JP2002003001A - Sheet conveying device and recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet conveying device capable of conveying a sheet with a folding tendency without producing the skewing defect and the rewinding defect. SOLUTION: This sheet conveying device separately conveying each sheet is provided with a feeding means for separately feeding each sheet and a conveying roller 620 and a pinch roller 625 for conveying the fed sheet. The friction coefficient in the conveying roller 620 at an end area contacting with both ends in the sheet width direction is kept smaller than the friction coefficient at a central area contacting with a central area in the sheet width direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus for separating and conveying sheets one by one and a recording apparatus having the same.

[0002]

2. Description of the Related Art In a recording apparatus such as a copying machine or a printing apparatus, a feeding cassette in which recording sheets are stacked and set is loaded, and sheets are separated and fed one by one from the cassette by a feeding mechanism to record. It is configured to do so.

Here, when the sheet is fed from the feeding cassette, the sheet is generally separated one by one by a separating claw provided on the cassette, but this may cause the recording sheet to bend. FIG. 7 is an exaggerated representation of this bending habit. FIG. 7 shows a state in which the recording sheet S is fed in the direction of arrow F, and a bending habit S3 which slightly bends downward is attached to both ends of the leading end of the recording sheet in the traveling direction by the separation claw of the cassette. Is shown.

It is inevitable that such bending habits occur at a certain probability depending on the surrounding temperature and humidity environment and the type, thickness and stiffness of the recording sheet.

FIG. 8 shows the situation when a recording sheet having such a curl is sent to the recording means (printer unit 100).

In the printer unit 700, the conveyed recording sheet S is nipped and conveyed by a conveying roller 701 and a pinch roller 702 urged by an appropriate spring force. After that, the recording head cartridge 703
The print head cartridge is transported to a position
Reference numeral 703 indicates that the recording is performed by discharging ink on a recording sheet by scanning in a direction perpendicular to the sheet surface.

[0007]

The conveying roller 701 is a reference for conveying the recording sheet, and it is necessary to prevent the recording sheet from slipping, so that the coefficient of friction is set very high.
When the recording sheet having the downward curl is made to make a U-turn and guided to the print unit, the curl becomes upward, but when the leading end of the sheet hits the circumference of the conveying roller 701, as described above. The nip portion (the contact point between the transport roller 701 and the pinch roller 702), which is the position where the sheet should be guided because the surface is configured with a high friction coefficient
It happens that you do not slip.

Generally, when a sheet is fed, the conveying roller 701 is stopped, or the sheet is pushed in from the rear while giving a rotation opposite to the sheet conveying direction in the direction of arrow G. Means for ensuring that the leading edge of the recording sheet is guided to the nip portion is adopted. This improves the accuracy of the cueing amount of the recording sheet by the transport roller and the reliability of eliminating skew.

However, when the corner of the leading end of the recording sheet having a curl as described above abuts on the circumference of the transport roller, the transport roller may be stopped or rotated in a reverse direction. As described above, since it is configured in a surface state having a high friction coefficient, it is often not guided to the nip portion, and thus, there is a possibility that a crawling amount defect or a skew defect may occur.

[0010] The present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a sheet transporting apparatus capable of transporting a sheet without causing skew or cueing even if the sheet has a curl, and a recording apparatus including the sheet transporting apparatus. is there.

[0011]

A typical configuration according to the present invention for achieving the above object is to separate and feed sheets one by one in a sheet feeding apparatus that separates and conveys sheets one by one. Feeding means, and a conveying means for conveying the fed sheet, and has a coefficient of friction in an end region where the vicinity of both ends in the sheet width direction in the conveying means is in contact.
It is characterized in that the coefficient of friction is made smaller than the friction coefficient in the central region where the central portion in the sheet width direction contacts.

