JP2012012180A - Sheet conveying device, and image forming apparatus - Google Patents

Abstract

Disclosed is a static elimination device that eliminates static electricity by connecting or disconnecting a conveying roller and ground without adding a dedicated drive source or static elimination member, and suppressing noise and wear.
A conveying roller for conveying a sheet by rolling on the sheet is moved between a pressure-contact position where the operation roller is in pressure contact with the sheet and a standby position separated from the sheet. Configure to move. An elastic member 3 made of a conductive material is attached to the operation mechanism so as to be connected to the ground and to apply a biasing force to the transport roller 1. A portion 3b in which one end portion of the elastic member 3 is extended is configured so that it can be electrically contacted and grounded only when the transport roller 1 is in a standby position.
[Selection] Figure 7

Description

  The present invention relates to a sheet conveying apparatus and an image forming apparatus having a charge eliminating function for removing static electricity generated in a conveying member accompanying sheet conveyance.

  In a paper transport device of an image forming apparatus, a transport roller in which a material having a high coefficient of friction, particularly rubber or urethane, is attached to a shaft portion made of metal in a skewered manner is widely used as a transport member for stably transporting paper. It has been. This transport roller is rotationally driven by a drive motor.

  In this image forming apparatus, the leading end of the sheet is separated from the sheet cassette as a sheet feeding operation, and then the sheet is conveyed to the printing unit as a sheet conveying operation.

  During this transport operation, the paper and the transport roller are transported by the frictional force of the surface of the paper and the transport roller when the transport roller rolls on the paper while being elastically pressed. For this reason, in the paper transport device, if the pressure contact force between the transport roller and the paper is set high, the transport force can be increased, and more stable transport performance can be obtained.

  However, in such a paper transport device, when the paper cassette is left in the image forming apparatus for a long period of time, the paper and the transport roller are deformed by the pressure contact force. Further, since the pressing force is applied to the paper cassette as a reaction, there is a problem that it is difficult for the user to load the paper cassette.

  Therefore, in the paper transport device, the transport roller is configured to be movable so that the position of the pressure contact state and the retracted state can be switched by adding a drive source such as an actuator, and the transport roller is used only when transporting the paper. There are some which are made to press contact.

  An image forming apparatus equipped with such a sheet conveying device that switches the position of the conveying roller is usually provided with a mode for continuously executing a plurality of prints. When the continuous printing mode is executed in such an image forming apparatus, the paper feeding operation and the paper transporting operation are repeated a plurality of times over a long time according to the number of prints. Along with this paper transport operation, static electricity is accumulated between the paper and the transport roller due to frictional charging. If static electricity is accumulated while the printing operation is repeated a plurality of times, the device may malfunction due to electrical noise. In addition to this, the accumulated static electricity triggers the sheets to attract each other, causing an error in the paper feeding operation, or the surrounding dust such as paper dust adheres to the rubber part and the conveyance force decreases. . In addition, for example, when the transport roller is exposed, for example, when the paper cassette is replaced, it is necessary to be careful because a conductor comes into contact with the transport roller where static electricity remains.

  In view of this, some of these paper transport devices use conductive ball bearings or oil-impregnated metals as bearings for the transport rollers. In the paper transport device using the conductive bearing, the cost is higher than that in the case of using the resin bearing without conductivity, and the frame itself holding the conductive bearing is also a conductive member. It was necessary to configure and connect to ground.

  In addition, there is a paper conveyance device that directly contacts a metal part for the purpose of charge removal with the shaft portion of the conveyance roller. In the paper conveying apparatus configured as described above, the shaft portion of the conveying roller that is rotationally driven and the metal component for charge removal are always in contact with each other, so that abnormal noise is generated or worn. The service life of metal parts is shortened.

  Therefore, the conventional paper transport device is provided with a recognition means such as a thermohygrometer for recognizing the charge of the paper and a contact / separation means for separating the charge removal member according to the determination result, and the charge removal member is always in contact. Instead, it is separated from the conveying roller when it is unnecessary. Thus, there has been proposed a device that realizes a long life of the static elimination member (see, for example, Patent Document 1).

  Further, the paper is cut by a moving blade that moves in a direction perpendicular to the paper transport direction and a fixed blade that is disposed on the opposite side of the paper. Then, there has been proposed a device in which a neutralizing brush that is in contact with or non-contacting with the platen roller is provided, reciprocating in synchronization with the moving blade, and neutralizing the entire width of the platen roller (for example, Patent Document 2). reference).

JP-A-7-57060 JP-A-5-104494

  However, in the paper sheet processing apparatus disclosed in the above-mentioned Patent Document 1, in addition to a recognition member such as a temperature / humidity meter, a dedicated member for charge removal such as a charge removal brush is required, and a dedicated member for separating the charge removal member is required. An approach / separation mechanism is required. Therefore, in the configuration of this paper sheet processing apparatus, the number of parts increases, the structure becomes complicated and expensive.

  Further, the paper cutting device disclosed in Patent Document 2 is premised on a device provided with a cutter, and a configuration in which the cutter movable blade and the conveyance roller are provided in close proximity is essential. . For this reason, it is difficult to apply the structure for removing electricity to the sheet conveying apparatus and the image forming apparatus, and there is a restriction on the layout when the electricity removing mechanism is arranged in the apparatus. Further, the configuration of the paper cutting device requires a member dedicated to static elimination such as a static elimination brush, which increases the number of parts, makes the structure complicated, and becomes expensive.

  An object of the present invention is to make it possible to reliably remove static electricity without adding a dedicated drive source or static elimination member, and to suppress the generation of abnormal noise. At the same time, it is an object of the present invention to provide a sheet conveying apparatus and an image forming apparatus that can improve the durability by suppressing the wear of a member for eliminating static electricity, have a small number of components, can be manufactured at low cost.

