27c and the transfer rollers 31a, 31b, and 31c. To do.

  At this time, the supply roller 63 (63a, 63b, 63c) of the developing unit 60 rotates to supply toner to the developing roller 64 (64a, 64b, 64c). The developing roller 64 (64a, 64b, 64c) to which the toner is supplied transports the toner to the photosensitive drums 30a, 30b, 30c, and forms toner images on the surfaces of the photosensitive drums 30a, 30b, 30c. Further, the toner images formed on the surfaces of the photosensitive drums 30a, 30b, and 30c are transferred to the printing surface of the roll paper.

The roll paper to which the toner image has been transferred is conveyed to the fixing device 32, and after the toner image is fixed by the fixing device, it is discharged from the roll paper discharge port 20 by the conveying roller pair 33.
The roll paper is cut to a predetermined length by the cutter unit 26, and the printed roll paper that has been cut to the predetermined length is discharged from the roll paper discharge port 20.

  At this time, as shown in FIG. 3, the clutch 268 of the cutter unit 26 is rotated by driving from a driving source such as a motor, and the driving is transmitted to the cutter shaft gear 267 via the idle gear 265, and the rotary blade 263 is rotated. Rotates. The roll paper is sandwiched between a rotating blade 263 and a counter blade 264, and is cut from an end portion in a direction substantially orthogonal to the medium conveyance direction.

  Next, the operation of the cutter unit when the jam release cover of the cutter unit is opened will be described with reference to FIGS.

As shown in FIG. 4, when the jam release cover 262 is rotated to be released from the main body unit 261, the idle gear 265 is separated from the cutter shaft gear 267 and the clutch 268, and the cutter shaft gear 267 and the clutch 268 are separated from each other. The drive connection between them is released. Therefore, the cutter shaft gear 267 does not rotate to drive from the drive source.
When the jam release cover 262 is opened, the cutter shaft gear 267 is restricted from rotating by a detent lever 276 as shown in FIG.

  At this time, the cutter shaft gear 267 is pressed by the detent lever 276 biased by the spring 277, and the contact surface 276b of the detent lever 276 contacts the flat portion 275a of the cam 275 of the cutter shaft gear 267. Therefore, the motor does not rotate unless a predetermined torque is exceeded.

  However, when the jam release cover 262 is opened, the idle gear 265 receives the idling torque of the clutch 268, and the idling torque received by the idle gear 265 exceeds a predetermined torque for rotating the cutter shaft gear 267. The cutter shaft gear 267 rotates and the rotary blade 263 shown in FIG. 5A rotates.

  The idling torque of the clutch 268 is a torque required to rotate the gear of the clutch 268 when the clutch 268 is disconnected from the drive source. Therefore, when the jam release cover 262 is opened, the idle gear 265 engaged with the gear of the clutch 268 receives the idling torque of the clutch 268, and a force for rotating the engaged cutter shaft gear 267 acts.

  Here, the torque of the idle gear 265 and the torque for rotating the cutter shaft gear 267 will be described.

  A case where the contact surface 276b of the detent lever 276 is in contact with the circumferential portion of the cam 275 will be described with reference to FIG. 10A is a diagram showing the positional relationship between the clutch 268, the idle gear 265, and the cutter shaft gear 267. FIG. 10B shows the contact surface 276b of the detent lever 276 with the circumferential portion of the cam 275. The contact state is shown.

  As shown in FIG. 10A, when the jam release cover is opened in the direction indicated by the arrow D in the figure, the idle gear 265 engaged with the gear of the clutch 268 receives the idling torque of the clutch 268 and is engaged. A force acts to rotate the cutter shaft gear 267 in the direction indicated by the arrow C in the figure.

  In this embodiment, as shown in FIG. 10B, the cutter shaft gear 267 receives a biasing force of 7.9 N from the detent lever 276, and the detent lever 276 and the cam 275 are moved from the center of the rotary blade shaft 263a. Since the distance LT to the contact portion (the arc portion of the cam 275) is 3 mm, the torque required to rotate the cutter shaft gear 267 (hereinafter referred to as “detent torque”) is 7.9 N × 0. 003 m × 100≈2.4 cNm.

  On the other hand, since the idling torque of the clutch 268 is 1.5 cNm, the cutter shaft gear 267 is not rotated by the idle gear 265.

  As described above, in this embodiment, the detent torque necessary for rotating the cutter shaft gear 267 is set to be larger than the idling torque of the clutch 268.

  Next, the operation of the detent lever 276 when the contact surface 276b of the detent lever 276 is in contact with the flat portion 275a of the cam 275 will be described in detail with reference to FIG. FIG. 9A shows the arrangement of the detent lever 276 of the present embodiment, and FIG. 9B shows the arrangement of the detent lever 276 of the comparative example.