In the above configuration, even if a sheet having a curl at both ends in the sheet width direction is inserted into the conveying means, the corner at the front end slides in the end area having a small coefficient of friction, so that the conveying means is not provided. Guided precisely. For this reason, skew correction and cueing are accurately performed. Therefore, when this is used for a recording apparatus, a high-quality image can be obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a recording apparatus according to an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment] A first embodiment will be described with reference to FIGS. Here, first,
The overall configuration of the recording apparatus will be described, and then the sheet transport configuration will be described.

<< Overall Configuration of Recording Apparatus >> The recording apparatus according to the present embodiment is a serial type ink jet recording apparatus, and a detachable disposable type recording head is used as a recording head used in the recording apparatus. .

FIG. 1 is a perspective view showing the appearance of a recording apparatus.
FIG. 2 is a right sectional explanatory view showing a sheet conveying path of a recording sheet of the recording apparatus.

First, the basic configuration of the recording apparatus will be described with reference to FIGS. In FIG. 1, reference numeral 101 denotes a base (bottom case), which together with the main case 102 constitutes a housing and a chassis of the recording apparatus main body.

Reference numeral 101a denotes a sheet remaining amount display window, which displays the remaining amount of recording sheets stacked on the feeding cassette 201.

Reference numeral 102a denotes a selection switch which has a configuration capable of selecting two types of modes "A / B" corresponding to the specifications of a device (computer or set-top box (STB), etc.) for sending data to the recording apparatus. Has become.

A recording sheet discharge section 102b is provided above the feed cassette 201, and three ribs 102c (three) are discharge receiving ribs installed in the recording sheet discharge section so as to extend in the discharge direction. And 102d (two), the recording sheet is discharged, and the recording sheets discharged thereafter are stocked on the recording sheet discharged earlier.

The feeding cassette 201 is detachably attached to the main body of the recording apparatus, stacks a plurality of recording sheets in the feeding cassette 201, and separates and supplies one recording sheet to the recording apparatus by a feeding mechanism. .

An operation panel 104 includes a power switch 104.
a, a reset switch 104b, a power supply display 104d, a data transfer display 104e, an error display 104f, and an ink remaining amount display for displaying the ink remaining amount for each of the black ink / color ink, and 104c is a black ink remaining amount. Two are provided in the display, and two 104g are provided in the color ink remaining amount display. For each color, "non-lighting", "only one lighting", and "two lighting" are provided according to the amount of ink used. A display mode of three stages is provided to express the remaining amount of ink, and when there are two types of tank capacities, the meaning of the display is made different depending on the respective capacities.

Reference numeral 105 denotes a discharge cover, which covers the above-described recording sheet discharge section 102b in which the recording sheets discharged from the printer are stocked, and is detachably attached to the main case 102. Most of the area on the upper surface is substantially flat, and is configured to be substantially flush with the upper surfaces of the main case 102 and other components.

A plurality of ribs are provided on the back surface of the discharge cover 105 in the sheet conveyance direction, and when the discharged recording sheet curls upward, the ribs guide the conveyance of the recording sheet.

Reference numeral 106 denotes an access cover. When a disposable type recording head cartridge or ink tank according to the present embodiment is newly attached or replaced, the access cover 106 is unlocked by the access cover lock 107 and the access cover 106 is opened. To perform the replacement work.

The access cover 106 is provided with a lever portion 106a as shown in FIG.
When the cover 06 is opened, the access cover 106 is turned on by turning the switch of the cover switch 501 through the cover arm 500 rotatably attached to the printer unit 600 as recording means.
The open state is recognized. And
The carriage is automatically moved to the cartridge replacement position after a lapse of a predetermined time after detecting the opening of the access cover 106, and when it is detected by the above means that the access cover 106 has been closed, the carriage is moved to the predetermined position (home position). Position or recovery position)
Has a sequence for automatically moving the carriage.

In FIG. 2, reference numeral 114 denotes a sheet guide, which is a member constituting a recording sheet conveyance path described later, and is attached to the printer unit 600.