  In order to achieve the above object, a paper transport device according to the present invention includes a transport roller for transporting a paper, a position in a pressure contact state where the transport roller is pressed against the paper, and a standby state separated from the paper. And a moving mechanism for moving between the position and the position, the conductive member formed of a conductive material is mounted so as to be connected to the ground, the conductive member It is characterized in that a part of is electrically contacted with a part of the transport roller only when the transport roller is in a standby position.

  According to the present invention, since the configuration for switching between the pressure contact state and the retracted state between the paper and the transport roller is used, a dedicated drive source is added to switch between the connection state and the disconnection state of the transport roller and the ground. There is no. According to the present invention, the conveying roller and the ground are disconnected in the pressure contact state, and abnormal noise and wear can be prevented. Further, in the retracted state, the conveyance roller and the ground are in a connected state, and the static electricity accumulated in the conveyance roller can be reliably removed. According to the present invention, the conductive member provided for switching between the pressed state and the retracted state of the sheet and the transport roller is used as the ground. Thereby, in this invention, it is not necessary to provide a static elimination part by adding a static elimination member newly or forming a contact surface from a flame | frame. This makes it possible to connect or disconnect the conveying roller and the ground without adding a dedicated drive source or neutralizing member, and to eliminate the noise and wear while ensuring the neutralization of the conveying roller and a simple and inexpensive device. Can be provided.

1 is a perspective view of a main part of an image forming apparatus according to an embodiment of the present 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 sectional drawing which shows schematic structure of the paper cassette concerning embodiment of this invention. (A) is a perspective view of the image forming apparatus in a loaded state of a paper cassette according to the embodiment of the present invention, and (b) is a perspective view of the image forming apparatus in a removed state of the paper cassette. (A) is sectional drawing which expands and shows a part of schematic structure of the moving means in the retracted state according to the embodiment of the present invention, and (b) shows the movement when the transport roller is in a pressure contact state. It is sectional drawing which expands and shows a part of schematic structure of a means. It is a perspective view which expands and shows a part of schematic structure of the static elimination means with a conveyance roller retracted | retracted state concerning embodiment of this invention. (A) is sectional drawing which expands and shows a part of schematic structure of the paper conveyance means in the retracted state according to the embodiment of the present invention, and (b) is a state in which the conveyance roller is in a pressure contact state. FIG. 3 is an enlarged cross-sectional view illustrating a part of a schematic configuration of a sheet conveying unit. 1 is a block diagram illustrating a functional configuration of an image forming apparatus according to an embodiment of the present invention. It is a flowchart which shows a series of processing operation | movement concerning embodiment of this invention.

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

  FIG. 1 is a perspective view of a main part of an image forming apparatus according to an embodiment of the present invention, and reference numeral 1 denotes a paper feed roller as a transport roller. The paper feed roller 1 is an active roller composed of a shaft portion 1a made of metal and a rubber portion 1b, and is configured as a unit in which a gear 1c is press-fitted into one end. The gear 1c of the paper feed roller 1 is always connected to a paper feed motor 27 shown in FIG.

  This paper feed roller 1 is driven to rotate by switching to the paper feed direction or the storage direction by controlling the paper feed motor 27 and transmitting the driving force in the required direction via the gear train and the gear 1c.

  In addition, in the perspective view of FIG. 1, reference numeral 2 denotes a resin member, which is a resin excellent in slidability and wear resistance, such as POM, which is unlikely to cause abnormal noise or wear even if it is always in contact with the metal shaft portion 1a. And PBT material.

  As will be described later, the resin member 2 is installed between the shaft portion 1a of the paper feed roller 1 and the shaft portion 50b of the paper feed roller moving motor 5b.

  In the perspective view of FIG. 1, 3 is a torsion spring which is a conductive member. As shown in FIG. 6 described later, the torsion spring 3 includes a movable end 3a and a fixed end 3b formed at both ends of the coil portion 3c.

  The torsion spring 3 is arranged so that a movable end 3a, which is a part of the torsion spring 3, indirectly biases the paper feed roller 1 in a retracting direction corresponding to a substantially downward direction toward FIG. . That is, the paper feed roller 1 that is a transport roller is biased by the torsion spring 3 toward the cam curved surface side (cam gear side) of the cam gear.

  In FIG. 1, reference numeral 4 denotes a frame member connected to the ground. As shown in FIG. 6 which will be described later, the coil member 3c of the torsion spring 3 is attached to the frame member 4 so as to be electrically connected in the inserted state. Thereby, the torsion spring 3 is connected to the ground via the frame member 4.

  Further, the frame member 4 holds main components for the image forming apparatus, such as components for the printing unit, components for the paper transport unit, and components for the cassette locking unit.

  In FIG. 1, 5a is a cam gear for moving the paper feed roller 1, and 5b is a roller moving motor for driving the cam gear 5a to rotate.

  In the perspective view of FIG. 1, reference numeral 6 denotes a paper guide, which is formed of a resin having a characteristic that the sliding resistance with respect to the paper P as a recording material is small (so-called excellent slidability). The paper guide 6 forms a conveyance path for smoothly guiding the leading edge of the paper P separated from the paper cassette 12 by the paper feed roller 1 to a roller pair composed of a capstan roller 8 and a pinch roller 9. .

  The paper guide 6 arranged in this manner is arranged so as to cover the cam gear 5a and cover the fracture surface of the moving means 5 and the frame member 4 at a position close to the torsion spring 3 installed on the frame member 4. The

  The paper guide 6 is provided with a static elimination brush 7 which is a static elimination member for removing static electricity accumulated on the paper P. This neutralizing brush 7 is provided with conductive brushes arranged in a straight line in parallel with the longitudinal direction of the paper feed roller 1 over a width slightly larger than the width of the paper P, and the tip of the brush is the tip of the paper P. It is comprised so that a back surface may be contacted.

  In the perspective view of FIG. 1, 8 is a capstan roller, and 9 is a pinch roller. The capstan roller 8 is an active roller made of metal, and is mainly for carrying a sheet after a sheet feeding operation. The pinch roller 9 is a driven roller that is paired with the capstan roller 8 and is formed of an elastic member. The pinch roller 9 is elastically biased so as to move in the normal direction of the shaft portion of the capstan roller 8. Roll while pressing against 8.