  9A and 9B, the urging force of the detent lever 276 is P. 9A, the distance from the center of the rotation shaft 276a of the detent lever 276 to the contact portion between the detent lever 276 and the cam 275 when the cutter shaft gear 267 rotates in the rotation direction indicated by the arrow B in FIG. 9B, from the center of the rotation shaft 276a of the detent lever 276 to the contact portion between the detent lever 276 and the cam 275 when the cutter shaft gear 267 rotates in the rotation direction indicated by the arrow B in the drawing. Let the distance be L + x. Note that X> 0.

As shown in FIG. 9A, in this embodiment, the detent lever 276 is disposed in the upstream region Ja so that the contact surface 276b of the detent lever 276 that is in surface contact with the flat portion 275a of the cam 275 is located. Yes.
In this case, the torque necessary for the cutter shaft gear 267 to rotate against the urging force P of the detent lever 276 is (F1 × L) Nm.

  On the other hand, as shown in FIG. 9B, the detent lever 276 is arranged in the downstream region Jb so that the contact surface 276b of the detent lever 276 that is in surface contact with the flat portion 275a of the cam 275 is located. In this case, the torque necessary for the cutter shaft gear 267 to rotate against the urging force P of the detent lever 276 is (F2 × (L + x)) Nm.

  Therefore, in this embodiment, the distance between the force point that applies force to the detent lever 276 and the center of the rotation shaft 276a of the detent lever 276 is shorter than that of the comparative example. The force F1 required to rotate the cutter shaft gear 267 against P is (L + x) / L times the force F2 of the comparative example, and the force required to rotate the cutter shaft gear 267 increases. Yes.

  As described above, the detent lever 276 is disposed in the upstream region Ja so that the contact surface 276b of the detent lever 276 that is in surface contact with the flat portion 275a of the cam 275 is positioned, so that it rotates with inertia when the clutch is demagnetized. It is possible to suppress the cutter shaft gear 267 from rotating due to the clutch gear.

  For example, as shown in FIG. 11A, in this embodiment, the force F1 required to rotate the cutter shaft gear 267 is 5.1 N, and the detent lever 276 and the cam 275 from the center of the rotary blade shaft 263a. Since the distance La to the abutment portion is 5.2 mm, the detent torque required to rotate the cutter shaft gear 267 is 5.1 N × 0.0052 m × 100≈2.7 cNm.

  On the other hand, since the idling torque of the clutch 268 is 1.5 cNm, the cutter shaft gear 267 is not rotated by the idle gear 265.

  In addition, as shown in FIG. 11B, in the comparative example, the force F2 required to rotate the cutter shaft gear 267 is 2.4 N, and the detent lever 276 and the cam 275 are moved from the center of the rotary blade shaft 263a. Since the distance Lb to the contact portion is 5.2 mm, the detent torque required to rotate the cutter shaft gear 267 is 2.4 N × 0.0052 m × 100≈1.3 cNm.

  On the other hand, since the idling torque of the clutch 268 is 1.5 cNm, the cutter shaft gear 267 is rotated by the idle gear 265.

  As described above, in this embodiment, the detent torque necessary for rotating the cutter shaft gear 267 is set to be larger than the idling torque of the clutch 268. Therefore, when the jam release cover is opened, the cutter shaft gear 267 It can suppress that it rotates, and it can suppress that the rotary blade 263 of the cutter unit 26 shown in FIG. 5 rotates.

  In this embodiment, the idle gear 265 contacts or separates from the cutter shaft gear 267 as the jam release cover 262 rotates. However, the present invention is not limited to this, and the idle gear 265 is not limited to the cutter shaft gear 267. As long as it contacts or separates from the gear 267, it may contact or separate from the cutter shaft gear 267 on the main unit 261 side.

  Further, as shown in FIG. 8, the cutter shaft gear 267 is disposed in the upstream region Ja so that the abutment surface 276 b of the detent lever 276 that is in surface contact with the flat portion 275 a of the cam 275 is positioned. Can be prevented from rotating.

  In this embodiment, as shown in FIG. 8, the rotation shaft 276a of the detent lever 276 is disposed below the horizontal line H passing through the center of the rotation blade shaft 263a. 12, the rotation shaft 276a of the detent lever 276 may be disposed above the horizontal line H passing through the center of the rotation blade shaft 263a.

  When the rotating shaft 276a of the detent lever 276 is disposed above the horizontal line H passing through the center of the rotating blade shaft 263a, the cam 275 can be pressed by the weight of the detent lever 276, and a load can be applied to the rotation of the rotating blade.