Reference numeral 109 denotes a U-turn cover, which is a member constituting a recording sheet transport path, and when the recording sheet is jammed in the recording sheet transport path for some reason (at the time of a jam), the U-turn cover 109 is provided. Open and remove the jammed recording sheet.

Reference numeral 110 denotes a discharge tray.
The recording sheet discharged from the
A sheet support (auxiliary) member for preventing the recording sheet from falling off from the apparatus main body (front side) when discharged to the apparatus 102b, and is usually stored in the apparatus main body. It is pulled out from the main body and used.

Then, an image is recorded by a recording means on a recording sheet conveyed by a sheet conveying device to be described later. (Recording Means) FIG. 3 is an exploded perspective view of the printer unit 600 viewed from the discharge side. This apparatus is provided with a replaceable color ink tank 603a and a black ink tank 603b.
Is provided with a carriage 604 for detachably holding a recording head cartridge 601 on which is mounted. This carriage 6
04 is a guide shaft 606 and a guide rail 6 fixed at both ends to the printer frame 605 and arranged in parallel with each other.
At 07, the recording sheet S is supported so as to be slidable in a main scanning direction perpendicular to the transport direction of the recording sheet S and parallel to the surface of the recording sheet.

The guide shaft 606 is a solid shaft having a smooth surface, and has a groove at one end for fixing it to the printer frame 605.

The carriage 604 is mounted on the printer frame 6.
A drive pulley 610, which is driven to rotate by a carriage motor 608 fixed to 05, is slidable in a direction parallel to the guide shaft 606, and supported by a printer frame 605 via a spring (not shown) so as to be rotatable. Is coupled to one portion of the belt 612 looped around the idler pulley 611, and by driving the carriage motor 608,
The belt 612 is driven, and the carriage 604 is
It is configured to reciprocate in the above direction along the 606 and the guide rail 607. In the present embodiment, the belt 612 is provided with a belt stopper formed of a urethane-based flexible member, and the shaft-shaped part of the belt stopper rotates on the bearing of the carriage 604 within a minute range.・ Slidably fixed.

The home position sensor 613 for detecting the position of the carriage 604 by detecting the passage of the carriage 604, the print head cartridge 601
And a flexible cable 614 for transmitting an electric signal from the main board.

The recording means performs one-line recording on the conveyed recording sheet by discharging the ink downward according to the recording signal by the recording head cartridge 601 in synchronization with the reciprocal movement of the carriage 604. That is, the recording head cartridge 601 generates a fine liquid ejection port (orifice), a liquid path, and an energy action section provided in a part of the liquid path, and generates droplet forming energy to act on the liquid in the action section. Energy generating means.

As an energy generating means for generating such energy, a recording method using an electromechanical transducer such as a piezo element, or irradiation of electromagnetic waves such as a laser to generate heat,
A recording method using energy generating means for discharging droplets by the action of the heat generation, or a recording method using energy generating means for discharging liquid by heating the liquid with an electrothermal converter such as a heating element having a heating resistance. and so on.

Among them, a recording head used in an ink jet recording method for discharging a liquid by thermal energy has a high density of liquid discharge ports for discharging a recording liquid to form discharge droplets. Therefore, high-resolution recording can be performed. Among them, a recording head using an electrothermal transducer as an energy generation source can easily be made compact, and has the advantages of IC technology and micro-machining technology, which have recently made remarkable progress in technology in the semiconductor field and markedly improved reliability. This is advantageous because it can be used for two reasons, high-density mounting is easy, and the manufacturing cost is low. Further, when one-line recording is performed by moving the recording head cartridge 601, the recording sheet S is conveyed by one line on the recording sheet S in the conveying direction by the sheet feeding motor, and the recording of the next line is performed.

It should be noted that a recovery mechanism is provided for removing ink or foreign matter accumulated in the nozzles of the recording head cartridge 601 by suction. In addition, an operation called a preliminary ejection operation is performed to remove a small amount of foreign matter and ink remaining in the nozzles even when the recovery operation is performed. In the preliminary ejection operation, the recording head driving for normal printing is performed at a predetermined position other than on the recording sheet. The waste ink discharged by these operations is stored in a waste ink absorber 623 (see FIG. 6) incorporated in the inner wall of the platen 622.