  In FIG. 1, reference numeral 10 denotes a lock member that locks the paper cassette 12 and holds the paper cassette 12 at a predetermined position in the mounting portion in the apparatus. Reference numeral 11 denotes a paper cassette detection sensor which determines whether or not the paper cassette 12 is normally loaded in the apparatus and is regulated at a predetermined position.

  Next, other main components and their roles in the image forming apparatus will be described with reference to the schematic cross-sectional view of the main part of the image forming apparatus in FIG.

  In the schematic cross-sectional view of FIG. 2, reference numeral 12 denotes a paper cassette that holds a continuous belt-like paper P wound around a roller-shaped bobbin 12a. A slit-shaped paper outlet for drawing out the paper P is provided on the outer peripheral surface of the paper cassette 12. The leading end of the separating member 12b is always in pressure contact with the paper P by the bias of the spring member 12c.

  A plurality of types of sizes such as card size, L size, and postcard size are prepared for the paper P, and each is stored in a dedicated or combined paper cassette 12. The user loads a paper cassette 12 of a required size in the apparatus. Then, the lock member 10 locks the paper cassette 12, and the paper cassette detection sensor 11 detects the paper cassette 12.

  In this paper cassette 12, when the paper feed roller 1 is driven to rotate, the paper P rotates with the bobbin 12a, and the separation member 12b scoops up the leading edge of the rotating paper P, and draws it out to the paper outlet.

  2 is a schematic cross-sectional view of FIG. 2, and reference numeral 13 denotes a thermal head as printing means. Reference numeral 14 denotes a platen roller disposed so as to face the thermal head 13 with the conveyance path of the paper P interposed therebetween. An ink ribbon 15a is wound around the supply bobbin 15b in the supply roll storage unit and the take-up bobbin 15c in the take-up roll storage unit. The ink ribbon 15a is provided with yellow (Y), magenta (M), and cyan (C) ink layers and an overcoat (OC) layer side by side for each screen.

  The thermal head 13 includes a heating unit 13a having a plurality of heat generating elements, selectively heats the heat generating elements according to image forming information, and thermally transfers the ink uniformly applied on the ink ribbon 15a to the paper P. To do. The thermal head 13 is composed of an attachment frame 13b and a spring member 13c that can move substantially in the vertical direction. In the thermal head 13, the mounting frame 13 b moves to a predetermined position and presses the heating unit 13 a and the platen roller 14 during the printing operation. In the thermal head 13, the ink ribbon 15a and the paper P are pressed by the urging force of the spring member 13c to perform thermal transfer.

  In the schematic cross-sectional view of FIG. 2, reference numeral 16 denotes a cutter unit for cutting the paper P. 16a is a cutter movable blade, 16b is a cutter fixed blade, and 16c is a cam gear connected to a cutter motor 16d shown in FIG.

  In this cutter unit, the cutter motor 16d rotationally drives the cam gear 16c, and reciprocates the cutter movable blade 16a in the direction perpendicular to the surface of the paper P. Accordingly, the cutter movable blade 16a and the cutter fixed blade 16b are rubbed in scissors to cut the paper P.

  The cutter unit may be constituted by a rotary cutter that reciprocates in the width direction (lateral direction) of the paper P.

  In the schematic cross-sectional view of FIG. 2, reference numerals 17 and 18 denote a discharge roller and a driven roller, which are disposed to face the lower surface and the upper surface of the paper P, respectively, and discharge the cut paper P and sag when the paper P is cut. Plays the role of suppressing flapping.

  As shown in the enlarged cross-sectional view of the main part of the paper cassette in FIG. 3, the paper cassette 12 used in this image forming apparatus has a bobbin 12a in a substantially vertical direction (normal direction) in the housing of the paper cassette 12 toward FIG. ) Is slidably mounted. Further, the bobbin 12a is urged substantially downward in FIG. 3 by the spring member 12d.

  In the paper cassette 12 configured in this manner, as shown in FIG. 2, when the paper feed roller 1 is in the pressure contact position, the paper P wound around the paper feed roller 1 is spring-loaded through the bobbin 12a. 12d is brought into a pressure contact state.

  When the paper P stored in the paper cassette 12 is fed, the feed roller 1 is rotationally driven in the feed direction to roll the entire paper P wound in a cylindrical shape. By this operation, the leading edge of the paper P on the outer peripheral surface of the paper P wound in a cylindrical shape is guided by the separating member 12b and fed to the transport path.

  In this paper cassette 12, the paper P is consumed by the biasing force of the spring member 12d as the paper P is consumed from a state where the winding diameter of the paper P wound in a cylindrical shape is increased and the winding diameter of the paper P is reduced. Then, it is brought into pressure contact with the paper feed roller 1. Therefore, the paper P wound in a cylindrical shape can be appropriately used from the beginning of use to the last roll.

  In this image forming apparatus, as shown in FIGS. 4A and 4B, the sheet cassette 12 is parallel to the direction perpendicular to the sheet conveying direction, that is, the longitudinal direction of the sheet feeding roller 1 from the side of the image forming apparatus. It is configured to be loaded.

  In this image forming apparatus, a lid member 19 that is an exterior cover is attached to the side surface of the image forming apparatus from the viewpoint of few restrictions on the external design and prevention of erroneous operation. The lid member 19 is configured to be openable and closable, and is configured to open when the paper cassette 12 is inserted and removed.

  In this image forming apparatus, a paper cassette detection sensor 11 is mounted. The paper cassette detection sensor 11 detects the paper cassette 12 only when the paper cassette 12 contacts the paper cassette 12 in the loading state shown in FIG. 4A and is turned on normally. The image forming apparatus further includes a lid detection sensor 20 that detects whether the lid member 19 is normally closed.

  In this image forming apparatus, the lid detection sensor 20 determines that there is no risk of the paper cassette 12 popping out carelessly only when the lid member 19 is normally closed, and permits the start of printing. ing.