  As described above, in this embodiment, the detent torque required for rotating the cutter shaft gear is set to be larger than the idling torque of the clutch, so that when the jam release cover is opened, the standby position The effect that it can suppress that the rotary blade of the cutter unit stopped at the same time rotates is acquired.

Therefore, when the release cover as the lid member is closed with respect to the apparatus main body, the rotating blade of the cutter unit as the cutting member is prevented from coming into contact with the counter blade, and the rotating blade is damaged. The effect that it can suppress is acquired.
Moreover, the effect that the rotary blade of the cutter unit can be stopped with high accuracy is obtained.

  Although the present embodiment has been described as a direct transfer type image forming apparatus that has three image forming units and transfers a toner image to roll paper conveyed by a transfer belt by the image forming unit, the present invention is not limited to this. Instead of this, an intermediate transfer type image forming apparatus for transferring a toner image onto a roll paper via an intermediate transfer belt may be used.

  Further, instead of an image forming apparatus having three image forming units, an image forming apparatus having one or two image forming units or an image forming apparatus having four or more image forming units may be used.

  Further, although the image forming apparatus has been described as a roll paper printer, the present invention is not limited thereto, and may be a copier, a facsimile machine, a multifunction peripheral (MFP) or the like.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Roll paper storage part 22, 23, 24, 25, 33 Pair of conveyance rollers 26 Cutter unit 27, 27a, 27b, 27c Image forming part 30a, 30b, 30c Photosensitive drum 31a, 31b, 31c Transfer roller 32 Fixing device 60 Developing unit 261 Main unit 262 Jam release cover 263 Rotating blade 264 Opposing blade 265 Idle gear 267 Cutter shaft gear 268 Clutch 273 Sensor 274 Light shielding plate 275 Cam 276 Detent lever 277 Spring

Claims (9)

An image forming apparatus having a cutting unit for cutting a print medium,
The cutting part is
A main body having a rotary blade;
An opposing blade for cutting with a print medium sandwiched between the rotary blade,
Have
The main body is
A rotary blade shaft gear attached to the rotary shaft of the rotary blade;
A load member for applying a load to the rotation of the rotary blade;
Drive transmission switching means for switching connection or disconnection of drive transmission to the rotary blade shaft gear;
Have
The drive transmission switching means has a gear, and transmits drive to the rotary blade shaft gear via a driven gear that contacts or separates from the rotary blade shaft gear;
2. An image forming apparatus according to claim 1, wherein a torque required for rotating the rotary blade shaft gear is set to be larger than a torque required for rotating the drive transmission switching means in the cut state. The image forming apparatus according to claim 1.
The cutting part is
Having the opposed blade, provided rotatably on the main body, and having an opening / closing portion that can be opened and closed with respect to the main body,
The rotary blade shaft gear is configured to transmit drive from the drive transmission switching means to the rotary blade shaft gear via the driven gear as the opening / closing portion rotates. The image forming apparatus according to claim 2.
The image forming apparatus according to claim 1, wherein the open / close portion includes the driven gear that meshes with a rotary blade shaft gear and a gear of a drive transmission switching unit when closed with respect to the main body portion. The image forming apparatus according to claim 2 or 3,
The image forming apparatus according to claim 1, wherein the opening / closing portion includes the driven gear that is separated from the rotary blade shaft gear when the opening / closing portion is opened with respect to the body portion. The image forming apparatus according to any one of claims 2 to 4,
The main body is
Having a cam attached to the rotary shaft of the rotary blade;
The image forming apparatus, wherein the load member abuts on the cam and applies a load to the rotation of the rotary blade. The image forming apparatus according to claim 5.
The cam has a flat portion,
The image forming apparatus, wherein the load member has a contact surface in surface contact with the flat surface portion, and the contact surface is urged by the flat surface portion. The image forming apparatus according to claim 5 or 6, wherein:
The load member is provided to be rotatable around a rotation axis,
The contact portion between the load member and the cam is arranged upstream when the upstream and downstream in the rotation direction of the rotary blade are separated by a straight line passing through the rotary shaft of the load member and the rotary shaft of the rotary blade. An image forming apparatus. The image forming apparatus according to claim 7.
The image forming apparatus according to claim 1, wherein the rotation shaft of the load member is disposed below a horizontal line passing through the rotation shaft of the rotary blade. The image forming apparatus according to claim 7.
The image forming apparatus according to claim 1, wherein the rotation shaft of the load member is disposed above a horizontal line passing through the rotation shaft of the rotary blade.

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