(Control means) The driving of the recording apparatus is controlled by control means shown in the block diagram of FIG. In FIG. 4, reference numeral 301 denotes a controller for executing various programs, including a gate array circuit for performing high-speed arithmetic processing of data, various timers for performing various timing controls,
It has a counter and the like. The ROM 304 stores various reference information such as a control table and setting value information. The MPU 302 is a so-called central processing chip that performs various calculations and the like. 303 is mainly controller and M
This is a RAM used as a work area of the PU. Various calculations and instructions are executed by the controller 301, the MPU 302, the RAM 303, and the ROM 304, and the devices are controlled.
ASF (Auto Sheet Feed) sensor 450, sheet sensor 62
9. The states of the home position sensor 613 and the discharge sensor 630 are used for determining conditions in various controls as necessary. The ASF motor 406 is driven via the ASF driver 305, and the carriage motor 608 is the carriage driver 3
The sheet feed motor 609 is driven via a sheet feed driver 307. The recording head 602 is
The recording operation is executed in response to the output of the gate array circuit of the controller 301.

{Sheet Conveying Apparatus} Next, the configuration of a sheet conveying apparatus that conveys recording to the recording means will be described.
The sheet conveying device conveys the recording sheets stacked and set on the feeding cassette 201 to the recording unit by a feeding unit and a conveying unit.

(Feeding Cassette) FIG. 5 is an overall perspective explanatory view of a feeding cassette 201 according to an embodiment of the present invention. This feeding cassette 201 is configured to be detachable from the apparatus main body, and two substantially horizontal slideable and guided guides on the cassette supporting surface of the apparatus main body when the cassette 201 is attached to and detached from the apparatus main body. Rail 201b is provided.

On the cassette 201, the stacked sheets S
There is provided a pressure plate 202 that urges the feeding roller 112c disposed in the apparatus main body facing the image forming apparatus. Pressure plate 202 is cassette 20
It is rotatably supported by the first pressure plate mounting shaft 201c, and is constantly urged by a coil spring 203 in a direction in which it comes into pressure contact with the feed roller 112c. The surface of the pressure plate 202 is galvanized,
A separation sheet (not shown) for preventing double feeding of the sheet S is provided immediately below the feed roller 112c. This separation sheet is formed of artificial leather, and the friction coefficient μ2 of the separation sheet surface is

Μ1 <μ2 <μ3

Μ1: sheet-to-sheet friction coefficient (about 0.7)

Μ2: Coefficient of friction between sheet and separation sheet (0.9
degree)

Μ3: Coefficient of friction between sheet and feeding roller (2.0
degree)

Is as follows.

The side guide 205 is a member that regulates the non-reference end of the stacked sheets S, and has a sheet size (A
(4, LTR) and variations in sheet cutting in the width direction, etc., are provided slidably on the cassette 201 in the sheet width direction. The regulation of the non-reference end of the sheet S is performed by bringing the guide surface 205a into contact with the non-reference end of the sheet S.

Then, on the downstream side in the transport direction of the reference guide member 201a, a separation claw 207 on the reference side having a predetermined hook amount with respect to the sheet S is rotatably pivoted on the inner surface of the reference side wall of the cassette 201 by an axis. It is supported by. Further, a separation claw 208 on the non-reference side is rotatably supported by a shaft at the downstream side of the side guide 205 in the transport direction.

(Feeding Means) The recording sheet stacked in the feeding cassette 201 is separated and fed to the printer unit 600 by the ASF unit 112 as the sheet feeding means shown in FIG. You.

In the ASF unit 112, a feed roller 112c separates and conveys only the uppermost recording sheet S1 of the stacked recording sheets S. Reference numeral 112a denotes a guide surface forming a feeding path, and the feeding surface is formed by the guide rib 109a and the sheet guide 114 forming the feeding path provided on the U-turn cover 109.