  In this image forming apparatus, the cover member 19 is opened, and the user carelessly operates the lock member 10, and the paper cassette 12 is unlocked and the paper cassette 12 is pulled out during the printing operation, so that the paper P is damaged. Prevent receiving. Further, in this image forming apparatus, the paper cassette 12 is taken out while the paper feed roller 1 remains in the pressure contact state, and the paper feed roller 1 in which static electricity is accumulated is prevented from being exposed.

  Further, when the lid detection sensor 20 is turned off during the printing operation and it is detected that the lid member 19 is opened, the paper P is immediately stored in the paper cassette 12 or the paper P is cut by the cutter unit 16. Control to eject paper.

  At the same time, before the user takes out the paper cassette 12, the paper feed roller 1 is moved from the press-contact state to the retracted state so that the paper feed roller 1 is controlled to be neutralized, and static electricity is stored. The paper roller 1 is prevented from being exposed.

  In this image forming apparatus, a mechanism for restricting unlocking of the lock member 10 may be added. The mechanism for restricting the unlocking is such that, for example, the engaging claw is engaged with the lock member 10 by a solenoid or the like, and the lock member 10 cannot be operated in the release direction until the retraction of the paper feed roller 1 is completed. Restrict. As a mechanism for restricting unlocking, various means conventionally used for preventing inadvertent operation can be applied.

  With this configuration, after the user opens the lid member 19 and waits until all the controls such as the retraction of the paper feed roller 1 are completed depending on the print size and the print situation, the lock member 10 is released and the paper cassette is released. 12 can be taken out.

  Next, the configuration relating to the movement of the sheet feeding roller and the charge removal in this image forming apparatus will be described with reference to enlarged sectional views showing the main parts shown in FIGS. 5 (a) and 5 (b).

  In FIGS. 5A and 5B, reference numeral 5c denotes a paper feed roller position detection sensor for detecting the stop position of the cam gear 5a, and reference numeral 5d denotes a worm gear that is always connected to the cam gear 5a.

  The cam gear 5 a is disposed so as to be sandwiched between the paper feed roller 1 and the frame member 4. The shaft 5 e that is the rotation center of the cam gear 5 a is disposed at a position shifted from the paper feed roller 1, and the shaft 1 a of the paper feed roller is disposed on the cam curved surface of the cam gear 5.

  The cam gear 5a is mounted so as to rotate around the shaft 5e in synchronization with the rotational drive of the worm gear 5d, which is substantially integrated with the shaft portion 50b of the paper feed roller moving motor 5b. The cam gear 5a is configured as an end face cam, and a cam curved surface is formed in which a cam surface 5f on a higher lift side and a cam surface 5g on a lower lift side are smoothly continuous.

  The cam gear 5a is driven to rotate so that the shaft portion 1a of the paper feed roller slides on the cam curved surface of the cam gear 5, and the retracted position shown in FIG. 5 (a) and the press contact position shown in FIG. 5 (b). Move between.

  At this time, the position of the cam gear 5a is monitored by the sheet feed roller position detection sensor 5c, and the rotation of the sheet feed roller moving motor 5b is driven when it is detected that the cam gear 5a has rotated to a predetermined stop position corresponding to the press contact position. Stop. As a result, the paper feed roller 1 is set at the press contact position shown in FIG.

  On the other hand, when the paper feed roller 1 is moved from the pressure contact position to the retracted position, the cam gear 5a is rotated by the paper feed roller position detection sensor 5c to a predetermined stop position corresponding to the retracted position. Is detected. When the paper feed roller position detection sensor 5c detects it, the rotational drive of the paper feed roller moving motor 5b is stopped. As a result, the paper feed roller 1 is set at the retracted position shown in FIG.

  The above-described configuration using the cam gear 5a for switching between the pressure contact state and the separation state between the paper feed roller 1 and the paper P is suitable for downsizing the apparatus.

  The configuration for switching between the pressure contact state and the separation state between the paper feed roller 1 and the paper P is, for example, the entire paper cassette 12 with respect to the paper feed roller 1 while the position of the paper feed roller 1 is fixed. You may utilize the structure which press-contacts or spaces apart. Furthermore, the configuration for switching between the pressure contact state and the separation state between the paper feed roller 1 and the paper P may be a configuration in which the spring member 12d provided in the paper cassette 12 is pressed against or separated from the bobbin 12a. good.

  Next, a configuration related to the charge eliminating unit in the image forming apparatus will be described with reference to an enlarged perspective view of a main part in FIG. 6 showing a portion of the charge eliminating unit when the sheet feeding roller is in the retracted state.

  The torsion spring 3 shown in FIG. 6 is made of a metal that is a conductive material, for example, a spring material such as a piano wire or a hard steel wire. The torsion spring 3 includes a movable end 3a, a fixed end 3b, and a coil portion 3c.

  A movable end 3 a which is a part of the torsion spring 3 presses the resin member 2. A fixed end 3 b which is a part of the torsion spring 3 is held by a holding member 21 attached to the frame member 4. The coil portion 3c is held so as to contact the inner periphery of the coil holding portion 4a formed by being bent from the frame member 4.

  The frame member 4 is made of a conductive metal, for example, a sheet metal member such as a galvanized steel plate or a stainless steel plate, and is connected to the ground by means such as a cable (not shown). Thereby, the torsion spring 3 can always ensure good conductivity with respect to the ground via the frame member 4.

  In the case of using a metal that is a conductive material for static elimination, the conductive metal is more electrically than the conductive resin compared to the conventional conductive resin. Since a stable resistance value is low, a stable charge eliminating effect can be obtained. Further, when a metal that is a conductive material for static elimination is used, the conductive metal is less expensive than the conductive resin, so that an inexpensive product can be provided.

  Next, the operation related to the charge eliminating means in this image forming apparatus will be described with reference to enlarged sectional views of the main part shown in FIGS. 7 (a) and 7 (b). 7A shows the retracted state of the paper feed roller 1, and FIG. 7B shows the press-contacted state of the paper feed roller 1. FIGS. 5A and 5B described above, respectively. It corresponds.

  In the standby state shown in FIG. 7A, the sheet cassette 12 can be loaded or removed, and each operation is stopped, and the sheet feed roller 1 starts from the sheet P held in the sheet cassette 12. Evacuated.

  In the press-contact state shown in FIG. 7B, the paper feed roller 1 is in a position where it is in press-contact with the paper P held in the paper cassette 12, so that the paper P can be transported and fed or stored. Can be transported. In this transportable state, the bobbin 12a is arranged to face the paper feed roller 1 so as to sandwich the paper P, and is urged in the normal direction of the paper feed roller 1 by the spring member 12d. Yes. Therefore, the paper P held by the bobbin 12a is in a state of being pressed against the paper feed roller 1 by receiving the biasing force of the spring member 12d via the bobbin 12a.

  The resin member 2, which is a part of the moving mechanism for shifting between the standby state and the pressure contact state (conveyable state), has a curved head formed at one end portion of the shaft portion 1a of the paper feed roller. Is engaged. Further, the resin member 2 is loosely inserted into a long hole drilled at the other end so that the shaft portion 50b of the paper feed roller moving motor 5b can rotate and move. As a result, the resin member 2 is installed in an arm member shape between the shaft portion 50b of the paper feed roller moving motor 5b and the shaft portion 1a of the paper feed roller.

  Further, a torsion spring 3 is attached between the frame member 4 and the resin member 2 in order to constitute a moving mechanism for moving the paper feed roller 1 between the standby state and the pressure contact state.

  As described with reference to FIG. 6, the torsion spring 3, which is a torsion coil spring, has the coil portion 3 c held by the coil holding portion 4 a erected on the frame member 4 and the holding member 21 erected on the frame member 4. The fixed end 3b is locked to the. At the same time, the movable end 3 a of the torsion spring 3 is locked to a locking arm portion protruding from the resin member 2.

  In the moving mechanism that shifts between the standby state and the pressure contact state configured as described above, the resin member 2 is centered on the shaft portion 50b of the paper feed roller moving motor 5b by the urging force of the torsion spring 3 as shown in FIG. It is biased to rotate counterclockwise.

  As a result, the resin member 2 rotates the shaft portion 1a of the sheet feed roller with which the free end is engaged and the entire sheet feed roller 1 integral therewith, counterclockwise around the shaft portion 50b toward FIG. Energize to let you.

  As shown in FIG. 5, the sheet feeding roller 1 receiving the urging force of the torsion spring 3 has a cam curved surface 5f of a cam gear 5a for moving the sheet feeding roller by the shaft portion 1a of the sheet feeding roller. The state pressed to 5 g is maintained.

  In the moving mechanism that shifts the paper feed roller 1 configured as described above between the standby state and the pressure contact state, the paper feed roller moving motor 5b is driven and controlled to mesh with the worm gear 5d provided on the shaft portion 50b. The cam gear 5a is rotated. As a result, the shaft 1a of the paper feed roller that is in sliding contact with the cam curved surface of the cam gear 5a is driven, and the paper feed roller 1 is in the standby state shown in FIG. 7 (a) and in the pressure contact state shown in FIG. 7 (b). Transition between positions.

  In addition, the moving mechanism that shifts between the standby state and the pressure contact state described above also serves as a charge removal unit (charge removal mechanism) of the paper feed roller 1.

  For this reason, the fixed end 3b of the torsion spring 3 extends from the position locked by the holding member 21 to the vicinity of the position in the standby state within the movement range of the shaft portion 1a of the paper feed roller. Thereby, when the shaft portion 1a of the paper feed roller reaches the position of the standby state, the shaft portion 1a is in electrical contact with the extending portion of the fixed end 3b, and the static electricity accumulated in the paper feed roller 1 is discharged from the torsion spring 3 and The frame member 4 is configured to be grounded and removed.

  The extended portion of the fixed end 3b of the torsion spring 3 is in contact with the shaft portion 1a of the paper feed roller in the retracted state of FIG. 7A, and the portion of the paper feed roller in the pressure contact state of FIG. 7B. It will be separated from the shaft portion 1a.

  Further, the moving mechanism that shifts between the standby state and the pressure contact state described above also serves as a static elimination means (static elimination mechanism) of the static elimination brush 7 that is a static elimination member.

  As shown in FIG. 7A, the static eliminating brush 7 is attached on the paper transport surface of the paper guide 6 so as to come into contact with the back surface of the paper P drawn from the paper cassette 12. As described above, the sheet guide 6 is made of resin and does not have conductivity, so there is no place for static electricity accumulated in the static elimination brush 7 to escape.

  In the image forming apparatus according to the present embodiment, the sheet feeding roller moving means 5 is disposed between the sheet conveying surface and the frame member 4. It is difficult to remove electricity by direct contact. In addition, when the static elimination brush 7 and the frame member 4 are connected via a conductive cable as in the prior art, the number of parts increases and the cost increases.

  Therefore, in the present embodiment, the movable end 3 a is extended so that the extending portion of the movable end 3 a of the torsion spring 3 is in contact with the lower surface of the static elimination brush 7 when the paper feed roller 1 is in a pressure contact state. .

  In the static eliminator of the static eliminator brush 7 configured as described above, the movable end 3a of the torsion spring 3 is moved from the position in the standby state shown in FIG. It is opened substantially upward to the position of the press contact state shown in (b). 7B, the extension portion of the movable end 3a of the torsion spring 3 is in contact with the lower surface of the static elimination brush 7, and the static elimination brush 7 is connected to the ground to be eliminated. The

  Here, the static elimination brush 7 is in contact with the paper P only when the paper P is on the transport path, so that the static elimination brush 7 is connected to the ground only when the paper feed roller 1 is in the pressure contact state. It's enough. Therefore, the extension portion of the movable end 3a of the torsion spring 3 only needs to be in contact with the lower surface of the static elimination brush 7 and grounded only in the pressure contact state of the paper feed roller 1 shown in FIG.