The above-described path takes a substantially U-turn path, and the sheet is conveyed in a direction in which one sheet is taken out from the feeding cassette 201 and conveyed away from the printer unit 600. The recording sheet S is conveyed in the direction of the recording start position in the printer unit 600 by turning the conveying direction by approximately 180 degrees with a smooth curvature by the substantially U-turn-shaped feeding path formed by the feeding path 109a. .

The sheet conveying path ahead of the U-turn path is constituted by a guide surface 114a provided on the sheet guide 114 and a rib 622a provided on a platen 622.
The sheet S is guided to the transport roller 620.

In the ASF unit 112, reference numeral 112b denotes an intermediate roller, and a pinch roller 113 rotatably attached to the base 101 is rotated by an appropriate spring force.
, And rotates following the rotation of the intermediate roller 112b to pinch and convey the recording sheet.

A plurality of recording sheets S are stacked in the feeding cassette 201 and inserted into the main body of the recording apparatus. The feeding roller 112c installed in the ASF unit 112 is rotated counterclockwise in FIG. 2 according to a preset sequence. The recording sheet S1 located on the uppermost surface of the plurality of stacked sheets is rotated by
Sheet conveyance is started at the same time as only one sheet is separated by 207 and 208.

The recording sheet S separated from the feed cassette 201 is further conveyed by the feed roller 112c, and when it reaches the intermediate roller 112b, the intermediate roller 112
The recording sheet S is nipped and conveyed by the pinch roller 113 and the pinch roller 113, and conveys the recording sheet S to the conveying roller 620 via the U-turn feeding path.

(Pickup / separation operation) Here, the sheet separation / feed operation will be specifically described. In the standby state, the half-moon surface of the feed roller 112c is substantially horizontal with the stacked sheets S. ing. Further, the pressure plate 202 and the stacked sheets S on the pressure plate 202 are urged by the coil spring 203 and receive a force in the direction of pressing against the feeding roller 112c, but the rotation of the pressure plate 202 is restricted by the separation claws 207 and 208. ing. At this time, there is a predetermined gap between the half-moon surface of the feeding roller 112c and the stacked sheets S.

When the feed roller 112c starts to rotate in response to the feed command, the arc-shaped outer peripheral surface of the feed roller 112c pushes down the pressure plate 202 and the sheet S on the pressure plate against the bias of the coil spring 203. At this time, a pressing force acts between the sheet S on the pressure plate 202 and the arc-shaped outer peripheral surface of the feeding roller 112c by the bias of the coil spring 203. As a result, a frictional force is generated between the arc-shaped outer peripheral surface of the rotationally driven feeding roller 112c and the uppermost sheet S1.

As described above, since the friction coefficient μ3 between the feeding roller 112c and the uppermost sheet S1 is higher than the friction coefficient μ1 between the sheets, the uppermost sheet S1 is caused by the frictional force. Conveyed in the rotation direction. At this time, as shown in FIG. 2, both corners of the leading end of the uppermost sheet S1 abut against the abutting portions of the separation claws 207 and 208 by the same predetermined amount, and as the central portion of the uppermost sheet S1 is conveyed. By forming almost the same loop S2 on the left and right,
The separation from the second and lower sheets S is encouraged. Then, when the loop of the uppermost sheet S1 reaches a predetermined amount or more, the sheet end starts sliding along the oblique sides of the separation claws 207, 208, is pulled out from the separation claws 207, 208, and is conveyed downstream.

At this time, a slight bending habit may remain on the recording sheet due to the loop S2 of the stacked sheets (FIG. 7 shows the bending habit S
3 is shown exaggerated).

In the present embodiment, the transport roller 620 is improved as described later so that the recording sheet having such a curl can be properly transported.

(Conveying Means) The sheet fed by the feeding means is conveyed by the conveying means, during which the image is recorded by the recording means. The transporting means includes a transport roller 620 as a transport rotary body, a pinch roller 625 as a driven rotary body, and the like.

The transport means will now be described.
As shown in FIG. 3, a transport roller 620 and a pinch roller 625 are rotatably attached to the printer unit 600. The conveying roller 620 applies a conveying force to the sheet by driving and rotating in synchronization with the recording operation, and the pinch roller 625 urges the sheet to the conveying roller 620 by an appropriate spring force, and the rotation of the conveying roller 620 The recording sheet is nipped and conveyed by the driven rotation.

The lower side of the sheet conveying surface in the recording area is mainly composed of a platen 622, and the platen 622 is a base.
A box structure is fixedly incorporated into the base 101 and has a gap between the base 101 and the base 101 for accommodating the waste ink absorber 623 (see FIG. 6). By screwing the platen 622 and the base 101 in this state, the warpage of the component alone is corrected, and the rigidity of the device is improved.

On the surface of the platen 622, protruding ribs 622a for reducing a sliding load during conveyance are provided on the recording sheet S.
Are formed in a plurality of rows along the carrying direction of the hologram.

A pinch roller 625 held by a pinch roller holder 624 rotatably mounted on the platen 622 is pressed against the transport roller 620 from below by a spring (not shown), and the transport roller 620 and the pinch roller 625 are pressed. The recording sheet (not shown) sandwiched between the recording sheets is conveyed by driving the sheet feed motor.

The pinch roller 625 has a diameter of the outer peripheral portion for nipping the recording sheet S between the pinch roller 625 and the transport roller 620.
It is almost the same as 0 and slightly smaller, with an outer diameter of 6 mm. Also, the ratio of the outer diameter of the rotating shaft held by the pinch roller holder 624 to the outer diameter of the pinch roller 625 is
1: 7.5 and the shaft diameter is 0.8 mm. Accordingly, since the rotation load is light, the recording sheet S can be conveyed with little loss. Also, since the outer diameter of the pinch roller 625 and the outer diameter of the transport roller 620 are almost the same, it is easy to guide the recording sheet to the contact point (nip) between the pinch roller 625 and the transport roller 620 when feeding.
Further, it is possible to reduce the force for pushing the leading end of the recording sheet into the nip.

The outer peripheral portion and the shaft portion of the pinch roller 625 are both subjected to nickel plating, and are discharged from the recording head cartridge 601 to be corroded by ink mist contained in the inside atmosphere of the apparatus, to prevent the pinch roller holder from being damaged.
Since the wear when sliding between the pinch roller 624 for a long time is reduced, the rotational load of the pinch roller 624 hardly increases even after long-term use.

Reference numeral 626 denotes a discharge roller (two rows), which rotates in synchronization with the transport roller 620 by receiving a driving force from the transport roller 620 via an idler gear row 627.
A spur 628 attached to the guide rail 607 is disposed above the discharge roller 626.
Is pressed against spur 628 from below by a spring (not shown), so that the recording sheet is conveyed while being nipped between discharge roller 626 and spur 628. The spur 628 is a rotator that has a small contact area with the sheet S and does not disturb the ink image even when the sheet contacts the sheet surface on which the ink image is recorded by ink ejection.

The recording sheet S conveyed by the conveying roller 620 is further conveyed in the direction of arrow E in FIG. 2 by the discharge roller 626, and finally on the ribs 102c and 102d serving as the discharge receiving ribs. The sheet is discharged along
The sequentially discharged sheets are stocked on the previously discharged sheets. A recording sheet conveyance path by the series of feeding cassettes 201 described above is indicated by a two-dot chain line 503.

Reference numeral 629 denotes a sheet sensor which is used as means for detecting the position of the leading end of the recording sheet.
2c and the recording sheet S conveyed by the intermediate roller 112b
The arrival of the recording sheet S is detected by the lever being pulled up by the leading end of the recording sheet S. After the detection of the sensor, the recording sheet S is conveyed by a predetermined amount to set the recording sheet S at the recording start position.