  In short, the moving mechanism that shifts between the standby state and the pressure contact state described above serves as both the charge removal means (charge removal mechanism) of the paper feed roller 1 and the charge removal means (charge removal mechanism) of the charge removal brush 7.

  The torsion spring 3 in the moving mechanism that shifts between the standby state and the pressure contact state described above is configured such that when the paper feed roller 1 is in the retracted state, the extending portion of the fixed end 3b of the torsion spring 3 is the paper feed roller. 1 is neutralized. On the contrary, when the paper feed roller 1 is in the pressure contact state, the extending portion of the movable end 3 a of the torsion spring 3 acts to neutralize the static elimination brush 7.

  Further, in the image forming apparatus according to the present exemplary embodiment, the moving mechanism that shifts between the standby state and the pressure contact state described above includes a neutralization unit (a neutralization mechanism) for the paper feed roller and a neutralization unit (a neutralization mechanism) for the neutralization brush. The torsion spring 3 is also provided.

  In the extended portion of the fixed end 3 b of the torsion spring 3, the shaft portion 1 a and the fixed end 3 b of the torsion spring 3 are in metal contact even when the contact pressure is relatively small in the retracted state of the paper feed roller 1.

  Further, the paper feed roller 1 is separated from the paper P when in the retracted state, and is in a state where the paper cannot be conveyed.

  Therefore, in the image forming apparatus according to the present embodiment, control is performed so that the paper feed roller 1 is not rotationally driven in the retracted state, but is rotationally driven only in the pressure contact state and during its movement. Thereby, it is possible to prevent the noise or wear from occurring due to the fixed end 3b of the torsion spring 3 being in sliding contact with the shaft portion 1a of the rotating paper feed roller.

  Next, functions of the image forming apparatus in the present embodiment will be described with reference to a block diagram showing a functional configuration of FIG.

  In the block diagram of FIG. 8 showing the functional configuration of the image forming apparatus, reference numeral 22 denotes a main controller as a control unit that controls the entire image forming apparatus. In FIG. 8, reference numeral 11 denotes a paper cassette detection sensor that detects the presence or absence of the paper cassette 12, and reference numeral 20 denotes a lid detection sensor that detects the closed state of the lid member 19.

  In order to prevent malfunction, this image forming apparatus is configured such that the image forming apparatus can shift to a print start operation only when both the paper cassette detection sensor 11 and the lid detection sensor 20 are in the ON state.

  In FIG. 8, reference numeral 23 denotes a paper detection sensor, which is disposed at a substantially intermediate position between the capstan roller 8 and the platen roller 14 on the paper conveyance path. The paper detection sensor 23 detects that the leading end of the paper P drawn from the paper cassette 12 has passed behind the capstan roller 8 during paper conveyance. Reference numeral 24 denotes an ink ribbon detection sensor that detects an identification band applied to the leading end of each color of the ink ribbon 15a. Reference numeral 25 denotes a cutter detection sensor that detects whether the cutter movable blade 16a is in the standby position or the cutting position. The paper feed roller position detection sensor 5c shown in FIG. 8 detects the stop position of the cam gear 5a, which is the moving means of the paper feed roller 1, as described above.

  In FIG. 8, reference numeral 26 denotes a paper feed motor driver for driving the paper feed motor 27. The paper feed motor 27 is connected to the paper feed roller 1, the capstan roller 8 and the like through a rotation mechanism.

  In FIG. 8, 28 is an ink ribbon winding motor driver, which controls the rotation of the ink ribbon winding motor 29. In a state where the ink ribbon 15a is mounted, the take-up bobbin 15c in the take-up roll storage unit and the ink ribbon winding motor 29 are connected via a rotation mechanism. In a state where the ink ribbon 15a is mounted, the ink ribbon winding motor driver 28 controls winding and winding of the ink ribbon 15a. The winding operation of the ink ribbon 15 a by the ink ribbon winding motor 29 is controlled based on the detection result of the ink ribbon detection sensor 24.

  In FIG. 8, reference numeral 30 denotes a thermal head moving motor driver. The driver 30 controls the rotation of the thermal head moving motor 31 that moves the thermal head 13 up and down, thereby operating the thermal head 13 between the printing position and the retracted position.

  In FIG. 8, 32 is a cutter motor driver. The cutter motor driver 32 controls the cutter motor 16d that drives the cutter movable blade 16a to cut the paper P.

  In FIG. 8, reference numeral 33 denotes a paper feed roller movement motor driver that controls the rotation of the paper feed roller movement motor 5b. As described above, the rotation driving of the paper feed roller movement motor 5b by the paper feed roller movement motor driver 33 is controlled based on the detection result of the paper feed roller position detection sensor 5c.

  In FIG. 8, reference numeral 34 denotes a display control unit that controls the display unit 35 including a display screen such as an LCD. The display unit 35 displays image data to be printed or displays a menu for inputting setting data necessary for printing.

  In FIG. 8, an operation unit 36 includes a power switch for instructing ON / OFF of the power of the image forming apparatus, a selection switch for selecting various menus displayed on the display unit 35, and the like.

  Next, a series of processing operations from the start of printing to the end of printing in the image forming apparatus according to the present embodiment will be described with reference to the flowchart of FIG.

  The main controller 22 of the image forming apparatus waits until the user instructs to start printing by pressing the selection button of the operation unit 35 with the roll paper cassette 12 and the ink ribbon 15a mounted on the apparatus main body ( NO in step S1). When the user presses the selection button on the operation unit 35 and inputs a print start command, the main controller 22 starts print processing (YES in step S1).

  When this printing process is started, first, the main controller 22 performs paper cassette detection and lid detection (step S2). Further, the main controller 22 determines whether or not both the paper cassette detection sensor 11 and the lid detection sensor 20 are in the ON state (step S3), so that the paper cassette 12 pops out carelessly during the printing operation. Make sure there is no fear. At this time, if any one of the two sensors is in the OFF state, the main controller 22 stops the printing operation (step S4) and displays error information on the display unit 35 such as an LCD.