Reference numeral 630 denotes a discharge sensor. After confirming that the recording sheet has been completely discharged by the discharge sensor 630, the next recording sheet is fed.

(Conveying Roller) The conveying roller 620 according to the present embodiment is configured so that the coefficient of friction is different between a region where the width direction edge of the recording sheet is in contact and a region where the center portion is in contact. Next, the configuration will be specifically described.

As shown in FIG. 3, a transport gear 621 is fixed to the shaft end of the transport roller 620. This transport roller 620
Is a solid shaft with an outer diameter of 7.561 mm, which is coated with urethane to increase the coefficient of friction with the recording sheet S. The transport roller 620 is driven to rotate by a sheet feed motor via a transport gear 621.

The urethane coating has a large frictional force on the sheet and is used to increase the frictional force between the transport roller 620 and the recording sheet, and has a function of reliably transporting the recording sheet. Then, the conveying roller 620 of the present embodiment has a coefficient of friction in an end region where the vicinity of both ends in the sheet width direction is in contact,
It is configured such that the coefficient of friction is smaller than the friction coefficient in the central region where the central portion in the sheet width direction contacts. That is, the non-painted portion 651 is arranged in an end region where both ends in the width direction of the recording sheet S abut. Since the unpainted portion 651 is not urethane-coated and is made of the material of the transport roller 620, a portion of the smooth metal surface subjected to nickel plating is exposed. The range of the unpainted portion 651 (range of the end region) is set to have a size with a margin in a region where the corners of the leading ends of both A4 and LTR recording sheets, which are the standard size, can contact.

In the present embodiment, the friction coefficient is set such that the friction coefficient μa in the end region is 0.15 to 0.3, and the friction coefficient μb in the central region is approximately 0.7 to 1.5, which is larger than the μa.

Thus, as described above, even if the recording sheet having the bending habit S3 remaining at the leading end is conveyed,
Since the transport roller 620 to which the bending habit S3 abuts has a metal surface with a very small frictional force, the leading end (corner) of the recording sheet slides and is accurately guided to the nip portion which is a contact point with the pinch roller 625. It has become. This is shown in FIG. Therefore, even if the sheet has a bending habit, the sheet can be conveyed without causing a skew defect or a cueing defect.

In the present embodiment, an example of urethane coating has been described. Alternatively, the surface condition of the conveying roller 620 may be configured by spraying alumina abrasive particles on the surface of the conveying roller or etching the material of the conveying roller 620 itself. It is needless to say that it is possible to make the structure rough, and it is not limited to urethane coating.

In this case, the same effect can be obtained by replacing the area of the non-painted portion 651 with a structure in which the abrasive treatment of alumina is not performed, or in which a smooth surface is formed without etching. available.

The point is that the entire surface is finished with a high coefficient of friction with respect to the sheet, so that the recording sheet is conveyed and the frictional force is reduced only at the portion corresponding to the tip corner of the fixed sheet. Is a requirement, and if this requirement is satisfied, the embodiment is arbitrary.

In this embodiment, the transport rollers 62
The positional relationship between 0 and the pinch roller 625 is such that the transport roller is disposed above, but the reverse may be adopted, that is, the transport roller may be disposed below.

In the above-described embodiment, an example in which the sheet conveying device is used as a recording device has been described. However, the above-described sheet conveying device is not limited to the recording device, and for example, separates and feeds a sheet document and reads it by a reading unit. The present invention can be suitably used even in a reading device such as a scanner, and in such a case, it is possible to accurately convey a document having a curl.

[0082]

The present invention is constructed as described above.
Even if a sheet having a curl at both ends in the sheet width direction is inserted into the conveying means, the front end corner slides on the end area having a small friction coefficient and is guided to the conveying means accurately. For this reason, skew correction and cueing are accurately performed. Therefore, when this is used for a recording apparatus, a high-quality image can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory perspective view of an external appearance of a recording apparatus.