  In this image forming apparatus, the main controller 22 must control so as to avoid overlooking the paper cassette 12 in an incomplete state. In this image forming apparatus, once the printing operation is started, the rollers and gears are rotationally driven to operate the printing head. If the lid member 19 is opened and the paper cassette 12 pops out of the apparatus, not only the printing quality is lowered but also inconvenience such as damage to the apparatus may occur. In particular, this type of image forming apparatus that is assumed to be used by an unspecified number of users needs to prevent such a problem. Therefore, the main controller 22 first performs paper cassette detection and lid detection (step S2), and determines that both are ON (step S3).

  Next, the main controller 22 rotationally drives the paper feed roller moving motor 5b (step S5) and performs the pressure contact operation of the paper feed roller 1. Here, the main controller 22 detects the stop position of the cam gear 5a by the paper feed roller position detection sensor 5c (step S6), and determines the pressure contact position of the paper feed roller 1 (step S7) until the paper feed roller moving motor 5b. Is driven to rotate (step S5).

  Next, the main controller 22 performs a paper feeding operation (step S8) after the pressure contact operation of the paper feeding roller 1 is completed. In this image forming apparatus, when the paper feed roller 1 is driven to rotate in the paper feed direction in the state shown in FIGS. 2 and 7B, the leading edge of the paper P wound around the bobbin 12a is moved into the paper cassette 12. Proceed along the circumference. Thereafter, the leading edge of the paper P is scooped up by the separating member 12b. When the paper feeding roller 1 is further rotated in the paper feeding direction, the leading edge of the paper P is guided by the separating member 12b and guided to the paper outlet.

  When the paper feed roller 1 is in a pressure contact state, the extended portion of the movable end 3a of the torsion spring 3 automatically contacts the lower surface of the static elimination brush 7 and is grounded, thereby eliminating the static electricity.

  The paper P thus fed is further transported by the paper feed roller 1 and is sandwiched between a pair of rollers composed of a capstan roller 8 and a pinch roller 9 arranged to face each other. At this time, since the paper feed roller 1 is synchronized with the rotation operation of the capstan roller 8, the paper P is continuously sent out from the paper cassette 12 in the paper feed direction. Thereafter, based on the detection information of the paper detection sensor 23, the main controller 22 controls to send out the paper P necessary for printing one image from the paper cassette 12, to the print start position, and to stop. .

  When the conveyance of the sheet P to the printing start position is completed, the main controller 22 next performs a marker detection operation (step S9). Specifically, the main controller 22 controls the alignment of the head of the ink ribbon 15a in the process of winding the ink ribbon 15a via the ink ribbon winding motor 29 and a gear train (not shown) connected to the motor. Do.

  Here, in the marker detection operation (step S10), the main controller 22 detects a change in the light reception level of the ink ribbon detection sensor 24 including the light projecting unit and the light receiving unit, and the light shielding marker provided on the ink ribbon 15a is detected. The position is determined.

  After this marker detection operation (step S9), the main controller 22 performs a printing operation (step S10) for each of the Y, M, C, and OC screens. This printing operation (step S10) is performed while the paper P and the ink ribbon 15a are conveyed in the upstream direction (the paper P storage direction) from the printing start position to the printing end position.

  First, the main controller 22 controls the thermal head moving motor 31 to move the mounting frame 13b of the thermal head 13 to the press contact position, and presses the heating unit 13a against the platen roller 14.

  Next, the main controller 22 conveys the paper P and the ink ribbon 15a between the thermal head 13 and the platen roller 14 while winding the paper P and the ink ribbon 15a around the winding bobbin 15c to remove slack. The printing end position at this time is a position where the leading edge of the paper P passes between the thermal head 13 and the platen roller 14 facing each other and moves to the paper cassette 12 side (upstream side).

  Next, when the main controller 22 determines that the printing operation has not ended (NO in step S11), the main controller 22 performs control so that the paper P is reversely conveyed (step S12) from the printing end position to the printing start position. At the time of reverse conveyance to the print start position (step S12), the main controller 22 drives the thermal head moving motor 31 again to retract the mounting frame 13b of the thermal head 13 to a predetermined retracted position. Further, the main controller 22 performs control so that the paper P is conveyed backward (step S12) to the printing start position. After that, the main controller 22 controls the remaining screens so that the desired printed image is thermally transferred by sequentially superimposing ink on the paper P while repeating the printing operation (step S10) in the same manner as described above.

  Next, the main controller 22 determines whether or not the printing operation is finished by detecting that printing of the OC, which is the protective layer, is finished (step S11). When the main controller 22 determines that the printing operation has been completed (YES in step S11), the main controller 22 transports the paper P to the cutting position (step S13) and proceeds to the paper P cutting operation (step S14).

  At this time, the sheet P is further conveyed in the sheet discharge direction while being sandwiched between a pair of rollers composed of the sheet discharge roller 17 and the driven roller 18 in the middle of being conveyed to the cutting position (step S13). The cutting position, which is the stop position of the paper P, is a position where the boundary between the printed area and the unprinted area of the paper P matches the cutting position of the cutter unit 16.

  The main controller 22 transports the paper P to the cutting position (step S13), and then performs a cutting operation (step S14) to cut at the boundary between the print portion and the margin. In this cutting operation (step S14), the cutter motor 16d is driven to rotate, and the cutter movable blade 16a is moved to the cutting position. At this time, as described above, the cutter movable blade 16a and the cutter fixed blade 16b cut the paper P by rubbing the upper and lower blades in a scissors shape. The cutter movable blade 16a that has finished cutting the paper P has moved from the non-cutting position (uppermost point) to the cutting position (lowermost point).

  Therefore, the main controller 22 returns the cutter movable blade 16a to the non-cutting position (uppermost point) before cutting again from the cutting position (lowermost point) based on the detection information of the cutter detection sensor 25, and puts it into a standby state. At this time, the cut sheet P is in a state of being sandwiched by a roller pair constituted by the paper discharge roller 17 and the driven roller 18.

  Next, after the cutting operation (step S14), the main controller 22 executes a paper discharge operation (step S15) in order to discharge the cut paper P onto a paper receiver (not shown). When the cut sheet P is discharged (step S15), the sheet P is transported further downstream from the print end position (discharge direction) only by the holding force of the roller pair constituted by the discharge roller 17 and the driven roller 18. It becomes a state to do. The driving force from the paper feed motor 27 is transmitted to the paper discharge roller 17 by a gear train (not shown), and the paper discharge operation is performed by the paper discharge roller 17 in synchronization with the capstan roller 8 (step S15). Is done.

  For this reason, during the paper discharge operation (step S15), the leading edge of the unprinted paper P is also advanced in the paper discharge direction along with the transport operation during paper discharge. As a result, the cut paper P is sent in the paper discharge direction by the paper discharge roller 17 and then pushed out to the front end of the unprinted paper P coming from the upstream side and goes out of the apparatus. The cut paper P discharged in this way is stacked in an orderly manner on a paper tray (not shown), and the paper discharge operation (step S15) is completed.

  After the paper discharge operation (step S15) is finished, the unprinted paper P is pulled out from the paper cassette 12. When the next printing is not performed continuously, the unprinted paper P must be completely stored in the paper cassette 12 and be in a standby state in which the paper cassette 12 is removable. Therefore, after the paper discharge operation (step S15), it is necessary to reversely transport the paper P to the storage position (step S16).

  For this reason, the front end of the paper P is composed of the capstan roller 8 and the pinch roller 9 in the middle of the reverse conveyance (step S16) to the storage position, contrary to the paper feeding operation (step S8). The roller is separated from the roller pair and is transported only by the paper feed roller 1. Furthermore, the paper feed roller 1 continues to rotate, accommodates the paper P in the paper cassette 12, and reversely transports to a position where the front end of the paper P is sufficiently drawn from the paper exit and stops.

  The main controller 22 executes the retracting operation of the paper feed roller 1 after the paper P is completely stored in the paper cassette 12. Here, during the printing operation (step S10), the paper feed roller 1 is always in the pressure contact position where it is in pressure contact with the paper P, and is in a conveying state.

  In this image forming apparatus, when a series of printing operations is completed, the paper cassette 12 can be loaded and unloaded, or even when left for a long time, the paper P and the paper feed roller 1 are prevented from being deformed. It is necessary to retract the roller 1 from the paper P and put it in a standby state.

  Here, as described above, the procedure is almost reversed from the pressing operation of the paper feed roller 1. Specifically, the main controller 22 detects the stop position of the cam gear 5a by the paper feed roller position detection sensor 5c (step S18). Thereafter, the main controller 22 reaches a standby state by controlling the paper feed roller moving motor 5b to be rotationally driven (step S17) until the retracted position of the paper feed roller 1 is determined (step S19). In this standby state, the extending portion of the fixed end 3 b of the torsion spring 3 automatically makes electrical contact with the shaft portion 1 a of the paper feed roller 1 and grounds.

  In this way, the main controller 22 ends a series of processing operations from the start of printing (step S1) to the end of printing (step S20).

  In short, in the image forming apparatus according to the embodiment of the present invention, the sheet feeding roller 1 and the neutralizing brush 7 are automatically neutralized by executing the series of processing operations from the start of printing to the end of printing described above. Can do. Therefore, no special operation is required for neutralizing the paper feed roller 1 and the neutralizing brush 7, so that the control by the main controller 22 is not burdened.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to this embodiment, Of course, a various deformation | transformation and change are possible within the range of the summary.

Claims (9)

A transport roller for transporting the paper;
A moving mechanism for moving the conveyance roller between a position in a pressure contact state where the conveyance roller is pressed against the sheet and a position in a standby state separated from the sheet;
A paper transport device comprising:
A conductive member made of a conductive material is attached so as to be connected to the ground,
A sheet conveying apparatus, wherein a part of the conductive member is configured to be in electrical contact with a part of the conveying roller only when the conveying roller is in a standby position. The conductive member is a torsion spring,
The extension part formed by extending one end of the torsion spring is configured to contact the shaft part of the transport roller only when the extension part is in a standby state position. Paper transport device.   The paper conveying apparatus according to claim 2, wherein the coil portion of the torsion spring is connected to a frame member connected to ground. Disposing a static elimination member at least partially in contact with the paper at a position close to the torsion spring,
The other end of the torsion spring, the conveyor rollers only when it is in the position of the pressure contact state, according to claim 2 or 3, characterized by being configured to electrically contact with the charge removing member Paper transport device.   5. The sheet conveying device according to claim 2, wherein the extending portion that is one end of the torsion spring is a fixed end, and the other end is a free end. 6. The moving mechanism includes a cam gear having a cam curved surface in which a cam surface having a high lift and a cam surface having a low lift are smoothly continuous, and a driving unit that rotates the cam gear.
The rotation of the cam gear by the driving means moves the conveying roller biased toward the cam curved surface side of the cam gear to the position of the pressure contact state or the position of the standby state. The sheet conveying apparatus according to any one of 1 to 5. The moving mechanism includes a cam gear having a cam curved surface in which a cam surface having a high lift and a cam surface having a low lift are smoothly continuous, and a driving unit that rotates the cam gear.
Due to the urging force of the torsion spring, the conveying roller is urged toward the cam gear and is in contact with the cam curved surface,
The rotation of the cam gear by the driving means moves the conveying roller biased toward the cam curved surface side of the cam gear to the position of the pressure contact state or the position of the standby state. The sheet conveying apparatus according to any one of 2 to 5. A sheet conveying device according to any one of claims 1 to 7, comprising:
A mounting portion capable of loading and unloading a paper cassette from the paper transport device;
An image forming apparatus comprising: a control unit that controls the moving mechanism so that the transport roller is moved to a retracted position before the paper cassette is removed from the mounting unit.   The image forming apparatus according to claim 8, wherein the control unit controls the rotation of the conveyance roller to be stopped when the conveyance roller is in a standby state.

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