FIG. 2 is an explanatory right sectional view showing a sheet conveyance path of a recording sheet of the recording apparatus.

FIG. 3 is an exploded perspective view of the printer unit viewed from a discharge side.

FIG. 4 is a block diagram of a control unit.

FIG. 5 is an overall perspective explanatory view of a feeding cassette.

FIG. 6 is an explanatory diagram illustrating a state in which a sheet is guided to a nip portion between a conveyance roller and a pinch roller.

FIG. 7 is an explanatory perspective view of a sheet having a bending habit;

FIG. 8 is a diagram illustrating a state in which a sheet having a curl is fed to a conventional recording apparatus.

[Explanation of symbols]

 S: Recording sheet 101: Base 101a: Sheet remaining amount display window 102: Main case 102a: Selection switch 102b: Recording sheet discharge unit 102c, 102d: Rib 104: Operation panel 104a: Power switch 104b: Reset switch 104c: Black ink Remaining display 104d Power display 104e Data transfer display 104f Error display 104g Display of remaining color ink 105 105 Discharge cover 106 Access cover 106a Lever 107 Access cover lock 109 U-turn cover 109a Guide rib 110: discharge tray 112 ... ASF unit 112a ... guide surface 112b ... intermediate roller 112c ... feed roller 113 ... pinch roller 114 ... sheet guide 114a ... guide surface 201 ... feed cassette 201a ... reference guide member 201b ... rail 201c ... shaft 202 … Pressing plate 203… Coil spring 205… Side guide 205a… Guide surface 207,208… Separating claw 301 ... Controller 302 ... MPU 303 ... RAM 304 ... ROM 305 ... ASF driver 306 ... Carriage driver 307 ... Sheet feed driver 406 ... ASF motor 450 ... ASF sensor 500 ... Cover arm 501 ... Cover switch 600 ... Printer unit 601 ... Recording Head cartridge 602 ... Recording head 603a ... Color ink tank 603b ... Black ink tank 604 ... Carriage 605 ... Printer frame 606 ... Guide shaft 607 ... Guide rail 608 ... Carriage motor 609 ... Sheet feed motor 610 ... Driving pulley 611 ... Idler pulley 612 ... Belt 613… Home position sensor 614… Flexible cable 620… Transport roller 621… Transport gear 622… Platen 622a… Rib 624… Pinch roller 625… Pinch roller 626… Discharge roller 627… Idler gear train 628… Spur 629… Sea Sensor 630… Discharge sensor 651… Unpainted part

Claims (5)

[Claims] 1. A sheet feeding apparatus for separating and conveying sheets one by one, comprising: feeding means for separating and feeding sheets one by one; and conveying means for conveying the fed sheets. A sheet conveying device, wherein a coefficient of friction in an end region of the conveying unit where the vicinity of both ends in the sheet width direction contacts is smaller than a friction coefficient in a central region where a center portion of the sheet width direction contacts. 2. The transporting device according to claim 1, wherein the transporting unit includes a transporting rotary body that is driven to rotate to apply a transporting force to the sheet, and a driven rotary body that presses the sheet against the transported rotary body and is driven to rotate. 2. The sheet conveying device according to claim 1, wherein a friction coefficient in an end region of the rotating body in contact with both ends in the sheet width direction is smaller than a friction coefficient in a central region in contact with a center portion in the sheet width direction. apparatus. 3. A structure according to claim 1, wherein said central region is coated with a high friction coefficient so as to have a higher friction coefficient than said end region not coated. The sheet conveying device as described in the above. 4. The sheet conveying device according to claim 1, wherein the sheets are separated one by one by a separation claw. 5. A recording apparatus that conveys a sheet and records an image, wherein: the sheet conveying apparatus according to claim 1; and an image on a sheet conveyed by the sheet conveying apparatus. A recording device comprising: recording means for forming.